Mean-time-to-crack model of microbump interconnect in FCGBA package under thermal cyclic test

By employing the physical characteristics of creep deformation mechanisms for solder joints in a flip-chip ball grid array (FCBGA) package under a thermal cyclic condition, an analytical model for the prediction of mean-time-to-crack (MTTC) is presented in the paper. With the consideration of time-dependent thermal testing functionals, the basic co-analyses of one-cycle Nabarro-Herring and Coble creep rates and the corresponding damage accumulation functionals for the conventional eutectic Sn/Pb micro-solder material are studied using the proposed MTTC model theoretically. For experimentally validation of the MTTC model, a batch of devices filled with resin in FCGBA package had been tested under a -40°C∼125°C thermal cyclic test with a period of 1-hour 1000 times. The MTTC model reveals that the solder bumps within the FCGBA can survive about 0.53 year under the cyclic testing circumstance. Under the room temperature, the device even can survive about 2.45 years under continuously operations.