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Date: | Mon, 11 Nov 1996 09:33:08 -0500 |
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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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