JP2000298811A - Magnetic head and magnetic reproducing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high sensitivity MI head that can efficiently detect a high frequency signal by connecting in direct at least signal input terminal and ground terminal of a high frequency amplifier comprising semiconductor pair chip for amplifying high frequency carrier to the detection electrode terminal and ground electrode terminal. SOLUTION: A high frequency oscillator to supply a high frequency carrier signal to an MI head is connected to the signal supply terminal 11 and ground terminal 17 provided on a substrate 35. A magnetism detector 12 is formed in such a manner that a detection conductor thin film 13 consisting of Cu is sandwiched between two layers of soft-magnetic material films 14. On the other hand, an output signal amplified with a pair chip 27 as a high frequency amplifier is then transmitted to an external output terminal 24. An input terminal 20 and a ground terminal 19 of the pair chip 27 are connected respectively in direct to the detection electrode terminal 15 and ground electrode terminal 16 provided at both end portions of the detection conductor thin film 13 formed in the length of 100 μm or less. Thereby, an inductance element in the connecting path between these terminals is remarkably reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head (hereinafter referred to as "MI head") utilizing a change in impedance of a detection conductor due to an applied magnetic field (hereinafter referred to as "magnetic impedance effect") and a high-density using the MI head. The present invention relates to a magnetic reproducing device.

[0002]

2. Description of the Related Art FIG. 6 is a technical report of the IEICE MR95-85.
FIG. 7 is a perspective view of a conventional MI head 61 utilizing a magnetic impedance effect, which is reported in FIG. 6A, the MI head 61 has a magnetic impedance in which a detection conductor thin film 42 made of a conductive metal thin film is sandwiched between a pair of soft magnetic cores 46 and 47 having a width substantially equal to a track width 43 of a magnetic recording medium 53. An effect detection unit (hereinafter, referred to as a magnetic detection unit) is provided. A pair of soft magnetic cores 46, 4
Reference numeral 7 denotes a laminated film in which permalloy films 44 and SiO2 films 45 are alternately laminated, as shown in FIG.

When reproducing a signal magnetization 54 recorded on a magnetic recording medium by a conventional MI head 61, a high frequency oscillator 48 transmits a UHF band high frequency carrier signal to a resistor 49.
The high-frequency current 50 is applied to the detection conductor thin film 42 via the. Then, terminals 5 connected to both ends of the detection conductor thin film 42
1 and a voltage change due to a magnetic impedance effect generated between the terminals 52. The directions of the axes of easy magnetization of the soft magnetic cores 46 and 47 are oriented in advance in the width direction of the recording track of the magnetic recording medium 53. When the signal magnetization 54 does not exist in the magnetic recording medium 53, the high-frequency current 50 and both terminals 51 of the detection conductor thin film 42 are connected between the terminals 51 and 52.
A voltage of the high frequency carrier signal equal to the product of the impedance between 52 is generated. Signal magnetization 5 in the magnetic recording medium 53
When 4 exists, the axes of easy magnetization of the soft magnetic cores 46 and 47 are deviated from the previously oriented directions by the signal magnetization 54. As a result, the applied signal magnetization 5
4, the impedance between the terminals 51 and 52 of the detection conductor thin film 42 changes.

The high-frequency carrier signal is AM-modulated by the signal magnetization 54 of the magnetic recording medium 53 and detected by the change in the impedance of the detection conductor thin film 42. The signal magnetization 54 of the magnetic recording medium 53 can be read by AM detection of this signal. The detection sensitivity of the signal magnetization 54 of the magnetic recording medium 53 by the magnetic impedance effect is much higher than the detection sensitivity by the magnetoresistance effect. The MI head using the magneto-impedance effect can obtain about ten times as much output as a giant MR head using magnetic bubbles which is currently under development.

FIG. 7 is a graph showing a change characteristic of a high-frequency carrier signal level with respect to a magnetic field applied to the above-described MI head 61. In FIG. 7, the characteristic curve 56 indicates that the frequency of the high-frequency carrier signal is 1 GHz and the above-described M
This is obtained by placing the I head 61 at the center of the Helmholtz coil and changing the intensity of the applied DC magnetic field.
As can be seen from FIG. 7, according to the characteristic curve 56, the high-frequency carrier signal level gradually changes near the applied magnetic field strength of zero. In order to modulate a high-frequency carrier signal with high sensitivity to a change in magnetic field strength and obtain a waveform of a high-frequency carrier signal with small distortion, a bias magnetic field 55 biasing the characteristic curve 56 so as to use a portion that changes linearly Setting is required. In the above-described MI head, the DC current for generating the bias magnetic field 55 is superimposed on the high-frequency carrier signal current. This DC current flows through the detection conductor thin film 42 to generate a DC magnetic field, which is used as a bias magnetic field.

[0006]

The rate of change of the impedance of the detection conductor due to the magnetic impedance effect is proportional to the product of the frequency of the high-frequency carrier signal applied to the detection conductor and the rate of change of the permeability of the soft magnetic core. In order to increase the rate of change in the impedance of the detection conductor, in the conventional MI head, a permalloy film 44 having a large change in magnetic permeability is used as a material for the soft magnetic cores 46 and 47 to prevent generation of eddy current due to high frequency. SiO as insulator to prevent
A laminated film in which two films 45 are alternately laminated is used. Further, the frequency of the high-frequency carrier signal is a high frequency of several hundred MHz or more.

However, as described below with reference to FIG. 8, the conventional MI head 61 has a problem that the magneto-impedance effect in the high-frequency region becomes extremely small. FIG. 8 is a graph in which the change in the total impedance of the detection conductor with respect to the frequency of the high-frequency carrier signal when a magnetic field is applied to the conventional MI head 61 and when the magnetic field is not applied is measured by an impedance meter. As shown in FIG. 8, in the conventional MI head,
The change in the total impedance of the detection conductor when the intensity of the applied magnetic field is zero is small in a high-frequency region of 100 MHz or more as shown by a curve 1. On the other hand, when the intensity of the applied magnetic field is 5 Oe, the change in the total impedance of the detection conductor increases almost linearly as the frequency of the high-frequency carrier signal increases, as indicated by a change curve 2. As a result, the magneto-impedance effect indicated by the arrow 3 in the figure rapidly decreases in a high frequency region of 200 MHz or more.

Since the operating characteristics of the high frequency carrier signal of such an MI head in the high frequency region have not been clearly analyzed, the MI head has not been put to practical use. Therefore,
In order to realize the MI head, it is necessary to analyze the operating characteristics in the high frequency region and find a new detection method for detecting a change in the impedance of the detection conductor due to the magnetic impedance effect with high sensitivity in the high frequency region.

An object of the present invention is to provide a highly sensitive MI head capable of efficiently detecting a change in impedance of a detection conductor due to a magnetic impedance effect in a high frequency range. Another object of the present invention is to provide a high-density magnetic reproducing apparatus using the MI head.

[0010]

According to the present invention, there is provided a magnetic head comprising:
A two-layered soft magnetic film formed on a substrate and detecting magnetization of a magnetic recording medium, and a detection conductor thin film formed on the substrate with a part interposed between the two soft magnetic films And a magnetic detection unit composed of Also, the ground electrode terminal formed on one side of the soft magnetic material on the substrate connected to one terminal of the detection conductor thin film and the ground electrode terminal connected to the other terminal of the detection conductor thin film on the substrate. A detection electrode terminal formed on the other side of the soft magnetic film via a dielectric film; Further, it has a signal supply terminal and a ground terminal formed on the substrate for inputting a high frequency carrier signal on which a direct current for generating a bias magnetic field is superimposed from an external power supply. The signal supply terminal and the detection electrode terminal, and the ground terminal and the ground electrode terminal are respectively connected by a conductor film. Further, at least a signal input terminal and a ground terminal of a high-frequency amplifier comprising a semiconductor bare chip for amplifying the high-frequency carrier signal are directly connected to the detection electrode terminal and the ground electrode terminal, respectively.

According to this magnetic head, since the detection conductor thin film and the high frequency amplifier are directly connected to the detection electrode terminal and the ground electrode terminal, respectively, the length of the detection conductor thin film is substantially increased by the connection lead wire. Can prevent an increase in the inductance component in a high frequency region. Therefore, it is possible to detect a change in impedance of the detection conductor thin film due to the magnetic impedance effect in the high frequency region without attenuating. As a result, an MI head having high sensitivity even in a high frequency region can be realized.

In the magnetic head having the above structure, a first ground film formed on the substrate, a dielectric film formed on the first ground film, a detection conductor thin film formed on the dielectric film, and a detection film It is desirable to have a first microstrip line constituted by electrode terminals. Thus, the input impedance of the high-frequency amplifier and the characteristic impedance of the detection conductor thin film can be matched, and loss due to impedance mismatch can be prevented.

The height of each of the detection electrode terminal and the ground electrode terminal from the surface of the substrate is larger than the height of a magnetic detection unit including the soft magnetic material, and an overcoat covering the magnetic detection unit. It is desirable that the coating material is smoothed to have the same height as the detection electrode terminal and the ground electrode terminal. Thereby, when mounting the high frequency amplifier consisting of a semiconductor bare chip to the magnetic head substrate,
No bending stress is applied to the silicon substrate on which the semiconductor bare chip is formed. Therefore, damage to the silicon substrate can be prevented.

According to another aspect of the present invention, there is provided a magnetic head having the above-mentioned structure, wherein a signal supply terminal and a ground terminal formed on a front surface of a substrate, and a second ground formed on the substrate and the back surface of the substrate, respectively. A second microstrip line composed of a film, a first ground film formed on the surface of the substrate, a dielectric film formed on the first ground film, and a detection film formed on the dielectric film It has a first microstrip line composed of a conductive thin film, and the first ground film and the second ground film are connected by a conductive film. According to the magnetic head having this configuration, the characteristic impedance of the transmission path connecting the terminals formed on the surface of the substrate and the characteristic impedance of the external transmission path can be matched. Therefore,
Loss due to impedance mismatch at connection to an external high-frequency oscillator or AM detector can be prevented.

In the magnetic head having this configuration, it is desirable that the first microstrip line and the second microstrip line have substantially the same characteristic impedance.

In the magnetic head having the above two configurations, it is preferable that the detection electrode terminal and the signal supply terminal are connected by a 50 ohm resistive thin film. Preferably, the length of the detection conductor thin film is 100 μm or less.

A magnetic reproducing apparatus according to the present invention comprises: a magnetic head according to the present invention; a magnetic recording medium holding means for reproducing a signal recorded by the magnetic head; and a magnetic recording medium having a predetermined position on the magnetic recording medium. And a positioning means for positioning the magnetic head. According to this magnetic reproducing apparatus, the signal magnetization recorded on the magnetic recording medium by the MI head can be detected with high sensitivity, so that a high-density magnetic recording and reproducing apparatus can be realized.

[0018]

FIG. 1 shows a preferred embodiment of the present invention.
This will be described with reference to FIG. First, before explaining an embodiment of the magnetic head of the present invention, a prototype MI head for analyzing the operating characteristics of the MI head at a high frequency will be described with reference to FIGS. This MI head is made of a soft magnetic material made of a FeTaN material having a width of 300 μm and a length of 3 mm, a gap of 0.3 μm made of SiO ₂ material, and a copper (Cu) material having a width of 400 μm, a length of 2 mm and a thickness of 1 μm.
Was prepared with the detection conductor thin film interposed therebetween. Instead of the signal magnetization from the magnetic recording medium, a DC magnetic field in the length direction was applied to the soft magnetic material of the prototype MI head by a Helmholtz coil as a source of an external magnetic field.

In this state, a high-frequency carrier signal was applied to the detection conductor thin film, and the total impedance including the detection conductor thin film of the prototype MI head was measured by an impedance meter having a detection lead wire connected to a terminal of the detection conductor thin film. The soft magnetic material of this MI head is completely saturated when the intensity of the applied magnetic field reaches 5 Oe. FIG.
FIG. 9 is a graph showing a change in the total impedance including the detection conductor thin film measured by an impedance meter while changing the frequency of the high-frequency carrier signal applied to the detection conductor thin film.

With an impedance meter, impedance can be measured separately for an inductance component and a resistance component. In FIG. 1, curves 4 and 5 respectively show the change in the inductance component with respect to the frequency of the high-frequency carrier signal for the real part and the imaginary part of the magnetic permeability when the intensity of the external magnetic field is zero and when the external magnetic field strength is 5 Oe. Curves 6 and 7 show the change in the resistance component.
In FIG. 1, curves 4 and 5 of the change of the inductance component of the total impedance including the detection conductor thin film of the prototype MI head with respect to the frequency of the high-frequency carrier signal are curves 1 and 2 of the change of the impedance of the conventional MI head shown in FIG. 2 shows similar characteristics. In the high-frequency region, since the inductance component of the detection conductor thin film and the connection lead wire that does not change due to the external magnetic field is large, the change in the inductance component that does not change due to the external magnetic field becomes dominant, and the inductance of the magnetic detection unit changes due to the external magnetic field. The components indicate that they are hidden.

On the other hand, the curve 6 of the change of the resistance component of the total impedance including the detection conductor thin film of the MI head shown in FIG.
From FIG. 7, it was found for the first time by this analysis that the resistance component changed significantly with respect to the external magnetic field. More specifically, the change curve 4 of the inductance component in FIG. 1 shows the difference between the inductance that changes due to the external magnetic field generated from the real part of the permeability of the soft magnetic material and the inductance that does not change due to the external magnetic field of the detection conductor thin film and the connection lead wire. It is sum. When an external magnetic field 5 Oe is applied, a change curve 5 is obtained. This is because the magnetic permeability of the soft magnetic body approaches the value of 1 in air due to magnetic saturation, so that an inductance component that does not change mainly due to the external magnetic field of the detection conductor thin film and the connection lead wire remains. Further, the change curve 6 of the resistance component shows the sum of the resistance component changed by the external magnetic field generated from the imaginary part of the magnetic permeability of the soft magnetic material and the resistance component not changed by the external magnetic field of the detection conductor thin film or the connection lead wire. ing. When an external magnetic field 5 Oe is applied, a change curve 7 is obtained. This is because the permeability of the imaginary part of the soft magnetic material becomes 1, and the resistance component of the detection conductor which does not change due to the external magnetic field is mainly.

FIG. 2 is a graph showing a change in inductance of the detection conductor thin film measured by changing the length of the detection conductor thin film having a thickness of 1 μm and a width of 10 μm. As shown in FIG. 3, for the first time, it has been found that the inductance of the detection conductor thin film greatly decreases when the length of the detection conductor thin film becomes 100 μm or less as shown by a curve 8. The magnetic head of the present invention has been invented based on the knowledge obtained by these analyses.
In other words, the inductance component of the detection conductor thin film and the connection lead wire that does not change due to the external magnetic field is greatly reduced,
It has been found that it is important to detect only a change in the impedance of the detection conductor thin film of the magnetic detection unit which changes in the high frequency region due to the external magnetic field.

A preferred embodiment of the magnetic head according to the present invention will be described below with reference to FIGS.

Embodiment 1 FIG. 3 is a perspective view showing a configuration of an MI head according to Embodiment 1 of the present invention. FIG. 4 (a)
4 is a plan view of an electrode forming surface of the MI head of FIG.
FIG. 4B is a cross-sectional view taken along line bb of FIG.
In FIGS. 4 and 5B, the high frequency oscillator 9 for supplying the MI head with a high frequency carrier signal on which a direct current for generating a bias magnetic field is superimposed includes a signal supply terminal 11 and a ground terminal provided on a substrate 35. 17. .

The magnetic detecting section 12 is formed such that a detecting conductive thin film 13 made of Cu is sandwiched between two soft magnetic thin films 14 and 14a made of FeTaN amorphous. At both ends of the detection conductor thin film 13, a detection electrode terminal 15 and a ground electrode terminal 16 are provided. The detection electrode terminal 15 is connected to the signal supply terminal 11 by the resistance film 10, and the ground electrode terminal 16 is connected to the ground terminal 17 by a conductor thin film 18 made of Cu.

The silicon microchip (hereinafter, referred to as a bare chip) 27 which is a high-frequency amplifier shown in FIGS. 3 and 4A is surrounded by a dotted line to clearly show each electrode terminal. The DC power supply 31 that supplies power to the bare chip 27 is connected to the ground terminal 17 and the power supply terminal 29. The bare chip power terminal 26 and the bare chip ground terminal 19 are directly connected to the power terminal 25 connected to the power supply terminal 29 by the conductor film 28 and the ground electrode terminal 16 connected to the ground terminal 17, respectively.

On the other hand, the output signal amplified by the bare chip 27 is transmitted from the output terminal 22 directly connected to the bare chip output terminal 30 to the external output terminal 24 via the conductor thin film 23. This output signal is input to the AM detector 32 connected to the external output terminal 24. Thus, M
When the signal magnetization from the magnetic recording medium is applied to the I head, the AM
The modulated signal is amplified by the bare chip 27,
The signal is transmitted to the external output terminal 24 as an output signal. This output signal is output from an AM detector 32 connected to the external output terminal 24.
As a result, a signal obtained by demodulating the signal magnetization from the magnetic recording medium is generated between the output terminal 33 and the ground terminal 34 of the AM detector 32.

The respective terminals 11, 17, 2 of the MI head
The wirings in the area 60 indicated by the two-dot chain line in the figure, which are connected to the high-frequency transmitter 9 and the AM detector 32 from 4, 29, respectively, are connected by a transmission line constituted by a microstrip line to handle a 1 GHz high-frequency signal. I have. Thereby, there is an advantage that the high-frequency oscillator 9 and the AM detector 32 can be provided at a location away from the MI head. The groove 35 is formed on the surface of the substrate 35 of the MI head that faces the magnetic recording medium so that the substrate 21 floats from the surface of the magnetic recording medium that rotates at high speed. Note that Fe
In order to sufficiently bring out the characteristics of the soft magnetic material of TaN, a nonmagnetic NiTiMg-based ceramic is used as the material of the substrate 35.

Next, Embodiment 1 will be described with reference to FIG.
Of the MI head will be described. In FIG. 4B, a first ground film 37 made of Cu is formed on a substrate 35 made of a NiTiMg-based ceramic by using a photolithography technique, and a dielectric film 38 made of alumina is formed thereon. With this configuration, a first microstrip line is formed by the detection conductor thin film 13, the first ground film 37, and the dielectric film 38. With this first microstrip line, impedance matching between the detection conductor thin film 13 and the input impedance of the semiconductor bare chip 27 as a high-frequency amplifier is performed with respect to a high-frequency carrier signal.

The width W of the detection conductor thin film 13 and the dielectric film 38
The value of the characteristic impedance of the first microstrip line is determined by the thickness h and the relative dielectric constant of the first microstrip line. Since the dielectric film 38 is formed of alumina having a relative dielectric constant of 10, if W / h is 1, the characteristic impedance of the first microstrip line is 50 ohms. Therefore, if the thickness h of the alumina dielectric film 38 is 10 μm, the width W of the detection conductor thin film 13 may be 10 μm. In an electric circuit in a high frequency region, a transmission line having a characteristic impedance of 50 ohms is generally used.
The impedance was unified at 0 ohms.

The width G of the conductor film 23 connecting the output terminal 22 and the external output terminal 24 is also 10 μm. This conductor film 2
3 is also formed on the first ground film 37 via the dielectric film 38 of alumina, similarly to the detection conductor thin film 13, and forms a microstrip line having a characteristic impedance of 50 ohms. In addition, the input terminal 2 of the bare chip
0, the ground terminal 19 of the bare chip, the output terminal 30 of the bare chip, and the power terminal 26 of the bare chip as Au, respectively.
Are formed on the substrate mounting surface of the bare chip 27. , Each terminal 19, 20, 2 of the bare chip 27
Reference numerals 6 and 30 are heated and bonded to the detection electrode terminal 15, the ground electrode terminal 16, the output terminal 22, and the power supply terminal 25 provided on the substrate 35 by the conductive Ag paste 39, respectively.

Usually, a high-frequency amplifier such as a transistor or an FET is configured by storing a bare chip obtained by cutting a microchip formed on a silicon wafer in a molding case. The input terminals, output terminals, power supply terminals, ground terminals, and the like of the bare chip are connected to the inside of the terminals of the mold case penetrating from the inside of the mold case to the outside by wire bonding of Au wires. Then, the external side of the molding case is inserted into the printed circuit board and connected.

As described above, in the high-frequency amplifier in which a very small bare chip is housed in the mold case, it is unavoidable that the overall size becomes large in the order of mm. That is, it is unavoidable that an inductance component in a high frequency region is increased by connecting the terminals of the mold case to the terminals of the bare chip by using the terminals of the mold case and the Au wires. However, the size of the bare chip is about 40 to 50 μm square, and it is a size that can be sufficiently mounted on a substrate which is a slider of the MI head even in consideration of a lead terminal portion provided on the bare chip.

The present invention focuses on this point. In particular, the input terminal 20 and the ground terminal 19 of the bare chip 27 are set to 100 μm.
The detection electrode terminals 15 and the ground electrode terminals 16 provided at both ends of the detection conductor thin film 13 having a length of not more than m are directly joined. Thereby, the inductance component in the connection path between these terminals which does not change due to the external magnetic field can be significantly reduced. That is, by forming in this way, there is no lead wire, and almost no inductance component is generated in the connection path between the magnetic detection unit 12 and the bare chip 27 which is a high-frequency amplifier.
Therefore, the inductance component mainly depends on the magnetic detection unit 1.
2 is determined by the length of the detection conductor thin film 13.

Further, the surface of the alumina film 36 as an overcoat formed so as to cover the MI element 12 before the bonding of the bare chip 27 is higher than the height K of the magnetic detecting section 12, and the surface of the detecting electrode terminal 15 is It is important to perform smooth polishing so that the height from the surface 35 is the same height H. If this smoothing step is omitted, the rate at which the silicon substrate of the bare chip 27 is damaged is increased.

In the MI head according to the first embodiment, if a number of MI heads are arranged on the substrate 35,
Before cutting the I-head as individual chips,
5 can be inspected in a state where many MI heads are arranged. That is, a substrate 35 on which a number of MI heads are arranged is arranged in a Helmholtz coil, and a probe of a network analyzer is connected to each detection electrode terminal 15 and ground electrode terminal 16. In this state, the quality of the MI head can be determined by applying a DC magnetic field in a direction perpendicular to the plane of FIG. Since the impedance of the probe of the network analyzer is generally 50 ohms, the impedance can be matched in this state.

The bare chip 27, which is a high-frequency amplifier,
Input impedance and output impedance are both 5
A 0 ohm one was used. In impedance matching, it has been experimentally found that the characteristic impedance can be regarded as substantially the same if the range of the characteristic impedance is within ± 5% in practical use.

The width W of the detection conductor thin film 13 of the first prototype of the MI head of Example 1 was 10 μm, the thickness T was 1 μm, and the length L was 100 μm. FeT as the soft magnetic film 14
Using an aN film, the track width Tw was 10 μm, the thickness Tm of the soft magnetic film 14 was 1.5 μm, and the length Lm was 1 mm.
According to the MI prototype of the first prototype, as a result of measurement using a high-frequency carrier signal of 1 GHz, it was found that there was a 24% impedance change rate. Furthermore, if the length L of the detection conductor thin film 13 is reduced, the rate of change in impedance is greatly increased.

The width W of the detection conductor film of the second prototype of the MI head of Example 1 is 10 μm, the thickness T is 1 μm, the length L is 10 μm, the track width Tw is 0.5 μm, and the soft magnetic film 14 is formed. Has a thickness Tm of 1.5 μm and a length Lm of 1 mm. That is, the MI having such a narrow track width of 0.5 μm
In the head, the length L of the detection conductor thin film 13 is set to 10
μm. According to the MI head of the second prototype, when the FeTaN film is used as the soft magnetic film 14, 1
As a result of measurement using a high frequency carrier signal of GHz, the rate of change in impedance was 52%. Also, this second
As a result of trial production using a material whose frequency characteristic of magnetic permeability changes to a high frequency, such as an Fe-based material, as a material of the soft magnetic film of the prototype, it was found that the rate of change in impedance reached 94%.

At present, a spin bubble giant M using a magnetic bubble as a magnetoresistive element being developed.
It can be seen that the impedance change rate is extremely high as compared with the impedance change rate of the R head of about 5 to 7%. As described above, the detection conductor thin film 13 having the length L of 10 μm and 100 μm has been described as an example of the prototype of the MI head. However, when the detection conductor thin film has the length L of 100 μm or more, as shown in FIG. , The inductance component is greatly increased, making it difficult to detect a sufficient signal.

<< Embodiment 2 >> Hereinafter, M of Embodiment 2 of the present invention will be described.
The I head will be described with reference to FIG. FIG. 5A is a plan view illustrating the configuration of the MI head according to the second embodiment of the present invention), and FIG. 5B is a cross-sectional view taken along line BB of FIG. The MI head according to the second embodiment is the same as the MI head according to the first embodiment.
This is a structure in which the I head is further adapted to easily match a high frequency carrier signal. M of the first embodiment described above
In the I head, the impedance matching of the MI head is achieved by the first strip line. However, it is necessary to adopt a configuration in which the characteristic impedance of each electrode terminal and the external connection terminal can be easily matched with the high-frequency carrier signal.

The dimensions of the detection electrode terminal 15 and the output terminal 22 need to be large enough to mount a bonding metal such as solder to connect to the bare chip 27. For example, the size of the diameter of the Au hemisphere of each terminal of the bare chip 27 is about 80.
The detection electrode terminal 15 and the output terminal 22 need to have at least a larger area of about 100 μm square. Further, in order to stably handle a high-frequency carrier signal, a thin film having a large width is desirable as an electrode terminal. However, as already described for the MI head of the first embodiment, in order to make the characteristic impedance 50 ohms, the relative dielectric constant 1
For alumina of 0, W / h is 1, which is related to the thickness h of the dielectric film 38 made of alumina. That is, in order to make the width of the conductor film constituting each electrode terminal 100 μm, the thickness of the dielectric film 38 also needs to be 100 μm. However,
Forming such a thick alumina film by vapor deposition or sputtering is almost impossible in production. The magnetic head according to the second embodiment solves this problem.

When the substrate 35 is considered as a dielectric, N
Since the relative permittivity of the iTiMg material is about 5, if W / h is 1.8, its characteristic impedance is 50 ohms. That is, when the width of the conductive film constituting the electrode terminal is required to be 100 μm, the thickness of the substrate 35 as the dielectric is required to be 180 μm. 5A and 5B, in the MI head of Example 2, the width of each electrode terminal was set to 300 μm, and the thickness of the substrate 35 as a dielectric was finished to 540 μm by machining. . On the back surface of the substrate 35, a second ground conductor film 40 was formed. Although the alumina dielectric film 38 having a thickness of 10 μm is formed on the surface of the substrate 35, it is extremely thin compared to the thickness of the substrate 35 of 540 μm, and can be ignored for transmitting a high-frequency signal. Further, the conductive film 4 is used to bring the first ground film 37 and the second ground film 40 into a common ground state from the side surface of the substrate 35.
No. 1 was formed by sputtering sputtering and electrically connected.

As described above, the detection electrode terminal 15 and the substrate 35 having the terminal width G ′ of 300 μm and the second
A ground film 40, an output terminal 22 having a terminal width G ′ of 300 μm,
The conductor films 23 and 24, the substrate 35, the second ground film 40, the signal supply terminal 11 having a terminal width G ′ of 300 μm, and the substrate 35
The second microstrip line having a characteristic impedance of 50 ohms by the
A pair is formed. By forming in this way,
In the MI head according to the second embodiment, the characteristic impedance of the first macro strip line formed by the detection conductor thin film 13, the dielectric film 38 of alumina, and the first ground film 37 is 50 ohms. Further, the characteristic impedance of the three sets of second microstrip lines can also be formed as 50 ohms. As a result, good impedance matching can be achieved for the high-frequency carrier signal in all transmission paths.

The first and second embodiments described above are used.
In the MI head, the FeTaN film is used as the soft magnetic material, but other soft magnetic materials such as Co-based, Fe-based amorphous magnetic material, permalloy, and sendust may be used. Further, although an example in which NiTiMg is used as the material of the substrate has been described, other materials such as AlTiC, other ceramics, glass materials, and carbon substrates may be used. On the other hand, although Cu was used as the material of the detection conductor thin film and the conductor film, Ag,
A conductive material such as Au or Al may be used. Although alumina was used as the material of the dielectric film for the first microstrip line, Si, SiO ₂ , glass-based materials,
An inorganic dielectric such as carbon or other ceramic materials may be used. Needless to say, the magnetic recording / reproducing apparatus can be configured by combining the M1 head of the present invention described in each of the above embodiments with an electromagnetic writing (recording) head using a known coil.

[0046]

As apparent from the description of the embodiments, the present invention has the following effects. That is, according to the magnetic head of the present invention, the length of the detection conductor can be substantially shortened by directly connecting each terminal of the semiconductor bare chip, which is a high-frequency amplifier, to each electrode terminal of the MI head. Therefore, since the inductance component of the detection conductor can be significantly reduced, a change in the impedance of the detection conductor due to the magnetic impedance effect in a high frequency region can be detected with high sensitivity. As a result, a high-sensitivity MI head suitable for magnetic reproduction of a high-density recording medium can be realized. Further, by forming a microstrip line on the magnetic head substrate, a magnetic head whose impedance is matched to a high-frequency carrier signal can be realized. In addition, the magnetic reproducing apparatus of the present invention provides the high sensitivity MI
Since the head is mounted, a magnetic reproducing apparatus suitable for reproducing a magnetic recording medium of high density recording can be realized.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the frequency of a high-frequency carrier signal of an MI head and the inductance component and the resistance component of impedance in an analysis based on the present invention.

FIG. 2 is a graph showing a relationship between the length of a detection conductor and an inductance in an analysis on which the present invention is based.

FIG. 3 is a perspective view showing the configuration of the MI head according to the first embodiment of the present invention.

4A is a plan view of an electrode forming surface of the MI head according to the first embodiment of the present invention, and FIG. 4B is a cross-sectional view taken along line BB of FIG. 4A.

5A is a plan view of an electrode forming surface of an MI head according to a second embodiment of the present invention, and FIG. 5B is a cross-sectional view taken along line BB of FIG. 5A.

6A is a perspective view of a conventional MI head, and FIG. 6B is a partially enlarged view of FIG. 6A.

FIG. 7 is a graph showing a change of a high-frequency carrier signal with respect to an external magnetic field strength of a conventional MI head.

FIG. 8 is a graph showing the relationship between the frequency of a high-frequency carrier signal and impedance in a conventional MI head.

[Explanation of symbols]

 1 Impedance characteristics when external magnetic field is zero 2 Impedance characteristics when external magnetic field is 5 Oe 3 Arrow showing change due to external magnetic field 4 Characteristics of inductance component when external magnetic field is zero 5 Characteristics of inductance component when external magnetic field is 5 Oe 6 When external magnetic field is zero Characteristics of resistance component 7 Characteristics of resistance component when external magnetic field 5 Oe 8 Inductance characteristics of detection conductor 9 High-frequency oscillator 10 Resistive film 11 Signal supply terminal 12 Magnetic detection unit 13 Detection conductor thin film 14 Soft magnetic film 15 Detection electrode terminal 16 Ground Electrode terminal 17 Ground terminal 18, 23, 28, 41 Conductive film 19 Bare chip ground terminal 20 Bare chip input terminal 21 Groove 22 Output terminal 24 External output terminal 25 Power terminal 26 Bare chip power terminal 27 Bare chip 29 Power supply terminal 30 Bare chip Output terminal 31 DC power supply 3 2 AM detector 33 Detector output terminal 34 Detector ground terminal 35 Substrate 36 Alumina film connection wiring area 37 First ground film 38 Dielectric film 39 Silver paste 40 Second ground film 60 Connection wiring area

Claims (8)

[Claims] 1. A laminated two-layer soft magnetic film formed on a substrate and detecting the magnetization of a magnetic recording medium, formed on the substrate with a part interposed between the two soft magnetic films. A ground electrode terminal formed on the substrate on one side of the soft magnetic film connected to one end of the detection conductor thin film; a soft magnetic film connected to the other end of the detection conductor thin film A detection electrode terminal formed on the substrate on the other side of the body film via a dielectric film, and a high-frequency carrier signal on which a direct current for generating a bias magnetic field is superimposed from an external power supply is input on the substrate. A signal supply terminal and a ground terminal formed; a conductor film formed on a substrate to connect the signal supply terminal to the detection electrode terminal; and the ground terminal and the ground electrode terminal; and a semiconductor chip for amplifying a high-frequency carrier signal. And a high-frequency amplifier comprising a said detection electrode terminals and the grounding electrode terminals, a magnetic head is characterized in that at least the signal input terminal and the ground terminal of the semiconductor bare chip of the radio frequency amplifier are connected directly respectively. 2. A first ground film formed on the substrate,
And a first microstrip line comprising a dielectric film formed on the first ground film, and the detection conductor thin film and the detection electrode terminal formed on the dielectric film. Item 7. The magnetic head according to Item 1. 3. The height of the detection electrode terminal and the ground electrode terminal from the substrate surface is larger than the height of a magnetic detection unit including the soft magnetic film, and covers the magnetic detection unit. 3. The magnetic head according to claim 1, wherein the overcoat material is smoothed so as to have the same height as the detection electrode terminal and the ground electrode terminal. 4. A second microstrip line comprising the substrate and a second ground film formed on a back surface of the substrate, wherein the first ground film and the second ground film are connected to each other. 3. The magnetic head according to claim 2, wherein the magnetic head is connected by a conductor film. 5. The magnetic head according to claim 4, wherein characteristic impedances of the first microstrip line and the second microstrip line are substantially equal. 6. The magnetic head according to claim 1, wherein the detection electrode terminal and the signal supply terminal are connected by a 50 ohm resistive thin film. 7. The magnetic head according to claim 1, wherein the length of the detection conductor thin film is 100 μm or less. 8. A magnetic head according to claim 1, wherein: a magnetic recording medium holding means for reproducing a signal recorded by the magnetic head; and a magnetic head for moving the magnetic head to a predetermined position on the magnetic recording medium. A magnetic reproducing apparatus comprising positioning means for positioning a magnetic head.