碲化鉍熱電材料(Bi2Te3)是常溫下具有最高熱電轉換效率之熱電材料，其與銅導線之間是以無鉛銲料進行迴銲接合形成熱電模組，然而此迴銲作業會在無鉛銲料與熱電材料之界面處生成多孔且脆的SnTe介金屬化合物，於界面處鍍製鎳擴散阻障層可抑制此化合物的生成。本研究選用p型之碲化鉍熱電材料((Bi0.2Sb0.8)2Te3)、SAC305與純Sn銲料及無電鍍方式鍍製鎳擴散阻障層。以百格測試方法對鎳層鍍製於p-BST後之附著程度進行測試，及使用推力測試機台對銲料與熱電材料反應生成之SnTe介金屬化合物進行機械性質測試，並觀察鎳擴散阻障層對系統機械性質的影響。 實驗結果顯示，p-BST表面之粗糙程度隨蝕刻時間的增加而上升，鎳層在蝕刻120秒之條件有最佳之附著結果，而隨著蝕刻時間的增加，p-BST表面會有孔洞的生成，將對附著能力產生影響。推力測試後，SAC305/p-BST系統之破壞皆由基材處發生，而Sn/p-BST系統則是發生在SnTe介金屬化合物內。另外，不論迴銲時間的增加或是多次迴銲條件下，Sn/p-BST系統生成極厚的SnTe介金屬化合物是降低系統機械強度的主要因素；Sn/Ni-P/p-BST系統則在多次迴銲後維持相同的機械強度，且鎳擴散阻障層加入SAC305/p-BST系統後可以改變測試後的破壞行為，由p-BST處轉變成銲料內，因此鎳擴散阻障層不僅能抑制SnTe介金屬化合物的生成，也同時能維持系統之機械性質。 ;Bismuth-Telluride material is an effective thermoelectric material and has the best device efficiency at room temperature. Since lead-free solder is applied in the thermoelectric module, the interfacial reaction forms a thick and porous intermetallic SnTe layer. A Ni diffusion barrier deposited at the interfaces can effectively prevent the formation of SnTe. The thermoelectric material and solder used in this research are (Bi0.2Sb0.8)2Te3 (abbreviated to p-BST) and SAC305, pure Sn. The Ni diffusion barrier was deposited by electroless plating method. This research performed peeling test on the adhesion between Ni layer and p-BST, and shear test on the SnTe intermetallic compounds which form at the interfaces of solders and p-BST, also compared with the systems coating Ni diffusion barrier. The results show that the surface roughness of p-BST increase with the increasing etching time and the adhesion ability of Ni layer has the best adhesion ability after etching for 120 seconds. With increasing etching time, voids will form at p-BST surface and that result in poor adhesion ability. After shear test, the failure occurred in the p-BST region for the SAC305/p-BST systems, but the failure occurred inside SnTe for the Sn/p-BST systems. On the other hand, the increase of the SnTe thickness is the main factor which decrease the shear strength after prolonging reaction time or multiple reflow. The shear strength maintain at the same value for the Sn/Ni-P/p-BST systems. Ni diffusion barrier also alter the failure mode as coated between SAC305 and p-BST systems. These results show that Ni diffusion barrier not only inhibit the formation of SnTe but also prevent the degradation of solders and p-BST systems.
