JP3627356B2 - Magnetoelectric conversion element, method for producing magnetoelectric conversion element, and magnetic sensor using magnetoelectric conversion element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetoelectric transducer and a magnetic sensor using the same.
[0002]
[Prior art]
A conventional magnetoelectric transducer and a magnetic sensor using the same will be described with reference to FIGS. FIG. 3 is a cross-sectional view of a conventional magnetoelectric conversion element 30, and FIG. 4 is a partial cross-sectional view of a magnetic sensor 40 using the magnetoelectric conversion element 30.
[0003]
As shown in FIG. 3, the conventional magnetoelectric conversion element 30 has a magnetoresistive effect film 1, and one main surface of the magnetoresistive effect film 1 is bonded to a soft magnetic substrate 5 by a resin layer 4. A plurality of short-circuit films 2, 2. . . 2 is formed, and the magnetoresistive film 1 and a plurality of short-circuit films 2, 2. . . The protective film 3 is formed on the upper surface of the substrate 2, and the soft magnetic plate 5 is bonded to the protective film 3 with the resin layer 4. An input electrode 7 a and an output electrode for extracting a change in resistance value at both ends of the magnetoresistive film 1. 7b are connected to each other.
[0004]
The magnetoresistive effect film 1 is formed by a thin film forming technique and has a very small strength because its thickness is 100 μm or less. In order to reinforce the thin magnetoresistive film 1, the magnetoresistive film 1 is bonded to the soft magnetic substrate 5 as described above. The soft magnetic substrate 5 having a thickness of 500 μm or more is used. Further, in order to concentrate the magnetic field on the magnetoresistive effect film 1, the magnetoresistive effect film 1 is sandwiched between two soft magnetic plates 5.
[0005]
As shown in FIG. 4, in the magnetic sensor 40, magnets 8a and 8b are attached to both main surfaces of the plate-like holding part 11 with an adhesive 14, respectively, and further on each outer main surface of the magnets 8a and 8b. Each of the magnetoelectric conversion elements 30 and 30 is attached with an adhesive 14, and the whole is accommodated in a case 15, and then a resin 17 is enclosed.
[0006]
Lead wires 13, 13, 13 and 13 are connected to the electrodes 7 a and 7 b of the two magnetoelectric conversion elements 30, respectively.
[0007]
The magnets 8a and 8b are made of an oxide-based ferrite material such as strontium ferrite, and it is necessary to increase the permeance coefficient in order to apply a sufficiently large bias magnetic field to the magnetoelectric conversion elements 30 and 30 and to prevent further demagnetization. In addition, a material having a large thickness is used.
[0008]
This magnetic sensor 40 is used, for example, for examining the corrosion state of the inner wall of a thin tube used in a heat exchanger of a nuclear power generation facility. Below, the usage method is demonstrated.
[0009]
First, the magnetic sensor 40 is inserted into the thin tube, and the resistance value of each magnetoelectric conversion element 30 is measured. From the measured value, the distance between each magnetoelectric conversion element 30 and the magnetic metal that is the object to be measured is calculated. If the inner wall of the thin tube is not corroded, the inner wall of the thin tube (made of a magnetic metal) itself becomes the object to be measured, and if the inner wall of the thin tube is corroded, the corroded material swells toward the center of the thin tube (Made of a magnetic metal) is the object to be measured.
[0010]
Thus, the distance between one magnetoelectric conversion element 30 measured from the resistance value of the magnetoelectric conversion element and the object to be measured located in the vicinity of the magnetoelectric conversion element 30, and the other magnetoelectric conversion element 30 By adding the distance between the object to be measured located in the vicinity of the magnetoelectric conversion element 30 and the distance between both of the magnetoelectric conversion elements 30 known in advance, the functioning portion in the capillary tube It is possible to calculate the inner diameter, that is, the inner diameter that functions to pass a liquid such as water in a heat exchanger or the like. That is, when the inner wall of the narrow tube is not corroded, the inner diameter of the functioning part in the narrow tube matches the inner diameter of the narrow tube, and the inner wall of the narrow tube corrodes and the corroded material swells toward the center of the narrow tube The inner diameter of the functioning part in the narrow tube is smaller than the inner diameter of the narrow tube. By calculating the inner diameter of the functioning portion of the thin tube, the thickness of the corroded material swelled toward the center of the thin tube can be recognized.
[0011]
In addition, the thin tube used for the heat exchanger etc. of a nuclear power generation facility will be replaced | exchanged for a new thing, when the corrosive substance of the inner wall becomes more than fixed thickness.
[0012]
[Problems to be solved by the invention]
However, the conventional magnetic sensor 40 has a configuration in which two magnets 8 a and 8 b made of an oxide-based ferrite material such as strontium ferrite are housed in the case 15 together with the magnetoelectric conversion element 30. There was a problem that was large. Therefore, a thin tube used for a heat exchanger of a nuclear reactor or the like cannot be used as an object to be detected.
[0013]
[Means for Solving the Problems]
The magnetoelectric conversion element according to claim 1 of the present invention is a magnetoelectric conversion element having two detection portions in which a plurality of short-circuit films are intermittently formed on a magnetoresistive effect film. Are arranged on the front surface and the back surface of a hard magnetic substrate made of rare earth magnets, respectively.
[0014]
According to a second aspect of the present invention, there is provided a method of manufacturing a magnetoelectric conversion element comprising: a hard magnetic body comprising a rare earth magnet and two detection portions formed by intermittently forming a plurality of short-circuit films on a magnetoresistive film. In a method for manufacturing a magnetoelectric transducer that is disposed on the front surface and the back surface of a substrate, after detecting portions are respectively disposed on the front and back surfaces of a hard magnetic substrate made of a rare earth magnet, a hard magnetic substrate made of a rare earth magnet is attached. Characterized by magnetism.
[0015]
A magnetic sensor according to a third aspect of the present invention is characterized in that the magnetoelectric conversion element according to the first aspect is accommodated in a case.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
A magnetoelectric conversion element of the present invention and a magnetic sensor using the same will be described with reference to FIGS. FIG. 1 is a cross-sectional view of the magnetoelectric transducer 20, and FIG. 2 is a partial cross-sectional view of the magnetic sensor 50. In addition, the same code | symbol is used about the same part as a conventional example, and the description is abbreviate | omitted.
[0017]
As shown in FIG. 1, the magnetoelectric conversion element 20 of the present invention has one main surface of the magnetoresistive film 1 bonded to one main surface of the hard magnetic substrate 6 and the soft magnetic substrate 5 by the resin layer 4. A plurality of short-circuit films 2, 2. . . 2 is formed, and the magnetoresistive film 1 and a plurality of short-circuit films 2, 2. . . 2, a protective film 3 is formed on the protective film 3, and a metal magnetic substrate 9 bonded to the protective film 3 with a resin layer 4 is bonded to the protective film 3 with the resin layer 4.
[0018]
Further, on the other main surface of the hard magnetic substrate 6, the metal magnetic substrate 9, the protective film 3, the plurality of short-circuit films 2, 2. . . 2, the magnetoresistive effect film 1 and the soft magnetic substrate 5 are bonded via the resin layer 4.
[0019]
Furthermore, insulating layers 10 and 10 are provided on the end surfaces of the metal magnetic substrates 9 and 9 and the magnetoresistive effect films 1 and 1, respectively, and input electrodes 7 a electrically connected to both ends of one magnetoresistive effect film 1, respectively. The input electrode 7c and the output electrode 7d are formed so that the output electrode 7b is electrically connected to both ends of the other magnetoresistive film 1, respectively.
[0020]
Since the metal magnetic plate 9 is a low coercive force magnetic material made of silicon steel plate, pure iron, soft iron or the like, there is an effect of concentrating the magnetic field when the hard magnetic material 6 is magnetized. Therefore, the output is larger when the magnetoresistive effect element is laminated via the metal magnetic body 9 than when the magnetoresistive effect element is laminated directly on the rare earth hard magnetic substrate. This is because the amount of change in magnetic flux density increases when the element is located at a set distance from the magnetized surface of the hard magnetic substrate.
[0021]
Since the metal magnetic substrate 9 and the hard magnetic substrate 6 have electrical conductivity, the insulating layers 10 and 10 are required on the respective end faces.
[0022]
Next, a method for manufacturing the magnetoelectric conversion element 20 will be described.
[0023]
First, a bulk made of InSb or the like is bonded to the soft magnetic substrate 5 with the resin layer 4, the bulk is polished, processed into a predetermined shape to form the magnetoresistive effect film 1, and the magnetoresistive effect film 1 The short-circuit film 2, 2 and 2. . . 2, the magnetoresistive effect film 1, the short-circuit film 2, 2. . . Two sets of the protective film 3 formed on the substrate 2 and the metal magnetic substrate 9 bonded to the protective film 3 with the resin layer 4 are prepared.
[0024]
Next, these are bonded to the front and back surfaces of the hard magnetic substrate 6 by the resin layer 4.
[0025]
Next, the insulating layers 10 and 10, the input electrodes 7a and 7c, and the output electrodes 7b and 7d are formed.
[0026]
Next, the magnetoelectric conversion element 20 is manufactured by magnetizing the hard magnetic substrate 6.
[0027]
The hard magnetic substrate 6 constituting the magnetoelectric conversion element 20 of the present invention is made of a rare earth magnet, such as samarium cobalt, and has a larger permeance coefficient than the oxide ferrite material and a maximum energy product. Therefore, even if the thickness is reduced, demagnetization is not caused and a sufficiently large bias magnetic field can be applied to the magnetoresistive film 1. Therefore, the thickness of the magnetoelectric conversion element 20 including the hard magnetic substrate 6 for applying the bias magnetic field can be reduced.
[0028]
A magnetic sensor 50 using the magnetoelectric transducer 20 of the present invention will be described with reference to a partial sectional view of FIG.
[0029]
As shown in the figure, the magnetic sensor 50 has a configuration in which the magnetoelectric conversion element 20 is placed on the holding portion 12 and is inserted into the center of the cylindrical case 16 together with the holding portion 12 and the resin 17 is enclosed. Have. Further, lead wires 13, 13, 13, and 13 are attached to the input electrode 7a, output electrode 7b, input electrode 7c, and output electrode 7d formed on the end face of the magnetoelectric conversion element 20, respectively.
[0030]
Since the magnetic sensor 50 uses the magnetoelectric transducer 20 having a small thickness, the outer diameter is small. Therefore, it can be used to measure the inner diameter of a thin tube used in, for example, a reactor heat exchanger, which could not be measured conventionally.
[0031]
As described above, the magnetoelectric conversion element 20 of the present invention has two sets of the hard magnetic substrate 6, the magnetoresistive effect film 1, the soft magnetic substrate 5, and the metal magnetic substrate 9. However, the magnetoresistive film 1 and the soft magnetic substrate 5 are not limited to two sets.
[0032]
For example, a plurality of soft magnetic substrates and a plurality of magnetoresistive films are bonded to one main surface of one hard magnetic substrate, and each magnetoresistive film is electrically connected by electrodes formed on the end surfaces. Similarly, if the same number of magnetoresistive films having the same shape are formed on the other main surface of the hard magnetic substrate, a magnetoelectric conversion element having a large resistance change can be formed without increasing the thickness. A part of the plurality of soft magnetic substrates may be replaced with a resin serving as an insulating layer.
[0033]
Furthermore, if a plurality of magnetoresistive films are formed electrically independent from each other, a magnetic sensor capable of extracting a plurality of electrical signals can be configured.
[0034]
In the method for manufacturing a magnetoelectric conversion element of the present invention, after the magnetoresistive film is bonded to the hard magnetic substrate for applying a bias magnetic field, the hard magnetic substrate is magnetized. For this reason, the bias magnetic field can be applied to the magnetoresistive film with high accuracy, so that variations in output voltage are reduced. In addition, since the hard magnetic substrate is made of a rare earth magnet, the hard magnetic substrate can be made thin, so that the thickness of the magnetoresistive film can be reduced without lowering the amount of change in the resistance value of the magnetoresistive effect film. In addition, it is easy to reduce the thickness and size.
[0035]
【The invention's effect】
Since the magnetoelectric conversion element of the present invention is configured by adhering a soft magnetic substrate on which a magnetoresistive film is formed to a hard magnetic substrate for applying a bias magnetic field, the thickness can be reduced. Furthermore, a magnetic sensor having a small outer diameter can be configured using the magnetoelectric transducer.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a magnetoelectric conversion element according to an embodiment of the present invention.
FIG. 2 is a partial cross-sectional view of a magnetic sensor according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view of a conventional magnetoelectric conversion element.
FIG. 4 is a partial cross-sectional view of a conventional magnetic sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Magnetoresistance effect film | membrane 2 Short circuit film 3 Protective film 4 Resin layer 5 Soft magnetic substrate 6 Hard magnetic substrate 7a, 7c Input electrode 7b, 7d Output electrode 8a, 8b Magnet 9 Metal magnetic substrate 10 Insulating layers 11, 12 Holding Part 13 Lead wire 14 Resin layer 15, 16 Case 17 Resin 20, 30 Magnetoelectric conversion element 40, 50 Magnetic sensor

Claims (3)

In the magnetoelectric conversion element having two sets of detection portions in which a plurality of short-circuit films are intermittently formed on the magnetoresistive film,
2. The magnetoelectric conversion element according to claim 1, wherein the two sets of detection portions are respectively arranged on the front and back surfaces of a hard magnetic substrate made of a rare earth magnet. Magnetoelectric conversion element manufacturing method in which two sets of detection portions formed by intermittently forming a plurality of short-circuit films on a magnetoresistive film are disposed on the front and back surfaces of a hard magnetic substrate made of a rare earth magnet, respectively. In
A method for manufacturing a magnetoelectric conversion element, comprising: detecting portions on a front surface and a back surface of a hard magnetic substrate made of a rare earth magnet; and then magnetizing the hard magnetic substrate made of a rare earth magnet. A magnetic sensor comprising the magnetoelectric conversion element according to claim 1 housed in a case.

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