Werner Engelmaier published an excellent article "Soldering:Quality and
Reliability Issues" I believe in Global SMT magazine. I have a paper
copy but it does not show the date it was written. Werner, perhaps you
could help with this?
The dissolution rates of various alloys into tin are detailed in
Klein-Wassink's Soldering in Electronics.
You may wish to perform a search in the forum using the word
"dissolution", and you may find a number of postings on the subject.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gervascio, Thomas
Sent: Friday, January 19, 2007 8:05 AM
To: [log in to unmask]
Subject: [TN] Minimum solder reflow temperatures for ENIG board finish

One rule of thumb that I used over the years was when soldering eutectic
solder (Sn 63 Pb 37) on ENIG board finishes to run the profile a bit
hotter than HASL. Instead of say 205 C I remember literature citing 217
C as the minimium temperature with the rationale being that nickel
diffusion rates into solder are much slower than copper. 
 
I did several internet searches for some supporting literature and
couldn't readily find any. Any ideas where I could find some supporting
evidence and/or literature?
 
Thanks
Tom Gervascio

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