| 摘要 |
PURPOSE:To obtain a magnetic recording medium having excellent uniformity in magnetic characteristics by using cooling drum which consists of a drum body formed of copper and is plated on the outside circumferential surface thereof with chromium or two layers of nickel and chromium, disposing such drum in a vacuum vessel and performing vacuum deposition or sputtering, etc. CONSTITUTION:A cooling drum 3 onsisting of a drum 31 which is formed of copper and on which a chrome plating layer 22 is formed by chrome plating is disposed in the central part of a vacuum vessel of a vacuum deposition device and a polyester base film 4 is so set on a take-up roll 6 that the film is moved along the circumferential side face of the drum 3 from a stock roll 5 and is taken up on the take-up roll. For example, a cobalt-nickel alloy 8 is set to a vapor source 7 for a ferromagnetic material. The inside of the vessel 1 is then evacuated to a vacuum by an evacuating system and the alloy 8 in the source 7 is heated by a thermion source 9 to perform vapor deposition, thereby forming the thin ferromagnetic metallic film layer consisting of the cobalt- nickel alloy on the film 4. There is thus virtually no temp. difference of the cooling drum between the stage when the vacuum deposition is started and the stage just prior to the end thereof and the fluctuation in coercive force is decreased, by which the uniformity in the magnetic characteristic of the resulted magnetic recording medium is improved. |
