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Influence of graphene nanosheets addition on the microstructure, wettability, and mechanical properties of Sn‑0.7Cu solder alloy Wenchao Yang1,2,3 · Yang Lv1,2 · Xinjiang Zhang4 · Xuanchen Wei1,2 · Yitai Li1,2 · Yongzhong Zhan1,2,3  Received: 17 May 2020 / Accepted: 30 June 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020

Abstract In this study, Sn-0.7Cu composite solders with different weight of graphene nanosheets (GNSs) were successfully prepared by mechanical milling and hot-pressing sintering. The effects of GNSs on the microstructure, wettability, and mechanical properties of Sn-0.7Cu solder alloys were investigated. The experimental results indicate that the distribution density of GNSs in the solder matrix became larger as the content of the GNSs increased, and the GNSs basically distributed at the grain boundary. In addition, the grain size of the solder deceased firstly and then increased with increasing GNSs. Furthermore, the melting temperature of Sn-0.7Cu-xGNSs composite solders barely change compared with original Sn-0.7Cu solder. After Sn-0.7Cu-xGNSs, composite solders reflowed on Cu substrate at 250 °C for 20 min, and the experimental results reveal that the spread area and spread rate of composite solders on Cu substrate decreased with increasing content of GNSs. In addition, the mechanical properties of Sn-0.7Cu-xGNSs composite solders were obtained by tensile test. The tensile test results show that the yield strength and the ductility of composite solders both increased firstly and then decreased with addition of GNSs. In summary, the composite solders have best ductility and best yield strength when the content of GNSs is 0.05 wt% and 0.075 wt%, respectively.

1 Introduction With the rapid development and miniaturization of surfacemount process in electronic packaging industries, the leadfree solders which were extensively used in microelectronic devices require better mechanical properties [1]. The traditional Sn–Pb solder has been widely applied due to its low

* Yitai Li [email protected] * Yongzhong Zhan [email protected] 1



School of Resources, Environment and Materials, Guangxi University, Nanning 530004, Guangxi, People’s Republic of China

2



Guangxi Key Laboratory of Processing for Non-Ferrous Metals and Featured Materials, Nanning 530004, Guangxi, People’s Republic of China

3

School of Materials Science and Engineering, South China University of Technology, Guangzhou, Guangdong 510641, People’s Republic of China

4

School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224002, Jiangsu, People’s Republic of China





melting point, good wettability, and excellent mechanical properties. However, due to the breakage of environment and health concerns of toxicity of lead, in 2006, international legislation (EU) has promulgated regulations that the usage of the lead is banned in electronic packaging industries [2–4]. This leads to the extensive research and development of leadfree solder materials, such as Sn–Ag [5, 6], S