JPH0562131A - Composite magnetic head - Google Patents

Abstract

PURPOSE:To make constant a reproduced output of a composite magnetic head by reducing magnetic flux leakage from a commonly used thin film magnetic core to an MR magnetism sensitive section. CONSTITUTION:An MR head constituting a magnetic gap g1 for reproduction and an inductive head constituting another magnetic gap g2 for recording are piled up on a substrate 2 in such a state where the heads are exposed to the surface 1 of this composite magnetic head which is brought into contact with magnetic recording media. The head winding 16 of the inductive head is electrically connected to the bias conductor 5 of the MR head and, at the same time, the second thin film magnetic core 10 which is the common magnetic body of the inductive and MR heads is divided into two parts by means of a nonmagnetic layer 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite magnetic head suitable for recording / reproducing on / from a hard disk, for example.

[0002]

2. Description of the Related Art For example, a recording / reproducing head of a hard disk drive device is a recording head using an induction type magnetic head (hereinafter referred to as an inductive head) and a magnetoresistive effect type magnetic head (hereinafter referred to as an "inductive head") having excellent short wavelength sensitivity. , M
It is called an R head. ) Is generally a composite type with a reproducing head.

As such a composite magnetic head, for example, one having a structure as shown in FIG. 4 is known. This magnetic head is provided with a reproducing magnetic gap on a substrate 51 called a slider made of, for example, Al ₂ O ₃ —TiC, facing a hard disk contact surface, that is, an ABS (air bearing surface) surface 52. The MR head forming g ₁ and the inductive head forming the recording magnetic gap g ₂ are laminated.

The MR head has a magnetoresistive effect sensitive section (hereinafter referred to as an MR sensitive section) 55 which is composed of a magnetoresistive effect thin film in which electrodes 53 and 54 are laminated at the front end and the rear end, respectively.
And a bias conductor 56 that gives the MR magnetic sensing section 55 a magnetized state in a desired direction.
It is sandwiched by a pair of thin film magnetic cores 58 and 59 that magnetically shield 5 through the insulating layer 57.

On the other hand, in the inductive head, the upper layer thin-film magnetic core 59 that shields the MR magnetic sensing section 55 is used as one thin-film magnetic core forming a closed magnetic path, and the other thin-film magnetic core 59 is laminated so as to face the thin-film magnetic core 59. And the recording magnetic gap g ₂ facing the ABS surface 52 with the thin film magnetic core 60.
Is configured. That is, the MR magnetic sensing unit 5
The thin-film magnetic core 60, which is laminated so as to face the upper-layer thin-film magnetic core 59 that shields 5, is bent toward the thin-film magnetic core 59 that functions as a shield at the front end portion facing the ABS surface 52, and the gap is narrow. The recording magnetic gap g ₂ is formed in the facing portion.

The thin-film magnetic core 60 is connected to the upper-layer thin-film magnetic core 59 that shields the MR magnetic sensitive section 55 on the back side, and the thin-film magnetic core 59 that functions as the shield forms a closed magnetic path. It is like this. Further, a head winding 61 for applying a magnetic field based on recorded information to the thin film magnetic cores 59 and 60.
Is provided in a spiral shape so as to surround the magnetic coupling portion 62 which is the connection portion of the thin film magnetic cores 59 and 60. The head winding 61 is embedded with an insulating layer 57 in order to electrically insulate it from the thin film magnetic cores 59 and 60.

The composite type magnetic head having the above-mentioned structure has a so-called shield type MR head in which a pair of thin film magnetic cores 58 and 59 sandwiching the MR magnetic sensitive portion 55 are magnetic shields, and one thin film magnetic core 59. A so-called two-gap type head structure is used in which an inductive head which is used as a core forming a magnetic path and which forms a closed magnetic path by the other thin film magnetic core 60 is laminated on the same substrate 51. In the recording in this composite type magnetic head, a current from an AC power supply is supplied to the terminal portion drawn out from the head winding 61, and a magnetic flux based on the recording information is generated from the recording magnetic gap g ₂ facing the ABS surface 52. On the other hand, in reproducing, the MR magnetic sensing section 55 is supplied with current from a DC power source through terminal portions drawn out from the front electrode 53 and the rear electrode 54, which are laminated on the front and rear ends of the MR magnetic section 55, respectively. 55
A sense current is applied to the MR conductor 55 and a direct current is applied to the terminal portion of the bias conductor 56 so that the MR magnetic sensing portion 55 is magnetized in a desired direction.

[0008]

By the way, in the composite magnetic head having the above-mentioned structure, the MR magnetic sensing section 5 is used.
5, each of the bias conductor 56 and the head winding 61 has two terminals, so that the total number of terminals of the head is 6 in total.
It becomes an individual. If the number of terminals is large as described above, the arrangement area of the terminals with respect to the slider 51 is increased, the slider 51 is not only increased in size, but also a problem occurs in wire assembly due to the extraction of the metal wire wire-bonded from the terminal to the terminal. .. Therefore, in the above configuration, the slider 5
It is difficult to reduce the size, and it will be difficult to support hard disk drive devices, which are expected to be further downsized and have higher recording capacities in the future.

Therefore, in order to reduce the number of terminals, the applicant of the present application first attempts to reduce the number of terminals to four as a whole by electrically connecting the head winding 61 and the bias conductor 56. Has been done. Specifically, as shown in FIG. 5, the head winding 61 and the bias conductor 56 are connected in parallel so that their terminals are commonly used. As a result, the number of terminals in the entire head is
There are a total of four terminals including the two terminals of the front end electrode 53 and the rear end electrode 54 of the MR magnetic sensing part 55. In this way, the head winding 61
When the and the bias conductor 56 are connected to each other, recording / reproducing is performed by sequentially switching the common terminal portions 63a and 63b to the AC power source 64 and the DC power source 65. That is, the common terminals 63a and 63b are connected to the AC power supply 64 when recording, and the common terminals 63a and 63b are connected to the DC power supply 65 when reproducing.

However, with the above configuration, the bias current supplied during reproduction flows not only in the bias conductor 56 but also in the head winding 61, and in addition to the magnetic flux generated in the bias conductor 56, this bias current is generated. Head winding 61
Thin-film magnetic core 5 in which the magnetic fluxes generated in
A large magnetic flux will flow to 9. Further, since the vicinity of the bias conductor 56 has a laminated structure, a step difference in shape occurs,
Due to this shape step, magnetic flux flowing from the lower surface of the common thin film magnetic core 59 (the surface facing the bias conductor 56) to the thin film magnetic core 59 leaks. Therefore, the MR magnetic sensing unit 5
In addition to the bias magnetic field from the bias conductor 56, a magnetic field generated by the current flowing through the head winding 61 is applied to 5 as a kind of bias magnetic field.

If this kind of bias magnetic field is constant, the stability of the output level will only slightly fluctuate at a level at which there is no practical problem, but of the thin film magnetic core 60 that determines the recording track width. Since the core width near the magnetic gap portion is narrow, the magnetic domain becomes unstable or the magnetic domain changes. As a result, the magnetic flux leaking from the head winding 61 fluctuates, which causes fluctuations in the bias magnetic field of the MR magnetic sensing section 55, resulting in fluctuations in output and changes in waveform. In particular, this variation is noticeable after recording.

Therefore, the present invention has been proposed in view of the above-mentioned technical problems, and reduces the leakage magnetic field from the common thin film magnetic core to the MR magnetic sensitive section to cause fluctuations in reproduction output. An object of the present invention is to provide a highly reliable composite magnetic head.

[0013]

In order to achieve the above object, the present invention provides a magnetic recording medium in which a magnetoresistive effect magnetic sensitive section is arranged between a first thin film magnetic core and a second thin film magnetic core. The third thin film magnetic core forming a closed magnetic path by the magnetoresistive effect magnetic head having a magnetic gap for reproduction facing the contact surface with the second thin film magnetic core. A thin film magnetic core is laminated on the same substrate as the thin film magnetic core, and an induction type magnetic head forming a recording magnetic gap facing the contact surface with the magnetic recording medium between the front end portions of these thin film magnetic cores. In the composite magnetic head, the head winding of the inductive magnetic head and the bias conductor of the magnetoresistive effect magnetic head are electrically connected, and the second thin film magnetic core sandwiches at least two layers across the nonmagnetic layer. It is characterized as being It is intended to.

[0014]

In a so-called two-gap type recording / reproducing head in which an MR head forming a reproducing magnetic gap and an inductive head forming a recording magnetic gap are laminated on a substrate facing a contact surface with a magnetic recording medium, Since the head winding of the head and the bias conductor of the MR head are electrically connected, the terminals of the head winding and the bias conductor are made common. Therefore, since the number of terminals of the entire head is reduced, the area for arranging these terminals is not required, and the size of the head can be reduced.

Further, in the present invention, a common magnetic body of the inductive head and the MR head, that is, a second thin film magnetic core forming a closed magnetic circuit and magnetically shielding the MR magnetic sensitive portion is sandwiched between the non-magnetic layers to form two layers. Since the structure is adopted, a large amount of magnetic flux generated by the bias current flowing through the head winding during reproduction flows into the magnetic body on the inductive head side separated by the non-magnetic layer, which makes it difficult to flow to the MR magnetic sensing section.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments to which the present invention is applied will be described in detail below with reference to the drawings. As shown in FIGS. 1 and 2, the composite magnetic head of the present embodiment is an MR head in which a reproducing magnetic gap g ₁ is exposed on an ABS surface 1 which is a contact surface with a hard disk, and an ABS head 1 on the ABS surface 1. A so-called 2-gap type recording / reproducing head structure is formed by laminating an inductive head facing the recording magnetic gap g ₂ on one side surface of the slider 2 made of an Al ₂ O ₃ —TiC substrate or the like.

The MR head has a pair of electrodes 3a and 3b (hereinafter, referred to as an electrode 3a provided on the ABS surface 1 side) for passing a sense current from a constant current source (not shown) to the front end portion and the rear end portion, respectively. , Electrode 3b provided on the rear end side
Is referred to as the rear end electrode 3b. ) MR sensitive section 4
And a bias conductor 5 for applying a magnetic field state in a desired direction to the MR magnetic sensing section 4.

The MR magnetic sensing portion 4 is formed as a rectangular pattern slightly narrower than the track width Tw of the recording magnetic gap g ₂ of the inductive head, and its longitudinal direction is perpendicular to the ABS surface 1. It is provided and one edge thereof faces the ABS surface 1. Further, the MR magnetic sensing part 4 is formed of, for example, SiO ₂
A pair of MR thin films that are magnetostatically coupled via a non-magnetic insulating layer made of, for example, are laminated to avoid generation of Barkhausen noise. In addition, MR
The thin film is made of a ferromagnetic thin film such as Permalloy,
The film thickness is about several hundred angstroms.

The tip electrode 3a is formed, for example, as a wiring pattern having a substantially L shape in a plan view, and one end of the tip electrode 3a is laminated on the tip of the MR magnetic sensing section 4 and is formed on the MR magnetic sensing section 4. One side edge of the pattern on the laminated side is the above A
It is exposed on the BS surface 1. The end portion 6 of the wiring pattern that is pulled out from the tip electrode 3a to the back side serves as a ground side terminal portion. On the other hand, the rear end electrode 3b is formed as a wiring pattern having a substantially L shape in a plane like the front end electrode 3a, is provided on the opposite side of the front end electrode 2a across the MR magnetic sensing part 4, and It is laminated on the rear end of the MR magnetic sensing part 4. Then, the end portion 7 of the wiring pattern, which is pulled out from the rear end electrode 3b to the back side, serves as a terminal portion on the current source side.

The bias conductor 5 is formed as an elongated wiring pattern having a rectangular shape in plan view, and is laminated on the MR magnetic sensing section 4 with an insulating layer 8 interposed therebetween at a predetermined distance.
Further, the bias conductor 5 is provided in a direction substantially orthogonal to the MR magnetic sensing section 4, that is, in a form crossing the MR magnetic sensing section 4. And both ends 5 of this bias conductor 5
Reference characters a and 5b are terminal portions for supplying a bias current from a DC power supply. Therefore, this terminal portion 5
The direct current supplied from a and 5b flows in the track width direction which is the longitudinal direction of the wiring pattern. This gives A
A bias magnetic field is applied to the MR magnetic sensing section 4 in a direction orthogonal to the BS surface 1.

In the MR head, the MR thin film magnetic sensing portion 4 is made of a magnetic material such as permalloy or the like with the insulating layer 8 interposed between the first thin film magnetic core 9 and the second thin film magnetic core 1.
It has a so-called shield-type configuration that slips in at 0. The shield type structure is adopted because short wavelength reproduction is required in this type of integrated head, and the reproduction waveform is required to be the same as the differential output waveform of the inductive head in signal processing. The thin film magnetic core 9 provided below the MR magnetic sensing part 4 is made to face the ABS 1 with one end thereof facing the ABS 1 via the insulating layer 8 with the slider 1. It is provided so as to extend in a substantially orthogonal direction.

On the other hand, the other thin film magnetic core 10 provided so as to face the above thin film magnetic core 10 is the same as the above thin film magnetic core 9,
The BS surface 1 is provided so that one end thereof faces the ABS surface 1 and extends in a direction substantially orthogonal to the ABS surface 1, and the portion facing the bias conductor 5 is for preventing escape from the bias conductor 5. The depression is provided. In particular, in this embodiment, the thin-film magnetic core 10 has a pair of magnetic layers 1 with the non-magnetic layer 13 sandwiched therebetween.
1 and 12 are laminated. In other words, the second thin-film magnetic core 10, which is a common magnetic body of the MR head and the inductive head, is separated into the pair of magnetic layers 11 and 12 by the non-magnetic layer 13.

The magnetic layer 12 provided on the MR head side is
The other magnetic layer 11 that functions as a so-called shield core that magnetically shields the MR magnetic sensing unit 4 and that is opposed to the magnetic layer 11 forms a closed magnetic path with a third thin film magnetic core of the inductive head described later. It is designed to function as a core.

The non-magnetic layer 13 provided between the magnetic layers 11 and 12 has a head winding 1 as described later.
The magnetic flux flowing in the magnetic path of the inductive head is caused to flow through the magnetic path of the inductive head as much as possible in the inductive head itself by the current for biasing 6 so that it does not flow to the MR magnetic sensing section 4 side. Therefore, from the viewpoint of preventing leakage of magnetic flux, the thickness of the non-magnetic layer 13 is preferably, for example, about several thousand angstroms to several μm, and more preferably 1 μm or more. The thickness of the nonmagnetic layer 13 is set to several μm, and the nonmagnetic layer 1
If a metal material such as copper is used for 3, the magnetic layers 11 and 12 and the non-magnetic layer 1 can be formed by the same plating process (frame plating).
3 can be sequentially formed. Further, as shown in FIG. 3, the thickness of the magnetic layer 11 on the inductive head side is set to MR.
If the magnetic layer 12 is thicker than the magnetic layer 12 on the head side, most of the magnetic flux generated by the bias current flowing in the head winding 16 flows to the magnetic layer 11 on the inductive head side, and the magnetic layer facing this magnetic layer 11 faces the magnetic layer 11. 12 to MR
The magnetic flux leaking to the magnetic sensitive section 4 side is further reduced.

On the other hand, in the inductive head, the upper magnetic layer 11 is used as the other thin film magnetic core forming a closed magnetic path,
With the third thin film magnetic core 14 laminated facing the magnetic layer 11, a recording magnetic gap g ₂ is formed between the front end portion of the third thin film magnetic core 14 and the ABS surface 1. That is, the third thin-film magnetic core 14 laminated so as to face the upper magnetic layer 11 is bent toward the magnetic layer 11 at the front end facing the ABS 1 and the facing portion is narrowed. And a recording magnetic gap g ₂ is formed. The third thin film magnetic core 14 magnetically contacts the magnetic layer 11 at the rear end to form a back gap.

A spiral head winding 16 is provided on the magnetic coupling portion 15 which is a connection portion between the third thin film magnetic core 14 and the magnetic layer 11 so as to surround the magnetic coupling portion 15. Has been. The head winding 16 is embedded with an insulating layer 8 in order to ensure insulation between the third thin film magnetic core 14 and the magnetic layer 11. Also,
Ends 16a of the winding start and end of the head winding 16,
16b is a terminal portion for passing a recording current from the AC power supply supplied to the head winding 16. The slider 2 is provided on the third thin film magnetic core 12.
An insulating layer 8 is provided which functions as a protective film for protecting the MR head and the inductive head laminated on top.

By the way, in the two-gap type composite magnetic head constructed as described above, as in the conventional head described above, as shown in FIG. 5, the bias conductor 5 of the MR head and the head winding of the inductive head are arranged. 16 and 16 are connected in parallel. As a result, the terminals of the bias conductor 5 and the head winding 16 are made common, and the total number of terminals of the head is 4 terminals including the 2 terminals of the electrodes 3a and 3b of the MR magnetic sensing part 4. Become. As a result, as the number of terminals is reduced, the area for arranging the terminals can be expected to be reduced, so that the slider 2 can be downsized, which is suitable for a magnetic head for a hard disk drive device in which miniaturization and large recording capacity are desired. Will be things. The commonization of these terminals is formed as a wiring pattern on the head chip.

Further, in recording / reproducing with this composite type magnetic head, an alternating current power supply 64 is applied to both terminals 17a and 17b in which the terminals of the bias conductor 5 and the head winding 16 are made common.
And the DC power source 65 are sequentially switched and connected. That is, when recording, the common terminal 17a,
17b is connected to the head winding 1 to generate a current according to the recorded information.
Energize 6. On the other hand, at the time of reproduction, the common terminals 17a and 17b are connected to the DC power supply 65 to give a magnetized state of a desired direction to be applied to the MR magnetic sensing section 4. At the same time, a current from a DC power supply is passed through the front end electrode 3a and the rear end electrode 3b of the MR magnetic sensing unit 4, and a sense current is passed through the MR magnetic sensing unit 4.

By the way, when the head winding 16 and the terminal of the bias conductor 5 are shared as described above, a DC current for bias supplied at the time of reproduction also flows through the head winding 16 and is generated by this current. The magnetic flux will flow to the second thin film magnetic core 10 which is a magnetic body having a common magnetic flux. At this time, when the second thin film magnetic core 10 is an integral magnetic body as shown in FIG.
Although the magnetic flux flowing through 0 leaks to the MR magnetic sensitive section 4 side due to the shape step, in the present example, the second thin film magnetic core 10 is separated into the two magnetic bodies 11 and 12 by the nonmagnetic layer 13. Most of the magnetic flux flows into the magnetic layer 11 on the inductive head side and does not flow to the magnetic layer 12 on the MR head side. Therefore, the influence of the leakage magnetic field leaking to the MR magnetic sensing unit 4 as a kind of bias magnetic field is significantly reduced, and the instability of the reproduction output is improved.

An embodiment of the composite type magnetic head to which the present invention is applied has been described above, but the present invention is not limited to the above-mentioned embodiment and various modifications can be made. For example, in the above example, the bias conductor 5 and the head winding 16 are connected in parallel, and the bias conductor 5 and the head winding 1 are connected.
By switching the direct current and the alternating current to 6 sequentially,
Although recording / reproducing is performed, the same effect can be obtained by connecting the bias conductor 5 and the head winding 16 in series.

[0031]

As is apparent from the above description, according to the composite type magnetic head of the present invention, the common magnetic body of the inductive head and the MR head is separated into two magnetic layers via the non-magnetic layer. Therefore, most of the magnetic flux generated by the bias current flowing through the head winding can flow through the magnetic layer on the inductive head side, and the magnetic flux leaking to the MR magnetic sensing section can be reduced. Therefore, the reproduction output is stable, and highly reliable recording and reproduction becomes possible.

Further, in the composite magnetic head of the present invention, since the head winding of the inductive head and the bias conductor of the MR head are electrically connected, the terminals of these head winding and bias conductor are made common. It is possible,
The number of terminals of the entire head can be reduced. Therefore, according to the composite magnetic head of the present invention, the area for arranging these terminals is not required, the head itself can be downsized, and the hard disk drive will be further increased in capacity and size in the future. It is extremely effective when used as a recording / reproducing head for a device.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part of a composite magnetic head to which the present invention is applied.

FIG. 2 is a plan view of the composite magnetic head of FIG.

FIG. 3 is an enlarged cross-sectional view of a main part showing another example of the composite magnetic head to which the present invention is applied.

FIG. 4 is an enlarged sectional view of a main part of a conventional composite magnetic head.

FIG. 5 is a circuit diagram when a head winding and a bias conductor are electrically connected in parallel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... ABS surface 2 ... Slider 3a ... Front end electrode 3b ... Rear end electrode 4 ... MR magnetic sensing part 5 ... Bias conductor 9 ... 1st thin film magnetic core 10 ... ..Second thin film magnetic cores 11, 12 ... Magnetic layer 13 ... Nonmagnetic layer 14 ... Third thin film magnetic core 16 ... Head winding

Claims (1)

[Claims] 1. A magnetoresistive effect magnetic sensing section is arranged between a first thin film magnetic core and a second thin film magnetic core, and constitutes a reproducing magnetic gap facing a contact surface with a magnetic recording medium. The third thin film magnetic core forming a closed magnetic circuit by the magnetoresistive effect magnetic head and the second thin film magnetic core is the second thin film magnetic core.
Of the thin film magnetic core, and an induction type magnetic head forming a recording magnetic gap facing the contact surface with the magnetic recording medium between the front ends of these thin film magnetic cores are laminated on the same substrate. In the composite magnetic head, the head winding of the induction type magnetic head and the bias conductor of the magnetoresistive effect type magnetic head are electrically connected, and the second thin film magnetic core sandwiches the nonmagnetic layer for at least 2 A composite magnetic head characterized by being formed as a layer.