Dynamic magnetic information storage or retrieval – Head – Core
Reexamination Certificate
2000-03-31
2002-07-02
Cao, Allen (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Core
Reexamination Certificate
active
06414818
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic head used in magnetic recording/reproduction, and a magnetic disk apparatus on which this magnetic head is mounted.
FIG. 1
schematically shows recording/reproduction by a magnetic head.
As shown in
FIG. 1
, a magnetic head
10
has a substrate
1
, and a lower protective layer
2
, lower magnetic pole layer
3
, magnetic gap layer
4
, lower insulating layer
5
, coil
6
, upper insulating layer
7
, upper magnetic pole layer
8
, and upper protective layer
9
, that are formed in this order on the substrate
1
. The upper magnetic pole layer
8
is formed to extend from that surface of the upper insulating layer
7
, which faces a disk
11
, i.e., from an air bearing surface (to be referred to as ABS hereinafter)
12
, to near the center of the coil
6
. The upper protective layer
9
is formed on the upper insulating layer
7
, upper magnetic pole layer
8
, lower magnetic pole layer
3
, and the like.
This magnetic head
10
has its ABS
12
facing the surface of the rotating disk
11
, as shown in FIG.
1
. The magnetic head
10
records/reproduces while it flies above the disk
11
through a gap having a minimum flying amount h, as shown in
FIG. 1
, with a dynamic pressure generated between the rotating disk
11
and ABS
12
.
The insulating layers
5
and
7
are made of a resin such as a photoresist, and its thermal expansion coefficient is generally about an order of magnitude larger than that of a metal or aluminum oxide as the material of the surrounding portion. Copper which forms the coil
6
has a thermal expansion coefficient of 16.5×10
−6
, the insulating material which covers the coil
6
has a thermal expansion coefficient of, e.g., 70×10
−6
, and aluminum oxide which covers the resultant structure has a thermal expansion coefficient of, e.g., 5.3×10
−6
. Hence, the thermal expansion coefficients of copper and the insulating material are larger than that of aluminum oxide. Also, the coil
6
is made of copper, and its thermal expansion coefficient is accordingly several times that of aluminum oxide which forms the lower and upper protective layers
2
and
9
. Therefore, when the temperature increases, the volumes of the insulating layers
5
and
7
and coil
6
become larger than that of the surrounding aluminum oxide portion due to a difference in thermal expansion coefficient, and the magnetic head
10
deforms accordingly.
FIG. 2
schematically shows deformation of the head. As shown in
FIG. 2
, the insulating layers
5
and
7
and coil
6
having large thermal expansion coefficients are located closer to the ABS
12
in the direction of thickness of the head, so that they deform more largely on the ABS side.
FIG. 3
is a graph obtained by plotting the amount of displacement that occurs when the head deforms such that the position of A changes to a position A′ in
FIG. 2
with respect to the position of B upon changing the ambient temperature of the head.
FIG. 2
reveals that this head has a deformation of about 1 nm/10° C. at the position A.
When such a deformation occurs, the minimum flying height decreases. When the flying height decreases in the future, the danger of crash or an increase of thermal asperity (TA) may occur to decrease the reliability. Particularly, in a situation where the temperature can increase as in a vehicle, this problem is serious.
BRIEF SUMMARY OF THE INVENTION
It is the first object of the present invention to provide a magnetic head in which, when the temperature increases, a deformation, which can induce a decrease in flying height, an increase in the danger of crash, and an increase in TA on the part of a magnetic head apparatus, does not occur on the ABS side.
It is the second object of the present invention to provide a highly reliable magnetic disk apparatus in which deformation of the magnetic head on the ABS side accompanying a temperature rise is prevented so that a decrease in flying height, an increase in danger of crash, and an increase in TA do not occur.
According to the first aspect of the present invention, there is provided a magnetic head having a lower protective layer, a lower magnetic pole layer formed on the lower protective layer, a magnetic gap layer formed on the lower magnetic pole layer, a lower insulating layer formed on the magnetic gap layer, a coil formed on the lower insulating layer, an upper insulating layer formed on the coil, an upper magnetic pole layer formed on the upper insulating layer, and an upper protective layer formed on the upper magnetic pole layer, at least the upper insulating layer, of the upper and lower insulating layers, being made of a resin having a glass transition temperature of 70° C. to 100° C.
According to the second aspect of the present invention, there is provided a magnetic head having a lower protective layer, a lower magnetic pole layer formed on the lower protective layer, a magnetic gap layer formed on the lower magnetic pole layer, a lower insulating layer formed on the magnetic gap layer, a coil formed on the lower insulating layer, an upper insulating layer formed on the coil, an upper magnetic pole layer formed on the upper insulating layer, and an upper protective layer formed on the upper magnetic pole layer, at least the upper insulating layer, of the upper and lower insulating layers, being made of a porous material.
According to the third aspect of the present invention, there is provided a magnetic head having a lower protective layer, a lower magnetic pole layer formed on the lower protective layer, a magnetic gap layer formed on the lower magnetic pole layer, a lower insulating layer formed on the magnetic gap layer, a coil formed on the lower insulating layer, an upper insulating layer formed on the coil, an upper magnetic pole layer formed on the upper insulating layer, and an upper protective layer formed on the upper magnetic pole layer, at least the upper insulating layer, of the upper and lower insulating layers, being made of polyimide.
According to the fourth aspect of the present invention, there is provided a magnetic head having a lower protective layer, a lower magnetic pole layer formed on the lower protective layer, a magnetic gap layer formed on the lower magnetic pole layer, a lower insulating layer formed on the magnetic gap layer, a coil formed on the lower insulating layer, an upper insulating layer formed on the coil, an upper magnetic pole layer formed on the upper insulating layer, and an upper protective layer formed on the upper magnetic pole layer, the magnetic head having an ABS smoothed by polishing in an atmosphere of 40° C. to 90° C.
According to the fifth aspect of the present invention, there is provided a magnetic recording apparatus comprising:
a magnetic recording medium including a substrate and a magnetic recording layer formed on at least one surface of the substrate;
driving means for supporting and rotating the magnetic recording medium;
a magnetic head having a lower protective layer, a lower magnetic pole layer formed on the lower protective layer, a magnetic gap layer formed on the lower magnetic pole layer, a lower insulating layer formed on the magnetic gap layer, a coil formed on the lower insulating layer, an upper insulating layer formed on the coil, an upper magnetic pole layer formed on the upper insulating layer, and an upper protective layer formed on the upper magnetic pole layer, at least the upper insulating layer, of the upper and lower insulating layers, being made of a resin having a glass transition temperature of 70° C. to 100° C., and the magnetic head being adapted to record information on the magnetic recording medium; and
a carriage assembly supporting the magnetic recording head to be movable with respect to the magnetic recording medium.
According to the sixth aspect of the present invention, there is provided a magnetic recording apparatus comprising:
a magnetic recording medium including a substrate and a magnetic recording layer formed on at least one surface of
Hoshina Shigeru
Sakata Hiromi
Tanimoto Kazushi
Yoda Hiroaki
Cao Allen
Kabushiki Kaisha Toshiba
Pillsbury & Winthrop LLP
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