Enhancing Sn-40Bi solder alloys with CuO nanoparticles: a comprehensive study of microstructure, corrosion resistance, thermal, and mechanical properties

Abstract This study investigates thes structural, mechanical, thermal, electrical, wettability, and corrosion properties of Sn-40Bi-xCuO (x = 0, 0.2, 0.4, 0.6, 0.8, and 1 wt%) solder alloys, reinforced with CuO nanoparticles (NPs).X-ray diffraction (XRD) and scanning electron microscopy (SEM). Transmission electron microscopy (sTEM) was used to identify CuO (NPs). Differential scanning calorimetry (DSC) was used to examine thermal parameters. Elastic factors, including toughness (T), yield strength (Y), Young’s modulus (E), and tensile strength (S), were investigated using the tensile test machine. Vickers microhardness tester was used to test the hardness and creep resistance. Wettability characteristics were measured using the Sessile Drop Method (SDM). X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirm that CuO NPs serve as effective nucleation sites, refining the microstructure and facilitating the formation of SnBi intermetallic compounds (IMCs). Differential scanning calorimetry (DSC) results showed a slight decrease in the melting point with increasing CuO nanoparticle content. Specifically, the melting temperature was reduced to 143.7 ℃ with the addition of 0.2 wt% CuO. This reduction enhances the alloy’s suitability for low-temperature soldering applications and indicates improved thermal stability. Mechanical testing reveals a significant improvement where the optimal composition, Sn-40Bi-1CuO, exhibited the highest ultimate tensile strength (77.91 MPa), elastic modulus (230.03 GPa) and maximum microhardness (21.65 gmf/mm 2 ), indicating improved creep resistance and mechanical stability. Furthermore, electrochemical corrosion studies suggest that the addition of CuO nanoparticles enhances corrosion resistance by refining the grain structure and promoting the formation of a stable passive layer. The tests revealed a notable improvement in corrosion behavior, with the Sn-40Bi-1CuO alloy exhibiting the lowest corrosion rate of 0.0028 mm/y. These findings indicate the alloy’s potential for reliable performance in aggressive corrosive environments. Wettability analysis demonstrates a reduction in contact angle, indicating superior solderability. Additionally, electrical resistivity measurements indicated a slight increase with higher CuO content, attributed to increased electron scattering within the solder matrix. These findings highlight the potential of Sn-40Bi-xCuO soslder alloys as promising candidates for next-generation green electronics, offering an optimal balance between mechanical robustness, thermal performance, and environmental sustainability.