> > As to the OP's original problem, the only way to determine just where
> > the break is on an inner track will be a TDR measurement compared to a
> > good PCB, as mentioned previously in this thread. The problem is you
> > will need a TDR capable of doing picosecond measurements to get any
> > sensible length measurement unless it is a very long track. Maybe time
> > to call on your local (what used to be) HP or Tektronix rep for an
> > instrument demonstration. :) The rest of us would just put a patch
> > wire on, call it fixed and wait for another failure if it really is a
> > via breakaway problem.
> >
>=20
> Thanks for the detailed discussion! In x-rays, it appears that one layer =
is
> misregistered by about 5 mils. We're thinking this can cause an occasiona=
l via
> failure. The sample size is still really small, but is causing us concern=
..

That's a tad over 0.1mm, which shouldn't be a problem unless using very sma=
ll pads ... but then I am used to working to ESA specs which require someth=
ing like 0.2mm land width around the hole.



--=20
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