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From [log in to unmask] Sat Apr 27 14: |
18:16 1996 |
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HADCO uses LPI soldermasks almost exclusively, and we also
"plug" the vias from one side with a wet mask dot pattern.
Tha only difference is that we perform the process in the
following sequence:
LPI soldermask
hot air solder level
wet mask via plug
In this way, the via barrels have a solder coating on them,
which we consider more reliable.
I agree with you 100% that this is almost a technology step
backwards, but it is the best we can do for now for those of
our customers who need plugged vias, either for vacuum
purposes at loaded board test, or to reduce bridging vias
sitting under components.
Always make sure that you don't plug a via which is needed
as a test point. We have also found it difficult to plug
vias drilled >.020".
Tom Coyle
Customer Services Engineer
HADCO Corporation
[log in to unmask]
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