Filling VIA in pad - Assembled
[Editor's note: This post is the third and final of a three-part post about a rather difficult and undersireable via in pad PCB. This board violates industry-wide recommended practices. The right thing to do in a case like this is to redesign the board without vias in the pads or have them plugged at the board house. We did get this one to work, but it wasn't a sure thing. Some designs require vias in the pads. If you have one of those, get the vias plugged and plated over at the board house. If you don't, you can ask us to try what we did here. It may work. It may not. There are no guarantees in a situation like this and in may incur additional labor charges. Call first for situations like this.]
It's long back to the customer, so it's probably about time I finish this series. If you didn't read the prior posts, we received the board with large vias in some of the BGA land pads, we filled the vias, and now, we've assembled the board.
The top view shows the Bluetooth radio module BGA happily secure on the board and the inset shows the underside of the board with all of the solder still in the via holes where it should be. The vias were plugged with high-temperature solder prior to assembly. Once plugged, the the board was assembled just as it would have been if did not have vias in the pads in the first place.
Again, please don't ever do this. We were lucky in this case. If you absolutely must put vias in pads, read all of our other via in pad posts for recommendations on how to properly handle them.