PCB copper laying in circuit board design

      Laying copper in PCB design is a very important aspect of circuit board design. What is PCB copper laying? It means filling the no wiring & idle space on the PCB with solid copper. The significance of laying copper is to reduce the impedance of the ground wire and improve its anti-interference ability; reduce voltage drop, improve power efficiency, connect to ground wire, and also reduce loop area.

The significance of PCB copper laying

      The main advantage of laying copper is to reduce the impedance of the ground wire, which is also a significant part of anti-interference. There are a large number of peak pulse currents in digital circuits, so reducing the impedance of the ground wire is more necessary.
      It is generally believed that for circuits composed entirely of digital devices, a large area of ground should be laid, while for analog circuits, the ground loop formed by laying copper can actually cause electromagnetic coupling interference to outweigh the gains (except for high-frequency circuits). Therefore, not all circuits need to be coated with copper.

Advantages and disadvantages of PCB copper laying

Advantage

1、 For EMC (electromagnetic compatibility) requirements, large areas of ground or power supply need to be covered with copper, which will play a shielding role. Some special areas, such as PGND (protective ground), play a protective role.
2、 For PCB manufacturing requirements, it is generally necessary to ensure a uniform copper plating effect during electroplating or to ensure that the lamination does not deform or bend. For PCB boards with less wiring, copper should be laid on each layer.
3、 For signal integrity requirements, provide a complete return path for high-frequency digital signals and reduce the wiring of the DC network. Of course, there are also reasons such as heat dissipation, special device installation requirements for copper laying, and so on.

Disadvantages 

1、 If the pins of the components are fully covered with copper, it may lead to rapid heat dissipation, making it difficult to disassemble and repair. So sometimes, in order to avoid this situation, cross connections are used for components (pin contact and solder pad contact are "ten" characters).
2、 Laying copper in the area around the antenna can easily lead to weak signals and interference in the collected signal. The impedance of copper laying can affect the performance of the amplification circuit. So the surrounding area of the antenna section is generally not covered with copper.

The shape of PCB copper laying

Solid shape copper laying

Solid copper laying has a dual effect of increasing current and shielding. However, with solid copper coating, if there is a certain tensile force during wave soldering, the board may curl up and even bubble. Therefore, when applying copper physically, several grooves are usually opened to alleviate the tension causing blistering of the copper foil.

Grid shaped copper laying

Grid copper coating mainly serves as a shielding effect, but increasing the current will reduce the effect. From the perspective of heat dissipation, grid copper coating not only reduces the heating surface of copper, but also plays a certain electromagnetic shielding role. However, the production process has certain requirements for grid shape copper laying, and a small grid size affects the quality yield.