Power Plane PCB: Best Practices


Power Plane PCB: Best Practices

One of the best ways to improve your multi-layered printed circuit board (PCB) is by using power planes. By employing power planes in your PCB, you can utilize shorter return paths, receive better decoupling between circuits and achieve a greater current capacity. If you’re interested in getting the most out of your PCB, learn the top ways to implement power planes.

This article covers the definition of power planes, how they’re used in PCBs and the best practices of using power planes with PCBs.

What Is a Power Plane?

A power plane is a flat copper plane designed to give your PCB a steady supply of voltage. Power planes are connected to power supplies, much like how ground planes connect to a power supply’s ground connection. These power planes supply components with power through contact with a via featuring a trace.

You’ll typically only find power planes in PCBs featuring more than three layers. This trend of using power planes in boards with more layers is partially due to the greater benefits of using ground planes for two-layer boards instead of power planes. Since stable ground planes utilize tracks to supply a power source with power, they tend to be a better option for two-layer boards.

The use of power planes in boards with more than three layers or more is an industry best practice of employing layers in even numbers when creating multi-layer stack-ups. When a stack-up has an odd number of layers, it creates an asymmetrical construction that often causes structural defects, such as warping and twisting.

How Are Power Planes Used In a PCB?

How Are Power Planes Used In a PCB?

While two-layer boards can benefit from ground planes featuring traces and tracks, most four or more layer boards can significantly benefit from power planes. A few of the top ways power planes are used in PCBs to provide greater advantages than those with traces include:

  • Greater current carrying capacity: Traces tend to struggle to handle larger currents, resulting in PCBs having higher operating temperatures. In contrast, power planes help PCBs have lower operating temperatures since they have a greater current carrying capacity.
  • Shorter return paths: Another way PCBs can benefit from power planes is their shorter return paths than those used with traces. These shorter return paths make it much more convenient for the power plane to power the circuit, as you can easily follow the via connecting the power lane and signal layer. By having shorter return paths, a PCB will receive improved electromagnetic compatibility (EMC) performance.
  • Better decoupling between circuits: Power planes are regularly used in PCBs instead of traces because they provide better decoupling between circuits. This improved decoupling helps stop noise and energy from spreading from circuit to circuit in the power supply.

Best Practices in Power Planes Design

If you’re interested in using power planes for your PCBs, you’ll want to understand the best practices for power plane design. By relying on some of the most common strategies for power plane designs, you can better dissipate heat and produce a more symmetrical construction. Here are the top best practices for power plane PCB designs:

Design the Power Planes for Proper Heat Dissipation

A multi-layer PCB needs to have proper heat dissipation to ensure it doesn’t overheat and break down. When you have a multi-layer board with power planes, it’s a good idea to utilize plane partitioning. You can also rely on multiple vias, as this design strategy can improve plane partitioning. With these strategies, you can dissipate heat from the PCB more effectively while employing power planes.

Use Multiple Domains

A single layer PCB usually only needs a single power domain to power its components when these components have identical voltage requirements. For more complex and dense PCB designs featuring power planes, it’s best practice to use multiple domains. For example, a PCB’s I/O ports might have different voltage requirements than microcontroller units, requiring you to account for both voltages by splitting the reference plane.

While having multiple domains can help you save space and ensure every component has the right power, you can still run into EMC issues, greater noise and crosstalk. Top manufacturers will separate their power plane PCB’s high power, analog and digital circuits to reduce the chances of negative effects. They may also separate each circuit’s power rails on the PCB and skip the power plane to receive more efficient routing. This design option requires using a ground plane to absorb noise and shorten return paths.

Ensure Multi-Layer Boards Have Symmetry

When you’re designing a multi-layer PCB, you’ll want it to have proper symmetry. Your power planes play a significant role in ensuring this symmetry. For example, a four-layer board will need to have two internal power planes. This design strategy is especially helpful for two-sided PCBs featuring components mounted on the bottom and top layers. Keep in mind you’ll need to rely on traces to give your PCB returns when using multiple power planes.

Collaborate Across Teams With Layout Software and the Best Layout Tools

Another best practice for producing power plane PCBs is to use layout software that allows you to collaborate across teams. Having software in your corner can help you set the correct layer dimensions, arrange the stack-up appropriately with the right power plane design and select the best materials. High-quality layout software can also help you determine the best locations, sizes, numbers and types of vias.

Using cross-team collaboration software helps ensure you use the best designs possible. This software can also help you more effectively simulate your designs and analyze them to create the best power plane placement and construction. You can complement this software by using effective layout tools to make the process even easier.

Choose Millennium Circuits Limited for Your Power Plane PCB Needs

Choose Millennium Circuits Limited for Your Power Plane PCB Needs

Now you know the best practices for designing a power plane PCB, you need a company that can supply you with the best PCBs for your needs. At Millennium Circuits Limited, we provide our clients with quality PCBs, including multi-layer PCBs featuring power planes. Due to our experience in the industry and ISO 9001:2015 certification, you can feel confident you’ll receive high-quality PCBs meeting your strictest requirements when you partner with us.

Learn more about our domestic and offshore PCB capabilities today. If you want more information on pricing or have any questions, please feel free to contact us or request a free quote.