Defining environmental loading is usually the most uncertain part of
the electronics reliability calculation. This paper demonstrates a practical
methodology to measure and characterize the dynamic thermal history of
the commercial airplane environment. To reduce irregular field thermal
cycles, an algorithm is presented that preserves key information necessary
for viscoplastic solder fatigue analysis. As an example application, the
IPC solder model will be used to evaluate 20 termination leadless ceramic
chip carrier on non-constrained printed wiring boards. This methodology
will enable more realistic thermal fatigue reliability assessments and
acceleration test specifications.
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