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Browse Prior Art Database

Producing High Coercivity Vacuum Deposited Magnetic Tapes

IP.com Disclosure Number: IPCOM000095188D
Original Publication Date: 1965-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Bickert, FG: AUTHOR [+2]

Abstract

The magnetic coercivity of vacuum deposited magnetic tape can be controlled by the angle of incidence of the vacuum deposited material. Coercivity increases as the angle of incidence from the normal of the substrate increases. As a practical matter, due to the large area of deposition, high-angle deposition upon a continuously moving tape requires relatively slow tape speeds to achieve desired thickness. However, if high-angle deposition upon a relatively fast moving tape is followed by deposition of a second layer at a lower angle while the tape is moving at a relatively high speed, the resulting magnetic film exhibits the high coercivity which is characteristic of high-angle deposition.

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Producing High Coercivity Vacuum Deposited Magnetic Tapes

The magnetic coercivity of vacuum deposited magnetic tape can be controlled by the angle of incidence of the vacuum deposited material. Coercivity increases as the angle of incidence from the normal of the substrate increases. As a practical matter, due to the large area of deposition, high-angle deposition upon a continuously moving tape requires relatively slow tape speeds to achieve desired thickness. However, if high-angle deposition upon a relatively fast moving tape is followed by deposition of a second layer at a lower angle while the tape is moving at a relatively high speed, the resulting magnetic film exhibits the high coercivity which is characteristic of high-angle deposition. For example, if cobalt is vacuum deposited at an angle of incidence of 85 degrees with the normal to the plane of the substrate and subsequently coated with cobalt at an angle of incidence of 60 degrees with the normal to the plane of the substrate, the resulting coercivity is substantially higher than is expected from deposition at the 60 degrees angle alone.

The drawing shows one arrangement of a mechanism utilized for producing high coercivity vacuum deposited magnetic recording tape. A body of ferromagnetic metal is heated in vessel 2 to a temperature sufficiently high to volatilize the metal within the vacuum evacuated chamber 4. The evaporated metal is directed and condensed onto a suitable substrate such as continu...