CN116783494A - Current sensor - Google Patents
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- CN116783494A CN116783494A CN202180092711.4A CN202180092711A CN116783494A CN 116783494 A CN116783494 A CN 116783494A CN 202180092711 A CN202180092711 A CN 202180092711A CN 116783494 A CN116783494 A CN 116783494A
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- 239000010410 layer Substances 0.000 claims abstract description 113
- 230000000694 effects Effects 0.000 claims abstract description 59
- 239000011241 protective layer Substances 0.000 claims abstract description 33
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- 239000002184 metal Substances 0.000 claims description 16
- 239000011347 resin Substances 0.000 claims description 7
- 229920005989 resin Polymers 0.000 claims description 7
- 239000011810 insulating material Substances 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 5
- 229920002577 polybenzoxazole Polymers 0.000 claims description 5
- 229910045601 alloy Inorganic materials 0.000 claims description 3
- 239000000956 alloy Substances 0.000 claims description 3
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 claims description 2
- 230000002040 relaxant effect Effects 0.000 abstract description 18
- 230000035882 stress Effects 0.000 description 86
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- 238000001514 detection method Methods 0.000 description 6
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- 229910052581 Si3N4 Inorganic materials 0.000 description 2
- 230000002238 attenuated effect Effects 0.000 description 2
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- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 2
- 229910000990 Ni alloy Inorganic materials 0.000 description 1
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- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
Abstract
A current sensor (1) has a magnetoresistance effect element (11), a feedback coil (12), a magnetic shield (13), and a protective layer (14) provided between the magnetoresistance effect element (11) and the magnetic shield (13). The feedback coil (12) is provided between the magnetoresistance effect element (11) and the protective layer (14), and the protective layer (14) has a stress relaxation layer (15) provided on the magnetic shield (13) side and an inorganic insulating layer (16) provided between the relaxation layer (15) and the feedback coil (12). Since the internal stress of the magnetic shield (13) is relaxed by the stress relaxing function of the stress relaxing layer (15) and the feedback coil (12) is protected by the inorganic insulating layer (16), the current sensor (1) of the present invention has stable characteristics by suppressing the influence of the stress of the magnetic shield (13) on the magnetic characteristics of the magnetic shield (13) and the magnetoresistance effect element (11).
Description
Technical Field
The present invention relates to a magnetic balance type current sensor using a magnetoresistance effect element.
Background
In the field of motor drive technology in electric vehicles and hybrid vehicles, or in the field of infrastructure such as a columnar transformer, a large current is handled, and therefore a current sensor capable of measuring a large current in a noncontact manner has been demanded. As such a current sensor, a current sensor using a magnetic sensor that detects an induced magnetic field (current magnetic field) from a measured current is known. Examples of the magnetic detection element for the magnetic sensor include a magnetoresistive effect element such as a GMR (Giant Magneto Resistive: giant magnetoresistance effect) element.
The magnetoresistance effect element has the following characteristics: although the detection sensitivity is high, the linearity is high and the detectable magnetic field strength range is narrow. Therefore, as in the current sensor shown in fig. 6 of patent document 1, there is a case where a method is used in which the strength of an induced magnetic field substantially applied to a magnetoresistive element is reduced by disposing a magnetic shield between a measured current and the magnetoresistive element so that the magnitude of the measured magnetic field is within a magnetic field strength range having good detection characteristics. In this way, by reducing the strength of the magnetic field substantially applied to the magnetoresistance effect element using the magnetic shield, the expansion of the measurement range of the magnetic field strength is achieved.
Prior art literature
Patent literature
Patent document 1: international publication No. 2017/064921
Disclosure of Invention
Problems to be solved by the invention
Patent document 1 discloses a magnetic balance type current sensor in which an insulating layer is formed between a feedback coil and a magnetic shield. However, in the current sensor described in this document, since the insulating layer is formed of si—nx, stress generated in the magnetic shield during a manufacturing process such as a cooling process after a heating process cannot be sufficiently relaxed. The influence of the stress may affect the magnetic shield and the magnetoresistance effect element, and the characteristics of the current sensor may be changed. As the size of the magnetic shield increases, the stress generated also increases, which has a problem that the influence on the characteristics of the current sensor increases.
The purpose of the present invention is to provide a current sensor that suppresses the influence of the stress of a magnetic shield on the magnetic characteristics of the magnetic shield and the magneto-resistance effect element, and that has stable characteristics.
Technical proposal for solving the problems
In order to solve the above-described problems, one embodiment of the current sensor according to the present invention includes a magnetoresistance element, a feedback coil, a magnetic shield, and a protective layer provided between the magnetoresistance element and the magnetic shield, wherein the feedback coil is provided between the magnetoresistance element and the protective layer, and the protective layer includes a stress relaxation layer provided on the magnetic shield side and an inorganic insulating layer provided between the stress relaxation layer and the feedback coil.
Since the stress of the magnetic shield can be relaxed by the stress relaxing layer having the protective layer, even when the magnetic shield is enlarged for measuring a large current, the current sensor can be made to suppress characteristic fluctuation due to the stress of the magnetic shield. In addition, the feedback coil can be protected by an inorganic insulating layer provided on the opposite side of the magnetic shield.
The stress relaxation layer may also be formed of a material having a young's modulus smaller than that of the magnetic shield. In this case, the young's modulus of the stress relaxation layer is preferably 1/10 or less of the young's modulus of the magnetic shield, and the young's modulus of the stress relaxation layer is preferably 3.5MPa or less. The stress relaxation layer is preferably formed of an insulating material.
According to these configurations, the stress of the magnetic shield can be effectively relaxed by the stress relaxing layer. In addition to the inorganic insulating layer, the stress relaxation layer is formed of an insulating material, so that the insulating property of the protective layer can be improved.
From the viewpoint of efficiently relaxing the stress caused by the magnetic shield, the stress relaxing layer is preferably formed of a resin, and as a preferable resin, polybenzoxazole is exemplified.
The protective layer includes, from the magnetic shield side, a metal layer adjoining the magnetic shield, the stress relaxation layer, the inorganic insulating layer, and the young's modulus of the metal layer may be smaller than the magnetic shield and larger than the stress relaxation layer.
The stress of the magnetic shield is relaxed by the stress relaxing layer, and the magnetic shield can be easily formed by providing the metal layer having a Young's modulus larger than that of the stress relaxing layer.
The magnetic shield is preferably formed of FeNi alloy.
Since the passive layer is formed on the surface of the magnetic shield of FeNi alloy, a passivation film for protecting the surface of the current sensor is not required, and thus the manufacturing can be easily performed.
Effects of the invention
According to the present invention, the stress of the magnetic shield can be relaxed and the feedback coil can be protected by the protective layer having the stress relaxing layer and the inorganic insulating layer. Accordingly, it is possible to provide a current sensor in which characteristic variation due to the influence of stress is suppressed.
Drawings
Fig. 1 is a cross-sectional view schematically showing the configuration of a current sensor according to a first embodiment of the present invention.
Fig. 2 is a plan view schematically showing the structure of the current sensor of the first embodiment.
Fig. 3 is an explanatory diagram schematically showing the structure of the current sensor of the first embodiment.
Fig. 4 is a cross-sectional view schematically showing a configuration of a modification of the current sensor according to the first embodiment.
Fig. 5 is a cross-sectional view schematically showing the configuration of a current sensor according to a second embodiment of the present invention.
Fig. 6 is a plan view schematically showing the structure of the current sensor of the second embodiment.
Fig. 7 is an explanatory diagram schematically showing the structure of the current sensor of the second embodiment.
Fig. 8 (a) is a schematic diagram showing the simulation result of the embodiment, and fig. 8 (b) is a schematic diagram schematically showing the displacement of the region Q in fig. 8 (a).
Fig. 9 (a) is a schematic diagram showing the simulation result of the comparative example, and fig. 9 (b) is a schematic diagram schematically showing the displacement of the region Q in fig. 9 (a).
Fig. 10 is a sectional view schematically showing the constitution of a current sensor whose magnetic shield surface is protected by a passivation film.
Detailed Description
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the respective drawings, the same members are given the same reference numerals, and the description thereof is omitted as appropriate.
(first embodiment)
Fig. 1, 2 and 3 are a cross-sectional view, a plan view and a perspective view schematically showing the structure of the current sensor according to the present embodiment. Fig. 1 shows a section of the line A-A of fig. 2 and 3.
As shown in these figures, the current sensor 1 of the present embodiment includes magnetoresistance effect elements 11a, 11b, 11c, and 11d, a feedback coil 12, and a magnetic shield 13, and as shown in fig. 1, a protective layer 14 is provided between the magnetoresistance effect element 11 and the magnetic shield 13. Hereinafter, the magneto-resistive effect elements 11a to 11d are appropriately referred to as magneto-resistive effect elements 11 without distinction.
As shown in fig. 2, the four magnetoresistance effect elements 11 of the current sensor 1 are giant magnetoresistance effect elements (GMR elements) each having a bent shape (a shape in which a plurality of elongated patterns extending in the X1-X2 direction are connected in a folded-back manner). The sensitivity axis direction P of each magnetoresistance element 11 is indicated by an arrow in fig. 2, and the sensitivity axis direction P (first direction) of the magnetoresistance elements 11a, 11d is set to face the Y1-Y2 direction Y2 side, and the sensitivity axis direction P of the magnetoresistance elements 11b, 11c is set to face the Y1-Y2 direction Y1 side.
The wiring 55 connected to the input terminal 55a is connected to one end of the magnetoresistance effect element 11a, the other end of the magnetoresistance effect element 11a is connected in series to one end of the magnetoresistance effect element 11b, and the other end of the magnetoresistance effect element 11b is connected to the ground terminal 56a via the wiring 56. The wiring 55 connected to the input terminal 55a is branched in the middle, and is also connected to one end of the magnetoresistance effect element 11c, the other end of the magnetoresistance effect element 11c is connected in series with one end of the magnetoresistance effect element 11d, and the other end of the magnetoresistance effect element 11d is connected to the ground terminal 56a via the wiring 56. The first midpoint potential measuring terminal 57a is connected between the other end of the magnetoresistance effect element 11a and one end of the magnetoresistance effect element 11b through the wiring 57, and the second midpoint potential measuring terminal 58a is connected between the other end of the magnetoresistance effect element 11c and one end of the magnetoresistance effect element 11d through the wiring 58.
The current I is measured in the current path 40 0 In the case of flowing in the X1 direction, the current I to be measured 0 The induced magnetic field, that is, the current magnetic field, acts to reduce the resistance value of the magnetoresistance effect elements 11a, 11d, and also acts to increase the resistance value of the magnetoresistance effect elements 11b, 11 c. Therefore, the detection voltage follows the measured current I 0 Become larger and larger.
In the feedback coil 12, the offset current edge and the measured current I 0 And flows in the opposite direction (X2 direction). By the canceling current, a canceling magnetic field in a direction of canceling the current magnetic field acts on the magnetoresistance effect element 11.
By increasing the canceling magnetic field, the detection voltage approaches zero, the canceling magnetic field and the current magnetic field acting on the magnetoresistance element 11 are balanced, and when the detection voltage is equal to or lower than a predetermined value, the current flowing through the feedback coil 12 is detected as the measured current I 0 Is measured by the above method.
In the current sensor 1, the current magnetic field is attenuated by the magnetic shield 13 provided between the current path 40 and the magnetoresistance effect element 11. This can expand the current I to be measured until the magnetoresistance element 11 is magnetically saturated 0 And the dynamic range of the current sensor 1 can be enlarged.
In the manufacturing process of the current sensor 1, after the magnetic shield 13 is formed, there is a heating step such as a firing step of the resin for encapsulation, and the heating step is also performed in the step of soldering the completed current sensor to the motherboard. During each heating process and the subsequent cooling process, stress is generated in the magnetic shield 13.
With the measured current I 0 The capability of attenuating the current magnetic field required for the magnetic shield 13 becomes high, and the magnetic shield 13 tends to be large in size, thereby increasing the thickness and the volume. As the magnetic shield 13 is enlarged, a stress (internal stress) generated inside the magnetic shield 13 also becomes large. Therefore, in the current sensor 1, the protective layer 14 is provided between the magnetoresistance effect element 11 and the magnetic shield 13 in order to alleviate stress of the magnetic shield 13.
The magnetoresistance element 11 is formed on a substrate 19, and covered with an insulating layer 18 made of an insulating material such as aluminum oxide or silicon nitride. Fig. 2 shows a case where a giant magnetoresistance effect element (GMR element) is used as the magnetoresistance effect element 11, but the present invention is not limited thereto. In addition to the giant magnetoresistance effect element (GMR element), an anisotropic magnetoresistance effect element (AMR element), a tunnel magnetoresistance effect element (TMR element), or the like can be used.
In the case of using GMR elements each having a Self-pinned structure as the magnetoresistance effect element 11, magnetization of the pinned layer can be performed by film formation in a magnetic field, and heat treatment in the magnetic field is not required after film formation. Therefore, GMR elements having different magnetization directions of the fixed layers can be arranged on the same substrate 19, and a full bridge circuit can be formed on one substrate 19.
The feedback coil 12 is a feedback coil for magnetic balance, and is provided between the magnetoresistance effect element 11 and the magnetic shield 13. Since the protective layer 14 is provided between the feedback coil 12 and the magnetic shield 13, the feedback coil 12 is provided between the magnetoresistance effect element 11 and the protective layer 14. In fig. 2, the outline of the feedback coil 12 for magnetic balance is shown by a thick dotted line. The wiring of the feedback coil 12 is configured to be wound in the X-Y plane of the area indicated by the dotted line. As shown in fig. 3, the feedback coil 12 is a spiral coil, and in fig. 1, a cross section of a plurality of feedback coil wirings wound around are shown side by side in the Y1-Y2 direction. In the present embodiment, the feedback coil 12 is shown in which two spiral coils are superimposed, but the feedback coil 12 may be formed of one spiral coil.
The feedback coil 12 is located between the magnetoresistance effect element 11 and the magnetic shield 13. Thus, the measured current I 0 Is applied to the magnetoresistance effect element 11 in a state of being attenuated by the magnetic shield 13. Therefore, the offset measurement current I can be generated with a small current 0 The current magnetic field of (2) can realize the power saving of the current sensor.
The feedback coil 12 is a plating layer formed of a nonmagnetic metal layer having low resistance. Examples of the nonmagnetic metal include gold and copper. Copper is preferred because of its low electrical resistance. In addition, by using copper, the feedback coil 12 can be formed by a Damascene (Damascene) process, and thus the feedback coil 12 can be formed to be thin. Therefore, the distance between the magnetoresistance effect element 11 and the magnetic shield 13 can be reduced, and for example, the distance between the magnetoresistance effect element 11 and the magnetic shield 13 can be made to be about 9 to 11 μm, about 6 to 7 μm, or even about 3 to 5 μm.
The magnetic shield 13 is formed of a soft magnetic material containing iron group elements such as Fe, co, ni, and the like. Since the passive state caused by the oxide film resistant to the corrosive action is formed on the surface of the magnetic shield 13, the magnetic shield 13 composed of an fe—ni alloy (iron-nickel alloy) is preferable from the standpoint that a layer for protection purposes is not required to be formed.
From the viewpoint of sufficiently attenuating the current magnetic field, the thickness D1 of the magnetic shield 13 is preferably 20 μm or more, more preferably 30 μm or more, and even more preferably 35 μm or more.
The protective layer 14 is composed of a stress relaxation layer 15 and an inorganic insulating layer 16, and has a stress relaxation function and an insulating function for relaxing stress generated by the magnetic shield 13. The "stress of the magnetic shield 13" refers to stress generated inside the magnetic shield 13 due to deformation of the magnetic shield 13 in the manufacturing process of the current sensor 1.
The stress relaxation layer 15 is provided on the magnetic shield 13 side of the protective layer 14. The stress relaxation layer 15 is formed of a material having a young's modulus smaller than that of the magnetic shield 13. Therefore, in the manufacturing process, the deformation of the stress relaxing layer 15 can suppress the characteristic change of the magnetic shield 13 due to the reverse magnetostriction effect caused by the internal stress and the thermal stress. In addition, the influence of the deformation of the magnetic shield 13 on the magnetoresistance effect element 11 can be suppressed.
From the viewpoint of effectively relaxing the stress of the magnetic shield 13, the young's modulus of the stress relaxing layer 15 is preferably 1/10 or less, more preferably 1/30 or less, and still more preferably 1/50 of the young's modulus of the magnetic shield 13.
From the same viewpoint, the Young's modulus of the stress relaxation layer 15 is preferably 3.5MPa or less, more preferably 3.0MPa or less, and still more preferably 2.5MPa or less. By using a material having a low young's modulus, the stress relaxation layer 15 is easily deformed, and thus stress caused by deformation of the magnetic shield 13 can be relaxed, and variation in magnetic characteristics of the magnetic shield 13 can be suppressed. Thus, the current sensor 1 having stable characteristics can be realized.
The stress relaxation layer 15 preferably has low water absorption and high moisture permeability. The water absorption rate of the stress relaxation layer 15 is preferably 1.0% or less, more preferably 0.7% or less, and still more preferably 0.5% or less. The moisture permeability of the stress relaxation layer 15 is preferably 100 (g/m 2 24 hours) or more, more preferably 200 (g/m) 2 24 hours) or more, more preferably 300 (g/m) 2 24 hours) or more.
The stress relaxation layer 15 is preferably formed of a resin such as polyimide or polybenzoxazole (hereinafter, also referred to as PBO as appropriate) as an insulating material. Polybenzoxazole is preferable in view of excellent stress relaxation function, low water absorption, high moisture permeability and small change in size (shape). Since polybenzoxazole has high hydrophobicity, expansion of the stress relaxation layer 15 due to water absorption can be suppressed, and the current sensor 1 having stable characteristics can be realized.
From the viewpoint of sufficiently exhibiting the stress relaxation function, the thickness D2 of the stress relaxation layer 15 is preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 4 μm or more. The upper limit of the thickness D2 is not particularly limited, and is, for example, 10 μm or less.
In order to cope with the case where the magnetic shield 13 becomes larger as the current to be measured increases, the current sensor 1 is provided with a stress relaxation layer 15. The stress due to the deformation of the magnetic shield 13 can be relaxed by the stress relaxing layer 15.
In addition, the current sensor 1 is provided with an inorganic insulating layer 16 that protects the feedback coil 12 between the stress relaxation layer 15 and the feedback coil 12. With this configuration, the stress of the magnetic shield 13 can be relaxed by the stress relaxing layer 15, and the occurrence of cracks in the inorganic insulating layer 16 can be suppressed.
From the standpoint of protecting the feedback coil 12 from moisture and air, silicon nitride is preferable as the material of the inorganic insulating layer 16. Further, by directly covering the feedback coil 12 with the protective layer 14 having a stress relaxing function, the thickness D3 of the inorganic insulating layer 16 can be made to be 0.2 μm or more, 0.5 μm or even 1.0 μm or more, and even when a sufficient protective function is provided, the occurrence of cracks can be suppressed.
From the viewpoint of protecting the feedback coil 12, the inorganic insulating layer 16 is preferably low in moisture permeability. The moisture permeability of the inorganic insulating layer 16 is preferably 0.4 (g/m 2 24 hours) or less, more preferably 0.1 (g/m) 2 24 hours) or less.
By suppressing the occurrence of cracks in the inorganic insulating layer 16, the feedback coil 12 can be protected by the inorganic insulating layer 16. For example, the feedback coil 12 made of copper having low resistance can be protected from moisture and air, and corrosion can be prevented.
The protective layer 14 is composed of two layers, namely, a stress relaxation layer 15 having a stress relaxation function and an inorganic insulating layer 16 having an insulating protective function, and functions thereof are different. This can realize both the function of relaxing the stress of the magnetic shield 13 and the function of protecting the feedback coil 12.
(modification)
Fig. 4 is a cross-sectional view schematically showing a configuration of a modification of the current sensor according to the present embodiment. The current sensor 2 shown in the figure differs from the current sensor 1 in that the protective layer 14 has a metal layer 25 in addition to the stress relaxation layer 15 and the inorganic insulating layer 16.
The current sensor 2 has a metal layer 25 adjacent to the magnetic shield 13, a stress relaxation layer 15, and an inorganic insulating layer 16 provided between the stress relaxation layer 15 and the feedback coil 12.
The Young's modulus of the metal layer 25 is smaller than that of the magnetic shield 13 and larger than that of the stress relaxation layer 15. Therefore, even when the stress relaxation layer 15 is formed of a resin such as PBO having a sufficiently small young's modulus, the deformation of the stress relaxation layer 15 can be suppressed by forming the magnetic shield 13 in the metal layer 25, and the magnetic shield 13 can be easily formed.
The metal layer 25 is preferably a metal having a young's modulus of 10 or more and 200 or less. Preferable metals for forming the metal layer 25 include gold, palladium, and the like.
Fig. 10 is a sectional view schematically showing the constitution of the current sensor 4 in which the magnetic shield is protected by the passivation film 46. The current sensor 4 shown in the figure is constituted by the magnetoresistance element 11, the feedback coil 12, the stress relaxation layer 45, and the magnetic shield 13, and is protected by the passivation film 46.
In the case where the passivation film 46 is formed on the large magnetic shield 13 and the stress relaxation layer 45 (on the Z1 side) as in the current sensor 4, if the stress relaxation layer 45 is formed to have softness and volume enough to relax the stress sufficiently, cracks are generated in the passivation film 46 due to deformation of the stress relaxation layer 45. In particular, cracks are likely to occur in the region Q crossing the magnetic shield 13 and the stress relaxation layer 45 indicated by R in fig. 10.
Therefore, in the current sensors 1 and 2 of the present embodiment, the stress relaxation layer 15 capable of sufficiently relaxing the stress is provided to relax the stress of the magnetic shield 13, and the inorganic insulating layer 16 is provided on the lower surface (the magnetoresistance effect element 11 side) of the stress relaxation layer 15 having small displacement (see fig. 1 and 4). With this configuration, it is possible to manufacture the current sensors 1 and 2 having stable characteristics with high yield while suppressing occurrence of cracks in the inorganic insulating layer 16.
(second embodiment)
Fig. 5, 6 and 7 are a cross-sectional view, a plan view and a perspective view schematically showing the structure of the current sensor 3 according to the present embodiment. Fig. 5 shows a section of the line A-A of fig. 6 and 7.
The current sensor 3 according to the present embodiment is different from the current sensors 1 and 2 according to the first embodiment in that a spiral-shaped (spiral-shaped) feedback coil 32 shown in fig. 7 is provided instead of the spiral-shaped (spiral-shaped) feedback coil 12 shown in fig. 3. As shown in fig. 6, the current sensor 3 can be miniaturized by the spiral-shaped feedback coil 32.
The feedback coil 32 is a feedback coil for magnetic balance, similar to the feedback coil 12. However, the feedback coil 32 surrounds the magnetoresistance effect element 11, and a part thereof is located between the feedback coil 32 and the magnetic shield 13. A protective layer 14 is provided between the portion of the feedback coil 32 between the feedback coil 32 and the magnetic shield 13. Therefore, the above-described portion in the feedback coil 12 is disposed between the magnetoresistance effect element 11 and the protective layer 14.
Examples
The results of the simulation of the current sensor according to the present invention will be described below, and the present invention will be described in more detail, but the scope of the present invention is not limited to these results and the like.
Example (example)
With the current sensor shown in fig. 1 having the following structure, the displacement and stress generated in the manufacturing process were simulated, and the maximum displacement of the upper and lower surfaces of the protective layer 14 made of PBO and the magnitude of the internal stress of the magnetic shield 13 were calculated. It should be noted that the numerals in "()" indicate thicknesses of the respective layers.
Insulating layer 18: siN (4 μm)/protective layer 14: PBO (4 μm)/magnetic shield 13: fe-Ni (35 μm)
Fig. 8 (a) is a schematic diagram showing the simulation result of the embodiment, and fig. 8 (b) is a schematic diagram schematically showing the displacement in the region Q of fig. 8 (a).
Comparative example
The current sensor having the following structure was subjected to the same simulation calculation as in the example, and the maximum displacement of the upper and lower surfaces of the insulating layer 18 made of SiN and the internal stress of the magnetic shield 13 were obtained by calculation. It should be noted that the numerals in "()" indicate thicknesses of the respective layers.
Insulating layer 18: siN (8 μm)/magnetic shield 13: fe-Ni (35 μm)
Fig. 9 (a) is a schematic diagram showing the simulation result of the comparative example, and fig. 9 (b) is a schematic diagram schematically showing the displacement in the region Q of fig. 9 (a).
TABLE 1]
As shown in table 1, by providing a protective layer having a stress relaxation function below the magnetic shield, the internal stress of the magnetic shield can be relaxed. In this way, it is known that the protective layer can suppress the influence of the internal stress on the magnetic properties of the magnetic shield and the magnetoresistance effect element. Therefore, it can be said that providing the protective layer is effective for increasing the thickness (volume) of the magnetic shield to cope with the increase in power.
As shown in fig. 8 (a), 8 (b), 9 (a), 9 (b) and table 1, the displacement of the magnetic shield can be alleviated by providing a protective layer having a stress alleviating function under the magnetic shield. Therefore, by forming the inorganic insulating layer 16 having a passivation function on the lower surface (surface on the magnetoresistance effect element 11 side) of the protective layer 14, occurrence of cracks in the inorganic insulating layer 16 can be prevented (see fig. 1).
Industrial applicability
The magnetic sensor having a magnetoresistance effect element according to an embodiment of the present invention is preferably used for a component of a current sensor of an infrastructure device such as a column transformer, a current sensor of an electric vehicle, a hybrid vehicle, or the like.
Description of the reference numerals
1. 2, 3, 4: current sensor
11. 11a to 11d: magneto-resistance effect element
12. 32: feedback coil
13: magnetic shield
14: protective layer
15. 45: stress relaxation layer
16: inorganic insulating layer
18: insulating layer
19: substrate board
25: metal layer
40: current path
46: passivation film
55: wiring
55a: input terminal
56: wiring
56a: grounding terminal
57. 58: wiring
57a: first midpoint potential measuring terminal
58a: second midpoint potential measuring terminal
D1, D2, D3: thickness of (L)
I 0 : measured current
P: sensitivity axis direction
Q, R: region(s)
Claims (9)
1. A current sensor is characterized in that,
has a magneto-resistive effect element, a feedback coil, a magnetic shield, a protective layer disposed between the magneto-resistive effect element and the magnetic shield,
the feedback coil is disposed between the magnetoresistance effect element and the protective layer,
the protective layer has a stress relaxation layer provided on the magnetic shield side and an inorganic insulating layer provided between the stress relaxation layer and the feedback coil.
2. The current sensor according to claim 1, wherein,
the stress relaxation layer is formed of a material having a Young's modulus smaller than that of the magnetic shield.
3. A current sensor according to claim 2, wherein,
the Young's modulus of the stress relaxation layer is 1/10 or less of the Young's modulus of the magnetic shield.
4. A current sensor according to claim 2, wherein,
the Young's modulus of the stress relaxation layer is 3.5MPa or less.
5. A current sensor according to claim 2, 3 or 4, characterized in that,
the stress relaxation layer is formed of an insulating material.
6. A current sensor according to claim 2, 3 or 4, characterized in that,
the stress relaxation layer is formed of a resin.
7. The current sensor according to claim 6, wherein,
the resin is polybenzoxazole.
8. The current sensor according to claim 1, wherein,
the protective layer includes a metal layer adjoining the magnetic shield, the stress relaxation layer, the inorganic insulating layer from the magnetic shield side,
the Young's modulus of the metal layer is smaller than the magnetic shield and larger than the stress relaxation layer.
9. The current sensor according to claim 1, wherein,
the magnetic shield is formed of an Fe-Ni alloy.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2021-019035 | 2021-02-09 | ||
| JP2021019035 | 2021-02-09 | ||
| PCT/JP2021/044788 WO2022172565A1 (en) | 2021-02-09 | 2021-12-06 | Electric current sensor |
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|---|---|
| CN116783494A true CN116783494A (en) | 2023-09-19 |
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| CN202180092711.4A Pending CN116783494A (en) | 2021-02-09 | 2021-12-06 | Current sensor |
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| JP (1) | JPWO2022172565A1 (en) |
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| US6429640B1 (en) * | 2000-08-21 | 2002-08-06 | The United States Of America As Represented By The Secretary Of The Air Force | GMR high current, wide dynamic range sensor |
| JP3971934B2 (en) * | 2001-03-07 | 2007-09-05 | ヤマハ株式会社 | Magnetic sensor and its manufacturing method |
| JP5723225B2 (en) * | 2011-06-03 | 2015-05-27 | パナソニック株式会社 | Bonding structure |
| JP6316960B2 (en) * | 2014-07-03 | 2018-04-25 | Ｊｘ金属株式会社 | UBM electrode structure for radiation detector, radiation detector and manufacturing method thereof |
| JP2016125901A (en) * | 2014-12-27 | 2016-07-11 | アルプス電気株式会社 | Magnetic field detector |
| CN108351373B (en) * | 2015-10-14 | 2020-08-14 | 阿尔卑斯阿尔派株式会社 | Current detecting device |
| JP2019105570A (en) * | 2017-12-13 | 2019-06-27 | アルプスアルパイン株式会社 | Magnetic sensor and current sensor |
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2021
- 2021-12-06 WO PCT/JP2021/044788 patent/WO2022172565A1/en active Application Filing
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| WO2022172565A1 (en) | 2022-08-18 |
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