Preparation of perpendicular magnetic recording media by DC magnetron sputter roll-coating

Preparation of perpendicular magnetic recording media by dc magnetron sputter roll-coating is described. PET film is used as the base film of a double-sided double-magnetic-layer medium. To maximize the output, magnetic properties of both the Co-Cr layer and the underlayer are investigated under the restricted condition imposed by the low heat resistivity of PET film. By adding a small amount of N2gas during sputtering, optimum coercivity of the underlayer is obtained with a good balance between high output and low modulation. We determined that a low degree of crystal orientation in the underlayer yields a high vertical coercivity of the Co-Cr layer and that a thin Co-Cr-O intermediate layer increases the output. Two techniques for reducing the curling of the medium are also adopted. Further improvement of the media and the head/medium interface is needed because of surface degradation and insufficient durability.