Hi Phil,
If you are getting warping, those parts will crack occasionally.  Can you
add a mechanical stiffener after SMT and wave to help prevent the bowing
of the board?   Also, if the parts are resistors, can you respin the board
and put less vaues in series?



Kerry McMullen
Principal New Product Mfg. Engineer
LTX Corporation
50 Rosemont Road
Westwood, MA 02090-2306
(T) 781-467-5468



Phil Nutting <[log in to unmask]>
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01/31/2006 11:31 AM
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[TN] Large SMT physical failure prevention






Good morning,

We have some designs that are calling for large, 1825 and 2225
components.  We have seen some mechanical failures where the parts have
cracked.  If we need to use these monster components, how do we ensure
we reduce or eliminate the mechanical failures.

Our failures were seen on a 16 inch by 17 inch 0.062 thick board.  On
these we have changed our handling methods.

On smaller 2 inch by 2 inch boards is this a don't care?  I know that
rapid temperature ramp up or down in the reflow process could be a
killer.  Something to work out with our CM.

Phil

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