Interfacial Reactions Between Thermoelectric Materials and Solders (SAC105, SAC305, LF35)之界面反應

• Main Authors: Ming-Ching Tsai, 蔡明錦
• Other Authors: Chih-Ming Chen
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/66368892721614021481

碩士 === 國立中興大學 === 化學工程學系所 === 102 === The main trend for the world is looking for environmentally friendly material and saving energy in order to preserve the limited resources on Earth. Thermoelectric materials have the characteristic of converting heat and electricity back and forth, so it has already been widely used in our life. The good Z value (figure of merit) of bismuth telluride has made it the most popular choice in low temperature usage, but the concern is that the formation of intermetallic compound SnTe during the reaction of bismuth telluride with solder Sn will affect the electrical property and reliability. The problem can be solved by either adding some metals into the solder or electroplating a Ni diffusion barrier layer between solder and bismuth telluride in order to suppress the formation of intermetallic compound SnTe. This study investigates the interfacial reactions of three different solders (SAC105, SAC305, and LF35) with N (Bi2Te2.7Se0.3) type and P (Bi0.5Sb1.5Te3) type substrates. The experiment runs with different reflow times under the constant temperature of 250oC and obtains the relationship between reaction time and the thickness of intermetallic compound for further exploring the growth mechanism. The result shows the combination of N type substrate with LF35 solder has higher intermetallic compound thickness and the main diffusion elements are Bi and Te for forming SnTe and BiTe intermetallic compounds. On the other hand, P type substrate with SAC305 solder has the lowest intermetallic compound thickness and the main diffusion elements are Sb and Te for forming SnTe and SbSn intermetallic compounds. Hence, the kinetic n value can be derived from the thickness of intermetallic compound to assume the reaction mechanism.