電遷移對共晶錫鉍銲點微結構與界面反應之影響

Electromigration Effects on Microstructure and Interfacial Reaction in Eutectic SnBi Solder Joint

陳龍泰(L. T. Chen) ； 陳志銘(C. M. Chen)

《材料科學與工程》 38卷2期 (2006/06) Pp. 88-92

https://doi.org/10.6409/JMSE.200606.0088

摘要

對於低溫無鉛銲料之發展，共晶Sn-58Bi合金是相當具有潛力的候選材料之一。本研究的目的在探討電遷移效應對共晶Sn-58Bi銲點微結構與界面反應之影響，實驗方法首先將共晶Sn-58Bi銲料回銲於金／鎳墊層上，接著施以5×10^3A/平方公分之電流密度，在70℃之溫度下進行爲期5至15天之反應，另外亦進行一組未通電之熱處理實驗作爲對照。實驗結果顯示在陽極端觀察到富Bi相之堆積層，且堆積層之厚度隨著反應時間之拉長而增加，顯示電遷移效應會造成Bi原子往陽極端移動。而藉由富Bi層於陽極端的堆積速率，可以推算出共晶Sn-58Bi銲料之DZ(上标 *)值3.9×10^(-10)(平方公分/s)。此外，亦觀察到通電10天後陰極和陽極端皆有二層介金屬化合物(Ni3Sn4與Au-Ni-Bi-Sn)之生成，而通電15天後陰極端仍有二相Ni3Sn4與Au-Ni-Bi-Sn之生成，然而陽極端卻只發現Ni3Sn4一相，另外未通電之結果則顯示僅有Ni3Sn4之生成。本研究也觀察到電遷移效應會加速銲料內富Bi相之成長粗化。

關鍵字

電遷移 ； 共晶Sn-58Bi銲料 ； 金／鎳墊層 ； 微結構變化 ； 界面反應

並列摘要

Microstructural evolution and interfacial reaction in the eutectic SnBi solder joint on the Ni/Au metallization with and without the current stressing of 5×10^3 A/cm^2 at 70℃ for 5 to 15 days are investigated. Electromigration is found to have significant effects not only on the phase formation at the joint interface but also on the phase coarsening and mass accumulation of Bi in the solder. In the solder joint without the current stressing, only a thin Ni3Sn4 phase was formed at the joint interface. For the solder joint with the current stressing, in addition to the Ni3Sn4 phase, a thick Au-Ni-Bi-Sn phase was formed at the joint interface after 10 days. However, the Au-Ni-Bi-Sn phase was not observed at the anode-side joint interface after 15 days of current stressing. Coarsening of the Bi-rich grain in the solder joint with the current stressing was much faster than that without the current stressing. Mass accumulation of Bi was observed at the anode side of the solder joint with the current stressing and the thickness of the Bi-rich accumulation layer increased with current stressing time. Based on the accumulation rate of the Bi-rich layer and the growth rate of the Bi-rich grain, the product of diffusivity and effective charge number of Bi in the eutectic SnBi solder is calculated to be 3.9×10^(-10) cm^2/s.

並列關鍵字

Electromigration ； eutectic SnBi solder ； Ni/Au metallization ； microstructure ； interfacial reaction