Mechanistic studies on mechanism of propionic acid action in elecroless nickel plating
- 化学化工－已发表论文 
Propionic acid as an additive in electroless nickel plating will accelerate chemical deposition and raise P contents in the deposits. In this work, the action mechanism of propionic acid in the electroless plating were studied by cyclic voltammetry and infrared reflection spectroscopy. The voltammetric curves at various concentrations of propionic acid indicate that propionic acid will promote both cathodic Ni2+ reduction and anodic NaH2PO2 oxidation. According to the differences between the infrared reflection spectra of adsorbed propionic acid on Ni substrates and that of the adsorbed species when propionic acid co-exists with NaH2PO2 or NiSO4, it was proposed that the acceleration of chemical deposition was attributed to the formation of surface complexes of propionic acid with NaH2PO2 and NiSO4, respectively. Propionic acid could form intermolecular hydrogen bonds with NaH2PO2, which promotes splitting of P-H bond in the reductant and producing PHO2- intermediates, hence facilitates the oxidation of NaH2PO2. At the same time, propionic acid is coordinated with Ni2+ via its -OCO- group to form bridge complexes so as to promote NiSO4 reduction. The accelerating oxidation of NaH2PO2 in turn helps the deposition of P, as a result, P contents in the deposits increase with accelerating NaH2PO2 oxidation.