Plastic and hermetic integrated circuits (IC’s), 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 IC’s, 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 IC’s, 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 IC’s.
 

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