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March 2004

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Subject:
From:
David Hoover <[log in to unmask]>
Reply To:
David Hoover <[log in to unmask]>
Date:
Sun, 28 Mar 2004 10:10:42 -0800
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The only time I've encountered this in the (far) past was when the epoxy was
not fully cured and had substantial air pocket voids.
At the time, it was being used for finepitch BGAs (like .8mm pitch or less).
There is other media's to use to fill those vias.
Non-conductive epoxy is one. It doesn't have the metal particles that can
create havoc when filling high aspect
ratio holes. I've seen this stuff used on even bigger holes than what has
been discussed here with success through assembly
cycles. (Not lead-free temperatures-yet)

Cheers,

David Hoover  aka, Groovy

http://home.earthlink.net/~dhoovy
----- Original Message -----
From: "Rick Thompson" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, March 23, 2004 9:36 AM
Subject: [TN] PWB delamination and silver epoxy fill


We have some boards we're building for a customer that they have spec'd in a
conductive silver epoxy fill for the through-vias. During reflow, these
boards are delaminating in some areas, always radiating out from a via. The
PWB vendor is saying that they believe this is related to using the silver
epoxy with FR4 and are recommending a change to Gtek or something similar in
Tg.

My question is, is this a common occurrence with FR4 and this type of silver
epoxy fill?

Thanks in advance,


Rick Thompson
Sr. SMT Process Engineer

SMTEK International, Inc.
+1 (805) 532-2800
[log in to unmask]




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