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Hi folks,
with this issue we have a fling or a big issue. This is what I knew up to now, supported by other papers. Thank You very much.
On the other hand there is existing a paper which tells exactly the opposite:
"Vibration Testing and Analysis of Ball grid Array Package Solder Joints" from Shaw Fong Wong e.a. Intel Technology 1-4244-0984-5/07/ 2007 IEEE
It says in the conclusion:
The comparison of SnAgCu and SnPb fatigue curves clearly indicated the better performance of SAC solder system under high cycle fatigue test.
I had not the time up to now to compare all boundary conditions, but in the paper of INTEL are Weibull curves drawn, which show that for cycles > 10**5 SAC survives SnPb. Vibration tests from about one hour ore more have more than 10**5 cycles..
This paper is already quoted in other papers and You can imagine that there is temporary a big uncertainity in the lead free society.
I would be happy if we can discuss about the big differences in the boundary conditions of these two worlds.
I started already comparing them, but I am interested in Your opinions. Is it the different annealing history or what?
Sincerely
Michael Jeremias
Industrial Engineering (OPPI41)
Electronics Production
((( Defence Electronics
EADS Deutschland GmbH
89077 Ulm
Tel.: +49 (0) 7 31.3 92-5533
Fax: +49 (0) 7 31.3 92-73 15
E-Fax: +49 (0) 7 31.3 92-20 5533
P Before printing, think about the environment !
-----Ursprüngliche Nachricht-----
Von: TechNet [mailto:[log in to unmask]] Im Auftrag von Joe Fjelstad
Gesendet: Montag, 8. Dezember 2008 21:45
An: [log in to unmask]
Betreff: [TN] 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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