Sometimes this is a function of post-soldering cooling rate. Is the mass of
the connector much greater than the other components, so it holds the heat
longer and cools slower?
What happens if you blow cool air on the joints right after soldering to
accelerate the cool-down rate?
The genesis of this comes from Rockwell's Mather & Hagge work on vps, which
showed the slower cooling with early versions of this process gave rise to
larger solder grain structures, which looked gray- giving rise to worries over
'cold solder joints'.

Bill Kenyon
Global Centre Consulting
3336 Birmingham Drive
Fort Collins, CO   80526
Tel: 970.207.9586   New Cell: 970.980.6373

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