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Is there any data to show that 0402s are relatively flex crack resistant due to their size?

I can find lots of references about 0805 and larger capacitors cracking due to board flex, but I can't find any test results for 0402 caps.

Is this perhaps just because they are so small that it is fairly difficult to get enough board deflection to crack them?

crj11
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I found a very thorough PhD thesis that measured flex cracking on MLCCs, and 0402s are MUCH less likely to crack than larger parts.

The test was performed by dropping a circular test board such that it was subjected to 5000g for 0.3ms. It turns out that "fast" strains induce cracking at lower strains than "slow" strains created by bending a board by slowly pressing on it, so this is a worst-case analysis for many board flex environments.

See EVALUATING THE SUSCEPTIBILITY OF ELECTRONIC COMPONENTS ASSEMBLED WITH LEADED SOLDER TO FLEXURAL FAILURES, WITH HIGH RATE CONSIDERATIONS by James Robert Watkins here.

The plot below shows that 0402 failure rate was significantly lower than larger parts. See the paper for a description of the test setup. enter image description here

crj11
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  • Still comparable to `0603`, which is 0% for all. (I assume this is a sampling size issue). Including `0805` would make this more compelling - based on this limited data it could well be a "cliff edge" characteristic where if component is larger than size `X` it may fail, but not otherwise. – awjlogan May 13 '21 at 14:38
  • I think the 0603 may have been assisted by the particular component, since it doesn't make sense that 0603s were better than 0402s. – crj11 May 13 '21 at 17:28