Hydrazine is used as a reducing agent in a novel electroless gold plating formulation. Anodic polarization cuI~/es have shown that excess free cyanide, used to stabilize the gold cyanide complex, poisons hydrazine oxidation on gold but not on transition metals such as nickel and cobalt. This allows a new type of plating, "substrate-catalyzed," which is neither immersion nor autocatalytic plating. This bath plates pure gold films at high initial rates up to 10 ~m/h with exceptional bath stability and life.
Hydrazine and dimethylamine borane are used as reducing agents in a new autocatalytic electroless gold plating formulation. Measurements of the kinetics of the anodic reaction have shown unique substrate/reducing agent interactions. Combining the unique characteristics of each reducing agent with improved kinetics facilitated by the addition of carbonate and triethanolamine has resulted in a plating bath with exceptional rate and stability. This formulation can be used on a variety of substrates which are normally difficult for electro]ess gold plating.
X-ray radiography coupled with high resolution optical densitometry, as well as optical and scanning electron microscopy, was employedto study the effect of pivotal zinc deposition parameters on thezinc morphology within a porous C foam electrode. Deposition was carried out in zinc-bromine and zinc-zinc cells with circulating electrolyte. Results on the effects of flow rate, substrate thickness, current density, and electrolyte composition on zinc distribution in the substrate and on its surface are described. This study has shown that in the absence of organic inhibitors, very nonuniform zinc deposition occurs within the porous electrode. This zinc deposition corresponds to the nonuniform primary current distribution dominated by ohmic resistance. This study has led to the conclusions that high electrolyte flow rates, moderate current densities, and thick foams all aid in producing increasingly uniform zinc deposits. The most beneficial effects on the zinc morphology, however, were obtained by adding to the electrolyte a dendrite inhibitor-solubilizer combination consisting of certain fluorosurfactants and butyrolactone.
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