Current sensor and current measuring device

Abstract

The invention provides a current sensor and a current measuring device. The current sensor may include at least one magnetoelectric conversion unit, a current conductor through which a measurement current flows, and a conductor plate at least partially overlapping the current conductor in plan view. The current conductor includes a main body portion that at least partially surrounds one of the at least one magnetoelectric conversion unit in plan view, the main body portion includes a first portion that surrounds at least three side surfaces of the one magnetoelectric conversion unit, and the thickness, permeability, and conductivity of the conductor plate are u, [mu] t, and [sigma] t, and the permeability and conductivity of the current conductor are [mu] b, [sigma] b. The shortest distance between the center of the magnetosensitive surface of the magnetoelectric conversion unit and the current conductor in plan view is h, the maximum width of the first portion in plan view is wb, and the shorter distance between the distance between the conductor plate and the current conductor and the distance between the conductor plate and the magnetosensitive surface in the thickness direction is zb. When wt is the narrowest width in the portion of the conductor plate that traverses the magnetoelectric conversion unit in plan view, each value satisfies a predetermined condition.

Description

Technical Field

[0001] The present invention relates to a current sensor and a current measuring device. Background Art

[0002] Patent Document 1 discloses a current sensor comprising a primary conductor, a lead frame, and a magnetic sensor. The primary conductor has an opening, and the lead frame and magnetic sensor have portions overlapping the opening. Patent Document 2 discloses a current sensor in which a support member supporting a magnetoelectric converter element is formed of a semiconductor substrate or a metal plate. Patent Document 3 discloses a current sensor in which an external current path is arranged on a substrate of a sensor package carrying a built-in sensor element, at a position opposite the sensor element. Patent Documents 4 and 5 disclose a magnetic sensor at least partially surrounded by a current conductor.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-36237

[0006] Patent Document 2: Japanese Patent No. 7328430

[0007] Patent Document 3: U.S. Patent No. 9,733,280

[0008] Patent Document 4: U.S. Patent Application Publication No. 2022 / 0091161

[0009] Patent Document 5: U.S. Patent Application Publication No. 2015 / 0160272 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] In a current sensor, it is desired to effectively suppress the influence of the skin effect generated in a current conductor through which a measurement current flows, from affecting the detection accuracy of the current sensor.

[0012] Means for solving problems

[0013] A current sensor according to one embodiment of the present invention may include: at least one magnetoelectric converter; a current conductor through which a measurement current measured by the at least one magnetoelectric converter flows; a signal processing unit that processes a signal output from the at least one magnetoelectric converter; a conductor plate that at least partially overlaps with the current conductor when viewed from above; and a sealing unit that seals at least the at least one magnetoelectric converter, the current conductor, and the signal processing unit. The current conductor may include a first main body portion that at least partially surrounds one of the at least one magnetoelectric converter when viewed from above, and the main body portion includes a first portion that surrounds at least three side surfaces of the one magnetoelectric converter. The thickness of the conductor plate may be set to u[m], and the magnetic permeability of the conductor plate may be set to μ t [N / A 2 ], the conductivity of the conductor plate is set to σ t [S / m], the magnetic permeability of the current conductor is set to μ b [N / A 2 ], let the conductivity of the current conductor be σ b [S / m], the shortest distance between the center of the magnetic sensitive surface of the at least one magnetoelectric converter and the surface of the current conductor when viewed from above is set to h [m], and the maximum width of the first portion when viewed from above is set to w b [m], the shorter distance between the conductor plate and the current conductor and the distance between the conductor plate and the magnetic sensitive surface of at least one magnetoelectric converter in the thickness direction is defined as z b [m], and the narrowest width of the portion of the conductor plate that crosses the at least one magnetoelectric converter when viewed from above is set to w t [m], satisfy

[0014] [Formula A]

[0015]

[0016] Here,

[0017] [Formula B]

[0018] (1) and In the case of

[0019]

[0020] [Formula C]

[0021] (2) and In the case of

[0022]

[0023] [Formula D]

[0024] (3) In cases other than (1) and (2),

[0025]

[0026] [Formula E]

[0027] In w t If the time is less than 4 hours,

[0028]

[0029] [Formula F]

[0030] In w t For ≥4h,

[0031] C w (w t )=1.

[0032] In the current sensor, the current conductor and the conductor plate may be non-magnetic bodies.

[0033] In any of the above current sensors, the current conductor and the conductor plate may be formed of a material containing 50% or more of copper.

[0034] In any of the current sensors, the conductivity σ of the conductor plate may be t [S / m] is 4.6×10 6 <σ t The thickness u[m] of the conductor plate and the shortest distance h[m] between the center of the magnetic sensitive surface of at least one magnetoelectric converter and the surface of the current conductor satisfy

[0035] [Formula G]

[0036]

[0037] and

[0038] [Formula H]

[0039]

[0040] and satisfy

[0041] [Formula 1]

[0042]

[0043] [Formula J]

[0044] In w t If <4h,

[0045]

[0046] [Formula K]

[0047] In w t For ≥4h,

[0048] C w (w t )=1.

[0049] In any of the above current sensors, the shortest distance h [m] between the center of the magnetic sensitive surface of the at least one magnetoelectric converter and the surface of the current conductor and the narrowest width w of the portion of the conductor plate that crosses the at least one magnetoelectric converter may be t [m] Satisfaction

[0050] 5×10 -5 m <h<5×10 -4 m、and

[0051] 2×10 -3 m <w t <2×10 -2 m,

[0052] and satisfy

[0053] [Formula L]

[0054]

[0055] In any of the above current sensors, the conductor plate may be embedded in the sealing portion without being exposed from a surface of the sealing portion.

[0056] In any of the above current sensors, the signal processing unit may be an IC chip, ie, a signal processing IC.

[0057] In any of the above current sensors, the magnetically sensitive surface may overlap with the signal processing IC in a plan view, and an electrical connection between the signal processing IC and the at least one magnetoelectric converter may not extend across the current conductor.

[0058] In any of the above current sensors, the at least one magnetoelectric conversion unit may include at least one magnetoelectric conversion element independent of the signal processing IC, and the magnetic sensitive surface of the at least one magnetoelectric conversion element may protrude from the circuit surface of the signal processing IC.

[0059] In any of the above current sensors, a surface of the signal processing IC opposite to the circuit surface may be arranged on a surface of the conductor plate facing the current conductor.

[0060] In any of the above current sensors, the at least one magnetoelectric converter may be built into the signal processing IC, and a magnetically sensitive surface of the magnetoelectric converter may not protrude from a circuit surface of the signal processing IC.

[0061] In any of the above current sensors, a surface of the signal processing IC opposite to the circuit surface may be arranged on a surface of the current conductor opposite to a surface facing the conductor plate via an insulating member.

[0062] In any of the above current sensors, the conductor plate may support the signal processing IC.

[0063] In any of the above current sensors, the current conductor may not have an interface between components connected to the signal processing IC.

[0064] In any of the above current sensors, the at least one magnetoelectric converter may be of a longitudinal magnetic field detection type.

[0065] In any of the above current sensors, the conductive plate may not include a hole or a slit that penetrates the conductive plate and at least partially overlaps with the magnetic sensitive surface in a plan view.

[0066] Any of the above current sensors may further include: a first terminal portion electrically connected to the current conductor and exposed from a first side surface of the sealing portion; and a second terminal portion exposed from a second side surface of the sealing portion opposite to the first side surface and outputting a signal output from the signal processing portion.

[0067] In any of the above current sensors, the current conductor may include a first terminal portion exposed from the sealing portion, and the first portion of the current conductor may be integrally formed with the first terminal portion.

[0068] In any of the above current sensors, at least a portion of the second terminal portion may be formed integrally with the conductor plate.

[0069] In any of the above current sensors, the conductor plate may not be sealed in the sealing portion and may be electrically insulated from the current conductor and the signal processing portion.

[0070] The current measuring device according to one aspect of the present invention may include a substrate and the current sensor mounted on the substrate. The conductive plate may be embedded in the sealing portion or the substrate without being exposed from the surface of the sealing portion or the surface of the substrate on which the current sensor is mounted.

[0071] The current measuring device according to one aspect of the present invention may include a substrate and the current sensor mounted on the substrate. The conductive plate may be arranged on the substrate on which the current sensor is mounted.

[0072] A current measuring device according to one embodiment of the present invention may include a substrate and the current sensor mounted on the substrate. A surface of the signal processing IC opposite to the circuit surface may be disposed on a surface of the current conductor that faces the conductor plate. The conductor plate may be disposed on the substrate on which the current sensor is mounted.

[0073] In the current measuring device, the conductor plate may be built into the substrate.

[0074] In any of the above current measuring devices, the conductor plate may be mounted on a surface layer of the substrate.

[0075] In any of the above current measuring devices, the conductor plate may be covered with an insulator.

[0076] In any of the above current measuring devices, the conductive plate may be arranged on a surface of the sealing portion on the circuit surface side of the signal processing IC.

[0077] A current sensor according to one embodiment of the present invention may include: at least one magnetoelectric converter; a current conductor through which a measurement current measured by the at least one magnetoelectric converter flows; a signal processing unit that processes a signal output from the at least one magnetoelectric converter; a conductor plate at least partially overlapping the current conductor when viewed from above; and a sealing unit that seals at least the at least one magnetoelectric converter, the current conductor, and the signal processing unit. The current conductor may be a non-magnetic body, including a main body that at least partially surrounds one of the at least one magnetoelectric converters when viewed from above, and the main body includes a first portion that surrounds at least three side surfaces of the one magnetoelectric converter. The thickness of the conductor plate may be u [m], the shortest distance between the center of the magnetic sensitive surface of the at least one magnetoelectric converter and the current conductor when viewed from above may be h [m], and the maximum width of the first portion when viewed from above may be w. b [m], the shorter distance between the conductor plate and the current conductor and the distance between the conductor plate and the magnetic sensitive surface of at least one magnetoelectric converter in the thickness direction is defined as z b [m], the narrowest width of the portion of the conductor plate that crosses the at least one magnetoelectric converter when viewed from above is defined as w t [m], and the conductivity of the conductor plate is set to σ t [S / m], if:

[0078] 5×10-5 m <h<5×10 -4 m;

[0079] 4×10 -4 m <w b <1×10 -2 m;

[0080] 2.55×10 ―4 m <z b <1.96×10 -2 m;

[0081] 2×10 -3 m <w t <2×10 -2 m;

[0082] 4.6×10 6 S / m<σ t ;

[0083] 2×10 -5 m <u<1×10 -3 m.

[0084] A current sensor according to one embodiment of the present invention may include: at least one magnetoelectric converter; a current conductor through which a measurement current measured by the at least one magnetoelectric converter flows; a signal processing unit that processes a signal output from the at least one magnetoelectric converter; a conductor plate at least partially overlapping the current conductor when viewed from above; and a sealing unit that seals at least the at least one magnetoelectric converter, the current conductor, and the signal processing unit. The current conductor may be made of a material containing more than 50% copper, including a main body that at least partially surrounds one of the at least one magnetoelectric converters when viewed from above, and the main body includes a first portion that surrounds at least three side surfaces of the one magnetoelectric converter. The shortest distance between the center of the magnetically sensitive surface of the at least one magnetoelectric converter and the current conductor when viewed from above may be set to h, and the maximum width of the first portion when viewed from above may be set to w. b The shorter distance in the thickness direction between the conductor plate and the current conductor and the distance between the conductor plate and the magnetic sensitive surface of at least one magnetoelectric converter is defined as z b In the case of

[0085] [Formula M]

[0086]

[0087] A current sensor according to one embodiment of the present invention may include: at least one magnetoelectric converter; a current conductor through which a measurement current measured by the at least one magnetoelectric converter flows; a signal processing unit that processes a signal output from the at least one magnetoelectric converter; a conductor plate at least partially overlapping with the current conductor when viewed from above; and a sealing unit that seals at least the at least one magnetoelectric converter, the current conductor, and the signal processing unit. The current conductor may include a main body that at least partially surrounds one magnetoelectric converter of the at least one magnetoelectric converter when viewed from above, and the main body includes a first portion that surrounds at least three side surfaces of the one magnetoelectric converter. The thickness of the conductor plate may be set to u[m], and the magnetic permeability of the conductor plate may be set to μ t [N / A 2 ], let the conductivity of the current conductor be σ b [S / m], the magnetic permeability of the current conductor is set to μ b [N / A 2 ], the conductivity of the conductor plate is set to σ t [S / m], the shortest distance between the center of the magnetic sensitive surface of at least one magnetoelectric converter and the current conductor when viewed from above is set to h [m], and the maximum width of the first portion when viewed from above is set to w b [m], the shorter distance between the conductor plate and the current conductor and the distance between the conductor plate and the magnetic sensitive surface of at least one magnetoelectric converter in the thickness direction is defined as z b [m], and the narrowest width of the portion of the conductor plate that crosses the at least one magnetoelectric converter when viewed from above is set to w t [m], satisfy

[0088] [Formula N]

[0089]

[0090] Here, satisfy

[0091] [Formula O]

[0092] (1) and In the case of

[0093]

[0094] [Formula P]

[0095] (2) and In the case of

[0096]

[0097] [Formula Q]

[0098] (3) In cases other than (1) and (2),

[0099]

[0100] [Formula R]

[0101] In w t If the time is less than 4 hours,

[0102]

[0103] [Formula S]

[0104] In w t For ≥4h,

[0105] C w (w t )=1.

[0106] It should be noted that the above summary of the invention does not list all the features of the present invention. In addition, sub-combinations of these feature groups can also constitute inventions. BRIEF DESCRIPTION OF THE DRAWINGS

[0107] Figure 1A 1 is a schematic plan view of the current sensor 10 according to the present embodiment when viewed from the top surface side (z-axis direction).

[0108] Figure 1B yes Figure 1A The current sensor 10 is shown in a cross-sectional view taken along line AA.

[0109] Figure 2 This is a diagram showing an example of frequency dependence showing the relationship between sensitivity fluctuation of a magnetoelectric conversion element and the frequency of a current flowing through a current conductor.

[0110] Figure 3 This is a diagram showing an example of the relationship between the sensitivity variation of a magnetoelectric conversion element whose three side surfaces are surrounded by current conductors and the distance between the current conductors and the conductive plate.

[0111] Figure 4 This is a diagram showing an example of the relationship between the sensitivity variation of one magnetoelectric transducer and the distance between the current conductor and the conductor plate when current detection is performed based on the difference between the outputs of two magnetoelectric transducers.

[0112] Figure 5 This is a diagram showing an example of a graph showing the relationship between sensitivity variation and frequency derived from equation (3).

[0113] Figure 6This is a diagram showing an example of simulation results in which the vertical axis represents sensitivity variation of a magnetoelectric transducer at a frequency of 10 MHz and the horizontal axis represents conductor width.

[0114] Figure 7 Graph showing the relationship between sensitivity variation of a magnetoelectric conversion element and the distance between a current conductor and a conductive plate.

[0115] Figure 8A The distance z is used when the magnetic sensitive surface of the magnetoelectric conversion element is located lower than the surface of the current conductor facing the signal processing IC. b Illustration for explanation.

[0116] Figure 8B The distance z is used when the magnetic sensitive surface of the magnetoelectric conversion element is located higher than the surface of the current conductor facing the signal processing IC 100. b Illustration for explanation.

[0117] Figure 9 The sensitivity variation of the magnetoelectric conversion element and the distance z are shown. b A diagram of the relationship.

[0118] Figure 10 This is a diagram for explaining the definition of parameters related to coils and conductors.

[0119] Figure 11 This is a graph showing the relationship between the sensitivity variation rate due to eddy current and the electrical conductivity of the conductor plate.

[0120] Figure 12 This is a diagram showing a graph illustrating the relationship between the normalized sensitivity variation rate and the width of the conductor plate according to the positional relationship in the thickness direction of the conductor plate, the current conductor, and the magnetoelectric conversion element.

[0121] Figure 13 The current sensor 10A of the modified example is equivalent to Figure 1A A cross-sectional view of the portion taken along line AA.

[0122] Figure 14 The current sensor 10B of the modified example is equivalent to Figure 1A A cross-sectional view of the portion taken along line AA.

[0123] Figure 15 The current sensor 10C of the modified example is equivalent to Figure 1A A cross-sectional view of the portion taken along line AA.

[0124] Figure 16 The current sensor 10D of the modified example is equivalent to Figure 1A A cross-sectional view of the portion taken along line AA.

[0125] Figure 17 The current sensor 10E of the modified example is equivalent to Figure 1A A cross-sectional view of the portion taken along line AA.

[0126] Figure 18 The current sensor 10F of the modified example is equivalent to Figure 1A A cross-sectional view of the portion taken along line AA.

[0127] Figure 19 The current sensor 10G of the modified example is equivalent to Figure 1A A cross-sectional view of the portion taken along line AA.

[0128] Figure 20 The current sensor 10H of the modified example is equivalent to Figure 1A A cross-sectional view of the portion taken along line AA.

[0129] Label Description

[0130] 10 Current sensor

[0131] 20a, 20b magnetoelectric conversion elements

[0132] 22a, 22b leads

[0133] 100 signal processing ICs

[0134] 108 lead wire

[0135] 130 sealing part

[0136] 140 current conductor

[0137] 141 Main body

[0138] 1411, 1412 slit portion

[0139] 142, 152 terminal parts

[0140] 150 lead frame

[0141] 151, 170 conductor plate

[0142] 160, 162 Insulating components

[0143] 170 conductor plate

[0144] 200 substrates

[0145] 201, 202 pads DETAILED DESCRIPTION

[0146] The present invention will be described below by way of embodiments of the invention, but the following embodiments do not limit the invention as defined in the claims. Furthermore, not all combinations of features described in the embodiments are necessarily essential to the solution provided by the invention.

[0147] Figure 1A and Figure 1B The internal structure of a semiconductor package that functions as the current sensor 10 according to this embodiment is shown. Figure 1A 1 is a schematic plan view of the current sensor 10 according to the present embodiment when viewed from the top surface side (z-axis direction). Figure 1B yes Figure 1A The current sensor 10 is shown in a cross-sectional view taken along line AA.

[0148] Regarding coordinates, Figure 1A In the paper, the x-axis is defined as the direction parallel to the paper and running from bottom to top, the y-axis is defined as the direction parallel to the paper and running from right to left, and the z-axis is defined as the direction perpendicular to the paper and running from the back to the front. Any of the x-axis, y-axis, and z-axis is orthogonal to the other axes.

[0149] The current sensor 10 includes a signal processing IC 100 , magnetoelectric conversion elements 20 a and 20 b , a current conductor 140 through which a measurement current flows, a lead frame 150 on the signal terminal side, and a sealing portion 130 .

[0150] The current conductor 140 includes a main body portion 141 and a terminal portion 142. The terminal portion 142 includes a pair of terminals 142a and 142b. The main body portion 141 is sealed in the sealing portion 130 and partially surrounds the magnetoelectric conversion elements 20a and 20b. The first portion 1410 of the main body portion 141 can surround at least three side surfaces of the magnetoelectric conversion element 20a when viewed from above. The magnetoelectric conversion element 20a can be surrounded by at least the inner side surfaces 1410a, 1410b, and 1410c of the first portion 1410. Figure 1A In the figure, a portion of the magnetoelectric transducer 20a is also surrounded by the inner side surface 1410d of the first portion 1410 in a plan view, but the magnetoelectric transducer 20a may not be surrounded by the inner side surface 1410d of the first portion 1410 in a plan view.

[0151] The measurement current flows through the terminal portion 142 and the main body portion 141. The pair of terminals 142a, 142b are physically integrated with the main body portion 141 and exposed to the outside of the sealing portion 130. By physically integrating the pair of terminals 142a, 142b with the main body portion 141, it is possible to suppress the reduction in reliability caused by the heat generated by the current conductor 140. Figure 1A In FIG. 1 , the current conductor 140 is a lead frame, and is also referred to as the lead frame 140 . The lead frame 140 is an example of a first lead frame.

[0152] The current conductor 140 does not need to be manufactured in the form of a lead frame in which a plurality of main body portions 141 and terminal portions 142 are connected together as a single metal plate, but may be manufactured using a single-piece metal member.

[0153] Lead frame 150 includes a main body 151 and a terminal portion 152. Terminal portion 152 includes multiple terminals 152a. Main body 151 is an example of a conductive plate at least partially overlapping current conductor 140 when viewed from above. Main body 151 is sealed within sealing portion 130, with first surface 151a, which faces main body 141 of current conductor 140, supporting signal processing IC 100. The surface of main body 151, which supports signal processing IC 100 and is opposite first surface 151a facing main body 141 of current conductor 140, is defined as second surface 151b of main body 151. Some of the multiple terminals 152a may be physically integral with main body 151. At least a portion of each of the multiple terminals 152a is exposed outside sealing portion 130. Lead frame 150 is an example of a second lead frame. Lead frame 140 and lead frame 150 may be formed of a conductive material primarily composed of copper.

[0154] The conductor plate at least partially overlapping the current conductor 140 in a plan view may at least partially overlap the main body 141 of the current conductor 140 in a plan view.

[0155] exist Figure 1A In the embodiment, the conductor plate is a part of the main body 151 of the lead frame 150, but the conductor plate can also be composed of a metal plate independent of the lead frame 150. The conductor plate can be a non-magnetic material. The conductor plate can be made of a material with a conductivity of 4.6×10 6 The conductor plate may be made of a material having a S / m or higher. For example, the conductor plate may be made of a material containing 50% or more copper. The conductor plate may also be made of graphite. The conductor plate may not be exposed from the surface of the sealing portion 130 but may be built into the sealing portion 130. In the case where the conductor plate is formed independently from the lead frame 150, the conductor plate may also be provided on the substrate on which the current sensor 10 is mounted. In this case, the conductor plate may not be exposed from the surface of the substrate on which the current sensor 10 is mounted but may be built into the substrate. Alternatively, the conductor plate may be provided on the substrate on which the current sensor 10 is mounted and further covered with an insulating material.

[0156] The pair of terminals 142a and 142b and the plurality of terminals 152a are arranged opposite each other across the signal processing IC 100 in a direction (y-axis direction) intersecting the thickness direction (z-axis direction) of the signal processing IC 100. The direction intersecting the thickness direction may be a direction along a plane (XY plane) perpendicular to the thickness direction. The pair of terminals 142a and 142b are exposed from the side surface 130a of the sealing portion 130. The plurality of terminals 152a are exposed from the side surface 130b of the sealing portion 130 opposite the side surface 130a.

[0157] like Figure 1B As shown, a pair of terminals 142a, 142b and multiple terminals 152a may protrude outward from opposing side surfaces 130a and 130b of sealing portion 130 at different heights in the thickness direction of sealing portion 130. Surfaces 1521 of multiple terminals 152a on the same side as first surface 100a of signal processing IC 100 and surfaces 1421 of the pair of terminals 142a, 142b on the same side opposite to first surface 100a of signal processing IC 100 may be located at the same height in the thickness direction (z-axis direction) of sealing portion 130. Alternatively, surfaces 1521 of multiple terminals 152a may be located below surfaces 1421 of the pair of terminals 142a, 142b in the thickness direction of sealing portion 130. Specifically, in a direction from first surface 130e of sealing portion 130 on the first surface 100a side of signal processing IC toward second surface 130f of sealing portion 130 on the second surface 151b side of main body 151 of lead frame 150, surface 1521 of plurality of terminals 152a and surface 1421 of pair of terminals 142a, 142b may be located at the same height. Alternatively, surface 1521 of plurality of terminals 152a may be located closer to second surface 130f of sealing portion 130 than surface 1421 of pair of terminals 142a, 142b.

[0158] The current conductor 140 is electrically insulated from the signal processing IC 100 . The current conductor 140 does not have an interface in contact with the signal processing IC 100 .

[0159] When the current conductor 140 is formed of a lead frame and the lead frame 140 and the lead frame 150 are arranged to overlap in the thickness direction, in order to ensure the insulation between the lead frame 140 and the lead frame 150 or the signal processing IC 100, a step may be provided in the thickness direction on at least one of the lead frame 140 and the lead frame 150.

[0160] The main body 141 of the lead frame 140 can be bent within the sealing portion 130 so as to approach the second surface 130f of the sealing portion 130 and be connected to the terminal portion 142. The lead frame 140 can be bent so that the portion of the second surface 141b of the main body 141 on the conductor plate 151 side of the lead frame 140 that is connected to the terminal portion 142 approaches the second surface 130f of the sealing portion 130 by at least half the thickness of the current conductor 140 relative to the portion of the second surface 141b of the main body 141 that faces the first surface 100a, the circuit surface of the signal processing IC 100. The main body 141 can be bent within the sealing portion 130 so as to approach the second surface 130f of the sealing portion 130 and be connected to the terminal portion 142. The main body 141 of the lead frame 140 can be bent by a bending process.

[0161] That is, when the main body 141 of the lead frame 140 is bent by bending, in the direction from the first surface 130e of the sealing portion 130 to the second surface 130f of the sealing portion 130, the portion connected to the terminal portion 142 in the second surface 141b on the conductor plate 151 side of the main body 141 of the lead frame 140 can be located closer to the second surface 130f side of the sealing portion 130 than the surface of the portion opposite to the circuit surface of the signal processing IC 100, that is, the first surface 100a, and the height difference between the surface of the portion opposite to the circuit surface of the signal processing IC 100, that is, the first surface 100a, and the portion connected to the terminal portion 142 can be more than half of the thickness of the lead frame 140.

[0162] The main body 151 of the lead frame 150 can be bent within the sealing portion 130 so as to approach the first surface 130e of the sealing portion 130 on the first surface 100a side of the signal processing IC, and can be connected to the terminal portion 152. The main body 151 of the lead frame 150 can be bent so as to approach the first surface 130e of the sealing portion 130 by at least half the thickness of the main body 151, and can be connected to the terminal portion 152. The main body 151 of the lead frame 150 can be bent by a bending process.

[0163] That is, when the main body 151 of the lead frame 150 is bent by bending, in the direction from the first surface 130e of the sealing portion 130 to the second surface 130f of the sealing portion 130, the portion of the second surface 151b of the main body 151 of the lead frame 150 that is connected to the terminal portion 152 can be located closer to the first surface 130e of the sealing portion 130 than the surface of the portion that supports the signal processing IC 100 and functions as a conductor plate, and the height difference between the surface of the portion that supports the signal processing IC 100 and functions as a conductor plate and the portion connected to the terminal portion 152 can be more than half the thickness of the main body 151 of the lead frame 150.

[0164] The main body 141 of the lead frame 140 can be connected to the terminal portion 142 within the sealing portion 130 via a step having a shear surface, close to the second surface 130f of the sealing portion 130. The step provided within the sealing portion 130 of the main body 141 of the lead frame 140 for connecting the main body 141 of the lead frame 140 to the terminal portion 142 can be no greater than 0.6 times the thickness of the main body 141. Furthermore, the main body 151 of the lead frame 150 can be connected to the terminal portion 152 within the sealing portion 130 via a step having a shear surface, close to the first surface 130e of the sealing portion 130. The main body 151 of the lead frame 150 can be connected to the terminal portion 152 via a step having a shear surface, no greater than 0.6 times the thickness of the main body 151.

[0165] A pair of terminals 142a and 142b protrude from the side surface 130a toward the negative side in the y-axis direction and are further bent toward the negative side in the z-axis direction. Multiple terminals 152a protrude from the side surface 130b toward the positive side in the y-axis direction and are further bent toward the negative side in the z-axis direction. A pair of terminals 142a and 142b may also protrude from the side surface 130a toward the negative side in the y-axis direction and are further bent toward the positive side in the z-axis direction. Multiple terminals 152a may also protrude from the side surface 130b toward the positive side in the y-axis direction and are further bent toward the positive side in the z-axis direction. The pair of terminals 142a and 142b and the multiple terminals 152a may not be bent. That is, the pair of terminals 142a and 142b may also protrude from the side surface 130a toward the negative side in the y-axis direction without being bent toward the positive and negative sides in the z-axis direction. The plurality of terminals 152 a may protrude from the side surface 130 b toward the positive side in the y-axis direction without being further bent toward the positive side and the negative side in the z-axis direction.

[0166] Signal processing IC 100 may be fixed to surface 151 a of main body 151 of lead frame 150 , which supports signal processing IC 100 , via an adhesive layer. The adhesive layer may be a die attach film.

[0167] The current conductor 140 has a slit portion 1411. Alternatively, the current conductor 140 may have a slit portion 1412. The two slit portions 1411 and 1412 are provided in the main body 141 and within the sealing portion 130. The magnetoelectric transducer element 20a is disposed within the slit portion 1411 in a plan view and is thereby partially surrounded by the current conductor 140. Furthermore, if the current conductor 140 has the slit portion 1412, the magnetoelectric transducer element 20b is disposed within the slit portion 1412 in a plan view and is thereby partially surrounded by the current conductor 140.

[0168] Specifically, the current conductor 140 includes the slit portion 1411, forming a first portion that surrounds a portion of the magnetoelectric transducer element. The current conductor 140 includes the slit portion 1412, forming a protrusion 1413 that surrounds at least three side surfaces of the magnetoelectric transducer element 20b when viewed from above. Furthermore, by providing the slit portions 1411 and 1412 in the main body 141, the main body 141, the first portion 1410, and the magnetoelectric transducers 20a and 20b are contained within the sealing portion.

[0169] In this case, the main body 141 of the current conductor 140 and the magnetoelectric transducer 20b are both contained within the sealing portion 130, and their relative positions are less likely to change. Even if the relative position of the conductor plate, which is at least partially overlapping the current conductor 140 when viewed from above, shifts in the XY plane direction relative to the current conductor 140 and the magnetoelectric transducer 20b, the eddy currents generated in the conductor plate will be generated at the position corresponding to the current conductor 140 regardless of the position of the conductor plate. Therefore, compared to a case where the current conductor 140 and the magnetoelectric transducer elements 20a and 20b are located outside the sealing portion 130, where the relative position of the current conductor 140 and the magnetoelectric transducer 20b is easily shifted due to installation deviation, the method of containing the main body 141 of the current conductor 140 and the magnetoelectric transducer elements 20a and 20b within the sealing portion 130 can suppress the deviation in sensitivity suppression caused by eddy currents.

[0170] The magnetoelectric transducer 20a may be disposed within the slit portion 1411 so that three side surfaces of the magnetoelectric transducer 20a are surrounded by the current conductor 140. That is, the magnetoelectric transducer 20a is surrounded by at least the surfaces 1410a, 1410b, and 1410c of the current conductor 140. The magnetoelectric transducer 20a may be further surrounded by the surface 1410d, or may not be surrounded by the surface 1410d.

[0171] By doing so, the measured current does not branch, and the current density can be increased in the portion of the current conductor 140 close to the magnetoelectric transducer 20a, resulting in further improvement in sensitivity. The magnetoelectric transducer 20a is an example of at least one magnetoelectric transducer.

[0172] The magnetoelectric transducer 20b may be arranged in the slit portion 1412 so that three side surfaces of the magnetoelectric transducer 20b are surrounded by the current conductor 140. That is, the magnetoelectric transducer 20b may be surrounded by at least the surface 1410e and surface 1410f of the current conductor 140 that define a portion of the slit portion 1412, and the surface 1413a of the protrusion 1413. The magnetoelectric transducer 20b may be further surrounded by the surface 1413b of the protrusion, or may not be surrounded by the surface 1413b of the protrusion.

[0173] The conductive plate, which at least partially overlaps with the current conductor 140, can at least partially overlap with the magnetically sensitive surface of the magnetoelectric transducer 20a when viewed from above. The conductive plate, which at least partially overlaps with the current conductor 140, can also at least partially overlap with the magnetically sensitive surface of the magnetoelectric transducer 20b when viewed from above. By disposing the magnetoelectric transducer 20b and taking the difference between the magnitude of the magnetic field measured by the magnetoelectric transducer 20a and the magnitude of the magnetic field measured by the magnetoelectric transducer 20b, it is possible to detect the magnetic field caused by the measurement current without being affected by a substantially uniform interfering magnetic field.

[0174] On the other hand, the current conductor 140 may not have the slit portion 1412, in which case the protrusion 1413 does not exist. When the current conductor 140 does not have the slit portion 1412, the two side surfaces of the magnetoelectric converter 20b may be surrounded by the surfaces 1410e and 1410f of the current conductor 140.

[0175] Here, when the current conductor 140 has a slit portion 1412 and the magnetoelectric transducer 20b is disposed within the slit portion 1412, the current flowing through the protrusion 1413 is weaker than the portion of the current conductor 140 surrounding the magnetoelectric transducer 20a, so the magnetoelectric transducer 20b is less susceptible to the skin effect. Similarly, when the two side surfaces are surrounded by the surfaces 1410e and 1410f of the current conductor 140, the magnetoelectric transducer 20b is less susceptible to the skin effect. Therefore, as long as the magnetoelectric transducer 20a, as an example of at least one magnetoelectric transducer portion, satisfies the structure of the present invention, the effects of the present invention can be achieved.

[0176] The magnetoelectric conversion elements 20a and 20b can be fixed to the circuit surface of the signal processing IC 100 by chip bonding, and electrically connected to the signal processing IC 100 by wire bonding. That is, the magnetoelectric conversion elements 20a and 20b can be electrically connected to the signal processing IC 100 via a plurality of leads 22a and 22b. The plurality of leads 22a and 22b can electrically connect the magnetoelectric conversion elements 20a and 20b to the signal processing IC 100 within the slit portions 1411 and 1412. That is, the plurality of leads 22a and 22b can electrically connect the magnetoelectric conversion elements 20a and 20b to the signal processing IC 100 in a manner that does not cross the current conductor 140. By doing so, the magnetic flux interlinked with the leads can be reduced, the induced electromotive force is less likely to be generated, and high-speed response is facilitated.

[0177] The magnetoelectric transducers 20a and 20b can also be electrically connected to the signal processing IC 100 by flip-chip bonding. The magnetoelectric transducers 20a and 20b output the signal processed by the signal processing IC 100 to the signal processing IC 100. The magnetoelectric transducers 20a and 20b can be configured independently of the signal processing IC 100. In other words, the magnetoelectric transducers 20a and 20b can be configured by a chip independent of the chip constituting the signal processing IC 100. The magnetoelectric transducers 20a and 20b can also be built into the chip constituting the signal processing IC 100.

[0178] The magnetically sensitive surfaces of the magnetoelectric conversion elements 20a and 20b can be arranged at a position overlapping with the side surface provided with the slit portion 1411 when viewed from a direction (x-axis direction or y-axis direction) intersecting the thickness direction (z-axis direction) of the magnetoelectric conversion elements 20a and 20b.

[0179] In consideration of stably mounting the magnetoelectric conversion elements 20a and 20b and making the lead wires firmly bonded, the thickness of the magnetoelectric conversion elements 20a and 20b is preferably less than twice the length of one side of the magnetically sensitive surface. Alternatively, it is more preferably less than the same thickness as one side of the magnetically sensitive surface. Even in such a case where the magnetoelectric conversion elements 20a and 20b are not made thicker in order to stably configure the magnetoelectric conversion elements 20a and 20b, by mounting the magnetoelectric conversion elements 20a and 20b on the signal processing IC 100, the shorter distance z between the conductor plate 151 and the current conductor 140 in the z-axis direction described later and the distance between the conductor plate 151 and the magnetically sensitive surface of the magnetoelectric conversion elements 20a and 20b can be appropriately adjusted. b By integrating the magnetoelectric conversion elements 20 a and 20 b into the signal processing IC 100 , adjustment is also facilitated in the same manner.

[0180] The signal processing IC 100 is electrically connected to the plurality of terminals 152a via the leads 108. The leads 22 and 108 can be formed of a conductive material mainly composed of Au, Ag, Cu, or Al.

[0181] The magnetoelectric transducers 20a and 20b may protrude from the first surface 100a of the signal processing IC 100 so that their magnetically sensitive surfaces overlap with the main body 141 of the current conductor 140 in a side view.

[0182] Magnetoelectric transducers 20a and 20b detect a magnetic field in a specific direction that changes based on the measurement current flowing through current conductor 140. Signal processing IC 100 amplifies a signal corresponding to the magnitude of the magnetic field and outputs the amplified signal via terminal 152a. Magnetoelectric transducers 20a and 20b can be chips formed from a compound semiconductor formed on a GaAs substrate and cut into a square or rectangular shape when viewed from above in the z-axis direction.

[0183] The magnetoelectric converter elements 20a and 20b can have a substrate made of silicon or a compound semiconductor and a magnetoelectric converter portion provided on the substrate. The thickness of the substrate can be adjusted by grinding the surface on the negative side in the z-axis direction. Since the magnetic field in the z-axis direction is detected, for example, a Hall element that detects the longitudinal magnetic field in the thickness direction of the current conductor 140 is suitable as the magnetoelectric converter elements 20a and 20b. In other words, the magnetoelectric converter elements 20a and 20b can have a magnetoelectric converter portion of the longitudinal magnetic field detection type. In addition, if the magnetoelectric converter elements 20a and 20b are configured to detect a magnetic field in any axial direction on the XY plane, for example, if they are configured to detect a magnetic field in the x-axis direction, then a magnetoresistive element, a fluxgate element, or a longitudinal Hall element is suitable as the magnetoelectric converter elements 20a and 20b. More specifically, they can be configured so as to overlap with the main body 141 of the current conductor 140 when viewed from above in the z-axis direction.

[0184] The signal processing IC 100 is a large-scale integrated circuit (LSI). The signal processing IC 100 is a monolithic IC. More specifically, the signal processing IC 100 is a signal processing circuit composed of a Si monolithic semiconductor formed on a Si substrate. The signal processing IC 100 has a circuit surface on which magnetoelectric conversion elements 20a and 20b are configured. In the present embodiment, the circuit surface is a first surface 100a corresponding to the top surface of the semiconductor package constituting the signal processing IC 100. The first surface 100a is an example of a circuit surface of the signal processing IC 100. The signal processing circuit processes the output signal corresponding to the magnitude of the magnetic field output from the magnetoelectric conversion elements 20a and 20b. The signal processing circuit corrects the measured current flowing through the current conductor 140 based on the output signal, and outputs the output signal representing the accurate current value via the terminal 152a. The signal processing circuit reduces the noise components contained in the output signals of the magnetoelectric conversion element 20a and the output signals of the magnetoelectric conversion element 20b based on the difference between the output signals of the magnetoelectric conversion element 20a and the output signals of the magnetoelectric conversion element 20b, amplifies the output signals of the magnetoelectric conversion element 20a and the output signals of the magnetoelectric conversion element 20b after the noise components are reduced, calculates the current value of the measured current based on the amplified output signals, and outputs an output signal representing the current value.

[0185] In this embodiment, the current sensor 10 is described as including two magnetoelectric transducers 20a and 20b as magnetoelectric transducers. However, the current sensor 10 only needs to include at least one magnetoelectric transducer. The at least one magnetoelectric transducer is, for example, the magnetoelectric transducer 20a.

[0186] The sealing portion 130 seals the magnetoelectric conversion elements 20a and 20b, the main body 141 of the current conductor 140, the signal processing IC 100, the leads 22, and the leads 108 with a molded resin. The molded resin is composed, for example, of an epoxy-based thermosetting resin containing silicon dioxide, and can be formed into a semiconductor package by transfer molding. It should be noted that, as described later, the sealing portion 130 may or may not seal the conductive plate that at least partially overlaps with the current conductor 140 when viewed from above.

[0187] The measuring current flows from the terminal 142a of the current conductor 140 through the portion of the main body 141 close to the magnetoelectric converter 20a to the terminal portion 142b. During this period, the direction of the current flow is bent in a roughly opposite direction, and the current path does not branch. As a result, the current sensitivity is not dispersed, and it flows in a manner that surrounds the magnetoelectric converter 20a. Therefore, as described later, the sensitivity and the effect of suppressing the skin effect can be improved. In one example, for the current sensor 10, a measuring current of up to 120A can be stably flowed, and a current of more than 400A can also be instantaneously flowed. However, if it is assumed that the temperature is uniform, the current path does not depend on the current value, and therefore, the current value has almost no effect on the characteristics of the current sensor 10 described later.

[0188] In addition, in this embodiment, based on Figure 1A and Figure 1B The following describes an example in which the main body 151 of the lead frame 150 is a conductor plate 151. In the following, when only the main body 141 is described, the main body 141 is used based on the following. Figure 1A and Figure 1B , refers to the portion of the current conductor 140 included in the sealing portion. In the present embodiment, in the current sensor 10 configured as described above, the skin effect generated in the current conductor 140 is effectively suppressed by utilizing the eddy current generated in the conductor plate 151 .

[0189] Figure 2 1 is a diagram showing an example of frequency dependence showing the relationship between sensitivity fluctuation of the magnetoelectric conversion element 20 a and the frequency of the current flowing through the current conductor 140 .

[0190] Figure 2The frequency dependence of the sensitivity of the magnetoelectric transducer 20a in the table system (tabless system) without the conductor plate 151 positioned opposite the main body 141 is shown, as well as the frequency dependence of the sensitivity of the magnetoelectric transducer 20a according to the distance between the main body 141 and the conductor plate 151. In this example, the magnetosensitive surface is located at the same height as the second surface 141b of the main body 141 in the z-axis direction, and the conductor width w is 1 / 4. b 3.5mm.

[0191] exist Figure 2 The line where the sensitivity remains unchanged even when the current frequency is varied, i.e., the portion where the sensitivity variation is greater than 0 dB, represents the portion where the sensitivity of the magnetoelectric transducer 20a increases due to the skin effect of the main body 141. Specifically, due to the skin effect, more current flows near the edge of the main body 141 than near the center when viewed in cross-section. This makes the current flowing through the main body 141 easier for the magnetoelectric transducer 20a to detect, increasing the sensitivity of the magnetoelectric transducer 20a. The portion where the sensitivity variation is less than 0 dB represents the portion where the skin effect of the main body 141 and the increase in the sensitivity of the magnetoelectric transducer 20a are suppressed by the eddy currents of the conductor plate 151. If the skin effect of the main body 141 can be completely eliminated by the eddy currents of the conductor plate 151, the sensitivity variation associated with frequency variation will be 0 dB. However, if the influence of the eddy current of the conductor plate 151 increases, the influence of the eddy current increases as the frequency of the measurement current flowing through the current conductor 140 increases. Therefore, when the frequency of the measurement current is high, the sensitivity of the electrical conversion element 20a decreases more significantly.

[0192] like Figure 2 As shown, in the tabless method (a method in which the current sensor 10 does not include the conductor plate 151), the sensitivity of the magnetoelectric transducer 20a increases as the frequency of the current increases. In the method in which the conductor plate 151 is present, the increase in the sensitivity of the magnetoelectric transducer 20a can be suppressed by the influence of the eddy current generated by the conductor plate 151. However, as the distance between the conductor plate 151 and the main body 141 decreases, the magnetoelectric transducer 20a is easily affected by the eddy current generated by the conductor plate 151. If the distance between the conductor plate 151 and the main body 141 is too short, for example, to 0.06 mm, the sensitivity of the magnetoelectric transducer 20a will be significantly reduced when the frequency of the measurement current flowing through the current conductor 140 is high.

[0193] Figure 3 Shown when looking down Figure 1A An example of the relationship between the sensitivity variation of the magnetoelectric conversion element 20 a whose three side surfaces are surrounded by the main body 141 and the distance between the main body 141 and the conductive plate 151 is shown. Figure 4An example of the relationship between sensitivity variation and the distance between the main body 141 and the conductor plate 151 when current detection is performed based on the difference between the output of the magnetoelectric transducer 20 a and the output of the magnetoelectric transducer 20 b is shown.

[0194] exist Figure 3 and Figure 4 In the case of conductor width w b 0.5mm. Figure 3 and Figure 4 In, z e The height of the magnetic sensitive surface is based on the bottom surface of the main body 141, that is, the second surface 141b of the main body 141 near the magnetoelectric converter 20a. When the magnetic sensitive surface is located higher than the second surface 141b of the main body 141, that is, in a direction away from the conductor plate 151, z e On the contrary, when the magnetic sensitive surface is located lower than the second surface 141b of the main body 141, that is, in the direction close to the conductor plate 151, z e Represents a negative value.

[0195] Compare Figure 3 and Figure 4 It can be seen that the sensitivity fluctuation characteristics are similar when focusing only on magnetoelectric transducer 20a and when focusing on both magnetoelectric transducers 20a and 20b. This is because, simply by reversing the polarity of the magnetic field affecting magnetoelectric transducers 20a and 20b, the sensitivity fluctuation of magnetoelectric transducer 20a is almost identical to the sensitivity fluctuation when taking the difference between magnetoelectric transducers 20a and 20b. Furthermore, since magnetoelectric transducer 20a is surrounded by main body 141 on three sides, it is significantly affected by the magnetic field generated by the current flowing through current conductor 140, the skin effect generated by current conductor 140, and the eddy currents generated by conductor plate 151. Consequently, the sensitivity fluctuation of magnetoelectric transducer 20a is greater than that of magnetoelectric transducer 20b. Therefore, the sensitivity fluctuation when taking the difference between magnetoelectric transducers 20a and 20b behaves similarly to the sensitivity fluctuation of magnetoelectric transducer 20a, allowing magnetoelectric transducer 20a to represent the sensitivity fluctuation when multiple magnetoelectric transducers are included. The following description focuses on the sensitivity fluctuation of the magnetoelectric conversion element 20 a.

[0196] First, the expression of the sensitivity variation of the magnetoelectric conversion element 20 a due to the skin effect will be described.

[0197] When the magnitude of the magnetic field outside the conductor is set to B b , let the magnetic permeability of vacuum be μ0, and the current flowing through the conductor be I f , and the distance from the center of the conductor to the center of the current is r, the magnetic field Bb It can be expressed by the following formula based on Ampere's law.

[0198] [Formula 1]

[0199]

[0200] From this we can see that the magnetic field B b is inversely proportional to the distance r. That is, the magnetic field B b It is inversely proportional to the distance from the center of the current to the center of the magnetic sensitive surface of the magnetoelectric conversion element 20b.

[0201] When direct current is passed through a linear conductor, the distance from the center of the conductor to the center of the magneto-sensitive surface of the magneto-electric conversion element 20 a corresponds to the distance r.

[0202] When a high-frequency current flows through a conductor, the skin effect that occurs in the conductor is indicated by the skin depth, which indicates the depth to which the current flows from the conductor's surface. The skin depth is the depth at which the current decays to 1 / e relative to the conductor's surface. When the skin depth is d, the magnetic permeability of the conductor is μ, the electrical conductivity is σ, and the frequency is f, the skin depth can be expressed by the following formula.

[0203] [Formula 2]

[0204]

[0205] Therefore, the distance r can be derived by assuming that the current flows from the surface of the conductor to the depth d. Note that, for non-magnetic materials such as copper, it can be assumed that μ = μ0 = 4π × 10 -7 NA -2 .

[0206] However, this assumption assumes that the conductor is straight. In reality, the conductor is U-shaped, so even when a DC current flows through the conductor, the current concentrates on the inner side of the U-shaped portion. In other words, the current concentrates on the magnetically sensitive surface side of the magnetoelectric converter element 20a. Therefore, if the distance from the center of the conductor to the center of the magnetically sensitive surface is r and the magnetic field B is derived, b (f=0), the magnetic field when a DC current is applied to the conductor is smaller than the actual value, and the sensitivity variation of the magnetoelectric conversion element 20a due to the frequency variation becomes a large calculated result.

[0207] Therefore, even in the case of a direct current, it is assumed that the current moves from the center of the conductor toward the magnetic sensitive surface at a constant ratio s, and the distance r is expressed by the following equation.

[0208] r=(distance from the magnetic sensitive surface to the surface of the conductor)+(conductor width)×(1-s) / 2…(2)

[0209] According to formula (2), when a DC current is applied to a conductor, the distance r from the magnetic sensitive surface to the center of the current can be derived, and the magnetic field B acting on the magnetic sensitive surface can be derived. b (f=0).

[0210] When the state in which a direct current is applied to a conductor changes to the state in which an alternating current is applied to the conductor, the current moves further toward the magnetically sensitive surface due to the influence of the skin effect.

[0211] Here, let r = (distance from the magnetic sensitive surface to the surface of the conductor) + (skin depth / 2) and derive the magnetic field B acting on the magnetic sensitive surface when AC is applied: skin (f). In this case, in B skin (f)>B b In the high frequency region (f=0), by setting B skin (f) / B b (f = 0), the sensitivity variation caused by the skin effect can be derived. skin (f) b (f = 0), the skin effect does not appear in the region other than the high frequency region, so it is set to B b (f) = B b (f=0).

[0212] Therefore, when the conductor width is set to w b The shortest distance from the center of the magnetic sensitive surface to the surface of the current conductor is set as h, and the conductivity of the conductor is set as σ b , where the frequency of the current is f and the magnetic permeability of the conductor at frequency f is μ, the frequency-dependent sensitivity variation due to the skin effect can be expressed using the variable s as shown in the following equation (3). The variable s represents the current deflection from the center of the conductor toward the magnetic sensitive surface due to the skin effect.

[0213] [Formula 3]

[0214]

[0215] The denominator of formula (3) represents a quantity proportional to the sensitivity of the magnetoelectric transducer 20a in the case of a high-frequency current, and the numerator represents a quantity proportional to the sensitivity of the magnetoelectric transducer 20a in the case of a direct current.

[0216] Figure 5 The graph shows the relationship between sensitivity variation and frequency derived from equation (3). The material of the current conductor is assumed to be copper. b ​The simulation results obtained by calculating the sensitivity change using the finite element method when the conductor width is set to 3.5 mm are shown in the other graph. b The sensitivity fluctuations were calculated using Equation (3) for a value of 3.5 mm and s = 0.86. Thus, the sensitivity fluctuation calculations using Equation (3) do not differ significantly from those using the finite element method. Specifically, these calculations indicate that when a DC current is applied to a conductor, 86% of the current flows from the center of the conductor toward the magnetically sensitive surface. This result well illustrates the actual sensitivity fluctuations in this situation.

[0217] By partially surrounding at least three sides of the magnetoelectric converter element 20a, even if the measured current is DC, 86% of the current density is concentrated in the area close to the magnetoelectric converter element. In other words, s is large. As is clear from equation (3), a large s reduces the influence of the skin effect, making it easier for eddy currents to improve frequency characteristics.

[0218] Figure 6 The vertical axis represents the sensitivity change of the magnetoelectric conversion element 20a when the frequency is 10 MHz, and the horizontal axis represents the conductor width w. b An example of the calculation results when . One graph shows the simulation results obtained by calculating the sensitivity variation using the finite element method, and the other graph shows the calculation results when s = 0.86 and equation (3) is used. In this way, even when the conductor width is changed, the calculation results using the finite element method do not differ significantly from the calculation results using equation (3). In other words, it can be said that using equation (3) to express the sensitivity variation caused by the skin effect with frequency is an effective method.

[0219] Next, the expression of the sensitivity variation of the magnetoelectric conversion element 20 a caused by the eddy current generated in the conductor plate 151 will be described.

[0220] Figure 7 FIG. 2 shows the relationship between the sensitivity change of the magnetoelectric conversion element 20a and the distance between the main body 141 and the conductor plate 151. Figure 7 In the figure, the vertical axis represents the conductor width w b The sensitivity change when the distance is 0.5 mm and the frequency f is 10 MHz. The horizontal axis represents the distance between the conductor plate 151 and the main body 141. Figure 7 In, z e Indicates the height from the bottom surface of the main body 141 to the magnetic sensitive surface. Figure 7 In the figure, the height z is shown. eAccordingly, the sensitivity variation of the magnetoelectric conversion element 20 a depends on the distance between the main body 141 and the conductor plate 151 .

[0221] like Figure 7 As shown, when the distance between the conductor plate 151 and the main body 141 is relatively close, the height z e When fixed, the influence of eddy currents generated in the conductor plate 151 increases, and sensitivity tends to decrease. In other words, the greater the distance between the conductor plate 151 and the main body 141, the smaller the influence of eddy currents generated in the conductor plate 151, and the higher the sensitivity tends to be.

[0222] Here, the shorter distance between the conductor plate 151 and the main body 141 and the distance between the conductor plate 151 and the magnetic sensitive surface is represented as z. b .

[0223] like Figure 8A As shown, when the magnetic sensitive surface 21a of the magnetoelectric conversion element 20a is located lower than the surface 141b of the main body 141 facing the signal processing IC 100, the distance z b represents the distance between the surface 151a of the conductor plate 151 on which the signal processing IC 100 is disposed and the magnetic sensitive surface 21a of the magnetoelectric conversion element 20a. Figure 8B As shown, when the magnetic sensitive surface 21a of the magnetoelectric conversion element 20a is located higher than the surface 141b of the main body 141 facing the signal processing IC 100, the distance z b 14 shows the distance between surface 151 a of conductive plate 151 on which signal processing IC 100 is arranged and surface 141 b of main body 141 facing signal processing IC 100 .

[0224] Figure 9 The sensitivity variation of the magnetoelectric conversion element 20a and the distance z are shown. b In the relationship. Figure 9 In the figure, the vertical axis represents the conductor width w b The sensitivity change when the distance is 0.5 mm and the frequency f is 10 MHz. The horizontal axis represents the shorter distance z between the distance between the conductor plate 151 and the main body 141 and the distance between the conductor plate 151 and the magnetic sensitive surface. b .like Figure 9 As shown in FIG, even if the height z from the bottom surface of the main body 141 to the magnetic sensitive surface is set as e The sensitivity of the magnetoelectric converter 20a also changes with the distance z. b Varies along a single curve.

[0225] That is, in the region where the current conductor 140 is not present between the magnetic sensitive surface 21a and the conductor plate 151, the effect of the eddy current on the change in the magnetic field ΔB depends on the distance between the conductor plate 151 and the magnetic sensitive surface 21a. On the other hand, when at least a portion of the current conductor 140 is present in the vicinity between the magnetic sensitive surface 21a and the conductor plate 151, a portion of the effect of the eddy current is shielded by the current conductor 140. Therefore, the effect of the eddy current on the change in the magnetic field ΔB depends on the distance between the conductor plate 151 and the main body 141 of the current conductor 140. Therefore, it can be said that the distance z is used to determine the change in the magnetic field ΔB. b It is effective to evaluate the sensitivity variation of the magnetoelectric conversion element 20 a caused by the eddy current as a parameter.

[0226] Therefore, if Figure 9 By expressing the curve shown, it is possible to quantitatively evaluate the sensitivity fluctuation of the magnetoelectric conversion element 20a caused by the eddy current.

[0227] Here, when current is passed through a coil to generate eddy current in a conductor around the coil, as shown in the literature (Y. Li, T. Theodoulidis, GY Tian, ​​Transactions on Magnetics, 43, 4010 (2007)), the change in magnetic field caused by the eddy current ΔB z It can be expressed by the following formula (4).

[0228] [Formula 4]

[0229]

[0230] Figure 10 This is a diagram for explaining the definition of parameters of equation (4) related to coils and conductors (Y. Li, T. Theodoulidis, GY Tian, ​​Transactions on magnetics, 43, 4010 (2007)). Figure 10In the diagram, the distance from the axial center of coil L to the inner circumference of coil L is r1, and the distance from the axial center of coil L to the outer circumference of coil L is r2. Conductor D consists of a first layer 1, a second layer 2, and a third layer 3, in descending order from coil L. The distance from the surface of coil L facing conductor D to the surface of first layer 1 facing coil L is z1, and the distance from the surface of coil L opposite to the surface facing conductor D to the surface of first layer 1 facing coil L is z2. With respect to the surface of first layer 1 facing coil L, the coordinates of the boundary between first layer 1 and second layer 2 are -d1, and with respect to the surface of first layer 1 facing coil L, the coordinates of the boundary between second layer 2 and third layer 3 are -d2. The magnetic permeability of first layer 1 is μ1, and the electrical conductivity of first layer 1 is σ1. The magnetic permeability of second layer 2 is μ2, and the electrical conductivity of second layer 2 is σ2. The magnetic permeability of the third layer 3 is μ3, and the electrical conductivity of the third layer 3 is σ3. Furthermore, the current density is i0. The magnetic permeability of vacuum is μ0. J(x) represents a Bessel function.

[0231] When the conductor D consists of one layer, R(a) can be expressed by the following formula.

[0232] [Formula 5]

[0233]

[0234] Furthermore, b1 can be expressed by the following formula.

[0235] [Formula 6]

[0236]

[0237] In addition, X(x 1, x2) can be expressed by the following formula.

[0238] [Formula 7]

[0239]

[0240] According to the above formula (4), the change in magnetic field ΔB z It can be expressed as the integral of a. And, if z is taken as the coefficient of a, the change in the magnetic field ΔB z Since the magnitude of the eddy current is proportional to the frequency, Ce is set as the proportionality constant, and the change in the magnetic field caused by the eddy current is ΔB. z It is approximated as follows.

[0241] [Formula 8]

[0242] ΔB z =-Cef / z b …(4)

[0243] Also, if Ce = 4.5×10 -12 , adding the skin effect term from Equation (3) above to Equation (4) and performing fitting and plotting results in Figure 9 the solid line shown.

[0244] The above equation representing the change in magnetic field ΔB caused by eddy currents z is an equation derived assuming the use of an ideal conductor. On the other hand, in a real conductor, i.e., the eddy currents generated in the conductor plate 151 can be reduced by decreasing the conductivity of the conductor plate 151, narrowing the width of the conductor plate 151, or thinning the thickness of the conductor plate 151. That is, in the case where the influence of eddy currents is large, by changing the thickness or conductivity of the conductor plate 151, eddy currents can be suppressed.

[0245] The thickness of the conductor plate 151 needs to consider the penetration depth to which eddy currents can penetrate. That is, it is necessary to evaluate the change in magnetic field ΔB caused by eddy currents separately according to whether the thickness of the conductor plate 151 exceeds the penetration depth where eddy currents can flow, i.e., the skin depth. The change in magnetic field caused by eddy currents is proportional to the coefficient Cσ t for correcting the eddy currents generated in the conductor plate 151 under conditions such as conductivity and frequency in a state where both the conductivity and frequency of the conductor 151 are high.

[0246] Therefore, when the skin depth is set to d and the thickness of the conductor plate 151 is set to u, it can be said that in the low-frequency region, i.e., when the thickness of the conductor plate 151 is smaller than the skin depth (u < d), the eddy currents spread throughout the thickness direction of the conductor plate 151, and the eddy currents are restricted by the thickness of the conductor plate 151. Thus, the current path is not restricted by the skin depth, and therefore, the resistance value R t of the conductor plate 151 can be expressed by the following equation.

[0247] [Equation 9]

[0248]

[0249] On the other hand, setting M as the mutual inductance between the current conductor 140 and the conductor plate 151, t as the time, and A as a proportional constant, the electromotive force of the eddy currents can be expressed by the following equation using the frequency f of the current flowing through the current conductor 140.

[0250] [Equation 10]

[0251] I f = Asin2πft

[0252] Thus, the electromotive force of the eddy current is proportional to the frequency f of the current flowing through the current-carrying conductor 140. Here, in Equation (1) representing the skin depth, the frequency f is included as a parameter. According to Equation (1), the higher the frequency, the smaller the skin depth.

[0253] According to the resistance value R t and the electromotive force V t in their respective equations, the change amount ΔB of the magnetic field caused by the eddy current is expressed by the following equation.

[0254] [Equation 11]

[0255]

[0256] Thus, when the thickness of the conductor plate 151 is smaller than the skin depth, that is, u < d, ΔB is proportional to the frequency f and the conductivity σ of the conductor plate 151 t However, in the region where the frequency f is large, it saturates by completely eliminating the magnetic field B generated in the main body portion 141, and the dependence on the frequency f disappears. That is, in principle, ΔB converges to a certain value, and 1 is the upper limit as the change rate of the magnetic field. On the other hand, for the correction coefficient Cσ representing the effect of suppressing the eddy current t , in the region where the frequency f is large, the magnetic field B generated in the conductor plate 151 is not suppressed by the thickness u and σ of the conductor plate 151 t , and the dependence on the frequency f disappears. That is, the effect of suppressing the eddy current generated in the conductor 151 disappears, so the correction coefficient converges to 1. Thus, the change rate of the magnetic field caused by the eddy current and the correction coefficient Cσ t both converge to 1, and as a result, they have the same value.

[0257] On the other hand, when the thickness of the conductor plate 151 is larger than the skin depth, that is, u > d, the skin depth restricts the eddy current more than the conductor plate 151.

[0258] When the magnetic permeability of the conductor plate 151 is set to μ t , the conductivity is set to σ t , and the frequency is set to f, the skin depth d of the conductor plate 151 can be expressed by the following equation.

[0259] [Equation 12]

[0260]

[0261] The effective thickness of the conductor plate 151 within the range where the eddy current flows can be assumed to be d. Thus, the resistance value R of the conductor plate 151 t can be expressed by the following equation using the range w of the eddy current flowing through the conductor plate 151 eff .

[0262] [Equation 13]

[0263]

[0264] Furthermore, the amount of change ΔB in the magnetic field caused by the eddy current can be expressed by the following equation.

[0265] [Formula 14]

[0266]

[0267] Therefore, when the thickness of the conductor plate 151 is greater than the skin depth (u>d), the change in the magnetic field ΔB is proportional to f 1 / 2 and σ t 1 / 2 However, in the region where the frequency f is relatively high, the effect of suppressing the eddy current generated in the conductor 151 disappears, so the correction coefficient converges to 1. That is, in the region where the frequency f is relatively high, the magnetic field B generated in the conductor plate 151 is affected by the thickness u of the conductor plate 151 and σ t The inhibitory effect disappears and the frequency f dependence disappears.

[0268] Figure 11 The correction coefficient Cσ for the sensitivity variation rate caused by eddy current is shown. t The relationship between the change in magnetic field ΔB and the conductivity of the conductor plate 151 is obtained using the finite element method. As described above, in the case of high frequency, the change in magnetic field ΔB and the conductivity σ of the conductor plate 151 are related. t The correction coefficient Cσ is proportional to the 1 / 2 power of t It also depends on this. Figure 11 The graph shown is a double logarithmic graph. And, in the case of a frequency of 10 MHz, the slope of the line segment L1 is σ t 1 / 2 The power of Figure 11 The curve shown in the figure shows that, in the case of high frequency, the correction coefficient Cσ of the magnetic field t , that is, the effect of eddy current on the sensitivity variation rate and the conductivity σ of the conductor plate 151 t Proportional to the power of 1 / 2.

[0269] On the other hand, at low frequencies, the sensitivity variation correction coefficient Cσ t The conductivity σ of the conductor plate 151 t When the frequency is 10kHz, the slope of line segment L2 is σ. t The power of Figure 11 The curve shown in the figure shows that, in the case of low frequency, the correction coefficient Cσ of the magnetic field t , that is, the effect of eddy current on the sensitivity variation rate and the conductivity σ of the conductor plate 151 t Proportional to the power of .

[0270] Considering the above expression of the sensitivity variation rate due to eddy current, as the thickness u of the conductor plate 151 and the conductivity σ of the conductor plate 151 t The correction term Cσ t , the following situations can be used to show how much the sensitivity change caused by eddy current is suppressed.

[0271] [Formula 15]

[0272] (1) In, and In the case of

[0273]

[0274] [Formula 16]

[0275] (2) When u<d, and In the case of

[0276]

[0277] [Formula 17]

[0278] (3) In cases other than (1) and (2),

[0279]

[0280] Here, the constant C is determined in a manner consistent with the results of the finite element method. u<d 、C u>d C u<d =4×10 -17 、C u>d =1.8×10 -14 .

[0281] As described above, the conductor plate 151 can be made of a member common to the terminal portion 152. The conductor plate 151 can be a non-magnetic body. For example, the conductor plate 151 can be made of a material containing 50% or more of copper. The conductor plate 151 can also be made of a member independent of the terminal portion 152. In this case, the conductor plate 151 can be made of, for example, an aluminum alloy that is easy to process and inexpensive. In addition, the conductor plate 151 can also be made of graphite. When the conductor plate 151 is made of graphite, the conductivity can be made 1×10 5 Even if the value of z bEven when the eddy current is small, it is possible to control the eddy current to an appropriate size and obtain good frequency characteristics. In addition, when a magnetic material is used as the conductor plate 151, it is also possible to increase the actual resistivity by taking the magnetic permeability into account in formula (5), thereby suppressing the eddy current to an appropriate size. In addition, there may be a case where the conductor plate 151 is thinned in order to control the eddy current to an appropriate size. In this case, the conductor plate 151 can also be formed using methods such as evaporation and plating.

[0282] The width w of the conductor plate 151 t When the eddy current is smaller, the current path of the eddy current is limited. If the eddy current is effectively w eff / 2 range uniformly flows, then the resistance value R of the conductor plate 151 at this time t In w t <2w eff The width w of the conductor plate 151 can be expressed as follows. t It is the width of the narrowest portion of the conductor plate 151 that crosses the portion overlapping with the magnetoelectric conversion elements 20 a and 20 b .

[0283] [Formula 18]

[0284]

[0285] Therefore, the amount of change ΔB in the magnetic field can be expressed by the following equation.

[0286] [Formula 19]

[0287]

[0288] Figure 12 This is a graph showing the relationship between the normalized sensitivity variation rate and the width of the conductor plate 151, depending on the positional relationship between the conductor plate 151, the main body 141 of the current conductor 140, and the magnetoelectric conversion element 20a in the thickness direction. The normalized sensitivity variation rate is a value obtained by normalizing the sensitivity when the conductor plate 151 is sufficiently wide and does not restrict eddy currents. Figure 12 As shown in FIG. 1 , if the width of the conductive plate 151 decreases, the sensitivity variation rate decreases according to the formula (6).

[0289] The actual shortest distance h between the center of the magnetically sensitive surface of the magnetoelectric conversion element 20 a and the main body 141 is set to w. eff =2h, if Figure 12 As shown in the graph, it can be confirmed that the behavior is similar to the line segment expressed by the finite element method. This reflects that 86% of the measured current flows toward the side of the main body 141 close to the magnetic sensitive surface, indicating that the eddy current density is high in the conductor plate 151 directly below it.

[0290] Thus, the correction term C of the width of the conductor plate 151 can be w (w t ) is expressed as follows.

[0291] [Formula 20]

[0292] In w t If the time is less than 4 hours,

[0293]

[0294] [Formula 21]

[0295] In w t For ≥4h,

[0296] C w (w t )=1.

[0297] The above description has described the correction term based on the skin effect and the correction term based on the eddy current.

[0298] Sensitivity fluctuations are generally expressed in decibels. Therefore, the sensitivity increase due to the skin effect and the sensitivity decrease due to eddy currents are expressed in decibels. In this case, the absolute value of the sensitivity fluctuation when eddy currents are added to the skin effect due to the presence of conductor plate 151 is smaller than when the sensitivity fluctuation occurs only due to the skin effect in conductor plate 141. This is the condition for achieving the appropriate effect of eddy currents. This can be expressed in the following formula.

[0299] [Formula 22]

[0300]

[0301] This formula can be transformed into the following formula.

[0302] [Formula 23]

[0303]

[0304] That is, the range in which the sensitivity reduction due to eddy currents does not exceed twice the sensitivity increase due to the skin effect can be said to be the range in which the frequency characteristics can be improved by eddy currents.

[0305] [Formula 24]

[0306]

[0307] Next, the range in which the eddy current exhibits a significant effect without being too small and exceeding manufacturing variations will be described.

[0308] The largest manufacturing variation is considered to be the positional deviation of the magnetoelectric converter element 20a during the die bonding process. Typical die bonding equipment has a positional deviation of approximately ±25 μm. Finite element method results indicate that the sensitivity variation caused by this positional deviation is 0.23%. The range in which eddy currents exceed this sensitivity can be expressed as follows.

[0309] [Formula 25]

[0310]

[0311] That is, it can be expressed by the following formula.

[0312] [Formula 26]

[0313]

[0314] Current sensors that measure current at 5 MHz are known for their high-speed response. Current sensors that measure currents exceeding 5 MHz are required to suppress sensitivity fluctuations caused by frequencies between 5 MHz and 10 MHz. Specifically, a current sensor that measures current at 10 MHz must satisfy the following equation, derived by substituting f = 10 MHz into equation (7).

[0315] [Formula 27]

[0316]

[0317] A current sensor that follows a measurement current of 5 MHz needs to satisfy the following equation derived by substituting f=5 MHz into the above equation (7).

[0318] [Formula 28]

[0319]

[0320] Here, in order to illustrate a specific example, after setting an assumed value for each parameter, a more simplified expression is derived in the form of numerical values.

[0321] As described above, when the frequency f is 10 MHz, the following equation must be satisfied.

[0322] [Formula 29]

[0323]

[0324] As another specific example, when the conductive plate 151 is a non-magnetic body, a more simplified expression is derived in a numerical form.

[0325] In the case where the conductor plate 151 is a non-magnetic material, the magnetic permeability of the conductor plate 151 can be approximated to be approximately equal to the magnetic permeability of vacuum μ0 = 4π×10 7 which is approximately equal.

[0326] In addition, in the case where the conductor plate 151 is a non-magnetic material, preferably, the lower limit of the conductivity σ of the conductor plate 151 t is 4.6×10 6 S / m < σ t , and the range of the thickness u of the conductor plate 151 is 20μm < u < 1mm.

[0327] In particular, when the thickness u [m] of the conductor plate 151 and σ t [S / m] satisfy

[0328] [Formula 30]

[0329]

[0330] the relationship of

[0331] [Formula 31]

[0332]

[0333] Equation (8) can be expressed as

[0334] [Formula 32]

[0335]

[0336] In addition, in the case where the conductor plate 151 is a non-magnetic material, preferably, the range of the shortest distance h is 0.05mm < h < 0.5mm, and the width w of the main body portion 141 t is in the range of 2mm < w t < 20mm.

[0337] When in such a range, it becomes ​​​​​​​​​​​​​​​​​​​​The range of w is 0.4 mm < w b <10 mm, and the distance z b The range of z is 0.255 mm < z b <19.6 mm. When each parameter satisfies the above range, Equation (8) is satisfied.

[0344] Moreover, when the current conductor 140 and the conductor plate are made of copper, after setting the assumptions of each parameter, a further simplified expression is derived in numerical form.

[0345] It can be assumed that for the magnetic permeability of the current conductor 140 and the conductor plate 151, μ b = μ t = 4π×10 -7 N / A 2 and for the conductivity of the current conductor 140 and the conductor plate 151, σ b = σ t = 5.95×10 7 S / m. Here, it is assumed that the thickness u of the conductor plate 151, the shortest distance h, and the width w of the current conductor 140 t are in the range where the correction term Cσ t and the correction term C wt become 1. For example, if the range of the thickness u of the conductor plate 151 is 20 μm < u < 1 mm, the range of the shortest distance h is 0.05 mm < h < 0.5 mm, and the width w t of the main body portion 141 is in the range of 2 mm < w t <20 mm, then the values of the correction term Cσ t and the correction term C wt become 1. In this case, the maximum conductor width w b of the portion of the main body portion 141 surrounding the magnetoelectric conversion element 20a is fixed, and the relationship between the shorter distance z between the conductor plate 151 and the main body portion 141 and the distance between the conductor plate 151 and the magnetic sensitive surface and the shortest distance h between the center of the magnetic sensitive surface of the magnetoelectric conversion element 20a and the main body portion 141 is derived. In this case, in the range where the shortest distance h is 0.05 mm < h < 0.5 mm, as a result of numerical calculation, the lower limit of the distance z b can be approximated as being approximately linear with respect to the shortest distance h. In addition, its coefficient can be approximated as being inversely proportional to the maximum conductor width w b . Therefore, the lower limit of the distance z b preferably satisfies the following formula. b The lower limit preferably satisfies the following formula.

[0346] [Formula 35]

[0347]

[0348] In addition, the distance z b The upper limit of can be calculated as 19.6 mm. As described above, the correction term Cσ can be derived. t and correction item C wt The distance z when set to 1 b An approximate range of .

[0349] Here, in Patent Documents 1 and 4, since an opening is provided in the primary conductor, the current density decreases due to the branching of the measured current. As a result, the sensitivity cannot be improved. Since the sensitivity cannot be improved in the state where the frequency of the measured current is low, the sensitivity ratio relative to the direct current will increase when the sensitivity changes. In addition, since the magnetoelectric conversion element is not locally surrounded, the current density is not concentrated around the magnetoelectric conversion element when the frequency of the measured current is low. In other words, the current density distribution becomes relatively uniform. On the other hand, when the frequency is increased, the current path is concentrated on the surface of the current conductor due to the skin effect. Therefore, compared with the case where the measured current is a direct current, the sensitivity change caused by the skin effect is very large when the frequency is high. Here, generally speaking, the frequency dependence of the size of the eddy current generated in the metal plate is different from the skin effect. Therefore, when the skin effect is large, it is difficult to eliminate it in a wide frequency range using eddy currents. In Patent Document 2, when the supporting member supporting the magnetoelectric conversion element is a semiconductor substrate, the skin effect cannot be suppressed. When the supporting member is a metal plate, the distance between the primary conductor and the supporting portion is close, and the influence of eddy current is large. Therefore, the sensitivity decreases as the frequency of the measured current increases. In addition, in Patent Document 2, since the magnetoelectric conversion element is connected to the metal plate only via an adhesive layer, the upper limit of Zb is limited, and the influence of eddy current is likely to be excessive. In Patent Document 3, since a current path is arranged on the substrate outside the sealing portion, the relative position of the measured current and the sensor element is easily changed due to installation offset, and the deviation of the sensitivity is large. Moreover, since the current conductor is straight, the current path is not bent, and the influence of the skin effect is very large. Therefore, it is difficult to use eddy current to improve the frequency characteristics in a wide frequency range.

[0350] Patent document 5 discloses an example in which a magnetoelectric converter element is surrounded on all four sides by a current conductor, and the current conductor has a portion close to three side surfaces of the magnetoelectric converter element and a portion away from one side surface of the magnetoelectric converter element. However, as in the examples disclosed in Patent Documents 1 and 4, the current density decreases due to the branching of the measured current. In addition, the resistance value of the portion of the current conductor sandwiched between the magnetoelectric converter elements is higher than that of the portion away from one side surface of the magnetoelectric converter element. As a result, the amount of current flowing through the portion sandwiched between the magnetoelectric converter elements is reduced, the sensitivity during direct current is reduced, and the ratio of sensitivity variation tends to increase.

[0351] On the other hand, according to the present embodiment, by designing the current sensor 10 so as to satisfy the above-mentioned conditions, the skin effect generated in the current conductor 140 can be effectively suppressed by utilizing the eddy current generated in the conductor plate 151 .

[0352] The above description uses an example in which the magnetoelectric transducers 20a and 20b are longitudinal magnetic field detection elements. However, even if the magnetoelectric transducers 20a and 20b are transverse magnetic field detection elements such as ferromagnetic magnetoresistive (MR) elements, tunneling magnetoresistive (TMR) elements, or vertical Hall effect elements, the frequency characteristics can be improved using the same principle. Specifically, by utilizing eddy currents to eliminate the skin effect generated in the main body 141, the current sensor 10 can achieve faster response.

[0353] Next, a modification of the current sensor 10 to which this principle can be applied will be described. The current sensors 10A to 10H described below differ from the current sensor 10 in that they utilize magnetoelectric transducers embedded in the signal processing IC 100 as the magnetoelectric transducers 20a and 20b. Figure 1A and Figure 1B The current sensor 10 shown is different. In each modification, there may also be magnetoelectric conversion elements 20a, 20b such as Figure 1A and Figure 1B In this way, it is constructed independently from the signal processing IC. Figures 13 to 20 About Figure 1A and Figure 1B The description of the same configuration among the components denoted by the reference numerals is omitted.

[0354] Figure 13 The current sensor 10A shown has the same configuration relationship of components as the current sensor 10, except that the magnetoelectric converter 20b (20a) is embedded in the signal processing IC 100. Since the magnetoelectric converter 20b (20a) is embedded in the signal processing IC 100, the distance from the conductor plate 151 to the magnetic sensitive surface of the magnetoelectric converter 20b is shorter than the distance from the conductor plate 151 to the main body 141. Therefore, the distance z bIt is the distance from the conductor plate 151 to the magnetic sensitive surface of the magnetoelectric conversion element 20b.

[0355] Figure 14 The current sensor 10B shown differs from the current sensor 10 in that the signal processing IC 100, in which the magnetoelectric conversion element 20b (20a) is embedded, is arranged on the side of the main body 141 opposite to the side 141b facing the conductor plate 151. The signal processing IC 100 is arranged on the side 141a of the main body 141 via the insulating member 160. The insulating member 160 can be a chip attach film, an insulating plate, a polymer film, etc. By arranging the insulating member 160 between the signal processing IC 100 and the main body 141, the withstand voltage between the signal processing IC 100 and the main body 141 can be ensured. In order to avoid potential surface discharge, the insulating member 160 can be arranged so as to protrude from the signal processing IC 100 when viewed from above. In the case of such a structure, the conductor plate 151 can also be composed of the same lead frame 150 as the terminal portion 152.

[0356] Figure 15 The illustrated current sensor 10C differs from the current sensor 10B in the following respects: the lead frame 150 on the signal terminal side is bent toward the bottom surface of the sealing portion 130, or surface 130f, so that it is at a different height than the main body 141 of the current conductor 140 when viewed from the side. Furthermore, a conductor plate 170, independent of the lead frame 150, is positioned on the surface of the main body 151 of the lead frame 150, on the side of the sealing portion 130, facing surface 130f. The signal processing IC 100 and the magnetoelectric converter element 20b (20a) are positioned opposite the conductor plate 170. In this case, the current conductor 140 and the lead frame 150 do not need to be separate lead frames; they can be separated from the same component. Since the lead frame 140 and the lead frame 150 do not need to be placed together and sealed by the sealing portion 130, manufacturing is simplified, and manufacturing costs can be reduced. Furthermore, the conductor plate 170 can be made of a different material from the lead frame 150. That is, the conductor plate 170 can be made of a material such as aluminum alloy that is cheaper than the lead frame 150 , has the best electrical conductivity, and has an optimized shape.

[0357] Figure 16The illustrated current sensor 10D differs from the current sensor 10C in that a conductive plate 170 is disposed on the surface 141b of the main body 141 of the current conductor 140, with an insulating member 162 interposed therebetween. As with the current sensor 10C, the conductive plate 170 can be made of a material different from that of the lead frame 150. Specifically, the conductive plate 170 can be made of a material such as aluminum alloy that is less expensive than the lead frame 150, has optimal conductivity, and has an optimized shape. Furthermore, since the conductive plate 170 is a separate component, there are no restrictions on thickness, width, or material, making it easier to design the current sensor 10D to improve its frequency characteristics.

[0358] Figure 17 The current sensor 10E shown differs from the current sensor 10C in the following respects: a conductor plate 170 is arranged at a position opposite to the magnetic sensitive surface of the magnetoelectric conversion element 20b (20a) on the circuit surface 100a of the signal processing IC 100, with an insulating member 162 interposed therebetween. Since the signal processing IC 100 and the conductor plate 170 are mounted on one surface 141a of the main body 141 of the current conductor 140, manufacturing is easy. In addition, the risk of discharge between the conductor plate 170 and the current conductor 140 is also low. Moreover, the distance between the conductor plate 170 and the magnetic sensitive surface is the distance z b The distance z can be accurately determined by the insulating member 162 between the conductor plate 170 and the magnetic sensitive surface regardless of the processing accuracy of the lead frame. b .

[0359] Figure 18The current sensor 10F shown differs from the current sensors 10 to 10E in that the conductor plate 170 is not sealed by the sealing portion 130 but is built into the substrate 200 on which the current sensor 10F is mounted. The signal processing IC 100 is arranged on the surface 141b of the main body 141 of the current conductor 140, which is on the bottom surface of the sealing portion 130, i.e., the surface 130f side. The circuit surface 100a of the signal processing IC 100 faces the surface 130f side of the sealing portion 130. In other words, the magnetic sensitive surface of the magnetoelectric conversion element 20b (20a) built into the signal processing IC 100 faces the surface 130f side of the sealing portion 130. The substrate 200 has a pad portion 201 electrically connected to the terminal portion 142 on the current conductor side and a pad portion 202 electrically connected to the terminal portion 152 on the signal terminal side. Moreover, the substrate 200 has a built-in conductor plate 170 at a position opposite to the magnetic sensitive surface of the magnetoelectric conversion element 20b (20a). In the case of such a structure, there is no need for a lead frame for configuring the conductor plate 170 or a special process for configuring the conductor plate 170. It can be prepared by appropriately setting the layout of the substrate 200, which is relatively simple. The conductor plate 170 can also be arranged on the surface of the substrate 200 instead of being built into the substrate 200. In the case where the conductor plate 170 is located on the surface of the substrate 200, it can be covered with an insulating material such as an anti-etching agent. Thereby, the occurrence of surface discharge from the terminal portion 142 on the current conductor side to the terminal portion 152 on the signal terminal side can be suppressed. The insulating material covering the conductor plate 170 can be a high heat dissipation resin. In the case where the conductor plate 170 is arranged on the surface of the substrate 200, the distance z b It is the distance from the bottom surface of the terminal portions 142 and 152 of the current sensor 10F to the magnetically sensitive surface. Alternatively, the wiring arranged on the substrate 200 may function as the conductor plate 170. The conductor plate 170 may also function as a shield relative to other wiring. The main body 141 and the magnetoelectric conversion element 20b are both included in the sealing portion 130, and their relative positions are not easily changed. Even if the relative positions of the conductor plate 170, the current conductor 140, and the magnetoelectric conversion element 20b in the XY plane direction are offset, the eddy current generated in the conductor plate 170 is generated at the position corresponding to the current conductor 140 regardless of the position of the conductor plate 170. Therefore, compared with the situation where the current conductor 140 as a whole and the magnetoelectric conversion elements 20a and 20b are present outside the sealing part 130 and the relative positions of the current conductor 140 and the magnetoelectric conversion elements 20b are easily changed due to installation offset, even if the conductor part 170 is not in the sealing part, the way in which the current conductor 140 and the magnetoelectric conversion elements 20a and 20b are included in the sealing part 130 can suppress the deviation in sensitivity suppression caused by eddy currents.

[0360] Figure 19The current sensor 10G shown is different from the current sensor 10F in which the conductor plate 170 is built into the substrate 200 in that the conductor plate 170 is provided on the surface layer of the substrate 200. Alternatively, the wiring arranged on the substrate 200 may function as the conductor plate 170. Even if the conductor plate 170 is exposed on the surface of the substrate 200, it is unlikely to become a problem as long as the CTI (Comparative Tracking Index) and the creepage distance relative to the surface of the substrate 200 (semiconductor package substrate) are conditions where creepage discharge is unlikely to occur. The conductor plate 170 may also function as a shielding member relative to other wiring. Distance z b It is the distance from the bottom surface of the terminal parts 142 and 152 of the current sensor 10F to the magnetic sensitive surface.

[0361] Figure 20 The illustrated current sensor 10H differs from the current sensor 10E in that the conductor plate 170 is disposed on the top surface 130e of the sealing portion 130, exposed from the sealing portion 130. This differs from the current sensor 10E in that the conductor plate 170 is disposed on the circuit surface 100a of the signal processing IC 100, interposed through the insulating member 162. The conductor plate 170 can function as a heat sink. The conductor plate 170 can be made of copper or an aluminum alloy. This structure improves the frequency characteristics of the current sensor 10H and promotes heat dissipation from the top surface of the sealing portion 130, thereby suppressing overheating of the current sensor 10H associated with flowing large currents through the main body 141.

[0362] While the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It is obvious to those skilled in the art that various modifications or improvements can be made to the above embodiments. It is obvious from the claims that such modifications or improvements are also within the technical scope of the present invention.

[0363] It should be noted that the order in which actions, processes, steps, and stages, etc., in the apparatus, system, program, and method described in the claims, specifications, and drawings may be performed in any order, unless otherwise expressly stated as "before," "prior to," or the like, and unless the output of an earlier process is used in a later process. Even if the flow of actions in the claims, specifications, and drawings is described using phrases such as "first" or "next," for convenience, it does not necessarily mean that the actions must be performed in that order.

Claims

1. A current sensor comprising: At least one magnetoelectric conversion unit; a current conductor through which a measurement current measured by the at least one magnetoelectric converter flows; a signal processing unit configured to process a signal output from the at least one magnetoelectric converter; a conductor plate, at least a portion of which overlaps with the current conductor when viewed from above; as well as a sealing portion that seals at least the at least one magnetoelectric converter, the current conductor, and the signal processing portion; The current conductor includes a main body portion that at least partially surrounds one of the at least one magnetoelectric converter in a plan view, and the main body portion includes a first portion that surrounds at least three side surfaces of the one magnetoelectric converter. When the thickness of the conductor plate is set to u[m], The magnetic permeability of the conductor plate is set to μ t [N / A 2 ], The conductivity of the conductor plate is set as σ t [S / m], The magnetic permeability of the current conductor is set to μ b [N / A 2 ], Let the conductivity of the current conductor be σ b [S / m], The shortest distance between the center of the magnetic sensitive surface of the at least one magnetoelectric converter and the surface of the current conductor in a plan view is defined as h [m], The maximum width of the first part when looking down is set to w b [m], The shorter distance in the thickness direction between the conductor plate and the current conductor and the distance between the conductor plate and the magnetic sensitive surface of the at least one magnetoelectric converter is defined as z b [m], The narrowest width of the portion of the conductor plate that crosses the at least one magnetoelectric converter in a plan view is defined as w. t [m] case, satisfy [Formula A] Here, [Formula B] (1) and In the case of [Formula C] (2) and In the case of [Formula D] (3) In cases other than (1) and (2), [Formula E] In w t If the time is less than 4 hours, [Formula F] In w t For ≥4h, C w (w t )=1。 2. The current sensor according to claim 1, wherein The current conductor and the conductor plate are non-magnetic bodies.

3. The current sensor according to claim 1, wherein The current conductor and the conductor plate are made of a material containing 50% or more of copper.

4. The current sensor according to claim 2, wherein: The conductivity σ of the conductor plate t [S / m] is 4.6×10 6 <σ t , The thickness u[m] of the conductor plate and the shortest distance h[m] between the center of the magnetic sensitive surface of at least one magnetoelectric converter and the surface of the current conductor satisfy [Formula G] and [Formula H] and satisfy [Formula 1] [Formula J] In w t If the time is less than 4 hours, [Formula K] In w t For ≥4h, C w (w t )=1。 5. The current sensor according to claim 4, wherein The shortest distance h [m] between the center of the magnetic sensitive surface of the at least one magnetoelectric converter and the surface of the current conductor and the narrowest width w of the portion of the conductor plate that crosses the at least one magnetoelectric converter t [m] Satisfaction 5×10 -5 m <h<5×10 -4 m、and 2×10 -3 m<w t <2×10 -2 m, and satisfy [Formula L] The current sensor according to claim 1 , wherein: The conductive plate is not exposed from the surface of the sealing portion but is embedded in the sealing portion.

7. The current sensor according to claim 1, wherein The signal processing unit is an IC chip, ie, a signal processing IC.

8. The current sensor according to claim 7, wherein: The magneto-sensitive surface overlaps with the signal processing IC in a plan view, and an electrical connection between the signal processing IC and the at least one magneto-electric converter does not span the current conductor.

9. The current sensor according to claim 8, wherein: The at least one magnetoelectric conversion unit includes at least one magnetoelectric conversion element independent of the signal processing IC. The magnetosensitive surface of the at least one magnetoelectric conversion element protrudes from the circuit surface of the signal processing IC.

10. The current sensor according to claim 8, wherein The surface of the signal processing IC opposite to the circuit surface is arranged on the surface of the conductor plate facing the current conductor.

11. The current sensor according to claim 7, wherein: The at least one magnetoelectric conversion unit is built into the signal processing IC. The magnetosensitive surface of the at least one magnetoelectric converter does not protrude from the circuit surface of the signal processing IC.

12. The current sensor according to claim 7, wherein: The surface of the signal processing IC opposite to the circuit surface is arranged on the surface of the current conductor opposite to the surface facing the conductor plate via an insulating member.

13. The current sensor according to claim 12, wherein: The conductive plate is disposed on a surface of the current conductor opposite to a surface on which the signal processing IC is disposed, with an insulating member interposed therebetween.

14. The current sensor according to claim 7, wherein: The conductive plate is disposed on the circuit surface of the signal processing IC via an insulating member.

15. The current sensor according to claim 7, wherein: The conductive plate supports the signal processing IC.

16. The current sensor according to claim 7, wherein: The current conductor has no interface with components connected to the signal processing IC.

17. The current sensor according to claim 1, wherein The at least one magnetoelectric converter is of a longitudinal magnetic field detection type.

18. The current sensor according to claim 1, wherein The conductive plate does not have a hole or a slit that penetrates the conductive plate and at least partially overlaps with the magnetic sensitive surface in a plan view.

19. The current sensor according to claim 1, wherein The current sensor further comprises: a first terminal portion, electrically connected to the current conductor and exposed from a first side surface of the sealing portion; as well as The second terminal portion is exposed from a second side surface of the sealing portion opposite to the first side surface, and outputs a signal output from the signal processing portion.

20. The current sensor according to claim 1, wherein The current conductor includes a first terminal portion exposed from the sealing portion, and the first portion of the current conductor is integrally formed with the first terminal portion.

21. The current sensor according to claim 19, wherein At least a portion of the second terminal portion is formed integrally with the conductor plate.

22. The current sensor according to claim 1, wherein The conductor plate is not sealed in the sealing portion and is electrically insulated from the current conductor and the signal processing portion.

23. A current measuring device comprising: substrate; and The current sensor according to claim 1 is mounted on the substrate. The conductive plate is not exposed from the surface of the sealing portion or the surface of the substrate on which the current sensor is mounted, but is embedded in the sealing portion or the substrate.

24. A current measuring device comprising: substrate; and The current sensor according to claim 1 is mounted on the substrate. The conductive plate is disposed on a substrate on which the current sensor is mounted.

25. A current measuring device comprising: substrate; and The current sensor according to claim 7 is mounted on the substrate. The surface of the signal processing IC opposite to the circuit surface is arranged on the surface of the current conductor facing the conductor plate. The conductive plate is disposed on a substrate on which the current sensor is mounted.

26. The current measuring device according to claim 25, wherein The conductor plate is built into the substrate.

27. The current measuring device according to claim 25, wherein: The conductor plate is mounted on the surface layer of the substrate.

28. The current measuring device according to claim 27, wherein The conductor plate is covered with insulation.

29. The current measuring device according to claim 25, wherein The conductive plate is disposed on a surface of the sealing portion on the circuit surface side of the signal processing IC.

30. A current sensor comprising: At least one magnetoelectric conversion unit; a current conductor through which a measurement current measured by the at least one magnetoelectric converter flows; a signal processing unit configured to process a signal output from the at least one magnetoelectric converter; a conductor plate, at least a portion of which overlaps with the current conductor when viewed from above; as well as The sealing portion seals at least the at least one magnetoelectric conversion portion, the current conductor, and the signal processing portion, wherein: The current conductor is a non-magnetic body, including a main body portion that at least partially surrounds one of the at least one magnetoelectric converter when viewed from above, and the main body portion includes a first portion that surrounds at least three side surfaces of the one magnetoelectric converter. When the thickness of the conductor plate is set to u[m], The shortest distance between the center of the magnetic sensitive surface of the at least one magnetoelectric converter and the surface of the current conductor in a plan view is defined as h [m], The maximum width of the first part when looking down is set to w b [m], The shorter distance in the thickness direction between the conductor plate and the current conductor and the distance between the conductor plate and the magnetic sensitive surface of the at least one magnetoelectric converter is defined as z b [m], The narrowest width of the portion of the conductor plate that crosses the at least one magnetoelectric converter in a plan view is defined as w. t [m], And the conductivity of the conductor plate is set as σ t In the case of [S / m], satisfy: 5×10 -5 m<h<5×10 -4 m; 4×10 -4 m<w b <1×10 -2 m; 2.55×10 -4 m<z b <1.96×10 -2 m; 2×10 -3 m<w t <2×10 -2 m; 4.6×10 6 S / m<σ t ; 2×10 -5 m<u<1×10 -3 m。 31. A current sensor comprising: At least one magnetoelectric conversion unit; a current conductor through which a measurement current measured by the at least one magnetoelectric converter flows; a signal processing unit configured to process a signal output from the at least one magnetoelectric converter; a conductor plate, at least a portion of which overlaps with the current conductor when viewed from above; as well as The sealing portion seals at least the at least one magnetoelectric conversion portion, the current conductor, and the signal processing portion, wherein: The current conductor is made of a material containing more than 50% copper, and includes a main body portion that at least partially surrounds one of the at least one magnetoelectric converter when viewed from above, and the main body portion includes a first portion that surrounds at least three side surfaces of the one magnetoelectric converter. When the shortest distance between the center of the magnetic sensitive surface of the at least one magnetoelectric converter and the current conductor is set to h in a plan view, The maximum width of the first part when looking down is set to w b [m], The shorter distance in the thickness direction between the conductor plate and the current conductor and the distance between the conductor plate and the magnetic sensitive surface of at least one magnetoelectric converter is defined as z b [m] case, satisfy [Formula M] 32. A current sensor comprising: At least one magnetoelectric conversion unit; a current conductor through which a measurement current measured by at least one magnetoelectric converter flows; a signal processing unit configured to process a signal output from the at least one magnetoelectric converter; a conductor plate, at least a portion of which overlaps with the current conductor when viewed from above; as well as The sealing portion seals at least the at least one magnetoelectric conversion portion, the current conductor, and the signal processing portion, wherein: The current conductor includes a main body portion that at least partially surrounds one of the at least one magnetoelectric converter in a plan view, and the main body portion includes a first portion that surrounds at least three side surfaces of the one magnetoelectric converter. When the thickness of the conductor plate is set to u[m], The magnetic permeability of the conductor plate is set to μ t [N / A 2 ], Let the conductivity of the current conductor be σ b [S / m], The magnetic permeability of the current conductor is set to μ b [N / A 2 ], The conductivity of the conductor plate is set as σ t [S / m], The shortest distance between the center of the magnetic sensitive surface of the at least one magnetoelectric converter and the current conductor in a plan view is defined as h [m], The maximum width of the first part when looking down is set to w b [m], The shorter distance in the thickness direction between the conductor plate and the current conductor and the distance between the conductor plate and the magnetic sensitive surface of the at least one magnetoelectric converter is defined as z b [m], The narrowest width of the portion of the conductor plate that crosses the at least one magnetoelectric converter in a plan view is defined as w. t [m] case, satisfy [Formula N] Here, [Formula O] (1) and In the case of [Formula P] (2) and In the case of [Formula Q] (3) In cases other than (1) and (2), [Formula R] In w t If the time is less than 4 hours, [Formula S] In w t For ≥4h, C w (w t )=1。

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