Life Expectancies of Ni-doped SAC Solder Alloy Subjected to Drop Test Loading

摘要

In this research, the mechanical behavior of novel Ni-doped Sn-1.2Ag-0.5Cu (SAC 1205) solder alloy, characterized by a high strain rate, was investigated in order to improve the drop test simulation model accuracy. Most researches focused on the elastic behavior of solder joint in simulation modeling. However, the sensitive strain rate of solder joint was important to take it into consideration since the solder joint was suffered the impact pulse during the drop test. In line with the drop test standard (JEDEC condition B), the test vehicle was subjected to impact loading with the peak acceleration of 1500 G for a period of 0.5 ms. This scenario ensured that the solder joint connecting the package and the test board was subjected to the impact loading for a very short time. In this study, the focus was on Thin Fine-pitch Ball Grid Array (TFBGA) package and the 11 mm × 10.6 mm, 9.4 mm × 9.4 mm, 12.6 mm × 12.6 mm, and 13.1 mm × 13.1 mm package sizes were investigated. The aim was to calculate the solder joint fatigue life by combining the results of finite element modeling with those obtained by experimental testing. The finite element model was used to analyze the stress and strain of the solder joint during the drop test. The model was developed using ANSYS/LS-DYNA and yielded a dynamic explicit solution. In order to investigate the performance of Ni-doped SAC 1205 solder alloy under the drop test conditions, the prediction model of solder alloy fatigue life was developed based on the Physics of Failure (PoF). The purpose of this research is to establish the fatigue life of SAC 1205N solder alloy with considering the sensitivity of strain rate for solder material.