> I typically use a 0.012 +0.003/-0.012 finished (Allow the via to plate shut)
> with a 0.025 pad.
> My vendor can do            finished hole diameter + 0.014
> He would drill at 0.016 (no cost hit) and plate back to 0.011    add the 0.014
> and you get 0.025.
>
> I agree with Cyrus on the test pad size at 0.035.  Build your via with a 0.025
> on all layers except the probed layer which could be 0.035.

I think this .025 via size sounds more realistic if you are space
constrained. However I don't recommend using .035 on the probed
layer. Only one probe point per net is needed, if in fact you even
need ICT. If I need test points, I use a unique via pad stack for test
points only, so that I can selectively unmask the test points and
mask over the other vias.


Dave Farthing
Gordian Design Services

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