The kinetic H/D isotope effect in electroless copper plating. A DEMS study

DEMS studies in electroless copper plating solution were carried out using a thin-layer flow-through cell within the electrode potential range -1.0 V to 0.7 V (SHE). The effect of H/D substitution in both formaldahyde and water on the rate of anodic oxidation of formaldehyde to formate was investigated by on-line mass spectrometry in electroless copper plating solutions and in Cu(II)-free solutions under controlled electrode potential as well as under open-circuit conditions. A negligible H/D isotope effect was found in electroless copper plating solution for H2O replacement by D2O within the potential range -0.7 to -0.4 V and under open-circuit conditions. The dependence of the k(H)/k(D) value for H/D substitution in formaldehyde on the electrode potential was enhanced in electroless plating solution at low (ca. -0.6 V) anodic potentials. The rupture of the C-H bond of formaldehyde is concluded to be the rate-limiting step in anodic oxidation of formaldehyde on copper and in electroless copper plating. Copyright (C) 1996 Elsevier Science Ltd