Current sensor and current measuring device

Abstract

SOLUTION: A current sensor may include at least one magnetoelectric conversion unit, a current conductor in which a measurement current measured by the magnetoelectric conversion unit flows, and a conductor plate that partly overlaps the current conductor in a plan view. The current conductor includes, in a plan view, a body part at least partly enclosing the one magnetoelectric conversion unit of the at least one magnetoelectric conversion unit, and the body part includes a first section enclosing at least three side surfaces of the one magnetoelectric conversion unit. When it is assumed that u represents the thickness of the conductor plate, μt represents the magnetic permeability of the conductor plate, σt represents the conductivity of the conductor plate, μb represents the magnetic permeability of the current conductor, σb represents the conductivity of the current conductor, h represents the shortest distance between the center of the magneto-sensitive surface of the magnetoelectric conversion unit and the current conductor, in a plan view, wb represents the maximum width of the first section, zb represents the distance between the conductor plate and the current conductor in the thickness direction and the distance between the conductor plate and the magneto-sensitive surface of the magnetoelectric conversion unit whichever is shorter, and in a plan view, wt represents the narrowest width of a section of the conductor plate crossing the magnetoelectric conversion unit, then each value satisfies a prescribed condition.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a current sensor comprising a primary conductor having an opening, a lead frame having a portion overlapping the opening, and a magnetic sensor. Patent Document 2 discloses a current sensor in which a support member for supporting a magnetoelectric conversion element is made of a semiconductor substrate or a metal plate. Patent Document 3 discloses arranging an external current rail at a position opposite the sensor element on a substrate on which a sensor package containing a sensor element is mounted. Patent Documents 4 and 5 disclose that a magnetic sensor is at least partially surrounded by a current conductor. [Prior art document] [Patent] [Patent Document 1] Japanese Unexamined Patent Publication No. 2018-36237 [Patent Document 2] Patent No. 7328430 [Patent Document 3] U.S. Patent No. 9,733,280 [Patent Document 4] U.S. Patent Application Publication No. 2022 / 0091161 [Patent Document 5] U.S. Patent Application Publication No. 2015 / 0160272 [Overview of the project] [Problems that the invention aims to solve]

[0003] In current sensors, it is desirable to effectively suppress the effect of the skin effect occurring in the current conductor through which the measured current flows, as this affects the detection accuracy of the current sensor. [Means for solving the problem]

[0004] A current sensor according to one aspect of the present invention includes at least one magnetoelectric conversion unit, a current conductor through which a measured current measured by the at least one magnetoelectric conversion unit flows, a signal processing unit that processes a signal output from the at least one magnetoelectric conversion unit, a conductor plate that at least partially overlaps the current conductor in a plan view, and a sealing unit that at least seals the at least one magnetoelectric conversion unit, the current conductor, and the signal processing unit. The current conductor may include a main body portion that at least partially surrounds one of the at least one magnetoelectric conversion units in a plan view, and the main body portion may include a first portion that at least surrounds three side surfaces of the one magnetoelectric conversion unit. The thickness of the conductor plate is u [m], the magnetic permeability of the conductor plate is μ t [N / A 2 , the conductivity of the conductor plate is σ t [S / m], the magnetic permeability of the current conductor is μ b [N / A 2 , the conductivity of the current conductor is σ b [S / m], in a plan view, the shortest distance between the center of the magnetosensitive surface of the at least one magnetoelectric conversion unit and the surface of the current conductor is h [m], in a plan view, the maximum width of the first portion is w b [m], in the thickness direction, 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 of the at least one magnetoelectric conversion unit is z b [m], in a plan view, the narrowest width in the portion of the conductor plate that crosses the at least one magnetoelectric conversion unit is w t [m], when this is the case,

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[0005] In the current sensor, the current conductor and the conductor plate may be made of non-magnetic material.

[0006] In any of the above-mentioned current sensors, the current conductor and the conductor plate may be made of a material containing 50% or more copper.

[0007] In any of the above current sensors, the conductivity σ of the conductor plate t [S / m] is 4.6 × 10 6 <σ t The thickness of the conductor plate is u[m] and the shortest distance h[m] between the center of the magnetosensitive surface of the at least one magnetoelectric conversion unit and the surface of the current conductor is,

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[0008] In any of the current sensors, the shortest distance h [m] between the center of the magnetic surface of the at least one magnetoelectric conversion unit and the surface of the current conductor, and the narrowest width w of the conductor plate in the portion that crosses the at least one magnetoelectric conversion unit. t [m] 5 x 10 -5 m <h<5×10 -4 m, and 2 x 10 -3 m <w t <2×10 -2 m, Satisfying the conditions,

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[0009] In any of the current sensors, the conductive plate may be embedded within the sealing portion without being exposed from the surface of the sealing portion.

[0010] In any of the current sensors, the signal processing unit may be a signal processing IC, which is an IC chip.

[0011] In any of the current sensors, the magnetic surface overlaps with the signal processing IC in a plan view, and the electrical connection between the signal processing IC and the at least one magnetoelectric conversion unit does not need to cross the current conductor.

[0012] In any of the current sensors, the at least one magnetoelectric conversion unit may include at least one magnetoelectric conversion element separate from the signal processing IC. The magnetosensitive surface of the at least one magnetoelectric conversion element may protrude from the circuit surface of the signal processing IC.

[0013] In any of the current sensors, the side opposite to the circuit side of the signal processing IC may be positioned on the side of the conductor plate facing the current conductor.

[0014] In any of the current sensors, the at least one magnetoelectric conversion unit may be built into the signal processing IC. The magnetosensitive surface of the magnetoelectric conversion unit does not need to protrude from the circuit surface of the signal processing IC.

[0015] In any of the current sensors, the side of the signal processing IC opposite to the circuit side may be arranged on the side of the current conductor opposite to the side facing the conductor plate, via an insulating member.

[0016] In any of the current sensors, the conductor plate may support the signal processing IC.

[0017] In any of the current sensors, the current conductor does not need to have an interface between members that lead to the signal processing IC.

[0018] In any of the current sensors, at least one magnetoelectric conversion unit may be of the longitudinal magnetic field detection type.

[0019] In any of the current sensors, the conductor plate does not need to have a hole or slit penetrating it at a position where, in a plan view, at least a portion of it overlaps with the magnetic surface.

[0020] Any of the current sensors may further include a first terminal portion that is electrically connected to the current conductor and exposed from the first side surface of the sealing portion, and a second terminal portion that is exposed from the second side surface of the sealing portion facing the first side surface and outputs a signal output from the signal processing unit.

[0021] In any of the current sensors, the current conductor includes 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.

[0022] In any of the current sensors, the second terminal portion may be integrally formed with the conductor plate in at least a portion thereof.

[0023] In any of the current sensors, the conductive plate may not be sealed within the sealing portion and may be electrically insulated from the current conductor and the signal processing unit.

[0024] A current measuring device according to one aspect of the present invention may comprise a substrate and a 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.

[0025] A current measuring device according to one aspect of the present invention may comprise a substrate and a current sensor mounted on the substrate. The conductive plate may be arranged on the substrate on which the current sensor is mounted.

[0026] A current measuring device according to one aspect of the present invention may comprise a substrate and a current sensor mounted on the substrate. The side of the signal processing IC opposite to the circuit side may be positioned on the side of the current conductor facing the conductor plate. The conductor plate may be positioned on the substrate on which the current sensor is mounted.

[0027] In the current measuring device, the conductor plate may be embedded in the substrate.

[0028] In any of the current measuring devices, the conductor plate may be mounted on the surface layer of the substrate.

[0029] In any of the above-mentioned current measuring devices, the conductor plate may be covered with an insulator.

[0030] In any of the current measuring devices, the conductor plate may be placed on the circuit-side surface of the signal processing IC in the sealing portion.

[0031] A current sensor according to one aspect of the present invention may comprise: at least one magnetoelectric conversion unit; a current conductor through which a measurement current measured by the at least one magnetoelectric conversion unit flows; a signal processing unit for processing a signal output from the at least one magnetoelectric conversion unit; a conductor plate that overlaps the current conductor in at least a portion in a plan view; and a sealing portion that seals at least the at least one magnetoelectric conversion unit, the current conductor, and the signal processing unit. The current conductor is a nonmagnetic material and includes a main body portion that, in a plan view, partially surrounds at least one of the at least one magnetoelectric conversion unit, and the main body portion may include a first portion that surrounds at least three sides of the one magnetoelectric conversion unit. The thickness of the conductor plate is u [m], the shortest distance between the center of the magnetosensitive surface of the at least one magnetoelectric conversion unit and the current conductor in a plan view is h [m], and the maximum width of the first portion in a plan view is w b [m], z is the shorter of the distance between the conductor plate and the current conductor in the thickness direction, and the distance between the conductor plate and the magnetosensitive surface of the at least one magnetoelectric conversion unit. b [m], in a plan view, the narrowest width in the portion of the conductor plate that crosses the at least one magnetoelectric conversion section is w t [m], the conductivity of the conductor plate is σ t If we use [S / m], 5 x 10 -5 m <h<5×10 -4 m, 4 x 10 -4 m <w b <1×10 -2 m, 2.55 × 10 ―4 m <z b <1.96 × 10 -2 m, 2 x 10 -3 m <w t <2×10 -2 m, 4.6 × 10 6 S / m<σ t , 2 x 10 -5 m <u<1×10 -3 m, It may satisfy the following conditions.

[0032] A current sensor according to one aspect of the present invention may comprise: at least one magnetoelectric conversion unit; a current conductor through which a measurement current measured by the at least one magnetoelectric conversion unit flows; a signal processing unit for processing a signal output from the at least one magnetoelectric conversion unit; a conductor plate that overlaps the current conductor in at least a portion in a plan view; and a sealing unit that seals at least the at least one magnetoelectric conversion unit, the current conductor, and the signal processing unit. The current conductor is made of a material containing 50% or more copper and includes a main body that in a plan view partially surrounds at least one of the at least one magnetoelectric conversion unit, and the main body may include a first portion that surrounds at least three sides of the one magnetoelectric conversion unit. In a plan view, the shortest distance between the center of the magnetosensitive surface of the at least one magnetoelectric conversion unit and the current conductor is h, and in a plan view, the maximum width of the first portion is w b The shorter of the distance between the conductor plate and the current conductor in the thickness direction, and the distance between the conductor plate and the magnetosensitive surface of the at least one magnetoelectric conversion unit, is z b In that case,

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[0033] A current sensor according to one aspect of the present invention may comprise: at least one magnetoelectric conversion unit; a current conductor through which a measurement current measured by the at least one magnetoelectric conversion unit flows; a signal processing unit for processing a signal output from the at least one magnetoelectric conversion unit; a conductor plate that overlaps the current conductor in at least a portion in a plan view; and a sealing portion that seals at least the at least one magnetoelectric conversion unit, the current conductor, and the signal processing unit. The current conductor includes a main body portion that, in a plan view, partially surrounds at least one of the at least one magnetoelectric conversion unit, and the main body portion may include a first portion that surrounds at least three sides of the one magnetoelectric conversion unit. The thickness of the conductor plate is u [m], and the permeability of the conductor plate is μ t [N / A 2 ], the conductivity of the current conductor is σ b [S / m], the permeability of the current conductor is μ b [N / A2 ], the conductivity of the conductor plate is σ t [S / m], in plan view, the shortest distance between the center of the magnetosensitive surface of the at least one magnetoelectric conversion unit and the current conductor is h [m], and in plan view, the maximum width of the first part is w b [m], z is the shorter of the distance between the conductor plate and the current conductor in the thickness direction, and the distance between the conductor plate and the magnetosensitive surface of the at least one magnetoelectric conversion unit. b [m], in a plan view, the narrowest width in the portion of the conductor plate that crosses the at least one magnetoelectric conversion section is w t If we use [m],

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[0034] It should be noted that the above summary of the invention does not enumerate all of its features. Furthermore, subcombinations of these features may also constitute an invention. [Brief explanation of the drawing]

[0035] [Figure 1A] This is a schematic plan view of the current sensor 10 according to this embodiment, as seen from the ceiling side (Z-axis direction). [Figure 1B] Figure 1A is a cross-sectional view of the current sensor 10 along line AA. [Figure 2]This figure shows an example of frequency dependence, illustrating the relationship between the sensitivity fluctuations of a magnetoelectric conversion element and the frequency of the current flowing through a current conductor. [Figure 3] This figure shows an example of the relationship between the sensitivity fluctuation of a magnetoelectric conversion element surrounded on three sides by a current conductor and the distance between the current conductor and the conducting plate. [Figure 4] This figure shows an example of the relationship between the sensitivity fluctuation of one magnetoelectric conversion element and the distance between the current conductor and the conducting plate when current detection is performed based on the difference in output between two magnetoelectric conversion elements. [Figure 5] This figure shows an example of a graph illustrating the relationship between sensitivity fluctuations and frequency, which are derived from equation (3). [Figure 6] This figure shows an example of simulation results when the vertical axis represents the sensitivity variation of a magnetoelectric conversion element at a frequency of 10 MHz, and the horizontal axis represents the conductor width. [Figure 7] This figure shows the relationship between the sensitivity fluctuation of the magnetoelectric conversion element and the distance between the current conductor and the conducting plate. [Figure 8A] This diagram illustrates the distance zb when the magnetosensitive surface of the magnetoelectric conversion element is located lower than the surface of the current conductor facing the signal processing IC. [Figure 8B] This diagram illustrates the distance zb when the magnetosensitive surface of the magnetoelectric conversion element is located higher than the surface of the current conductor facing the signal processing IC 100. [Figure 9] This figure shows the relationship between the sensitivity variation of the magnetoelectric conversion element and the distance zb. [Figure 10] This is a diagram illustrating the definitions of parameters related to coils and conductors. [Figure 11] This figure shows the relationship between the sensitivity fluctuation rate due to eddy currents and the conductivity of the conductive plate. [Figure 12] This figure shows a graph illustrating the relationship between the normalized sensitivity fluctuation rate, which depends on the positional relationship in the thickness direction of the conductor plate, current conductor, and magnetoelectric conversion element, and the width of the conductor plate. [Figure 13] This is a cross-sectional view of the current sensor 10A in a modified example, corresponding to line AA in Figure 1A. [Figure 14]This is a cross-sectional view of the current sensor 10B according to a modified example, corresponding to line AA in Figure 1A. [Figure 15] This is a cross-sectional view of the current sensor 10C according to a modified example, corresponding to line AA in Figure 1A. [Figure 16] This is a cross-sectional view of the current sensor 10D in a modified example, corresponding to line AA in Figure 1A. [Figure 17] This is a cross-sectional view of the current sensor 10E according to a modified example, corresponding to line AA in Figure 1A. [Figure 18] This is a cross-sectional view of the current sensor 10F according to a modified example, corresponding to line AA in Figure 1A. [Figure 19] This is a cross-sectional view of the current sensor 10G according to a modified example, corresponding to line AA in Figure 1A. [Figure 20] This is a cross-sectional view of the current sensor 10H according to a modified example, corresponding to line AA in Figure 1A. [Modes for carrying out the invention]

[0036] The present invention will be described below through embodiments of the invention, but these embodiments are not intended to limit the invention as defined in the claims. Furthermore, not all combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0037] Figures 1A and 1B show the internal configuration of a semiconductor package that functions as a current sensor 10 according to this embodiment. Figure 1A is a schematic plan view of the current sensor 10 according to this embodiment, viewed from the top side (Z-axis direction). Figure 1B is a cross-sectional view of the current sensor 10 shown in Figure 1A, along line AA.

[0038] In Figure 1A, the coordinate system is defined as follows: the X-axis is parallel to the plane of the paper and runs from bottom to top; the Y-axis is parallel to the plane of the paper and runs from right to left; and the Z-axis is perpendicular to the plane of the paper and runs from back to front. Any one of the X, Y, or Z axes is perpendicular to the other axes.

[0039] The current sensor 10 comprises a signal processing IC 100, magnetoelectric conversion elements 20a and 20b, a current conductor 140 through which the measured current flows, a lead frame 150 on the signal terminal side, and a sealing portion 130.

[0040] 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 within the sealing portion 130 and partially surrounds the magnetoelectric conversion elements 20a and 20b. The first portion 1410 of the main body portion 141 may surround at least three sides of the magnetoelectric conversion element 20a in a plan view. The magnetoelectric conversion element 20a may be surrounded at least by the inner sides 1410a, 1410b, and 1410c of the first portion 1410. In Figure 1A, a portion of the magnetoelectric conversion element 20a is also surrounded by the inner side 1410d of the first portion 1410 in a plan view, but the magnetoelectric conversion element 20a may not be surrounded by the inner side 1410d of the first portion 1410 in a plan view.

[0041] A measurement current flows through the terminal portion 142 and the main body portion 141. The pair of terminals 142a and 142b are physically integrated with the main body portion 141 and are exposed outside the sealing portion 130. By physically integrating the pair of terminals 142a and 142b with the main body portion 141, a decrease in reliability due to heat generation of the current conductor 140 can be suppressed. In Figure 1A, 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.

[0042] The current conductor 140 does not need to be manufactured in the form of a lead frame in which multiple body portions 141 and terminal portions 142 are connected as a single metal plate; it may be manufactured using individual metal parts.

[0043] The lead frame 150 includes a main body 151 and a terminal portion 152. The terminal portion 152 includes a plurality of terminals 152a. The main body 151 is an example of a conductor plate that overlaps with the current conductor 140 in plan view, at least in part. The main body 151 is sealed within the sealing portion 130 and supports the signal processing IC 100 with the first surface 151a of the current conductor 140 facing the main body 141. The surface of the main body 151 that supports the signal processing IC 100 and is opposite to the first surface 151a of the current conductor 140 facing the main body 141 is the second surface 151b of the main body 151. Some of the plurality of terminals 152a may be physically integrally formed with the main body 151. At least a portion of each of the plurality of terminals 152a is exposed outside the sealing portion 130. The lead frame 150 is an example of a second lead frame. The lead frames 140 and 150 may be made of a conductive material mainly composed of copper.

[0044] A conductor plate that overlaps with the current conductor 140 in a plan view may overlap with the main body portion 141 of the current conductor 140 in a plan view.

[0045] In Figure 1A, the conductor plate is part of the main body 151 of the lead frame 150, but the conductor plate may be made of a separate metal plate from the lead frame 150. The conductor plate may be made of a non-magnetic material. The conductivity of the conductor plate is 4.6 × 10⁻⁶. 6 The conductive plate may be made of a material with a density of S / m or greater. For example, the conductive plate may be made of a material containing 50% or more copper. The conductive plate may also be made of graphite. The conductive plate may not be exposed from the surface of the sealing portion 130 and may be built into the sealing portion 130. If the conductive plate is made separately from the lead frame 150, the conductive plate may be provided on the substrate on which the current sensor 10 is mounted. In this case, the conductive plate may not be exposed from the surface of the substrate on which the current sensor 10 is mounted and may be built into the substrate. Alternatively, the conductive plate may be provided on the substrate on which the current sensor 10 is mounted and further covered with an insulating material.

[0046] The pair of terminals 142a and 142b and the multiple terminals 152a are arranged opposite each other via the signal processing IC 100 in a direction (Y-axis direction) that intersects with the thickness direction (Z-axis direction) of the signal processing IC 100. The direction intersecting with the thickness direction may be 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 multiple terminals 152a are exposed from the side surface 130b of the sealing portion 130 that is opposite to the side surface 130a.

[0047] As shown in Figure 1B, the pair of terminals 142a, 142b and the multiple terminals 152a may protrude outward from different heights in the thickness direction of the sealing portion 130 on the opposing sides 130a and side 130b of the sealing portion 130. The side 1521 of the multiple terminals 152a on the same side as the first side 100a of the signal processing IC 100 may be at the same height in the thickness direction (Z-axis direction) of the sealing portion 130 as the side 1421 of the pair of terminals 142a, 142b on the same side as the side opposite to the first side 100a of the signal processing IC 100. Alternatively, the side 1521 of the multiple terminals 152a may be located below the side 1421 of the pair of terminals 142a, 142b in the thickness direction of the sealing portion 130. In other words, in the direction from the first surface 130e of the sealing portion 130 on the first surface 100a side of the signal processing IC to the second surface 130f of the sealing portion 130 on the second surface 151b side of the main body portion 151 of the lead frame 150, the surface 1521 of the multiple terminals 152a and the surface 1421 of the pair of terminals 142a and 142b may be at the same height. Alternatively, the surface 1521 of the multiple terminals 152a may be on the second surface 130f side of the sealing portion 130 than the surface 1421 of the pair of terminals 142a and 142b.

[0048] The current conductor 140 is electrically insulated from the signal processing IC 100. The current conductor 140 does not have an interface that comes into contact with the signal processing IC 100.

[0049] When the current conductor 140 is composed of a lead frame, and the lead frame 140 and the lead frame 150 are arranged overlapping in the thickness direction, a step may be provided in the thickness direction on at least one of the lead frame 140 and the lead frame 150 in order to ensure insulation between the lead frame 140 and the lead frame 150 or the signal processing IC 100.

[0050] The main body portion 141 of the lead frame 140 may be bent within the sealing portion 130 so as to approach the second surface 130f of the sealing portion 130 and connected to the terminal portion 142. The lead frame 140 may be bent and connected to the terminal portion 142 such that the portion of the second surface 141b of the main body portion 141 that is connected to the terminal portion is closer to the second surface 130f of the sealing portion 130 by more than half the thickness of the current conductor 140 than the portion of the second surface 141b of the main body portion 141 that is connected to the first surface 100a, which is the circuit surface of the signal processing IC 100, than the portion of the second surface 141b of the main body portion 141 that is connected to the second surface 130f of the sealing portion 130. The main body portion 141 of the lead frame 140 may be curved within the sealing portion 130 so as to approach the second surface 130f of the sealing portion 130 and connected to the terminal portion 142. The main body portion 141 of the lead frame 140 may be curved by bending.

[0051] In other words, if the main body portion 141 of the lead frame 140 is curved 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 141b of the main body portion 141 of the lead frame 140 on the conductor plate 151 side that is connected to the terminal portion 142 may be on the second surface 130f side of the sealing portion 130 rather than the surface facing the first surface 100a, which is the circuit surface of the signal processing IC 100, and the height difference between the surface facing the first surface 100a, which is the circuit surface of the signal processing IC 100, and the portion connected to the terminal portion 142 may be half or more of the thickness of the lead frame 140.

[0052] The main body portion 151 of the lead frame 150 may be bent within the sealing portion 130 so as to approach the first surface 130e of the sealing portion 130, which is the first surface 100a side of the signal processing IC, and connected to the terminal portion 152. The main body portion 151 of the lead frame 150 may be curved and bent so as to approach the first surface 130e of the sealing portion 130 by more than half of the thickness of the main body portion 151 and connected to the terminal portion 152. The main body portion 151 of the lead frame 150 may be curved by bending.

[0053] In other words, if the main body portion 151 of the lead frame 150 is curved 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 portion 151 of the lead frame 150 that is connected to the terminal portion 152 may be on the side of 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 difference in height between the surface that supports the signal processing IC 100 and functions as a conductor plate and the portion that is connected to the terminal portion 152 may be half or more of the thickness of the main body portion 151 of the lead frame 150.

[0054] The main body portion 141 of the lead frame 140 may be connected to the terminal portion 142 by a step with a shear surface, so as to approach the second surface 130f of the sealing portion 130 within the sealing portion 130. The step provided within the sealing portion 130 of the main body portion 141 of the lead frame 140 for connecting the main body portion 141 of the lead frame 140 to the terminal portion 142 may be 0.6 times or less the thickness of the main body portion 141. Furthermore, the main body portion 151 of the lead frame 150 may be connected to the terminal portion 152 by a step with a shear surface, so as to approach the first surface 130e of the sealing portion 130 within the sealing portion 130. The main body portion 151 of the lead frame 150 may be connected to the terminal portion 152 by a step of 0.6 times or less the thickness of the main body portion 151.

[0055] A pair of terminals 142a and 142b protrude from the side surface 130a towards the negative side in the Y-axis direction and are further bent towards 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 towards the negative side in the Z-axis direction. A pair of terminals 142a and 142b may protrude from the side surface 130a towards the negative side in the Y-axis direction and be further bent towards the positive side in the Z-axis direction. Multiple terminals 152a may protrude from the side surface 130b toward the positive side in the Y-axis direction and be further bent towards the positive side in the Z-axis direction. A pair of terminals 142a and 142b, and multiple terminals 152a, do not have to be bent. That is, a pair of terminals 142a and 142b do not have to protrude from the side surface 130a towards the negative side in the Y-axis direction and be bent towards the positive and negative sides in the Z-axis direction. The multiple terminals 152a protrude from the side surface 130b toward the positive side in the Y-axis direction and do not necessarily need to be bent toward the positive and negative sides in the Z-axis direction.

[0056] The signal processing IC 100 may be fixed to the surface 151a of the main body 151 of the lead frame 150 that supports the signal processing IC 100, via an adhesive layer. The adhesive layer may be a die attach film.

[0057] The current conductor 140 has a slit portion 1411. The current conductor 140 may also have a slit portion 1412. The two slit portions 1411 and 1412 are provided on the main body portion 141 and within the sealing portion 130. In a plan view, the magnetoelectric conversion element 20a is positioned within the slit portion 1411 and is partially surrounded by the current conductor 140. If the current conductor 140 has a slit portion 1412, the magnetoelectric conversion element 20b is positioned within the slit portion 1412 and is partially surrounded by the current conductor 140 in a plan view.

[0058] In other words, the current conductor 140 has a slit portion 1411, forming a first portion that surrounds a part of the magnetoelectric conversion element. The current conductor 140 also has a slit portion 1412, forming a projection 1413 that surrounds at least three sides of the magnetic field conversion element 20b in a plan view. Furthermore, since the slit portions 1411 and 1412 are provided on the main body portion 141, the main body portion 141, the first portion 1410, and the magnetoelectric conversion elements 20a and 20b are contained within the sealing portion.

[0059] In this case, both the main body 141 of the current conductor 140 and the magnetoelectric conversion element 20b are included in the sealing portion 130, and their relative positions are unlikely to change. Even if the relative positions of the conductor plate, which overlaps with the current conductor 140 in a plan view, with respect to the current conductor 140 and the magnetoelectric conversion element 20b shift in the XY plane, the eddy currents generated in the conductor plate will occur at a position corresponding to the current conductor 140, regardless of the position of the conductor plate. Therefore, compared to the case where the current conductor 140 and the magnetoelectric conversion elements 20a and 20b are outside the sealing portion 130 and the relative positions of the current conductor 140 and the magnetoelectric conversion element 20b are likely to change due to mounting misalignment, the configuration in which the main body 141 of the current conductor 140 and the magnetoelectric conversion elements 20a and 20b are included in the sealing portion 130 can suppress variations in sensitivity suppression due to eddy currents.

[0060] By positioning the magnetoelectric conversion element 20a within the slit portion 1411, three sides of the magnetoelectric conversion element 20a may be surrounded by the current conductor 140. That is, the magnetoelectric conversion element 20a is surrounded by at least three surfaces 1410a, 1410b, and 1410c of the current conductor 140. The magnetoelectric conversion element 20a may or may not be further surrounded by a surface 1410d.

[0061] In this way, the current under measurement does not branch, and the current density can be increased in the portion of the current conductor 140 closest to the magnetoelectric conversion element 20a, resulting in increased sensitivity. The magnetoelectric conversion element 20a is an example of at least one magnetoelectric conversion unit.

[0062] By positioning the magnetoelectric conversion element 20b in the slit portion 1412, three sides of the magnetoelectric conversion element 20b may be surrounded by the current conductor 140. That is, the magnetoelectric conversion element 20b may be surrounded by at least the surfaces 1410e and 1410f of the current conductor 140 that define a part of the slit portion 1412, and the surface 1413a of the projection 1413. The magnetoelectric conversion element 20b may or may not be surrounded by the surface 1413b of the projection.

[0063] A conducting plate positioned so as to overlap at least a portion with the current conductor 140 may, in a plan view, overlap at least a portion with the magnetosensitive surface of the magnetoelectric conversion element 20a. A conducting plate positioned so as to overlap at least a portion with the current conductor 140 may, in a plan view, also overlap at least a portion with the magnetosensitive surface of the magnetoelectric conversion element 20b. By arranging the magnetoelectric conversion element 20b and taking the difference between the magnitude of the magnetic field measured by the magnetoelectric conversion element 20a and the magnitude of the magnetic field measured by the magnetoelectric conversion element 20b, the magnetic field due to the measured current can be detected without being affected by a substantially uniform disturbance magnetic field.

[0064] On the other hand, the current conductor 140 does not have to have the slit portion 1412, in which case the projection portion 1413 does not exist. If the current conductor 140 does not have the slit portion 1412, the magnetoelectric conversion element 20b may be surrounded on two sides by the surfaces 1410e and 1410f of the current conductor 140.

[0065] Here, if the current conductor 140 has a slit portion 1412 and the magnetoelectric conversion element 20b is arranged in the slit portion 1412, the current flowing through the projection portion 1413 is weaker than the portion of the current conductor 140 surrounding the magnetoelectric conversion element 20a, so the magnetoelectric conversion element 20b is less susceptible to the skin effect. Similarly, if the current conductor 140 is surrounded on two sides by surfaces 1410e and 1410f, the magnetoelectric conversion element 20b is also less susceptible to the skin effect. Therefore, if the magnetoelectric conversion element 20a satisfies the configuration of the present invention as an example of at least one magnetoelectric conversion part, the effects of the present invention can be achieved.

[0066] The magnetoelectric elements 20a and 20b may be fixed to the circuit surface of the signal processing IC 100 by die bonding and electrically connected to the signal processing IC 100 by wire bonding. That is, the magnetoelectric elements 20a and 20b may be electrically connected to the signal processing IC 100 via multiple wires 22a and 22b. The multiple wires 22a and 22b may be electrically connected to the magnetoelectric elements 20a and 20b and the signal processing IC 100 within the slit portions 1411 and 1412. That is, the multiple wires 22a and 22b may be electrically connected to the magnetoelectric elements 20a and 20b and the signal processing IC 100 without crossing the current conductor 140. By doing so, the magnetic flux linked to the wires can be reduced, making it less likely for induced electromotive force to be generated and facilitating a fast response.

[0067] The magnetoelectric elements 20a and 20b may be electrically connected to the signal processing IC 100 by flip-chip bonding. The magnetoelectric elements 20a and 20b output the signals processed by the signal processing IC 100 to the signal processing IC 100. The magnetoelectric elements 20a and 20b may be configured separately from the signal processing IC 100. That is, the magnetoelectric elements 20a and 20b may be configured on chips other than the chips that make up the signal processing IC 100. The magnetoelectric elements 20a and 20b may be built into the chip that makes up the signal processing IC 100.

[0068] The magnetosensitive surfaces of the magnetoelectric conversion elements 20a and 20b may be positioned so as to overlap with the side surface on which the slit portion 1411 is provided, when viewed from a direction (X-axis or Y-axis) that intersects the thickness direction (Z-axis direction) of the magnetoelectric conversion elements 20a and 20b.

[0069] The thickness of the magnetoelectric conversion elements 20a and 20b is preferably less than twice the length of one side of the magnetic sensing surface, considering the stable mounting of the magnetoelectric conversion elements 20a and 20b and the strengthening of the wire connections. Alternatively, it is more preferable that the thickness is the same as or less than one side of the magnetic sensing surface. Even if the magnetoelectric conversion elements 20a and 20b are not made thick in order to stably position them in this way, by mounting the magnetoelectric conversion elements 20a and 20b on top of the signal processing IC 100, the shorter of the distance zb between the conductor plate 151 and the current conductor 140, and the distance between the conductor plate 151 and the magnetic sensing surfaces of the magnetoelectric conversion elements 20a and 20b, as described later, can be appropriately adjusted. Similarly, adjustment can be easily made by integrating the magnetoelectric conversion elements 20a and 20b into the signal processing IC 100.

[0070] The signal processing IC 100 is electrically connected to multiple terminals 152a via wire 108. Wires 22 and 108 may be made of a conductive material mainly composed of Au, Ag, Cu, or Al.

[0071] The magnetoelectric conversion elements 20a and 20b may protrude from the first surface 100a of the signal processing IC 100 such that, in a side view, the magnetosensitive surfaces of the magnetoelectric conversion elements 20a and 20b overlap with the main body 141 of the current conductor 140. This can increase the sensitivity of the magnetoelectric conversion elements 20a and 20b.

[0072] The magnetoelectric conversion elements 20a and 20b detect a magnetic field in a specific direction that changes according to the measured current flowing through the current conductor 140, and the signal processing IC 100 amplifies the signal according to the magnitude of the magnetic field and outputs the amplified signal via terminal 152a. The magnetoelectric conversion elements 20a and 20b are made of compound semiconductors formed on a GaAs substrate and may be chips cut into a square or rectangular shape when viewed from the Z-axis direction.

[0073] The magnetoelectric conversion elements 20a and 20b may have a substrate made of silicon or a compound semiconductor and a magnetoelectric conversion unit provided on the substrate. The thickness of the substrate is adjusted by polishing the surface on the negative side in the Z-axis direction. Since the magnetic field in the Z-axis direction will be 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 conversion elements 20a and 20b. That is, the magnetoelectric conversion elements 20a and 20b may have a longitudinal magnetic field detection type magnetoelectric conversion unit. Furthermore, if the magnetoelectric conversion elements 20a and 20b are positioned to detect a magnetic field in any one axis direction on the XY plane, for example, if they are positioned 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 conversion elements 20a and 20b. More specifically, they may be positioned so as to overlap the main body 141 of the current conductor 140 in a plan view from the Z-axis direction.

[0074] 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 made 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 arranged. In this embodiment, the circuit surface is the first surface 100a, which corresponds to the top surface of the semiconductor package constituting the signal processing IC 100. The first surface 100a is an example of the circuit surface of the signal processing IC 100. The signal processing circuit processes an output signal corresponding to the magnitude of the magnetic field output from the magnetoelectric conversion elements 20a and 20b. Based on the output signal, the signal processing circuit corrects the measured current flowing through the current conductor 140 and outputs an output signal indicating an accurate current value via terminal 152a. The signal processing circuit reduces noise components contained in the output signals of magnetoelectric conversion element 20a and magnetoelectric conversion element 20b based on the difference between the output signals of magnetoelectric conversion element 20a and magnetoelectric conversion element 20b, amplifies the output signals of magnetoelectric conversion element 20a and magnetoelectric conversion element 20b with reduced noise components, calculates the current value of the measured current based on the amplified output signals, and outputs an output signal indicating the current value.

[0075] In this embodiment, an example is described in which the current sensor 10 includes two magnetoelectric conversion elements 20a and 20b as a magnetoelectric conversion unit. However, the current sensor 10 only needs to have at least one magnetoelectric conversion element. The at least one magnetoelectric conversion element is, for example, magnetoelectric conversion element 20a.

[0076] 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 wires 22 and 108 with a molding resin. The molding resin is, for example, an epoxy-based thermosetting resin with silica added, and may be molded into a semiconductor package using a transfer mold. As will be described later, the sealing portion 130 may or may not seal the conductor plate that overlaps with the current conductor 140 in a plan view, or it may not.

[0077] The measured current flows from terminal 142a of the current conductor 140, sequentially through the part of the main body 141 closest to the magnetoelectric conversion element 20a, and to terminal 142b. The direction of current flow is bent in approximately opposite directions, and the current path does not branch. As a result, the current flows around the magnetoelectric conversion element 20a without dispersion, thereby enhancing sensitivity and the skin effect suppression effect, as will be described later. In one example, the current sensor 10 can steadily supply a measured current of up to 120A, and instantaneously, it can supply currents exceeding 400A. However, assuming a uniform temperature, the current path does not depend on the current value, so the current value has almost no effect on the characteristics of the current sensor 10, which will be explained later.

[0078] Furthermore, in this embodiment, an example in which the main body portion 151 of the lead frame 150 is a conductor plate 151 will be described based on Figures 1A and 1B.Hereafter, unless otherwise specified, when simply referred to as the main body portion 141, it refers to the portion of the current conductor 140 that is included in the sealing portion, based on Figures 1A and 1B.In this embodiment, in the current sensor 10 configured as described above, the skin effect occurring in the current conductor 140 is effectively suppressed by eddy currents generated in the conductor plate 151.In a plan view, the conductor plate 151 does not have holes or slits penetrating the conductor plate 151 at positions that overlap with the magnetosensitive surfaces of the magnetoelectric conversion elements 20a and 20b.This makes it possible to effectively generate eddy currents in the conductor plate 151.

[0079] Figure 2 shows an example of frequency dependence, illustrating the relationship between the sensitivity fluctuation of the magnetoelectric conversion element 20a and the frequency of the current flowing through the current conductor 140.

[0080] Figure 2 shows the frequency dependence of the sensitivity of the magnetoelectric conversion element 20a in a configuration where the conductor plate 151 is not positioned opposite the main body 141 (tabless configuration), and the frequency dependence of the sensitivity of the magnetoelectric conversion element 20a depending on 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 b It is 3.5 mm.

[0081] In Figure 2, the line where there is no sensitivity fluctuation even when the current frequency is varied, that is, the portion where the sensitivity fluctuation value is greater than 0 dB, represents the portion where the sensitivity of the magnetoelectric conversion element 20a increases due to the skin effect of the main body 141. In other words, due to the skin effect, more current flows near the edges than near the center when viewed in cross-section of the main body 141, making it easier for the magnetoelectric conversion element 20a to detect the current flowing through the main body 141, and thus increasing the sensitivity of the magnetoelectric conversion element 20a. The portion where the sensitivity fluctuation value is lower than 0 dB represents the portion where the skin effect of the main body 141 is suppressed by the eddy currents of the conductor plate 151, and the increase in sensitivity of the magnetoelectric conversion element 20a is suppressed. If the effect of the skin effect of the main body 141 can be completely canceled out by the eddy currents of the conductor plate 151, the sensitivity fluctuation associated with frequency fluctuation will be 0 dB. However, as the influence of eddy currents in the conductive plate 151 increases, the influence of eddy currents increases as the frequency of the measured current flowing through the current conductor 140 increases. Therefore, when the frequency of the measured current is high, the decrease in the sensitivity of the power conversion element 20a becomes greater.

[0082] As shown in Figure 2, in the tabless configuration (where the current sensor 10 does not have a conductor plate 151), the sensitivity of the magnetoelectric conversion element 20a increases as the frequency of the current increases. In the configuration where the conductor plate 151 is present, the increase in sensitivity of the magnetoelectric conversion element 20a can be suppressed by the influence of eddy currents generated in the conductor plate 151. However, as the distance between the conductor plate 151 and the main body 141 decreases, the magnetoelectric conversion element 20a becomes more susceptible to the influence of eddy currents generated in the conductor plate 151. If the distance between the conductor plate 151 and the main body 141 is made too short, for example to 0.06 mm, the sensitivity of the magnetoelectric conversion element 20a decreases significantly when the frequency of the measured current flowing through the current conductor 140 is high.

[0083] Figure 3 shows an example of the relationship between the sensitivity fluctuation of the magnetoelectric conversion element 20a, which is surrounded on three sides by the main body 141 as shown in Figure 1A, and the distance between the main body 141 and the conductor plate 151, in a plan view. Figure 4 shows an example of the relationship between the sensitivity fluctuation when current detection is performed based on the difference between the output of the magnetoelectric conversion element 20a and the output of the magnetoelectric conversion element 20b, and the distance between the main body 141 and the conductor plate 151.

[0084] In Figures 3 and 4, the conductor width w b It is 0.5 mm. In Figures 3 and 4, z e z is the height of the magnetic sensing surface relative to the bottom surface of the main body 141, that is, the second surface 141b of the main body 141 near the magnetoelectric conversion element 20a. When the magnetic sensing surface is at a position higher than the second surface 141b of the main body 141, that is, in the direction away from the conductor plate 151, z e This is expressed as a positive value. Conversely, when the magnetic surface is at a lower position than the second surface 141b of the main body 141, that is, in the direction approaching the conductor plate 151, z e It is expressed as a negative value.

[0085] Comparing Figures 3 and 4, it can be seen that the sensitivity fluctuation characteristics are similar when focusing only on the magnetoelectric conversion element 20a and when focusing on both magnetoelectric conversion elements 20a and 20b together. This is because the polarity of the magnetic field affecting magnetoelectric conversion elements 20a and 20b is reversed, and there is almost no difference between the sensitivity fluctuation of magnetoelectric conversion element 20a and the sensitivity fluctuation when the difference between magnetoelectric conversion elements 20a and 20b is taken. Furthermore, magnetoelectric conversion element 20a is surrounded on three sides by the main body 141, and is greatly affected by the magnetic field generated when current flows through the current conductor 140. It is also greatly affected by the skin effect in the current conductor 140 and the eddy currents in the conductor plate 151, resulting in a greater sensitivity fluctuation than that of magnetoelectric conversion element 20b. Therefore, the sensitivity variation obtained by taking the difference between magnetoelectric conversion elements 20a and 20b behaves similarly to the sensitivity variation of magnetoelectric conversion element 20a, and can be represented by magnetoelectric conversion element 20a when multiple magnetoelectric conversion elements are present. Below, we will explain focusing on the sensitivity variation of magnetoelectric conversion element 20a.

[0086] First, we will explain how to express the sensitivity variation of the magnetoelectric conversion element 20a due to the skin effect.

[0087] Outside the conductor, the magnitude of the magnetic field is B. b Let μ0 be the permeability of a vacuum, and I be the current flowing through a conductor. f If r is the distance from the center of the conductor to the center of the current, then the magnetic field B bAccording to Ampère's law, this can be expressed by the following equation:

number

[0088] Therefore, magnetic field B b It can be seen that it is inversely proportional to the distance r. That is, magnetic field B b This is inversely proportional to the distance from the center of the current to the center of the magnetosensitive surface of the magnetoelectric conversion element 20b.

[0089] When a direct current flows through a straight conductor, the distance from the center of the conductor to the center of the magnetosensitive surface of the magnetoelectric conversion element 20a corresponds to the distance r.

[0090] When a high-frequency current flows through a conductor, the skin effect is manifested by an index called skin depth, which indicates how deep the current flows from the surface of the conductor. Skin depth represents the depth to which the magnitude of the current attenuates to 1 / e relative to the conductor surface. If the skin depth is d, the permeability of the conductor is μ, the conductivity is σ, and the frequency is f, then the skin depth can be expressed by the following equation.

number

[0091] Therefore, assuming that an electric current flows from the surface of the conductor to a depth d, the distance r can be derived. Note that for non-magnetic materials such as copper, μ = μ0 = 4π × 10 -7 NA -2 We can assume that this is the case.

[0092] However, this assumption is based on the premise 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 inside the U-shaped portion. That is, the current concentrates on the magnetosensitive surface side of the magnetoelectric conversion element 20a. Therefore, let r be the distance from the center of the conductor to the center of the magnetosensitive surface, and the magnetic field B bWhen we derive (f=0), the magnetic field when a DC current is applied to the conductor becomes smaller than it actually is, and the sensitivity fluctuation of the magnetoelectric conversion element 20a due to frequency fluctuations becomes a large calculation result.

[0093] Therefore, even in the case of a DC current, we assume that the current is shifted by a certain percentage s from the center of the conductor towards the magnetic surface, and express the distance r as follows.

[0094] r = (distance from magnetic surface to conductor surface) + (conductor width) × (1-s) / 2 ... (2)

[0095] From equation (2), when a DC current is applied to a conductor, the distance r from the magnetic surface to the center of the current can be derived, and the magnetic field B acting on the magnetic surface can be calculated. b We can derive (f=0).

[0096] When the current applied to a conductor is changed from a direct current to an alternating current, the current shifts further towards the magnetic surface due to the skin effect.

[0097] Here, let r = (distance from the magnetic surface to the conductor surface) + (skin depth / 2), and the magnetic field B acting on the magnetic surface when AC is applied. skin Derive (f). In this case, B skin (f)>B b In the high-frequency region where (f=0), B skin (f) / B b By setting (f=0), we can derive the sensitivity variation due to the skin effect. On the other hand, B skin (f) b In regions other than the high-frequency region where (f=0), the skin effect does not appear, so B b (f) = B b Let f=0.

[0098] Therefore, the conductor width is w b h is the shortest distance between the center of the magnetic surface and the surface of the current conductor, and σ is the conductivity of the conductor. b ​If the frequency of the current is f and the permeability of the conductor at frequency f is μ, the frequency-induced sensitivity variation due to the skin effect can be expressed by the following equation (3) using the variable s. The variable s indicates that the current is biased from the center of the conductor toward the magnetic surface due to the skin effect.

number

[0099] The denominator of equation (3) represents a quantity proportional to the sensitivity of the magnetoelectric conversion element 20a in the case of high-frequency current, and the numerator represents a quantity proportional to the sensitivity of the magnetoelectric conversion element 20a in the case of direct current.

[0100] Figure 5 is a graph showing the relationship between sensitivity fluctuation and frequency, derived from equation (3). The material of the current conductor is assumed to be copper. One of the graphs shows the conductor width w b The first graph shows the simulation results of calculating the sensitivity variation using the finite element method with a conductor width w of 3.5 mm. The second graph shows the conductor width w of 3.5 mm. b The results of calculating the sensitivity variation using equation (3), with a length of 3.5 mm and s = 0.86, are shown. As shown, the results of calculating the sensitivity variation using equation (3) do not differ significantly from the results of calculating the sensitivity variation using the finite element method. In other words, these calculation results suggest that when a DC current is applied to the conductor, the current is biased from the center of the conductor towards the magnetic surface, and this explains the actual sensitivity variation in this case well.

[0101] By partially surrounding at least three sides of the magnetoelectric conversion element 20a, even if the measured current is DC, 86% of the current density is concentrated near the magnetoelectric conversion element. That is, s is large. As is clear from equation (3), when s is large, the effect of the skin effect is reduced, making it easy to improve the frequency characteristics by eddy currents.

[0102] Figure 6 shows the sensitivity variation of the magnetoelectric conversion element 20a at a frequency of 10 MHz on the vertical axis, and the conductor width w on the horizontal axis. bAn example of the calculation results in this case is shown. One graph shows the simulation results of calculating the sensitivity variation using the finite element method, and the other graph shows the calculation results using equation (3) with s = 0.86. As can be seen, even when the conductor width is varied, the calculation results using the finite element method and the calculation results using equation (3) do not differ significantly. In other words, it can be said that expressing the frequency-induced sensitivity variation due to the skin effect with equation (3) is an effective method.

[0103] Next, we will explain how to express the sensitivity fluctuations of the magnetoelectric conversion element 20a due to eddy currents generated in the conductive plate 151.

[0104] Figure 7 shows the relationship between the sensitivity fluctuation of the magnetoelectric conversion element 20a and the distance between the main body 141 and the conductor plate 151. In Figure 7, the vertical axis represents the conductor width w. b This shows the sensitivity variation when the width 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. In Figure 7, z e This indicates the height from the bottom surface of the main body 141 to the magnetic sensing surface. That is, in Figure 7, the height z e The dependence of the sensitivity fluctuation of the magnetoelectric conversion element 20a on the distance between the main body 141 and the conductor plate 151 is shown accordingly.

[0105] As shown in Figure 7, when the distance between the conductor plate 151 and the main body 141 is short, the height z e When the conductor plate 151 is fixed, the influence of eddy currents generated in the conductor plate 151 becomes greater, and the 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 becomes, and the higher the sensitivity tends to be.

[0106] Here, the shorter of the distance between the conductor plate 151 and the main body 141, and the distance between the conductor plate 151 and the magnetic surface, is z. b This is how it is expressed.

[0107] As shown in Figure 8A, when the magnetosensitive surface 21a of the magnetoelectric conversion element 20a is at a lower position than the surface 141b of the main body 141 facing the signal processing IC 100, the distance zb indicates the distance between the surface 151a of the conductor plate 151 on which the signal processing IC 100 is disposed and the magnetosensitive surface 21a of the magnetoelectric conversion element 20a. On the other hand, as shown in FIG. 8B, when the magnetosensitive surface 21a of the magnetoelectric conversion element 20a is at a position higher than the surface 141b of the main body 141 facing the signal processing IC 100, the distance z b indicates the distance between the surface 151a of the conductor plate 151 on which the signal processing IC 100 is disposed and the surface 141b of the main body 141 of the signal processing IC 100 facing the signal processing IC 100.

[0108] FIG. 9 shows the sensitivity variation of the magnetoelectric conversion element 20a and the distance z b and the relationship therebetween. In FIG. 9, the vertical axis indicates the sensitivity variation when the conductor width w b is 0.5 mm and the frequency f is 10 MHz. The horizontal axis indicates the shorter distance z b between the conductor plate 151 and the main body 141 and the distance between the conductor plate 151 and the magnetosensitive surface. As shown in FIG. 9, even when the height z e from the bottom surface of the main body 141 to the magnetosensitive surface is changed, the sensitivity variation of the magnetoelectric conversion element 20a can be seen to change along a single curve with respect to the distance z b .

[0109] That is, in a region where the current conductor 140 does not exist between the magnetosensitive surface 21a and the conductor plate 151, the influence of the change amount ΔB of the magnetic field due to eddy current depends on the distance between the conductor plate 151 and the magnetosensitive surface 21a. On the other hand, when at least a part of the current conductor 140 exists around between the magnetosensitive surface 21a and the conductor plate 151, since a part of the influence of the eddy current is shielded by the current conductor 140, the influence of the change amount ΔB of the magnetic field due to the eddy current 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 it is effective to use the distance z b as a parameter to evaluate the sensitivity variation of the magnetoelectric conversion element 20a due to eddy current.

[0110] Therefore, if the curve as shown in FIG. 9 is formulated, the sensitivity variation of the magnetoelectric conversion element 20a due to eddy current can be quantitatively evaluated.

[0111] Here, if we pass an electric current through the coil and generate eddy currents in the conductor surrounding the coil, the change in the magnetic field due to the eddy currents is ΔB. z As shown in the reference (Y. Li, T. Theodoulidis, GYTian, ​​Transactions on magnetics, 43, 4010 (2007)), it can be expressed by the following equation (4).

[0112]

number

[0113] Figure 10 is a diagram illustrating the definition of the parameters in equation (4) relating to the coil and conductor (quoted from the reference Y. Li, T. Theodoulidis, GY Tian, ​​Transactions on magnetics, 43, 4010 (2007)). In Figure 10, r1 is the distance from the axial center of coil L to the inner surface of coil L, and r2 is the distance from the axial center of coil L to the outer surface of coil L. Conductor D is composed of the first layer 1, the second layer 2, and the third layer 3, in order of proximity to coil L. z1 is the distance from the surface of coil L facing conductor D to the surface of the first layer 1 facing coil L, and z2 is the distance from the surface of coil L opposite to the surface of the first layer 1 facing coil L. Let the coordinates of the boundary between the first layer 1 and the second layer 2 be -d1, with respect to the surface of the first layer 1 facing coil L, and let the coordinates of the boundary between the second layer 2 and the third layer 3 be -d2, with respect to the surface of the first layer 1 facing coil L. Let the permeability of the first layer 1 be μ1 and its conductivity be σ1. Let the permeability of the second layer 2 be μ2 and its conductivity be σ2. Let the permeability of the third layer 3 be μ3 and its conductivity be σ3. Furthermore, let the current density be i0. Let the permeability of vacuum be μ0. J(x) represents the Bessel function.

[0114] Furthermore, R(a) can be expressed by the following equation when the conductor D is composed of a single layer.

number

[0115] Furthermore, b1 can be expressed by the following equation.

number

[0116] In addition, X(x1,x2) can be expressed by the following equation.

number

[0117] From equation (4) above, the change in magnetic field ΔB z This can be expressed as an integral with respect to a. Then, if we take z as the coefficient of a, the change in the magnetic field ΔB is obtained. z It can be seen that it is proportional to -1 / z. Also, since the magnitude of the eddy current is proportional to the frequency, the change in the magnetic field due to the eddy current, ΔB, can be calculated by setting Ce as the proportionality constant. z This can be approximated as follows:

number

[0118] The change in the magnetic field due to the eddy currents described above (ΔB) z The equation shown is derived assuming the use of an ideal conductor. On the other hand, the eddy currents generated in an actual conductor, i.e., the conductor plate 151, can be reduced by lowering the conductivity of the conductor plate 151, narrowing the width of the conductor plate 151, or reducing the thickness of the conductor plate 151. In other words, if the effect of eddy currents is large, the eddy currents can be suppressed by changing the thickness or conductivity of the conductor plate 151.

[0119] The thickness of the conductor plate 151 needs to consider the penetration depth through which eddy currents can penetrate. That is, depending on whether the thickness of the conductor plate 151 exceeds or does not exceed the penetration depth through which eddy currents can flow, i.e., the skin depth, it is necessary to separately evaluate the change amount ΔB of the magnetic field due to eddy currents. The change amount of the magnetic field due to eddy currents is a coefficient C that corrects the eddy currents generated in the conductor plate 151 when both the conductivity and frequency of the conductor 151 are high, according to conditions such as conductivity and frequency. σt is proportional to.

[0120] Therefore, when the skin depth is d and the thickness of the conductor plate 151 is u, in the low-frequency region, that is, 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 it can be said that the eddy currents are restricted by the thickness of the conductor plate 151. Thus, since the current path is not restricted by the skin depth, the resistance value R of the conductor plate 151 t can be expressed by the following formula.

Equation

[0121] On the other hand, the electromotive force of the eddy currents can be expressed by the following formula using the frequency f of the current flowing through the current conductor 140, where M is the mutual inductance between the current conductor 140 and the conductor plate 151, t is time, and A is a proportionality constant.

Equation

[0122] Therefore, the electromotive force of the eddy currents is proportional to the frequency f of the current flowing through the current conductor 140. Here, the formula (1) representing the skin depth includes the frequency f as a parameter. From formula (1), the skin depth becomes smaller as the frequency increases.

[0123] The resistance value R t and the electromotive force V t From each of the respective formulas, the change amount ΔB of the magnetic field due to eddy currents is represented by the following formula.

Equation

[0124] Therefore, 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 high, it saturates by completely canceling 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 constant value, and 1 is the upper limit as the change rate of the magnetic field. On the other hand, the correction coefficient C representing the effect of suppressing eddy currents σt In the region where the frequency f is high, 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, since the effect of suppressing the eddy current generated in the conductor 151 disappears, the correction coefficient converges to 1. Therefore, since both the change rate of the magnetic field due to the eddy current and the correction coefficient C σt converge to 1, the values are the same as a result.

[0125]

[0126] 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. Let the permeability of the conductor plate 151 be μ t and the conductivity be σ t When the frequency is f, the skin depth d of the conductor plate 151 can be expressed by the following formula.

Equation

[0127] The effective thickness of the conductor plate 151 in the range where the eddy current flows can be assumed to be d. Therefore, the resistance value R of the conductor plate 151 t can be expressed by the following formula using the range w eff where the eddy current flows in the conductor plate 151.

Equation

[0128] The change in the magnetic field due to eddy currents, ΔB, can be expressed by the following equation.

number

[0129] 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 f 1 / 2 and σ t 1 / 2 It is proportional to σ. However, in the region of high frequency f, the effect of suppressing eddy currents generated in the conductor 151 disappears, so the correction coefficient converges to 1. That is, in the region of high frequency f, the magnetic field B generated in the conductor plate 151 is proportional to the thickness u of the conductor plate 151 and σ. t The suppressive effect is eliminated, and the dependence on frequency f disappears.

[0130] Figure 11 shows the correction coefficient C for sensitivity fluctuation rate due to eddy currents. σt The following shows the results obtained using the finite element method regarding the relationship with the conductivity of the conductor plate 151. As described above, in the case of high frequency, the change in the magnetic field ΔB is equal to the conductivity σ of the conductor plate 151. t Because it is proportional to the square root of, the correction coefficient C σt This also depends on this. The graph shown in Figure 11 is a log-log graph. And, when the frequency is 10 MHz, the slope of the line segment L1 is σ t 1 / 2 It is a power of and the graph shown in Figure 11 shows the magnetic field correction coefficient C in the case of high frequency. σt In other words, the effect of suppressing the sensitivity fluctuation rate due to eddy currents is the conductivity σ of the conductor plate 151. t This shows that it is proportional to the square root of .

[0131] On the other hand, in the case of low frequencies, the sensitivity fluctuation rate correction coefficient C σt The conductivity σ of the conductor plate 151 t It is proportional to the first power of . When the frequency is 10 kHz, the slope of the line segment L2 is σ t It is a power of and the graph shown in Figure 11 shows the magnetic field correction coefficient C in the case of low frequency. σt In other words, the effect of suppressing the sensitivity fluctuation rate due to eddy currents is the conductivity σ of the conductor plate 151.t This shows that it is proportional to the first power of .

[0132] Considering the above expression for sensitivity fluctuation rate due to eddy currents, the thickness u of the conductor plate 151 and the conductivity σ of the conductor plate 151 are determined. t Correction term C σt The extent to which sensitivity fluctuations due to eddy currents are suppressed can be expressed by the following case distinctions.

number

number

number

[0133] Here, the constant C is defined to match the results of the finite element method. u<d , C u>d These are C u<d = 4 × 10 -17 , C u>d = 1.8 × 10 -14 That is the case.

[0134] As described above, the conductor plate 151 may be made of the same material as the terminal portion 152. The conductor plate 151 may be a non-magnetic material. For example, the conductor plate 151 may be made of a material containing 50% or more copper. The conductor plate 151 may be made of a separate material from the terminal portion 152. In this case, the conductor plate 151 may be made of, for example, an aluminum alloy that is easy to process and inexpensive. Alternatively, the conductor plate 151 may be made of graphite. If the conductor plate 151 is made of graphite, the conductivity will be 1 × 10⁻⁶. 5 It can be set to a value of such a degree, z bEven when the magnetic field is small, the eddy currents can be controlled to an appropriate size, and good frequency characteristics can be obtained. Furthermore, if a magnetic material is used as the conductor plate 151, the effective resistivity can be increased by considering the permeability in equation (5), and the eddy currents can be suppressed to an appropriate size. In addition, the conductor plate 151 may be made thinner in order to control the eddy currents to an appropriate size. In that case, the conductor plate 151 may be formed using methods such as vapor deposition or plating.

[0135] Width of conductor plate 151 w t When the current becomes smaller, the current path of the eddy current is restricted. The eddy current effectively becomes w eff Assuming that the current flows uniformly within the range of / 2, the resistance value of the conductor plate 151 at that time is R t is, w t <2w eff In this case, it can be expressed by the following equation: width w of the conductor plate 151 t This is the width of the narrowest part of the conductor plate 151 that crosses the portion that overlaps with the magnetoelectric conversion elements 20a and 20b.

number

[0136] Therefore, the change in the magnetic field ΔB can be expressed by the following equation.

number

[0137] Figure 12 is a graph showing the relationship between the normalized sensitivity fluctuation rate, which depends on the positional relationship in the thickness direction of the conductor plate 151, the main body 141 of the current conductor 140, and the magnetoelectric conversion element 20a, and the width of the conductor plate 151. The normalized sensitivity fluctuation rate is normalized to the sensitivity when the width of the conductor plate 151 is sufficiently wide and eddy currents are not limited. As shown in Figure 12, as the width of the conductor plate 151 decreases, the sensitivity fluctuation rate decreases according to equation (6).

[0138] In fact, with respect to the shortest distance h between the center of the magnetosensitive surface of the magnetoelectric conversion element 20a and the main body 141, w effWhen =2h, it can be confirmed that the behavior is similar to that of the line segment shown by the finite element method, as shown in the graph in Figure 12. This reflects that 86% of the current being measured flows towards the part of the main body 141 closer to the magnetic surface, indicating that the density of eddy currents in the conductor plate 151 is high directly below that point.

[0139] Therefore, the correction term C for the width of the conductor plate 151 w (w t ) can be expressed by the following formula.

number

number

[0140] The above explanation describes the correction terms due to the skin effect and the correction terms due to eddy currents.

[0141] Incidentally, 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 both expressed in decibels. In this case, the condition for obtaining an appropriate effect from eddy currents is when the absolute value of the sensitivity fluctuation, which is the skin effect plus eddy currents due to the presence of the conductor plate 151, is small compared to the case where only the sensitivity fluctuation due to the skin effect occurs on the conductor plate 141. This can be expressed by the following equation.

number

number

[0142] In other words, the range in which the decrease in sensitivity due to eddy currents does not exceed twice the increase in sensitivity due to the skin effect is considered to be the range in which the frequency characteristics can be improved by eddy currents. Therefore, the desirable range in which the eddy currents are not too large can be expressed by the following equation.

number

[0143] Next, a range in which the eddy current is not too small and a clear effect exceeding manufacturing variations appears will be described.

[0144] Among manufacturing variations, the most significant factor is considered to be the positional variation in the die bonding process of the magnetoelectric conversion element 20a. The positional variation of a general die bonding apparatus is about ±25 μm. The sensitivity variation due to this positional variation was 0.23% from the results of the finite element method. The range in which the eddy current exhibits an effect exceeding this sensitivity can be expressed by the following formula.

Equation

[0145] That is, it can be expressed by the following formula.

Equation

[0146] There exists a current sensor that follows a measurement current of 5 MHz and is a high-speed response current sensor. As a current sensor that follows a measurement current exceeding 5 MHz, it is required that the sensitivity variation due to the frequency from 5 MHz to 10 MHz be suppressed. That is, a current sensor that follows a measurement current of 10 MHz needs to satisfy the following formula derived by substituting f = 10 MHz into the above formula (7).

Equation

[0147] A current sensor that follows a measurement current of 5 MHz needs to satisfy the following formula derived by substituting f = 5 MHz into the above formula (7).

Equation

[0148] Here, to show a specific example, after setting assumed values for each parameter, a more simplified expression is numerically derived.

[0149] As described above, when the frequency f is 10 MHz, the following equation needs to be satisfied.

Number

[0150] As another specific example, when the conductor plate 151 is a non-magnetic material, a more simplified expression is numerically derived.

[0151] When 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 And can be approximated to be approximately equal.

[0152] Also, when the conductor plate 151 is a non-magnetic material, 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 preferably 20 μm < u < 1 mm.

[0153] In particular, when the thickness u [m] of the conductor plate 151 and σ t [S / m] satisfy

Number

Number

Number

[0154] Also, when the conductor plate 151 is a non-magnetic material, the range of the shortest distance h is 0.05 mm < h < 0.5 mm, and the width w of the main body portion 141 t The range is 2 mm < w tIt is preferably <20 mm. When it is within such a range, [Number] it becomes, and Equation (8) is [Number] expressible as.

[0155] Also, when the conductor plate 151 is a non-magnetic material, further, the maximum conductor width w of the portion surrounding the magnetoelectric conversion element 20a of the main body portion 141 b is in the range of 0.4 mm < w b < 10 mm, and the distance z b is in the range of 0.255 mm < z b < 19.6 mm, which is preferable. When each parameter satisfies the above range, Equation (8) is satisfied.

[0156] Furthermore, when the current conductor 140 and the conductor plate are made of copper, after setting assumptions for each parameter, a further simplified expression is numerically derived.

[0157] Regarding the magnetic permeability of the current conductor 140 and the conductor plate 151, μ b = μ t = 4π × 10 -7 N / A 2 and regarding the conductivity of the current conductor 140 and the conductor plate 151, σ b = σ t = 5.95 × 10 7 S / m can be assumed. Here, 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 C σt 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 range of the width w of the main body portion 141 t is 2 mm < w t < 20 mm, then the correction term C σt and the correction term C wtThe value becomes 1. In this case, the maximum conductor width w of the portion surrounding the magnetoelectric conversion element 20a of the main body 141 b is fixed, and the shorter distance z between the conductor plate 151 and the main body 141 and the distance between the conductor plate 151 and the magneto-sensitive surface b is derived for the relationship with the shortest distance h between the center of the magneto-sensitive surface of the magnetoelectric conversion element 20a and the main body 141. In this case, when the shortest distance h is in the range of 0.05 mm < h < 0.5 mm, the distance z b The lower limit of can be approximately linear with respect to the shortest distance h as a result of numerical calculation. Also, its coefficient can be approximated to be in an inverse proportional relationship with the maximum conductor width w b Therefore, the lower limit of the distance z b preferably satisfies the following equation.

Equation

[0158] Also, the upper limit of the distance z b can be calculated as 19.6 mm. As described above, an approximate formula for the range of the distance z σt and the correction term C wt when both are set to 1 can be derived. b

[0159] ​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, sensitivity cannot be increased. Because sensitivity cannot be increased at low frequencies of the measured current, when sensitivity fluctuations occur, they become large in proportion to the sensitivity at DC current levels. Also, because the magnetoelectric conversion element is not partially surrounded, the current density does not concentrate around the magnetoelectric conversion element when the frequency of the measured current is low. In other words, a relatively uniform current density distribution is achieved. On the other hand, when the frequency is increased, the current path concentrates on the surface of the current conductor due to the skin effect. Therefore, the sensitivity fluctuation due to the skin effect is much larger at high frequencies compared to when the measured current is a DC current. Generally, the frequency dependence of the skin effect and the magnitude of eddy currents generated in a metal plate are not the same. Therefore, when the skin effect is large, it is difficult to cancel it out with eddy currents over a wide frequency range. In Patent Document 2, when the support member supporting the magnetoelectric conversion element is a semiconductor substrate, the skin effect cannot be suppressed, and when the support member is a metal plate, the distance between the primary conductor and the support is small, and the influence of eddy currents is large, so sensitivity decreases as the frequency of the measured current increases. Furthermore, in Patent Document 2, the magnetoelectric conversion element is connected to the metal plate only via an adhesive layer, which limits the upper limit of Zb and makes it prone to excessive eddy current influence. In Patent Document 3, the current rail is placed on a substrate outside the encapsulation, so mounting misalignment easily changes the relative position of the measured current and the sensor element, resulting in large variations in sensitivity. Moreover, because the current conductor is linear, the current path cannot be bent, and the skin effect is very large. Therefore, it is difficult to improve the frequency characteristics over a wide frequency range using eddy currents.

[0160] Patent Document 5 discloses an example in which a magnetoelectric conversion element is surrounded on all four sides by a current conductor, and the current conductor has portions that are close to three sides of the magnetoelectric conversion element and portions that are far from one side of the magnetoelectric conversion element. However, similar to the examples disclosed in Patent Documents 1 and 4, the current density decreases as the current being measured branches. In addition, the resistance value of the portion of the current conductor sandwiched between the magnetoelectric conversion elements is higher than that of the portion far from one side of the magnetoelectric conversion element. Therefore, the amount of current flowing through the portion sandwiched between the magnetoelectric conversion elements decreases, the sensitivity for DC current decreases, and the rate of sensitivity fluctuation tends to increase.

[0161] On the other hand, according to this embodiment, by designing the current sensor 10 to satisfy the above conditions, the skin effect generated in the current conductor 140 can be effectively suppressed by the eddy currents generated in the conductor plate 151.

[0162] The above describes an example where the magnetoelectric conversion elements 20a and 20b are longitudinal magnetic field detection elements. However, the frequency characteristics can be improved using the same principle even if the magnetoelectric conversion elements 20a and 20b are transverse magnetic field detection elements such as ferromagnetic magnetoresistance elements (MR), tunnel magnetoresistance elements (TMR), or vertical Hall elements. In other words, by canceling the skin effect occurring in the main body 141 with eddy currents, a high-speed response of the current sensor 10 can be achieved.

[0163] Next, we will describe some modified versions of the current sensor 10 to which this principle can be applied. The current sensors 10A to 10H shown below differ from the current sensor 10 shown in Figures 1A and 1B in that they utilize magnetoelectric conversion elements embedded in the signal processing IC 100 as magnetoelectric conversion elements 20a and 20b. In each modified version, the magnetoelectric conversion elements 20a and 20b may also be configured separately from the signal processing IC, as shown in Figures 1A and 1B. In Figures 13 to 20, explanations of equivalent configurations among the components indicated by symbols in Figures 1A and 1B will be omitted.

[0164] The current sensor 10A shown in Figure 13 has the same arrangement of components as the current sensor 10, except that the magnetoelectric conversion element 20b (20a) is embedded in the signal processing IC 100. Since the magnetoelectric conversion element 20b (20a) is embedded in the signal processing IC 100, the distance from the conductor plate 151 to the magnetosensitive surface of the magnetoelectric conversion element 20b is shorter than the distance from the conductor plate 151 to the main body 141. Therefore, the distance z b This is the distance from the conductor plate 151 to the magnetosensitive surface of the magnetoelectric conversion element 20b.

[0165] The current sensor 10B shown in Figure 14 differs from the current sensor 10 in that the signal processing IC 100, which has an embedded magnetoelectric conversion element 20b (20a), is positioned on the side 141a opposite to the side 141b of the main body 141 that faces the conductor plate 151. The signal processing IC 100 is positioned on the side 141a of the main body 141 via an insulating member 160. The insulating member 160 may be a die attach film, an insulating plate, or a polymer film. By positioning 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. To avoid discharge due to potential creepage, the insulating member 160 may be positioned so as to protrude from the signal processing IC 100 in a plan view. Even in such a configuration, the conductor plate 151 may be made of the same lead frame 150 as the terminal portion 152.

[0166] The current sensor 10C shown in Figure 15 differs from the current sensor 10B in that the lead frame 150 on the signal terminal side is bent toward the bottom surface 130f of the sealing portion 130, making it a different height from the main body portion 141 of the current conductor 140 in a side view, and a separate conductor plate 170 is placed on the surface of the main body portion 151 of the lead frame 150 toward the surface 130f of the sealing portion 130. The signal processing IC 100 and the magnetoelectric conversion 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 two separate lead frames from the beginning, but may be separated from the same component. Since it is not necessary to overlap the lead frame 140 and the lead frame 150 and seal them with the sealing portion 130, manufacturing is easier and manufacturing costs can be reduced. In addition, the conductor plate 170 can be made of a different material from the lead frame 150. In other words, the conductor plate 170 can be made of a material such as aluminum alloy, which is cheaper than the lead frame 150, has optimal conductivity, and has an optimized shape.

[0167] The current sensor 10D shown in Figure 16 differs from the current sensor 10C in that the conductor plate 170 is placed on the surface 141b of the main body portion 141 of the current conductor 140 via an insulating member 162. Similar to the current sensor 10C, the conductor plate 170 can be made of a different material than the lead frame 150. In other words, the conductor plate 170 can be made of a material that is cheaper than the lead frame 150, has optimal conductivity, and has an optimized shape, such as an aluminum alloy. Furthermore, since the conductor plate 170 is a separate component, there are no constraints on thickness, width, material, etc., making it easier to design the current sensor 10D to improve its frequency characteristics.

[0168] The current sensor 10E shown in Figure 17 differs from the current sensor 10C in that the conductor plate 170 is positioned opposite the magnetic surface of the magnetoelectric conversion element 20b (20a) on surface 100a, which is the circuit surface of the signal processing IC 100, via an insulating member 162. 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. Furthermore, the risk of discharge occurring between the conductor plate 170 and the current conductor 140 is also low. In addition, the distance between the conductor plate 170 and the magnetic surface is distance z b However, regardless of the machining accuracy of the lead frame, the distance z is controlled by the insulating member 162 between the conductor plate 170 and the magnetic surface. b It can be determined precisely.

[0169] The current sensor 10F shown in Figure 18 differs from current sensors 10 to 10E in that the conductor plate 170 is not sealed in 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 positioned on the surface 141b of the main body portion 141 of the current conductor 140, on the surface 130f side which is the bottom surface of the sealing portion 130, via an insulating member 160. The circuit surface 100a of the signal processing IC 100 faces the surface 130f side of the sealing portion 130. In other words, the magnetosensitive 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 land portion 201 that is electrically connected to the terminal portion 142 on the current conductor side, and a land portion 202 that is electrically connected to the terminal portion 152 on the signal terminal side. Furthermore, the substrate 200 incorporates a conductor plate 170 at a position opposite the magnetosensitive surface of the magnetoelectric conversion element 20b (20a). In this configuration, there is no need for a lead frame for positioning the conductor plate 170, nor a dedicated process for positioning the conductor plate 170. Preparation is simple, as it can be done by appropriately setting the layout of the substrate 200. Instead of being incorporated into the substrate 200, the conductor plate 170 may be provided on the surface layer of the substrate 200. If the conductor plate 170 is located on the surface layer of the substrate 200, it may be covered with an insulator such as a resist. This suppresses creepage discharge from the current conductor side terminal portion 142 to the signal terminal side terminal portion 152. The insulator covering the conductor plate 170 may be a high heat dissipation resin. When the conductor plate 170 is positioned on the surface layer of the substrate 200, the distance z bThis is the distance from the bottom surface of the terminals 142 and 152 of the current sensor 10F to the magnetic sensing surface. Wiring arranged on the substrate 200 may function as a conductor plate 170. The conductor plate 170 may function as a shield from other wiring. The main body 141 and the magnetoelectric conversion element 20b are both included in the sealing part 130, and their relative positions do not easily change. Even if the relative positions of the conductor plate 170 and the current conductor 140 or magnetoelectric conversion element 20b in the XY plane are shifted, the eddy currents generated in the conductor plate 170 will occur at the position corresponding to the current conductor 140, regardless of the position of the conductor plate 170. Therefore, compared to the case where the entire current conductor 140 and the magnetoelectric conversion elements 20a and 20b are outside the sealing portion 130, and the relative position of the current conductor 140 and the magnetoelectric conversion elements 20b is prone to change due to mounting misalignment, the configuration in which the current conductor 140 and the magnetoelectric conversion elements 20a and 20b are included in the sealing portion 130, even when the conductor portion 170 is not inside the sealing portion, can suppress variations in sensitivity suppression due to eddy currents.

[0170] The current sensor 10G shown in Figure 19 differs 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. Wiring arranged on the substrate 200 may also 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 be a problem if the conditions for creepage discharge are such that creepage discharge is unlikely to occur with respect to the CTI (comparative tracking index) and creepage distance of the surface of the substrate 200 (semiconductor package substrate). The conductor plate 170 may also function as a shield from other wiring. Distance z b This is the distance from the bottom surface of the terminals 142 and 152 of the current sensor 10F to the magnetic surface.

[0171] The current sensor 10H shown in Figure 20 differs from the current sensor 10E in that the conductor plate 170 is positioned on surface 100a, which is the circuit surface of the signal processing IC 100, via an insulating member 162, in that the conductor plate 170 is positioned on surface 130e, which is the ceiling surface of the sealing portion 130, and is exposed from the sealing portion 130. The conductor plate 170 may function as a heat sink. The conductor plate 170 may be made of copper or an aluminum alloy. With this configuration, the frequency characteristics of the current sensor 10H can be improved, and furthermore, heat dissipation from the ceiling surface of the sealing portion 130 can be promoted, thereby suppressing overheating of the current sensor 10H when a large current is passed through the main body 141.

[0172] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiments. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention.

[0173] It should be noted that the execution order of operations, procedures, steps, and stages in the apparatus, systems, programs, and methods shown in the claims, specifications, and drawings is not explicitly stated as "before," "prior to," etc., and that these can be implemented in any order unless the output of a previous process is used in a later process. Even if the operation flow in the claims, specifications, and drawings is described using phrases such as "first," "next," etc. for convenience, it does not mean that it is essential to perform the operations in that order. [Explanation of Symbols]

[0174] 10 Current Sensor 20a, 20b Magnetoelectric conversion element 22a, 22b wires 100 Signal Processing ICs 108 wires 130 Sealing part 140 Current Conductor 141 Main body 1411, 1412 Slit section 142,152 Terminal section 150 Lead Frames 151,170 Conductor plate 160,162 Insulating material 170 Conductor Plate 200 circuit boards 201,202 Land Department

Claims

1. At least one magnetoelectric conversion unit, A current conductor through which the measurement current measured in the at least one magnetoelectric conversion unit flows, A signal processing unit that processes the signal output from at least one magnetoelectric conversion unit, A conductive plate that overlaps with the current conductor in a plan view, The sealing portion that seals at least one magnetoelectric conversion unit, the current conductor, and the signal processing unit Equipped with, The current conductor includes a main body portion that, in a plan view, partially or completely surrounds one of the at least one magnetoelectric conversion portion, and the main body portion includes a first portion that surrounds at least three sides of the one magnetoelectric conversion portion. The thickness of the aforementioned conductor plate is u [m], The permeability of the conductor plate is μ ｔ [N / A] ２ ], The conductivity of the aforementioned conductor plate is σ ｔ [S / m] The permeability of the current conductor is μ ｂ [N / A] ２ ], The conductivity of the current conductor is σ ｂ [S / m] In a plan view, the shortest distance between the center of the magnetosensitive surface of the at least one magnetoelectric conversion unit and the surface of the current conductor is h [m]. In plan view, the maximum width of the first part is w ｂ [>] The shorter of the distance between the conductor plate and the current conductor in the thickness direction, and the distance between the conductor plate and the magnetosensitive surface of the at least one magnetoelectric conversion unit, is z. ｂ [>], In a plan view, the narrowest width w is at a portion crossing the at least one magnetoelectric conversion portion of the conductor plate. ｔ [m] In that case, [Math A] Satisfying the conditions, Here, [Number B] [Number C] 【Number D】 [Math E] [Number F] This is a current sensor.

2. The current sensor according to claim 1, wherein the current conductor and the conductor plate are made of non-magnetic material.

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 copper.

4. The conductivity σ of the aforementioned conductor plate ｔ [S / m] is 4.6 × 10 ６ <σ ｔ And, The thickness u [m] of the conductor plate and The shortest distance h [m] between the center of the magnetosensitive surface of the at least one magnetoelectric conversion unit and the surface of the current conductor is, [G] and [Number H] Satisfying the following conditions, and, [Mathematics I] Satisfying the conditions, [Number J] [Number K] That is, The current sensor according to claim 2.

5. The shortest distance h [m] between the center of the magnetosensitive surface of the at least one magnetoelectric conversion unit and the surface of the current conductor, and the narrowest width w of the conductor plate in the portion that crosses the at least one magnetoelectric conversion unit. ｔ [m] 5 x 10 －５ m < h < 5 × 10 －４ m, and, 2×10 －３ m<w ｔ <2×10 －２ m、 Satisfying the conditions, [Number L] A current sensor according to claim 4, satisfying the requirements.

6. The current sensor according to claim 1, wherein the conductive plate is not exposed from the surface of the sealing portion and is built into the sealing portion.

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

8. The current sensor according to claim 7, wherein the magnetic sensing surface overlaps with the signal processing IC in a plan view, and the electrical connection between the signal processing IC and the at least one magnetoelectric conversion unit does not straddle the current conductor.

9. The at least one magnetoelectric conversion unit includes at least one magnetoelectric conversion element separate from the signal processing IC, The current sensor according to claim 8, wherein the magnetosensitive surface of 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 side of the signal processing IC opposite to the circuit side is arranged on the side of the conductor plate facing the current conductor.

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

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

13. The current sensor according to claim 12, wherein the conductive plate is disposed on the side of the current conductor opposite to the side on which the signal processing IC is arranged, via an insulating member.

14. The current sensor according to claim 7, wherein the conductive plate is arranged 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 does not have an interface between members that lead to the signal processing IC.

17. The current sensor according to claim 1, wherein the conductor plate does not have a hole or slit penetrating the conductor plate at a position that overlaps with at least a portion of the magnetic surface in a plan view.

18. A first terminal portion is electrically connected to the current conductor and is exposed from the first side surface of the sealing portion, A second terminal portion is exposed from the second side facing the first side of the sealing portion and outputs a signal from the signal processing unit. The current sensor according to claim 1, further comprising:

19. 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.

20. The current sensor according to claim 18, wherein the second terminal portion is integrally formed with at least a portion of the conductor plate.

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

22. circuit board and The substrate is mounted on the current sensor according to claim 1, A current measuring device in which the conductive plate is not exposed from the surface of the sealing portion or the substrate on which the current sensor is mounted, and is built into the sealing portion or the substrate.

23. circuit board and The substrate is mounted on the current sensor according to claim 1, The conductive plate is a current measuring device, which is placed on a substrate on which the current sensor is mounted.

24. circuit board and The substrate is equipped with the current sensor described in claim 7, The side of the signal processing IC opposite to the circuit side is positioned on the side of the current conductor facing the conductor plate. The conductive plate is a current measuring device, which is placed on a substrate on which the current sensor is mounted.

25. The current measuring device according to claim 24, wherein the conductive plate is built into the substrate.

26. The current measuring device according to claim 24, wherein the conductive plate is mounted on the surface layer of the substrate.

27. The current measuring device according to claim 26, wherein the conductor plate is covered with an insulator.

28. The current measuring device according to claim 24, wherein the conductive plate is arranged on the surface of the signal processing IC on the circuit side of the sealing portion.

29. At least one magnetoelectric conversion unit, A current conductor through which the measurement current measured in the at least one magnetoelectric conversion unit flows, A signal processing unit that processes the signal output from at least one magnetoelectric conversion unit, A conductive plate that overlaps with the current conductor in a plan view, The sealing portion that seals at least one magnetoelectric conversion unit, the current conductor, and the signal processing unit A current sensor comprising, The current conductor is a nonmagnetic material and, in a plan view, includes a main body portion that partially or completely surrounds one of the at least one magnetoelectric conversion portion, and the main body portion includes a first portion that at least surrounds three sides of the one magnetoelectric conversion portion. The thickness of the aforementioned conductor plate is u [m], In a plan view, the shortest distance between the center of the magnetosensitive surface of the at least one magnetoelectric conversion unit and the surface of the current conductor is h [m]. In plan view, the maximum width of the first part is w ｂ [>] The shorter of the distance between the conductor plate and the current conductor in the thickness direction, and the distance between the conductor plate and the magnetosensitive surface of the at least one magnetoelectric conversion unit, is z. ｂ [>], In a plan view, the narrowest width of the conductor plate in the portion that crosses the at least one magnetoelectric conversion section is w ｔ [>] 、 The conductivity of the aforementioned conductor plate is σ ｔ [S / m] 、 In that case, 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、 A current sensor that satisfies the following conditions.

30. At least one magnetoelectric conversion unit, A current conductor through which the measurement current measured in the at least one magnetoelectric conversion unit flows, A signal processing unit that processes the signal output from at least one magnetoelectric conversion unit, A conductive plate that overlaps with the current conductor in a plan view, The sealing portion that seals at least one magnetoelectric conversion unit, the current conductor, and the signal processing unit A current sensor comprising, The current conductor is made of a material containing 50% or more copper, and in a plan view, includes a main body that partially or completely surrounds one of the at least one magnetoelectric conversion units, and the main body includes a first portion that at least surrounds three sides of the one magnetoelectric conversion unit. In a plan view, the shortest distance between the center of the magnetosensitive surface of the at least one magnetoelectric conversion unit and the current conductor is h. In plan view, the maximum width of the first part is w ｂ [>] The shorter of the distance between the conductor plate and the current conductor in the thickness direction, and the distance between the conductor plate and the magnetosensitive surface of the at least one magnetoelectric conversion unit, is z. ｂ [>], In that case, [Number M] A current sensor that satisfies the following conditions.

31. At least one magnetoelectric conversion unit, A current conductor through which a measurement current, measured in at least one magnetoelectric conversion unit, flows, A signal processing unit that processes the signal output from at least one magnetoelectric conversion unit, A conductive plate that overlaps with the current conductor in a plan view, The sealing portion that seals at least one magnetoelectric conversion unit, the current conductor, and the signal processing unit A current sensor comprising, The current conductor includes a main body portion that, in a plan view, partially or completely surrounds one of the at least one magnetoelectric conversion portion, and the main body portion includes a first portion that surrounds at least three sides of the one magnetoelectric conversion portion. The thickness of the aforementioned conductor plate is u [m], The permeability of the conductor plate is μ ｔ [N / A] ２ ], The conductivity of the current conductor is σ ｂ [S / m] The permeability of the current conductor is μ ｂ [N / A] ２ ], The conductivity of the aforementioned conductor plate is σ ｔ [S / m] In a plan view, the shortest distance between the center of the magnetosensitive surface of the at least one magnetoelectric conversion unit and the current conductor is h [m]. In plan view, the maximum width of the first part is w ｂ [>], The shorter of the distance between the conductor plate and the current conductor in the thickness direction, and the distance between the conductor plate and the magnetosensitive surface of the at least one magnetoelectric conversion unit, is z. ｂ [>], In a plan view, the narrowest width of the conductor plate in the portion that crosses the at least one magnetoelectric conversion section is w ｔ If we use [m], [Number N] Satisfying the conditions, Here, [Number O] [Number P] [Math Question] [Number R] [Number S] This is a current sensor.

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