This just came in my email from SMT Net.  I have not been able to link to the 

article yet but the title and first  paragraph sounds familiar. 

Joe  

_Fragility of Pb-free Solder Joints_ 

(http://www.smtnet.com/adsystem/redir.cfm?adid=831)  

_Universal Instruments_ 

(http://www.smtnet.com/company/index.cfm?fuseaction=view_company&company_id=46383)  

Credit/Source: Peter Borgesen, Surface Mount Laboratory, Universal  

Instruments; and Donald W. Henderson, IBM Corporation  

Recent investigations have revealed that Pb-free  solder joints may be 

fragile, prone to premature interfacial failure  particularly under shock loading, 

as initially formed or tend to become so under  moderate thermal aging. 

Depending on the solder pad surface finish, different  mechanisms are clearly 

involved, but none of the commonly used surface finishes  appear to be consistently 

immune to embrittlement processes. This is of obvious  concern for products 

facing relatively high operating temperatures for  protracted times and/or 

mechanical shock or strong vibrations in  service...







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