Plastic Ball Grid Array Solder Joint Reliability Assessment under Combined Thermal Cycling and Vibration Loading Conditions
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Concurrent vibration and thermal environment is commonly encountered in the service life of electronic equipment, including those used in automotive, avionic, and military products. Though extensive research exists in literature for solder joint failures due to thermal cycling, limited research has been conducted on investigating solder joint failures due to a combination of vibration and thermal cycling. In this study, experiments were conducted on PBGA assemblies under thermal cycling, vibration loading, and combined thermal cycling and vibration loading conditions. The results showed much earlier PBGA solder joint failure under combined loading compared with either thermal cycling or vibration loading alone. It was found that traditional linear superposition can overpredict the solder joint fatigue life since it neglects the interaction of the vibration and thermal cyclic loadings. An incremental damage superposition approach using finite element analysis was applied to PBGA solder joint reliability assessment. This approach can model the nonlinear interactions between vibration loading and thermal cycling. It considers the temperature effect on vibration response and the effect caused by thermomechanical mean stress affects. This approach was validated through experiments and reflects the actual damage trends. Based on the incremental damage superposition approach, a rapid solder joint fatigue life prediction simulation approach for PBGA was also developed for combined temperature cycling and vibration loading conditions. This approach included a thermomechanical stress model and a vibration stress model to analyze the interconnect stress under thermal cycling and vibration loading conditions. The mean stress during thermal cycling was obtained from the response curve. The damage due to two different loadings was then calculated using the generalized strain approach and superposed. This approach was also validated using experimental data. This work has also resulted in a rapid virtual qualification algorithm to predict solder joint reliability under combined temperature and vibration loading conditions. The importance of physics of failure principles in modeling and designing experiments were also explored and addressed. Industry should benefit from this study on reliability prediction, qualification, and accelerated testing design.