JPS6216218A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To prevent the uneven wear of a thin film magnetic head by using a compd. of MgO and SiO2 which is limited in the range of component compsn. to form a protective film for the above-mentioned head. CONSTITUTION:Films of a core material for magnetic cores 21, 22, a gap material 4, conductors to be formed as signal coils 31, etc. are successively formed on a substrate 1 polished to a specular surface and are repeatedly etched until the films are patterned to prescribed shapes. The protective film 5 is finally formed to complete the thin film magnetic head. The protective film 5 is formed of the compd. of MgO and SiO2, by which the m.p. is decreased and the adequate hardness and coefft. of thermal expansion are provided. The film for the core material consisting of a Co-Nb amorphous alloy can be formed by mixing SiO2 at 10-70% concn. therewith and at 10-60% in the case of 'Sendust(R)'. The uneven wear of the head is prevented by using such protective film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a thin film magnetic head, and more particularly to a thin film magnetic head on which a protective film suitable for preventing uneven wear is formed.

[Background of the invention]

A protective film is formed on the thin film magnetic head to provide impact resistance, moisture resistance, environment resistance, wear resistance, and the like. Non-magnetic ceramics 5i02 or AL201 can be used as a material for such a protective film.
The use of this method is shown in Japanese Patent Application Laid-open Nos. 56-179925, 58-26508, and 1987-161122.

However, it is known that a mixture of MIo and 5i02 formed by electron beam evaporation has an appropriate hardness and coefficient of thermal expansion, and can form a thick film for thin-film magnetic heads using 90 series amorphous or Sendust core materials. It wasn't.

[Purpose of the invention]

An object of the present invention is to provide a thin film magnetic head on which a protective film is formed that can effectively suppress the occurrence of uneven wear of the thin film magnetic head.

[Summary of the invention]

In order to achieve this object, the present invention is characterized in that the protective film of the thin film magnetic head is formed of a mixture (compound portion) of MgO and 8i02 in an appropriate ratio.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1(α) and 1(b) are structural explanatory diagrams of a thin film magnetic head, where (α) is one example shown in a cross-sectional view, and (, 6) is the other side shown in a perspective view.

In the drawing (α), 1 is a substrate, 4 is a gap material, 5 is a protective film, 21 and 22 are magnetic cores, and 51 is a signal coil. air core, 5 is a signal coil, 4 is a gap material, is a protective film, 52
is the winding hole.

In each of these thin film magnetic heads, the core materials of the magnetic cores 2, 21, 22, non-magnetic insulating material, a conductor that becomes the signal coil 51 (in the case of (α) in the figure), etc. are mounted on a mirror-polished substrate 1. Film formation and etching are sequentially repeated to pattern into a predetermined shape. Finally, a protective film 5 is formed to complete the thin film magnetic head. In addition, in the case of FIG. 6(b), the signal coil 5 is installed.

! These treatments are performed using the photo-etching process used in the manufacture of ICs, etc., so a large number of Herad chips can be obtained from a single substrate with high precision, and there is little variation in performance, making it possible to mass-produce. Excellent for compatibility.

By the way, the protective film 5 is provided for the purposes of (1) protection from external impact, (2) moisture resistance, environmental resistance, (4) abrasion resistance, etc., and this protective film 5 is provided in the vicinity of the gap material 4 (i.e., in the vicinity of the gap). ), it is an important component of the head that determines the quality of the tape touch. The thickness of the protective film 5 is required to be approximately 20 to 40 μm in terms of tape sliding properties and uneven wear resistance. When the thickness K reaches this level, problems such as film peeling or film cracking generally occur due to accumulated film stress, leading to thin film magnetism.

It was difficult to form a film that could be applied to RAD. To solve this problem, it is necessary to reduce the internal stress of the film as much as possible, and an effective means is to match the thermal expansion coefficients of the materials forming the head. However, the metal core material CCO-based amorphous, Sendust.

The thermal expansion coefficient of N1Fa metal, etc.) is 100XIQ-'
1/[deg.]C or more, whereas general ceramics have a small thermal expansion coefficient of 100 x 10-' 1/υ or less. Therefore, it is difficult to match the thermal expansion coefficients of the core material and the protective film. Also, ZrO2゜At20 g
is a material with a relatively large coefficient of thermal expansion among ceramics, but its hardness relative to the core material causes uneven wear.
ZrO and K also have the disadvantage that they have higher melting points and are difficult to form into films.

On the other hand, like ZrO2, Mρ has a melting point of approximately ・280
However, it was found that a mixture (compound) with SiO2 lowers the melting point and has moderate hardness (HV=450 to 850) and thermal expansion coefficient.

FIG. 2 is a diagram showing the change in thermal expansion coefficient depending on the composition ratio of MgO and 5in2, which are protective film materials, when Co--Nb amorphous and sendust films are used as core materials, respectively. As shown in the figure, it can be seen that even if the composition ratio is the same, the coefficient of thermal expansion slightly changes depending on the film forming conditions and the like.

The figure also shows the occurrence of cracks and peeling when a protective film of about 50 μm was formed on Co--Nb-based amorphous and sendust films using an electron beam evaporation device. In the same figure, 0 is good, × is bad,
Considering that up to Δ is effective, it can be seen that a bottom film can be formed at a mixing ratio of 5ift of 10 to 70% for Co--Nb-based amorphous, and 10 to 60% for sendust.

From this result, it can be concluded that if the difference in thermal expansion coefficient between the core material and the protective film material (protection/film material) is approximately 40 to 50x+0-'1 A or more, the protective film will crack or peel.

It was found that the internal stress of the protective film formed with the O composition shown in FIG. 2 was approximately I x 10' ely9/-, which was approximately one order of magnitude smaller than that of SiO alone.

By forming a protective film of the above-mentioned mixture (compound) of MgO and 8z02, the uneven wear seen in the past was eliminated, and the reliability of the head was significantly improved.

The above characteristics of the protective film according to the present invention are the results of examination of a film formed using an electron beam evaporation device, but similar results were obtained with a protective film formed using a mixture (compound) of Ml, O, and 5Z02 using a sputtering device. Ta.

Figure 5 shows that Co-Nb amorphous is used as the core material of the magnetic core, and MgO and 5i according to the present invention are used as the protective film.
FIG. 2 is a diagram showing an example of the wear characteristics of a thin film magnetic head formed using a mixture (compound) of No wear was observed. 1. MgO and 8i0. The effect of the present invention is not impaired by adding a small amount of the fifth substance other than the above. Furthermore, an adhesion layer of Cr, Ti, etc. may be formed before forming the mixture (compound) of MgO and 5ho2.

In addition, regarding the composition ratio of MgO and SiO2, [ is a part.

Even if there is a lack of oxygen, there is no problem.

Furthermore, the mixture of MgO and S io2 according to the invention ((l
.

The membrane of the compound) has good tape sliding properties and is compatible with the core material, so it can be used effectively not only as a protective film material but also as a constituent material near the core material.

〔Effect of the invention〕

As explained above, according to the present invention, the thermal expansion coefficient is close to that of the core material, the hardness is appropriate, a protective film of 20 μm or more can be obtained, there is no uneven wear, and the tape has good sliding properties. A thin film magnetic head can be obtained, and a thin film magnetic head with excellent functions can be provided by eliminating the drawbacks of the above-mentioned prior art.

[Brief explanation of the drawing]

Fig. 1 (α1, (b) is a structural explanatory diagram explaining the structure of a thin film magnetic head, Fig. 2 is a diagram showing changes in the thermal expansion coefficient depending on the composition ratio of the protective film material, and Fig. 5 is a diagram illustrating the structure of the thin film magnetic head. It is a diagram showing an example of wear characteristics of a thin film magnetic head using a protective film. 1... Substrate, 2, 21, 22... Magnetic core, 5
．． 51...Signal coil, 4...Gap material, 5...
·Protective film. Representative Patent Attorney Katsoo Ogawa Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) A thin film magnetic head comprising at least a magnetic core, a gap material, and a protective film formed in a predetermined shape on a substrate by film formation and etching, characterized in that the composition of the protective film is composed of MgO and SiO_2. Thin film magnetic head. (2) In the thin film magnetic head according to claim (1), the composition ratio of MgO and SiO_2 is set to SiO_2.
A thin film magnetic head characterized in that the concentration is 10 to 70%.