Rules for proofing and layering of PCB multilayer boards

Pcb (printed circuit board) can be divided into single-sided, double-layered and multi-layered. There is no limit to the number of layers of multilayer boards. At present, there are more than 100 layers of PCB, commonly four-layer and six-layer boards.
On the basis of Top Layer and Bottom Layer, the simple four-layer board adds power layer and ground layer, which greatly solves the problem of electromagnetic interference, improves the reliability of the system, improves the routing rate of wires and reduces the area of PCB.
The setting of the number of multilayer boards is very flexible, and designers can make reasonable settings according to the actual situation. So, what is the layering principle of pcb multilayer board? The settings of various layers shall meet the following requirements:
1. The power plane should be close to the ground plane, closely coupled with the ground plane, and arranged below the ground plane. Below the element layer is the ground layer, which provides the device shielding layer and the reference layer for the top wiring;
2. The signal layer should be adjacent to the internal electrical layer, not directly adjacent to other signal layers, and all signal layers should be adjacent to the ground layer as much as possible;  
3. Isolate the digital circuit from the analog circuit. If conditions permit, arrange analog signal lines and digital signal lines in layers, and adopt shielding measures; If it needs to be arranged in the same signal layer, isolation belt and ground strip should be adopted to reduce the interference. The power supply and ground of analog circuit and digital circuit should be isolated from each other and cannot be mixed.
4. When designing the multilayer board, each layer should be symmetrical, and it is best to have even copper layers. If it is asymmetrical, it will easily cause distortion.
Multi-layer PCB has many advantages, such as: high assembly density and small volume; The connection between electronic components is shortened, the signal transmission speed is fast, and the wiring is convenient; Good shielding effect, and so on.