JPH0785288B2 - Magnetic head manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a magnetic head mounted on a video tape recorder (VTR) or the like, and more specifically, a magnetic gap vicinity is formed of a ferromagnetic metal thin film. The present invention relates to a method of manufacturing a so-called composite magnetic head in which most of the magnetic core is composed of a ferromagnetic oxide.

[Outline of Invention]

According to the present invention, in manufacturing a magnetic head, a step of forming a first kerf on a substrate made of a ferromagnetic oxide to form an inclined surface inclined at a predetermined angle with respect to an upper surface of the substrate, A step of forming second and third kerfs so as to be continuous with the first kerf at both end positions of the inclined surface, and a step of strengthening the upper surface of the substrate including the first, second and third kerfs. A step of forming a magnetic metal thin film, a step of filling a non-magnetic material on the ferromagnetic metal thin films formed in the first, second and third kerfs, and surface grinding from the upper surface side of the substrate A core block is created by the step of applying and the step of forming a fourth kerf for regulating the track width adjacent to the inclined surface, and these core blocks are joined together through a gap spacer at a predetermined position. Generated inside the above ferromagnetic oxide by cutting Suppresses a decrease in processing yield by the rack, it is an attempt is made to improve the electromagnetic conversion characteristics and processing characteristics.

[Conventional technology]

In the field of magnetic recording, high-density recording of information signals and higher frequencies are being promoted, and in response to this, ferromagnetic metal powders such as Fe, Co, and Ni are used as magnetic powders as magnetic recording media. In addition, so-called metal tapes and so-called vapor-deposited tapes in which a magnetic metal material is directly deposited on a base film by a vacuum thin film forming technique such as vapor deposition have been put into practical use.

By the way, since this kind of magnetic recording medium has high coercive force and residual magnetic flux density, the core material of the magnetic head used for recording / reproducing is required to have high saturation magnetic flux density and high magnetic permeability.

However, although a head using ferrite, which has been widely used in the past, has a high magnetic permeability, an excellent reproducing efficiency, and an excellent wear resistance, it has a low saturation magnetic flux density and has a limitation in increasing the recording density. On the other hand, a head using a ferromagnetic metal material such as an Fe-Al-Si alloy has a saturation magnetic flux density higher than that of ferrite, so that it can be sufficiently recorded on a high coercive force magnetic recording medium, but it is generally used. With the core thickness in the above-mentioned head shape, the effective magnetic permeability in the operating frequency region was low and a sufficient reproduction output could not be obtained.

Under such circumstances, the applicant of the present application has proposed, in Japanese Patent Application Laid-Open No. 58-250988, a composite type magnetic head capable of high-density recording on the metal tape or the like and at the same time obtaining a sufficient reproduction output.

This magnetic head, as shown in FIG. 8 and FIG.
A pair of magnetic core portions (31) and (32) formed of ferromagnetic oxide such as -Zn ferrite are formed by obliquely cutting the abutting surfaces of the magnetic core portions (31) and (32), respectively, and forming ferromagnetic metal thin films (31a) and (32a).
To form the ferromagnetic metal thin film formation surface (31a), (32a)
Ferromagnetic metal thin films (33) and (34) are adhered and formed on the upper surface, and the abutting surfaces of the ferromagnetic metal thin films (33) and (34) are used as a magnetic gap g, and track width regulating grooves (37) and
A non-magnetic material (3) is provided to secure sliding contact with the recording medium in the (38) and prevent wear of the ferromagnetic metal thin films (33) and (34).
It is composed by filling 5) and (36), and has excellent characteristics in terms of reliability, magnetic characteristics, wear resistance and the like.

[Problems to be solved by the invention]

By the way, in order to manufacture the above magnetic head, first,
As shown in FIG. (A), a substrate (11
The first kerf (112) is applied to 1) to form an inclined surface (112a) corresponding to the ferromagnetic metal thin film forming surface, and the ferromagnetic metal thin film (113) is formed on this inclined surface (112a). Put on. Then, as shown in FIG. 10 (B), the first kerf (11
The non-magnetic material (114) is melt-filled in the inside of 2) and the surface is ground to a predetermined depth from the surface to obtain the magnetic gap forming surface (115). Further, although not shown, it is common to form a core block by performing a second kerf processing for regulating the track width adjacent to the first kerf (112).

Usually, the ferromagnetic metal thin film (113) is formed by a vacuum thin film forming technique such as sputtering in order to obtain a uniform film quality, etc., and is formed from the upper surface (111a) of the substrate (111) to the inclined surface (112a). Is formed as a continuous film having a certain thickness. Therefore, at the time of this film formation, internal strain in the ferromagnetic metal thin film (113) or the ferromagnetic metal thin film (113) and the substrate (11)
Strain is more likely to occur due to the difference in thermal expansion coefficient from 1). In particular, this crack is caused by the ferromagnetic metal thin film (11
It becomes remarkable with the increase of the film thickness of 3), and it becomes a big obstacle when making a magnetic head having a wide track width Tw.

The influence of these strains on the substrate (111) is large, and, for example, in the above-mentioned surface grinding step, the first kerf (112)
Cracks (so-called cracks) h often occur along the edges, which is one of the causes of lowering the yield. The crack h is a serious problem in terms of head characteristics and processing characteristics.

For example, when forming a winding groove for coil winding on one core block, this forming groove may be chipped, or the machined surface may be scratched when the magnetic gap forming surface is mirror-finished.

Further, when the crack h remains in the completed magnetic head, the crack h acts as a pseudo gap and causes undulation (ripple) in the frequency characteristic of the reproduction output, or causes crosstalk, which deteriorates the electromagnetic conversion characteristic. Cause.

Under such circumstances, the present invention has been proposed, and an object of the present invention is to provide a method of manufacturing a magnetic head that is excellent in electromagnetic conversion characteristics and processing characteristics and that suppresses a decrease in yield due to cracks generated inside a ferromagnetic oxide. To do.

[Means for solving problems]

In order to achieve this object, a method of manufacturing a magnetic head according to the present invention is directed to a tilted surface which is formed by subjecting a substrate made of a ferromagnetic oxide to a first kerf processing and tilted at a predetermined angle with respect to the upper surface of the substrate. Forming the second and third kerfs so as to be continuous with the first kerf at both ends of the inclined surface, and the first, second and third kerfs. Forming a ferromagnetic metal thin film on the upper surface of the substrate including
1, a step of filling a non-magnetic material on the ferromagnetic metal thin film formed in the second and third kerfs, a step of performing surface grinding from the upper surface side of the substrate, and a step of adjoining the inclined surface. A core block is formed by a step of forming a fourth kerf for controlling the track width, and these core blocks are joined together through a gap spacer and cut at a predetermined position.

[Action]

As described above, according to the present invention, the second and third kerfs are formed so as to be continuous with the first kerf at both ends of the inclined surface serving as the ferromagnetic metal thin film forming surface, and then the ferromagnetic metal thin film is covered. As a result, the ferromagnetic metal thin film has a substantially discontinuous film structure at the second and third kerfs. Therefore, the internal stress applied to the ferromagnetic metal thin film is dispersed and the above-mentioned internal strain is reduced, so that the substrate does not crack.

〔Example〕

Next, a method of manufacturing a magnetic head to which the present invention is applied will be described in the order of steps with reference to the drawings. In the following embodiments, a so-called wide track magnetic head will be described as an example.

To manufacture a magnetic head according to the present invention, first, as shown in FIG. 1, the upper surface (1a) of a substrate (1) made of a ferromagnetic oxide such as Mn-Zn ferrite, that is, this substrate (1). At the joint surface when the magnetic core halves in
A plurality of first kerfs (2) having a substantially V-shaped cross section are formed in parallel with each other by a rotary grindstone over the entire width, and an inclined surface (2a) inclined at a predetermined angle θ with respect to the upper surface (1a) is formed. To do. In addition,
In this embodiment, the groove depth A of the first kerf (2) is 100 μm.
m.

The inclined surface (2a) corresponds to the surface on which a ferromagnetic metal thin film described later is formed, and the angle θ formed by the inclined surface (2a) and the upper surface (1a) that forms the magnetic gap is usually 20.゜ <
The angle θ is set to <80 °, but in order to make a wide track, the angle is set to 0 ° <θ <45 °, preferably 2 ° <θ <30 °. When the angle θ is 45 ° or more, it takes a long time to form a film for forming a wide track, and it is preferably less than 30 °. On the contrary, when the angle θ is 0 °, the magnetic gap and the inclined surface (2a) are located in parallel with each other, and the influence of crosstalk and the pseudo gap is large. Therefore, it is preferable to set the angle larger than 2 °. In this embodiment, the angle θ is set to 15 °.

Next, as shown in FIG. 2, a second kerf (3) and a third kerf are provided at both ends of the inclined surface (2a) so as to be continuous with the first kerf (2). (4) is formed. Examples of the method of forming the above-mentioned kerfs (3) and (4) include a method of forming a grindstone, a method of using a thin cutting wheel such as a plated grindstone, a laser processing method, and the like.

Here, the slopes (3a) and (4a) of the second and third kerfs (3) and (4) are inclined at a predetermined angle α with respect to the vertical direction of the upper surface (1a) of the substrate (1). It is an inclined surface. If the inclination angle α is too large, the internal stress of the thin film itself cannot be dispersed when forming the ferromagnetic metal thin film, which will be described later. Therefore, the thickness is appropriately set in consideration of the film thickness of the ferromagnetic metal thin film, the inclination angle θ, and the like. In this embodiment, the angle α is set to 8 °. On the other hand, the inclined surfaces (3b) and (4b) are inclined surfaces that are inclined at a predetermined angle β with respect to the vertical direction of the upper surface (1a) of the substrate (1). If this inclination angle β is too large, it is still impossible to disperse the internal stress of the ferromagnetic metal thin film.
Preferably, 0 ° <β <45 ° should be set. Further, in this embodiment, the groove depth B of the second and third kerfs (3), (4),
C is 150 μm and 50 μm respectively, and each kerf (3), (4)
The tip width D of each of the above was about 50 μm.

Then, as shown in FIG. 3, a ferromagnetic metal thin film is formed over the entire upper surface (1a) of the substrate including the first, second and third kerfs (2), (3) and (4). (5) is adhered and formed. In this embodiment, the ferromagnetic metal thin film (5) is formed to have a thickness of 30 μm.

At this time, although the ferromagnetic metal thin film (5) is formed with a sufficient film thickness on the inclined surface (2a) and the upper surface (1a), both ends of the inclined surface (2a) are steep (3).
Because of a) and (4a), it is formed extremely thin due to the so-called shadow effect. Therefore, the ferromagnetic metal thin film (5a) on the inclined surface (2a) and the ferromagnetic metal thin film (5b) on the upper surface (1a) are substantially discontinuous when viewed as a film structure. As a result, the ferromagnetic metal thin film (5)
Ability to add to each ferromagnetic metal thin film (5a),
Since the internal strain in (5b) is reduced, cracks will not occur in the substrate (1) in the subsequent processing (for example, surface grinding).

At present, as a means for eliminating the above-mentioned cracks, the head member, that is, the substrate (1), the ferromagnetic metal thin film (5), the non-magnetic material, etc. having the optimum thermal expansion coefficient should be selected. From the above, it can be said that the present invention is extremely effective, considering that cracks inevitably occur when the thickness of the ferromagnetic metal thin film is increased. In particular, when manufacturing a wide track magnetic head, the present invention brings about a great effect in consideration of increasing the thickness of the ferromagnetic metal thin film (5).

Here, the material of the ferromagnetic metal thin film (5) is a ferromagnetic amorphous alloy, a so-called amorphous alloy (for example, F
An alloy consisting of one or more elements of e, Ni, Co and one or more elements of P, C, B, Si, or Al, Ge, Be, Sn, I as the main component
Metals such as alloys containing n, Mo, W, Ti, Mn, Cr, Zr, Hf, Nb, etc.
Amorphous metalloid alloys, or metal-metal amorphous alloys containing transition elements such as Co, Hf, Zr and rare earth elements as main components), Sendust, Fe-Al-Si alloys, Fe-Al alloys, Fe- Si-based alloy, Fe-Si-Co-based alloy, N
Permalloy, which is an i-Fe-based alloy, may be mentioned, and its film forming method includes sputtering method, vacuum evaporation method, flash evaporation method, ion plating method, cluster
A vacuum thin film forming technique such as an ion beam method may be used. Although the ferromagnetic metal thin film (5) has a single layer structure in this example, it has a high wear resistance insulating film such as SiO ₂ , Ta ₂ O ₅ , Al ₂ O ₃ , ZrO ₂ or Si ₃ N _4. A plurality of layers may be formed through the layer. In this case, the number of laminated ferromagnetic metal thin films can be set arbitrarily.

Subsequently, as shown in FIG. 4, a non-magnetic material (6) is melt-filled in the first kerf (2) on which the ferromagnetic metal thin film (5) is formed, and then, as shown in FIG. Surface grinding is performed up to the position of the middle XX line to expose the end surface (5a) of the inclined surface (2a) on the upper surface of the substrate (1).

Here, since the internal strain of the ferromagnetic metal thin film (5) itself is reduced, the substrate (1) may be cracked or scratches may be generated on the ground surface during the surface grinding. Disappear. Therefore, the processing yield is improved.

Here, the surface of the ferromagnetic metal thin film (5) was previously coated with Si.
A non-magnetic material such as O ₂ or Cr may be sputtered to provide a protective film to prevent erosion and the like when the non-magnetic material (6) is melt-filled.

Next, as shown in FIG. 5, a fourth kerf (7) for regulating the track width is formed adjacent to the inclined surface (2a) on which the ferromagnetic metal thin film (5) is deposited. The pair of magnetic core blocks (10), (2
0) is obtained. In this embodiment, the track Tw is set to 90
It was about μm.

The fourth kerf (7) may have any shape, such as a polygonal shape as in this example, a substantially V shape, a semicircular shape, or the like. The track width Tw may be regulated by cutting the fourth kerf (7) so as to overlap with one edge (5c) of the ferromagnetic metal thin film (5).

Further, one of the pair of magnetic core blocks (10) and (20) created in the above process is used as the magnetic core block (2
For 0), as shown in FIG. 6, a groove is formed in a direction orthogonal to the first kerf (2) to form a winding groove (21) for winding the coil. Also in this step, there is no concern that the formation groove (21) will be chipped due to the dispersion of the internal stress of the ferromagnetic metal thin film (5).

Then, the joint surface (10a) of the magnetic core block (10)
Alternatively, a gap spacer is attached to at least one of the joint surfaces (20a) of the magnetic core blocks (20), and as shown in FIG. 7, these magnetic core blocks (10), (20)
Are abutted so that the end faces (5a) of the ferromagnetic metal thin film (5) are aligned with each other, and fusion-bonded with a non-magnetic material (9) such as glass, and at the same time, the fourth kerf (7). The inside is filled with the non-magnetic material (9).

As the gap spacer, SiO ₂ , ZrO ₂ , Ta ₂ O
₅ , Cr, etc. are used. Further, in this manufacturing process, the filling of the non-magnetic material (9) into the fourth kerf (7) is not performed at the same time as the joining of the magnetic core blocks (10) and (20). In the step shown, the non-magnetic material (9) may be filled in the fourth kerf (7) in advance, and only the core blocks (10) and (20) may be joined in the step shown in FIG.

Finally, after slicing was performed at the positions of the YY line and the Y'-Y 'line in FIG. 7 to cut out a plurality of head chips, the magnetic recording medium contact surface was cylindrically polished and the slicing process was performed. The magnetic head shown in FIG. 9 is completed. At this time, a magnetic head for azimuth recording can be prepared by inclining the slicing direction with respect to the magnetic core blocks (10) and (20) with respect to the abutting surface.

In the magnetic head shown in FIGS. 8 and 9, the magnetic core portions (31) and (32) are made of a ferromagnetic oxide such as Mn-Zn.
It is made of ferrite and these magnetic core parts (31), (3
Inclined surfaces (31a), (32a) with the joining surface of 2) cut away diagonally
Includes a high-permeability alloy, for example, continuously from the front gap forming surface to the back gap forming surface.
Ferromagnetic metal thin film (33), (3) Fe-Al-Si alloy film
4) is deposited and formed by the vacuum thin film forming technique, and is constituted as magnetic core halves (I) and (II), respectively. Then, these magnetic core halves (I) and (II) are butted against each other via a gap spacer such as SiO ₂ to obtain a predetermined track width Tw.
The contact surfaces of the ferromagnetic metal thin films (33) and (34) that have been surface-ground up to this point are configured to form the magnetic gap g.

Here, one magnetic core half (I) of this magnetic head uses one magnetic core block (10) as a base material, and the other magnetic core half (II) uses the core block (20) as a base material. I am trying. Therefore, the ferromagnetic metal thin film (33), (3
4) corresponds to the ferromagnetic metal thin film (5), the non-magnetic material (35) corresponds to the non-magnetic material (6), and the non-magnetic material (36) corresponds to the non-magnetic material (9).

As described above, in the magnetic head manufactured by the manufacturing method of the present invention, the stress generated at the time of forming the ferromagnetic metal thin film (5) is continuous with the first kerf (2) at both end positions of the inclined surface (2a). The second and third kerfs (3) and (4) formed on the substrate (1) are dispersed to reduce the internal stress applied to the substrate (1). No cracks will occur. Therefore, the crack does not act as a pseudo gap, or the frequency characteristic of the reproduction output does not undulate, so that the electromagnetic conversion characteristic is significantly improved. Further, when the magnetic gap forming surface is mirror-finished, the processed surface is not scratched, and the processing yield is greatly improved.

The specific embodiment of the present invention has been described above, but the present invention is not limited to this embodiment. For example,
A magnetic head in which the inclination angle θ of the inclined surface that forms the ferromagnetic metal thin film is set relatively large, a magnetic head in which the ferromagnetic metal thin film is formed only in the vicinity of the magnetic gap,
The present invention can be applied to various magnetic head manufacturing methods such as a magnetic head in which a ferromagnetic metal thin film is bent at a position away from the magnetic gap without departing from the spirit of the present invention.

〔The invention's effect〕

As is clear from the above description, according to the manufacturing method of the present invention, the first surface having the inclined surface serving as the surface on which the ferromagnetic metal thin film is formed is formed.
The second and third kerfs are formed so as to be continuous with the kerf of
After that, by depositing a ferromagnetic metal thin film, the film structure of the ferromagnetic metal thin film is made substantially discontinuous, and the internal strain of the thin film applied to the substrate is reduced, so that the substrate is not cracked in the subsequent steps. It never happens. Therefore, the processing characteristics and the processing yield are significantly improved.

As a result, it is possible to provide a magnetic head which is excellent in electromagnetic conversion characteristics, in which cracks do not remain in the obtained magnetic head, there is no undulation in the pseudo gap and the frequency characteristic of the reproduction output.

In particular, the present invention is suitable for manufacturing a so-called wide track magnetic head in which the ferromagnetic metal thin film has a relatively thick film structure.

[Brief description of drawings]

1 to 7 show an example of a method of manufacturing a magnetic head according to the present invention in the order of the steps, and FIG.
FIG. 2 is a schematic perspective view showing the kerf cutting step of FIG. 2, FIG. 2 is a schematic perspective view showing the second and third kerf cutting steps, and FIG. 3 is a schematic perspective view showing the ferromagnetic metal thin film forming step. Is a schematic perspective view showing a non-magnetic material filling step and a surface grinding step, FIG. 5 is a schematic perspective view showing a fourth cutting groove cutting step, and FIG. 6 is a schematic perspective view showing a winding groove forming step. The figure is a schematic perspective view showing a slicing process. FIG. 8 is an external perspective view showing an example of a magnetic head, and FIG. 9 is an enlarged plan view of an essential part showing a contact surface of the magnetic recording medium. FIG. 10 shows a conventional magnetic head manufacturing method.
FIG. 10 (A) is a schematic sectional view showing a ferromagnetic metal thin film forming step, and FIG. 10 (B) is a schematic sectional view showing a surface grinding step. 1 ... Substrate 2 ... First kerf 2a ... Sloping surface 3 ... Second kerf 4 ... Third kerf 5 ... Ferromagnetic metal thin film 6,9 ... Non-magnetic material 7 ... … Fourth kerf 10,20 …… Core block

Claims (1)

[Claims] 1. A step of forming a sloping surface which is inclined at a predetermined angle with respect to an upper surface of the substrate by subjecting a substrate made of a ferromagnetic oxide to a first kerf, and at both end positions of the sloping surface. Forming second and third kerfs so as to be continuous with the first kerf, and forming a ferromagnetic metal thin film on the upper surface of the substrate including the first, second and third kerfs A step, a step of filling a non-magnetic material on the ferromagnetic metal thin films formed in the first, second and third kerfs; a step of performing surface grinding from the upper surface side of the substrate; Fourth for regulating track width adjacent to surface
And a step of forming a kerf, the core blocks are formed, the core blocks are joined to each other through gap spacers, and the core blocks are cut at a predetermined position.