| Summary: | 博士 === 國立中正大學 === 機械工程所 === 97 === The solder joints play a crucial role in providing electrical and thermal connectivity throughout an electronic packaging. Thus, the reliability of the solder joints directly impacts on the performance of the electronic packaging. Therefore, evaluating the mechanical strength of solder joints is critical importance to improving the reliability and service life of portable consumer electronic products. The mechanical behaviors of solder joints are generally characterized using the drop test. This method provides reliable and accurate results; however, it is conducted under the board level rather than the chip level. Besides, the experimental works with high cost are suffered. Therefore, an efficient and effective technique for evaluating the capacity of solder joints at the chip level to withstand high-speed impacts is required. In this study, novel experimental process and numerical analysis techniques for evaluating high-speed-impact strength and energy absorbance capability of the lead-free solder under the chip level are presented. After impact testing, the fracture surface and the failure modes of the samples will be carefully examined. This failure-mode analysis can help to understand the solder joint strength effect on various solder material under high strain rate. From the results, we can found that the percentage of interfacial fracture is increasing with impact speed. Therefore, to understand the interfacial strength is necessary for solder joint reliability. A two-step approach using the three-dimensional nonlinear dynamic finite element model has been successfully developed to simulate the mechanical behaviors of the lead-free solder joint under the high speed shear loading. The results show the good agreement between the experimental and computational simulation. So that these proposed approaches provide efficient experimental method and accurate numerical analysis tools for high speed impact problems.
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