Current sensor

Abstract

SOLUTION: A current sensor is formed of at least one magnetoelectric transducer, a conductor, and a signal processing IC, which are sealed by a sealing part. The current sensor comprises: a pair of first lead terminals that are partially exposed to a side face of the sealing part, are electrically connected with the conductor, input measurement current to the conductor, and output the measurement current from the conductor; a metal member that is partially exposed to the side face of the sealing part, and is separated from the conductor; and an element support part that is formed of a metal plate or a semiconductor substrate, supports the at least one magnetoelectric transducer and metal member on a surface on the same side as a first surface, and is separated from the conductor.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] This invention relates to a current sensor. [Background technology]

[0002] Patent documents 1 and 2 disclose current sensors having magnetoelectric conversion elements. [Prior art document] [Patent] [Patent Document 1] Japanese Patent No. 6415148 [Patent Document 2] Japanese Patent No. 6017182 [Overview of the project] [Problems that the invention aims to solve]

[0003] In current sensors having a magnetoelectric conversion element, variations in the position of the magnetoelectric conversion element between individual sensors can lead to variations in the sensitivity of the measured current measured by the magnetoelectric conversion element, potentially impairing the quality of the current sensor. [Means for solving the problem]

[0004] A current sensor according to one aspect of the present invention may comprise at least one magnetoelectric element. The current sensor may comprise a conductor that at least partially surrounds the at least one magnetoelectric element in a plan view and through which a measurement current measured by the at least one magnetoelectric element flows. The current sensor may comprise a signal processing IC that processes the signal output from the at least one magnetoelectric element. The current sensor may comprise an IC support portion having a gap for electrical insulation from the conductor, a first surface and a second surface opposite to the first surface, and supporting the signal processing IC on the first surface. The current sensor may comprise an element support portion made of a metal plate or a semiconductor substrate, which supports the at least one magnetoelectric element on the same side as the first surface. The element support portion is arranged opposite the same side of the conductor as the second surface, overlaps with the conductor when viewed from the thickness direction of the element support portion, but does not overlap with the conductor when viewed from a direction intersecting the thickness direction.

[0005] In the current sensor, the conductor may have a stepped portion such that, in the thickness direction, the surface on the same side as the first surface of the element support portion and the surface on the same side as the second surface of the conductor are spaced apart.

[0006] Any of the current sensors may include a sealing portion that seals the at least one magnetoelectric conversion element, the conductor, and the signal processing IC. The current sensor may include a pair of first lead terminals that are partially exposed on the side surface of the sealing portion, electrically connected to the conductor, input the measured current to the conductor, and output the measured current from the conductor. The current sensor may include a metal member that is partially exposed on the side surface of the sealing portion and spaced apart from the conductor. The element support portion may support the at least one magnetoelectric conversion element and the metal member on the same side as the first surface.

[0007] Each of the current sensors may have a plurality of second lead terminals, some of which are exposed on the side surface of the sealing portion and electrically connected to the signal processing IC. The IC support portion may be integrally formed with at least one of the plurality of second lead terminals.

[0008] In any of the current sensors, the element support portion may support the second surface of the IC support portion opposite to the first surface that supports the signal processing IC, on the same side as the first surface.

[0009] In any of the current sensors, the metal component is separate from the plurality of second lead terminals and does not need to be electrically connected to the signal processing IC.

[0010] In any of the current sensors, the metal member may be at least one second lead terminal that is different from at least one of the plurality of second lead terminals.

[0011] In any of the current sensors, the pair of first lead terminals and the plurality of second lead terminals may be arranged to face each other via the signal processing IC in a first direction intersecting the thickness direction of the signal processing IC. The metal member may include a first portion and a second portion spaced apart in a second direction intersecting the first direction. The element support portion may support the first portion and the second portion at both end portions in the second direction. When the distance in the second direction of a portion that does not support the first portion and the second portion between the both end portions of the element support portion is L and the thickness of the element support portion is h, L < 8×10 6 ×h 2 may be satisfied.

[0012] Any of the current sensors may include an adhesive layer that adheres the element support portion to the second surface of the IC support portion.

[0013] In any of the current sensors, the adhesive layer may be a die attach film.

[0014] Any of the current sensors may include a plurality of second lead terminals, a part of which is exposed on a side surface of the sealing portion and is electrically connected to the signal processing IC. At least one lead terminal of the plurality of second lead terminals, the element support portion, and the IC support portion may be integrally formed.

[0015] In any of the current sensors, the conductor may have a stepped portion such that a surface on the same side as the first surface of the element support portion in the thickness direction and a surface on the same side as the second surface of the conductor are spaced apart.

[0016] In any of the current sensors, the IC support portion and the element support portion, or at least one of the plurality of second lead terminals and the IC support portion may be connected via a bent portion that bends such that a surface on the same side as the first surface of the element support portion in the thickness direction and a surface on the same side as the second surface of the conductor are spaced apart.

[0017] In any of the current sensors, the plurality of second lead terminals, the IC support portion, the element support portion, and the metal member may be integrally formed by a first lead frame. The pair of first lead terminals and the conductor may be integrally formed by a second lead frame.

[0018] 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]

[0019] [Figure 1A] This is a schematic plan view of the current sensor according to the first embodiment, as seen from the ceiling side. [Figure 1B] Figure 1A is a cross-sectional view of the current sensor shown along line AA. [Figure 2A] This is a schematic plan view of the current sensor according to the second embodiment, as seen from the ceiling side. [Figure 2B] Figure 2A is a cross-sectional view of the current sensor shown along line AA. [Figure 3A] This is a schematic plan view of the current sensor according to the third embodiment, as seen from the ceiling side. [Figure 3B] Figure 3A is a cross-sectional view of the current sensor shown along line AA. [Figure 4A] This is a schematic plan view of the current sensor according to the fourth embodiment, as seen from the ceiling side. [Figure 4B] Figure 4A is a cross-sectional view of the current sensor shown along line AA. [Figure 5] This flowchart shows the procedure for manufacturing a current sensor according to the first embodiment. [Figure 6A] This figure schematically shows the manufacturing process of the current sensor according to the first embodiment. [Figure 6B] This figure schematically shows the manufacturing process of the current sensor according to the first embodiment. [Figure 6C] This figure schematically shows the manufacturing process of the current sensor according to the first embodiment. [Figure 6D]This figure schematically shows the manufacturing process of the current sensor according to the first embodiment. [Figure 7] This flowchart shows the procedure for manufacturing a current sensor according to the fourth embodiment. [Figure 8A] This figure schematically shows the manufacturing process of the current sensor according to the fourth embodiment. [Figure 8B] This figure schematically shows the manufacturing process of the current sensor according to the fourth embodiment. [Figure 8C] This figure schematically shows the manufacturing process of the current sensor according to the fourth embodiment. [Figure 8D] This figure schematically shows the manufacturing process of the current sensor according to the fourth embodiment. [Figure 9] This is a schematic plan view of the area around the conductor of a current sensor according to a modified example of the first embodiment, as seen from the ceiling side. [Modes for carrying out the invention]

[0020] The present invention will be described below through embodiments, but these embodiments are not intended to limit the scope of the claims. Furthermore, not all combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0021] The current sensor comprises a primary conductor through which the measurement current flows, a magnetoelectric conversion element that detects the magnetic field generated by the measurement current, and a signal processing IC that amplifies the signal from the magnetoelectric conversion element and outputs it externally. The primary conductor, magnetoelectric conversion element, and signal processing IC are encapsulated in molded resin to form a single semiconductor package.

[0022] For example, Patent Document 1 discloses a current sensor comprising a U-shaped primary conductor, a magnetoelectric conversion element positioned in the opening of the primary conductor, and a signal processing IC. The insulating member supporting the magnetoelectric conversion element is positioned to contact the bottom surface of the support portion supporting the signal processing IC, without contacting the primary conductor.

[0023] Furthermore, Patent Document 2 discloses a current sensor comprising a U-shaped primary conductor, a magnetoelectric conversion element positioned in the opening of the primary conductor, and a signal processing IC. The insulating member supporting the magnetoelectric conversion element is positioned to contact the back surface of the primary conductor.

[0024] In the current sensors described in Patent Documents 1 and 2, the insulating member supporting the magnetoelectric conversion element is made of insulating tape or an insulating sheet. However, because the insulating member has low rigidity, it may deform during resin sealing in the assembly process. If the insulating member deforms, the position of the magnetoelectric conversion element provided in the opening of the primary conductor changes, which can cause variations in the sensitivity of the measured current measured by the magnetoelectric conversion element between individual units, potentially impairing the quality of the current sensor.

[0025] Furthermore, the apparatus used to manufacture insulating materials for current sensors, as described in Patent Documents 1 and 2, is not a general-purpose apparatus used in typical post-processing, but rather a dedicated apparatus. This dedicated apparatus cuts the insulating material to the desired size and attaches it to the lead frame. Therefore, manufacturing such current sensors requires investment in dedicated apparatus, and the complex manufacturing process raises concerns about increased costs.

[0026] Therefore, in each embodiment, it is possible to suppress variations in the sensitivity of current measurement between individual units, providing a high-quality, compact, and highly sensitive current sensor. In addition, in each embodiment, efficient production enables cost reduction through economies of scale, providing a compact and highly sensitive current sensor.

[0027] Figures 1A and 1B show the internal configuration of a semiconductor package that functions as a current sensor 10 according to the first embodiment. Figure 1A is a schematic plan view of the current sensor 10 according to the first 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.

[0028] 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.

[0029] The current sensor 10 comprises a signal processing IC 100, a magnetoelectric conversion element 20, an IC support portion 112, an element support portion 114, a conductor 120, a sealing portion 130, a pair of lead terminals 140, a plurality of lead terminals 150, and a suspension pin 160. The magnetoelectric conversion element 20 is electrically connected to the signal processing IC 100 via a wire 30. The signal processing IC 100 is electrically connected to the plurality of lead terminals 150 via a wire 108. Wires 30 and 108 may be formed from a conductive material mainly composed of Au, Ag, Cu, or Al.

[0030] The sealing portion 130 seals the magnetoelectric conversion element 20, conductor 120, signal processing IC 100, IC support portion 112, element support portion 114, wire 30, and wire 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. Since it is molded into a semiconductor package, a small current sensor 10 can be realized.

[0031] The magnetoelectric conversion element 20 detects a magnetic field in a specific direction that changes according to the measured current flowing through the conductor 120, and the signal processing IC 100 amplifies the signal according to the magnitude of the magnetic field and outputs the amplified signal via the lead terminal 150. The magnetoelectric conversion element 20 is made of a compound semiconductor formed on a GaAs substrate and may be a chip cut out in the shape of a square or rectangle when viewed from the Z-axis direction. The magnetoelectric conversion element 20 may have a substrate made of silicon or a compound semiconductor and a magnetoelectric conversion part provided on the substrate. The thickness of the substrate is adjusted by polishing the negative side of the Z-axis direction. The substrate may have a desired thickness in the range of 50 μm to 600 μm. Since a magnetic field in the Z-axis direction is detected, a Hall element is suitable as the illustrated magnetoelectric conversion element. Also, if the magnetoelectric conversion element 20 is positioned to detect a magnetic field in any one axis direction on the XY plane, for example, if it is positioned to detect a magnetic field in the X-axis direction, then a magnetoresistive element or a fluxgate element is suitable as the magnetoelectric conversion element.

[0032] In the first embodiment, an example is described in which the current sensor 10 comprises one magnetoelectric conversion element 20. However, the current sensor 10 may comprise two or more magnetoelectric conversion elements 20. In a plan view, at least a portion of each of the multiple magnetoelectric conversion elements 20 may be surrounded by a conductor 120. A portion of the conductor 120 may be positioned between each of the multiple magnetoelectric conversion elements 20.

[0033] The signal processing IC 100 processes the signal output from the magnetoelectric conversion element 20. The signal processing IC 100 is a large-scale integrated circuit (LSI). The signal processing IC 100 is cut into a rectangular or square shape in plan view. The signal processing IC 100 is a signal processing circuit made of a Si monolithic semiconductor formed on a Si substrate. A compound semiconductor substrate may be used instead of the Si substrate. The signal processing circuit processes an output signal corresponding to the magnitude of the magnetic field output from the magnetoelectric conversion element 20. Based on the output signal, the signal processing circuit outputs an output signal via the lead terminal 150 indicating the current value of the measured current flowing through the conductor 120. The thickness of the substrate of the signal processing IC 100 is adjusted by polishing the negative side of the Z-axis direction. The substrate has a desired thickness in the range of 50 μm to 600 μm. The signal processing circuit of the signal processing IC 100 is equipped with a circuit that takes a minute output signal corresponding to the magnitude of the magnetic field of the magnetoelectric conversion element as input and amplifies at least the input signal.

[0034] The conductor 120 has a U-shape in plan view and at least partially surrounds the magnetoelectric conversion element 20 in plan view, through which the measurement current measured by the magnetoelectric conversion element 20 flows. The conductor 120 is electrically connected to a pair of lead terminals 140. The conductor 120 may be physically integrated with the pair of lead terminals 140. The measurement current is input from one of the pair of lead terminals 140, and the measurement current is output from the other lead terminal 140 via the conductor 120. The pair of lead terminals 140 and the conductor 120 may be integrally formed by a lead frame of a conductive material mainly composed of copper. The measurement current measured by the magnetoelectric conversion element 20 flows through the pair of lead terminals 140 and the conductor 120. The conductor 120 has a slit 140a that opens to the side surface 130a of the sealing portion 130. The magnetoelectric conversion element 20 is placed inside the slit 140a. The measurement current flowing through the conductor 120 flows along the U-shape from one end to the other. This generates a magnetic field around the conductor 120, which is proportional to the magnitude of the measurement current and the distance from the conductor 120. At the location where the magnetoelectric conversion element 20 is placed, a magnetic field is generated in which the Z-axis component is largest. Since the magnetoelectric conversion element 20 is placed inside the slit 140a, high sensitivity to the measurement current can be obtained.

[0035] A pair of lead terminals 140 and a plurality of lead terminals 150 are arranged facing each other via the signal processing IC 100 in a direction (Y-axis direction) that intersects the thickness direction (Z-axis direction) of the signal processing IC 100. Part of the pair of lead terminals 140 is exposed from side 130a of the sealing portion 130. Part of the plurality of lead terminals 150 is exposed from side 130b of the sealing portion 130, opposite to side 130a. Part of the suspension pins 160 are exposed from side 130c and side 130d of the sealing portion 130, which are opposite to side 130a and side 130b in the X-axis direction. The suspension pins 160 are metal components for supporting the semiconductor package on the lead frame during the manufacturing stage. The suspension pins 160 are leads that support the sealing portion 130, which is molded resin, throughout the assembly process.

[0036] The multiple lead terminals 150 are metal components electrically connected to the signal processing IC 100, while the suspension pins 160 are metal components not electrically connected to the signal processing IC 100. The suspension pins 160 are separate from the multiple lead terminals 150. The multiple lead terminals 150 and the suspension pins 160 may be formed together with a pair of lead terminals 140 and a conductor 120 by a lead frame made of a conductive material mainly composed of copper. The multiple lead terminals 150 and the suspension pins 160 are isolated from the conductor 120 and electrically insulated from the conductor 120.

[0037] The pair of lead terminals 140, the conductor 120, the multiple lead terminals 150, and the suspension pin 160 may be integrally formed by a lead frame made of a conductive material mainly composed of copper. The pair of lead terminals 140 are primary-side lead terminals and are an example of a pair of first lead terminals. The multiple lead terminals 150 are secondary-side lead terminals and are an example of a multiple second lead terminals. The lead frame has a desired thickness in the range of 50 μm to 600 μm.

[0038] The IC support portion 112 is a plate-shaped member that supports the signal processing IC 100 on the ceiling-side surface 112a of the current sensor 10. The IC support portion 112 may be integrally configured with at least one of the multiple lead terminals 150. In the first embodiment, the IC support portion 112 is integrally configured with the lead terminals 150a and 150b located at both ends in the X-axis direction of the multiple lead terminals 150. The IC support portion 112 may be composed of lead frames for all of the multiple lead terminals 150. The signal processing IC 100 may be bonded to the surface 112a of the IC support portion 112 via an adhesive layer 116. The adhesive layer 116 may be a die attach film.

[0039] The IC support portion 112 has extensions 112c and 112d that surround the conductor 120 and extend toward a pair of lead terminals 140. The conductor 120 and the magnetoelectric conversion element 20 are arranged between extensions 112c and 112d. Extensions 112c and 112d are examples of first and second portions that are spaced apart along the surface 112a and in the X-axis direction.

[0040] The element support portion 114 is made of a metal plate or a semiconductor substrate and supports the magnetoelectric conversion element 20 and the IC support portion 112 on the surface 114a facing the ceiling of the current sensor 10. The element support portion 114 is spaced apart from the conductor 120 and is electrically insulated from the conductor 120. On surface 114a, the element support portion 114 supports the surface 112b of the IC support portion 112, which is opposite to surface 112a that supports the signal processing IC 100. When viewed from the thickness direction (Z-axis direction) of the magnetoelectric conversion element 20, the element support portion 114 overlaps with the conductor 120, but is physically spaced apart from the conductor 120. The semiconductor substrate constituting the element support portion 114 may be a silicon substrate or a compound semiconductor substrate. The thickness of the semiconductor substrate may be in the range of 100 μm to 700 μm and depends on the size of the semiconductor substrate, so the semiconductor substrate may be of an appropriate thickness so as not to crack. The metal plate constituting the element support portion 114 is preferably made of a metal that does not have ferromagnetic properties, such as copper or aluminum. The thickness of the metal plate may be appropriately selected within the range of 100 μm to 700 μm to ensure sufficient rigidity.

[0041] The element support portion 114 is bonded to the IC support portion 112 via the adhesive layer 115, and is bonded to the magnetoelectric conversion element 20 via the adhesive layer 115 and the adhesive layer 21. The adhesive layer 115 and the adhesive layer 21 may be die attach films.

[0042] Adhesive layers 21, 115, and 116 may be the same size as the magnetoelectric conversion element 20, element support part 114, and signal processing IC 100 in a plan view. Adhesive layers 21, 115, and 116 may be die attach films made of non-conductive resin or die attach films made of conductive resin. The non-conductive resin may be epoxy-based or silicone-based resin. The conductive resin may be an epoxy-based resin mixed with an Ag filler. Adhesive layers 21, 115, and 116 may have a desired thickness in the range of 1 μm to 50 μm. Adhesive layers 21, 115, and 116 may be pastes made of conductive or non-conductive materials.

[0043] The element support portion 114 is bonded to a part of the negative Z-axis side surface 112b of the IC support portion 112 and positioned to extend to the position of the magnetoelectric conversion element 20. The conductor 120 has a stepped portion 140b such that the surface 114a of the element support portion 114 and the surface 120a of the conductor 120 are spaced apart in the thickness direction (Z-axis direction) of the element support portion 114. The portion of the conductor 120 facing the element support portion 114 has a stepped portion 140b such that it protrudes toward the ceiling side (positive Z-axis side) of the sealing portion 130. The stepped portion 140b may be provided on the conductor 120 by a half-cutting process so that the element support portion 114 and the conductor 120 do not come into contact. The stepped portion 140b may also be provided on the conductor 120 by coining or half-etching.

[0044] In the first embodiment, the element support portion 114 is bonded to the surface 112b of the IC support portion 112. However, the element support portion 114 may be bonded only to the extensions 112c and 112d of the IC support portion 112 and positioned to extend to the position of the magnetoelectric conversion element 20.

[0045] The voltage of the primary network to which conductor 120 is connected via lead terminal 140 is generally higher than the voltage of the secondary network to which signal processing IC 100 is connected via lead terminal 150. Therefore, conductor 120 must be electrically insulated from the magnetoelectric conversion element 20 and signal processing IC 100, which are electrically connected by wire 30. For this reason, conductor 120 is covered with a molded resin, which is an insulator. The element support portion 114 on which the magnetoelectric conversion element 20 is mounted has a gap of distance d between it and conductor 120, provided by a stepped portion 140b on conductor 120. Molded resin is mainly inserted into the gap between element support portion 114 and conductor 120. The dielectric breakdown electric field strength of typical molded resin is approximately 20kV / mm, so if the gap distance d is designed to be 50μm or more, the molded resin inserted into the gap will have an dielectric strength of approximately 1kV or more. If the primary circuit voltage is AC240V and the secondary circuit voltage is DC5V, sufficient insulation can be ensured.

[0046] The element support portion 114 supports the extensions 112c and 112d at both ends in the X-axis direction. Here, L (m) is the length of the portion of the element support portion 114 that does not support the extensions 112c and 112d, the width of the element support portion 114 in the Y-axis direction is b (m), and the thickness of the element support portion 114 is h (m). When a load P (N) is applied in the negative Z-axis direction to the position where the magnetoelectric conversion element 20 is placed on the element support portion 114, the same result as in the three-point bending test occurs, and the stress σ (Pa) generated in the element support portion 114 is expressed by the following equation (1). σ = (2 / 3) × (PL / bh) 2 ) ···(1)

[0047] Here, when the element support portion 114 is a silicon substrate, the fracture stress σ of the silicon substrate b It has been experimentally determined that the pressure is approximately 400 MPa. For example, if you inflate a Hall element on a silicon substrate with 100 gf (≈ 100 × 10⁻¹⁰ MPa) -4When die-bonding at (N), if the stress σ generated in the silicon substrate is within a range smaller than the fracture stress, assembly can be executed without the silicon substrate cracking. Here, assuming that the short-side width b of the silicon substrate is 0.3 mm, which is equivalent to the width of the smallest hole element, the relational expression (2) can be obtained between L and h. σ = (2 / 3) × ((100 × 10 -4 ) × L / (0.3 × 10 -3 ) × h 2 ) < (400 × 10 6 ) = σ b Therefore, L < 8 × 10 6 × h 2 ···(2)

[0048] In the range of L and h where the relational expression (2) holds, displacement of the hole element can be suppressed and stable assembly can be executed.

[0049] That is, when the distance in the X-axis direction, which is the length of the portion not supporting the extension portions 112c and 112d between both end portions of the element support portion 114, is L, and the thickness of the element support portion 114 is h, L < 8 × 10 6 × h 2

[0050] It is preferable to satisfy.

[0051] According to the current sensor according to the first embodiment, since the element support member that supports the magnetoelectric conversion element 20 is composed of a rigid semiconductor substrate or a metal plate, deformation of the element support portion 114 can be prevented, and the position of the magnetoelectric conversion element 20 is stabilized. Thereby, variation in the sensitivity of the measured current measured by the magnetoelectric conversion element 20 among individuals can be suppressed, and the quality of the current sensor 10 can be improved.

[0052] FIGS. 2A and 2B show the internal configuration of the semiconductor package functioning as the current sensor 10 according to the second embodiment. FIG. 2A is a schematic plan view seen from the ceiling surface side (Z-axis direction) of the current sensor 10 according to the second embodiment. FIG. 2B is a cross-sectional view taken along line A-A of the current sensor 10 shown in FIG. 2A.

[0053] The current sensor 10 according to the second embodiment differs from the current sensor 10 according to the first embodiment in that the metal member supporting the element support portion 114 is not a member integrally formed with the lead terminal 150, but rather a suspension pin 160.

[0054] In the current sensor 10 according to the second embodiment, similar to the current sensor 10 according to the first embodiment, the magnetoelectric conversion element 20 detects a magnetic field in a specific direction generated by the current flowing through the lead terminal 140. The signal processing IC 100 amplifies the signal according to the magnitude of the current, and the amplified signal is output from the lead terminal 150.

[0055] In the second embodiment, the two suspension pins 160 extend from the sides 130c and 130d of the sealing portion 130 toward the conductor 120 to a position opposite the conductor 120. The suspension pins 160 are spaced apart from the conductor 120 and are electrically insulated from the conductor 120. The conductor 120 is positioned between the two suspension pins 160. The suspension pins 160 are metal components that are not electrically connected to the signal processing IC 100. The suspension pins 160 are separate from the multiple lead terminals 150.

[0056] Here, let L (m) be the distance in the X-axis direction, which is the longitudinal side of the portion between the two suspension pins 160 that are not supported between the two ends of the element support portion 114, let b (m) be the width in the Y-axis direction, which is the short side of the element support portion 114, and let h (m) be the thickness of the element support portion 114. When a load P (N) is applied in the negative Z-axis direction to the position where the magnetoelectric conversion element 20 is placed on the element support portion 114, the same condition as in the three-point bending test occurs, and the stress σ (Pa) generated in the element support portion 114 is expressed by the following equation (1). σ = (2 / 3) × (PL / bh) 2 ) ···(1)

[0057] Here, when the element support portion 114 is a silicon substrate, the fracture stress σ of the silicon substrate b It has been experimentally determined that the pressure is approximately 400 MPa. For example, if you inflate a Hall element on a silicon substrate with 100 gf (≈ 100 × 10⁻¹⁰ MPa)-4 When die bonding with N), the stress σ generated in the silicon substrate can be kept below the fracture stress so that the silicon substrate does not crack during assembly. Here, if the width b of the shorter side of the silicon substrate is 0.3 mm, which is equivalent to the width of the minimum Hall element, then the relationship (2) is obtained between L and h. σ = (2 / 3) × ((100 × 10 -4 ) × L / (0.3 × 10 -3 ) × h 2 )<(400×10 6 )=σ b Therefore, L < 8 × 10 6 ×h 2 ...(2)

[0058] Within the range of L and h for which relation (2) holds, misalignment of the Hall element can be suppressed, enabling stable assembly.

[0059] In other words, if L is the distance in the X-axis direction which is the longitudinal side of the portion between the two suspension pins 160 that are not supported between the two ends of the element support portion 114, and h is the thickness of the element support portion 114, then L < 8 × 10 6 ×h 2 It is preferable that the following conditions be met.

[0060] According to the current sensor 10 of the second embodiment, the element support member that supports the magnetoelectric conversion element 20 is made of a rigid semiconductor substrate or metal plate, so deformation of the element support portion 114 can be prevented and the position of the magnetoelectric conversion element 20 is stabilized. As a result, variations in the sensitivity of the measured current measured by the magnetoelectric conversion element 20 can be suppressed between individual units, and the quality of the current sensor 10 can be improved.

[0061] Figures 3A and 3B show the internal configuration of a semiconductor package that functions as a current sensor 10 according to the third embodiment. Figure 3A is a schematic plan view of the current sensor 10 according to the third embodiment, viewed from the ceiling side (Z-axis direction). Figure 3B is a cross-sectional view of the current sensor 10 shown in Figure 3A, along line AA.

[0062] The current sensor 10 according to the third embodiment differs from the current sensor 10 according to the first embodiment, in which the metal member supported by the element support portion 114 is a lead terminal 150 integrally formed with the IC support portion 112, in that the metal member supported by the element support portion 114 is a lead terminal 150 integrally formed with the IC support portion 112, specifically the lead terminals 150a and 150b at both ends in the X-axis direction, among the multiple lead terminals 150. Furthermore, the current sensor 10 according to the third embodiment also differs from the current sensor 10 according to the second embodiment, in which the metal member supported by the element support portion 114 is a suspension pin 160 instead of a lead terminal 150, in that the metal member supported by the element support portion 114 is a lead terminal 150a and 150b at both ends in the X-axis direction, among the multiple lead terminals 150, specifically the lead terminals.

[0063] Parts of lead terminals 150a and 150b are exposed from the side surface 130b of the sealing portion 130, similar to the other lead terminals 150. Lead terminals 150a and 150b extend toward the pair of lead terminals 140 to a position facing the conductor 120. The conductor 120 and the magnetoelectric conversion element 20 are positioned between the ends 150c and 150d of lead terminals 150a and 150b, which are embedded in the sealing portion 130. The element support portion 114 supports the ends 150c and 150d.

[0064] Here, let L (m) be the distance in the X-axis direction, which is the longitudinal side of the portion between the two ends of the element support portion 114 that does not support ends 150c and 150d, let b (m) be the width in the Y-axis direction, which is the short side of the element support portion 114, and let h (m) be the thickness of the element support portion 114. When a load P (N) is applied in the negative Z-axis direction to the position where the magnetoelectric conversion element 20 is placed on the element support portion 114, the same result as in the three-point bending test occurs, and the stress σ (Pa) generated in the element support portion 114 is expressed by the following equation (1). σ = (2 / 3) × (PL / bh) 2 ) ···(1)

[0065] Here, when the element support portion 114 is a silicon substrate, the fracture stress σ of the silicon substrate b It has been experimentally determined that the pressure is approximately 400 MPa. For example, if you inflate a Hall element on a silicon substrate with 100 gf (≈ 100 × 10⁻¹⁰ MPa) -4 When die bonding with N), the stress σ generated in the silicon substrate can be kept below the fracture stress so that the silicon substrate does not crack during assembly. Here, if the width b of the shorter side of the silicon substrate is 0.3 mm, which is the same as the width of the minimum Hall element, then the relationship (2) is obtained between L and h. σ = (2 / 3) × ((100 × 10 -4 ) × L / (0.3 × 10 -3 ) × h 2 )<(400×10 6 )=σ b Therefore, L < 8 × 10 6 ×h 2 ...(2)

[0066] Within the range of L and h for which relation (2) holds, misalignment of the Hall element can be suppressed, enabling stable assembly.

[0067] In other words, if L is the distance in the X-axis direction which is the longitudinal side of the portion between the two ends of the element support portion 114 that does not support ends 150c and 150d, and h is the thickness of the element support portion 114, then L < 8 × 10 6 ×h 2 It is preferable that the following conditions be met.

[0068] According to the current sensor 10 of the third embodiment, the element support member that supports the magnetoelectric conversion element 20 is made of a rigid semiconductor substrate or metal plate, so deformation of the element support portion 114 can be prevented and the position of the magnetoelectric conversion element 20 is stabilized. As a result, variations in the sensitivity of the measured current measured by the magnetoelectric conversion element 20 can be suppressed between individual units, and the quality of the current sensor 10 can be improved.

[0069] Figures 4A and 4B show the internal configuration of a semiconductor package that functions as a current sensor 10 according to the fourth embodiment. Figure 4A is a schematic plan view of the current sensor 10 according to the fourth embodiment, viewed from the top side (Z-axis direction). Figure 4B is a cross-sectional view of the current sensor 10 shown in Figure 4A, along line AA.

[0070] The current sensor 10 according to the fourth embodiment differs from the current sensor 10 according to the first, second, and third embodiments in that the element support portion 114, which is made of a metal member spaced apart from the conductor 120, is integrally configured with the IC support portion 112 and the lead terminals 150a and 150b located at both ends of the plurality of lead terminals 150.

[0071] According to the current sensor 10 of the fourth embodiment, two lead frames are used to form the sensor. One lead frame consists of an IC support portion 112, an element support portion 114, a lead terminal 150, and a suspension pin 160, while the other lead frame consists of a conductor 120 and a lead terminal 140. The two lead frames are preferably made of a conductive material mainly composed of Cu, but they may be made of different conductive materials. In the fourth embodiment, the thicknesses of the two lead frames are the same, but they may be different.

[0072] In the fourth embodiment, the element support portion 114 is a lead formed by extending the IC support portion 112 and bending it at the bent portion 113, and is made of a metal plate of a conductive material. In plan view, the element support portion 114 is arranged to overlap with the conductor 120, and in cross-sectional view, it is arranged so that it does not come into contact with the conductor 120 at a distance d in the thickness direction of the element support portion 114. That is, the IC support portion 112 and the element support portion 114 are connected via the bent portion 113, which is bent so that the surface 114a of the element support portion 114 and the surface 120a of the conductor 120 facing the element support portion 114 are separated in the thickness direction (Z-axis direction).

[0073] Furthermore, the element support portion 114 supports the magnetoelectric conversion element 20, which is positioned in the slit 140a, a U-shaped opening in the conductor 120. The bent portion 113 is provided on the lead at the connecting portion between the IC support portion 112 closer to the conductor 120 and the element support portion 114. However, the bent portion 113 may be provided, for example, on the lead between the lead terminal 150 and the IC support portion 112. If the bent portion 113 is provided on the lead between the lead terminal 150 and the IC support portion 112, the element support portion 114 may be integrally constructed with the IC support portion 112 without any steps when viewed from a direction intersecting the thickness direction of the element support portion 114.

[0074] According to the current sensor 10 of the fourth embodiment, the element support member that supports the magnetoelectric conversion element 20 is made of a rigid metal plate, so deformation of the element support portion 114 can be prevented, and the position of the magnetoelectric conversion element 20 is stabilized. As a result, variations in the sensitivity of the measured current measured by the magnetoelectric conversion element 20 can be suppressed between individual units, and the quality of the current sensor 10 can be improved.

[0075] Figure 5 is a flowchart showing the procedure for manufacturing the current sensor 10 according to the first embodiment. Figures 6A, 6B, 6C, and 6D are schematic diagrams showing the manufacturing process of the current sensor 10 according to the first embodiment.

[0076] First, the semiconductor wafer is diced to create individual silicon substrates that will become the element support portion 114 (S100). The silicon wafer may then be polished to the desired thickness using a backgrinding device used in a later process, and then cut to the desired size using a dicing device also used in a later process to create the silicon substrate that will become the element support portion 114. If a die attach film is used with the dicing tape during dicing, the element support portion 114 and the die attach film, which is the adhesive layer 115, are formed simultaneously. Here, a silicon substrate is used as an example, but even a metal plate can be cut to the desired size using a dicing device to create the substrate.

[0077] Furthermore, the wafer of the signal processing IC 100 is diced to create individual pieces of the signal processing IC 100 (S102). In addition, the wafer of the magnetoelectric conversion element 20 is diced to create individual pieces of the magnetoelectric conversion element 20 (S104). In the process of creating individual pieces of the signal processing IC 100, the wafer of the signal processing IC 100 is polished to a desired thickness using a backgrinding device, and then cut to a desired size using a dicing device to create the signal processing IC 100. When a die attach film is used as the dicing tape during dicing, the signal processing IC 100 and the die attach film, which is the adhesive layer 116, are formed simultaneously. Also, in the process of creating individual pieces of the magnetoelectric conversion element 20, the wafer of the magnetoelectric conversion element 20 is polished to a desired thickness using a backgrinding device, and then cut to a desired size using a dicing device to create the magnetoelectric conversion element 20. When a die attach film is used on the dicing tape during dicing, the magnetoelectric conversion element 20 and the die attach film, which is the adhesive layer 21, are formed simultaneously.

[0078] As shown in Figure 6A, the lead frame 200, which includes the conductor 120, IC support portion 112, lead terminals 140, lead terminals 150, and suspension pins 160, is formed by providing a stepped portion 140b on the conductor 120. Here, in the lead frame 200, the surface 112a that supports the signal processing IC 100 of the IC support portion 112 is defined as the first surface, and the surface 112b opposite to the first surface is defined as the second surface. The silicon substrate, which is the element support portion 114, is die-bonded to the IC support portion 112 and the conductor 120 on the same side as the second surface of the lead frame 200 via an adhesive layer 115 so as not to come into contact with the conductor 120 (S106). After die bonding, it is desirable to cure the adhesive layer 115 in order to fix it to the element support portion 114.

[0079] Next, as shown in Figure 6B, the signal processing IC 100 is die-bonded to the first surface of the IC support portion 112 of the lead frame 200 via an adhesive layer 116, and the magnetoelectric conversion element 20 is die-bonded to the element support portion 114 on the same side as the first surface of the lead frame 200 via an adhesive layer 21, such that the conductor 120 surrounds the magnetoelectric conversion element 20 at least partially in a plan view (S108). After die bonding, it is desirable to cure the adhesive layer 116 of the signal processing IC 100 in order to fix it to the IC support portion 112. Also, after die bonding, it is desirable to cure the adhesive layer 21 of the magnetoelectric conversion element 20 in order to fix it to the element support portion 114.

[0080] Furthermore, the signal processing IC 100 and the magnetoelectric conversion element 20 are electrically connected by wire bonding, and the signal processing IC 100 and the secondary lead terminal 150 are also electrically connected by wire bonding (S110).

[0081] As shown in Figure 6C, in the resin encapsulation process, the encapsulated portion 130 is formed by encapsulating the lead frame 200, which includes the IC support portion 112, lead terminals 140, lead terminals 150, and suspension pins 160, the magnetoelectric conversion element 20, the element support portion 114, and the signal processing IC 100 with molded resin (S112). In the resin encapsulation process, the lead frame 200, with the element support portion 114, the magnetoelectric conversion element 20, and the signal processing IC 100 mounted and electrically connected by wires 30 and 108, is sandwiched between resin encapsulation molds 71 ​​and 72 and solidified by the poured molded resin. After encapsulation, it is desirable to cure the molded resin to allow it to harden sufficiently.

[0082] As shown in Figure 6D, the resin-encapsulated current sensor is separated into individual pieces (S114), the lead terminals 140 and 150 are cut to the desired length, and lead forming is performed to shape them into the desired form (S116). This completes the current sensor 10 according to this embodiment.

[0083] As described above, the manufacturing method for the current sensor 10 can be handled entirely by downstream equipment, eliminating the need for investment in dedicated equipment. This allows for efficient production of the current sensor 10 and reduces costs through economies of scale.

[0084] Figure 7 is a flowchart showing the procedure for manufacturing the current sensor 10 according to the fourth embodiment. Figures 8A, 8B, 8C, and 8D are schematic diagrams showing the manufacturing process of the current sensor 10 according to the fourth embodiment.

[0085] The current sensor 10 according to the fourth embodiment is manufactured using a lead frame 200 and a lead frame 250. The lead frame 200 comprises a plurality of lead terminals 150, a suspension pin 160, an IC support portion 112, and an element support portion 114. The lead frame 250 comprises a conductor 120 and a lead terminal 140.

[0086] As shown in Figure 8A, recesses 152 are provided on the surfaces of both ends of the lead frame 200 that face the lead frame 250. Similarly, protrusions 162 corresponding to the recesses 152 are provided on the surfaces of both ends of the lead frame 250 that face the lead frame 200. The recesses 152 of the lead frame 200 and the protrusions 162 of the lead frame 250 are manufactured by partial punching, coining, and etching.

[0087] The lead frame 200 is bent at the bending portion 113 so that the IC support portion 112 and lead terminals 150 are on the first level surface, and the element support portion 114 and leads with recesses 152 are on the second level surface, which has a different height in the thickness direction of the lead frame 200 from the first level surface. The lead frame 250 is formed by providing a stepped portion 140b in the part corresponding to the conductor 120. The bending portion 113 is formed by bending the lead frame 200 so that the element support portion 114 does not come into contact with the conductor 120 at a gap of distance d when the two lead frames 200 and 250 are joined, thereby creating a step between the first level surface and the second level surface. The bending portion 113 is manufactured by bending or half-punching. Here, in the lead frame 200, the surface 112a that supports the signal processing IC 100 of the IC support portion 112 is defined as the first surface, and the surface opposite to the first surface is defined as the second surface.

[0088] In the lead frame joining process (S200), the recesses 152 at both ends of the lead frame 200 and the protrusions 162 at both ends of the lead frame 250 are fitted together, and the lead frame 200 and the lead frame 250 are fixed so that they overlap in a predetermined positional relationship. In this way, by joining the lead frames together, a single lead frame can be created that includes the IC support portion 112 as well as the element support portion 114.

[0089] In parallel with the bonding of the lead frames, the wafer of the signal processing IC 100 is diced to separate the signal processing IC 100 into individual pieces (S202). In addition, the wafer of the magnetoelectric conversion element 20 is diced to separate the magnetoelectric conversion element 20 into individual pieces (S204).

[0090] Next, as shown in Figure 8B, the signal processing IC 100 is bonded to the first surface of the IC support portion 112 of the lead frame 200 by die bonding via an adhesive layer 116, and the magnetoelectric conversion element 20 is bonded to the element support portion 114 on the same side as the first surface of the lead frame 200 by die bonding via an adhesive layer 21, such that the conductor 120 surrounds the magnetoelectric conversion element 20 at least partially in a plan view (S206).

[0091] In the die bonding process (S206) of the signal processing IC 100 and the magnetoelectric conversion element 20, the signal processing IC 100 is mounted on the IC support portion 112 on the first side of the lead frame 200 using a die bonding apparatus, and the magnetoelectric conversion element 20 is mounted on the element support portion 114 on the first side of the lead frame 200 where the signal processing IC 100 is die-bonded. After die bonding, it is desirable to cure the adhesive layer 116 of the signal processing IC 100 in order to fix it to the IC support portion 112. Also, after die bonding, it is desirable to cure the adhesive layer 21 of the magnetoelectric conversion element 20 in order to fix it to the element support portion 114.

[0092] Furthermore, the signal processing IC 100 and the magnetoelectric conversion element 20 are electrically connected by wire bonding, and the signal processing IC 100 and the secondary lead terminal 150 are also electrically connected by wire bonding (S208).

[0093] As shown in Figure 8C, in the resin encapsulation process, the encapsulation portion 130 is formed from molded resin, comprising lead frames 200, 250 including IC support portion 112, element support portion 114, lead terminals 140, lead terminals 150, and suspension pins 160, as well as the magnetoelectric conversion element 20 and the signal processing IC 100 (S210).

[0094] In the resin encapsulation process, the element support portion 114, the magnetoelectric conversion element 20, and the signal processing IC 100 are mounted, and the lead frames 200 and 250, electrically connected by wires 30 and 108, are sandwiched between resin encapsulation molds 71 ​​and 72 and solidified by the poured molding resin. After encapsulation, it is desirable to cure the molding resin to ensure it is fully hardened.

[0095] As shown in Figure 8D, the resin-encapsulated current sensor is separated into individual pieces (S212), the lead terminals 140 and 150 are cut to the desired length, and lead forming is performed to shape them into the desired form (S214). This completes the current sensor 10 according to this embodiment.

[0096] According to the manufacturing method of the current sensor 10 according to the fourth embodiment, all processes can be handled by downstream equipment, except for the lead frame joining process performed by the lead frame manufacturer. Therefore, there is no need to invest in dedicated equipment, production can be carried out efficiently, and costs can be reduced through economies of scale.

[0097] Figure 9 shows a modified example of the first embodiment, illustrating the internal configuration of a semiconductor package that functions as a current sensor 10, displaying only the area around the conductor 120. Figure 9 is a schematic plan view of the current sensor 10 according to the modified example of the first embodiment, as seen from the ceiling side (Z-axis direction).

[0098] As shown in Figure 9, the current sensor 10 of the modified first embodiment is formed such that two magnetoelectric elements 20 and 40 are arranged near the conductor 120. The magnetoelectric elements 20 and 40 are electrically connected to the signal processing IC 100 via wires 30 and 50, respectively. The magnetoelectric element 20 is located within the slit 140a and is positioned on the ceiling-side surface 114a of the element support portion 114. The magnetoelectric element 40 is positioned opposite the magnetoelectric element 20 in the X-axis direction relative to the conductor 120 and is positioned on the ceiling-side surface 114a of the element support portion 114.

[0099] In this configuration, when the measurement current flowing through the conductor 120 is supplied in the direction of the arrow shown in the figure, a magnetic field is generated at the position of the magnetoelectric conversion element 20 in the positive Z-axis direction, and a magnetic field is generated at the position of the magnetoelectric conversion element 40 in the negative Z-axis direction. The output voltages of the magnetoelectric conversion elements 20 and 40 are either positive and negative voltages, or negative and positive voltages. Therefore, the signal processing circuit calculates the difference between the output voltages of the magnetoelectric conversion elements 20 and 40 to obtain a signal corresponding to the magnitude of the current. On the other hand, with respect to an external magnetic field, such as the Earth's magnetic field, the output voltages of the magnetoelectric conversion elements 20 and 40 are either the same positive voltage or the same negative voltage, so they are canceled out by calculating the difference. The current sensor 10 can obtain higher sensitivity to the measurement current and strong resistance to external noise.

[0100] Although described here as a modification of the first embodiment, the example of arranging two magnetoelectric conversion elements 20 and 40 in the vicinity of the conductor 120 may also be applied to the second, third, and fourth embodiments.

[0101] 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.

[0102] 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]

[0103] 10 Current Sensor 20,40 Magnetoelectric conversion element 30, 50, 108 wires 71,72 Resin sealing mold 100 Signal Processing ICs 112 IC support part 112c extension 112d extension 113 Bending section 114 Element support section 21,115,116 Adhesive layer 120 conductor 130 Sealing part 140 Lead terminals 140a Slit 140b Step section 150, 150a, 150b lead terminals 152 recess 162 Convex part 160 Hanging pins 200,250 lead frames

Claims

1. At least one magnetoelectric conversion element, A conductor through which the measurement current measured by the at least one magnetoelectric conversion element flows, which at least partially surrounds the at least one magnetoelectric conversion element in a plan view, A signal processing IC that processes the signal output from at least one magnetoelectric conversion element, An IC support portion having a gap for electrically insulating the conductor, a first surface and a second surface opposite to the first surface, and supporting the signal processing IC on the first surface, An element support portion, which is made of a metal plate or a semiconductor substrate and supports the at least one magnetoelectric conversion element on the same side as the first surface, A sealing portion that seals the at least one magnetoelectric conversion element, the conductor, and the signal processing IC, A pair of first lead terminals are provided, which are partially exposed on the side surface of the sealing portion, electrically connected to the conductor, input the measured current to the conductor, and output the measured current from the conductor. A portion of the side surface of the sealing portion is exposed, and a plurality of second lead terminals are electrically connected to the signal processing IC. Equipped with, The element support portion is positioned opposite the same side of the conductor as the second surface, overlaps with the conductor when viewed from the thickness direction of the element support portion, and does not overlap with the conductor when viewed from a direction intersecting the thickness direction. At least one of the plurality of second lead terminals, the element support portion, and the IC support portion are connected to each other in a plan view and are integrally formed. A current sensor in which the IC support portion and the element support portion, or at least one of the plurality of second lead terminals and the IC support portion are connected via a bent portion that bends in the thickness direction such that the surface of the element support portion on the same side as the first surface and the surface on the same side as the second surface of the conductor are spaced apart.

2. The current sensor according to claim 1, wherein the conductor has a stepped portion such that, in the thickness direction, the surface on the same side as the first surface of the element support portion and the surface on the same side as the second surface of the conductor are spaced apart.

3. The sealing portion further comprises a metal member that is partially exposed on the side surface and spaced apart from the conductor, The current sensor according to claim 1, wherein the metal member is separate from the plurality of second lead terminals and is not electrically connected to the signal processing IC.

4. At least one magnetoelectric conversion element, A conductor through which the measurement current measured by the at least one magnetoelectric conversion element flows, which at least partially surrounds the at least one magnetoelectric conversion element in a plan view, A signal processing IC that processes the signal output from at least one magnetoelectric conversion element, An IC support portion having a gap for electrically insulating the conductor, a first surface and a second surface opposite to the first surface, and supporting the signal processing IC on the first surface, An element support portion, which is made of a metal plate or a semiconductor substrate and supports the at least one magnetoelectric conversion element on the same side as the first surface, A sealing portion that seals the at least one magnetoelectric conversion element, the conductor, and the signal processing IC, A pair of first lead terminals are provided, which are partially exposed on the side surface of the sealing portion, electrically connected to the conductor, input the measured current to the conductor, and output the measured current from the conductor. A portion of the side surface of the sealing portion is exposed, and a plurality of second lead terminals are electrically connected to the signal processing IC, A metal member is partially exposed on the side surface of the sealing portion and is spaced apart from the conductor, Equipped with, The element support portion is positioned opposite the same side of the conductor as the second surface, overlaps with the conductor when viewed from the thickness direction of the element support portion, and does not overlap with the conductor when viewed from a direction intersecting the thickness direction. At least one of the plurality of second lead terminals, the element support portion, and the IC support portion are connected to each other in a plan view and are integrally formed. The aforementioned metal member is separate from the plurality of second lead terminals and is not electrically connected to the signal processing IC. The plurality of second lead terminals, the IC support portion, the element support portion, and the metal member are integrally formed by the first lead frame. A current sensor in which the pair of first lead terminals and the conductor are integrally formed by a second lead frame.

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