The so-called copper pouring is to use the idle space on the PCB as a reference plane, and then fill it with solid copper. These copper areas are also called copper pouring. The significance of copper coating is to reduce the impedance of the ground wire and improve the anti-interference ability; to reduce the voltage drop and improve the efficiency of the power supply; to connect to the ground wire can also reduce the loop area. Presumably everyone knows that at high frequencies, the distributed capacitance of the wiring on the printed circuit board will work. When the length is greater than 1/20 of the corresponding wavelength of the noise frequency, an antenna effect will occur. The noise will be emitted through the wiring, If there is poorly grounded copper clad copper in the PCB of the circuit board factory, it becomes a tool for spreading noise. Therefore, in high-frequency circuits, don't think that connecting a certain part of the ground wire to the ground is the "ground" Line", must be less than N/20 spacing, punch holes in the wiring, and "good grounding" with the ground plane of the multilayer circuit board. If the copper cladding is handled properly, the copper cladding not only has the dual function of increasing the current but also shielding interference.
In copper pouring, in order to make copper pouring achieve our expected effect, we need to pay attention to those issues in copper pouring:
1. If there are many grounds on the PCB, such as SGND, AGND, GND, etc., it is necessary to use the most important "ground" as a reference to independently pour copper, digital ground and GND according to the position of the PCB board. It’s not much to say that the ground is separated to pour copper. At the same time, before copper pouring, first thicken the corresponding power connection: 5.0V, 3.3V, etc. In this way, multiple deformable structures of different shapes are formed.
2. For the single-point connection of different grounds, the method is to connect through a 0 ohm resistor or a magnetic bead or an inductance.
3. The metal inside the equipment, such as Jinwu radiator, Jinwu reinforcement bar, etc., must be "good grounded".
4. The island (dead zone) problem, if you think it is too big, it will not take much to define a ground via and add it.
5. Do not cover copper in the open area of the middle layer of the multilayer circuit board. Because it is difficult for you to make the copper clad on this pcb board "good ground".
6. Pour copper near the crystal oscillator. The crystal oscillator in the circuit is a high-frequency emission source. The method is to pour copper around the crystal oscillator, and then ground the shell of the crystal oscillator separately.
7. At the beginning of wiring, the ground wires should be treated equally. When wiring, the ground wire should be routed well; you can't rely on adding vias after pouring copper to eliminate the connected ground pins. This effect is very bad. .
8. It is best not to have sharp corners on the pcb board (< = 180 degrees) because from the perspective of electromagnetism, this constitutes a transmitting antenna! It will always have an impact on others, whether it is large or small That's it, I recommend using the edge of the arc.
9. The heat dissipation metal block of the three-terminal regulator must be well grounded. The ground isolation zone near the crystal oscillator must be well grounded. In short: If the grounding problem of the copper clad on the PCB is handled well, it must be "the advantages outweigh the disadvantages". It can reduce the return flow area of the signal line and reduce the external electromagnetic interference of the signal.
In short: if the grounding problem of the copper on the PCB board is handled well, it will definitely be "better than harm". It can reduce the return area of the signal line and reduce the electromagnetic interference of the signal to the outside.
