| Summary: | 碩士 === 國立成功大學 === 材料科學及工程學系 === 104 === Sn-Cu alloys have been recognized as the most promising Pb-free candidates for its well wettibility and lower cost. This study chooses Sn-xCu(x=0.3, 0.7, 2.5, 5 wt.% ) to use in photovoltaic (P.V.) modules, and researches on the applicabilityofSn-xCu/Cu P.V. modules by measuring resistance, microstructure and pull-off test. The result showed that Sn-0.7Cu is the most suitable solder applied in P.V. modules. But after current test, the resistance of Sn-0.7Cu modules increases 52%. In order to fix this problem, we tried two improved experiments.
The first improved experiment is changing solder in modules. Adding 0.2Zn in Sn-0.7Cu could inhibit the growth of IMC that could promote the conductivity of modules. After current test, the resistance of Sn-0.7Cu-0.2Zn modules only increases 9.5% which confirms the true of adding 0.2Zn would stabilize the IMC at interface. The second improved experiment is changing experimental process of P.V. ribbon. Using electroplating to replace hot-dipped could decrease the thickness of solder layer which would decrease the consumption of Ag paste and increase the conductivity of modules.
Sn-0.7Cu-0.2Zn modules have the lowest resistance (0.021 Ω). After 72hr current test, the resistance only increases 0.002Ω. Although PSC modules have the thickest Ag paste after reflowed, the IMCs at interface still over grow after current test. To sum up, depressing the growth of IMC is the best way to enhance conductivity.
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