| Summary: | 碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 101 === With the importance of energy and environmental issues increase, recycling and reuse of waste heat become an important part of sustainable development.Additionly, when the electronic component size quickly significantly reduced, resulting in heat density increases, which means thermal management technology has attracted more attention. Thermoelectric material has a feature that it can convert heat and electricity into each other, which means a great potential for applications in waste heat recovery and development; thermoelectric cooler also has a number of advantages that can be used to solve the heat dissipation problem of small size electronic components.
The conversion efficiency of thermoelectric materials increases with the thermoelectric figure of merit (ZT) increases, and they can be divided into three types according to their operating temperature. However, the conversion efficiency of one single thermoelectric material is limited, so the most conmmon application is connecting the P-type and N-type thermoelectric materials in series to become modules. In this study,we choose the P-type thermoelectric material Zn4Sb3 as a base material, Cu as an electrode , Ni as a diffusion barrier layer; elecroplate Ag and Sn layer on bonding interface respectively, as high and low melting point metal for solid-liquid interdiffusion bonding. Bonding the sample with different parameters,and analses the two systems:preheating & non-preheating.
Experimental results show that the preheating system will generate cracks between the interface of Zn4Sb3/Sn/Ni, and cuase the sample fail at this position; their strength are lower than those without preheating, about 10MPa ~ 15MPa. However, the non-preheating system shows that Zn4Sb3 can provides Zn to react with Ni and form an intermetallic Ni5Zn21 directly.The interface between Ni5Zn21 and Zn4Sb3 is smooth and continuous, providing the system a higher strength value, about 15 ~ 20MPa, even more than 20MPa. Although the non-preheating system shows better bonding results, Ni still can’t be used as a barrier layer for SLID between Zn4Sb3 and Cu electrode. After aging, Ni will be completely exhausted since Zn4Sb3 can provide an unlimited amount of Zn to react with it to form Ni5Zn21. Once the Ni layer disappear, all metal atoms will interdiffuse to whole system and cause the sample fail eventually.
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