Thermal resulted fatigue life analysis of ceramic ball grid array package

A full three-dimensional (3-D) finite element analysis is not possible anymore. In order to deal with the problem, a modified global/local finite element model was established. A finite element software named MARC was used to analyze the thermal strain/stress and accumulated plastic energy of the complex solders in FF1152 (1152-Ball Flip-Chip Fine-Pitch BCA). Thus, the location of the most critical solder was identified. Then under the accelerated fatigue condition of 0°C to 100°C, a plastic energy accumulate based fatigue life prediction model was used to predict the most critical solder's thermal fatigue life. And the result is quite approximate to the foreign data. The optimizing function of Nastran software and manual draft join was used to confirm equivalent parameter of equivalent solder. The results which compare with real solder indicate that the error of equivalent result is 3.01%. Therefore, the validity and correctness of the modified model is demonstrated, and the modified model can be used to analyze different types of SMT encapsulation.