Hi Gerald - there are a couple of good papers in the published literature 
that you can use to demonstrate that you situation is not a solder joint 
integrity concern. I am just getting back from vacation so give me a 
couple of days to dig out and I'll send you  the references.

Dave Hillman
Rockwell Collins
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From:   Gerald Bogert <[log in to unmask]>
To:     <[log in to unmask]>
Date:   06/06/2013 03:20 PM
Subject:        [TN] Soldering to SMD device wth Sn98Bi2.5 leads using 
Sn63Pb37 solder
Sent by:        TechNet <[log in to unmask]>



June 6, 2013

 

We have an OM who soldered surface mount Opto-couplers with Sn98/Bi2.5
leads using Sn63Pb37 solder.  The reflow solder profile used was the
traditional one for Sn63 solder with a measured peak temperature in the
range of 209 to 215C.  The actual amount of Bi by weight that wound up
in the completed solder joint was calculated to be about 0.19%.  Based
on this, there is no issue with a low temperature alloy forming with the
combination of Bi and Pb. 

 

However, since the melting point of the Sn98/Bi2.5 solder is around
223-231C, the reflow profile used will not result in melting of the
solder on the part terminations.  Is this an issue or will the Sn63
properly bond to the solder on the part terminations to form an
acceptable solder joint?

 

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