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Hi Jerry -
The reference I have always used is the ASM Metals Handbook, Volume 8,
8th edition, titled Metallography, Structures, and Phase Diagrams.
Look on page 330. The binary phase diagram for tin/lead shows the
eutectic at 61.9% Sn. This diagram is credited to M. Hansen
"Constitution of Binary Alloys", 2nd edition. I know that within the
last year ASM has put out a much heralded revision to Pearson's phase
diagram compilation that corrected many of the binary phase diagrams
but I don't think that they found any errors in the Sn/Pb diagram. Hey
TechNet - anyone else know of a different published eutectic point?
Dave Hillman
Rockwell Collins
[log in to unmask]
______________________________ Reply Separator _________________________________
Subject: Re: Sub: Solder Paste Plastic or Eutectic
Author: [log in to unmask] (Jerry Cupples) at ccmgw1
Date: 11/23/96 2:25 PM
Dave, you said:
> The true
> eutectic for tin/lead is 61.9%tin/38.1%lead (183C)- everyone calls
> 63/37 or 60/40 eutectic but they are really near eutectic alloys.
Hmmm. I have seen dozens of references which show 63.0%/37.0% to be the
eutectic composition for tin-lead binary alloys, and this is the first time
I've seen otherwise.
Anybode got a new edition of Hansen? I'd like to see confirmation,
otherwise I'll keep my solder post as close as possible to 63% tin. We'd
all be able to save some money if you are!
regards,
Jerry Cupples
Interphase Corporation
Dallas, TX USA
http://www.iphase.com
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