Electrochemical behaviour of alkaline copper complexes

A search for non-cyanide plating baths for copper resulted in the developme nt of alkaline copper complex baths containing trisodium citrate [TSC] and triethanolamine [TEA]. Voltammetric studies were carried out on platinum to understand the electrochemical behaviour of these complexes. In TSC soluti ons, the deposition of copper involves the slow formation of a monovalent s pecies. Adsorption of this species obeys Langmuir isotherm. in TEA solution s the deposition involves the formation of monovalent ions obeying the non- activated Temkin isotherm. Conversion of divalent to monovalent copper is a lso slow, in TEA and TSC alkaline copper solutions, the predominant species that undergo stepwise reduction contain only TEA ligands.