| Summary: | 博士 === 國立成功大學 === 工程科學系碩博士班 === 94 === The flip chip chip scale package (FCCSP) is different from conventional wire-bonding package by flipping the silicon chip over and connecting the solder bumps to the substrate directly. Because the flip chip package has excellent electrical properties, high I/O density, and yield-increase of each wafer by reducing the size of IC, therefore, it is more suitable to those advanced electronic products demanding high speed, large electric current, high-pin-count than other traditional packages. This paper focuses on the fatigue life of the solder joint in FCCSP under thermal cycling loads, and the finite element analysis software is applied to simulate the deformation of solder balls.
First, Surface Evolver is applied to predict the shape of solder joints after reflow, then the results are brought into ANSYS as the shape factors to simulate the fatigue life of the solder joint in the FCCSP. This research focused on the FCCSP with eutectic lead-free 96.5Sn3.5Ag solder joints on FR-4 PCB, and adopted Garofalo-Arrhenius creep model along with finite element software, ANSYS 7.0, to investigate the outer solder fatigue lives of five FCCSP models in three-dimension under thermal cycling of -20℃~110℃. These five models are the original model, the model with BT-resin substrate, the model with high-α ceramics substrate, the model with BT-Resin substrate, the model with Mold-resin encapsulant, the model with Potting-resin encapsulant.
Finally, Taguchi method is used to study the effect of designing parameters, such as substrate thickness, solder pad radius, Young’s modulus of underfill, linear coefficient of expansion of underfill, Young’s modulus of FR4, linear coefficient of expansion of FR4, on the fatigue life of the solder joint. Consequently, the optimal combination of factor-level is attained, and hopefully to improve the fatigue life of solder joints in the packaging.
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