KINETICS OF ELECTROLESS COPPER PLATING AND MECHANICAL-PROPERTIES OF DEPOSITS

Electroless copper films were prepared from an EDTA bath in which pH was adjusted with three kinds of alkalis (LiOH, NaOH, and KOH). Mechanical properties of the deposits and the kinetics of electroless copper plating were investigated to clarify their mutual relationship. The use of LiOH, among the alkalis tested, gave the best result for the mechanical properties. The electrochemical analysis of the electroless copper deposition based on the mixed potential theory indicates that there is an interaction between the partial anodic and cathodic reactions, which is induced by the adsorption of methylene glycol anion. The polarization technique using a quartz crystal microbalance electrode and the AC impedance method disclose that an improvement of the mechanical properties of copper films is achieved when such an interaction is eliminated by preventing the adsorption of methylene glycol anion through utilizing LiOH and surfactant such as polyethylene glycol as well as elevating the bath temperature.