Laser Beam Ultrasonic Assisted Fluxless Soldering of Ceramics Using Bi-Ag-La Solder.

The work dealt with the soldering of ceramic substrates by the application of laser beam heating using ultrasound assistance. The joints were fabricated at a laser beam power of 2 kW and ultrasound frequency of 40 kHz. The Bi11Ag₂La alloy was applied as the solder, which wetted both substrates, namely Al₂O₃ and ZrO₂. Wetting of the ZrO₂ substrate was significantly better, attaining a wetting angle of 45.5°. In the case of Al₂O₃ the wetting angle attained just 73° under the same conditions. Neither a new transition layer, nor any contact interlayer were observed on the interface in either substrate. In spite of that, the fabricated joints achieved satisfactory quality and showed no cracks or irregularities. [ABSTRACT FROM AUTHOR]