An attempt has been made to improve the quality of the solder joint prepared using Sn multilayer along with SAC305 solder paste with respect to the joints prepared using only the SAC305 solder paste. Comparative results of solder joint properties have been reported. Joint interfaces have been characterized using scanning electron microscopy, X‐ray diffraction, nanoindentation, and cyclic voltammetry (CV). Correlations between different nonlinear behaviors reflected in the microstructural, electrical, and mechanical properties of the solder joints have been established through nonlinear ultrasonic testing and fractal dimensional analysis. Experimentalresults are further modeled to establish a power‐law relationship to detect the scale‐invariant behavior of the solder joints. This power‐law scaling provides an indicator of the underlying microstructural organization and the mode of energy dissipation under mechanical loading within solder joints. Finite element analysis reveals a 46% reduction in peak von Mises stress for Sn multilayer‐induced solder joints compared to their nonlayered counterparts, suggesting their ability to withstand higher forces. CV analysis further indicates superior electrochemical stability on using Sn multilayers for making the solder joints. Sn multilayers not only refine intermetallic compound morphology at the joint interface but also contribute to better distribution of induced stress.
Char et al. (Fri,) studied this question.