Hi All!

This is my first post to the Designers Council. I have a question about
solder masking via's in a BGA pattern, and want to see if I'm thinking  correctly.
I'd like your opinions about this.

I think it's a bad idea to leave the via's free from solder mask on the
topside of the board beneath the BGA, and then tent (or plug) the via's from the
bottomside. To me, you're just asking for trouble down the road because you're
 creating a little "cup" if you will, that willl trap flux residue and all
kinds of stuff in the via's that won't be able to be cleaned out well. This is
a  676 ball 1.0mm pitch BGA pattern.

This assembly will be put together using double-sided reflow, there will be
no wave soldering. All through-hole is going to be hand-soldered.

My opinion is that either you leave the via's free from solder mask on both
sides, or cover them on the topside only, or ideally, plug them  completely.

Am I wrong about this?

Thanks!

-Steve Gregory-


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