JPH0522283B2 - - Google Patents

Description

[Detailed Description of the Invention] Field of Application This invention relates to an improvement of a composite magnetic head that is mainly composed of a ferromagnetic oxide such as ferrite and uses a magnetic metal material near the operating gap. It prevents mutual diffusion that occurs at the joint with the metal magnetic material, eliminates magnetic spurious gaps, prevents magnetic characteristics, such as undulations in the frequency characteristics of the reproduced output, and has flat output characteristics. The present invention relates to a composite magnetic head which has a structure with good manufacturability and is suitable for various magnetic recording and reproducing devices using recording media having high coercive force.

BACKGROUND ART In recent years, in the field of magnetic recording, so-called metal recording media having high coercive force have been used to meet the demand for higher density recording signals. for example,
It is being used in magnetic recording and reproducing devices for a wide variety of recording formats, such as FDDs, HDDs, VTRs, magnetic tape storage devices for computers, S-DATs, and still video floppies.

A magnetic head that magnetically records and reproduces information on a magnetic recording medium having a high residual magnetic flux density, such as a metal tape, has had to generate a magnetic field strength higher than before in its magnetic gap.

On the other hand, in the case of a magnetic head that consists of a magnetic core made of a ferromagnetic oxide such as single-crystal ferrite, which is split into halves, and a pair of halves are abutted against each other, with the abutting portion forming a magnetic gap, the ferrite forming the gap is Since Bs was as low as 6000G at most, there was a problem that sufficient recording magnetic field strength could not be obtained.

Therefore, in a magnetic head mainly made of ferromagnetic oxide, the area near the magnetic gap of the magnetic head is
Various so-called composite magnetic heads have been proposed that are constructed from metal magnetic thin films having a higher saturation magnetic flux density Bs than ferrite.

For example, referring to the schematic diagram of the medium facing surface of a conventional composite magnetic head shown in FIGS. Half piece 1, 2
A metal magnetic thin film 3, is formed on each abutting surface 1a, 2a using a vacuum thin film forming technique such as a sputtering method.
After the magnetic core halves 1 and 2 are formed, a magnetic gap 5 is formed by butting the magnetic core halves 1 and 2 together.

In addition, the metal magnetic thin film of the composite magnetic head with such a configuration is required to have the following characteristics:
An Fe-Al-Si metal magnetic thin film is a material that satisfies the following requirements.

Has a Bs higher than that of ferrite materials Has excellent wear resistance Has excellent thermal stability Has excellent magnetic permeability at high frequencies (e.g. 10MHz) Problems with conventional technology The above-mentioned A composite magnetic head using an Fe--Al--Si alloy film as a metal magnetic thin film is widely used as an excellent magnetic head that satisfies various conditions for the use of metal tapes. However, the following problems arose.

To explain using the schematic diagram of the magnetic head in Fig. 4,
When forming the metal magnetic thin films 3 and 4 on the abutting surfaces of the magnetic cores 1 and 2 and forming the magnetic head core at high temperature using glass or the like, mutual diffusion between the metal magnetic thin films and the magnetic head core occurs. Due to the thin film formation conditions and the difference in thermal expansion coefficient between the cores 1 and 2 and the thin films 3 and 4, the magnetic properties of the initial layer of the metal magnetic thin film deteriorate, and the bonding parts 1b and 2b with the magnetic cores 1 and 2 deteriorate. When a magnetic discontinuity occurs and such a composite magnetic head is used for reproduction, the junctions 1b and 2b act as a pseudo gap, and a pseudo peak as shown in FIG. 6 (conventional method, peak b) appears. There was a problem in which the frequency characteristics of the reproduced output were distorted.

Furthermore, if there is a processed strain layer on the abutting surface of the magnetic cores 1 and 2 on which the metal magnetic thin film is to be deposited, the joining portion 1b
It was found that a magnetic discontinuity occurs in the magnetic field, which acts as a pseudo gap in the same way as described above.

For this kind of pseudo-gap generation problem,
In general, azimuth loss is used to make the joints 1b and 2b, which form a pseudo gap, and the magnetic gap 5 non-parallel, for example, as shown in FIG.
This problem has been dealt with by providing a predetermined azimuth angle.

However, in the structure shown in FIG. 3, it is necessary to deposit the metal magnetic thin film to a thickness of about 20 μm, which reduces yield due to film peeling or takes a long time to form the deposit, reducing productivity. There were problems such as poor quality.

Purpose of the Invention The object of the present invention is to provide a composite magnetic head suitable for high-density recording and reproducing on a magnetic recording medium having a high coercive force Hc, by preventing mutual diffusion between a metal magnetic thin film and a magnetic head core. The objective is to create a composite magnetic head that prevents the formation of gaps, is suitable for mass production, is highly reliable, and has good wear resistance.

Structure of the Invention As a result of various studies aimed at preventing mutual diffusion between the metal magnetic thin film and the magnetic head core in a composite magnetic head, the inventors first formed a Cr thin film on a substrate made of ferromagnetic oxide, etc. Then, Fe-
It is thought that if an Al-Si alloy film is formed, an Fe-Al-Si alloy film (a so-called Fe-Al-Si alloy film by epitaxial growth) will be formed along the crystal orientation of the underlying Cr thin film. It has been found that the crystal orientation of the initial layer is less disturbed and the soft magnetic properties of the Fe-Al-Si alloy film can be easily improved by heat treatment.

That is, the present invention provides a composite magnetic head in which a magnetic core mainly composed of ferromagnetic oxide has a metallic magnetic material at least in the vicinity of the operating gap.
The ferromagnetic oxide surface has a strain-free high flatness surface,
This is a composite magnetic head characterized by having a metal thin film body in which a Cr thin film and a Fe-Al-Si alloy thin film with a thickness of 100 Å to 1000 Å are laminated in this order.

The composite magnetic head of the present invention includes, for example, Ni-
The abutting surfaces of the magnetic core halves made of ferromagnetic oxides such as Zn ferrite and Mn-Zn ferrite are made into high-precision, flat and strain-free surfaces through stress-free processing such as mechanochemical polishing and float polishing. After processing it into a predetermined shape, a Cr thin film with a thickness of 100 Å to 1000 Å is deposited on the surface, and then a Fe-Al-Si alloy thin film, so-called sendust film, is deposited on the surface and processed into a predetermined shape. It is characterized by a structure in which magnetic core halves are butted together to form a magnetic gap.

Effects of the Invention By providing a metal thin film body with a two-layer structure of an Fe-Al-Si alloy thin film and a Cr thin film, which is a feature of this invention, on the ferromagnetic oxide magnetic core surface, the effect of relaxing the stress in the thin film can be obtained. This can prevent the alloy film from peeling off after heat treatment, and the magnetic core and Fe-Al-
This is effective in improving the bonding strength with Si-based alloy thin films.

In addition, mutual diffusion between the Fe-Al-Si alloy thin film and the ferromagnetic oxide due to heat treatment is difficult to occur, and the magnetic properties of the ferromagnetic oxide magnetic core surface layer are not deteriorated, resulting in a high coercive force Hc. A composite magnetic head suitable for high-density recording and reproducing on a magnetic recording medium can be obtained, and the effect of substantially eliminating so-called pseudo gaps and significantly reducing waviness in frequency characteristics can be obtained.

In addition, the metal thin film body may be a relatively thin film, and it is possible to obtain a composite magnetic head with excellent productivity, high reliability, and good abrasion resistance since it does not require much time to form the metal film.

Preferred Embodiments of the Invention In the present invention, a composite magnetic head has a structure in which a metal thin film is deposited on a ferromagnetic oxide surface with a strain-free high flatness surface, and a Cr thin film is further deposited on top of the ferromagnetic oxide surface. Any known structure can be used as long as it has a laminated structure with an Fe-Al-Si alloy thin film.

In addition, in this invention, the ferromagnetic oxide that is the main component of the magnetic core includes Ni-Zn ferrite and Mn-
Single-crystal ferrite such as Zn ferrite and HIP-treated sintered ferrite can be used.

The Fe-Al-Si alloy thin film provided in the outermost layer is a so-called sendust alloy, which has been widely used in composite magnetic heads, and a known composition can be selected as appropriate depending on the purpose of the magnetic head. I get it, but 3
An alloy in the range of ~10wt%Al, 6~15wt%Si, 80~90wt%Fe is often used, and if necessary, Cr, Ta, Ni, Co, Mo, Zr, rare earth elements, etc. It is also good to add.

A thin Cr film and a thin Fe-Al-Si alloy film are formed on the surface of the ferromagnetic oxide that constitutes the magnetic core half.The deposition methods include various sputtering methods, vacuum evaporation, Known vapor phase film forming methods such as ion plating can be used.

As for preferred deposition methods and conditions, in any method, the higher the degree of vacuum achieved, the better, and it is necessary to maintain a high vacuum of at least 10 ^-6 Torr or less, preferably 2 × 10 ^-6 Torr or less, and more preferably Preferably it is 1×10 ^-6 Torr or less.

When using the sputtering method, an inert gas such as argon gas is used as the sputtering gas, and the pressure may be appropriately selected depending on the structure of the sputtering device.

In this invention, since the thickness of the Cr thin film deposited on the ferromagnetic oxide surface is as thin as 100 Å to 1000 Å, it is strongly influenced by the surface condition of the ferromagnetic oxide, such as residual strain stress and roughness. In order to exhibit the effect of the Cr thin film, the surface roughness of the ferromagnetic oxide is preferably 100
The thickness is preferably 40 Å or less, more preferably 40 Å or less.

Strain-free surfaces of such ferromagnetic oxides. A good method for obtaining a high flatness state is mechanochemical polishing, float polishing, diamond polishing followed by mechanochemical polishing, or diamond polishing followed by mechanochemical polishing followed by float polishing. It is also good to use a reverse sputtering method.

In addition, in this invention, as a mechanochemical polishing method, MgO, ZrO ₂ , Al ₂ with a particle size of 0.1 μm or less
Using a suspension of 0.5wt% to 20wt% of O ₃ , SiO ₂ , etc. alone or mixed fine powder in pure water, for example, hard cloth, solder, Sn, etc. It is preferable that a disc-shaped polisher consisting of a polisher is rotatably disposed, the workpiece is brought into contact with the polisher surface in this suspension under a predetermined load, and the two are rotated relative to each other to perform polishing.

In the polishing method, the polisher material, rotation speed, and load pressure may be appropriately selected depending on conditions such as the particle size of the fine powder, the amount of suspension in pure water, and the workpiece material ^. Conditions of ~1 Kg/cm ² and rotational speed of 10 m/min to 100 m/min are preferable. In addition, the particle size of the single or mixed fine powder is
If the particle size exceeds 0.1 μm, scratches will occur, so the particle size is preferably 0.1 μm or less.

In this invention, the thickness of the metal thin film consisting of the Cr thin film and the Fe-Al-Si alloy film is 0.2 μm or more, based on the magnetic properties of the alloy magnetic film, head productivity, and reliability.
30 μm, preferably 0.5 μm to 20 μm.

As mentioned above, the Cr thin film, which is a feature of this invention, is
In order to prevent mutual diffusion between the Fe-Al-Si alloy film and the ferromagnetic oxide and to promote crystal orientation in the initial layer of the Fe-Al-Si alloy film, we first adopted a bcc structure. In order to obtain the above effect, a thickness of at least 100 Å is required, but in order to prevent the Cr thin film itself from forming a pseudo gap, it is necessary to make the thickness 1000 Å or less. Furthermore, preferably 200
It ranges from Å to 500 Å.

In addition, the thickness of the Fe-Al-Si alloy film must be 0.1 μm or less for sufficient saturation recording on high coercive force media, and has high magnetic properties (magnetic permeability, coercive force).
In order to stably ensure this and obtain excellent workability, the thickness is 30 μm or less, preferably 10 μm or less.

Further, the metal thin film may be formed only on one of the magnetic core halves in the vicinity of the gap of a pair of magnetic core halves made of ferromagnetic oxide, or may be formed on both.

Furthermore, when the magnetic core halves are formed on both pairs of magnetic core halves, the film thickness structure of each metal thin film body may be within the above-mentioned film thickness range and does not need to be unified.

In order to improve the magnetic properties of the sendust film in the metal thin film body thus deposited in two layers, heat treatment may be performed as necessary.

Heat treatment may be performed after film formation and before processing, or may be performed after processing into the shape of the magnetic head, or may be performed during glass welding when bonding the magnetic head core halves. Heating for this purpose may be used in combination with heat treatment.

The temperature and time of the heat treatment should be appropriately selected to improve the magnetic properties of the metal alloy film, while also considering the difference in thermal expansion coefficient between the ferromagnetic oxide and the magnetic core half. The heat resistance of the ferromagnetic oxide that makes up the body, the ferromagnetic oxide and Cr thin film,
The selection should take into consideration the mutual diffusion between the three elements with the Fe-Al-Si alloy film, and should be selected appropriately depending on the ferromagnetic oxide used and the composition of the metal alloy film. .

Usually, the heat treatment temperature is preferably 300°C or higher and 800°C or lower. More preferably, the temperature is 400°C or higher and 600°C or lower. The time is preferably 1 minute or more and 10 hours or less, and more preferably 10 minutes or more and 2 hours or less.

The cooling rate also needs to be selected appropriately depending on the composition of the ferromagnetic oxide used and the metal alloy film, as well as the heat treatment temperature and time, but it is usually preferably 1°C/hr or more and 10000°C/hr or less. , a range of 50°C/hr to 600°C/hr is more preferable.

Any atmosphere may be used as long as it does not significantly deteriorate the magnetic properties of the metal alloy film and the ferromagnetic oxide, but vacuum, inert gas, or nitrogen gas is preferable.

DISCLOSURE OF THE INVENTION BASED ON THE DRAWINGS FIG. 1 is a perspective explanatory view of a composite magnetic head according to the present invention.

As shown in FIG. 1, the composite magnetic head according to the present invention has magnetic core halves 10 and 11 made of a ferromagnetic oxide such as Mn-Zn ferrite, which are processed without strain, and a portion near a magnetic gap 12. on the surface,
The Cr thin film 13, the ferromagnetic thin film 14, the Cr thin film 13', and the ferromagnetic thin film 14' are respectively deposited and formed by a vacuum thin film forming technique such as sputtering to form a multilayer structure. It is formed of a non-magnetic material 15 such as SiO ₂ deposited on a thin film, and also forms a window 16 for coil winding, and the pair of core halves 10 and 11 are joined by a glass 17. There is.

Example One main surface of a magnetic substrate made of Mn--Zn single-crystal ferrite was polished to a mirror surface using diamond powder, and then reverse sputtering was performed to finish the main surface into a highly accurate strain-free surface.

At this time, the roughness was measured to be 40 Å or less using a surface step measuring device (manufactured by Taylor Hobson). Further, the state of removal of the surface strain layer was confirmed by ellipsometry.

On the main surface of the above strain-free processed magnetic substrate,
A 99.9% Cr film was deposited to a thickness of 0.03 μm using an RF two-pole magnetron sputtering device, and a Fe-Al-Si film was further deposited to a thickness of 1.5 μm.

After the Fe-Al-Si film was deposited, heat treatment was performed at 800°C.

The sputtering conditions described above were an input power of 1 kW and an Ar gas pressure of 5 x 10 ^-3 Torr.

Cr film and Fe-Al-Si after heat treatment at 800℃
The reaction situation of the film was determined by
The results of the line image investigation are shown in Figure 2a.

For comparison, after finishing the Mn-Zn single-crystal ferrite surface into a highly accurate strain-free surface, a Fe-Al-Si film was deposited under the sputtering conditions described above.
After that, Fe−Al− was subjected to heat treatment at 800℃.
Fe−Al−
The results of an investigation using X-ray images of Al, which has a Si composition,
It is shown in Figure 2b.

Next, an Al ₂ O ₃ film for forming a magnetic gap was deposited on the substrate to a thickness of 0.1 μm using an RF two-pole magnetron sputtering device to obtain a three-layer composite magnetic substrate. Furthermore, a large number of track grooves for forming tracks and winding grooves for winding wires for recording and reproduction were formed.

Furthermore, the composite magnetic substrate is cut into multiple halves with predetermined dimensions, and the half with the winding groove and the half without the winding groove are glass bonded by vacuum heat treatment, and at the same time, a metal alloy film is formed. After improving its magnetic properties, it was sliced, processed to have a predetermined size and shape, and made into chips.

Next, as shown in FIG. 5, a composite head was formed and the electromagnetic conversion characteristics were measured.

For comparison, a composite head using only a conventional Fe--Al--Si film was also fabricated and its electromagnetic conversion characteristics were measured.

FIG. 6 is a schematic diagram of reproduction waveforms of the composite head according to the conventional method and the present invention, where a is the output from the magnetic gap, and b is the pseudo-gap due to the magnetic discontinuity between the sendust film and the magnetic core half. This is the output by

As a result of measuring the output ratio b/a, the b/a of the present invention is
0.02, b/a of the conventional method was 0.2, and it was confirmed that in the case of the head according to the present invention, the effect of the pseudo gap was significantly reduced to the extent that it was practically no problem, and it had good recording and reproducing characteristics. did it.

Furthermore, as a natural result, the waviness of the reproduction frequency characteristics of the composite head according to the present invention was significantly improved and was less than 1 dB.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a composite magnetic head according to the present invention. Figure 2 shows the reaction situation between the substrate ferrite and the thin film on its surface in the example.
It is a photograph showing the results of an investigation using an X-ray image of Al having a -Al-Si composition. FIGS. 3a, 3b and 4 are explanatory diagrams of a conventional composite magnetic head. FIG. 5 is a perspective view of the composite head. FIG. 6 is a schematic diagram of the output frequency characteristics of the magnetic head. DESCRIPTION OF SYMBOLS 10, 11...Magnetic core half, 12...Magnetic gap, 13...First magnetic film, 14...Second magnetic film, 15...Nonmagnetic material, 16...Window for coil winding, 17... ...Glass.

Claims (1)

[Claims] 1. In a composite magnetic head having a magnetic core mainly composed of ferromagnetic oxide and a magnetic metal material at least in the vicinity of the operating gap, a ferromagnetic oxide surface with a thickness of 100 Å to 1000 Å Cr
A composite magnetic head characterized by having a metal thin film body laminated in this order: a thin film and a Fe-Al-Si alloy thin film.