JPH05101332A - Thin film magnetic head - Google Patents

Abstract

(57) [Summary] [Object] To suppress the occurrence of popcorn noise in a thin film magnetic head without deteriorating the recording / reproducing characteristics, and to enable high density recording and high transfer rate. [Structure] Rear region B of upper magnetic pole layer 4 and lower magnetic pole layer 5
A first region B ₁ that contacts the entire width to form the rear gap 6, and a second region B ₁ having a constant width wider than the first region B ₁ .
The region B ₂ and the connecting region B ₃ whose width is linearly reduced toward the first region B ₁ are included.

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 and reproducing information on a recording track of a magnetic recording medium such as a magnetic disk.

[0002]

2. Description of the Related Art With the expansion of the range of use of computers in recent years, in magnetic disk devices widely used as external storage devices, there is an increasing demand for miniaturization along with an increase in storage capacity. The realization of high-density recording is an important issue.

In such high-density recording, on the magnetic disk side serving as a recording medium, the track density is increased to increase the recording density in the radial direction, and the magnetization reversal interval on each track is shortened to perform recording in the circumferential direction. This is achieved by increasing the density, but with this, the magnetic head that performs information recording / reproducing operation on each track is affected by adjacent recording tracks for recording / reproducing operation on a narrow recording track. It is required to be able to perform without receiving, and in order to meet this demand, there is an increasing demand for a thin film magnetic head instead of a conventional ferrite head.

Since the thin-film magnetic head has an extremely small magnetic pole and can suppress the inductance to a low level, the signal-to-noise ratio (S / N) is reduced due to the reduction of impedance noise.
Ratio) can be expected, and since the rise and fall times of the recording current can be shortened and the reversal time of the recording current can be shortened, it is possible to cope with an increase in recording density, which is useful for realizing high-density recording. It has many advantages.

FIG. 5 is a partially cutaway perspective view of a main part of a conventional thin film magnetic head, and FIG. 6 is a plan view of the same. As shown in FIG. 5, in the thin film magnetic head, a conductor coil 1 having a plurality of turns 10, 10 ... Is formed in an insulating layer 2 made of a thermosetting resin or the like, and the insulating layer 2 is laminated on one surface thereof. Al ₂
Along with the gap layer 3 made of a non-magnetic material such as O ₃ (alumina), the upper magnetic pole layer 4 and the lower magnetic pole layer 5 made of a NiFe alloy etc.
And the magnetic pole layers 4 and 5 between the turns 10 and
While extending to one side in the juxtaposed direction of 10 ... and sandwiching the gap layer 3 extended to the same side to form a conversion gap, at the end portion of the gap layer 3 on the other side of the juxtaposed direction, A yoke 7 having a rear gap 6 in which the two magnetic pole layers 4 and 5 are in direct contact is formed on a base 8 on the lower magnetic pole layer 5 side.

The upper magnetic pole layer 4 and the lower magnetic pole layer 5 have substantially the same shape in a plan view. In JP-A-55-84019, the two magnetic pole layers 4 and 5 have a planar shape, that is, a yoke 7. It is disclosed that the planar shape of (1) affects the conversion efficiency during recording and reproduction. The shapes of the pole layers 4 and 5 shown in FIGS. 5 and 6 are those disclosed in the above publication, and the gap layer 3
And a front end region A having a substantially constant narrow width, and a rear end that is continuously provided at the base end of the front end region A and gradually increases its width toward the other side (rear side) to form a fan shape in plan view. The region B is formed by the region B, and the side face angle θ of the rear region B is set in the range of 30 ° to 60 °. By using the magnetic pole layers 4 and 5 having such a shape, the magnetic saturation level of the yoke 7 can be increased and the conversion efficiency can be improved, as described in JP-A-55-84019.
It is described in Japanese Patent Publication No. The rear gap 6 is
To efficiently capture the magnetic flux generated when recording information,
The widthwise central portion near the rear end of the rear region B is in contact with the rear region B over a predetermined width.

Further, Japanese Patent Application Laid-Open No. 3-46109 discloses a thin film magnetic head for reducing the generation of wiggle during reproduction. The cause of the wiggle is that the change in magnetization in the pole face is not uniform in time and causes a local time delay. In the thin film magnetic head disclosed in the above publication, the upper magnetic pole layer 4 and the lower magnetic pole layer 5 are brought into contact with each other over the entire width of the rear region B, and the tip region A facing the recording track is formed.
By forming the rear gap 6 that is substantially parallel to the end face of the magnetic disk, the unstable portion of the magnetic domain in the vicinity of the rear gap 6 is eliminated and the wiggle is reduced.

[0008]

By the way, it is known that in a thin film magnetic head, pulse-like noise having a high peak value, so-called popcorn noise, is generated with an appropriate time delay after an information recording operation. However, there is a problem that this popcorn noise causes an operation error in the reproducing operation following the recording operation.

The survey report on popcorn noise is
`` IEEE TRANSACTIONS ON MAGNETICS, Vol.25, NO.5, SEP
TEMBER 1989, PP3212-3214 ", and according to this report, the probability of occurrence of popcorn noise decreases with the increase of the elapsed time after the recording operation. This can be solved by increasing the time until the start, but this is against the demand for high density recording and high speed operation and is not a desirable measure.

Further, it is considered that the popcorn noise is caused by a time delay in the change of the magnetic domain structure in the magnetic pole surface at the time of the transition from the recording operation to the reproducing operation, as described in JP-A-3-46109. In the case of using the thin-film magnetic head disclosed in US Pat. No. 6,096,088, the magnetic domain is stabilized, some improvement can be recognized against popcorn noise, but it is not sufficient.

Further, the applicant of the present application has found that the side surface angle θ of the rear region B is
It is experimentally found that increasing the value is effective in reducing popcorn noise, and based on this finding, there is a rear region B having a constant width (side angle θ = 90 °) and a constant width smaller than this. A thin film magnetic head having an upper magnetic pole layer 4 and a lower magnetic pole layer 5 which are connected to the front end region A by an intermediate region whose width is increased toward the rear region B has already been proposed (Japanese Patent Application No. Hei 10 (1999) -135242). 3-125557).

This magnetic pole shape corresponds to a shape in which both sides of the latter half of the rear area B shown in FIG. 6 are linearly cut off, and disclosed in Japanese Patent Laid-Open Nos. 55-84019 and 3-46109. In comparison with the thin film magnetic head, the reduction of the inductance due to the reduction of the area of the pole layers 4 and 5 can be expected, the high density recording can be positively supported, and the S / N ratio can be improved. Although, an additional effect can be obtained, the effect of reducing the popcorn noise, which is the original purpose, is not sufficient.

The present invention has been made in view of the above circumstances, and an object thereof is to propose a magnetic pole shape capable of effectively suppressing the generation of popcorn noise, and to provide a thin film magnetic head having good recording and reproducing characteristics. And

[0014]

A thin-film magnetic head according to the present invention comprises a conductor coil having a plurality of turns in an insulating layer sandwiched between a pair of magnetic pole layers, and the turns are arranged on one side of the turns in parallel. In a thin film magnetic head in which a conversion gap sandwiching a non-magnetic layer between both magnetic pole layers and a rear gap on which the two magnetic pole layers directly contact each other are formed to form a yoke, a rear region of both magnetic pole layers is provided. Connects the first region forming the rear gap over the entire width thereof and the second region having a substantially constant width wider than the first region, and linearly reduces the width toward the first region. It is characterized in that it is composed of a connection area.

[0015]

In the present invention, attention is paid to the effect of suppressing the generation rate of popcorn noise due to the increase of the side surface angle θ in the rear area, and also to the effect of suppressing the popcorn noise due to the stabilization of the magnetic domain, which is wider than the tip area. A shape having a constant width (side angle θ = 90 °) and a shape in which both sides of the rear gap on the rear end side are cut off leaving the equivalent width of the rear gap, that is, the first region forming the rear gap over the entire width. And the second region having the constant width form a rear region having a shape connected by a connecting region having a width reduced toward the former.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a partially cutaway perspective view showing a main part of a thin film magnetic head according to the present invention, and FIG. 2 is a plan view of the same.

The basic structure of the thin-film magnetic head according to the present invention is the same as the conventional one, and a conductor coil 1 having a plurality of turns 10, 10 in one plane is provided in a plurality of stages in an insulating layer 2 made of thermosetting resin or the like. (Two steps in this figure), the gap layer 3 made of a non-magnetic material is laminated on one surface side of the insulating layer 2, and these are collectively formed as an upper magnetic pole layer 4 made of a NiFe alloy or the like. The magnetic pole layers 4 and 5 are sandwiched between the lower magnetic pole layer 5 and the magnetic pole layers 4 and 5 extending to one side in the juxtaposing direction of the turns 10 with a predetermined width and extending to the same side. The gap layer 3
To form a conversion gap, and at the end of the gap layer 3 on the other side in the juxtaposed direction, a rear gap 6 in which both magnetic pole layers 4 and 5 are in direct contact is formed to form a yoke 7. The structure is such that this is deposited on the base 8 on the side of the lower magnetic pole layer 5.

The upper magnetic pole layer 4 and the lower magnetic pole layer 5 constituting the yoke 7 have substantially the same shape in a plan view, and as shown in FIG. 2, these magnetic pole layers 4 and 5 have a substantially constant narrow width. And the rear region B including the portion where the rear gap 6 is formed is connected to the front end region A that sandwiches only the gap layer 3 and forms the conversion gap by the intermediate region C that reduces the width toward the former. It becomes.

The rear region B and the first region B ₁ contacting each other over the entire width to form the rear gap 6,
A second region B ₂ that is continuous with the intermediate region and has a substantially constant width wider than the first region B ₁ , and the second region B ₂ to the first region B ₁
And a connecting region B ₃ for connecting the both while linearly reducing the width toward.

That is, the above-described shape of the rear region B is the second region B ₂ having a constant width and extending to a position corresponding to the rear gap 6.
Is cut off on both sides of the rear gap 6 leaving a necessary width to form a first region B _1, and a straight line is formed between the first region B ₁ and the second region B ₂ whose width is reduced as a result of the cutting. It corresponds to the connection in the trapezoidal connection region B ₃ having side edges that are inclined toward each other.

First, the yoke 7 having the above-described structure has a planar shape shown in FIG. 2, and the lower magnetic pole layer 5 made of a NiFe alloy is formed on the surface of the base body 8. An extremely thin gap layer 3 made of a non-magnetic material such as Al ₂ O ₃ (alumina) is formed on the entire surface except the region B ₁ , and then a portion to be the tip region A on the surface of the gap layer 3 and the lower magnetic pole layer 5 are formed. After forming the insulating layer 2 on the surface of the gap layer 3 and the surface of the base 8 except the first region B ₁ , the spiral conductor coil 1 having the turns 10, 10 ... On the gap layer 3 is formed. The process of forming the insulating layer 2 on the surface of the insulating layer 2 and stacking the insulating layer 2 on the upper surface of the insulating layer 2 is repeated to integrally form the insulating layer 2 having a predetermined thickness and enclosing the two-stage conductor coils 1 and 1. Finally, on the surface of the insulating layer 2 and the gap layer 3 protruding on a part thereof, In correspondence with the section pole layer 5 forming the upper magnetic pole layer 4, the first region B ₁ of both the magnetic layer 4, 5 to each other are joined in a non-formation portion of the insulating layer 2 and the gap layer 3, the rear It is obtained by forming the gap 6.

The rear regions B of the upper and lower magnetic pole layers 4 and 5 in the thin film magnetic head according to the present invention correspond to the conventional rear region B shown in FIG. 6 whose side surface angle θ is 90 °. It is expected that the generation rate of popcorn noise will be reduced, and the magnetic domain is stabilized by cutting off the part that causes the unstable magnetic domain around the rear gap 6, and further reduction of the generation rate of popcorn noise is expected. it can.

In the connection region B ₃ , the magnetization direction of the reflux magnetic domain becomes oblique and becomes a phase delay component, which is harmful from the viewpoint of reducing popcorn noise, but the connection region B ₃ has a constant width. This is effective for preventing the recording / reproducing efficiency from being lowered due to the adoption of the second area B ₂ that it has. That is,
In order to reduce the popcorn noise, it is desirable to make the opening angle α of the connection area B ₃ as large as possible, but if the opening angle α is too large, the recording / reproducing efficiency will be lowered. From these, the opening angle α is 120 °
It is desirable to set it to ˜175 °.

Finally, a test conducted to confirm the effect of the thin film magnetic head according to the present invention having the above-mentioned structure will be described. In this test, as shown in the time chart of FIG. 3, first, the write operation is performed under the condition that the write current is 20 mAop and the write time is 200 μsec, and then the post write recovery time of 20 μsec is elapsed. Wait for the process of performing the read operation under the condition that the read time is 180 μsec.
Repeated for a second, the procedure for checking the occurrence rate of popcorn noise was performed.

Since the occurrence rate of popcorn noise is easily influenced by the measurement conditions, the measurement conditions are strictly controlled, the white noise level is assumed to be 30 μVop, and the noise threshold voltage for popcorn noise detection is set to 40 μVop. It was determined that popcorn noise occurred when noise having a level higher than this was detected. As a result,
In the conventional thin film magnetic head shown in FIG.
The number of popcorn noise detected in the test time of 20 seconds
The number of popcorn noises detected in the thin-film magnetic head according to the present invention was 0 to 2 in the same test time, while the number of popcorn noises reached to 1000, and the occurrence rate of popcorn noise was significantly reduced. Became.

FIG. 4 shows the inductance of the thin-film magnetic head according to the present invention and the calculation result of the head noise calculated using the inductance, the thin-film magnetic head disclosed in Japanese Patent Laid-Open No. 3-46109, and the above-mentioned Japanese Patent Application. 6 is a graph showing comparison with each of the thin film magnetic heads proposed in Hei 3-125557.

The plane shapes of the pole layers 4 and 5 of the thin film magnetic head disclosed in Japanese Patent Laid-Open No. 3-46109 are substantially the same as those shown in FIGS. 5 and 6, and are increased from the tip region A. While having a fan-shaped rear region B that extends rearward,
It is obvious that it has a head inductance larger than that of the thin film magnetic head proposed in Japanese Patent Application No. 3-125557. The □ mark in FIG. 4 is the predicted value of the thin film magnetic head disclosed in Japanese Patent Laid-Open No. 3-46109, and the ◯ mark is the Japanese Patent Application No. 3-12.
These are the calculation results of the thin-film magnetic head proposed in No. 5557, and the latter advantage is clear in terms of head noise reduction.

The mark ● in FIG. 4 shows the calculation result of the thin film magnetic head according to the present invention. As described above, the thin film magnetic head according to the present invention corresponds to the thin film magnetic head proposed in Japanese Patent Application No. 3-125557 with the vicinity of the rear gap 6 cut off in the rear region B. Inductance and head noise can be expected to be reduced by reducing the area of No. 5, and in practice the thin film magnetic head proposed in Japanese Patent Application No. 3-125557 produces a head noise of about 3.2 μVrms, whereas the thin film magnetic according to the present invention It has been clarified that the head only produces a head noise of about 2.7 μVrms and a noise reduction effect of about 16% can be obtained.

[0029]

As described above in detail, in the thin-film magnetic head according to the present invention, the rear regions of the pair of magnetic pole layers forming the yoke are the first region forming the rear gap over the entire width, By forming the second area having a wide and substantially constant width and the connecting area that linearly changes the width and connects the two, the generation rate of popcorn noise is significantly increased without deteriorating the recording / reproducing characteristics. The present invention has excellent effects such as a reduction in time, a transition time to a reproduction operation after a recording operation can be shortened, and high density recording and a high transfer rate can be supported.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a main part of a thin film magnetic head according to the present invention.

FIG. 2 is a plan view of a thin film magnetic head according to the present invention.

FIG. 3 is a time chart showing writing and reading timings in a comparison test of the occurrence rate of popcorn noise between the product of the present invention and the conventional product.

FIG. 4 is a graph showing a comparison result of head noise between a product of the present invention and a conventional product.

FIG. 5 is a partially cutaway perspective view showing a main part of a conventional thin film magnetic head.

FIG. 6 is a plan view of a conventional thin film magnetic head.

[Explanation of symbols]

1 conductor coil 2 insulating layer 3 gap layer 4 upper magnetic pole layer 5 lower magnetic pole layer 6 rear gap 7 yoke 8 base A tip region B rear region B ₁ first region B ₂ second region B ₃ connecting region

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kazuyoshi Kubota 4-53-3 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd. (72) Inventor Masayuki Takagishi 4-chome, Kitahama, Chuo-ku, Osaka City, Osaka Prefecture 5-33 Sumitomo Metal Industries, Ltd. (72) Inventor, Kiichiro Goda 4-53-3 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd.

Claims (1)

[Claims] 1. A conversion gap including a conductor coil having a plurality of turns in an insulating layer sandwiched between a pair of magnetic pole layers, and a non-magnetic layer sandwiched between the magnetic pole layers on one side in a direction in which each turn is arranged in parallel. In a thin film magnetic head in which a yoke is formed by forming a rear gap in which the two pole layers are in direct contact with each other, a rear region of the both pole layers forms the rear gap over the entire width thereof. A thin film magnetic head comprising: a first region, a second region having a substantially constant width wider than the first region, and a connecting region connecting the two regions and linearly reducing the width toward the first region. ..