Actually the photo imagable mask should all be SMOBC due to the attach
of the solder finished during developing for that old technology.
Deposited masks did not have the issue and since the technology for
developing a SMOBC board with deposited mask had some issues, some OEM's
began to be specific on drawings for SMOTL.  We refuse any orders not
willing to be revised to SMOBC.



Jeffrey Bush
Director, Quality Assurance and Technical Support

                          76 Technology Drive - POB 1890
                             Brattleboro, Vermont 05302-1890
                                Tel. 802.257.4571.21 Fax. 802.257.0011
                                    [log in to unmask]
                              http://www.vtcircuits.com	



-----Original Message-----
From: Steve Gregory [mailto:[log in to unmask]] 
Sent: Wednesday, March 31, 2004 4:41 PM
To: [log in to unmask]
Subject: [TN] Solder mask over Tin/Lead...


Hi All!

I'm just wondering if I'm missing something. Is there any performance
reason whatsoever, that requires solder mask over Tin/Lead instead of
using SMOBC (Solder Mask Over Bare Copper)?

Got a board in receiving inspection that I got called back to look at
because the mask was failing tape test. When I saw the board, it was
solder mask over Tin/Lead, just like it was called out on the drawing.
The mask had already lost adhesion in a few places, but we hadn't done
anything to it yet assembly-wise...

I see didn't see this particular boards drawing before we went out and
bought it, otherwise I would have thrown-up a red flag then. What
suprised me though, is that our fab vendor didn't say anything before
they built it. Is anything other than SMOBC being used regularly. I
thought solder mask over Tin/Lead was ancient stuff, and that everybody
learned not to do that anymore...

-Steve Gregory-

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