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PCB with Blind and Buried Vias

Basically the blind and buried vias are popular to be designed on high density PCBs due to the limit of small space, the blind and buried vias can only pass through necessary layers and more surface area become available for components, they have the ability to meet the density constraints of line and pads on a typical design without increasing the layer count or board size and reduce the PCB aspect ratio for convenient production.


Blind Vias

Blind via is a copper plated hole that connects only one outer layer to one or more inner layers, it never goes all the way through a circuit board but only visible on one side of circuit boards. The blind via can be laser or mechanically drilled based on the detailed via hole size and layer stackup.


Buried Vias

Buried Via is a copper plated hole that connects two or more inner layers without contacting the outer layers, as the name suggests, it’s buried inside, so it’s not visible from the outer layer of PCB. Buried via has no impact to any trace or surface mount component on the top or bottom layers, trace or SMD pad can be placed directly over the buried via.

A-TECH CIRCUITS has capacity to build both of blind via and buried via with different demands, We’ll use laser drill for the blind vias with size smaller than 150um and use mechanical drill for the blind via size larger than 150um, the technology of blind via we can achieve include via in pad, stacked via and staggered via. The minimum size of buried via normally need to be 150um and they’ll be plugged with resin to avoid prepreg flow into buried via which might affect the connection with adjacent layers.