JPS5987614A - Metallic magnetic thin film head - Google Patents

Abstract

PURPOSE:To obtain a thin film head having excellent magnetic characteristics by using an electrically insulated material having a heat expansion coefficient approximate to the coefficient of a metallic magnetic film as an inter-layer film and thereby suppressing the generation of the stress produced by a heat treatment in a manufacturing process of the metallic magnetic films laminated alternately with theinter-layer films. CONSTITUTION:As shown in the figure, ''Sendust'' films 2, 2', 2'' and 2''' and inter-layer films 3, 3' and 3'' are laminated alternately with each other between nonmagnetic substrates 1 and 1'. A glass film 4 is used to adhere the film 2''' and the substrate 1'. The thickness ranging from the film 2 through the film 2''' is equal to the track width. A head gap 5 is formed with a prescribed angle to said track width. The films 3-3'' have a heat expansion coefficient approximate to that of films 2-2''', and a nonmagnetic insulator having excellent adhesive performance to the films 2-2''' and high reliability is used. The glass having a comparatively large heat expansion coefficient alpha of about 45X10<-7>/deg is used for a material suitable to an Si inter-layer film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a metal magnetic thin film head suitable for video tape recorders and the like.

[Prior art]

In recent years, metal tapes have become popular as magnetic tapes used in video tape recorders, and with this, metal magnetic thin film heads whose core material is Sendust film with high saturation magnetic flux density have attracted attention as magnetic heads suitable for such magnetic tapes. It has been confirmed that this head has superior performance compared to conventional ferrite heads.

Such a metal magnetic thin film head is basically constructed by sandwiching a sendust film between two nonmagnetic substrates, but the recording track to be formed on the magnetic tape has a relatively wide width. Since the thickness of the sendust film determines the track width, the thickness of the sendust film must be made relatively large. However, the resistance value of the sendust film is very small, and increasing the film thickness will cause high frequency The eddy current loss becomes significantly large, and the regeneration efficiency at high frequencies decreases.

Therefore, in order to eliminate such defects, a plurality of sendust films and electrically insulating interlayer films are alternately laminated between the non-abrasive substrates to form a multi-I@ structure and obtain a predetermined track width. The electrical resistance of the core material is increased to significantly reduce eddy current loss at high frequencies.

By the way, Sio2 film has conventionally been used as an interlayer film, and its thermal expansion coefficient is 4 to 6 x 10-7/deg.
In contrast, the thermal expansion coefficient of Sendust film is 13
0 to 150 x 10-7/deg, and the thermal expansion coefficients of the interlayer film and the sendust film are significantly different. Therefore, when heat is applied to the laminate of the interlayer film and the sendust film, a relatively large stress is generated in the sendust film due to the large difference in coefficient of thermal expansion between the two.

On the other hand, the sendust film requires heat treatment in order to develop desired characteristics. The sendust film is formed by sputtering on a non-magnetic substrate, but in order to produce the desired magnetic properties, it is necessary to heat the non-magnetic substrate during sputtering, or to perform an annealing treatment when sputtering is performed at a low temperature. There is. Therefore, such heat treatment causes relatively large stress in the sendust film.

Such stress significantly affects the initial magnetic permeability, which is one element that determines the magnetic properties, and deteriorates the magnetic properties. Therefore, in conventional metal magnetic thin film heads using sendust films, when attempting to obtain desired magnetic properties through heat treatment, the stress generated by this heat treatment simultaneously limits the magnetic properties, making it difficult to achieve sufficient performance. The drawback was that it was not possible.

[Object of the present invention]

An object of the present invention is to provide a metal magnetic thin film head that eliminates the drawbacks of the prior art described above, suppresses the generation of stress during heat treatment in the manufacturing process of metal magnetic films alternately laminated with interlayer films, and has excellent magnetic properties. There is something to do.

[Summary of the invention]

To achieve this objective, the present invention provides, as a glabellar membrane,
It is characterized by being made of an electrically insulating material having a coefficient of thermal expansion close to that of the metal magnetic film.

[Example of the present invention]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing an embodiment of a metal magnetic thin film head according to the present invention, in which 1.1' is a non-magnetic substrate 2, 2
/ , 2//, 2/// is Sendust film, 3゜5'
, 3'' is an interlayer film, 4 is a glass film, and 5 is a head gap.

In the figure, Sendust films 2.2', 2", 2' and interlayer films 5.5', 5" are alternately laminated between the non-magnetic substrates 1.1', and the glass film 4 is Sendust films 2.2', 2", 2' and interlayer films 5.5', 5". The film 2'' is bonded to the non-magnetic substrate 1'.The thickness from the Sendust film 2 to the Sendust J1g2'' forms the track width, and the head is attached at a predetermined angle to the track width. A gap 5 is formed.

Interlayer film 3.3/, sl/ is Sendust film 2.2'
.

A non-magnetic insulator is used that has a thermal expansion coefficient close to that of Sendust film 2, 2/, 2'', and 2#, and is good in terms of adhesion and reliability with Sendust films 2, 2/, 2'', and 2#. for,
Since Sendust is an alloy magnetic material of F''e, Ag, and Si, each oxide, FezOa +A
120a, Sing is a non-magnetic insulator, and in terms of adhesion with the sendust film, reliability, etc.
Although preferred as a material for interlayer films, forming a thin film of Fezes insulators is more difficult than forming AA or Si oxide films, and may become magnetized or semi-magnetic, making it difficult to form thin films of Fezes insulators. If the interlayer film is magnetic or semimagnetic, the magnetic properties thereof will affect the metal magnetic film head, which is undesirable. Therefore, it is preferable to use an Al+Sl based nonmagnetic oxide as the interlayer film. Furthermore, A/zo3 has a thermal expansion coefficient α of approximately 80 x 10-7/deg, which is extremely large compared to the thermal expansion coefficient of SiO2 (α = s x 10-'/deg), and is similar to that of sendust ( α=150~1
50 X10-7/aeg), interlayer film 5.3',
An example of a material suitable for a Sl-based interlayer film is a material with a thermal expansion coefficient α of approximately 45X 1o-
Corning's 7059 glass is relatively large at 7/deg. As described above, in this example, the interlayer film formed between the sendust films has a coefficient of thermal expansion close to that of the sendust film. Since the sendust film is made of a material that has the following properties, it is hardly affected by stress during heat treatment and has significantly improved magnetic properties. The magnetic properties can be further improved by forming the nonmagnetic substrate 1.1' from a material with a thermal expansion coefficient close to that of the Sendust film. Furthermore, since this embodiment has a multilayer structure in which the Sendust film and the interlayer film made of a non-magnetic insulating material are alternately formed, the reproduction efficiency at high frequencies is increased and the performance is improved. Since it has excellent adhesion with other materials, yields can be greatly improved.

2(a) to 2(e) are process diagrams showing a specific example of the magnetic thin film head for gold shown in FIG. 1, and parts corresponding to those in FIG. 1 are given the same reference numerals.

First, the coefficient of thermal expansion α is approximately 150 x 10-7/de
A sendust film 2 is deposited on a non-magnetic substrate 1 at a rate of 8 μm at a speed of 4 μm/hour using a DC 4-pole sputtering device.
The film was formed to a thickness of m (FIG. 2(a)).

Next, using an RF sputtering device, using a 99% ceramic alumina target, Al was sputtered onto the sendust film 2.
An interlayer film 6 made of 2O3 was formed to a thickness of about tooX (FIG. 2(b)). The Al2O3 film has a thermal expansion coefficient α of approximately 80 x 10-? / deg, and the thermal expansion coefficient α of the 5i02 film conventionally used as an interlayer film is approximately s x
10-7/deg, whereas Sendust's thermal expansion coefficient α (= i3o~150×10-'/
degree).

Next, a sendust film 2' is formed on the interlayer film 3 to a thickness of 8 μm by the method described above (FIG. 2(C)).
In the same way, interlayer films and sendust films are alternately formed,
Sendust films 2.2', 2'2''' and interlayer films 3.3',
5" are alternately stacked (Fig. 2(d)')
o The uppermost sendust film 2 of the thus laminated laminate
A low melting point glass film 4 is applied to the non-magnetic substrate 1' and the non-magnetic substrate 1', respectively.
．． Sputtered with a thickness of 2 μm and formed a sendust film 2″
' and the non-magnetic substrate 1' were stacked against each other with the low melting point glass film 4 formed on both faces, and were bonded together by heating (FIG. 2(e)). Next, a head gap is formed by cutting along the dotted line 6, grinding and lapping the cut surface, and bonding it through a non-magnetic film.As shown in FIG. A metal magnetic thin film head having 5 was obtained.

In this manufacturing method, the sendust film 2.2', 2"2"'
Although there is no separate annealing process for producing the magnetic properties, since heating is performed in the process of bonding the non-magnetic substrate 1' to the Sendust film 2M, this heating has the same effect as the annealing process. Sendust film 2, 2
/, 2'/, 2/# have magnetic properties. Of course, an annealing treatment is performed after the lamination process shown in FIG. 2(d), and then the Sendust film 2' and the nonmagnetic substrate 1'
It is also possible to perform an adhesion process with.

According to this manufacturing method, compared to the conventional 5iOz interlayer film, the magnetic properties were improved over the entire frequency band (~8 MHz), and in particular, the magnetic properties were improved in the high frequency range. The remarkable improvement in magnetic properties is particularly expressed in the initial magnetic permeability μ.

Next, another specific example of the method for manufacturing a metal magnetic thin film head according to the present invention will be described.

In this specific example, Corning's 7059 glass is used for the interlayer films 3.
9 glass, as mentioned earlier, is about 45 x 1o-7/d
It has a coefficient of thermal expansion of eg, which is much larger than 5i02, and has good adhesion to the sendust film. That is, in the steps shown in FIGS. 2(a) to 2(e), Corning Co.'s 70
Targeting 59 glass, 70 with a thickness of about 800X
59 Interlayer film made of glass 3,! , / , s//l
, to form. Sendust films 2.2', 2"21f/ and interlayer films 5, 5', 5 thus formed
The alternating laminates are annealed in vacuum at 600°C for about 30 minutes to bring out the magnetic properties of each Sendust film. In this case, the thermal expansion coefficient of the non-magnetic substrate 1 is the same as that of the Sendust film. Since it is slightly smaller than the coefficient of thermal expansion,
Although the film surface of the sendust film 2' is warped in a concave shape, the non-magnetic substrate 1' is bonded after flattening the film surface.

The metal magnetic thin film head shown in Figure 1 can be obtained by going through the same process as described above, and its magnetic properties are also comparable to those obtained by the manufacturing method described above. I was able to do that.

FIG. 3 is an explanatory diagram showing the initial magnetic permeability of the Sendust film for each material of the interlayer film, where the horizontal axis shows the coefficient of thermal expansion of the interlayer film material, and the vertical axis shows the coefficient of thermal expansion of the interlayer film material of SiO2. It represents the ratio of the initial magnetic permeability of the Sendust film when the interlayer film is made of another material to the initial magnetic permeability of the Sendust film at a certain time.

In Fig. 6, the thickness of the glabellar membrane is 0.2 μm, the thickness of the sendust layer is 6 μm, and 3 layers of sendust film 1
Two interlayer films are alternately laminated, and 4 M Ilz
It represents the ratio of initial permeability at . At point A, the interlayer film is 5iOz, at points B and C, 7059 glass, and A
It represents the ratio of initial magnetic permeability when l20g. From this, 7059.

It can be seen that AlzOa significantly improves the magnetic properties of the Sendust film as an interlayer film material compared to 5i02.

As a result of the experiment, the interlayer film was 5iOz and 7059 glass.

In the case of A120a, the thickness of each interlayer film is approximately 3
It has been found that insulation is maintained and losses such as eddy current loss can be eliminated if the temperature is 00X or higher. Therefore,
In order to maximize the effect of stress due to the difference in thermal expansion coefficient between the sendust film and the interlayer film, it is preferable that the interlayer film be relatively thick. On the other hand, considering special plays such as slow speed, still 3x speed, and search, if the thickness of the interlayer film made of non-magnetic insulating material in Sendust's multilayer film, which is the track width of the magnetic head, is slightly thickened, the magnetic tape In the recording track formed on the recording track, there is a wide unrecorded part due to the interlayer film of the metal magnetic thin film head, and the amount of noise from this unrecorded part becomes large and appears conspicuously on the playback screen, which affects the image quality of the reproduced image. It will cause deterioration.

Therefore, there is a limit to the thickness of the interlayer film, and as mentioned above, it was fixed at 0.2 μm.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to suppress the generation of stress in the metal magnetic film during heat treatment during the manufacturing process, so that excellent magnetic properties can be exhibited.
It is possible to provide a metal magnetic thin film head with high playback efficiency at high frequencies, improved performance, improved production yield, and superior functions not found in the conventional technology.

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment of the metal magnetic thin film head according to the present invention, and FIGS. 2(a) to 2e) are process diagrams showing a specific example of the method for manufacturing the metal magnetic thin film head of FIG. , FIG. 3 is an explanatory diagram showing the initial magnetic permeability of the Sendust film for each material of the interlayer film. .3', 5
“…Interlayer film 4…Low melting point glass film 5…Head gap agent Patent attorney Usui 1) Li 7jo 4 1st Kantsutsu 2 Figure 3 Sen CX (Xlo, /de9n 1st page) Continuation of 0 Author: Mitsuharu Tamura, Hitachi, Ltd. Home Appliance Research Laboratory, 292 Yoshida-cho, Totsuka-ku, Yokohama 0 Author: Toshi Ishihara 93, Tokai Factory, Hitachi, Ltd., 1410 Inada, Oaza, Katsuta City

Claims (1)

[Claims] (1) In a metal magnetic thin film head in which a plurality of metal magnetic films and glabellar films are alternately laminated between two nonmagnetic substrates, the interlayer film has a thermal expansion coefficient close to that of the metal magnetic film. 1. A metal magnetic thin film head comprising a non-magnetic insulating material having a structure such that stress in the metal magnetic film due to heat treatment can be suppressed. (2. In claim (1), the metal magnetic film is a sendust film, and the interlayer film is an alumina film or a glass film with a coefficient of thermal expansion of 45 x 10-7/deg. A magnetic thin film head for gold.