Theme: Pad, soldering point, via, plated-through hole
In a BGA we would like to use vias in the pads. How can these pads be covered with solder resist on the bottom side?
We don't have space for dog bones in our 0.5 mm pitch BGA, so we want to have a drill hole in each BGA pad and the pad on all layers. But for that we want it to be covered with solder resist on the bottom side.
Answer: For example, you could basically do the pads on layer 100 without a soldermask and manually draw slices (= filled circles) into the soldermask layer on the top side.
You could also create a padstack for these pads. You enter all copper layers and additionally the solder stop on the bottom. Exactly for the latter, you enter a negative addition, so that practically nothing of it remains. You could also reduce the inner pads a bit in this padstack to have more space for routing.
You can save all this within the respective package in the components database.
