- 期刊
含鉛與無鉛錫球在FCOB封裝體上之熱－機械行為的比較
Comparison of Thermo-Mechanical Behaviors on FCOB Packages with Lead and Lead-free Solder Bumps
摘要
本文利用有限元素分析－ANSYS探討FCOB封裝體內無鉛錫球96.5Sn/3.5Ag在底部充填後的熱－機械行為，以典型的－55~125℃溫度循環負載之時間－溫度相關的非線性分析，並模擬錫球塑性與潛變行為。文中以63Sn/37Pb錫球為基準，並皆遵守Garofalo-Arrhenius穩態潛變本質方程式，探討最外且貼近晶片端錫球之應力、塑性與潛應變遲滯迴圈、應力歷史及塑性與潛應變歷史；又無鉛錫球96.5Sn/3.5Ag具有較高的熔點，其在回銲製程需經過較高的回銲溫度，因此在較高－55~155℃溫度循環負載下，分析結果顯示，無鉛錫球96.5Sn/3.5Ag仍然有較佳之防止潛變效果。
並列摘要
The finite element analysis code-ANSYS was employed to probe the thermal-mechanical behaviors of lead- free solder 96.5Sn/3.5Ag in FCOB after underfill processing in this study. The temperature range of -55~125℃, time-dependent and nonlinear material properties were considered in this analysis to simulate the plasticity and creep behaviors of solders. The lead solder of 63Sn/37Pb is also considered to establish a baseline. All of these solder alloys are assumed to obey the Garofalo-Arrhenius steady-state creep constitutive law. The equivalent stress, equivalent plastic strain and creep strain hysteresis loops, equivalent stress history. and equivalent creep strain history at the outmost and farthest solder and near the chip are studied for the flip-chip packages. Moreover, since the lead- free material 96.5Sn/3.5Ag has the higher melting point than 63Sn/37Pb, it needs higher reflow temperature during reflow process. For higher cycling temperature with loading rang -55~155℃, the lead-free solder 96.5Sn/3.5Ag still has good performance on creep.