Bonding mechanism in ultrasonic-assisted soldering of ZrO2 and 304 stainless steel using a micro-alloyed active solder alloy

Ceramic-metal soldering joints are widely needed in various industries and a key factor in soldering is the interfacial bonding between the ceramic and solder alloys. Active elements, such as Ti and rare earth, are often added to solder alloys to realize interfacial bonding. The content of the active elements is usually 2 ~ 4 wt%, which can significantly increase the melting temperature of the solder alloys. In this research, a micro-alloyed reactive solder comprising Sn-3.0Ag-0.5Cu alloy with 0.2 wt% Ti was used to solder ZrO2 ceramics and 304 stainless steel. The effective interfacial reaction was achieved with the aid of the ultrasound. The reaction product was Zr0.5Ti0.35Sn0.15O2 and Ti11.3Sn3O10 at the Sn-Ag-Cu-Ti/ZrO2 interface, and the maximum shear strength of the soldered specimens was 30.75 +/- 9.92 Mpa. The melting temperature of the soldering alloy was not significantly increased compared to regular Sn-Ag-Cu solder alloy.

Automated summary

Active element soldering technology can achieve effective bonding between ceramics and metals, but the addition of active elements often results in an increase in the melting point of the solder alloys. In this study, a micro-alloyed reactive solder and ultrasound assistance were used to successfully achieve effective interfacial reaction in soldering ZrO2 ceramics and 304 stainless steel.