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Process for Producing Magnetic Layers

IP.com Disclosure Number: IPCOM000062672D
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 3 page(s) / 43K

Publishing Venue

IBM

Related People

Bandara, U: AUTHOR [+3]

Abstract

A process is described for producing magnetic layers for storage means with uniformly aligned magnetic particles. Magnetic disks are produced by applying a suspension of hard-magnetic elliptical particles in the form of a very thin layer to an aluminum substrate. For a high signal strength and a high bit density, the previously unoriented particles have to be aligned along the circumference of the disk. For that purpose, orientation magnets with a horseshoe-shaped cross-section and a narrow gap are used. By means of these orientation magnets, a high magnetic field is generated within the gap along the circumference of the disk. By turning the disk, while the magnetic field is being applied, the particles on the entire disk are oriented.

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Process for Producing Magnetic Layers

A process is described for producing magnetic layers for storage means with uniformly aligned magnetic particles. Magnetic disks are produced by applying a suspension of hard-magnetic elliptical particles in the form of a very thin layer to an aluminum substrate. For a high signal strength and a high bit density, the previously unoriented particles have to be aligned along the circumference of the disk. For that purpose, orientation magnets with a horseshoe-shaped cross-section and a narrow gap are used. By means of these orientation magnets, a high magnetic field is generated within the gap along the circumference of the disk. By turning the disk, while the magnetic field is being applied, the particles on the entire disk are oriented. As the particles must be mobile for orientation, that step is effected while the viscosity of the magnetic layer is still very high. However, in practice, the mobility of the particles has two undesirable side effects. The actual field, to which a single particle is exposed when passing the orientation field, also comprises elements in its peripheral regions which are opposed to the orienting field, so that part of the previously oriented particles will again be disoriented. The high strength of the orientation field also leads to a chaining of the magnetic particles, which, after several passes, causes "windrows" along the disk circumference. Such "windrows" may lead to head stiction when the disk starts rotating and to missing bits at high storage densities. To avoid those disadvantages, the organic binder is replaced, at least partly, by a binder that is cured during exposure, and by exposing only a narrow region in the center of the magnetic field, thus excluding the influence of the peripheral regions of the magnetic field. This manufacturing process will be desc...