# Do I need to fill in the vias under BGA pads?

I have a very dense BGA footprint. There is no way I can place the via between the pads - the PCB manufacture's tolerances do not let me. Also, the thinnest allowable traces do not fit between the pads. One way to do this was place via right under the pads. But because of the via's hole right under the pad, I am afraid that I might not solder it properly (the pad diameter of the via is essentially equal to the pad for the BGA ball). Filling the holes with non-conductive material costs 5x more expensive. Should I look for a component with the larger BGA pitch, or not filling the via will be ok?

• What about finding a board house that is more capable of handling features associated with BGA packages? – Matt Young Oct 21 '14 at 19:53
• @MattYoung 6/6mil trace/space, 8/18 via hole/pad. Is that bad? – Nazar Oct 21 '14 at 20:03
• @Naz, yes, that's a low-cost, low-performance shop. 4/4 space trace and 4/14 vias are pretty common. Even smaller vias can be done with laser-drilling. – The Photon Oct 21 '14 at 20:14
• @ThePhoton Well, without filling the via - $60 per board, with filling$250. They can do 4/4, but they said it will cost more than filling. – Nazar Oct 21 '14 at 20:34
• Also if you don't fill during re-flow the solder from the BGA balls will likely be sucked right down those via holes to the back of your board. – Some Hardware Guy Oct 22 '14 at 20:58