Jim,

If the solder significantly stiffens the leads then it will also increase the
resonant frequency and reduce the magnitude of vibration for a given level of
excitation, so whether the higher stress concentration is significant is not
immediately obvious. Can't you just re-run the FEA with the new geometry?

David Whalley



>The fact of the matter is that the components are ceramic QFPs on polyimide.  
>Our concern isn't with thermal excursions, though, since we restrain our 
>assemblies and control the surface TCE to ~7 ppm/degrees C.  Our FEA revealed 
>high stress concentrations during vibration where the lead is attached to the 
>component.  The concern is that solder in the bend will shorten the lead
length 
>from the component body to the first bend, thus increasing the stress during 
>vibration.

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