碲化鉛熱電材料與銅電極之填料接合性質研究

Abstract

熱電材料可將熱能轉換成為電能，但其模組製作是一大挑戰，特別是熱電材料與電極接合之技術。PbTe是重要的中高溫熱電材料，本研究改變不同填料，在真空環境中進行PbTe熱電材料與銅電極之接合，實驗結果發現，利用固態擴散接合，將AgCuTi銲片與PbTe熱電材料接合，在520℃持溫60分鐘，發現AgCuTi銲片裡的Ti元素會與Te元素產生TeTi化合物，進而達成接合效果，但也發現Ag元素會有擴散到熱電材料之情形。利用複合銲片接合，填料為助銲劑、SnAg銲片、AlSi銲片與PbTe熱電材料接合，在320℃與580℃個別持溫20分鐘，有最佳的接合效果，在銲道裡沒有發現氣孔與裂痕，但銲道裡有銅元素散佈之情形，未來必須要再增加擴散阻障層，以阻擋銅擴散之情形。hermoelectric materials can be applied for converting heat energy directly to electric power. However, joining of thermoelectric material with electrode is a main challenge in constructing thermoelectric devices for the practical application. PbTe is regarded as one of the most likely materials working at intermediate temperature region. In this study, joining of PbTe thermoelectric materials and Cu electrode has been performed by changing different metal fillers, which were heated at elevated temperature and vacuum environment. The experiment results showed that the insertion of AgCuTi filler between PbTe and Cu can achieve effective joining at heating temperature of 520℃ and holding for 60 minutes. The compound of titanium and tellurium formed in the interface of joints which may promote the joining effect. However, diffusion of silver atoms to PbTe has been found, which may influence the thermoelectric properties of device. On the other hand, the use of flux/SnAg/AlSi fillers as incorporation can also attain effective joining at heating temperature of 320℃ and 580℃, which holding for 20 minutes respectively. There is no void and crack can be found in the interface of joints. However, the diffusion of copper atoms in the welding zone is a noteworthy problem.