Shear strength and wettability of active Sn3.5Ag4Ti(Ce,Ga) solder on Al2O3 ceramics

The work deals with the study of wettability of Sn3.5Ag4Ti(Ce,Ga) solder on ceramic material of Al₂O₃. The Sn3.5Ag4Ti(Ce,Ga) solder is used for ultrasonic soldering of metallic and ceramic materials. The microstructure of Sn3.5Ag4Ti(Ce,Ga) solder consists of a tin matrix, where non-uniformly distributed constituents of partially dissolved Ti and uniformly distributed fine needles of Ag–Sn phase were observed. The solder was of heterogeneous composition. X-ray diffraction analysis has revealed the presence of following phases: Ag₃Sn, Ti₆Sn₅, Ti₃Sn. For determination of melting point, the Differential scanning calorimetry analysis (DSC) was performed. Wettability of Sn3.5Ag4Ti(Ce,Ga) solder was determined at temperatures 800, 850 and 900 °C in dependence on wetting time. The best wettability of solder Θ = 46° was achieved at 850 °C/43 min. The experiments with high-temperature activation were performed in vacuum of 10^?4 Pa. On the basis of experience attained by measurement of contact angle, the soldered joints of Al₂O₃/Al₂O₃ and Al₂O₃/metal were fabricated in conditions of high-temperature activation in vacuum at temperature 850 °C/10 min. For comparison, also the joints fabricated in the conditions of ultrasonic activation in the air at temperature 280 °C/1 min were applied. The shear strength of joints of Al₂O₃/Al₂O₃ and Al₂O₃/metal fabricated with Sn3.5Ag4Ti(Ce,Ga) solder varied from 17 to 35 MPa. The shear strength of joints fabricated in vacuum is slightly higher than in the case of joints fabricated by use of power ultrasound.