Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
1999-07-13
2001-12-11
Resan, Stevan A. (Department: 1773)
Stock material or miscellaneous articles
Composite
Of inorganic material
C360S125330, C360S125330, C360S313000
Reexamination Certificate
active
06329087
ABSTRACT:
BACKGROUND OF THE INVENTION AND DESCRIPTION OF THE PRIOR ART
The present invention relates to a wafer for use in a magnetic head capable of reading and writing on a magnetic medium, and to a magnetic head produced from such a wafer. More particularly, the present invention relates a wafer for a magnetic head, which is excellent in heat transferring property, so that the temperature is less risen during reading or writing, and to a magnetic head produced from such a wafer.
In such a conventional type of a magnetic head, thin magnetic films such as an insulating layer, a magnetic shield film, a bottom pole and a top pole; an MR element; a gap layer; a coil layer and an overcoat are formed on a surface of a substrate formed of, for example, an alumina-titanium carbide and the like.
The insulating films such as the insulating layer, the gap layer and the overcoat are usually formed of alumina.
With the above conventional magnetic head, the insulating films such as the insulating layer, the gap layer and the overcoat are formed of alumina, as described above. Therefore, the conventional magnetic head suffers from problems of a lower heat conductivity, a poor heat transferring property and an instability of the characteristic of the magnetic head due to a temperature rise. Particularly, when the magnetic head includes an MR element, there is a disadvantage that the temperature rise is significant, whereby the motion of the MR element is unstable, because the MR element is a reading element. Another problem is that because the insulating layer is formed of alumina, when the surface of the magnetic head is polished at a finishing step, only the alumina material is polished in a larger amount to produce a difference in level, for a reason that the alumina material is softer than another material. As a result, the gap between a medium and a recording/regenerating element is widened, thereby causing a reduction in output. Further, the conventional magnetic head has a disadvantage that it is poor in water resistance.
OBJECT AND SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a wafer for a magnetic head, and to a magnetic head, which has an excellent heat-transferring property, in which the instability of the magnetic head characteristic due to a temperature rise is not caused, and a reduction in output due to the polishing at the finishing step cannot be produced, and which is excellent in water resistance.
The present inventors have made zealous studies to solve the above problems and as a result, they have found that the above problems can be solved by using a film composition represented by a formula, Al—N
(1−x)
—O
x
(wherein, 0.3≦×≦0.6), in place of alumina conventionally used for the insulating film such as the insulating layer, the gap layer, the overcoat and the like provided on the substrate.
To achieve the above object, according to a first aspect of the present invention, there is provided a wafer for a magnetic head, comprising a wafer substrate, and an insulating layer provided on the wafer substrate and formed of a film composition represented by a formula, Al—N
(1−x)
—O
x
, wherein 0.05≦×≦0.8.
According to a second aspect of the present invention, in addition to the first aspect, the wafer substrate is alumina-titanium carbide.
According to a third aspect of the present invention, there is provided a wafer for a magnetic head, comprising a wafer substrate, and an insulating layer provided on the wafer substrate ad formed of a film composition represented by a formula, Al—N
(1−x)
—O
x
, wherein 0.3≦×≦0.6.
According to a fourth aspect of the present invention, in addition to the third aspect, the wafer substrate is alumina-titanium carbide.
According to a fifth aspect of the present invention, there is provided a magnetic head, comprising a magnetic head substrate, and an insulating layer provided on said magnetic head substrate and formed of a film composition represented by a formula, Al—N
(1−x)
—O
x
, wherein 0.05≦×≦0.8.
According to a sixth aspect of the present invention, in addition to the fifth aspect, the magnetic head further includes an MR element, and a gap film provided in the proximity to the MR element and formed of a film composition represented by a formula, Al—N
(1−x)
—O
x
, wherein 0.05≦×≦0.8.
According to a seventh aspect of the present invention, in addition to the sixth aspect, the magnetic head further includes an overcoat formed of a film composition represented by a formula, Al—N
(1−x)
—O
x
, wherein 0.05≦×≦0.8.
According to an eighth aspect of the present invention, in addition to the seventh aspect, the substrate is alumina-titanium carbide.
According to a ninth aspect of the present invention, there is provided a magnetic head, comprising a magnetic head substrate, and an insulating layer provided on the magnetic head substrate and formed of a film composition represented by a formula, Al—N
(1−x)
—O
x
, wherein 0.3≦×≦0.6.
According to a tenth aspect of the present invention, in addition to the ninth aspect, the magnetic head further includes an MR element, and a gap film provided in the proximity to the MR element and comprised of a film composition represented by a formula, Al—N
(1−x)
—O
x
, wherein 0.3≦×≦0.6.
According to an eleventh aspect of the present invention, in addition to the tenth aspect, the magnetic head further includes an overcoat formed of a film composition represented by a formula, Al—N
(1−x)
—O
x
wherein 0.3≦×≦0.6.
According to a twelfth aspect of the present invention, in addition to the eleventh aspect, the substrate is alumina-titanium carbide.
As described above, by using a film composition represented by a formula, Al—N
(1−x)
—O
x
, wherein 0.05≦×≦0.8, in place of the conventionally used alumina, for an insulating film such as an insulating layer, a gap layer, an overcoat and the like provided on a substrate, a wafer for a magnetic head as well as a magnetic head excellent in heat transferring property. In this magnetic head, the instability of the magnetic head characteristic due to a temperature rise is not caused, and a reduction in output due to a larger gap between the magnetic head and a medium cannot be produced by a difference in film level due to due to the polishing at a finishing step. Further, the magnetic head is also excellent in water resistance.
Particularly, by using a film composition represented by a formula, Al—N
(1−x)
—O
x
, wherein 0.3≦×≦0.6, a wafer for a magnetic head as well as a magnetic head can be produced which can reconcile a smaller difference in film level and a higher heat conductivity and a higher voltage resistance.
The insulating layer may be provided on the wafer substrate or on the magnetic head substrate directly or with an alumina sputtered layer interposed therebetween.
REFERENCES:
patent: 4861671 (1989-08-01), Muchnik et al.
patent: 4901179 (1990-02-01), Satomi et al.
patent: 1-150215 (1989-06-01), None
Armstrong, Westerman Hattori, McLeland & Naughton
Resan Stevan A.
Sumitomo Special Metals Co. Ltd.
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