Steve -

You will not be successful with 8140 material with a 4 oz copper finish.
There are conformable materials like conformask that will model the
conductor finish.  If the OEM will not budge on the DFSM finish, you can
apply an LPI initially, then overcoat with DFSM.  The initial LPI
coating levels the base to the conductor somewhat and should resolve
this issue.

Jeffrey Bush
Director, Quality Assurance and Technical Support

VERMONT CIRCUITS INCORPORATED
  76 Technology Drive - POB 1890
    Brattleboro, Vermont 05302
      Voice: 802.257.4571.21 Fax: 802.257.0011
           http://www.vtcircuits.com
 

-----Original Message-----
From: Stephen Gregory [mailto:[log in to unmask]] 
Sent: Thursday, June 02, 2005 6:36 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
__________________________________________________________________
This message may contain information that is privileged and confidential
to
LaBarge, Inc.  It is for use only by the individual or entity named
above.
If you are not the intended recipient, you may not copy, use or deliver
this message to anyone.  In such event, you should destroy the message
and
kindly notify the sender by reply e-mail.

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