KINETICS OF ELECTROLESS COPPER PLATING IN THE PRESENCE OF EXCESS TRIETHANOLAMINE

The electroless copper plating rate dependence on the various ligands, such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), N,N,N',N'-tetrakis(2-hydroxypropyl)-ethylenediamine (HPA), N,N,N',N'-tetrakis(2-hydroxyethyl)-ethylenediamine (HEA), triethanolamine (TEA), and triisopropanolamine (TIPA), were examined. TEA solution plating rate was the fastest of all ligands, the maximum rate being over 20 times faster than the current rate observed in the EDTA system. In order to reveal the rate dependence on the ligand, the adsorption equilibrium constants for Cu(II)-ligand complex onto the adsorbed ligand and the maximum deposition rates were determined based on the plating model previously proposed. The dependence was explained using the ligand adsorption equilibrium constant; (K1) onto the reactive surface; (K2) onto the adsorbed complexes and (K3) the complex adsorption equilibrium constant.