AbstractsChemistry

"A novel process utilizing an organic immersion plating bath (OIPB) was developed for depositing gold films onto nickel films by a galvanic displacement reaction. The bath was prepared with poor electrically conductive organic solutions that are commonly used for the liquid-liquid extraction of metal ions from aqueous solutions. The objectives of the study were to identify bath parameters that would result in the deposition of uniform, continuous gold films. The parameters investigated included: gold concentration (0.1 to 3.0 g/L); amount of metal extractant (1.7 to 50 vol. %); type of metal extractant; type of diluent; deposition time (0.5 to 30 minutes); and deposition temperature 20 to 40ʻC). The effect various additives (HCl, H₂SO₄, KCl, water, glacial acetic acid, acetone, decanol, methanol) and sparging gases (N₂, 5%H₂/Ar forming gas, compressed air) had on the morphology of the deposited gold films was also considered. It was found that the type of metal extractant and diluent had a substantial effect on the morphology of the deposited gold film; an addition of HCl to the OIPB was required to obtain gold films composed of uniform gold particles. The deposition rate was self-limiting which is characteristic of galvanic displacement reaction. First-order reaction rate constants were determined; the reaction rate was found to be mixed chemical/diffusion controlled. characterization of the deposited gold films demonstrated that they were crystalline and composed of nanometer sized particles. Furthermore, it was found that the gold films were typically 18-35 nm thick and composed of pure metallic gold with no co-deposited nickel or carbon detected in the gold film" – Abstract, p. iii.