Prognostication of Accrued Damage and Impending Failure Under Temperature-Vibration in Leadfree Electronics

Electronics in defense applications may be exposed to sustained period of high temperature vibration. A number of mission critical applications are enabled through electronics control systems including navigation, guidance and control. Prognostication methods for assessment of accrued damage and identification of impending failure are needed under combined temperature vibration environments. In this paper, two-formats of leadfree board assemblies have been used to study the effect of prognostication sensor-location and use-conditions on the detectability of accrued damage and identification of impending failure. Transient strain deformation histories have been acquired using strain gauges fixed on the backside of the PCB, in the footprint of the front-side part. Feature vectors have been identified and their evolution studied in the pre-failure space. Effect of sensor location on the fidelity of early-identification of damage onset has been quantified. The feature-vectors were analyzed using a combination of statistical and frequency-based techniques. The frequency content of the strain signal is analyzed and patterns corresponding to before and after failure of electronic components at different conditions of vibration loads. A comparison of different feature vectors and change in the behavior of feature vectors with damage evolution under temperature and vibration has been quantified.