Greetings  folks 
Found this  on the wires today... (Cut it earlier out but lost the link but I 
am  sure I am not the only one who read it. However I can go dig it up if  
there is interest)   
Why are we  still using lead-free solder again? So it goes.... 
Joe 
"Davide de  Maio of National Physical Laboratory discussed the high frequency 
vibration  testing of tin-lead and lead-free solder joints, with reference to 
automotive  and aerospace electronics--a grim reminder that 80% of failures 
in airborne  electronics were attributable to vibration and shock. A test piece 
had been  designed representing a single solder joint between two copper 
components, which  was tested to failure at frequencies of 400Hz and 800Hz. A 
range of SAC  lead-free solders had been evaluated, with tin-lead as a comparison. 
The  tin-lead solder outperformed the lead-free examples, especially at the 
higher  frequency. In general, failure occurred at or near the intermetallic 
interface,  which would be expected to be the most stressed area. Of the SAC 
alloys,  performance at 400Hz was better the higher the silver content. Annealing 
of SAC  had a deleterious effect on performance at both 400Hz and 800Hz."
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