JPS63266619A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To obtain a thin film magnetic head having a good high frequency characteristic, good linearity and a wide dynamic range by providing a magnetic resistance effect element (MR element) near a magnetic flux introducing path (yoke) continuously formed without having a divide part. CONSTITUTION:An MR element 7 is formed in an insulator 11 at a process to laminate it in the order of an insulator/an MR element/an insulator on a lower part yoke 9. On the insulator 11, an upper part yoke 8 to introduce a magnetic flux to the MR element 7 is overlapped and the upper part yoke 11 is connected with the lower part yoke 9 in a side mutually facing with a head gap and formed in a continuous body. Namely, since the MR element 7 is arranged near the yoke 8, a signal generated in the yoke 8 can be detected even in the MR element 7 and for the yoke 8 facing with the MR element 7, it is not necessary to provide a gap such as a conventional head. Thus, without damaging a function as a magnetic head, the magnetic circuit resistance of the whole head can be reduced, the high frequency characteristic can be improved and also the linearity of the head and a dynamic range are improved.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is a method for recording data on a magnetic recording medium using a magnetoresistive element (hereinafter referred to as an MR element) that applies the magnetoresistive effect of a ferromagnetic thin film. The present invention relates to a thin-film magnetic head that detects signals generated by the magnetic field.

<Prior Art> It is known that a thin film magnetic head using an MR element has many advantages over a wire-wound magnetic head. In other words, the MR element can extract resistance changes as voltage changes by receiving a signal magnetic field recorded on a magnetic recording medium, so it has the advantage of being able to reproduce the signal magnetic field without depending on the transfer speed of the magnetic recording medium. Another advantage is that even when the transport speed of the magnetic recording medium is low, the output is higher than that of a wire-wound magnetic head.

This type of thin-film magnetic head using an MR element is used for high-density magnetic recording media, so the MR element is usually exposed at the tip of the head in order to be close to the magnetic recording medium. A high magnetic permeability magnetic material for shielding is provided on both sides or one side. When constructing a multi-channel thin film magnetic head using a high permeability magnetic material as a substrate, Ni-Zn ferrite or MnZn ferrite is used as the high permeability magnetic material for the lower shield, while the high permeability magnetic material for the upper shield is used. For ease of processing, a metal with high magnetic permeability such as permalloy is used.

Such a thin film magnetic head needs to be designed with a gap length of 0.5 μm or less in order to be applicable to a magnetic recording medium with a high recording density of, for example, 50 KBPI or more.

However, when an MR element is constructed in such a narrow gap, when the head tip comes into contact with the magnetic recording medium as it travels, the moisture on the medium or the highly transparent upper shield The MR element was often short-circuited by a minute peeled-off object of the magnetic material, resulting in no output. Further, when the magnetic recording medium is a metal ferromagnetic medium having electrical conductivity, this also causes a short circuit in the MR element. Apart from these problems, M
Since the R element had a very thin film thickness of about 300 to 700 mm, there was a problem in durability when the MR element was provided exposed at the tip of the head.

In order to improve this problem, we developed a thin film magnetic head (YMR) that has a structure in which the MR element is separated from the tip of the head and the magnetic flux generated in the magnetic recording medium is guided to the MR element through a magnetic flux introduction path (hereinafter simply referred to as a yaw table). head) is proposed.

FIG. 5 is a side view of the YMR head, in which the upper yoke is divided into a front part and a rear part, and an MR element 1 is located in the gap between the upper yoke front part 2 and the upper yoke rear part 3, and the lower shield height is It is manufactured using a magnetic permeability material 4 as a support substrate. The front end of the upper yoke 2 forms a predetermined gap with the high permeability magnetic material 4, and comes into sliding contact with the magnetic recording medium 5 with a space 6 in between.

<Problems to be Solved by the Invention> In the yoke type MR head with the above structure, the magnetic circuit resistance of the entire head is limited by the MR element and cannot be made too low. Since a gap is provided due to the need for electrical insulation, there is a drawback that the efficiency of the head decreases particularly in a high frequency range. Furthermore, since the signal magnetic flux guided by the yoke concentrates on the MR element, the magnetic flux density of the MR element becomes significantly higher than the magnetic flux density of the yoke. As a result, the response of the MR element is a square-law characteristic, which deteriorates the linearity of the reproduced signal, and its dynamic range is also narrow, which is disadvantageous for large signal magnetic fields.

<Means for Solving the Problems> The present invention includes upper and lower yoke parts for transmitting magnetic flux from a magnetic recording medium to an MR element, an insulator filled between the upper and lower yoke parts, and an insulator in the insulator. In a thin film magnetic head comprising a buried MR element thin film, the MR element is provided close to a yoke that is continuously formed without having a divided portion.

<Function> Since the MR element is placed close to the yoke, the signal generated in the yoke can also be detected by the MR element, and there is no need to provide a gap between the yoke facing the MR element as in conventional heads. Therefore, it is possible to reduce the magnetic circuit resistance of the entire head without impairing its function as a magnetic head, and to improve the high frequency characteristics as well as the linearity and dynamic range of the head.

<Example 1> In Fig. wI1, the lower yoke 9 as a support substrate is M
A magnetic substrate such as n-Zn ferrite or Ni-Zn ferrite, or a substrate in which permalloy, sendust, or an amorphous magnetic film is formed on a nonmagnetic substrate is used. On the surface of the lower yoke 9, S i (h e AIIgOs
The insulator 11 is formed by a film forming technique such as P-CVD or sputtering. The insulator 11 is formed extremely thin in the head gap portion facing the recording medium 10, but at a position away from the recording medium facing portion,
In order to efficiently transmit magnetic flux from the upper yoke, which will be described later, to the MR element, the magnetic yoke is thickly formed to lift the center of the yoke. The MR element thin film 7 is embedded in the thick portion of the insulator 11. The MR element thin film 7 is made of a NiFe-based or NiCo-based alloy film, and is usually formed by a method such as vapor deposition or sputtering. In the step of forming the insulator 11, the MR element 7 is coated with an insulator/M on the lower yoke 9.
It is formed in the insulator 1 by laminating the R element/insulator in this order. The insulators 11 on either side of the insulators 11 that sandwich the MR element 7 are formed to have a thin film thickness. In this example, the upper insulator in the figure is formed thinly,
An upper yoke 8 for guiding magnetic flux to the MR element 7 is superimposed on the thin insulator.

The upper yoke 8 is made of permalloy, sendust, or an amorphous magnetic film, and is connected to the lower yoke 9 on the side facing the head gap, forming a continuous body.

In the thin film magnetic head having the above structure, the magnetic recording medium 10
The magnetic field generated is guided to the MR element 7 through the upper yoke 8. Since the signal magnetic flux passing through the upper yoke 8 is shunted to the MR element 7 and detected, the efficiency of convergence of the magnetic flux passing through the upper yoke 8 is lower than in conventional yoke type MR heads, but the magnetic flux of the entire head is The 9CUgJ road resistance is different from the conventional yoke type M because the yoke part is integrated.
It is significantly smaller than the R head. Therefore, especially in the high frequency region where the signal magnetic field is small, the magnetic head with the above structure can guide much more signal magnetic flux to the upper yoke 8 than the conventional yoke type MR head, and as a result, the signal magnetic flux is shunted to the MR element 7. The signal magnetic flux generated also increases. On the other hand, at low frequencies, the signal magnetic field is large enough that the conventional yoke type MR head detects more signal magnetic flux.
As the linearity of the R element deteriorates, there are drawbacks such as a narrowing of the dynamic range. However, according to the structure of the above embodiment, the sensitivity is improved in the high frequency range and the increase in unnecessary signals can be suppressed in the low frequency range, so that a fairly flat frequency characteristic is obtained and the dynamic range is widened. Further, since there is no window in the upper yoke unlike in the conventional yoke type MR head, there is no asymmetry in the reproduced waveform due to intrusion of magnetic flux, which has the advantage of facilitating waveform equalization.

<5! Embodiment 2> In FIG. 2, an MR element 7a is embedded in an insulator 11 whose central portion is raised as in the first embodiment. A plurality of MR elements 7a of this embodiment are provided, and these MR elements are electrically connected in series. An upper yoke 8 is superimposed on a plurality of buried MR elements 7a to form a thin film magnetic head.

In the thin film magnetic head structure of this embodiment, a plurality of MR elements can be provided, and the output can be easily improved while maintaining the linearity and dynamic range of the MR elements.

<Example 3> The thin film magnetic head in Example 1 and Example 2 has a structure in which the upper yoke 8 is formed to have approximately the same thickness over the entirety, but in this example, as shown in FIG. , the film thickness of the upper yoke 8 in the region 8a facing the MR element 7 is set as that of the other region 8b.
Form thinner than .

By reducing the film thickness of the portion facing the MR element, the signal magnetic flux shunted to the MR element 7 can be increased.

If the film thickness of the upper yoke is made too thin, the magnetic circuit resistance of the entire head will increase and the signal magnetic flux will decrease, which may impede the original operation. It is desirable to design it to an appropriate thickness.

<Embodiment 4> Each of the above embodiments shows a structure in which the MR element is arranged close to the upper yoke 8 side, but as shown in FIG.
A lower yoke portion 3 is formed on 2 using permalloy, sendust, an amorphous magnetic film, etc., and is brought close to the lower yoke 13 via a thin insulator to form an MR element 7. M.R.
An upper yoke 8 is deposited on the element 7 via a thick insulator to form a thin film magnetic head.

In the structure of this embodiment, the signal magnetic flux is guided by the lower yoke 13 and branched to the MR element 7, producing the same effect as in the previous embodiment.

It goes without saying that a thin film magnetic head can be constructed by combining the above embodiments.

<Effects of the Invention> According to the present invention, it is possible to obtain a thin film magnetic head with good high frequency characteristics, good linearity and a wide dynamic range even in a yoke type MR magnetic head, which is superior to the conventional structure. Easy reproduction output with different waveform equalization can be obtained. Furthermore, machining of the yoke portion is significantly easier than in the conventional structure.

[Brief explanation of the drawing]

1 to 4 are side sectional views of a yoke type MR head according to the present invention, and FIG. 5 is a side sectional view of a conventional yoke type MR head. 7: MR element 8: Upper yoke 9: Lower high permeability magnetic material 11: Insulator 12: Non-magnetic substrate 13
:Lower yoke

Claims (1)

[Claims] 1. Upper and lower yokes for transmitting magnetic flux from a magnetic recording medium to a magnetoresistive element, an insulator filling a space between the upper and lower yokes, and an insulator embedded in the insulator. A thin film magnetic head comprising an MR element, characterized in that the MR element is arranged close to one yoke, and the yoke portion where the MR element is close is made of a continuous body. 2. The thin film magnetic head according to claim 1, wherein the MR element is comprised of a plurality of elements connected in series. 3. The thin film magnetic head according to claim 1, wherein the yoke is formed to have a thinner film thickness in the MR element facing region than in other regions.