What are HDI PCBs: How to Design, Fabricate & Assemble?

Q: How much does an HDI board cost compared to standard PCBs?

HDI PCBs typically cost 20-50% more than standard PCBs for basic designs and up to double for complex designs. However, HDI often reduces total system cost by enabling smaller product sizes, fewer layers (a 10-layer standard board can often be made as a 6-8 layer HDI), and improved performance. For high-volume production, the price difference narrows to 10-15%.

Q: What are the typical lead times for HDI PCB assembly services?

Standard HDI PCB manufacturing typically requires 5-8 business days for prototype quantities and 10-15 business days for production volumes. Complex designs with multiple stacked microvias or special materials may require 12-20 days. Express services can reduce prototype delivery to 48-72 hours with a 30-50% premium. Our integrated PCB and assembly facility can deliver complete PCBA solutions in 5-7 days for urgent projects.

Q: How reliable are high density interconnect PCBs in harsh environments?

HDI PCBs can be extremely reliable in harsh environments when properly designed and manufactured. For automotive applications, our HDI boards withstand temperature cycling from -40°C to +125°C for 1000+ cycles.

Q: Can HDI circuit boards handle high-frequency applications?

Yes, HDI PCBs excel in high-frequency applications up to 100 GHz when designed with appropriate materials and techniques.

Q: What are the examples of industrial automation PCBs?

Typical examples include industrial Ethernet gateways for communication protocols (e.g., Ethernet/IP, EtherCAT), programmable logic controller (PLC) mainboards, and human-machine interface (HMI) control panels that require high reliability and real-time processing.

Q: What are the main differences between industrial control PCBA and commercial PCBA?

The core differences are in reliability and durability: industrial PCBA uses components rated for wider temperature ranges and longer lifecycles, employs more robust PCB designs, and adheres to stricter quality standards to withstand harsh factory environments like vibration and humidity.

Q: What should you consider when finding a reliable industrial automation PCBA supplier?

Key considerations are technical capability (experience with industrial protocols and impedance control), quality systems, and operational stability.

Q: What is the difference between vias and microvias?

A via is a plated hole in a PCB used to connect copper layers (through-hole, blind, or buried). A microvia is a very small via, usually laser-drilled in HDI boards. Microvia connects only adjacent layers, enabling higher routing density.

Q: What is the difference between a microvia and a through-hole via?

A microvia is a small laser-drilled via connecting adjacent layers in high-density PCBs. While a through-hole via (plated through-hole) is mechanically drilled and goes through the entire board, connecting all layers.

Q: Can PCB edge plating be used for thermal management of high-power LED boards?

Yes, PCB edge plating improves heat dissipation since more conductive routes for transferring heat are presented. It comes in handy, particularly with high-power LED boards where excessive heat could impact performance as well as lifetime. Good edge plating relocates heat far away from vulnerable parts, yielding thermal reliability. For most first-time projects, lead - free HASL gives the best cost-reliability-assembly ease balance. It suits standard components and has great solderability. Pick ENIG if using fine-pitch components (BGA, QFN) or need a flat surface for precise placement.

Conventional multilayer PCBs are prone to signal distortion caused by electromagnetic interference while transmitting high-frequency signals, leading to the reduction of performance, EMC problems, and higher manufacturing and after-sales costs.

HDI PCB technology addresses the above constraints by finer routing, controlled impedance structures, and advanced dielectric materials to allow better signal isolation and cleaner high-speed signal paths.

This blog will guide you through all essential information about this HDI multilayer PCB, including its pros and cons, differences from PTH and other PCBs, and stackup.

You will also get a deep dive into how to design these high density interconnect PCBs, best practices for manufacturing and assembling them, costs for these PCBs, and why to partner with a reliable HDI circuit board supplier like FS Circuits.

What are HDI PCBs?

High density interconnect PCBs refer to a group of PCBs that utilize advanced technologies to attain increased wiring density per unit area. These HDI multilayer PCBs offer microvias, fine lines and spaces, and more than one layer to enhance miniaturization as well as high performance in electronics.

The core objective of HDI circuit boards is to enable more components and functions to be packed into a smaller space, driven by the miniaturization and increased performance demands of modern electronics like smartphones, AI servers, and advanced automotive systems.

Advantages of HDI PCBs

Miniaturization and Lightweight Assembly

By introducing micro-vias (blind/buried vias) and finer traces, HDI circuit boards present a much higher wiring density in compact and lighter electronic products.

Excellent Electrical Performance

By combining shorter interconnection paths using microvias and high-end low-loss materials, HDI PCBs ensure outstanding performance for high-speed and high-frequency applications.

Better Stability

With compact size, advanced PCB materials, and construction like filled vias and sequential lamination, these PCBs also provide better resistance to heat, moisture, and mechanical stress.

System-Cost Saving Potential

Although high density interconnect PCBs are more costly to produce, they may enable a reduction in the overall system cost for complicated designs.

Support High-End Precision Packaging

HDI PCBs are fully compatible with ultra-compact SMT component packages, including BGA, CSP, and QFN, making these PCBs a foundational component in cutting-edge AI hardware and high-performance computing.

Disadvantages of HDI PCBs

Longer Lead Times

The intricate stackups, numerous lamination stages, and tight tolerances make these high density interconnect PCBs longer to manufacture, usually adding lead times compared to those of standard layouts.

Complex Design

HDI PCB design requires strict trace/space rules, detailed impedance and signal integrity considerations, and knowledge of microvia usage, making it a more involved and risky design process.

Quality Control Challenges

Tiny features such as microvias, blind and buried vias, and dense routing also challenge visual and electrical inspections, which are increasingly assisted by AOI and X-ray systems with high levels of reliability in defect detection.

Lower Production Yield

The complex process of fabrication, high precision tolerances, and fragile materials combine to generally cause higher defect rates and lower yields than traditional PCB methods.

HDI PCB vs. Multilayer PCB vs. PTH PCB

Differences	Multilayer PCB	PTH PCB	HDI PCB
Via	Through-holes, blind or buried vias	Plated Through-hole vias	Microvias, blind or buried vias
Routing Density	Moderate routing density	Higher density allowing smaller holes and spacing	Very high routing density
Layer Count	Starting at 4 layers, extending to 30, 64, or even over 100 layers	Single-layer or multilayer	From 4 layers for simpler consumer devices to 20+ for complex systems
Electrical Performance	Adequate for many applications	Robust signal and power paths; increased signal integrity in high-speed scenarios	Enhanced signal integrity, reduced EMI, and more
Cost	Moderate cost	Less cost	Highest cost
Manufacturing Complexity	Moderate complexity	Simplist manufacturing	Highest manufacturing complexity
Application	Consumer electronics, automotive, medical, and more	High-reliability sectors like automotive, aerospace, industrial machinery, and medical devices	Space-constrained high-performance devices like smartphones, wearables, tablets, and digital cameras, as well as complex systems in automotive, IoT, and more.

Professional Guidelines for HDI PCB Design

Designing HDI multilayer PCBs successfully requires careful consideration of signal integrity, power distribution, thermal management, and more. Below are some key things to consider when designing these high density interconnect PCBs:

Proper HDI Stackup Selection

The planning and selection of HDI PCB stackup should be based on requirements for signal integrity, power integrity, thermal management, and manufacturing costs. Below are the common types of HDI circuit board stackups and their applications:

Type I HDI PCB (1+N+1): features single build-up layers on both sides with microvias connecting to the first buried layer. Ideal for smartphone applications and portable devices requiring moderate density enhancement.

Type II HDI PCB (2+N+2): incorporates two build-up layers on each side, enabling higher component density. Perfect for tablet computers, automotive infotainment systems, and advanced consumer electronics.

Type III HDI PCB: The most advanced configuration with stacked microvias spanning multiple layers. Essential for server motherboards, networking equipment, and high-performance computing applications.

Microvia Design

Ensure the aspect ratio of the microvias is ≤ 0.75:1 to 1:1 to prevent unreliable copper plating inside the hole. Keep the aspect ratio of the laser microvias below 0.8:1, and use via-in-pad for BGA pitches ≤ 0.8 mm to eliminate dog-bone fanout and save routing space.

Maintain annular ring ≥ 0.05 mm on laser-drilled microvias to prevent thermal, mechanical, or environmental failures. Minimize stacked microvias on high-speed signals to prevent impedance discontinuities and thermal stress concentration.

Impedance Control for High-Speed Signals

Ensure at least 2W to 3W spacing between traces to mitigate crosstalk in tightly packed HDI PCB routing. Place reference planes on the adjacent layers with one dielectric spacing. Maintain tight coupling between signal and reference planes, especially under fine-pitch BGAs.

For high-speed and RF designs, design traces with controlled impedance (e.g., ~50 Ω single-ended, ~100 Ω differential) and minimize discontinuities such as stub lengths. Use simulation tools to validate impedance against the chosen stackup and materials.

Learn: How to Achieve Target PCB Impedance Control?

Thermal Management

Thermal challenges in HDI PCBs require innovative solutions beyond traditional copper pours. Prioritize thermal vias under high-power components and plan for adequate cooling early in the layout.

For power electronics applications, incorporate thick copper layers (105μm) in critical power distribution layers while maintaining thin dielectric layers for signal routing.

Trace Width and Spacing

General values of trace width and spacing can go down to 3-4 mils (0.075-0.1 mm). At higher densities, finer traces are required so that they can route between tightly packed components.

Use microvias for escaping high-pin-count BGAs. Staggered vias are often more reliable and cost-effective than stacked vias.

Power Distribution

HDI PCBs use power and ground planes to reduce noise and voltage drop. Design a robust PDN with closely spaced power/ground planes and adequate decoupling for stable voltage.

Design for Manufacturability

Consult your HDI PCB manufacturer before finalizing the design. They can provide specific capabilities on minimum features, tolerances, and preferred data formats.

Specify copper-filled, resin-filled, or tented vias clearly. Note that filled and capped vias have stricter requirements.

HDI PCB Manufacturing Process

Best Practices for HDI PCB Fabrication & Assembly

Below are some best practices for manufacturing and assembling these high density interconnect PCBs:

Guidelines for HDI Board Manufacturing

Material Selection

Use thinner core and prepreg materials to facilitate microvia formation and support fine features. For high-speed signals, select materials with stable dielectric constants to control impedance.

Microvia Drilling Control

Maintain the standard HDI dielectric thickness from 65 to 75 μm. For UV laser drilling, keep the minimum via diameter at 75 μm; for CO₂ laser drilling, at 100 μm. Control the via wall angle at 60-80° for both CO₂ and laser drilling during the HDI PCB manufacturing process.

Desmear Execution

Use plasma + chemical dual desmear for microvias in 2-N-2 or any-layer HDI. Use cross-section analysis to check for resin smear at the target pad interface to ensure no polymer barrier remains.

Plating Uniformity

Use periodic pulse reverse(PPR) plating rather than traditional DC plating to enhance plating uniformity and avoid voids caused by rapid or insufficient deposition.

IPC-6012 Revision ES raised the Class 3 minimum plating thickness at any point in the via from 18 μm to 20 μm, with plating uniformity tightened to ±15%. For HDI blind microvias, plating through-hole (TP)> 85% is required; for filled vias, TP> 95% is required.

Sequential Lamination Management

The typical parameters for lamination are the temperature from 180 to 200°C, pressure 200–400 PSI, and time 60–120 minutes.

Via Fill and Planarization

Adjust the fill pressure based on the via diameter or the board thickness ratio. Control the curing temperature at 150-180°C using a three-stage temperature gradient of preheat–fill–cure.

After CMP (chemical mechanical polishing), pad coplanarity must be controlled within ±15 μm. Some leading processes achieve surface flatness of <8 μm.

HDI PCB Assembly Guidelines

Surface Finish Selection

Choose ENIG and ENEPIG finishes rather than HASL for the SMD and BGA assembly for high density interconnect PCBA.

Solder Paste and Stencil

Keep the stencil area ratio larger than 0.66. For fine-pitch BGA and via-in-pad structures, keep stencil thickness from 100 to 125 μm. For ultra-HDI PCB assembly, use a thinner stencil or Type 5+ solder paste.

Use Type 4 or Type 5 solder paste for 01005 components and fine-pitch applications, combined with laser-cut or electroformed stencils.

Reflow Temperature Profile

Balances temperatures across different PCB areas, activates flux, and particularly allows large copper areas to catch up with small components during the soak stage.

Using nitrogen-protected reflow equipment, peak temperature fluctuation can be controlled within ±3°C, effectively reducing thermal stress accumulation on HDI boards.

Why Partner with FS Circuits for HDI PCB Assembly Services?

As a global high-density interconnect PCB producer with top-tier operations, FS Circuits employs state-of-the-art technology, experienced engineering, and end-to-end manufacturing capabilities to deliver uncompromising results for customers worldwide.

FS Circuits

20+ Years Experience • 300+ PCB Engineers • 200+ SMT Assembly Specialists Serving 200+ international clients with one-stop and turnkey PCB assembly solutions from prototype to volume production.

Get Your HDI PCB Assembly Quote Today

FS Circuits

Comprehensive Manufacturing Capabilities

Specification	Standard Capability	Advanced Capability	Applications
Layer Count	4-16 layers	Up to 32 layers	Consumer to enterprise computing
Microvia Diameter	100-150μm	50-75μm	Ultra-high density designs
Minimum Trace/Space	75/75μm (3/3 mil)	50/50μm (2/2 mil)	Advanced mobile processors
Via Stacking	2-3 levels	Up to 6 levels	Server and networking equipment
Board Thickness	0.4-3.2mm	0.2-6.0mm	Wearables to industrial systems

Advanced Manufacturing Infrastructure

SMT Lines: 2 SMT PCBA lines, capable of 8 million placements daily
Component Placement Machine: The latest machine capable of handling 01005 size components and 0.15mm Pitch BGA
Manufacturing Environment: ±1°C temperature stability and 45±5% humidity control
Solder Types: Water Soluble, Leaded, and Lead-Free options available
Testing & Quality Control: Includes X-Ray, AOI, ICT, Flying Probe, Burn-in, and Function Testing
Component Range: 0201 to BGA, CSP, and QFP
Speed & Efficiency: 0.15 sec/chip, 0.7 sec/QFP
Through-Hole Assembly: 25,000 units per month
THT Equipment: 5 automatic soldering/testing lines
THT Full-Time Production Staff: 200+

Supply Chain Excellence and Cost Savings

Tied up with tier-1 component distributors like Arrow, Avnet, and Future Electronics, ensuring original parts and competitive prices.
Integrated PCB and assembly facility saves logistics costs and reduces lead times by 30% compared to single-stand-alone vendors.
Proved 15-25% total cost savings compared to similar capabilities in North America or Europe, without sacrificing quality or delivery performance.

Value-Added Services and Support

Design consultation, free DFM checking for HDI PCB designs, and application-specific optimization.
Component purchasing, SMT assembly, through-hole insertion, testing, and box build assembly.
Rapid prototyping with 24- 48-hour PCB delivery and complete PCBA solutions in 5-7 days.
Global component supply network assures availability even for obsolete or difficult-to-find components.
Specialized services include firmware programming, functional testing, and customer support with CE, FCC, UL, and other regulatory approvals necessary for international market access.

Compliance with Global Standards

Long-term certifications include ISO 9001:2015, ISO 14001, IATF 16949, ISO 13485, and UL approval.
HDI PCB assembly quality control system supported by Six Sigma methodologies and lean manufacturing principles.

Quality Assurance for Critical Applications

100% X-ray inspection, microsectioning analysis, and accelerated life testing for MIL-PRF specifications.
PPAP (Production Part Approval Process) documentation and ongoing SPC (Statistical Process Control) monitoring for automotive PCB JESD22-A104 requirements.
Specialized documentation packages for FDA submissions, lot traceability systems, separate production lines, and validation protocols for medical PCB production.

Rigorous HDI PCB Certifications

Industrial HDI circuit boards manufacturing necessitates adherence to stringent global standards for ensuring guaranteed performance and reliability in mission-critical applications. As an experienced China PCB manufacturer, we are certified on several industry standards to serve a range of market niches.

Standard	Application	Key Requirements	Industries Served
IPC-2226	HDI Design Guidelines	Microvia design, layer count, trace specifications	Consumer Electronics, Telecom
IPC-6016	HDI Performance Specification	Microvia reliability and stacked via requirements	High-Speed Digital and RF Applications
ISO 13485	Medical Grade PCB Quality	Biocompatibility, sterilization resistance	Medical Devices, Implantable Electronics
AS9100D	Aerospace Quality Management	Military grade PCB specifications	Aerospace, Defense, Military
IATF 16949	Automotive Quality	Automotive electronics reliability	Electric Vehicles and ADAS Systems

Customer Success Stories

Our HDI circuit board solutions have enabled breakthrough products as industries. One of the world’s largest medical device firms shrank its implantable sensor by 60% with our advanced microvias technology while maintaining 15-year reliability expectations.

A tier-1 automotive supplier achieved first-pass design success for their autonomous driving computer using our state-of-the-art thermal management practices with the ability to operate in engine compartment temperatures up to 105°C.

One of the telecom equipment companies brought their 5G small cell radio to market 6 months earlier than planned using our high-speed prototyping and concurrent engineering assistance.

Conclusions

HDI circuit boards boast higher density, superior signal integrity, and a smaller size. This makes them ideal for up-to-date high-performance applications in smartphones, medical devices, and automotive systems.

Success in designing, manufacturing, and assembling these HDI multilayer PCBs requires expertise in advanced materials, precision processes, comprehensive quality management, and more.

With over 20 years of experience in the PCB industry, world-class facilities, and a commitment to continuous innovation, FS Circuits can be your ideal HDI PCB supplier for challenging projects in various industries.

Frequently Asked Questions

How much does an HDI board cost compared to standard PCBs?

HDI PCBs typically cost 20-50% more than standard PCBs for basic designs and up to double for complex designs. However, HDI often reduces total system cost by enabling smaller product sizes, fewer layers (a 10-layer standard board can often be made as a 6-8 layer HDI), and improved performance. For high-volume production, the price difference narrows to 10-15%.

What are the typical lead times for HDI PCB assembly services?

Standard HDI PCB manufacturing typically requires 5-8 business days for prototype quantities and 10-15 business days for production volumes. Complex designs with multiple stacked microvias or special materials may require 12-20 days. Express services can reduce prototype delivery to 48-72 hours with a 30-50% premium. Our integrated PCB and assembly facility can deliver complete PCBA solutions in 5-7 days for urgent projects.

How reliable are high density interconnect PCBs in harsh environments?

HDI PCBs can be extremely reliable in harsh environments when properly designed and manufactured. For automotive applications, our HDI boards withstand temperature cycling from -40°C to +125°C for 1000+ cycles.

Can HDI circuit boards handle high-frequency applications?

Yes, HDI PCBs excel in high-frequency applications up to 100 GHz when designed with appropriate materials and techniques.

Turnkey Industrial Control PCBA Services | FS Circuits

A failure in industrial automation can halt the machines and delay the manufacturing of the whole industrial system. Therefore, the industrial control PCB must comply with high-quality standards and maintain careful material selection, proper layout, strict quality control, and more during manufacturing and assembly.

This guide is here to help you learn more about these industrial automation PCBs, including their features and benefits, common uses of them in the smart factory.

You will also know more about how to design these industrial machinery control PCBs correctly, best practices for assembling these PCBs, including proper materials selection, challenges and solutions, industry standards for them.

We will also introduce key things to consider when selecting a PCBA supplier for industrial control, and why to choose FS Circuits’ advanced and turnkey industrial automation control PCBA services.

What is Industrial Control PCB?

An industrial automation PCB is a printed circuit board designed for operation in industrial environments with extreme temperatures and mechanical vibration. It serves as the core unit of industrial equipment, controlling various functions and processes.

Industrial control PCB assembly is the process of building such PCBs for industrial control systems and the automation of equipment.

Advantages of Industrial PCB

Here are the key advantages of these PCBs for industrial control:

Environmental Safety

Industrial PCBs are designed with protective measures to protect from such harsh conditions as dust, moisture, and exposure to various chemicals in harsh industrial environments.

Immune to Noise

Industrial environments are full of noise due to motors, switching devices, and other industrial equipment, and also experience numerous electromagnetic interferences. Industrial automation PCBs are designed with proper shielding and filtering techniques to minimize interference for reliable signal transmission.

Temperature Range

The temperature inside industrial conditions may change frequently. Industrial automation PCBs with high tg materials are designed to operate even in maximum temperatures where temperatures change over time. They are designed with a layout that resists deformation caused by heat.

Mechanical Durability

Industrial PCBs are designed to withstand high mechanical vibration and shock generated in the industries. Strong board materials, solder joints, and secure mounting components ensure stable operation under harsh mechanical conditions.

Flexible and Functional Interface

Industrial automation PCBs typically include multiple legacy and modern (Ethernet, USB) communication ports, as well as expansion slots (PCI, PCIe) to connect with sensors, actuators, and specialized industrial modules. This enables direct integration into complex control systems.

Critical Redundancy and Safety

For high-availability or safety-critical applications, these PCBs can be designed with redundancy (like dual power or network links) and incorporate safety-oriented designs. They can meet stringent international safety standards (e.g., UL, IEC).

Key Uses of Industrial Automation PCBs

Industrial machinery control PCBs are mainly used for the following applications:

Automation and Robotics

These industrial PCBs are commonly found in robotics for handling motion-controlled machinery equipment and navigation. They are critical for control units of robots and other industrial automation operations, offering computational power and connectivity.

PLC Control System

Industrial control PCBs in Programmable Logic Controller (PLC) integrate modules like CPU, and input/output interfaces, meeting the demands for high-speed, accurate data processing, and complex logic control.

They also ensure that the PLC can accurately collect data in real-time from on-site sensors and control the actions of actuators based on preset programs.

Signals and Communications Networks

Industrial automation PCBs are used as signal controllers in communication between components and machinery equipment through network devices like routers, switches, and modems. These PCBs enable components to interact and operate efficiently.

Power Management

These are crucial for the distribution and management of power. They are used in converters, inverters, and the distribution of electricity to equipment used in machines and systems.

Intelligent Sensors and Instruments

In industrial automation manufacturing, industrial PCBs serve as the core components for intelligent sensors and instruments to real-time monitor temperatures, pressure, flow, and liquid level. A high-precision industrial automation PCB enhances the measurement and monitoring accuracy and reliability of the sensors in harsh environments.

Distributed Control System (DCS)

These PCBs also play a crucial role in data acquisition, processing, and communication within the DCS(Distributed Control System) in industrial manufacturing.

By designing industrial PCBs effectively, the DCS can achieve centralised management and decentralised control of the entire production process, thereby improving production efficiency and management standards.

Industrial Control PCBA Design Guidelines

Below are some key things to consider when designing these industrial machinery control PCBs:

Multi-Layer PCB Design

Designers can utilize multilayer PCB designs that typically employ 4-10 layers, and sometimes even more than 16 layers. For most industrial control boards, the optimal choice for balancing cost and performance is a 4-layer PCB.

The recommended correct 4-layer structure is as follows:

Layer 1: Signal (Top)

Layer 2: Ground Plane

Layer 3: Power Plane

Layer 4: Signal (Bottom)

Layer Stack-Up Optimization

Below are some key methods to optimize the layer stack-up of industrial control PCBs:

Position each signal layer adjacent to a power or ground plane to create microstrip or stripline configurations.
Keep layer stack-up symmetrical vertically to minimize PCB warping risk

Component Placement

For instance, position the MCU in the upper-center area of the PCB. Place capacitors as close as possible to the pins, and keep the trace lengths within 5mm.

Mount the external crystal oscillator immediately adjacent to the MCU and surround it with ground traces (Guard Ring), with ground vias at both ends for isolation. Position the DC-DC module at the board’s edge, away from analog and communication areas;

EMC Design and Signal Integrity

To maintain signal integrity, a PCB in industrial automation should be designed with proper grounding techniques, like ground plane shielding to critical signal layers, shielded traces, ferrite beads, and filters. Use differential signalling to improve noise immunity.

Never route the traces across a plane with discontinuities. Implement guard traces and densely populate via stitching at both ends, maintaining spacing of at least 3 times the trace width. Maintain strict length matching for differential pairs, with deviation not exceeding 5 mils.

For impedance control, use 50Ω for single-ended signals and 100Ω for differential pairs. Also, there should be separation between the digital, power, interface, and analog regions, and ensure that they won’t overlap.

Thermal Management

During industrial automation PCB design, place heat-sensitive components away from the heat source, utilize the thermal vias, heatsinks, and copper pour to improve heat conduction on these PCBs in harsh environments.

Moreover, employ thermal pads with star-pattern connections to balance both solderability and heat transfer. Also ensure the copper coverage are not on the high-speed signal regions, and with recommende 2oz thickness on both top and bottom layers of the 2 layer PCBs.

Power Integrity

Wide power traces and multiple power planes are used to deliver stable energy. Add overcurrent protection devices, such as fuses and PTC thermistors, to safeguard circuits against damage, ensuring both safety and reliability in demanding applications.

Spacing

Calculate the line width based on the current the PCBs carry. Minimum trace spacing depends on operating voltage, pollution degree, and applicable safety standards. Creepage and clearance requirements must comply with IPC and IEC guidelines.

Best Practices for Industrial Control PCBA

Early DFM Review before PCBA

It’s necessary to implement the DFM review early before the industrial control PCB assembly to get feedback about the design and find issues to prevent the risk of widespread failures in later stages.

Below are key points to check during your DFM review:

Ensure the pad size complies with IPC-7351
Component Orientation Consistency
At least two fiducial marks for alignment
Test Point Diameter ≥1.0mm with Spacing ≥2.54mm
Reserve X-ray inspection area beneath BGA packages

Proper Materials Selection

For different applications of industrial automation, the materials for the PCB assembly varies:

Industrial PCB Materials	Features	Common Uses in Industrial Automation
FR-4	Tg value of 130 and 140℃, Dk of 4.2-4.6, and Df of 0.015-0.025	Common industrial control uses
High Tg FR-4	Tg value of 170 and 180℃, Dk of 4.0-4.4, and Df of 0.012-0.018	Industrial automation controllers, power management boards, industrial control motherboards in high temperature below 100℃
Polyimide	Tg value above 300, Dk of 3.4-3.6 and Df of 0.002-0.005	Flexible industrial PCBs for High-power devices (LEDs, power modules)
Metal Core Substrates like aluminum and copper	Tg value above 250, Dk of 4.2-4.8 and Df of 0.008-0.015	Heat dissipation for high-power LED lighting, motor drivers, power modules (IGBT) and others
Ceramic	Thermal conductivity 24–230 W/m·K, CTE matched to silicon, excellent insulation	high-power laser driver systems, high-frequency radiofrequency modules, and aerospace control units

Lamination Process Control

For the industrial control motherboard, utilize the vacunm lamination technology. Develop exclusive temperature control models for lamination by adjusting the heating rate and pressure gradient based on the PCB type and the lamination structure. Industrial control PCBA suppliers can even generate independent SPC data packages for each batch of products for customers to trace.

Surface Finish Selection

Standard OSP and immersion sliver finishes can not meet the requirement for the demanding environments in industrial automation. The recommeded solution is to implement ENIG plating across the main control board combined with localized Hard Gold reinforcement. This ensures robust solder joint reliability while simultaneously enhancing connector interface durability and longevity.

Conformal Coating

To prevent short circuits led by moisture, salt spray, mold and dust during the industrial automation control PCBA, it’ s better to implement conformal coating with materials like the acrylic, polyurethane, or silicone compounds.

Also, carefully control the coating thickness and coverage area, such as avoiding connectors and heat sinks, and verify through ultraviolet light inspection. For outdoor or high-dust environments, encapsulation processes should be implemented as an additional protective measure.

Cleaning after Soldering

After soldering, the flux residue that has absorbed the moisture will lead to conductive paths that cause short circuits. Therefore suppliers need to implement rigorous cleaning and iconic contamination testing to ensure the insulation performance.

Quality Control

The quality control for industrial automation control PCBA should cover the whole process from the IQC to the final output. Manufacturers need to implement a comprehensive series of testing including the AOI, X-ray, flying probe testing, functional testing, SPI, thermal testing, humidity testing, and more.

Standards for Industrial Control PCB Assembly

Standard	What It Measures / Covers
IPC-A-610	Acceptability criteria for solder joints, component placement, and overall assembly workmanship
IPC-6012	Performance and qualification requirements for rigid printed circuit boards
IPC-2221	General PCB design rules including spacing, creepage, and layout guidelines
IPC-2152	Current-carrying capacity of PCB traces based on copper thickness and temperature rise
IPC-7351	Surface-mount land pattern design and component placement requirements
IPC J-STD-001	Requirements for soldering materials, processes, and solder joint quality
ISO 9001	Quality management system and process control requirements
UL 94	Flammability ratings of PCB substrate and plastic materials
UL 796	Safety requirements for printed wiring boards
IEC 61000	Electromagnetic interference (EMI) and electromagnetic compatibility (EMC) limits
IEC 60204-1	Electrical safety requirements for industrial machinery systems

Future Trends of Industrial PCBs

Miniaturization

As industrial controllers become more compact and feature-rich, HDI technology with smaller vias and finer trace spacing will enable higher routing density and more complex circuit layouts in limited spaces.

Integration with IoT & Edge Intelligence

Industrial automation PCBs increasingly need to support IoT connectivity, edge computing, and real-time data processing to enable smart factory applications and distributed intelligence in automation.

AI-Enhanced Design & Manufacturing

AI and machine learning are transforming PCB design, layout optimization, and quality inspection through predictive analytics and automated tools, leading to fewer defects and more efficient industrial PCB production.

Industry 4.0 Integration

Industrial PCB manufacturing itself is evolving toward smart factories, where automation, data exchange (IoT), and cyber-physical systems reduce errors and optimize production performance under Industry 4.0 frameworks.

Cloud-Connected Quality & Data Sharing

Cloud-based inspection data and shared analytics across production facilities will allow cross-site quality control, predictive maintenance, and remote troubleshooting for PCB assemblies used in industrial control systems.

How to Choose Reliable Industrial PCBA Suppliers?

Below are some key points to check when selecting a suitable PCBA supplier for industrial control:

Technical Depth: Check if the manufacturer can provide impedance simulation and SI/PI analysis.
Process Capability: Whether they support HDI, back-drilling, and mixed-pressure materials; What is the minimum line width?
Quality Management System: Are they certified to ISO 9001/IATF 16949? Can they provide PPAP documents? Do the products comply with RoHS and REACH regulations? Is the UL file number valid?
Response Speed: What is the lead time for the small-batch prototype? Is there dedicated FAE support available?

Why Partner With FS Circuits for Industrial Control PCBA?

FS Circuits is your trusted and one-stop solution for industrial PCB assembly and offers multi-layer industrial PCB fabrication. FS Circuits can match your needs for simple to complex designing, small batch to high volume industrial automation PCBA, and startups to industrial giants.

With the support of global procurement, professional engineering, and strict quality control, our specialists lead projects via 1V1 PM to deliver a better industrial control PCBA solution.

Through advanced PCB assembly capabilities, we ensure that every performance metric meets industrial-grade standards in industrial automation.

Resistance to Harsh Environments: Utilize substrates like high Tg FR-4, IMS substrates, ceramics, polyimide; Conformal coating and more
Strong Current-Carrying Capacity: We offer thicker copper foil with 2 oz thickness for your industrial control PCB manufacturing based on your requirements, ensuring your PCB conductivity and overall electrical stability.
Strong EMC: We offer a well-structured, layered PCB design for high-frequency, high-precision industrial control signal systems, enhancing signal integrity and system response speed.
Multilayer Structure Support: FS Circuits meet the requirements for precision control circuits and multi-signal integration, offering HDI PCB designs, high-precision drilling and custom complex industrial control PCBs with multiple layers.

Strict and Rigorous Quality Control: Our inspection and testing for these industrial control boards cover the whole PCBA process, including IQC, SPI, X-ray, AOI, functional testing, flying probe testing, thermal and humidity testing and more.
Adhere to Industrial-Grade Standards: Our final industrial PCB assembly complies with ISO 9001:2015, RoHS, REACH, and UL, providing with valid document and full traceability.
Superior Responsiveness: We support fast PCB prototyping within 24 hours, and we can provide you a quote with better prices within 2-3 days.

FS Circuits Industrial Control PCB Assembly Capability

Capability	Volume
Maximum number of layers	36
Board thickness	0.25″
Maximum Panel Size	23.62″x39.37″
Impedance tolerance	-/+ 5%
Minimal Laser Drilling	0.002″
Minimal Mechanical Drilling	0.0059″
Min trace and space	0.0015″
Drilling process	“Blind Buried Vias”

FAQ

What are the examples of industrial automation PCBs?

Typical examples include industrial Ethernet gateways for communication protocols (e.g., Ethernet/IP, EtherCAT), programmable logic controller (PLC) mainboards, and human-machine interface (HMI) control panels that require high reliability and real-time processing.

What are the main differences between industrial control PCBA and commercial PCBA?

The core differences are in reliability and durability: industrial PCBA uses components rated for wider temperature ranges and longer lifecycles, employs more robust PCB designs, and adheres to stricter quality standards to withstand harsh factory environments like vibration and humidity.

What should you consider when finding a reliable industrial automation PCBA supplier?

Key considerations are technical capability (experience with industrial protocols and impedance control), quality systems, and operational stability.

Microvia PCB: All Things You Need to Know

As the brains of today’s electronics shrink to microscopic proportions, how can designers try to connect hundreds of signals within those smart devices? The answer can be found in microvias in the PCB.

This post will guide you through all things about microvia PCBs, including their importance, types, differences from blind vias, and microvia design guidelines and manufacturing proven best practices.

What is a Microvia PCB?

A PCB microvia is designed for high-density, high-performance applications. These printed circuit boards make use of microscopic holes, or microvias, whose diameter measures less than 150 microns. These PCB vias do not require spacing, allowing components to be arranged more closely together, thus enabling intricate and highly functional designs. Moreover, microvia PCBs enable a dense interconnect pattern with signal integrity and high-speed signal wiring.

Microvias in PCBs have their greatest strength in devices that need compact and high-speed signal wiring. They enable a dense interconnect pattern with signal integrity and have become integrated into the most advanced applications, such as 5G networks, state-of-the-art medical devices, or car electronics.

PCB Microvia vs. Blind Via: Key Differences

A microvia is a type of blind via, but not all blind vias are microvias. Below are the key differences between microvias and blind vias in PCBs:

Key Differences	Blind Via	Microvia
Definition	Outer-to-inner via that does not pass through the board	Laser-drilled via connecting adjacent layers
Drilling method	Controlled-depth mechanical drilling or laser	Laser only
Typical diameter	0.1–0.3 mm	0.05–0.15 mm (50–150 µm)
Aspect ratio	Often around 1:1, depending on the process	Usually 0.75:1 to 1:1
Cost impact	About 20–40% higher than through-hole boards	HDI process, often 2–3× base cost
Visibility	Visible from one side	Visible if blind; hidden if buried
Typical applications	BGA escape routing, preserving inner-layer routing	HDI boards, fine-pitch BGA, smartphones, wearables

Types of Microvias in PCB

Different PCB microvia types are available depending on the specific design and application. A few of the most common types include:

Blind Microvia

Blind microvias are an outstanding connector option for an outer layer and one or more inner layers, but they do not connect the outer layer through the entire board. They will save space in designs for direct connectivity to external components. This type of PCB via maintains signal integrity by reducing unnecessary layers.

Buried Microvia

Buried microvias connect only the internal layers of a PCB and are invisible from the outer surfaces. This way, they provide highly dense interconnection within the internal layers and don’t affect the external ones. This type is common in multilayer PCBs for high-performance applications.

Stacked Microvias

Stacked microvias refer to the placement of multiple microvias one on top of another across layers. Such microvias are useful in complex designs needing vertical connectivity through a multitude of layers. They are precision-manufactured to ensure alignment and reliability.

Staggered Microvias

Staggered microvias use an offset arrangement. They are not stacked, but rather layered vertically into or onto neighboring layers. These relieve the stress on the board and economically provide a means of multilayer connectivity. They are commonly used in HDI designs for structural integrity reasons.

Skip Microvia

A skip microvia connects non-adjacent layers by “skipping” an intermediate layer or layers. It allows longer vertical interconnects without stacking multiple individual PCB microvias. These microvias are more complex and require careful fabrication control.

What Makes Microvia PCBs a Game-Changer?

Microvias in PCBs are changing the face of today’s electronics with their astonishing design flexibility and unparalleled performance. Below are the benefits of utilizing these PCB vias in an HDI stackup:

Enable Miniaturization in HDI Design

With the use of microvias, HDI designs can be made with more layers and provide tighter, more efficient connections between them. The HDI microvia stackup structure thus improves signal integrity while allowing a smaller size of the board for very complex, high-speed electronic devices.

These microvias in PCBs allow the addition of more layers without increasing dimensions and compromising functionality, which is highly desirable for advanced applications like 5G and medical devices.

Improves Signal Integrity

Microvias shorten interconnect lengths and reduce parasitic inductance and capacitance relative to through-hole vias. This leads to lower signal reflections, reduced loss, and better performance at high data rates and high frequencies. All of those advantages make these PCB vias critical for high-speed digital and RF circuits.

Reduces Manufacturing Complexity

By enabling direct connections between adjacent layers, microvias often reduce the total number of layers required in a PCB stackup. This can lower overall board thickness, weight, and potentially cost for complex designs when compared to boards that rely on larger or multiple mechanical vias.

Improves Thermal Management

When used in arrays or filled configurations, PCB microvias can distribute current paths more evenly and assist in heat dissipation. They enhance power rail stability and thermal performance, which is particularly important in dense, high-power boards.

Greater Design Flexibility

PCB Microvias provide designers with more freedom to place vias in tight spaces (including via-in-pad for fine-pitch components) and configure stacked or staggered via structures. They simplify routing for complex IC breakouts.

Key Limits of Microvia PCBs

Higher Manufacturing Cost

A microvia in PCBs generally requires sequential build-up, laser drilling, additional plating, and tighter process control. As the HDI structure and the PCB microvia fabrication become more and more complex, the cost for these PCBs has been higher.

More Difficult Inspection

Some microvia defects are internal or latent and may not be detected by conventional visual inspection or ordinary microsection evaluation.

Stringent Materials Selection

Dielectric thickness, laminate properties, copper behavior, and thermal expansion characteristics can influence microvia reliability. Therefore, material selection cannot be separated from the intended microvia structure and reliability requirements.

PCB Microvia Design Rules and Guidelines

Microvia PCBs are optimally designed to ensure effective performance and reliability. Here are some important considerations for arranging microvias in printed circuit design:

Adopt the Right Via Type

Select the microvia type from blind, buried, stacked, or staggered based on the kind of requirements that the design has in terms of complexity, performance, and cost within the designed structures.

Follow IPC-2226 and IPC-T-50M Standards

Take the IPC-2226 and IPC-T-50M as primary references for microvia design dimensions, definitions, and stack-up classifications. These standards define microvias and recommend build-up structures for HDI designs to ensure the manufacturability and reliability of microvia in PCBs.

Prefer Staggered over Stacked Microvias

Use staggered microvias rather than tightly stacked ones wherever feasible. Staggered microvias distribute stress and improve reliability under thermal cycling. When stacking is required, limit vertical stack height and ensure accurate alignment.

Aspect Ratio

When the laser-drilled microvia PCB aspect ratio exceeds 1:1, the plating can not reach the via bottom reliably. This results in thin or absent copper that passes room-temperature electrical tests but fails under thermal cycling. The PCB microvia aspect ratio should be at or below 1:1, with 0.75:1–0.8:1 recommended for microvia PCB fabrication.

Formula: Microvia Aspect Ratio = (Dielectric Thickness on Outer Layer + Outer Copper Foil Thickness) ÷ Microvia Diameter

Annular Ring Requirements

For HDI microvias, the minimum annular ring is typically 75 µm on the capture pad and 50 µm on the target pad. For a 100 µm PCB microvia with 53 µm registration tolerance and a 50 µm Class 3 annular ring, the minimum pad = 100 + 2 × (53 + 50) = 306 µm. Round up to 0.30–0.35 mm.

Via-in-Pad for Fine-Pitch BGA

For a 0.5 mm fine-pitch BGA, designers should implement via-in-pad with microvias because dog-bone fan-out stops fitting.

Must specify a planarization tolerance of ±10 µm flatness. Without planarization, solder voids and tombstoning occur during reflow. Specify filled and capped vias required in fab notes, not just “via-in-pad”.

Symmetry Stackup Design

Design the buildup symmetrically around the core to prevent warpage. For a 1+N+1 HDI stackup, use one microvia buildup layer on each side of the core.

Buried Via Span Limits

Buried vias should not span more than 3 layers. Buried microvias should not span more than 3 layers to prevent registration failure and open circuits.

For connections spanning more than 3 layers in the core, use sequential lamination with multiple buried via stages rather than attempting a single deep buried via.

Anti-Pad Clearance on Ground Planes

Insufficient anti-pad clearance on ground planes causes capacitive coupling and impedance shift. For RF and high-speed digital signals, keep the anti-pad clearance no less than 200µm to maintain the controlled impedance through the via transition.

Impedance Control

Thinner dielectric helps impedance control, but limits microvia diameter. Thicker dielectric allows larger vias but degrades impedance control.

For high-speed designs, use the thinnest dielectric that still allows a manufacturable microvia aspect ratio (0.75:1–0.8:1). If this forces via diameters below 75 µm, switch to UV laser drilling or accept a larger aspect ratio with a microvia PCB manufacturer that has demonstrated plating capability at that ratio.

Microvia PCB Fabrication Process

Build-Up Layer Lamination

Laminate a dielectric layer(prepreg or resin-coated copper) onto the existing core. This layer becomes the medium for further laser drilling. For CO₂ drilling, a window is etched into the copper foil on the entry side via a photolithography process.

Laser Drilling

Load the panel into the laser drilling machine. The automatic vision system aligns the panel according to the fiducial marks. The laser then drills all the PCB microvias on the panel.

Desmear

After laser drilling, implement desmear methods to clean the charred resin residue created by the thermal energy from the laser drilling on the via bottoms and sidewalls.

Electroless Copper Deposition

A thin conductive layer of copper is deposited on the via walls and bottom through an electroless (autocatalytic) plating process. This seed layer enables subsequent electrolytic plating to build copper thickness.

Electrolytic Copper Plating

With the seed layer, standard electroplating can fill the micropores with copper. For plate-hole applications, implement copper-filled electroplating to fill the through-hole cavity with copper, forming a flat, weldable surface.

Sequential Lamination

For HDI stackups requiring more than one buildup layer, the entire process (Steps 1–6) is repeated for each layer pair in sequential lamination cycles. Each cycle adds one dielectric-and-copper layer pair with its own microvias.

Mechanical Drilling (Through-Holes)

After all buildup layers are completed, mechanical drilling creates through-holes that span the full stack.

Final Plating and Surface Finish

Plate the through-holes with copper to the required thickness. Then a surface finish is applied to protect exposed copper and provide solderability.

Inspection and Testing

Verify and inspect the microvias through multiple methods, including X-ray, microsection, IST, electrical testing, thermal stress testing, reflow simulation, and more.

Guidelines for PCB Microvia Manufacturing

Below are some key things to consider for microvia PCB fabrication:

Proper Materials Choice

Microvias must be supported by thermally and mechanically durable materials. Select dielectric materials with stable properties (e.g., consistent dielectric constant, low voiding potential, laser-drill compatibility) to support reliable laser-drilled microvia formation and plating.

Laser Selection for Drilling

Choose CO₂ lasers for ≥75 µm PCB microvias at high volume; UV lasers for <75 µm vias and direct drilling. The laser must stop at the target copper pad. If it penetrates too deep, it damages the inner layer; If it stops too shallow, the via bottom remains covered with dielectric and the electrical connection fails.

Desmear Method Choice

Choose a chemical desmear method for standard FR-4 through-holes. Plasma desmear for microvias in HDI production because it achieves more complete resin removal in small geometries. Many HDI fabricators use dual desmear to maximize interface bonding quality for stacked microvia structures.

Precise Control of Microvia Filling

Precision control operates simultaneously at three levels: molecular (additive adsorption), process (current, convection, chemistry), and system (DFM rules, quality verification).

Maintain vacuum-assisted filling with uniform resin fill and stable processing conditions for multilayer and high-aspect-ratio applications. Stacked microvias should be filled and planarized before lamination.

Lamination Cycles Control

A standard 1+N+1 HDI microvia stackup requires one lamination cycle. A 2+N+2 HDI requires two cycles. Each additional cycle multiplies cost and lead time and re-exposes all inner cores to the full press thermal cycle. Minimize lamination cycles during stackup planning.

Testing and Qualification

For stacked microvias with 3+ levels in Class 3 products, IST testing is mandatory, with extended cycle counts: 750 cycles minimum for 3-level stacks, 1000 cycles for 4+ levels.

How to Choose Reliable Microvia PCB Manufacturers?

It’s important to choose the proper manufacturer to ensure quality and reliability in PCB microvias. Choose the manufacturer that has experience in microvia technology because it is indicative of their ability to handle complex designs and to meet top standards in quality.

Look at their equipment and certifications to check if they have the most modern technology and industry standards for microvia PCB fabrication.

Read feedback and case studies to find out more about the manufacturer’s reputation and success record in their projects. Make sure that this manufacturer provides you with really great customer support throughout the design and production process.

Ask the manufacturer for the lead time and price to make sure that the client can have its projects done on time and affordably. Ask them about the quality control processes they have in place so that they can keep producing in a reliable and defect-free manner.

FS Circuits: Reliable Microvia PCB Manufacturer

With advanced equipment and experienced engineering and production teams, strict quality control, and adherence to standards like ISO 9001, FS Circuits ensures the high quality and consistency of our micro-hole PCBs, meeting the requirements of your projects.

Send Your Gerber File for Quote

FS Circuits

Conclusion

Microvia in PCBs is revolutionizing the electronics industry by enabling devices that are able to shrink as we go faster and perform better. Their ability to save space while upholding functionality and performance makes them a suitable interconnect for today’s gadgets-those that come in small, high-tech packages-and will be fully effective in promising future devices. Get Your Reliable Microvia PCB Today – Contact Us for a Quote!

What is the difference between vias and microvias?

A via is a plated hole in a PCB used to connect copper layers (through-hole, blind, or buried). A microvia is a very small via, usually laser-drilled in HDI boards. Microvia connects only adjacent layers, enabling higher routing density.

What is the difference between a microvia and a through-hole via?

A microvia is a small laser-drilled via connecting adjacent layers in high-density PCBs. While a through-hole via (plated through-hole) is mechanically drilled and goes through the entire board, connecting all layers.

PCB Edge Plating Guidelines: Design, Process & Thickness

PCB Edge Plating: How to Design and Implement?

In today’s smaller, faster, and densely integrated electronics, from 5G IoT modules to medical wearables, EMI failures have become a frustrating challenge for PCB performance. PCB edge plating, also called side plating or copper plating, serves as a solution for EMI challenges and enhances PCB mechanical integrity, grounding continuity, and EMI performance.

This blog will guide you through all things about this PCB plating, including those metal edges, its benefits, when to implement it, its whole process, thickness, design guidelines, and more.

What is PCB Edge Plating?

PCB edge plating, also called edge metallization, PCB castellated edges, or side plating, refers to the deposition of a conductive copper layer along the PCB outer contour. This PCB plating establishes electrical connections between the top layer, bottom layer, and even the internal layers of the PCB.

PCB Edge Plating vs. Castellated Holes

These two are two different edge metallization techniques used on printed circuit boards. PCB edge plating “frames” the side of the board with copper, while castellated holes PCB create a row of “half‑circle solder pads” along the board edge.

Key Differences	Edge Plating	Castellated Holes
Definition	A continuous copper layer deposited on the sidewalls of the PCB	Half‑circle plated holes located on the board edge (like castle battlements)
Primary Purpose	Grounding, EMI shielding, edge connections	SMD‑style board‑to‑board soldering (modules)
Manufacturing Process	Board edges are routed before electroless copper/plating, then plated with copper	Through‑holes are drilled and plated first, then the board is routed through the hole centre to create the half‑circle
Cost & Typical Use	Relatively lower cost. Used for RF shielding cans, EMI protection, and ground connections	Relatively higher cost. Used for wireless modules, sensor modules, and more

Different Types of PCB Edge Plating Methods

Below are some key types of methods during the PCB plating process:

Surround Edge Plating

Surround edge plating involves plating a metallic layer along the entire PCB edge, exposing the PCB sidewalls to chemical plating on base copper.

This PCB edge plating creates an extension in the solid conductive path and is particularly suitable for applications requiring better EMI shielding.

Edge of Copper Board

It is used to avoid oxidation and mechanical stress on copper traces on the board’s edges. It is typically used when certain areas of the board’s edge need to be plated.

Board Edge PTH

Board Edge PTH, or castellated holes on PCBs, refers to fabricating plated holes on the edge of the board. Split PCBs are chopped in half, leaving behind semi-circular edges that have been plated. Board Edge PTH is frequently utilized in module applications and board-to-board interfaces.

Round-Edge Plating

Round-edge plating creates a smooth, rounded shape by covering most or all of the PCB’s edges from top to bottom. This PCB plating process is suitable for creating solid grounding connections against metal enclosures or shields. It’s generally applied in higher EMI shielded and mechanically rugged applications.

Why Edge Plating on PCBs?

PCB edge plating has certain valuable advantages, enhancing the work of printed circuit boards, reliability, and functionality:

Mechanical Strength

They ensure that PCBs become stronger and prevent breakage when handling them and using the boards. Extra strength is desirable in PCBs that are applied to abusive conditions or units that are relocated frequently. These castellated holes are also what allow the board to fit more firmly into the metal casing.

Electric Benefits

The PCB edge plating helps enhance signal flow on the PCB. There are fewer interference and clearance indications of higher frequency circuits. As one has additional metal, additional electrical flow can be supported. On the whole, the PCB is enhanced to handle more complicated electronic devices that will require a good quality of signals.

Thermal Management

PCB side plating provides a secondary means for heat to escape from the board. It is also combined with other passive thermal routing features like heat sinks to channel excessive heat away from temperature-sensitive components.

In high-power modules like DC-DC converters, LED drivers, plated half-holes create a low-resistance thermal conduit soldered directly to the motherboard ground plane, helping maintain lower junction temperatures for power ICs.

Electromagnetic Compatibility (EMC)

PCB edge plating suppresses radiated emissions from internal signal or return layers, eliminating fields from leaking out of PCB sidewalls. Through creating a continuous conductive path around the PCB perimeter, this copper plating also enhances EMC by confining EMI emitted from PCB edges.

When to Use PCB Edge Plating?

High-Speed Designs

Edge plating makes the ground conductors and reference conductors across the board layers electrically connected at a consistent, low-impedance path at the board edge. This can be of such value in high-speed digital and RF design, because a stable grounding leads to a reduction in noise, ground loops, and enables better high-frequency performance.

High-Power Applications

Since the side plating can help in dissipating heat in hot sections of the PCB. The application is found in high-density power electronics, LED drivers, and power supply boards, where effective heat dissipation is used to extend the PCB component life.

Board-to-Board Connections

This PCB plating may be a direct electrical connection of the PCB edge, making the PCB edge a connector (e.g., gold fingers on expansion cards or modular boards). These plated edges have the capability of mating with sockets, backplanes, or dock connectors without further connector hardware.

RF Modules and Communication Modules

For RF and microwave circuits (e.g., 5G module, antenna front-end), PCB edge plating can help to avoid radiation leakage and ensure the signal performance of the circuit at high frequencies by reducing disruptions at the board boundary.

PCB Edge Plating Guidelines for Designing

Clear Indication in Design Files

The area for PCB edge plating through mechanical layers and silkscreen should be marked out clearly on the design files or technical documents. It is used to prevent CAM engineers from mistakenly taking it as a standard copper layer at the PCB edges.

Proper Plating Materials and Finishes

Select plating materials and thickness based on electrical, mechanical, and durability requirements. Common PCB edge plating uses copper, often with protective finishes like ENIG or hard gold, where high durability or contact reliability is needed.

Maintain Minimum Copper Overlap

Copper overlay ensures that the PCB edge plating is properly stuck to the surface of the PCB. Maintain at least 500 μm for smooth contact and smooth function.

Optimize the Layout

The copper layer at the edge of the board should belong to a clearly defined network (usually GND), and signal traces should avoid being too close to the edge of the board to prevent short circuits or incomplete electroplating.

Provide Adequate Clearances

Ensure that milling, routing, and plating equipment can operate without interference. Avoid placing vias near the PCB edge. Maintain at least 10 mil clearance between the edge plating and the other copper features.

Avoid Sharp Corners

Design PCB edge plating with rounded corners and, where possible, include chamfers to achieve more plating uniformity and mechanical strength. This also aids in manufacturing consistency and reduces defects.

Small Batch Validation

Produce 5–10 prototype boards to test the integrity of the electroplating, adhesion, mechanical quality, and electrical functionality, allowing for early detection of issues and adjustments to reduce rework costs during mass production of PCB edge plating.

Recommended Thickness of Edge Plating on PCB

The recommended PCB edge plating thickness is based on the IPC standard and the application requirements of your products.

According to the IPC-6012 standard class 1, the minimum average thickness of the copper for edge plating on PCB for standard consumer electronics should be 20 µm.

Based on the IPC-6012 standard class 2, the minimum average thickness of the copper for edge plating on PCBs in special applications like industrial control, telecommunications, and more should be about 25 µm.

Common PCB edge plating thicknesses are between 20 and 25 µm, but for higher reliability and better EMI shielding, the thickness can also be much higher, up to 50 µm.

The PCB Edge Plating Process: How to Implement?

Edge Milling and Profiling

The PCB panel is routed or milled to its final external form before any plating chemistry starts. Milling decides on the edges that will be plated, and produces flat and burr-free surfaces, for good plating adhesion.

Edge Surface Preparation

The new milled edges are washed, oiled, and chemically modified (micro-etching or activation) so that they are free of contaminants and the surface is made rougher.

Electroless Copper Plating

An initial thin copper layer is deposited chemically (without electrical current) over the entire board, including the exposed sidewalls. This ensures the plating process can uniformly cover complex geometries.

Electroplating

The seeded board is then placed in an electrolytic bath in which copper is electroplated to a desired depth on the periphery, upper, and bottom surfaces. Electrical current moves metal ions in solution to the plated area,s enhancing conductivity and physical strength.

Etching

Excess copper deposited during electroplating is selectively etched away to match the intended circuitry and edge contacts. This may include defining plated fingers for edge connectors or ensuring clearances from other features.

Optional Surface Finishes (ENIG, Gold, Tin)

In order to improve the solderability, corrosion resistance, and wear properties, surface finishes can be further overplated with Electroless Nickel Immersion Gold (ENIG), gold plating, or even tin on the copper edges.

Final Cleaning and Drying

Following plating and surface finishing, boards are thoroughly cleaned to remove residues from acids, plating solutions, and masking materials. Proper drying prevents oxidation before shipment or assembly.

Inspection, Testing, and Depanelization

Quality control checks include measuring plating thickness, verifying electrical continuity, and visual inspection for defects. Once approved, the panel is depaneled into individual boards, taking care to preserve the plated edges during singulation.

Common Issues in PCB Edge Plating Process

Copper Delamination

PCB edge plating on the large substrates may result in copper peeling due to insufficient adhesion. To address this issue, it is essential to roughen the surface using a combination of chemical and other proprietary methods. Subsequently, direct metallization with a higher copper bonding strength is employed to prepare the copper plating.

Burrs

In certain PCB edge plating processes, burrs may form during the final machining stage. Implement a modified proprietary process to polish the burrs to the edges of the features.

Higher Cost

Due to much more process complexity, the cost for edge plating on PCBs can be much higher. You can choose to partner with an experienced PCBA manufacturer like FS Circuits for fast-turn and cost-effective PCB manufacturing and PCBA.

Conclusion

PCB edge plating can improve board performance considerably by providing greater mechanical strength, electrical contact, and EMC compatibility. It is helpful in high-frequency applications and is a significant advantage in contemporary electronics design.

Ready to design stronger, more reliable PCBs? Check out FS Circuits. Consult our experts for edge plating and advanced PCB manufacturing and turnkey PCBA services today.

Can PCB edge plating be used for thermal management of high-power LED boards?

Yes, PCB edge plating improves heat dissipation since more conductive routes for transferring heat are presented. It comes in handy, particularly with high-power LED boards where excessive heat could impact performance as well as lifetime. Good edge plating relocates heat far away from vulnerable parts, yielding thermal reliability.

For most first-time projects, lead – free HASL gives the best cost-reliability-assembly ease balance. It suits standard components and has great solderability. Pick ENIG if using fine-pitch components (BGA, QFN) or need a flat surface for precise placement.

How do we prevent delamination on plated boards on edges following thermal cycling?

In order to prevent plate delamination, apply good-quality plated material and observe good surface finishes, optimize the PCB edging plating thickness, and apply thermal shock-resistant coatings. Along with this design improvement, reducing thermal stress and greater bonding of plated material with substrate can prevent delamination.

What is the effect of edge plating on the overall impedance control of the PCB?

PCB edge plating has implications for impedance control, especially at high-frequency signals at the board edge. It is critical that designers account for this by adjusting trace width or edge spacing as required.

PCB Design for Manufacturability Guide: Best Practices

PCB design for manufacturability principles

PCB Design for Manufacturability Guide: Best Practices

In the rapidly evolving field of electronic manufacturing, ensuring reliability and efficiency is a primary concern. Approximately 70% of defects in PCB fab and assembly stem from design errors, highlighting the importance of Design for Manufacturability (DFM). But what exactly is DFM, and how can it be applied?

This guide will explain what DFM means, its main elements, its importance, provide examples, and discuss the software involved. Furthermore, it will cover the PCB DFM checklist, principles, best practices, and common pitfalls to avoid when designing for manufacturing.

What is Meant by Design for Manufacturability?

The engineering methodology known as DFM aims to create products that are easy and affordable to manufacture. This method entails proactively assessing manufacturing requirements, capabilities, and constraints throughout the design stage.

Effective DFM before PCB fabrication promotes collaboration between design and manufacturing teams to ensure effective durability, testing, and assembly.

Differences between DFM, DFA, and DFMA

DFM focuses on addressing issues related to the yield and reliability of bare PCB manufacturing. DFA emphasizes tackling quality and efficiency issues during the PCBA process.

DFMA does not merely add DFM and DFA together, but rather seeks to find the optimal balance between electrical performance, manufacturability, and assembly efficiency through a systematic design review process.

In practical projects, it is advisable to incorporate DFMA thinking at the schematic stage, rather than checking DFM or DFA separately after completing the layout.

Below are some key differences between DFM, Design for Assembly, and DFMA:

Differences	Design for Manufacturability	DFA	Design for Manufacturing and Assembly
Main Goal	Ensure PCB fabrication with high yield and low cost	Ensure components can be mounted quickly, accurately, and reliably	Achieve the lowest total cost by balancing DFM and DFA trade-offs
Key Considerations	Minimum trace width/spacing; Aspect ratio (board thickness/drill size); Annular ring width; Copper distribution symmetry; Material selection (Tg, CTE);	Component orientation and spacing; Number of unique component types; Pad size accuracy; Test point coverage; Manual assembly feasibility;	Prioritization of DFM vs. DFA constraints; Manufacturing cost vs. assembly cost; Time-to-market reduction; Overall profit margin optimization;
Output	Manufacturable Gerber files that meet the fabricator’s process window	Stencil files and placement data that enable fast, high-quality assembly	A fully optimized design package that balances all fabrication and assembly constraints
Interface With	PCB Fabrication House (FAB)	PCBA Assembly House	Coordinates both FAB + Assembly House

Importance of PCB Design for Manufacturability

Early design phase manufacturability issues are addressed by DFM, which leads to:

Cutting Expenses

Proper design for manufacturing and assembly reduces the production costs of PCB projects by optimizing material use, reducing waste, and simplifying assembly processes. Early DFM analysis, which identifies design elements that are expensive or difficult to manufacture, can enable cost-effective alternatives before production begins.

Enhanced Dependability and Quality

By aligning the design with established manufacturing capabilities, DFM reduces the risk of defects, rework, and field failures. The results include improved product quality and long-term reliability, which are especially crucial in high-stakes industries like automotive, aerospace, and medicine.

Quicker Time to Market

Design for manufacturability reduces the number of design revisions and prototyping cycles by detecting manufacturability issues early in the design process. This reduces development timelines and helps companies launch products more quickly and predictably.

Improved Testability and Manufacturability

DFM ensures that the PCB layout, component placement, and assembly processes can be used with standard manufacturing and testing equipment. This makes testing simpler, boosts assembly yield, and enables automated production processes.

Key Phases of DFM Process

The following crucial stages must be prioritized to apply design for manufacturability successfully:

Component Placement

Component placement includes routine orientation of PCB parts that are alike to avoid chances of assembly errors, effective spacing among the parts to create solid solder joints, adequate space away from board edges to prevent damage to parts when handled, and proper positioning of heat-emitting parts to prevent thermal-related issues.

Signal Integrity

Signal integrity guarantees that all data is transmitted correctly. In order to do this, trace widths must be optimized according to current demands, high-speed signals must have even impedance, adequate grounding must be done to avoid electromagnetic interference, and suitable vias that preserve signal quality while being manufactured must be made.

Manufacturing Constraints

Production constraints are referred to as manufacturing constraints. In order to prevent warping, these include producing symmetrical stacks of layers, adhering to minimum feature sizes specified by manufacturers, choosing materials that satisfy mechanical and electrical requirements, and choosing surface finishes that complement assembly procedures.

Design for Manufacturability Software

Valor NPI for DFM Validation

Before production starts, Valor NPI finds possible problems with DFM manufacturing. In addition to pointing out components of your PCB design that are beyond the manufacturing capacity of your suppliers.

It also identifies design elements that could result in reduced yields or field failures.

Vayo DFM

For teams working on PCB and PCBA design and processes, Vayo DFM is an advanced 3D Design for Manufacturability digitization tool. The program intelligently decodes various PCB ECAD file formats, Gerber files, and BOM information.

It simulates the results of PCBA assembly using its large library of 3D components. This encourages zero-defect manufacturing in PCBA production and supports the digital capture of process knowledge.

CAM350

With features like output generation, optimization, and verification, the CAM350 software tool for DFM analysis helps to improve and expedite the PCB manufacturing process.

From handling data input and preparation to analysis, testing, milling, and drilling, it offers solutions for every step of the workflow, culminating in the manufacturing of the final bare board.

Autodesk Fusion

Combining design and manufacturing tools to improve workflow efficiency, Autodesk Fusion is a potent platform for implementing Design for Manufacturing and Assembly. By promoting seamless teamwork, it streamlines procedures and empowers engineers to efficiently design, test, and enhance products.

Design for Manufacturability Principles

Successful PCB design is based on several fundamental DFM ideas. Among these designs for the principles of manufacturability are:

Simplicity in Design

PCB designs should be kept simple. When feasible, use fewer layers and components because this simplifies and lowers the cost of the design. Simple designs have a lower chance of failure and are simpler to correct if they do.

Standardization of Components & Processes

Make use of standard components and manufacturing techniques. Production is accelerated and made more dependable as a result. Most manufacturers are accustomed to standard processes, and standard parts are simpler to replace.

Tolerance Consideration

Consider manufacturing tolerances when designing. Allow a small amount of leeway for changes in part location and size. By doing this, problems with parts that don’t fit during assembly are avoided. Additionally, it lowers manufacturing waste and errors.

Optimized Thermal Management

Consider temperature when designing. Make use of methods like heat sinks and thermal vias. Give warm components some room. In addition to preventing overheating, proper thermal management extends the PCB’s lifespan and dependability.

Electrical Performance Optimization

Make sure the electrical performance is sound. For various currents, use the appropriate trace widths. Create the PCB stack-up with impedance control in mind. This minimizes signal issues and guarantees the PCB operates electrically well.

Testability & Accessibility

Make testing the PCB simple. Add markers and test points for automated testing. Make essential parts available so that major components can be serviced. This facilitates maintenance and allows for the early detection of faults.

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PCB DFM Checklist for Analysis

Below are some key points to check for the DFM analysis before PCB fabrication:

Document and Stackup

Gerber File Integrity

Ensure that all manufacturing layers (copper, solder mask, stencil, silkscreen) and drilling files are complete, using clear naming conventions (e.g., TopCopper.gbr). Additionally, verify that the drilling files include a complete tool size table.

Clear Stackup Structure

It is essential to specify the material type (e.g., FR-4 high Tg), the copper thickness for each layer, dielectric thickness, and the final board thickness. Ensure a symmetrical PCB stackup to prevent PCB warpage.

Routing and Layout

Trace Width and Spacing

Check whether the minimum trace width and spacing are within the manufacturer’s production capabilities.

Avoid Isolated Copper and Sharp Angles

Check and remove isolated copper pads (floating copper) that are not connected to any network to prevent static electricity risks. Additionally, avoid routing that forms angles less than 90° (acute angles) to prevent etching solution residue leading to over-etching.

Differential Signals

Ensure that the spacing for differential pairs is consistent and that length matching is performed as required.

Thermal Pads

Inspect component pads connected to large copper areas to ensure they utilize Thermal Relief connections to avoid excessive heat dissipation during soldering, which can lead to cold solder joints.

Copper Balance

Strive for an even distribution of copper across all layers, or add balancing copper (Thieving) in open areas. Significant unevenness in copper distribution may cause warping during lamination.

PCB DFM Guide: Best Practices

By adopting these best practices, designers can significantly improve PCB manufacturability and efficiency:

Early Involvement in the Design Process

Involve production teams early on. Designs will then be viable and cost-effective to produce. Early involvement in design pinpoints issues and allows the ability to correct them before mass production, saving money and improving product quality.

Simplification and Standardization of Design

Simplify designs by removing parts and unnecessary features. Use standard, readily available components to reduce the cost of manufacture and lead time. Standard components are cheaper and easier to replace and maintain.

Design for Assembly (DFA)

Design for simplicity of assembly. Minimize the number of parts and make them easy to handle and fit. Reduce the need for complex tools. DFA reduces assembly time and cost and improves quality.

Design for Quality

Make products strong and long-lasting by using excellent quality materials. Use rigorous design methodology and consider how the product will be utilized. Easy-to-maintain designs allow for longer-lasting repair and replacement.

Use of DFM Analysis Tools

Use computer software to check designs for manufacturing. The computer program will highlight potential manufacturing issues and suggest modifications. Detection of problems early on saves dollars and improves product quality by making timely revisions to the design.

Collaboration with Suppliers

Collaborate with suppliers in advance to capitalize on their expertise with materials and processes. Suppliers like Tencom can provide useful insight, suggest alternate materials, and suggest design adjustments to make for easier manufacturing without diminishing functionality.

DFM Examples in Various Industries

Consumer Electronics

To avoid tombstoning and misalignment during reflow soldering, solder pad dimensions and spacing for surface-mount devices (SMDs) should be properly designed. In the production of consumer electronics, this Design for manufacturability enhancement directly raises first-pass yield and lowers rework.

Automotive

Employing a small number of common fasteners and connectors for all car models simplifies assembly and inventory, and cuts production costs. In order to increase supply chain efficiency and streamline assembly lines, the automotive industry has widely adopted this DFM strategy.

Aerospace

In the aerospace industry, Design for Manufacturing (DFM) often involves using highly dependable materials and optimizing assembly procedures to reduce failure rates and maintenance requirements. Selecting components and manufacturing techniques that minimize weight and costs while meeting stringent safety and performance requirements.

Medical Devices

Creating parts for medical devices with smooth surfaces and few nooks and crannies to enable complete sterilization and cleaning. This DFM approach improves patient safety and guarantees adherence to health regulations.

Industrial Machinery

Designing industrial machinery with easily upgradeable or replaceable modular components. This DFM method increases product life, decreases downtime, and streamlines maintenance.

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FAQ

What are DFM and DFT?

Design for Assembly (DFA) is designed to make PCBs simpler to assemble, as it entails the design being simple and using common components that are simple to assemble.

Design for Testability (DFT) ensures that PCBs are simple to test when assembled. It is a process of integrating test points and provisions to facilitate automated testing.

Is DFM the same as DFA?

DFM emphasizes creating products that can be manufactured easily and economically. In contrast, DFA concentrates on designing products for straightforward and efficient assembly. Although both strive to improve product production, DFM deals with the entire manufacturing process, whereas DFA focuses specifically on the assembly phase.

What is the DFM strategy?

The DFM strategy is to create PCBs with manufacturing taken into account. It is focused on creating designs that are easy and cheap to manufacture in terms of element placement and manufacturing process simplicity and ease. It works towards minimizing errors and costs and increasing manufacturing efficiency with manufacturing-friendly designs.

What are the most critical DFM considerations for high-frequency PCBs?

For high-frequency PCBs, reducing signal loss, reducing EMI, and maintaining trace width and trace spacing under control are some of the DFM considerations that are crucial. Correct materials must be utilized, and there must be controlled impedance with no sharp trace angles to maintain signal integrity.

Chip on Board Technology: All Things You Need to Know

Chip on Board Technology: All Things You Need to Know

Chip on board removes the packaging of individual semiconductor devices. This makes the final product cheaper, lighter, and more compact. So, what is this technology on a PCB? How are these chips mounted on the PCBs?

This ultimate guide will help you learn more about COB tech, including its types, pros, uses, and materials. You will also know how this tech varies from SMD, the manufacturing process, and how these chips are mounted on the PCBs. You will understand how to design for better chip-on-board assembly.

What is Chip on Board Technology?

COB is an electronic configuration technology that involves various components being assembled together to mount a semiconductor chip on a PCB. It integrates various components to work as a single unit. It is much more convenient than the traditional method of packing with pads or leads.

Difference between Chip on Board vs SMD

Chip on PCB	SMD
Direct die bonding to PCB	Soldered onto PCB pads
Bare die mounted directly on PCB and wire-bonded.	Pre-packaged chip soldered onto PCB.
Encapsulated with epoxy or silicone resin.	Protected in a plastic or ceramic package.
Wire bonding or flip-chip connections.	Uses solder joints (leads, BGA, LGA).
More compact, no extra packaging needed.	Requires more space due to the package.
Better thermal performance, heat spreads directly.	More heat buildup, requires cooling solutions.
Used in LEDs, LCD drivers, and high-density circuits.	Common in consumer electronics, automotive, and IoT devices.

Types of Chip on PCB

There are various types of chips mounted on the boards. Some are:

Dam and Fill

It is the most commonly used encapsulation methodology for the chip on board package application of semiconductors. An epoxy layer surrounds the chip and fills the chip with an encapsulant. It thus creates a dam around the edges that prevents it from being damaged by various other environmental aspects.

There are basically two different ways for the Dam and fill dispense patterns, commonly termed as Spiral Fill and Dot & Line, to use the encapsulated technique. It prevents overflow of the encapsulant, preserves the wire bonds from external factors, and is durable.

Chip on flex

It is an IC chip placed on the top of a flexible printed circuit board that allows the device to have lightweight and flexible structures. In a chip-on-flex assembly, the microchip bypasses the conventional assembly steps needed for individual IC packaging.

This chip-on-board streamlines the overall design and manufacturing process while enhancing performance due to the reduced interconnection length. It has applications in saving space, is lightweight, cost-effective, and has thermal durability.

Flip Chip

Flip chip is an advanced version of traditional COB technology. Unlike standard chip on PCBs where chips are wire-bonded, flip-chip chip-on-board involves connecting the chip with a bump before flipping it onto the substrate.

This enhances the existing benefits of COB, offering greater reliability, improved near-screen performance, superior display quality, a more streamlined manufacturing process, true chip-level spacing, and outstanding RGB lighting effects. Flip-chip chip-on-board LED assemblies provide better heat dissipation, higher lumen output, and more compact designs.

Flip chip COB is used in high-performance computing, RF devices, and advanced integrated circuits where high-speed signal transmission and efficient heat dissipation are critical.

Wire Bonding

Wire bonding is the most traditional method to use the COB in which the semiconductor is directly connected to the substrate, and an electrical configuration is set up using fine wire bonds.

The semiconductor die is placed directly onto the PCB or substrate using adhesive (conductive or non-conductive epoxy).

Fine metal wires are used to connect the die’s bond pads to the PCB, ensuring electrical connectivity. A protective layer of epoxy or resin is applied to shield the die and wire bonds from environmental factors such as dust, moisture, and mechanical stress.

Advantages of Chip on Board

Eliminates IC Packaging steps
Reduces the cost of manufacturing
COB makes the product cost-effective
Alternative to conventional IC packaging methods
Increases lifespan and reduces the overheating problem
Minimize the solder joints in the instrument.

Material Requirements for Chip on PCB

PCB substrate

The PCB substrate is one of the primary building blocks of the Chip on Board PCB. It provides electrical insulation, mechanical support, and thermal management to the system. To accomplish this, FR4 (Fiberglass Epoxy Resin) was chosen since it provides these features at the additional bonus of being inexpensive.

Generally, polyamide is chosen for its high thermal stability and broader application range. High-frequency conduction with lower dielectric performance suitable for RF microwave circuits is accomplished with Rogers. Heat sinking is done using aluminum and copper in power electronics.

Gold and Aluminum wires

They are used to establishing a connection between the PCB and the die as they are cost-effective, have better conductivity, and are reliable.

Surface Finish

A widely used Electroless Nickel Immersion Gold (ENIG) surface finish that provides a smooth, solderable surface with good corrosion resistance.
Electroless Nickel Electroless Palladium immersion gold finish improves bonding reliability, especially with gold bond wires.
Epoxy resins serve as encapsulation material to protect the device from environmental degradation. It forms a protective layer over the wire bonds and die, encapsulating them from moisture, dust, and other environmental threats.

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Common Applications of Chip on PCB

COB technology is widely utilized in the PCB industry, particularly in sectors that demand miniaturization, high density, superior performance, and high reliability. Below are its primary applications across various PCB applications:

LED Lighting and Display

CoB LED lighting enables the high-density integration of multiple LED chips into a compact module. It provides significantly higher luminous density and uniform, shadow-free light compared to traditional SMD solutions, while also benefiting from excellent thermal management that effectively extends lifespan.

Products include chip on board LED light strips, commercial recessed lights, and lighting for medical and photography purposes. In the realm of small-pitch, high-resolution LED displays, chip on PCB technology achieves smaller pixel pitch and higher pixel density by directly soldering RGB LED chips onto the PCB, resulting in finer display quality.

Automotive Electronics Sector

Chip on board leds are widely used in automotive headlights, daytime running lights, taillights, and interior ambient lighting due to their high brightness, excellent shock resistance, and wide temperature adaptability.

In modules requiring high reliability, such as engine control units (ECUs) and tire pressure monitoring systems, COB technology meets stringent demands for vibration and high-temperature performance.

Consumer Electronics

Miniaturized devices such as smartphones and smartwatches utilize chip on PCB for camera modules, flash LEDs, and proximity sensors, while maintaining or improving functionality

COB is also used in smart home devices like smart bulbs and security cameras, where size constraints and thermal management are critical design considerations.

Medical Applications

Medical imaging devices like endoscopes, surgical lighting, and patient monitoring equipment utilize chip on board technology for its miniaturization and superior thermal management.

Portable medical diagnostic devices, including blood glucose monitors and pulse oximeters, leverage COB’s small form factor and efficiency for point-of-care applications.

LED Chip on Board Package vs. SMD LED Package

LED COB tech and SMD tech are the two main packaging methods for current LED lighting and displays. Below are some basic differences between these two packages and how to choose between them for LED packages:

Differences	Chip on PCB LED	SMD LED
Package Structure	Surface light source with multiple chips mounted directly on the substrate	Point light source with chips packaged into individual beads and mounted on the PCB
Optical Performance	Uniform, continuous light emission; no visible pixelation; low glare;	Visible pixelation at close range; moderate uniformity; high brightness;
Lifespan (MTBF)	~50,000 hours typical	~35,000 hours typical
Reliability	Robust; excellent moisture, dust, and impact resistance; fewer failure points	Moderate protection; more individual beads → more potential failure points
Maintenance	Difficult to repair, usually requires the whole module replacement	Easy to repair, and individual beads or modules can be replaced
Cost Structure	Higher initial cost; potentially lower long-term maintenance cost	Lower upfront investment; mature, cost-optimized technology
When to Choose	– Applications requiring high luminous density, small light-emitting surface, and high uniformity – Indoor high-definition displays, control rooms, and high-end retail – In harsh environments	– Flexibility and cost control are essential – A limited budget or requires large-scale deployment – For quick replacement of faulty bulbs. – RGB light strips, landscape lighting, and general illumination

Chip on Board Design Rules and Tips

Below are some key things to consider during chip-on-PCB designs:

Thermal Management

The bare chip on PCB generates a high heat flux density during operation, leading to a decline in chip performance or failure. Utilize heat sinks or thermal pads, ensuring a low thermal resistance contact path between the chip’s back and the PCB.

Avoid voids at the bottom of the chip, as they can create a thermal resistance layer. Do not place the chip directly on a large copper area without thermal resistance optimization.

Thermal Expansion Matching

The CTE of the chip differs significantly from that of the FR-4 substrate. Frequent thermal cycling can cause stress cracks at connection points due to uneven expansion.

Use low CTE PCB materials, such as polyimide (PI) or ceramic substrates, to reduce thermal mismatch stress. If FR-4 must be used, consider adding localized reinforcement layers in the chip mounting area to lower the CTE difference.

Pad and Wire Bonding Design

The reliability of wire bonding during the chip on board process depends on the pad design. The pad surface must be gold-plated (ENIG or electroplated gold).

Pads must be clearly defined by either solder mask defined (SMD) or non-solder mask defined (NSMD) methods. Avoid copper or routing around the pads to prevent the gold wire from contacting adjacent metals during bonding.

Mechanical Fixation and Chip Underfill

Use epoxy resin to secure the back of the chip to the PCB, applying pressure during the curing process to prevent chip displacement.

Inject underfill adhesive into the gap between the chip and the PCB to enhance the solder joint’s resistance to mechanical stress and vibration. It is recommended that the CTE of the underfill adhesive is close to that of the chip.

Gold Wire Routing and Length

Minimize the gold wire length to reduce parasitic inductance and resistance. Make the gold wire as straight as possible, avoiding bends or crossings.

For high-speed signals, gold wires should be kept as short as possible, following the ground plane routing. Maintain the characteristic impedance matching of the gold wires.

Chip on Board Manufacturing Process

Below are the main steps of how the chip on boards are made:

Substrate Selection: Choose a PCB substrate material such as FR4, polyimide, or metal-core PCB, depending on the thermal and electrical needs of the application.
Implement a conductive surface finish treatment like ENIG (Electroless Nickel Immersion Gold) or ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold) to enhance wire bonding reliability on chip on PCB.
The PCB undergoes chemical or plasma treatment for cleaning purposes to eliminate contaminants, ensuring better adhesion for the chip and wire bonds.

A thin layer of epoxy adhesive (conductive or non-conductive substrate) is applied to the PCB at the designated die placement area.
The bare semiconductor die chip is precisely aligned and placed onto the adhesive-coated PCB.
The PCB substrate is heated to cure the adhesive, securing the chip firmly in place to perform the curing process.
The bonding pads placed on both the PCB and the chip are surface cleaned to guarantee an unbreakable connection during the thermosonic bonding mechanism.
Thus, the wire bonds are inspected under a microscope or using automated optical inspection (AOI) to ensure quality and proper connectivity.

Methods of Chip on Board Assembly

Below are some key types of ways that mount the chips on PCBs:

Surface Mount Technology

SMT (Surface Mount Technology) is a commonplace practice to mount chips and diverse components of electrical devices on PCBs. SMT’s pins aren’t configured into the forums, so the PCB is configured with the copper pads for the mounting of the digital components. A solder mask with a combination of solder and flux is implemented on the PCB to use a solder bump that is used for the company attachment of the electronic additives.

The components are positioned into the solder-pasted pads, making use of an automated Pick and Place machine to ensure high accuracy, reliability, and performance. The PCB is saved under a reflow oven that melts the solder paste by way of heating the device. This establishes an electrical and mechanical link between the PCB and chip that solidifies the solder joints.

Through Hole Technology

It is a method of mounting electrical components on a PCB by inserting the leads into already drilled holes. First, the PCB goes through a step where it is prepared with leads and pre-drilled, configured holes. The leads to the THT chip are inserted into the corresponding holes in such a manner that there is proper alignment.

The lead is heated using hand and wave soldering techniques to trim and prevent an accident while the lead is being excessed. Therefore, visual inspection and electrical testing are performed to determine defects, if any.

Advanced Chip on Board

It is the method where the substrate has a smooth and clean surface with the conductive layer that is prepared for bonding the ‘chip’ pads. The solder mask is opened to enable the placement of the chip on PCBs. A silver die-attached epoxy, silicone, conductive adhesive, or acrylate bonds the chip to the substrate.

Bond wires are formed by interconnecting the chip and substrate through wire bonding. This is done by special equipment that places very fine wires to make connections inserted into the device. At last, the COB assembly is encapsulated with an epoxy molding compound or a liquid encapsulant, which serves to protect the chip from damage.

Chip on Board Package Process

Die Attach (Adhesive Dispensing & Placement)

The process starts by applying a conductive or non-conductive adhesive, usually silver-filled epoxy, onto the PCB substrate. Then, the bare die is carefully placed onto the adhesive-coated area using automated equipment or manual alignment under a microscope.

Curing

After placement, the PCB goes to a curing oven where heat hardens the adhesive. This step secures the die to the board and is vital for mechanical stability and thermal conductivity.

Wire Bonding

Fine wires, typically made of aluminum or gold, connect the die's bond pads to matching pads on the PCB. Thermosonic or ultrasonic bonding creates these electrical pathways between the chip and the circuit board.

Encapsulation (Potting)

The die and wire bonds are covered with a protective epoxy resin, creating a "glob top" that protects against physical damage, moisture, and contaminants. This encapsulant also helps with heat dissipation and improves optical properties for display applications.

Testing and Inspection

The assembled COB module undergoes electrical testing, including continuity and functional checks, as well as visual inspection, often using automated optical inspection or microscopy. This ensures bond quality and identifies defects before final integration.

Conclusion

COB manufacturing minimizes size and cost while increasing performance over packaged integrated circuits. This technology is common in LEDs, sensors, automotive electronics, and medical devices.

The selection of materials for Chip on PCB is based on thermal management, electrical performance, reliability, and cost. More advanced applications tend to use gold-plated contacts, epoxy molding compounds, and advanced thermal interface materials, while more cost-effective designs use standard FR4 PCBs and aluminum wire bonding.

FAQ

What are Chip on Board LED lights?

Chip-on-Board (COB) LED lights are a type of LED lighting. In this method, multiple LED chips are directly mounted onto a substrate, which is usually a printed circuit board (PCB). These chips are encapsulated together as a single module. This integrated design results in a high-density, uniform light source. It also offers better thermal management and takes up less space compared to traditional LED packaging.

What types of applications benefit most from COB technology?

COB technology is particularly useful in applications that need high brightness, even lighting, and a compact design. These applications include commercial and architectural lighting, automotive interior and exterior lighting, high-resolution LED displays (especially small-pitch screens), and smart lighting systems.

What is the Difference between PCB and COB?

In short, the PCB is the board. COB is the way of putting chips onto that board. This method removes traditional packaging, which improves density and thermal efficiency.

What is a COB package?

A COB package is an electronic assembly where one or more bare chips are mounted directly onto a substrate, typically a PCB. These chips are electrically connected through wire bonding and are covered with protective resin or epoxy. This packaging improves thermal dissipation, reduces size, and increases reliability.

Semi Flexible PCBs: How to Design and Manufacture?

semi flexible PCB design rules and manufacturing

Semi Flexible PCBs: How to Design and Manufacture?

Compared with a standard rigid PCB, or a flexible or rigid-flex PCB, a semi flexible PCB can be a more flexible and cost-effective solution for fitting into ever-smaller, irregularly shaped spaces in constrained spaces.

This guide will provide you with more information about these semi flex circuit boards, including their structure, materials, pros and cons, when and not to use these PCBs, how they vary from flex PCBs and rigid-flex PCBs, and guidelines for semi flex PCB designing and manufacturing.

What is a Semi Flexible PCB?

A Semi Flexible PCB is a unique type of PCB with specially treated areas where slight bending or flexing can be done. Semi-flexible PCBs are constructed for single or occasional bending, for instance, during assembly into a housing or enclosure.

New products are miniaturizing and becoming more complex. Semi-flex PCBs help designers save space and reduce connectors and cables, which improves reliability. They are especially useful in products where the board needs to bend one or more times during mounting but also gets fixed once mounted.

Semi Flex PCB Structure and Composition

Material composition, flexibility, and layer configurations are some of the important factors that need to be considered to understand the function and structure of the PCB.

Here’s some description of materials used in this special PCB structure and composition.

FR-4 Material

FR-4 is a type of fiberglass that is strengthened by using epoxy lamination to increase its flame resistance and moisture resistance. It provides flexibility to semi-flex PCBs. Some parts of the FR-4 are thinned for contraction without affecting the PCB design, which makes it a cost-effective solution.

Copper Foil

Firstly, base materials such as FR-4 are laminated using a copper foil, which helps in circuit formation. Copper has good conducting properties, which helps to connect the components in the PCB.

Solder Mask

To prevent oxidation, a solder mask is applied to copper traces. This helps in soldering and also protects against short circuits.

Adhesives

Adhesives help to join the layers of flexible and rigid regions, which provides strength.

Other Flexible Materials

Alongside, some of the other materials with different properties can be used in semi flexible PCBs for specific applications. Materials like Polyethylene Naphthalate and liquid crystal polymer also provide variable flexibility and improve thermal efficiency.

How Partial Flexibility is Achieved in Semi Flex PCBs?

Partial flexibility in semi flexible PCBs is achieved by thinning down certain sections of the FR-4 material, which is a substrate material. The thinner sections, so-called semi-flex zones, allow this PCB to curve without fracturing, whereas the rest of this semi flex circuit board remains stiff and strong. Therefore, this kind of PCB can fit all the components within limited spaces.

Layer configuration

The layer composition of a semi flexible PCB is usually a combination of rigid and semi-flex areas. The rigid areas, made of conventional FR4 material, are populated with components, while the semi-flex areas are achieved by thinning the FR4.

This layer combination allows this PCB to bend once without breaking reliable electronic connections and structural support.

Semi Flex Circuit Boards: Pros and Cons

Pros of Semi-Flexible PCBs

Compared to other PCBs like rigid PCBs, flex PCBs, and rigid-flex PCBs, semi-flex PCBs have their own key advantages as follows:

Cost Less

Compared to rigid-flex PCBs, a semi flex PCB costs less, due to using a standard FR-4 substrate rather than polyimide, and with the standard rigid PCB manufacturing process. For a typical 4-6 layer board, semi-flex can achieve cost savings of 20-40% over rigid-flex, making it an accessible option for cost-sensitive projects.

Require Fewer Connectors and Cables

Semi flex circuit boards reduce connectors and cables by adding multiple board functions into one continuous circuit. This integration saves space and removes potential failure points where individual components would otherwise be connected.

Space Saving and 3D Integration

By allowing the PCB to bend and conform to the product housing, semi flexible PCBs support compact and 3D assembly.

A single semi-flex PCB can replace multiple rigid boards connected by cables, dramatically reducing the required footprint. This capability is critical for modern products where internal space is at a premium.

Enhanced Mechanical Stability

Semi-flex PCBs will restrict repetitive bending in particular regions without splitting, as opposed to rigid boards that can break under stress. The longevity of these PCBs makes them appropriate for devices that are open to vibration or movement.

Limitations of Semi-Flexible PCBs

Limited Bend Cycles
Bend Angle Restrictions
Layer Count Constraints in Bend Area
Design Complexity
Manufacturing Precision Challenges
Material and Thermal Limitations
Repair and Maintenance Challenges

Rigid Flex PCB vs Flex PCB vs Semi Flexible PCB

Feature	Flex PCB	Rigid-Flex PCB	Semi flex PCB
Material	Polyimide (PI) as the base material, with rolled copper for the circuits	Combines rigid FR-4 substrates and flexible polyimide (PI) layers	Typically FR-4
Flexibility	Highly flexible	Offers selective flexibility.	Bends only in specific areas
Cost	More expensive than rigid PCBs.	The highest cost, due to complex manufacturing	Lower
Durability	Excellent for repeated bending	Designed to withstand mechanical stress, vibrations, and temperature variations	Good for static bends
Applications	Wearables, medical, aerospace(dynamic)	Foldable phones, medical devices (endoscopes), automotive sensors, and aerospace	Static installs(automotive, consumer electronics, medica, and etc)
Manufacturing Complexity	Higher complexity than rigid PCBs.	Extremely high complexity.	Simpler(depth milling)

When to and Not to Use Semi Flexible PCB?

The decision between using these PCBs or not depends on the requirements of your projects.

When to Use

Use semi flex PCBs when your project requires:

For Static, One-Time Bending
For Constrained Space and Lower Budget
For Moderate Reliability in Fixed Position

When Not to Use

Don’t use these semi flex circuit boards when your project requires:

For Dynamic or Repeated Bending
For High-Flexibility Needs
Extreme Durability
A complex multilayer board structure

Common Applications of Semi Flex PCB

Consumer Electronics

Semi-flexible PCBs are frequently found in devices like cameras, smartwatches, and cell phones. When connected to the mainstream, these PCBs enable consumer electronics to be included in a straightforward, air-efficient form without compromising their functionality.

Medical Devices

For wearable sensors and tiny health monitoring devices in the medical field, these PCBs’ flexibility allows them to be used in devices that require long-lasting, thin designs that are comfortable for patients.

Automotive Electronics

In confined automotive applications such as rearview cameras or dashboard switches, semi-flex PCBs are perfect. Because these PCBs eliminate the need for large cables, the electronics in cars are lighter, more dependable, and simpler to assemble.

Aerospace & Military Equipment

Semiflex PCBs are utilized in defense and aerospace applications where robust yet lightweight devices are required. A semi-flex PCB maintains performance and dependability even when subjected to tight mounting and vibrations.

Semi Flex PCB Design Guidelines

The design of semi flex circuit boards involves providing a one-time bending capability to specific areas based on rigid PCBs. This is achieved through precise depth milling on an FR-4 substrate.

The key to success lies in strictly adhering to the core premise of ‘static bending’ and implementing a set of stringent semi flex PCB design rules. You should consider things as follows:

Bending Area Design

Layer Limitations

The number of copper layers in the bending area must be restricted to 1 or 2 layers. Thicker laminations cannot bend reliably.

Avoid Components and Vias

No components, pads, or vias are allowed in the bending area of these semi flexible PCBs. All holes, pads, and annular rings must be at least 1mm away from the edge of the bending zone.

Routing Direction

The routing in the bending area should be perpendicular to the bending axis to distribute stress evenly. Additionally, traces and blank copper areas should be in a radial pattern. The bending direction should remain consistent (either in the X or Y direction).

Copper Foil Selection

Use high-ductility copper foil in the bending area.

Filling Blank Areas

Fill the blank area in the bending area with non-functional copper to enhance mechanical stability.

Bending Radius

If the bend is too frequent, it can break or crack. This risk can be eliminated by using a safe bending radius.

The minimum bend radius depends on the length of the semi-flex area:

45° bend: Requires 5 mm semi-flex length
90° bend: Requires 10 mm semi-flex length
180° bend: Requires 20 mm semi-flex length

Layering and Symmetry

The layering design of the entire semi flex PCB must remain symmetrical, which aids in forming a stable neutral axis during bending.

Use Curved or Rounded Corners

Sharp corners created when the traces change direction will become stress concentration points in the flexible area. Under bending forces, these sharp corners lead to tears in copper traces. Always use curved or rounded corners for traces entering the flex region to distribute stress evenly.

Thermal Management in Flex Areas

On a semi-flexible PCB, heat may accumulate in flexible areas. Over time, prevent the PCB from deteriorating by using the right materials and taking heat flow into account.

Apply Hatched Polygon for Copper Planes

When subjected to bending forces, a solid copper ground plane may crack, tear, or become rigid, defeating the purpose of the flexible section. Instead, use a hatched polygon (a mesh or grid pattern). This maintains electrical connectivity while preserving the structural integrity and flexibility of the flexible area.

Semi Flexible PCB Manufacturing Process

Below are the key steps in the manufacturing process of these semi flex circuit boards:

Design

The fabrication process begins with a semi-flex PCB design, which is done using various design software. Engineers determine the rigid and flexible areas that define the bending and stiff regions.

Standard Rigid Board Fabrication

This stage is similar to the standard rigid PCB manufacturing process, including cutting materials, inner layer circuit creation (dry film, exposure, development, etching), AOI, browning, lamination, drilling, and electroplating.

Apply Flexible Coating

In areas of the board that require bending, apply a flexible coverlay or flexible solder mask to prevent cracking of the coating during bending of these semi flexible PCBs.

Depth-Controlled Milling

This is the most critical step in the manufacturing of semi-flexible PCBs. Before the finished board is milled out from the production panel, a CNC milling machine is used to perform precise depth milling on the backside of the designated bending area.

Flex Area Processing

In Flex area processing, bending areas are treated with special care. Engineers reduce the thickness of material or add flexible layers to bending areas, so they do not shatter upon bending.

Quality Control Measures

Finally, implement quality control measures like electrical testing, functional testing, AOI inspection, and more to ensure the final quality before packaging and delivery.

Best Practices of Semi Flex PCB Fabrication

Below are some key things to consider during the semi flexible PCB manufacturing process:

Materials Selection

Use standard FR-4 material as the substrate rather than polyimide. It is recommended to use FR-4 materials with a Tg of 135°C.

Flexible Solder Mask in Bend Areas

Traditional solder masks crack and flake when bent. Use a flexible solder mask(flexible LPI) in the bending area. And use standard green solder masks on rigid areas.

Controlled Depth Milling Accuracy

Uneven residual thickness from imprecise depth milling will compromise the bending performance and also lead to fractures.

During depth-controlling milling, board thickness uniformity, prepreg thickness, resin content, and milling tolerance must be fully matched to the design’s bend requirements and define the optimal remaining thickness range.

Two-Step Lamination Process

To solve the uneven residual thickness, you can utilise a two-step lamination process and low-flow prepreg materials.

During the pressing process, a 0.5–1.0mm thick FR-4 backplane supports both sides, preventing the bonding area from sinking or the flexible region from cracking.

Implement Testing to Avoid Defects

To ensure that the boards meet the required quality, reliability, and more for their intended “flex to install” applications, you will need to implement various tests to prevent any defects or issues.

Those tests include electrical testing, flying probe testing, bending and mechanical testing, and reliability testing.

Standards for Semi Flex Circuit Boards

Below are some key standards and certifications for semi flexible PCB manufacturing and assembly:

Industry Standards

IPC-2223: The fundamental standard for semi flex PCB design, defining parameters like bending radius and layer counts, and more.
IPC-6013: It defines product classifications (e.g., Class 2, Class 3) and the inspection standards that must be met.
IPC-4101: This standard regulates the rigid substrates used in these PCBs, such as FR-4.0 Tg 135°C materials.
IPC-A-610: This is the acceptability standard for electronic components, providing guidelines for the assembly and inspection of semi-flexible PCBs.
J-STD-001: This standard specifies the requirements for soldering electrical and electronic components, materials, and processes.

System Certification

ISO 9001: The most fundamental and widely recognized quality management system certification for PCB manufacturers.
IATF 16949: If semi flexible PCBs are utilized in the automotive sector, manufacturers must obtain this certification.
ISO 13485: Semi flex PCB factories catering to medical device applications must comply with the requirements of this system.
ISO 14001: This certification indicates that the manufacturer meets international standards in environmental management.
UL: This certification guarantees that semi-flex PCB products meet safety and flame retardancy standards. The rigid sections are subject to UL 796 standards, while the flexible parts adhere to UL 796F standards.

FS Circuits: Advanced & Professional Semi Flex PCB Factory

With over 18 years of experience in the PCB industry, FS Circuits is committed to providing semi-flexible PCBs at lower prices and higher quality. We deliver turnkey semiflex PCB fabrication and assembly services for various applications, including automotive, medical, consumer electronics, industrial control, telecommunication, and moand more.

With complete equipment and professionals, we provide free DFM review, one-on-one engineering support for your semi flexible PCB manufacturing and assembly, and can optimise your design.

With strict quality control and management, our high-quality semi rigid flex PCBs are certified with ISO 9001:2015, ISO 14001:2015, RoHS, REACH, and more.

Get in touch with us to design your next smart semi-flex PCB solution!

FAQs

Can semi-flex PCBs support high-frequency or high-speed signals?

Yes, it does support high frequency when designed with proper materials like low-loss FR4 or controlled-impedance layers with suitable model practices. Also, signal integrity is often better than in systems with connectors and terminals.

What recent advancements have improved semi-flexible PCB durability?

Recent advancements feature adhesiveless constructions that wipe out delamination issues, insulating layers with high tear strength, laser-defined flex windows for more precise control, and specialized copper treatments that increase flex life by reducing the risk of copper cracking during repeated bending.

Is local production of semi-flexible PCBs more feasible with new technologies?

Digital manufacturing, laser processing, and automated handling system breakthroughs are making smaller-scale, local production of semi-flex PCBs ever more feasible. This enables quicker prototyping, reduced shipping expenses, and better intellectual property protection for sensitive designs.

Are there any known attempts to make semi-flexible PCBs stretchable and electronics-friendly?

Yes, hybrid circuits are being created that incorporate stretchable sections with rigid and flexible regions. They use serpentine trace patterns, bespoke elastomeric substrates, and novel interface methods to create “rigid-flex-stretch” boards that not only accommodate bending but also stretching in particular areas, particularly valuable for such applications as next-generation wearables and conformable medical devices.

How do semi-flex PCBs enhance mechanical reliability in rugged environments?

It can be carried out by eliminating fragile connectors and solder joints in tight spaces, as they offer better vibration resistance and long-term durability in severe conditions like motor vehicles or aerospace environments.

SMT PnP Process: Best Practices and Tips

SMT assembly technology has transformed electronics production with the capacity to mount components directly onto printed circuit boards. An essential part of the SMT PnP machines used in the process is the Pick and Place machine, which deposits the components automatically at high speed and accuracy. One of the critical stages during SMT PCBA is the SMT PnP process that deposits the components automatically at high speed and accuracy.

The current article discusses the core concepts of the SMT PnP process, including its components, how those SMT pick and place machines work, benefits, and step-by-step execution for maximum efficiency. You will also learn more about SMT workflow management tips and how to solve those challenges during this PnP process for SMT automation.

What is the SMT PnP Process?

SMT PnP, which is also called SMT pick and place, is an automated and critical process in modern PCBA for SMT automation. During the SMT PnP process, high-speed robotic machines precisely pick surface-mount components from feeders and place them onto solder-pasted pads on a circuit board.

Relying on vacuum nozzles, vision systems that verify component orientation and board fiducials, and sophisticated software, this process optimizes component placement efficiency in the SMT process.

Key Components in the SMT PnP Process

Surface-mount technology (SMT) pick and place (PnP) machines are at the heart of today’s electronics. They are used to integrate component assembly into the PCB with very high accuracy. Hence, this feature of SMT PnP makes its use essential in many high-powered electronic devices.

Some of the major components of SMT PnP are:

Feeder system

This system supplies the electronic components to the pick and place machines. Larger feeders and small feeders supply components based on their sizes in the machines.

Placement head

The placement head is the component that picks the components and puts them into the machine. Small parts are placed at very high speeds, whereas larger ones are picked up and transported into the PCB. The placement head rotates to ensure the perfect placement of the parts.

Reflow Soldering Oven

This helps maintain soldered connections by controlling the temperature for soldering. Proper soldering ensures firm and rigid solder joints, which do not harm the rest of the component as well.

Control system

To monitor how the components are placed and the overall SMT PnP process, a camera is mounted on the system along with computerized software, called a control system. It helps in detecting solder defects and also checks if the parts have been misplaced.

Rework Station

This component allows the parts that are defective or misplaced to be included. It suggests more precise tools for the replacement, thereby ensuring uniformity in the manufactured PCBs.

Conveyor System

The conveyor unit helps to pass the PCBs through various stages of the SMT PnP process. At a uniform speed, a belt moves the component through the machine. It also works with the placement head to fit the components precisely into the board.

Vision System

A camera takes multiple snapshots of the different components and the PCB to help align the parts properly, which are analyzed by the software to provide information on their position and rotation for precise SMT pick and placement.

SMT PnP: Why Implement It?

Automated pick-and-place in SMT brings speed, efficiency, production accuracy, and minimum human errors, which reduces time and cost for high-quality assembly. The primary advantages explained in detail are:

Increased Speed

The thousands of components placed in an hour using SMT PnP machines show that they are far faster than human beings. It incorporates high-speed placement from manufacturers to meet very high production rates, while faster SMT assembly implies a faster product turnaround.

Accuracy Improvement

Sophisticated vision systems allow automated assembly to ensure the right alignment for placement of components. Errors and soldering defects have been eliminated through an automated SMT workflow. Thus, a high level of accuracy provides reliability and superior performance in electronics.

Scalability

SMT PnP machines support small to high-volume PCB assembly. A company can scale up without any impact on the quality. The different specifications and designs of products will have their adaptability by this SMT automation.

Low Labor Cost

Apart from features like offline production setup that reduces downtime to nearly zero, the elimination of manual component placement in the SMT PnP process also minimizes labor costs and human error. Funds are allocated to development and quality control.

Better Production Throughput

The SMT PnP process delivers exceptional throughput with higher placement speeds. With high speed, automated features such as auto-setting feeders (ASF) and simultaneous front/rear operations, the SMT PnP process reduces machine downtime and allows single-pass assembly of complex boards with thousands of components.

Superior Quality Assurance

In order to ensure early defects inspeciton and correction, the SMT pick and place process has integrated multiple inspection checkpoints like SPI, pre-reflow AOI, post-reflow AOI, and X-ray. Moreover, advanced vision systems in this process also inspect component orientation, polarity, and accuracy in real time.

This results in industry-leading first-pass yields exceeding 99.99%, making it essential for zero-defect industries like automotive, medical, and telecommunications.

What is the SMT Pick and Place Machine?

An SMT PnP machine is an automated robotic equipment for PCBA for accurately placing surface-mount components, such as capacitors, resistors, and integrated circuits, onto the PCB.

The device then drops the parts into assigned positions on the circuit board. New devices deposit thousands of components per hour. They can work with components as small as sand grains. The majority of Pick and Place Machines employ optical systems to deposit items with precision.

They are essential in electronics manufacturing because they work several times faster than the human hand. Hobbyists and small businesses utilize small machines, whereas large industrial models cost hundreds of thousands of dollars.

These SMT PnP Machines have revolutionized SMT automation by providing more speed, less error, and the ability to manufacture complex devices like smartphones, computers, and medical devices.

The SMT PnP Process: Step-by-Step Guide

DFM & Data Preparation

Before production, prepare data files like the Bill of Materials (BOM), Pick-and-Place file, and Gerber data. Then implement a DFM check to verify component footprints, pad spacing, and fiducial marker placement to correct design errors before physical assembly begins.

Load the Bare PCB onto the SMT Line

Manually load or automatically load the bare PCBs onto the conveyor rail for SMT PCBA. Then the board is conveyed to the work position and mechanically clamped or held by vacuum, establishing a precise reference for all subsequent processing steps.

Solder Paste Application

Apply solder paste to the PCB pads with a stencil or screen printing. This paste acts like a binder medium to join the components; it is a mixed material of tiny solder balls and flux. Applying paste when soldering ensures proper electrical and mechanical contacts.

Component Placement

In this procedure, an automated pick-and-place machine picks up the SMT components like resistors, capacitors, and ICs and places them exactly on the PCB. Precision is essential, as misplaced components may lead to faulty connections and circuit failure. The SMT PnP machine takes directions from a vision system.

Inspection

After component placement, use an Automated Optical Inspection(AOI) system to scan for placement defects. This inspection aims to find any missing parts, misplaced or incorrectly placed parts that will affect the functionality of the final PCBs. Early detection like this can reduce the defect limit.

Reflow Soldering

Then the PCB is carried through to a reflow oven and heated precisely to a high temperature. Melting the solder paste and solidifying will produce excellent electrical connectivity between parts and the board. This ensures that all components are mechanically attached and electrically connected during the SMT PnP process.

Cleaning and Testing

After reflow soldering, clean the excess flux residues away using a solvent or ultrasonic cleaner. Implement testing of the PCB functionality to check whether all the SMT components are soldered correctly and the circuitry functions as expected after the SMT pick and place.

Final Inspection

Implement AOI inspection, visual inspection, and more testing to check for any cosmetic defects or not and whether it is within expected quality levels. It is the last stage of detection of defects that have been missed before the unit PCBs are ready for packaging and shipment for use devices.

How to Solve Issues during SMT PnP Process?

There are a few challenges and problems in the SMT Pick and Place process. The solutions are below:

Challenge	Solutions
Component Misplacement	Use vision systems for accurate placement. Calibrate tools from time to time.
Nozzle Pickup and Release Failures	Regularly inspecting and cleaning the nozzles, replacing worn parts and monitor the pressure
Solder Joint Voids	Ensure adequote preheating and controlled cooling, and implement vaccumm reflow soldering if possible.
Tombstoning	Design symmetrical pads, ensure a balanced thermal paths, optimize reflow soldering temperature, and improce the stencil design.
Cold Solder Joint	Ensure sufficient reflow soldering temperature and time
BGA Solder Balls	Use nitrogen in the reflow process, ensure enough amount of solder paste
Excessive or insufficient solder paste application	Optimize stencil design, enhance control of solder paste printing, and regularly clean the stencil
Vision System Errors	Maintain optimal lighting conditions, use advanced vision algorithms with pattern recognition for fine-pitch ICs
Machine Downtime	Perform routine maintenance. Use real-time monitoring
Insufficient Inspection	Use inline AOI systems for early defect detection.
High Labor Costs	Crank up SMT automation to reduce manual effort.
Supply Chain Disruptions	Use good suppliers. Keep buffer stock.

SMT Workflow Management Tips

Below are some best practices for enhancing your SMT line efficiency and tips for your effective SMT PnP process.

Process Management and Line Balancing

Set up a Standard SMT Line

A standard SMT production line should be configured in the following order: Screen Printer → SPI (Solder Paste Inspection) → Pick and Place Machine → Reflow Oven → AOI (Automated Optical Inspection) → Testing/Repair.

Conduct Line Balancing Analysis

Perform a line balancing analysis to ensure a balanced workload among those SMT PnP machines. An effective strategy is to use only half of the available feeder slots, utilizing the other half for offline feeder changes to reduce downtime. Advanced line balancing software can optimize component allocation and minimize changeover time.

Manage Production Line Bottlenecks

Shorten operators’ walking distances through proper equipment layout and increase conveyor speeds where feasible. Ensure that infrastructure such as ESD flooring, compressed air, and buffer conveyors are planned before SMT pick and place equipment arrives.

Data Quality and Equipment Setup

The SMT PnP process not only relies on the speed of the machine, but also on the settings of the feeders, component center data, package orientation, nozzle matching, panel support and the quality of the preparation in upstream printing.

The weak data and mechanical details will lead to compromised accuracy, output, and yield of the entire placement process.

Ensuring High-Quality Data

Ensure that the library origin, including center coordinates, rotation direction conventions, package height, pick points, and feeder assignments is correct, and the rotation rules match the orientation of the components on the tape.

Correctly Setting up Feeders

Pre-structured feeder preparation is essential for minimizing changeover time on the placement machine. A picking list should be automatically generated based on the work schedule, controlling material supply as needed.

Optimizing PCB design for SMT assembly

Omit fiducial marks to accurately position the QFP and BGA type components. And align the SMT components in the same direction. Tooling strips are also important, especially in tight PCB spaces.

Quality Control and Process Monitoring

Implement Statistical Process Control (SPC)

Apart from rigorous SPI and AOI inspections, also implement SPC to monitor the SMT PnP process through control charts, capature thoses drifts before the PCB defects occur, reflecting the process itself rather than the scrap bin.

When control charts only display common cause noise, the process is in a controlled state—no intervention is needed. When special causes are indicated, it is crucial to identify and eliminate that specific cause.

Operator Training and Maintenance

Structured Operator Training Program

Implement an operator training program like an IPC training course, covering essential knowledge such as solder paste storage, thawing, mixing, stencil cleaning, and print inspection. Training should also instruct operators to promptly stop and report when they detect abnormal patterns, rather than treating defects as isolated incidents during the SMT pick and place process.

Strict Material Management

Maintain strict control over component inventory, including FIFO (first in, first out) rotation. Use barcode/RFID verification to ensure the correct material-feeder allocation. Establish a material error-proofing mechanism to prevent incorrect components from being placed.

Leverage Automation and Smart Technologies

Integrate MES (Manufacturing Execution Systems) and AI-driven optimization to automatically adjust process parameters and predict defects.

Balance Speed, Flexibility, and Cost

Make strategic equipment choices based on production needs. Choose high-speed SMT PnP machines for high volume SMT assembly, while flexible machines for high-mix production. Use value stream mapping to identify and eliminate waste in the process.

Why Choose FS Circuits for Your SMT PnP Efficiency?

With over 18 years of experience for EMS PCB manufacturing and turnkey PCB assmembly, FS Circuits has kept “quality, service, cost-effectiveness and sustainable growth” as the key of our development.

With 8 automatic SMT pick and place lines, advanced SMT PnP machines like Samsung SM471/482/481, Fujifilm CP8/6 series, electric feeders, we perfectly achieve 01005 SMT precision, and support common IC, BGA, QFN, PLCC, other components of precision package components assembly.

Also with professional enigineers, expertise in global sourcing, we deliever cost-effective, one-stop, and advanced SMT PCBA servies ensuring SMT PnP efficiency, tailored to your project needs in various applications like telecommunications, smart home, automotive, industrial control and more.

FAQ

What is the working principle of an SMT pick and place machine?

It uses a vacuum nozzle to pick components from feeders, a vision system to align them using fiducial marks, and a high-speed gantry to place them precisely onto solder-pasted PCB pads.

How much does a PCB pick and place machine cost?

PCB pick and place machine costs range from $5,000–$15,000 for benchtop/entry-level models, $30,000–$80,000 for mid-range production machines, and over $150,000 for high-speed, multi-head systems used in volume manufacturing.

What are the differences between PnP and SMT?

PnP (pick-and-place) is a single sub-process within SMT automation, and it focuses on component placement. SMT encompasses the entire assembly flow, including solder paste printing, PnP placement, reflow soldering, and inspection.

IMS PCB: Material Properties, How to Design and Make?

IMS PCB: Material Properties, How to Design and Make?

IMS PCBs are specialized circuit boards featuring a metal substrate with improved heat dissipation. They provide less overheating, longer component life, and better performance.

This ultimate guide will help you learn more about these metal core PCBs, including how they vary from FR-4 material, material properties, types, stackup, applications, design guidelines, manufacturing process, and introduce a reliable IMS PCB manufacturer like FS Circuits.

What is IMS PCB?

A circuit board specifically designed for heat management is known as an IMS PCB, or metal core PCB. A thin dielectric layer, a copper circuit layer, and a metal base, typically copper or aluminum, are its three main layers.

A built-in heat sink is the metal substrate. Heat transfer is permitted while electrical insulation is provided by the dielectric layer. When in use, these PCBs effectively remove heat from electrical components. Component failure and overheating are avoided by the design. In high-power applications where the typical PCB would fail from heat, they are essential.

IMS PCB vs. FR4 PCB: What are the Differences?

Insulated metal substrate PCBs would be appropriate for high-power components like LEDs and automotive electronics. FR4 PCBs made from fiberglass would be better for general electronics with low power demand. The two are contrasted below.

Feature	IMS PCB	FR4 PCB
Thermal Conductivity	Higher( 1–7 W/m·K, depending on dielectric)	Lower (~0.3–0.4 W/mK)
Base Material	Metal(Aluminium/Copper)	Fiberglass(FR4)
Heat Dissipation	Excellent	Poor
Cost	Higher material and manufacturing costs	Lower cost
Mechanical Strength	Higher mechanical rigidity and strength	Adequate mechanical strength
Electrical Insulation	Providing electrical isolation while maintaining thermal paths.	The entire substrate acts as an electrical insulator; no dedicated thermal layer.
Design Flexibility	Typically limited to single- or double-sided designs	Supports single-sided to very high-density multilayer designs with greater flexibility.
Typical Applications	LED lighting, power converters, automotive electronics, and other thermal-critical applications.	General-purpose electronics, consumer devices, low-power circuits, and most standard PCB applications.

Common Types of IMS PCBs

Depending on the performance requirements, these metal core PCBs are made for a variety of applications. Single-layer, double-layer, multi-layer, flexible, and hybrid IMS PCBs are a few of these. Because of their many advantages in terms of flexibility, complexity, and heat dissipation, they are perfect for a wide range of applications, including power electronics, LED lightbulbs, and automobiles.

Single-layer IMS PCB

These PCBs have one layer of the circuit on a metal base. They are easy to design and manufacture. Single-layer PCBs are used extensively in power supplies and LED lights. They offer good heat dissipation for general applications.

Double-layer IMS PCB

An insulating layer sits between the two circuit layers of a double-layer

insulated metal substrate PCB. For more intricate circuits, they offer improved performance. Electrical applications for double-layer PCBs are found in both industry and automobiles. They effectively manage heat while accommodating more electrical connections.

Multi-layer IMS PCB

Multiple layers of circuits stacked on top of one another make up a multi-layer insulated metal substrate PCB. They are made for cutting-edge uses that demand strength and efficiency. They are frequently used in aerospace, telecommunication, and medical applications. For intricate electronic systems, they have outstanding heat management capabilities.

Flexible IMS PCB

This PCB is flexed and mounted in tight areas. They are used in wearable devices, car lights, and medical equipment. Flexible PCBs perform better in heat dissipation. They help in the reduction of electronic device size and weight.

Hybrid IMS PCB

To obtain certain qualities, a hybrid insulated metal substrate PCB blends several materials. They are used in high-frequency applications and power electronics. They offer better thermal and electric performance. They can be used in specific sectors, such as renewable energy and aerospace.

Structure of IMS PCB Stackup

These MC PCBs have a three-layer composition and excellent thermal management. Each layer serves a distinct function and cooperates to provide effective heat dissipation while preserving electrical performance. The application’s thermal requirements and financial constraints are taken into consideration when choosing the materials.

Base Metal Substrate Alternatives

The thickness of the most common base IMS printed circuit board material, like aluminum and copper, is typically between 1.0mm to 3.0mm.

Dielectric Layer Compositions and Properties

This thin layer uses ceramic-filled polymers that permit heat transfer while providing good electrical insulation. The thickness ranges from 50 to 150 microns. IMS PCB thermal conductivity is 1–7 W/mK. Although it costs more, the material with a higher thermal conductivity is superior.

Circuit Layer Specifications

The copper foil circuit layer thickness is between 35μm and 210μm. Typical copper weights include 1oz, 2oz, and 3oz. HASL, ENIG, OSP, and immersion silver are surface finishes for copper protection and solderability.

Metal Core PCB Materials

Aluminum

Aluminum is the most widely used base material for IMS printed circuit boards due to its low cost and good thermal conductivity. Although copper is more expensive and heavier, it also has a higher thermal conductivity.

Copper Core

Copper, the base metal used in insulated metal substrate PCBs, has a higher thermal conductivity than aluminum, making it ideal for high-power and high-frequency applications that require the greatest amount of heat dissipation.

Steel Core

Compared to copper or aluminum, steel core insulated metal substrate PCBs have a lower heat conductivity but greater mechanical strength and rigidity. They are appropriate for uses where structural stability is needed.

Properties of IMS PCB Materials

Insulated metal substrate PCBs possess numerous advantages over standard circuit boards. Their metal substrate enhances heat dissipation, thereby ideal for high-power devices. Below are the primary features making them a top choice in different industries.

Excellent Heat Dissipation

These PCBs are designed to conduct heat away from components. The metal base, usually aluminum or copper, helps in thermal conductivity. This prevents overheating and enhances the functioning of electronic devices.

Higher Reliability Under Hostile Environments

Insulated metal substrate PCBs can endure high-temperature operations and usage that is highly powered. Metallic substrate application offers greater strength compared to the typical PCB. The PCB endures thermal expansion and contraction, and thus reduces the likelihood of destruction.

Eliminates Heat Sinks Required

These PCBs dissipate heat naturally, reducing the need for extra cooling systems. This simplifies product design and reduces costs. The lack of large heat sinks allows for smaller electronic products.

Improves Component Life

Proper heat management avoids overheating electronic components. Lower operating temperatures reduce component stress, eliminating early failure. IMS PCB thermal resistance allows for long-term dependable performance.

Low CTE

The CTE of these metal core PCBs is low, reducing mechanical stress during thermal cycling and making them less prone to warpage, fracturing, and solder joint fatigue.

High Current Capacity

The thick metal core provides low impedance, allowing for stable power distribution and continuous high-current flow without localized overheating.

Fire Resistance

IMS PCBs are less vulnerable to fire compared to FR-4, making them suitable for high-power or high-temperature environments.

Applications of IMS Printed Circuit Boards

LED Lighting Systems

Insulated metal substrate PCBs work great with LED applications through efficient heat dissipation from light-emitting diodes. It prevents thermal degradation and extends the life of LEDs significantly. Even heat dissipation enables stable light emission and color rendition with aging.

Power Converters and Supplies

Power supplies generate significant amounts of heat in the process of voltage conversion. Insulated metal substrate PCBs manage this thermal load very efficiently. The metal substrate constitutes a built-in heat sink, and there is no need for large external cooling components.

Automotive Electronics

Today’s automobiles rely on numerous heat-generating electronic modules. Insulated metal substrate PCBs are suitable for engine control units and LED headlight modules. They can withstand the wide temperature range and vibration found in automotive environments.

Solar Power Inverters

Solar inverters convert DC power from panels to AC energy for domestic use in the new energy industry. The conversion processes generate high heat levels during operation. Insulated metal substrate PCBs help maintain optimal operating temperatures for maximum efficiency and system life.

Partner with Reliable IMS PCB Manufacturer

With 20 years of professional PCB manufacturing and PCBA experience, we are dedicated to streamlining our operations to create economical yet high-quality IMS PCBs.

Get a Quote

FS Circuits

Metal Core PCB Design Guidelines

Below are some key things to consider during IMS PCB design:

Metal Core Selection

The most commonly used metal core for these IMS PCBs is an aluminum substrate, offering a high cost-performance ratio and lightweight properties. The copper substrate has exceptional thermal conductivity, making it ideal for high-power applications, though it is heavier and more expensive.

Heat Dissipation

Place the high-heat-generating components centrally on the aluminum substrate to achieve the shortest heat dissipation path. Maintain an exposed area of aluminum substrate directly beneath the heat source. It is recommended to use large solid copper foil to enhance thermal conductivity. Utilize thermal vias and place them under those or near high-power components.

Electrical Insulation

Utilize a high-performance ceramic-filled resin insulation layer to achieve better thermal conductivity. Select and determine the thickness of the insulation layer based on the operating voltage.

Keep a safe distance between high-voltage lines and the edges of the aluminum substrate; the aluminum substrate itself cannot serve as a conductive hole, and all inter-layer electrical connections must be made through external wire soldering or jumpers.

Component Placement

Place heat-generating components evenly to avoid localized hotspots, and keep them close to the area with direct access to the thermal vias. Keep temperature-sensitive components away from high-temperature areas.

Consider airflow and external heat sink connections. Avoid placing multiple high-power devices too close together unless thermal analysis confirms reliability.

Routing

Determine the width and thickness of high-current traces based on the current-carrying requirements to prevent sharp angle bends, current concentration, and localized heating.

Avoid routing signal lines beneath the heat sink pads of heating components, as this can disrupt the thermal conduction path and prevent signal integrity issues caused by high temperatures.

Grounding Design

Implement multiple reliable grounding points on the metal base layer, with at least three grounding holes evenly distributed across the substrate. This approach enhances electromagnetic shielding to improve EMC performance and helps avoid issues such as static electricity accumulation and insufficient voltage withstand.

Manufacturing Processes of Metal Core PCBs

Metal Base Preparation

The metal substrate of aluminum, copper, or other metals is cleaned and prepared. Surface treatments involve micro-roughening to improve adhesion.

Dielectric Layer Application

Thermally conductive insulating material is applied to the metal base. Layer thickness is precisely controlled to balance thermal conductivity against electrical insulation.

Copper Foil Lamination

Copper foil is laminated on the dielectric layer by applying pressure and heat. This provides the foundation for mounting components and traces on the circuit.

Circuit Patterning

The circuit pattern is created by photolithography and etching. Chemical reactions are carefully regulated in order not to undercut fine traces.

Surface Finishing

Plating surface finishes such as HASL, ENIG, or OSP for exposure protection of copper. The selection of the finish defines solderability and reliability in the long term.

Mechanical Processing

Drilling, routing, and cutting to final dimensions. Special carbide tools need to be employed due to the metal substrate's hardness.

Testing and Inspection

Electrical testing and thermal performance certification. This ensures that the board meets electrical functionality as well as thermal dissipation specifications.

Thermal Stress Relief

Thermal heat and cool cycles are under control to reduce internal stresses. This improves long-term reliability when thermal cycling is applied.

Fabrication Techniques

To achieve optimal thermal performance, IMS PCB uses specialized manufacturing processes. The surface of the substrate metal is treated to improve the dielectric coating's adherence. To achieve a balance between electrical isolation and heat conduction, high thermal conductivity dielectrics are used precisely.

Quality Control Considerations

Insulated metal substrate PCBs quality assurance addresses thermal performance qualification and structural integrity testing. Tests of thermal resistance ensure that the dielectric layer meets prescribed dissipation of heat limits critical in high-power devices. Adhesion tests between the layers prevent delamination upon thermal cycling.

Meet Industry Standards and Certifications

IMS PCB manufacturing meets rigorous industry standards that ensure reliability for critical applications. Base material specifications are governed by IPC-4101 standards and performance standards for metal base boards by IPC-6012. UL certification is required to meet safety standards, and most IMS PCBs must undergo UL 94V-0 flammability ratings.

FS Circuits: Advanced and Reliable IMS PCB Manufacturer

With over 18 years of experience in the PCB industry and production lines for materials like aluminum, copper, and other metals, FS Circuits delivers advanced and reliable IMS PCB manufacturing and turnkey metal core PCB assembly services in various applications like automotive, telecommunications, LED lighting, new energy, and more, tailored to your project needs.

Conclusion

To sum up, the insulated metal substrate PCB is a key component of contemporary electronics that requires excellent thermal control. It plays an essential role in everything from the LED lighting that lights up our surroundings to the power converters found in electric cars and telecom networks.

Using a metal core PCB is not just a choice when your design has issues with reliability, size, or thermal performance; it is a calculated move to create a more durable and reliable electronic product.

FAQ

What is the thermal conductivity of Insulated metal substrate PCBs?

The critical dielectric insulation layer in an insulated-metal-substrate (IMS) PCB normally has a thermal conductivity between 1 and 8 W/m·K. The heat-spreading base is provided by the metal substrate, which is typically copper (~400 W/m·K) or aluminum (~200 W/m·K).

What is IMS material?

Insulated Metal Substrate is what “IMS” stands for. It describes a PCB structure that consists of a copper circuit layer on top of a thin, electrically insulating, but thermally conductive, dielectric layer on top of a metal base plate (typically copper, but occasionally aluminum).

How do insulated metal substrate PCBs execute the thermal management process?

The metal core PCB’s metal base gives the circuit board more support, and the dielectric layer has the ability to dissipate heat and provide dielectric strength. This makes it possible for PCB designers to produce smaller PCBs. High-density and compact PCBs frequently produce more heat, but IMS PCBs’ metal base aids in heat dissipation more efficiently, improving the board’s thermal performance and prolonging its life.

PCB vs PCBA: Key Differences and How to Choose?

In today’s fast-paced electronics manufacturing, it’s easy to confuse PCB and PCBA when designing electronics and ordering. Even though PCB and PCBA sound and look similar, they vary from each other in many aspects.

So, what are the differences between PCB vs PCBA that allow PCB engineers and designers to successfully distinguish between these two items?

This article will expand on the crucial differences between PCB and PCBA, what happens from bare PCB to PCBA, how they relate to each other, and how to choose between PCB manufacturing and PCB assembly services. You will also know why to partner with FS Circuits for advanced PCB manufacturing and assembly services.

What is a PCB?

The Printed Circuit Board (PCB) forms the basic platform of every electronic product that you use today. A bare PCB before manufacturing and assembly is made out of non-conductive substrates like FR4 with conductive routes etched onto the substrate using copper. These interconnect the various components of your circuit, such as resistors, capacitors, and microchips.

In this sense, these blank PCBs can be thought of as the “skeleton” of your circuit. After designing and producing, the bare PCBs are ready for PCB assembly. With different requirements for flexibility, layer count, and performance, PCBs can be categorized into various types.

For more details about various types of PCBs, you can refer to 11 Essential PCB Types That Transform Electronic Design 2026.

What Does PCBA Mean?

PCBA is the basic process to transform a bare, non-functional PCB into a more complete and active working circuit. The PCBA process starts with applying solder paste on the PCB pad, and is then followed by efficient component placement using automated pick-and-place PCBA machines.

PCBA typically uses 3 methods for Assembly:

SMT PCB Assembly

With the trend of PCB miniaturization, SMT PCB assembly has become the most common PCBA method nowadays. It involves placing very small components on the solder paste applied on the PCB pad, and making the entire board pass through a reflow oven, where controlled heat melts the solder to form permanent connections.

Bringing benefits like high density, smaller footprint, automation, and cost-effectiveness for mass PCB fabrication, SMT PCBA has become common in consumer electronics applications like smartphones, laptops, and computers.

Through-Hole PCB Assembly

THT assembly involves inserting component leads into holes on the PCB after PCB drilling, and then soldering the components to the opposite PCB side through wave soldering.

Although it brings benefits like better mechanical bonding and components with high power or high stress, it can lead to more PCB surface area requirements and longer assembly time than the SMT process. It remains the technology of choice for components that undergo significant mechanical stress, such as connectors, transformers, and high-wattage power resistors.

Mixed Assembly (Hybrid)

Mixed PCB assembly means combining surface mount technology (SMT) and through-hole technology in a PCBA process. SMT components are typically implemented first for densification, followed by THT/TH parts. The mixed-assembly method is typically suitable for complex assemblies requiring both compact designs and robust assembly, such as power supplies, industrial control equipment, and automotive electrical/electronic equipment.

PCB vs PCBA: Why the Difference Matters?

The difference between PCB and PCBA is crucial for successful PCB project planning, accurate PCB cost estimation, and efficient communication with your manufacturer during PCB design. Failure to understand the difference between PCBA and PCB can lead to incorrect ordering, longer lead time, and more PCB costs.

PCB vs PCBA: What are the Key Differences?

The PCB is a bare board with no electronic components. A PCBA is an assembled, fully functioning board with all electronic components mounted to it. Here are the main distinctions between PCB and PCBA:

Differences	PCB	PCBA
Components	An insulating substrate, copper foil, solder mask, and a silkscreen layer	Bare PCB with all mounted components like ICs, capacitors, etc., solder joints, and flux residues.
Process	PCB fabrication, including etching, drilling, plating, surface finishing, and more	PCB assembly, including component placement, soldering, and inspection
Testing	Electrical Testing, and visual inspection	AOI, X-ray, ICT, functional testing, and more
Packaging	Vaccum packaging	Antistatic packaging
Functionality	Provides mechanical support for electric connectivity	Fully functional for electronics
Cost	Lower, driven by complexity, materials, layer count, and others	Higher due to component prices and more labor costs
Lead Time	Fast Turnround	Longer, About 2-4 weeks
Application	Upstream stage of electronics fabrication, prototyping	Final electronic products

PCB vs. PCBA: Differences in Design

The design for bare PCB manufacturing aims to enhance performance and reliability and reduce the cost of PCBs. It involves material selection, stack-up design, trace, vias, and pad design, impedance control, and more.

A PCBA design focuses on the overall system performance, stability, and manufacturability of the populated board. This shifts the emphasis to component selection, layout for automated assembly, heat dissipation, signal integrity, and more.

While distinct, PCB and PCBA design considerations are not independent. PCBA reliability is constrained by decisions made during the bare PCB design. And poor assembly practices can negate even the most sophisticated board layout.

PCB VS. PCBA: Key Differences in Manufacturing Process

Distinguishing factors between bare PCB manufacturing and the PCB assembly process and their final role in electronic product development are given in the table below:

Differences	PCB	PCBA
Manufacturing Step	Board fabrication	Component assembly and soldering
Components	Not included	Mounted on the board
Functionality	Non-functional	Fully functional
Processes Involved	Etching, drilling, layering	SMT, THT, soldering, inspection
Final Use	Base for assembly	Ready for integration into products

PCB vs. PCBA: Key Differences in Applications

Bare PCBs serve as a foundation for PCB design and development of circuit boards. While the PCBA provides the functional units in different electronics. Below are the key differences between these two in applications:

Differences during Product Development

Blank PCBs are primarily used for design validation, mechanical fitting, and basic electrical testing. Engineers also use these boards to verify the stacking structure, impedance control, and copper foil.

In comparison, the PCBA serves as a critical foundation for functional prototype validation, mass production, and after-sales spare parts.

Application Differences Across Industries

Bare boards serve as fundamental components in electronics, from consumer products to automotive, aerospace, telecommunications, industrial equipment, and medical devices.

PCBA services span multiple industries, including consumer electronics, automotive, industrial automation, medical devices, telecommunications, aerospace, energy, IoT, and LED lighting.

PCB vs PCBA: How to Choose?

Choosing between bare PCB and PCBA service should be based on your project’s specific stage, technical requirements, and business priorities.

Choose a bare PCB if:

You are in the prototyping or R&D phase and want the flexibility to manually solder and test component variations.
You have in-house assembly capabilities.
You need to source components for cost savings.
You are developing a simple circuit with large, easy-to-solder components.

Choose a Turnkey PCBA if:

You lack experience in PCB assembly.
You need a ready-to-use functional module for a commercial product, saving time on sourcing and assembly.
Your design is complex, featuring fine-pitch SMDs, BGAs, or high component density that requires automated, high-precision assembly.
You are moving to medium or high-volume production and need consistency, quality control, and faster time-to-market.

PCB and PCBA: How They Relate to Each Other?

A bare PCB without any electronic components mounted provides the mechanical support and electrical pathways for a circuit but can not function on its own.

A PCBA is the same bare PCB after soldering all the components onto it. It is a complete, fully functional electronic assembly that can function and perform its designed tasks.

The relationship is simple: a PCBA is a PCB that has been populated with components. A PCB is the foundation, and the PCBA is the finished product built upon it.

FS Circuits: A Reliable PCB and PCBA Manufacturer

FS Circuits is a PCB and PCBA manufacturer specialising in turnkey PCB assembly. Along with expertise in PCB assembly service, we also offer comprehensive PCB manufacturing services to our customers. Our bare board manufacturing capabilities include up to 1-58L rigid board, 1-6L flex board, 2-10L rigid-flex board, and 1-6L aluminium/copper board (36/10).

Why Partner with FS Circuits for PCB Manufacturing and Assembly?

Quality Assurance

Rigorous Quality Control: FS Circuits implements quality control throughout every stage of PCB fabrication, ensuring every detail is carefully considered to build customer trust.
Advanced Equipment & Certifications: We utilise advanced production and testing equipment and have obtained multiple prestigious certifications, including ISO9001, UL, ISO14001, ISO/TS16949 (automotive), and ISO13485 (medical device).

Comprehensive Service

One-to-One Personalised Service: With a professional team including project service, component procurement, PCB engineering, BOM engineering, PMC, IQC, production supervisors, process control engineers, and OQC, FS Circuits provides dedicated, personalised service.
True Turnkey EMS Provider: As an EMS manufacturer with 20 years of experience, FS Circuits proficiently handles all required services, including PCB fabrication, assembly, component procurement, testing, quality control, and finished PCB assembly.

Cost-Effectiveness

Strengthened Supply Chain: Training and expanding our procurement team have strengthened our supply chain, enabling better pricing without compromising quality.

Sustainable Development Commitment

Environmental Responsibility: Our PCB fabrication processes comply with RoHS, ISO 14001, UL, and IPC certification standards, demonstrating a commitment to reducing environmental impact.
Eco-Friendly Options: We offer lead-free PCB assembly, lead-free solder paste, and other environmentally friendly options.

FAQ

Are PCB and PCBA interchangeable?

No, PCBs and PCBAs are not interchangeable items. A PCB is only an incomplete item and cannot perform any of the functions by itself.

In contrast, a PCBA is a completely assembled and operational unit, and swapping of this PCB and PCBA alters the functionality of the system, resulting in procurement errors and delaying of the production process.

Can a PCB work without being assembled into a PCBA?

PCBs are partially assembled products and therefore cannot work independently. They provide a means for an electrical signal to travel along a designated path.

Hence, functional operation will only occur when a component has been added to the PCB and soldered into place, which converts the PCB into a PCBA.

Do PCBs and PCBAs undergo different testing processes?

Yes, multiple testing processes are completed on both PCBs and PCBAs. PCBs generally undergo the following tests: electrical continuity, insulation, and short circuit testing.

Conversely, there are several more advanced testing processes required for a PCBA: functional testing, in-circuit testing, and visual inspection.