At 05:48 PM 4/16/96 PST, sbryan wrote:
>     
>     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
>[log in to unmask]
>     
>
>
Using the term "dry film" as a generic is not wise. there are high
conformance dry film masks that are .001 - .002 inch thick. These masks are
designed for smt use and should not be ruled out, or worse, placed in the
category of thicker dry film masks.
Regards,

Gary Ferrari
Tech Circuits
(203)269-3311
[log in to unmask]