Synergistic effect of additives on electrodeposition of copper from cyanide-free electrolytes and its structural and morphological characteristics

Electrodeposition of acid copper plating on mild steel substrate is tedious due to the galvanic displacement reaction of copper on mild steel. This can be avoided by using a proper complexing agent, because the complexing agent tuned the potential of noble direction to less noble direction by complex formation. In this paper, environment friendly electrodeposition of copper from non-cyanide electrolyte using sodium gluconate as complexing agent was investigated in alkaline medium. The effects of additives such as 1, 2, 3-benzotriazole, sodium lauryl sulphate, PEG 8000 and saccharin were studied. These additives are found to reduce the grain size, grain boundaries and improve surface morphology of the copper deposits. Also they improve the throwing power of the depositing electrolytes and hardness of deposits. The electrodeposited copper coatings were characterized by X-ray diffraction technique. XRD results indicate that the electrodeposited copper shows polycrystalline and face centered cubic structure. The crystal size was calculated by XRD and AFM analysis. Among these additives studied, the mixture of benzotriazole and sodium lauryl sulphate acts as the best additive. A uniform pore-free surface observed under SEM and AFM results reveal the grain refining brought about by the additives.