I’m looking for guidance on when to choose backdrilling a through-hole via versus using a blind via in a PCB design. In what scenarios is one preferred over the other?
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If you’ve got a high speed signal going through a standard TH via but it only needs to connect a few layers backdrilling is a good way to clean up the extra stub. It helps with signal integrity and is usually more cost effective than redesigning the stackup.
Blind vias are useful when you’re tight on space like under a dense BGA and don’t want the via going through the whole board. They cost more, but sometimes you just need them for routing.
I would say use backdrilling when you’re already using through holes and need to reduce reflections. Use blind vias when you’re doing dense routing or need to save space vertically. But I’m not a designer so someone from our design team might have a different take.
Backdrilling is generally less expensive to fabricate than blind vias since it involves fewer processing steps. However, since you start with a full through-hole via before removing the unused stub, it still requires space through the entire board thickness and additional clearance for the oversized backdrill.
Blind vias, on the other hand, only extend to specific layers, which can free up routing or copper space on other layers. They’re useful in dense designs but are more complex to fabricate and plate, especially for deep or high-aspect-ratio barrels. There’s also a higher risk of trapped chemicals or contaminants during processing, which can affect reliability if not managed carefully.
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