A buried via joins two or more inner layers without reaching either outer surface. It is drilled and plated in an inner core or sub-laminated stack before that piece is pressed into the full board, so buried vias add drilling and plating cycles and often extra lamination cycles. Buried vias free surface and outer-layer routing space and appear in dense multilayer and HDI boards, often alongside blind vias and microvias.
Layers 3 to 6 get a buried via set so the inner pairs can swap layers without eating space on top.
Also heard as
- buried via hole
Related terms
Blind via
Via that starts on an outer layer and ends at an inner layer without passing through the whole board.
HDI
High-density interconnect: boards built with microvias, fine lines and sequential lamination for dense parts.
Microvia
Very small laser-drilled via, typically 0.15 mm or less across, spanning one thin dielectric layer.
Stackup
Ordered arrangement of copper layers, cores and prepregs that makes up a multilayer board, with each thickness.