JP2003030806A - Nonmagnetic substrate material for magnetic head and magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a nonmagnetic substrate material having excellent balance in thermal conductivity and wear resistance and to apply the material for a magnetic head having a magnetoresistance effect element. SOLUTION: The nonmagnetic substrate material for a magnetic head essentially comprises titanium oxide and aluminum oxide. The aluminum oxide occupies 50 to 80% volume of the material. The magnetic head is produced by using the nonmagnetic substrate material as a first substrate 2 and a second substrate and forming a magnetoresistance effect element 5 on each substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-magnetic substrate material for a magnetic head having an excellent balance between thermal conductivity and wear resistance, and a magnetic head having a magnetoresistive effect element on the non-magnetic substrate.

[0002]

2. Description of the Related Art A VTR (Video Tape Recorder) or DAT (Digit) using a magnetic recording tape as a recording medium.
A magnetic recording / reproducing apparatus such as an al audio tape is provided with a magnetic head including a magnetoresistive head for recording a predetermined signal on a magnetic recording tape and reproducing the recorded signal.

HD using a magnetic disk as a recording medium
D (Hard Disk Drive) and FDD (Flexible Disk D)
A magnetic recording / reproducing apparatus such as a rive) is also equipped with a similar magnetic head.

In recent years, in order to increase the density of magnetic recording,
There is an increasing demand for a narrower track and a narrower gap for narrowing the track width for recording and reproduction. In order to meet such demands, a magnetic head (hereinafter, referred to as “MR head”) having a magnetoresistive effect element on a substrate made of a non-magnetic substrate is used for an HDD device or the like for reproduction only.

As a guard material for a non-magnetic substrate used in an MR head, a technique using an Al ₂ O ₃ —TiC system has been disclosed (see, for example, Japanese Patent Publication No. 58-5470).

Here, when the magnetic head is mounted on a rotating drum and is used for a helical reproducing magnetic head that slides at high speed on a magnetic recording medium, the magnetoresistive effect element is heated by frictional heat. In general, a magnetoresistive element changes its magnetic resistance with temperature. Al ₂ O ₃ -Ti described above
When a C-based non-magnetic substrate is used, the heat conductivity is high, so that heat dissipation is good, and the change in magnetoresistance due to the temperature rise of the magnetoresistive element does not pose a problem.

[0007]

However, Al ₂
When an MR head using an O ₃ —TiC-based non-magnetic substrate is mounted on a rotating drum and used as a helical reproducing magnetic head that slides at high speed on a magnetic recording medium, the initial shape changes greatly due to wear. , The bias state and the resistance value of the magnetoresistive element change. Therefore, problems such as deterioration of reproduction output and symmetry of output waveform occur.

[0008]

The present invention has been made to solve the above problems. That is, in the present invention, the titanium oxide and the aluminum oxide are the main components, and the aluminum oxide has a volume ratio of 50-8.
It is a non-magnetic substrate material for a magnetic head, which is 0%. Also,
It is also a magnetic head in which a magnetoresistive effect element is formed using this non-magnetic substrate material as a substrate.

According to the present invention as described above, the thermal conductivity and the wear resistance of the non-magnetic substrate material for the magnetic head can be balanced, and the present invention is also used in the magnetic head for reproducing while sliding on the magnetic recording medium. become able to.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic perspective view illustrating a magnetic head according to this embodiment, and FIG. 2 is an enlarged view of an element portion of the magnetic head. That is, the MR head 1 includes a first substrate 2, a lower shield thin film 3 and a first non-magnetic non-conductive film (hereinafter, referred to as “lower gap film”) 4 on the first substrate 2. Magnetoresistive element 5 formed through
The magnetoresistive effect element 5, and the second nonmagnetic nonconductive film (hereinafter, referred to as “upper gap film”) 6 and the upper shield thin film 7 on the magnetoresistive effect element 5. And a second substrate 8 to be joined together.

The MR head 1 has a tape sliding surface 1a shown in FIG.
Is processed into an arcuate curved surface along the running direction of the magnetic tape indicated by the arrow A direction. The MR head 1 is formed so that the magnetoresistive effect element 5 or a portion in the vicinity thereof protrudes most than the other portions on the tape sliding surface 1a. Therefore, in the MR head 1, the contact characteristics of the magnetoresistive effect element 5 with respect to the magnetic tape can be improved.

The lower shield thin film 3 is a soft magnetic film formed on the first substrate 2. As a material, sendust, permalloy, Co-based amorphous or the like is preferable from the viewpoint of soft magnetic characteristics.

The lower shield thin film 3 is a shield material that magnetically shields the lower layer of the magnetoresistive effect element 5.
The lower gap film 4 is a nonmagnetic insulating film formed on the lower shield thin film 3 described above, and is made of Al ₂ O ₃ or Si.
O ₂ is the most suitable in terms of insulation characteristics.

The magnetoresistive effect element 5 utilizes the phenomenon that the resistance value changes due to the change in the direction of the current flowing therethrough and the deviation angle in the direction magnetized by the magnetic field from the recording medium. The signal recorded on the magnetic tape is read.

The MR head 1 reads the signal recorded on the recording medium by detecting the resistance change rate of the magnetoresistive effect element 5.

The magnetoresistive element 5 is a SAL (Sof
t Adjacent Layer) film 5a, insulating film 5
It has a three-layer structure in which a and the MR film 5c are stacked in this order from the lower gap film 4 side.

The SAL film 5a is for applying a bias magnetic field to the MR film 5c, and is made of a soft magnetic material such as permalloy having a low coercive force and a high magnetic permeability. The insulating film 5b is M
It is for insulating between the R film 5c and the SAL film 5a.
It is made of an insulating material such as a.

In the MR element 5c, the side surfaces of the above-mentioned three-layer film are formed in a tapered shape. The MR film 5c is made of a soft magnetic material such as Ni-Fe whose resistance value changes according to the magnitude of the external magnetic field due to the magnetoresistive effect.

In the magnetoresistive element 5, a permanent magnet film 9 made of a hard magnetic material having a high coercive force is in contact with tapered portions on both side surfaces. The permanent magnet film 9 is for applying a bias magnetic field to the magnetoresistive effect element 5 in order to stabilize the operation of the magnetoresistive effect element 5, and Cr / CoCr /
It is formed of Pt or the like.

On the permanent magnet film 9, there is formed a conductive thin film 10 made of a conductive material having a low electric resistance for flowing a sense current to the magnetoresistive effect element 5. Conductive thin film 1
Reference numeral 0 denotes an electrode for supplying a sense current to the magnetoresistive element 5, which is made of TiW / Ta or the like.

As shown in FIG. 1, the conductive thin film 10 is formed so as to be exposed from the second substrate 8, and the exposed end faces 10a and 10a serve as external terminals.

The upper gap film 6 is a non-magnetic insulating film formed on the conductive thin film 10 and the magnetoresistive effect element 5. Like the lower gap film 4, the upper gap film 6 has an insulating characteristic A.
I ₂ O ₃ and SiO ₂ are preferred.

The upper shield thin film 7 is the upper gap film 6
It is a soft magnetic film formed on the above. From the viewpoint of soft magnetic characteristics, sendust, permalloy, Co-based amorphous, and the like are preferable.

In the present invention, the structure and material of the magnetoresistive effect element 5 are not limited to the above-mentioned examples, and the material is appropriately selected according to the intended use, reproduction characteristics, etc. Should be decided.

Next, in Table 1, TiO 2₂And Al₂O₃And the Lord
Non-magnetic substrate material Al as a component₂O ₃Volume fraction and heat conduction
The relationship between the rate and the wear amount is shown.

[0026]

[Table 1]

The sample whose thermal conductivity was measured had a diameter of 10
mm, and a plate-like substrate having a thickness of 2 mm. The thermal conductivity was calculated from the following equation (1).

[0028] Thermal conductivity = thermal diffusivity x density x specific heat (1)

The thermal diffusivity, density and specific heat were determined by the laser flash method, Archimedes method and differential scanning calorimetry method, respectively.

The head shape for which the amount of wear was measured is 1.5 m.
The width is m (width) × 2 mm × 0.2 mm (thickness), the contact width of the sliding surface is 80 μm, and the curvature in the contact width direction is R6 mm.

In the running test, a data storage tape drive deck SDX-300C (manufactured by Sony Corporation) and a Co alloy thin film vapor deposition tape SDX-T3N (manufactured by Sony Corporation) were used in an environment of 10 ° C. and 50% RH. It was run for 1000 hours. The amount of wear was calculated from the amount of change in electrical resistance before and after the running test.

First, regarding the thermal conductivity, Al₂O₃Body of
Al by adjusting the product ratio to 50% or more ₂O₃-Compared to TiC
It can be equal or better than the comparison.

Next, with respect to the wear amount, the wear amount of 80% or less by volume ratio of Al ₂ O ₃ is 0.1~0.3μm and Al ₂ O ₃
-It shows very good wear resistance as less than 1/10 compared to TiC type.

From the above results, by using TiO ₂ and Al ₂ O ₃ as the main components and setting the volume ratio of Al ₂ O ₃ to 50 to 80%, a non-magnetic material having a good balance between thermal conductivity and wear resistance can be obtained. A substrate material can be obtained.

Therefore, even in the magnetic head using the non-magnetic substrate material, it becomes possible to achieve a good balance between heat conduction and wear resistance.

In the above-described embodiment, the non-magnetic substrate used in the magnetic head for the data storage tape recorder is assumed and evaluated, but the same result is obtained also in the magnetic head for VTR or DAT. be able to.

[0037]

As described above, the present invention has the following effects. That is, the non-magnetic substrate and the magnetic head of the present invention have an excellent balance between thermal conductivity and wear resistance, and it is possible to obtain a good magnetic head without deterioration of reproduction output and the like.

[Brief description of drawings]

FIG. 1 is a schematic perspective view illustrating a magnetic head according to an embodiment.

FIG. 2 is an enlarged view of an element portion of a magnetic head.

[Explanation of symbols]

1 ... MR head, 2 ... First substrate, 3 ... Lower shield thin film, 4 ... Lower gap film, 5 ... Magnetoresistive element, 6
... upper gap film, 7 ... upper shield thin film, 8 ... second substrate, 9 ... permanent magnet film, 10 ... conductive thin film

Claims (2)

[Claims] 1. A titanium oxide and an aluminum oxide as main components, wherein the aluminum oxide has a volume ratio of 50.
A non-magnetic substrate material for a magnetic head, which is -80%. 2. A magnetic head provided with a magnetoresistive effect element for reading a magnetic signal by a magnetoresistive effect on a nonmagnetic substrate, wherein the nonmagnetic substrate contains titanium oxide and aluminum oxide as main components, and the aluminum oxide is used. A magnetic head having a volume ratio of 50 to 80%.