I would also suggest that anyone interested in vibration testing of
Pb-free solders go to
http://acqp2.nasa.gov/projects/LeadFreeSolderTestingForHighReliability_P
roj1.html. See Section 4.1 and Section 10.


-----Original Message-----
From: Joe Fjelstad [mailto:[log in to unmask]] 
Sent: Monday, December 08, 2008 12:45 PM
To: [log in to unmask]
Subject: [LF] vibration testing of tin-lead and lead-free solder joints


 
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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