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February 2001

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Subject:
From:
"Stephen R. Gregory" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 20 Feb 2001 19:52:09 EST
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Hi Tenison!

I normally don't have problems, but there has been a few occasions where I've
had stencil foils release from the mesh...the mesh has never released from
the frame.

I clean using Kyzen IONOX in a "vintage" Conceptronic cleaner...no
ultrasonics...but I have used ultrasonic cleaners at many past
employers...never had problems. Most stencil vendors are pretty current as
far as what everybody uses to clean their stencils with, and it's been my
experience that the epoxy that they use is pretty robust.

In the occasions where I did have a problem, I contacted my stencil vendor
and relayed the problem to them. Also on these occasions it's happened only
after 3 or 4 uses. What was relayed back to me was that more than likely the
surface of the foil where the mesh is bonded to the foil wasn't prepped as
well as it should have been, I was told that it's should be "roughened-up"
slightly and cleaned well for the epoxy to make a good bond.

The stencils that did that on me did have holes etched around the perimeter
of the foil (as usual) that provides a good area for the epoxy to penetrate
and make a good bead. But the mesh released (along with the bead of epoxy)
anyway...so it seems to me that a good surface prep needs to be done on the
foils to prevent that from happening.

My vendor took the stencils back and remounted them free of charge...it's
only happened a few times with me.

-Steve Gregory-

<< Hi everyone!

 My problem today has to do with stencils for solder paste printing.

 We are having a lot of problems with the glue releasing when we go to use
 the stencil.   Packing tape will hold through the end of the job.  The
 temperature is OK and the time in cleaner is acceptable according to the
 stencil vendor.

 We have checkout our stencil cleaner and the parameters on the various
 printers.

 We have had our stencil cleaner for many years and only had the problem in
 the last year.'

 We have had no luck with the problem and the stencil vendor is also
 confused.

 Has anyone had this problem before and found a solution?

 Tenison Stone
 Telex Communications >>

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