The so-called copper coating of PCB circuit boards refers to using the idle space on the PCB as a reference plane, and then filling it with solid copper. These copper areas are also known as copper filling. The significance of copper coating is to reduce the impedance of the ground wire and improve its anti-interference ability; Reduce voltage drop and improve power efficiency; Connecting to the ground wire can also reduce the loop area.

There are generally two methods of copper coating, namely large-scale copper coating and grid copper coating. Large area copper coating has the dual functions of increasing current and shielding, but if the copper coating is applied on a large area, the board may curl up and even bubble during wave soldering. Therefore, when covering a large area with copper, several grooves are usually opened to alleviate blistering on the copper foil. Grid copper coating, from the perspective of heat dissipation, reduces the heating surface of copper and plays a certain role in electromagnetic shielding. Therefore, high-frequency circuits with high anti-interference requirements for multi-purpose grid copper coating; Low frequency circuits, circuits with high current, and other commonly used large area copper coating.