JPH10228606A - Magnetic head and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an MIG head having high yield and reliability and to provide its producing method by improving the gap accuracy of the MIG head. SOLUTION: At least one magnetic core of this MIG head has a metal magnetic film 1 on the gap-facing surface of a ferromagnetic oxide, and the magnetic gap 6 of this head consists of a nonmagnetic oxide gap material comprising Cr2 O3 or having such a structure that Cr2 O3 is held between a nonmagnetic oxide material essentially comprising SiO2 . A pair of core half bodies are brought into contact on the Cr2 O3 faces on the gap-facing surfaces, and a low melting point glass essentially comprising PbO is molded by heat treatment on Cr2 O3 in a groove formed in the ferromagnetic oxide to join the core half bodies. In this process, the heat treatment is carried out in an atmosphere containing oxygen at least in the temp. range T satisfying Tg-85 deg.C<=T<=T<=Tg-35 deg.C (wherein Tg is the glass transition temp. of the low melting point glass) during the temp. is raised in the heat treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head suitable for recording and reproducing information at a high density on a magnetic recording medium having a high coercive force used in a system such as a digital VTR and a data streamer, and a method of manufacturing the same. is there.

[0002]

2. Description of the Related Art With the demand for higher density of magnetic recording systems such as VTRs and data streamers, a magnetic head suitable for high-density magnetic recording / reproducing is made of a material having a higher saturation magnetic flux density Bs than a conventional ferrite material. 2. Description of the Related Art A magnetic head using a metal magnetic material such as a Co-based amorphous film or an Fe-based nitride film, and particularly, a MIG head has been actively developed.

As a structure of a conventional MIG head, as shown in FIG. 1, a metal magnetic film 1 having a high saturation magnetic flux density is formed mainly on a surface facing a magnetic gap of a ferrite 2 as a magnetic core. the provided structure magnetic gap 6 is the mainstream, the magnetic gap was mainly a structure which sandwiches Cr8 with SiO ₂ 7.

FIGS. 2A to 2F show a conventional method of manufacturing a MIG head. First, a winding groove 12 and a back glass groove 13 are formed in a pair of ferrite cores 2, and then a track groove 14 is formed. Next, the gap facing surface 15
After polishing, a metal magnetic film 1 is formed on the surface facing the gap, and SiO ₂ 7 and Cr 8 are sequentially formed thereon as a gap material by sputtering. Then, a pair of core halves are abutted on a gap surface, the low melting point lead glass 4 is molded on Cr8 by heat treatment, and the cores are joined by a gap to form one gapped bar.

Further, conventionally, the atmosphere during the heat treatment is in an N ₂ flow which is an inert gas. The reason for this is to prevent oxidation of the metal magnetic film used by heat treatment. Thereafter, the head chip is cut at a predetermined head chip core width and azimuth angle, and the sliding surface is polished to complete the head chip.

[0006]

However, the conventional structure of the MIG head has a problem that the gap length accuracy is poor and the characteristics are not stable, and the MIG head used as a gap material when measuring the gap length with an optical microscope. In this case, light is reflected on the substrate, and it is difficult to accurately measure the gap length.

Therefore, as a result of analyzing the cause, in the conventional gap material configuration, as shown in FIG. 3, Cr used as the gap material is partially removed by residual oxygen during heat treatment and oxygen in the low melting point lead glass 4. Oxidized and uneven Cr oxide 9
It was found that the gap length 10 was unstable because the volume was expanded and the film thickness became uneven.

Further, the purpose of using the conventional Cr as the gap material is for improving the wettability of the low melting point lead glass, the only oxides such as SiO ₂ without using Cr,
As shown in FIG. 4, there is a problem that the flow of the low-melting lead crow 4 is poor and the chip strength is greatly deteriorated.

[0009]

In order to solve the above-mentioned problems, a magnetic head according to the present invention has a magnetic core of at least one side in which a metal magnetic film is formed on a surface of a ferromagnetic oxide facing a gap. The gap is formed of a gap material made of Cr ₂ O ₃ , or at least one magnetic core has a metal magnetic film formed on a gap facing surface of a ferromagnetic oxide. The magnetic gap is formed of a gap material having a structure in which Cr ₂ O ₃ is sandwiched between nonmagnetic oxides containing SiO ₂ as a main component.

[0010] The method of manufacturing the magnetic head includes a pair of magnetic heads.
A groove is formed in the ferromagnetic oxide of
A magnetic metal film on at least one side of the gap
Forming a pair of core halves;
Cr on the surface of the body facing the gap and the surface of the groove_TwoO_ThreeForming a
Or SiO_TwoNon-magnetic oxide containing Cr as the main component and Cr_TwoO _Three
To form a pair of core halves with C
r_TwoO_ThreeLow melting point gas mainly composed of PbO
The lath is replaced with Cr in the groove._TwoO_ThreeMold by heat treatment on top
Of a MIG head having a step of joining cores
In the temperature rise process of the heat treatment, at least Tg-85 ° C ≦ T ≦ Tg-35 ° C (where Tg is the glass transition point of the low melting glass).
Temperature range T), heat treatment in an atmosphere containing oxygen
It is characterized by doing.

FIG. 5 shows the change in the thickness of each of Cr and Cr ₂ O ₃ after the heat treatment in the electric furnace used for manufacturing the MIG head. In the heat treatment at 520 ° C. for 10 minutes, the thickness of Cr is increased by about 70%, whereas the thickness of Cr ₂ O ₃ is hardly changed. This is because Cr is oxidized by residual oxygen during the heat treatment to become Cr oxide and expands in volume, whereas Cr ₂ O ₃ is oxidized from the beginning, so there is no new oxidation by heat treatment, This is because the volume is constant.

Therefore, the magnetic gap of the MIG head is formed of Cr ₂ O ₃ , or a gap material having a structure in which Cr ₂ O ₃ is sandwiched between non-magnetic oxides containing SiO ₂ as a main component, so that the heat treatment can be performed. There is no change in film thickness, and a stable gap length can be realized.

Furthermore, since Cr ₂ O ₃ is transparent, unlike Cr, there is no problem in manufacturing such as the fact that the gap length cannot be measured with high accuracy due to the reflection of light by Cr, which has been a problem with conventional Cr.

[0014] However, only the current state of Cr in Cr ₂ O _3, although the flow of glass over Cr ₂ O ₃ good than on SiO _2, worse than on a conventional Cr, the MIG head gap strength Is not enough.

Therefore, a means for sufficiently flowing glass on Cr ₂ O ₃ will be described. Conventionally, the atmosphere during heat treatment is N ₂
Although it was a flow, in order to improve the wettability of the glass, some air (oxygen was reduced to about 20%
(Including) heat treatment was studied. FIG. 6 shows a temperature rise process of a heat treatment (maximum temperature of 510 ° C. for 10 min. Keep).
₂ shows the results of examining the wetting angle of a low melting point lead glass (glass transition point Tg = 385 ° C.) on Cr and Cr ₂ O ₃ when heat treatment is performed in _two flows. From this result, it was found that the low-melting-point lead glass can achieve substantially the same wettability as that on Cr by performing a heat treatment at 350 ° C. or more on the atmosphere replacement temperature Tc even on Cr ₂ O ₃ . Therefore, to flow the low melting point lead glass on Cr ₂ O ₃ , the temperature range of at least 300 ° C. (glass transition point Tg-85 ° C.) to 350 ° C. (glass transition point Tg-35 ° C.) Requires heat treatment in the atmosphere. In addition, the same examination was performed for SiO ₂ , but even if Tc was increased to 510 ° C., the same wettability as Cr could not be realized.

Therefore, on Cr ₂ O ₃ , the heat treatment is performed in the air at least in the temperature range of (Tg-85 ° C.) to (Tg-35 ° C.) during the temperature rise process in the heat treatment.
It can be seen that the same wettability of glass as on Cr can be realized (however, Tg is the glass transition point of the glass used).

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic head according to the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 7 shows a magnetic recording medium according to Embodiment 1 of the present invention.
Perspective view of magnetic head and near magnetic gap seen from sliding surface
An enlarged view of the side is shown. Ferrite 2 magnetic core
A metal magnetic film 1 having a high saturation magnetic flux density is formed on the surface facing the gap.
Cr is formed between the metal magnetic films._TwoO_ThreeMagnetic gap
A loop 6 is formed. Also in the core gap
The joining is performed with the low melting point lead glass 4. In this embodiment
The ferrite is Mn-Zn ferrite, the metal magnetic film is
An FeTaN film having a saturation magnetic flux density Bs = 1.6T was used.
The glass used for bonding the core is mainly composed of PbO.
Low melting point glass with glass transition point Tg = 385 ° C
Was used. The difference between this head manufacturing method and the conventional one is that
In the conventional method of manufacturing a magnetic head shown in FIG.
Cr material_TwoO_ThreeOnly by sputtering instead of
And then mold the low melting point lead glass by heat treatment.
Then, in the heat treatment step of joining the cores with the gap, FIG.
As shown in FIG.
And then N_TwoChanged to heat treatment in the flow
That is the point. In this embodiment, Cr_TwoO_ThreeHas a thickness of 100
0 °. FIG. 8 shows the conventional magnetic gap of the Cr gap (a).
And Cr of the present invention_TwoO_ThreeGap (b) magnetic head
The GL (gap length) distribution at the time of trial production is shown. Of the present invention
Cr _TwoO_ThreeGap distribution of magnetic head with gap is lower than conventional products
It can be seen that it is very sharp and has little variation. Ma
Cr_TwoO_ThreeReaction with FeTaN which is a metal magnetic film
I knew it wasn't. Thus, as a result of this embodiment, GL
Accuracy is improved, stable head characteristics can be obtained,
The head manufacturing yield has been greatly improved. In addition, the conventional C
Gap length can be measured more accurately than r gap
To solve conventional head manufacturing challenges.
I was able to.

(Embodiment 2) FIG. 9 is a perspective view of a magnetic head according to Embodiment 2 of the present invention, and an enlarged view of the vicinity of a magnetic gap viewed from a sliding surface. A metal magnetic film 1 having a high saturation magnetic flux density is formed on the magnetic gap opposing surface of a ferrite 2 as a magnetic core, and a magnetic gap 6 having a structure in which Cr ₂ O ₃ is sandwiched between SiO ₂ is formed between the metal magnetic films. ing. The other parts and the manufacturing method are the same as in the first embodiment. In this embodiment, the thickness of SiO ₂ is 600 ° and the thickness of Cr ₂ O ₃ is 4
It was set to 00 °, and each was formed by sputtering. As a result, the GL distribution of this head is almost the same as in the first embodiment.
The GL accuracy has been improved compared to the prior art, stable head characteristics can be obtained, and the head manufacturing yield has been greatly improved.
In addition, the gap length can be measured with high accuracy, and the conventional problem in head manufacturing can be solved.

Next, the effects specific to this embodiment will be described. In the gap of only Cr ₂ O _{3 of} Example 1, the heat treatment temperature was 35 °.
If there is residual oxygen in the N ₂ flow atmosphere at 0 ° C or higher,
It has been found that the residual oxygen in the atmosphere reacts with FeTaN, which is a metal magnetic film, and the head characteristics may deteriorate. It is considered that the reason for this is that the effect of suppressing the reaction between the residual oxygen in the atmosphere and FeTaN is small with only 1000 ° Cr ₂ O ₃ alone. However, in this example, it was found that even if there was residual oxygen in the N ₂ flow atmosphere at a heat treatment temperature of 350 ° C. or higher, the residual oxygen in the atmosphere did not react with FeTaN as the metal magnetic film. It is considered that the reason for this is that 600 ° SiO 2 prevents the reaction between the residual oxygen in the atmosphere and FeTaN. Therefore, it was found that Example 2 had a larger allowance for the atmosphere during the heat treatment than Example 1 and was advantageous in manufacturing.

(Embodiment 3) FIG. 10 is an enlarged view showing the vicinity of a gap on a sliding surface according to Embodiment 3 of the present invention. The difference from the first and second embodiments is that the track width is regulated by electric discharge machining.

Even in such a head, a magnetic gap having the same high precision as that of the first and second embodiments could be realized by using Cr ₂ O ₃ or a gap material having a structure in which Cr ₂ O ₃ was sandwiched between SiO ₂ . .

The method of manufacturing these heads is shown in FIG.
In (e), unlike the first and second embodiments, first, a low-melting lead glass is molded in the back groove, and then, electric discharge machining for track regulation is performed, and then the low-melting lead glass is molded in the track groove. In the heat treatment step of molding the low melting point lead glass, heat treatment was performed in the atmosphere up to Tc = 350 ° C. at the time of raising the temperature, and then heat treatment was performed in an N ₂ flow. As a result, the glass flow is good,
No problem such as deterioration of chip strength was observed.

In the first to third embodiments, the case where FeTaN was used as the metal magnetic film was described. However, a Co-based amorphous film, sendust, Fe
Similar effects can be obtained by applying the present invention to a magnetic head using a GaSiRu metal magnetic film.

[0025] In Examples 2 and 3, the same effect even by using a non-magnetic oxide mainly containing SiO ₂ of Pyrex or the like instead of SiO ₂ is obtained.

[0026]

According to the magnetic head and the method of manufacturing the same according to the present invention, the accuracy of the magnetic gap can be greatly improved, the accuracy of measuring the gap length can be improved, and the manufacturing yield of the magnetic head can be greatly increased. Was.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a structure of a conventional magnetic head and an enlarged view of the vicinity of a magnetic gap viewed from a sliding surface.

FIG. 2 is a perspective view showing a conventional method for manufacturing a magnetic head.

FIG. 3 is a diagram showing a problem of a conventional magnetic head.

FIG. 4 is a perspective view of a magnetic head manufactured by a conventional manufacturing method.

FIG. 5 is a diagram showing a change in film thickness of Cr and Cr ₂ O ₃ after heat treatment.

FIG. 6 is a view showing a wetting angle of a low melting point lead glass on Cr and Cr ₂ O ₃ according to heat treatment conditions.

FIG. 7 is a perspective view showing the structure of the magnetic head according to the first embodiment of the present invention, and an enlarged view of the vicinity of the magnetic gap seen from the sliding surface.

FIG. 8 shows GLs of a conventional magnetic head and a magnetic head of the present invention.
Diagram showing (gap length) distribution

FIG. 9 is a perspective view showing the structure of a magnetic head according to a second embodiment of the present invention, and an enlarged view of the vicinity of a magnetic gap viewed from a sliding surface.

FIG. 10 is an enlarged view of the vicinity of a magnetic gap viewed from a sliding surface of a magnetic head according to a third embodiment of the present invention.

[Explanation of symbols]

1 metallic magnetic film 2 ferrite 3 Cr ₂ O ₃ 4 low melting point lead glass 6 magnetic gap 7 SiO ₂ 8 Cr 9 Cr oxide 10 gap length 11 EDM 12 winding groove 13 back groove 14 track groove 15 gap surface

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ken Takahashi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] An MIG wherein at least one magnetic core has a metal magnetic film formed on a surface of a ferromagnetic oxide facing a gap.
Magnetic head is characterized in that the magnetic gap of the head is formed of a gap material made of Cr ₂ O _3. 2. A MIG in which at least one magnetic core has a metal magnetic film formed on a surface of a ferromagnetic oxide facing a gap.
A magnetic head, wherein the magnetic gap of the head is formed of a gap material having a structure in which Cr ₂ O ₃ is sandwiched between nonmagnetic oxides containing SiO ₂ as a main component. Forming a groove in the pair of ferromagnetic oxides and then forming a metal magnetic film on at least one of the gap opposing surfaces of the ferromagnetic oxide to form a pair of core halves; C is applied to the gap opposing surface and the groove surface of the core half.
r ₂ O ₃ is formed, or a non-magnetic oxide containing SiO ₂ as a main component and Cr ₂ O ₃ are formed, and a pair of core halves are abutted on a Cr ₂ O ₃ surface on a gap opposing surface to form PbO. Molding a low melting point lead glass as a main component on the Cr ₂ O ₃ in the groove by heat treatment and joining the core.
In the manufacture of the IG head,
At least in a temperature range T of Tg-85 ° C. ≦ T ≦ Tg-35 ° C. (where Tg is the glass transition point of the low-melting glass), the magnetic head is heat-treated in an atmosphere containing oxygen. Manufacturing method.