Microstructure, mechanical and electrical performances of zirconia nanoparticles-doped tin-silver-copper solder alloys

The present study investigates the influence of ZrO2 nanoparticles addition on microstructure, material properties i.e., elastic moduli, creep behavior, hardness, shear strength and electrical resistivity of Sn–3.0Ag–0.5Cu (wt%)-based interconnected alloys. From microstructure observation it was revealed that in the plain Sn–Ag–Cu bulk solder a needle-shaped Ag3Sn and irregular shaped Cu6Sn5 IMC particles were formed in the elongated-like β-Sn grains. However, in the composite solder alloy, very fine needle-shaped Ag3Sn and irregular shaped Cu6Sn5 IMC particles were formed in equiaxed β-Sn grain matrix. Further, material properties like elastic moduli, hardness, creep behavior and electrical resistivity of Sn–Ag–Cu solder were improved significantly after adding the ZrO2 nanoparticle. Sn–Ag–Cu-based composite solder joints were prepared on Au/Ni-metallized Cu pad ball grid array (BGA) substrate and investigated their performance after exposing a thermal shock chamber at –40 to 90 °C. From this test, it was confirmed that the degradation behavior of plain solder joints was much faster as compared to the composite solder joints and also detected some micro-cracks at the interface and solder matrix. Further, the shear strength of plain solder joints was decreased significantly as compared to the composite solder joints.