Coil device

Abstract

To provide a coil device having sufficiently large magnetic coupling.SOLUTION: The coil device 10 includes the first conductors 30, the second conductors 40 disposed inside the first conductors 30 and at least partially extending along the first conductors 30, the cores 20a and 20b in which the first conductors 30 and the second conductors 40 are disposed, and the insulating film 70 covering the outer peripheral surfaces, the inner peripheral surfaces, and the side surfaces connecting the outer peripheral surfaces and the inner peripheral surfaces of the second conductors 40. A gap having a predetermined length in a direction in which the outer peripheral surface of the second conductor 40 and the inner peripheral surface of the first conductor 30 face each other is provided between the insulating film 70 covering the outer peripheral surface of the second conductor 40 and the inner peripheral surface of the first conductor, the second conductor 40 has a main body portion bent in a U shape, and the gap is provided from one end to the other end of the main body portion along an extending direction of the main body portion.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a coil device used, for example, as an inductor or the like. [Background Art]

[0002] As a coil device used as an inductor or the like, for example, the coil device described in Patent Document 1 is known. The coil device described in Patent Document 1 includes two conductors and a core in which the two conductors are disposed. In the coil device described in Patent Document 1, magnetic coupling between the two conductors is increased by forming a region where no magnetic body is disposed between the two conductors.

[0003] However, with the coil device described in Patent Document 1, due to its configuration, it is difficult to sufficiently increase the magnetic coupling between the two conductors, and there is a demand for a technology that enables sufficient increase of magnetic coupling between respective conductors. [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2007-184509 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a coil device having sufficiently large magnetic coupling. [Means for Solving the Problem]

[0006] To achieve the above object, the coil device according to a first aspect of the present invention is: a first conductor; a second conductor disposed inside the first conductor, at least a part of the second conductor extending along the first conductor; The device has a core in which the first conductor and the second conductor are arranged, An insulating layer is formed at least between the first conductor and the second conductor.

[0007] A coil device according to a first aspect of the present invention has a first conductor and a second conductor disposed inside the first conductor and at least a portion of which extends along the first conductor, and an insulating layer is formed between at least the first conductor and the second conductor. In this case, the first conductor and the second conductor are arranged overlapping (double) with a predetermined gap between them, and under such arrangement, magnetic flux can be efficiently transmitted between the first conductor and the second conductor, and the magnetic coupling between the first conductor and the second conductor can be made sufficiently large. Furthermore, since the first conductor and the second conductor are sufficiently insulated through the insulating layer interposed between them, it is possible to prevent short-circuit failures from occurring between the first conductor and the second conductor, and a highly reliable coil device can be realized.

[0008] Preferably, the second conductor is made of a flat rectangular wire, and the insulating layer is made of an insulating coating formed on the surface of the second conductor. By using a flat rectangular wire with an insulating coating as the second conductor in this way, it becomes possible to interpose an insulating layer between the first conductor and the second conductor simply by placing the second conductor on top of the first conductor, and the above-mentioned effects can be easily obtained.

[0009] Preferably, the first conductor and the second conductor are connected via a fusion layer formed by fusing the insulating layer formed on the surface of the second conductor. With this configuration, it is possible to fill the space between the first conductor and the second conductor with an insulating layer consisting of the fusion layer without any gaps, thereby ensuring sufficient insulation between the first conductor and the second conductor.

[0010] Preferably, the insulating layer is formed between the core and the first conductor or the second conductor. With this configuration, the core and the first conductor or the second conductor are sufficiently insulated through the insulating layer interposed between them, making it possible to prevent short-circuit failures from occurring between the core and the first conductor or the second conductor, and thus realizing a highly reliable coil device.

[0011] Preferably, the first conductor is made of a conductive plate with a plating layer formed on its surface. With this configuration, bonding materials such as solder or conductive adhesive can easily adhere to the surface of the first conductor, and the first conductor can be firmly connected to the mounting surface of the mounting substrate. In particular, when solder is used as the bonding material, solder fillets can be easily formed on the side surface of the first conductor, thereby making the connection between the first conductor and the mounting surface of the mounting substrate stronger.

[0012] Preferably, the second conductor has a mounting-facing surface that can face the mounting surface, and the mounting-facing surface consists of a joinable surface on which the insulating layer is not formed and a non-joint surface on which the insulating layer is formed, wherein the non-joint surface is formed closer to the first conductor than the joinable surface. In this case, the joining member described above is more likely to adhere to the joinable surface, while it is less likely to adhere to the non-joint surface. Therefore, it is possible to prevent the joining member attached to the joinable surface from protruding toward the first conductor with the non-joint surface, and short-circuit failures between the first conductor and the second conductor can be effectively prevented.

[0013] Preferably, the bondable surface has a raised portion that rises from the mounting surface. With this configuration, it is possible to attach the bonding member not only to the surface facing the mounting surface of the mounting substrate, but also to the raised portion. Therefore, when solder is used as the bonding member, it is possible to form a solder fillet on the raised portion of the bondable surface, and the second conductor can be firmly connected to the mounting surface of the mounting substrate. Furthermore, with the above configuration, it is possible to prevent, for example, the formation of solder balls on the mounting portion of the second conductor.

[0014] Preferably, the end of the first conductor has an outer bend that bends outward, and the end of the second conductor has an inner bend that bends inward, and the radius of curvature of the inner surface of the outer bend is greater than the radius of curvature of the outer surface of the inner bend. In this case, the bending angle of the inner surface of the outer bend (the portion of the inner surface of the first conductor where the outer bend is located) is smaller than the bending angle of the outer surface of the inner bend (the portion of the outer surface of the second conductor where the inner bend is located). Therefore, the outer surface of the inner bend bends sharply near the mounting surface of the mounting substrate, while the inner surface of the outer bend bends gently from a position away from the mounting surface of the mounting substrate. Thus, a relatively large space is formed between the inner surface of the outer bend and the outer surface of the inner bend, which effectively prevents short-circuit failures from occurring between the first conductor and the second conductor around the mounting surface of the mounting substrate.

[0015] Preferably, the cross-sectional area of ​​the first conductor perpendicular to its extending direction is larger than the cross-sectional area of ​​the second conductor perpendicular to its extending direction. With this configuration, the DC resistance of the first conductor can be made smaller than that of the second conductor.

[0016] Preferably, the bottom surface of the core is positioned at a distance from the mounting surface. This configuration makes it possible to ensure sufficient insulation between the bottom surface of the core and the mounting surface of the mounting substrate, and in particular when the core is made of a metallic magnetic material, it is possible to effectively prevent short-circuit defects from occurring between the bottom surface of the core and the mounting surface of the mounting substrate.

[0017] Preferably, an insulating coating layer is formed on at least the bottom surface of the core. With this configuration, sufficient insulation can be ensured between the bottom surface of the core and the second conductor (or the first conductor), and between the bottom surface of the core and the mounting surface of the mounting substrate, via the insulating coating layer.

[0018] Preferably, the mounting portion of the first conductor and the mounting portion of the second conductor are insulated from each other via a resin spacer. This configuration effectively prevents short-circuit failures from occurring between the first mounting portion and the second mounting portion.

[0019] To achieve the above objective, the coil device according to a second aspect of the present invention is: A first conductor having a first outer mounting portion formed at one end and a second outer mounting portion formed at the other end, A second conductor is disposed inside the first conductor and has a first inner mounting portion formed at one end and a second inner mounting portion formed at the other end. A core in which the first conductor and the second conductor are arranged, The resin spacer has a first lateral insulating portion disposed between the first outer mounting portion and the first inner mounting portion, and a second lateral insulating portion disposed between the second outer mounting portion and the second inner mounting portion.

[0020] A coil device according to a second aspect of the present invention includes a first conductor having a first outer mounting portion formed at one end and a second outer mounting portion formed at the other end, and a second conductor arranged inside the first conductor and having a first inner mounting portion formed at one end and a second inner mounting portion formed at the other end. That is, in the coil device according to the second aspect of the present invention, similar to the coil device according to the first aspect of the present invention, the first conductor and the second conductor are arranged overlapping (doubled) with a predetermined distance between them, so that magnetic flux can be efficiently transmitted between the first conductor and the second conductor, and the magnetic coupling between the first conductor and the second conductor can be made sufficiently large.

[0021] Also, the coil device according to the second aspect of the present invention includes a resin spacer having a first lateral insulating portion arranged between a first outer mounting portion and a first inner mounting portion, and a second lateral insulating portion arranged between a second outer mounting portion and a second inner mounting portion. By arranging the first lateral insulating portion between the first outer mounting portion and the first inner mounting portion, a sufficient insulation distance therebetween can be sufficiently secured via the first lateral insulating portion, and the first outer mounting portion and the first inner mounting portion can be sufficiently insulated from each other. Similarly, by arranging the second lateral insulating portion between the second outer mounting portion and the second inner mounting portion, a sufficient insulation distance therebetween can be sufficiently secured via the second lateral insulating portion, and the second outer mounting portion and the second inner mounting portion can be sufficiently insulated from each other. Therefore, it is possible to prevent the occurrence of a short circuit defect between the first conductor and the second conductor, and a highly reliable coil device can be achieved.

[0022] Preferably, a bottom surface of the resin spacer is arranged above respective bottom surfaces of the first inner mounting portion and the second inner mounting portion, and is also arranged above respective bottom surfaces of the first outer mounting portion and the second outer mounting portion. By adopting such a configuration, when the coil device is mounted on a mounting substrate with the resin spacer attached thereto, it is possible to prevent the resin spacer from interfering with (contacting) the mounting substrate, and sufficient mounting strength between the coil device and the mounting substrate can be sufficiently secured.

[0023] Preferably, the resin spacer is disposed between one end portion and the other end portion of the second conductor, between the bottom surface of the core and the first inner mounting portion, and has an inner insulating portion disposed between the bottom surface of the core and the second inner mounting portion. By arranging (a part of) the inner insulating portion between the bottom surface of the core and the first inner mounting portion, a sufficient insulation distance therebetween can be sufficiently secured via the inner insulating portion, and sufficient insulation between the bottom surface of the core and the first inner mounting portion can be achieved. Similarly, by arranging (a part of) the inner insulating portion between the bottom surface of the core and the second inner mounting portion, a sufficient insulation distance therebetween can be sufficiently secured via the inner insulating portion, and sufficient insulation between the bottom surface of the core and the second inner mounting portion can be achieved.

[0024] Furthermore, by arranging (a part of) the inner insulating portion between the bottom surface of the core and the first inner mounting portion and filling the space therebetween with (a part of) the inner insulating portion, when connecting the first inner mounting portion to a land pattern of a mounting substrate by, for example, solder, the problem that the first inner mounting portion and the bottom surface of the core are connected by solder balls (occurrence of a short-circuit defect) can be effectively prevented. Similarly, by arranging (a part of) the inner insulating portion between the bottom surface of the core and the second inner mounting portion and filling the space therebetween with (a part of) the inner insulating portion, when connecting the second inner mounting portion to a land pattern of a mounting substrate by, for example, solder, the problem that the second inner mounting portion and the bottom surface of the core are connected by solder balls (occurrence of a short-circuit defect) can be effectively prevented.

[0025] A first gap is formed between the first lateral insulating portion and one end of the inner insulating portion in the first direction, and a second gap is formed between the second lateral insulating portion and the other end of the inner insulating portion in the first direction. The first lateral insulating portion, the second lateral insulating portion, and the inner insulating portion each extend along a second direction perpendicular to the first direction, and the resin spacer may have a first connecting portion that connects one end of each of the first lateral insulating portion, the second lateral insulating portion, and the inner insulating portion in the second direction along the first direction. With this configuration, it becomes possible to fit one end of the second conductor into the resin spacer through the first gap and the other end of the second conductor into the resin spacer through the second gap, making it easier to attach the resin spacer to the second conductor. Furthermore, by connecting the first lateral insulating section, the second lateral insulating section, and the inner insulating section with a connecting section, it becomes possible to construct a resin spacer that integrates these components via the connecting section, making it easier to attach the resin spacer to the second conductor compared to when these components are constructed separately.

[0026] Preferably, at least one of the upper and lower surfaces of the first connection portion is formed with a first outward inclined portion that slopes downward toward the outside in the second direction. When, for example, the first and second conductors are attached to the core after the resin spacer has been attached to the second conductor, the above configuration makes it possible to prevent the connection portion of the resin spacer from interfering with (contacting) the bottom surface of the core during this process, and thus the process can be carried out easily.

[0027] Preferably, at the other end of the inner insulating portion located on the opposite side of the second direction from the first connecting portion, a second outer inclined portion is formed on at least one of the upper and lower surfaces of the inner insulating portion, which slopes downward toward the outside in the second direction. With this configuration, it is possible to prevent the inner insulating portion of the resin spacer from interfering with (contacting) the bottom surface of the core, etc., when attaching the resin spacer to the second conductor, and the attachment of the resin spacer becomes smoother.

[0028] Preferably, at the other end of the inner insulating portion located on the opposite side of the first connection portion in the second direction, the width of the inner insulating portion along the first direction decreases as it moves outward in the second direction. This configuration makes it possible to prevent the ends of the resin spacer in the first direction from interfering with (contacting) one end and the other end of the second conductor when attaching the resin spacer to the second conductor, and makes the attachment of the resin spacer smoother.

[0029] Preferably, the resin spacer has a projection that protrudes from the bottom surface of the resin spacer and is positioned at least partially between the first tip of the first inner mounting portion and the second tip of the second inner mounting portion. With this configuration, it is possible to properly insulate the first tip and the second tip via the projection, and problems such as them being connected by solder balls or the like (occurrence of short-circuit defects) can be prevented.

[0030] Preferably, the bottom surface of the resin spacer has a first stepped surface located on one side of the protrusion and a second stepped surface located on the other side of the protrusion, with the first inner mounting portion in contact with the first stepped surface and the second inner mounting portion in contact with the second stepped surface. With this configuration, the first inner mounting portion is fixed to the first stepped surface and the second inner mounting portion is fixed to the second stepped surface, so that the resin spacer can be attached to the second conductor in a stable state.

[0031] A first gap is formed between the first lateral insulating portion and one end of the inner insulating portion in the first direction, a second gap is formed between the second lateral insulating portion and the other end of the inner insulating portion in the first direction, the first lateral insulating portion, the second lateral insulating portion and the inner insulating portion each extend along a second direction perpendicular to the first direction, and the resin spacer may have a first connecting portion that connects one end of each of the first lateral insulating portion, the second lateral insulating portion and the inner insulating portion in the second direction along the first direction, and a second connecting portion that connects the other end of each of the first lateral insulating portion, the second lateral insulating portion and the inner insulating portion in the second direction along the first direction.

[0032] In this configuration, the first gap is surrounded on all four sides by the first lateral insulating portion, one end of the inner insulating portion in the first direction, the first connection portion, and the second connection portion, while the second gap is surrounded on all four sides by the second lateral insulating portion, the other end of the inner insulating portion in the first direction, the first connection portion, and the second connection portion. With one end and the other end of the second conductor inserted into the first and second gaps, respectively, the resin spacer can be fixed to the bottom surface of the core, for example, thereby stably attaching the resin spacer to the core.

[0033] Preferably, the bottom surface of the resin spacer has a first recess located on one side in the second direction and a second recess located on the other side in the second direction, the first inner mounting portion is housed in the first recess and the second inner mounting portion is housed in the second recess. By housing the first inner mounting portion in the first recess and the second inner mounting portion in the second recess, it is possible to prevent the first inner mounting portion and the second inner mounting portion from being exposed to the outside, and good insulation can be achieved between the first inner mounting portion and the second inner mounting portion.

[0034] The resin spacer has a first arm portion rising from the first connection portion and a second arm portion rising from the second connection portion. The tip of the first arm portion has a first protrusion projecting inward in the first direction, and the tip of the second arm portion has a second protrusion projecting inward in the first direction. A first recess is formed on one side surface of the core in the first direction, and a second recess is formed on the other side surface of the core in the first direction. The first protrusion may engage with the first recess, and the second protrusion may engage with the second recess. By engaging the first protrusion with the first recess, the first arm portion can be fixed to one side surface of the core in the first direction. Similarly, by engaging the second protrusion with the second recess, the second arm portion can be fixed to the other side surface of the core in the first direction. As a result, the resin spacer can be fixed to the core via the first arm portion and the second arm portion.

[0035] Preferably, a third inclined portion is formed on the surface of the first lateral insulating portion, in a position facing the first outer mounting portion, and slopes downward toward the outside. A fourth inclined portion is formed on the surface of the second lateral insulating portion, in a position facing the second outer mounting portion, and slopes downward toward the outside. By forming the third inclined portion on the surface of the first lateral insulating portion, interference (contact) between the first lateral insulating portion and the first outer mounting portion can be prevented. Similarly, by forming the fourth inclined portion on the surface of the second lateral insulating portion, interference (contact) between the second lateral insulating portion and the second outer mounting portion can be prevented.

[0036] The first inner mounting portion and the first outer mounting portion may have a bent shape that is approximately L-shaped, the other of the first inner mounting portion and the first outer mounting portion may have a roughly straight shape, the second inner mounting portion and the second outer mounting portion may have a bent shape that is approximately L-shaped, and the other of the second inner mounting portion and the second outer mounting portion may have a roughly straight shape. For example, by making the shapes of the first inner mounting portion and the second inner mounting portion roughly straight, it is possible to make the shape of the first conductor a simple shape, and the processing of the first conductor becomes easier. Also, by making the shapes of the first outer mounting portion and the second outer mounting portion bent (approximately L-shaped), the second conductor can be connected to the land pattern of the mounting substrate in a stable state. [Brief explanation of the drawing]

[0037] [Figure 1A] Figure 1A is a perspective view of a coil device according to the first embodiment of the present invention. [Figure 1B] Figure 1B is a plan view of the coil device shown in Figure 1A. [Figure 1C] Figure 1C is a plan view of the coil device shown in Figure 1A with a tape component attached. [Figure 2] Figure 2 is an exploded perspective view of the coil device shown in Figure 1A. [Figure 3] Figure 3 is a cross-sectional view of the coil device shown in Figure 1A along the line III-III. [Figure 4A] Figure 4A is a perspective view of a coil device according to a second embodiment of the present invention. [Figure 4B] Figure 4B is a plan view of the coil device shown in Figure 4A. [Figure 5] Figure 5 is an exploded perspective view of the coil device shown in Figure 4A. [Figure 6] Figure 6 is a cross-sectional view of the coil device shown in Figure 4A along the line VI-VI. [Figure 7] Figure 7 is a perspective view of a coil device according to a third embodiment of the present invention. [Figure 8] Figure 8 is an exploded perspective view of the coil device shown in Figure 7. [Figure 9]Figure 9 is a cross-sectional view of the coil device shown in Figure 7 along line VII-VII. [Figure 10] Figure 10 is a perspective view of a coil device according to a fourth embodiment of the present invention. [Figure 11] Figure 11 is a perspective view of the resin spacer shown in Figure 10. [Figure 12] Figure 12 is a perspective view of the resin spacer shown in Figure 11 with the second conductor attached. [Figure 13] Figure 13 is a perspective view of a coil device according to a fifth embodiment of the present invention. [Figure 14A] Figure 14A is a perspective view of the resin spacer shown in Figure 13. [Figure 14B] Figure 14B is a perspective view of the bottom surface of the resin spacer shown in Figure 14A. [Figure 15] Figure 15 is a side view showing the inside of the coil device shown in Figure 13. [Figure 16A] Figure 16A is a perspective view illustrating the manufacturing method of the coil device shown in Figure 13, focusing on the method of attaching the resin spacer to the second conductor. [Figure 16B] Figure 16B is a perspective view showing the process that follows Figure 16A. [Figure 16C] Figure 16C is a perspective view showing the process that follows Figure 16B. [Figure 16D] Figure 16D is a perspective view showing the process that follows Figure 16C. [Figure 17A] Figure 17A is a perspective view of a coil device according to the sixth embodiment of the present invention. [Figure 17B] Figure 17B is a bottom view of the coil device shown in Figure 17A. [Figure 18] Figure 18 is a perspective view of the resin spacer shown in Figure 17A. [Figure 19] Figure 19 is a side view showing the inside of the coil device shown in Figure 17A. [Figure 20] Figure 20 is a perspective view of a coil device according to the seventh embodiment of the present invention. [Figure 21] Figure 21 is a perspective view of the second core shown in Figure 20. [Figure 22] Figure 22 is a perspective view of the resin spacer shown in Figure 20. [Figure 23] Figure 23 is a side view showing the internal state of the coil device shown in Figure 20. [Figure 24A] Figure 24A is a perspective view of a coil device according to the eighth embodiment of the present invention. [Figure 24B] Figure 24B is a bottom view of the coil device shown in Figure 24A. [Figure 25] Figure 25 is a perspective view of the resin spacer shown in Figure 24A. [Figure 26] Figure 26 is a side view showing the inside of the coil device shown in Figure 24A. [Figure 27] Figure 27 is a side view showing the internal state of the coil device according to the ninth embodiment of the present invention. [Figure 28] Figure 28 is a perspective view of the resin spacer shown in Figure 27. [Figure 29] Figure 29 is a side view showing the internal state of a coil device according to the 10th embodiment of the present invention. [Figure 30] Figure 30 is a bottom view of the coil device shown in Figure 29. [Figure 31] Figure 31 is a side view showing the internal state of a modified coil device shown in Figure 4A. [Figure 32] Figure 32 is a perspective view of the resin spacer shown in Figure 31. [Figure 33A] Figure 33A is a side view showing the inside of a modified coil device as shown in Figure 27. [Figure 33B] Figure 33B is a bottom view of the coil device shown in Figure 33A. [Modes for carrying out the invention]

[0038] The present invention will be described below based on the embodiments shown in the drawings.

[0039] First Embodiment As shown in Figure 1A, the coil device 10 according to the first embodiment of the present invention has a substantially rectangular parallelepiped shape and functions as a coupling coil used in power supply circuits and the like. The width of the coil device 10 in the X-axis direction is preferably 3.0 to 20.0 mm, the width in the Y-axis direction is preferably 3.0 to 20.0 mm, and the width in the Z-axis direction is preferably 3.0 to 20.0 mm.

[0040] As shown in Figure 2, the coil device 10 includes a first core 20a, a second core 20b, a first conductor 30, and a second conductor 40. Either the first conductor 30 or the second conductor 40 functions as a primary coil, and the other functions as a secondary coil. Details of the conductors 30 and 40 will be described later.

[0041] The first core 20a and the second core 20b each have the same shape and are formed in a so-called E-shape. The first core 20a and the second core 20b are arranged to face each other in the Y-axis direction and are joined together using an adhesive or the like. The first core 20a and the second core 20b are made of magnetic material and are manufactured by molding and sintering magnetic powder composed of a magnetic material with relatively high magnetic permeability, such as Ni-Zn ferrite, Mn-Zn ferrite, or metallic magnetic material.

[0042] The first core 20a has a first base portion 21a, a pair of first outer legs 22a, 22a, a first middle leg portion 23a positioned between each of the pair of first outer legs 22a, 22a, a first groove portion 24a, and first lateral groove portions 25a, 25a. The first base portion 21a has a substantially flat plate shape (substantially rectangular parallelepiped shape).

[0043] A pair of first outer legs 22a, 22a are formed at predetermined intervals in the X-axis direction on one and the other end of the first base portion 21a in the X-axis direction. Each of the first outer legs 22a, 22a protrudes by a predetermined length from one side of the first base portion 21a in the Y-axis direction toward the other side in the Y-axis direction. Each of the first outer legs 22a, 22a has an elongated shape in the Z-axis direction and extends from the upper end to the lower end of the first base portion 21a in the Z-axis direction.

[0044] The first intermediate leg portion 23a is formed approximately in the center of the first base portion 21a in the X-axis direction. The first intermediate leg portion 23a protrudes by a predetermined length from one side of the first base portion 21a in the Y-axis direction toward the other side in the Y-axis direction. The first intermediate leg portion 23a has an elongated shape in the Z-axis direction and extends from the upper part to the lower end of the first base portion 21a in the Z-axis direction. The protrusion width of the first intermediate leg portion 23a in the Y-axis direction is approximately equal to the protrusion width of the first outer leg portion 22a in the Y-axis direction. In the illustrated example, the X-axis width of the first intermediate leg portion 23a is larger than the X-axis width of the first outer leg portion 22a, approximately 2 to 3 times greater.

[0045] As shown in Figure 3, an insulating coating is applied to the surface of the first middle leg portion 23a facing the mounting surface 50 of the mounting substrate, forming an insulating coating layer 26. The insulating coating layer 26 is made of a resin-based material such as epoxy resin or urethane resin. The thickness of the insulating coating layer 26 is preferably 1 to 200 μm. The insulating coating layer 26 is also similarly formed on the bottom surface of the second middle leg portion 23b of the second core 20b.

[0046] As shown in Figure 2, the first groove 24a has a shape (approximately U-shaped) corresponding to the shape of the first conductor 30 and extends along the periphery of the first middle leg 23a. The first conductor 30 and the second conductor 40 can be placed overlapping inside the first groove 24a. The first groove 24a has a first lateral portion 241, a second lateral portion 242, and an upper portion 243.

[0047] The first lateral portion 241 and the second lateral portion 242 each extend substantially linearly along the Z-axis direction, extending from the upper end to the lower end in the Z-axis direction of the first base portion 21a. The first lateral portion 241 is formed between the first outer leg portion 22a and the first middle leg portion 23a located on one side in the X-axis direction, and the second lateral portion 242 is formed between the first outer leg portion 22a and the first middle leg portion 23a located on the other side in the X-axis direction. The X-axis width of each of the first lateral portion 241 and the second lateral portion 242 is greater than the sum of the respective thicknesses (plate thicknesses) of the conductors 30 and 40. As will be described later, the conductor sides 31 and 41 of the conductors 30 and 40 are arranged in the first lateral portion 241, and the conductor sides 32 and 42 of the conductors 30 and 40 are arranged in the second lateral portion 242.

[0048] The upper portion 243 is formed above the first base portion 21a and extends along the X-axis direction. The upper portion 243 connects the upper end of the first lateral portion 241 and the upper end of the second lateral portion 242. The width of the upper portion 243 in the Z-axis direction is greater than the sum of the thicknesses (plate thicknesses) of the conductors 30 and 40. As will be described later, the upper conductor portions 33 and 43 of the conductors 30 and 40 are arranged in the upper portion 243.

[0049] The pair of first lateral grooves 25a, 25a are formed below the first outer legs 22a, 22a, which are located on one and the other side in the X-axis direction, respectively, and extend along the X-axis direction toward one end and the other end of the first base portion 21a in the X-axis direction. The first lateral grooves 25a, 25a are connected to the lower ends of the lateral portions 241, 242, respectively, and the lateral portions 241, 242 and the first lateral grooves 25a, 25a form a substantially L-shaped groove. The Z-axis width of each of the first lateral grooves 25a, 25a is approximately the same as or greater than the thickness (plate thickness) of the first conductor 30. As will be described later, the mounting portions 34, 35 of the first conductor 30 are arranged in the first lateral grooves 25a, 25a, respectively.

[0050] The second core 20b includes a second base portion 21b, a pair of second outer legs 22b, 22b, a second middle leg portion 23b (Figure 1B) and a second groove portion 24b, and second lateral groove portions 25b, 25b, which are positioned between each of the pair of second outer legs 22b, 22b. The second outer legs 22b, 22b are positioned opposite the first outer legs 22a, 22a, and the second middle leg portion 23b is positioned opposite the first middle leg portion 23a. Since the shape of the second core 20b is the same as that of the first core 20a, a description of the shape of each of the above parts in the second core 20b will be omitted.

[0051] As shown in Figure 1B, the combination of the first core 20a and the second core 20b is made possible by joining one side of the first core 20a, which is located on the opposite side in the Y-axis direction from the first base portion 21a, and one side of the second core 20b, which is located on the opposite side in the Y-axis direction from the second base portion 21b, via an adhesive or the like (not shown). More specifically, the outer leg portions 22a, 22b of the cores 20a, 20b are joined to each other and / or the middle leg portions 23a, 23b are joined to each other.

[0052] When the first core 20a and the second core 20b are combined while facing each other in the Y-axis direction, gaps G1 and G2 with a predetermined width in the Y-axis direction are formed between the first core 20a and the second core 20b at the positions where the outer leg portions 22a and 22b are formed, and a gap G3 with a predetermined width in the Y-axis direction is formed at the positions where the middle leg portions 23a and 23b are formed.

[0053] Gap G1 has a predetermined length in the X-axis direction and is formed between the first outer leg portion 22a and the second outer leg portion 22b, which are located on one side in the X-axis direction. Gap G2 has a predetermined length in the X-axis direction and is formed between the first outer leg portion 22a and the second outer leg portion 22b, which are located on the other side in the X-axis direction. The lengths of gaps G1 and G2 in the X-axis direction are equal to the lengths of the outer leg portions 22a and 22b in the X-axis direction. In addition, gaps G1 and G2 also have a predetermined length in the Z-axis direction, and this length is equal to the lengths of the outer leg portions 22a and 22b in the Z-axis direction.

[0054] Gap G3 has a predetermined length in the X-axis direction and is formed between the first mid-leg portion 23a and the second mid-leg portion 23b. The length of gap G3 in the X-axis direction is equal to the length of the mid-leg portions 23a and 23b in the X-axis direction. In the illustrated example, the length of gap G3 in the X-axis direction is longer than the length of gaps G1 and G2 in the X-axis direction. Gap G3 also has a predetermined length in the Z-axis direction, and its length is equal to the length of the first mid-leg portions 23a and 23b in the Z-axis direction. Gaps G1 to G3 are formed in a straight line along the boundary between the first core 20a and the second core 20b.

[0055] The Y-axis width W1 of gap G1 is preferably 0.1 to 1.0 mm, and more preferably 0.1 to 0.5 mm. The same applies to the Y-axis widths of gaps G2 and G3. Note that the Y-axis widths of gaps G1 to G3 may be different.

[0056] As shown in Figure 2, the first conductor 30 is made of a conductive plate and has a curved shape (approximately U-shape). The first conductor 30 is arranged together with the second conductor 40 between the first core 20a and the second core 20b. Examples of materials that make up the first conductor 30 include good conductive metals such as copper and copper alloys, silver, and nickel, but it is not particularly limited as long as it is a conductive material. The first conductor 30 is formed, for example, by machining a metal plate, but the method of forming the first conductor 30 is not limited to this.

[0057] In the illustrated example, the first conductor 30 has an overall elongated shape, and the height of the first conductor 30 in the Z-axis direction is greater than its width in the X-axis direction. The cross-sectional area of ​​the first conductor 30 perpendicular to the direction of extension is greater than the cross-sectional area of ​​the second conductor 40 perpendicular to the direction of extension. Also, the thickness (plate thickness) of the first conductor 30 is greater than the thickness (plate thickness) of the second conductor 40. The thickness of the first conductor 30 is preferably 0.5 to 2.5 mm, and the thickness of the second conductor 40 is preferably 0.1 to 1 mm. The width of the first conductor 30 in the Y-axis direction may be approximately equal to the width of the second conductor 40 in the Y-axis direction.

[0058] A plating layer is formed on the entire surface of the first conductor 30. The plating layer consists of a single layer or multiple layers and is composed of metal plating layers such as Cu plating, Ni plating, Sn plating, Ni-Sn plating, Cu-Ni-Sn plating, Ni-Au plating, and Au plating. The plating layer is formed on the surface of the first conductor 30 by, for example, electroplating or electroplating. The thickness of the plating layer is not particularly limited, but is preferably 1 to 30 μm.

[0059] The first conductor 30 has a first conductor side portion 31, a second conductor side portion 32, a conductor upper portion 33, a first mounting portion (outer mounting portion) 34, and a second mounting portion (outer mounting portion) 35. The first conductor side portion 31 and the second conductor side portion 32 each extend along the Z-axis direction. Of the first conductor 30, the side where the first conductor side portion 31 is located functions as an input terminal (or output terminal), and the side where the second conductor side portion 32 is located functions as an output terminal (or input terminal). The conductor upper portion 33 extends along the X-axis direction and connects the first conductor side portion 31 and the second conductor side portion 32, respectively.

[0060] The first mounting portion 34 and the second mounting portion 35 are formed continuously (integrally) to one end and the other end of the first conductor 30, i.e., the lower ends of the first conductor side portion 31 and the second conductor side portion 32, respectively. The mounting portions 34 and 35 are bent in a direction substantially perpendicular to the conductor side portions 31 and 32 and extend outward in the X-axis direction. Through these mounting portions 34 and 35, the first conductor 30 can be connected to the mounting surface 50 of the mounting substrate (Figure 3). The first conductor 30 is joined to the mounting surface 50 by means of a joining member such as solder or conductive adhesive.

[0061] As shown in Figure 1A, the ends (end faces) of the mounting portions 34 and 35 are exposed to the outside from the sides in the X-axis direction of the first core 20a and the second core 20b. Also, as shown in Figure 3, the lower surfaces of the mounting portions 34 and 35 are exposed to the outside from below the first core 20a and the second core 20b. By exposing the mounting portions 34 and 35 to the outside in this way, it is possible to efficiently dissipate the heat generated around the mounting portions 34 and 35 to the outside of the cores 20a and 20b.

[0062] Near the boundary between the first conductor side portion 31 and the first mounting portion 34, a first outer bend portion 38 is formed that bends outward in the X-axis direction (opposite the side where the second conductor 40 is located), and near the boundary between the second conductor side portion 32 and the second mounting portion 35, a second outer bend portion 39 is formed that bends outward in the X-axis direction.

[0063] As shown in Figures 1B and 2, a first outer notch 36 and a second outer notch 37 are formed on the outer surface of the first conductor 30. The first outer notch 36 is formed on the surface of the first conductor side portion 31 and the first mounting portion 34, and extends along the longitudinal direction of the first conductor side portion 31 and the first mounting portion 34. The first outer notch 36 consists of a groove, and a tapered surface is formed on its inner side. The shape of the first outer notch 36 is equal to the shape formed by the first conductor side portion 31 and the first mounting portion 34, and is approximately L-shaped. The first outer notch 36 is formed approximately in the center of the first conductor side portion 31 and the first mounting portion 34 in the Y-axis direction, and extends continuously from the upper end of the first conductor side portion 31 to the end of the first mounting portion 34.

[0064] The second outer notch 37 is formed on the surface of the second conductor side portion 32 and the second mounting portion 35, and extends along the longitudinal direction of the second conductor side portion 32 and the second mounting portion 35. The second outer notch 37 consists of a groove, and a tapered surface is formed on its inner side. The shape of the second outer notch 37 is equal to the shape formed by the second conductor side portion 32 and the second mounting portion 35, and is approximately L-shaped. The second outer notch 37 is formed approximately in the center of the second conductor side portion 32 and the second mounting portion 35 in the Y-axis direction, and extends continuously from the upper end of the second conductor side portion 32 to the end of the second mounting portion 35.

[0065] The outer notches 36 and 37 are formed in the first conductor 30 at positions corresponding to (close to) the gaps G1 and G2. More specifically, the outer notches 36 and 37 are formed in the conductor side portions 31 and 32 so as to extend in the Z-axis direction along the outer leg edges 22a1 and 22b1 of the outer leg portions 22a and 22b adjacent to the first conductor 30. In addition, the outer notches 36 and 37 are formed in the mounting portions 34 and 35 so as to extend in the X-axis direction along the lower ends of the outer leg portions 22a and 22b.

[0066] The first outer notch 36 faces the other end of the gap G1 in the X-axis direction, and at the position corresponding to the gap G1, the distance between the surface of the first conductor 30 and the other end of the gap G1 in the X-axis direction is a distance corresponding to the depth D of the first outer notch 36. The second outer notch 37 faces the one end of the gap G2 in the X-axis direction, and at the position corresponding to the gap G2, the distance between the surface of the first conductor 30 and the one end of the gap G2 in the X-axis direction is a distance corresponding to the depth of the second outer notch 37.

[0067] The Y-axis width of the outer notches 36 and 37 is greater than the Y-axis width of the gaps G1 and G2. The ratio W2 / W1 of the Y-axis width W2 of the first outer notch 36 to the Y-axis width W1 of the gap G1 is preferably 0.5 to 10, more preferably 1 to 7, and particularly preferably 3 to 5. The same applies to the ratio of the Y-axis width of the second outer notch 37 to the Y-axis width of the gap G2.

[0068] The ratio W2 / W3 between the Y-axis width W2 of the first outer notch 36 and the Y-axis width W3 of the first conductor 30 is preferably 0.2 to 0.8, and more preferably 0.3 to 0.5. The same applies to the ratio between the Y-axis width of the second outer notch 37 and the Y-axis width of the first conductor 30.

[0069] The ratio D / T1 of the depth D of the first outer notch 36 to the thickness T1 of the first conductor 30 is preferably 0.1 to 0.5, and more preferably 0.2 to 0.4. The same applies to the ratio of the depth of the second outer notch 37 to the thickness T1 of the first conductor 30.

[0070] The relationship between the depth D of the first outer notch 36 and the Y-axis width W1 of the gap G1 is preferably D > W1, but is not limited to this. The ratio D / W1 of the depth D to the width W1 is preferably 0.5 to 5, and more preferably 1 to 3. The same applies to the relationship between the depth of the second outer notch 37 and the Y-axis width of the gap G2.

[0071] In this embodiment, by determining the values ​​of W2 / W1, W2 / W3, D / T1, or D / W1 as described above, or by setting D > W1, it is possible to prevent the leakage magnetic flux generated in gaps G1 and G2 from hitting the conductor sides 31 and 32 and the mounting parts 34 and 35 at the positions corresponding to gaps G1 and G2.

[0072] As shown in Figure 2, the second conductor 40 is made of a flat wire and has a curved shape (approximately U-shape). The second conductor 40 can be made of the same material as the first conductor 30. The second conductor 40 is placed together with the first conductor 30 inside the cores 20a, 20b (inside the grooves 24a, 24b). When the conductors 30, 40 are placed inside the grooves 24a, 24b, the second conductor 40 is placed inside the first conductor 30 at a predetermined distance, the middle legs 23a, 23b are placed inside the second conductor 40, and the outer legs 22a, 22b are placed outside the first conductor 30.

[0073] In the illustrated example, the second conductor 40 has an elongated shape, and its height in the Z-axis direction is greater than its length in the X-axis direction. The second conductor 40 is smaller than the first conductor 30 and, when arranged, is surrounded by the first conductor 30.

[0074] The second conductor 40 has a first conductor side portion 41, a second conductor side portion 42, a conductor upper portion 43, a first mounting portion (inner mounting portion) 44, and a second mounting portion (inner mounting portion) 45. The first conductor side portion 41 and the second conductor side portion 42 each extend along the Z-axis direction and are arranged opposite each other in the X-axis direction. Of the second conductor 40, the side where the first conductor side portion 41 is located functions as an input terminal (or output terminal), and the side where the second conductor side portion 42 is located functions as an output terminal (or input terminal).

[0075] The first conductor side portion 41 of the second conductor 40 extends substantially parallel to the first conductor side portion 31 of the first conductor 30, and the second conductor side portion 42 of the second conductor 40 extends substantially parallel to the second conductor side portion 32 of the first conductor 30.

[0076] The upper conductor portion 43 extends along the X-axis direction and connects the upper ends of the first conductor side portion 41 and the second conductor side portion 42, respectively. The upper conductor portion 43 of the second conductor 40 extends substantially parallel to the upper conductor portion 33 of the first conductor 30.

[0077] The first mounting portion 44 and the second mounting portion 45 are formed continuously (integrally) with one end and the other end of the second conductor 40, that is, the lower ends of the first conductor side portion 41 and the second conductor side portion 42, respectively.

[0078] The mounting portions 44 and 45 are bent in a direction substantially perpendicular to the conductor side portions 41 and 42 and extend inward in the X-axis direction. As shown in Figure 3, the mounting portions 44 and 45 extend along the bottom surfaces of the intermediate leg portions 23a and 23b, and a gap of a predetermined width is formed between the upper surfaces of the mounting portions 44 and 45 and the bottom surfaces of the intermediate leg portions 23a and 23b. As mentioned above, an insulating coating layer 26 is formed on the bottom surfaces of the intermediate leg portions 23a and 23b, so the intermediate leg portions 23a and 23b and the mounting portions 44 and 45 are well insulated from each other.

[0079] The extension direction of the first mounting portion 44 of the second conductor 40 is opposite to that of the first mounting portion 34 of the first conductor 30 with respect to the X-axis direction. Also, the extension direction of the second mounting portion 45 of the second conductor 40 is opposite to that of the second mounting portion 35 of the first conductor 30 with respect to the X-axis direction.

[0080] The second conductor 40 can be connected to the mounting surface 50 of the mounting board via these mounting parts 44 and 45. The second conductor 40 is joined to the mounting surface 50 via a joining material such as solder or conductive adhesive.

[0081] The lower surfaces of the mounting parts 44 and 45 are exposed to the outside from below the first core 20a and the second core 20b. By exposing the mounting parts 44 and 45 to the outside in this way, it is possible to efficiently dissipate the heat generated around the mounting parts 44 and 45 to the outside of the cores 20a and 20b.

[0082] The mounting sections 44 and 45 have mounting facing surfaces 440 and 450 that can face the mounting surface 50 of the mounting substrate. The mounting facing surfaces 440 and 450 are the magnetic surfaces of the mounting surface 50. Details of the mounting facing surfaces 440 and 450 will be described later.

[0083] An insulating layer 70 is formed between the first conductor 30 and the second conductor 40. The insulating layer 70 is interposed between the first conductor 30 and the second conductor 40 and plays a role in providing good insulation between the first conductor 30 and the second conductor 40. In this embodiment, the insulating layer 70 is composed of an insulating coating formed on the surface of the second conductor 40 and is integrally formed with respect to the second conductor 40. In the illustrated example, the surface (outer surface) of the insulating layer 70 is not in contact with the inner surface of the first conductor 30, and a gap is formed between the outer surface of the insulating layer 70 and the inner surface of the first conductor 30.

[0084] Various forms of the insulating layer 70 are conceivable. For example, the insulating layer 70 may be composed of a fused layer formed by fusing an insulating coating formed on the surface of the second conductor 40. In this case, the inner surface of the first conductor 30 and the outer surface of the second conductor 40 are connected via the fused layer (insulating layer 70), making it possible to completely fill the gap between the first conductor 30 and the second conductor 40 with the insulating layer 70, thereby ensuring sufficient insulation between the first conductor 30 and the second conductor 40. Furthermore, connecting the first conductor 30 and the second conductor 40 via the insulating layer 70 enhances the magnetic coupling between the first conductor 30 and the second conductor 40.

[0085] The fusion layer can be formed by heating the insulating coating formed on the surface of the second conductor 40. The fusion layer may be composed separately from the insulating coating formed on the surface of the second conductor 40; for example, the insulating coating and the fusion layer may be formed as two layers on the surface of the second conductor 40.

[0086] Furthermore, for example, the insulating layer 70 may be made of a resin body (such as a resin spacer) formed separately from the second conductor 40. In this case, by making the shape of the resin body a bent shape corresponding to the shape of the gap between the first conductor 30 and the second conductor 40 (approximately U-shaped), it becomes possible to form the insulating layer 70 so as to conform to the outer surface of the second conductor 40 and the inner surface of the first conductor 30.

[0087] As shown in FIG. 2, the insulating layer 70 covers the entire surface of the second conductor 40 (excluding the bondable surfaces 441 and 451 on the mounting opposing surfaces 440 and 450 described later). The range in which the insulating layer 70 is formed is not limited to the illustrated range, and the insulating layer 70 only needs to be formed at least at a position where the inner surface of the first conductor 30 and the outer surface of the second conductor 40 face each other.

[0088] As shown in FIG. 3, when the distance between the inner surface of the first conductor 30 and the outer surface of the second conductor 40 is L, the thickness T3 of the insulating layer 70 is appropriately determined within the range of 0<T3≤L. For example, when the insulating layer 70 is formed of an insulating coating formed on the surface of the second conductor 40, the thickness thereof is preferably 1 to 200 μm, more preferably 1 to 100 μm. Further, for example, when the insulating layer 70 is formed of a resin body formed separately from the above-described second conductor 40, the thickness of the insulating layer 70 may be larger than the above thickness.

[0089] The material constituting the insulating layer 70 is not particularly limited, and examples thereof include polyester, polyester imide, polyamide, polyamide imide, polyurethane, epoxy, and epoxy-modified acrylic resin.

[0090] The insulating layer 70 entirely covers the outer surface, the inner surface, and the side surfaces orthogonal to these on the conductor side portions 41, 42 and the conductor upper portion 43. By forming the insulating layer 70 on the inner surfaces of the conductor side portions 41, 42 and the conductor upper portion 43, it is possible to satisfactorily insulate the second conductor 40 from the middle leg portions 23a, 23b of the cores 20a, 20b.

[0091] Between the second conductor 40 and the middle leg portions 23a, 23b of the cores 20a, 20b, the insulating layer 70 is integrally formed with the second conductor 40, and extends along the inner surface of the second conductor 40 (the conductor side portions 41, 42 and the conductor upper portion 43). The configuration of the insulating layer 70 formed between the second conductor 40 and the middle leg portions 23a, 23b of the cores 20a, 20b is the same as the configuration of the insulating layer 70 formed between the first conductor 30 and the second conductor 40 described above.

[0092] Furthermore, the insulating layer 70 completely covers the inner surface, sides, and end faces (each end face of the second conductor 40) of the mounting portions 44 and 45, while only partially covering the outer surfaces (mounting opposing surfaces 440 and 450).

[0093] More specifically, the mounting surfaces 440 and 450 have bondable surfaces 441 and 451 on which the insulating layer 70 is not formed, and non-bondable surfaces 442 and 452 on which the insulating layer 70 is formed. Since the insulating layer 70 is not formed on the bondable surfaces 441 and 451, the bondable surfaces 441 and 451 are made conductive, making it possible to connect the bondable surfaces 441 and 451 to the mounting surface 50 of the mounting substrate via a bonding member such as solder.

[0094] The connectable surfaces 441 and 451 are formed from approximately the center of the mounting portions 44 and 45 in the X-axis direction to the tip portions of the mounting portions 44 and 45 (each end of the second conductor 40). The non-connectable surfaces 442 and 452 are formed from the base portions of the mounting portions 44 and 45 (the connection portion with the conductor side portions 41 and 42) to approximately the center of the mounting portions 44 and 45 in the X-axis direction. Therefore, in this embodiment, the non-connectable surfaces 442 and 452 are formed closer to the first conductor 30 than the connectable surfaces 441 and 451.

[0095] Thus, in this embodiment, the insulating layer 70 is formed over the entire length of the inner surface of the second conductor 40, whereas on the outer surface of the second conductor 40, there are regions where the insulating layer 70 is not formed only at both ends in the length direction.

[0096] As shown in Figure 2, a first inner bend 46 is formed near the boundary between the first conductor side portion 41 and the first mounting portion 44, bending inward in the X-axis direction (opposite the side where the first conductor 30 is located), and a second inner bend 47 is formed near the boundary between the second conductor side portion 42 and the second mounting portion 45, bending inward in the X-axis direction. The radius of curvature of the outer surfaces of the inner bends 46 and 47 of the second conductor 40 is smaller than the radius of curvature of the inner surfaces of the outer bends 38 and 39 of the first conductor 30.

[0097] In the manufacture of the coil device 10, the first core 20a, the second core 20b, the first conductor 30, and the second conductor 40 shown in Figure 2 are prepared. For the second conductor 40, for example, a flat rectangular wire with an insulating coating (insulating layer 70) formed on its surface is machined into the shape shown in Figure 2. Such a flat rectangular wire with an insulating coating can be formed, for example, by immersing a metal plate in a resin liquid.

[0098] On the mounting-facing surfaces 440 and 450 of the second conductor 40, joinable surfaces 441 and 451 are formed where the insulating layer 70 is not formed. The joinable surfaces 441 and 451 are formed by applying laser irradiation or the like to the flat wire at the position where the joinable surfaces 441 and 451 are to be formed, thereby peeling off the insulating layer 70 from the mounting-facing surfaces 440 and 450. The peeling off of the insulating layer 70 may also be done by scraping the surface of the flat wire with a file or the like. Preferably, solder is applied to the peeled portion of the insulating layer 70 by solder dipping or the like. This makes it possible to improve the solder wettability of the joinable surfaces 441 and 451. The formation of the joinable surfaces 441 and 451 may be done before processing the flat wire into the shape shown in Figure 2, or it may be done after processing.

[0099] Next, the first conductor 30 and the second conductor 40 are placed overlapping inside the first groove 24a (second groove 24b) of the first core 20a (second core 20b). More specifically, the second conductor 40 is placed so as to surround the first middle leg portion 23a (second middle leg portion 23b), and then the first conductor 30 is placed at a predetermined interval so as to surround the second conductor 40. At this time, the first conductor 30 and / or the second conductor 40 may be fixed to the first core 20a with an adhesive or the like.

[0100] Alternatively, the inner surface of the first conductor 30 and the outer surface of the second conductor 40 may be joined in advance via an insulating layer 70 (fusion layer), and then placed inside the first groove 24a (second groove 24b) of the first core 20a (second core 20b). By integrating the first conductor 30 and the second conductor 40 via the insulating layer 70 in this way, it becomes easier to place them inside the first groove 24a (second groove 24b) of the first core 20a (second core 20b).

[0101] Next, the second core 20b (first core 20a) is combined with the first core 20a (second core 20b) so that the first conductor 30 and the second conductor 40 are housed inside the second groove 24b (first groove 24a).

[0102] At this time, as shown in Figure 1B, the first core 20a and the second core 20b are combined with a predetermined distance in the Y-axis direction such that a gap G1 is formed between the first outer leg portion 22a and the second outer leg portion 22b located on one side in the X-axis direction, a gap G2 is formed between the first outer leg portion 22a and the second outer leg portion 22b located on the other side in the X-axis direction, and a gap G3 is formed between the first middle leg portion 23a and the second middle leg portion 23b.

[0103] As a result, the outer notches 36 and 37 face the gaps G1 and G2, and the outer bent portions 38 and 39 face the gap G3. Subsequently, the coil device 10 shown in Figure 1A is obtained by joining the first core 20a and the second core 20b with an adhesive or the like.

[0104] Subsequently, as shown in Figure 1C, tape members 60 may be attached to the upper surfaces of cores 20a and 20b, and characters such as a manufacturing number (identifier / in the illustrated example, the characters "R15") may be printed on the surface of the tape member 60. Alternatively, tape members 60 with characters such as a manufacturing number (identifier) ​​pre-printed on them may be attached to the upper surfaces of cores 20a and 20b. The tape member 60 is, for example, Kapton tape and is attached so as to span across cores 20a and 20b. The characters on the tape member 60 are printed by laser irradiation or the like. Conventionally, characters were engraved on the upper surface of the core by laser irradiation, and then tape members were attached over the characters, but in this case, there was a problem that the characters engraved on the upper surface of the core became difficult to see. As in this embodiment, by printing characters on a tape member attached to the upper surface of the core, or by attaching a tape member with characters printed on it to the upper surface of the core, the characters can be clearly seen, and the above-mentioned problem can be effectively prevented.

[0105] As shown in Figures 2 and 3 above, the coil device 10 in this embodiment has a first conductor 30 and a second conductor 40 which is arranged inside the first conductor 30 and at least a portion of it (conductor side portions 41, 42 and conductor upper portion 43) extends along the first conductor 30 (conductor side portions 31, 32 and conductor upper portion 33), and an insulating layer 70 is formed between at least the first conductor 30 and the second conductor 40. In this case, the first conductor 30 and the second conductor 40 are arranged overlapping (double) with a predetermined gap between them, but under such arrangement, magnetic flux can be efficiently transmitted between the first conductor 30 and the second conductor 40, and the magnetic coupling between the first conductor 30 and the second conductor 40 can be made sufficiently large. Furthermore, since the first conductor 30 and the second conductor 40 are sufficiently insulated from each other via the insulating layer 70 interposed between them, it is possible to prevent short-circuit failures from occurring between the first conductor 30 and the second conductor 40, and a highly reliable coil device 10 can be realized.

[0106] Furthermore, in this embodiment, the second conductor 40 is made of a flat rectangular wire, and the insulating layer 70 is made of an insulating coating formed on the surface of the second conductor 40. By using a flat rectangular wire with an insulating coating as the second conductor 40 in this way, it becomes possible to interpose the insulating layer 70 between the first conductor 30 and the second conductor 40 simply by placing the second conductor 40 on top of the first conductor 30, and the above-mentioned effects can be easily obtained.

[0107] Furthermore, in this embodiment, the insulating layer 70 is formed between the middle leg portions 23a and 23b of the cores 20a and 20b and the second conductor 40. Therefore, the middle leg portions 23a and 23b and the second conductor 40 are sufficiently insulated from each other via the insulating layer 70 interposed between them, making it possible to prevent short-circuit failures from occurring between the middle leg portions 23a and 23b and the second conductor 40, thereby realizing a highly reliable coil device 10.

[0108] Furthermore, the first conductor 30 in this embodiment is made of a conductor plate with a plating layer formed on its surface. As a result, bonding materials such as solder and conductive adhesive can easily adhere to the surface of the first conductor 30, and the first conductor 30 can be firmly connected to the mounting surface 50 of the mounting substrate. In particular, when solder is used as the bonding material, solder fillets can be easily formed on the side surface of the first conductor 30, thereby making the connection between the first conductor 30 and the mounting surface 50 of the mounting substrate firm.

[0109] Furthermore, in this embodiment, the mounting opposing surfaces 440 and 450 have joinable surfaces 441 and 451 on which the insulating layer 70 is not formed, and non-joinable surfaces 442 and 452 on which the insulating layer 70 is formed, and the non-joinable surfaces 442 and 452 are formed closer to the first conductor 30 than the joinable surfaces 441 and 451. In this case, the joining member described above is more likely to adhere to the joinable surfaces 441 and 451, while it is less likely to adhere to the non-joinable surfaces 442 and 452. Therefore, the non-joinable surfaces 442 and 452 can prevent the joining member attached to the joinable surfaces 441 and 451 from protruding toward the first conductor 30, and this effectively prevents short-circuit defects caused by solder balls or the like from occurring between the first conductor 30 and the second conductor 40.

[0110] Furthermore, in this embodiment, the radius of curvature of the inner surfaces of the outer bent portions 38 and 39 is greater than the radius of curvature of the outer surfaces of the inner bent portions 46 and 47 of the second conductor 40. In this case, the bending angle of the inner surfaces of the outer bent portions 38 and 39 is smaller than the bending angle of the outer surfaces of the inner bent portions 46 and 47. Therefore, the outer surfaces of the inner bent portions 46 and 47 bend sharply near the mounting surface 50 of the mounting substrate, while the inner surfaces of the outer bent portions 38 and 39 bend gently from a position away from the mounting surface 50 of the mounting substrate. Consequently, a relatively large space is formed between the inner surfaces of the outer bent portions 38 and 39 and the outer surfaces of the inner bent portions 46 and 47, effectively preventing short-circuit failures from occurring between the first conductor 30 and the second conductor 40 around the mounting surface 50. Furthermore, even if the land pattern of the mounting substrate to which the mounting portions 44 and 45 of the second conductor 40 are connected is wide in the X-axis direction, contact between the mounting portions 34 and 35 of the first conductor 30 and the land pattern can be prevented.

[0111] Furthermore, in this embodiment, the cross-sectional area of ​​the first conductor 30 perpendicular to its extension direction is larger than the cross-sectional area of ​​the second conductor 40 perpendicular to its extension direction. Therefore, the DC resistance of the first conductor 30 can be made smaller than that of the second conductor 40.

[0112] Furthermore, in this embodiment, an insulating coating layer 26 is formed on the bottom surface of the middle leg portions 23a and 23b of the cores 20a and 20b. Therefore, sufficient insulation can be ensured between the bottom surface of the middle leg portions 23a and 23b and the second conductor 40 via the insulating coating layer 26.

[0113] Second Embodiment The coil device 110 according to the second embodiment of the present invention differs only in the following points, and its other configurations are the same as those of the first embodiment described above, and it provides the same effects. In the drawings, common reference numerals are used for members common to the first embodiment, and descriptions of overlapping parts are omitted.

[0114] As shown in Figures 4A and 5, the coil device 110 includes a first core 120a, a second core 120b, a first conductor 130, and a second conductor 40. The first core 120a differs from the first core 20a in the first embodiment in that it has a pair of first outer legs 122a, 122a, but does not have the lateral grooves 25a, 25b shown in Figure 2. The length of the first outer legs 122a, 122a in the Z-axis direction is longer by the amount by which the lateral grooves 25a, 25b are absent.

[0115] The second core 120b differs from the second core 20b in the first embodiment in that it has a flat plate shape. When the first core 120a and the second core 120b are combined, a so-called EI-type core is formed.

[0116] As shown in Figure 4B, a gap G4 is formed between the first outer leg 122a and the second core 120b located on one side in the X-axis direction, and a gap G5 is formed between the first outer leg 122a and the second core 120b located on the other side in the X-axis direction. Each of the gaps G4 and G5 extends along the first outer leg 122a in the Z-axis direction and the X-axis direction, respectively.

[0117] Furthermore, a gap G6 is formed between the first mid-leg portion 23a and the second core 120b. The gap G6 extends along the first mid-leg portion 23a in the Z-axis and X-axis directions.

[0118] As shown in Figure 5, the first conductor 130 has a first conductor side portion 131, a second conductor side portion 132, a conductor upper portion 133, a first mounting portion 134, and a second mounting portion 135. Step portions 131a and 132a are formed at the upper ends of the conductor side portions 131 and 132, and step portions 131b and 132b are formed at the lower ends of the conductor side portions 131 and 132. The step portions 131a and 132a are formed on both sides of the conductor side portions 131 and 132 (planes parallel to the XZ plane), and the step portions 131b and 132b are formed on the inner surfaces of the conductor side portions 131 and 132 (planes parallel to the YZ plane).

[0119] The width of the upper part 133 of the conductor in the Y-axis direction is smaller than the width of the upper part 33 of the first conductor 30 shown in Figure 2, by the amount by which the stepped portions 131a and 132a are formed at the upper ends of the conductor sides 131 and 132.

[0120] The first mounting section 134 has a first mounting bend 340, a first mounting connection 341, and a first mounting body 342. The second mounting section 135 has a second mounting bend 350, a second mounting connection 351, and a second mounting body 352. The mounting bends 340 and 350 are formed continuously (integrally) with the lower ends of the conductor sides 131 and 132. The mounting bends 340 and 350 are bent in a direction substantially perpendicular to the conductor sides 131 and 132 and extend in the Y-axis direction toward the side where the first core 120a is located.

[0121] The mounting connection portions 341 and 351 are formed continuously (integrally) with the ends of the mounting bend portions 340 and 350, and connect the mounting bend portions 340 and 350 to the mounting body portions 342 and 352. The mounting connection portions 341 and 351 extend outward in the X-axis direction.

[0122] The mounting body portions 342 and 352 are formed continuously (integrally) with the ends of the mounting connection portions 341 and 351, and extend in the Y-axis direction toward the side where the second core 120b is located. The first conductor 130 can be connected to the mounting surface (not shown) of the mounting substrate via the mounting body portions 342 and 352. The mounting body portions 342 and 352 are joined to the mounting surface by a joining material such as solder or conductive adhesive.

[0123] A first outer notch 136 and a second outer notch 137 are formed on the outer surface of the first conductor 130. The outer notches 136 and 137 extend continuously along the longitudinal direction of the conductor side portions 131 and 132 and the mounting bend portions 340 and 350. Parts of the outer notches 136 and 137 (upper ends) are also formed at each end of the conductor upper portion 133 in the X-axis direction.

[0124] As shown in Figures 4B and 5, the first outer notch 136 consists of a chamfered portion obtained by chamfering one corner in the Y-axis direction of each of the conductor upper part 133, the first conductor side part 131, and the first mounting bend part 340 (the corner between the outer surface and the side surface of each of the conductor upper part 133, the first conductor side part 131, and the first mounting bend part 340). The second outer notch 137 consists of a chamfered portion obtained by chamfering one corner in the Y-axis direction of each of the conductor upper part 133, the second conductor side part 132, and the second mounting bend part 350 (the corner between the outer surface and the side surface of each of the conductor upper part 133, the second conductor side part 132, and the second mounting bend part 350). At the positions where the outer notches 136 and 137 are formed, the conductor upper part 133, the conductor side parts 131 and 132, and the mounting bend parts 340 and 350 are each provided with an inclined surface (C-surface).

[0125] The outer notches 136 and 137 are formed in the conductor 130 at positions corresponding to (or close to) the gaps G4 and G5. More specifically, the outer notches 136 and 137 are formed in the conductor 130 so as to extend in the Z-axis direction along the outer leg edges 122a1 and 122a1 of the outer leg portions 122a, 122a1 adjacent to the conductor 130.

[0126] The first outer notch 136 faces obliquely to the other end of the gap G4 in the X-axis direction, and at the position corresponding to the gap G4, the distance between the surface of the conductor 130 and the other end of the gap G4 in the Y-axis direction is a distance corresponding to the Y-axis width W5 or X-axis width W6 of the first outer notch 136. The second outer notch 137 faces obliquely to one end of the gap G5 in the X-axis direction, and at the position corresponding to the gap G5, the distance between the surface of the conductor 130 and one end of the gap G5 in the Y-axis direction is a distance corresponding to the Y-axis width or X-axis width of the second outer notch 137.

[0127] The Y-axis width of the outer notches 136 and 137 is preferably greater than the Y-axis width of the gaps G4 and G5, but is not limited to this. The ratio W5 / W4 of the Y-axis width W5 of the first outer notch 136 to the Y-axis width W4 of the gap G4 is preferably 0.5 to 6, more preferably 1 to 5, and particularly preferably 2 to 4. The same applies to the ratio of the Y-axis width of the second outer notch 137 to the Z-axis width of the gap G5.

[0128] The X-axis width of the outer notches 136 and 137 is preferably greater than the Y-axis width of the gaps G4 and G5, but is not limited to this. The ratio W6 / W4 of the X-axis width W6 of the first outer notch 136 to the Y-axis width W4 of the gap G4 is preferably 0.5 to 6, more preferably 1 to 5, and particularly preferably 2 to 4. The same applies to the ratio of the X-axis width of the second outer notch 137 to the Y-axis width of the gap G5.

[0129] The ratio W5 / W7 between the Y-axis width W5 of the first outer notch 136 and the Y-axis width W7 of the conductor 130 is preferably 0.1 to 0.5, and more preferably 0.2 to 0.3. The same applies to the ratio between the Y-axis width W7 of the second outer notch 137 and the Y-axis width W7 of the conductor 130.

[0130] The ratio W6 / T2 between the width W6 in the X-axis direction of the first outer notch 136 and the thickness T2 of the conductor 130 (Figure 5) is preferably 0.1 to 0.9, and more preferably 0.3 to 0.7. The same applies to the ratio between the width W6 in the X-axis direction of the second outer notch 137 and the thickness T2 of the conductor 130.

[0131] In this embodiment, by determining the values ​​of W5 / W4, W6 / W4, W5 / W7, or W6 / T2 as described above, or by setting W5>W4 or W6>W4, it is possible to prevent the leakage magnetic flux generated in gaps G4 and G5 from hitting the upper part 133 of the conductor at the positions corresponding to gaps G4 and G5.

[0132] In this embodiment, the same effects as in the first embodiment can be obtained. Furthermore, in this embodiment, the size of the mounting parts 134 and 135 (especially the size of the mounting body parts 342 and 352) is smaller than the size of the mounting parts 34 and 35 in the first embodiment, so the coil device 110 can be miniaturized.

[0133] Furthermore, in this embodiment, as shown in Figure 6, stepped portions 131b and 132b are formed at the lower ends of the conductor side portions 131 and 132. As a result, a space is formed between the mounting portions 134 and 135 (mounting bend portions 340 and 350) of the first conductor 130 and the mounting portions 44 and 45 of the second conductor 40 by the width of the stepped portions 131b and 132b. This effectively prevents short-circuit failures from occurring between the first conductor 130 and the second conductor 40 around the mounting surface (not shown) of the mounting substrate.

[0134] Third Embodiment The coil device 210 according to the third embodiment of the present invention differs only in the following points, and its other configurations are the same as those of the first embodiment described above, and it provides the same effects. In the drawings, common reference numerals are used for members common to the first and second embodiments, and descriptions of overlapping parts are omitted.

[0135] As shown in Figure 7, the coil device 210 has a first core 120a, a second core 220b, a first conductor 30, and a second conductor 240. The second core 220b has the same shape as the first core 120a.

[0136] As shown in Figure 8, the second conductor 240 has a first mounting portion 244 and a second mounting portion 245. The ends of the mounting portions 244 and 245 (each end of the second conductor 240) are raised upwards. As shown in Figure 9, the end faces of the mounting portions 244 and 245 are positioned at a predetermined distance in the Z-axis direction from the bottom surfaces of the middle leg portions 23a and 23b of the cores 120a and 220b.

[0137] The first mounting portion 244 has a first mounting opposing surface 440', and the second mounting portion 245 has a second mounting opposing surface 450'. The first mounting opposing surface 440' has a first rising portion 443 that rises up relative to the mounting surface of the mounting substrate (not shown), and the second mounting opposing surface 450' has a second rising portion 453 that rises up relative to the mounting surface of the mounting substrate. The rising portions 443 and 453 are raised relative to the mounting surface of the mounting substrate at intermediate positions in the X-axis direction of the bondable surfaces 441' and 451'.

[0138] In this embodiment, the same effects as in the first embodiment can be obtained. In addition, in this embodiment, the mounting opposing surfaces 440', 450' have rising portions 443, 453. Therefore, it is possible to attach the bonding member not only to the surface facing the mounting surface of the mounting substrate, but also to the rising portions 443, 453, with respect to the mounting portions 244, 245. As a result, when solder is used as the bonding member, it is possible to form solder fillets on the rising portions 443, 453, and firmly connect the second conductor 240 to the mounting surface of the mounting substrate. Furthermore, it is possible to prevent the occurrence of short-circuit defects between the mounting portions 244, 245 caused by, for example, the formation of solder balls on the mounting portions 244, 245 of the second conductor.

[0139] Furthermore, in this embodiment, the bottom surfaces of the cores 120a and 220b are positioned at a distance from the mounting surface (not shown) of the mounting substrate. More specifically, as shown in Figure 7, the bottom surfaces of the cores 120a and 220b are positioned at a distance equal to or greater than the thickness of the first conductor 30 from the bottom surfaces of the mounting portions 34 and 35 connected to the mounting surface of the mounting substrate. Therefore, in this embodiment, sufficient insulation between the bottom surfaces of the cores 120a and 220b and the mounting surface of the mounting substrate can be ensured, and in particular when the cores 120a and 220b are made of a metallic magnetic material or the like, short-circuit failures between the bottom surfaces of the cores 120a and 220b and the mounting surface can be effectively prevented.

[0140] Fourth Embodiment The coil device 310 according to the fourth embodiment of the present invention differs only in the following points, and its other configurations are the same as those of the first embodiment described above, and it provides the same effects. In the drawings, common reference numerals are used for members common to the first to third embodiments, and descriptions of overlapping parts are omitted.

[0141] As shown in Figure 10, the coil device 310 includes a first core 120a, a second core 220b, a first conductor 30, a second conductor 40, and a resin spacer 80. The resin spacer 80 is positioned below the cores 120a and 220b and is fixed so as to straddle the first conductor 30 and the second conductor 40. The resin spacer 80 primarily serves to provide good insulation between the first conductor 30 and the second conductor 40.

[0142] As shown in Figures 11 and 12, the resin spacer 80 has a base portion 81, a first lateral insulating portion 82a, a second lateral insulating portion 82b, a first groove portion 83a, a second groove portion 83b, and a protruding portion 84.

[0143] The base portion 81 has a flat plate shape and is positioned above the first mounting portion 44 and the second mounting portion 45, respectively, and is fixed so as to be sandwiched between the lower ends of the first conductor side portion 41 and the second conductor side portion 42 of the second conductor 40.

[0144] A projection 84 extending in the Y-axis direction is formed approximately in the center of the base portion 81 in the X-axis direction. The projection 84 is positioned in the gap formed between the mounting portions 44 and 45 of the second conductor 40. The downward projection width of the projection 84 is approximately equal to the thickness (plate thickness) of the mounting portions 44 and 45, and the projection 84 is used to separate the first mounting portion 44 and the second mounting portion 45 in the X-axis direction. The projection 84 is intended to prevent the phenomenon (solder bridging) in which the first mounting portion 44 and the second mounting portion 45 are connected via a soldering member (solder ball) when the second conductor 40 is connected to the mounting surface (not shown) of the mounting board via a soldering member such as solder.

[0145] The first groove 83a is formed between the base portion 81 and the first lateral insulating portion 82a, and the second groove 83b is formed between the base portion 81 and the second lateral insulating portion 82b. The grooves 83a and 83b extend along the Y-axis direction, with one end of each groove 83a and 83b closed in the Y-axis direction, while the other end in the Y-axis direction is open. Through the other end of each groove 83a and 83b in the Y-axis direction, the lower ends of the conductor sides 41 and 42 of the second conductor 40 can be inserted into the grooves 83a and 83b.

[0146] The first lateral insulating portion 82a is positioned on one side of the base portion 81 in the X-axis direction, straddling the first groove portion 83a. The second lateral insulating portion 82b is positioned on the other side of the base portion 81 in the X-axis direction, straddling the second groove portion 83b. The lateral insulating portions 82a and 82b extend in the Y-axis direction and have the same Y-axis width as the base portion 81. A first inclined portion 85a is formed on the upper surface of the first lateral insulating portion 82a, and a second inclined portion 85b is formed on the upper surface of the second lateral insulating portion 82b.

[0147] The first lateral insulating portion 82a is positioned between the first mounting portion 34 (Figure 10) of the first conductor 30 and the first conductor side portion 41 of the second conductor 40. At this time, the first inclined portion 85a is positioned to conform to the shape of the first outer bend portion 38 of the first conductor 30.

[0148] The second lateral insulating portion 82b is positioned between the second mounting portion 35 (Figure 10) of the first conductor 30 and the second conductor side portion 42 of the second conductor 40. At this time, the second inclined portion 85b is positioned to conform to the shape of the second outer bent portion 39 of the first conductor 30.

[0149] The lateral insulating portions 82a and 82b are intended to prevent the phenomenon (solder bridging) in which the first mounting portion 34 (second mounting portion 35) of the first conductor 30 and the first mounting portion 44 (second mounting portion 45) of the second conductor 40 are connected via a bonding member such as solder when the conductors 30 and 40 are connected to the mounting surface (not shown) of the mounting board.

[0150] In this embodiment, the same effects as in the first embodiment can be obtained. In addition, in this embodiment, the mounting portions 34, 35 of the first conductor 30 and the mounting portions 44, 45 of the second conductor 40 are insulated via the resin spacer 80. Therefore, it is possible to effectively prevent short-circuit failures from occurring between the first mounting portions 34, 35 and the second mounting portions 44, 45.

[0151] Fifth Embodiment The coil device 410 according to the fifth embodiment of the present invention differs only in the following points, and its other configurations are the same as those of the fourth embodiment described above, and it provides similar effects. In the drawings, common reference numerals are used for members common to the fourth embodiment, and descriptions of overlapping parts are omitted.

[0152] As shown in Figure 13, the coil device 410 includes a first core 420a, a second core 420b, and a resin spacer 90. The second core 420b has a bottom recess 27. The bottom recess 27 is formed on the bottom surface of the second base portion 21b of the second core 420b and is recessed upward in the Z-axis direction from the bottom surface of the second base portion 21b. The bottom recess 27 has a predetermined length along the X-axis direction and is formed continuously from one side to the other in the X-axis direction of the second base portion 21b. Although not shown in detail, a bottom recess 27 is similarly formed on the bottom surface of the first base portion 21a of the first core 420a. The bottom recess 27 is provided to prevent the resin spacer 90 from interfering (contacting) with the bottom surfaces of the cores 420a and 420b when the resin spacer 90 is placed on each of their bottom surfaces. Therefore, it is preferable that the depth of the bottom recess 27 in the Z-axis direction is equal to or greater than the thickness of the resin spacer 90 in the Z-axis direction.

[0153] A bottom protrusion 27a is formed at one end of the recess 27 in the X-axis direction, and a bottom protrusion 27b is formed at the other end of the recess 27 in the X-axis direction. The bottom surfaces of the bottom protrusions 27a and 27b are located above the positions of the bottom surfaces of the first mounting portion 34 and the second mounting portion 35 of the first conductor 30, and above the positions of the bottom surfaces of the first mounting portion 44 and the second mounting portion 45 of the second conductor 40. Note that the bottom protrusions 27a and 27b may be omitted (see Figure 10).

[0154] As shown in Figure 14A, the resin spacer 90 has an inner insulating portion 91, a first lateral insulating portion 92a, a second lateral insulating portion 92b, a first groove portion 93a, a second groove portion 93b, a protruding portion 94, and a connecting portion 96. The resin spacer 90 is attached to the positions of the first mounting portion 44 and the second mounting portion 45 of the second conductor 40.

[0155] The inner insulating portion 91 has a substantially flat shape and extends along the Y-axis direction. As shown in Figure 15, the inner insulating portion 91 is positioned above the first mounting portion 44 and the second mounting portion 45 of the second conductor 40, and is fixed so as to be sandwiched between the lower end of the first conductor side portion 41 and the lower end of the second conductor side portion 42 of the second conductor 40. More specifically, the inner insulating portion 91 is positioned between one end and the other end of the second conductor 40, between the bottom surfaces of the cores 420a and 420b and the first mounting portion 44 of the second conductor 40, and between the bottom surfaces of the cores 420a and 420b and the second mounting portion 45 of the second conductor 40.

[0156] The inner insulating portion 91 primarily serves to provide insulation between the cores 420a and 420b and the mounting portions 44 and 45 of the second conductor 40. Specifically, by placing a portion of the inner insulating portion 91 between the bottom surfaces of the cores 420a and 420b and the first mounting portion 44, it becomes possible to ensure a sufficient insulation distance between them via the inner insulating portion 91, thereby providing sufficient insulation between the bottom surfaces of the cores 420a and 420b and the first mounting portion 44. Similarly, by placing a portion of the inner insulating portion 91 between the bottom surfaces of the cores 420a and 420b and the second mounting portion 45, it becomes possible to ensure a sufficient insulation distance between them via the inner insulating portion 91, thereby providing sufficient insulation between the bottom surfaces of the cores 420a and 420b and the second mounting portion 45.

[0157] Furthermore, by placing a portion of the inner insulating portion 91 between the bottom surfaces of the cores 420a and 420b and the first mounting portion 44 of the second conductor 40, and filling the space between them with the inner insulating portion 91, it is possible to effectively prevent the problem of the first mounting portion 44 and the bottom surfaces of the cores 420a and 420b being connected by solder when the first mounting portion 44 is connected to the land pattern of the mounting board, for example, with solder (occurrence of short-circuit failure). Similarly, by placing a portion of the inner insulating portion 91 between the bottom surfaces of the cores 420a and 420b and the second mounting portion 45 of the second conductor 40, and filling the space between them with the inner insulating portion 91, it is possible to effectively prevent the problem of the second mounting portion 45 and the bottom surfaces of the cores 420a and 420b being connected by solder when the second mounting portion 45 is connected to the land pattern of the mounting board, for example, with solder (occurrence of short-circuit failure).

[0158] The upper surface of the inner insulating portion 91 and the bottom surfaces of the cores 420a and 420b are not in contact, and a gap is formed between the upper surface of the inner insulating portion 91 and the bottom surfaces of the cores 420a and 420b. The width of the inner insulating portion 91 in the X-axis direction is smaller than the distance between the first conductor side portion 41 and the second conductor side portion 42 of the second conductor 40, which makes it possible to smoothly insert (position) the inner insulating portion 91 along the Y-axis direction between the first conductor side portion 41 and the second conductor side portion 42.

[0159] As shown in Figure 14A, an outer inclined portion 910a is formed on the upper surface of the inner insulating portion 91. The outer inclined portion 910a has a tapered surface and is inclined to become lower toward the outside in the Y-axis direction at the end of the inner insulating portion 91 on the positive Y-axis side. Due to the provision of the outer inclined portion 910a, the thickness of the inner insulating portion 91 in the Z-axis direction decreases toward the outside in the Y-axis direction. As shown in Figure 15, the bottom inclined portion 910a is inclined to be spaced apart in the Z-axis direction from the bottom surfaces of the cores 420a and 420b. The bottom inclined portion 910a is formed only on the upper surface of the inner insulating portion 91, but it may also be formed on the lower surface of the inner insulating portion 91.

[0160] By forming a bottom inclined portion 910a on at least one of the upper and lower surfaces of the inner insulating portion 91, it becomes possible to prevent the inner insulating portion 91 from interfering with (contacting) the bottom surfaces of the cores 420a, 420b, etc., when attaching the resin spacer 90 to the second conductor 40, thereby making the attachment of the resin spacer 90 smoother.

[0161] As shown in Figure 14A, a lateral inclined portion 912a is formed on one side of the inner insulating portion 91 in the X-axis direction, and a lateral inclined portion 912b is formed on the other side of the inner insulating portion 91 in the X-axis direction. The lateral inclined portions 912a and 912b have tapered surfaces and are inclined inward in the X-axis direction at the end of the inner insulating portion 91 on the positive Y-axis side. Due to the presence of the lateral inclined portions 912a and 912b, the width of the inner insulating portion 91 in the X-axis direction decreases as it moves outward in the Y-axis direction. As shown in Figure 15, the lateral inclined portion 912a is inclined to be spaced apart in the X-axis direction from the lower end of the first conductor side portion 41 of the second conductor 40. The lateral inclined portion 912b is inclined to be spaced apart in the X-axis direction from the lower end of the second conductor side portion 42 of the second conductor 40.

[0162] By forming side inclined portions 912a and 912b on the inner insulating portion 91, it becomes possible to prevent the ends of the resin spacer 90 in the X-axis direction from interfering with (contacting) the first conductor side portion 41 and the second conductor side portion 42 of the second conductor 40 when the resin spacer 90 is attached to the second conductor 40, thereby making the attachment of the resin spacer 90 smoother.

[0163] As shown in Figure 14B, a projection 94 is formed on the lower surface (bottom surface) of the inner insulating portion 91. The projection 94 protrudes from the lower surface of the inner insulating portion 91 and extends along the Y-axis direction. A bottom inclined portion 94a is formed on one side surface of the projection 94 in the X-axis direction, and a bottom inclined portion 94b is formed on the other side surface of the projection 94 in the X-axis direction. The projection 94 has a shape that tapers along its projection direction, and the cross-sectional shape of the projection 94 (cross-sectional shape parallel to the XZ plane) is approximately trapezoidal. One end of the projection 94 in the Y-axis direction is connected to a connecting portion 96, and the other end of the projection 94 in the Y-axis direction is located at the other end of the inner insulating portion 91 in the Y-axis direction.

[0164] As shown in Figure 15, at least a portion of the protrusion 94 (in this embodiment, the entire protrusion 94) is positioned between the first mounting portion 44 and the second mounting portion 45 of the second conductor 40. By forming the protrusion 94 on the lower surface of the inner insulating portion 91, it is possible to effectively insulate the tip portion 44a of the first mounting portion 44 and the tip portion 45a of the second mounting portion 45 via the protrusion 94, thereby preventing problems such as solder balls connecting them (occurrence of short-circuit failures). The lower surface (protruding surface) of the protrusion 94 is substantially flush with the lower surface of the connection portion 96 and the lower surfaces of the lateral insulating portions 92a and 92b.

[0165] As shown in Figure 14B, a first stepped surface 911a and a second stepped surface 912b are formed on the lower surface of the inner insulating portion 91. The first stepped surface 911a is formed on the positive X-axis side of the protrusion 94, and the second stepped surface 911b is formed on the negative X-axis side of the protrusion 94. The step heights of the stepped surfaces 911a and 911b correspond to the protrusion length of the protrusion 94. As shown in Figure 15, the upper surface of the first mounting portion 44 abuts against the first stepped surface 911a, and the upper surface of the second mounting portion 45 abuts against the second stepped surface 911b. As a result, the first mounting portion 44 is fixed to the first stepped surface 911a, and the second mounting portion 45 is fixed to the second stepped surface 911b, so that the resin spacer 90 can be stably attached to the second conductor 40.

[0166] The step height of the first stepped surface 911a is smaller than the thickness of the first mounting portion 44. Therefore, when the upper surface of the first mounting portion 44 is in contact with the first stepped surface 911a, the lower surface of the first mounting portion 44 will be located below (overhanging) the tip of the protruding portion 94. Similarly, the step height of the second stepped surface 911b is smaller than the thickness of the second mounting portion 45. Therefore, when the upper surface of the second mounting portion 45 is in contact with the second stepped surface 911b, the lower surface of the second mounting portion 45 will be located below (overhanging) the tip of the protruding portion 94.

[0167] Furthermore, when the resin spacer 90 is attached to the second conductor 40, the lower surface of the first mounting portion 44 is located below the lower surface of the first lateral insulating portion 92a of the resin spacer 90, and the lower surface of the second mounting portion 45 is located below the lower surface of the second lateral insulating portion 92b of the resin spacer 90. As a result, in this embodiment, the bottom surface of the resin spacer 90 is positioned above the lower surfaces of the first mounting portion 44 and the second mounting portion 45 of the second conductor 40, and above the lower surfaces of the first mounting portion 34 and the second mounting portion 35 of the first conductor 30.

[0168] By adopting this configuration, when the coil device 410 is mounted on the mounting board with the resin spacer 90 attached to the second conductor 40, it becomes possible to prevent the resin spacer 90 from interfering with (contacting) the mounting board, and sufficient mounting strength between the coil device 410 and the mounting board can be ensured.

[0169] As shown in Figure 14A, the first lateral insulating portion 92a is positioned adjacent to the inner insulating portion 91 on the positive X-axis side and extends linearly along the Y-axis for a predetermined length. The second lateral insulating portion 92b is positioned adjacent to the inner insulating portion 91 on the negative X-axis side and extends linearly along the Y-axis for a predetermined length. The lengths of the lateral insulating portions 92a and 92b along the Y-axis are shorter than the lengths of the inner insulating portion 91 along the Y-axis. As a result, the lengths of the lateral insulating portions 92a and 92b along the Y-axis are relatively short, increasing the durability of the lateral insulating portions 92a and 92b and preventing damage to them.

[0170] As shown in Figure 15, the thickness of the lateral insulating portions 92a and 92b along the Z-axis direction is smaller than the thickness of the inner insulating portion 91 along the Z-axis direction, and a step is formed between the upper surfaces of the lateral insulating portions 92a and 92b and the upper surface of the inner insulating portion 91.

[0171] The first lateral insulating portion 92a is positioned between the first mounting portion 34 of the first conductor 30 and the first mounting portion 44 of the second conductor 40. This allows for sufficient insulation distance between them via the first lateral insulating portion 92a, thereby providing sufficient insulation between the first mounting portion 34 of the first conductor 30 and the first mounting portion 44 of the second conductor 40. Similarly, the second lateral insulating portion 92b is positioned between the second mounting portion 35 of the first conductor 30 and the second mounting portion 45 of the second conductor 40. This allows for sufficient insulation distance between them via the second lateral insulating portion 92b, thereby providing sufficient insulation between the second mounting portion 35 of the first conductor 30 and the second mounting portion 45 of the second conductor 40.

[0172] As shown in Figure 14A, a first inclined portion 95a is formed on the upper surface of the first lateral insulating portion 92a, and a second inclined portion 95b is formed on the upper surface of the second lateral insulating portion 92b. The first inclined portion 95a extends continuously along the longitudinal direction of the first lateral insulating portion 92a, and the second inclined portion 95b extends continuously along the longitudinal direction of the second lateral insulating portion 92b.

[0173] As shown in Figure 15, the first inclined portion 95a is inclined to be lower toward the positive X-axis direction at a position facing the first mounting portion 34 of the first conductor 30. The second inclined portion 95b is inclined to be lower toward the negative X-axis direction at a position facing the second mounting portion 35 of the first conductor 30.

[0174] By forming a first inclined portion 95a on the first lateral insulating portion 92a, when the first lateral insulating portion 92a is positioned between the first mounting portion 34 of the first conductor 30 and the first mounting portion 44 of the second conductor 40, it is possible to prevent the first lateral insulating portion 92a from interfering with (contacting) the first mounting portion 34 of the first conductor 30. Furthermore, by forming a second inclined portion 95b on the second lateral insulating portion 92b, when the second lateral insulating portion 92b is positioned between the second mounting portion 35 of the first conductor 30 and the second mounting portion 45 of the second conductor 40, it is possible to prevent the second lateral insulating portion 92b from interfering with (contacting) the second mounting portion 35 of the first conductor 30.

[0175] As shown in Figure 14A, a first groove (first gap) 93a is formed between the first lateral insulating portion 92a and one end of the inner insulating portion 91 in the X-axis direction, and a second groove (second gap) 93b is formed between the second lateral insulating portion 92b and the other end of the inner insulating portion 91 in the X-axis direction. In this embodiment, the resin spacer 90 can be attached to the second conductor 40 by fitting one end of the second conductor 40 (the lower end b of the first conductor side portion 41) into the first groove 93a and the other end of the second conductor 40 (the lower end of the second conductor side portion 42) into the second groove 93b, making it easy to attach the resin spacer 90 to the second conductor 40.

[0176] The end of the first lateral insulating portion 92a on the negative Y-axis side, the end of the second lateral insulating portion 92b on the negative Y-axis side, and the end of the inner insulating portion 91 on the negative Y-axis side are connected by a connecting portion 96. The connecting portion 96 extends along the X-axis direction. By connecting the first lateral insulating portion 92a, the second lateral insulating portion 92b, and the inner insulating portion 91 along the X-axis direction with the connecting portion 96, it becomes possible to construct a resin spacer 90 in which these are integrated via the connecting portion 96, making it easier to attach the resin spacer 90 to the second conductor 40 compared to when they are constructed as separate parts. Note that the end of the first lateral insulating portion 92a on the positive Y-axis side, the end of the second lateral insulating portion 92b on the positive Y-axis side, and the end of the inner insulating portion 91 on the positive Y-axis side are not connected by a connecting portion, and the positive Y-axis side of the first groove portion 93a and the positive Y-axis side of the second groove portion 93b are open.

[0177] An outer inclined portion 960a is formed on the upper surface of the connecting portion 96, sloping downward toward the negative Y-axis direction. The outer inclined portion 960a is formed continuously from one end to the other in the X-axis direction of the connecting portion 96. Also, as shown in Figure 14B, an outer inclined portion 960b is formed on the lower surface of the connecting portion 96, sloping downward toward the negative Y-axis direction. The outer inclined portion 960b is formed continuously from one end to the other in the X-axis direction of the connecting portion 96. The outer inclined portions 960a and 960b have symmetrical shapes.

[0178] As will be described later, after attaching the resin spacer 90 to the second conductor 40, the assembly of the first conductor 30 and the second conductor 40 is attached to the cores 420a and 420b. By forming outward inclined portions 960a and 960b on the connecting portion 96, it is possible to prevent the connecting portion 96 from interfering with (contacting) the bottom surface of the cores 420a and 420b during this process, making it easier to carry out the process.

[0179] A notch 96a is formed at the end of the connecting portion 96 on the negative Y-axis side. The notch 96a consists of a recess extending from the negative Y-axis end of the connecting portion 96 toward the positive Y-axis side. The notch 96 is provided to make it easier to distinguish the front and back sides of the resin spacer 90 using an imaging device such as a CCD camera. The notch 96 is located on the negative side of the center of the connecting portion 96 in the X-axis direction, but it may also be located on the positive side. By placing the notch 96 on one side of the connecting portion 96 in the X-axis direction, it becomes easier to distinguish the front and back sides of the resin spacer 96.

[0180] Next, the manufacturing method of the coil device 410 will be explained, focusing on the method of attaching the resin spacer 90 to the second conductor 40. First, the resin spacer 90 is attached to the second conductor 40, and this is done using a jig 100 as shown in Figure 16A. The jig 100 has a jig body 110, a conductor fixing part 120, a spacer insertion part 130, and a conductor mounting part 140.

[0181] The jig body 110 has a roughly rectangular parallelepiped shape with its longitudinal direction in the X-axis direction. On the Y-axis positive side of the jig body 110, a plurality (8) of conductor fixing parts 120 are arranged at regular intervals along the X-axis direction. The conductor fixing parts 120 have a roughly rectangular parallelepiped shape and protrude toward the Y-axis positive side. The inner surface of the roughly C-shaped second conductor 40 can be hooked onto the outer surface of the conductor fixing parts 120, thereby enabling the second conductor 40 to be fixed to the conductor fixing parts 120 (see Figure 16B).

[0182] The width of the conductor fixing portion 120 in the X-axis direction is preferably equal to or less than the distance in the X-axis direction between the first conductor side portion 41 and the second conductor side portion 42 of the second conductor 40, and more preferably approximately equal to it. This allows the second conductor 40 to be fixed to the conductor fixing portion 120 securely or without displacement.

[0183] On the Y-axis positive side surface of the jig body 110, a plurality (eight) of spacer insertion sections 130 are arranged at regular intervals along the X-axis direction. Each of the multiple spacer insertion sections 130 is formed in a position corresponding to a plurality of conductor fixing sections 120. More specifically, the spacer insertion sections 130 are formed in a position offset below the conductor fixing sections 120. The spacer insertion sections 130 have a concave shape that recesses from the Y-axis positive side surface of the jig body 110 toward the Y-axis negative side, and a portion of the resin spacer 90 (the Y-axis positive side end of the inner insulating section 91 and the Y-axis positive side ends of the lateral insulating sections 92a and 92b shown in Figure 14A) can be placed inside.

[0184] The width of the spacer insertion portion 130 in the X-axis direction is preferably equal to or greater than the width of the resin spacer 90 in the X-axis direction shown in Figure 14A, and more preferably approximately equal to it. This prevents displacement of the resin spacer 90 in the X-axis direction when a portion of the resin spacer 90 is placed inside the spacer insertion portion 130.

[0185] The conductor mounting portion 140 has a substantially rectangular parallelepiped shape with its longitudinal direction in the X-axis direction and is connected to the lower end of the jig body portion 120. The width of the conductor mounting portion 140 in the X-axis direction is substantially equal to the width of the jig body portion 120 in the X-axis direction. The conductor mounting portion 140 has a shape that protrudes in the positive Y-axis direction more than the face of the jig body portion 120 on the positive Y-axis side.

[0186] The mounting portions 34 and 35 of the first conductor 30 and 44 and 45 of the second conductor 40 can be placed on the upper surface of the conductor mounting portion 140. Preferably, the Y-axis width of the conductor mounting portion 140 (the projection length from the Y-axis positive side surface of the jig body portion 120) is larger than the Y-axis width of the mounting portions 34 and 35 of the first conductor 30 and 44 and 45 of the second conductor 40. This allows the mounting portions 34 and 35 of the first conductor 30 and 44 and 45 of the second conductor 40 to be placed on the upper surface of the conductor mounting portion 140 in a stable state.

[0187] To attach the resin spacer 90 to the second conductor 40, first prepare the jig 100 shown in Figure 16A, and then fix the second conductor 40 to the conductor fixing part 120 of the jig 100 so that the inner surface of the second conductor 40 abuts against the outer surface of the conductor fixing part 120 as shown in Figure 16B. The first mounting part 44 and the second mounting part 45 of the second conductor 40 are placed on the upper surface of the conductor mounting part 140. In Figure 16B, the second conductor 40 is fixed to only one conductor fixing part 120 of the jig 100, but other second conductors 40 may be fixed to other conductor fixing parts 120.

[0188] Next, as shown in Figure 16C, the resin spacer 90 is attached to the second conductor 40. When attaching the resin spacer 90, the resin spacer 90 is attached by sliding it toward the second conductor 40 in the Y-axis direction so that the first groove 93a and the second groove 93b of the resin spacer 90 fit into the first conductor side 41 and the second conductor side 42 of the second conductor 40, respectively. When the resin spacer 90 is inserted toward the first conductor side 41 and the second conductor side 42 until the first conductor side 41 is located near the bottom of the first groove 93a and the second conductor side 42 is located near the bottom of the second groove 93b, the end of the resin spacer 90 on the negative Y-axis side is inserted into the spacer insertion part 130. By inserting the end of the resin spacer 90 on the negative Y-axis side into the spacer insertion part 130 in this way, it is possible to prevent the end of the resin spacer 90 on the positive Y-axis side from being positioned in a position that unnecessarily protrudes toward the positive Y-axis side.

[0189] Next, as shown in Figure 16D, the resin spacer 90 is slid downward along the first conductor side portion 41 and the second conductor side portion 42 of the second conductor 40, positioning the resin spacer 90 at the positions of the first mounting portion 44 and the second mounting portion 45 of the second conductor 40. At this time, the resin spacer 90 is slid downward along the first conductor side portion 41 and the second conductor side portion 42 until the upper surface of the first mounting portion 44 abuts against the first stepped surface 911a (Figure 14B) formed on the bottom surface of the inner insulating portion 91 of the resin spacer 90, and the upper surface of the second mounting portion 45 abuts against the second stepped surface 911b (Figure 14B).

[0190] Adhesive is applied in advance to the upper surfaces of the first mounting section 44 and the second mounting section 45, or to the first stepped surface 911a and the second stepped surface 911b of the inner insulating section 91. This allows the upper surface of the first mounting section 44 to be joined with the adhesive when it comes into contact with the first stepped surface 911a. Similarly, it allows the upper surface of the second mounting section 45 to be joined with the adhesive when it comes into contact with the second stepped surface 911b. Epoxy resin, acrylic resin, or urethane resin can be used as the adhesive. When the adhesive is curing, it is preferable to press the upper surface of the resin spacer 90 toward the mounting sections 44 and 45 to improve adhesion between them and ensure good bonding between the stepped surfaces 911a and 911b.

[0191] Next, the first conductor 30 is placed on the outside of the second conductor 40. The first conductor 30 is installed such that the first conductor side portion 31 of the first conductor 30 faces the first conductor side portion 41 of the second conductor 40, and the second conductor side portion 32 of the first conductor 30 faces the second conductor side portion 42 of the second conductor 40. The first mounting portion 34 and the second mounting portion 35 of the first conductor 30 are placed on the conductor mounting portion 140. Next, adhesive is applied, for example, only to a few localized areas between the inner surface of the first conductor 30 and the outer surface of the second conductor 40, and then cured. This forms a conductor assembly consisting of the first conductor 30, the second conductor 40, and the resin spacer 90.

[0192] Next, the first core 420a and the second core 420b shown in Figure 13 are attached to this conductor assembly. The sides of the conductor assembly on the negative Y-axis side are joined to the first core 420a, the sides of the conductor assembly on the positive Y-axis side are joined to the second core 420b, and the first core 420a and the second core 420b are joined with adhesive. For the sides of the conductor assembly on the negative Y-axis side and the first core 420a, it is sufficient to join them locally in a few places with adhesive, for example, but the joining with adhesive may be omitted. Similarly, for the sides of the conductor assembly on the positive Y-axis side and the second core 420b, it is sufficient to join them locally in a few places with adhesive, for example, but the joining with adhesive may be omitted. The first core 420a and the second core 420b can be joined together by bonding the first middle leg portion 22a and the second middle leg portion 22b to each other with adhesive, as shown in Figures 1B and 2, and by bonding the first outer leg portion 23a and the second outer leg portion 23b to each other with adhesive. After that, the coil device 410 shown in Figure 13 can be manufactured by curing the adhesive. Note that the resin spacer 90 may be attached to the second conductor 40 after the cores 420a and 420b have been assembled to the first conductor 30 and the second conductor 40.

[0193] In this embodiment as well, the same effects as in the fourth embodiment can be obtained. In particular, in this embodiment, as shown in Figures 14A and 14B, the inner insulating portion 91 is provided with an outer inclined portion 910a and side inclined portions 912a and 912b, and the connecting portion 96 is provided with outer inclined portions 960a and 960b. This makes it possible to prevent the resin spacer 90 from interfering with (contacting) the core 420a, 420b, etc. when attaching the resin spacer 90 to the second conductor 40, and makes it easier to attach the resin spacer 90 to the second conductor 40.

[0194] Sixth Embodiment The coil device 510 according to the sixth embodiment of the present invention differs only in the following points, and its other configurations are the same as those of the fifth embodiment described above, and it provides the same effects. In the drawings, common reference numerals are used for members common to the fifth embodiment, and descriptions of overlapping parts are omitted.

[0195] As shown in Figure 17A, the coil device 510 has a resin spacer 590. As shown in Figure 18, the resin spacer 590 has an inner insulating portion 91, a first lateral insulating portion 92a, a second lateral insulating portion 92b, a connecting portion 96, and a connecting portion 97. The connecting portion 97 connects the Y-axis positive end of the first lateral insulating portion 92a, the Y-axis positive end of the inner insulating portion 91, and the Y-axis positive end of the second lateral insulating portion 92b along the X-axis direction. The shape of the connecting portion 97 is the same as that of the connecting portion 96.

[0196] The connecting portion 96 and the connecting portion 97 do not have the outer inclined portions 960a and 960b shown in Figures 14A and 14B. Furthermore, the bottom surface of the resin spacer 590 does not have the first stepped surface 911a and the second stepped surface 911b shown in Figure 14B. In other words, the top and bottom surfaces of the resin spacer 590 are flat surfaces.

[0197] On the other hand, a bottom groove 98 is formed on the lower surface of the inner insulating portion 91 of the resin spacer 590 in the central part in the X-axis direction. The bottom groove 98 extends along the Y-axis direction from one end to the other of the inner insulating portion 91 in the Y-axis direction. By forming the bottom groove 98 on the lower surface of the inner insulating portion 91, for example, when the first mounting portion 44 and the second mounting portion 45 of the second conductor 40 are connected to the mounting substrate with solder, the bottom groove 98 can prevent the molten solder from flowing between the first mounting portion 44 and the second mounting portion 45 by crawling along the lower surface of the inner insulating portion 91. Note that a groove corresponding to the bottom groove 98 may also be formed along the Y-axis direction in the central part in the X-axis direction on the upper surface of the inner insulating portion 91.

[0198] The first groove 593a is surrounded on all four sides by the first lateral insulating portion 92a, one end of the inner insulating portion 91 in the X-axis direction, and the connecting portion 96 and the connecting portion 97. The second groove 593b is surrounded on all four sides by the second lateral insulating portion 92b, the other end of the inner insulating portion 91 in the X-axis direction, and the connecting portion 96 and the connecting portion 97. As shown in Figure 17B, the opening shape of the first groove 593a corresponds to the bottom shape of the first mounting portion 44 of the second conductor 40, and the first mounting portion 44 can be inserted into the first groove 593a. The opening shape of the second groove 593b corresponds to the bottom shape of the second mounting portion 45 of the second conductor 40, and the second mounting portion 45 can be inserted into the second groove 593b.

[0199] As shown in Figure 19, the resin spacer 590 is attached to the bottom surface of the cores 420a and 420b with adhesive (or without adhesive) attached to the first conductor 30 and the second conductor 40 (the assembly of the first conductor 30 and the second conductor 40 described above). The resin spacer 590 is attached by inserting (passing through) one end of the second conductor 40 into the first groove 593a and the second groove 593b of the resin spacer 590, respectively.

[0200] The upper surface of the resin spacer 590 is bonded to the bottom surface of the cores 420a and 420b by adhesive in only a few localized places. With the resin spacer 590 attached to the bottom surface of the cores 420a and 420b, a portion of the mounting portion 44 and 45 of the second conductor 40 is housed inside the grooves 593a and 593b, while the remaining portion of the mounting portion 44 and 45 is exposed outside the grooves 593a and 593b. In other words, the bottom surface of the resin spacer 590 is located above the bottom surface of the mounting portion 44 and 45, which allows the mounting portion 44 and 45 to be properly connected to the land pattern of the mounting board by solder or the like without being obstructed by the resin spacer 590.

[0201] In this embodiment as well, the same effects as in the fifth embodiment can be obtained. In particular, in this embodiment, the resin spacer 590 can be installed in the coil device 510 simply by inserting the first mounting portion 44 and the second mounting portion 45 of the second conductor 40 through the first groove portion 593a and the second groove portion 593b, respectively, and fixing the upper surface of the resin spacer 590 to the bottom surface of the cores 420a and 420b, making the installation of the resin spacer 590 easy.

[0202] Seventh Embodiment The coil device 610 according to the seventh embodiment of the present invention differs only in the following points, and its other configurations are the same as those of the sixth embodiment described above, and it provides the same effects. In the drawings, common reference numerals are used for members common to the sixth embodiment, and descriptions of overlapping parts are omitted.

[0203] As shown in Figure 20, the coil device 610 has a first core 620a, a second core 620b, and a resin spacer 690. As shown in Figure 21, the first core 620b has a second base portion 621b, and a side recess 28 is formed on the outer surface of the second base portion 621b. The side recess 28 is formed at the lower end of the outer surface of the second base portion 621b, and the lower end of the side recess 28 is connected to the bottom recess 27. Since the first core 620a has the same shape as the second core 620b, a detailed explanation thereof is omitted.

[0204] The side recess 28 has an arm mounting portion 28a and an engagement recess 28b. The arm mounting portion 28a has a concave shape that recesses inward in the Y-axis direction from the surface of the second base portion 621b. The arm mounting portion 28a is formed approximately in the center of the second base portion 621b in the X-axis direction and extends upward along the Z-axis direction for a predetermined length from the bottom recess 27 of the second core 620b.

[0205] The engaging recess 28b is formed at the upper end of the arm mounting portion 28a. The engaging recess 28b has a concave shape that recesses inward in the Y-axis direction from the surface of the second base portion 621b, and the depth of the engaging recess 28b along the Y-axis direction is greater than the depth of the arm mounting portion 28a along the Y-axis direction. An inclined surface is formed on the bottom surface of the engaging recess 28b, and the engaging recess 28b is formed so that its width narrows towards the bottom.

[0206] As shown in Figure 22, the resin spacer 690 differs from the resin spacer 590 in the sixth embodiment shown in Figure 18 in that it has arm portions 99a and 99b. Arm portion 99a is raised upward along the Z-axis from the upper surface of the connecting portion 96, and arm portion 99b is raised upward along the Z-axis from the upper surface of the connecting portion 97.

[0207] The arm portions 99a and 99b each have an arm body portion 990a and 990b and a protrusion portion 991a and 991b. The arm body portions 990a and 990b have a columnar structure (approximately rectangular parallelepiped shape) with their longitudinal direction in the Z-axis direction. The protrusion portion 991a is formed at the tip of the arm body portion 990a and protrudes toward the positive Y-axis direction (the center of the resin spacer 690). The protrusion portion 991b is formed at the tip of the arm body portion 990b and protrudes toward the negative Y-axis direction (the inside of the resin spacer 690). The protrusion portions 991a and 991b are arranged opposite each other along the Y-axis direction. The protrusion portions 991a and 991b have inclined surfaces and are formed to taper toward the direction of protrusion. The convex shape of the protrusion portion 991b corresponds to the concave shape of the engagement recess 28b shown in Figure 21.

[0208] As shown in Figures 21 and 22, the arm body portion 990b is fixed to the arm mounting portion 28a of the second core 620b. Similarly, the arm body portion 990a is fixed to the arm mounting portion (not shown) of the first core 620a. The protrusion 991b engages with the engagement recess 28b of the second core 620b (see Figure 23), and the protrusion 991b engages with the engagement recess (not shown) of the second core 620a. When the arm portions 99a and 99b are fixed to the cores 620a and 620b, the surfaces of the arm portions 99a and 99b are substantially flush with the outer surfaces (surfaces) of the cores 620a and 620b.

[0209] By engaging the protrusion 991b with the engagement recess 28b of the second core 620b, the arm portion 99b can be fixed to the outer surface of the second core 620b in the Y-axis direction. Similarly, by engaging the protrusion 991a with the engagement recess (not shown) of the second core 620a, the arm portion 99a can be fixed to the outer surface of the first core 620a in the Y-axis direction. As a result, the resin spacer 690 can be fixed to the cores 620a and 620b via the arm portions 99a and 99b, and the resin spacer 690 can be attached to the cores 620a and 620b without using adhesive. The resin spacer 690 is attached to the cores 620a and 620b with adhesive (or without using adhesive) while the cores 620a and 620b are attached to the first conductor 30 and the second conductor 40 (assembly of the first conductor 30 and the second conductor 40). As shown in Figure 23, when the resin spacer 690 is fixed to the cores 620a and 620b, a gap is formed between the upper surface of the resin spacer 690 (inner insulating part 91, connecting parts 96 and 97, lateral insulating parts 92a and 92b) and the bottom surface of the cores 620a and 620b, and they are not in close contact.

[0210] Eighth Embodiment The coil device 710 according to the eighth embodiment of the present invention differs only in the following points, and its other configurations are the same as those of the sixth embodiment described above, and it provides the same effects. In the drawings, common reference numerals are used for members common to the sixth embodiment, and descriptions of overlapping parts are omitted.

[0211] As shown in Figure 24A, the coil device 710 has a resin spacer 790. As shown in Figure 25, the resin spacer 790 has a first groove 793a and a second groove 793b. The X-axis width of the first groove 793a is smaller than the X-axis width of the first groove 593a of the resin spacer 590 shown in Figure 18. Similarly, the X-axis width of the second groove 793b is smaller than the X-axis width of the second groove 593b of the resin spacer 590 shown in Figure 18. The X-axis widths of the grooves 793a and 793b are approximately equal to the plate thickness of the second conductor 40.

[0212] In this embodiment, as shown in Figure 26, the first groove 793a functions as an insertion passage for the first conductor side portion 41 of the second conductor 40, and the lower end of the first conductor side portion 41 of the second conductor 40 is inserted through the first groove 793a. The second groove 793b functions as an insertion passage for the second conductor side portion 42 of the second conductor 40, and the lower end of the second conductor side portion 42 of the second conductor 40 is inserted through the second groove 793b. In other words, the first mounting portion 44 of the second conductor 40 is not placed (inserted) through the first groove 793a, and the second mounting portion 45 of the second conductor 40 is not placed (inserted) through the second groove 793b.

[0213] As shown in Figure 25, an outward inclined portion 960a extending along the X-axis is formed at the end of the connecting portion 96 on the negative Y-axis side, and an outward inclined portion 960b extending along the X-axis is formed at the end of the connecting portion 97 on the positive Y-axis side.

[0214] As shown in Figure 24B, a spacer recess 913a is formed on the lower surface of the inner insulating portion 91 on the positive X-axis side, and a spacer recess 913b is formed on the negative X-axis side. The spacer recess 913a and the spacer recess 913b are arranged with a predetermined distance between them in the X-axis direction, and this distance is equal to or greater than the distance between the first mounting portion 44 and the second mounting portion 45 of the second conductor 40.

[0215] The first mounting portion 44 of the second conductor 40 is housed in the spacer recess 913a, and the upper surface of the first mounting portion 44 abuts against the bottom surface of the spacer recess 913a. The second mounting portion 45 of the second conductor 40 is housed in the spacer recess 913b, and the upper surface of the second mounting portion 45 abuts against the bottom surface of the spacer recess 913b. As shown in Figure 26, when the mounting portions 44 and 45 are housed in the spacer recesses 913a and 913b, a portion of the mounting portions 44 and 45 of the second conductor 40 is housed inside the spacer recesses 913a and 913b, while the remaining portion of the mounting portions 44 and 45 is exposed to the outside of the spacer recesses 913a and 913b. By housing a portion of the mounting portions 44 and 45 in the spacer recesses 913a and 913b in this way, good insulation can be achieved between the first mounting portion 44 and the second mounting portion 45.

[0216] When attaching the resin spacer 790 to the second conductor 40, the second conductor 40 is prepared before the shapes of the first mounting portion 44 and the second mounting portion 45 are given to it, that is, the second conductor 40 having a roughly C-shape. Then, the first groove portion 793a is inserted through one end of the second conductor 40, and the second groove portion 793b is inserted through the other end. After that, one end of the second conductor 40 is bent (i.e., the first mounting portion 44 is given to the second conductor 40), and the end is housed in the spacer recess 913a so that its upper surface abuts against the bottom surface of the spacer recess 913a. The other end of the second conductor 40 is also bent (i.e., the second mounting portion 45 is given to the second conductor 40), and the end is housed in the spacer recess 913b so that its upper surface abuts against the bottom surface of the spacer recess 913b. In other words, after attaching the resin spacer 790 to the roughly C-shaped second conductor 40, forming is performed on the second conductor 40 to give it the shape of the first mounting portion 44 and the second mounting portion 45. The resin spacer 790 is attached to the bottom surface of the second conductor 40 or the cores 420a, 420b, with the cores 420a, 420b attached to the first conductor 30 and the second conductor 40 (assembly of the first conductor 30 and the second conductor 40) with adhesive (or without adhesive).

[0217] In this embodiment, the same effects as in the sixth embodiment can be obtained. In addition, in this embodiment, as shown in Figure 26, when the resin spacer 790 is attached to the second conductor 40, the upper surfaces of the resin spacer 790 (inner insulating portion 91, connecting portions 96, 97 and lateral insulating portions 92a, 92b) are in contact with the bottom surfaces of the cores 420a, 420b. Therefore, the inner insulating portion 91, etc., can ensure good insulation between the mounting portions 44, 45 of the second conductor 40 and the bottom surfaces of the cores 420a, 420b.

[0218] Furthermore, the resin spacer 790 is pressed upward in the Z-axis direction by the first mounting section 44 and the second mounting section 45, thereby being fixed in place by being sandwiched between the mounting sections 44, 45 and the cores 420a, 420b. Therefore, the resin spacer 790 can be installed without using adhesive.

[0219] Ninth Embodiment The coil device 810 according to the ninth embodiment of the present invention differs only in the following points, and its other configurations are the same as those of the eighth embodiment described above, and it provides the same effects. In the drawings, common reference numerals are used for members common to the eighth embodiment, and descriptions of overlapping parts are omitted.

[0220] As shown in Figure 27, the coil device 810 includes a second conductor 840 and a resin spacer 890. The second conductor 840 does not have the first mounting portion 44 and the second mounting portion 45 shown in Figure 26, but it has a first lateral bend portion 48 and a second lateral bend portion 49. The first lateral bend portion 48 is formed at one end of the second conductor 40 and bends inward in the X-axis direction and downward in the Z-axis direction. Similarly, the second lateral bend portion 49 is formed at the other end of the second conductor 40 and bends inward in the X-axis direction and downward in the Z-axis direction. That is, the first lateral bend portion 48 and the second lateral bend portion 49 bend toward each other in the X-axis direction and then extend parallel to each other along the Z-axis direction.

[0221] As shown in Figure 28, a first lateral step portion 920a extending along the Y-axis is formed on the upper surface of the first lateral insulating portion 92a of the resin spacer 890. Similarly, a second lateral step portion 920b extending along the Y-axis is formed on the upper surface of the second lateral insulating portion 92b. The height of each step portion of the first lateral step portion 920a and the second lateral step portion 920b is equal to or greater than the plate thickness of the second conductor 840. Note that the inclined portions 95a and 95b shown in Figure 25 are not formed on the upper surfaces of the lateral insulating portions 92a and 92b, and the outer inclined portions 960a and 960b shown in Figure 25 are not formed on the connecting portions 96 and 97. Furthermore, the spacer recesses 913a and 913b shown in Figure 24B are not formed on the lower surface of the inner insulating portion 91.

[0222] As shown in Figure 27, the first lateral step portion 920a has a first lateral bend portion 48 (a portion extending in the X-axis direction), and the second lateral bend portion 49 (a portion extending in the X-axis direction) of the second conductor 840 has a second lateral bend portion 920b. The first lateral bend portion 48 is inserted downward through the interior of the first groove portion 793a, and the second lateral bend portion 49 is inserted downward through the interior of the second groove portion 793b. In other words, the resin spacer 890 has a roughly L-shaped insertion passage through which the first lateral bend portion 48 is inserted by the first lateral step portion 920a and the first groove portion 793a. Also, the second lateral step portion 920b and the second groove portion 793b have a roughly L-shaped insertion passage through which the second lateral bend portion 49 is inserted.

[0223] The upper surface of the resin spacer 890 is joined to the bottom surface of the cores 420a and 420b by adhesive or the like. In this embodiment, the same effects as in the eighth embodiment can be obtained. In addition, in this embodiment, since the first mounting portion 44 and the second mounting portion 45 are not formed on the second conductor 840, it is not necessary to form the second conductor 840 to give it the shape of the first mounting portion 44 and the second mounting portion 45 after inserting the lateral bent portions 48 and 49 of the second conductor 40 into the grooves 793a and 793b of the resin spacer 890. Therefore, the manufacturing of the coil device 810 becomes easier.

[0224] Tenth Embodiment The coil device 910 according to the tenth embodiment of the present invention differs only in the following points, and its other configurations are the same as those of the first embodiment described above, and it provides the same effects. In the drawings, common reference numerals are used for members common to the first embodiment, and descriptions of overlapping parts are omitted.

[0225] As shown in Figures 29 and 30, in the coil device 910, the first middle leg portion 23a of the first core 20a and the second middle leg portion 23b of the second core 20b are connected by a magnetic resin layer 200. The magnetic resin layer 200 consists of magnetic powder and a resin containing the magnetic powder. Examples of magnetic powder include metal powder (metallic material) and ferrite. Examples of ferrite include Ni-Zn ferrite and Mn-Zn ferrite. Examples of resin include epoxy resin, acrylic resin, and urethane resin. The magnetic resin layer 200 is in close contact with the surface of the first middle leg portion 23a on the positive Y-axis side and in close contact with the surface of the first middle leg portion 23b on the negative Y-axis side.

[0226] In this embodiment, the magnetic resin layer 200 is formed (applied) over the entire surface of the first middle leg portion 23a on the positive Y-axis side (and / or the surface of the second middle leg portion 23b on the negative Y-axis side). However, the magnetic resin layer 200 may be formed only on a portion of the surface of the first middle leg portion 23a on the positive Y-axis side (and / or the surface of the second middle leg portion 23b on the negative Y-axis side). Preferably, the magnetic resin layer 200 is formed over 30% or more of the surface of the first middle leg portion 23a on the positive Y-axis side (or the surface of the second middle leg portion 23b on the negative Y-axis side), more preferably over 50% or more, and particularly preferably over 75% or more. The larger the area of ​​the region where the magnetic resin layer 200 is formed, the more it is possible to reduce the loss of magnetic flux passing through the first core 20a and the second core 20b, thereby realizing a coil device 910 with excellent inductance characteristics.

[0227] The Y-axis width of the magnetic resin layer 200 corresponds to the Y-axis width of the gap G3 shown in Figure 30, and is preferably 0.1 to 1.0 mm, and more preferably 0.1 to 0.5 mm. However, the Y-axis width of the magnetic resin layer 200 may be smaller than the Y-axis width of the gap G3. The magnetic resin layer 200 may be formed on only one of the surfaces of the first middle leg portion 23a on the positive Y-axis side and the second middle leg portion 23b on the negative Y-axis side. In this case, the Y-axis width of the magnetic resin layer 200 will be smaller than the Y-axis width of the gap G3. Furthermore, even if the magnetic resin layer 200 is formed on both of the above surfaces, if the magnetic resin layer 200 is not formed to span the Y-axis side of the first middle leg portion 23a and the Y-axis side of the second middle leg portion 23b, the Y-axis width of the magnetic resin layer 200 will be smaller than the Y-axis width of the gap G3.

[0228] The magnetic resin layer 200 may be formed locally (in a spot-like manner) at multiple locations on the surface of the first middle leg portion 23a on the positive Y-axis side (or the surface of the second middle leg portion 23b on the negative Y-axis side). Alternatively, the magnetic resin layer 200 may be formed continuously or discontinuously only on the outer edge of the surface of the first middle leg portion 23a on the positive Y-axis side (and / or the surface of the second middle leg portion 23b on the negative Y-axis side). In this case, the shape of the magnetic resin layer 200 may be a ring shape surrounding the outer edge of the surface of the first middle leg portion 23a on the positive Y-axis side (or the surface of the second middle leg portion 23b on the negative Y-axis side).

[0229] Although detailed illustrations are omitted, in the coil device 910, the first outer leg portion 22a of the first core 20a and the second outer leg portion 22b of the second core 20b may be connected by a magnetic resin layer 200. The magnetic resin layer 200 may be formed on both of the pair of first outer leg portions 22a (and / or the pair of second outer leg portions 22b), or on only one of the pair of first outer leg portions 22a (and / or the pair of second outer leg portions 22b).

[0230] In this case as well, the magnetic resin layer 200 may be formed locally (in a spot-like manner) at multiple locations on the surface of the first outer leg portion 22a on the positive Y-axis side (or the surface of the second middle leg portion 22b on the negative Y-axis side). Alternatively, the magnetic resin layer 200 may be formed continuously or discontinuously only on the outer edge of the surface of the first outer leg portion 22a on the positive Y-axis side (and / or the surface of the second middle leg portion 22b on the negative Y-axis side). In this case, the shape of the magnetic resin layer 200 may be a ring shape surrounding the outer edge of the surface of the first outer leg portion 22a on the positive Y-axis side (or the surface of the second outer leg portion 22b on the negative Y-axis side).

[0231] However, if the magnetic resin layer 200 is not formed between the first outer leg portion 22a and the second outer leg portion 22b, and is formed only between the first middle leg portion 22a and the second middle leg portion 22b, it becomes possible to effectively reduce the loss of magnetic flux passing through the first core 20a and the second core 20b, thereby realizing a coil device 910 with excellent inductance characteristics.

[0232] Furthermore, forming a resin layer without magnetic powder between the first outer leg portion 22a and the second outer leg portion 22b, and forming a resin layer (magnetic resin layer 200) containing magnetic powder only between the first middle leg portion 22a and the second middle leg portion 22b, allows for a better (stronger) connection between the first core 20a and the second core 20b.

[0233] It should be noted that the present invention is not limited to the embodiments described above, and can be modified in various ways within the scope of the present invention.

[0234] In the first embodiment described above, the insulating layer 70 formed on the surface of the second conductor 40 ensured insulation between the first conductor 30 and the second conductor 40. However, the insulating layer 70 may also be formed on the surface of the first conductor 30 (particularly on the inner surface of the first conductor 30) to insulate the first conductor 30 and the second conductor 40. Alternatively, the insulating layer 70 may be formed on both the surface of the second conductor 40 and the inner surface of the first conductor 30. The same applies to the second to fourth embodiments described above.

[0235] Furthermore, in the first embodiment described above, insulation between the second conductor 40 and the middle leg portions 23a and 23b of the cores 20a and 20b was ensured by the insulating layer 70 formed on the surface of the second conductor 40. However, the first conductor 30 and the outer leg portions 22a and 22b of the cores 20a and 20b may be insulated by forming the insulating layer 70 on the surface of the first conductor 30 (particularly the outer surface of the first conductor 30). Alternatively, the second conductor 40 may be insulated from the middle legs 23a and 23b of the cores 20a and 20b by forming an insulating layer 70 on the outer circumferential surface of the middle legs 23a and 23b (insulating coating the middle legs 23a and 23b), or the first conductor 30 may be insulated from the outer legs 22a and 22b of the cores 20a and 20b by forming an insulating layer 70 on the outer circumferential surface of the outer legs 22a and 22b of the cores 20a and 20b (insulating coating the outer legs 22a and 22b). The same applies to the second to fourth embodiments described above.

[0236] In the first embodiment described above, the insulating layer 70 was formed continuously along the outer or inner surface of the second conductor 40, but it may also be formed intermittently. The same applies to the second to fourth embodiments described above.

[0237] In the first embodiment described above, the first core 20a and the second core 20b were configured as separate components, but they may be configured as a single unit. The same applies to the second to fourth embodiments described above.

[0238] In the first embodiment described above, the radius of curvature of the outer surface of the inner bent portions 46 and 47 of the second conductor 40 was smaller than the radius of curvature of the inner surface of the outer bent portions 38 and 39 of the first conductor 30, but the above relationship may be reversed. The same effect can be obtained in this case as well. The same applies to the second to fourth embodiments described above.

[0239] In each of the above embodiments, the insulating layer 70 extended continuously along the inner or outer surface of the second conductor 40, but it may also extend intermittently.

[0240] In the first embodiment described above, as shown in Figure 3, the insulating coating layer 26 was formed on the bottom surface of the middle leg portions 23a and 23b, but the position of the insulating coating layer 26 is not limited to this. For example, the insulating coating layer 26 may be formed on the entire core 20a and 20b. Alternatively, the insulating coating layer 26 may be formed on the bottom surface of the outer leg portions 22a and 22b. In this case, good insulation can be achieved between the bottom surface of the outer leg portions 22a and 22b and the mounting portions 34 and 35 of the first conductor 30. Furthermore, by forming the insulating coating layer 26 on the bottom surface of the base portions 21a and 21b, good insulation can be achieved between the bottom surface of the base portions 21a and 21b and the mounting surface of the mounting substrate.

[0241] As shown in Figure 29, the fifth embodiment may be applied to the second embodiment, and the coil device 110 (Figure 4A) in the second embodiment may be equipped with the resin spacer 90 shown in Figure 14A or the resin spacer 90' shown in Figure 32. The resin spacer 90' shown in Figure 32 differs from the resin spacer 90 shown in Figure 14 in that the lateral insulating portions 92a and 92b do not have inclined portions 95a and 95b formed thereon. As shown in Figure 31, the mounting bends 340 and 350 of the mounting portions 134 and 135 of the first conductor 130 are located adjacent to the lateral insulating portions 92a and 92b in the X-axis direction. However, since the inner side shape of the mounting bends 340 and 350 in the X-axis direction is vertical, the slanted portions 95a and 95b can be omitted from the lateral insulating portions 92a and 92b without interfering with (contacting) the mounting bends 340 and 350.

[0242] In the ninth embodiment described above, the lateral bends 48 and 49 may be omitted from the second conductor 840 shown in Figure 27. In this case, as shown in Figure 33A, the conductor sides 41 and 42 of the second conductor 840' will have a linear shape that extends linearly along the Z-axis direction. Therefore, as shown in Figure 33B, the lateral steps 920a and 920b shown in Figure 28 can be omitted from the resin spacer 890'. The lateral steps 920a and 920b are provided to accommodate the lateral bends 48 and 49, but the second conductor 840' shown in Figure 33A does not have the lateral bends 48 and 49, unlike the second conductor 840 shown in Figure 27. As shown in Figure 33A, the lower ends of the conductor sides 41 and 42 of the second conductor 840' protrude downward from the lower surface of the resin spacer 890'. The lateral bent portions 48 and 49 of the second conductor 840' can be connected to the land pattern of the mounting board with solder or the like via the protruding portions 41 and 42 of the conductor sides.

[0243] The 10th embodiment described above may be applied to the 2nd to 9th embodiments described above, and the coil devices in the 2nd to 9th embodiments may also be provided with a magnetic resin layer 200.

[0244] In the first embodiment described above, the tape member 60 shown in Figure 1C had characters (identifiers) such as a manufacturing number printed on it in advance. However, the tape member 60 may be a plain tape member without such characters printed on it. [Explanation of Symbols]

[0245] 10,110,210,310,410,510,610,710,810,910… Ill device 20a, 120a, 420a, 620a… 1st core 20b, 120b, 220b, 420b, 620b… Second core 21a, 621b... First base section 21b...Second base section 22a, 122a...first outer leg 22a1,122a1...first outer leg edge 22b...Second outer leg 22b1...Second outer leg edge portion 23a...First middle leg portion 23b...Second middle leg portion 24a...First groove portion 24b...Second groove portion 241...First side portion 242...Second side portion 243...Upper portion 25a...First side groove portion 25b...Second side groove portion 26...Insulating coating layer 27...Bottom surface recessed portion 27a,27b...Bottom surface protruding portions 28...Side surface recessed portion 28a...Arm installation portion 28b...Engagement recessed portion 30,130...First conductor 31,131...First conductor side portion 32,132...Second conductor side portion 33,133...Conductor upper portion 34,134...First mounting portion 340...First mounting bent portion 341...First mounting connection portion 343...First mounting main body portion 35,135...Second mounting portion 350...Second mounting bent portion 351...Second mounting connection portion 353...Second mounting main body portion 36,136...First outer notch portion 37,137...Second outer notch portion 38...First outer bent portion 39...Second outer bent portion 40,240,840,840’...Second conductor 41...First conductor side portion 42...Second conductor side portion 43...Conductor upper portion 44,244...First mounting portion 440,440’...Mounting opposing surface 441,441’...Bondable surface 442...Non-bonding surface 443...Rising portion 45,245...Second mounting portion 450,450'...Implementation opposite surface 451,451'…joinable surface 452…Non-bonded surface 453... Upright section 46...First inner bending part 47...Second inner bending part 48...First lateral bending part 49…Second lateral bending part 50… Mounting surface of the circuit board 60... Tape component 70…Insulating layer 80, 90, 590, 690, 790, 890, 890'... Resin spacers 91...Inner insulation 911a, 911b…Step surface 910a, 910b, 960a, 960b...Outside slope part 912a, 912b...Slope side part 913a, 913b… Spacer recess 92a, 92b... Side insulation 920a, 920b... Lateral step section 93a, 593a, 793a... First groove (first gap) 93b, 593b, 793b... Second groove (second gap) 94...Protruding part 94a, 94b…Bottom inclined part 95a, 95b…slanted part 96, 97… Connection part 96a... Notch 98...Bottom groove 99a, 99b... Arm section 990a, 990b... Arm body 991a, 991b... protruding part 100... Jig 110... Jig body 120...Conductor fixing part 130...Spacer insertion section 140...Conductor mounting section 200...Magnetic resin layer

Claims

1. The first conductor and, A second conductor is disposed inside the first conductor, and at least a portion of it extends along the first conductor. The device has a core in which the first conductor and the second conductor are disposed, At least an insulating layer is formed between the first conductor and the second conductor. The insulating layer consists of an insulating film formed on the surface of the second conductor. The insulating coating covers the outer circumferential surface, the inner circumferential surface, and the side surface connecting the outer circumferential surface and the inner circumferential surface of the second conductor. A gap of a predetermined length is provided between the insulating coating covering the outer surface of the second conductor and the inner surface of the first conductor, in the direction in which the outer surface of the second conductor and the inner surface of the first conductor face each other. The second conductor has a body portion that is bent in a U-shape, The gap is a coil device provided along the extending direction of the main body, from one end to the other end of the main body.

2. The coil device according to claim 1, wherein the second conductor is made of a flat rectangular wire.

3. The coil device according to claim 1 or 2, wherein the insulating coating covering the inner circumferential surface of the second conductor is formed between the core and the second conductor.

4. The coil device according to any one of claims 1 to 3, wherein the first conductor is a conductive plate having a plating layer formed on its surface.

5. The second conductor has a mounting-facing surface that can face the mounting surface, The mounting surface consists of a bondable surface on which the insulating layer is not formed and a non-bondable surface on which the insulating layer is formed. The coil device according to any one of claims 1 to 4, wherein the non-joining surface is formed in proximity to the first conductor compared to the joinable surface.

6. The coil device according to claim 5, wherein the bondable surface has a rising portion that is raised relative to the mounting surface.

7. The end of the first conductor has an outwardly bent portion formed therein. The end of the second conductor has an inwardly curved portion formed therein. The coil device according to any one of claims 1 to 6, wherein the radius of curvature of the inner surface of the outer bent portion is greater than the radius of curvature of the outer surface of the inner bent portion.

8. The coil device according to any one of claims 1 to 7, wherein the cross-sectional area of ​​the first conductor perpendicular to the extending direction is greater than the cross-sectional area of ​​the second conductor perpendicular to the extending direction.

9. The coil device according to any one of claims 1 to 8, wherein the bottom surface of the core is positioned at a distance from the mounting surface.

10. The coil device according to any one of claims 1 to 9, wherein an insulating coating layer is formed on at least the bottom surface of the core.

11. The coil device according to any one of claims 1 to 10, wherein the mounting portion of the first conductor and the mounting portion of the second conductor are insulated via a resin spacer.

12. The coil device according to any one of claims 1 to 11, wherein the insulating coating covering the outer surface of the second conductor and the inner surface of the first conductor are locally connected by an adhesive.

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