Influence of N-N dimethyl formamide on electroless copper plating using hypophosphite as reducing agent

The effect of N-N dimethyl formamide (DMF) on deposition rate, deposit composition, structure and morphology of electroless copper deposition obtained from hypophosphite baths was studied. The electrochemical reactions of hypophosphite (oxidation) and cupric ion (reduction) have been investigated at various concentrations of DMF. It is found that the deposition rate decreased significantly with the DMF addition and the depositsʹ color changed from dark-brown to copper-bright with improved uniformity. Indeed, SEM/EDX analysis showed that the nickel and phosphorus content in the deposits decreased slightly with DMF addition. Cyclic voltammetry and electrochemical impedance spectroscopy showed that the DMF inhibited the oxidation of hypophosphite and the reduction of cupric ions by its adsorption on metallic surface.