The copper deposits need to pay attention to those issues:
1. If there are many lands on the PCB, such as SGND, AGND, GND, etc., it is necessary to independently cover the copper with the most important “ground” as the reference for different locations on the surface of the PCB board. The digital and analog grounds are separated. Copper does not say much at the same time, and before the copper is coated, the corresponding power connection is first bolded: 5.0V, 3.3V, etc. In this way, a plurality of differently deformed structures are formed.
2. For different single-point connections, the method is to connect through 0 ohm resistors or magnetic beads or inductors;
3. Copper coating near the crystal, the crystal in the circuit is a high frequency emission source, the approach is to surround the crystal in the copper, and then the crystal shell is grounded separately.
4. If you think of the problem of isolated islands (dead zones), it would not be too much to define a single hole to add to it.
5. When starting the wiring, the ground should be treated in the same way. When the cable is routed, the ground line should be taken well and cannot be depended on.
After the copper is eliminated by adding vias to connect to the ground pins, this effect is very bad.
6. It is best not to have sharp corners ("=180 degrees") on the board, because from the electromagnetic point of view, this constitutes a transmitting antenna, which will only have a big impact on others. However, I suggest using the edge of the arc.
7. The empty area of the middle layer of the multilayer board is not covered with copper. Because you have a hard time making this copper “grounded”
8. Metals inside the equipment, such as metal radiators, metal reinforcement strips, etc., must be “good grounded”.
9. The thermal mass of the three-terminal regulator must be well grounded. The grounding strip near the crystal must be well grounded.
In short: Copper on the PCB, if the grounding problem is handled well, it must be "benefit outweighs the disadvantages", it can reduce the return flow area of the signal line and reduce the external electromagnetic interference.