The design of printed circuit board is based on the principle of circuit, which can realize the function of the circuit designer. The design of the printed circuit board mainly refers to the layout of the layout. Optimize the layout of internal electronic components. Optimize layout of metal wire and through hole. Electromagnetic protection. Heat dissipation and other factors. Excellent layout design can save production cost, achieve good circuit performance and heat dissipation performance. The simple layout design can be realized by hand, and the complex layout design needs to be realized by computer aided design (CAD).