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Plasma Deposition Technology for Magnetic Recording Thin-Film Media

Objective

The objective was to exploit the potential advantages of a significant increase in recording capacity when metallic thin films, instead of conventional oxide particles, are used as the basis for magnetic recording media. In order to develop such a technology, the interdependence of substrate materials, thin magnetic layers, overcoats, heads and drive systems need to be assessed, developed and produced accordingly.
LeyboldHeraeus was responsible for the development of various deposition methods, eg sputtering, evaporation and plasmaCVD for the magnetic layer, while the definition of the quality standards of the disks and their possible implementation into a disk drive system was entrusted, from October1987, to SAGEM, which was also responsible of the evaluation of differently prepared media.
The objective was to exploit the potential advantages of a significant increase in recording capacity when metallic thin films, instead of conventional oxide particles, are used as the basis for magnetic recording media. In order to develop such a technology, the interdependence of substrate materials, thin magnetic layers, overcoats, heads and drive systems need to be assessed, developed and produced accordingly.

Among the different deposition methods, sputtering has reached the most advanced status. A sputtering system, suitable for the study of production conditions, has been designed and built. The machine is a vertical inline system for double sided disk coating and provides the best conditions for continuous production and for a high disk quality with a minimum risk of defects.

Special emphasis has been put on carbon overcoating for mechanical and chemical protection of the recording layer. Complete layer systems were deposited, both in the above mentioned machine on hard disks and in a large roll coater on foils for the industrial production of floppy disks, with promising results.

The work has been focused on hard discs for longitudinal recording and on protective and lubricating layers for use in Winchester drives. The new thin film production technologies developed during these studies can now be used in a future production line, based on the new equipment now available, with the quality and reproducibility needed to market the discs.
Among the different deposition methods, sputtering has reached the most advanced status. At LeyboldHeraeus a sputtering system, suitable for the study of production conditions, has been designed and built. The machine is a vertical in-line system for dou blesided disk coating and provides the best conditions for continuous production and for a high disk quality with a minimum risk of defects. The process technology for the fabrication of disks with longitudinal recording has developed so far that the qua lity can compete with other good quality disks available on the market, but the maximum storage capacity is still expected to be achieved by vertical recording.
Special emphasis has also been put on carbon overcoating for mechanical and chemical protection of the recording layer. Complete layer systems were deposited, both in the above-mentioned machine on hard disks and in a large roll coater on foils for the industrial production of floppy disks, with promising results.
Media studies by the partners clearly demonstrate the potential advantage (a substantial increase in recording capacity) of thin magnetic layers over conventional oxide particles for high-density recording. However, the switchover to thin-film media requ ires many modifications of the standard production technology.
Tribological problems between heads and disc still remain drawbacks in vertical recording. The strong involvement of heads manufacturers is necessary to overcome these problems and to define the needed standard heads and the consequent media characteristics. Accordingly, the work has been focused on hard discs for longitudinal recording and on protective and lubricating layers for use in Winchester drives. The new thin-film production technologies developed during these studies can now be used in a futureproduction line, based on the new equipment now available, with the quality and reproducibility needed to market the discs.

Coordinator

LEYBOLD HERAEUS GMBH
Address
Siemensstrasse 100
8755 Alzenau
Germany

Participants (2)

BASF AG
Germany
Address
Carl-bosch-straße 38
67056 Ludwigshafen
Société d'Applications Générales d'Électricité et de Mécanique
France
Address
6 Avenue D'iena
75783 Paris