Simple six layers first-order HDI (one-time pressing of 6 layers boards, the stackup structure is 1+4+1) There are only through holes and blind vias in the board, but no buried vias. The difference between this situation and the through-hole board is only without blind vias. HDI PCB Stacture needs one press fit, plated blind vias and through holes in production. The difference between six-layer HDI and multi-layer boards is that multiple processes such as laser drilling blind holes are required.

This HDI 1+4+1 stackup structure has no buried holes, so in the production, the 1 layer and 3 layers can be used as a core board, the 4 and 5 layers can be used as another core board, and the outer layer can be added the dielectric PP layer and copper foil. And are laminated together after adding the dielectric PP layer in the middle. This manufacturing simplifies the structure and saves manufacturing costs, and also shortens the production cycle.

6 layer first-order blind buried via HDI, this HDI PCB board cancels through hole structure. And the 6 layers first-order blind buried via HDI structure needs to be laminated twice, plating the buried vias once, and resin plugged holes once, plating Blind vias once. This HDI structure also saves a certain amount of cost and shortens the delivery time. Please see the follow 1+4+1HDI PCB without through vias stackup.

Standard 6 layer HDI 1+(Press 6 layers at a time, the stackup is (1+4+1)), this type board stackup is (1+N+1), (N≥2, N is even number), This 6 layers HDI 1+PCB board has through holes, buried vias, and blind vias. This 6 layer 1+ HDI PCB stackup is the mainstream design in the industry. This process is the most complicated, requiring two pressed, once plating buried vias, once resin plug hole, and once plating blind vias and through holes.