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?


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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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