Victor, are you doing via in pad with these PTH's, or are these on the
other side of a mask dam from the BGA ball?

If not, your main problems would be entrapped chemistry and the possibility
of protruding fill/plug material interfering with the assembly process. You
also have the mask fill manufacturing issues discussed a few months ago on
the designercouncil list, where a few people described issues getting
manufacturers up to speed and guaranteeing sufficient fill.

If you are doing Via in pad, you're likely to have entrapped chemistry,
head on pillow, entrapped air causing thermal expansion issues,
incompletely filled vias causing solder thieving... and probably more. I
don't recommend it without a lot of experimentation and representative
coupon microsections.

Tom

On Fri, Apr 7, 2017 at 11:54 AM, Joyce Koo <[log in to unmask]> wrote:

> HOP if not done properly.
> > CON - creates a flux trap leading to corrosion
> >
> > ------------------------
> > Ed Hare
> > [log in to unmask]
> >
> >
> >
> >
> >> On Apr 7, 2017, at 8:14 AM, <[log in to unmask]>
> >> <[log in to unmask]> wrote:
> >>
> >> Fellow TechNetters:
> >>
> >>   What are the PROS and CONS on inadequate, partial, small PTH
> >> fill/plugging under BGA?
> >>
> >> Victor,
> >
>