Coil device

Abstract

The invention provides a coil device with sufficiently large magnetic coupling. A coil device (10) includes a first conductor (30), a second conductor (40) disposed on an inner side of the first conductor (30) and at least a portion of which extends along the first conductor (30), and cores (20a, 20b) in which the first conductor (30) and the second conductor (40) are disposed. An insulating layer (70) is formed at least between the first conductor (30) and the second conductor (40).

Description

[0001] This application is filed on May 12, 2021 、Application No. 202110516234.1 、The name of the invention is Coil Pack Place A divisional application for a patent application. Technical Field

[0002] The present invention relates to a coil device for use as, for example, an inductor or the like. Background Art

[0003] As a coil device used as an inductor, for example, there is known a coil device described in Patent Document 1. The coil device described in Patent Document 1 has two conductors and a core in which the two conductors are arranged. In the coil device described in Patent Document 1, the magnetic coupling between the two conductors can be increased by forming a region where no magnetic body is arranged between the two conductors.

[0004] However, in the coil device described in Patent Document 1, it is difficult to make the magnetic coupling between the two conductors sufficiently large due to its structure, and a technology that can make the magnetic coupling between the conductors sufficiently large is required.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2007-184509 Summary of the invention

[0008] Problems to be solved by the invention

[0009] The present invention has been made in view of such actual conditions, and an object of the present invention is to provide a coil device having sufficiently large magnetic coupling.

[0010] Technical solutions to solve problems

[0011] In order to achieve the above object, the present invention provides a coil device having:

[0012] a first conductor;

[0013] a second conductor disposed inside the first conductor and at least a portion of which extends along the first conductor; and

[0014] a core, within which the first conductor and the second conductor are internally arranged,

[0015] An insulating layer is formed at least between the first conductor and the second conductor.

[0016] The coil device of the present invention has a first conductor, and a second conductor arranged inside the first conductor and at least partially extending along the first conductor, and an insulating layer is formed at least between the first conductor and the second conductor. In this case, the first conductor and the second conductor are arranged to overlap (double layer) at a predetermined interval, but in this configuration, the 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 fully increased. In addition, the first conductor and the second conductor are fully insulated by the insulating layer interposed therebetween, so that a short circuit defect between the first conductor and the second conductor can be prevented, and a highly reliable coil device can be realized.

[0017] Preferably, the second conductor is formed of a flat wire, and the insulating layer is formed of an insulating film formed on the surface of the second conductor. In this way, by using a flat wire with an insulating film as the second conductor, the insulating layer can be interposed between the first conductor and the second conductor simply by arranging the second conductor to overlap the inner side of the first conductor, and the above-mentioned effect can be easily achieved.

[0018] 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 such a structure, the insulating layer formed by the fusion layer can be filled without gaps between the first conductor and the second conductor, and the insulation between the first conductor and the second conductor can be fully ensured.

[0019] Preferably, the insulating layer is formed between the core and the first conductor or the second conductor. By setting such a structure, the core and the first conductor or the second conductor are fully insulated via the insulating layer interposed therebetween, thereby preventing a short circuit defect between the core and the first conductor or the second conductor, and realizing a highly reliable coil device.

[0020] Preferably, the first conductor is formed of a conductor plate having a plated layer formed on the surface. With such a structure, it is easy to attach a bonding member such as solder or a conductive adhesive 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 member, a solder fillet can be easily formed on the side surface of the first conductor, thereby making it possible to firmly connect the first conductor to the mounting surface of the mounting substrate.

[0021] Preferably, the second conductor has a mounting opposite surface that can be opposite to the mounting surface, and the mounting opposite surface is composed of a bondable surface on which the insulating layer is not formed, and a non-bonding surface on which the insulating layer is formed, and the non-bonding surface is formed closer to the first conductor than the bondable surface. In this case, it is easy to attach the above-mentioned bonding member to the bondable surface, but it is not easy to attach the bonding member to the non-bonding surface. Therefore, the bonding member attached to the bondable surface can be prevented from being exposed toward the first conductor by the non-bonding surface, and a short circuit defect between the first conductor and the second conductor can be effectively prevented.

[0022] Preferably, the bondable surface has a rising portion that rises relative to the mounting surface. By setting such a structure, not only can the bonding member be attached to the surface opposite to the mounting surface of the mounting substrate, but the bonding member can also be attached to the rising portion. Therefore, when solder is used as the bonding member, a solder fillet can be formed on the rising portion of the bondable surface, and the second conductor can be firmly connected to the mounting surface of the mounting substrate. In addition, by setting the above structure, it is possible to prevent, for example, a solder ball from being formed on the mounting portion of the second conductor.

[0023] Preferably, an outer curved portion that curves toward the outside is formed at the end of the first conductor, and an inner curved portion that curves toward the inside is formed at the end of the second conductor, and the curvature radius of the inner surface of the outer curved portion is greater than the curvature radius of the outer surface of the inner curved portion. In this case, the bending angle of the inner surface of the outer curved portion (the portion of the inner surface of the first conductor where the outer curved portion is located) is smaller than the bending angle of the outer surface of the inner curved portion (the portion of the outer surface of the second conductor where the inner curved portion is located). Therefore, the outer surface of the inner curved portion is sharply curved near the mounting surface of the mounting substrate, while the inner surface of the outer curved portion is gently curved from a position away from the mounting surface of the mounting substrate. Therefore, a large space is formed between the inner surface of the outer curved portion and the outer surface of the inner curved portion, and a short circuit defect between the first conductor and the second conductor can be effectively prevented around the mounting surface of the mounting substrate.

[0024] Preferably, the cross-sectional area of ​​the first conductor perpendicular to the extension direction is larger than the cross-sectional area of ​​the second conductor perpendicular to the extension direction. By setting such a structure, the DC resistance of the first conductor can be made smaller than the DC resistance of the second conductor.

[0025] Preferably, the bottom surface of the core is arranged at a position away from the mounting surface. By setting such a structure, the insulation between the bottom surface of the core and the mounting surface of the mounting substrate can be fully ensured, and in particular, when the core is composed of a metal magnetic body, etc., a short circuit defect between the bottom surface of the core and the mounting surface of the mounting substrate can be effectively prevented.

[0026] Preferably, an insulating coating layer is formed at least on the bottom surface of the core. With such a structure, the insulation between the bottom surface of the core and the second conductor (or the first conductor) or the insulation between the bottom surface of the core and the mounting surface of the mounting substrate can be fully ensured through the insulating coating layer.

[0027] Preferably, the mounting portion of the first conductor and the mounting portion of the second conductor are insulated via a resin spacer. By setting such a structure, it is possible to effectively prevent a short circuit defect from occurring between the first mounting portion and the second mounting portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1A It is a perspective view of the coil device according to the first embodiment of the present invention.

[0029] Figure 1B yes Figure 1A A top view of the coil arrangement is shown.

[0030] Figure 1C is Figure 1A A top view of the coil device with the tape member attached thereto is shown.

[0031] Figure 2 yes Figure 1A An exploded perspective view of the coil device shown.

[0032] Figure 3 yes Figure 1A A cross-sectional view of the coil arrangement along line III-III is shown.

[0033] Figure 4A It is a perspective view of a coil device according to a second embodiment of the present invention.

[0034] Figure 4B yes Figure 4A A top view of the coil arrangement is shown.

[0035] Figure 5 yes Figure 4A An exploded perspective view of the coil device shown.

[0036] Figure 6 yes Figure 4A A cross-sectional view of the coil arrangement along line VI-VI is shown.

[0037] Figure 7 It is a perspective view of a coil device according to a third embodiment of the present invention.

[0038] Figure 8 yes Figure 7 An exploded perspective view of the coil device shown.

[0039] Fig. 9 yes Figure 7A cross-sectional view of the coil arrangement along line VII-VII is shown.

[0040] Fig.10 It is a perspective view of a coil device according to a fourth embodiment of the present invention.

[0041] Fig.11 yes Fig.10 A perspective view of the resin spacer shown.

[0042] Fig.12 is Fig.11 A perspective view of a resin spacer shown when a second conductor is mounted on the resin spacer. DETAILED DESCRIPTION

[0043] Hereinafter, the present invention will be described based on the embodiments shown in the drawings.

[0044] First embodiment

[0045] like Figure 1A As shown, the coil device 10 of the first embodiment of the present invention is formed in a substantially rectangular parallelepiped shape and functions as a coupling coil for a power supply circuit, etc. 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.

[0046] like Figure 2 As shown, the coil device 10 includes a first core 20a, a second core 20b, a first conductor 30, and a second conductor 40. One of the first conductor 30 and the second conductor 40 functions as a primary coil, and the other functions as a secondary coil. The conductors 30 and 40 will be described in detail later.

[0047] The first core 20a and the second core 20b have the same shape, respectively, and are formed in a so-called E-shape. The first core 20a and the second core 20b are arranged in a manner opposite to each other in the Y-axis direction and are bonded using an adhesive or the like. The first core 20a and the second core 20b are formed of a magnetic body, for example, by molding and sintering a magnetic material with a high magnetic permeability, such as a magnetic powder composed of Ni-Zn ferrite, Mn-Zn ferrite, or a metal magnetic body.

[0048] The first core 20a includes a first base portion 21a, a pair of first outer legs 22a, 22a, a first middle leg portion 23a disposed between the pair of first outer legs 22a, 22a, a first groove portion 24a, and first side groove portions 25a, 25a. The first base portion 21a is formed in a substantially flat plate shape (substantially rectangular parallelepiped shape).

[0049] A pair of first outer leg portions 22a, 22a are formed at predetermined intervals along the X-axis direction at the ends of the first base portion 21a on one side and the other side in the X-axis direction, respectively. The first outer leg portions 22a, 22a protrude from the surface of the first base portion 21a on one side in the Y-axis direction toward the one side in the Y-axis direction by a predetermined length. The first outer leg portions 22a, 22a each have an elongated shape in the Z-axis direction, and extend from the upper end to the lower end of the first base portion 21a in the Z-axis direction.

[0050] The first middle leg portion 23a is formed at the approximate center of the first base portion 21a in the X-axis direction. The first middle leg portion 23a protrudes from the surface of one side of the first base portion 21a in the Y-axis direction toward one side of the Y-axis direction by a predetermined length. The first middle leg portion 23a has an elongated shape in the Z-axis direction, and extends from the upper part of the first base portion 21a in the Z-axis direction to the lower end. The protruding width of the first middle leg portion 23a in the Y-axis direction is approximately equal to the protruding width of the first outer leg portion 22a in the Y-axis direction. In the example shown in the figure, the width of the first middle leg portion 23a in the X-axis direction is greater than the width of the first outer leg portion 22a in the X-axis direction, and is approximately 2 to 3 times the width of the first outer leg portion 22a in the X-axis direction.

[0051] like Figure 3 As shown, the surface of the first middle leg portion 23a facing the mounting surface 50 of the mounting substrate is subjected to insulation coating to form an insulation coating layer 26. The insulation coating layer 26 is made of a resin material such as epoxy resin or polyurethane resin. The thickness of the insulation coating layer 26 is preferably 1 to 200 μm. In addition, the insulation coating layer 26 is also formed on the bottom surface of the second middle leg portion 23b of the second core 20b.

[0052] like Figure 2 As shown, the first groove portion 24a has a shape (roughly a U-shape) corresponding to the shape of the first conductor 30, and extends along the periphery of the first middle leg portion 23a. Inside the first groove portion 24a, the first conductor 30 and the second conductor 40 can be arranged in an overlapping manner. The first groove portion 24a has a first side portion 241, a second side portion 242, and an upper portion 243.

[0053] The first lateral portion 241 and the second lateral portion 242 extend in a substantially straight line along the Z-axis direction, respectively, extending from the upper end portion of the first base portion 21a in the Z-axis direction to the lower end portion. 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 of 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 of 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 thicknesses (plate thicknesses) of each of the conductors 30 and 40. As described later, the conductor side portions 31 and 41 of the conductors 30 and 40 are arranged in the first lateral portion 241, and the conductor side portions 32 and 42 of the conductors 30 and 40 are arranged in the second lateral portion 242.

[0054] 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 side portion 241 and the upper end of the second side portion 242. The Z-axis direction width of the upper portion 243 is greater than the sum of the thicknesses (plate thicknesses) of the conductors 30 and 40. As described later, the conductor upper portions 33 and 43 of the conductors 30 and 40 are arranged on the upper portion 243.

[0055] A pair of first side grooves 25a, 25a are respectively formed below the first outer leg portions 22a, 22a located on one side and the other side in the X-axis direction, and extend along the X-axis direction toward one end side and the other end side of the first base portion 21a in the X-axis direction. The first side grooves 25a, 25a are respectively connected to the lower ends of the side portions 241, 242, and a substantially L-shaped groove portion is formed by the side portions 241, 242 and the first side grooves 25a, 25a. The width of each of the first side grooves 25a, 25a in the Z-axis direction is the same as the thickness (plate thickness) of the first conductor 30, or is greater than the thickness (plate thickness) of the first conductor 30. As described later, the mounting portions 34, 35 of the first conductor 30 are respectively arranged in the first side grooves 25a, 25a.

[0056] The second core 20b includes a second base portion 21b, a pair of second outer leg portions 22b, 22b, and a second middle leg portion 23b ( Figure 1B ) and the second groove 24b, and the second lateral grooves 25b, 25b. The second outer legs 22b, 22b are arranged opposite to the first outer legs 22a, 22a, and the second middle legs 23b are arranged opposite to the first middle legs 23a. Since the shape of the second core 20b is the same as that of the first core 20a, the description of the shapes of the above-mentioned parts of the second core 20b is omitted.

[0057] like Figure 1BAs shown, the combination of the first core 20a and the second core 20b can be performed by bonding a surface of one side of the first core 20a located on the opposite side of the Y-axis direction of the first base portion 21a to a surface of one side of the second core 20b located on the opposite side of the Y-axis direction of 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 bonded to each other and / or the middle leg portions 23a, 23b are bonded to each other.

[0058] If the first core 20a and the second core 20b are placed opposite to each other and combined along the Y-axis direction, gaps G1 and G2 having a specified width in the Y-axis direction are formed between the first core 20a and the second core 20b at the positions where the outer legs 22a and 22b are formed, and a gap G3 having a specified width in the Y-axis direction is formed at the positions where the middle legs 23a and 23b are formed.

[0059] The 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 located on one side in the X-axis direction. The 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 located on the other side in the X-axis direction. The lengths of the gaps G1 and G2 in the X-axis direction are equal to the lengths of the outer legs 22a and 22b in the X-axis direction. In addition, the gaps G1 and G2 also have a predetermined length in the Z-axis direction, and their lengths are equal to the lengths of the outer legs 22a and 22b in the Z-axis direction.

[0060] The gap G3 has a predetermined length in the X-axis direction and is formed between the first middle leg portion 23a and the second middle leg portion 23b. The length of the gap G3 in the X-axis direction is equal to the length of the middle legs 23a and 23b in the X-axis direction. In the example shown in the figure, the length of the gap G3 in the X-axis direction is longer than the length of the gaps G1 and G2 in the X-axis direction. In addition, the gap G3 also has a predetermined length in the Z-axis direction, and its length is equal to the length of the first middle legs 23a and 23b in the Z-axis direction. The gaps G1 to G3 are formed in the same straight line along the boundary between the first core 20a and the second core 20b.

[0061] The Y-axis width W1 of the 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 the gaps G2 and G3. In addition, the Y-axis widths of the gaps G1 to G3 may be different from each other.

[0062] like Figure 2As shown, the first conductor 30 is composed of a conductor plate and has a bent shape (roughly a U-shape). The first conductor 30 is disposed between the first core 20a and the second core 20b together with the second conductor 40. As a material constituting the first conductor 30, good conductors such as copper and copper alloys, silver, nickel and the like can be cited, but there is no particular limitation as long as it is a conductor material. The first conductor 30 is formed by machining a metal plate, for example, but the method of forming the first conductor 30 is not limited thereto.

[0063] In the example shown in the figure, the first conductor 30 has a longitudinal shape as a whole, and the height of the first conductor 30 in the Z-axis direction is greater than the width thereof in the X-axis direction. The cross-sectional area perpendicular to the extension direction of the first conductor 30 is greater than the cross-sectional area perpendicular to the extension direction of the second conductor 40. In addition, 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 substantially equal to the width of the second conductor 40 in the Y-axis direction.

[0064] A plating layer is formed on the entire surface of the first conductor 30. The plating layer is composed of a single layer or a plurality of layers, for example, a metal plating layer such as Cu plating, Ni plating, Sn plating, Ni-Sn plating, Cu-Ni-Sn plating, Ni-Au plating, Au plating, etc. The plating layer is formed by performing, for example, electroplating or electroless plating on the surface of the first conductor 30. The thickness of the plating layer is not particularly limited, but is preferably 1 to 30 μm.

[0065] The first conductor 30 includes a first conductor side portion 31, a second conductor side portion 32, a conductor upper portion 33, a first mounting portion 34, and a second mounting portion 35. The first conductor side portion 31 and the second conductor side portion 32 extend in the Z-axis direction, respectively. In the first conductor 30, the side where the first conductor side portion 31 is arranged functions as an input terminal (or output terminal), and the side where the second conductor side portion 32 is arranged functions as an output terminal (or input terminal). The conductor upper portion 33 extends in the X-axis direction and connects the first conductor side portion 31 and the second conductor side portion 32, respectively.

[0066] The first mounting portion 34 and the second mounting portion 35 are respectively formed continuously (integrally) at one end and the other end of the first conductor 30, that is, at the lower end of the first conductor side portion 31 and the second conductor side portion 32. The mounting portions 34 and 35 are bent in a substantially perpendicular direction relative 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 ( Figure 3 The first conductor 30 is joined to the mounting surface 50 via a joining member such as solder or a conductive adhesive.

[0067] like Figure 1A As shown in FIG. 1 , the ends (end faces) of the mounting portions 34 and 35 are exposed to the outside from the sides of the first core 20a and the second core 20b in the X-axis direction. Figure 3 As shown, 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. Thus, by exposing the mounting portions 34 and 35 to the outside, the heat generated around the mounting portions 34 and 35 can be efficiently released to the outside of the cores 20a and 20b.

[0068] A first outer bent portion 38 bent toward the outside in the X-axis direction (opposite to the side on which the second conductor 40 is arranged) is formed near the boundary between the first conductor side portion 31 and the first mounting portion 34, and a second outer bent portion 39 bent toward the outside in the X-axis direction is formed near the boundary between the second conductor side portion 32 and the second mounting portion 35.

[0069] like Figure 1B and Figure 2 As shown, a first outer cutout portion 36 and a second outer cutout portion 37 are formed on the outer surface of the first conductor 30. The first outer cutout portion 36 is formed on the surface of the first conductor side portion 31 and the first mounting portion 34, and extends along the extension direction (longitudinal direction) of the first conductor side portion 31 and the first mounting portion 34. The first outer cutout portion 36 is composed of a groove, and a tapered surface is formed on the inner side thereof. The shape of the first outer cutout portion 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 cutout portion 36 is formed at the approximate 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.

[0070] The second outer cutout portion 37 is formed on the surface of the second conductor side portion 32 and the second mounting portion 35, and extends along the extension direction (longitudinal direction) of the second conductor side portion 32 and the second mounting portion 35. The second outer cutout portion 37 is composed of a groove, and a tapered surface is formed inside the groove. The shape of the second outer cutout portion 37 is equal to the shape formed by the second conductor side portion 32 and the second mounting portion 35, and is substantially L-shaped. The second outer cutout portion 37 is formed at the substantially central portion 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.

[0071] The outer cutouts 36 and 37 are formed in the first conductor 30 at positions corresponding to the gaps G1 and G2 (positions close to the gaps G1 and G2). More specifically, the outer cutouts 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 edge portions 22a1 and 22b1 of the outer leg portions 22a and 22b adjacent to the first conductor 30. In addition, the outer cutouts 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.

[0072] The first outer cutout portion 36 is opposed to (faces) the other end side of the gap G1 in the X-axis direction, and at a position corresponding to the gap G1, the surface of the first conductor 30 and the other end side of the gap G1 in the X-axis direction are separated by a distance corresponding to the depth D of the first outer cutout portion 36. The second outer cutout portion 37 is opposed to (faces) one end side of the gap G2 in the X-axis direction, and at a position corresponding to the gap G2, the surface of the first conductor 30 and the one end side of the gap G2 in the X-axis direction are separated by a distance corresponding to the depth of the second outer cutout portion 37.

[0073] The width of the outer cutouts 36 and 37 in the Y-axis direction is greater than the width of the gaps G1 and G2 in the Y-axis direction. The ratio W2 / W1 of the width W2 of the first outer cutout 36 in the Y-axis direction to the width W1 of the gap G1 in the Y-axis direction is preferably 0.5 to 10, more preferably 1 to 7, and particularly preferably 3 to 5. The ratio of the width of the second outer cutout 37 in the Y-axis direction to the width of the gap G2 in the Y-axis direction is the same.

[0074] The ratio W2 / W3 of the width W2 of the first outer cutout 36 in the Y-axis direction to the width W3 of the first conductor 30 in the Y-axis direction is preferably 0.2 to 0.8, more preferably 0.3 to 0.5. The same applies to the ratio of the width W2 of the second outer cutout 37 in the Y-axis direction to the width W3 of the first conductor 30 in the Y-axis direction.

[0075] The ratio D / T1 of the depth D of the first outer cutout 36 to the thickness T1 of the first conductor 30 is preferably 0.1 to 0.5, more preferably 0.2 to 0.4. The same applies to the ratio of the depth D of the second outer cutout 37 to the thickness T1 of the first conductor 30.

[0076] The relationship between the depth D of the first outer cutout 36 and the width W1 of the gap G1 in the Y-axis direction is preferably D>W1, but is not limited thereto. The ratio D / W1 of the depth D to the width W1 is preferably 0.5 to 5, more preferably 1 to 3. The relationship between the depth of the second outer cutout 37 and the width of the gap G2 in the Y-axis direction is the same.

[0077] 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 the gaps G1 and G2 from contacting the conductor side portions 31 and 32 and the mounting portions 34 and 35 at the positions corresponding to the gaps G1 and G2.

[0078] like Figure 2 As shown, the second conductor 40 is made of a flat wire and has a bent shape (roughly a U-shape). The second conductor 40 can be made of the same material as the first conductor 30. The second conductor 40 is arranged inside the cores 20a and 20b (inside the grooves 24a and 24b) together with the first conductor 30. When the conductors 30 and 40 are arranged inside the grooves 24a and 24b, the second conductor 40 is arranged at a predetermined interval inside the first conductor 30, the middle leg portions 23a and 23b are arranged inside the second conductor 40, and the outer leg portions 22a and 22b are arranged outside the first conductor 30.

[0079] In the example shown in the figure, the second conductor 40 has a vertically long shape, and its height in the Z-axis direction is longer than its length in the X-axis direction. The second conductor 40 is smaller than the first conductor 30 and is surrounded by the first conductor 30 when the second conductor 40 is arranged.

[0080] The second conductor 40 includes a first conductor side portion 41, a second conductor side portion 42, a conductor upper portion 43, a first mounting portion 44, and a second mounting portion 45. The first conductor side portion 41 and the second conductor side portion 42 extend along the Z-axis direction and are arranged opposite to each other in the X-axis direction. The side of the second conductor 40 where the first conductor side portion 41 is arranged functions as an input terminal (or output terminal), and the side where the second conductor side portion 42 is arranged functions as an output terminal (or input terminal).

[0081] The first conductor side portion 41 of the second conductor 40 extends substantially in parallel along 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 in parallel along the second conductor side portion 32 of the first conductor 30 .

[0082] The conductor upper 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. The conductor upper portion 43 of the second conductor 40 extends substantially parallel to the conductor upper portion 33 of the first conductor 30.

[0083] The first mounting portion 44 and the second mounting portion 45 are respectively formed continuously (integrally) at one end and the other end of the second conductor 40 , that is, at the lower ends of the first conductor side portion 41 and the second conductor side portion 42 .

[0084] The mounting portions 44 and 45 are bent in a substantially perpendicular direction relative to the conductor side portions 41 and 42 and extend inward in the X-axis direction. Figure 3 As shown, the mounting portions 44, 45 extend along the bottom surfaces of the middle legs 23a, 23b, and a gap of a predetermined width is formed between the upper surfaces of the mounting portions 44, 45 and the bottom surfaces of the middle legs 23a, 23b. In addition, as described above, the insulating coating layer 26 is formed on the bottom surfaces of the middle legs 23a, 23b, so that the middle legs 23a, 23b and the mounting portions 44, 45 are well insulated.

[0085] The first mounting portion 44 of the second conductor 40 extends in the opposite direction to the first mounting portion 34 of the first conductor 30 with respect to the X-axis direction. In addition, the second mounting portion 45 of the second conductor 40 extends in the opposite direction to the second mounting portion 35 of the first conductor 30 with respect to the X-axis direction.

[0086] The second conductor 40 can be connected to the mounting surface 50 of the mounting substrate via the mounting portions 44 and 45. The second conductor 40 is joined to the mounting surface 50 via a joining member such as solder or a conductive adhesive.

[0087] The lower surfaces of the mounting portions 44 and 45 are exposed to the outside from below the first core 20a and the second core 20b. Thus, by exposing the mounting portions 44 and 45 to the outside, the heat generated around the mounting portions 44 and 45 can be efficiently released to the outside of the cores 20a and 20b.

[0088] The mounting portions 44 and 45 have mounting opposing surfaces 440 and 450 that can be opposed to the mounting surface 50 of the mounting substrate. The mounting opposing surfaces 440 and 450 are surfaces connected to the mounting surface 50. The details of the mounting opposing surfaces 440 and 450 will be described later.

[0089] 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 of insulating the first conductor 30 and the second conductor 40 well. The insulating layer 70 of this embodiment is composed of an insulating film formed on the surface of the second conductor 40, and is formed integrally with the second conductor 40. In the example shown in the figure, 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.

[0090] Various forms of the insulating layer 70 are conceivable. For example, the insulating layer 70 may be formed of a fusion layer formed by fusion-bonding the 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 fusion layer (insulating layer 70), and the insulating layer 70 can be filled in the gap between the first conductor 30 and the second conductor 40 without a gap, so that the insulation between the first conductor 30 and the second conductor 40 can be fully ensured. In addition, by connecting the first conductor 30 and the second conductor 40 via the insulating layer 70, the effect of improving the magnetic coupling between the first conductor 30 and the second conductor 40 can be achieved.

[0091] The welding layer can be formed by heating the insulating film formed on the surface of the second conductor 40. In addition, the welding layer can also be composed of an insulating film different from the insulating film formed on the surface of the second conductor 40. For example, the insulating film and the welding layer can also be formed on the surface of the second conductor 40 in two layers.

[0092] In addition, for example, the insulating layer 70 may be formed of a resin body (a resin body such as a resin spacer) that is formed separately from the second conductor 40. In this case, by setting the shape of the resin body to a curved shape corresponding to the shape of the gap (approximately U-shaped) between the first conductor 30 and the second conductor 40, the insulating layer 70 can be formed along the outer surface of the second conductor 40 and the inner surface of the first conductor 30.

[0093] like Figure 2 As shown, the insulating layer 70 covers the entire surface of the second conductor 40 (except for the bonding surfaces 441 and 451 of the mounting opposing surfaces 440 and 450 described later). The range in which the insulating layer 70 is formed is not limited to the range shown in the figure, and the insulating layer 70 is at least formed at a position where the inner surface of the first conductor 30 and the outer surface of the second conductor 40 are opposite.

[0094] like Figure 3 As shown in FIG. 1 , 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 composed of an insulating film formed on the surface of the second conductor 40, the thickness is preferably 1 to 200 μm, and more preferably 1 to 100 μm. In addition, for example, when the insulating layer 70 is composed of a resin body formed separately from the second conductor 40, the thickness of the insulating layer 70 may be thicker than the above-mentioned thickness.

[0095] 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.

[0096] The insulating layer 70 covers the outer surface, inner surface, and side surfaces orthogonal to the outer surface and inner surface of the conductor side portions 41, 42 and the conductor upper portion 43. By forming the insulating layer 70 on the inner surface of the conductor side portions 41, 42 and the conductor upper portion 43, the second conductor 40 and the middle legs 23a, 23b of the cores 20a, 20b can be well insulated.

[0097] Between the second conductor 40 and the middle legs 23a, 23b of the cores 20a, 20b, the insulating layer 70 is formed integrally 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 insulating layer 70 formed between the second conductor 40 and the middle legs 23a, 23b of the cores 20a, 20b is formed in the same manner as the insulating layer 70 formed between the first conductor 30 and the second conductor 40 described above.

[0098] In addition, the insulating layer 70 covers the entire inner surface, side surface, and end surface (each end surface of the second conductor 40 ) of the mounting portions 44 , 45 , but only partially covers the outer surface (mounting opposing surfaces 440 , 450 ).

[0099] In more detail, the mounting opposite surfaces 440 and 450 include bondable surfaces 441 and 451 on which the insulating layer 70 is not formed, and non-bonding 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, conductivity is imparted to the bondable surfaces 441 and 451, and the bondable surfaces 441 and 451 and the mounting surface 50 of the mounting substrate can be connected via a bonding member such as solder.

[0100] The bondable surfaces 441, 451 are formed from the substantially central portion of the mounting portions 44, 45 in the X-axis direction to the front end portions (each end portion of the second conductor 40) of the mounting portions 44, 45. The non-bonding surfaces 442, 452 are formed from the base end portions (the connection portions with the conductor side portions 41, 42) of the mounting portions 44, 45 to the substantially central portion of the mounting portions 44, 45 in the X-axis direction. Therefore, in the present embodiment, the non-bonding surfaces 442, 452 are formed closer to the first conductor 30 than the bondable surfaces 441, 451.

[0101] Thus, in this embodiment, the insulating layer 70 is formed on the entire inner surface of the second conductor 40 along the longitudinal direction thereof, whereas on the outer surface of the second conductor 40 , there are regions where the insulating layer 70 is not formed only at the two ends in the longitudinal direction thereof.

[0102] like Figure 2As shown, a first inner curved portion 46 curved toward the inner side in the X-axis direction (the side opposite to the side where the first conductor 30 is arranged) is formed near the boundary between the first conductor side portion 41 and the first mounting portion 44, and a second inner curved portion 47 curved toward the inner side in the X-axis direction is formed near the boundary between the second conductor side portion 42 and the second mounting portion 45. The curvature radius of the outer surface of the inner curved portions 46 and 47 of the second conductor 40 is smaller than the curvature radius of the inner surface of the outer curved portions 38 and 39 of the first conductor 30.

[0103] In the manufacture of the coil device 10, the Figure 2 The first core 20a, the second core 20b, the first conductor 30, and the second conductor 40 are shown. As the second conductor 40, for example, a rectangular wire having an insulating film (insulating layer 70) formed on the surface thereof is prepared by machining. Figure 2 In addition, this type of rectangular wire with an insulating coating can be formed by dipping a metal plate into a resin solution, for example.

[0104] The mounting opposite surfaces 440 and 450 of the second conductor 40 form bondable surfaces 441 and 451 on which the insulating layer 70 is not formed. The bondable surfaces 441 and 451 are formed by subjecting the above-mentioned flat wire to laser irradiation at the position where the bondable surfaces 441 and 451 are to be formed, and peeling off the insulating layer 70 from the mounting opposite surfaces 440 and 450. In addition, the stripping of the insulating layer 70 can also be performed by scraping off the surface of the flat wire with a file or the like. Preferably, solder is attached to the peeled portion of the insulating layer 70 by dip soldering or the like. In this way, the solder wettability of the bondable surfaces 441 and 451 can be improved. In addition, the formation of the bondable surfaces 441 and 451 can be performed when the flat wire is processed into Figure 2 It can be done before the shape shown, or after processing.

[0105] Next, the first conductor 30 and the second conductor 40 are arranged in an overlapping manner inside the first groove 24a (second groove 24b) of the first core 20a (second core 20b). More specifically, the second conductor 40 is arranged so as to surround the first middle leg 23a (second middle leg 23b), and then the first conductor 30 is arranged 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 by an adhesive or the like.

[0106] In addition, a member in which the inner surface of the first conductor 30 and the outer surface of the second conductor 40 are joined via the insulating layer 70 (welding layer) may be arranged inside the first groove 24a (second groove 24b) of the first core 20a (second core 20b) in advance. In this way, by integrating the first conductor 30 and the second conductor 40 in advance via the insulating layer 70, it is easy to arrange the first core 20a (second core 20b) inside the first groove 24a (second groove 24b).

[0107] Next, the second core 20 b (first core 20 a ) is combined with the first core 20 a (second core 20 b ) so that the first conductor 30 and the second conductor 40 are housed in the second groove 24 b (first groove 24 a ).

[0108] At this time, if Figure 1B As shown, the first core 20a and the second core 20b are combined with a prescribed interval set along the Y-axis direction in such a manner that a gap G1 is formed between the first outer leg 22a and the second outer leg 22b on one side of the X-axis direction, a gap G2 is formed between the first outer leg 22a and the second outer leg 22b on the other side of the X-axis direction, and a gap G3 is formed between the first middle leg 23a and the second middle leg 23b.

[0109] Thus, the outer cutouts 36 and 37 are arranged to face the gaps G1 and G2, and the outer curved portions 38 and 39 are arranged to face the gap G3. Then, the first core 20a and the second core 20b are bonded together using an adhesive or the like to obtain a Figure 1A The coil arrangement 10 is shown.

[0110] Afterwards, if Figure 1C As shown, a tape member 60 may be attached to the upper surface of the core 20a, 20b, and characters such as a production number (identification code / characters such as "R15" in the illustrated example) may be printed on the surface of the tape member 60. Alternatively, a tape member 60 pre-printed with characters such as a production number (identification code) may be attached to the upper surface of the core 20a, 20b. The tape member 60 is, for example, a polyimide tape (Kapton tape) and is attached across the cores 20a, 20b. The printing of characters on the tape member 60 is performed by laser irradiation or the like. In addition, currently, characters are engraved on the upper surface of the core by laser irradiation, and the tape member is attached in a manner covering the characters from above, but in this case, there is a problem that the characters engraved on the upper surface of the core are difficult to recognize. As in the present embodiment, by printing characters on the tape member attached to the upper surface of the core, or by printing characters on the tape member attached to the upper surface of the core, the characters can be clearly recognized, and the above-mentioned problems can be effectively prevented.

[0111] As mentioned above, Figure 2 and Figure 3 As shown, the coil device 10 of the present embodiment includes a first conductor 30 and a second conductor 40 arranged inside the first conductor 30 and at least a portion (conductor side portions 41, 42 and conductor upper portion 43) extending along the first conductor 30 (conductor side portions 31, 32 and conductor upper portion 33), and an insulating layer 70 is formed at least between the first conductor 30 and the second conductor 40. In this case, the first conductor 30 and the second conductor 40 are arranged to overlap (double layer) with a predetermined interval, and in this arrangement, the 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 sufficiently increased. In addition, the first conductor 30 and the second conductor 40 are sufficiently insulated with the insulating layer 70 interposed therebetween, so that the short circuit defect between the first conductor 30 and the second conductor 40 can be prevented, and the coil device 10 with high reliability can be realized.

[0112] In addition, the second conductor 40 of the present embodiment is composed of a flat wire, and the insulating layer 70 is composed of an insulating film formed on the surface of the second conductor 40. In this way, by using a flat wire with an insulating film as the second conductor 40, the insulating layer 70 can be interposed between the first conductor 30 and the second conductor 40 simply by arranging the second conductor 40 to overlap the inner side of the first conductor 30, and the above-mentioned effect can be easily achieved.

[0113] In addition, in the present embodiment, the insulating layer 70 is formed between the middle legs 23a, 23b of the cores 20a, 20b and the second conductor 40. Therefore, since the middle legs 23a, 23b and the second conductor 40 are sufficiently insulated via the insulating layer 70 interposed therebetween, a short circuit defect between the middle legs 23a, 23b and the second conductor 40 can be prevented, and a highly reliable coil device 10 can be realized.

[0114] In addition, the first conductor 30 of the present embodiment is composed of a conductor plate having a plated layer formed on the surface. Therefore, it is easy to attach a bonding member such as solder or a conductive adhesive 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 member, solder fillets can be easily formed on the side surfaces of the first conductor 30, thereby making it possible to firmly connect the first conductor 30 and the mounting surface 50 of the mounting substrate.

[0115] In addition, in the present embodiment, the mounting opposing surfaces 440, 450 include the bondable surfaces 441, 451 on which the insulating layer 70 is not formed, and the non-bonding surfaces 442, 452 on which the insulating layer 70 is formed, and the non-bonding surfaces 442, 452 are formed closer to the first conductor 30 than the bondable surfaces 441, 451. In this case, it is easy to attach the above-mentioned bonding member to the bondable surfaces 441, 451, but it is not easy to attach the bonding member to the non-bonding surfaces 442, 452. Therefore, the bonding member attached to the bondable surfaces 441, 451 can be prevented from being exposed toward the first conductor 30 by the non-bonding surfaces 442, 452, and the short circuit defect caused by the solder ball or the like between the first conductor 30 and the second conductor 40 can be effectively prevented.

[0116] In addition, in the present embodiment, the curvature radius of the inner surface of the outer curved portions 38 and 39 is larger than the curvature radius of the outer surface of the inner curved portions 46 and 47 of the second conductor 40. In this case, the curvature angle of the inner surface of the outer curved portions 38 and 39 is smaller than the curvature angle of the outer surface of the inner curved portions 46 and 47. Therefore, the outer surface of the inner curved portions 46 and 47 is sharply curved near the mounting surface 50 of the mounting substrate, while the inner surface of the outer curved portions 38 and 39 is gently curved from a position away from the mounting surface 50 of the mounting substrate. Therefore, a large space is formed between the inner surface of the outer curved portions 38 and 39 and the outer surface of the inner curved portions 46 and 47, and the occurrence of a short circuit defect between the first conductor 30 and the second conductor 40 can be effectively prevented around the mounting surface 50. In addition, 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, the mounting portions 34 and 35 of the first conductor 30 can be prevented from contacting the land pattern.

[0117] In addition, in this embodiment, the cross-sectional area of ​​the first conductor 30 perpendicular to the extending direction is larger than the cross-sectional area of ​​the second conductor 40 perpendicular to the extending direction. Therefore, the DC resistance of the first conductor 30 can be made smaller than that of the second conductor 40.

[0118] In this embodiment, the 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, the insulating coating layer 26 can ensure sufficient insulation between the bottom surface of the middle leg portions 23a and 23b and the second conductor 40.

[0119] Second embodiment

[0120] The coil device 110 of the second embodiment of the present invention differs from the first embodiment described above only in the following points, and the other structures are the same as the first embodiment described above, and the same functions and effects are achieved. In the drawings, the same symbols are marked for the components common to the first embodiment, and the description of the repeated parts is omitted.

[0121] like Figure 4A and Figure 5 As shown, 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 includes a pair of first outer legs 122a, 122a, but does not include Figure 2 The side grooves 25a and 25b shown in the figure are different from the first core 20a of the first embodiment in this point. The length of the first outer leg portions 122a and 122a in the Z-axis direction is extended by the amount that the side grooves 25a and 25b are not provided.

[0122] The second core 120b is different from the second core 20b of the first embodiment in that it is formed in a flat plate shape. When the first core 120a and the second core 120b are combined, a so-called EI type core is formed.

[0123] like Figure 4B As shown, a gap G4 is formed between the first outer leg 122a and the second core 120b 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 on the other side in the X-axis direction. The gaps G4 and G5 extend in the Z-axis direction and the X-axis direction respectively along the first outer leg 122a.

[0124] In addition, a gap G6 is formed between the first middle leg portion 23a and the second core 120b. The gap G6 extends in the Z-axis direction and the X-axis direction along the first middle leg portion 23a.

[0125] like Figure 5 As shown, the first conductor 130 includes 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 side surfaces (surfaces parallel to the XZ plane) of the conductor side portions 131 and 132, and the step portions 131b and 132b are formed on the inner surfaces (surfaces parallel to the YZ plane) of the conductor side portions 131 and 132.

[0126] The width of the conductor upper portion 133 in the Y-axis direction is smaller than the width of the conductor upper portion 133 in the Y-axis direction by the amount of the stepped portions 131a and 132a formed at the upper ends of the conductor side portions 131 and 132. Figure 2 The width of the conductor upper portion 33 of the first conductor 30 in the Y-axis direction is shown.

[0127] The first mounting portion 134 includes a first mounting bent portion 340, a first mounting connecting portion 341, and a first mounting main body portion 342. The second mounting portion 135 includes a second mounting bent portion 350, a second mounting connecting portion 351, and a second mounting main body portion 352. The mounting bent portions 340 and 350 are continuously (integrally) formed at the lower end portions of the conductor side portions 131 and 132. The mounting bent portions 340 and 350 are bent in a substantially perpendicular direction relative to the conductor side portions 131 and 132, and extend in the Y-axis direction toward the side where the first core 120a is arranged.

[0128] The mounting connection parts 341 and 351 are continuously (integrally) formed at the ends of the mounting bent parts 340 and 350, and connect the mounting bent parts 340 and 350 and the mounting main parts 342 and 352. The mounting connection parts 341 and 351 extend outward in the X-axis direction.

[0129] The mounting body parts 342 and 352 are formed continuously (integrally) at the ends of the mounting connection parts 341 and 351, and extend in the Y-axis direction toward the side where the second core 120b is arranged. The first conductor 130 can be connected to the mounting surface (not shown) of the mounting substrate via the mounting body parts 342 and 352. The mounting body parts 342 and 352 are joined to the mounting surface via a joining member such as solder or a conductive adhesive.

[0130] A first outer cutout portion 136 and a second outer cutout portion 137 are formed on the outer surface of the first conductor 130. The outer cutout portions 136 and 137 extend continuously along the extending direction (longitudinal direction) of the conductor side portions 131 and 132 and the mounting bent portions 340 and 350. Parts (upper ends) of the outer cutout portions 136 and 137 are also formed at the respective ends of the conductor upper portion 133 in the X-axis direction.

[0131] like Figure 4B and Figure 5 As shown, the first outer cutout portion 136 is composed of a chamfered portion that chamfers the corners of the conductor upper portion 133, the first conductor side portion 131, and the first installation curved portion 340 on one side in the Y-axis direction (the corners between the outer surfaces and the side surfaces of the conductor upper portion 133, the first conductor side portion 131, and the first installation curved portion 340). The second outer cutout portion 137 is composed of a chamfered portion that chamfers the corners of the conductor upper portion 133, the second conductor side portion 132, and the second installation curved portion 350 on one side in the Y-axis direction (the corners between the outer surfaces and the side surfaces of the conductor upper portion 133, the second conductor side portion 132, and the second installation curved portion 350). At the positions where the outer cutout portions 136 and 137 are formed, the conductor upper portion 133, the conductor side portions 131 and 132, and the installation curved portions 340 and 350 are each provided with an inclined surface (C surface).

[0132] The outer cutouts 136 and 137 are formed in the conductor 130 at positions corresponding to the gaps G4 and G5 (positions close to the gaps G4 and G5). More specifically, the outer cutouts 136 and 137 are formed in the conductor 130 along the outer leg edges 122a1 and 122a1 of the outer leg portions 122a and 122a adjacent to the conductor 130 so as to extend in the Z-axis direction.

[0133] The first outer cutout portion 136 faces a direction inclined with respect to the other end side of the gap G4 in the X-axis direction, and at a position corresponding to the gap G4, the surface of the conductor 130 and the other end side of the gap G4 in the Y-axis direction are separated by a distance corresponding to the Y-axis width W5 or the X-axis width W6 of the first outer cutout portion 136. The second outer cutout portion 137 faces a direction inclined with respect to one end side of the gap G5 in the X-axis direction, and at a position corresponding to the gap G5, the surface of the conductor 130 and the one end side of the gap G5 in the Y-axis direction are separated by a distance corresponding to the Y-axis width or the X-axis width of the second outer cutout portion 137.

[0134] The Y-axis width of the outer cutouts 136 and 137 is preferably greater than the Y-axis width of the gaps G4 and G5, but is not limited thereto. The ratio W5 / W4 of the Y-axis width W5 of the first outer cutout 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 ratio of the Y-axis width of the second outer cutout 137 to the Z-axis width of the gap G5 is also the same.

[0135] The width of the outer cutouts 136 and 137 in the X-axis direction is preferably greater than the width of the gaps G4 and G5 in the Y-axis direction, but is not limited thereto. The ratio W6 / W4 of the width W6 of the first outer cutout 136 in the X-axis direction to the width W4 of the gap G4 in the Y-axis direction is preferably 0.5 to 6, more preferably 1 to 5, and particularly preferably 2 to 4. The ratio of the width of the second outer cutout 137 in the X-axis direction to the width of the gap G5 in the Y-axis direction is also the same.

[0136] The ratio W5 / W7 of the width W5 of the first outer cutout 136 in the Y-axis direction to the width W7 of the conductor 130 in the Y-axis direction is preferably 0.1 to 0.5, more preferably 0.2 to 0.3. The same is true for the ratio of the width W5 of the second outer cutout 137 in the Y-axis direction to the width W7 of the conductor 130 in the Y-axis direction.

[0137] The width W6 of the first outer cutout portion 136 in the X-axis direction and the thickness T2 of the conductor 130 ( Figure 5 The ratio W6 / T2 of the conductor 130 is preferably 0.1 to 0.9, and more preferably 0.3 to 0.7. The ratio of the width of the second outer cutout 137 in the X-axis direction to the thickness T2 of the conductor 130 is also the same.

[0138] 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, the leakage magnetic flux generated in the gaps G4 and G5 can be prevented from contacting the upper portion 133 of the conductor at the position corresponding to the gaps G4 and G5.

[0139] In this embodiment, the same effect as in the first embodiment can be achieved. In addition, in this embodiment, the size of the mounting parts 134, 135 (particularly the size of the mounting body parts 342, 352) is smaller than the size of the mounting parts 34, 35 of the first embodiment, so that the coil device 110 can be miniaturized.

[0140] In addition, in this embodiment, if Figure 6 As shown, since the conductor side portions 131 and 132 are provided with step portions 131b and 132b at their lower ends, a space is formed between the mounting portions 134 and 135 (mounting bent portions 340 and 350) of the first conductor 130 and the mounting portions 44 and 45 of the second conductor 40 by the step width of the step portions 131b and 132b, and a short circuit defect between the first conductor 130 and the second conductor 40 can be effectively prevented around the mounting surface (not shown) of the mounting substrate.

[0141] Third embodiment

[0142] The coil device 210 of the third embodiment of the present invention is different from the first embodiment described above only in the following points, and the other structures are the same as the first embodiment described above, and the same effects are achieved. In the drawings, the components common to the first and second embodiments are marked with common symbols, and the description of the repeated parts is omitted.

[0143] like Figure 7 As shown, the coil device 210 includes 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.

[0144] like Figure 8 As shown in FIG. 1 , 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 (the ends of the second conductor 240) stand upward. Fig. 9 As shown, the end surfaces of the mounting portions 244 and 245 are arranged at a predetermined interval in the Z-axis direction with respect to the bottom surfaces of the middle leg portions 23 a and 23 b of the cores 120 a and 220 b.

[0145] The first mounting portion 244 has a first mounting opposite surface 440', and the second mounting portion 245 has a second mounting opposite surface 450'. The first mounting opposite surface 440' has a first rising portion 443 rising relative to the mounting surface (not shown) of the mounting substrate, and the second mounting opposite surface 450' has a second rising portion 453 rising relative to the mounting surface of the mounting substrate. The rising portions 443 and 453 rise relative to the mounting surface of the mounting substrate at a midway position of the bondable surfaces 441' and 451' in the X-axis direction.

[0146] In this embodiment, the same effect as in the first embodiment can be obtained. Moreover, in this embodiment, the mounting opposite surfaces 440', 450' have rising portions 443, 453. Therefore, with respect to the mounting portions 244, 245, not only can the bonding member be attached to the opposite surface to the mounting surface of the mounting substrate, but the bonding member can also be attached to the rising portions 443, 453. Therefore, in the case of using solder as the bonding member, solder fillets can be formed on the rising portions 443, 453, and the second conductor 240 can be firmly connected to the mounting surface of the mounting substrate. In addition, the occurrence of a short circuit defect between the mounting portions 244, 245 caused by, for example, solder balls being formed on the mounting portions 244, 245 of the second conductor can be prevented.

[0147] In addition, in the present embodiment, the bottom surfaces of the cores 120a and 220b are arranged at positions away from the mounting surface (not shown) of the mounting substrate. Figure 7 As shown, the bottom surfaces of the cores 120a and 220b are separated from the bottom surfaces of the mounting portions 34 and 35 connected to the mounting surface of the mounting substrate by a distance equal to or greater than the thickness of the first conductor 30. Therefore, in this embodiment, it is possible to sufficiently ensure insulation between the bottom surfaces of the cores 120a and 220b and the mounting surface of the mounting substrate, and in particular, when the cores 120a and 220b are made of a metal magnetic body or the like, it is possible to effectively prevent short circuit defects from occurring between the bottom surfaces of the cores 120a and 220b and the mounting surface.

[0148] Fourth embodiment

[0149] The coil device 310 of the fourth embodiment of the present invention is different from the first embodiment described above only in the following points, and the other structures are the same as the first embodiment described above, and the same functions and effects are achieved. In the drawings, the components common to the first to third embodiments are marked with common symbols, and the description of the repeated parts is omitted.

[0150] like Fig.10As shown, 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 disposed below the cores 120a and 220b and fixed in a manner spanning the first conductor 30 and the second conductor 40. The resin spacer 80 mainly has the function of achieving good insulation between the first conductor 30 and the second conductor 40.

[0151] like Fig.11 and Fig.12 As shown, the resin spacer 80 includes a base portion 81 , a first lateral insulating portion 82 a , a second lateral insulating portion 82 b , a first groove portion 83 a , a second groove portion 83 b , and a protruding portion 84 .

[0152] The base portion 81 has a flat plate shape, is disposed above each of the first mounting portion 44 and the second mounting portion 45 , 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 .

[0153] A protrusion 84 extending in the Y-axis direction is formed at a substantially central portion in the X-axis direction of the base portion 81. The protrusion 84 is disposed in a gap formed between the mounting portions 44 and 45 of the second conductor 40. The downward protrusion width of the protrusion 84 is substantially equal to the thickness (plate thickness) of the mounting portions 44 and 45, and the first mounting portion 44 and the second mounting portion 45 can be separated in the X-axis direction via the protrusion 84. The protrusion 84 is a member for preventing the first mounting portion 44 and the second mounting portion 45 from being connected via a bonding member (solder ball) (solder bridge) when the second conductor 40 is connected to a mounting surface (not shown) of a mounting substrate via a bonding member such as solder.

[0154] The first groove 83a is formed between the base 81 and the first side insulating portion 82a, and the second groove 83b is formed between the base 81 and the second side insulating portion 82b. The grooves 83a and 83b extend along the Y-axis direction, and one end of the grooves 83a and 83b in the Y-axis direction is closed, while the other end in the Y-axis direction is open. Through the other end of the grooves 83a and 83b in the Y-axis direction, the lower end of the conductor side portions 41 and 42 of the second conductor 40 can be inserted into the grooves 83a and 83b.

[0155] The first lateral insulating portion 82a is disposed on one side of the base portion 81 in the X-axis direction with the first groove portion 83a interposed therebetween. The second lateral insulating portion 82b is disposed on the other side of the base portion 81 in the X-axis direction with the second groove portion 83b interposed therebetween. 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.

[0156] The first side insulating portion 82a is disposed on the first mounting portion 34 ( Fig.10 ) and the first conductor side portion 41 of the second conductor 40. At this time, the first inclined portion 85a is arranged along the shape of the first outer bent portion 38 of the first conductor 30.

[0157] The second side insulating portion 82b is disposed on the second mounting portion 35 ( Fig.10 ) and the second conductor side portion 42 of the second conductor 40. At this time, the second inclined portion 85b is arranged along the shape of the second outer curved portion 39 of the first conductor 30.

[0158] The side insulating portions 82a and 82b are components for preventing 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 from being connected via a joining member (solder bridge) when the conductors 30 and 40 are connected to a mounting surface (not shown) of a mounting substrate via a joining member such as solder.

[0159] In this embodiment, the same effects as those of the first embodiment can be achieved. In addition, in this embodiment, the mounting portions 34 and 35 of the first conductor 30 and the mounting portions 44 and 45 of the second conductor 40 are insulated via the resin spacer 80. Therefore, it is possible to effectively prevent the occurrence of short-circuit defects between the first mounting portions 34 and 35 and the second mounting portions 44 and 45.

[0160] In addition, the present invention is not limited to the above-mentioned embodiment, and various changes can be made within the scope of the present invention.

[0161] In the first embodiment described above, the insulation properties of the first conductor 30 and the second conductor 40 are ensured by the insulating layer 70 formed on the surface of the second conductor 40, but by forming the insulating layer 70 on the surface of the first conductor 30 (particularly, the inner surface of the first conductor 30), the first conductor 30 and the second conductor 40 can be insulated. In addition, 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.

[0162] In the first embodiment, the insulation between the second conductor 40 and the middle legs 23a and 23b of the cores 20a and 20b is ensured by the insulating layer 70 formed on the surface of the second conductor 40. However, the first conductor 30 and the outer legs 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 and the middle legs 23a and 23b of the cores 20a and 20b may be insulated by forming the insulating layer 70 on the outer circumferential surface of the middle legs 23a and 23b of the cores 20a and 20b (applying insulation coating to the middle legs 23a and 23b), and the first conductor 30 and the outer legs 22a and 22b of the cores 20a and 20b may be insulated by forming the insulating layer 70 on the outer circumferential surface of the outer legs 22a and 22b of the cores 20a and 20b (applying insulation coating to the outer legs 22a and 22b). The same applies to the above-mentioned second to fourth embodiments.

[0163] In the first embodiment described above, the insulating layer 70 is continuously formed along the outer surface or the inner surface of the second conductor 40 , but may be intermittently formed. The same applies to the second to fourth embodiments described above.

[0164] In the first embodiment described above, the first core 20a and the second core 20b are configured as separate bodies, but they may be configured as one body. The same applies to the second to fourth embodiments described above.

[0165] In the first embodiment, the curvature radius of the outer surface of the inner curved portions 46 and 47 of the second conductor 40 is smaller than the curvature radius of the inner surface of the outer curved portions 38 and 39 of the first conductor 30, but the above magnitude relationship may be reversed. In this case, the same effect can be achieved. The same applies to the second to fourth embodiments.

[0166] In the above-described embodiments, the insulating layer 70 extends continuously along the inner surface or the outer surface of the second conductor 40 , but may extend intermittently.

[0167] In the first embodiment described above, if Figure 3 As shown in the figure, the insulating coating layer 26 is formed on the bottom surface of the middle leg portions 23a and 23b, but the formation position of the insulating coating layer 26 is not limited thereto. 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, the insulation between the bottom surface of the outer leg portions 22a and 22b and the mounting portions 34 and 35 of the first conductor 30 can be well achieved. In addition, by forming the insulating coating layer 26 on the bottom surface of the base portions 21a and 21b, the insulation between the bottom surface of the base portions 21a and 21b and the mounting surface of the mounting substrate can be well achieved.

[0168] Explanation of symbols

[0169] 10, 110, 210, 310... coil device

[0170] 20a, 120a...the first core

[0171] 20b, 120b, 220b...Second core

[0172] 21a: first base portion

[0173] 21b... Second base portion

[0174] 22a, 122a... first outer leg

[0175] 22a1, 122a1... first outer leg edge

[0176] 22b…Second outer leg

[0177] 22b1…Second outer foot edge

[0178] 23a…First midfoot

[0179] 23b…Second midfoot

[0180] 24a: first groove

[0181] 24b...Second groove portion

[0182] 241……First side

[0183] 242... Second side

[0184] 243... Upper part

[0185] 25a: first side groove

[0186] 25b... Second side groove

[0187] 26...Insulation coating

[0188] 30, 130...First conductor

[0189] 31, 131 ... side of the first conductor

[0190] 32, 132... Second conductor side

[0191] 33, 133... Upper part of conductor

[0192] 34, 134...First installation part

[0193] 340...First installation curved portion

[0194] 341...First installation connection portion

[0195] 343...First installation main body

[0196] 35, 135... Second installation part

[0197] 350...Second installation bend

[0198] 351... Second installation connection portion

[0199] 353... Second installation main body

[0200] 36, 136... first outer incision

[0201] 37, 137... Second outer incision

[0202] 38... first outer curved portion

[0203] 39... Second outer curvature

[0204] 40, 240... Second conductor

[0205] 41……side portion of first conductor

[0206] 42... Second conductor side

[0207] 43... Upper part of conductor

[0208] 44, 244...First installation part

[0209] 440, 440'... Install opposite side

[0210] 441, 441'...joint surface

[0211] 442……Non-joint surface

[0212] 443...Standing part

[0213] 45, 245... Second installation part

[0214] 450, 450'... Install opposite side

[0215] 451, 451'...joint surface

[0216] 452……Non-joint surface

[0217] 453...Standing part

[0218] 46... first inner curved portion

[0219] 47... Second inner curvature

[0220] 50……Mounting surface of mounting base

[0221] 60...Tape components

[0222] 70...Insulation layer

[0223] 80......Resin spacer

Claims

1. A coil device, wherein: have: a first conductor; A second conductor, which is disposed inside the first conductor and at least a portion of which extends along the first conductor; as well as A core has at least a portion of the first conductor and the second conductor disposed therein, and the core has an insulating layer formed on at least a portion of the surface.

2. The coil device according to claim 1, wherein: The insulating layer is formed at least on a bottom surface of the core.

3. The coil device according to claim 1, wherein: The bottom surface of the core is arranged at a position away from the mounting surface, The insulating layer is formed on a bottom surface of the core disposed at a position away from a mounting surface.

4. The coil device according to claim 1, wherein: The insulating layer is formed on a surface of the core opposite to a portion where the first conductor or the second conductor is exposed from the core.

5. The coil device according to claim 1, wherein: The second conductor has mounting portions formed at both ends thereof, the mounting portions being exposed from the core and extending along the bottom surface of the core.

6. The coil device according to claim 1, wherein: The insulating layer is formed on the entire surface of the core.

7. The coil device according to claim 1, wherein: The insulating layer is made of resin material.

8. The coil device according to claim 1, wherein: The core includes a metallic magnetic body.

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