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December 2000

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Subject:
From:
"Stephen R. Gregory" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 14 Dec 2000 19:03:34 EST
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In a message dated 12/14/00 4:29:20 PM Central Standard Time,
[log in to unmask] writes:

<< Is it possible the solder in these connections is reaching the plastic
 stage, crystallizing and then loosing it's strength?  If so, why doesn't
 this happen to others in the industry running this process? >>

Hi Jim!

Don't consider yourself the "Lone Stranger" with this problem, I've had this
too. It's mostly been where there's a via connected to the pads with a very
short trace. Heat transfer through the traces would conduct enough heat to
cause exactly what you are seeing.

A fixture as what was suggested would work, but what we wound up doing was to
use a liquid mask to mask off the via's that connect to the QFP pads...and
that solved it. The volume of the boards weren't enough to justify fixtures...

It's a design problem...that's why I think that the guys that lay-out these
"jewels" need to come on down to the production floor and see what we have to
go through to build their creations....

-Steve Gregory-

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