Vibration fatigue analysis for FCOB solder joints

Vibration fatigue tests and analysis for flip chip solder joint reliability assessments were investigated. Dynamic characterizations of flip chip on board (FCOB) assemblies were evaluated using accelerometer and high-speed camera measurements during vibration tests. Out-of-plane vibration fatigue tests were investigated for constant G-level tests at 3 G, 5 G and 10 G respectively. A varying G-level vibration test with 3 G, 5 G and 10 G blocks arranged in ascending sequence was conducted for cumulative fatigue damage assessment study. The test results for outer chains on the large chips satisfy the two-parameter Weibull distribution well. FEA using a global-local submodeling method was used to compute the fundamental frequency result, compared to experimental data. A quasi-static analysis method was developed to model the effect of flip chip location on solder joint fatigue life. The linear cumulative damage analysis method (Miner's rule) predicted nonconservative results for vibration fatigue failures in the flip chip solder joints. Transient vibration behavior after drop test was also studied to predict the fatigue life of the FCOB assembly subjected to drop loading.