In situ study of electrochemical migration of Sn3Ag0.5Cu solder reinforced by Cu6Sn5 nanoparticles

The increasing packaging density and power density have led to a drastic increase in the electric field strength between solder joints, and the accelerated movement of ions significantly rises the potential for failure of solder joints caused by electrochemical migration (ECM). To improve the anti-electrochemical migration ability of Sn3Ag0.5Cu solder (SAC305), we doped Cu6Sn5 nanoparticles (NPs) into SAC305 solder paste and studied its mechanism for inhibiting ECM. In this experiment, Cu6Sn5 NPs were prepared by ultrasound-assisted chemical reduction, and composite solder pastes were prepared by mechanically mixing Cu6Sn5 NPs with SAC305. In situ observation of the ECM between electrodes was carried out under different operating conditions. The addition of Cu6Sn5 NPs within 0.6 wt% could effectively inhibit the ECM by prolonging the incubation period. However, when the amount of Cu6Sn5 NPs exceeded 0.6 wt%, the catalytic effect of Cu6Sn5 NPs on the hydrogen evolution reaction would create vigorous convection within the droplet, which accelerated the failure by ECM. Apart from that, it was found that the addition of Cu6Sn5 NPs could increase the threshold for instantaneous failure of solder joints under high voltage.

Automated summary

The increase in packaging and power density has resulted in a higher electric field strength between solder joints and increased potential for failure due to electrochemical migration. To enhance the anti-electrochemical migration ability of SAC305 solder, Cu6Sn5 nanoparticles (NPs) were added to the paste and their mechanism for inhibiting ECM was studied. Cu6Sn5 NPs were prepared through ultrasound-assisted chemical reduction and composite solder pastes were prepared by mechanically mixing them with SAC305. In situ observation showed that adding 0.6 wt% Cu6Sn5 NPs effectively inhibited ECM by prolonging the incubation period, but exceeding this amount led to accelerated failure. Furthermore, Cu6Sn5 NPs increased the threshold for instantaneous failure under high voltage.