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March 1999

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Subject:
From:
Paul Wilson <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 31 Mar 1999 10:43:22 -0500
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Jim,

There are many theories and proofs out there.  The one thing I was
interested in was that at temperatures above 450F,  tin metal can alloy
nickel at a small percentage.  The pastes used would dictate temperature of
reflow, but it is not known how these pastes would behave toward the nickel
compared to tin metal.

Let's say you were around 430F +/- 40F.

What if the "black pads" are formed as the hot ones?
A ternary or quaternary phase diagram of the metals would be useful
(Sn/Pb/Au/Ni).

Just speculating,
                 Paul Wilson
               Plant Chemist  /  R&D Manager
                   Circuit Center, Inc.
                 4738 Gateway Circle
                  Dayton, OH 45440

          Phone (937) 435-2131     Fax (937) 435-7698
            http://www.circuitcenter.com

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