1. The multi-layer circuit board has high assembly density and small volume.

2. The multi-layer circuit board is convenient for wiring, and the wiring length and the connection between components are shortened, which is conducive to improving the speed of signal transmission.

3. For high-frequency circuits, after adding the ground layer, the signal line forms a constant low impedance to the ground layer, the circuit impedance is greatly reduced, and the shielding effect is better.

4. For electronic products with high demand for heat dissipation, multi-layer circuit boards can be provided with a metal core heat dissipation layer to meet the needs of special functions such as shielding and heat dissipation.

5. Functionally, multi-layer circuit boards of smart audio circuit boards are better than single and double-sided boards, but the higher the number of layers, the greater the manufacturing cost, the longer the processing time, and the more complicated the quality inspection.

6. The common multi-layer circuit boards of smart audio circuit boards are four or six-layer boards. The difference between the four-layer board and the six-layer board is that there are two more internal signal layers between the middle layer, the ground layer and the power layer. Six-layer boards are thicker than four-layer boards.