JPH0589433A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To provide a thin film magnetic head for preventing generation of an inverse output, and showing no waviness in a frequency characteristic of an output. CONSTITUTION:An insulation layer 9 on a base plate 1, a magnetic shield layer 10 in between the insulating layers 9, an under core 3 on the insulating layer 9, a gap part 6 on the under core 3, an upper core 7 on the gap part 6, another insulating layer 11 on the upper core 7, another magnetic shield layer 12 on the other insulating layer 11 and a protective layer 8 on the other magnetic shield layer 12 are provided, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film magnetic head for recording / reproducing on / from a magnetic recording medium such as a magnetic disk.

[0002]

2. Description of the Related Art In recent years, in order to cope with an increase in recording density, a magnetic head has come to use a thin film magnetic head which uses a material having a high magnetic permeability and a high saturation magnetic flux density. .

FIG. 4 shows, as an example, a top view (a) of a conventional thin film magnetic head and a sectional view (b) taken along the line AB.

FIG. 5 is an enlarged view of portion a of FIG. 4 (b).
In FIGS. 4 and 5, reference numeral 1 is a substrate made of a non-magnetic material of Al ₂ O ₃ .TiC or a magnetic material of Mn-Zn ferrite.

The insulating layer 2 on the substrate 1, and the insulating layer 2
On the lower core 3, a lower core 3 made of a magnetic film, a gap portion 6 made of a coil 4 made of a conductive film and an insulating film 5 on the lower core 3, and an upper core 7 made of a magnetic film on the gap portion 6. The protective layer 8 made of an insulating film was provided on the upper core 7. Each of the above constituent elements has been formed by a film forming technique such as sputtering or vacuum evaporation, a photolithography technique using a resist, an etching technique such as ion milling or chemical etching. The reproduced waveform of such a thin film magnetic head is shown in FIG. That is, in the conventional thin film magnetic head, since the recording wavelength and the width of the tip of the magnetic core are close to each other as shown in c of FIG. The output that is contrary to the output of will be reproduced. The frequency characteristic of the thin-film magnetic head exhibiting such a reproduction output causes undulations as indicated by e and f in the characteristic curve, as shown in the conventional example of FIG. In particular, since the peak of this waviness is matched with the maximum frequency used in design, the optimum magnetic core width c at high recording density is necessarily narrowed to 2 μm.

[0006]

However, in the above-mentioned conventional structure, the optimum magnetic core width at high recording density becomes narrow, and therefore, at the position where the magnetic core width becomes narrow as shown in FIG. The magnetic saturation of the magnetic material occurs and the recording efficiency decreases. In addition, since the magnetic core width is narrow during reproduction, the magnetic resistance increases and reproduction efficiency deteriorates. Further, since the frequency characteristic as in the conventional example shown in FIG. 7 is exhibited, there is a problem that it is difficult to shape the waveform and match the waveform equivalent circuit that improves the error rate.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems, to prevent the occurrence of counter output, and to provide a thin film magnetic head having no undulation in the output frequency characteristic.

[0008]

To achieve the above object, a thin film magnetic head of the present invention comprises a magnetic shield layer in the middle of an insulating layer, another insulating layer on an upper core, and another insulating layer. Another magnetic shield layer is provided on the magnetic shield layer, and a protective layer is provided on the other magnetic shield layer.

[0009]

According to the present invention, the width of the core portion can be widened and magnetic saturation at the time of recording can be prevented.

[0010]

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

FIG. 1 is a sectional view of a thin film magnetic head according to an embodiment of the present invention. As shown in FIG. 1, a magnetic shield layer 10 is formed on a substrate 1 via a nonmagnetic insulating layer 9 formed by a vapor deposition method, a sputtering method, or the like, and is the same as or larger than the lower core 3. Make a shape into a shape. Permalloy, which is a soft magnetic alloy, is used for the magnetic shield layer 10. However, a soft magnetic material such as amorphous can be used in addition to this, and it is desired that the magnetic shield effect has a high magnetic permeability. These alloys are formed into a film by a vapor deposition method, a sputtering method, a plating method, or the like. Thickness is 0.5
was μm. Further, the lower core 3 is formed thereon with a nonmagnetic insulating layer 9 of about 0.2 μm interposed. In the case of this embodiment, the thickness indicated by c'is about 4 μm.
A coil 4 for passing a recording current on it and generating a reproducing voltage.
A gap portion 6 is formed by dividing the magnetic circuit and the insulating film 5 for generating a magnetic flux outside. Coil 4 is Cu
It is composed of a conductive film such as
It is performed by a plating method or the like. The upper core 7 is formed on the gap portion 6. The thickness of the upper core 7 in this example was about 6 μm. On top of that, another non-magnetic insulating layer 11
Another magnetic shield layer 12 is deposited through the above to form a shape having the same size as or larger than the upper core 7. This thickness was also 0.5 μm. The other magnetic shield layer 12 thus formed is protected by the protective layer 8. Such a thin film magnetic head exhibits a reproduced waveform as shown in FIG. 2, and no occurrence of counter output is observed. The frequency characteristic of the thin film magnetic head showing such a reproduction output shows a characteristic curve showing a uniform decreasing tendency as shown in the embodiment of FIG. Further, as shown in FIG. 3, the effect of the magnetic shield is sufficient if it is 0.1 μm or more.

[0012]

As is apparent from the above description, according to the present invention, the width of the core portion can be widened and magnetic saturation at the time of recording can be prevented, so that the counter output is not generated and the reproduction efficiency is improved. It is possible to realize a thin film magnetic head that facilitates matching of waveform equivalent circuits.

[Brief description of drawings]

FIG. 1 is a sectional view of a thin film magnetic head according to an embodiment of the invention.

[Fig. 2] Similarly reproduced waveform diagram

FIG. 3 is a diagram showing the relationship between the anti-reproduction output and the thickness of the magnetic shield layer in the present invention.

4A is a top view of a conventional thin film magnetic head, and FIG. 4B is a sectional view of the same.

FIG. 5 is an enlarged sectional view of a main part of a conventional thin film magnetic head.

[Fig. 6] Similarly, playback waveform diagram

FIG. 7 is a frequency characteristic diagram of outputs of a conventional example and an example.

[Explanation of symbols]

 1 substrate 3 lower core 6 gap part 7 upper core 8 protective layer 9 insulating layer 10 magnetic shield layer 11 other insulating layer 12 other magnetic shield layer

Claims (1)

[Claims] 1. An insulating layer is provided on a substrate, a lower core is provided on the insulating layer, a gap is provided on the lower core, an upper core is provided on the gap, and a protective layer is provided on the upper core. A thin film magnetic head, wherein a magnetic shield layer is provided in the middle of the insulating layer, another insulating layer is provided on the upper core, and another magnetic shield layer is provided on the other insulating layer.