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January 2004

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Subject:
From:
"Barmuta, Mike" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 13 Jan 2004 14:01:46 -0800
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text/plain (86 lines)
Steve: I think this is a board surface to mask adhesion problem as opposed
to a problem with the mask chemistry or cure.
1.If you have additional unprocessed boards, run one thru the washer without
the wavesolder exposure. If the board comes out without the mask peeling or
very slight peeling it's properly a pretty good indicator that the mask is
correctly formulated and cured.

2.Run the same board thru the normal wavesolder process, which stresses the
mask due to CTE mismatch, then wash. If the mask lifts it's probably the
surface prep of the board prior to SM dry film lamination.

Also if the mask is not coming off from the topside of the board it would
point more to scenario 2.


Regards

Michael Barmuta

Staff Engineer

Fluke Corp.

Everett WA

425-446-6076



-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Steve Gregory
Sent: Tuesday, January 13, 2004 1:01 PM
To: [log in to unmask]
Subject: [TN] "Snake Board"...


Hi All!

You're probably wondering; "What the heck? Snake board?" That's what I call
it.

Built this assembly (all PTH), waved it, and then washed it, went to get it
out of our cleaner, and all the solder mask is coming off in big slabs just
like a snake does when he sheds his skin! Go look at "Mask Peel, Mask Peel
2, &
Mask Peel 3" at:

http://www.stevezeva.homestead.com

I wash in a Electrovert MCS-1000 with Kyzen XJN, and the mask on the board
was a Dupont Vacrel dry film. Never have had a problem with Vacrel dry
films.

The mask doesn't look degraded, or damaged in any way...it's just not stuck
to the board! Anybody ever seen this happen before? Unfortunately, this was
a
rather expensive assembly.....:^{

Nice way to start the year off, huh?

-Steve Gregory-

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