Solid State ion conductors are sucessfully employed in chemical sensors for gases such as oxygen for process control and environmental protection. The application requires elevated temperatures for sufficiently high ionic conductivity and is restricted to a few gases for which suitable solid electrolytes are available.
The effect of citric-acid surface modification on the bond strength of the solid-state bonded interface of tin and copper has been investigated by SEM observation of the interfacial microstructures and fractured surfaces. Citric-acid surface modification was carried out in a vacuum chamber at a bonding temperature of 383–473 K and a bonding pressure of 7 MPa (bonding time: 1800 s). The citric-acid surface modification decreased bonding temperature by 70 K at which bonded joints could be obtained and bond strength comparable with the base metal was achieved.