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| From [log in to unmask] Wed Apr 24 11: |
06:02 1996 |
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I am surprised that an one is still using dry film soldermask. And
even more shocked that anyone has just started to use dry film. I was
sure that the entire industry has converted to LPI.
Why are you using dry film soldermask?
______________________________ Reply Separator _________________________________
Subject: ASSY: Dry film mask and paste thickness
Author: [log in to unmask] at corp
Date: 4/16/96 3:47 PM
We have just started using a dry film mask(Vacrel), which is about .003"
thick. We are using a .006" stencil and printing .020" pitch parts, and are
measuring paste thickness of about .009". We are using a metal squeegee,
but seeing some "dog ear" looks to the paste. We seem to be getting a poor
separation of paste from the stencil. The mask is about .0005" higher than
the pads. Our variation in paste height measurements on a board has
increased by .002" from Photo Imageable to dry film.
Are there any ideas on how to process a board with Vacrel to improve our
printing process?
Thanks for any ideas/suggestions.
Steve Quinn
Heurikon Corp
8310 Excelsior Dr
Madison, Wi 53717
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