Advantages of multi-layer PCB: high assembly density, small size, and light weight. Due to the high assembly density, the connections between components are reduced, thereby improving reliability; the number of wiring layers can be increased, thereby increasing design flexibility; a circuit with a certain impedance can be formed; a high-speed transmission circuit can be formed; circuit and magnetic circuit shielding layers can be set, and a metal core heat dissipation layer can also be set to meet the needs of special functions such as shielding and heat dissipation; simple installation and high reliability.