Current sensor, and method for manufacturing a current sensor
Patent Information
- Application Number
- JP2025273926
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-04-04
- Filing Date
- 2025-12-22
- Publication Date
- 2026-10-16
Smart Images
Figure 2026169131000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a current sensor and a method for manufacturing the current sensor.
Background Art
[0002] Patent Document 1 describes manufacturing a current sensor by covering the upper surface side with a first sealing member and covering the lower surface side with a second sealing member. Patent Document 2 describes a current sensor that includes a plate-shaped support portion that supports a magnetoelectric conversion element and a signal processing IC on the ceiling surface side of a sealing portion and is spaced apart from a conductor. [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent No. 6971908 Specification [Patent Document 2] Japanese Patent No. 7329118 Specification
Summary of the Invention
Problems to be Solved by the Invention
[0003] There is a demand for a current sensor that can secure a creepage distance, prevent the occurrence of cracks or the like in a sealing portion, ensure withstand voltage, and can be miniaturized.
Means for Solving the Problems
[0004] A current sensor according to one aspect of the present invention may include at least one magnetoelectric element. The current sensor may include a current 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 include a signal processing IC that processes a signal output from the at least one magnetoelectric element. The current sensor may include a support portion that supports the surface of the at least one magnetoelectric element opposite to the magnetic surface and the surface of the signal processing IC opposite to the circuit surface as a first surface. The current sensor may include a signal conductor that is connected to the circuit surface of the signal processing IC via electrical wiring and transmits a signal output from the signal processing IC. The current sensor may include an integrally configured sealing portion that seals the at least one magnetoelectric element, a part of the current conductor, the electrical wiring, the signal processing IC, a part of the signal conductor, and at least a part of the support portion. When the support portion facing the first surface is designated as the second surface, at least two of the first surface, the second surface, and the side surface of the support portion may be in contact with the sealing portion without being exposed from the sealing portion. The current conductor may have its first terminal surface exposed from the first surface of the sealing portion facing the first surface of the support portion, and its second terminal surface exposed from the second surface continuous with the first surface of the sealing portion. The signal conductor may have its third terminal surface exposed from the first surface of the sealing portion, and its fourth terminal surface exposed from the third surface opposite to the second surface of the sealing portion. The second surface and the second terminal surface of the sealing portion may be located substantially on the same plane. The third surface and the fourth terminal surface of the sealing portion may be located substantially on the same plane.
[0005] In the current sensor, the first surface, the first terminal surface, and the third terminal surface of the sealing portion may be located substantially on the same plane.
[0006] In any of the current sensors, the sealing portion may contain an inorganic filler.
[0007] In any of the current sensors, the sealing portion does not need to have an internal interface within the sealing portion that substantially does not cross the filler.
[0008] In any of the current sensors, the signal conductor may be in contact with the first surface of the support portion.
[0009] In any of the current sensors, a cross-section of the filler may be present on the surface of the sealing portion.
[0010] In any of the current sensors, the sealing portion may have a fourth surface opposite to the first surface, a fifth surface, and a sixth surface opposite to the fifth surface. The fifth and sixth surfaces do not need to expose an internal interface of the sealing portion that substantially does not cross the filler.
[0011] In any of the current sensors, the sealing portion may have a fourth surface opposite to the first surface, a fifth surface, and a sixth surface opposite to the fifth surface. The cross-sections of the filler on the fifth and sixth surfaces of the sealing portion may be exposed in the same proportion as the filling rate of the filler in the sealing portion, within a range of 5%.
[0012] The current sensor according to claim 1, wherein in any of the current sensors, when the minimum distance along the first surface of the sealing portion between the first terminal surface and the third terminal surface is defined as the creepage distance, the creepage distance is 79% or more of the length of the sealing portion in the direction along the creepage distance.
[0013] When the creepage distance is defined as the minimum distance along the first surface of the sealing portion between the first terminal surface and the third terminal surface, the creepage distance may be 85% or more of the length of the sealing portion in the direction along the creepage distance.
[0014] In any of the above-mentioned current sensors, if the creepage distance is defined as the minimum distance along the first surface of the sealing portion between the first terminal surface and the third terminal surface, the creepage distance may be 8 mm or less.
[0015] In any of the current sensors, among the members sealed in the sealing portion, the only members exposed from the surface of the sealing portion are the first and second terminal surfaces of the current conductor and the third and fourth terminal surfaces of the signal conductor.
[0016] In any of the current sensors, at least a portion of the second surface of the current conductor opposite to the first surface on the same side as the first surface of the sealing portion and the first surface of the support portion may be located on the same plane.
[0017] In any of the current sensors, the current conductor may have a stepped portion such that the second surface opposite to the first surface facing the first surface of the sealing portion is separated from the first surface of the support portion.
[0018] In any of the current sensors, the sealing portion seals the support portion, and the support portion does not need to be exposed from the sealing portion.
[0019] In any of the current sensors, the sealing portion seals a part of the support portion, the support portion is insulating, and the end of the support portion may be exposed from the sealing portion.
[0020] In any of the current sensors, the sealing portion may have a fourth surface opposite to the first surface, a fifth surface, and a sixth surface opposite to the fifth surface. The exposed surface of the end portion exposed from the sealing portion may be coplanar with the fifth or sixth surface of the sealing portion.
[0021] In any of the current sensors, the support portion may be separated from both the current conductor and the signal conductor, and a portion of the sealing portion may be present between the current conductor and the signal conductor.
[0022] In any of the current sensors, the magnetoelectric conversion element and the signal processing IC are connected by a wire, and the current conductor may have a curvature with a radius of 20% or more of the thickness of the plate of the current conductor at a position facing the wire.
[0023] In any one of the current sensors, the sealing portion may have a fourth surface opposite to the first surface. A plane where the ratio of the filler area to the area of the sealing portion is equal to or less than half of the average filling rate of the filler in the mold resin constituting the sealing portion, among the planes existing inside or on the surface of the sealing portion, may exist only on the first surface and the fourth surface.
[0024] In any one of the current sensors, the magnetosensitive surface of the magnetoelectric conversion element and the circuit surface of the signal processing IC are arranged facing the first terminal surface and the second terminal surface side, and the distance between the magnetosensitive surface and the first surface of the sealing portion may be smaller than the thickness of the lead frame.
[0025] Any one of the current sensors may further include a substrate on which the current sensor is mounted by solder, and a metal plate may be disposed at a position on the substrate that faces the magnetoelectric conversion element.
[0026] In any one of the current sensors, the sealing portion may have a fourth surface opposite to the first surface, a fifth surface of the sealing portion sharing edges with both the first surface and the fourth surface, and a sixth surface opposite to the fifth surface. Among the first surface, the fourth surface, the fifth surface, and the sixth surface of the sealing portion, only an insulator may be present at a portion sandwiched between the first terminal surface and the third terminal surface in top view.
[0027] In any one of the current sensors, the current conductor has a step in a direction away from the support portion in side view, the support portion exists only between the step and the third terminal surface in plan view, and the end surface of the support portion may overlap the end portion of the signal conductor.
[0028] In any one of the current sensors, in top view, the support portion may be separated from the signal conductor.
[0029] A method for manufacturing a current sensor according to one aspect of the present invention may include the step of preparing a lead frame in which a plurality of sets of current conductors through which a measurement current measured by at least one magnetoelectric conversion element flows, and signal conductors that transmit signals output from a signal processing IC that processes signals output from at least one magnetoelectric conversion element, wherein the first surface of a support portion is partially bonded to the second surface of the lead frame. The manufacturing method may include the step of arranging the at least one magnetoelectric conversion element on the first surface of the support portion such that, in a plan view, it is at least partially surrounded by the current conductor, and arranging the signal processing IC at a position different from the position where the at least one magnetoelectric conversion element is arranged on the first surface of the support portion. The manufacturing method may include the step of electrically connecting the at least one magnetoelectric conversion element and the signal processing IC by electrical wiring, and electrically connecting the signal processing IC and the signal conductor by electrical wiring. The manufacturing method may include the step of attaching a film to the first surface of the lead frame opposite to the second surface. The manufacturing method may include the step of placing the lead frame in the cavity of the mold, with a gap formed between the cavity and the support portion. The manufacturing method may include the step of filling the cavity with molding resin and sealing the at least one magnetoelectric conversion element, the signal processing IC, the support portion, and the electrical wiring with the molding resin. The manufacturing method may include the step of removing the film from the first surface of the lead frame sealed with the molding resin. The manufacturing method may include the step of cutting the lead frame sealed with the molding resin into individual pieces.
[0030] In the above manufacturing method, the cavity of the mold may be flat over the region of the multiple current sensors.
[0031] In any of the above manufacturing methods, the lead frame may be formed by etching.
[0032] In any of the above manufacturing methods, a step may be provided after the step of removing the film to remove organic matter from the surface of the lead frame that is exposed.
[0033] It should be noted that the above summary of the invention does not enumerate all of its features. Subcombinations of these features may also constitute an invention. [Brief explanation of the drawing]
[0034] [Figure 1] This is a magnified view of a portion of the sealed area when the mold sealing process is performed twice. [Figure 2A] This is a schematic plan view of the current sensor according to the first embodiment, as seen from the mounting surface side (z-axis direction). [Figure 2B] Figure 2A is a cross-sectional view of the current sensor shown along line AA. [Figure 3] This is a magnified view of the electrical connection between the magnetoelectric conversion element and the signal processing IC. [Figure 4A] This is a schematic plan view of the current sensor according to the second embodiment, as seen from the mounting surface side (z-axis direction). [Figure 4B] Figure 4A is a cross-sectional view of the current sensor shown along line AA. [Figure 5A] This is a schematic plan view of the current sensor according to the third embodiment, as seen from the mounting surface side (z-axis direction). [Figure 5B] Figure 5A is a cross-sectional view of the current sensor shown along line AA. [Figure 6A] This is a schematic plan view of the current sensor according to the fourth embodiment, as seen from the mounting surface side (z-axis direction). [Figure 6B] Figure 6A is a cross-sectional view of the current sensor shown along line AA. [Figure 7A] This is a schematic plan view of the current sensor according to the fifth embodiment, as seen from the mounting surface side (z-axis direction). [Figure 7B] Figure 7A is a cross-sectional view of the current sensor shown along line AA. [Figure 8A] This is a schematic plan view of the current sensor according to the sixth embodiment, as seen from the mounting surface side (z-axis direction). [Figure 8B] Figure 8A is a cross-sectional view of the current sensor shown along line AA. [Figure 9A] This is a schematic plan view of the current sensor according to the seventh embodiment, as seen from the mounting surface side (z-axis direction). [Figure 9B] Figure 9A is a cross-sectional view of the current sensor along line AA. [Figure 10] This is a schematic diagram of the seventh embodiment in which two magnetoelectric conversion elements are arranged. [Figure 11A] This is a diagram illustrating the manufacturing method of a current sensor. [Figure 11B] This is a diagram illustrating the manufacturing method of a current sensor. [Figure 12A] This is a plan view of the state after completing step 2 in order to realize the first embodiment. [Figure 12B] This is a plan view of the state after completing step 2 in order to realize the seventh embodiment. [Figure 13] This is a cross-sectional view showing an example of a current sensor mounted on a circuit board. [Modes for carrying out the invention]
[0035] The present invention will be described below through embodiments, but these embodiments are not intended to limit the scope of the claims. Not all combinations of features described in the embodiments are necessarily essential to the solution of the invention.
[0036] The current sensor comprises a current conductor through which the current to be measured flows, a magnetoelectric conversion element that detects the magnetic field generated by the measured current, and a signal processing IC that amplifies the signal from the magnetoelectric conversion element and outputs it externally. The current conductor, magnetoelectric conversion element, and signal processing IC are encapsulated in resin to form a single semiconductor package.
[0037] For example, Patent Document 1 discloses a method for manufacturing a current detection device, comprising the steps of: arranging a conductor through which the current to be measured flows and a magnetic sensor for detecting a magnetic field generated by the current flowing through the conductor at a distance from each other on a support member; sealing at least a portion of the conductor and the upper surface of the magnetic sensor with a first sealing member; removing the support member; and sealing at least a portion of the conductor and the bottom surface of the magnetic sensor with a second sealing member.
[0038] As in the manufacturing method described in Patent Document 1, when the sealing portion is composed of a first sealing member and a second sealing member, the molding sealing process must be performed twice. Furthermore, by performing the molding sealing process twice, an interface 133 is formed between the molded resin layer 132 formed in the first molding sealing process and the molded resin layer 131 formed in the second molding sealing process, as shown in Figure 1. The presence of the interface 133 may lead to delamination or cracking at the interface 133.
[0039] Furthermore, as shown in Patent Document 2, if the terminals protrude from the side of the sealing portion, the entire current sensor becomes larger.
[0040] Taking the above into consideration, the current sensors according to each embodiment provide current sensors that can maintain creepage distance even when miniaturized and have high pressure resistance performance that can suppress the occurrence of delamination or cracks within the sealed portion.
[0041] Figures 2A and 2B show the internal configuration of the current sensor 10 according to the first embodiment. Figure 2A is a schematic plan view of the current sensor 10 according to the first embodiment, as seen from the mounting surface side (z-axis direction). Figure 2B is a cross-sectional view of the current sensor 10 shown in Figure 2A, along line AA.
[0042] The current sensor 10 comprises a signal processing IC 100, a magnetoelectric conversion element 20, a support part 110, a sealing part 130, a current conductor 140, and a signal conductor 150. 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 signal conductor 150 via a wire 108.
[0043] The sealing portion 130 seals the magnetoelectric conversion element 20, the signal processing IC 100, the support portion 110, a part of the current conductor 140, a part of the signal conductor 150, the wire 30, and the wire 108 with resin. The resin may be, for example, an epoxy-based thermosetting resin with silica added. The pair of current conductors 140 are the lead terminals on the primary side. The signal conductors 150 are a plurality of lead terminals on the secondary side.
[0044] In Figure 2A, 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.
[0045] The magnetoelectric conversion element 20 detects 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 the signal conductor 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 in a plan view from the z-axis direction. The magnetoelectric conversion element 20 may be a longitudinal magnetic field detection element, for example, a Hall element that utilizes the Hall effect and has a sensitivity axis in a direction intersecting the magnetosensitive surface. The magnetoelectric conversion element 20 may also be a transverse magnetic field detection element, for example, a magnetoresistive element or fluxgate element that detects a magnetic field in any one axis direction on the xy plane along the magnetosensitive surface. The magnetoresistive element may be, for example, a semiconductor magnetoresistive element (SMR), an anomaly magnetoresistive element (AMR), a giant magnetoresistive element (GMR), or a tunnel magnetoresistive element (TMR).
[0046] 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.
[0047] The current conductor 140 has a U-shape in plan view and a slit 144 extending in the y-axis direction in its central portion. The magnetoelectric conversion element 20 is placed within the slit 144. The current conductor 140 surrounds at least partially the sides of the magnetoelectric conversion element 20, and the measurement current measured by the magnetoelectric conversion element 20 flows through it. The current conductor 140 may surround at least three sides of the magnetoelectric conversion element 20.
[0048] The signal processing IC 100 is a large-scale integrated circuit (LSI). The signal processing IC 100 is electrically connected to the magnetoelectric conversion element 20 via wire 30. The signal processing IC 100 is cut into a rectangular or square shape in plan view. Furthermore, the signal processing IC 100 is electrically connected to at least two of the multiple lead terminals constituting the signal conductor 150 via wire 108. Wires 30 and 108 may be formed from a conductive material mainly composed of Au, Ag, Cu, or Al. Wire 30 is an example of electrical wiring.
[0049] 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 signal conductor 150 indicating the current value of the measured current flowing through the current conductor 140. The signal processing circuit of the signal processing IC 100 is equipped with a circuit that takes a small output signal corresponding to the magnitude of the magnetic field of the magnetoelectric conversion element as input and amplifies the input signal at least. The signal processing circuit of the signal processing IC 100 may include a circuit that corrects the characteristics of the magnetoelectric conversion element 20 according to temperature or stress.
[0050] The current conductor 140 constitutes a pair of lead terminals 143a and 143b. The measured current is input from one lead terminal 143a of the pair of lead terminals 143a and 143b, and the measured current is output from the other lead terminal 143b. Each of the pair of lead terminals 143a and 143b may have a tip portion divided into multiple parts. That is, on the surface of the current sensor 10, the exposed surfaces of the pair of lead terminals 143a and 143b may each be divided into multiple terminal surfaces.
[0051] The measured current flowing through the current conductor 140 flows along the U-shape from one end to the other. This generates a magnetic field around the current conductor 140, which is determined by the magnitude of the measured current and the distance from the current conductor 140. At the position 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 144, high sensitivity to the measured current can be obtained.
[0052] The signal conductor 150 has multiple lead terminals that transmit signals output from the signal processing IC 100. The signal conductor 150 may be made up of a lead frame of a conductive material mainly composed of copper, together with the current conductor 140.
[0053] The support portion 110 is a sheet-like member that supports the magnetoelectric conversion element 20 and the signal processing IC 100 on the mounting surface side 110a of the sealing portion 130, and is separated from the current conductor 140. At least a portion of the terminal surface 140a of the current conductor 140 on the same side as the surface 130e of the sealing portion 130 and the opposite side surface 140d of the current conductor 140 are on the same plane as the surface 130a of the sealing portion 130 and the surface 110a of the support portion 110. However, the current conductor 140 has a stepped portion 142 in a direction that separates it from the support portion 110 so as not to come into contact with the support portion 110. That is, the current conductor 140 has a stepped portion 142 such that the surface 110a of the support portion 110 and the surface 140c of the current conductor 140 facing surface 110a are separated in the thickness direction of the current conductor 140. Therefore, the support portion 110 and the stepped portion 142 do not overlap, and the support portion 110 is located on the signal conductor 150 side. The stepped portion 142 may be provided on the current conductor 140 by half-etching or half-through processing so that the support portion 110 and the current conductor 140 do not come into contact. If the stepped portion 142 is formed by half-etching, there is no need to prepare a special mold when forming the lead frame, and efficient manufacturing is possible. If the stepped portion 142 is formed by half-through processing, the thickness of the current conductor 140 can be maintained, and heat generation when the measured current is passed through can be suppressed. In this case, the stepped portion 142 is located in a position that does not overlap with the terminal surface 140a when viewed from the z-axis direction, that is, in a part where the thickness of the lead frame is thin, so that the area of the terminal surface can be sufficiently secured, and mounting the current sensor 10 to the substrate becomes easier. By providing the stepped portion 142, it becomes easier to maintain pressure resistance in the event of delamination between the mold resin and the support portion 110 compared to when the support portion 110 and the current conductor 140 are in contact. Since the support portion 110 is held by the signal conductor 150, the end face of the support portion 110 and the end face of the signal conductor 150 may overlap in a plan view.
[0054] The current conductor 140 and the signal conductor 150 may be formed by half-etching the lead frame. When formed by half-etching, the edges of the etched portion are rounded. The radius of the rounding depends on the thickness of the lead frame and is 20% or more of the thickness h1 of the portion of the current conductor 140 that is thinner than other portions, i.e., the thickness h1 of the portion 1401 sealed within the sealing portion 130.
[0055] Figure 3 is an enlarged view of the electrical connection between the magnetoelectric conversion element 20 and the signal processing IC 100. When the current conductor 140 is formed by half-etching, the edges 145 become rounded. When the edges 145 are rounded, the wire 30 connecting the magnetoelectric conversion element 20 and the signal processing IC 100 is less likely to come into contact with the current conductor 140. In other words, the withstand voltage between the magnetoelectric conversion element 20 or the signal processing IC 100, or a signal processing system comprising the magnetoelectric conversion element 20 and the signal processing IC 100, and the current conductor 140 can be improved.
[0056] The support portion 110 is on the same side 110a as the mounting surface 130e of the sealing portion 130, and contacts the surface 150d of the signal conductor 150 opposite to the surface 150c of the sealing portion 130 that faces surface 130e. The signal conductor 150 may be bonded to the surface 110a of the support portion 110 via an adhesive layer, similar to the magnetoelectric conversion element 20 and the signal processing IC 100. The support portion 110 may be made of an insulating material with a low modulus of elasticity, such as a polymer tape like polyimide tape. The support portion 110 may be made of a material such as silicon, whose coefficient of linear expansion is close to that of the signal processing IC or the magnetoelectric conversion element 20, and connected to the lead frames constituting the current conductor 140 and the signal conductor 150 via an adhesive. The support portion 110 may be made of a material with a thickness of less than 0.1 mm. This reduces the stress acting on the signal processing IC due to changes in heat generated within the sealing portion 130.
[0057] The current sensor 10 is a SON-type semiconductor package, similar to the current sensor shown in Patent Document 1. More specifically, the current conductor 140 has a terminal surface 140a exposed from the mounting surface 130e of the sealing portion 130, which is opposite the surface 100a of the support portion 110, and a terminal surface 140b exposed from the side surface 130a of the sealing portion 130, which is continuous with the surface 130e. The terminal surface 140a and the terminal surface 140b are connected. The terminal surface 140b is a surface that extends from the terminal surface 140a along the mounting surface 130e of the sealing portion 130 toward the surface 130f of the sealing portion 130, and the terminal surface 140a and the terminal surface 140b are continuous surfaces.
[0058] The signal conductor 150 has a terminal surface 150a exposed from the surface 130e of the sealing portion 130, and a terminal surface 150b exposed from the side surface 130b of the sealing portion 130 opposite to surface 130a. The terminal surface 150b is a surface that extends from the terminal surface 150a, which is along the mounting surface 130e of the sealing portion 130, toward the surface 130f of the sealing portion 130, and the terminal surface 150a and the terminal surface 150b are continuous surfaces.
[0059] The surface 130e of the sealing portion 130, the terminal surface 140a of the current conductor 140, and the terminal surface 150a of the signal conductor 150 are located substantially on the same plane or on the same plane. The terminal surfaces 140a and 150a may protrude from the surface 130e of the sealing portion 130 by a thickness of 50 μm or less or 20 μm or less, for example, by being coated with an exterior plating made of a non-magnetic material including Sn. In this specification, if the difference in height in the z-axis direction between the terminal surface 140a of the current conductor 140, the terminal surface 150a of the signal conductor 150, and the surface 130e of the sealing portion 130 is 50 μm or less, the surface 130e of the sealing portion 130, the terminal surface 140a of the current conductor 140, and the terminal surface 150a of the signal conductor 150 may be considered to be located substantially on the same plane. Preferably, the difference in height is 20 μm or less.
[0060] The surface 130a of the sealing portion 130 and the terminal surface 140b of the current conductor 140 are located substantially on the same plane or on the same plane. The surface 130b of the sealing portion 130 and the terminal surface 150b of the signal conductor 150 are located substantially on the same plane or on the same plane. The terminal surfaces 140b and 150b may have irregularities on a part of them. Even in such cases, if at least a part of the terminal surfaces 140b and 150b is on the same plane as the surface 130a or 130b of the sealing portion and does not protrude from the surface 130a or 130b, the terminal surfaces 140b and 150b may be considered to be on the same plane as the surface 130a or 130b.
[0061] In this specification, if the height difference in the y-axis direction between the surface 130a of the sealing portion 130 and the terminal surface 140b of the current conductor 140 is 50 μm or less, the surface 130a of the sealing portion 130 and the terminal surface 140b of the current conductor 140 may be considered to be located substantially on the same plane. Preferably, the height difference is 20 μm or less.
[0062] In this specification, if the height difference in the y-axis direction between the surface 130b of the sealing portion 130 and the terminal surface 150b of the current conductor 150 is 50 μm or less, the surface 130a of the sealing portion 130 and the terminal surface 140b of the current conductor 140 may be considered to be located substantially on the same plane. Preferably, the height difference is 20 μm or less.
[0063] By making the terminal portions of the current conductor 140 and the signal conductor 150 have terminal surfaces that are coplanar with the outer surface of the sealing portion 130, it is easier to miniaturize the device compared to a current sensor that has terminals protruding from the sealing portion 130.
[0064] Since the terminal surfaces 140a and 140b of the current conductor 140 do not protrude from the sealing portion 130 in the planar direction, the distance between the terminal surfaces and the magnetoelectric conversion element 20 is reduced, and heat generation of the current conductor 140 due to the measured current can be suppressed.
[0065] The circuit surface of the signal processing IC 100 and the magnetosensitive surface of the magnetoelectric conversion element 20 are surrounded on two sides by terminals 140 and 150. Therefore, electromagnetic fields from the outside are blocked by the terminals, providing a shielding effect. Furthermore, the magnetosensitive surface of the magnetoelectric conversion element 20 faces the direction of terminal surfaces 140a and 150a. Therefore, when mounted on a substrate via solder, by placing a metal plate on the substrate at a position opposite the magnetosensitive surface, electromagnetic fields from the surface can also be blocked. An example is shown in Figure 13. In Figure 13, the current sensor 10 is electrically connected to the substrate 200 via solder 202 at terminal surfaces 140a and 150a. The substrate 200 incorporates a metal plate 210 at a position that overlaps with the magnetoelectric conversion element 20 in the thickness direction (z-axis direction). The metal plate 210 may be made of a conductive material mainly composed of copper. By placing the metal plate 210 in the inner layer of the substrate 200, creepage distance can be ensured. The metal plate 210 can be the wiring installed on the circuit board 200.
[0066] The terminal surface 140a of the current conductor 140 and the terminal surface 150a of the signal conductor 150 may be plated with tin. The terminal surfaces 140a and 140b of the current conductor 140, and the terminal surfaces 150a and 150b of the signal conductor 150 may be plated with tin.
[0067] Of the components sealed in the sealing portion 130, only the terminal surfaces 140a and 140b of the current conductor 140, and the terminal surfaces 150a and 150b of the signal conductor 150 are exposed from the surface of the sealing portion 130. The sealing portion 130 seals the support portion 110, and the support portion 110 is not exposed from the sealing portion 130.
[0068] Furthermore, if the creepage distance L1 is defined as the minimum distance along the surface 100e of the sealing portion 130 between the terminal surface 140a of the current conductor 140 and the terminal surface 150a of the signal conductor 150, then the creepage distance L1 is 79% or more of the length L2 of the sealing portion 130 in the direction along the creepage distance. For example, if the length L3 of the terminal surface 140a in the y-axis direction and the length L4 of the terminal surface 150a in the y-axis direction are 0.4 mm or less, then the creepage distance L1 can be 3 mm or more. This allows the creepage distance to be secured in a small space. The creepage distance L1 can be 8 mm or less.
[0069] More preferably, when the creepage distance L1 is defined as the minimum distance along the surface 100e of the sealing portion 130 between the terminal surface 140a of the current conductor 140 and the terminal surface 150a of the signal conductor 150, the creepage distance L1 is 85% or more of the length L2 of the sealing portion 130 in the direction along the creepage distance. For example, the length L3 of the terminal surface 140a in the y-axis direction and the length L4 of the terminal surface 150a in the y-axis direction are 0.3 mm or less, and the creepage distance L1 may be 3.4 mm or more. This allows the creepage distance to be secured in a small space. The creepage distance L1 may be 8 mm or less.
[0070] The creepage distance L1 is preferably the shortest distance between terminal surfaces 140a and 150a. Here, if a conductor is exposed in the area between terminal surfaces 140a and 150a when viewed from above, among surfaces 130e, 130f, 130c, and 130d which share edges with both surfaces 130e and 130f, the creepage distance will be reduced. For example, if a suspension lead is present on surface 130c or 130d, the creepage distance will be reduced by the width corresponding to the suspension lead. Therefore, no conductor is exposed between terminal surfaces 140a and 150a. That is, among surfaces 130e, 130f, 130c, and 130d which share edges with both surfaces 130e and 130f, only an insulator is present in the area between terminal surfaces 140a and 150a when viewed from above. Since the current sensor 10 is in an SON-type package, it can be fixed to the dicing tape during individual piece formation even without the presence of suspension leads. This prevents the current sensor 10 from scattering.
[0071] The thickness h1 of the portion of the current conductor 140 that is thinner than the other portions, i.e., the portion 1401 sealed within the sealing portion 130, is thicker than the thickness h2 of the portion of the signal conductor 150 that is thinner than the other portions, i.e., the portion sealed within the sealing portion 130. This reduces the resistance of the current conductor 140 and suppresses the heat generated when current flows through the current conductor 140.
[0072] The thickness of portion 1501 of the signal conductor 150 can be less than half the thickness h3 of the lead frame constituting the current conductor 140 and the signal conductor 150. This allows portion 1501 of the signal conductor 150 to be easily realized by etching. The thickness h2 of portion 1501 of the signal conductor 150 can be made thinner than the thickness h4 of the signal processing IC 100. This allows a step in the z-axis direction to be created between the portion of the signal processing IC 100 that connects the wires 108 and the portion of the signal conductor 150 that connects the wires 108. This makes it easier to connect the wires 108 and the signal conductor 150.
[0073] Furthermore, it is preferable to silver-plate the portion of the signal conductor 150 that connects to the wire 108. This suppresses fluctuations in sensitivity due to magnetism during the plating process.
[0074] The sealing portion 130 contains an inorganic filler. The sealing portion 130 is manufactured in a single mold sealing process, as shown in the manufacturing method of the current sensor 10 described later, and the entire sealing portion 130 is integrally constructed. As a result, there are virtually no interfaces in the sealing portion 130 that do not cross the filler. Here, "there are virtually no interfaces that do not cross the filler" means that there are no interfaces in the sealing portion 130 that do not cross the filler, extending over 95% or more, or 99% or more, of the width or height of the sealing portion 130, as shown in Figure 1. In other words, even if such interfaces exist in the sealing portion 130 at a rate of less than 1% or less than 5% of the width or height of the sealing portion 130, it can still be said that "there are virtually no interfaces that do not cross the filler."
[0075] According to Patent Document 1, an internal sealing interface is formed between the sealing portion formed by the first sealing and the sealing portion formed by the second sealing. The internal sealing interface is a plane that the filler contained in the sealing portion may touch but does not cross. The internal sealing interface is substantially parallel to the width or height direction of the sealing portion 130. Furthermore, since the filler only touches and does not cross the plane containing this interface, the ratio of the filler area at the sealing interface to the sealing portion is very small with respect to the filler filling rate of the sealing resin. For example, the ratio of the filler area to the area of the sealing resin in this plane is 5% or less of the filler filling rate when no surface grinding is performed after the first sealing. If grinding is performed after the first sealing to remove foreign matter or modify the surface, the filler is more likely to be exposed at the interface. Even in that case, the filler significantly slows down the grinding rate, so it is reasonable that the grinding is less than the radius of the filler. Therefore, the ratio of the filler area at the sealing interface to the sealing portion is 50% or less of the filler filling rate.
[0076] The current sensor 10 is manufactured by individualizing it, as described in the manufacturing method below. Therefore, the surface of the sealing portion 130, which becomes the cut surface when individualizing it (side surfaces 130a, 130b, 130c, and 130d), has a cross-section of the filler.
[0077] Since there are no interfaces inside the sealing portion 130, there are virtually no interfaces that do not cross the filler on the cut surfaces 130c and 130d. Therefore, the cross-sections of the filler on surfaces 130c and 130d are exposed to an extent equivalent to the filler filling rate of the sealing portion 130. The ratio of the area of the filler cross-section exposed from the surfaces of surfaces 130c and 130d to the area of surfaces 130c and 130d is within a range that is not statistically significant with respect to the filler filling rate inside. A range that is not statistically significant means, for example, a range where no significant difference is observed when the significance level is set to 0.05. Alternatively, the ratio of the area of the filler cross-section exposed from the surfaces of surfaces 130c and 130d to the area of surfaces 130c and 130d coincides with the filler filling rate inside within a range of 5%. Since there is no interface of the molded resin within the sealing portion 130, delamination or cracking along the interface does not occur.
[0078] Since the surfaces 130e and 130f of the sealing portion 130 are not the cutting surfaces when the product is separated into individual pieces, there are no interfaces that cross the filler, i.e., no cross-sections of the filler. However, if the surface 130e or 130f of the sealing portion 130 is surface-treated by blasting or the like, there may be interfaces that cross the filler on the surface 130e or 100f of the sealing portion 130. In that case as with the sealing portion interface, the ratio of the filler area at the sealing portion interface to the sealing portion is 50% or less of the filler filling rate.
[0079] The internal interface of the sealing portion, or surfaces 130e and 130f, as described above, experience local changes in Young's modulus or coefficient of thermal expansion due to variations in the filler ratio, making them susceptible to localized stress. On the other hand, Patent Document 1 has an internal interface of the sealing portion, which means that localized stress can cause problems in terms of characteristics or reliability. Furthermore, the configuration described in Patent Document 2 forms not only the surface and back surface but also a portion of the side surface of the sealing portion by filling, making it prone to similar problems. In contrast, in the current sensor 10, the only planes where the filler area relative to the area of the sealing portion is 50% or less of the filler filling rate relative to the mold resin are surfaces 130e and 130f. Therefore, the current sensor 10 is less prone to characteristic variations or reliability problems such as cracks caused by spatial fluctuations of localized stress.
[0080] Figures 4A and 4B show the internal configuration of the current sensor 10 according to the second embodiment. Figure 4A is a schematic plan view of the current sensor 10 according to the second embodiment, as seen from the mounting surface side (z-axis direction). Figure 4B is a cross-sectional view of the current sensor 10 shown in Figure 4A, along line AA.
[0081] The current sensor 10 according to the second embodiment differs from the current sensor 10 according to the first embodiment in that the current conductor 140 does not have a stepped portion 142, while the signal conductor 150 has a stepped portion 152.
[0082] The terminal surface 140a of the current conductor 140 on the same side as the surface 130e of the sealing portion 130 and the opposite surface 140d are not on the same plane as the surface 110a of the support portion 110. The signal conductor 150 is provided with a stepped portion 152 to separate it from the current conductor 140. To prevent the surface 140d of the current conductor 140 from contacting the surface 110a of the support portion 110, the height from the surface 130f of the sealing portion 130 (opposite the mounting surface 130e) to the surface 140d of the current conductor 140 is higher than the height from the surface 130f of the sealing portion 130 to the surface 110a of the support portion 110.
[0083] By not having a stepped portion 142 in the current conductor 140, heat generation associated with an increase in the resistance value of the current conductor 140 can be suppressed.
[0084] Figures 5A and 5B show the internal configuration of the current sensor 10 according to the third embodiment. Figure 5A is a schematic plan view of the current sensor 10 according to the third embodiment, as seen from the mounting side (z-axis direction). Figure 5B is a cross-sectional view of the current sensor 10 shown in Figure 5A, along line AA.
[0085] The current sensor 10 according to the third embodiment differs from the current sensor 10 according to the first embodiment in that the width of the support portion 110 in the x-axis direction is longer than the width of the support portion 110 in the x-axis direction of the current sensor 10 according to the first embodiment, and the end faces 110c and 110d of the support portion 110 are exposed from the sides of the sealing portion 130, which are surfaces 130c and 130d.
[0086] In the first embodiment, the sealing resin may apply stress to the support portion 110 during sealing, causing deformation of the signal terminal 150. By having the support portion 110 extend beyond the signal conductor 150 to the side surface of the sealing portion 130 in a plan view, the support portion 110 can be supported not only by the signal conductor 150 but also by the entire lead frame, thereby suppressing deformation of the signal conductor 150. In this case, by using a support portion 110 with a comparative tracking index equal to or higher than that of the sealing portion 130, surface discharge transmitted through the support portion 110 can be suppressed. Specifically, it is desirable to use polyimide or epoxy.
[0087] Figures 6A and 6B show the internal configuration of the current sensor 10 according to the fourth embodiment. Figure 6A is a schematic plan view of the current sensor 10 according to the fourth embodiment, as seen from the mounting surface side (z-axis direction). Figure 6B is a cross-sectional view of the current sensor 10 shown in Figure 6A, along line AA.
[0088] The current sensor 10 according to the fourth embodiment differs from the current sensor 10 according to the first embodiment in that the current conductor 140 and the signal conductor 150 do not have stepped portions 142 and 152, and the surface 140d of the current conductor 140 is in contact with the surface 110a of the support portion 110. With this configuration, the current conductor 140 and the signal conductor 150 can be formed by etching only one surface of the lead frame, thereby improving manufacturing efficiency.
[0089] Figures 7A and 7B show the internal configuration of the current sensor 10 according to the fifth embodiment. Figure 7A is a schematic plan view of the current sensor 10 according to the fifth embodiment, as seen from the mounting side (z-axis direction). Figure 7B is a cross-sectional view of the current sensor 10 shown in Figure 7A, along line AA.
[0090] The current sensor 10 according to the fifth embodiment differs from the current sensor 10 according to the first embodiment in that the stepped portion 142 of the current conductor 140 is formed only on the surface 140c facing the surface 110a of the support portion 110. Alternatively, the shape of the current conductor 140 and signal conductor 150 other than the stepped portion 142 may be created by etching one surface of the lead frame, and then the stepped portion 142 may be formed on the surface 140c of the current conductor 140 by coining.
[0091] Alternatively, the current conductor 140 and signal conductor 150, including the stepped portion 142, may be formed by etching both sides of the lead frame. By forming the current conductor 140 and signal conductor 150 by etching, including the stepped portion 142, the current conductor 140 and signal conductor 150 can be manufactured efficiently.
[0092] Figures 8A and 8B show the internal configuration of the current sensor 10 according to the sixth embodiment. Figure 8A is a schematic plan view of the current sensor 10 according to the sixth embodiment, as seen from the mounting surface side (z-axis direction). Figure 8B is a cross-sectional view of the current sensor 10 shown in Figure 8A, along line AA.
[0093] The current sensor 10 according to the sixth embodiment differs from the current sensor 10 according to the first embodiment in that the support portion 110 is divided into a support portion 112 that supports the magnetoelectric conversion element 20 and a support portion 114 that supports the signal processing IC 100.
[0094] If there are many areas with narrow gaps between the components sealed by the sealing portion 130, the fluidity of the molding resin deteriorates during the molding sealing process, making it difficult to fill the entire lead frame constituting the current conductor 140 and the signal conductor 150 with the molding resin. By dividing the support portion 110 into two, a gap is created between the support portion 112 and the support portion 114, allowing the molding resin to pass through this gap and improving the embedding ability of the molding resin. This improves the edge pressure of the sealing portion 130.
[0095] In the second, fourth, and fifth embodiments, the support portion 110 was described in an example where it is not exposed from the surfaces 130c and 130d of the sealing portion 130. However, the support portion 110 in the second, fourth, and fifth embodiments may be exposed from the surfaces 130c and 130d of the sealing portion 130, similar to the current sensor 10 in the third embodiment. Similarly, in the current sensor 10 in the sixth embodiment, the support portion 112 and the support portion 114 may be exposed from the surfaces 130c and 130d of the sealing portion 130, similar to the current sensor 10 in the third embodiment.
[0096] Figures 9A and 9B show the internal configuration of the current sensor 10 according to the seventh embodiment. Figure 9A is a schematic plan view of the current sensor 10 according to the seventh embodiment, as seen from the mounting surface side (z-axis direction). Figure 9B shows a cross-sectional view of the current sensor 10 shown in Figure 8A, along line AA.
[0097] The current sensor 10 according to the seventh embodiment differs from the current sensor 10 according to the first embodiment in that the support portion 110 is not in contact with the lead frames constituting the current conductor 140 and the signal conductor 150, the width of the support portion 110 in the x-axis direction is longer than the width of the support portion 110 in the x-axis direction of the current sensor 10 according to the first embodiment, and the end faces 110c and 110d of the support portion 110 are exposed from the sides of the sealing portion 130, which are surfaces 130c and 130d.
[0098] By separating the support portion 110 from the lead frames that constitute the current conductor 140 and the signal conductor 150, discharge does not occur from the signal processing IC 100 to the signal conductor 150 via the interface between the support portion 110 and the sealing portion 130.
[0099] The interface between the support portion 110 and the signal conductor 150 is often more prone to delamination than the mold resin due to differences in water absorption or thermal expansion coefficients. The absence of an interface between the support portion 110 and the signal conductor 150 offers a reliability advantage in suppressing delamination. Here, the support portion 110 and the signal conductor 150 may be separated even when viewed from above. As a result, even if the support portion 110 is pushed up by the sealing portion 130, contact with the signal conductor 150 can be avoided.
[0100] The seventh embodiment is achieved by fixing the support portion 110 to the portion of the lead frame that constitutes the current conductor 140 and the signal conductor 150 that does not remain as part of the current sensor 10, thereby creating a step. Similar to the third embodiment, the support portion 110 can be bonded to the current sensor 10 all at once rather than individually, resulting in improved manufacturing efficiency. Specifically, the material for the support portion 110 can be pulled out from a reel and bonded, eliminating the need to cut it into individual pieces for each current sensor 10 and then bond them using a specially prepared mold.
[0101] Figure 10 is a schematic diagram of the seventh embodiment in which two magnetoelectric conversion elements 20a and 20b are arranged. Magnetoelectric conversion element 20a is placed inside the slit 144, and magnetoelectric conversion element 20b is placed across the current conductor 140 from magnetoelectric conversion element 20a. This allows the effect of uniform external noise to be canceled out when the difference between them is amplified by the signal processing IC. At this time, it is desirable to partially surround the magnetoelectric conversion element 20b with the current conductor 140 so that the coupling capacitance between the wire 30 connected to magnetoelectric conversion element 20a and the current conductor 140 is equal to the coupling capacitance between the wire 30 connected to magnetoelectric conversion element 20b and the current conductor 140. When the projected area of the current conductor 140 from the z-axis direction is large in this way, it is desirable to support the support part 110 with a lead frame located outside the current sensor 10. This eliminates the need to provide the bonding portion between the support part 110 and the signal conductor 150 inside the current sensor 10, and the current sensor 10 can be made smaller.
[0102] Next, the manufacturing method of the current sensor 10 according to the first embodiment will be described with reference to Figures 11A and 11B.
[0103] In step 1, a lead frame 50 is prepared in which multiple sets of current conductors 140 and signal conductors 150 are formed, and one side 110a of a support portion 110 is bonded to the portion of one surface 50a of the lead frame 50 that corresponds to the signal conductor 150. The lead frame 50 may be prepared by forming the current conductors 140 and signal conductors 150 by etching, and then bonding one side 110a of a support portion 110, such as polyimide tape, to the portion of one surface 50a of the lead frame 50 that corresponds to the signal conductor 150. After etching the lead frame 50, a stepped portion 142 of the current conductor 140 may be formed by half-through processing or coining. After etching the lead frame 50, silver plating may be applied to the surface of the signal conductor 150 that has been thinned by etching, i.e., the surface to which the wire 108 will be connected in step 2.
[0104] In step 2, the magnetoelectric conversion element 20 is positioned on the surface 110a of the support portion 110 such that, in a plan view, it is at least partially surrounded by the current conductor 140 within a slit 144 formed in the current conductor 140, with its magnetic surface facing away from the support portion 110. The signal processing IC 100 is positioned on the surface 110a of the support portion 110 at a different location from where the magnetoelectric conversion element 20 is positioned, with its circuit surface facing away from the support portion 110. The different location on the surface 110a of the support portion 110 from where the magnetoelectric conversion element 20 is positioned is, for example, a position in a plan view that faces the magnetoelectric conversion element 20 across the U-shaped folded portion of the current conductor 140. Furthermore, the magnetic surface of the magnetoelectric conversion element 20 and the circuit surface of the signal processing IC 100 are electrically connected by wire 30, and the signal processing IC and the signal conductor 150 are electrically connected by wire 108.
[0105] In step 3, a film 180 is applied to the surface 50b of the lead frame 50 opposite to surface 50a. The film 180 may be, for example, polyimide tape. The film 180 is in contact only with the unetched surface of the lead frame 50, that is, the surface that is furthest away from surface 50a in the direction perpendicular to surface 50a. The film 180 prevents the molding resin from adhering to the terminal surface.
[0106] In step 4, the lead frame 50 with the film 180 attached is placed in the cavity of the mold 300. Furthermore, the cavity is filled with molding resin, and the magnetoelectric conversion element 20, signal processing IC 100, support part 110, wire 30, and wire 108 are sealed with the molding resin to form a sealed part 130. At this time, the cavity is flat over the entire portion of the lead frame that will be assembled as a current sensor 10, and the entire surface of the film 180 is in contact with the mold. The flat region of the cavity is flat in the region that spans multiple current sensors 10, and does not need to be flat over the entire lead frame. In this way, even if the size of the current sensor 10 is changed, it is not necessary to create a new mold. Here, the ends of the lead frame 50 are held by the mold 300 sandwiching both sides. On the other hand, the surface of the mold 300 is separated from the support portion 110 so that the support portion 110, current conductor 140, signal conductor 150, magnetoelectric conversion element 20, and signal processing IC 100 in the current sensor 10 portion are not exposed from the sealing portion 130 on the side opposite to the terminal surface. This is achieved by providing a step 302 that is larger than the thickness of the support portion 110 in one of the upper and lower molds of the mold 300. In other words, the support portion 110 is separated from the surface of the mold 300. The area in which the mold 300 holds the lead frame 50 by sandwiching it from both sides can be any area that does not form the current sensor 10, and does not necessarily have to be the end of the lead frame 50. For example, the area between the terminals that make up the current sensor 10 and the terminals that make up the adjacent current sensor 10 can be held down by the mold 300. In that case, the entire lead frame 50 can bend significantly, and it is possible to suppress resin from flowing between the film 180 and the mold 300.
[0107] Here, the step 302 of the mold 300 prevents the mold 300 from sandwiching the terminal surface of the support portion 110 and the terminal portion of the current conductor 140 or signal conductor 150 from above and below. Therefore, during sealing, no pressure is applied to the terminal surface from the mold 300, and without the film 180, the molding resin would wrap around and cover the terminal surface. Because the film 180 adheres to the terminal surfaces 140a and 150a of the lead frame 50, it prevents the molding resin from covering the terminal surfaces 140a and 150a even when no pressure is applied, making it possible to manufacture a current sensor 10 in a single sealing process that exposes the terminals from the sealing portion 130 while preventing the internal structure from being exposed.
[0108] In step 5, after the mold resin has solidified, the mold is removed from the mold 300 with the film 180 still attached.
[0109] In step 6, the film 180 is removed from the surface 50b of the lead frame 50, which is sealed with mold resin. The terminal surfaces 140a of the current conductor 140 and 150a of the signal conductor 150, which are exposed after the film 180 is removed, may be subjected to blasting to completely remove any film components. Furthermore, the terminal surfaces 140a of the current conductor 140 and 150a of the signal conductor 150 may be plated with tin.
[0110] In step 7, the lead frame 50 sealed with molded resin is cut into individual pieces to manufacture multiple current sensors 10.
[0111] Through the above process, the entire sealing portion 130 of the current sensor 10 can be integrally formed in only one molding process. As a result, when molding is performed using a molding resin containing filler, there are virtually no interfaces in the sealing portion 130 that do not cross the filler. Furthermore, although the surface of the sealing portion 130 (side surfaces 130a, 130b, 130c, and 130d, which become the cut surfaces when the product is separated into individual pieces) has a cross-section of the filler, there are no interfaces inside the sealing portion 130. Therefore, there are virtually no interfaces in the cut surfaces 130c and 130d that do not cross the filler. Consequently, the cross-section of the filler on surfaces 130c and 130d is exposed to an extent equivalent to the filler filling rate of the sealing portion 130. The cross-section of the filler in the portion of surface 130a of the sealing portion 130 where the terminal surface 140b is absent, and in the portion of surface 130b of the sealing portion 130 where the terminal surface 150b is absent, is also exposed in a manner greater than the filler filling rate of the sealing portion 130. Since there is no interface of the mold resin within the sealing portion 130, delamination or cracking along the interface does not occur.
[0112] As described above, the manufacturing method for the current sensor 10 shown in Figures 11A and 11B makes it possible to manufacture a current sensor 10 that ensures creepage distance, prevents cracks from occurring within the sealing portion 130, ensures pressure resistance, and allows for miniaturization.
[0113] Here, Figure 12A shows a plan view of the state after completing step 2 to realize the first embodiment. The support portion 110 is individually attached to the lead frame 50 for each element of the current sensor 10. In this state, the current sensor 10 can be manufactured by sealing and then cutting the dashed line portion. In the case of realizing the second, fourth, fifth, and sixth embodiments, the support portion 110 may also be individually attached to the lead frame 50 in the same manner as in Figure 12A.
[0114] Here, Figure 12B shows a plan view of the state after completing step 2 in order to realize the seventh embodiment. The support portion 110 differs from the plan view for realizing the first embodiment in that it is arranged across multiple current sensors 10. In addition, by providing a stepped portion or spacer on the lead frame 50 of the dotted line portion 52 and then attaching the support portion 110, the support portion 110 can be separated from the current conductor 140, and the support portion 110 can be separated from the signal conductor 150. In the case of realizing the third embodiment, the support portion 110 can also be arranged across multiple current sensors 10.
[0115] 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.
[0116] It should be noted that the execution order of operations, procedures, steps, and stages in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not explicitly stated as "before" or "prior to," and 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, this does not mean that it is essential to perform the operations in that order. [Explanation of Symbols]
[0117] 10 Current Sensor 20 Magnetoelectric conversion element 30,108 wires 50 Lead Frames 100 Signal Processing ICs 110,112,114 Support part 130 Sealing part 140 Current Conductor 142 Stepped section 143a, 140b Lead terminals 143a, 143b Lead terminals 144 slits 150 signal conductor 180 film 200 circuit boards 202 Solder 210 Metal plate 300 molds
Claims
1. At least one magnetoelectric conversion element, A current conductor through which the measurement current measured by the at least one magnetoelectric conversion element flows, at least partially surrounding 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, A support portion that supports the surface of at least one magnetoelectric conversion element opposite to the magnetosensitive surface and the surface of the signal processing IC opposite to the circuit surface as its first surface, A signal conductor connected to the circuit surface of the signal processing IC via electrical wiring, which transmits signals output from the signal processing IC, An integrally configured sealing portion that seals at least one magnetoelectric conversion element, a part of the current conductor, the electrical wiring, the signal processing IC, a part of the signal conductor, and at least a part of the support portion. Equipped with, When the surface of the support portion facing the first surface is designated as the second surface, at least two of the first surface, the second surface, and the side surface of the support portion are in contact with the sealing portion without being exposed from the sealing portion. The current conductor has a first terminal surface exposed from the first surface of the sealing portion facing the first surface of the support portion, and a second terminal surface exposed from a second surface continuous with the first surface of the sealing portion. The signal conductor has a third terminal surface exposed from the first surface of the sealing portion, and a fourth terminal surface exposed from the third surface opposite to the second surface of the sealing portion. The second surface and the second terminal surface of the sealing portion are located substantially on the same plane. The third surface and the fourth terminal surface of the sealing portion are located substantially on the same plane as the current sensor.
2. The current sensor according to claim 1, wherein the first surface, the first terminal surface, and the third terminal surface of the sealing portion are located substantially on the same plane.
3. The current sensor according to claim 2, wherein the sealing portion includes an inorganic filler.
4. The current sensor according to claim 3, wherein the sealing portion does not have an internal interface within the sealing portion that substantially does not cross the filler.
5. The current sensor according to claim 1, wherein the signal conductor is in contact with the first surface of the support portion.
6. The current sensor according to claim 3, wherein a cross-section of the filler is present on the surface of the sealing portion.
7. The sealing portion has a fourth surface opposite to the first surface, a fifth surface, and a sixth surface opposite to the fifth surface. The current sensor according to claim 3, wherein the fifth and sixth surfaces do not expose an internal sealing interface that substantially does not cross the filler.
8. The sealing portion has a fourth surface opposite to the first surface, a fifth surface, and a sixth surface opposite to the fifth surface. The current sensor according to claim 3, wherein the cross-sections of the filler on the fifth and sixth surfaces of the sealing portion are exposed in the same proportion as the filling rate of the filler in the sealing portion, within a range of 5%.
9. The current sensor according to claim 1, wherein the creepage distance is defined as the minimum distance along the first surface of the sealing portion between the first terminal surface and the third terminal surface, and the creepage distance is 79% or more of the length of the sealing portion in the direction along the creepage distance.
10. The current sensor according to claim 1, wherein the creepage distance is defined as the minimum distance along the first surface of the sealing portion between the first terminal surface and the third terminal surface, and the creepage distance is 85% or more of the length of the sealing portion in the direction along the creepage distance.
11. The current sensor according to claim 1, wherein the creepage distance is defined as the minimum distance along the first surface of the sealing portion between the first terminal surface and the third terminal surface, and the creepage distance is 8 mm or less.
12. The current sensor according to claim 1, wherein, of the members sealed in the sealing portion, the only members exposed from the surface of the sealing portion are the first terminal surface and the second terminal surface of the current conductor and the third terminal surface and the fourth terminal surface of the signal conductor.
13. The current sensor according to claim 1, wherein at least a portion of the second surface of the current conductor opposite to the first surface on the same side as the first surface of the sealing portion and the first surface of the support portion are located on the same plane.
14. The current sensor according to claim 1, wherein the current conductor has a stepped portion such that the second surface opposite to the first surface facing the first surface of the sealing portion is separated from the first surface of the support portion.
15. The current sensor according to claim 1, wherein the sealing portion seals the support portion, and the support portion is not exposed from the sealing portion.
16. The current sensor according to claim 1, wherein the sealing portion seals a part of the support portion, the support portion is insulating, and the end of the support portion is exposed from the sealing portion.
17. The sealing portion has a fourth surface opposite to the first surface, a fifth surface, and a sixth surface opposite to the fifth surface. The current sensor according to claim 16, wherein the exposed surface of the end portion exposed from the sealing portion is located on the same plane as the fifth or sixth surface of the sealing portion.
18. The current sensor according to claim 16, wherein the support portion is separated from both the current conductor and the signal conductor, and a portion of the sealing portion exists between both the current conductor and the signal conductor.
19. The current sensor according to claim 1, wherein the magnetoelectric conversion element and the signal processing IC are connected by a wire, and the current conductor has a curvature with a radius of 20% or more of the plate thickness of the current conductor at a position facing the wire.
20. The sealing portion has a fourth surface opposite to the first surface, The current sensor according to claim 1, wherein, among the planes on the inside or surface of the sealing portion, only the first and fourth planes exist such that the ratio of the filler area to the area of the sealing portion is half or less of the average filling rate of the filler in the mold resin constituting the sealing portion.
21. The current sensor according to claim 1, wherein the magnetosensitive surface of the magnetoelectric conversion element and the circuit surface of the signal processing IC are arranged toward the first terminal surface and the second terminal surface, and the distance between the magnetosensitive surface and the first surface of the sealing portion is less than the thickness of the lead frame.
22. The current sensor according to claim 21, further comprising a substrate on which the current sensor is mounted via solder, wherein a metal plate is arranged on the substrate at a position facing the magnetoelectric conversion element.
23. The sealing portion has a fourth surface opposite to the first surface, a fifth surface of the sealing portion that shares an edge with both the first surface and the fourth surface, and a sixth surface opposite to the fifth surface. The current sensor according to claim 1, wherein, of the first, fourth, fifth, and sixth surfaces of the sealing portion, only an insulator is present in the portion sandwiched between the first terminal surface and the third terminal surface when viewed from above.
24. The current sensor according to claim 1, wherein the current conductor has a step in a direction away from the support portion when viewed from the side, the support portion exists only between the step and the third terminal surface when viewed from above, and the end face of the support portion overlaps with the end of the signal conductor.
25. The current sensor according to claim 18, wherein, in a top view, the support portion is separated from the signal conductor.
26. A lead frame having multiple sets of current conductors through which a measurement current measured by at least one magnetoelectric conversion element flows, and signal conductors that transmit signals output from a signal processing IC that processes signals output from at least one magnetoelectric conversion element, wherein the lead frame is prepared such that the first surface of a support portion is partially bonded to the second surface of the lead frame. The steps include: arranging the at least one magnetoelectric conversion element on the first surface of the support portion such that, in a plan view, it is at least partially surrounded by the current conductor, and arranging the signal processing IC at a position different from the position on the first surface of the support portion where the at least one magnetoelectric conversion element is arranged; The steps include electrically connecting the at least one magnetoelectric conversion element and the signal processing IC by electrical wiring, and electrically connecting the signal processing IC and the signal conductor by electrical wiring, The step of attaching a film to the first surface of the lead frame opposite to the second surface, The steps include: positioning the lead frame within the mold cavity, with a gap formed between the cavity and the support portion; The steps include filling the cavity with molded resin and sealing the at least one magnetoelectric conversion element, the signal processing IC, the support portion, and the electrical wiring with the molded resin, The steps include removing the film from the first surface of the lead frame sealed with the molding resin, The steps include: separating the lead frame, which is sealed with the aforementioned mold resin, into individual pieces by cutting; A method for manufacturing a current sensor equipped with the following features.
27. The method for manufacturing a current sensor according to claim 26, wherein the cavity of the mold is flat over the region of the plurality of current sensors.
28. The method for manufacturing a current sensor according to claim 26, wherein the lead frame is formed by etching.
29. The method for manufacturing a current sensor according to claim 26, further comprising the step of removing organic matter from the surface of the lead frame that is exposed, after the step of removing the film.