What are the PCB wiring rule?

I. Layout

10 rules for component layout:

1. Follow the layout principle of "big first, small later, difficult first, easy later", that is, important unit circuits and core components should be laid out first.

2. The principle block diagram should be referred to in the layout, and the main components should be arranged according to the main signal flow rule of the single board.

3. The arrangement of components should be convenient for debugging and maintenance, that is, large components cannot be placed around small components, and there should be enough space around components and devices that need to be debugged.

4. For the same structural circuit part, the "symmetrical" standard layout should be adopted as much as possible;

5. Optimize the layout according to the standards of uniform distribution, balanced center of gravity, and beautiful layout;

6. The same type of plug-in components should be placed in one direction in the X or Y direction. The same type of polar discrete components should also strive to be consistent in the X or Y direction to facilitate production and inspection.

7. Heat-generating components should generally be evenly distributed to facilitate the heat dissipation of the single board and the whole machine. Temperature-sensitive devices other than temperature detection components should be kept away from components with high heat generation.

8. The layout should try to meet the following requirements: the total connection is as short as possible, and the key signal line is the shortest; high voltage, high current signals are completely separated from small current, low voltage weak signals; analog signals are separated from digital signals; high frequency signals are separated from low frequency signals; the spacing of high frequency components should be sufficient.
9. The layout of the decoupling capacitor should be as close to the power pin of the IC as possible, and the loop formed between it and the power supply and ground should be as short as possible.
10. When laying out components, appropriate consideration should be given to placing devices using the same power supply together as much as possible to facilitate future power supply separation.

2. Priority of wiring

Key signal lines are prioritized: key signals such as analog small signals, high-speed signals, clock signals and synchronization signals are prioritized for wiring
Density priority principle: Start wiring from the device with the most complex connection relationship on the single board. Start wiring from the area with the densest connection on the single board
Note:
a. Try to provide dedicated wiring layers for key signals such as clock signals, high-frequency signals, sensitive signals, and ensure their minimum loop area. If necessary, manual priority wiring, shielding and increased safety spacing should be adopted to ensure signal quality.
b. The EMC environment between the power layer and the ground layer is poor, and signals that are sensitive to interference should be avoided.
c. Networks with impedance control requirements should be routed as per the line length and line width requirements as possible.