The circuit board determines the process difficulty and processing price according to the number of wiring surfaces. Common circuit boards are divided into single panel and double panel. However, high-end electronic products are limited by product space design factors. In addition to surface wiring, multilayer circuits can also be superimposed inside. In the production process, after a layer of wiring is completed, it is positioned and pressed by optical equipment so that the multilayer circuit is superimposed on a circuit board, commonly known as a multilayer circuit board.

Multilayer circuit boards are currently the most widely used type of circuit boards in daily life. Has the following advantages:

1. High assembly density, small size and light weight;

2. Due to the high assembly density, the wiring between the components is reduced, the installation is simple, and the reliability is high;

3. Due to the repeatability and consistency of graphics, wiring and assembly errors are reduced, and equipment maintenance, debugging and inspection time are saved;

4. The number of wiring layers can be increased, thereby increasing design flexibility;

5. A circuit with a certain impedance can be formed, and a high-speed transmission circuit can be formed;

6. Circuit, magnetic circuit shielding layer can be set, and metal core heat dissipation layer can also be set to meet the needs of special functions such as shielding and heat dissipation.

With the continuous development of electronic technology, the computer, medical, aviation and other industries have continuously improved the requirements for electronic equipment. The circuit board is developing in the direction of reducing the size, reducing the quality and increasing the density. Due to the limitation of available space, single and double panels cannot further increase the assembly density, so it is necessary to consider the use of multilayer circuit boards with more layers and higher assembly density. Multilayer circuit boards have been widely used in the manufacture of electronic products because of their flexible design, stable and reliable electrical performance, and superior economic performance.