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The work aims to study the direct bonding of silicon substrate with solders type Sn-Ag-Ti.

During the bonding process with ultrasound assistance, the active element (Ti,Ce,Mg) is distributed from the solder to interface with a silicon substrate, where it supports the bond formation.

Formation of a reaction layer, 1-2 μm in thickness, was observed. The new Si2Ti phases and Mg2Si phase were identified in the reaction layer.

The results of analysis suggest that the Si/Sn-Ag-Ti joint is of diffusion character. The highest average strength on silicon substrate (39 MPa) was achieved with Sn-Ag-Ti(Mg) solder.

This paper aims to investigate the effect of solder alloying with a small amount of La and Y on bond formation with the Si and Cu substrates.

Bi₂La and Bi₂Y solders were studied. Soldering was performed using a fluxless method in air and with ultrasonic activation.

It was found that in the process of ultrasonic soldering, the La and Y were distributed at the interface with Si and Cu substrates, which enhanced the bond formation. Addition of La or Y elements in a Bi-based solder also ensured wetting of non-metallic materials such as Si, Al₂O₃ and SiC ceramics.

The addition of lanthanides offers a method for ensuring wetting of non-metallic materials. The bond with Si was of an adhesive character without the formation of a new contact interlayer. This resulted in lower shear strength of the bond with Si (8-10 MPa). The shear strength of the bond with a Cu substrate was 22-30 MPa.