Hi Steve,
In a message dated 02/21/2002 9:30:10, [log in to unmask] writes:
>Beginning with the Coffin-Manson Law and the Engelmaier (Sir Werner's)
equation, it was
>determined that solder joint volume needed to be increased and the
>"acceptable geometry" needed to be modified, almost to point of "the bigger
>the blob the better the job".
Well, neither Coffin-Manson Law and the Engelmaier (Sir Werner's) equation
would suggest more solder joint volume, only taller solder joints.

>The idea is to increase the solder joint volume up the castellation and
outward to the pad
>creating a "bulbous" fillet -- this portion of the joint contributes to 85%
of the solder joint life with >respect to crack formation and propogation.
This "bulbous" SJ idea did not work very well, as the results provided by
Martin-Marietta during the Industry Days of this Air force clearly showed. In
order to bring any improvement at all, it was necessary that all four sides
of the  LLCCCs had identical SJs in terms of their geometry--something that
proved hard to do.

Werner Engelmaier

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