JPH0963019A - Magnetic resistant effect type head and magnetic disk device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect an MR film from an electrostatic damage by preventing a discharge current from flowing to the GND through the MR film when the static electricity charged on a recording medium discharges. SOLUTION: The discharge current from a recording medium 5 is prevented from flowing in an MR film 6 at the time of a floating by providing an grounding member 1 at the position nearest to the recording medium 5. The end part 1a of the grounding member 1 is joined to a slider 2 and the other end part 1b is prolonged toward the recording medium 5 to the air bearing surface(ABS) of a slider rail 3 or to the vicinity of the surface. Consequently, when the static electricity charged on the recording medium 5 is discharged toward the MR head 9, the discharge current is guided to the end part 1b of the grounding member 1 to be made to flow to the GRD from the end part 1a via the slider 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive head, and more particularly to a magnetoresistive head having a structure for preventing the influence of a discharge current from a recording medium.
The present invention relates to a magnetic disk device using this head.

[0002]

2. Description of the Related Art In a magnetic disk device (hereinafter referred to as HDD), a magnetoresistive effect, which is remarkable in a ferromagnetic thin film, is utilized so that the output does not depend on the medium speed and a large output can be obtained. Magnetoresistive heads (hereinafter referred to as MR heads) have come to be used.

FIG. 5 is a perspective view showing the structure of a conventional MR head. FIG. 5 (a) is an overall view, and FIG. 5 (b) is a partially enlarged view of the head portion. Further, FIG. 6 shows a conventional M
FIG. 6 is a side view showing a state in which the R head is levitated from the recording medium.

On the surface of the slider 2 of the MR head 9 facing the recording medium 5, two slider rails 3 are provided in the circumferential direction of the recording medium 5, and when the recording medium 5 rotates, air is generated. It is configured to flow. A head portion 9a for recording / reproducing data is formed on the air outflow side of the slider rail 3 by a thin film method.

In the head portion 9a, 6 is an MR layer,
7 is a magnetic core, 8 is an insulating layer, 11 is an insulating layer, 12 is a magnetic core (for inductive), 13 is a coil (for inductive: a write current flows), 16 is a read pattern, and 17 is an inductive gap film. . In addition,
Since the structure of the head portion 9a is well known, its detailed description is omitted here.

The MR head 9 is attached to the carriage mechanism via the suspension 4, and is floated by the rotation of the recording medium 5 to record or reproduce data. Data recording is performed by generating a recording magnetic field in the inductive gap film 17. Data playback is M
The R film 6 is used. A lead pattern 16 is formed on the MR film 6.
The lead pattern 16 passes a sense current through the MR film 6 and senses a reproduction output voltage according to the resistance change rate of the MR film 6.

By the way, since the surface of the recording medium 5 used in the HDD is covered with an insulating material such as a protective film and a lubricating film, the static electricity generated in the recording medium 5 is charged on the recording medium 5 without flowing out. . At that time, since the MR head 9 flies over the surface of the recording medium 5 with a low flying height of 0.1 μm or less, the charging potential of the recording medium 5 is the dielectric strength of air (1 atmospheric pressure,
If it exceeds 3.5 KV / mm at around 20 degrees, discharge is performed toward the MR head 9.

Normal discharge often occurs toward a place having a narrow insulation distance or to a good conductive material such as metal. When a discharge occurs in the MR film 6 of the MR head 9, a discharge current flows from the good conductive material connected to the MR film 6 to the GND via the lead pattern (lead wire) 16.

When electric discharge occurs in the magnetic core 7 of the MR head 9, G is transferred via the slider 2 and the suspension 4.
When a discharge current flows in the ND, and when the magnetic core 7 passes through the MR film 6 and the lead pattern (lead wire) 16
Discharge current may flow to the.

Between the magnetic core 7 and the slider 2, Al
_Since the insulating layer 8 such as ₂ O ₃ is formed with a thickness of about 10 μm,
This part has a high resistance. An insulating layer 11 made of Al ₂ O ₃ or the like is also formed between the one magnetic core 7 and the MR film 6, but its thickness is 0.2 μm or less. Therefore, even if the discharge reaches the magnetic core 7, the discharge current easily flows from the magnetic core 7 through the MR film 6.

In this case, the MR film 6 is a thin film of 20 to 30 nm and has a width of about 2 μm, so that the cross-sectional area is very small. When a discharge current flows here, the generated Joule heat exceeds the allowable limit of the MR film 6 even if the current is low,
The MR film 6 is burned and destroyed, and the ability as a magnetic head is lost.

[0012]

As described above, conventionally, when static electricity charged on the recording medium 5 is discharged toward the MR head 9, the discharge current flows into the MR film 6 of the MR head 9, and There was a problem of losing the ability as a head.

Incidentally, such a phenomenon can occur not only in the MR head but also in a general inductive head.
7 and 8 show the structure of a general inductive head.

7A and 7B are perspective views showing the structure of a general inductive head. FIG. 7A is an overall view, and FIG. 7B is a partially enlarged view of the head portion. Further, FIG. 8 is a side view showing a state in which the inductive head is levitated from the recording medium. The same members as those in FIGS. 5 and 6 are designated by the same reference numerals.

The inductive head 18 is attached to the carriage mechanism via the suspension 4.
The recording medium 5 is floated by the rotation of the recording medium 5 to record or reproduce data. In this case, the recording and reproduction of data is performed by the head portion 18a provided on the air outflow side of the slider rail 3.
The inductive gap film 17 of FIG.

Here, as in the case of the MR head 9, the static electricity charged on the recording medium 5 is discharged toward the inductive head 18, and the discharge current flows into the coil 13 via the inductive gap 17 and the coil 13 is discharged. The magnetic circuit including the core 12 is destroyed.

However, since the film thickness of the inductive gap 17 is comparatively thick and the coil 13 is also provided at a deep place, the magnetic circuit is destroyed unless a high current flows into the inductive gap 17. It will not be done. Therefore, the inductive head 1
In the case of 8, it can be considered that the influence of the discharge current is small due to its structure.

On the other hand, since the MR head 9 has the MR film 6 in addition to the inductive gap 17,
For the above-mentioned reason, when there is a discharge, the MR film 6 is destroyed even if the discharge current is low, so the effect is very large.

The present invention has been made in view of the above points, and prevents the discharge current from flowing into the GND through the MR film when the static electricity charged on the recording medium is discharged.
An object of the present invention is to provide a magnetoresistive head capable of protecting the MR film from electrostatic breakdown and a magnetic disk device using the head.

[0020]

According to the present invention, in a magnetoresistive head having an MR film at an air outflow side end of a slider having conductivity, a grounding member is provided at a position closest to the recording medium when flying. Is provided to prevent the discharge current from the recording medium from flowing into the MR film.

The grounding member is made of a wire or plate of a good conductive material, one end of which is in electrical contact with the slider or a suspension for supporting the slider, and the other end of which is the best contact with the recording medium when flying. It is provided near the recording medium.

With this structure, when static electricity charged on the recording medium is discharged, the discharge current flows to GND via the slider or the suspension by the ground member. As a result, it is possible to prevent the discharge current from the recording medium from flowing into the MR film and prevent the discharge film from destroying the MR film.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a perspective view showing the overall configuration of a magnetic disk device according to a first embodiment of the present invention. This device has a recording medium (disk)
5, the MR head 9, a head arm 51, a carriage 52, a carriage drive motor 53, a recording medium drive motor 54, and the like, and a control circuit 55 for driving and controlling the mechanism. The mechanism has a hermetic structure in which cleanliness is secured against the outside air.

On the recording medium 5, servo information for head positioning control is provided in advance for each sector by the data surface servo system. The MR head 9 moves in the radial direction of the recording medium 5 via the head arm 51 to record / reproduce data on / from the recording medium 5. The structure of the MR head 9 will be described later with reference to FIGS. 2 and 3.

The head arm 51 has one end supporting the MR head 9 via the suspension 4 and the other end rotatably provided on the carriage 52. The carriage 52 is
The head arm 5 is driven by the carriage drive motor 53.
The MR head 9 is moved by rotating 1.

The carriage drive motor 53 is a motor for driving the carriage 52, and is composed of a voice coil motor. The recording medium drive motor 54 drives the recording medium 5
It is a motor for rotating, and is composed of a spindle motor.

The control circuit 55 is composed of a read / write circuit for recording / reproducing data, a servo circuit for controlling the positioning of the MR head 9 based on servo information, and the like.

2A and 2B are perspective views showing the structure of the MR head according to the first embodiment. FIG. 2A is an overall view and FIG. 2B is a partially enlarged view of the head portion. . Further, FIG. 3 is a side view showing a state where the MR head in the first embodiment floats above the recording medium.

On the surface of the slider 2 of the MR head 9 facing the recording medium 5, two slider rails 3 are provided in the circumferential direction of the recording medium 5, and air is generated when the recording medium 5 rotates. It is configured to flow. A head portion 9a for recording / reproducing data is formed on the air outflow side of the slider rail 3 by a thin film method.

In the head portion 9a, 6 is an MR layer,
7 is a magnetic core, 8 is an insulating layer, 11 is an insulating layer, 12 is a magnetic core (for inductive), 13 is a coil (for inductive: a write current flows), 16 is a read pattern, and 17 is an inductive gap film. . In addition,
Since the structure of the head portion 9a is well known, its detailed description is omitted here.

The MR head 9 is attached to the carriage mechanism via the suspension 4, and is floated by the rotation of the recording medium 5 to record or reproduce data. Data recording is performed by generating a recording magnetic field in the inductive gap film 17. Data playback is M
The R film 6 is used. A lead pattern 16 is formed on the MR film 6.
The lead pattern 16 passes a sense current through the MR film 6 and senses a reproduction output voltage according to the resistance change rate of the MR film 6.

Here, in the first embodiment, the ground member 1 is provided at the tip of the MR head 9 (the end of the slider 2 on the air outflow side). This earth member 1 is M
This is for preventing a discharge current from the recording medium 5 from flowing into the R film 6, and is provided at a position closest to the recording medium 5 when the MR head 9 is levitated. An insulating layer 15 is provided so as to cover the ground member 1.

The ground member 1 is made of a wire or plate of a good conductive material (for example, permalloy, gold, etc.), and one end 1a thereof has a conductive slider 2 (for example, AlTiC).
Is electrically bonded to. The other end 1b of the ground member 1 extends toward the recording medium 5 to the air bearing surface (ABS) of the slider rail 3 or the vicinity thereof.

The slider 2 is electrically joined to a suspension 4 having conductivity, and the suspension 4 is further passed through a PCB (wiring circuit board) or HDD frame from a system case such as a personal computer to GND.
Is electrically connected to.

The thickness W of the ground member 1 is approximately equal to the thickness of the MR magnetic core 7, and is, for example, about 2 to 3 μm. Further, in the MR head 9, the slider rail 3
Has a length L1 of 1.6 to 2.0 mm, while the head portion 9a has a length L2 of about 30 .mu.m.

According to this structure, the earth member 1 (volume resistivity ρ <, which is provided at the tip of the MR head 9 (the end of the slider 2 on the air outflow side) and is made of a wire or plate of a good conductive material. 100 [μΩ-cm] is a standard, and AlTiC (ρ = 2) of a slider material that is generally used.
000 to 3000 [μΩ-cm]). Therefore, as viewed from the material, the discharge current flows more easily in the ground member 1 than in the slider 2.

When the MR head 9 floats above the recording medium 5, the MR head 9 tilts as shown in FIG. At that time, since the other end 1b of the ground member 1 is located at the position closest to the recording medium 5, the discharge current flows through the ground member 1 rather than the air bearing surface (ABS) of the slider rail 3 from the viewpoint of the structure. It will be easier.

Here, the magnetic core 7 sandwiching the MR film 6
Is made of permalloy, the permalloy is a good conductive material (ρ = 25 [μΩ-cm]), and M
Since the distance between the R head 9 and the recording medium 5 is the minimum, the magnetic core 7 is better than the slider 2 in terms of both material and structure.
The discharge current will easily flow to. In this case, the magnetic core 7 has the same ease of flow as the earth member 1, and the discharge current flows through both with the same probability.

However, the magnetic core 7 includes the slider 2 and an insulating layer 8 (ρ = 10 ¹⁴ [μΩ-cm]) such as Al ₂ O ₃ .
Are electrically insulated from each other, and are also electrically insulated from the suspension 4. One earth member 1
Is finally electrically connected to GND through the slider 2, so that the discharge current flows far more to the ground member 1 than the magnetic core 7.

If permalloy is used as the material of the grounding member 1, the permalloy is a magnetic material having a high magnetic permeability (also a good conductive material), and the magnetic core 7 of the MR head 9 is made.
Since it is the same as the material generally used as the material of the MR film 6 and the MR film 6, it is not necessary to add a special material, and the thin film process can be facilitated.

In this case, since the other end 1b of the earth member 1 is exposed to the air bearing surface (ABS) of the slider rail 3 like the magnetic core 7 and the MR film 6, the durability to the use environment of the same degree as these, Has stability.

If gold is used as the material of the grounding member 1, gold is a better conductive material than permalloy (ρ = 2.3).
[ΜΩ-cm]), which is chemically stable, is a material more suitable for the purpose of the present invention than permalloy.

For the above reasons, when the static electricity charged on the recording medium 5 is discharged toward the MR head 9,
The discharge current is guided to the end 1b of the ground member 1 and flows from the end 1a to the GND via the slider 2. As a result, the discharge current from the recording medium 5 is generated by the MR film 6.
Flow into the MR and its discharge current
It is possible to prevent the membrane 6 from being destroyed.

(Second Embodiment) Next, a second embodiment of the present invention will be described. FIG. 4 is a side view showing a state where the MR head according to the second embodiment of the present invention is levitated from the recording medium. Since the basic configuration is the same as that of the first embodiment, only different points will be described here.

In the second embodiment, the ground member 10 is attached to the tip of the MR head 9 (the end of the slider 2 on the air outflow side).
Is provided. The grounding member 10 is provided to prevent the discharge current from the recording medium 5 from flowing into the MR film 6, and is provided at the position closest to the recording medium 5 when the MR head 9 floats. Also, this ground member 1
An insulating layer 15 is provided so as to cover 0.

The ground member 10 is made of a wire or plate of a good conductive material (for example, permalloy, gold, etc.), and one end 10a thereof is electrically joined to the conductive suspension 4. In addition, the other end 10b of the ground member 10
Are extended toward the recording medium 5 up to or near the air bearing surface (ABS) of the slider rail 3.

The thickness W of the ground member 1 is substantially equal to the thickness of the MR magnetic core 7, and is, for example, about 2 to 3 μm. Further, in the MR head 9, the slider rail 3
Has a length L1 of 1.6 to 2.0 mm, while the head portion 9a has a length L2 of about 30 .mu.m.

According to this structure, the suspension 4 is generally made of stainless steel (ρ = 100 to 200 [μ
.OMEGA.-cm]) and electrically connecting the suspension 4 and the ground member 10 to each other, the discharge current from the recording medium 5 can be supplied to the GND as in the first embodiment.

In this case, since the slider 2 is not used, the resistance becomes lower than that in the case of the first embodiment, and the discharge current further easily flows through the ground member 10. This allows
It is possible to prevent the discharge current from the recording medium 5 from flowing into the MR film 6 and prevent the MR film 6 from being destroyed by the discharge current. Further, if permalloy or gold is used as the material of the earth member 10, the same effect as in the first embodiment can be obtained.

[0050]

As described above, according to the present invention, in the magnetoresistive head having the MR film at the end on the air outflow side of the slider having conductivity, the magnetoresistive head is located at the position closest to the recording medium when flying. Since the discharge current from the recording medium is prevented from flowing into the MR film by providing the ground member, when the static electricity charged in the recording medium is discharged, the discharge current flows into the GND through the MR film. And protect the MR film from electrostatic breakdown.

[Brief description of drawings]

FIG. 1 is a perspective view showing an overall configuration of a magnetic disk device according to a first embodiment of the present invention.

2A and 2B are perspective views showing a structure of an MR head according to the first embodiment, FIG. 2A is an overall view, and FIG. 2B is a partially enlarged view of a head portion.

FIG. 3 is a side view showing a state in which the MR head according to the first embodiment is levitated from the recording medium.

FIG. 4 is a side view showing a state where the MR head of the second embodiment of the invention is levitated from the recording medium.

FIG. 5 is a perspective view showing the structure of a conventional MR head,
The figure (a) is a general view, and the figure (b) is a figure which partially enlarges and shows a head part.

FIG. 6 is a side view showing a state in which a conventional MR head is levitated from a recording medium.

7A and 7B are perspective views showing a structure of a general inductive head, FIG. 7A is an overall view, and FIG. 7B is a partially enlarged view of a head portion.

FIG. 8 is a side view showing a state in which the inductive head floats above a recording medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ground member 2 ... Slider, 3 ... Slider rail, 4 ... Suspension, 5 ... Recording medium, 6 ... MR film, 7 ... Magnetic core, 8, 11 ... Insulating layer, 9 ... MR head, 10 ... Ground member, 12 ... magnetic core (for inductive), 13 ... coil (for inductive), 14, 15 ... insulating layer, 16 ... lead pattern, 17 ... inductive gap 18 ... inductive head.

Claims (6)

[Claims] 1. An electrically conductive slider has an MR film at the end on the air outflow side, and a grounding member for preventing a discharge current from a recording medium from flowing into the MR film is used for the above-mentioned recording when flying. A magnetoresistive head, which is provided at a position closest to the medium. 2. The ground member is made of a wire or plate made of a material having good conductivity, one end of which is in electrical contact with the slider, and the other end of which is attached to the recording medium at a position closest to the recording medium when flying. The magnetoresistive head according to claim 1, wherein the magnetoresistive head is provided for the head. 3. The ground member is made of a wire or plate of a good conductive material, one end of which is in electrical contact with a suspension for supporting the slider, and the other end of which is closest to the recording medium when flying. The magnetoresistive head according to claim 1, wherein the magnetoresistive head is provided at a position facing the recording medium. 4. The magnetoresistive head according to claim 1, wherein the ground member is made of permalloy. 5. The magnetoresistive head according to claim 1, wherein the ground member is made of gold. 6. An electrically conductive slider has an MR film at an end on the air outflow side, and a grounding member for preventing a discharge current from a recording medium from flowing into the MR film is used for the above-mentioned recording during floating. A magnetic disk drive comprising a magnetoresistive head provided at a position closest to a medium.