The aim of this study was to characterize a Zn-Mg type soldering alloy and direct soldering of SiC ceramics with a copper substrate. The Zn1.5Mg solder exerts a wider melting interval. The temperature of the eutectic reaction was 365 °C, and the liquidus temperature was 405 °C. The microstructure of the soldering alloy is comprised of a zinc matrix. Segregation of binary eutectics in the form of (Zn) + Mg₂Zn₁₁ lamellas occurred on the boundaries of Zn grains. Additionally, the presence of a MgZn₂ magnesium phase was observed in the solder matrix. The SiC/solder bond was formed due to magnesium distribution from solder to the boundary with SiC ceramics, where magnesium reacts with silicon, which is infiltered in SiC ceramics. By a mutual interaction, a new Mg₂Si phase is formed. An interaction between the molten zinc solder and Cu substrate occurred on the boundary of the Cu/substrate joint at the formation of a transition zone composed of two new phases, namely the γCu (Cu₅Zn₈) non-wettable phase type, approximately 30 µm wide, and a wettable (CuZn₄) phase type ε, approximately 12 µm wide. The average shear strength of a combined SiC/Cu joint fabricated using Zn1.5Mg solder was 44 MPa.

The aim of this study was to characterize a Sn-Ti solder alloy containing 6 wt.% SiC nanoparticles and evaluate its use for direct soldering of SiC ceramics to a copper (Cu) substrate. Soldering was performed with direct ultrasound activation. The average tensile strength of the solder alloy was 17.1 MPa. Differential Thermal Analysis (DTA) analysis revealed an apparent transition at 234 ℃, corresponding to a eutectic reaction within the Sn-Ti binary system, indicating structural changes in the solder. The solder matrix consisted primarily of pure tin, while titanium combined with SiC nanoparticles to form a TiC phase. The existence of this phase was confirmed by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analysis of the solder. The bond at the interface between the SiC ceramic substrate and the solder was formed through diffusion and chemical reactions. The XRD analysis of the fractured surface from the SiC side confirmed the formation of phases such as TiC, Ti₂Sn, CTi₂, CuSn, SiC, and Cu₆Sn₅; the TiC and CTi₂ phases resulted from the interaction of active Ti in the solder with the SiC ceramic surface. The bond at the Cu substrate interface formed due to the high solubility of tin in the solder and the formation of probable CuSnTi and CuSnTi3₅ phases, along with a mixture of Sn + η Cu₆Sn₅ solid solution. The average shear strength of the SiC/Cu joint, fabricated using SnTi3 solder with 6 wt.% SiC nanoparticles, was 21.5 MPa.

This paper examines the wettability and interactions between ceramic and composite materials soldered with Bi-based solder containing 11 wt.% of silver and 3 wt.% titanium using indirect electron beam soldering technology. The Bi11Ag3Ti solder, with a melting point of 402 °C, consisted of a bismuth matrix containing silver lamellae. Titanium, acting as an active element, positively influenced the interaction between the solder and the joined materials. SiC and Ni-SiC substrates were soldered at temperatures of 750 °C, 850 °C, and 950 °C. Measurements of wettability angles indicated that the lowest value (20°) was achieved with SiC substrates at 950 °C. A temperature of 750 °C appeared to be the least suitable for both substrates and was entirely unsuitable for Ni-SiC. It was also observed that the Bi11Ag3Ti solder wetted the SiC substrates more effectively than Ni-SiC substrates. The optimal working temperature for this solder was determined to be 950 °C. The shear strength of the joints soldered with the Bi11Ag3Ti alloy was 23.5 MPa for the Al₂O₃/Ni-SiC joint and 9 MPa for the SiC/Ni-SiC joint.

This study investigates the effect of SiC nanoparticle addition on the microstructure, interfacial reactions, and mechanical properties of Zn5Al3Ti active solder used for ultrasonic soldering of AlN ceramic to copper substrates. Composite solders containing 3 and 6 wt.% SiC nanoparticles were prepared and applied under flux-free ultrasonic soldering conditions. The solder alloys were evaluated by tensile testing, while the soldered joints were evaluated by shear strength testing. The solder microstructure and interfacial regions were characterized using SEM/EDS analysis. The results showed that the addition of SiC nanoparticles modified the microstructure of the Zn5Al3Ti solder and influenced the mechanical performance of the ceramic/metal joints. Among the investigated systems, the AlN/Zn5Al3Ti + 6 wt.% SiC/Cu joint exhibited the highest shear strength, reaching approximately 101 MPa. SEM/EDS observations revealed the formation of compact multilayered interfacial regions, including possible Cu–Zn intermetallic phases at the Cu/solder interface and Al–Ti–Zn-based reaction products near the solder/AlN interface. The improved joint performance may be attributed to the combined effect of SiC-induced microstructural modification, the presence of Si-containing particles, and the formation of compact metallurgical bonds. The results indicate that Zn5Al3Ti solder modified with 6 wt.% SiC nanoparticles is a promising material for producing strong AlN/Cu joints under the applied ultrasonic soldering conditions.

The reactive soldering of silicon-carbide (SiC) ceramics to a Ni-SiC composite was investigated using an Sn-5Sb-3Ti active solder and electron-beam heating at 750 °C, 850 °C and 950 °C. Wettability: The average contact angle decreased from 94 ± 4° (750 °C) to 60 ± 3° (850 °C) and further to 24 ± 2° (950 °C), demonstrating progressively improved spreading of the filler with increasing temperature. Interfacial reactions: Continuous layers of Ni₃(Sn,Sb)₄ and Ti₆(Sn,Sb)₅ formed along the Ni-SiC/filler interface, the latter confirming Ti diffusion that activates the wetting of the composite surface. Mechanical performance: Shear-lap tests on three joints per condition yielded 39 ± 6 MPa (750 °C), 27 ± 2 MPa (850 °C) and 36 ± 15 MPa (950 °C). The highest and lowest individual values at 950 °C were 51 MPa and 21 MPa, respectively. These results show that a higher soldering temperature lowers the contact angle and promotes interfacial reaction, but only a moderate improvement in average joint strength is obtained. These findings demonstrate a flux-free route to bond SiC ceramics with Ni-SiC composites, which is highly relevant for next-generation power-electronics modules and other high-temperature applications.