Hi Michael,
You have received pretty good advice from Dave, Bill, Paul, and Andy, but the
answer bill got from the 'head of all soldering operations at Siemens' is
essentially non-information, if not dis-information. The properties change
with composition, of course, but not wildly, and as far as fatigue reliability
is concerned by about a factor of 2 to 3, which is small potatoes compared to
the impact of other parameters determining the lives of solder joints.
From your original question as well as your 2nd message, it is not clear why
you want or need a high-temp solder. From your description of the clip-leads
with solder preforms I am guessing that we are talking about NAS clip-leads
and that you are using some ceramic components on FR-4 or polyimide.
Depending on component size and severity of use conditions (as well as the
compliancy of the lead geometry), your primary concern should most likely be
the reliability of the solder joints.
I have extensive experience with clip-leads and published the results of an
exhaustive reliability study (Engelmaier, W., and A. I. Attarwala, "Surface-
Mount Attachment Reliability of Clip-Leaded Ceramic Chip Carriers on FR-4
Circuit Boards," IEEE Trans. Components, Hybrids, and Manufacturing
Technology, Vol. CHMT-12, No. 2, June 1989, p. 284), and there certainly is no
problem with near eutectic Sn-Pb solder.
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask]
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