Hi Werner, IPC LF Listservers,

<Hi Dave,
In electronic packaging, approaches like MIL-HDBK-217 do not work,
since they do not take into account the real physics-of-failure
determined by the underlying damage mechanism(s) and material behaviors.
In particular with the higher temperatures required for LF-soldering
material degradation for PWBs and componennts is a real problem.
Only a real understanding of the underlying technical issues can help.
Werner Engelmaier>

Thanks Werner,

Ignoring HDBK-217, which I really wasn't focussed on, I think we agree.

Writing my response another way. In going to higher temperatures most
companies will first look for physical (mechanical) failures. This can come
from process observations like wetting and land component coverage or even
metalurgical, or physical disturbances in materials. Another step is DC
(electrical) effects and obvious AC performance failures. The next step
should be reliability testing which causes certain physical failures, and
certain electrical failures, as one hopes to understand long term
reliability. The last step discovered is often high frequency (electrical)
failures as the materials change with age.

Yours in Engineering, Dave
YiEngr, MA/NY DDave

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