Steve,

While it is not an "easy" process, I know a number of companies that have
done the dry over liquid process for several years. Your fab shop needs to
verify the LPI is compatible with the dry film and there are a few tricks to
make it easier. If you contact one of the solder mask services (Solder Mask
Inc, Mask Tek etc) they can do the job for your vendor or perhaps give them
some tips to help them do it themselves.

Regards,
Bob

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Stephen Gregory
Sent: Thursday, June 02, 2005 3:36 PM
To: [log in to unmask]
Subject: [TN] Dry Film "Soda Strawing"...an update.


Hi all!

We just had a conference call with the fab vendor about our soda strawing
issue.

They acknowledged that the fabs are defective, but asked for a deviation
to notes on the fab drawing. We can't approve any deviation without asking
our customer first.

The drawing calls out for 4-oz copper, and 4-mil dry-film solder mask. The
mask being used is Dupont Vacrel 8140. The assembly is a power supply.

They want to apply a LPI, then apply the dry film. I understand that
applying
a 4-mil dry film over 4-oz. copper traces is difficult and challenging, but
can
it be done without these kind of soda strawing defects?

Kind regards,

-Steve Gregory-
Senior Process Engineer
LaBarge Incorporated
Tulsa, Oklahoma
(918) 459-2285
(918) 459-2350 FAX
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