In fast PCB design, multilayer circuit boards are generally used. Multilayer circuit board is made of multiple etched single or double-sided boards by lamination and bonding. Compared with single-layer and double-layer circuit boards, multilayer circuit boards have many advantages, especially in small electronic products.

1. Multilayer circuit boards have high assembly density and small size. With the smaller and smaller volume of electronic products, higher requirements are put forward for the functions of PCB circuit boards, and the demand for multilayer circuit boards is also growing.

2. It is convenient to use multi-layer PCB circuit board to lay wires, which greatly shortens the length of laying wires, reduces the laying of wires between electronic components, and also improves the speed of data signal transmission.

3. For high-frequency circuits, after entering the ground plane, the signal line has a stable low characteristic impedance to the ground, and the characteristic impedance of the power circuit decreases significantly, which has a significant interception effect.

4. For electronic products with high requirements for heat dissipation function, a metal core heat dissipation layer can be set on the multilayer circuit board, which is convenient to meet the requirements of shielding, heat dissipation and other special functions.

In terms of function, multilayer circuit boards are better than single-sided and double-sided boards, but the more layers, the higher the production cost, the longer the processing time, and the more complex the quality inspection. With the improvement of technology, there are more than 100 layers of printed circuit boards, which are mainly used in precision Aerospace instruments and medical equipment.