Dynamic magnetic information storage or retrieval – Head – Core
Patent
1990-11-20
1992-11-10
Tupper, Robert S.
Dynamic magnetic information storage or retrieval
Head
Core
360120, 360127, 29603, G11B 531, G11B 523
Patent
active
051629607
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic head which is mounted on a magnetic recording/playback device such as a video tape recorder, a floppy disc drive device, or a hard disc drive device, etc.
In a so-called composite type magnetic head in which an oxide material such as Mn-Zn ferrite or ceramics and a magnetic thin metal film are made in composite fashion, a junction or bonding of the oxide material with the magnetic thin metal film may be required in the manufacturing process thereof. For example, in a magnetic head in which the magnetic thin metal film is made composite in a direction perpendicular to a gap portion, it is necessary to bond another oxide substrate to an oxide substrate on which a magnetic thin metal film is formed so that both the substrates sandwich the magnetic thin metal film therebetween. Alternatively, an oxide substrate is bonded to both sides of a magnetic thin metal film which is made into a thin strip.
Fusion glass having a high melting point is used for carrying out the above mentioned bonding of an oxide substrate and a magnetic thin metal film, unless a problem occurs. This is because the high melting point glass has advantages that such glass can be washed with organic solvent since it is chemically stable and strong bonding can be obtained.
However, it is necessary to elevate the fusing temperature not less than 550.degree. C. for carrying out bonding with glass having a high melting point. Accordingly, distortion due to thermal expansion may be caused in ferrite or magnetic thin metal film and the influence by the distortion may induce cracking in a magnetic core, resulting in deterioration of magnetic characteristics.
When the magnetic thin metal film is formed of a ferromagnetic amorphous metallic alloy, a so-called amorphous alloy, the fusing temperature is generally not less than the crystallization temperature (crystallization temperature is generally 400.degree. C. to 500.degree. C.). Accordingly, crystallization of the amorphous alloy deteriorates soft magnetic characteristics. If the oxide substrate is bonded to the magnetic thin metal film with a high melting point glass, the glass and the magnetic thin metal film, or the oxide substrate and the magnetic thin metal film, effect an oxidation-reduction reaction at the interface therebetween so that a region at which the permeability is remarkably lowered results, that is, a reaction layer may be formed.
If the above mentioned problems occur, a low temperature bonding agent such as a fusing glass having a low melting point, water glass or organic adhesive agent is used to bond the oxide substrate to the magnetic thin metal film. However, if the above mentioned low temperature bonding agent is used for bonding the oxide magnetic material to the magnetic thin metal film, the low temperature bonding agent has a disadvantage that it is inferior to the high melting point glass in bonding strength, weather resistance, wear resistance, surface characteristics and precision of thickness of the bonding layer.
On the other hand, it is said that bonding with high melting point glass which is chemically stable and high in bonding strength as is similar to bonding between the oxide substrate and the magnetic thin metal film in the above mentioned composite type magnetic head is preferable to bond the magnetic cores themselves at a gap therebetween in a magnetic head formed of oxide magnetic material such as Mn-Zn ferrite or a magnetic head in which the oxide magnetic material and the magnetic thin metal film are made composite. Particularly, this tendency is strong in a magnetic head which is mounted on a magnetic recording/playback device such as a video tape recorder since such a magnetic head requires durability.
However, if magnetic cores in which the oxide magnetic material such as ferrite is made composite, the magnetic thin metal films are bonded with each other with glass, and a reaction layer may be formed. If the interface between the ferrite and the magnetic thin metal film is formed
REFERENCES:
patent: 3412455 (1968-11-01), Bronnes et al.
patent: 4048714 (1977-09-01), Huntt
patent: 4172318 (1979-10-01), Huntt
patent: 4887177 (1989-12-01), Sillen
Eguchi Hiroya
Ikeda Toshito
Karamon Hideaki
Kumura Tatsuo
Matsuyama Hideaki
Sony Corporation
Tupper Robert S.
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