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What Is an Industrial PCB and How Is It Made?

Industrial PCB for CNC stepper motor

An industrial PCB must remain stable in demanding conditions. So, it has features that make it rugged enough to withstand extreme environments. This write-up will help you understand things that make it different from conventional circuit boards, its fabrication requirements, and example applications in the real world.

What is an Industrial Printed Circuit Board?

The industrial PCB is a circuit board specially designed for industrial applications. It can be a PCB for a power supply system or a high-voltage motor controller. Another example is the PCB of a building’s lighting system or the control electronics of automated manufacturing equipment.

These boards support entire electrical systems and must continue to operate in harsh conditions. For example, they must not fail when temperatures vary extensively, or moisture levels drastically rise.

The boards must meet other environmental conditions, including mechanical shock, vibrations, or high voltages. As such, they find helpful applications in the following sectors: energy industry, industrial automation, defense electronics, avionics, etc.

An example of the industrial circuit board for an automotive application
An example of the industrial circuit board for an automotive application
Resource: https://www.researchgate.net

What Makes an Industrial PCB Different?

Many features distinguish industrial circuit boards from regular boards. They include operating temperatures and voltage range, vibration and shock resistance, moisture resistance, and expected service life.

Operating Temperature

An industrial-grade PCB reliably operates in a broad range of temperatures, from as low as -65°C to around 150°C. That means it can be a board that works in the cold or retains its performance in blazing heat levels, depending on the desired application characteristics.

Vibration and Shock Resistance

Excessive vibrations and mechanical shocks characterize industrial electrical circuits. Their PCBs must, therefore, come designed to resist damage adequately. Sometimes, the substrate is flexible to absorb the vibrations or made from a rigid backing material like metal.

Moisture and Corrosion Resistance

The industrial PCB has a higher ability to resist moisture damage or corrosion. Usually, this protection involves coating it with a heavier and higher quality solder resist layer. Other measures include making the board with materials that repel moisture.

Operating Voltage and Power Requirements

Industrial electrical circuits are typically high-voltage. Their PCBs usually use large-sized power traces to handle the higher currents. Other measures include extensive heat dissipation features and materials that can withstand higher heat levels, like metal and ceramics.

Lifespan

One significant property distinguishing industrial circuit boards from commercial or consumer-grade boards is their longer lifespan. They typically last between 5 and 10 years, with some remaining operable for more than a decade.

Rigid-flex PCB assemblies for industrial application
Rigid-flex PCB assemblies for industrial application
Resource: https://www.researchgate.net

Industrial PCB Types and Design Standards

Industrial circuit boards are mainly classified by their material types and construction or stack up. They can be flexible or rigid and single-layer or multilayered. Each board type has an application that fits it. They also meet the IPC class 3 standard requirements.

Types of Industrial Circuit Boards

Rigid boards are made from a rigid substrate such as FR4 or metal, while flexible types are polyimide or Teflon (PTFE). Some combine both flexible and rigid materials in one piece.

Rigid boards are applicable where space is adequate and structural integrity paramount. On the other hand, flex boards fit where space is limited or if the PCB must bend permanently or during use.

The single-layer board is the most basic type. It fits simple applications like LED lighting. A multilayer board has more than two copper layers, providing more routing options. The number of layers can be as high as 16 or more.

Industrial PCB Design Standard

Industrial circuit boards comply with IPC class 3 standards. They meet high-performance requirements for harsh environments, as documented by the IPC 6012E standard. This standard covers military, medical, and automotive PCBs.

Several addenda within the standard identify application-specific requirements. They are IPC 6012 ES for military and space avionics, IPC 6012 EM for medical devices, and IPC 6012 EA for automotive boards.

IPC class 3 compliant circuits can withstand higher temperatures, mechanical shock and vibration, humidity, and other environmental stresses. Their materials typically have the following main properties.

  • A Tg value above 170 degrees Celsius for temperature withstand
  • Heat conductivity above 0.4 W/m.K for proper heat dissipation.
  • A dielectric constant of less than 4 to prevent signal degradation
  • Heavy copper to handle high power levels
A motor PCB design
A motor PCB design
Resource: https://forum.arduino.cc

Industrial PCB Manufacturing Process

The industrial PCB manufacturing process takes a slightly different route than a standard circuit board. The designing engineer must incorporate special board features and select a suitable material for the substrate. That’s in addition to its special routing and layout requirements or testing standards.

Material Selection

Because it operates in demanding conditions, the industrial PCB material must withstand various extremes, including heat, vibrations, and shock. Different materials are used depending on the application environment.

  • FR4 – a fiberglass epoxy substrate that suits milder applications with moderate requirements. For more demanding applications, high Tg FR4s offer better performance.
  • Polyimide – used to make flexible circuit boards. It can withstand higher environmental stresses than FR4, such as vibration and temperature, in addition to flexing.
  • Ceramic – supports higher temperature applications and high-frequency circuits. It mainly produces RF or microwave boards.
  • Metal Cores – a metallic core allows rapid heat dissipation and withstands higher mechanical shock and vibration levels. Mainly used for power electronics circuit boards and LED PCBs.

Design and Layout

Industrial PCB design takes into account the higher requirements of the application environment. Proper routing is also necessary, or the board may suffer performance issues due to incorrect component placement and thermal management problems. The following characterize the design and layout process:

  • Using thicker copper for high-power needs
  • Ensuring controlled impedance or impedance matching
  • Using ground planes to shield signal layers and reduce signal loss
  • Using blind or buried vias
  • Incorporating backup traces to prevent system failure
  • Integrating thermal management features like graphite layers to dissipate heat and heat shields near high-temperature components

Prototyping and Fabrication

The industrial PCB requires prototyping before going into full-fledged production. The prototype goes through a testing process to identify errors. This production stage saves you losses that a flawed end-product could cause.

During fabrication, the manufacturer ensures proper manufacturing techniques. They also follow various production standards to provide a product that satisfies client needs and industry standards. Some, like thicker coatings, protect the board against moisture damage.

Testing

The industrial circuit board undergoes rigorous testing using manual/visual and automated methods such as AOI and X-ray. These help catch flaws before the board leaves the factory and integrates into its end-use system.

Other tests include ICT (in-circuit testing), the flying probe test, and burn-in tests. These tests ensure high-quality boards that conform to various standards, such as UL and IPC class 3.

Industrial circuit board for use in avionics
Industrial circuit board for use in avionics
Resource: https://www.designworldonline.com

What is The Industrial Printed Circuit Board Used For?

Industrial applications of printed circuit boards are wide and varied. They range from the PCB’s integration in electrical devices like motors to its use in the control electronics of automation systems. Here is a collection of some of these uses.

  • Industrial motor drives and controllers
  • Power supply systems
  • Automotive electronics
  • Industrial system controller circuits
  • Telecommunication equipment and systems
  • Energy production systems
  • Healthcare equipment and systems
  • Aerospace system avionics
  • Military and defense electronics

Conclusion

The industrial PCB is a rugged circuit board that withstands harsh operating conditions. It operates in extreme heat and dust conditions, for example, or in applications with mild to intense vibrations. By adhering to strict design and fabrication standards, your contract manufacturer produces circuit boards that can last many years.

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