Werner's point on the cooling rate is a good one. When folks were using vapor
phase soldering, the very slow cooling gave rise to large grain structure,
which looked like the classic 'cold solder joints'. Accelerating the cooling
rate yielded small solder grain structure, which gave the desired shiny joints.
Thus, was wondering if monitoring the grain structure vs cooling rate could
be used to optimize the cooling profile for high value assemblies. Then a
suitable process control document could be prepared to guide the assembly team and
quality group. Has anyone tried this already and could share results?

[This grain structure work was reported at China Lake in the days of the
pre-NEPCON February Soldering Seminars by Rockwell. Those with near-complete sets
of Proceedings can no doubt locate the paper.]

Bill Kenyon
Global Centre Consulting

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