Microstructure and hardness of SAC305 and SAC305-0.3Ni solder on Cu, high temperature treated Cu, and graphene-coated Cu substrates

Li, Shengli; Liu, Y.; Zhang, H.; Cai, Hongming; Sun, Fenglian; Zhang, Kouchi

doi:10.1016/j.rinp.2018.10.005

Microstructure and hardness of SAC305 and SAC305-0.3Ni solder on Cu, high temperature treated Cu, and graphene-coated Cu substrates

Title

Microstructure and hardness of SAC305 and SAC305-0.3Ni solder on Cu, high temperature treated Cu, and graphene-coated Cu substrates

Author

Li, Shengli (Harbin University of Science and Technology)
Liu, Y. (TU Delft Electronic Components, Technology and Materials; Harbin University of Science and Technology)
Zhang, H. (TU Delft Electronic Components, Technology and Materials; Harbin University of Science and Technology)
Cai, Hongming (Harbin University of Science and Technology)
Sun, Fenglian (Harbin University of Science and Technology)
Zhang, Kouchi (TU Delft Electronic Components, Technology and Materials)

Date

2018

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.