Reliability assessment of PBGA solder joints using the new creep constitutive relationship and modified energy-based life prediction model

In this study, a new creep constitutive relationship and a modified energy-based fatigue model are proposed. Compared to the commonly used hyperbolic-sine and two-regime power law relationships, the new relationship was found to be capable of covering the whole temperature range and stress regime. The modified energy-based fatigue model represents the cycling temperature and frequency effects well, which is not the case in the widely used strain-based Coffin-Manson and energy-based Morrow fatigue life prediction models. Furthermore, the relationship and model are applied to investigate the thermal fatigue reliability of a 256 I/O plastic ball grid array (PBGA) assembly. The simulation result is found to be in agreement with that obtained from accelerated thermal cycling (ATC) test. It is concluded that the new constitutive equation and the life prediction model can be used confidently for the assessment of long-term reliability of solder joints