Another term that may better suit is wetting. It requires that
the one metal melts and  wets the other metal. It does not require that
the two metals melt and alloy. Another factor that it is needed to be
considered is the components. What is the maximum temp that they can
withstand?
        Ramon 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Thursday, October 26, 2006 8:10 AM
To: [log in to unmask]
Subject: Re: [TN] Backward Compatibility of Tin Electroplating

Hi Rich! Unless the electroplated tin has some unique surface finish
characteristics, it is not necessary to exceed 232C (the melting point
of
tin) in the reflow process. Some folks don't realize that the majority
of solder connections are the result of molten solder alloys diffusing
into component or pwb surface finishes rather than both surfaces being
molten.
An example I like to use is that if we needed to "melt" a gold surface
finish (which some component fabricators use as their solderable finish)
then we would need to achieve a reflow profile exceeding 1064C which
would be a bit of an issue for the rest of the assembly! Could the
vendor be suggesting that 232C needs to be exceeded for some other
reason than creating the solder joint?

Dave Hillman
Rockwell Collins
[log in to unmask]




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Subject
                                       [TN] Backward Compatibility of
Tin
             10/26/2006 12:17          Electroplating
             AM


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                  Richard
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Does anyone have any reason to suspect that tin electroplated SM
components being soldered with a 63/37 solder paste require a profile
that must exceed the reflow temperature of tin?

Being told by a component vendor this is the case.  I would totally
discount this but seem to recall reading this more than once on some
other component Tech data sheets. I can't explain why this would be
necessary, but.....

Any thoughts would be appreciated.

Rich K / Kimball


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