Effect of pulse current on the electrodeposition of copper from choline chloride-ethylene glycol

Deep eutectic solvents (DESs) have been considered as alternatives to classic aqueous deposition baths used at room temperature. This work describes a preliminary study about the copper deposition process from a bath based on choline chloride/ethylene glycol deep eutectic solvents. The physical properties, such as viscosity and conductivity of the bath, are compared before and after the addition of CuCl2 center dot 2H(2)O. The process kinetics during copper deposition was investigated. By optimizing the concentration of metallic salts and operating temperature, deposits with compact surfaces and small grain size were obtained. However, the process has a very limited current efficiency. Pulse plating was applied to improve the mass transport and refine grain size. In this case, an important improvement was achieved. Current efficiency (CE) increased significantly compared to the results obtained in direct current. This proves that pulse plating can be used as an effective method to reduce deposition time and costs. Surface morphology of deposits was observed by scanning electron microscopy (SEM), and compositional analysis was quantified by energy-dispersive X-ray spectroscopy (EDXS).