METHOD FOR CONTROLLING PLATING FILM THICKNESS OF ELECTROLESS-PLATED MAGNETIC DISK MEDIUM

摘要

PURPOSE:To suppress the variations in plating precipitation amt. by applying a negative bias on a material to be electroless-plated to determine the percipitation starting point and the plating precipitation amt. CONSTITUTION:An Al disk substrate 1 coated with an Ni-P film 2 is dipped in an electroless Ni-P plating soln., a negative bias is applied for a specified time to determine the precipitation starting point, and the thickness of the Ni-P plating film 3 is controlled to a specified value. The substrate is then dipped in an electroless Co-Ni-P plating soln., and a Co-Ni-P plating magnetic film 4 is formed by the same control as before. As a result, the coefficient of variation of the plating film thickness is reduced, and the yield is increased.