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September 2005

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Subject:
From:
"Victor G. Hernandez" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Tue, 20 Sep 2005 13:42:03 -0500
Content-Type:
text/plain
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text/plain (110 lines)
My two cents worth would add that plugging one side of the barrel could
entrap PWB and/or assembly process contaminants which could attack the
barrel at a later date.

Victor,

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Mcmaster, Michael
Sent: Tuesday, September 20, 2005 11:36 AM
To: [log in to unmask]
Subject: Re: [TN] My "Okie" cross-section...an epilog.


Steve

I don't mean to be argumentative or disagree with the lab that did such
a fine job on your boards, but I believe you could consider these boards
defective IF they caused you a problem.  The button plate used for the
filled vias is way too thick.  This carried over to the surface and
subsequent Planarization did not remove the button on the surface.  You
can see evidence of the attempted planarization in the cross section of
the vias.  The "button" comes up out of the whole in a nice smooth arc
then appears beveled.

If I were to hazard a guess, I'd say the plating area on the filled vias
was too high and they were overplated.

Given the vias are filled because they are in a solderable pad, most of
my customers would send them back because of assembly issues (real or
anticipated).



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Monday, September 19, 2005 5:53 PM
To: [log in to unmask]
Subject: [TN] My "Okie" cross-section...an epilog.

Good Evening All!

Well, I now know as much about the raised vias on a board for an a
assembly that we built as I could hope to know. A very professional and
informative cross-section was done on the fab that contained blind vias
that were used in SMT pads. The lab report was done by a fellow
Technetter and his team that have asked to remain nameless.

If you recall, these vias looked like little "anthills" in the pads, and
there were many opinions offered as to why these vias looked the way
they do, from pre-preg resin flowing up through the vias during
lamination, to not planarizing the fab after via fill. I think you will
find the report and cross-sections informative and interesting.

Go to: http://www.stevezeva.homestead.com/files/Raised_Vias.doc

Thank-you "Mr. Nameless" and your team for your excellent work!

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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