Hello again Werner,
You raise a good point, I have seen acceleration factors being used and
abused, like applying a high-Pb acceleration factor to standard SnPb, even SAC
assemblies!

Several companies are doing comparisons of SAC models but I can't  comment on
specifics, maybe they will.  In my own development, I have  compared several
SAC models to acceleration factors from SAC thermal cycling  experiments.
Some agree, others don't, by as much as half an order of  magnitude. Situation
was similar for SnPb. As always, no model should be used  blindly without an
evaluation of whether it applies to the situation at  hand.
Acceleration factor models all have their boundaries (i.e. they  only apply
for conditions covered by empirical correlations) and should be  tested for the
type of assembly and conditions being considered.

For example, for strain energy based approaches, the models apply over the
range of strain energy covered by the empirical correlations.  Beyond that
it's an extrapolation.  Which is why it's important to look at the size of  the
database that was used and the range of conditions that was covered.   Strain
energy models simplify that task since we just have to look at the range  of
strain energies on which the empirical correlations are based.

With best regards,
Jean-Paul


In a message dated 10/13/2005 4:29:25 PM Eastern Standard Time,
[log in to unmask] writes:

That of  course opens the question, what is the difference between them, and
how  well do the answer obtained agree?







Quote of the month:
"It is the weight, not numbers  of experiments that is to be regarded", Isaac
 Newton.
_______________________________________________
Jean-Paul  Clech

EPSI Inc., P.O. Box 1522, Montclair, NJ 07042, USA
tel.:+1  (973)746-3796, fax: +1 (973)655-0815

_http://www.jpclech.com_ (http://www.jpclech.com/)

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