EFFECTS OF HYPOPHOSPHITE CONTENTS AND SURFACE-TREATMENT ON ELECTROPLATED CO-NI-P THIN-FILMS

This article describes the effects of sodium hypophosphite (hypo) cont ent in cobalt nickel sulfate bath, and the duration of surface treatme nt prior to electroplating, on the magnetic, structural, and electrica l properties of Co-Ni-P thin films. The coercivity of the Co-Ni-P laye r can be controlled independently either by hypo content or by surface treatment. Transmission electron microscopy microstructure indicates that the width of grain boundaries of Co-Ni-P films is influenced by h ypo in the magnetic bath. The mechanism of the coercivity increase by hypo in the bath is thought to result from magnetostatic or exchange d ecoupling at phosphorus-rich grain boundaries. Effects of these factor s on media noise can be well-explained by the microstructural change o f Co-Ni-P layers.