JP7577142B2 - Current Sensors - Google Patents

Description

The present invention relates to a magnetic balance type current sensor using a magnetoresistive effect element.

In fields such as motor drive technology for electric vehicles and hybrid cars, and infrastructure-related fields such as columnar transformers, relatively large currents are handled, and current sensors capable of measuring large currents without contact are required. One such current sensor known is one that uses a magnetic sensor that detects the induced magnetic field (current magnetic field) from the current to be measured. Examples of magnetic detection elements for magnetic sensors include magnetoresistance effect elements such as GMR (giant magnetoresistance) elements.

Although the magnetoresistance effect element has a high detection sensitivity, it has the characteristic that it has high linearity and a relatively narrow range of magnetic field strength that can be detected. For this reason, a method may be used in which a magnetic shield is placed between the measured current and the magnetoresistance effect element, as in the current sensor shown in FIG. 6 of Patent Document 1, to reduce the strength of the induced magnetic field that is actually applied to the magnetoresistance effect element and to set the magnitude of the measured magnetic field within a magnetic field strength range that has good detection characteristics. By using a magnetic shield in this way, it is possible to reduce the strength of the magnetic field that is actually applied to the magnetoresistance effect element and expand the measurement range of the magnetic field strength.

International Publication No. 2017/064921

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, the current sensor described in the document has an insulating layer formed of Si-Nx, so that it is not possible to sufficiently alleviate the stress generated in the magnetic shield during the manufacturing process, such as the cooling process after the heating process. There is a risk that the influence of this stress will extend to the magnetic shield and the magnetoresistance effect element, causing the characteristics of the current sensor to fluctuate. There is a problem in that the stress generated by the magnetic shield increases with the size of the magnetic shield, which increases the influence on the characteristics of the current sensor.
An object of the present invention is to provide a current sensor having stable characteristics by suppressing the effect of stress from a magnetic shield on the magnetic characteristics of the magnetic shield and on a magnetoresistance effect element.

In one aspect, the current sensor of the present invention provided to solve the above problems comprises a magnetoresistive element, a feedback coil, a magnetic shield, and a protective layer provided between the magnetoresistive element and the magnetic shield, the feedback coil being provided between the magnetoresistive element and the protective layer, and the protective layer having a stress relief layer provided on the magnetic shield side, and an inorganic insulating layer being provided between the stress relief layer and the feedback coil.
The stress relaxation layer of the protective layer can relieve the stress of the magnetic shield, so that even if the magnetic shield is enlarged to measure a large current, the current sensor can suppress the characteristic fluctuation due to the stress of the magnetic shield. In addition, the feedback coil can be protected by the inorganic insulating layer provided on the opposite side of the magnetic shield.

The stress relaxation layer may be formed of a material having a smaller Young's modulus than the magnetic shield. In this case, it is preferable that the Young's modulus of the stress relaxation layer is 1/10 or less of the Young's modulus of the magnetic shield, and it is preferable that the Young's modulus of the stress relaxation layer is 3.5 MPa or less. It is preferable that the stress relaxation layer is formed of an insulating material.

These configurations allow the stress of the magnetic shield to be efficiently relieved by the stress relief layer. In addition, by forming the stress relief layer from an insulating material in addition to the inorganic insulating layer, the insulating properties of the protective layer can be improved.

From the viewpoint of efficiently alleviating the stress caused by the magnetic shield, it is preferable that the stress relaxation layer is formed from a resin, and a preferred resin is polybenzoxazole.

The protective layer may include, from the magnetic shield side, a metal layer adjacent to the magnetic shield, the stress relief layer, and the inorganic insulating layer, and the Young's modulus of the metal layer may be smaller than that of the magnetic shield and larger than that of the stress relief layer.
The stress of the magnetic shield is relieved by the stress relieving layer, and the magnetic shield can be easily formed by providing a metal layer having a larger Young's modulus than that of the stress relieving layer.

The magnetic shield is preferably made of an FeNi alloy.
The magnetic shield of the FeNi alloy can be easily manufactured because a passive layer is formed on the surface, eliminating the need to provide a passivation film for protecting the surface of the current sensor.

According to the present invention, the stress of the magnetic shield can be relieved and the feedback coil can be protected by a protective layer including a stress relief layer and an inorganic insulating layer. Therefore, a current sensor can be provided in which the characteristic fluctuation due to the influence of stress is suppressed.

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a current sensor according to a first embodiment of the present invention. FIG. 2 is a plan view illustrating a schematic structure of the current sensor according to the first embodiment; FIG. 1 is an explanatory diagram illustrating a structure of a current sensor according to a first embodiment; FIG. 11 is a cross-sectional view illustrating a schematic configuration of a modified example of the current sensor according to the first embodiment; FIG. 5 is a cross-sectional view illustrating a schematic configuration of a current sensor according to a second embodiment of the present invention. FIG. 13 is a plan view illustrating a structure of a current sensor according to a second embodiment; FIG. 13 is an explanatory diagram illustrating a structure of a current sensor according to a second embodiment; 8A is a schematic diagram showing a simulation result of an embodiment; FIG. 8B is a schematic diagram showing the displacement of region Q in FIG. 8A; 9A is a schematic diagram showing a simulation result of a comparative example, and FIG. 9B is a schematic diagram showing the displacement of an area Q in FIG. 9A. A cross-sectional view showing a schematic configuration of a current sensor in which the magnetic shield surface is protected by a passivation film.

An embodiment of the present invention will be described below with reference to the drawings. In each drawing, the same components are given the same numbers and descriptions will be omitted as appropriate.

(First embodiment)
1, 2 and 3 are a cross-sectional view, a plan view and a perspective view, respectively, showing the configuration of a current sensor according to this embodiment. Fig. 1 shows a cross section taken along line AA in Figs. 2 and 3.

As shown in these figures, the current sensor 1 of this embodiment comprises magnetoresistance effect elements 11a, 11b, 11c and 11d, a feedback coil 12 and a magnetic shield 13, and as shown in Figure 1, a protective layer 14 is provided between the magnetoresistance effect element 11 and the magnetic shield 13. Hereinafter, when there is no need to distinguish between the magnetoresistance effect elements 11a to 11d, they will be referred to as magnetoresistance effect element 11 as appropriate.

2, each of the four magnetoresistance effect elements 11 of the current sensor 1 comprises a giant magnetoresistance effect element (GMR element) having a meandering shape (a shape formed by connecting multiple long patterns extending in the X1-X2 direction in a folded manner). The sensitivity axis direction P of each magnetoresistance effect element 11 is represented by an arrow in FIG. 2, and the sensitivity axis direction P (first direction) of the magnetoresistance effect elements 11a and 11d is set to face the Y2 side in the Y1-Y2 direction, and the sensitivity axis direction P of the magnetoresistance effect elements 11b and 11c is set to face the Y1 side in the Y1-Y2 direction.

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 and one end of the magnetoresistance effect element 11b are connected in series, 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 branches off midway and is also connected to one end of the magnetoresistance effect element 11c, the other end of the magnetoresistance effect element 11c and one end of the magnetoresistance effect element 11d are connected in series, 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 measurement terminal 57a is connected between the other end of the magnetoresistance effect element 11a and one end of the magnetoresistance effect element 11b by the wiring 57, and the second midpoint potential measurement terminal 58a is connected between the other end of the magnetoresistance effect element 11c and one end of the magnetoresistance effect element 11d by the wiring 58.

When the measured current _I flows in the X1 direction in the current path 40, the current magnetic field, which is the induced magnetic field due to _I , acts to reduce the resistance values of the magnetoresistance effect elements 11a and 11d and to increase the resistance values of the magnetoresistance effect elements 11b and 11c. Therefore, the detection voltage increases as the measured current _I increases.

A canceling current flows in the feedback coil 12 in the opposite direction (X2 direction) to the current _I0 to be measured. The canceling current generates a canceling magnetic field in the magnetoresistance element 11 such that the canceling magnetic field from the current acts on the magnetoresistance element 11.

By increasing the canceling magnetic field, the detection voltage approaches zero, and the canceling magnetic field and the current magnetic field acting on the magnetoresistive element 11 reach a state of equilibrium. When the detection voltage falls below a predetermined value, the current flowing through the feedback coil 12 is detected as the measurement value of the measured current _I0 .

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 makes it possible to widen the range of change in the measured current _I0 until the magnetoresistance effect element 11 becomes magnetically saturated, thereby making it possible to widen the dynamic range of the current sensor 1.

In the manufacturing process of the current sensor 1, after the magnetic shield 13 is formed, there are heating processes such as a process of baking the resin for the package, and a further heating process is also performed in the process of soldering the completed current sensor to the mother board. Stress is generated in the magnetic shield 13 during each heating process and the subsequent cooling process.

As the measured current _I0 increases, the magnetic shield 13 is required to have a higher ability to attenuate the current magnetic field, and the magnetic shield 13 tends to become larger in size, thickness, and volume. As the magnetic shield 13 becomes larger, the stress (internal stress) generated inside the magnetic shield 13 also increases. Therefore, in the current sensor 1, a protective layer 14 is provided between the magnetoresistance effect element 11 and the magnetic shield 13 to relieve the stress of the magnetic shield 13.

The magnetoresistance effect element 11 is formed on a substrate 19 and is covered with an insulating layer 18 made of an insulating material such as alumina or silicon nitride. In FIG. 2, a giant magnetoresistance effect element (GMR element) is used as the magnetoresistance effect element 11, but this is not limited to this. In addition to the giant magnetoresistance effect element (GMR element), elements such as anisotropic magnetoresistance effect elements (AMR elements) and tunnel magnetoresistance effect elements (TMR elements) can be used.

When GMR elements in which each pinned layer has a self-pinned structure are used as the magnetoresistance effect element 11, the pinned layers can be magnetized by deposition in a magnetic field, and heat treatment in a magnetic field is not required after deposition. This makes it possible to arrange GMR elements with pinned layers having different magnetization directions on the same substrate 19, and to configure a full bridge circuit on a single 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 a 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 dashed line. The wiring of the feedback coil 12 is arranged so as to go around within the XY plane of the area shown by this dashed line. As shown in FIG. 3, the feedback coil 12 is a spiral coil, and in FIG. 1, the cross sections of the multiple feedback coil wirings that go around are shown lined up in the Y1-Y2 direction. In this embodiment, the feedback coil 12 in which two spiral coils are stacked is shown, but the feedback coil 12 may be made of one spiral coil.

The feedback coil 12 is located between the magnetoresistance effect element 11 and the magnetic shield 13. Therefore, the current magnetic field of the current _I0 to be measured is applied to the magnetoresistance effect element 11 in a state where it is attenuated by the magnetic shield 13. Therefore, a current magnetic field that cancels the current magnetic field of the current _I0 to be measured can be generated with a relatively small current, making it possible to reduce the power consumption of the current sensor.

The feedback coil 12 is a plated layer, and is formed of a low-resistance non-magnetic metal layer. Examples of non-magnetic metals 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 process, so that the feedback coil 12 can be made thin. This allows the distance between the magnetoresistance effect element 11 and the magnetic shield 13 to be reduced; for example, the distance between the magnetoresistance effect element 11 and the magnetic shield 13 can be set to about 9 to 11 μm, about 6 to 7 μm, or even about 3 to 5 μm.

The magnetic shield 13 is made of a soft magnetic material containing iron group elements such as Fe, Co, and Ni. A magnetic shield 13 made of an Fe-Ni alloy (iron-nickel alloy) is preferred because it does not require the formation of a protective layer, since the surface of the magnetic shield 13 is passively formed by an oxide film that resists corrosion.

In order to sufficiently attenuate the current magnetic field, the magnetic shield 13 preferably has a thickness D1 of 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 that relieves the stress caused by the magnetic shield 13. "Stress of the magnetic shield 13" refers to the stress that occurs inside the magnetic shield 13 due to deformation of the magnetic shield 13 during 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 with a smaller Young's modulus than the magnetic shield 13. Therefore, deformation of the stress relaxation layer 15 during the manufacturing process can be suppressed, which would cause the characteristics of the magnetic shield 13 to change due to the inverse magnetostriction effect caused by internal stress or thermal stress. In addition, the effect of deformation of the magnetic shield 13 on the magnetoresistance effect element 11 can also be suppressed.

From the viewpoint of efficiently alleviating the stress of the magnetic shield 13, the Young's modulus of the stress relaxation layer 15 is preferably 1/10 or less of the Young's modulus of the magnetic shield 13, more preferably 1/30 or less, and even more preferably 1/50.

From the same viewpoint, the Young's modulus of the stress relaxation layer 15 is preferably 3.5 MPa or less, more preferably 3.0 MPa or less, and even more preferably 2.5 MPa or less. By using a material with a low Young's modulus, the stress relaxation layer 15 becomes more easily deformed, and the stress due to the deformation of the magnetic shield 13 can be relieved, and the change in the magnetic properties of the magnetic shield 13 can be suppressed. Therefore, the current sensor 1 can have stable properties.

The stress relaxation layer 15 preferably has low water absorption and high moisture permeability. The water absorption of the stress relaxation layer 15 is preferably 1.0% or less, more preferably 0.7% or less, and even more preferably 0.5% or less. The moisture permeability of the stress relaxation layer 15 is preferably 100 (g/ ^m2 ·24 hours) or more, more preferably 200 (g/ ^m2 ·24 hours) or more, and even more preferably 300 (g/ ^m2 ·24 hours) or more.

The stress relaxation layer 15 is preferably formed of a resin that is an insulating material, such as polyimide or polybenzoxazole (hereinafter, also referred to as PBO, as appropriate). Polybenzoxazole is preferred because it has excellent stress relaxation function, low water absorption, high moisture permeability, and small dimensional (external shape) change. Since polybenzoxazole is highly hydrophobic, it is possible to suppress the expansion of the stress relaxation layer 15 due to water absorption, resulting in a current sensor 1 with stable characteristics.

From the viewpoint of ensuring sufficient 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, but is, for example, 10 μm or less.

In order to accommodate the increase in size of the magnetic shield 13 due to the increase in the current of the object to be measured, the current sensor 1 is provided with a stress relief layer 15. This stress relief layer 15 can relieve stress caused by deformation of the magnetic shield 13.

In addition, the current sensor 1 has an inorganic insulating layer 16 between the stress relaxation layer 15 and the feedback coil 12 to protect the feedback coil 12. With this configuration, the stress relaxation layer 15 can relieve the stress of the magnetic shield 13 and prevent cracks from occurring in the inorganic insulating layer 16.

From the viewpoint of protecting the feedback coil 12 from moisture and air, silicon nitride is a preferred material for the inorganic insulating layer 16. In addition, by directly covering the feedback coil 12 with a protective layer 14 having a stress relaxation function, the occurrence of cracks can be suppressed even when the thickness D3 of the inorganic insulating layer 16 is set to 0.2 μm or more, 0.5 μm or even 1.0 μm or more, thereby providing a sufficient protective function.

The inorganic insulating layer 16 preferably has low moisture permeability from the viewpoint of protecting the feedback coil 12. The moisture permeability of the inorganic insulating layer 16 is preferably 0.4 (g/ ^m2 ·24 hours) or less, and more preferably 0.1 (g/ ^m2 ·24 hours) or less.

By suppressing the occurrence of cracks in the inorganic insulating layer 16, the inorganic insulating layer 16 can protect the feedback coil 12. For example, the feedback coil 12, which is made of copper with low resistance, can be protected from moisture and air to prevent corrosion.

The protective layer 14 is composed of two layers, a stress relief layer 15 with a stress relief function and an inorganic insulating layer 16 with an insulating protection function, and has separate roles. This allows it to achieve both the stress relief function of relieving the stress of the magnetic shield 13 and the function of protecting the feedback coil 12.

(Modification)
4 is a cross-sectional view showing a schematic configuration of a modified example of the current sensor according to the present embodiment. The current sensor 2 shown in the figure is different from the current sensor 1 in that the protective layer 14 includes a metal layer 25 in addition to the stress relaxation layer 15 and the inorganic insulating layer 16.

The current sensor 2 comprises a metal layer 25 adjacent to the magnetic shield 13, a stress relief layer 15, and an inorganic insulating layer 16 provided between the stress relief 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 if the stress relaxation layer 15 is made of a resin such as PBO, which has a sufficiently small Young's modulus, by forming the magnetic shield 13 on the metal layer 25, deformation of the stress relaxation layer 15 can be suppressed 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. Preferred metals for forming the metal layer 25 include, for example, gold and palladium.

Figure 10 is a cross-sectional view showing a schematic configuration of a current sensor 4 in which the magnetic shield is protected by a passivation film 46. The current sensor 4 shown in the figure is composed of a magnetoresistance effect element 11, a feedback coil 12, a stress relaxation layer 45, and a magnetic shield 13, and these are protected by the passivation film 46.

When a passivation film 46 is formed on a large magnetic shield 13 and stress relaxation layer 45 (Z1 side) as in the current sensor 4, if the stress relaxation layer 45 is soft enough and has a volume large enough to sufficiently relax the stress, the deformation of the stress relaxation layer 45 will cause cracks in the passivation film 46. Cracks are particularly likely to occur in the region Q that straddles the magnetic shield 13 and the stress relaxation layer 45, indicated by R in Figure 10.

Therefore, in the current sensors 1 and 2 of this embodiment, a stress relaxation layer 15 capable of sufficient stress relaxation is provided to relax the stress of the magnetic shield 13, and an inorganic insulating layer 16 is provided on the lower surface (the magnetoresistance effect element 11 side) of the stress relaxation layer 15, which has a small displacement (see Figures 1 and 4). This configuration suppresses the occurrence of cracks in the inorganic insulating layer 16, and current sensors 1 and 2 with stable characteristics can be manufactured with a high yield.

Second Embodiment
5, 6 and 7 are a cross-sectional view, a plan view and a perspective view, respectively, that show the configuration of the current sensor 3 according to this embodiment. Fig. 5 shows a cross section taken along line AA in Figs. 6 and 7.

The current sensor 3 of this embodiment differs from the current sensors 1 and 2 of the first embodiment in that it has a solenoid (spiral) feedback coil 32 shown in Fig. 7 instead of the spiral (wound) feedback coil 12 shown in Fig. 3. As shown in Fig. 6, the solenoid feedback coil 32 allows the current sensor 3 to be made smaller.

The feedback coil 32, like the feedback coil 12, is a feedback coil for magnetic balance. However, it surrounds the magnetoresistance effect element 11, and a part of it is located between the feedback coil 32 and the magnetic shield 13. A protective layer 14 is provided between the magnetic shield 13 and the part of the feedback coil 32 that is located between the feedback coil 32 and the magnetic shield 13. For this reason, the above-mentioned part of the feedback coil 12 is provided between the magnetoresistance effect element 11 and the protective layer 14.

Below, the present invention will be explained in more detail by showing the results of a simulation performed on the current sensor of the present invention, but the scope of the present invention is not limited to these results.

(Example)
1 having the following configuration, a simulation calculation was performed on the displacement and stress occurring during the manufacturing process to calculate the maximum displacement on the upper and lower surfaces of protective layer 14 made of PBO and the magnitude of internal stress in magnetic shield 13. The numbers in parentheses indicate the thickness of each layer.
Insulating layer 18: SiN (4 μm) / Protective layer 14: PBO (4 μm) / Magnetic shield 13: Fe-Ni (35 μm)
FIG. 8A is a schematic diagram showing the simulation results of the example, and FIG. 8B is a schematic diagram showing the displacement in a region Q in FIG. 8A.

Comparative Example
The same simulation calculation as in the example was performed for a current sensor having the following configuration, 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 calculated. The numbers in parentheses indicate the thickness of each layer.
Insulating layer 18: SiN (8 μm)/magnetic shield 13: Fe—Ni (35 μm)
FIG. 9A is a schematic diagram showing the simulation results of a comparative example, and FIG. 9B is a schematic diagram showing the displacement in a region Q in FIG. 9A.

As shown in Table 1, by providing a protective layer with a stress relaxation function under the magnetic shield, it was possible to relieve the internal stress of the magnetic shield. In this way, it was found that the protective layer can suppress the effect of internal stress on the magnetic properties of the magnetic shield and the magnetoresistance effect element. Therefore, it can be said that providing a protective layer is effective in increasing the thickness (volume) of the magnetic shield to accommodate higher power.

In addition, as shown in Figures 8(a), 8(b), 9(a), 9(b) and Table 1, by providing a protective layer with a stress relaxation function under the magnetic shield, the displacement of the magnetic shield can be relaxed by the protective layer. Therefore, by forming an inorganic insulating layer 16 with a passivation function on the lower surface (surface on the magnetoresistance effect element 11 side) of the protective layer 14, it is possible to prevent cracks from occurring in the inorganic insulating layer 16 (see Figure 1).

A magnetic sensor equipped with a magnetoresistance effect element according to one embodiment of the present invention can be suitably used as a component of a current sensor in infrastructure equipment such as a columnar transformer, or as a current sensor in electric vehicles, hybrid cars, etc.

1, 2, 3, 4: current sensors 11, 11a to 11d: magnetoresistance effect elements 12, 32: feedback coil 13: magnetic shield 14: protective layers 15, 45: stress relaxation layer 16: inorganic insulating layer 18: insulating layer 19: substrate 25: metal layer 40: current path 46: passivation film 55: wiring 55a: input terminal 56: wiring 56a: ground terminal 57, 58: wiring 57a: first midpoint potential measurement terminal 58a: second midpoint potential measurement terminal D1, D2, D3: thickness I ₀ : current to be measured P: sensitivity axis direction Q, R: area

Claims (12)

The magnetic recording medium includes a magnetoresistive element, a feedback coil, a magnetic shield, and a protective layer provided between the magnetoresistive element and the magnetic shield,
the feedback coil is provided between the magnetoresistive element and the protective layer,
the protective layer includes a stress relief layer provided on the magnetic shield side, and an inorganic insulating layer provided between the stress relief layer and the feedback coil,
the feedback coil is partially embedded in the stress relief layer,
The current sensor is characterized in that the inorganic insulating layer is provided on a surface of the stress relaxation layer on which the magnetoresistance effect element is located, and directly covers the feedback coil. 2. The current sensor of claim 1, wherein the feedback coil has a multi-layer structure between the magnetic shield and the magnetoresistive element, and a portion of the feedback coil located closer to the magnetic shield is embedded in the stress relaxation layer, and a portion of the feedback coil located closer to the magnetoresistive element is embedded in an insulating layer harder than the stress relaxation layer. The current sensor according to claim 2 , wherein the magnetoresistive element is embedded in the insulating layer. The current sensor according to claim 1 , wherein the stress relaxation layer is provided between the magnetic shield and the inorganic insulating layer. The current sensor according to claim 1 , wherein the stress relaxation layer is made of a material having a smaller Young's modulus than the magnetic shield. The current sensor according to claim 5 , wherein the Young's modulus of the stress relaxation layer is equal to or less than 1/10 of the Young's modulus of the magnetic shield. The current sensor according to claim 5 , wherein the Young's modulus of the stress relaxation layer is 3.5 MPa or less. The current sensor according to claim 5 , wherein the stress relief layer is made of an insulating material. The current sensor according to claim 5 , wherein the stress relaxation layer is made of a resin. the protective layer includes, from the magnetic shield side, a metal layer adjacent to the magnetic shield, the stress relaxation layer, and the inorganic insulating layer,
3. The current sensor according to claim 1 , wherein the metal layer has a Young's modulus smaller than that of the magnetic shield and larger than that of the stress relaxation layer. The resin is polybenzoxazole.
The current sensor according to claim 9 . The magnetic shield is formed of an Fe-Ni alloy.
The current sensor according to claim 1 .

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