在熱電元件的製作過程中，會使用軟銲技術來連接不同的金屬材料，而不同金屬相連接會發生界面反應，生成介金屬相。介金屬相的產生可能會影響熱電材料的性質，或造成銲點的機械強度下降，因此在製程中會使用阻障層鎳，防止銲料與熱電材料反應。本研究探討無鉛銲料中主要元素錫，與阻障層鎳對n型及p型商用組成之熱電材料(Bi0.25Sb0.75)2Te3、Bi2(Te0.9Se0.1)3，及其二元系統Sb2Te3、Bi2Te3、Se2Te3在250 oC的界面反應。在Sn/(Bi0.25Sb0.75)2Te3與Sn/Sb2Te3的界面反應中，在短時間時均生成單一層生成相SnTe + Liquid相。當反應時間增長，SnTe + Liquid相會增厚，且在靠近基材端會出現Sn3Sb2與SnTe的深淺交錯排列條紋，而Sn/(Bi0.25Sb0.75)2Te3反應偶中還會出現Bi白點析出。
在Sn/Bi2(Te0.9Se0.1)3界面反應中，生成深灰色SnTe相及白色Bi6Te7與BiTe相，Se並未參與反應。其二元系統Sn/Bi2Se3界面反應生成SnSe及BiSe相；Sn/Bi2Te3之反應速率十分快速，約59 μm/min，生成不平整之SnTe + Liquid相。在Bi2(Te0.9Se0.1)3材料中，Se含量雖只佔材料中的6%且未參與反應，卻使Sn/Bi2(Te0.9Se0.1)3與Sn/Bi2Te3界面反應之生成相及反應速率有很大的差異。
在Ni/(Bi0.25Sb0.75)2Te3固/固反應中，生成深灰色NiTe相及不連續之白色塊狀相，為(Bi,Sb)2Te3相。其中NiTe相機械性質不佳，易在研磨過程中碎裂。Ni/Bi2(Te0.9Se0.1)3反應偶則生成NiTe相及白色的BiTe相。Ni在此反應偶中擴散較快，所生成之介金屬相也較厚。Ni的快速擴散及所生成的介金屬相，可能會影響熱電元件的性質以及可靠度。

(Bi1-xSbx)2Te3 and Bi2(Te1-ySey)3 are common thermoelectric materials. In the manufacturing of thermoelectric device, Sn is the major element for most of the electronic solders, and Ni is used as diffusion barrier. The interfacial reactions between Sn, Ni and (Bi1-xSbx)2Te3, Bi2(Te1-ySey)3 thermoelectric materials will be investigated in this study. The interfacial reactions at 250 oC in the Sn/(Bi0.25Sb0.75)2Te3 and Sn/Sb2Te3 couples are examined. The initial reaction product only has one phase, and is SnTe phase with small pores which are filled with liquid. With longer reaction time, the small liquid droplets connect together and form periodic liquid layer in the reaction zone. The liquid layer, which is primarily molten Sn, further reacts with Sb, and a self-assembled Sn3Sb2/SnTe alternating layer is found in the couples. Bi precipitates are found as well in the reaction zone in the Sn/(Bi0.25Sb0.75)2Te3 couples in the later stage of reactions.
In Sn/Bi2(Te0.9Se0.1)3 couple, it formed SnTe, Bi6Te7, and BiTe phase. Sn/Bi2Se3 couple formed SnSe and BiSe phase. In Sn/Bi2Te3, the interfacial reaction rate is fast, and the growth rate is about 59 μm/min. It formed a irregular SnTe + Liquid phase. The amount of Se in Bi2(Te0.9Se0.1)3 substrate is only 6%, but it’s growth rate and intermetallic compound are very different compared with Sn/Bi2Te3 couple.
The Ni/(Bi0.25Sb0.75)2Te3 and Ni/Bi2(Te0.9Se0.1)3 couples both formed NiTe phase, and Ni/Bi2(Te0.9Se0.1)3 also formed BiTe phase. Ni penetrates deeper in Bi2(Te0.9Se0.1)3 substrate. The fast diffusion rate may cause failure or lower the efficiency in thermoelectric device.

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