| Summary: | 碩士 === 國立臺灣科技大學 === 材料科學與工程系 === 101 === In this study, the Sn-Zn alloys were used as the solders because of its low cost and the melting point is closer to the conventional Sn-Pb solder.
However, BGA and FC technology are two of the mainstreams applied to the electronic packaging widely, and the Ni/solder/Cu structure is the most common one. Therefore, this study demonstrates interfacial reaction of the Ni/Sn-xZn/Cu sandwich structure couples, the purpose is to investigate whether the Zn content of the Sn-Zn alloy, inter-diffusion between Cu and Ni atoms and the thickness of the solders will effect the formation of IMC phases.
The results reveal that the Zn content of the Sn-Zn alloy and the diffusion of Cu atoms will affect the formation of IMC phases. When the Zn content is 1 wt%, the (Ni, Cu)3Sn4 phase was formed on the interface of the Ni side after soldering. Then, the (Ni, Cu)3Sn4 phase changed into the (Cu, Ni, Zn)6Sn5 phase after aging for 40 h. While the Zn content is more than 5 wt%, the Ni5Zn21 phase was formed on the interface of the Ni side, and the Cu5Zn8 phase was formed on the interface of the Cu side. After long-term aging, the Cu5Zn8 phase departed from the interface, and the Sn atoms refilled the vacancies. Then, the (Cu, Zn)6Sn5 phase was formed on the interface between the Cu5Zn8 phase and the Cu substrate.
The thickness of the solders were decreased to 0.5 mm to make the Cu atoms diffuse to the Ni side more quickly, then cause the transformation of IMC phase on the Ni side.
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