Evaluation of Fatigue Behavior of Lead-Free Solder Joints in Four-Point Bending Test by Finite-Element Modeling

Fatigue performance of solder joints in four-point bending test is evaluated by finite-element modeling. A simplified modeling technique is implemented in order to focus on the behavior of the critical solder joint. The fatigue life is estimated by taking into account the creep behavior of the solder joints and the utilization of Morrow's fatigue model. Fatigue life curves are generated for room temperature and two elevated temperatures with the critical orientation of chip scale packages on the test board. The results are compared with the real four-point bending test conducted for two different temperatures. In addition, some parametric studies are conducted including the significance of test temperature, copper wiring structure, and the dwell time in the cyclic loading profile. Besides these, the structural integrity of the test board is also checked.