First, the reason for laying copper:
- EMC, for large areas of ground or power supply copper, will play a shielding role, some special, such as PGND play a protective role.
- PCB process requirements, generally in order to ensure the plating effect, or laminate is not deformed, for the layout of less PCB board copper layer.
- Signal integrity requirements, a complete return path for high-frequency digital signals, and reduce the wiring of the DC network. Of course, there is heat, special device installation requires copper plating and other reasons.
Second, the benefits of copper plating:
The greatest benefit of copper deposition is the reduction of ground impedance (so-called anti-jamming is also caused by a large part of the reduction in ground impedance). There are a large number of spike currents in the digital circuit, so reducing the ground impedance is more necessary. It is generally considered that Circuits made up entirely of digital devices should be laid on a large area, and for analog circuits, the ground loop formed by copper plating will cause electromagnetic coupling interference rather than gain (except for high-frequency circuits). Therefore, it is not a circuit that must be copper-plated (BTW: mesh-plated copper has better performance than whole blocks).
Third, the significance of copper is:
- Copper is connected to ground so that the circuit area can be reduced.
- A large area of copper is equivalent to reducing the resistance of the ground wire, reducing the pressure drop. From these two points, whether it is a digital ground or an analog ground, copper should be laid in order to increase the anti-interference ability, and at high At the time of frequency, it is also necessary to separate the copper from the digital ground and the analog ground, and then connect them with a single point. The single point can be wound with a wire on a magnetic ring and then connected. However, if the frequency is not too high, or if the working conditions of the instrument are not bad, it can be relatively relaxed. The crystal can be counted as a high-frequency emitter in the circuit. You can lay copper around and then ground the crystal’s case. This would be better.