In this study, the electric spark discharge method was used to prepare a cuprous iodide nanocolloid (CuINC); specifically, an electrical discharge machine was used to prepare a CuINC under five sets of pulse width modulation (Ton-Toff) parameters, and ultraviolet-visible spectrophotometry and a zetasizer were used to evaluate the most suitable parameter set. Copper wires were used as electrodes (copper content = 99.7%, diameter = 1 mm), and deionized water mixed with iodine was used as the dielectric fluid. The analysis results indicated that the CuINC prepared under Ton-Toff = 10-10 ls had absorbance of 1.8 and a zeta potential of -31.9 mV. The resultant CuINC had the highest concentration and suspension stability; this indicated that Ton-Toff = 10-10 ls is the most suitable parameter combination for preparing a CuINC. X-ray diffraction revealed a complete CuI crystal structure. Transmission electron microscopy images showed that most of the CuI nanoparticles were smaller than 5 nm and that the nanoparticles were evenly dispersed. The electricdischarge-based production process employed in this study is rapid and simple, and the end products have favorable suspension power. The method is a safe, environmentally friendly, and rapid method of preparing CuINCs.

Enhanced solder wettability (SW) of oxidized-Cu (OC) with 96.5Sn-3Ag-0.5Cu lead-free solder (LFS) by Ar-H 2 plasmas was investigated. The SW of OC was significantly improved from 0% wetting of Cu oxidized in air at 260°C for 1 h to 100% wetting of OC modified by Ar-H 2 plasmas for 10 min. The SW of Cu was found to be highly dependent on the surface characteristics of Cu. By decreasing the total surface energy (TSE), decreasing the polar surface energy (PSE), and increasing the dispersive surface energy (DSE) on the surfaces of OC modified by Ar-H 2 plasmas, the SW with LFS improves. X-ray photoelectron spectroscopy (XPS) indicates that Ar-H 2 plasma treatment is used to remove the copper oxides CuO and Cu 2 O from the OC surfaces. The ratio of the total amount of Cu 2 O to CuO was found to be a good indication of how the copper oxides CuO and Cu 2 O affect the PSE, DSE, and SW of Cu.