本文係針對覆晶封裝(Flip-chip Packages)探討銲錫接點失效，其主要方法係採用含電熱耦合效應之電性分析，並進一步改變輸入電流值、導線層材料及UBM厚度，分析其孔洞生成的位置與變化。因此，首先使用有限元素分析軟體ANSYS進行模擬銲錫接點的電性分析，觀察其內部電流密度集中區域以及溫度分佈狀況。接著改變輸入電流值、導線層材料及UBM厚度，並分析三種變因對模型內部之電流密度、溫度與焦耳熱的影響程度。
由電流密度與焦耳熱最大值可知關鍵破壞處皆在覆晶銲錫接點之陰極處附近，即孔洞會最先在此處形成，然後隨著時間增加而沿UBM與銲錫的接面擴展，最後造成銲點失效。接著以不同輸入電流值、導線層材料及UBM厚度進行分析，可知當輸入電流愈大，關鍵破壞處之電流密度愈大，溫度也愈高，所產生之焦耳熱也愈大。將模型之鋁墊與鋁導線部分更換為銅材料，關鍵破壞處的電流密度會變小，溫度也降低許多，所產生的焦耳熱也較小。當UBM厚度為0.45μm時，關鍵破壞處之電流密度與焦耳熱最大值皆較UBM厚度為0.5μm與0.55μm大。當輸入電流為40mA且UBM厚度為0.5μm，UBM上靠近陰極彎角處之電流密度為1.56x106A/cm2，將模型之鋁墊與鋁導線部分更換為銅材料後，此處之電流密度降低為1.27x106A/cm2，較原先數據小約18.6%。然而當輸入電流為40mA且導線層材料仍為鋁，將UBM厚度由原本的0.5μm分別改為0.45μm以及0.55μm，可發現UBM上靠近陰極彎角處之電流密度改變分別為增加61.5%以及幾乎不變。

By focusing on a Flip-chip Packages, this study aims to discuss the failure behavior of the solder joint. An advanced electro-thermo coupling model is adopted. Furthermore, the input current value, the material compositions of the conductor layer and the thickness of the UBM are changed to analyze the location and its change of the voids. Therefore, the finite element analysis software ANSYS is applied to simulate and analyze the solder joints under electromigration. Subsequently, the current density distribution and the temperature distribution are investigated. Finally, the the input current value, the material compositions of the conductor layer and the thickness of the UBM are changed to investigate their effects on the current density, temperature and Joule heating in the model.

The failure of a flip chip solder joint is always at cathode chip side where the voids appear initially based on the maximum value of current density and Joule heating. Accordingly, the void consistently expand along the interface of UBM and solder bump, and eventually leads to the failure of the solder joint. Then, the input current value, the material compositions of the conductor layer and the thickness of the UBM are changed to analyze the change of the current density distribution and the temperature distribution. It shows that all the current density, temperature and Joule heating increase at the current crowding spots when current input increases. Once the material composition of the conductor layer is changed to Cu, all the current density, temperature and Joule heating decrease at the current crowding spots. It also shows that current density and Joule heating at the current crowding spots with the thickness of the UBM is 0.45μm is larger than that with the thickness of 0.5μm or 0.55μm. For example, when current input is 40mA and the thickness of the UBM is 0.5μm , the current density at the current crowding spot on the UBM is 1.56x106A/cm2. Once the material compositions of the conductor layer is changed to Cu, the current density at the current crowding spots on the UBM is 1.27x106A/cm2. It is about 18.6% lower than before. However, when current input is 40mA and the material compositions of the conductor layer is still Al , the current density at the current crowding spot on the UBM becomes 61.5% increasing and is almost no change with the thickness of the UBM from the original 0.5μm to 0.45μm and 0.55μm respectively.

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