Hi Mike,
You are absolutely correct: "3.0 +/- 0.3 sec minimum" is nonsensical.
In order to resolve all your questions, one needs to consider the purpose of
the test. Simply stated, it is to subject the coupon to a temperature
increase to the same temperature as the solder pot. Heat transfer takes time,
thus the 3 second minimum immersion time. Because the solder pot temperature
near the surface may be somewhat lower than the set pot temperature, a
minimum immersion of 1 inch below the surface is called for. And of course,
the coupon needs to be immersed totally. the 3 seconds are the immersion
dwell time, thus the timer should start upon complete immersion, and should
stop when the top edge emerges from the solder. You need to consider that
after thermal equilibrium is reached, nofurther damage--in the shot
term--occurs.

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], Website: www.engelmaier.com

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