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July 1998

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Subject:
From:
Charles Barker <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 10 Jul 1998 13:28:02 -0500
Content-Type:
text/plain
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text/plain (79 lines)
Todd, you do not say how thick this stencil is.  With all this polishing
and plating, could your opening have decreased below the 1.5:1 ratio?






Todd Ness <[log in to unmask]> on 07/10/98 04:13:28 AM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
      to Todd Ness <[log in to unmask]>

To:   [log in to unmask]
cc:    (bcc: Charles Barker/US/I-O INC)
Subject:  [TN] Electropolishing Laser-Cut Stencils




Hi all,

We are currently having problems with a laser-cut stencil that is
electropolished and nickel plated with 9-mil openings. The paste does
not release well from the apertures. We are having to wipe after every
print. The board is fixtured well and we have been using the same
paste for the last two years. We had a different laser-cut stencil in
production from a different manufacturer with the same 9-mil opening,
but this stencil was not electropolised or nickel-plated. With this
stencil, the paste release was excellent and we never had to worry
about wiping.

Does anyone have any input into whether or not laser-cut stencils
should be electropolished and nickel plated? I have heard
contradicting opinions on this subject. One source has said that you
do not want to electropolish laser-cut stencils because the
rough laser walls will give you a better paste release. Whereas,
another source has said that the smooth laser walls will give you a
better paste release.

Also, what benefit does nickel plating give you? Does the paste tend
to roll better with nickel plating? Do you tend to get more or less
paste deposit on the boards with nickel plating? Does it increase the
life of the stencil?

Has anyone using laser stencils seen major differences between
the quality of different stencil manufacturers?

Any input into this subject would be greatly appreciated.

Thanks,
Todd

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