Method for manufacturing coil component, coil component, coil component intermediate, electricity transmission device, electricity reception device, and power transfer system

Abstract

A method for manufacturing a coil component (10) according to one embodiment of the present invention involves preparing a die which has a plate-like body portion (101) and a spiral-shaped protrusion protruding from the surface of the body portion, and which has formed therein one or more cutouts that are indented from the apical end of the protrusion and open from an inner lateral surface of the protrusion, the inner lateral surface being located on the center side of the spiral shape of the protrusion, and from an outer lateral surface disposed on the opposite side of the inner lateral surface. A spiral-shaped planar coil is mounted on the surface of the body portion of the die so as to lie along the protrusion. A molten molding material is mounted so as to cover the planar coil and the die. Then, the molding material is hardened to manufacture a first coil retention member (20) that retains the planar coil (11).

Description

Coil component manufacturing method, coil component, coil component intermediate, power transmission device, power receiving device, and power transmission system

[0001] The present disclosure relates to a method for manufacturing a coil component, a coil component, a coil component intermediate, a power transmitting device, a power receiving device, and a power transfer system.

[0002] Wireless power transmission systems that transmit power in a contactless manner are becoming increasingly popular.

[0003] For example, a system is known that transmits power contactlessly by passing a high-frequency current through a resonant circuit including a coil.

[0004] When a high-frequency current flows through a coil, the skin effect can occur. The skin effect increases AC resistance, causing a decrease in transmission efficiency during power transmission. Taking this into consideration, if the coil is made of litz wire, the skin effect can be suppressed, and the decrease in transmission efficiency can be suppressed. However, because litz wire is made by twisting together many enameled wires, it is expensive to manufacture and requires a lot of effort, and the larger the coil size, the greater the manufacturing effort.

[0005] On the other hand, a technique using a spiral, plate-shaped planar coil with a rectangular conductor cross section is also known (see Patent Document 1). Such a planar coil can be formed, for example, by punching it out of a plate material. Therefore, such a planar coil can improve manufacturing efficiency regardless of the size of the coil. It is also advantageous in terms of reducing the thickness and weight of the device in which the coil is incorporated.

[0006] Japanese Patent Application Laid-Open No. 2020-47614

[0007] Patent Document 1 discloses a structure in which a magnetic body is provided between turn portions constituting a planar coil, protruding from between the turn portions in the axial direction of the planar coil. This structure can improve performance, such as the Q value. However, when a planar coil is formed from a plate material as described above, the planar coil is prone to warping. Therefore, the planar coil may be held by a plate-shaped coil holding member made of a molding material such as resin to suppress warping. Here, when the magnetic body described above and a coil holding member are used together, a groove for accommodating the magnetic body may be formed in the coil holding member.

[0008] When a groove for accommodating the protruding portion of the magnetic material is provided in the coil holding member, the groove may be formed in a spiral shape along the spiral-shaped planar coil. In this case, for example, the coil holding member may be formed using a mold having a plate-shaped base and a spiral-shaped protruding portion protruding from the base, and the groove may be formed by the protruding portion.

[0009] However, when forming the coil holding member as described above, the continuous spiral-shaped protrusions impair the flow of the molding material, particularly in the radial direction. This can cause variations in the thickness of the coil holding member. Furthermore, when continuously spiral-shaped grooves are formed in the coil holding member, the coil holding member is prone to warping during hardening of the molding material. The variations in thickness and warping of the coil holding member can result in, for example, unwanted gaps, which can impair the finish of the finished product.

[0010] In view of the above, an object of the present disclosure is to provide a method for manufacturing a coil component, a coil component, a coil component intermediate, a power transmitting device, a power receiving device, and a power transfer system that can suppress variations in thickness and warping of the coil component.

[0011] The embodiments of the present disclosure relate to the following [1] to

[12] .

[0012] [1] A method for manufacturing a coil component, comprising: preparing a mold having a plate-like main body portion and a spiral-shaped protrusion protruding from a surface of the main body portion, the protrusion being recessed from a tip thereof and having one or more notches formed in an inner surface of the protrusion located toward the center of the spiral shape formed by the protrusion and an outer surface opposite the inner surface; placing a spiral-shaped planar coil on the surface of the main body portion of the mold so as to follow the protrusion; placing a molten molding material so as to cover the planar coil and the mold; and producing an intermediate body including a first coil holding member in which a spiral-shaped groove corresponding to the protrusion is formed by hardening the molding material, and a raised portion is formed in the groove at a position corresponding to the notch so as to partially fill the groove, thereby dividing the groove or partially shallowing the depth of the groove, and the planar coil integrated with the first coil holding member.

[0013] [2] The method for manufacturing a coil component according to [1], wherein a plurality of the notches are formed in the mold, and the plurality of notches include one or a plurality of notch groups each consisting of a plurality of the notches aligned in a radial direction of the spiral shape formed by the convex portion or in a direction parallel to the radial direction.

[0014] [3] The method for manufacturing a coil component according to [2], wherein the plurality of notches include a plurality of groups of notches that are arranged at regular angles in a circumferential direction around the center of the spiral shape formed by the convex portion and that are aligned in the radial direction.

[0015] [4] The method for manufacturing a coil component according to any one of [1] to [3], wherein, when viewed in the axial direction of the spiral shape formed by the convex portion, the convex portion includes a plurality of straight portions extending linearly, and the spiral shape is formed by sequentially connecting the plurality of straight portions such that one of the adjacent straight portions is bent relative to the other, and the notch is formed between both ends of the straight portions.

[0016] [5] The method for manufacturing a coil component according to any one of [1] to [4], wherein the die is used such that the ratio of the volume of all of the notches to a reference volume obtained by adding up the volume of the convex portion and the volume of all of the notches is less than 10%.

[0017] [6] The method for manufacturing a coil component according to any one of [1] to [5], further comprising: a step of placing a molten magnetic resin material, containing a magnetic material and a resin, on the intermediate body so as to fill the groove of the first coil holding member and cover the planar coil held by the first coil holding member; and a step of hardening the magnetic resin material to fabricate a second coil holding member including a plate-shaped spacer portion extending in a radial direction of the spiral shape of the planar coil, and a spiral-shaped wall portion formed from the portion of the magnetic resin material filling the groove and protruding from the spacer portion, wherein a recess is formed in the wall portion at a position corresponding to the protrusion of the first coil holding member, the recess being recessed toward the spacer portion.

[0018] [7] The method for manufacturing a coil component according to [6], further comprising a step of stacking a second coil holding member on a magnetic shielding member formed by laying out a plurality of ferrite plates, in which the positions of the notches in the mold and the shapes of the plurality of ferrite plates are adjusted so that the boundaries between adjacent ferrite plates and the recesses in the wall portions overlap.

[0019] [8] A coil component comprising: a first coil holding member having a spiral-shaped groove formed therein and having raised portions that partially fill in and divide the groove or partially shallow the depth of the groove; a planar coil having a spiral shape that is disposed in a portion of the first coil holding member where there is no groove and that extends along the groove; and a second coil holding member that includes a plate-like spacer portion and a spiral-shaped wall portion that protrudes from the spacer portion and sandwiches the planar coil between itself and the first coil holding member, wherein the wall portion passes through the planar coil and is accommodated in the groove, and the wall portion has a recess that recesses toward the spacer portion at a position corresponding to the raised portion.

[0020] [9] A coil component intermediate comprising: a first coil holding member having a spiral-shaped groove formed therein and having a raised portion that partially fills in and divides the groove or that reduces the depth of the groove; and a spiral-shaped planar coil that is disposed in a portion of the first coil holding member where there is no groove and extends along the groove.

[0021]

[10] A power transmission device including the coil component according to [8].

[0022]

[11] A power receiving device including the coil component according to [8].

[0023]

[12] A power transfer system including a power transmitting device and a power receiving device, wherein at least one of the power transmitting device and the power receiving device includes the coil component according to [8].

[0024] According to the present disclosure, it is possible to suppress variations in thickness and warpage of coil components.

[0025] 6A is a diagram illustrating a schematic view of a wireless power transmission system to which a coil component according to an embodiment is applied. FIG. 6B is a perspective view of a coil component according to an embodiment. FIG. 6C is a plan view of the coil component shown in FIG. 2. FIG. 6D is a cross-sectional view of the coil component corresponding to line IV-IV in FIG. 3. FIG. 6E is a plan view of a first coil holding member constituting the coil component shown in FIG. 2. FIG. 6F is a partial perspective view of the first coil holding member, the second coil holding member, and the planar coil constituting the coil component shown in FIG. 2. FIG. 6G is a diagram illustrating a method for manufacturing the coil component shown in FIG. 2, and is a plan view of a mold used for manufacturing. FIG. 6H is a perspective view of the mold shown in FIG. 6A. FIG. 6I is a diagram illustrating a method for manufacturing the coil component shown in FIG. 2, and is a diagram illustrating the flow of molding material supplied to the mold. FIG. 6I is a perspective view of the mold illustrating the flow of molding material supplied to the mold. FIG. 6H is a plan view of a coil component according to a first modified example. FIG. 6I is a plan view of a coil component according to a second modified example. FIG. 6I is a plan view of a coil component according to a third modified example. FIG. 6I is a plan view of a coil component according to a fourth modified example. FIG. 6I is a plan view of a coil component according to a fifth modified example. FIG. 6I is a plan view of a coil component according to a sixth modified example. FIG. 6I is a plan view of a coil component according to a seventh modified example. FIG. 6I is a diagram illustrating the arrangement of ferrite plates in the coil component according to the seventh modified example. FIG. 6I is a diagram illustrating a graph illustrating performance evaluation results for the embodiment and multiple modified examples.

[0026] An embodiment will be described below with reference to the drawings.

[0027] In this specification, terms such as "sheet," "film," and "plate" are not distinguished from one another solely based on the difference in name. Therefore, for example, "sheet" is a concept that also includes members that can be called films or plates.

[0028] <Wireless Power Transmission System> Fig. 1 schematically shows a wireless power transmission system S to which a coil component 10 according to one embodiment is applied. First, the wireless power transmission system S to which the coil component 10 is applied (hereinafter abbreviated as power transmission system S) will be described as an example with reference to Fig. 1 .

[0029] The power transmission system S includes a power transmitting device 1 and a power receiving device 2. The power transmitting device 1 includes a coil component 10 and a high-frequency current supply unit 1A. The coil component 10 in the power transmitting device 1 functions as a power transmitting coil. The high-frequency current supply unit 1A supplies a high-frequency current to the coil component 10 serving as a power transmitting coil.

[0030] The power receiving device 2 includes a coil component 10 and a conversion unit 2A. The coil component 10 in the power receiving device 2 functions as a power receiving coil. The conversion unit 2A shapes the high-frequency current generated in the coil component 10. The conversion unit 2A includes a rectifier circuit that converts the high-frequency current into a direct current. The conversion unit 2A may be configured to include, for example, a full-wave rectifier circuit including a plurality of diodes and a smoothing capacitor.

[0031] In the present embodiment, each of the power transmitting device 1 and the power receiving device 2 includes a coil component 10. However, the coil component 10 may be used in only one of the power transmitting device 1 and the power receiving device 2, and a different type of coil component may be used in the other.

[0032] When transmitting power wirelessly (contactlessly) from the power transmitting device 1 to the power receiving device 2, the power transmitting device 1 supplies a high-frequency current of a predetermined frequency from the high-frequency current supply unit 1A to the coil component 10 serving as a power transmitting coil. At this time, a magnetic field is generated in the coil component 10 by electromagnetic induction. Then, due to the influence of this magnetic field, a high-frequency current is generated in the coil component 10 serving as a power receiving coil in the power receiving device 2. That is, the power receiving device 2 receives the magnetic field from the power transmitting device 1 or is influenced by the magnetic field at the power transmitting device 1, and causes the high-frequency current to flow by electromagnetic induction. The conversion unit 2A converts this high-frequency current into a direct current and supplies the converted direct current to, for example, a battery (not shown).

[0033] The power transmission system S shown in Fig. 1 employs a magnetic resonance method as a power transmission method. However, the coil component 10 according to the present embodiment may also be used in a power transmission system that employs an electromagnetic induction method. The power transmission system S is configured as a system that wirelessly transmits power to an electric vehicle. In this case, the power transmitting device 1 is installed on a road, in a parking lot, or the like. The power receiving device 2 is installed in the electric vehicle.

[0034] However, the use of the power transmission system S is not limited to power transmission to electric vehicles. For example, the power transmission system S may be used to transmit power to flying objects such as drones and robots. The power transmission system S may also be used to transmit power to underwater submersibles and exploration robots. The use of the coil component 10 is not limited to wireless power transmission systems. For example, the coil component 10 may be used in transformers, DC-DC converters, antennas, etc.

[0035] <Coil Component> Fig. 2 is a perspective view of the coil component 10 according to the present embodiment. Fig. 3 is a plan view of the coil component 10. Fig. 4 is a cross-sectional view of the coil component 10 taken along line IV-IV in Fig. 3.

[0036] Referring to Figures 2 to 4, the coil component 10 includes a planar coil 11, a first coil holding member 20, a second coil holding member 30, a first magnetic shield member 40, a second magnetic shield member 50, a first connection terminal 61, and a second connection terminal 62.

[0037] The planar coil 11 is held in a sandwiched state between a first coil holding member 20 and a second coil holding member 30. Fig. 2 shows a state in which the first coil holding member 20 is separated from the planar coil 11 and the second coil holding member 30. Fig. 3 does not show the first coil holding member 20. Also, Figs. 2 and 3 do not show the second magnetic shield member 50. Each part of the coil device 10 will be described in detail below.

[0038] (Planar Coil) As shown in Figures 2 to 4, the planar coil 11 is formed in a spiral shape. Specifically, the planar coil 11 includes a conductor 11E formed in a spiral shape around an arbitrary central axis C. The spiral shape refers to the shape of a plane curve that moves away from the center as it turns (or moves closer to the center as it turns). In the illustrated embodiment, the spiral shape is located on an imaginary plane perpendicular to the central axis C.

[0039] Hereinafter, the axial direction refers to a direction extending on the central axis C or a direction parallel to the central axis C. The radial direction refers to the radial direction of a circle drawn on a plane centered at an arbitrary point on the central axis C and perpendicular to the central axis C. The circumferential direction refers to the direction along a circle centered on the central axis C (the circumferential direction of the circle).

[0040] The conductor 11E is made of a conductive material. In this embodiment, the conductor 11E is made of copper, but is not limited to this. The conductor 11E may be made of a copper alloy, aluminum, an aluminum alloy, or the like. In this embodiment, the planar coil 11 is composed only of the conductor 11E. Therefore, although the planar coil 11 is made of copper, it may also be made of a copper alloy, aluminum, an aluminum alloy, or the like.

[0041] The planar coil 11 (conductor 11E) is plate-shaped. Specifically, the planar coil 11 is a planar coil made of non-litz wire. As shown in Fig. 4, the cross section of the conductor in a direction perpendicular to the winding direction of the spiral shape of the planar coil 11 (conductor 11E) is rectangular.

[0042] The planar coil 11 includes a plurality of turn portions 11n arranged in a direction perpendicular to the central axis C of the spiral shape. The conductor 11E is composed of the plurality of turn portions 11n. The plurality of turn portions 11n are connected so as to gradually move away from the central axis C radially outward from the central axis C. As a result, the plurality of turn portions 11n form a spiral shape as a whole.

[0043] The turn portions 11n are basically linear conductor portions that do not form a loop but wrap around the central axis C 360 degrees. In the case of a so-called planar coil, both ends of the turn portions 11n are offset radially. In multiple turn portions 11n, the radially outer end of one turn portion 11n is connected to the radially inner end of another turn portion 11n. This causes the multiple turn portions 11n to extend as a whole away from the central axis C. "Radially inward" means a direction that approaches the central axis C in the radial direction. Furthermore, "radially outward" means a direction that moves away from the central axis C in the radial direction.

[0044] In this embodiment, the turn portion 11n winds around to form a polygon. The term "spiral shape" as used herein and in this disclosure refers to a planar curved shape wound in a spiral shape. The planar curved shape referred to here also includes a planar pattern that winds around repeatedly while bending like a broken line, as shown in the figure. In other words, the spiral shape refers to a planar curved shape that moves away from the center as it turns (or moves closer to the center as it turns).

[0045] In the illustrated example, the planar coil 11 (conductor 11E) includes first to eighth turn portions 111 to 118. The first to eighth turn portions 111 to 118 are arranged in this order from the innermost position in the radial direction toward the outermost position. In other words, the first turn portion 111 is located at the innermost position in the radial direction, and the eighth turn portion 118 is located at the outermost position in the radial direction. In further words, the first turn portion 111 forms the innermost portion of the planar coil 11 (conductor 11E). Furthermore, the eighth turn portion 118 forms the outermost portion of the planar coil 11 (conductor 11E). In the following, when describing matters common to each of the multiple turn portions 11n, they will be referred to as the turn portion 11n or the turn portions 111 to 118.

[0046] Each of the turn portions 111 to 118 extends on the imaginary plane. The first to eighth turn portions 111 to 118 are connected in this order, thereby forming a spiral shape for the planar coil 11 (conductor 11E). In the illustrated example, the conductor 11E has an octagonal shape as a whole. The conductor 11E is wound so that each of the turn portions 111 to 118 forms a roughly octagonal shape. However, the shape of the conductor 11E is not limited to this. The conductor 11E may have a polygonal shape other than an octagonal shape (e.g., a square, hexagon, or dodecagon) as a whole. In this case, each of the turn portions 111 to 118 may be wound so as to roughly form a polygon other than an octagon (e.g., a square, hexagon, or dodecagon). The conductor 11E may also have a circular shape as a whole. In this case, each of the turn portions 111 to 118 may be wound so as to roughly form a circle.

[0047] One end of each of the turn portions 111 to 118 is located radially inward from the other end of the turn portion 111 to 118. In other words, the other end of each of the turn portions 111 to 118 is located radially outward from the one end of the turn portion 111 to 118.

[0048] As shown in FIG. 3 , each of the turn portions 111-118 includes a plurality of straight line portions st1-st9 arranged around the central axis C. When viewed in the axial direction, each of the straight line portions st1-st9 extends linearly. Adjacent straight line portions st1-st9 are connected to each other in the circumferential direction of a circle centered on the central axis C. In each of the turn portions 111-118, the plurality of straight line portions st1-st9 are sequentially connected so that one of the adjacent straight line portions bends toward the other, thereby forming a spiral-shaped planar coil 11. In the illustrated example, the first to seventh turn portions 111-117 include the first to ninth straight line portions st1-st9. In contrast, the eighth turn portion 118 includes the first to eighth straight line portions st1-st8 but does not include the ninth straight line portion st9. In the first to seventh turn portions 111-117, the first to ninth straight line portions st1-st9 are arranged in this order along the circumferential direction. In the eighth turn portion 118, first to eighth straight portions st1 to st8 are arranged in this order along the circumferential direction.

[0049] The end of the first straight portion st1 that is not connected to the second straight portion st2 forms the radially inner end of each turn portion 111-118. In the first to seventh turn portions 111-117, the end of the ninth straight portion st9 that is not connected to the eighth straight portion st8 forms the radially outer end of the first to seventh turn portions 111-117. The ninth straight portion st9 extends radially outward from and parallel to the first straight portion st1. In the eighth turn portion 118, the end of the eighth straight portion st8 that is not connected to the seventh straight portion st7 forms the radially outer end. The first to seventh turn portions 111-117 each have their radially outer end connected to the radially inner end of the second to eighth turn portions 118 that are adjacent to them on the radially outer side.

[0050] The planar coil 11 (conductor 11E) described above is formed by punching a metal plate such as a copper plate or an aluminum plate into a spiral shape, for example. Alternatively, the planar coil 11 can also be formed by etching a metal foil such as a copper foil or an aluminum foil into a spiral shape.

[0051] The radius of the planar coil 11 (the distance from the central axis C to the farthest point in the radial direction) may be 80 mm or more and 450 mm or less. When the coil component 10 is used as a power transmitting coil component or a power receiving coil component of a power transmission system S that transmits power to an electric vehicle by magnetic field resonance, the radius of the planar coil 11 may be 200 mm or more and 350 mm or less.

[0052] The thickness of the planar coil 11 (conductor 11E) is measured along the axial direction of the planar coil 11. The thickness of the planar coil 11 (thickness of the conductor 11E) may be, for example, 0.1 mm or more and 2.0 mm or less, 0.2 mm or more and 1.0 mm or less, or 0.3 mm or more and 0.7 mm or less. The thickness of the planar coil 11 (conductor 11E) may be, for example, 0.15 mm or more and 0.35 mm or less. When transmitting power to an electric vehicle using the magnetic resonance method, it is desirable to be able to transmit 1 kW or more, preferably 5 kW or more, of power in the high-frequency current frequency range of 10 kHz to 200 kHz, particularly 79 kHz to 90 kHz. In this case, the thickness of the planar coil 11 made of copper is preferably 0.4 mm or more.

[0053] The wire width of the planar coil 11 (conductor 11E) is not particularly limited. However, considering that a power of 1 kW or more, preferably 5 kW or more, can be transmitted in a high-frequency current frequency range of, for example, 79 kHz to 90 kHz, the wire width of each of the turn portions 111 to 118 may be 2 mm to 20 mm. In this case, the wire width of each of the turn portions 111 to 118 may be 2 mm to 16 mm, 2 mm to 12 mm, or 2 mm to 8 mm. Note that the wire width refers to the distance between the inner and outer peripheral surfaces of the linear portion of the planar coil 11 (conductor 11E) in a cross section perpendicular to the direction in which the planar coil 11 (conductor 11E) winds around.

[0054] The aspect ratio of the planar coil 11 (conductor 11E) having a rectangular cross section is determined by dividing the wire width (the radial width of each turn portion 11n) of the planar coil 11 (conductor 11E) by the thickness of the planar coil 11 (conductor 11E). The aspect ratio of the planar coil 11 (conductor 11E) may be 2 to 12, or 3 to 10.

[0055] The thickness and line width of the planar coil 11 (conductor 11E) may be measured on a cross section obtained by axially cutting the coil component 10 to expose the planar coil 11 (conductor 11E). In this case, the thickness and line width of the planar coil 11 (conductor 11E) may be measured by measuring each part of the planar coil 11 (conductor 11E) with a ruler or the like, or by analyzing a cross-sectional image.

[0056] In this embodiment, the central axis C is determined as follows. First, linear imaginary turn sections similar in shape to the innermost turn section 111 are drawn sequentially from the radially inner end of the innermost turn section 111 in a spiral shape extending radially inward. Drawing is continued until all imaginary turn sections that fit within a diameter of 1 cm are drawn. A line that passes through the radially inner region of the imaginary turn sections that fit within a diameter of 1 cm in a direction perpendicular to the circumferential and radial directions of the spiral shape is determined to be the central axis C.

[0057] (First Coil Holding Member) The first coil holding member 20 is a member that overlaps the planar coil 11 in the axial direction and holds the planar coil 11. In this embodiment, the first coil holding member 20 is formed by hardening a molten molding material. The molten molding material is hardened while in contact with the planar coil 11. As a result, the first coil holding member 20 is integrated with the planar coil 11 and holds the planar coil 11. A structure in which the first coil holding member 20 and the planar coil 11 are integrated may be referred to as an intermediate 10M below.

[0058] In the coil device 10, for example, when transmitting electric power, the magnetic field generated by the planar coil 11 passes through the first holding member 20. Therefore, the first coil holding member 20 is preferably non-conductive (insulating) and non-magnetic so as not to interfere with the magnetic field and to prevent eddy currents from occurring.

[0059] Considering that non-conductivity (insulation) and non-magnetic properties are preferable, the material of the first coil holding member 20 is, for example, an insulating resin, and may also be fiber-reinforced plastic. More specifically, the material of the first coil holding member 20 may be glass fiber-reinforced polyamide. However, the material of the first coil holding member 20 is not particularly limited. For example, it may not contain glass fiber. Also, thermoplastic resins or thermosetting resins other than polyamide may be used. Note that insulation is defined as a material having a volume resistivity of 10 １０ It means that the resistance is Ω·m or more. Non-magnetic means that it does not exhibit magnetism.

[0060] Fig. 5A is a plan view of the first coil holding member 20. Fig. 5B shows a partial perspective view of the first coil holding member 20. The first coil holding member 20 has a rectangular shape in plan view, and when the first coil holding member 20 overlaps with the planar coil 11 in the axial direction, it covers the entire planar coil 11.

[0061] 4, 5A, and 5B, a spiral groove 21 is formed in the first coil holding member 20. The groove 21 is also formed with a plurality of raised portions 22 that partially fill the groove 21, dividing the groove 21, or partially reducing the depth of the groove 21. The groove 21 is formed so as to be recessed from the surface of the first coil holding member 20 that overlaps with the planar coil 11. An installation region 23 that holds the planar coil 11 is formed in a portion of the surface of the first coil holding member 20 that overlaps with the planar coil 11, where the groove 21 is not formed.

[0062] As will be described in detail later, second coil holding member 30 has wall portion 32 that protrudes beyond planar coil 11 toward first coil holding member 20. Groove 21 forms a space to accommodate wall portion 32. Wall portion 32 has recessed portion 33 that recesses from its tip. In first coil holding member 20, raised portion 22 that fills groove 21, dividing groove 21 or reducing the depth of groove 21, is positioned so as to fit into recessed portion 33 of wall portion 32.

[0063] In this embodiment, the raised portion 22 fills the groove 21 and divides it. The state in which the raised portion 22 fills the groove 21 and divides it means that the raised portion 22 completely fills a portion of the groove 21. The raised portion 22 is formed to connect opposing side surfaces of a portion of the groove 21. The "between side surfaces" refers to the space between the side surface located near the center of the spiral shape of the portion of the groove 21 and the side surface facing it. The raised portion 22 can function as a rib that reinforces the strength and rigidity that may be reduced by the groove 21. This makes the first coil holding member 20 less likely to bend, improving shape retention performance.

[0064] In this embodiment, as shown in Fig. 5A, a plurality of raised portion groups 22G, each consisting of a plurality of raised portions 22 arranged in the radial direction, are formed on the first coil holding member 20. Specifically, four raised portion groups 22G are formed at regular angle intervals (90 degrees) in the circumferential direction of the spiral shape. However, the number and positions of the raised portions 22 are not particularly limited.

[0065] As described above, the first coil holding member 20 is formed by hardening a molten molding material. As will be described in detail below, the first coil holding member 20 is formed by supplying the molten molding material to a mold 100 (see FIGS. 6A and 6B ) having a spiral-shaped protrusion 102 and hardening it. The protrusion 102 of the mold 100 has a notch 103 recessed from its tip. The groove 21 is formed by the protrusion 102, and the raised portion 22 is formed by the notch 103. The notch 103 in the protrusion 102 of the mold 100 ensures good fluidity of the molding material, allowing the molding material to be spread evenly over the mold 100. This results in a good finished first coil holding member 20.

[0066] The raised portions 22 in the first coil holding member 20 are formed to correspond to the notches 103 formed in the mold 100 in order to improve the fluidity of the molding material. However, as described above, the raised portions 22 also function as reinforcement in the first coil holding member 20. Therefore, the raised portions 22 are not simply formed for convenience in the manufacturing process, but rather exert a technical effect that is unrelated to the manufacturing process.

[0067] (Second Coil Holding Member) The second coil holding member 30 is a member that holds the planar coil 11 by sandwiching the planar coil 11 between itself and the first coil holding member 20. The second coil holding member 30 overlaps with the planar coil 11 in the axial direction of the planar coil 11.

[0068] As shown in Figures 2 to 4 and 5B, the second coil holding member 30 includes a plate-shaped spacer portion 31 extending radially of the planar coil 11, and a spiral-shaped wall portion 32 protruding from the surface of the spacer portion 31 that overlaps with the planar coil 11.

[0069] The second coil holding member 30 is magnetic and has the function of suppressing magnetic permeability and / or leakage magnetic fields. Specifically, the second coil holding member 30 is magnetic and insulating. The magnetic field generated by the coil component 10 spreads in all directions relative to the central axis C of the planar coil 11. In this case, the magnetic property of the second coil holding member 30 allows the spreading magnetic flux lines to be directed toward the central axis C. Furthermore, if the magnetic field generated by the coil component 10 reaches peripheral components located around the coil component 10, adverse effects may be caused on the peripheral components. Therefore, the second coil holding member 30 is provided to prevent magnetic lines from reaching the peripheral components. This allows the second coil holding member 30 to suppress leakage magnetic fields that do not contribute to the generation of current.

[0070] The second coil holding member 30 contacts the planar coil 11 in an area where the wall portion 32 is not present on the surface of the spacer portion 31 that overlaps the planar coil 11. The wall portion 32 protrudes beyond the planar coil 11 toward the first coil holding member 20, in a direction away from the spacer portion 31. In the second coil holding member 30, the wall portion 32 is also magnetic. Such wall portion 32 can improve the performance of the coil component 10, such as the coupling coefficient and Q value.

[0071] 4 and 5B , the wall portion 32 is accommodated in the groove 21 of the first coil holding member 20. The wall portion 32 has a recess 33 recessed from its tip toward the spacer portion 31. The wall portion 32 has the recess 33 at a position corresponding to the protruding portion 22 of the first coil holding member 20. When the first coil holding member 20, the planar coil 11, and the second coil holding member 30 are integrated, the protruding portion 22 is positioned so as to fit into the recess 33 of the wall portion 32. The arrangement pattern of the recess 33 is the same as the arrangement pattern of the protruding portion 22. Therefore, the multiple recesses 33 include multiple recess groups 33G each consisting of multiple recesses 33 arranged radially as shown in FIG. 3 . Specifically, four recess groups 33G are formed at regular intervals (90 degrees) around the circumferential direction of the spiral shape. However, the number and positions of the recesses 33 are not particularly limited.

[0072] Here, increasing the number or volume of the raised portions 22 results in an increase in the number or volume of the recessed portions 33, and a decrease in the volume of the wall portions 32. A decrease in the volume of the wall portions 32 reduces the performance improvement effects of the wall portions 32, such as the coupling coefficient and Q value. Therefore, it is undesirable for the number or volume of the raised portions 22 to be excessively large. It is also undesirable for the raised portions 22 to be concentrated in a specific area. After extensive research, the present inventors have found that it is desirable for the ratio of the volume of the raised portions 22 to the volume of the groove 21 without the raised portions 22 to be less than 10%. In this case, the performance improvement effect of the wall portions 32 can be effectively obtained, and good formability, strength, and rigidity of the first coil holding member 20 can be ensured.

[0073] The second coil holding member 30 includes, for example, a holding material containing resin and a plurality or an infinite number of magnetic particles made of a magnetic material. The magnetic particles are held by the holding material. The holding material is insulating, more specifically, non-magnetic and insulating. The insulating property means that the volume resistivity is 10 １０ This means that the resistance is Ω·m or more.

[0074] The resin for forming the holding material of the second coil holding member 30 may be, for example, a thermosetting resin such as epoxy resin or polyimide. Alternatively, a thermoplastic resin such as nylon, polyethylene, or polypropylene may also be used as the resin for forming the second coil holding member 30. The holding material may also include or be made of, for example, fiber-reinforced plastic. For example, the holding material may include or be made of glass-fiber-reinforced polyamide.

[0075] The magnetic particles of the second coil holding member 30 may be made of one or more of ferrite, particularly soft magnetic ferrite, nanocrystalline magnetic material, silicon steel, soft magnetic iron, and amorphous metal.

[0076] The relative magnetic permeability of the second coil holding member 30 is preferably 2.0 or more, and may be 2.0 or more and 20.0 or less. The relative magnetic permeability of the second coil holding member 30 is more preferably 5.0 or more, and may be 5.0 or more and 20.0 or less. The relative magnetic permeability of the second coil holding member 30 is not particularly limited, but if it is too high, the flexibility and strength of the second coil holding member 30 may be undesirably impaired. Therefore, the relative magnetic permeability of the second coil holding member 30 may be 30 or less.

[0077] (First Magnetic Shield Member) The first magnetic shield member 40 is provided to suppress magnetic transmission and / or leakage magnetic field. As shown in FIG. 4 , the first magnetic shield member 40 is placed on the surface of the second coil holding member 30 opposite the surface that overlaps with the planar coil 11. The first magnetic shield member 40 is formed in a plate shape and extends along the radial direction of the planar coil 11. The first magnetic shield member 40 is sized so that its outer periphery is positioned outside the second coil holding member 30 and the planar coil 11 when viewed in the axial direction. In the illustrated example, the first magnetic shield member 40 has a rectangular shape when viewed in the axial direction.

[0078] The first magnetic shield member 40 includes a magnetic material. As described above, the magnetic field generated by the coil component 10 spreads in all directions relative to the central axis C of the planar coil 11. In this case, the first magnetic shield member 40 has magnetic properties, which allows the spreading magnetic flux lines to be directed toward the central axis C. The first magnetic shield member 40 also prevents the magnetic field from reaching surrounding components. This allows the first magnetic shield member 40 to suppress leakage magnetic fields that do not contribute to the generation of current.

[0079] The first magnetic shield member 40 preferably includes a soft magnetic material. More specifically, the first magnetic shield member 40 includes a ferrite, preferably a soft ferrite. The first magnetic shield member 40 may also include a nanocrystalline magnetic material.

[0080] The relative magnetic permeability of the first magnetic shield member 40 is not particularly limited, but is preferably 100 or greater, and may be 100 or greater and 10,000 or less. The relative magnetic permeability of the first magnetic shield member 40 may be 1,000 or greater, 2,000 or greater, or 3,000 or greater. The relative magnetic permeability of the first magnetic shield member 40 may be 8,000 or less, 6,000 or less, or 4,000 or less.

[0081] In the example shown in FIG. 4 , the first magnetic shield member 40 is in contact with the second coil holding member 30, but this is not limited thereto. The first magnetic shield member 40 may be spaced apart from the second coil holding member 30. When the first magnetic shield member 40 is disposed spaced apart from the second coil holding member 30, the distance between the first magnetic shield member 40 and the second coil holding member 30 is not particularly limited, but is, for example, 3 mm or less. Note that the longer the distance between the first magnetic shield member 40 and the second coil holding member 30, the more difficult it is for heat to be dissipated from the coil component 10, which may result in the coil component 10 becoming too hot. For this reason, it is preferable that the distance between the first magnetic shield member 40 and the second coil holding member 30 be 1 mm or less.

[0082] (Second Magnetic Shield Member) The second magnetic shield member 50 is placed on the surface of the first magnetic shield member 40 opposite the surface that is placed on the second coil holding member 30. The second magnetic shield member 50 is formed in a plate shape and extends along the radial direction of the planar coil 11. The second magnetic shield member 50 is sized so that its outer periphery is located outside the second coil holding member 30 and the planar coil 11, and outside the first magnetic shield member 40, when viewed in the axial direction. In the illustrated example, the first magnetic shield member 40 has a rectangular shape when viewed in the axial direction.

[0083] The second magnetic shield member 50 is non-magnetic and conductive. This allows the second magnetic shield member 50 to suppress magnetic transmission and / or leakage magnetic fields. This also prevents the magnetic fields or electromagnetic waves generated by the coil component 10 from affecting other electronic components, the human body, etc. The second magnetic shield member 50 can be made of a metal such as aluminum or an aluminum alloy.

[0084] 2 and 3 , the first connection terminal 61 is connected to the radially inner end of the first turn portion 111 located on the innermost periphery side of the planar coil 11. Although not shown, the first connection terminal 61 passes radially outward between the second coil holding member 30 and the first magnetic shield member 40 and extends from the second coil holding member 30. The second connection terminal 62 is connected to the radially outer end of the eighth turn portion 118 located on the outermost periphery side of the planar coil 11. The first connection terminal 61 and the second connection terminal 62 can be used, for example, when connecting to the high-frequency current supply unit 1A or the conversion unit 2A.

[0085] When the coil component 10 is used as a power transmission coil, the first connection terminal 61 and the second connection terminal 62 are connected to the high-frequency current supply unit 1A or AC power supply as shown in Fig. 1. When a high-frequency current is supplied to the coil component 10, the current can flow from the first connection terminal 61 to the planar coil 11, and then from the second connection terminal 62 to the high-frequency current supply unit 1A or AC power supply. Alternatively, the current can flow from the second connection terminal 62 to the planar coil 11, and then from the first connection terminal 61 to the high-frequency current supply unit 1A or AC power supply. This allows a magnetic field including magnetic field lines along the central axis of the planar coil 11 to be generated.

[0086] On the other hand, when the coil component 10 is used as a receiving coil, a high-frequency current can be generated in the planar coil 11 by receiving a magnetic field including magnetic field lines along the central axis of the planar coil 11. Then, this high-frequency current can be supplied to an external device from the first connection terminal 61 or the second connection terminal 62.

[0087] Needless to say, the first connection terminal 61 and the second connection terminal 62 are made of a conductive material. In this embodiment, the first connection terminal 61 and the second connection terminal 62 are made of copper, which is the same material as the conductor 11E of the planar coil 11, but the material is not limited to this. The first connection terminal 61 and the second connection terminal 62 may also be made of a copper alloy, aluminum, an aluminum alloy, or the like.

[0088] <Method for Manufacturing Coil Component> Next, an example of a method for manufacturing the coil component 10 will be described.

[0089] Fig. 6A is a plan view of a mold 100 used in this example, and Fig. 6B is a perspective view of the mold 100. When manufacturing the coil component 10, the mold 100 is first prepared. The mold 100 has a plate-shaped main body portion 101 and a spiral-shaped convex portion 102 protruding from the surface of the main body portion 101. The mold 100 is formed with one or more (multiple in this example) notches 103 recessed from the tip of the convex portion 102. The notches 103 are open from an inner surface 102A of the convex portion 102 located toward the center of the spiral shape formed by the convex portion 102 and an outer surface 102B opposite thereto.

[0090] In this example, the plurality of notches 103 includes one or more (in this example, multiple) notch groups 103G each consisting of a plurality of notches 103 aligned in the radial direction. More specifically, in the mold 100, four notch groups 103G are arranged at regular angles (90 degrees in this example) in the circumferential direction.

[0091] The convex portion 102 in the mold 100 includes first to eighth turn groove forming portions 121 to 128. The first to eighth turn groove forming portions 121 to 128 are arranged in this order from the innermost position in the radial direction toward the outermost position. Each of the turn groove forming portions 121 to 128 extends on the imaginary plane. The first to eighth turn groove forming portions 121 to 128 are connected in this order to form a spiral shape. In the illustrated example, the convex portion 102 is shaped to fit the planar coil 11, and therefore has an octagonal shape overall. Each of the turn groove forming portions 121 to 128 includes a plurality of first to ninth straight line portions st11 to st19 arranged around its central axis. Each of the straight line portions st11 to st19 extends linearly when viewed in the axial direction. In each of the turn groove forming portions 121 to 128, a spiral shape is formed by sequentially connecting a plurality of straight line portions st11 to st19 such that one of the adjacent straight line portions is bent toward the other.

[0092] The notch group 103G is provided in the first straight portion st11, the third straight portion st13, the fifth straight portion st15, and the seventh straight portion st17 in each of the turn groove forming portions 121 to 128. Also, each notch 103 is formed between both ends of the first straight portion st11, the third straight portion st13, the fifth straight portion st15, and the seventh straight portion st17. In other words, the notches 103 are not formed in the bent portions.

[0093] Furthermore, in the mold 100, the notches 103 are desirably formed so that the ratio of the volume of all the notches 103 to a reference volume obtained by adding up the volume of the protrusions 102 and the volume of all the notches 103 is less than 10%. In this embodiment, the notches 103 are formed so that the ratio of the volume of all the notches 103 to the reference volume is less than 10%. This ensures that the volume of the wall portion 32 of the magnetic second coil holding member 30 is sufficient when the coil component 10 is completed, and the effect of improving coil performance by the wall portion 32 can be suitably obtained. However, the number and positions of the notches 103 are not particularly limited.

[0094] After the mold 100 is prepared as described above, the spiral-shaped planar coil 11 is placed on the surface of the main body 101 of the mold 100 so as to follow the protrusions 102. Figures 6A and 6B show the state in which the planar coil 11 is placed on the mold 100.

[0095] Thereafter, a molten molding material is placed so as to cover the planar coil 11 and the mold 100. In this example, the molding material is supplied to the center of the mold 100 and flows radially outward as shown by the arrows in FIG. 7A. Here, the mold 100 has a notch 103 formed in the protrusion 102, recessed from the tip. The notch 103 allows the molding material to flow as shown by the arrows in FIG. 7B. This allows the notch 103 to ensure good fluidity of the molding material and enable the molding material to be spread uniformly over the mold 100.

[0096] The molding material is then hardened to produce an intermediate 10M consisting of a first coil holding member 20 made of the molding material and a planar coil 11 integrated with the first coil holding member 20. A spiral groove 21 corresponding to the protrusion 102 is formed in the first coil holding member 20, and a raised portion 22 is formed at a position corresponding to the notch 103 in the groove 21, either partially filling the groove 21 to divide it or partially reducing the depth of the groove 21. In this embodiment, the notch 103 allows the molding material to be spread evenly on the mold 100, thereby making the thickness of the molding material uniform. This allows the first coil holding member 20 to be formed with a uniform thickness.

[0097] After the intermediate 10M is produced, it is removed from the mold 100. A molten magnetic resin material containing a magnetic material and a resin is applied to the intermediate 10M so as to fill the groove 21 of the first coil holding member 20 and cover the planar coil 11 held by the first coil holding member 20. The magnetic resin material is then cured to produce the second coil holding member 30. The second coil holding member 30 has a plate-shaped spacer portion 31 extending radially and a spiral-shaped wall portion 32 formed from the portion of the magnetic resin material that fills the groove 21 and protruding from the spacer portion 31. The wall portion 32 has a recess 33 recessed toward the spacer portion 31 at a position corresponding to the protrusion 22 of the first coil holding member 20.

[0098] Thereafter, the first connection terminal 61 and the second connection terminal 62 are provided, and the first magnetic shield member 40 and the second magnetic shield member 50 are stacked in order on the second coil holding member 30, thereby manufacturing the coil component 10.

[0099] In the present embodiment described above, first coil holding member 20 for holding planar coil 11 is produced using mold 100 in which notch 103 recessed from the tip is formed in spiral-shaped protrusion 102. Notch 103 is formed so as to be open from inner surface 102A of protrusion 102 located on the center side of the spiral shape formed by protrusion 102 and outer surface 102B on the opposite side.

[0100] The notches 103 described above allow the molding material to flow. This ensures good fluidity of the molding material, allowing it to be uniformly spread on the mold 100. This results in a uniform thickness of the molding material on the mold 100, and therefore allows the first coil holding member 20 to be formed with a uniform thickness. Furthermore, the first coil holding member 20 formed by hardening the molding material has a spiral-shaped groove 21 corresponding to the protrusion 102 of the mold 100. Furthermore, the first coil holding member 20 formed by hardening the molding material has a raised portion 22 formed at a position corresponding to the notch 103 in the groove 21, either partially filling the groove 21 to separate it or partially shallowing the depth of the groove 21. Here, the raised portion 22 can function as a rib to reinforce the strength and rigidity that may be reduced by the groove 21. This makes the first coil holding member 20 less likely to bend, improving its shape retention. Therefore, according to this embodiment, thickness variations and warpage of the coil component 10 can be suppressed.

[0101] <Modifications> Next, several modifications of the coil device 10 according to the above-described embodiment will be described with reference to Figures 8 to 13, 14A, and 14B. Components in the modifications described below that are the same as those in the above-described embodiment are designated by the same reference numerals, and redundant description will be omitted. Note that the first coil holding member 20 is not shown in Figures 8 to 13 and 14A.

[0102] FIG. 8 is a plan view of a coil component according to a first modified example. In this first modified example, the multiple recesses 33 formed in the wall portion 32 of the second coil holding member 30 include eight recess groups 33G, each consisting of multiple recesses 33 arranged radially. Specifically, the eight recess groups 33G are formed at regular angles (45 degrees) around the circumferential direction of the spiral shape. Each recess group 33G is formed between both ends of the straight line portions st1 to st9. The positions of the eight recess groups 33G correspond to the positions of the eight arrows in FIG. 8. The mold used to manufacture the first modified example has a shape similar to that of the second coil holding member 30. The formation pattern of the raised portions 22 in the first coil holding member 20 formed using this mold is the inverse of the formation pattern of the recesses 33.

[0103] FIG. 9 is a plan view of a coil component according to a second modification. In this modification, the multiple recesses 33 formed in the wall portion 32 of the second coil holding member 30 include four recess groups 33G consisting of multiple recesses 33 arranged radially. These four radially extending recess groups 33G are formed at regular intervals (90 degrees) around the circumferential direction of the spiral shape. Furthermore, on both sides of each radially arranged recess group 33G in the wall portion 32, a recess group 33G is formed parallel to the radially arranged recess group 33G. That is, in this modification, twelve recess groups 33G are formed. One radially extending recess group 33G and a set of two parallel recess groups 33G are formed in the first linear portion st1, the third linear portion st3, the fifth linear portion st5, and the seventh linear portion st7, between both ends of each linear portion. The positions of the twelve recess groups 33G correspond to the positions of the twelve arrows in FIG. 9 . The mold used to manufacture the second modified example has the same shape as the second coil holding member 30. The formation pattern of the raised portions 22 in the first coil holding member 20 formed by such a mold is the inverse of the formation pattern of the recessed portions 33.

[0104] FIG. 10 is a plan view of a coil component according to a third modification. In this modification, the multiple recesses 33 formed in the wall portion 32 of the second coil holding member 30 include eight recess groups 33G consisting of multiple recesses 33 arranged radially. These eight radially extending recess groups 33G are formed at regular angles (45 degrees) around the circumferential direction of the spiral shape. Furthermore, on both sides of each radially arranged recess group 33G in the wall portion 32, a recess group 33G is formed parallel to the radially arranged recess group 33G. In other words, in this modification, 24 recess groups 33G are formed. One radially extending recess group 33G and a set of two parallel recess groups 33G are formed on each of the straight portions st1 to st8, between both ends of each straight portion. The positions where the 24 recess groups 33G are formed correspond to the positions of the 24 arrows in FIG. 10. The mold used to manufacture the third modification has a shape similar to that of the second coil holding member 30. The formation pattern of the protrusions 22 in the first coil holding member 20 formed by such a mold is the inverse of the formation pattern of the recesses 33 .

[0105] FIG. 11 is a plan view of a coil component according to a fourth modified example. The formation pattern of the plurality of recesses 33 formed in the wall portion 32 of the second coil holding member 30 in the fourth modified example is the same as that in the above-described embodiment. That is, the plurality of recesses 33 includes four recess groups 33G each consisting of a plurality of recesses 33 arranged in the radial direction. However, the width of the recesses 33 in the four recess groups 33G is greater than the width of the recesses 33 in the above-described embodiment. The formation positions of the four recess groups 33G correspond to the positions of the four arrows in FIG. 11. The mold used to manufacture the fourth modified example has a shape similar to that of the second coil holding member 30. The formation pattern of the protrusions 22 in the first coil holding member 20 formed using such a mold is the inverse of the formation pattern of the recesses 33.

[0106] FIG. 12 is a plan view of a coil component according to a fifth modified example. The formation pattern of the plurality of recesses 33 formed in the wall portion 32 of the second coil holding member 30 in the fifth modified example is the same as that in the first modified example. That is, the plurality of recesses 33 includes eight recess groups 33G each consisting of a plurality of recesses 33 arranged in the radial direction. However, the width of the recesses 33 in the eight recess groups 33G is greater than the width of the recesses 33 in the first modified example. The formation positions of the eight recess groups 33G correspond to the positions of the eight arrows in FIG. 12. The mold used to manufacture the fifth modified example has a shape similar to that of the second coil holding member 30. The formation pattern of the protrusions 22 in the first coil holding member 20 formed using such a mold is the inverse of the formation pattern of the recesses 33.

[0107] FIG. 13 is a plan view of a coil component according to a sixth modified example. In the sixth modified example, similar to the first modified example, the plurality of recesses 33 formed in the wall portion 32 of the second coil holding member 30 includes eight recess groups 33G each consisting of a plurality of recesses 33 arranged radially. The eight recess groups 33G are formed at regular angles (45 degrees) around the circumferential direction of the spiral shape. However, each of the eight recess groups 33G is formed at a bend where adjacent straight sections st1 to st9 connect. The positions of the eight recess groups 33G correspond to the positions of the eight arrows in FIG. 8. The mold used to manufacture the sixth modified example has a shape similar to that of the second coil holding member 30. The pattern of the raised portions 22 in the first coil holding member 20 formed using such a mold is the inverse of the pattern of the recesses 33.

[0108] Fig. 14A is a plan view of a coil component according to a seventh modified example. Fig. 14B is a diagram showing the arrangement of ferrite plates 40P constituting a first magnetic shield member 40 in the coil component according to the seventh modified example.

[0109] 14B , in the seventh modification, the first magnetic shield member 40 is configured by laying out a plurality of ferrite plates 40P. Then, the second coil holding member 30 is placed on top of the first magnetic shield member 40. The boundaries BL between adjacent ferrite plates 40P overlap with the recesses 33 in the wall portions 32 of the second coil holding member 30. The positions of the notches in the mold and the shapes of the plurality of ferrite plates are adjusted so that this overlapping state is formed.

[0110] In the seventh modification, twelve ferrite plates 40P are laid out, and twelve boundaries between adjacent ferrite plates 40P are formed. In the seventh modification, twelve overlapping recess groups 33G are formed on each boundary between twelve pairs of adjacent ferrite plates 40P. The positions where the twelve recess groups 33G are formed correspond to the positions of the twelve arrows in FIG. 14A . The mold used to manufacture the seventh modification has a shape similar to that of the second coil holding member 30. The formation pattern of the raised portions 22 in the first coil holding member 20 formed using such a mold is the inverse of the formation pattern of the recesses 33.

[0111] <Simulation of Performance Evaluation> Next, the results of a simulation of the performance of the coil component 10 according to the above-described embodiment and the coil components according to several modified examples will be described. In the performance evaluation described here, the Q value of each coil component was calculated by simulation.

[0112] FIG. 15 shows a graph illustrating performance evaluation results for the embodiment and several modified examples. The volume of the wall portion 32 of the second coil holding member 30, in other words, the volume of the groove 21 of the first coil holding member 20, decreases in the following order: the embodiment, the first and sixth modified examples, the seventh modified example, the second modified example, the third modified example, the fourth modified example, and the fifth modified example, all of which have the same volume. On the horizontal axis (groove volume ratio) in FIG. 15 , 100% represents a configuration (ref) in which the protrusion 22 is not formed in the groove 21. The volume of the groove 21 in the embodiment and each modified example is smaller than the volume of the groove 21 in the configuration (ref) in which the protrusion 22 is not formed in the groove 21. The horizontal axis (groove volume ratio) represents the ratio of the volume of the groove 21 in the embodiment and each modified example to the volume of the groove 21 in the configuration (ref) in which the protrusion 22 is not formed in the groove 21. A larger groove volume ratio indicates a larger volume of the wall portion 32.

[0113] Table 1 below shows the relationship between the above ref, the volume ratio of the embodiment and each modification, and the Q value.

[0114]

[0115] 15 and Table 1, in the first, sixth, seventh, second, and third modifications, in which the groove volume ratio is 90% or more, the wall portion 32 has a large volume, thereby maintaining a high Q value. In the mold 100, the notches 103 are desirably formed so that the ratio of the notch volume to the reference volume obtained by adding up the volume of the protrusions 102 and the volume of all the notches 103 is less than 10%. This means that the groove volume ratio is 90% or more, and that the volume of the wall portion 32 is 90% or more compared to a case in which the recesses 33 are not present. The results shown in FIG. 15 and Table 1 confirm that the above-described formation conditions for the notches 103 are desirable.

[0116] Comparing the first and sixth variations, the groove volume ratios are the same, but the Q value of the sixth variation is lower than that of the first variation. Considering this result, it is considered undesirable to form the recess 33 at the bent portion. Furthermore, no noticeable change in performance was observed for the seventh variation compared to other similar conditions (such as the second and sixth variations). Considering this result, it is considered that the positional relationship between the recess 33 and the boundary of the ferrite plate 40P is unrelated to the change in performance.

[0117] Although the embodiments of the present disclosure have been described above, various modifications may be made to the above-described embodiments. Such modifications are also within the technical scope of the present disclosure. For example, in the above-described embodiments, the raised portion 22 of the first coil holding member 20 partially fills the groove 21 and divides the groove 21, but the raised portion 22 may partially shallow the depth of the groove 21. In this case, the notch 103 formed in the convex portion 102 of the mold 100 is formed so that its bottom surface does not reach the starting point of the convex portion 102 but is recessed halfway into the convex portion 102.

Claims

1. A step of preparing a mold having a plate-shaped main body portion and a spiral convex portion protruding from the surface of the main body portion, being recessed from the tip of the convex portion, and having one or more notches formed to open from the inner surface of the convex portion located on the central side of the spiral shape formed by the convex portion and the outer surface on the opposite side thereof; a step of installing a spiral planar coil on the surface of the main body portion of the mold along the convex portion; a step of installing a molten molding material so as to cover the planar coil and the mold; a step of producing an intermediate body composed of a first coil holding member in which a spiral groove corresponding to the convex portion is formed by curing the molding material, and a raised portion that partially fills the groove to divide the groove or partially shallow the depth of the groove is formed at a position corresponding to the notch in the groove, and the planar coil integrated with the first coil holding member. A method for manufacturing a coil component, comprising:

2. The method for manufacturing a coil component according to claim 1, wherein a plurality of the notches are formed in the mold, and the plurality of notches include one or more notch groups composed of a plurality of the notches arranged in the radial direction of the spiral shape formed by the convex portion or in a direction parallel to the radial direction.

3. The method for manufacturing a coil component according to claim 2, wherein the plurality of notches include a plurality of notch groups arranged at regular angles in the circumferential direction around the center of the spiral shape formed by the convex portion, and each of the notch groups is arranged in the radial direction.

4. When viewed in the axial direction of the spiral shape formed by the convex portion, the convex portion includes a plurality of straight portions extending linearly, and the spiral shape is formed by sequentially connecting the plurality of straight portions so that one of the adjacent straight portions is bent with respect to the other, and the notch is formed between both ends of the straight portion. The method for manufacturing a coil component according to claim 1.

5. The method for manufacturing a coil component according to claim 1, wherein the mold is used in which the ratio of the volume of all the notches to the reference volume obtained by adding the volume of the convex portion and the volume of all the notches is less than 10%.

6. A step of installing a molten magnetic resin material containing a magnetic material and a resin onto the intermediate member so as to fill the groove of the first coil holding member and cover the planar coil held by the first coil holding member; A step of producing a second coil holding member including a plate-like spacer portion that extends and expands in the radial direction of the spiral shape formed by the planar coil and a spiral wall portion that is formed from a portion of the magnetic resin material filled in the groove and protrudes from the spacer portion by curing the magnetic resin material, The method for manufacturing a coil component according to any one of claims 1 to 5, wherein a recess that is recessed toward the spacer portion is formed at a position corresponding to the raised portion of the first coil holding member in the wall portion.

7. The method for manufacturing a coil component according to claim 6, further comprising a step of stacking a second coil holding member on a magnetic shield member formed by laying a plurality of ferrite plates, and adjusting a position of the notch and shapes of the plurality of ferrite plates in the mold so that a boundary between adjacent ferrite plates overlaps with the recess in the wall portion.

8. A first coil holding member in which a spiral groove is formed and a raised portion is formed to partially fill and divide the groove or partially shallow the depth of the groove; A planar coil having a spiral shape disposed in a portion of the first coil holding member where there is no groove and extending along the groove; A second coil holding member including a plate-like spacer portion and a spiral wall portion protruding from the spacer portion, and sandwiching the planar coil between the second coil holding member and the first coil holding member, The wall portion passes through the planar coil and is accommodated in the groove, The wall portion has a recess that is recessed toward the spacer portion at a position corresponding to the raised portion.

9. A coil component intermediate body comprising a first coil holding member in which a spiral groove is formed and a raised portion is formed to partially fill and divide the groove or shallow the depth of the groove; A planar coil having a spiral shape disposed in a portion of the first coil holding member where there is no groove and extending along the groove.

10. A power transmission device comprising the coil component according to claim 8.

11. A power reception device comprising the coil component according to claim 8.

12. A power transmission system comprising a power transmission device and a power reception device, wherein at least one of the power transmission device and the power reception device includes the coil component according to claim 8.

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