- 學位論文
錫鉍銲料與金基材界面反應之研究
The study of interfacial reaction between SnBi solder and Au substrate
摘要
錫鉍銲料與金基材之間的介面反應，會形成錫金二元系的介金屬相。鉍含量的多寡，決定了介金屬化合物的組成。當鉍含量高於57wt%時，界面上的兩種介金屬相是AuSn及AuSn2；而當鉍含量為50wt%時，在相同的條件下，會多生ㄧ新的介金屬相，為Sn-Bi-Au的三元介穩相，而此介穩相在時效溫度較高或是時效時間增加的情況下會完全轉換成AuSn4，所以當反應時間增加至72小時的條件下，最終介金屬相會形成三層介金屬相，分別為AuSn、AuSn2及AuSn4。同時在原本看似連續層介金屬相中，也會出現富鉍相的聚集，形成許多小白點，以及在AuSn4的外層出現連續狀的富鉍連續層。 從反應動力學的觀點，以介金屬相的厚度，對時間的平方根做圖，藉由線性迴歸，圖形趨近於一斜直線。由此可知，介金屬的成長主要是擴散機制所控制，並且，在固定錫鉍銲料組成的條件下，隨著反應時間與時效溫度的增加，介金屬層厚度與生成速率常數(k)也隨之增加；但在反應溫度及反應時間固定的條件下，隨著鉍含量的增加，介金屬層的厚度和生成速率常數(k)則是下降。然後再將不同反應溫度與k值的數據代入Arrhenius equation中，可以計算反應活化能。數據顯示共晶組成的錫鉍銲料具有較低的反應活化能，當鉍含量越高，介金屬相的生成活化能也相對較高，因此較不易生成介金屬化合物。
並列摘要
The interfacial reaction between Sn-Bi solder and Au substrate grows Sn-Au intermetallic compound (IMC) mainly. The constituent of IMC depends on the composition (wt%) of Bi in the solder. When the weight percent of Bi is more than eutectic composition (57wt%), AuSn and AuSn2 would be found at interface. When the composition of Bi is 50wt%, a Sn-Au-Bi ternary metastable compound was formed and after longtime aging or the reaction temperature was increased, the ternary compound will become AuSn4. That means AuSn、AuSn2 and AuSn4, three different Sn-Au IMC will be co-existing at the interface. After longtime aging there are some Bi-rich segregation in the intermetallic compound and others which segregate between IMC and solder become a continuous layer. Based on reaction kinetics, we plotted the IMC thickness vs the square root of time and obtained a linear relationship between these two variables by means of linear regression model. The figure shows a straight line, which means that the growth of IMC is controlled by diffusion mechanism. In the figure, we also know that thickness and growth rate constant (k) are increasing with time and temperature for a specific composition of Bi but decreasing with the composition of Bi in the solder under the fixed conditions of temperature and reaction time. Then we substitute the growth rate constant (k) and temperature into Arrhenius equation, we would obtain the reaction activity energy (Q). When the solder is eutectic, the result shows that the reaction activity energy is the lowest and it decreases when the composition of Bi increases.