Comparison of Plastic and Hermetic Micro-Circuits Under Temperature Cycling and Temperature Humidity Bias
L. Condra, S. O'Read, T. Freedman, L. Flancia, M. Pecht, and D. Barker
Plastic and hermetic integrated circuits (ICís), as discrete packages
and as assembled on circuit card assemblies, were temperature cycled between
?5 and +85ºC through 1000 cycles, and 26 parametric values were observed
in terms of failure rates or shifts. The circuit card assemblies
were then tested for up to 650 h in 85ºC-85% relative humidity (RH).
Circuit cards were also assembled using both plastic and hermetic versions
of a custom IC, for comparison against each other as well as against an
older discrete version of the card, which had a history of reliable operation
for over 20 years. The IC version of the cards were coated with either
urethane or parylene, and along with unassembled ICís, were tested for
1000 h in 85ºC-85% RH with intermittent bias temperature, humidity,
bias (THB). Conservative lifetime estimates, for both the plastic
and the ceramic ICís, for avionics applications, were determined to be
well over 20 years. It is concluded that, in this and similar applications,
there is no reliability advantage between plastic and ceramic ICís.
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