Process for producing read and/or write heads for magnetic recor

Details Process for producing read and/or write heads for magnetic recor Process for producing read and/or write heads for magnetic recor

1992-02-28

1993-10-05

Powell, William A.

Adhesive bonding and miscellaneous chemical manufacture

Delaminating processes adapted for specified product

Delaminating in preparation for post processing recycling step

29603, 156643, 156644, 156651, 156657, 1566591, 156662, H01L 21306, B44C 122, C03C 1500, C23F 100

Patent

active

052501507

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a process for producing magnetic read and/or write heads. It is mainly intended for the production of heads for general public video recording. However, it can naturally be used in other fields, such as that of computer memories.


PRIOR ART

A magnetic recording support for video equipment or for computer memories has numerous tracks on which are written informations in the form of magnetic domains.
In order to increase the recorded information quantity, there is an increase not only in the number of informations per length unit on a track, but also the number of tracks. For this purpose, the width of the tracks is reduced and the distance between the tracks is reduced until the tracks are contiguous.
In order to avoid the mixing of informations relative to two contiguous tracks, the informations are preferably written in an inclined manner on each track, the inclination (or azimuth) being opposed between succeeding tracks. The read and write head must in this case have an inclined gap, whose inclination is a function of the track to be written or read. Thus, an "azimuth" is defined for said gap as being the angle between the plane of the gap and the transverse plane of the head, which is the plane perpendicular to the general direction of the recording support.
Straight or inclined gap heads for video recording can be mechanically obtained by the straight or oblique machining of pole pieces. Such a process is more particularly described in "Recent Magnetics for Electronics", JARECT, vol. 10, chapter 11, pp 121-133, 1983, published by Y. SAKURAI, North-Holland.
However, this production process suffers from the disadvantage of not making it possible to obtain gaps with a width less than 10 microns, which significantly decreases the information density which can be read or written.
However, processes for the production of magnetic heads are known, which make it possible to obtain narrower gaps. These processes use thin film deposition and etching methods. Such a process is e.g. described in EP-A-262 028.
In these processes, the upper magnetic piece in which the gap is formed necessarily has a limited width, because it is one of the films produced. Generally this thickness is less than 5 microns. If the recording support rubs against said piece, the resulting inevitable wear will rapidly destroy the said piece.
Therefore such heads can only be used in systems where the head and recording support are not in contact with one another. Consequently they are unusable for video recording.
However, processes for the production of thin film heads are known, which obviate this disadvantage. These processes also use film deposits, but the head obtained works on the edge, so that the wear affects the largest dimension and not the thickness of the films. In this case, the recording support passes in a plane no longer parallel, but instead perpendicular to the plane of the films. Japanese Patent Abstracts, vol. 13, No. 322 (P-902-3670) of 20.7.1989 corresponding to Japanese application JP-A-1 088 909 describes such a process. According to this document, the starting product is a glass substrate, on which is deposited a conductive coating, e.g. of tungsten, followed by the formation by electrodeposition of a magnetic coating, e.g. of Fe-Ni, part of said magnetic coating is then etched to form a riser which is parallel or inclined with respect to the vertical of the substrate, then deposition takes place by sputtering of an amagnetic material coating such as SiO.sub.2, which is etched so as to only leave it on the riser, followed by the formation of a second magnetic coating using the conductive coating as the electrode and then the complete entity is planarized. This gives a magnetic piece separated by a gap corresponding to the SiO.sub.2 coating. A protective film e.g. of Al.sub.2 O.sub.3 is deposited thereon. A hole is made in the entity and a coil is formed through it and around the pole pieces.
Although satisfactory in certain respects, this process still suffers from

REFERENCES:
patent: 4875970 (1989-10-01), Takeya et al.
patent: 5104483 (1992-04-01), Takeya
IBM Technical Disclosure Bulletin, vol. 21, No. 12, May 1979, p. 5002, Armonk, US, K. E. Petersen: "Thin Film Magnetic Heads".
Patent Abstracts of Japan, vol. 11, No. 305 (P-623) (2752), Oct. 6, 1987; and JP-A-6297118 (Hitachi Ltd.) 6 May 1987.
Patent Abstracts of Japan, vol. 14, No. 158, (P-1027) (4101) Mar. 27, 1990; and JP-A-201411 (Sony Corporation) Jan. 18, 1990.
Patent Abstracts of Japan, vol. 13, No. 322 (P-902) (3670), 20 Jul. 1989; and JP A-1088909 (Toshiba Corporation) Apr. 3, 1989.

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