Orthogonal design optimization for Cu/Sn58Bi-0.4Mg/Cu solder joint strength in ultrasonic-assisted soldering

This study investigated the influence of three ultrasonic-assisted soldering process parameters, namely soldering temperature, ultrasonic duration, and ultrasonic power, on the strength of Cu/Sn58Bi-0.4Mg/Cu solder joints. A three-factor, three-level orthogonal experiment was conducted by us using an L9 (34) orthogonal design, and the research outcome was evaluated in terms of solder joints shear strength. The optimal experimental design was determined through range analysis, and the Analysis of Variance (ANOVA) was performed to assess the individual impacts of each factor on the experimental results. Furthermore, we employed scanning electron mi-croscopy (SEM) to examine the microstructures of the solder joints, investigate the progression of intermetallic compounds (IMC), and analyze the fracture surface morphology. Furthermore, we conducted essential Energy Dispersive Spectroscopy (EDS) elemental analysis to study the diffusion and distribution of elements. Finally, validation experiments were performed to compare the optimal design from the orthogonal experiment with the design derived from theoretical analysis, revealing that the latter yielded superior results. This study has identified an excellent set of parameters for ultrasonically assisted Cu/Sn58Bi-0.4Mg/Cu bonding. It offers novel insights into parameter selection for ultrasonic-assisted soldering, with potential energy conservation and efficiency improvement benefits.