The design of printed circuit board is based on the circuit schematic diagram to realize the functions required by the circuit designer. Printed circuit board design mainly refers to layout design, which needs to consider the layout of external connections. Optimal layout of internal electronic components. Optimum layout of metal connection and through hole. Electromagnetic protection. Heat dissipation and other factors. Excellent layout design can save production costs, achieve good circuit performance and heat dissipation performance. Simple layout design can be realized by hand. Complex layout design needs to be realized by computer aided design (CAD).