Simulation and Fatigue Damage Prediction for Board Level CBGA Solder Joint of LTCC-based SiP Module under Random Vibration Loading

Aerospace/airborne military SiP modules have strong demand in high performance, multi-layer flexibility, embedded passive integration and airtightness requirement. Based on this, high-density integrated LTCC (Low Temperature Co-fired Ceramic) based SiP modules with ball grid array (BGA) I/Os show obvious superiority upon other packaging, often being soldered onto Digital/RF printed circuit board (PCB). However, board level ceramic BGA solder joints suffer sustaining random vibration mechanical stress under complicated conditions, for which the interconnection reliability need to be evaluated in advance. In this paper, 3D finite element analysis (FEA) models were developed using ANSYS workbench to understand the vibration-mechanical behavior of CBGA under random vibration test. Related materials properties were accurately obtained by DMA analysis. Simulated load boundaries are consistent with random vibration test bench. The natural frequencies of board level CBGA solder joint LTCC-based SiP specimen were obtained from modal analysis to confirm the vibration mode, based on which the subsequent random vibration simulations were conducted to mapping the equivalent stress/strain distribution of BGAs at interconnect solder joints in X/Y/Z directions. For fatigue prediction, the "three-zone technology" suggested by Steinberg, which taken into consideration both Gaussian distribution and Miner's linear damage theory together, was used to predict fatigue life of CBGA solder joint under random vibration conditions.