Hi Sheila,
You did not say what kind of temperature cycling nor for how many cycles this
"temperature cycling after solder rework" would involve. But from a purely
technical point of view, temperature cycling of product to be shipped to the
customer is silly. It is not a very effective ESS techique for full
assemblies, because if it were carried out to be effective it would do more
damage to good solder joints than finding bad ones. Any temperature cycling of
full assemblies will accumulate some fatigue damage and therefore reduce the
life.  Whether this is significant or not will depend on the severity and
number of temperature cycles as well as the design parameters of the assembly.
To find bad—improperly wetted, other so-called defects rarely make a
difference—solder joints one would be well advised to use vibration,
preferably at -40 degrees C. Good solder joints are not damaged, bad ones fall
apart.

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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