Effect of nano-TiO2 addition on wettability and interfacial reactions of Sn0.7Cu composite solder/Cu solder joints

The influences of intermixing nano-TiO₂ particles on the wettability and interfacial reaction of Sn0.7Cu composite solder with Cu substrate were investigated. The wettability of the Sn0.7Cu composite solder alloy was measured by the sessile-drop method under a 10^-3 Torr vacuum solder at 250 °C up to 1800 s. Scanning electron microscopy (SEM) was used to quantify the interfacial microstructure for each processing condition. The wettability property was improved by 0.25 - 1.0 wt.% addition of nano-TiO₂ particles into the Sn0.7Cu solder. Intermetallics formed at the Sn0.7Cu composite solder/Cu interface were identified as Cu₆Sn₅ adjacent to the solder and Cu₃Sn IMCs adjacent to the Cu substrate, respectively. The addition of nano-TiO₂ particles to the Sn0.7Cu solder effectively repressed the growth of the IMC layer at the interface.