Fatigue life prediction for flip chip soldered joints based on creep stain model

Finite element method was used to simulate the inelastic stress in soldered joints of flip chip, and the results indicated that the maximums of equivalent creep strain and equivalent plastic strain in soldered joint both located at the upper surface of limbic chip.Processing the stress and strain of soldered joints with time, it was indicated that soldered joints had significantly relaxed the stress in the initial stage of circulation, with the accumulated trends of plastic strain and creep strain.With the hysteresis loop of stressstrain, cyclical variation of the loop was observed, and the curve became stable with the cyclic loading of heat.On account of the interaction between plastic strain and creep strain, the solomon model and shine and fox model were utilized to calculate fatigue life of the soldered joints.The simulated results were almost the same with the the practical life.