Manufacturing and Characterization of Sn-0.6Al Lead-Free Composite Solder Using Accumulative Extrusion Process

In this research, the manufacturing and characterization of a Sn-Al lead-free solder composite, reinforced with electric arc furnace dust, through an accumulative extrusion process was studied. To this end, one eutectic Sn-0.6Al solder alloy and three composite lead-free solders Sn-0.6Al/X%D (X = 0.5, 1, 1.5) were fabricated. The microstructure of the solders was investigated using x-ray diffraction (XRD) and a scanning electron microscope (SEM) equipped with an energy dispersion spectroscopy (EDS) detector. Thermal characteristics of the samples were investigated using differential scanning calorimetry (DSC). The wetting angle, density, electrical resistivity, microhardness, tensile strength and shear strength of the samples were also measured. The results of microstructural investigations indicated that the solder comprises the β-Sn phase and has a eutectic microstructure, and the increase in the number of accumulative extrusion passes results in a better, more uniform distribution of Al in the Sn matrix. The results of DSC tests showed a decrease in the melting point of the Sn-0.6Al solder alloy, which indicates successful alloying. The results showed that the contact angle of the Sn-0.6Al solder alloy with the substrate was 37° and the wetting angles of the Sn-0.6Al/X%D (X = 0.5, 1, 1.5) composite solders were 39°, 42° and 72°, respectively. Density measurements showed that, by fabrication of the Sn-0.6Al eutectic solder alloy, the density of the composite solder can be reduced by up to 18% compared to the Sn-37Pb alloy. Electrical resistivity measurements indicated that electrical resistivity of Sn-0.6Al/X%D (X = 0.5, 1, 1.5) composite solders was comparable to Sn-37Pb solder. Finally, mechanical test results showed that, by addition of 1% reinforcement particles, the microhardness, ultimate tensile strength and shear strength are improved.