JP3360171B2 - Magnetic impedance head module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a magnetic sensor,
In particular, it relates to a magnetic impedance sensor which is a high-sensitivity magnetic sensor.

[0002]

2. Description of the Related Art With the rapid development of information devices and measurement / control devices in recent years, there has been an increasing demand for small, low-cost, high-sensitivity, high-speed magnetic sensors. For example, due to the high density of magnetic printing and magnetic recording in card readers, automatic ticket gates for transportation, banknote inspection devices, etc., and the demand for non-contact reading, the magnetoresistance effect (MR) There is an increasing demand for a small magnetic detecting element that can detect a weak surface magnetic flux with high sensitivity instead of a sensor.

At present, typical magnetic detecting elements used include an inductive reproducing magnetic head, a magnetoresistive (MR) element, a flux gate sensor, and a Hall element. Recently, the magneto-impedance effect of amorphous wires (JP-A-6-176930, JP-A-7-181239,
JP-A-7-333305) and the magnetic impedance effect of a magnetic thin film (JP-A-8-75835, Journal of the Japan Society of Applied Magnetics)
vol. 20, 553 (1996)), and a high-sensitivity magnetic sensor has been proposed.

[0004] The inductive reproducing magnetic head has a problem that the magnetic head itself becomes large because coil winding is required. Further, even if it is attempted to reduce the size, there is a problem that the relative speed between the magnetic head and the medium is reduced and the detection sensitivity is significantly reduced. On the other hand, a magnetoresistance effect (MR) element using a ferromagnetic film has come to be used. The MR element detects the magnetic flux itself, not the temporal change of the magnetic flux, and thus, the miniaturization of the magnetic head has been promoted.

However, even in the current MR element, for example, an MR element using a spin valve element, the rate of change in electric resistance is as small as 6% or less at the maximum, and an external magnetic field required to obtain a resistance change of several% is 1.6. It is as large as kA / m or more. Therefore, the magnetoresistive sensitivity is a low sensitivity of 0.001% / (A / m) or less. Recently, a giant magnetoresistance effect (GMR) using an artificial lattice having a magnetoresistance change rate of several tens of percent has been found. However, an external magnetic field of several tens A / m is required to obtain a resistance change of several tens%.

The fluxgate sensor measures the magnetism by using the fact that the symmetric BH characteristic of a high magnetic permeability core such as permalloy is changed by an external magnetic field, and has a high resolution and a high directivity of ± 1 °. Have. However, there is a problem that a large magnetic core is required to increase detection sensitivity, it is difficult to reduce the size of the entire sensor, and power consumption is large.

In a magnetic field sensor using a Hall element, when a magnetic field is applied perpendicularly to a plane through which current flows, an electric field is generated in a direction perpendicular to both the current and the applied magnetic field, and an electromotive force is induced in the Hall element. This is a sensor that utilizes Hall elements are advantageous in terms of cost, but have low magnetic field detection sensitivity,
In addition, since it is composed of semiconductors such as Si and GaAs, the mobility of electrons or holes changes due to the scattering of thermal oscillations of the lattice in the semiconductor due to temperature changes. Have.

As described above, JP-A-6-176930, JP-A-7-181239, and JP-A-7-333305 propose a magneto-impedance element, and this magnetic impedance element can greatly improve the magnetic field sensitivity. It is planned. The basic principle of this magneto-impedance element is to detect, as a change due to an externally applied magnetic field, only a voltage with respect to a time change of a circumferential magnetic flux generated by applying a time-varying current to a magnetic wire.

FIG. 15 shows an example of the magneto-impedance element. In the magneto-impedance element 1 of FIG. 15, the magnetic wire 2 has a zero magnetostriction
An amorphous wire of about m (wire drawn and tension annealed after drawing) is used. FIG. 16 shows an applied magnetic field dependence of a change in impedance of a wire (for example, the magnetic wire 2 in FIG. 15). When a high-frequency current of about 10 MHz is applied to a small-sized wire with a length of about 1 mm, the voltage amplitude of the wire is about 0.1% / (A), which is 100 times or more that of the MR element.
/ M) with high sensitivity. FIG. 16 shows that by applying a bias magnetic field, the linearity of the applied magnetic field dependence of the impedance change is improved, and a negative feedback coil is wound around the amorphous wire, and a current proportional to the voltage across the amorphous wire is applied to the coil. By applying negative feedback, it is possible to provide a sensor having excellent linearity and invariant in magnetic field detection sensitivity with respect to a temperature change of the sensor section.

However, since this high-sensitivity magnetic impedance element is made of an amorphous wire having a diameter of about 30 μm, it is not suitable for fine processing, and it has been difficult to provide an ultra-small magnetic detection element. Also, both the bias coil and the negative feedback coil must be manufactured by winding a thin copper wire, and there is a limit to miniaturization, and
There was also a problem with productivity.

In order to detect the local magnetic field, the amorphous wire 4 must be used in the vertical direction or the horizontal direction (FIG. 18) as shown in FIG. A terminal portion, a winding portion of a bias coil (not shown) or a wound portion of a negative feedback coil (not shown) has a thickness, and a distance L to the DUT 3 is generated. Therefore, there is a problem in a method of using the card reader, an automatic ticket gate for transportation, a banknote inspection device, and the like that may come into contact with the DUT 3. 17 and 18
In the figure, 5 indicates a copper plate, 6 indicates solder, and 7 indicates a magnetic field sensitivity range.

By the way, in the magnetic detection sensor for bills used in the bill detecting device, for example, an MR element shown in FIG. 19 is used. In the bill magnetic detection sensor 8, FIG.
As shown in FIG. 0, bill detection is performed using two MR elements 9. The characteristics of the MR element 9 are as shown in FIG. 21, and the reference point is moved so that linearity is obtained by the magnetic field (bias magnetic field) of the magnet 10. Also, the magnet 10
Is also used to magnetize magnetic ink printed on banknotes.

In the structure of the bill magnetic detection sensor 8,
There is a distance between the bill (the DUT 3) and the MR element 9 for the thickness of the case 11 (about 250 μm), and the magnetic detection of the bill decreases. In addition, since the detection sensitivity of the MR element 9 is low, it is necessary to bring the bill and the magnetic detection sensor into close contact. On the other hand, the inventors have proposed a small-sized magnetic impedance element having a bias coil and a negative feedback coil in which a thin film coil is three-dimensionally wound around a thin film magnetic core in Japanese Patent Application No. 9-269084.

As shown in FIG. 22, the magnetic sensor using the magnetic impedance element has two thin film magnetic impedance elements 15 provided with a negative feedback coil 12 and a bias coil 13 wound around a magnetic core 14. It is roughly composed of an impedance head slider and a drive circuit 18 for driving the two thin-film magnetic impedance elements 15. The driving circuit 18 supplies the high-frequency current to the two thin-film magneto-impedance elements 15.
9, a detection circuit 20 for detecting signals from the two thin-film magneto-impedance elements 15, an amplification circuit 21 for differentially amplifying and outputting the current from the detection circuit 20, and an amplification circuit 21
And a negative feedback unit 22 (negative feedback resistor) interposed between the negative feedback coil 12 and the output unit for negatively feeding the output signal from the amplifier circuit 21 back to the negative feedback coil 12.

Then, the output of the oscillation circuit 19 is applied to the thin-film magnetic impedance element 15 at a high frequency, and the output of the thin-film magnetic impedance element 15 is detected by the detection circuit 20 (detection circuit 20).
The differential detection is performed by a peak hold circuit (not shown) provided in the circuit, and the signal is amplified by the amplifier circuit 21. FIG. 23 shows another type of magnetic sensor circuit using two thin-film magnetic impedance elements 15. As shown in FIG. 24, this magnetic sensor circuit exhibits output characteristics with sensitivity of 0.025 V / (A / m) and excellent linearity.

[0016]

SUMMARY OF THE INVENTION As a magnetic sensor,
It is a small, low-cost, high-sensitivity magnetic sensor with excellent output linearity and temperature characteristics with respect to the detected magnetic field, and
In order to detect a minute and minute magnetic field, it is necessary to make the distance to the DUT 3 as close as possible. Since the magnetic field sensitivity is low in the MR element 9 as a magnetic sensor, the measured object 3 needs to be brought closer. However, when the magnetic sensor is used as a current banknote detecting magnetic sensor, a distance corresponding to the thickness of the case 11 (about 250 μm) is generated. In addition, in the high-sensitivity magnetic sensor using the amorphous wire 4, since the distance to the DUT 3 is large, a fine magnetic field cannot be sufficiently detected, and there is a problem in productivity.

In Japanese Patent Application No. 9-269084, the present inventors wound a thin-film coil three-dimensionally around a thin-film magnetic core to provide a small-sized magnetic impedance element (thin-film MI element) having a bias coil and a negative feedback coil. is suggesting. However, as shown in FIGS. 25 and 26, in order to operate as a magnetic sensor, the thin-film magneto-impedance element 15A (thin-film MI element 15A) is mounted on a circuit board, and the thin-film MI element 15A is mounted.
The element 15A and a circuit (such as a drive circuit) are connected using gold wire bonding 23, and coated with resin 24.
Need to be applied. In the magnetic sensor shown in FIGS. 25 and 26, the distance between the thin-film magnetic element and the DUT 3 is large, and is not suitable for detecting a minute and minute magnetic field. Further, in the above-described conventional technology, it has been a fact that the contact with the DUT 3 cannot be performed smoothly, and accordingly, good measurement is hindered and reliability is reduced.

The present invention has been made in view of the above circumstances, and makes a smooth contact with an object to be measured by smoothly contacting the object to be measured.
Movement is ensured, and good magnetic field detection is achieved, and thus reliability
It is an object of the present invention to provide a magnetic impedance head module capable of improving the performance .

[0019]

According to the first aspect of the present invention,
A substrate made of a non-magnetic material, a thin-film magnetic core formed on the substrate, first and second electrodes provided at both longitudinal ends of the thin-film magnetic core, and an insulator provided on the thin-film magnetic core A magnetic impedance head module comprising a magnetic impedance sensor head slider provided with a thin film bias coil and a thin film negative feedback coil provided through a driving circuit having an oscillation circuit and a detection / amplification circuit; 10 μm or more over the entire surface of the head slider where the thin-film magnetic core is formed
Apply a coating of 00 μm or less,
Edge blend on the corners and sides of the surface
Wherein the surface portion is a contact surface with the object to be measured.

The thin-film magnetic core is made of NiFe, CoFe, Ni
FeP, FeNiP, FeCoP, FeNiCoP, CoB, NiCoB, FeNi
CoB, FeCoB, CoFe plating film, or CoZrNb, FeSi
It is formed of an amorphous sputtered film of B or CoSiB or a NiFe sputtered film. Glass, ceramics, and silicon are used as the material of the substrate. Silicon, epoxy, phenol, polyimide, Norbock resin, and ceramics are used as coating materials. According to a second aspect of the invention, in the configuration of claim 1, wherein, prior to
A through hole is formed in the substrate, and the through hole is
Terminals of the first electrode, the second electrode, and the thin film bias coil
And the terminal of the thin film negative feedback coil is connected to the thin film on the substrate.
Each terminal provided on the surface opposite to the surface on which the magnetic core is formed
It is characterized by connecting with .

According to a third aspect of the present invention, in the configuration of the first or second aspect, the thin-film magnetic core in the magneto-impedance sensor head slider is formed.
It is noted that the drive circuit is mounted on the surface
Sign.

According to a fourth aspect of the present invention, there is provided a driving circuit and a driving circuit according to any one of the first to third aspects.
Ball and magnetic impedance sensor head slider
They are connected and integrated by a grid array .

According to a fifth aspect of the present invention, in the configuration of the fourth aspect , the ball grid array is formed of solder balls.
Characterized in that that. The invention according to claim 6 is the invention according to claim 4.
In the described configuration, the ball grid array is Au balls
It is characterized by consisting of .

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetic impedance head module according to a first embodiment of the present invention will be described below with reference to FIGS. This magnetic impedance head module has a magnetic impedance including a substantially rectangular substrate 30 made of a nonmagnetic material such as glass, ceramics, or silicon, and a thin-film magnetic impedance element 15A (thin-film MI element 15A) mounted on the substrate 30. A sensor head slider (MI sensor head slider 31) and a drive circuit 18 (not shown) for driving the thin film MI element 15A
(See FIG. 23).

The drive circuit 18 includes an oscillation circuit 19 (see FIG. 23) for supplying a high-frequency current to the thin-film MI element 15A, and a detection circuit 20 for detecting a signal from the thin-film MI element 15A.
(See FIG. 23), an amplifier circuit 21 (see FIG. 23) that differentially amplifies and outputs the current from the detection circuit 20, and an output circuit of the amplifier circuit 21 and the negative feedback coil 12 interposed. A negative feedback section 22 (negative feedback resistor) (see FIG. 23) for negatively feedbacking an output signal from the amplifier circuit 21 to the negative feedback coil 12 is roughly configured.

The thin-film MI element 15A has a thin-film magnetic core 14 in the form of a rectangular thin plate. A thin film negative feedback coil 12 and a thin film bias coil 13 are wound around the thin film magnetic core 14 via an insulator (not shown). The thin film negative feedback coil 12 and the thin film bias coil 13 are wound alternately. Negative feedback coil terminals 32 are connected to both ends of the thin film negative feedback coil 12.

A bias coil terminal 33 is connected to both ends of the thin film bias coil 13. Thin film magnetic core 14
Constitutes a first electrode and a second electrode (symbols are omitted), and a thin film MI sensor terminal 34 is connected to both ends. A wide portion 3 is provided at the tip of the negative feedback coil terminal 32.
2a is formed. A wide portion 33a is formed at the tip of the bias coil terminal 33. At the tip of the thin-film MI sensor terminal 34, a wide portion 34a is formed.

The substrate 30 has wide portions 32a, 33a, 3
A through hole 30c is formed corresponding to 4a from the front surface portion 30a to the back surface portion 30b. On the back surface portion 30b of the substrate 30, connection pads 30d (terminals) for the drive circuit 18 and the like are provided respectively corresponding to the through holes 30c. The negative feedback coil terminal 32, the bias coil terminal 33, and the thin film MI sensor terminal 34 are connected to the connection pad 30 through each through hole 30c.
d.

A coating 24 (protective film) made of silicon, epoxy, phenol, polyimide, Norbox-based resin, or ceramics is applied to the surface portion 30a of the substrate 30 so as to cover the thin film MI element 15A. The thickness T of the coating 24 is set to 100 μm or less. The drive circuit 18 is provided on the back surface 30 b of the substrate 30.
Is installed. The thin-film magnetic core 14 is made of NiFe, CoFe,
NiFeP, FeNiP, FeCoP, FeNiCoP, CoB, NiCoB, FeN
iCoB, FeCoB, CoFe plating film, or CoZrNb, FeS
It is formed of an amorphous sputtered film of iB or CoSiB or a NiFe sputtered film.

The magneto-impedance head module of this embodiment is used for detecting an object to be measured 3 such as a bill or a magnetic card.
In which the thin film MI element 15A (thin film magnetic core 14) is formed [ie, the surface portion 2 of the coating 24]
4a] is described in paragraph “0035” and FIG.
As described above, the measurement object 3 is brought into contact . The corners and sides of the surface portion 24a of the coating 24 are edge-blended and have a curved shape (a shape having a roundness 35).

In the magneto-impedance head module configured as described above, the thin-film MI element 15A is formed by winding the thin-film negative feedback coil 12 and the thin-film bias coil 13 around the thin-film magnetic core 14.
A is a three-dimensionally wound thin film coil around the thin film magnetic core 14 as described above, and a small magnetic impedance element (see FIGS. 22 and 23) having the thin film bias coil 13 and the thin film negative feedback coil 12. Similarly, downsizing can be achieved, and the cost reduction of the apparatus can be achieved with the downsizing.

As described with reference to FIGS. 15 and 16, a thin-film MI element 15A, which is an example of the MI element,
The sensitivity characteristics are excellent, a large output can be obtained, and a fine magnetic field can be detected. FIG. 19 and FIG.
The conventional technology (the bank magnetic detection sensor 8) described using 0 has a problem in terms of sensitivity in detecting a fine magnetic field, but in the present embodiment, the sensitivity characteristics are excellent as described above. Since fine magnetic field detection can be performed, the problem caused by the conventional technology (the banknote magnetic detection sensor 8) of FIGS. 19 and 20 can be improved.

Also, since the surface portion 24a of the coating 24 is configured to be in contact with the object 3 to be measured,
The distance from the device under test 3 is shortened, so that the device under test 3 can be more easily detected, and the device can be made more compact. In the present embodiment, the thickness of the coating 24 covering the thin-film MI element 15A is set to 100 μm or less, and the distance between the thin-film MI element 15A and the DUT 3 is 10 μm.
0 μm or less, which makes it easy to detect the DUT 3. In other words, in the banknote magnetic detection sensor 8 shown in FIGS. 19 and 20, there is a distance corresponding to the thickness of the case 11 (about 250 μm) between the banknote (the DUT 3) and the MR element 9; Although there was a problem, in this embodiment,
As described above, since the distance between the thin-film MI element 15A and the DUT 3 is 100 μm or less, and good sensitivity is ensured, the distance between the DUT 3 and the prior art shown in FIGS. The sensitivity problem arising from the distance between can be improved.

In the present embodiment, the coating 2
The thickness of the coating 2 was set to 100 μm or less.
Since so as to contact the object to be measured 3 to 4 of the surface portion 24a, the bill diagram distance in the thickness (about 250 [mu] m) content of the case 11 is required between the (object to be measured 3) and MR element 9 The size of the apparatus can be reduced as compared with the prior art shown in FIGS.

The corners and sides of the surface 24a of the coating 24 are edge-blended and rounded, so that the surface 24a comes into smooth contact with the DUT 3 ( That is, the surface portion 24a
Smooth movement of the contact surface and are) the object to be measured 3 with the measured object is secured, it is possible to achieve good detection and thus improve the reliability. Further, since the thin-film bias coil 13 is wound around the thin-film magnetic core 14, the reference point (see FIG. 21) in the impedance change characteristic with respect to the applied voltage can be moved by the magnetic field generated by the thin-film bias coil 13. The magnet 10 required by the MR element 9 for moving the reference point is not required, and the adjustment of the movement of the reference point can be performed more easily than when the magnet 10 is used.

In the present embodiment, the drive circuit 18 is mounted on the surface of the MI sensor head slider 31 opposite to the side on which the thin film MI element 15A is mounted (the back surface 30a of the substrate 30). Wire bonding 2
3 (see FIGS. 25 and 26)
The configuration can be simplified as compared with the above.

In the present embodiment, the object 3 is brought into contact with the surface portion 24a of the coating 24, and the thin film MI
The detection of the device under test 3 is performed with the element 15A (MI sensor head slider 31) in the horizontal direction, because the detection capability can be improved as follows. That is, the DUT 3 such as a bill or a magnetic card
Exhibits a magnetic distribution as shown in FIG. Then, as shown in FIG. 11, when the thin film MI element 15A is used in the vertical direction with respect to the DUT 3 (magnetic field distribution), there is a range 40 of 100 μm or more where magnetism cannot be detected. Decrease. On the other hand, when the thin film MI element 15A is used in the horizontal direction as shown in FIG. 12, the range 40 in which magnetism cannot be detected is suppressed to 100 μm or less, and the range in which magnetism can be detected (magnetic detection range) is correspondingly reduced. Is expanded, and the detection capability is improved as described above.

A magnetic sensor was constructed using the MI sensor head slider 31 of the present embodiment in the circuit of FIG. 23, and its output was obtained. The good results shown in FIG. 24 were obtained. Further, when the magnetic detection of the banknote was performed using this embodiment, the magnetic field detection result of the banknote shown in FIG. 13 could be obtained. In this case, the distance between the banknote and the thin-film MI element 15A is 600 μm, but when the distance is close to 100 μm, it becomes as shown in FIG.
(0.6 mm), it was confirmed that the detection ability can be improved up to about 6 times as compared with the case of (0.6 mm).

In the first embodiment, the case where one thin-film MI element 15A is mounted on the substrate 30 is taken as an example. However, instead of this, as shown in FIGS.
The MI sensor head slider 31 may be manufactured by mounting the three thin-film MI elements 15A, and a magnetic impedance head module (second embodiment) may be configured using the MI sensor head slider 31.

In the second embodiment, two thin films MI
In-phase components due to the temperature characteristics of the element 15A can be eliminated, and stability can be improved. Further, since the sensitivity is good thin film MI elements 15A there are two, Ru Hakare further improvement in the sensitivity.

Next, a magnetic impedance head module according to a third embodiment of the present invention will be described with reference to FIG. In the third embodiment, the connection terminals of the MI sensor head slider 31 and the drive circuit 18 are connected to solder balls or
The magneto-impedance head module is configured by being connected by a ball grid array 41 composed of Au balls.

In the third embodiment, a ball grid array 41 is interposed between the MI sensor head slider 31 and the drive circuit 18 so that the connection terminals (connection pads 30d) of the MI sensor head slider 31 are connected to the drive circuit. 18 are connected, and the connection of the drive circuit 18 can be easily performed. Further, since the drive circuit 18 is disposed on the surface of the substrate 30 opposite to the side on which the thin film MI element 15A is provided (the back surface b of the substrate 30), the surface 24a of the coating 24 is attached to the DUT 3. It is possible to make contact .

Next, a fourth embodiment of the present invention will be described with reference to FIGS. In the fourth embodiment, two thin film MI elements 1
5A, a driving circuit 18 integrated with a semiconductor is disposed at the center of the substrate 30, and the driving circuit 18 and the MI sensor head slider 31 are connected by wire bonding 23 to form an integrated magnetic impedance head chip (magnetic impedance head). Module). In the fourth embodiment, since the drive circuit 18 and the MI sensor head slider 31 are arranged collectively,
Accordingly, the size of the magnetic impedance head chip (magnetic impedance head module) can be reduced.

[0044]

According to the present invention, the magnetic impedance head according to claim 1 is provided.
According to the invention according to the load module, since the surface of the magnetic impedance sensor head slider on which the thin-film magnetic core is formed is opposed to the measured object, a case is provided between the measured object and the measured object and the sensor. The magnetic field can be detected more favorably than in the prior art in which a distance corresponding to the thickness of the case occurs between the cases. Further, since the corners and sides of the surface of the magnetic impedance sensor head slider facing the object to be measured are edge-blended, smooth contact with the object to be measured is ensured, and smooth movement of the object is ensured. Detection, and thus the reliability can be improved.

According to the second aspect of the present invention, the magneto-impedance sensor head slider and the drive circuit can be connected through the through-hole, and both can be integrated, and the device can be downsized accordingly. Claim
According to the invention described in the third aspect , the magneto-impedance sensor head slider and the drive circuit are integrated, and the device is downsized. According to the invention described in any one of claims 4 to 6 , the connection between the magneto-impedance sensor head slider and the drive circuit can be easily performed, and the two can be integrated, so that the size can be reduced. .

[Brief description of the drawings]

FIG. 1 is a plan view showing a main part excluding a drive circuit and an insulator of a magneto-impedance element according to a first embodiment of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is a rear view of FIG. 1;

FIG. 4 is a plan view showing a main part of a magneto-impedance element according to a second embodiment of the present invention, excluding a driving circuit and an insulator.

FIG. 5 is a side view of FIG. 4;

FIG. 6 is a rear view of FIG. 4;

FIG. 7 is a front view schematically showing a third embodiment of the present invention.

FIG. 8 is a plan view schematically showing a third embodiment of the present invention.

FIG. 9 is a front view of FIG. 8;

FIG. 10 is a schematic diagram showing a magnetic field distribution of a device under test 3;

FIG. 11 is a schematic diagram illustrating an example in which a thin-film MI element is arranged in a vertical direction with respect to an object to be measured (magnetic field distribution).

FIG. 12 is a schematic diagram illustrating an example in which a thin-film MI element is arranged in a lateral direction with respect to an object to be measured (magnetic field distribution).

FIG. 13 shows the MI sensor head slider of FIG.
FIG. 7 is a diagram showing a magnetic field detection result of a bill by a magnetic sensor configured using the circuit of FIG.

FIG. 14 is a diagram for explaining that the detection ability is improved when the distance between the bill and the thin-film MI element is reduced.

FIG. 15 is a diagram schematically showing a conventional magnetic impedance element.

16 is a diagram showing the applied magnetic field dependence of the impedance change of the magnetic wire of FIG.

FIG. 17 is a diagram in which an amorphous wire is arranged in a vertical direction to detect a local magnetic field.

FIG. 18 is a diagram in which amorphous wires are arranged in a lateral direction to detect a local magnetic field.

FIG. 19 is a perspective view showing an example of a banknote magnetic detection sensor.

FIG. 20 is a circuit diagram showing a wiring state of FIG. 19;

FIG. 21 is a diagram showing characteristics of the MR element of FIG. 19;

FIG. 22 is a block diagram showing a magnetic sensor provided with two thin-film magnetic impedance elements.

FIG. 23 is a circuit diagram showing another magnetic sensor configured using two thin-film magnetic impedance elements.

24 is a diagram showing output characteristics of the magnetic sensor of FIG.

FIG. 25 is a plan view showing another magnetic sensor in which a thin-film MI element and a circuit are connected by using gold wire bonding.

FIG. 26 is a front view showing the magnetic sensor of FIG. 25.

[Explanation of symbols]

14 Thin-film magnetic core 15A Thin-film MI element 18 Drive circuit 24 Coating 24a Surface part (surface part on which thin-film magnetic core is formed in magnetic impedance sensor head slider) 30 Substrate 31 MI sensor head slider (magnetic impedance sensor head slider) 35 Roundness

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hideki Kato 173-1 Asana, Asaba-cho, Iwata-gun, Shizuoka Pref. −98012 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 33/02 G01R 33/032-33/09

Claims (6)

(57) [Claims] 1. A substrate made of a non-magnetic material, a thin-film magnetic core formed on the substrate, first and second electrodes provided at both longitudinal ends of the thin-film magnetic core, and the thin film A magnetic impedance head module comprising a magnetic impedance sensor head slider provided with a thin film bias coil and a thin film negative feedback coil provided on a magnetic core via an insulator, and a drive circuit having an oscillation circuit and a detection / amplification circuit. The entire surface of the magnetic impedance sensor head slider on which the thin film magnetic core is formed is 10 μm or more and 100 μm or more.
m or less, and apply the coating
Edge blending is applied to the corners and sides of the
A magnetic impedance head module , wherein the surface portion is a contact surface with an object to be measured. 2. A through-hole is formed in the substrate, and a first electrode, a second electrode, a terminal of a thin-film bias coil and a terminal of a thin-film negative feedback coil are formed through the through-hole by a thin-film magnetic core in the substrate. 2. The terminal of claim 1 , wherein the terminal is connected to a terminal provided on a surface opposite to the surface provided.
Magnetic impedance head module according to. 3. A opposite to the side formed with the thin film magnetic core in the magneto-impedance sensor head slider
Claims, characterized in that mounting the driving circuit on the surface of the side
The magneto-impedance head module according to claim 1 or 2 . Wherein the drive circuit and magnetic impedance sensor head slider is connected by a ball grid array, claims 1 to 3, characterized in that integrated
The magnetic impedance head module according to any one of the above. 5. The ball grid array from the solder ball
Magnetic impedance head module according to claim 4, characterized in that. 6. The ball grid array is composed of Au balls .
Magnetic impedance head module according to claim 4, wherein the that.