Disadvantages of multilayer boards: high cost; long cycle; high-reliability testing methods are required. Multilayer printed circuit is the product of the development of electronic technology in the direction of high speed, multi-function, large capacity and small volume. With the continuous development of electronic technology, especially the extensive and in-depth application of large-scale and very large-scale integrated circuits, multilayer printed circuits are rapidly developing in the direction of high density, high precision, and high-level digitalization. Fine lines and small apertures have appeared. , Blind and buried holes, high plate thickness to aperture ratio and other technologies to meet the needs of the market.