Microstructure and hardness of SAC305 and SAC305-0.3Ni solder on Cu, high temperature treated Cu, and graphene-coated Cu substrates
Shengli Li (Harbin University of Science and Technology)
Y. Liu (Harbin University of Science and Technology, TU Delft - Electronic Components, Technology and Materials)
Hao Zhang (TU Delft - Electronic Components, Technology and Materials, Harbin University of Science and Technology)
Hongming Cai (Harbin University of Science and Technology)
Fenglian Sun (Harbin University of Science and Technology)
Guo Qi Zhang (TU Delft - Electronic Components, Technology and Materials)
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Abstract
In this study, SAC305 and SAC305-0.3Ni solder balls were soldered onto Cu, high temperature treated Cu (H-Cu) and graphene coated Cu (G-Cu) substrates, respectively. The microstructure, the interfacial reaction, and the hardness of the solder joints were investigated. The interfacial intermetallic compound (IMC) is Cu6Sn5 in the solder joints of SAC305/Cu, SAC305/H-Cu, and SAC305/G-Cu. With the addition of 0.3 wt% Ni in the SAC305 solder, the interfacial IMC on Cu, H-Cu, and G-Cu transforms from Cu6Sn5 into (Cu, Ni)6Sn5. The thickness of Cu6Sn5 and (Cu, Ni)6Sn5 is the lowest on G-Cu substrate. Meanwhile, smooth (Cu, Ni)6Sn5 interfacial IMC layers are obtained in SAC305-0.3Ni/H-Cu and SAC305-0.3Ni/G-Cu solder joints. Both the SAC305 and the SAC305-0.3Ni solder bulks have the highest β-Sn content and the lowest concentration of eutectic phases on G-Cu substrate. Consequently, the hardness of the solder bulks on G-Cu is lower than that on the other two kinds of substrates.
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