| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 106 === This thesis uses finite element analysis software ANSYS17.0 Workbench to simulate the thermal strain behavior of the flip-chip fine-pitch ball grid array(FCFBGA) package structure with copper pillar bumps, and is studied the fatigue life of the bump solder (Sn3.5Ag) in the accelerated temperature cycle.
In the simulation, first ANSYS Workbench is used to set up the model and then set the parameters of each component's material. The solder bump and the bottom solder ball are nonlinear viscoplastic materials, while their viscoplastic behavior is described by Anand’s model. The mold compound and underfill are viscoelastic materials, and their viscoelastic behavior is described by Maxell model. Other materials are considered elastic materials to improve the efficiency of the solution. Then meshes it, sets the boundary conditions, and exerts a temperature cycle load to the body. Finally, observe the strain distribution of the structural body and substitute the results of the equivalent plastic strain change of the solder bump during temperature cycling into the Coffin Manson formula to investigate the reliability of the solder bump.
In the results and discussion, the effect on the fatigue life was observed by changing the dimensions of the different components and the CTE of the material. Finally, the variation in the size of bump's pitch and the CTE of underfill has a significant effect on the solder bump fatigue life.
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