JPH05250630A - Magnetic head - Google Patents

Abstract

PURPOSE:To mass-produce magnetic heads in a high yield even in the case of <=0.4mum effective gap length and to commercially provide high performance magnetic heads in large quantities at a low cost. CONSTITUTION:A pair of magnetic cores obtd. by forming multilayered films 10, 10' consisting of alternately laminated magnetic alloy films 11, 11' having high saturation magnetic flux density and inter-laminar insulating films 12, 12' on substrates 13, 13' are placed opposite to each other with a narrow magnetic gap (g) in-between to form a magnetic path. The insulating films 12, 12' are formed with a multiple oxide or an oxide mixture contg. at least vanadium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head mounted on a magnetic reproducing apparatus such as a VTR, and more particularly to a high performance magnetic head excellent in mass productivity and reliability.

[0002]

2. Description of the Related Art In recent years, in order to increase the recording density of magnetic recording / reproducing apparatus, it has become possible to increase the holding power of information recording media, widen the recording / reproducing frequency, and speed up recording tapes and disks. Therefore, it is becoming impossible to follow the conventional ferrite head. For this reason, magnetic films made of Co-based amorphous alloys, sendust-based alloys, Fe-C-based materials, Fe-N-based materials, or the like, which have higher saturation magnetic flux densities than ferrite, have come to be used or attracted attention. The saturation magnetic flux density of these magnetic films is about twice as high as that of ferrite. A magnetic head using such a magnetic film effectively magnetizes a magnetic recording medium having a high coercive force at a short recording wavelength, thereby achieving wide band magnetic recording. Can be done.

In consideration of practical use, such a magnetic head is constructed by a magnetic alloy film having a large saturation magnetic flux density Bs only in the vicinity of the working gap of the head core where magnetic saturation is a problem, and other parts of the head core are A magnetic head made of a composite material composed of ferrite or the like, which has excellent wear resistance, has been proposed, but since the magnetic alloy film has a low electric resistance, there is a problem that the reproduction output is reduced due to leakage current loss in the high frequency range. Occurs. In order to solve this problem, as disclosed in Japanese Patent Application Laid-Open No. 60-234209, there has been proposed a magnetic head in which the magnetic alloy film is a multilayer film with an interlayer insulating film interposed therebetween.

The first example is shown in FIG. Figure 1 (a)
Is a top view, and FIG. 1B is a side view. That is, the magnetic alloy multilayer film 10 forming the main magnetic circuit of this magnetic head,
10 'is a magnetic alloy film 11 having a high magnetic permeability and a high saturation magnetic flux density,
11 'and the interlayer insulating films 12 and 12' are connected to the non-magnetic holding material 13,
It has a multi-layered structure in which it is alternately laminated on 13 ', and is abutted via an operating gap g to form a magnetic path C.
As the material of the magnetic alloy film, a Co-based amorphous film, a sendust alloy film, or the like is used with a thickness of several μm to several tens of μm per layer, and the interlayer insulating film is formed of SiO 2.
A film of ₂ or Al ₂ O ₃ is used with a thickness of several hundred Å to several μm per layer.

A second example is shown in FIG. 2A is a top view and FIG. 2B is a side view. This magnetic head has a magnetic alloy multilayer film 10, on a high magnetic susceptibility ferrite or non-magnetic holding material 13, 13 'formed in a V shape.
10 'is formed into a magnetic core half body, and the magnetic core half bodies are butted against each other through an operating gap g, and the low melting glass 1
The structure is such that they are joined at 4, 14 '.

In both the first and second examples, a magnetic head having good high frequency characteristics can be obtained by forming the magnetic alloy film in multiple layers.

[0007]

In the magnetic head according to the above-mentioned prior art, the magnetic core halves are butted and joined together when the working gap g is formed. It is necessary to lap the cross section of the alloy multilayer film. However, SiO ₂ or Al ₂ O ₃ is used for the interlayer insulating film of the magnetic alloy multilayer film according to the conventional technique.
Since a material having a hardness higher than that of the alloy film is used, when the flat lap is performed, the interlayer insulating film exposed on the wrap surface protrudes more than other alloy film, which causes a problem when the magnetic cores are butted against each other. However, there is a problem that a highly accurate effective gap length cannot be obtained.

The above problems will be described in more detail below.

The view shown in FIG. 3 is an enlarged view of the portion A in FIG. Only one magnetic core is shown for clarity. In this figure, the B surface shows a flat lap surface, but when the B surface was measured with a roughness meter after the wrapping was completed, it was found that the interlayer insulating film 12 protruded from the magnetic alloy film 11 by t. It has been revealed that the value of t varies widely from 100Å to 500Å and varies depending on the measurement location and the manufacturing lot, which causes defective effective gap length. The cause of the interlayer insulating film protruding beyond the magnetic alloy film is the difference in Vickers hardness. Table 1 shows the Vickers hardness of the magnetic alloy film (eg, Co—Nb—Zr amorphous film) and the interlayer insulating film (eg, SiO ₂ or Al ₂ O ₃ ).

[0010]

[Table 1]

The Vickers hardness of the magnetic alloy film is about 700-
Although it is 800, the interlayer insulating film is about 900 to 1100, and the magnetic alloy film having a small Vickers hardness is first lapped during the planar wrapping, and the interlayer insulating film is in a protruding state. Since the value of the protrusion amount t is 100 Å to 500 Å, there is not much problem in the case of a magnetic head having a large effective gap length, but it becomes a serious problem in the case of a head having a small effective gap length.

FIG. 4 shows the results of examining the relationship between the target effective gap length and the defect rate of the effective gap length of the prototype, in which a magnetic head was actually manufactured as a prototype. Here, the shape of the prototype magnetic head used is that shown in FIG. 2, and the defect rate is judged to be non-defective if it is within ± 10% of the target effective gap length, and other than that. It was judged to be defective. According to FIG. 4, it became clear that the defective rate drastically increases when the effective gap length becomes 0.4 μm or less.

This will be a serious problem in providing a magnetic head for high density recording in the future. That is, in order to perform high-density recording, it is necessary to reduce the effective gap to enable recording / reproducing of short wavelength signals.
More specifically, the current NTSC-VHS video head has an effective gap length of about 0.5 μm, while the higher density recording of an NTSC-VHS video head has an effective gap length of about 0.3 μm. Also NTSC 8m
/ MVTR head has an effective gap length of around 0.25 μm, and NTSC-high band 8 with higher density recording
Head for m / mVTR and PAL-high band 8m / mV
The effective gap length of the TR head needs to be 0.2 μm or less.

To summarize the above, it is difficult to mass-produce magnetic heads having an effective gap length of 0.4 μm or less with a high yield in the magnetic head according to the prior art, and a magnetic head capable of high density recording is inexpensive. And it became clear that it is impossible to provide a large amount to the market.

An object of the present invention is that the effective gap length is 0.4.
Mass production with a good yield even for magnetic heads of μm or less,
It is to provide a high-performance magnetic head to the market inexpensively and in large quantities.

[0016]

In order to achieve the above object, in the present invention, a complex oxide or oxide mixture containing vanadium element is used as a material for the interlayer insulating film. As a result, the Vickers hardness of the interlayer insulating film can be made smaller than that of the magnetic alloy film, the protrusion of the interlayer insulating film can be prevented during flat lapping, and a magnetic head having an effective gap length of 0.4 μm or less can be manufactured with high yield. It becomes possible.

The interlayer insulating film according to the present invention preferably further contains at least phosphorus element. Further, it is preferable that the interlayer insulating film contains at least one element selected from the group consisting of antimony, lead, tellurium, barium, thallium and arsenic.

[0018]

The present invention makes the interlayer insulating film a composite oxide or an oxide mixture containing at least vanadium element so that the Vickers hardness of the interlayer insulating film is smaller than the Vickers hardness of the magnetic alloy film, and when the surface is lapped. It is possible to prevent the interlayer insulating film from protruding. This eliminates obstacles when the magnetic cores are butted, and a magnetic head having an effective gap length of 0.4 μm or less can be stably obtained.

Here, it is preferable that the complex oxide or the oxide mixture contains another oxide in addition to the vanadium element. The reason is to prevent the Vickers hardness from becoming too small. Specifically, for example, it is a composite oxide or an oxide mixture of SiO ₂ and an oxide of the above-mentioned element which has been conventionally used as an interlayer insulating film. However, it is not necessary to be particular about SiO _2, and any substance may be used as long as it can form a reliable interlayer insulating film. That is, S
Any substance having a melting point and hardness equal to or higher than that of iO ₂ can be used, and examples thereof include Al ₂ O ₃ and ZrO ₂ .

The Vickers hardness of the interlayer insulating film obtained by the present invention is about 400 to 600, which is a value that is appropriately smaller than the Vickers hardness of the magnetic alloy film. With a Vickers hardness of this level, no film protrusion occurs during flat lapping, and unnecessary uneven wear does not occur during sliding of the magnetic tape, so that a good interlayer insulating film can be obtained.

The interlayer insulating film preferably contains phosphorus element. The reason is to promote vitrification of vanadium element and prevent crystallization.

Furthermore, it is preferable that the interlayer insulating film contains at least one element selected from the group consisting of antimony, lead, tellurium, barium, thallium and arsenic. The reason is that among these elements, antimony is used to improve water resistance,
Elemental elements of thallium and arsenic Lead, tellurium and barium elements to improve vitrification stability, lead and barium and arsenic elements to improve chemical stability, barium element to improve mechanical properties,
This is because the elements of lead, tellurium, and thallium are effective in controlling the coefficient of thermal expansion.

[0023]

EXAMPLES The present invention will be described with reference to examples.

First, several materials used for the interlayer insulating film were made as prototypes. The compositions of these are shown in Table 2.

[0025]

[Table 2]

The composition in the table is not the interlayer insulating film itself, but the target for sputtering for forming this. The target for sputtering the No. 1 interlayer insulating film in Table 2 was melt-formed SiO ₂ glass (quartz glass).
Was used. The sputtered film formed using this target has been frequently used conventionally as an interlayer insulating film of a magnetic head, and is used for comparison with other materials. For other No. ₂ to No. 5 interlayer insulating films, SiO ₂
Glass (quartz glass) powder, Al ₂ O ₃ powder or ZrO ₂
The powder, the V ₂ O ₅ powder, the Sb ₂ O ₃ powder, and the PbO powder were mixed and molded, and a target obtained by sintering by hot pressing was used. The sputtered film formed by using such a target exists in the state of a complex oxide or an oxide mixture composed of each element constituting the target. The heat resistance of these sputtered films is good up to 750 ° C., which is higher than the heat resistant temperature of the magnetic alloy film shown in Table 1, so that a stable interlayer insulating film can be formed. When the Vickers hardness of these sputter targets was measured, the SiO _{2 of} No. 1 was 10
Although it showed a large value of 50, No. 2 according to the present invention
~ No.5 target has Vickers hardness of 420 ~ 58
The value was 0, which was an appropriately smaller value than the Vickers hardness of the magnetic alloy film.

Next, a magnetic head using the above No. 1 to No. 5 materials for the interlayer insulating film was manufactured as a prototype, and the relationship between the target effective gap length and the defective rate of the effective gap length of the prototype was examined. Is shown in FIG. Here, the shape of the prototype magnetic head used is that shown in FIG. 2, and the defect rate is judged to be non-defective if it falls within ± 10% of the target effective gap length, and other than that. Was determined to be defective. According to it, in the magnetic head using No. 1 or the conventional material for the interlayer insulating film, the defective rate sharply increases when the effective gap length becomes 0.4 μm or less, but No. 2 to No.
In the magnetic head using the material of No. 5 as the interlayer insulating film, it has been clarified that the defective rate does not increase so much even when the effective gap length is 0.4 μm or less. Further, in the middle of the manufacturing process of each of the prototype magnetic heads, the flat lap surface, that is, the surface B in FIG.
In the magnetic head using the conventional material for the interlayer insulating film, the value of t in FIG. 3 was 100Å to 500Å, but the materials of No. 2 to No. 5 in the present invention were used for the interlayer insulating film. The magnetic heads used each had a value of t of almost 0. This qualitatively agrees with the effective gap length defect rate of 0.4 μm or less of each of the prototype magnetic heads.

Further, each of the prototype magnetic heads was attached to a rotary drum and mounted on a VHS type VTR to carry out a magnetic tape running test. No. 1 to No. 5 materials were used as an interlayer insulating film. The magnetic head of No. 1 did not cause unnecessary uneven wear, output deterioration, scratches on the head sliding surface, etc. at all during traveling. Therefore, it has been clarified that the magnetic head according to the present invention has no problem in practical use as compared with the magnetic head according to the prior art.

[0029]

According to the present invention, a pair of magnetic cores having a multilayer film in which a magnetic alloy film having a high saturation magnetic flux density and an interlayer insulating film are alternately interposed are formed on a support through a minute magnetic gap. In a magnetic head having a magnetic path formed by facing each other, the interlayer insulating film is made of a complex oxide or an oxide mixture containing at least a vanadium element, so that the Vickers hardness of the interlayer insulating film is made to be the magnetic alloy film. It is possible to prevent the interlayer insulating film from projecting when the flat surface is lapped by making the hardness smaller than the Vickers hardness of. This eliminates obstacles when the magnetic cores are butted, and a magnetic head having an effective gap length of 0.4 μm or less can be stably obtained. Further, the magnetic head thus obtained does not cause any problem in mounting by the VTR, and has the same reliability as the conventional magnetic head.

As described above, according to the present invention, a high-performance head capable of high-density recording, which has been difficult to mass-produce by the prior art, can be provided to the market inexpensively and in large quantities.

[Brief description of drawings]

FIG. 1 is a diagram showing a first example of a magnetic head common to the prior art and the present invention.

FIG. 2 is a diagram showing a second example of a magnetic head common to the prior art and the present invention.

FIG. 3 is an enlarged view of a portion A of the magnetic head in FIG.

FIG. 4 is a graph showing the relationship between the target effective gap length and the defect rate of a conventional magnetic head.

FIG. 5 is a graph showing the relationship between the target effective gap length and the defect rate of the magnetic head used in the example according to the present invention.

[Explanation of symbols]

10, 10 '... Magnetic alloy multilayer film, 11, 11' ... High saturation magnetic flux density magnetic alloy film, 12, 12 '... Interlayer insulating film, 1
3, 13 '... Support for forming magnetic alloy film, 1
4, 14 '... Glass for joining magnetic cores, g ... Working gap, A ... Working gap vicinity, C ... Magnetic path.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shigeki Yamamura Inventor 1410 Inada, Katsuta City, Ibaraki Pref., Inside the Tokai Plant, Niitsu Seisakusho Co., Ltd. Tokai Plant (72) Inventor Akira Kato 4026 Kuji Town, Hitachi City, Hitachi, Ibaraki Prefecture Hitachi Research Laboratory, Ltd. (72) Inventor Takashi Namerikawa 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Ltd. (72) Inventor Takashi Naito 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Ltd. Hitachi Research Laboratory

Claims (4)

[Claims] Claim: What is claimed is: 1. A magnetic path comprising a pair of magnetic cores, each having a multi-layered film in which a magnetic alloy film having a high saturation magnetic flux density and an interlayer insulating film are alternately interposed on a support, facing each other through a minute magnetic gap. A magnetic head having the above-mentioned structure, wherein the interlayer insulating film is a complex oxide or an oxide mixture containing at least a vanadium element. 2. The magnetic head according to claim 1, wherein the interlayer insulating layer further contains at least phosphorus element. 3. The magnetic head according to claim 2, wherein the interlayer insulating layer further contains at least one element selected from the group consisting of antimony, lead, tellurium, barium, thallium and arsenic. 4. The magnetic head according to claim 1, wherein the magnetic gap has an effective gap length of 0.
A magnetic head having a thickness of 4 μm or less.