Chamfering rules: Sharp and right angles should be avoided in PCB design to avoid unnecessary radiation and poor process performance. Device decoupling rules: A. Add necessary decoupling capacitors on the printed board to filter out the interference signal on the power supply and stabilize the power supply signal. In a multi-layer board, the position of the decoupling capacitor is generally not too high, but for a double-layer board, the layout of the decoupling capacitor and the wiring method of the power supply will directly affect the stability of the entire system, and sometimes even affect the design. success or failure.