Hi Jack,
Our test point pads are usually specific...we don't
tend to unmask the vias for this.
The data / coordinates are contained within the smd
pick and place file with their own unique identifier. They basically extract
this data afterwards and modify it as needed.
Together we decide on the required test points
beforehand (usually they exagerate and add points that are not needed
later) and luckily there have not been many modification requests afterwards. If
there are they lets us know via pilot run reports etc.
Sorry it's not directly answering your
question...
Paul.
I'm wading into deeper water
these days...
We have vias that can be used
as test points that are 40mil pads
with 13mil holes. Normally we
would like mask to cover most of
the pad but not the hole, so we
have an 18mil aperture on the
mask layer.
Whenever these vias are USED as
test points, we have to open
up the mask and leave them
fully exposed.
The problem is, no matter how
hard we try to generate test point
data, during test fixture
development they end up inserting a few
more, moving them around, etc.
which means we either have to
modify the mask or leave ALL of
them exposed. We are discussing
now to modify the mask to
minimize the possibility of solder shorts,
preferably without having to
change the board revision.
Has anyone else had to deal
with this situation?
I would be interested to know
if you are generating test point data,
Is it really good enough?
Or,
Are they modifying it in
production?
If so, do they make an effort
to get the TP changes back to you?
the man with the mask,
Jack
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