JPH0795362B2 - Composite magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention is a so-called composite in which the vicinity of the operating gap is made of a magnetic alloy thin film and most of the magnetic core halves are made of an oxide magnetic material. The present invention relates to a magnetic head, and more particularly to improvement of the magnetic alloy thin film.

[Outline of Invention]

The present invention is a composite magnetic head comprising a magnetic core half body composed of an oxide magnetic material and a magnetic alloy thin film, wherein the magnetic alloy thin film is a Fe-Ga-Si soft magnetic thin film. , It aims to improve the magnetic characteristics of the magnetic alloy thin film to improve the recording / reproducing efficiency.

[Conventional technology]

For example, in magnetic recording / reproducing devices such as VTRs (video tape recorders), the density of information signals is being increased, and in response to this high density recording, magnetic powders such as Fe, Co, and Ni are used as magnetic recording media. A so-called metal tape using a ferromagnetic metal powder, a so-called vapor deposition tape in which a ferromagnetic metal material is directly deposited on a base film by a vacuum thin film forming technique such as vapor deposition, and the like have been used.

This kind of magnetic recording medium has high coercive force and residual magnetic flux density, and accordingly, a material having high saturation magnetic flux density and high magnetic permeability is required for the core material of the magnetic head.

However, a head using an oxide magnetic material such as ferrite, which has been widely used in the past, has a high magnetic permeability, but has a low saturation magnetic flux density, so that there is a limit to increasing the recording density. On the other hand, a head using a magnetic alloy material such as Fe-Al-Si alloy has a saturation magnetic flux density larger than that of ferrite and is capable of sufficiently recording on a high coercive force magnetic recording medium, but is generally used. With a core thickness in the shape of a head, the effective magnetic permeability in the frequency range used is low and the reproduction characteristics deteriorate.

Under such circumstances, the magnetic core portion is made of an oxide magnetic material, and a magnetic alloy material is formed as a main core material on each of these magnetic core portions, and these magnetic alloy thin films are butted against each other to form an operating gap. A so-called composite magnetic head has been proposed.

[Problems to be solved by the invention]

However, in the composite magnetic head having the above-mentioned structure, since the contact area between the oxide magnetic material and the magnetic alloy thin film is large, various problems remain due to the difference in thermal expansion coefficient between them.

That is, Mn-Zn ferrite (coefficient of thermal expansion: 115 to 120 × 10 ^-7 / ° C) is used for the magnetic core and Fe-Al-Si is used for the magnetic alloy thin film.
In a magnetic head using a system alloy (coefficient of thermal expansion: 150 to 160 × 10 ^-7 / ° C), it is difficult to avoid strain due to the difference in coefficient of thermal expansion. For this reason, microcracks are generated in the magnetic core portion during head production, or the magnetic characteristics of the magnetic alloy thin film are deteriorated. As a result, there is a problem in that the magnetic head is inferior in reproduction efficiency.

When a ferromagnetic amorphous alloy is used for the magnetic alloy thin film, the crystallization temperature of the amorphous material must be taken into consideration when joining the magnetic core halves by glass bonding or the like, so that a large joining strength is obtained. It's hard to get. Therefore, it is possible to use an amorphous alloy having a crystallization temperature that satisfies the above conditions, but in this case, a sufficient saturation magnetic flux density cannot be obtained, and there is a problem in recording efficiency of the head.

Under such circumstances, the present invention has been proposed, and an object of the present invention is to improve the magnetic characteristics of the magnetic alloy thin film and to provide a composite magnetic head having excellent recording and reproducing efficiency.

[Means for solving problems]

In order to improve the magnetic characteristics of the composite magnetic head, the inventors of the present invention have made repeated studies on a magnetic alloy thin film that constitutes an operating gap and is involved in recording and reproduction, and as a result, an Fe-Ga-Si soft magnetic thin film is obtained. Since it has a high saturation magnetic flux density and, at the same time, a thermal expansion coefficient similar to that of the oxide magnetic material forming the magnetic core portion, it has been found that it is useful as a magnetic alloy thin film of a composite magnetic head.

The composite magnetic head of the present invention has been completed based on such findings, and in a composite magnetic head comprising a magnetic core half body composed of an oxide magnetic material and a magnetic alloy thin film, the magnetic alloy thin film Is a Fe-Ga-Si based soft magnetic thin film.

[Action]

Fe-Ga-Si soft magnetic thin film has a saturation magnetic flux density of 13000.
Since it is about Gauss and is larger than the Fe-Al-Si based soft magnetic thin film (11000 Gauss), the recording efficiency is improved.

At the same time, the thermal expansion coefficient of the Fe-Ga-Si soft magnetic thin film is 13
Since it is about 0 × 10 ^-7 / ° C, which is close to the thermal expansion coefficient (115 to 120 × 10 ^-7 / ° C) of oxide magnetic material (Mn-Zn ferrite), oxide magnetic material etc. The microcracks and warpage are suppressed, and the magnetic properties of the Fe-Ga-Si alloy can be sufficiently exhibited, so that the reproduction efficiency is improved.

〔Example〕

An embodiment of a composite magnetic head to which the present invention is applied will be described below with reference to the drawings.

FIG. 1 is an external perspective view showing an example of a composite magnetic head to which the present invention is applied, and FIG. 2 is a main part enlarged plan view showing a sliding surface of the magnetic recording medium.

In this composite magnetic head, the magnetic core portion (1),
(11) is made of an oxide magnetic material, for example, Mn-Zn ferrite, and has a substantially arcuate shape on both sides due to track width regulating grooves (2) and (12) near the contact surface. Is cut out. A winding hole (21) for winding a coil for supplying a signal to the magnetic head is formed in one magnetic core half body (1).

The contact surfaces of the magnetic core portions (1) and (11) include the inside of the track width regulating grooves (2) and (12),
A magnetic alloy thin film (3) or (13) made of a high saturation magnetic flux density alloy, Fe—Ga—Si soft magnetic thin film in the present invention, is continuously coated from the front gap forming surface to the back gap forming surface. And magnetic core halves (I) and (II) are formed. Further, the operating gap g is formed by abutting the parallel portions (3a) and (13a) formed on the contact surfaces of the magnetic alloy thin films (3) and (13). In the track width regulating grooves (2) and (12), non-magnetic materials (22) and (22) for regulating the track width and preventing wear of the magnetic alloy thin films (3) and (13) are provided. ) Is melt-filled.

Here, in the present invention, the magnetic alloy thin film (3),
(13) is composed of a Fe-Ga-Si soft magnetic thin film.

In the Fe-Ga-Si-based soft magnetic thin film, in order to secure predetermined magnetic characteristics, the basic components Fe, Ga, and Si are Ga1 to 23 atom%, Si9 to 31 atom%, and the balance Fe. . However, the Fe content is in the range of 68 to 84 atomic%. If these basic components are out of the above range, the saturation magnetic flux density, magnetic permeability,
It becomes difficult to secure magnetic properties such as coercive force.

That is, when the composition of the Fe-Ga-Si-based soft magnetic thin film is Fe _a Ga _b Si _c (where a, b, and c are each represented by the composition ratio in atomic%), the composition range is , 68 ≦ a + b ≦ 84 1 ≦ b ≦ 23 9 ≦ c ≦ 31 a + b + c = 100.

In the Fe-Ga-Si based soft magnetic thin film, Fe may be partially replaced by Co. In this case, not only the saturation magnetic flux density but also the corrosion resistance and wear resistance are improved as Co increases,
When the Co substitution amount is too large, not only the saturation magnetic flux density is significantly deteriorated but also the soft magnetic characteristics are deteriorated. Therefore, the Co substitution amount with respect to Fe is preferably suppressed to 0 to 15 atom%.

That is, when the composition of the Fe-Ga-Si-based soft magnetic thin film is Fe _d Co _e Ga _f Si _g (where d, e, f, and g are the composition ratios expressed as atomic%), The composition range thereof satisfies the relationship of 68≤d + e≤840 0 <e≤15 1≤f≤35 1≤g≤35 d + e + f + g = 100.

In order to further improve the corrosion resistance and wear resistance of the Fe-Ga-Si-based soft magnetic thin film, a basic composition of Fe, Ga, Co (including a part of Fe replaced by Co) is used. Ti, Cr, M
At least one of n, Zr, Nb, Mo, Ta, W, Ru, Os, Ir, Re, Ni, Pd, Pt and Hf may be added.

That is, the composition of the Fe-Ga-Si-based soft magnetic thin film is represented by Fe _h Co _i Ga _j Si _k M _l (where h, i, j, k, l represent the composition ratio in atomic%, and M is Ti, Cr, Mn, Zr, Nb, Mo, Ta, W, Ru, Os, Ir, Re, Ni, Pd, P
Represents at least one of t and Hf. ), The composition range satisfies the relation of 68 ≦ h + i ≦ 84 0 ≦ i ≦ 15 1 ≦ j ≦ 23 6 ≦ k ≦ 31 0.5 ≦ 1 ≦ 6 h + i + j + k + 1 = 100. It may be a soft magnetic thin film. The addition amount of the above-mentioned additional element M is set to 0.5 to 6 atom%, because if the addition amount is less than 0.5 atom%, sufficient effect for improving wear resistance and corrosion resistance cannot be expected, while the addition amount is 6 atom. %
If it exceeds, the soft magnetic properties are deteriorated and the saturation magnetic flux density is decreased, which is not preferable. However, when two or more additive elements M are used, the additive amount of each additive element is preferably in the range of 0 to 5 atomic%.

In any of these cases, part of Ga may be replaced with Al and part of Si may be replaced with Ge in the above composition formula.

Here, as the method for forming the Fe-Ga-Si-based soft magnetic thin film, various conventionally known methods can be considered. Among them, the vacuum thin film forming technique is preferable.

Examples of the technique of this vacuum thin film forming technique include sputtering, ion plating, vacuum evaporation method, cluster ion beam method and the like. In particular, sputtering may be performed in an inert gas (Ar gas or the like) atmosphere containing oxygen gas or nitrogen gas to further improve the corrosion resistance and the like of the obtained soft magnetic thin film.

In addition, as a method of adjusting the composition of each of the above-mentioned component elements, i) each component element is weighed so as to have a predetermined ratio, and these are melted in advance in, for example, a high-frequency melting furnace to form an alloy ingot. , A method of using this alloy ingot as an evaporation source, ii) a method of preparing evaporation sources of individual elements of each component, and controlling the composition by the number of these evaporation sources, iii) preparation of evaporation sources of individual elements of each component Then, the output (applied voltage) applied to these evaporation sources is controlled to control the evaporation speed to control the composition, iv) a method of implanting another element while vapor-depositing the alloy as the evaporation source, and the like.

The soft magnetic thin film formed by the above-described vacuum thin film forming technique has a slightly higher coercive force in the state as it is, and good soft magnetic characteristics cannot be obtained. It is preferable to remove and improve the soft magnetic properties.

In the composite magnetic head having such a structure, composite magnetic heads were prepared by changing the compositions of the magnetic alloy thin films (3) and (13) variously, and recording and reproducing characteristics and corrosion resistance were measured for each. The results are shown in Table 1. For comparison, magnetic heads using Fe—Al—Si soft magnetic thin films as the magnetic alloy thin films (3) and (13) were also measured in the same manner, and the results are shown in Table 1.

In the measurement of the recording / reproducing characteristics described above, the composite magnetic head shown in FIG. 3 to be described later was used for reproducing when the recording characteristics and for recording when the reproducing characteristics were used. The magnetic tape used had a coercive force of about 1500 Oe. Furthermore, the corrosion resistance of each head depends on the observation of the surface of the film surface after immersion in tap water for about 1 week at room temperature. The evaluation of the corrosion resistance was made based on the following surface conditions.

A: There is no change in the film surface and the mirror surface is maintained.

B: A state where thin rust is generated on the film surface.

C: A state where thick rust is generated on the film surface.

D: Rust generated to such an extent that the film itself disappears.

As is clear from this table, the composite magnetic head using the Fe-Ga-Si soft magnetic thin film as the magnetic alloy thin film is caused by the fact that this soft magnetic thin film has a high saturation magnetic flux density (approximately 13000 gauss). It was found that the recording characteristics are improved.

The thermal expansion coefficient of the Fe-Ga-Si soft magnetic thin film is 135
× 10 ^-7 / ℃, Fe-Al-Si soft magnetic thin film (160 ×
Since the thermal expansion coefficient of the magnetic core part (for example, Mn-Zn ferrite) is much closer to 120 × 10 ^-7 / ° C compared to 10 ^-7 / ° C), the film stress generated during the formation of the magnetic alloy thin film, etc. It gets quite small. Therefore, microcracks and the like in the head manufacturing process can be effectively eliminated, and good reproduction characteristics can be obtained. Further, a composite magnetic head having uniform head characteristics can be obtained and the yield can be improved.

As described above, according to the present invention, it is possible to provide a composite magnetic head capable of sufficiently exhibiting the magnetic characteristics of the magnetic alloy thin film.

Further, since the Fe-Ga-Si-based soft magnetic thin film has excellent wear resistance and corrosion resistance, the life of the head is extended and good recording / reproducing characteristics can be maintained for a long time. Moreover, the initial electromagnetic conversion characteristics of the head can be maintained for a long period of time even when the relative speed between the head and the medium required for high-density recording increases. Therefore, a spacing loss and the like due to uneven wear of the sliding surface of the magnetic recording medium can be eliminated, so that a composite magnetic head suitable for recording and reproducing in a high frequency region can be provided.

Further, since the present invention can be carried out without changing the conventional structure, manufacturing method, process, etc., it can be said that this practical value is extremely high.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment and can be applied to composite magnetic heads having various structures without departing from the spirit of the present invention.

For example, as shown in FIG. 3, the abutting surfaces of the magnetic core portions (30) and (31) made of an oxide magnetic material are obliquely cut into inclined surfaces (30a) and (31a), respectively, and the inclined surfaces ( Magnetic alloy thin films (32) and (32) made of Fe-Ga-Si based soft magnetic thin films are formed on 30a) and (31a) to form magnetic core halves, and these magnetic alloy thin films (32) and (32) are formed. A composite magnetic head in which the contact surface of 32) has an operating gap g may be used. In addition, the track width regulating grooves (34) and (35) are notched in the magnetic core portions (30) and (31) to regulate the track width, and the track width regulating grooves (34) and (35) and the magnetic Non-magnetic materials (36) and (37) are melt-filled in the alloy thin films (32) and (33). In this composite magnetic head, the track width can be regulated by the film thickness of the magnetic alloy thin films (32) and (33), so that the track can be narrowed and it is a magnetic head suitable for high density recording.

Alternatively, as shown in FIG. 4, on the inclined planes (40a) and (41a) of the magnetic core portions (40) and (41) inclined by a required angle with respect to the working gap g and the inclined planes (40a). ), (41
a) Magnetic field composed of Fe-Ga-Si based soft magnetic thin film continuously formed in the track width regulating grooves (42), (43), (44), (45) notched on both sides of a). Alloy thin film (4
The present invention is also applicable to a composite magnetic head formed by depositing 6) and (47). In this way, the above-mentioned one-sided plane (40
By arranging a) and (41a), the influence of the pseudo gap generated in the head shown in FIGS. 1 and 2 can be eliminated.

Furthermore, as shown in FIG. 5, the magnetic core (50),
The abutting surface of (51) is obliquely cut across the entire width to form inclined surfaces (50a) and (51a), and these inclined surfaces (50a) and (51a)
Magnetic alloy thin film composed of Fe-Ga-Si soft magnetic thin film (5
2) and (53) may be adhered and the track width may be regulated by the thickness of the magnetic core portions (50) and (51) to form a composite magnetic head.

〔The invention's effect〕

As is clear from the above description, in the composite magnetic head of the present invention, since the magnetic alloy thin film which constitutes the operating gap and serves as the main core is the Fe-Ga-Si soft magnetic thin film,
The stress contribution to the magnetic body due to the difference in thermal expansion coefficient between the oxide magnetic material and the magnetic alloy thin film during the head manufacturing process is reduced, and deterioration of the magnetic characteristics can be suppressed. Therefore, the reproducing efficiency is remarkably improved. Further, since the Fe-Ga-Si based soft magnetic thin film has a large saturation magnetic flux density, it exhibits good recording characteristics for a high coercive force magnetic recording medium.

Furthermore, according to the present invention, there is no need to change the manufacturing process of the composite magnetic head, and there is no concern about a decrease in production efficiency or a decrease in accuracy.

Furthermore, since distortion in the process of forming the head can be effectively suppressed, microcracks, warpage, etc. are effectively removed, and the head characteristics and yield are improved.

Further, the Fe-Ga-Si based soft magnetic thin film is also excellent in corrosion resistance and abrasion resistance, and is therefore advantageous in terms of durability of the composite magnetic head.

These advantages work effectively to improve the performance of the composite magnetic head in combination with the features such as the ease of downsizing, the high productivity, the high reliability, and the high density recording, which are derived from the configuration of the composite magnetic head. Therefore, it is possible to provide a composite magnetic head with high practical value.

[Brief description of drawings]

FIG. 1 is an external perspective view showing an embodiment of a composite magnetic head to which the present invention is applied, and FIG. 2 is an enlarged plan view of an essential part showing a contact surface of the magnetic recording medium. FIG. 3 to FIG. 5 are enlarged plan views of essential parts showing the contact surface of the magnetic recording medium of another example of the present invention. 1,11 …… Magnetic core (oxide magnetic material) 3,13 …… Magnetic alloy thin film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Hayashi 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Masatoshi Hayakawa 6-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Osamu Ishikawa 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation

Claims (1)

[Claims] 1. A composite magnetic head comprising a magnetic core half body composed of an oxide magnetic material and a magnetic alloy thin film, wherein the magnetic alloy thin film is a Fe—Ga—Si soft magnetic thin film. Magnetic head.