Heavy Copper PCBs
There are many reasons why a PCB designer might want to use heavy copper, but it’s important to be aware of the limitations that come with this plating. These limits include current rating capacity, heat generation, and the ability to perform well in harsh environments.
When a high current passes through a copper trace it causes a localized heat transition. This heat then dissipates into the surrounding environment via conduction and convection. This is why the maximum current rating for a track should never exceed its thickness plus 10 percent. This will ensure that the heat generated does not cause the copper to warp or decrease its electrical performance.
The amount of heat a trace generates is proportional to the amount of current it carries, so the first step in designing a circuit board with heavy copper is to gauge the amount of current the circuit will be required to carry. Then the designer can select the right copper thickness and width. The designer can also utilize a tool to determine the maximum temperature rise that the circuit board can withstand.
Limitations of Heavy Copper PCBs
One of the limitations that comes with a heavy copper pcb is that it can be challenging to achieve good thermal management in the manufacturing process. This is because etching and plating thicker copper traces is more difficult than etching thinner traces. In order to reduce this challenge, designers can use a special plating technique called differential etching. This allows them to increase the copper traces’ width and spacing without compromising their current carrying capability.
Another limitation of heavy copper PCBs is that it can be challenging to use small holes for connections or wires. The reason for this is that copper has a tendency to plate the sides of these holes shut when it is plated. In order to overcome this problem, designers should work with the PCB fabricator early in the design process to make sure that the holes are sized appropriately.
When using heavy copper, designers should also consider the substrate material. This is because different FR-4 materials have different glass transition temperatures (Tg). The choice of a suitable substrate is essential in order to ensure that the heat generated by the copper doesn’t exceed the Tg of the base material and causes cracking and layer separation.
While there are limitations to heavy copper PCBs, the benefits outweigh the negatives. These include the ability to withstand harsh environments, low failure rates, and reduced cost. In addition, these types of circuit boards can be used in a variety of industries including military/defense, automotive, solar panel, and welding equipment manufacturers. These industries often require boards that are capable of handling high levels of current. By working with a trusted PCB manufacturer, you can be confident that your next project will be able to meet these rigorous requirements.
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