Wide pH Range Electroless Copper Deposition at Room Temperature EQCM and CV Study of Autocatalytic Copper(II) Reduction by Cobalt(II)-Pentaethylenehexamine Complexes

Abstract

Co(II) complex with pentaethylenehexamine was found to be an effective reducing agent in the autocatalytic reduction of Cu(II) to metal (electroless copper plating). Cyclic voltammetry and electrochemical quartz crystal microgravimetry were used to study the autocatalytic Cu(II) reduction by Co(II) in pentaethylenehexamine solutions. Electroless copper plating was studied by measuring the instantaneous copper deposition rate, open-circuit potential and electrochemical parameters of the partial reactions. It was determined that the electrochemically active and easily oxidizable Co(II) complexes with pentaethylenehexamine are formed in a wide solution pH range, from acidic (pH 4.4) to alkaline (pH 9.5) medium. The maximum copper deposition rate at 20 oC was obtained at pH about 5 and is equal to 55.1 µg cm-2/2 min.