JPH05210816A - Magnetic head - Google Patents

Abstract

PURPOSE:To make a joint boundary between a ferrite single crystal and a ferrite polycrystal uniform and reduce a sliding noise. CONSTITUTION:In a ferrite joint type magnetic head in which ferrite single crystals are used for sliding parts 1a and 2a of a magnetic recording medium and ferrite polycrystals are used for parts 1b and 2b consisting a rear magnetic circuit, the ferrite single crystal and the ferrite polycrystal are united integrally by glass sputtered films 9 and 10 formed by sputtering the glass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonded ferrite type magnetic head whose main core is a bonded ferrite composed of single crystal ferrite and polycrystalline ferrite.

[0002]

2. Description of the Related Art In recent years, video tape recorders (VTRs)
High-density recording and short-wavelength recording have been promoted with the advent of so-called digital video tape recorders, etc., in response to the demands for downsizing and longer time of equipment such as It is being used.

Therefore, research has been conducted to deal with this in the field of magnetic heads. For example, for a magnetic head for a video tape recorder requiring a high recording density, only a so-called single crystal ferrite using a single crystal ferrite having a high saturation magnetic flux density at a high frequency of about 5 MHz and a relatively large magnetic permeability is used. A single-unit type magnetic head composed of is proposed. However, the single-type ferrite head has a drawback that the level of sliding noise is high.

Therefore, a magnetic head has been proposed in which the sliding noise level is reduced by reducing the proportion of the single crystal ferrite. Such a magnetic head is
The so-called junction ferrite type magnetic, in which the sliding contact portion of the magnetic recording medium is formed of single crystal ferrite having a high saturation magnetic flux density, and the remaining portion constituting the rear magnetic circuit portion is formed of polycrystalline ferrite having a high magnetic permeability. The head. This magnetic head has a simple structure similar to that of the single ferrite head described above, but is capable of high-density recording and achieves a reduction in sliding noise level.

By the way, the single crystal ferrite and the polycrystalline ferrite are generally joined by a hot press treatment. The hot pressurizing process is performed, for example, in a nitrogen atmosphere at about 12
Under a temperature condition of about 50 ° C., a single crystal ferrite and a polycrystalline ferrite are superposed on each other, and about 5 kgf / c
This is because a pressure of about m ² is applied and held for several hours.

[0006]

However, in the hot pressing treatment, since the heating temperature is as high as 1250 ° C., the grains of the polycrystalline ferrite grow and grow into the single crystal ferrite. The bonding interface between crystalline ferrite and polycrystalline ferrite becomes unclear. for that reason,
The effect of reducing sliding noise due to the junction type of single crystal ferrite and polycrystalline ferrite cannot be expected sufficiently.

Therefore, the present invention has been proposed in view of such a conventional situation, and it is possible to prevent grain growth at the bonding interface between the single crystal ferrite and the polycrystalline ferrite, and thus the bonding ferrite having a very low sliding noise level. A type of magnetic head is provided.

[0008]

In order to achieve the above-mentioned object, a magnetic head according to the present invention uses a single crystal ferrite in a sliding contact portion of a magnetic recording medium and a polycrystalline ferrite in a portion constituting a rear magnetic circuit portion. In the bonded ferrite type magnetic head using, the single crystal ferrite and the polycrystalline ferrite are bonded and integrated by a glass sputtered film formed by sputtering glass.

[0009]

In the magnetic head according to the present invention, since the single crystal ferrite and the polycrystalline ferrite are bonded and integrated by the glass sputtered film formed by sputtering glass, the bonding interface between the single crystal ferrite and the polycrystalline ferrite is formed. Will be uniform. Therefore, sliding noise is reduced by making the joint interface uniform.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described in detail below with reference to the drawings. As shown in FIG. 1, the magnetic head of this embodiment has a pair of magnetic core halves 1 and 2 whose main core is a bonded ferrite obtained by bonding a single crystal ferrite and a polycrystalline ferrite. It is constructed by abutting one another and joining them together by the fused glasses 3 and 4.

On the abutting surfaces of the pair of magnetic core halves 1 and 2, track width restricting grooves 5 and 6 each having a substantially arc shape for restricting a track width Tw of a magnetic gap g which operates as a recording / reproducing gap. Are provided on both edge sides. Further, coil winding grooves 7 and 8 having a substantially U-shaped cross section for winding a coil are provided on the abutting surfaces of the magnetic core halves 1 and 2. The coil winding groove 7,
8, the inclined surface 7a provided on the magnetic gap g side,
8a regulates the depth of the magnetic gap g.

By the way, in the magnetic head of this embodiment, in order to reduce the sliding noise generated by the ferrite, the sliding contact portions 1a and 2a of the magnetic recording medium are made of single-crystal ferrite having a high saturation magnetic flux density. Back portions 1b and 2b constituting the rear magnetic circuit portion excluding the vicinity of the gap g
Are composed of polycrystalline ferrite having a high magnetic permeability. As a result, at the time of recording, the entire magnetic head exhibits the same characteristics as those made of a high saturation magnetic flux density material, and sufficient recording can be performed even on a high coercive force magnetic recording medium. On the other hand, at the time of reproduction, since the average magnetic permeability of the magnetic head is high, a good electromagnetic conversion characteristic is exhibited.

In particular, in this embodiment, a glass sputtered film formed by sputtering glass with a single crystal ferrite and a polycrystalline ferrite for the purpose of making the bonding interface between the single crystal ferrite and the polycrystalline ferrite uniform. It is joined and integrated by 9 and 10. The glass sputtered films 9 and 10 are formed by using high melting point glass as a target and sputtering the glass on single crystal ferrite and polycrystalline ferrite, respectively. The glass used here is a glass that melts at a temperature sufficiently lower than the temperature at which the grains of the polycrystalline ferrite grow because it prevents the grains of the polycrystalline ferrite from growing at the bonding interface. For example, the yield point T _D is 58
A glass having a glass transition temperature Tg of 3 ° C. and a glass transition temperature Tg of 640 ° C. is preferable. It should be noted that such a glass has sufficiently high reliability also in terms of the bonding strength between the single crystal ferrite and the polycrystalline ferrite, and the fused glass 3, 4 at the time of gap bonding is used.
It does not melt by the heat of. As described above, the glass sputtered films 9 and 10 formed by sputtering glass having a temperature lower than the temperature at which the grains of polycrystalline ferrite grow.
Is provided at the joint interface between the single crystal ferrite and the polycrystalline ferrite, so that the joint interface can be made uniform. Therefore, the joint interface becomes clear, and sliding noise can be reduced.

The above magnetic head is manufactured as follows. First, as shown in FIG. 2, single crystal Mn
The Zn ferrite substrate 11 and the polycrystalline MnZn ferrite substrate 12 are cut into a predetermined size, and the end faces are mirror-polished with diamond abrasive grains or a resin-based # 1000 grindstone. Next, glass is sputtered on both sides or one side of the single crystal MnZn ferrite substrate 11 and the polycrystalline MnZn ferrite substrate 12. The glass is sputtered as follows.

First, SiO ₂ 73% and Na ₂ O 14
%, CaO 11%, Al ₂ O ₃ 2%,
The yield point T _D is 583 ° C and the glass transition temperature Tg is 640 ° C.
Use glass. In addition, the yield point T _D of the glass here is the fusion glass 3 used in the gap fusion.
It is necessary to use a temperature at which the viscosity of ⁴ is 10 ⁴ poise, that is, higher than the working temperature. That is, this is to prevent the glass sputtered film at the bonding interface from being melted by the heat during the gap bonding.

Next, a glass having the above-mentioned composition was prepared to have a diameter of 4 m.
A disk-shaped target having a thickness of 5 mm and a thickness of 5 mm is manufactured to be a target made of glass. Then, using a magnetron type sputtering device, in an Ar + 10% O ₂ gas atmosphere,
Under conditions of a gas pressure of 6 mToor and a power density of 1 W / cm ² , glass is sputtered on both surfaces of the single crystal MnZn ferrite substrate 11 and the polycrystalline MnZn ferrite substrate 12 using a glass target having the above composition. The gas atmosphere may be only Ar gas.

As a result, on both surfaces of the single crystal MnZn ferrite substrate 11 and the polycrystalline MnZn ferrite substrate 12,
As shown in FIG. 3, glass sputter films 13 and 14 each made of glass are formed. If the film thickness of the glass sputtered films 13 and 14 at this time is too thin, sufficient bonding strength cannot be obtained at the bonding interface, and if too thick, the non-magnetic portion between the single crystal ferrite and the polycrystalline ferrite becomes thick, This will lead to an increase in magnetic resistance. Therefore, the film thickness of the glass sputtered films 13 and 14 is determined from the viewpoint of the bonding strength and the magnetic resistance at the bonding interface, and the total film thickness at the bonding interface is optimally about 50Å to 2000Å.
In this example, glass sputter films 13 and 14 were formed on both surfaces of the single crystal MnZn ferrite substrate 11 and the polycrystalline MnZn ferrite substrate 12, respectively.

Next, the single crystal MnZn ferrite substrate 11 and the polycrystalline MnZn ferrite substrate 12 are alternately stacked as shown in FIG. Then, at a temperature higher than the glass transition temperature Tg of the glass sputtered films 13 and 14,
A pressure of about 25 kgf / cm ² is applied to these substrates 11 and 12, and pressure heat treatment is performed along the temperature curve shown in FIG.

In this embodiment, the glass transition point Tg is 640.
Since the temperature was at 0 ° C, heat of 700 ° C at which the glass melted sufficiently was applied. The working temperature Tw at this time is 700
If the temperature is from ℃ to 720 ℃, grains of polycrystalline ferrite will not grow. Since the glass transition point Tg can be freely set by changing the composition of the glass, the working temperature Tw at the time of bonding can be selected from a wide range in which the bonding strength can be sufficiently secured.

As a result, a bonded ferrite block having a uniform bonding interface between the single crystal ferrite and the single crystal ferrite and having a high bonding strength can be obtained. Then, a magnetic head chip is cut out from the obtained bonded ferrite block to a predetermined size, winding groove processing and track width processing are performed on this, and gap bonding is performed, whereby the bonded ferrite type magnetic head is manufactured. ..

The specific embodiments to which the present invention is applied have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, as shown in FIG. 6, a metal magnetic thin film 1 made of a ferromagnetic metal material such as sendust is provided on the facing surfaces of the magnetic core halves 1 and 2 of FIG.
The present invention can also be applied to a metal-in-gap type magnetic head formed by depositing films 5 and 16. Of course, this magnetic head can also obtain the same effects as the magnetic head shown in FIG. In addition, as shown in FIG. 7, the opposing surfaces of the magnetic core halves 1 and 2 of FIG. 1 are notched obliquely with respect to the magnetic gap g, and metal magnetic thin films 17 and 18 are formed on the inclined surfaces. The present invention can also be applied to a magnetic head in which a magnetic gap g is formed on the abutting surface between the oblique films 17 and 18. Similarly, this magnetic head has the same effects as the magnetic head shown in FIG. Actually, when the sliding noise was measured using the magnetic heads shown in FIGS. 6 and 7, the sliding noise of 1 dB was compared with the conventional bonded ferrite type magnetic head manufactured by the hot press treatment at high temperature. Dynamic noise reduction was achieved.

[0022]

As is apparent from the above description, in the magnetic head of the present invention, the single crystal ferrite and the polycrystalline ferrite are joined and integrated by the glass sputtered film formed by sputtering glass. The joint interface between the single crystal ferrite and the polycrystalline ferrite becomes uniform. Therefore, according to the magnetic head of the present invention, sliding noise is significantly reduced, and recording / reproduction can be performed well.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a magnetic head to which the present invention is applied.

2 is a perspective view showing a step of manufacturing the magnetic head of FIG. 1 and showing a substrate cutting step. FIG.

3 is a perspective view showing a step of producing the magnetic head of FIG. 1 and showing a step of forming a glass sputtered film. FIG.

4 is a perspective view showing a step of manufacturing the magnetic head shown in FIG. 1 and showing a step of joining substrates. FIG.

5 is a diagram showing a process of manufacturing the magnetic head shown in FIG. 1, and is a diagram showing a heating temperature curve when joining substrates. FIG.

FIG. 6 is a perspective view showing another example of a magnetic head to which the present invention is applied.

FIG. 7 is a perspective view showing still another example of a magnetic head to which the present invention is applied.

[Explanation of symbols]

1, 2 ... Magnetic core halves 1a, 2a ... Magnetic recording medium sliding portion (single crystal ferrite) 1b, 2b ... Back portion (polycrystalline ferrite) 3, 4 ... Fused glass 9 , 10 ... Glass sputtered film

Claims (1)

[Claims] 1. A junction ferrite type magnetic head in which single crystal ferrite is used in a sliding contact portion of a magnetic recording medium and polycrystalline ferrite is used in a portion constituting a rear magnetic circuit portion, wherein the single crystal ferrite and the polycrystalline ferrite are combined. Is a magnetic head characterized by being integrally bonded by a glass sputtered film formed by sputtering glass.