What is Backdrilling in PCB Fabrication?

Vias PCB Fabrication 
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Editorial Team - PCB Directory

Aug 17, 2020

Back drilling or Controlled depth drilling is a process used to remove the unwanted portion of a PCB Via Stub. Plated Through Hole (PTH) Vias are used to connect two or more layers of a Printed Circuit Board to each other. However often, a via does not need to run the entire thickness of the board to connect each layer. For example, if we have a 10 layer PCB and need to connect layer 1 to layer 3 using a via, the PTH via runs through all the layers of the PCB even though layers 3 to 10 do not need to be connected to each other using that particular via. This unused portion of the via is called a stub. These stubs can cause significant signal distortion (click here to read more about PCB via Stubs).

Backdrilling is a technique used to remove the unused portion of the stub (conductive plating) in a printed circuit board. This is removed by using a drill that has the diameter slightly larger than the diameter of the original via (PTH) hole.

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