Choosing the Right Components and Materials for Power Electronics PCBs

Power Electronics PCBs are vital to the operation of the automotive industry, renewable energy systems, and industrial automation machinery. These boards are subjected to high voltage, large currents, and severe heat, making the selection of power electronics PCB components and materials with respect to reliability over time critical. Whether you are designing a circuit for PCB board assembly manufacturing or looking for a turnkey PCB fabrication vendor, your decisions regarding the power PCB design will affect the energy efficiency and sustainability of the entire system. 

The following guide aims to show every detail associated with electronics PCB design with the appropriate selection of PCB materials and components for Power Electronics PCBs. 

Why Power Electronics PCBs Need Special Attention? 

As opposed to a generic PCB used in conspicuous electronics, power PCBs must:

• Manage excessive power loading without overheating.
• Prevent high voltage insulation breakdown.
• Possess sufficient mechanical strength to endure shock and vibration stress.
• Minimize electromagnetic interference (EMI) generated by nearby circuits.

Choosing components or materials that do not meet engineering requirements can result in overheating, loss of efficiency, and circuit failure. Understanding material selection and design strategies is crucial.

Choosing PCB Materials for Power Electronics 

The choice of materials on a power PCB affects its thermal management capability and electrical stress tolerance. 

1. Substrate Material 

The substrate supports the copper layer within the board, providing mechanical strength and thermal resistance.

Power PCB Substrate Materials List

• FR4 (Epoxy Fiberglass): Most common PCB material; low thermal resistance, unsuitable for high-power applications.
• Polyimide (PI): Enhanced thermal and mechanical strength, ideal for flexible high-temperature PCBs.
• Metal Core PCB (MCPCB): Uses aluminum or copper bases for superior heat dissipation, commonly used in LED lighting and motor controls.
• Ceramic PCBs: High thermal conductivity and excellent electrical insulation, used in aerospace, military, and power converters.

Learn About: PCB Thermal Profiling in PCB Assembly

2. Copper Thickness: Leads for Power 

Thicker copper allows a PCB to transport more current.

• 1 oz copper (35µm thick) – Standard for general PCBs, not for power circuits.
• 2 to 4 oz copper – Common in power electronics PCBs; supports larger currents.
• Heavy Copper PCBs (up to 20 oz) – Used in power distribution circuits and battery management systems.

Best Practice: To avoid overheating, use at least 2 oz copper layers in power PCBs.

4. Thermal Management Materials 

Efficient cooling is imperative when dealing with power circuits that produce a lot of heat.

• Thermal Vias: Holes with copper plating that allow heat to be transmitted to the other side of the PCB.
• Heat Sinks: Components that transfer heat away from other components that generate a lot of heat.
• Thermal Interface Materials (TIMs): Allow better conduction of heat between components and the sinks.

Best Strategy: To aid cooling, place thermal vias under hot components.

Choosing the Right Components for Power Electronics PCBs 

Careful selection of components for power electronics PCBs results in robust operation coupled with high efficiency.

1. Power Semiconductors: Managing Switching and Conversion:

• For inverters and DC-DC converters’ high-speed switching circuits, use MOSFETs & IGBTs. 
• For rectifiers and high-efficiency power supplies, use Schottky Diodes & SiC Diodes. 
• Thyristors and Triacs: Used in drive motors and AC power control systems.

2. Capacitors: Energy Storage and Filtering:

• Electrolytic Capacitors: Used to filter power, these have high capacitance. 
• Film Capacitors: Special inverters use these to control high voltage and high-frequency currents. 
• Ceramic Capacitors: Use these for highly effective noise reduction and decoupling. 

Tip: If you want to increase efficiency, use capacitors with low equivalent series resistance.

3. Inductors and transformers: Conditioning of power:  

• High-Current Inductors: Found in Switch Mode Power Supplies. 
• Ferrite Core Transformers: Step down or up the voltage in isolated power converters.

4. Resistors and heat dissipation components.

• Thick film resistors: Used in applications that are high in power. 
• Shunt Resistors: Used to read electric current in power circuits. 
• Heat sinks and fans: Used in high power systems and to prevent overheating. 
• Connectors and terminals: Flex PCB connectors: Used in designs made of flexible high-density power elements. 
• High-current power connectors: Used in circuits with high power output. 
• Screw terminals: Widely used in industrial applications for reliable electrical connections. 

Important pointers for the design of power PCBs: 

When designing power PCBs, the layout of the PCB is just as important, if not more important, than materials and components.

1.Trace Width & Space:

• Heat generation and resistance can be reduced with wider traces. 
• Avoid spacing that is too close in high-voltage circuits to avoid breakdown voltage.

2. Optimized Layer Stack-Up

• Use multiple copper layers to enhance current flow. 
• Place high-current traces in the inner layers to reduce EMI.

3. Ground & Power Planes

• Solid ground planes are essential for maintaining signal quality and reducing noise. 
• Split power and ground planes to reduce potential drop.

4. Placing Thermal Vias

Put thermal vias below high-powered devices to help dissipate heat. 

Ensuring Reliability in Power PCBs 

For sustained performance over time, consider these recommendations:

• Apply Conformal Coatings: Defense against dust, moisture and other contaminants. 
• Run Thermal Simulations: Determine hot spots and work on improving heat removal. 
• Check for EMI Compliance: Follow FCC, CE, and UL requirements. 
• Use Turnkey PCB Manufacturing: Partnering with a PCB assembly manufacturing company guarantees the elimination of mistakes. 

Effective power electronics PCB design necessitates good materials and components, as well as proper layout strategies, to guarantee efficiency, reliability, and durability. The optimal selection of PCB materials, combined with the best copper thickness and outstanding power electronics PCB components, enables reliable, high-performance power circuits under extreme conditions.