Hi Chris, AIM-DavidS, Robin, , , IPC LF Listservers,

<This issue is currently being studied by the NPL to determine the
effects of "mixed" process soldering in respect of manufacturing during
the transition stage as Pb-F soldering comes in.>

NPL is studying this again, and I am not that confident in the results they
will achieve this time since they plan to terminate their study at "a
number of hours" rather than a failure percentage. Also I don't seem to
remember that they are varying dwell times, delta T, and other factors.
Otherwise, if memory serves me, it seemed like they are following the same
protocall that Werner and the IPC group has established which is good (e.g.
in situ electrical testing, other)

NPL has already written a recent report (on that CD from Global SMT) that
indicated that mixing solders was better than any pure solder. This is
counter intuitive, unless NPL's test only stresses that particular type of
failure. Read a note stream from back in December by our reliability list
participants.


Yours in Engineering, Dave
Y i Engr, MA/NY DDave

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