The rules for wiring power lines and ground lines are as follows.
• Add decoupling capacitors between the power supply and ground.
• Try to widen the width of the power cord and ground wire. It is better that the ground wire is wider than the power cord.
The PCB of digital circuit can use a wide ground wire to make up a circuit, namely to form a ground net to use, the ground of analog circuit can't use like this.
• Use a large area of copper as the ground wire. Connect the unused ground to the ground as a ground wire on the printed circuit board or use a multilayer board. The power supply and the ground wire each occupy one floor.
Check of rules
After the wiring design is completed, it is necessary to carefully check whether the wiring design complies with the rules established by the designer. It is also necessary to confirm whether the established rules meet the requirements of the PCB production process. Generally, the following aspects are checked.
• Whether the distance between the line and the line, the line and the component pad, the line and the through hole, the component pad and the through hole, and the through hole and the through hole is reasonable and meets the production requirements.
• Whether the width of the power line and the ground line is appropriate, whether the power supply and the ground line are tightly coupled (low wave impedance), and whether there is a place where the ground line can be widened in the PCB.
• Whether the best measures have been taken for the key signal lines, such as the shortest length, plus the protection line, the input line and the output line are clearly separated.
• Is there a separate ground for analog and digital circuits?
• Whether or not a graphic (such as an icon or a note) added to the PCB will short-circuit the signal.
• Modify some ideal line shapes.
• Whether a process line is added on the PCB, whether the solder mask meets the requirements of the production process, whether the solder mask size is appropriate, and whether the character mark is pressed on the device pad or not.
• Whether the outer frame of the power stratum in the multilayer board is reduced, such as the copper foil in the power stratum exposed outside the board, which may cause short circuits.