----- Original Message -----
Sent: Tuesday, January 28, 2003 11:02
AM
Subject: [TN] Flaking Mask
Hi All!
I've
got a problem that I ran into a few years back, and I thought I had solved it.
We've built a couple of pretty pricey assemblies ($4,000 +), that has
the mask flaking off of all copper features. Via's, traces, everything...
When we had this problem before, a Dynachem Dynamask dry film was
used. Since then, whenever dry film mask is called out on the fab drawing, we
specifically call out Dupont Vacrel 8100, since we learned back then that this
dry-film is not affected by the Aquanox XJN we use in cleaning. Go to:
http://www.stevezeva.homestead.com and look at MaskFlake 1-3
The mask flakes off when it is washed in our Electrovert MCS-1000
batch cleaner after 2 or 3 wash cycles. We use the Kyzen Aquanox XJN according
to the manufacturers specifications. We run it in a 20-25% concentration with
DI water. The concentration is measured twice a day with a refractometer. The
cleaning cycle is as follows:
6-minute wash
4-minute rinse
2-minute final rinse
6-minute dry
Wash Temperature 140 F.
Rinse Temperature 110 F.
We have two fully loaded assemblies that
exhibit this problem, and at $4,000 each, this is not good.
The fab
vendor swears that the Dupont dry film was used. But over the past few years
since we've always called out the Vacrel, we have NEVER had the problem like
we did with the Dynachem Dynamask.
Have any of you ever had this
problem? Is there any way (visually) to tell the difference between the Dupont
and the Dynachem?
The way this mask came off, sure is like it was the
Dynachem dry film...
-Steve Gregory- ---------------------------------------------------
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