Influence of Cu nanoparticles on Cu6Sn5 growth behavior at the interface of Sn/Cu solder joints

With nanoparticles (NPs) for enhancement the reliability of solder joints and interconnections is a trending research arena. In this study, Cu NPs prepared by chemical reduction method, were doped into flux and disseminated to the pure Sn solder (initial diameter of 1.4 mm) and iterfaces during reflow at 250 °C for 30 s and 90 s. For the experiment, the solder corresponding to flux without NPs content was observed to have the bigger thickness of Cu
₆
Sn
₅
layer, compare with the specimen treated with flux with nanoparticles. The presence of Cu NPs was observed to hinder the IMC growth. Upon cooling, the oxides formed by Cu NPs altered the screw-dislocation driven growth of prismatic IMCs and thus produced Cu
₆
Sn
₅
rods with tapered ends. In the sector of microelectronic packaging materials design, the technique of doping the flux with Cu nanoparticles can be utilized to optimally tailor the interfacial IMC layer microstructure and the thickness.