Reliability of Ni-modified reduced graphene oxide reinforced Sn-58Bi/Cu solder joints after isothermal aging

• Systematic investigation of rGO@Ni effects on Cu/Sn-58Bi solder joints • rGO@Ni modifies Sn grain orientations, regulates IMC growth, and improves mechanical properties. • 0.01 wt% rGO@Ni suppresses Cu–Sn interdiffusion during aging, reducing IMC thickness and stabilizing shear performance. The Joule heat generated during the opreation of microelectronic devices can subject the Sn-Bi solder alloy to isothermal aging, which affects the reliability of solder joint interconnections. In this study, the effect of nickel-modified reduced graphene oxide (rGO@Ni) on the microstructure and shear fracture behaviour of Cu/Sn-58Bi-rGO@Ni/Cu solder joints was investigated. The solder joints were reflowed at 160 °C to 180 °C for 80 s, followed by isothermal aging at 100 °C for different time. The crystal structure of the solder was analysed by electron backscatter diffraction. The morphology of the solder joints was observed by scanning electron microscopy. The results showed that the growth rate of the IMC layer in the Sn-58Bi-0.01rGO@Ni solder is the slowest. The addition of 0.01 wt% rGO@Ni reduces the risk of brittle Bi phase and enhances the shear strength of the solder joints.