High Current PCB Design: 5 Important Tips to Keep in Mind

High current PCB design

A poorly designed high-current circuit board can cause malfunctions, component damage, or fire hazards. To avoid these risks, anyone involved in high-current PCB design must always adhere to specific essential guidelines. This article will discuss five critical tips for designing a reliable, efficient high current PCB.

What is a High Current PCB?

Before we go over the high-current PCB design tips, defining what qualifies a PCB as a high-current type is essential. Generally, a PCB for high-existing applications is designed to carry over a few Amps (A) of current. This type of board has more significant components that can handle higher power dissipation than standard circuit boards. A high-current PCB is also usually either a flexible or rigid circuit board.

High Current Rigid PCB

A high-current rigid PCB is a printed circuit board made of solid layers of metals and non-metallic materials, such as glass-fiber epoxy resin. This type of board can tolerate high current requirements due to its robust nature. It also typically has multiple layers for improved thermal management.

In a rigid high-current PCB, the components are soldered directly to the board’s surface, so thermal reliefs and large copper pour areas are essential. The added layers also make it easier to route high-current traces and reduce the risk of short circuits.

High Current Flexible PCB

A flexible circuit board is an alternative to the rigid PCB for high-current applications. This type of board has components connected by thin polyimide film and held together by an adhesive.
Flexible PCBs are usually much lighter than rigid boards, making them ideal for applications where a lightweight circuit board is needed. A high-current flexible PCB is also usually more resistant to damage due to its flexibility and ability to conform to any board shape.

High Current PCB Design

During the high-current PCB design process, engineers must consider their circuit board’s power requirements. That means using passive and active components such as resistors, transistors, and capacitors to accommodate the higher current levels.

In addition to component selection, it’s recommended to consider other aspects of high-current PCB design, such as board layout, thermal management, and electrical performance. Below, we compiled a list of five essential tips to keep in mind when designing a high-power PCB.

High Current PCB Design Tips

High current PCB design is done with the board’s requirements and operating conditions in mind. That includes the current levels and voltages that the board will be working with, the stack-up rules, and the general board layout. Here is a list of 5 essential high-power PCB design guidelines to always keep in mind:

High Current PCB Components

Ensure all your components, such as relays, switches, and connectors, are rated for the appropriate current levels. Also, select power supplies, resistors, and other components of suitable quality and size for the high current requirements of your board.

When choosing your high-current PCB components, select the suitable component using the board’s estimated current. Also, consider the amount of heat generated by members operating at high currents and voltages, as this could affect the overall thermal management of your board.

In some cases, a component for a high-current PCB design will require a heat sink. Determine this by calculating the thermal resistance (the temperature increase over ambient) at a given current. If this exceeds the power rating of your component, then a heat sink may be needed to dissipate the excess heat.

High Current PCB Traces

One of the most important PCB design guidelines for power electronics involves trace requirements, both in terms of size and suitability. High-current PCB traces must be designed with the correct width and thickness to handle high current levels.

The trace width is determined by the amount of current flowing through it, board stack up, voltage, and temperature rise. A wider trace can carry more current without heating up too much. However, however, this is not always the best practice when it comes to high-power PCB design.

If signal and power integrity issues crop up when routing high-current traces on your boards, you may want to use power planes instead of traces, especially if the current is too high and the trace width too high.

High Current PCB Layout

High current PCB layout requires careful consideration of all component and routing requirements. Ensure all high-current components are spaced out adequately to prevent short circuits, crosstalk, or other interference.

Use thermal vias to remove heat from components on your high-current PCB design. Thermal vias are copper-plated holes that can help dissipate heat and maintain the temperature of the board at a safe level.

Use these near areas with high current components and ensure that they are connected to ground planes, as this will help more efficiently transfer the heat away from your board’s components.

High Current PCB Thermal Management

In a high-current PCB, thermal management is one of the most important aspects to consider. The components and traces generate heat as current is passed through them, which can lead to overheating and component damage.

To ensure proper high-current PCB thermal management, use copper pour areas on the board to dissipate heat. If necessary, consider adding additional cooling components, such as fans or heat sinks, to help keep the board cool. Properly placed vias can also help move the heat away from components, as earlier mentioned.

A thicker board of at least 3mm is also recommended. This type of board will provide additional area for thermal dissipation and can help spread the heat over a larger surface. That’s in addition to providing the much-needed mechanical support to large, high-current PCB components such as connectors and heat sinks.

Conclusion

Designing a PCB for high-current applications can be quite a challenge. These boards operate under higher power levels, which require components and traces that can handle the high current. Taking into account all of the factors, such as component type, trace width and layout, and thermal management, can help ensure a safe and efficient board design.

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