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.