Liquid-state interfacial reactions of p-type (Bi,Sb)2Te3 thermoelectric (TE) material with Sn and Sn-3.0 wt.%Ag-0.5 wt.%Cu (SAC305) solders, respectively, were examined at 250°C on a commercial highly orientated (Bi,Sb)2Te3 substrate with a (110) soldering plane. For the reactions with Sn, the initial reaction phase was the porous SnTe intermetallic compound (IMC). Then, a dense SnTe layer with many tiny cracks formed between the porous phase and TE substrate. With longer aging time, the dense SnTe gradually changed to the porous phase due to Sb dissolution. In the subsequent stage, the reaction phase zone included porous SnTe, an alternating layer microstructure of SnTe and liquid solder, and SnTe/Sn3Sb2 alternating layers from the solder to TE. The IMC growth was extremely fast, being approximately 15 μm/min, and nearly linear with aging time, suggesting reaction control. For the reactions with SAC305, a similar microstructure of porous SnTe and the dense layer was observed. Compared with the reactions with Sn, however, the IMC growth rate was greatly suppressed by ~ 80%. This can be attributed to the Ag-rich phase layer between the dense SnTe and (Bi,Sb)2Te3. Ag was verified to be the key element for dramatically changing the interfacial reaction behavior.

中文翻译：

---

Sn 和 Sn-Ag-Cu 焊料与 p 型 (Bi,Sb)2Te3 热电材料的液态界面反应

p 型 (Bi,Sb)2Te3 热电 (TE) 材料分别与 Sn 和 Sn-3.0 wt.%Ag-0.5 wt.%Cu (SAC305) 焊料的液态界面反应在 250°C 下在具有 (110) 焊接平面的商用高度定向 (Bi,Sb)2Te3 衬底。对于与 Sn 的反应，初始反应阶段是多孔 SnTe 金属间化合物 (IMC)。然后，在多孔相和 TE 衬底之间形成具有许多微小裂纹的致密 SnTe 层。随着老化时间的延长，由于 Sb 溶解，致密的 SnTe 逐渐转变为多孔相。在随后的阶段，反应相区包括多孔 SnTe、SnTe 和液态焊料的交替层微观结构，以及从焊料到 TE 的 SnTe/Sn3Sb2 交替层。IMC 增长非常快，大约为 15 μm/min，并且与老化时间几乎呈线性关系，建议反应控制。对于与 SAC305 的反应，观察到多孔 SnTe 和致密层的类似微观结构。然而，与与 Sn 的反应相比，IMC 的生长速度被大大抑制了约 80%。这可归因于致密 SnTe 和 (Bi,Sb)2Te3 之间的富银相层。银被证实是显着改变界面反应行为的关键元素。