A
6 Layer PCB board is in general a
4 Layer PCB board with 2 extra signal layers added between the planes. The 6-layer
PCB classic stackup includes 4 routing layers (2 outer layers + 2 internal layers) and 2 internal planes (one for ground and the other for power). This enhances the EMI dramatically by offering 2 buried layers for high-speed signals and 2 surface layers for routing low speed signals. The signal layers should be closed to the adjacent planes.