JPH0777009B2 - Thin film magnetic head - Google Patents

Description

The present invention relates to a thin film magnetic head used in a PCM (Pulse Code Modulation) recording / reproducing apparatus and the like, and more specifically, a winding shape of a coil conductor and a relative contact portion. It is related to the physical relationship.

[Outline of Invention]

According to the present invention, a coil conductor is wound on a lower magnetic body via an insulating film, is connected to the lower magnetic body via a contact portion in the innermost winding of the coil conductor, and is coupled to a magnetic recording medium pair. In a thin-film magnetic head having an upper magnetic film forming an operating gap in cooperation with the lower magnetic body on the contact surface, the contact portion is formed near the operating gap, and the maximum magnetic film of the upper magnetic film is formed. When the road cross-sectional area is Sa, the area of the contact portion is Sb, and the area surrounded by the innermost winding of the coil conductor is Sc, by configuring so that Sc ≧ 2Sa Sb ≧ Sa, This is intended to improve the recording / reproducing efficiency by eliminating the magnetic saturation of the contact portion for magnetically connecting the substrate and the upper magnetic film.

[Conventional technology]

In the field of magnetic recording, magnetic recording media are becoming higher in coercive force along with higher density recording, and the recording / reproducing wavelength is becoming shorter. Therefore, in the magnetic head as well, a core material having a high saturation magnetic flux density is used, and a narrow gap is promoted to cope with the above high density recording.

Therefore, as the magnetic head, a thin film magnetic head manufactured by using a technique similar to the semiconductor manufacturing process has been receiving attention.

In this thin-film magnetic head, (1) since the alloy magnetic film having a high saturation magnetic flux density is used for the magnetic core, the high frequency magnetic permeability and the saturation magnetic flux density are increased. Therefore, high-speed writing to a magnetic recording medium having a high coercive force is possible.

(2) A narrow gap and a narrow track are possible, and the head magnetic field is steep, so high resolution recording is possible. Further, since the inductance is small, it can be used in a wide frequency band.

(3) Since hundreds of head elements are collectively formed on the wafer by the photolithography technique, the productivity is high and the processing accuracy is good.

It has features such as.

Generally, in this type of thin film magnetic head, as schematically shown in FIG. 3, a coil conductor (54) is wound on a lower magnetic body (51) through an insulating film (53), and further, An upper magnetic film (56) is formed on the coil conductor (54) via an insulating film (55). The upper magnetic film (56) and the lower magnetic body (51) are magnetically connected to each other at the contact portion (57) in the innermost winding of the coil conductor (54) to form a closed magnetic circuit. The recording / reproduction is performed with the operating gap g.

[Problems to be solved by the invention]

However, the contact portion (57) is formed close to the coil conductor (54) in order to reduce the size of the head. Therefore, depending on the size of the contact portion (57), the contact portion (57) is magnetically saturated.

The saturation of this contact part (57) is due to the contact part (57).
The coil conductor (54) formed by sandwiching the
a) and the magnetic field from the winding rear part (54b), and especially when the upper magnetic film (56) is formed on the winding rear part (54b).

When the contact portion (57) is saturated in this way, the working gap g portion becomes difficult to saturate, and a sufficient magnetic field in the gap cannot be obtained. Therefore, there is a problem that the original magnetic characteristics of the magnetic film are not exhibited and the recording / reproducing efficiency is deteriorated.

Therefore, the present invention was proposed in order to solve the above-mentioned problems, and eliminates magnetic saturation of the contact portion,
An object of the present invention is to provide a thin film magnetic head having excellent recording / reproducing efficiency by drawing out the magnetic characteristics inherent in the magnetic film.

[Means for solving problems]

In order to achieve this object, the thin film magnetic head of the present invention is
A coil conductor is wound on the lower magnetic body through an insulating film,
An upper magnetic film that is connected to the lower magnetic body through a contact portion in the innermost winding of the coil conductor and that forms an operating gap in cooperation with the lower magnetic body on the contact surface of the magnetic recording medium is formed. In the formed thin film magnetic head, the contact portion is formed near the working gap, and the maximum magnetic path cross-sectional area of the upper magnetic film is
When Sa, the area of the contact portion is Sb, and the area surrounded by the innermost winding of the coil conductor is Sc, Sc ≧ 2Sa Sb ≧ Sa.

[Action]

Since the contact portion for magnetically connecting the substrate and the upper magnetic film is formed near the operation gap, it is possible to reduce the influence of the magnetic field from the winding rear portion of the coil conductor.

At the same time, the area surrounded by the innermost winding of the coil conductor is at least twice the maximum magnetic path cross-sectional area of the upper magnetic film, and the area of the contact portion is at least equal to the maximum magnetic path cross-sectional area of the upper magnetic film. As a result, the magnetic saturation of the contact portion is eliminated.

〔Example〕

Embodiments of a thin film magnetic head to which the present invention is applied will be described below with reference to the drawings.

In the thin film magnetic head of the present invention, as shown in FIG. 1, the first insulating film (2) made of SiO ₂ or the like is formed on the lower magnetic body (1) except for the vicinity of the working gap G and the contact portion (8). ) Has been formed.

In the present embodiment, as the lower magnetic body (1), a composite substrate in which a ferromagnetic metal material such as Fe—Al—Si alloy (Sendust) is coated on a ferromagnetic oxide substrate such as Mn—Zn ferrite is used. used. The lower magnetic body (1) is not limited to this, and is a composite substrate in which the above-mentioned ferromagnetic metal material is deposited on a non-magnetic substrate such as ceramic, or the above-mentioned strong magnetic oxide substrate alone. May be used in.

A coil conductor (3) made of a conductive metal material such as Cu or Al is wound around the first insulating film (2). In the present invention, the coil conductor (3) is a spiral type,
A spiral multi-layer type or multi-layer helical type winding structure is used.

A first insulating film (4) is formed so as to cover the coil conductor (3) to insulate the upper magnetic film (5) described later. The portion of the second insulating film (4) in the vicinity of the working gap G and the contact portion (8) are removed by the same etching method as the first insulating film (2). And, in the vicinity of the operation gap G,
A gap spacer (6) made of SiO ₂ , Ta ₂ O ₅ or the like is formed to have a predetermined film thickness.

An upper magnetic film (5) forming a magnetic circuit in cooperation with the lower magnetic body (1) is deposited on the second insulating film (4).

The upper magnetic film (5) is formed from the contact portion (8) to the magnetic recording medium contact surface (10) covering the winding front portion (3a) of the coil conductor (3). The upper magnetic film (5) may be formed on the winding rear part (3b) of the coil conductor (3). The upper magnetic film (5) is connected to the lower magnetic body (1) through a window (7) provided in each insulating film (2), (4) to form a magnetic flux transmission path, and a contact portion ( 8) and the magnetic recording medium contact surface (1
In the vicinity of 0), the working gap G is formed by facing each other with the gap spacer (6) interposed therebetween.

Furthermore, although not shown, the above-mentioned coil conductor (3)
A protective plate for protecting the magnetic circuit portion constituted by the upper magnetic film (5) and the like, and for ensuring contact with the magnetic recording medium is fusion-bonded using a low melting point glass or the like as an adhesive.

Here, in the present invention, in the thin film magnetic head configured as described above, the contact portion (8) is close to the working gap G (that is, a position separated from the winding rear portion (3b)).
The magnetic saturation of the contact part (8) caused by the influence of the winding rear part (3b) of the coil conductor (3) is eliminated by forming the coil.

For example, as a lower magnetic body (1), a composite substrate in which Sendust is deposited on Mn-Zn type ferrite with a thickness of 10 μm is used, the length Lb of the contact portion (8) is set to 10 μm, and the upper magnetic film (5) is used.
Of the maximum magnetic path cross-sectional area is 10 μm, the length Ld of the second insulating film (4) in the winding front part (3a) is 14 μm, the depth length Dp is 10 μm, and the total length of the upper magnetic film (5) is 80 μm for Le
In the thin-film magnetic head set to, the change in the magnetic field in the gap was examined by changing the distance CL from the contact portion (8) to the center of the winding rear portion (3b), and the results shown in FIG. 2 were obtained.

As is clear from FIG. 2, it was confirmed that the magnetic field in the gap depends on the length of the distance CL and increases as the distance CL increases.

That is, it was confirmed that if the contact portion (8) is formed near the working gap G, the influence of the magnetic field in the rear portion (3b) of the winding is reduced, and the magnetic field in the gap that is involved in recording / reproducing becomes large.

Further, in the present invention, the maximum magnetic path cross-sectional area of the upper magnetic film (5) is set to Sa, and the area surrounded by the innermost circumference winding of the coil conductor (3) (the one-turn winding structure as in this embodiment). Then, the area surrounded by the front part (3a) and the rear part (3b) of the winding)
Sc is expressed as Sc ≧ 2Sa (1), and when the area of the contact portion (8) is Sb, Sb ≧ Sa (2) is satisfied. .

The above Sa, Sb, Sc are respectively expressed by the following equations Sa = La × Wa Sb = Lb × Wb Sc = Lc × Wc (where La is the film thickness at the maximum magnetic path cross-sectional area of the upper magnetic film, Lb, Lc Is the direction of contact with the magnetic recording medium (arrow X in FIG. 1).
Direction), and Wa, Wb, Wc respectively represent the length in the track width direction. ) Is represented by.

If the condition of the formula (1) is satisfied and at the same time the contact portion (8) is formed closer to the working gap G, the magnetic saturation of the contact portion (8) due to the influence of the winding rear portion (3b) can be surely eliminated. A good magnetic field in the gap is obtained.

Further, according to the above equation (2), the area of the contact portion (8) is secured, the magnetic resistance is reduced, and the magnetic saturation in the contact portion (8) is more reliably eliminated.

According to the experiments conducted by the present inventor, the area Sc surrounded by the innermost circumferential winding of the coil conductor (3) is less than twice the maximum magnetic path cross-sectional area Sa of the upper magnetic film (5), or the contact portion. The area Sb of (8) is the maximum magnetic path cross-sectional area of the upper magnetic film (5).
It was confirmed that when it is smaller than Sa, magnetic saturation occurs in the contact part (8).

Hereinafter, specific experimental results will be described.

First, in FIG. 1 above, La = 7 μm, Lb = 5 μm,
A sample with Lc = 11 μm was prepared.

In this example, Wa = Wb = Wc. Therefore, Sa> Sb and Sc <2Sa, and this example corresponds to the comparative example.

With this setting, the magnetic field strength at a position 0.1 μm away from the magnetic gap is 0.13 Tesla (value at a recording current of 0.5 A).
And a magnetic recording medium (Hc
It has been found that it is difficult to obtain sufficient recording characteristics for 1200 Oe or more).

Therefore, next, La = 7 μm, Lb = 10 μm, Lc = 20 μm
(However, Wa = Wb = Wc) was prepared.

In this example, Sa <Sb, Sc> 2Sa, and therefore corresponds to the embodiment.

In the case of this example, when the magnetic field strength was similarly measured at a position 0.1 μm away from the magnetic gap, it was found to be 0 at a recording current of 0.5 A.
It was 18 Tesla, and it was found that sufficient recording characteristics could be obtained even for a magnetic recording medium containing metal magnetic powder as magnetic powder.

Needless to say, the present invention is not limited to the above-mentioned embodiments, and various structures can be adopted without departing from the spirit of the present invention.

〔The invention's effect〕

As is clear from the above description, according to the thin film magnetic head of the present invention, the magnetic saturation of the contact portion for making a magnetic connection between the substrate and the upper magnetic film is eliminated, so that the magnetic film of each magnetic film is essentially The magnetic characteristics of (3) can be extracted, the working gap portion can be saturated, the recording / reproducing efficiency is improved, and good recording / reproducing characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic enlarged sectional view of an essential part showing an embodiment of a thin film magnetic head to which the present invention is applied. FIG. 2 is a characteristic diagram showing the relationship between the distance from the contact portion to the center of the coil conductor (the rear portion of the winding) and the magnetic field in the gap. FIG. 3 is an enlarged sectional view of an essential part schematically showing the structure of a conventional thin film magnetic head. 1 ... Lower magnetic body 3 ... Coil conductor 5 ... Upper magnetic film 8 ... Contact section 10 ... Magnetic recording medium contact surface G ... Working gap

Claims (1)

[Claims] 1. A magnetic recording medium, in which a coil conductor is wound on a lower magnetic body via an insulating film, and is connected to the lower magnetic body via a contact portion in an innermost winding of the coil conductor. In a thin film magnetic head having an upper magnetic film forming an operating gap in cooperation with the lower magnetic body on the contact surface, the contact portion is formed near the operating gap, and Sc ≧ 2Sa Sb ≧ Sa when the magnetic path cross-sectional area is Sa, the contact area is Sb, and the area surrounded by the innermost winding of the coil conductor is Sc. Magnetic head.