| Flip-chip package is one of the most advanced packaging techniquesproviding high I/O density and excellent performance. Solder joints isimportant component in Flip-chip package, they can provide mechanicaland electrical connections between silicon chip and substrate. Thereliability problems of microelectronic packags are largely caused by thefatigue failure of solder bumps under thermal loads. Analysis the failurelife of solder bumps has significant meaning in the reliability of flip-chippackages.In this study, thin and fine-pitch Ball Grid Array Packages--TF-BGAis simulated by FEM software to predict the thermal fatigue life of solderball under thermal cycling loading. The convergence of solder meshmodel is considered to assure the accuracy of the simulation. The materialmodel of solder is set to be viscoplastic. The equation to predict thefatigue life of solder is based on inelastic strain energy density. 3D slicemodel, 1/4 model and 2D symmetric model are used in this study. Theslice model of FEM is compared with the symmetric model to discuss thefeasibility of using the slice model to predict the inelastic behavior ofsolder. The effect of geometric dimensions of substrate and PCB boardand the different loading temperature range on the fatigue life of solderare also discussed. The fatigue life of lead free material is predicted at thesame time because of the forbid of the Pb material.
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