The significance of copper coating is to reduce the impedance of the ground wire and improve the anti-interference ability, reduce the voltage drop and improve the efficiency of the power supply. Connecing with the ground wire can also reduce the loop area. Also for the purpose of making the PCB as undistorted as possible during soldering, most PCB manufacturers will also require PCB designers to fill the open areas of the PCB with copper or grid-like ground wires.
Copper coating is an important part of PCB design. Whether it is the domestic PCB design software, some foreign Protel and PowerPCB provide intelligent copper coating function, so how can we apply copper? Here I will give some of my own share ideas with everyone, hoping to bring benefits to you.
In fact, the so-called copper pour is to use the unused space on the PCB as a reference surface and then fill it with solid copper. These copper areas are also called copper pour. The significance of copper coating is to reduce the impedance of the ground wire and improve the anti-interference ability, reduce the voltage drop and improve the efficiency of the power supply; connecting with the ground wire can also reduce the loop area. Also for the purpose of making the PCB as not deformed as possible when soldering, most PCB manufacturers also require PCB designers to fill the open areas of the PCB with copper or grid-like ground wires. If the PCB has many grounds, such as SGND, AGND, GND, etc., then how to pour copper? My approach is to use the most important “ground” as the reference for the difference in the position of the PCB board. For copper plating, the digital ground and analog ground are separated to pour copper. At the same time, before pour copper, thicken the corresponding power connection: v5.0v, v3.6v, v3.3v, etc. In this way, multiple deformable structures with different shapes are formed.
There are several problems to be dealt with in copper coating. One is the single-point connection of different grounds, which is connected through 0 ohm resistors or magnetic beads or inductance. The other is copper coating near the crystal oscillator, and the crystal oscillator in the circuit is a high-frequency emission source. It is to coat copper around the crystal oscillator, and then ground the shell of the crystal oscillator separately. The third is the problem of the dead zone. If you think it is too big, it won’t cost much to define a ground via and add it.
In addition, whether large-area copper pour is better or grid copper pour is better, it is not good to generalize. Why? Large area copper, if wave soldering, the board may be up and even blistering. From this point of view, the heat dissipation of the grid is better. It is usually a multi-purpose grid with high requirements for anti-interference in high-frequency circuits, and circuits with large currents in low-frequency circuits are commonly used with complete copper. However, one person said that impedance matching must be used when making signals above 1GHz, and the reflective surface must be full copper!
Personal experience summary: When starting wiring, the ground wire should be treated equally. When routing the ground wire, the ground wire should be routed well. You cannot rely on the copper pour to eliminate the ground pin for the connection by adding vias. This effect is very poor. Of course, if the grid copper is used, these ground connections will affect the appearance. If you are careful, delete it. In short, if the grounding problem of the copper coating on the PCB is dealt with, it must be “pros outweigh the disadvantages”. It can reduce the return area of the signal line and reduce the electromagnetic interference of the signal to the outside.
Finally, sum up the benefits of copper coating, that is reduce ground wire impedance, improve anti-interference ability, reduce voltage drop, improve power supply efficiency, reduce high-frequency interference, and it looks very beautiful!
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