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
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