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February 1999

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Subject:
From:
Ryan Jennens <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 18 Feb 1999 17:12:49 -0500
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Evenin' all!

        My question is this:  My stencil printer operator has said that he has to
wipe our 6-mil stencil each pass to get the paste in the 20-mill pitch
aperatures for a QFP to release well.  We are using Amtech NC-559 type 3
paste with 89.5% metal.  The paste is not old.  I considered using type 4
paste, which has a much finer powder in it. I was told by Amtech that this
finer powder paste will pack more densly into the aperatures and I could get
some bridging, unless I order a new stencil with aperature reductions.  Our
squeegee speed is 0.6 inches/s, or 15mm/s.  Is this too slow?  Amtech
suggested that at this slow speed, the paste could be rising out of the
aperature, as if someone pressed on a wet sponge and it rose back to its
original shape.  What is a good squeegee speed for 20 mil pitch parts?
Thanks all!

Ryan Jennens
TelGen Corp.

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