Lee, Harvey,
Checking my bibliography on lead-free electronics at
   http://www.dbicorporation.com/rohsbib.htm
the only item that I can find by Wenger and Furrow is

Wenger, George M., and Furrow, Robert G., "Immersion Silver Surface
Finish: Usage Requirement Test Results &  Production Experience,"
Proceedings of the AESF SUR/FIN 2000, Chicago, IL, June 26-29, 2000, pp.
xx-xx.

Is this the one that you were referring to?  (I won't have access to the
paper itself until I get home, in about a week.)

I hit 9 engineering/science libraries in Missouri, Kansas, Colorado,
Utah, and Oregon during my drive from Lexington, Kentucky out to
Portland, Oregon for the IEEE EMC Symposium.  So far on this trip I've
found about 30 additional papers, going back to 1869, that were on my
want list at
   http://www.dbicorporation.com/rohswant.htm
I intend to hit the libraries at another 7 engineering schools on the
drive back home.

At the University of Colorado - Boulder I ran across:

   Ditz, M. J., "Determination of the Moisture Threshold for Silver
   Migration,"  Proceedings of the 20th International Symposium for
   Testing and Failure Analysis, Los Angeles, CA, Nov. 13-18, 1994, pp.
   181-187.

This paper says that approximately 40% relative humidity (RH) is
required for silver migration to occur.  They used chip capacitors
attached to a hybrid with silver epoxy for their tests.  The gaps
between exposed silver particles in adjacent joints were in the micron
range.  With 50V bias at 50C, they saw one failure withing 48 hours at
43% RH.  At 40% RH they saw no failures in an additional 640 hours,
whereupon they terminated the test.

I hope that this helps!

John Barnes KS4GL, PE, NCE, NCT, ESDC Eng, ESDC Tech, PSE, SM IEEE
dBi Corporation
http://www.dbicorporation.com/

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