1. The assembly density of multi-layer circuit boards is high and their volume is small. With the decreasing volume of electronic products, higher requirements are also put forward for the electrical performance of PCBs, and the demand for multi-layer circuit boards is also increasing.

　　2. The use of multi-layer circuit boards facilitates wiring, significantly shortens the length of wiring, and shortens the connections between electronic components, which also improves the speed of signal transmission.

　　3. For high-frequency circuits, after adding a ground layer, the signal line will form a constant low impedance to the ground, resulting in a significant reduction in circuit impedance and better shielding effect.

　　4. For electronic products with high heat dissipation requirements, multi-layer circuit boards can be equipped with metal core heat dissipation layers, which is convenient to meet special functional needs such as shielding and heat dissipation.

　　In terms of performance, multi-layer circuit boards are superior to single double-sided boards, but the higher the number of layers, the higher the production cost, the longer the processing time, and the more complex the quality inspection. However, in terms of cost comparison for the same area, although the cost of multi-layer circuit boards is higher than that of single and double layers, the cost difference between the two is not as significant when considering the factor of reducing noise lamps. With technological progress, there are now over 100 layers of PCB boards, which are mostly used in precision aerospace instruments and medical equipment.