Coil assembly

Abstract

To prevent an increase in size of a coil assembly including a plurality of laminated coils.SOLUTION: A coil assembly 10 comprises a first coil C1 and a second coil C2 having a structure in which coil wires are formed in insulating layers K11-K22 and laminated with each other in a thickness direction of the insulating layers. The first coil and the second coil have a plurality of winding parts 111-221 laminated in the thickness direction, and connection parts b1, b5 connecting the plurality of winding parts to each other. The connection part b5 of the second coil is provided at an outside end of both ends in a winding direction of the second coil when seen in the thickness direction. An outer edge L2 in an outer direction at the outside end of the second coil is located inside an outer edge L1 in the outer direction of a portion, of the plurality of winding parts of the first coil, which corresponds to the outside end of the second coil in the thickness direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a coil assembly including a plurality of stacked coils.

Background Art

[0002] Conventionally, a configuration in which a plurality of coils are arranged in the vicinity of each other and used has been known. For example, in the non-contact power supply device of Patent Document 1, as a power transmission coil that performs non-contact power supply to a power reception device, a power transmission coil of a power transmission resonance circuit and a characteristic variable coil arranged in the vicinity above the power transmission coil are magnetically coupled to each other and used. In the non-contact power supply device of Patent Document 2, a power transmission coil included in a power transmission resonance circuit and a relay coil included in a relay resonance circuit are magnetically coupled to each other and used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a plurality of coils used by being arranged in the vicinity of each other as described above are stacked and integrated to form a coil assembly as a multilayer substrate, in each coil, in order to reduce the electrical resistance while securing the number of turns for obtaining a desired ampere-turn, a plurality of winding portions (coil wires such as copper foil) are stacked in the thickness direction with an insulating layer interposed therebetween, and a configuration in which the winding portions are electrically connected to each other may be adopted. In such a configuration, through-hole vias penetrating the entire multilayer substrate are used in order to electrically connect between the plurality of winding portions and to provide an electrical connection portion for receiving an external current in each coil on the end face of the multilayer substrate.

[0005] However, if a configuration is adopted in which a through-hole via for a particular coil is positioned outside of other coils (winding portion) in the thickness direction of the insulating layer, for example, to prevent interference between that coil and other coils, the coil assembly becomes larger. For this reason, there is a need for a technology that can suppress the increase in size of a coil assembly comprising multiple stacked coils. [Means for solving the problem]

[0006] As one embodiment of the present disclosure, a coil assembly (10) is provided. This coil assembly has a structure in which coil wires are formed on an insulating layer (K11~K22), and comprises a first coil (C1) and a second coil (C2) stacked on top of each other in the thickness direction of the insulating layer, wherein the first coil and the second coil each have a plurality of winding portions (111~221) stacked in the thickness direction, and connecting portions (b1, b5) that connect the plurality of winding portions to each other, wherein the connecting portion (b5) of the second coil is provided at the outer end of the winding direction of the plurality of winding portions of the second coil when viewed in the thickness direction, and the outer edge (L2) of the outer end of the second coil in the outer direction is located inward from the outer edge (L1) of the portion of the plurality of winding portions of the first coil that corresponds to the outer end of the second coil in the thickness direction. Furthermore, the number of windings in the first coil is greater than the number of windings in the second coil. . In another embodiment of the present invention, a coil assembly (10) is provided. This coil assembly has a structure in which coil wires are formed on an insulating layer (K11~K22), and comprises a first coil (C1) and a second coil (C2) stacked on top of each other in the thickness direction of the insulating layer, the first coil and the second coil each having a plurality of winding portions (111~221) stacked in the thickness direction, and connecting portions (b1, b5) connecting the plurality of winding portions to each other, the connecting portion (b5) of the second coil is provided at the outer end of the winding direction of the plurality of winding portions of the second coil when viewed in the thickness direction, and With the direction from the center of the insulating layer toward the outer edge being defined as the outward direction, the outward outer edge (L2) at the outer end of the second coil is located inward from the outward outer edge (L1) of the portion of the plurality of windings of the first coil that corresponds to the outer end of the second coil in the thickness direction, the first coil and the second coil are used magnetically coupled to each other in a contactless power supply system, and in the operating state of the first coil and the second coil, the ampere-turn of the first coil is greater than the ampere-turn of the second coil.

[0007] In this coil assembly configuration, the outer edge of the outer end of the second coil where the connecting portion is provided is located inward from the outer edge of the portion of the first coil's windings that corresponds to the outer end of the second coil in the thickness direction. Therefore, compared to a configuration where the outer edge of the second coil's outer end is located outward from the outer edge of the portion of the first coil's windings that corresponds to the outer end of the second coil in the thickness direction, the size of the coil assembly in the thickness direction can be reduced. Consequently, the size of the coil assembly comprising multiple stacked coils can be kept from increasing. [Brief explanation of the drawing]

[0008] [Figure 1] This block diagram shows a schematic configuration of a contactless power supply device to which a coil assembly is applied as one embodiment of the present disclosure. [Figure 2] This is an explanatory diagram showing the detailed configuration of the coil assembly of the first embodiment. [Figure 3] This is an explanatory diagram schematically showing the outlines of multiple winding sections of the first coil and the outlines of multiple winding sections of the second coil. [Figure 4] This is an explanatory diagram showing a magnified view of the subregion shown in Figure 2. [Figure 5] This is an explanatory diagram showing the detailed configuration of the coil assembly in the comparative example. [Figure 6] This is a cross-sectional view showing a coil assembly of the first embodiment and a coil assembly of a comparative example. [Figure 7] This is an explanatory diagram showing the detailed configuration of the coil assembly of the second embodiment. [Figure 8] This is an explanatory diagram showing the detailed configuration of the coil assembly of the second embodiment. [Figure 9] This is an explanatory diagram showing the detailed configuration of the coil assembly of the second embodiment. [Figure 10] These are explanatory diagrams showing enlarged versions of the subregions shown in Figures 8 and 9. [Figure 11] This is a cross-sectional view showing a coil assembly of the second embodiment. [Modes for carrying out the invention]

[0009] A. First Embodiment: A1. Device configuration of the contactless power supply device: The contactless power supply device 100 shown in Figure 1 supplies power to the power receiving device 200 without contact. The contactless power supply device 100 comprises a power supply circuit 140, a power transmission output circuit 130, and a plurality of power transmission units 105 connected in parallel to the power transmission output circuit 130. Each power transmission unit 105 comprises a power transmission resonant circuit 110 and a characteristic variable circuit 120. Each power transmission resonant circuit 110 is connected in parallel to the power transmission output circuit 130.

[0010] The power supply circuit 140 is configured, for example, as an AC / DC converter circuit that rectifies the AC voltage of an external power supply and outputs a DC voltage. The power transmission output circuit 130 is a circuit that converts the DC power supplied from the power supply circuit 140 into AC power at a predetermined operating frequency and supplies it to the power transmission resonant circuit 110. The power transmission output circuit 130 is configured, for example, as an inverter circuit.

[0011] The power transmission resonant circuit 110 is a circuit that supplies power to the power receiving device 200 through resonance. The power transmission resonant circuit 110 includes a first coil C1 and a resonant capacitor 116 connected in series with the first coil C1.

[0012] The first coils C1 of each power transmission resonant circuit 110 are arranged so that their respective coil surfaces are aligned horizontally, as will be described later. The coil surfaces are surrounded by the wiring that forms the coil and function as surfaces that output magnetic flux corresponding to the current flowing through the coil. The first coils C1 are also called "power transmission coils".

[0013] The variable-characteristic circuit 120, which is paired with the power transmission resonant circuit 110, is a closed circuit consisting of a second coil C2 and a variable-characteristic capacitor 126 connected in series. The second coil C2 is positioned so as to be magnetically coupled to the first coil C1 of the paired power transmission resonant circuit 110. In Figure 1, the magnetic coupling between the first coil C1 and the second coil C2 is indicated by two parallel lines. The second coil C2 is also called a "variable-characteristic coil." The second coil C2 plays a role in adjusting the input impedance of the power transmission resonant circuit 110 by changing the frequency characteristics of the inductance of the first coil C1.

[0014] As will be described later, the first coil C1 and the second coil C2 are each configured as part of a coil assembly (coil assembly 10 described later) configured integrally.

[0015] The difference in the magnetic coupling state between the first coil C1 and the second coil C2 is expressed as the difference in the coupling coefficient. The coupling coefficient takes a value greater than -1 and less than +1 according to the arrangement relationship of the second coil C2 with respect to the first coil C1. In this embodiment, both the first coil C1 and the second coil C2 are coils having a coreless structure.

[0016] The power receiving device 200 is mounted on various devices that operate using electric power, such as electronic devices and electric vehicles. The power receiving device 200 includes a power receiving resonance circuit 210, a power receiving circuit 220, and a battery 230.

[0017] Similar to the power transmission resonance circuit 110, the power receiving resonance circuit 210 also has a power receiving coil 212 and a resonance capacitor 216 connected in series. The primary series secondary series capacitor method (also called the "SS method") is applied to the power transmission resonance circuit 110 and the power receiving resonance circuit 210. In addition, a non-contact power supply method of single-phase on the power transmission side - single-phase on the power receiving side, in which the power transmission side is composed of the single-phase first coil C1 and the power receiving side is composed of the single-phase power receiving coil 212, is applied. The power receiving resonance circuit 210 resonates at the same resonance frequency as the power transmission resonance circuit 110, and is a circuit that obtains the AC power induced in the power receiving coil 212 in a resonance coupling state where the power receiving coil 212 and the first coil C1 are magnetically coupled.

[0018] The power receiving circuit 220 is, for example, a circuit that converts the AC power obtained by the power receiving resonance circuit 210 into DC power and charges the battery 230 as a load. The power charged in the battery is used as electric power in the device on which the power receiving device 200 is mounted.

[0019] Figure 1 shows an example where the coil surface of the power receiving coil 212 of the power receiving device 200 is positioned above the coil surface of the first coil C1 of the first power transmission unit 105 of the non-contact power supply device 100. In this case, the power receiving coil 212 is magnetically coupled to the first coil C1 and the second coil C2, which is magnetically coupled to the first coil C1.

[0020] In the first power transmission unit 105, where the power receiving coil 212 is positioned above, the input impedance of the power transmission resonant circuit 110 becomes smaller, and a drive current with a predetermined operating frequency f0 is supplied to the first coil C1 from the power transmission output circuit 130. In this case, a current with an operating frequency f0 induced by the resonant coupling between the power receiving coil 212 and the first coil C1 flows through the power receiving coil 212, and power is supplied from the power transmission resonant circuit 110 to the power receiving device 200 via the power receiving resonant circuit 210.

[0021] In contrast, in the second and subsequent transmission units 105 where the receiving coil is not positioned above, the input impedance of the transmission resonant circuit 110 becomes larger, and the output current flowing through the first coil C1 is smaller than the drive current flowing through the first coil C1 of the first transmission unit 105. As a result, in the transmission resonant circuit 110 of the transmission unit 105 that has a first coil C1 where the receiving coil 212 is not positioned above, it is possible to suppress the consumption of wasted power, reduce leakage flux, and improve transmission efficiency.

[0022] The change in the input impedance of the power transmission resonant circuit 110 depending on the presence or absence of the power receiving coil 212, as described above, can be achieved, for example, by adjusting the circuit constants of the power transmission resonant circuit 110 and the characteristic variable circuit 120 (such as the inductance of the second coil C2 and the capacitance of the characteristic variable capacitor 126), as described in Japanese Patent Application Publication No. 2021-97485.

[0023] A2. Detailed configuration of coil assembly 10: The first coil C1 and the second coil C2 described above are both part of a coil assembly 10, which has a structure in which multiple coil wires are stacked in the thickness direction (thickness direction of the insulating layer) with an insulating layer in between and integrated. Note that the coil wire located on the outermost (surface side) in the stacking direction in the coil assembly 10 may be covered with, for example, solder resist. In this embodiment, the coil wires are formed of copper foil, so the coil assembly 10 can also be said to be a multilayer substrate having a structure in which multiple structures of copper foil insulated by an insulating layer are stacked. In Figure 2, the coil assembly 10 is shown decomposed in the thickness direction of the insulating layer (hereinafter simply referred to as the "thickness direction"). Note that in Figure 2, in addition to the Z axis, the X axis and Y axis, which are orthogonal to the Z axis and mutually orthogonal, are shown. "Z axis direction" is a general term for the +Z direction and the -Z direction. Similarly, "X axis direction" is a general term for the +X direction and the -X direction, and "Y axis direction" is a general term for the +Y direction and the -Y direction. The XYZ axes in Figure 3 and subsequent drawings correspond to the XYZ axes in Figure 2. The "thickness direction" mentioned above is parallel to the Z-axis direction.

[0024] The first coil C1 has a structure in which a first subcoil section C11 and a second subcoil section C12 are stacked in the thickness direction. Similarly, the second coil C2 has a structure in which a third subcoil section C21 and a fourth subcoil section C22 are stacked in the thickness direction. Each of these four subcoil sections C11, C12, C21, and C22 consists of a coil wire and an insulating layer that is in contact with the coil wire in the thickness direction. The term "insulating layer" is a concept that includes not only the insulating layer provided between the coil wires, but also the solder resist that covers the coil wires located on the surface of the coil assembly 10. In this embodiment, for convenience, the first coil C1 will be described as being divided into two sub-coil sections C11 and C12. However, as described above, the coil assembly 10 has a structure in which multiple coil wires (winding sections 111, 121, 211, and 221, described later) are laminated and integrated with an insulating layer in between. Therefore, these two sub-coil sections C11 and C12 are not formed as independent components. The same applies to the two sub-coil sections C21 and C22 of the second coil C2.

[0025] The first subcoil section C11 comprises an insulating layer K11 and a winding section 111 composed of a coil wire in contact with the insulating layer K11. The winding section 111 comprises an end section 113, a wiring outlet section 112, and an outer end section E11. The end section 113 corresponds to the beginning of the winding of the first coil C1. In this embodiment, the end section 113 is located approximately in the center of the insulating layer K11 and inside the winding portion (winding coil pattern) of the winding section 111. The inside of the winding portion of the winding section 111 means the side of the winding section 111 that, when viewed in the thickness direction (Z-axis direction), is in the direction from the outer edge of the insulating layer K11 toward the center of the insulating layer K11 along the planar direction (direction along the XY plane) of the insulating layer K11. In other words, it means the region enclosed by the winding portion. The wiring outlet 112 extends outward from the end portion 113 and connects to the winding portion 111. The "outward direction" mentioned above refers to the direction from the center CP of the insulating layer toward the outer edge when viewed in the thickness direction, as shown in Figure 3. As shown in Figure 2, the winding portion 111 is arranged in a circular motion along the outer edge of the insulating layer K11. In this embodiment, it is circular in the counterclockwise direction. This circular direction is also called the "winding direction". In this embodiment, the winding portion 111 is circular for approximately one and a half turns in the winding direction. At this time, the second turn is located further outward than the first turn. The outer end E11 corresponds to the outer end of the two ends of the winding portion 111. That is, the end portion 113 corresponds to the inner end of the winding portion 111, and the outer end E11 corresponds to the outer end. In this embodiment, the outer end E11 is configured as the end of the straight portion 114 of the winding end portion of the winding portion 111. A connecting portion b1 is provided at the outer end E11. Furthermore, connecting portions b2, b3, and b4 are provided approximately in the center of the insulating layer K11. Details of connecting portions b1 to b4 will be described later.

[0026] The second subcoil section C12 has a similar configuration to the first subcoil section C11 described above. Specifically, the second subcoil section C12 comprises an insulating layer K12 and a winding section 121. The winding section 121 comprises an end section 123, a wiring outlet section 122, and an outer end section E12. The end section 123 corresponds to the end of the winding of the first coil C1. The outer end section E12 is configured as the end of the straight section 124 at the beginning of the winding in the winding section 121. A connecting section b1 is provided at the outer end section E12. Also, similar to the first subcoil section C11, connecting sections b2 to b4 are provided approximately in the center of the insulating layer K12.

[0027] The third subcoil section C21 has a similar configuration to the two subcoil sections C11 and C12 described above. Specifically, the third subcoil section C21 comprises an insulating layer K21 and a winding section 211. The winding section 211 is wound approximately one and a half times in the winding direction. At this time, the second winding is located further outward than the first winding. The winding section 211 comprises an end section 213, a wiring outlet section 212, and an outer end section E21. The end section 213 corresponds to the beginning of the winding of the second coil C2. The outer end section E21 is configured as the end of the straight section 214 at the end of the winding in the winding section 211. Similar to the two subcoil sections C11 and C12 described above, connecting sections b2 to b4 are provided approximately in the center of the insulating layer K21. In addition, a connecting section b5 is provided in the insulating layer K21. In the third subcoil section C21, the connecting section b5 is provided at the outer end section E21. The connecting portion b3 is provided at the end portion 213.

[0028] The fourth subcoil section C22 has a similar configuration to the three subcoil sections C11, C12, and C21 described above. Specifically, the fourth subcoil section C22 comprises an insulating layer K22 and a winding section 221. The winding section 221 comprises an end section 223, a wiring outlet section 222, and an outer end section E22. The end section 223 corresponds to the end of the winding of the second coil C2. The outer end section E22 is configured as the end of the straight section 224 at the beginning of the winding in the winding section 221. Similar to the three subcoil sections C11, C12, and C21 described above, connecting sections b2 to b4 are provided approximately in the center of the insulating layer K22. In addition, a connecting section b5 is provided in the insulating layer K22. In the fourth subcoil section C22, the connecting section b5 is provided at the outer end section E22. The connecting section b4 is provided at the end section 223.

[0029] In the coil assembly 10, the four sub-coil sections C11, C12, C21, and C22 described above are stacked in this order from top to bottom. Therefore, in two adjacent sub-coil sections in the stacking direction, the insulating layer of one section is in contact with the insulating layer of the other, and direct contact between the windings of these two sub-coil sections is suppressed.

[0030] Each connecting portion b1 to b5 is a via formed from a conductive material, such as copper. Connecting portion b1 connects winding portion 111 and winding portion 121. As a result, winding portion 111 and winding portion 211 are connected in series, forming a single coil wire. In this embodiment, connecting portion b1 is formed as a through-hole via that penetrates the coil assembly 10 in the thickness direction. Therefore, connecting portion b1 is also formed in the two sub-coil portions C21 and C22, which have winding portions 211 and 221 that are not directly connected to the two winding portions 111 and 121 of the first coil C1.

[0031] The connecting portion b2 connects the end of the winding portion 121 in the second subcoil portion C12 to the terminal portion t2 on the surface of the first subcoil portion C11. In this embodiment, the terminal portion t2 is electrically connected to the power transmission output circuit 130. The end portion 113 is electrically connected to the resonant capacitor 116. The connecting portion b2 is formed as a through-hole via that penetrates the coil assembly 10 in the thickness direction. Therefore, the connecting portion b2 is also formed in the two subcoil portions C21 and C22, which have winding portions 211 and 221 that are not directly connected to the two winding portions 111 and 121 of the first coil C1. The resonant capacitor 116 may be placed in the region inside the winding portion 111 in the substrate insulating layer K11. In this configuration, the coil assembly 10 and the resonant capacitor 116 are integrated into one unit.

[0032] The connecting portion b3 connects the terminal portion t3 on the surface of the first subcoil portion C11 to the beginning of the winding portion 211. The connecting portion b4 connects the terminal portion t4 on the surface of the first subcoil portion C11 to the end of the winding portion 221. In this embodiment, both connecting portions b3 and b4 are electrically connected to the variable capacitor 126. Both connecting portions b3 and b4 are formed as through-hole vias that penetrate the coil assembly 10 in the thickness direction. Therefore, connecting portions b3 and b4 are also formed in the two subcoil portions C11 and C12, which have winding portions 111 and 121 that are not directly connected to the two winding portions 211 and 221 of the second coil C2. The variable capacitor 126 may be placed in the region inside the winding portion 221 in the substrate insulating layer K22. In this configuration, the coil assembly 10 and the resonant capacitor 116 are integrated into one unit.

[0033] The connecting portion b5 connects the winding portion 211 and the winding portion 221. As a result, the winding portion 211 and the winding portion 221 are connected in series, forming a single coil wire. In this embodiment, the connecting portion b5 is formed as an inner via that penetrates only a portion of the thickness direction of the coil assembly 10. More specifically, the connecting portion b5 is formed as a via that penetrates the two sub-coil portions C21 and C22. Therefore, as shown in Figure 2, the connecting portion b5 is not formed in the other two sub-coil portions C11 and C12. Note that "inner via" is also called "interstitial via".

[0034] As shown in Figure 2, the widths of the two windings 111 and 121 of the first coil C1 are equal. Similarly, the widths of the two windings 211 and 221 of the second coil C2 are equal. Here, the ampere-turns of the first coil C1 are greater than those of the second coil C2. Therefore, the requirement to reduce the electrical resistance of the two windings 111 and 121 of the first coil C1 is stronger than that of the two windings 211 and 221 of the second coil C2. In the coil assembly 10 of the first embodiment, the widths of the two windings 111 and 121 are greater than the widths of the two windings 211 and 221. Therefore, the electrical resistance of the two windings 111 and 121 can be further reduced. Furthermore, even with this increased width, the winding amount is secured and the required ampere-turns are achieved by positioning the two windings 111 and 121 further outward. Furthermore, at least a portion of the two windings 211 and 221 of the second coil C2 is contained within the widthwise contour of the two windings 111 and 121 of the first coil C1 when viewed in the thickness direction. That is, the width and position of the windings 111, 121, 211, and 221 are adjusted so that when viewed in the +Z direction, the two windings 111 and 121 completely conceal at least a portion of the two windings 211 and 221.

[0035] In Figure 3, the thick solid line outer edge P1 indicates the outer edge of the contours of the two windings 111 and 121. The thin dashed line outer edge P2 indicates the outer edge of the contours of the two windings 211 and 221. "Outer edge of contour" refers to the edge of each winding, viewed in the thickness direction (Z-axis direction), where the portion of the contour along the four sides of the insulating layer closest to the outer edge is extended parallel to the four sides. Outer edge P1 is located outward relative to outer edge P2. Therefore, the first coil C1 can be reliably positioned outward relative to the second coil C2. Consequently, as described above, the electrical resistance can be reduced while ensuring the ampere-turn of the first coil C1.

[0036] Here, the configuration near the connecting portion b5 will be explained using Figure 4. The partial regions Ar12 and Ar22 shown in Figure 4 are enlarged versions of the partial regions Ar12 and Ar22 shown in Figure 2. As shown in Figure 4, the outer edge L2 in the outward direction at the outer end E22 of the winding portion 221 of the second coil C2 (fourth subcoil portion C22), that is, the outer edge L2 of the straight portion 224, is located inward from the outer edge L1 of the portion of the winding portion 121 of the first coil C1 (second subcoil portion C12) that corresponds to the outer end E22 of the second coil C2 (fourth subcoil portion C22) in the thickness direction (the straight portion 125 shown in Figure 2). For this reason, as shown in the upper part of Figure 6, at the left end, the third subcoil portion C21 and the fourth subcoil portion C22 are located inward from the first subcoil portion C11 and the second subcoil portion C12. Therefore, compared to the configuration of the comparative example shown in the lower part of Figure 6, the dimensions of the coil assembly 10 when viewed in the thickness direction (Z-axis direction) can be made smaller.

[0037] A3. Comparative example: The comparative example coil assembly 90 shown in Figure 5 includes a first coil C8 and a second coil C9. The first coil C8 comprises a first subcoil section C81 and a second subcoil section C82. The first subcoil section C81 comprises a winding section 811, an end section 813, and a wiring outlet section 812. The outer end E81 of the winding section 811 is formed to protrude outward from the straight section 814 at the end of the winding section 811. The second subcoil section C82 comprises a winding section 821, an end section 823, and a wiring outlet section 822. The outer end E82 of the winding section 821 is formed to protrude outward from the straight section 824 at the beginning of the winding section 821.

[0038] The second coil C9 comprises a first subcoil section C91 and a second subcoil section C92. The first subcoil section C91 comprises a winding section 911, an end section 913, and a wiring outlet section 912. The outer end E91 of the winding section 911 is formed to protrude outward from the straight section 914 at the end of the winding section 911. The second subcoil section C92 comprises a winding section 921, an end section 923, and a wiring outlet section 922. The outer end E92 of the winding section 921 is formed to protrude outward from the straight section 924 at the beginning of the winding section 921.

[0039] The four sub-coil sections C81, C82, C91, and C92 described above are all equipped with connecting sections b91, b92, b93, b94, and b95. Connecting section b91 connects the winding section 811 of the first sub-coil section C81 to the winding section 821 of the second sub-coil section C82. Connecting section b92 connects the terminal section t12 on the surface of the first sub-coil section C81 to the end of the winding section 821. Connecting section b93 connects the terminal section t13 on the surface of the first sub-coil section C81 to the beginning of the winding section C91. Connecting section b94 connects the terminal section t14 on the surface of the first sub-coil section C81 to the end of the winding section 921. Connecting section b95 connects the winding section 911 and the winding section 921.

[0040] In the comparative example, the connecting portion b95 is formed as a through-hole that penetrates the coil assembly 90 in the thickness direction. Therefore, in order to secure the placement area for the connecting portion b95, as shown in Figure 5, the winding portions 811 and 821 are positioned with a margin inward (opposite to the outward direction) compared to the outer edge of each insulating layer. Furthermore, the connecting portion b91 is positioned at the outer ends E81, E82, E91, and E92 that protrude outward from the straight portions 814, 824, 914, and 924 of each sub-coil portion C81, C82, C91, and C92. Therefore, the size of the insulating layer in the outward direction is increased by the amount that protrudes outward. For this reason, as shown in the lower part of Figure 6, the coil assembly 90 of the comparative example has a relatively large dimension when viewed in the thickness direction (Z-axis direction).

[0041] As is clear from Figure 6, the coil assembly 10 of the first embodiment has smaller dimensions in the thickness direction compared to the coil assembly 90 of the comparative example described above. Therefore, the size of the insulating layer can be reduced. Furthermore, since it is not necessary to cut out a hole in a part of the winding portion 111 of the first coil C1 and the winding portion 121 of the second coil C2, for example, in order to avoid the connection between the winding portion 211 and the winding portion 221, an increase in the electrical resistance of the winding portions 111 and 121 can be suppressed.

[0042] According to the coil assembly 10 of the first embodiment described above, the outer edge L2 of the outer ends E21 and E22 of the second coil C2, where the connecting portion b1 is provided, is located inside the outer edge L1 of the portion of the multiple winding portions 111 and 121 of the first coil C1 that corresponds to the outer ends E21 and E22 of the second coil C2 in the thickness direction. Therefore, compared to a configuration in which the outer edges of the outer ends E21 and E22 of the second coil C2 are located outside the outer edge L1 of the portion of the multiple winding portions 111 and 121 of the first coil C1 that corresponds to the outer ends E21 and E22 of the second coil C2 (straight portion 125) in the thickness direction, the size of the coil assembly 10 when viewed in the thickness direction can be reduced. Consequently, the size of the coil assembly 10 comprising multiple stacked coils C1 and C2 can be suppressed.

[0043] Furthermore, since the connecting portion b5 of the second coil C2 is formed by an inner via, the increase in the electrical resistance of the coil can be suppressed compared to a configuration in which it is formed by a through-hole via. Specifically, if the connecting portion b5 were formed by a through-hole via, such a through-hole via would interfere with the winding portions 111 and 121 of the first coil C1. Therefore, in order to avoid such interference, it would be necessary to hollow out a part of the winding portions 111 and 121 to create a hole and pass the through-hole via (connecting portion b5) through this hole. In such a configuration, the electrical resistance of the first coil C1 increases due to the creation of a hole in a part of the winding portions 111 and 121. In contrast, in the coil assembly 10 of the first embodiment, since the connecting portion b5 is formed by an inner via, it is not necessary to create a hole in the winding portions 111 and 121, and the increase in electrical resistance mentioned above can be suppressed.

[0044] Furthermore, since the ampere-turns of the first coil C1 are greater than those of the second coil C2, the first coil C1, with its larger ampere-turns, can be positioned further outward in the thickness direction. Therefore, compared to a configuration where the second coil C2 is positioned further outward than the first coil C1, the width of the winding portion of the first coil C1 can be made larger, and electrical resistance can be further reduced. Because the first coil C1, with its larger ampere-turns, has greater losses than the second coil C2, a reduction in electrical resistance is required. Accordingly, the coil assembly 10 of the first embodiment can meet this requirement.

[0045] Furthermore, since the outer edges P2 of the contours of the multiple windings 211 and 221 of the second coil C2 are located inward from the outer edges P1 of the contours of the multiple windings 111 and 121 of the first coil C1, the first coil C1 can be reliably positioned outward relative to the second coil C2. Also, since the outer edges P2 of the contours of the multiple windings 211 and 221 of the second coil C2 are located inward from the outer edges P1 of the contours of the multiple windings 111 and 121 of the first coil C1, the coil width of the first coil C1 can be increased, and the electrical resistance of the first coil C1 can be further reduced.

[0046] Furthermore, if we consider the outer shape of the insulating layer and the area of ​​the region without coil wire inside the winding (central part), at least a portion of the windings 211 and 221 of the second coil C2 is contained within the widthwise contour of the windings 111 and 121 of the first coil C1. This maximizes the coil width of the first coil C1 (the width of the multiple windings 111 and 121), thereby reducing the electrical resistance of the first coil C1. In addition, from another perspective, the following effects are achieved. That is, if we consider the coil width of the first coil C1 to be fixed, having at least a portion of the windings 211 and 221 of the second coil C2 contained within the widthwise contour of the windings 111 and 121 of the first coil C1 results in the effect of securing a larger area in the central part.

[0047] Furthermore, since the outer ends E11 and E12 of the multiple winding sections 111 and 121 of the first coil C1 are configured as the ends of the straight sections 114 and 124 along the winding direction of the first coil C1, the size of the first coil C1 as viewed in the thickness direction can be reduced compared to a configuration in which the outer ends E11 and E12 of the multiple winding sections 111 and 121 of the first coil C1 are configured as parts that protrude outward from the straight sections 114 and 124 (comparative example configuration). The same applies to the second coil C2.

[0048] Furthermore, since the connecting portion b1 of the first coil C1 is formed by a through-hole via and the connecting portion b5 of the second coil C2 is formed by an inner via, the manufacturing of the coil assembly 10 can be simplified compared to a configuration in which both connecting portions b1 and b5 are formed by inner vias, thereby reducing manufacturing time and costs. Generally, the manufacturing of inner vias, which are vias formed only in a portion of the thickness direction, is more complex than the manufacturing of through-hole vias that penetrate the entire thickness direction, resulting in increased manufacturing time and costs.

[0049] B. Second Embodiment: The coil assembly 20 of the second embodiment shown in Figures 7 to 9 comprises a first coil C3 and a second coil C4. The first coil C3 is also called a "power transmission coil," similar to the first coil C1 in the first embodiment. The second coil C4 is also called a "variable characteristic coil," similar to the second coil C2 in the first embodiment. In the second embodiment, the first coil C3 has a structure in which a total of six subcoil sections (first subcoil section C31, second subcoil section C32, third subcoil section C33, fourth subcoil section C34, fifth subcoil section C35, sixth subcoil section C36) are stacked in this order in the thickness direction. The second coil C4 has a structure in which two subcoil sections (seventh subcoil section C41, eighth subcoil section C42) are stacked in the thickness direction. As with the first embodiment, the first coil C3 is merely divided into six sub-coil sections C31 to C36 for convenience, and these sub-coil sections C31 to C36 are not formed as independent components. The same applies to the second coil C4. As shown in Figures 7 to 9, the coil wires provided in each sub-coil section C31 to C36 and C41 to C42 are thinner than those in the first embodiment. This reduces losses caused by eddy currents. In addition, since three winding sections are connected in parallel in each coil C3 and C4, the total cross-sectional area of ​​the winding sections in coils C3 and C4 is relatively large. This suppresses the increase in electrical resistance of coils C3 and C4 due to the thinning of the wires. Furthermore, the number of sub-coil sections in the first coil C3, in other words, the number of layers and winding sections, is greater than the number of sub-coils in the second coil C4, in other words, the number of layers and winding sections. Thus, in the second embodiment, the electrical resistance of the first coil C3 is further reduced by increasing the number of subcoils (number of layers, number of windings) of the first coil C3, which has a larger ampere-turn capacity.

[0050] The first subcoil section C31 comprises an insulating layer K31 and three winding sections 311, 312, and 313, each composed of a coil wire in contact with the insulating layer K31. One end of each of these three winding sections 311 to 313 is connected to a common end section 319 located approximately in the center of the insulating layer K31. On the other hand, the other ends of each of the three winding sections 311 to 313 are located at different positions on the insulating layer K31. Specifically, the other end of winding section 311 is located at a corner of the insulating layer K31. Three connecting sections b21, b22, and b23 are provided at this corner. Of these three connecting sections b21, b22, and b23, connecting section b21 is located at the other end of winding section 311. The other end of winding section 313 is located at the corner adjacent to the corner where the other end of winding section 311 is located. This corner is provided with three connecting parts b41, b42, and b43. Of these three connecting parts b41, b42, and b43, connecting part b41 is provided at the other end of the winding part 313. The other end of the winding part 312 is located approximately midway between the corner where the other end of the winding part 311 is provided and the corner where the other end of the winding part 313 is provided, and is positioned near the outer edge of the insulating layer K31. Three connecting parts b31, b32, and b33 are provided at a position approximately midway between the corner where the other end of the winding part 313 is provided. Of these three connecting parts b31, b32, and b33, connecting part b31 is provided at the other end of the winding part 312.

[0051] Each of the aforementioned connecting portions b21-b23, b31-b33, and b41-b43 is formed as a through-hole via that penetrates the coil assembly 20 in the thickness direction. Each sub-coil portion C31-C36 and C41-C42 is provided with connecting portions b11, b12, b13, and b14 in addition to the aforementioned connecting portions b21-b23, b31-b33, and b41-b43. As shown in Figure 7, the surface of the first sub-coil portion C31 is provided with four terminal portions t21, t22, t23, and t24. Connecting portion b11 connects terminal portion t21 to the end portion 349 of the fourth sub-coil portion C34, the end portion 359 of the fifth sub-coil portion C35, and the end portion 369 of the sixth sub-coil portion C36, which will be described later. The connecting portion b12 connects the end portion 319 of the first subcoil portion C31, the end portion 329 of the second subcoil portion C32, and the end portion 339 of the third subcoil portion C33 to each other. The connecting portion b13 connects the terminal portion t23 of the first subcoil portion C31 to the end portion 419 of the seventh subcoil portion C41. The connecting portion b14 connects the terminal portion t24 of the first subcoil portion C31 to the end portion 429 of the eighth subcoil portion C42.

[0052] The second subcoil section C32 comprises an insulating layer K32 and three winding sections 321, 322, and 323, each composed of a coil wire in contact with the insulating layer K32. One end of each of these three winding sections 321 to 323 is connected to a common end section 329 located approximately in the center of the insulating layer K31. On the other hand, the other ends of each of the three winding sections 311 to 323 are located at different positions on the insulating layer K31. A connecting section b22 is provided at the other end of winding section 321. A connecting section b32 is provided at the other end of winding section 322. A connecting section b42 is provided at the other end of winding section 323. In winding section 323, the portion continuing from the connecting section b42 is configured as a bypass section 325 that detours outward to avoid the connecting section b42 and the adjacent connecting section b41. As described above, since the other end of the winding portion 313 is located at the corner of the insulating layer K31, the bulging coil wire path (i.e., the bypass portions 325 and 335) that bypasses the connecting portion b41 starting from this other end can be arranged using the empty space at the corners of the insulating layers K32 and K33. Therefore, compared to a configuration in which the bypass portion is located on a straight section of the insulating layer instead of a corner, it is possible to suppress the increase in the dimensions of the insulating layer (the vertical or horizontal dimensions when viewed from above) in order to secure the path of the coil wire that bulges for the bypass.

[0053] The third subcoil section C33 comprises an insulating layer K33 and three winding sections 331, 332, and 333, each composed of a coil wire in contact with the insulating layer K33. One end of each of these three winding sections 331 to 333 is connected to a common end section 339 located approximately in the center of the insulating layer K33. On the other hand, the other ends of each of the three winding sections 331 to 333 are located at different positions within the insulating layer K33. A connecting section b23 is provided at the other end of winding section 331. A connecting section b33 is provided at the other end of winding section 332. A connecting section b43 is provided at the other end of winding section 333. In winding section 333, the portion continuing from the connecting section b43 is configured as a bypass section 335 that detours outward to avoid the connecting sections b41 and b42 adjacent to the connecting section b43.

[0054] The fourth subcoil section C34 comprises an insulating layer K34 and three winding sections 341, 342, and 343, each composed of a coil wire in contact with the insulating layer K34. One end of each of these three winding sections 341 to 343 is connected to a common end section 349 located approximately in the center of the insulating layer K34. On the other hand, the other ends of each of the three winding sections 341 to 343 are located at different positions within the insulating layer K34. A connecting section b21 is provided at the other end of winding section 341. A connecting section b31 is provided at the other end of winding section 342. A connecting section b41 is provided at the other end of winding section 343. In winding section 341, the portion continuing from the connecting section b21 is configured as a bypass section 345 that detours outward to avoid the connecting sections b22 and b23 adjacent to the connecting section b21.

[0055] The fifth subcoil section C35 comprises an insulating layer K35 and three winding sections 351, 352, and 353, each composed of a coil wire in contact with the insulating layer K35. One end of each of these three winding sections 351 to 353 is connected to a common end section 359 located approximately in the center of the insulating layer K35. On the other hand, the other ends of each of the three winding sections 351 to 353 are located at different positions in the insulating layer K35. A connecting section b22 is provided at the other end of winding section 351. A connecting section b32 is provided at the other end of winding section 352. A connecting section b42 is provided at the other end of winding section 353. In winding section 351, the portion continuing from the connecting section b22 is configured as a bypass section 355 that detours outward to avoid the connecting section b22 and the adjacent connecting section b23.

[0056] The sixth subcoil section C36 comprises an insulating layer K36 and three winding sections 361, 362, and 363, each composed of a coil wire in contact with the insulating layer K36. One end of each of these three winding sections 361 to 363 is connected to a common end section 369 located approximately in the center of the insulating layer K36. On the other hand, the other ends of each of the three winding sections 361 to 363 are located at different positions within the insulating layer K36. A connecting section b23 is provided at the other end of winding section 361. A connecting section b33 is provided at the other end of winding section 362. A connecting section b43 is provided at the other end of winding section 333.

[0057] In the first subcoil section C31 and the fourth subcoil section C34, winding section 311 and winding section 341 are connected in series with each other. Similarly, winding section 312 and winding section 342 are connected in series with each other, and winding section 313 and winding section 343 are connected in series with each other. In addition, in the second subcoil section C32 and the fifth subcoil section C35, winding section 321 and winding section 351 are connected in series with each other. Similarly, winding section 322 and winding section 352 are connected in series with each other, and winding section 323 and winding section 353 are connected in series with each other. In addition, in the third subcoil section C33 and the sixth subcoil section C36, winding section 331 and winding section 361 are connected in series with each other. Similarly, winding section 332 and winding section 362 are connected in series with each other, and winding section 333 and winding section 363 are connected in series with each other. Then, three sets of winding sections, each consisting of two winding sections connected in series with each other, are connected in parallel with each other.

[0058] The seventh subcoil section C41 comprises an insulating layer K41 and three winding sections 411, 412, and 413, each composed of a coil wire in contact with the insulating layer K41. One end of each of these three winding sections 411 to 413 is connected to a common end section 419 located approximately in the center of the insulating layer K41. On the other hand, the other ends of each of the three winding sections 411 to 413 are located at different positions within the insulating layer K41. A connecting section b51 is provided at the other end of winding section 411. A connecting section b52 is provided at the other end of winding section 412. A connecting section b53 is provided at the other end of winding section 413. The three connecting sections b51 to b53 are located approximately opposite each other with respect to the three connecting sections b31 to b33, with the center of the insulating layer K41 in between.

[0059] The eighth subcoil section C42 comprises an insulating layer K42 and three winding sections 421, 422, and 423, each composed of a coil wire in contact with the insulating layer K42. One end of each of these three winding sections 421 to 423 is connected to a common end section 429 located approximately in the center of the insulating layer K42. On the other hand, the other ends of each of the three winding sections 421 to 423 are located at different positions in the insulating layer K42. A connecting section b51 is provided at the other end of winding section 421. A connecting section b52 is provided at the other end of winding section 422. A connecting section b53 is provided at the other end of winding section 423. The three connecting sections b51 to b53 are located approximately opposite each other with respect to the three connecting sections b31 to b33, with the center of the insulating layer K42 in between.

[0060] The connecting portion b51 connects the winding portion 411 and the winding portion 421. The connecting portion b52 connects the winding portion 412 and the winding portion 422. The connecting portion b53 connects the winding portion 413 and the winding portion 423. All three of these connecting portions b51 to b53 are formed by inner vias formed in a part of the thickness direction in the coil assembly 10a.

[0061] In the seventh subcoil section C41 and the eighth subcoil section C42, the winding section 411 and the winding section 421 are connected in series with each other. Similarly, the winding section 412 and the winding section 422 are connected in series with each other, and the winding section 413 and the winding section 423 are connected in series with each other.

[0062] Figure 10 shows enlarged views of the partial region Ar36 shown in Figure 8 and the partial region Ar42 shown in Figure 9. As shown in Figure 10, the outer edge L4 at the outer end of the winding portion 421-423 of the second coil C4 (eighth sub-coil portion C42) is located inward from the outer edge L3 of the portion of the winding portion 341-343, 351-353, and 361-363 of the first coil C3 (sub-coil portion C34-C36) that corresponds to the outer end of the second coil C4 in the thickness direction. Therefore, the same effect as in the first embodiment is achieved, that is, as shown in Figure 11, the dimensions of the coil assembly 20 when viewed in the thickness direction (Z-axis direction) can be made smaller.

[0063] The coil assembly 20 of the second embodiment described above provides the same effects as the coil assembly 10 of the first embodiment. In addition, since the number of windings in the first coil C3 is greater than the number of windings in the second coil C4, the electrical resistance of the first coil C3 can be reduced compared to a configuration in which the number of windings is the same as or less than that of the second coil C4.

[0064] C. Other embodiments: (C1) In the first embodiment, the ampere-turns of the first coil C1 were greater than those of the second coil C2. In the second embodiment, the ampere-turns of the first coil C3 were greater than those of the second coil C4. However, the disclosure is not limited to these. The ampere-turns of the first coil C1 may be less than or equal to those of the second coil C2. Also, the ampere-turns of the first coil C3 may be less than or equal to those of the second coil C4.

[0065] (C2) In the first embodiment, the outer edge P2 of the contours of the winding portions 211 and 221 of the second coil C2 was located inside the outer edge P1 of the contours of the winding portions 111 and 121 of the first coil C1, but the disclosure is not limited thereto. A portion of the outer edge P2 of the contours of the winding portions 211 and 221 of the second coil C2 may be located outside the outer edge P1 of the contours of the winding portions 111 and 121 of the first coil C1, when viewed in the thickness direction.

[0066] (C3) In the first embodiment, a portion of the winding portions 211 and 221 of the second coil C2 was contained within the widthwise contour of the winding portions 111 and 121 of the first coil C1 when viewed in the thickness direction, but the disclosure is not limited thereto. The entirety of the winding portions 211 and 221 of the second coil C2 may be contained within the widthwise contour of the winding portions 111 and 121 of the first coil C1 when viewed in the thickness direction. Alternatively, the entirety of the winding portions 211 and 221 of the second coil C2 may not be contained within the widthwise contour of the winding portions 111 and 121 of the first coil C1 when viewed in the thickness direction.

[0067] (C4) In the first embodiment, the outer ends E11 and E12 of the first coil C1, where the connecting portion b1 is provided in the winding portions 111 and 121, were configured as the ends of the straight portions 114 and 124 along the winding direction, but the disclosure is not limited thereto. Similar to the comparative example, they may be configured as portions that protrude outward from the straight portions 114 and 124.

[0068] (C5) In the first embodiment, the first coil C1 and the second coil C2 were the "transmission coil" and the "variable coil" in a contactless power supply device, but the disclosure is not limited thereto. The first coil C1 and the second coil C2 may be applied to any two types of coils used in magnetic coupling with each other. For example, the first coil C1 and the second coil C2 may be applied to the transmission coil included in the transmission resonant circuit of a contactless power supply device, and to the relay coil included in the relay resonant circuit that is magnetically coupled to the transmission coil. Also, for example, the first coil C1 and the second coil C2 may be applied to two types of coils used in a transformer. The same applies to the first coil C3 and the second coil C4 in the second embodiment. Furthermore, the first coil C1 and the second coil C2, or the first coil C3 and the second coil C4, may be applied to two coils used without magnetic coupling with each other. Even in such a configuration, the coil assembly, which is packaged by stacking the two coils, can be miniaturized, and the increase in the electrical resistance of each coil can be suppressed. Although coils C1 to C4 in each of the above embodiments were all coils without a core (magnetic material), they may also be coils with a core.

[0069] (C6) In each embodiment, the winding start of each coil C1 to C4 was located inside the winding portion of the winding section, but the disclosure is not limited thereto. It may be located outside the winding portion. With this configuration, since the end portion is not located inside the winding portion, the inner region of the winding portion (the central region when the insulating layer is viewed in plan) can be utilized more widely. In addition, in this configuration, the connecting portion is located close to the inner region of the winding portion, but one connecting portion can be located outward relative to the connecting portion of the other coil. For this reason as well, the inner region of the winding portion can be utilized more widely. Examples of utilization include, for example, increasing the winding portion in this region, or, in a configuration in which other devices (e.g., other circuit boards) are placed in contact with the coil assembly in the thickness direction, the above region can be used as a retraction region (accommodation region) for the structure of the other device.

[0070] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in each embodiment corresponding to the technical features in the embodiments described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-mentioned problems, or to achieve some or all of the above-mentioned effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. The features of this disclosure are as follows: [Form 1] A coil assembly (10), The device has a structure in which coil wires are formed in an insulating layer (K11~K22), and comprises a first coil (C1) and a second coil (C2) stacked on top of each other in the thickness direction of the insulating layer. The first coil and the second coil each have a plurality of winding portions (111 to 221) stacked in the thickness direction, and connecting portions (b1, b5) that connect the plurality of winding portions to each other. The connecting portion (b5) of the second coil is provided at the outer end of the winding direction of the plurality of winding portions of the second coil, when viewed in the thickness direction. With the direction from the center to the outer edge of the insulating layer in the thickness direction defined as the outward direction, the outward outer edge (L2) at the outer end of the second coil is located inward from the outward outer edge (L1) of the portion of the plurality of windings of the first coil that corresponds to the outer end of the second coil in the thickness direction. Coil assembly. [Form 2] In the coil assembly described in Embodiment 1, A coil assembly in which, in the operating state of the coil assembly, the ampere-turns of the first coil are greater than those of the second coil. [Form 3] In the coil assembly described in Embodiment 1 or Embodiment 2, A coil assembly in which, when viewed in the thickness direction, the outer edge (P2) of the contour of the plurality of windings of the second coil is located inward from the outer edge (P1) of the contour of the plurality of windings of the first coil. [Form 4] In the coil assembly described in any of Forms 1 to 3, A coil assembly in which at least a portion of the winding portion of the second coil is contained within the widthwise contour of the winding portion of the first coil when viewed in the thickness direction. [Form 5] In the coil assembly described in any of Forms 1 to 4, The connecting portion of the first coil is provided at the outer end of the winding direction of the plurality of winding portions of the first coil, A coil assembly in which the outer ends of the plurality of winding portions of the first coil are configured as the ends of the straight portions of the first coil along the winding direction. [Form 6] In the coil assembly described in any of Forms 1 to 5, A coil assembly in which the number of windings in the first coil is greater than the number of windings in the second coil. [Form 7] In the coil assembly described in any one of the forms 1 to 6, The connecting portion of the first coil is formed by through-hole vias that penetrate the insulating layer in the thickness direction. The connecting portion of the second coil is formed by an inner via formed in a part of the thickness direction of the insulating layer, in a coil assembly. [Explanation of symbols]

[0071] 10...Coil assembly, C1...First coil, C2...Second coil, b1...Connecting part, b5...Connecting part, L1...Outer edge, L2...Outer edge

Claims

1. A coil assembly (10), The device has a structure in which coil wires are formed in insulating layers (K11 to K22), and comprises a first coil (C1) and a second coil (C2) stacked on top of each other in the thickness direction of the insulating layers. The first coil and the second coil each have a plurality of winding portions (111 to 221) stacked in the thickness direction, and connecting portions (b1, b5) that connect the plurality of winding portions to each other. The connecting portion (b5) of the second coil is provided at the outer end of the winding direction of the plurality of winding portions of the second coil, when viewed in the thickness direction. With the direction from the center to the outer edge of the insulating layer as viewed in the thickness direction, the outer edge (L2) of the outer end of the second coil in the outer direction is located inward from the outer edge (L1) of the portion of the plurality of windings of the first coil that corresponds to the outer end of the second coil in the thickness direction. The number of windings in the first coil is greater than the number of windings in the second coil. Coil assembly.

2. In the coil assembly according to claim 1, The first coil and the second coil are used in a contactless power supply system, magnetically coupled to each other. A coil assembly in which, in the operating state of the first coil and the second coil, the ampere-turns of the first coil are greater than those of the second coil.

3. A coil assembly (10), The device has a structure in which coil wires are formed in insulating layers (K11 to K22), and comprises a first coil (C1) and a second coil (C2) stacked on top of each other in the thickness direction of the insulating layers. The first coil and the second coil each have a plurality of winding portions (111 to 221) stacked in the thickness direction, and connecting portions (b1, b5) that connect the plurality of winding portions to each other. The connecting portion (b5) of the second coil is provided at the outer end of the winding direction of the plurality of winding portions of the second coil, when viewed in the thickness direction. With the direction from the center to the outer edge of the insulating layer as viewed in the thickness direction, the outer edge (L2) of the outer end of the second coil in the outer direction is located inward from the outer edge (L1) of the portion of the plurality of windings of the first coil that corresponds to the outer end of the second coil in the thickness direction. The first coil and the second coil are used in a contactless power supply system, magnetically coupled to each other. In the operating state of the first coil and the second coil, the ampere-turn of the first coil is greater than the ampere-turn of the second coil. Coil assembly.

4. In the coil assembly according to claim 3, A coil assembly in which, when viewed in the thickness direction, the outer edge (P2) of the contour of the plurality of winding portions of the second coil is located inward from the outer edge (P1) of the contour of the plurality of winding portions of the first coil.

5. In the coil assembly according to claim 4, A coil assembly in which at least a portion of the winding portion of the second coil is contained within the widthwise contour of the winding portion of the first coil when viewed in the thickness direction.

6. In the coil assembly according to claim 1, The connecting portion of the first coil is provided at the outer end of the winding direction of the plurality of winding portions of the first coil, A coil assembly in which the outer ends of the plurality of winding portions of the first coil are configured as the ends of the straight portions of the first coil along the winding direction.

7. In the coil assembly according to any one of claims 1 to 6, The connecting portion of the first coil is formed by through-hole vias that penetrate the insulating layer in the thickness direction. The connecting portion of the second coil is formed by an inner via formed in a part of the thickness direction of the insulating layer, in a coil assembly.

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