(140d) A Multifaceted Experimental Design Investigation of Nodule Formation In Electroformed Parts In Compact Disc Plating Operations

A multifaceted experimental design combining chemical mixture and operational parameters was developed to identify the factors affecting nodule formation in electroformed parts in compact disc plating operations.  The mixture variables investigated were the bath wetting agent (surface tension reducer), bromide salt (anode corrosion) and grain refiner (stress reducer) concentrations. The anode nickel level and plating head rotational speed were the operating variables studied. A disc quality score to account for and quantify nodule size and location was developed, and optimal operating parameters and bath mixture concentrations were identified.  The analysis indicated that high level interactions among mixture variables and operating parameters have a significant effect on the disc quality score. All plating bath components and, to a lesser extent, rotational speed had a significant effect on disc quality for the variable ranges investigated.  The concentrations of wetting agent and stress reducer in the plating bath had the most significant impact on nodule formation. The location of the nodules on the disc was not influenced by plating bath or operating variables.