Stress screening of electronic modules: investigation of effects of temperature rate of change

The authors discuss a study conducted to investigate the effects of temperature rate of change on the environmental stress screening of printed wiring assemblies (PWAs). The related effects of chamber air velocity and temperature dwell time on module temperature response were evaluated. The effects of varying thermal cycling parameter levels were investigated. The effects of various chamber air temperature rates of change and velocity levels on the temperature responses of two vastly different PWAs were measured. A thermal-cycling analysis of a PWA of the same construction as one of the two PWAs tested in the investigation was also performed. The results of a portion of the test are compared with the analytical predictions, validating the thermal response trends predicted by the mathematical model.<>