Blind Vias start on an outer layer but terminate on an inner layer, buried Vias exist only between inner layers and do not begin or terminate on an outer layer.
Another variant of these technologies is stacked vias. Stacked Vias are used when a blind via is required but exceeds an aspect ratio of 1:1 and cannot be formed through sequential lamination due to another blind or buried via beginning on the same layer as the blind via's termination layer.
Stacked Vias is used commonly on High Density Interconnects (HDI) PCBs. Blind, buried, and stacked vias are used to save PCB dimensions. Blind & buried PCB Capabilities
- Blind/buried vias with mechanical drills
- Blind/buried vias with laser drills
- i+N+i (i≥1), Any-Layer HDI
- Multilayer copper filled stacked micro via structure
- 1.5/1.5 mil line/space
- Complex rigid-flex with blind/buried vias
- Via in PAD fill types: non-conductive epoxy, conductive epoxy, copper filled, silver filled and electrochemical plating