能源相關的開發與應用一直是近年來全世界皆致力研究的重要議題。在能源使用的過程中有多達2/3的能源都是以廢熱的形式損耗掉，若能重新使用廢熱能，將對提升能源使用率帶來可觀助益。熱電裝置即是一種將廢熱重新轉換成電力的獵能技術。然而熱電材料在經過模組化封裝後，接合處常伴隨發生劇烈的界面反應，進而使得熱電模組的可靠度與熱電表現因而劣化。本研究利用無電鍍鈷磷層作為低溫碲化鉍熱電材料的擴散阻障層，繼而探討其對熱電接點的界面反應、機械行為、接觸電阻、以及熱電表現的影響。在界面反應的探討中，銲料若與熱電母材進行直接接合，界面處將發生嚴重的交互擴散並生成大量介金屬化合物，進而對熱電接點的穩定性產生衝擊，此外脆性的介金屬化合物也為熱電模組的可靠度帶來疑慮。若添加無電鍍鈷磷擴散阻障層於銲料與熱電基材之間，界面處的穩定性即可大幅改善，並能有效抑制脆性碲化錫介金屬化合物的生成。在分析接點的機械性質時，可見得在添加鈷磷擴散阻障層後，接點的推力強度具顯著提升，此成效可歸因於界面穩定性的改善，有效減少生成脆性相。由破斷面的分析可知，接點的破斷模式因為阻障層的添加變得更具延展性，相較於直接接合的試片，斷裂前所能承受的吸收能也因此增高，並能增強熱電模組的機械強度。由量測熱電性質變化之結果中可知，添加無電鍍鈷磷層並不會造成性質劣化，P型接點之性質甚至在熱儲存後更為優化。綜合上述可知，無電鍍鈷磷擴散阻障層不僅能改善界面的穩定性，還能提升接點的機械性質可靠度，且不會影響熱電表現，可以有效提升模組接點可靠度。;Energy-related applications have become attractive research areas in recent years. The thermoelectric device is an energy harvesting technology that utilizes the conversion between heat and electricity to promote energy usage efficiency. However, in the assembly of the thermoelectric devices, severe interfacial reactions occur at the joint interface, and this degrades the reliability of the thermoelectric module and deteriorates the thermoelectric performance. In this study, an electroless Co-P layer was used as the diffusion barrier for Bi2Te3-based thermoelectric devices. The influence of the diffusion barrier on the interfacial reaction, mechanical behavior, contact resistivity, and thermoelectric properties of thermoelectric joints was analyzed. Regarding the interfacial reaction, if solders are directly bonded with thermoelectric substrates, multiple intermetallic compounds (IMCs) will form at the interface, which will affect the stability of the thermoelectric joints. In addition, the brittle nature of IMCs will cause a reliability concern for the thermoelectric devices. The addition of a Co-P diffusion barrier will significantly improve the interfacial stability and effectively inhibit the formation of brittle SnTe IMC. Regarding the mechanical behavior of thermoelectric joints, their joint shear strength was significantly improved after the Co-P diffusion barrier was applied. The failure mode of the thermoelectric joints became more ductile due to the added barrier layer. The results of shear test correlated with the optimized interfacial stability of thermoelectric joints. Most importantly, the addition of the Co-P diffusion barrier did not cause a significant deterioration in thermoelectric properties. These findings indicate that the Co-P layer is a promising diffusion barrier for Bi2Te3-based thermoelectric devices.
