Hi IPC LF Listservers,

I just came across this article and it might be interesting to those of us
that can access it via an SMTA subscription. If you can, use Olli Salmela
as your search term.

Hey every bit helps in knowledge.

------------Abstract from the smta.org site-------
RELIABILITY ANALYSIS OF SOME CERAMIC LEAD-FREE SOLDER ATTACHMENTS
Author :    Olli Salmela et al.

Abstract : In this paper, an approach to interpret lead-free solder thermal
cycling test results is discussed. First, the experiments are described.
Second, failure analysis and statistical analysis are performed. The actual
lifetime prediction is based on both utilization of analytical models and
finite element (FE) simulations. Special attention is paid to re-
calibration of the models in order to reflect the change of solder
material.

As an end result, two new methods to enhance the lifetime prediction
accuracy of Engelmaier's model are suggested. Based on the data from the
literature, the prediction accuracy enhancement scheme is widened to cover
also plastic packages in case of both SnPb and lead-free assemblies.
------------Abstract from the smta.org site-------

This report with it's mathematics comes down to a failure mechanism in the
solder and a better performance for SAC in low stress/strain situations.
This is some of what Jean-Paul told us about awhile ago as a Christmas
present. In comparison another report I read recently from the uic site,
which NIST/iNEMI Carol referenced shows failures at the interfaces. As far
as I know it is still too early to have Pin-in-Hole with fillet lifting
effects being analyzed.

Yet every bit helps, and this article seems helpful.


Yours in Engineering, Dave
YiEngr, MA/NY DDave

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