For the design of the chip density and the high clock frequency, the design of the 6 -layer board should be considered. It is recommended to stack the layer:

　　1. Sig -GND -SIG -PWR -GND -SIG; For this scheme, this superposition layer scheme can get better signal integrity. The impedance of the wiring layer can be better controlled, and both floors can well absorb magnetic lines. And in the case of power and strata, it can provide a good return path for each signal layer.

　　2. GND -SIG -GND -PWR -SIG -GND; For this solution, this plan is only applicable to the situation where the density density is not very high. This layer has all the advantages of the above layer, and this top and bottom layer The horizon is relatively complete and can be used as a better shield. It should be noted that the power layer should be close to the non -main component surface, because the plane of the bottom layer will be more complete. Therefore, EMI performance is better than the first solution.

　　Summary: For the solution of the six -layer board, the distance between the power layer and the formation should be reduced as much as possible to obtain good power and ground coupling. However, the 62mil plate thickness, although the laminar spacing is reduced, it is not easy to control the distance between the main power and the ground layer. Compared with the first plan and the second solution, the cost of the second solution is greatly increased. Therefore, when we lay the layer, we usually choose the first solution. When designing, follow the 20H rules and mirror layer rules.