KR910009026B1 - Magnetic head and manufacturing method - Google Patents

Abstract

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Description

Magnetic Head and Manufacturing Method Thereof

1 is a perspective view of a magnetic head according to the present invention.

2 is a cross-sectional view after final processing as well.

3 and 4 are views for explaining the preparation of the monocrystalline-polycrystalline ferrite binder of the present invention.

5a to (h) sequentially show a step of manufacturing the magnetic head according to the present invention, (a) to (g) is a perspective view, and (h) is a front view.

6 and 7 are graphs showing the effect of the present invention.

8 is a perspective view of a conventional magnetic head.

* Explanation of symbols for main parts of the drawings

11: Half core (Half core block) 11a: Butt surface

11b: single crystal ferrite surface 11c: polycrystalline ferrite

12: magnetic gap 13: thin film attachment groove

14: magnetic metal film d: thickness of the polycrystalline ferrite layer

The present invention forms a thin film attachment groove inclined with respect to the abutment surface of a pair of half-core abutments made of ferrite, and uses a magnetic gap in which the junction surface of the metal magnetic film attached to the thin film attachment groove is a magnetic gap. It's about the head.

As the magnetic head core of the type in which the magnetic gap of the metal magnetic film is inclined, the one shown in FIG. 8 is conventionally proposed. That is, the thin film attachment groove 13 inclined with respect to the magnetic gap 12 which should be formed, respectively, is formed in the up-down relationship in the abutment surface of a pair of half core 11 which consists of single crystal ferrite, and this thin film adhesion groove is A magnetic metal film 14, such as sender, is attached to 13 by thin film forming means such as sputtering and vapor deposition. The track width restricting grooves 15 are formed on both sides of the core 11 at the abutting surface of the half core 11 in a point symmetrical relationship with respect to the center of the magnetic gap 12. The track width restricting groove 15 is arranged to cut one end near the mating surface of the thin film attachment groove 13. The magnetic gap 12 is formed in the gap between the end faces of the metal magnetic film 14 attached to the thin film attachment groove 13. The nonmagnetic oxide bonding material (hereinafter simply referred to as glass) 16, such as glass, is filled in the space of the metal magnetic film 14 having a substantially V-shape and the space of the track width restricting groove 15 to thereby provide a pair of half cores. (11) is bonded and fixed. The coil winding hole 17 is formed in one half core 11. The reason for using the single crystal ferrite as the half core 11 is that since the single crystal ferrite has excellent mechanical properties and wear resistance, the magnetic head core using the single crystal ferrite can form track processing with high precision and use for a long time. Because can withstand enough.

However, the ferrite magnetic head in which the core is formed of single crystal ferrite generates noise peculiar to the single crystal ferrite. Therefore, as a magnetic head for video for a high quality video recorder in recent years, low S / N ratio (signal noise ratio) has become a problem. The cause of this noise is said to be that when the magnetic body is made of a single crystal material, there are very few magnetic domain fixing elements in the magnetization, and the movement of the magnetic wall is easily generated.

On the other hand, the polycrystalline ferrite core used has a crystal grain boundary because the magnetic material is a polycrystalline material, and since it acts as an element for fixing the magnetic domain, there is no noise generation as in the case of the single crystal ferrite, and the high S / It is possible to form a magnetic head which can be used sufficiently even in a device where the N ratio is required. However, the polycrystalline ferrite as a core may have a dense structure such as a high-temperature press material and a hot hydrostatic press material, even if it is used as a contact type magnetic head. As a result, part of the grain boundary is dropped and becomes unusable in a relatively short time. In addition, there is a drawback that the output characteristics cannot be obtained because the crystal axes near the gap are random.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and the portion on the side where the magnetic medium of the core contacts is composed of single crystal ferrite and other portions of polycrystalline ferrite to provide a magnetic head having a high S / N ratio. It aims to do it.

In the magnetic head according to the present invention, in the magnetic head in which a metal magnetic film is provided on a mating surface of a pair of half cores, the portion on the side where the magnetic medium of the half core contacts is composed of single crystal ferrite, and the other portion is made of polycrystalline ferrite. And the thickness of the said single crystal ferrite is set to 60 micrometers or less. The thickness of the single crystal is limited to 60 µm or less because when the thickness becomes more than this, the amount of noise generated increases, making it difficult to obtain a sufficient S / N ratio.

According to the present invention, since the extremely thin layer of the surface in contact with the magnetic medium of the core is made of polycrystalline ferrite, the influence on the generation of noise due to the presence of this layer is very small, and the other part is made of polycrystalline ferrite. Therefore, the S / N ratio is considerably better than when the whole is made of single crystal. On the other hand, in this case, since there is no peeling at the grain boundary and the wear resistance is high, it is prolonged in the service period and strong against mechanical processing. Therefore, the precision of track processing can be increased.

As a method of manufacturing such a magnetic head, a half having a region having a thickness of a single crystal and a polycrystal is brought into contact with a single crystal ferrite and a polycrystalline ferrite, and the single crystal ferrite is grown on the polycrystal side by solid phase reaction by heating. A method of forming the core block is suitable. In this case, by adjusting heating temperature and reaction time, the thickness of the single crystal side can be controlled to 60 µm or less.

Hereinafter, an embodiment of the magnetic head according to the present invention will be described with reference to FIGS. 1 to 7. 1 and 2 show an embodiment of the present invention. FIG. 1 shows a magnetic head before processing a contact surface to a magnetic medium, and FIG. 2 shows a cross section of the magnetic head after processing. In addition, since the basic shape of a magnetic head itself is the same as that of the prior art example, it abbreviate | omits description. In this embodiment, the track width regulating groove 15 formed by the half core 11 formed of the single crystal ferrite layer 11b and the polycrystalline ferrite 11c on the mating surface 11a (see FIG. 5a), and An erosion prevention film 20 made of a single layer film of an activated metal or a metal oxide or a laminated film of an active metal and a metal oxide is interposed between the glass 16 filled in the track width restricting groove 15. This prevents the erosion of the magnetic metal film 14 by the glass 16. The erosion prevention film 20 may be composed of a composite of an activated metal metal oxide. In this case, as active metal, and the like Cr, Ti, Zr, Hf preferred, as the metal oxides are preferred, such as SiO _2, Ta ₂ O _5. The glass 16 is filled in the V-shaped space of the magnetic metal film 14 attached to the thin film attachment groove 13, but the erosion prevention film 20 is formed of the magnetic magnetic film 14 and the glass 16. It is interposed in between.

Next, a method of manufacturing the magnetic head according to the present invention will be described.

3 and 4 show a method for producing a single crystal-polycrystalline ferrite conjugate used in the present invention, 1 is a Mn-Zn-based single crystal ferrite plate used as a seed, and 2 is a single crystal having the same composition. The lower polycrystalline ferrite block, 3 is the interface between the single crystal ferrite plate 1 and the polycrystalline ferrite block 2. The joining surfaces of the two fellites 1 and 2 are wrapped with SiC abrasive grains (2000 mesh, 4000 mesh), and then mirror polished with a diamond having a particle diameter of 3 µm. After applying lean acetic acid to both clean surfaces of the joint, they are bonded to each other to form a bonded body, which is placed in a shape and perpendicular to the joint surface in an atmosphere in which nitrogen gas flows. Pressurize to a high temperature (temperature 1250 ° C., pressure 30 kg / cm 2, treatment time 30 minutes). After the high temperature press, the bonded body was subjected to pressurized heat treatment by applying a pressure of 1000 kg / cm 2 at a temperature of 1320 ° C. for 3 hours by a hot hydrostatic press (HIP) method. As a result, the bonding interface 3 induces a solid phase reaction with each other, and single crystals are grown on the polycrystalline ferrite 2 side to form a single crystallization region 4. This is cut into predetermined blocks to form a half core block.

In the above process, the thickness of the single crystal layer formed by the solid phase reaction is controlled by adjusting the temperature and the treatment time in the hot hydrostatic press method.

Next, a manufacturing process of the magnetic head using the half core block will be described with reference to FIG. In the processing of the half-core block 11, the single crystal ferrite 11b is positioned in advance on the contact surface side with the magnetic medium. In the first step, a wedge-shaped thin film attachment groove 13 is formed in the mating surface 11a of the half core block 11 (Fig. 5A). In the second step, the magnetic metal film 14 made of sender or the like is attached to the thin film attachment groove 13 by sputtering or the like (FIG. 5B). In the third process, the magnetic metal film 14 is lap polished so that only the magnetic metal film 14 in the thin film attachment groove 13 is left (Fig. 5C). In the fourth step, the track width restricting groove 15 is formed to be adjacent to the thin film attachment groove 13 to which the magnetic metal film 14 is attached, and to cut a part of the thin film attachment groove 13 (5d). Degree).

In the following fifth step, the erosion prevention film 20 is formed in the magnetic metal film 14 and the track width restricting groove 15 by means of thin film attachment means such as sputtering (FIG. 5E). The erosion prevention film 20 may be formed of a single layer of any one of activated metals such as Cr, Ti, Zn, and Hf or metal oxides such as SiO ₂ and Ta ₂ O ₅ with a film thickness of 0.4 to 2 μm. And a metal oxide may be formed by lamination. In the case of lamination, for example, Cr is sputtered first at a film thickness of 0.4 to 2 탆, and then SiO ₂ is sputtered at a film thickness of 0.4 to 1 탆 from above. In addition, the erosion prevention film 20 may be formed by the composite of the activated metal film and the metal oxide. In this case, for example, it is formed by sputtering a composite sintered target of Cr and SiO ₂ . The erosion prevention film 20 as described above is made of glass 16 such as ferrite or the like, which is the material of the half-core block 11, or sender, which is the material of the magnetic metal film 14, during the fusion cleaning of the glass 16, which is the next step. ) To prevent erosion. After the formation of the erosion prevention film 20 is completed in the fifth step, the glass 16 is melt-filled on the erosion prevention film 20 in the sixth step. Thus, the glass 16 is filled in the space between the magnetic metal film 14 and the erosion prevention film 20 via the erosion prevention film 20 (FIG. 5f). In the seventh step, the glass 16 is lap-polished by low stone until the bonding surface 14a of the magnetic metal film 14 is exposed to a predetermined amount, thereby determining the gap width of the magnetic gap 12. (Figure 5g). In the eighth step, the pair of half-core blocks 11 whose polishing of the bonding surface 14a is finished are positioned to face each other by positioning the bonding surface 14a to be the magnetic gap 12, and the two half-core blocks 11 The joints are joined to form a bonded core block (Fig. 5h). The heterojunction co-block is cut to a predetermined width along the cutting line AB to form a magnetic head material shown in FIG. 1, and its magnetic medium contact surface is processed into an arc surface to obtain a magnetic head as shown in FIG.

Hereinafter, the effect of this invention is demonstrated more concretely.

FIG. 6 shows measured values of perturbation noise when the thickness (denoted by d in FIG. 2) of the single crystal ferrite layer 11b of the magnetic head in the present invention is changed. It can be seen that the amount of is almost proportional. In this case, the smaller the value of d, the smaller the perturbation noise. However, in order to use this magnetic head in a high-quality video tape recorder as described above, the perturbation noise is preferably 7 dB or less, and for this purpose, it is required to be 60 m or less.

FIG. 7 shows the result of measuring the output when the signal is input to the magnetic tape using a magnetic head and is reproduced under the same conditions in the case where d is changed as described above. You can see the output tends to increase. This is because, as described above, the influence of the dispersion of the crystal axes in the polycrystal near the gap is reduced by the presence of the single crystal ferrite. It can be seen that the degree of deterioration is small compared to the above-mentioned amount of perturbation noise and the effect of improvement is large by reducing d.

As described above, in the magnetic head of the present invention, since the portion of the surface side in contact with the magnetic medium of the half core is composed of single crystal ferrite and other portions of polycrystalline ferrite, the thickness of the single crystal ferrite layer is 60 占 퐉 or less. Both the mechanical properties of the contact surface with the magnetic medium and the good magnetic properties can be obtained at the same time. That is, since the single crystal layer is thin, the generation of perturbation noise as the crystal can be suppressed, and the S / N ratio can be maintained enough to be used for a high quality video tape recorder or the like, thereby obtaining a clear image. In addition, due to the high wear resistance of the single crystal layer, it is possible to extend the life of the magnetic head and to improve the accuracy of track processing, thereby providing a magnetic head without dimension irregularities, and to obtain high output characteristics compared to the polycrystalline magnetic head. There is a number.

In addition, since the half-core single crystal and polycrystal two regions are manufactured by the single crystal growth method by solid phase reaction, it is most suitable for preparing a core using two regions as in the present application. Easy to control It also has a remarkable effect such as no increase in the magnetoresistance at the interface between the two regions.

Claims (2)

In a magnetic head in which a metal magnetic film is formed on a mating surface of a pair of ferrite half cores, and the metal magnetic film is opposed to the magnetic gap, a portion on the surface side where the magnetic medium of the half core is in contact with each other has a thickness of 60 μm or less. A magnetic head comprising a single crystal ferrite layer and other portions made of polycrystalline ferrite. The single crystal ferrite and the polycrystalline ferrite are brought into contact with each other, and the single crystal ferrite is grown on the polycrystalline side by solid phase reaction by heating to form a pair of half core blocks having two regions of single crystal and polycrystal, and the pair of half After attaching the magnetic metal film to the abutment surface of the core block, a track width regulation groove is formed so that the single crystal region is the contact surface side of the magnetic medium. Then, the glass is melt-filled in the track width regulation groove, and then the abutment is performed. The surface is polished to expose the end face of the metal magnetic film that becomes the magnetic gap, and then the half core blocks are joined to the end faces of the metal magnetic film, and then the joint core blocks are cut to a predetermined width. Method of manufacturing a magnetic head.

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