JP2763703B2 - Magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head, and more particularly to a magnetic head capable of controlling a change in a magnetic domain structure represented by a wiggle in a magnetization mechanism of a magnetic core composed of soft ferrite, particularly Mn-Zn ferrite. Is to be provided.

[0002]

2. Description of the Related Art Conventionally, in the field of magnetic recording, the recording density of signals recorded on a magnetic recording medium has been improved, and the coercive force of the magnetic recording medium itself has been improved. The head is required to have a narrower track and a higher saturation magnetic flux density.

In such a background, a monolithic magnetic head using a ferrite such as a Mn-Zn ferrite for a head core and a slider is widely and generally used as a floating magnetic head for performing recording and reproduction on a magnetic disk. I have.

The ferrite heads are roughly classified into a monolithic type and a composite type. In the monolithic type, a slider also serves as a head magnetic circuit, and track width processing called a center rail is performed. In the composite type, a small magnetic circuit is fitted into non-magnetic ceramic and glass-bonded,
Although it is generally considered to be highly reliable, the structure is slightly more complicated and the manufacturing cost is higher than that of the monolithic type. Furthermore, the monolithic type is larger than the standardized output.
However, for the same number of turns, the composite type has a smaller inductance, so the composite type can be said to have a slightly higher frequency. In addition, there are both advantages and disadvantages, such as a problem of recording bleeding, a problem of effective use of a disk surface, and a problem of floating reliability, and both types are widely and generally used.

Hereinafter, an example of a conventional magnetic head will be described with reference to the drawings. Figure 4 is a monolithic type, Figure 5
1 is a perspective view of a composite type floating magnetic head. FIG. 6 is an enlarged plan view of a main part of the composite floating magnetic head shown in FIG.

The conventional magnetic head 1 'shown in FIGS.
Is a magnetic core chip 3 'shown in FIG.
a, 2a. Generally, floating magnetic heads include a monolithic type in which a magnetic core chip 3 'protrudes outside the slider main body 2 as shown in FIG. 4, and a composite type included in the slider main body 2 as shown in FIG. The magnetic core chip 3 'is composed of a magnetic core 4a made of ferrite, a mold glass 5 filled around the magnetic core 4a, and a winding coil wound around a winding portion of the magnetic core. And
A gap 4 is formed in the magnetic core 4a. Therefore, in the structure shown in FIGS. 4 and 5, the magnetic head 4 'is completed by fitting the magnetic core 4a to the slider body 2 having the flying rails 2a and 2a, and further filling and fixing the mold glass 5. Have been.

As shown in FIGS. 4 and 5, a magnetic core 4a inserted into a groove 2b formed at one end of a slider body 2 made of, for example, a non-magnetic ceramic material or a magnetic ferrite material, and its periphery. A magnetic core chip 3 ′ is formed by the mold glass 5 filled in the magnetic core chip 3 ′. Further, the slider body 2 is provided with a pair of floating rails 2a and 2a so as to stabilize the levitation force on the medium facing surface thereof, so that a constant levitation force is generated even when the medium speed is low, such as when starting and stopping. 2 near the inflow of air 2
c. And the inclined surface 2 of the slider 2
a groove 2b for inserting a magnetic core 4a into one end of a rail surface 2d opposite to the floating rails 2a, 2a on which the c, 2c are formed.
Are formed.

[0008]

A conventional magnetic core chip 3 is composed of a material forming a magnetic core 4a and a mold glass 5;
Are in direct contact with each other, a reaction between the magnetic core 4a forming material and the mold glass 5 occurs, and a reaction deterioration layer is generated at the interface between the magnetic core 4a forming material and the mold glass. Furthermore, when there is a difference in the coefficient of thermal expansion between the mold glass 5 and the magnetic core forming material, internal thermal stress and tensile stress are generated inside the magnetic core 4a forming material, and the magnetic properties are deteriorated. .

What has recently been noticed in the above-mentioned magnetic head 1 'is the generation of wiggle noise. Uighur noise is considered to be a type of Barkhausen noise.Generally, Barkhausen noise is considered to be caused by discontinuous domain wall motion.However, Uighur noise changes its magnetic domain structure when a large magnetic field such as a recording magnetic field is applied. It is interpreted that the magnetization response characteristic changes.

That is, the structure of the conventional magnetic head 1 'is as follows.
Since the volume of the magnetic core 4a is reduced, the domain size is
It cannot be ignored compared to the size of the magnetic core 4a, and the magnetization behavior of the magnetic domain size affects the magnetic head characteristics. In other words, since the magnetic circuit of the magnetic head 1 ′ becomes smaller, it is interpreted that a change in the magnetic domain structure such as wiggle noise affects the magnetic head characteristics.

Further, the wiggle noise is generated due to the above-mentioned defect factor in the magnetic core 4a. Therefore, the generation of such wiggle noise directly affects the magnetic anisotropy in the core of the stress-induced anisotropy, which makes it difficult to select an optimal magnetization direction of the magnetic head core. Therefore, the generation of wiggle noise causes magnetic hysteresis and lowers the magnetic permeability.

Therefore, the hindrance of domain wall motion, which is a cause of the above-mentioned wiggle noise, that is, the cause of reversible domain wall motion is caused by non-uniformity (crystal grain boundaries, lattices, impurities) inside the material forming the magnetic core 3. Therefore, it can be said that the internal energy changes depending on the position where the domain wall exists. In particular, a sintered body such as ferrite has a problem that the inside tends to be non-uniform as compared with a metal.

Therefore, the present invention suppresses the deterioration of the magnetic properties due to the reaction between the magnetic core forming material and the mold glass as described above and the deterioration of the magnetic properties due to thermal stress, suppresses the generation of wiggle noise, and improves the magnetic properties. Another object of the present invention is to provide a magnetic head capable of controlling a magnetization mechanism of a magnetic head core, that is, a magnetization state thereof, while providing a simple magnetic head.

[0014]

According to a first aspect of the present invention, a groove is formed in a slider body made of a non-magnetic material or a magnetic material and having a flying rail. In a magnetic head having a magnetic core fixed by glass, a buffer layer of a non-magnetic material is formed between the mold glass and the magnetic core.

[0015]

According to the magnetic head of the present invention, by forming a buffer layer made of a non-magnetic material between the mold glass and the magnetic core, the mold glass does not come into direct contact with the magnetic core-forming material, and the mold glass does not directly contact the mold glass. And the formation of a degraded layer due to the reaction between the magnetic layer and the magnetic core forming material.
When the magnetic core is formed of ferrite, the buffer layer is formed of a non-magnetic material having a thermal expansion coefficient of 70 to 170 × 10 ⁻⁷ / ° C., so that the thermal expansion coefficient of the buffer layer is reduced. By setting the coefficient of thermal expansion of the ferrite as a substance in the vicinity of the coefficient of thermal expansion and reducing the difference between the coefficients of thermal expansion, the residual thermal stress inside the ferrite forming the magnetic core chip and the occurrence of tensile stress can be reduced. it can. As a typical material of the buffer layer, Cr having a thermal expansion coefficient of (about 84 × 10 ⁻⁷ / ° C.) is preferable.

Accordingly, in the present invention, a magnetic head which can control the magnetization mechanism of the magnetic head core part 3, that is, the magnetization state thereof, can be provided, while providing a magnetic head having good magnetic properties while suppressing the generation of wiggle noise. can do. This effect is achieved not only by the two types of floating magnetic heads shown in the above-mentioned conventional example, but also by filling mold glass around a magnetic core such as a composite type magnetic head. Can be applied to a magnetic head having

[0017]

An embodiment of the present invention will be described below. The magnetic head 1 of the present invention shown in FIG. 1 comprises a magnetic core chip 3 shown in FIG. 2 and a slider body 2 having flying rails 2a, 2a. The core chip 3 includes a magnetic core 4 a, a buffer layer 6 made of a non-magnetic material and coated around the magnetic core 4 a,
Glass 5 covering the magnetic core 4a
The winding coil 8 is wound around the winding portion 3a. A gap 4 is formed in the magnetic core 4a. Therefore, in this structure, the magnetic core 4a, on which the buffer layer 6 made of the substance forming the magnetic core 4a and the non-magnetic material is formed, is fitted to the slider body 2 having the flying rails 2a, 2a. The magnetic head 1 is completed by filling and fixing the glass 5.

When the magnetic core 4a is formed of ferrite, a buffer layer 6 made of a nonmagnetic material of 70 to 170 × 10 ^-7 / ° C. is formed between the magnetic core 4a and the mold glass 5. However, the material of the buffer layer 6 includes
It is desirable to use Cr.

Therefore, the magnetic head 1 according to the present invention is provided between the mold glass 5 of the magnetic core chip 3 and the magnetic core.
By forming the buffer layer made of a non-magnetic material, the mold glass and the magnetic core do not come into direct contact with each other, and deterioration due to a reaction between the mold glass and a substance forming the magnetic core can be prevented. Further, as described above, the thermal expansion coefficient of the buffer layer is set near the thermal expansion coefficient of the magnetic core forming material, and the difference between the two thermal expansion coefficients is reduced, so that the residual heat inside the magnetic core forming material is reduced. Stress and tensile stress are not easily generated, and cracks and peeling inside the magnetic core forming material can be prevented.

When the magnetic core is formed of ferrite, the buffer layer has a coefficient of thermal expansion of 70 to 170 × 10 ⁻⁷ / ° C.
By setting the coefficient of thermal expansion of the buffer layer to be close to the coefficient of thermal expansion of ferrite, which is a magnetic core forming substance, by reducing the difference between the coefficients of thermal expansion of the two, It is possible to make it difficult to generate residual thermal stress and tensile stress inside the ferrite forming the core chip.

FIG. 3 is a graph showing the measured asymmetry variation of the magnetic core 3 of the magnetic head according to the present invention. When FIG. 3 is compared with FIG. 7 which is a graph showing the asymmetry fluctuation rate of the conventional magnetic head 1 ′, it is confirmed that the occurrence of wiggle noise is reduced. That is, by preventing the deteriorated layer at the magnetic core forming material-mold glass interface and avoiding thermal stress and tensile stress inside the magnetic core forming material, the asymmetry fluctuation rate is improved as compared with the conventional magnetic head, and the bit shift fluctuation is improved. Can be said to be greatly reduced.

[0022]

According to the magnetic head of the present invention, a buffer layer made of a nonmagnetic material is formed between a mold glass of a magnetic core chip and a magnetic core forming material.
Since the mold glass and the magnetic core do not come into direct contact with each other, deterioration due to a reaction between the mold glass and a substance forming the magnetic core can be prevented. Further, as described above, the thermal expansion coefficient of the buffer layer is set near the thermal expansion coefficient of the magnetic core forming material, and the difference between the two thermal expansion coefficients is reduced, so that the residual heat inside the magnetic core forming material is reduced. Stress,
It is difficult to generate tensile stress, and it is possible to prevent cracks and peeling inside the magnetic core forming material. When the magnetic core is formed of ferrite, the buffer layer is formed of a non-magnetic material having a coefficient of thermal expansion of 70 to 170 × 10 ⁻⁷ / ° C., so that the coefficient of thermal expansion of the buffer layer can be reduced. By setting the coefficient of thermal expansion of the ferrite in the vicinity of the ferrite, and by reducing the difference in the coefficient of thermal expansion between the two, the residual thermal stress inside the ferrite forming the magnetic core chip and the tensile stress are hardly generated, and the inside of the ferrite is hardly generated. Cracks and peeling can be prevented. In general, it is desirable that the buffer layer be formed of Cr.

Accordingly, a magnetic head having good magnetic characteristics can be provided by suppressing such a wiggle generation factor and a non-uniformity factor inside the magnetic core forming material of the magnetic head. Therefore, such an improvement in the magnetic characteristics makes it possible to manufacture a good magnetic head compatible with high-density recording.

[Brief description of the drawings]

FIG. 1 is a perspective view of a composite floating magnetic head according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view of a main part of FIG.

FIG. 3 is a graph showing a variation rate of asymmetry of the magnetic head shown in FIG. 1;

FIG. 4 is a perspective view showing an example of a conventional monolithic floating magnetic head.

FIG. 5 is a perspective view showing an example of a conventional composite floating magnetic head.

FIG. 6 is an enlarged plan view of a main part of FIG. 5;

FIG. 7 is a graph showing a variation rate of asymmetry of the magnetic head shown in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic head 2 Slider main body 2a Flying rail 2b Groove 3 Magnetic core chip 3a Winding part 4 Gap 4a Magnetic core 5 Mold glass 6 Buffer layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-56709 (JP, A) JP-A-63-133373 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 5/60

Claims (1)

(57) [Claims] 1. A magnetic head comprising a slider body made of a non-magnetic material or a magnetic material and having a flying rail and having a groove formed therein, and a magnetic core inserted and fixed in the groove with mold glass. And a buffer layer made of a non-magnetic material.