Hi Phil,
That German study was indeed on chip components.
I have not seen, or even heard of, this AMP study, so you have me at a
disadvantage.
Butt-joints are a real problem in any case, that is why they have all but
disappeared. But there is no reason why an off-center (within reason, of
course) gull-wing solder joints should be any less reliable, at least for
thermal cycling. Now, there have been studies, where strenght has been equated
with reliability—off-center solder joints are likely somewhat less strong than
perfectly cetered ones, but any properly wetted solder joint has more than
ample strenght to survive all but deliberate shear- or pull-off tests. But
solder joint strength can not be equated with reliability for thermal cyclic
fatigue.
If you have a copy of this AMP report I would like one, otherwise, p[erhaps
you recall the definition of reliability in this study.

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask]


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