Study of Active Soldering of Al2O3 Sputtering Targets on Copper Substrates.

The work deals with the technology of joining ceramic Al2O3 targets with copper. The active solder types Sn3.5Ag4Ti(Ce, Ga), Sn2Ti, and Bi25In18Sn were analysed in this study. These solders were selected owing to their acceptable melting point and possibility of mechanical activation. The highest melting point, namely 235.8 °C, was achieved by Sn2Ti solder. The phases Ti6Sn5 and Ti3Sn were observed in this solder. In Sn3.5Ag4Ti(Ce, Ga) solder, besides the phases of the Sn-Ti system, the silver phases Ag3Sn and Ag3Ti were also observed. In Bi25In18Sn solder the phases BiIn2, In3Sn, InSn4, and BiIn were found. The shear strength of fabricated joints varied from 7 to 35 MPa. The highest strength of joints was achieved with Sn3.5Ag4Ti(Ce, Ga) solder. The lowest shear strength was attained with Bi25In18Sn solder. In the case of active solders, Ti formed a continuous layer of reaction products consisting of Ti-O systems on the joint boundary of Al2O3 ceramics. In the case of Bi25In18Sn solder, In also contributes to joint formation. The layers of reaction products alter the surface energy of ceramic substrate and allow its wetting with solder. [ABSTRACT FROM AUTHOR]