Steve 

Very interesting what you wrote. Two things I want to add: 
- We do need creep. Without creep no differences in CTE could be accommodated thus considerable stress would build up in the components. Especially ceramic capacitors wouldn't like that too much. 
- The other is, that each deformation mechanism has its own degradation mechanism. This means 1000 cycles of grain boundary sliding ( GBS) do another harm to the solder than 1000 cycles of dislocation climb (DC). GBS is less severe than (DC). Thus I believe that blocking GBS is not the best idea to enhance the reliability of SMT assemblies.

Have a nice day

Guenter

Guenter Grossmann
Swiss Federal Institute for Materials Testing and Research EMPA
Centre for Reliability
8600 Duebendorf
Switzerland

Phone: xx41 1 823 4279
Fax :      xx41 1823 4054
mail:     [log in to unmask]

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