Effect of nano-Al addition on properties and microstructure of low-Ag content Sn–1Ag–0.5Cu solders

In this paper, Al nanoparticles were manually mixed into the Sn–1Ag–0.5Cu solder paste to prepare composite solder. The content of Al nanoparticles ranged from 0 to 0.4 wt% in the solders. The influences of Al nanoparticles on the melting characteristics, wettability, mechanical properties, microstructure and interfacial intermetallic growth of low-Ag Sn–1Ag–0.5Cu solders on copper substrate were investigated. Results show that added Al nanoparticles can not obviously change the melting point of the Sn–1Ag–0.5Cu solder, and improve the wettability and mechanical properties of plain Sn–1Ag–0.5Cu solder. However, excessive addition Al nanoparticles will reduce the wettability and mechanical properties of the solder. There is an optimum amount of Al nanoparticles in Sn–1Ag–0.5Cu solder, which is 0.1 wt%, and Sn–1Ag–0.5Cu–0.1Al nano-composite solder exhibit the best comprehensive properties. Based on the microstructure examination, it is found that adding Al nanoparticles can obviously refine the microstructure of Sn–1Ag–0.5Cu–xAl solder. In addition, the interfacial intermetallic compounds (IMC) layer thickness of the Sn–1Ag–0.5Cu–xAl solders are smaller than that of plain Sn–1Ag–0.5Cu solder, which indicates that Al nanoparticles can effectively suppress IMC formation and growth.