A Study on Electroless Plating of Cobalt Alloy Films for Perpendicular Recording

An electroless plating bath for the preparation of perpendicular recording media was developed. It was found that the hcp structure of Co-P is oriented normal to the film plane with the Mn codeposition into the films. First, an ammoniacal malonate-malate bath, containing MnSO₄, was selected. Nickel was codeposited into the films in order to decrease the saturation magnetization, Ms, since low Ms is necessary to decrease the demagnetizing field. Second, effects were investigated for three factors (i.e., MnSO₄ concentration, bath pH, and NiSO₄ concentration) causing the c-axis perpendicular orientation of the film properties. Optimum plating conditions for perpendicular recording media were thus determined.