The work deals with the study of interaction Cu substrate (purity 5N) and Zn4Al and Zn6Al6Ag (purity 4N) solders for higher application temperatures. Soldering was performed with power ultrasound in the air without flux application at temperature 420 °C. Acting time of ultrasonic vibration was 5 s. Soldered joints were assessed by optical light microscopy, EDX microanalysis and DSC analysis. It was found out that the melting temperatures of solders were 404.9 °C and 396.9 °C. Intermetallic layers (IM) CuZn 4 and Cu 5 Zn 8 were formed at the Cu/Zn4Al boundary. At the boundary Cu/Zn6Al6Ag there were formed AgZn 3 and Cu 5 Zn 8 IM layers. Shear strength of joint Cu/Zn4Al was 34.5 MPa and shear strength of Cu/Zn6Al6Ag was 39 MPa.

The work deals with joining of graphite with stainless steel type AISI 321 by use of active solder type Sn3Ti. Structure of active solder type Sn3Ti is composed of a tin matrix in which the Ti6Sn5 phase is uniformly precipitated and the Ti3Sn phase is non-uniformly distributed. Wettability of Sn3Ti solder was determined in 10-4 Pa vacuum, at temperatures 860, 900 and 950 °C. Wetting angle of Sn3Ti solder on graphite is reduced with increasing soldering temperature and also with prolonged dwell time at soldering temperature. Temperature exerts greater effect on reduction of wetting angle. The lowest wetting angle on graphite 23° was observed at temperature 950 °C/20 min. The lowest wetting angle, observed on steel type AISI 321, attained value 18° at temperature 860 °C/20 min. Based on the results of wettability tests, the joints of graphite with stainless steel type AISI 321 were fabricated. The reactions after soldering resulted in formation of a continuous reaction layer with 5 μm average thickness on graphite/Sn3Ti solder boundary.

This paper deals with soldering high-purity brittle, nonmetallic materials such as SiO2, Si, and C (graphite). However, these materials exert poor wettability when using tin solder. Therefore, to reduce the wetting angle, an Sn solder alloyed with active Ti element was used. At a soldering temperature of 860°C and 15 min soldering time, the wetting angle on SiO2ceramics was 30°, on silicon 42°, and on graphite 52°. All these wetting angles are below 90° and are acceptable for soldering. It has been shown that the bond in all joined materials (SiO2, Si, and C) was of a diffusion character. New intermetallic products were formed on the boundary with nonmetal, thus allowing bond formation. The shear strength of SiO2ceramics attained an average value of 17 MPa.

The work deals with joining active metals as Ti, Zr and Hf with Al2O3ceramics. The solubility of these active metals in selected Sn and In based solders was studied at a selected soldering temperature. Capability of active metals to wet Al2O3ceramics and to form a diffusion bind was ascertained. Soldering was performed with Sn, Sn5Ag, In and In30Sn solders, which were enriched by an active element from metallic substrate of the joint in soldering process. Soldering temperature in vacuum varied from 770 to 870 °C and soldering time was selected from 8 to 20 min. It was found out that the most suitable metal for active solders is Ti, because it is dissolved in Sn solder already at temperature 780 °C. Wetting of ceramic Al2O3substrate and formation of a diffusion bond was achieved already at temperature 830 °C/8 min. Diffusion bond with Zr was formed just at temperature 870 °C/20 min. and it was impossible to form a diffusion bond with Hf.

The work deals with soldering of silicon substrate with active solders designated S-Bond 220-1, 220-50 and 220-M. Soldering was performed with power ultrasound in the air without flux application at temperature 250 to 280 °C. The results of EDX analysis have shown that active elements as Ti, Ce and Mg support wetting of Si substrate and thus assure the joint formation. Strength of joints was studied by shear test. The highest strength was achieved with S-Bond 220-1 solder. The strength of joints fabricated with S-bond solders on Si substrate varied from 23 to 38 MPa.

This work deals with the effect of solder alloying with a small amount of lanthanum on joint formation with metallic and ceramic substrate. The Bi-Ag – based solder with 2 wt.% lanthanum addition and Bi solder with 2 wt.% lanthanum addition were studied. Soldering was performed by a<br />fluxless process on the air, by activation with a power ultrasound. It was found out that, during the process of ultrasonic soldering, lanthanum is distributed on the boundary, both with the copper and the ceramic substrate, which enhances the joint formation. The bond with Al₂O₃ceramics is of an adhesive character, without the formation of a new contact interlayer.

The paper deals with the study of interaction between Cu, Al substrates (purity 5N) and ZnAl4, ZnAg6Al6 zinc solders for higher application temperatures. Soldering was performed with power ultrasound in the air without flux application at temperature 420 °C. Acting time of ultrasonic vibration was 3 s and ultrasound frequency was 40 kHz. Soldered joints were assessed by optical light microscopy and EDX microanalysis. Intermetallic layers (IM) CuZn4 and Cu5Zn8 were formed at the Cu/ZnAl4 boundary. The βZn-αAl mechanical mixture was formed at the Al/ZnAl4 boundary. AgZn3 and Cu5Zn8 IM layers were formed at the Cu/ZnAg6Al6 boundary, and mechanical mixture of βZn-αAl and AgZn3 intermetallic mixture were formed at the boundary Al/ZnAg6Al6.