Coil device and manufacturing method thereof

Abstract

The invention provides a coil device capable of preventing temperature rise of a coil and deterioration of inductance characteristics and a manufacturing method thereof. A coil device (1) is provided with: a core (3) having a columnar core part (30), a side wall part (32) surrounding the core part (30), and a recessed part (36) located between the core part (30) and the side wall part (32); a winding wire having a winding part (20) accommodated in the recess (36) and having a plurality of layers in the radial direction of the core part (30), and a lead-out part led out from the winding part (20); a resin (6) attached to the winding part (20); and a terminal (5a) connected to the lead-out portion and provided on the side wall portion (32). The winding section (20) has dense sections (24) having a relatively large number of layers in the radial direction of the winding section (20), and sparse sections (25) having a relatively small number of layers in the radial direction. The resin (6) does not bond the sparse portion (25) and the side wall portion (32), but bonds the dense portion (24) and the side wall portion (32).

Description

Technical Field

[0001] The present disclosure relates to coil devices and methods of manufacturing the same. Background Art

[0002] Currently, a coil device having a so-called pot-shaped core is known (see, for example, Patent Document 1). The pot-shaped core is a bottomed, cylindrical core having a cylindrical core portion, a sidewall portion surrounding the core portion, and a recessed portion between the core portion and the sidewall portion. The recessed portion accommodates the coil, and the core portion is inserted inside the coil. The lead portion extending from the coil is connected to a terminal provided on the sidewall portion.

[0003] By filling the recess with resin, the heat generated by the coil can be dissipated through the resin, thereby preventing the temperature of the coil from rising.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 10-4021 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] However, if the amount of resin filled in the recess varies, heat dissipation from the coil will be insufficient, potentially causing a temperature rise in the coil. Furthermore, if the coil is entirely covered with resin, as in the coil assembly of Patent Document 1, stress (heat load) is likely to be generated due to differences in the thermal expansion coefficients of the coil, resin, and core, potentially degrading the inductance characteristics of the coil assembly.

[0009] The present disclosure provides a coil device and a method for manufacturing the same that can prevent a temperature increase and degradation of the inductance characteristics of a coil.

[0010] Technical solutions to solve problems

[0011] The present disclosure provides a coil device having:

[0012] a core having a columnar core portion, a sidewall portion surrounding the core portion, and a recessed portion between the core portion and the sidewall portion;

[0013] a winding having a winding portion accommodated in the recess and having a plurality of layers along a radial direction of the core, and a lead-out portion led out from the winding portion;

[0014] a resin attached to the winding portion; and

[0015] a terminal connected to the lead portion and provided on the side wall portion;

[0016] The winding portion has a dense portion with a relatively large number of layers along a radial direction of the winding portion and a sparse portion with a relatively small number of layers along the radial direction.

[0017] The resin does not bond the sparse portion to the side wall portion, but bonds the dense portion to the side wall portion.

[0018] The resin may bond the outer peripheral surface of the dense portion and the inner peripheral surface of the side wall portion.

[0019] The resin may also bond the bottom surface of the dense portion and the bottom of the recessed portion.

[0020] The dense portion may be closer to the bottom of the recessed portion than the sparse portion.

[0021] It may also be that the dense portion has a first dense portion and a second dense portion closer to the bottom of the recess than the first dense portion, the sparse portion is located between the first dense portion and the second dense portion along the axial direction of the core, and the resin bonds the second dense portion and the side wall portion.

[0022] The resin may bond the second dense portion to the side wall portion without bonding the first dense portion to the side wall portion and without bonding the sparse portion to the side wall portion.

[0023] In a cross section parallel to the axial direction of the core, the surface of the resin may be recessed toward the bottom of the recessed portion between the dense portion and the side wall portion, and may be convex as it approaches the dense portion and the side wall portion.

[0024] The surface of the resin may swell more significantly near the side wall portion than near the dense portion.

[0025] The resin may not bond the core portion and the dense portion.

[0026] The dense portion may be in contact with the core portion, but not in contact with the side wall portion and the bottom of the recessed portion.

[0027] The resin may partially bond the dense portion and the side wall portion along a path connecting the outer peripheral surface of the wound portion and the terminal at the shortest distance in a plan view.

[0028] The coil device of the present disclosure provides a manufacturing method having:

[0029] a step of preparing a wound portion having a dense portion with a relatively large number of layers in a radial direction and a sparse portion with a relatively small number of layers in a radial direction;

[0030] a step of preparing a core having a columnar core portion, a sidewall portion surrounding the core portion, and a recessed portion located between the core portion and the sidewall portion;

[0031] a step of applying a resin to the concave portion; and

[0032] A step of accommodating the wound portion in the recessed portion and allowing the resin to enter between the dense portion and the side wall portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a perspective view of the coil device according to the first embodiment.

[0034] Figure 2 Yes Figure 1 A three-dimensional diagram of the internal structure of the coil device.

[0035] Figure 3 It is a three-dimensional diagram of the first core.

[0036] Figure 4 yes Figure 2 A three-dimensional view of the terminal.

[0037] Figure 5 It is along Figure 2 A cross-sectional view taken along line VV is shown.

[0038] Figure 6 This is a diagram showing a winding method of a winding wire.

[0039] Figure 7 yes Figure 5 A partially enlarged cross-sectional view of the coil device.

[0040] Figure 8 It is a cross-sectional view of a coil device according to a second embodiment.

[0041] Figure 9A This is a graph showing the measurement results of the rate of change of the inductance characteristics of the coil device.

[0042] Figure 9B This is a graph showing the measurement results of the rate of change of the inductance characteristics of the coil device.

[0043] Figure 9C This is a graph showing the measurement results of the rate of change of the inductance characteristics of the coil device.

[0044] Figure 10 It is a cross-sectional view of a coil device according to a third embodiment.

[0045] Figure 11 It is a plan view of a coil device according to a fourth embodiment.

[0046] Figure 12 yes Figure 5A cross-sectional view of a modified example of the coil device.

[0047] Figure 13 yes Figure 10 A cross-sectional view of a modified example of the coil device. DETAILED DESCRIPTION

[0048] The following describes embodiments of the present disclosure with reference to the accompanying drawings. The drawings are merely schematic and illustrative for the purpose of understanding the present disclosure, and their appearance and dimensional ratios may differ from the actual objects. Furthermore, the present disclosure is not limited to the following embodiments.

[0049] (First embodiment)

[0050] Figure 1 The coil device 1 of the first embodiment shown in FIG. 1 functions as an inductor, for example, and is mounted on a filter circuit of an electronic device. Figure 1 and Figure 2 As shown, the coil device 1 includes a winding 2, a first core 3, a second core 4, a terminal 5a, a terminal 5b, and a resin 6 ( Figure 5 ).

[0051] The winding 2 is, for example, an insulated coated winding having a conductive core wire coated with an insulating film. The winding 2 is a well-known winding such as AIW (polyamide-imide copper wire), UEW (polyurethane copper wire), or PEW (polyester copper wire). The winding 2 is a round wire, but may also be a square wire, a stranded wire, a Litz wire, a braided wire, or the like. In addition, the winding 2 may also be a self-welding wire having a welding layer. The material constituting the winding 2 is not particularly limited, and may be, for example, copper, a copper alloy, silver, or nickel. The diameter of the winding 2 is, for example, 10 to 400 μm. At both ends of the winding 2, the coating is peeled off, exposing the conductive core wire.

[0052] like Figure 2 As shown, the winding 2 includes a winding portion 20 and lead portions 21 and 22 extending from the winding portion 20. The winding portion 20 is an air-core coil housed within the first core 3. The lead portions 21 and 22 extend in the same direction, but may also extend in different directions (e.g., opposite directions). Furthermore, the lead portions 21 and 22 extend parallel to each other, but may also extend non-parallel.

[0053] The first core 3 is a so-called pot-shaped core. The first core 3 is formed of a material containing a magnetic material and a resin. There is no particular restriction on the magnetic material constituting the first core 3, and it may be, for example, ferrite (Ni-Zn ferrite, Mn-Zn ferrite, etc.) or a metal magnetic body (Fe-Ni alloy, Fe-Si alloy, Fe-Si-Cr alloy, Fe-Co alloy, Fe-Si-Al alloy, amorphous iron, etc.). There is no particular restriction on the resin constituting the first core 3, and it may be epoxy resin, phenol resin, polyester resin, polyurethane resin, polyimide resin, etc. The first core 3 may also be a sintered body of a metal magnetic body.

[0054] like Figure 3 As shown, the first core 3 has a core portion 30, a side wall portion 32, a bottom wall portion 34, and a recessed portion 36. The bottom wall portion 34 is located at the bottom of the first core 3 having a bottomed cylindrical shape. The core portion 30 has a cylindrical shape and protrudes from the bottom wall portion 34. The shape of the core portion 30 is not limited to a cylindrical shape, and may be, for example, an elliptical column or a polygonal column. The core portion 30 passes through the winding portion 20 ( Figure 2 ) on the inside.

[0055] The recess 36 is located between the core 30 and the sidewall 32. The recess 36 is annular in plan view. The winding portion 20 is accommodated in the recess 36 (the space between the outer circumferential surface 30a of the core 30 and the inner circumferential surface 32e of the sidewall 32). As will be described later, the recess 36 is coated (filled) with resin.

[0056] The side wall portion 32 protrudes from the bottom wall portion 34 to surround the core portion 30 in all directions. The side wall portion 32 is formed in an annular shape. When viewed from above, the inner peripheral surface 32e of the side wall portion 32 is circular. The outer peripheral surface of the side wall portion 32 includes a first surface 32a, a second surface 32b, a third surface 32c, and a fourth surface 32d. The second surface 32b, the third surface 32c, and the fourth surface 32d are substantially flat. Meanwhile, the first surface 32a has recesses and projections.

[0057] overlooking Figure 3 When viewed from above, the ridgeline between the second surface 32b and the third surface 32c is curved, but the second surface 32b and the third surface 32c may also be orthogonal. Furthermore, when viewed from above, the ridgeline between the second surface 32b and the fourth surface 32d is curved, but the second surface 32b and the fourth surface 32d may also be orthogonal. Furthermore, when viewed from above, the ridgeline between the first surface 32a and the third surface 32c is chamfered, but the first surface 32a and the third surface 32c may also be orthogonal. Furthermore, when viewed from above, the ridgeline between the first surface 32a and the fourth surface 32d is chamfered, but the first surface 32a and the fourth surface 32d may also be orthogonal.

[0058] In the following, the axis parallel to the axial direction of the core 30 is set as the Z axis. In addition, the axis perpendicular to the second surface 32b is set as the X axis. In addition, the axis perpendicular to the third surface 32c and the fourth surface 32d is set as the Y axis. The Y axis is an axis along the direction relative to the third surface 32c and the fourth surface 32d. The X axis, Y axis and Z axis are orthogonal to each other. There is no particular restriction on the length of the coil device 1 in the X axis direction, for example, it is 2 to 20 mm. There is no particular restriction on the length of the coil device 1 in the Y axis direction, for example, it is 2 to 20 mm. There is no particular restriction on the length of the coil device 1 in the Z axis direction, for example, it is 1 to 10 mm.

[0059] In the present disclosure, the negative direction side of the X-axis is set as the "front", and the positive direction side of the X-axis is set as the "back". In addition, the positive direction side and the negative direction side of the Y-axis are set as the "side". In addition, the positive direction side of the Z-axis is set as the "top", and the negative direction side of the Z-axis is set as the "bottom". However, the top in the Z-axis direction is not necessarily consistent with the top in the vertical direction. In addition, the bottom in the Z-axis direction is not necessarily consistent with the bottom in the vertical direction. A mounting substrate (not shown) for mounting the coil device 1 is arranged below the coil device 1. The winding axis of the above-mentioned winding portion 20 is oriented in a direction perpendicular to the mounting substrate.

[0060] In addition, in the present disclosure, "equal", "same" or "same" are not concepts that only indicate a state in which the physical quantities of multiple objects being compared are strictly equal, identical or the same. A state in which an error of less than ±Δ% (without special restrictions, for example, Δ=7, 5 or 3) occurs between the physical quantities of multiple objects being compared is also included in the concept of "equal", "same" or "same".

[0061] In this disclosure, the term "parallel" does not necessarily mean strictly parallel, but also encompasses any condition where an error of ±Δθ° (without particular limitation, for example, Δθ=3) or less occurs with respect to strict parallelism. Furthermore, the terms "perpendicular" or "orthogonal" do not necessarily mean strictly perpendicular or orthogonal, but also encompass any condition where an error of ±Δθ° (without particular limitation, for example, Δθ=3) or less occurs with respect to strict perpendicular or orthogonal.

[0062] Notches 37a and 37b are formed on the upper surface of the side wall portion 32. When viewed in the X-axis direction, notches 37a and 37b are separated in the Y-axis direction. Notches 37a and 37b are formed by cutting away the upper surface of the side wall portion 32 downward. Notches 37a and 37b extend forward from the center of the side wall portion 32 in the X-axis direction. However, the center of the side wall portion 32 in the X-axis direction is not only the strict center of the side wall portion 32 in the X-axis direction, but also includes positions that are ±Δx away from the strict center of the side wall portion 32 in the X-axis direction. Δx is not particularly limited and may, for example, be equivalent to 5% of the length of the side wall portion 32 in the X-axis direction.

[0063] The depth of the notch 37a or 37b is not particularly limited, and may be, for example, not less than 1 / 5 and not more than 1 / 2 of the height of the side wall 32. The length (minimum or maximum length) of the notch 37a or 37b in the X-axis direction, as viewed in the Y-axis direction, is not particularly limited, and may be, for example, not less than 1 / 4 or not less than 1 / 3 of the length of the side wall 32 in the X-axis direction. The length (minimum or maximum length) of the notch 37a or 37b in the Y-axis direction, as viewed in the X-axis direction, is not particularly limited, and may be, for example, not less than 1 / 4 and not more than 1 / 2 of the length of the side wall 32 in the X-axis direction.

[0064] like Figure 2 As shown, the lead portion 21 passes through the notch 37a and is led forward toward the outside of the side wall 32. In addition, the lead portion 22 passes through the notch 37b and is led forward toward the outside of the side wall 32.

[0065] When viewed in the Y-axis direction, the lead portion 21 passes through the notch 37a and is exposed to the side (the negative Y-axis side). Furthermore, when viewed in the Y-axis direction, the lead portion 22 passes through the notch 37b and is exposed to the side (the positive Y-axis side). Furthermore, when viewed in the Y-axis direction, the winding portion 20 passes through the notches 37a and 37b and is exposed to the side.

[0066] When viewed from the X-axis direction, the lead portion 21 passes through the notch 37a and is exposed forward. Furthermore, when viewed from the X-axis direction, the lead portion 22 passes through the notch 37b and is exposed forward. Furthermore, when viewed from the X-axis direction, the winding portion 20 passes through the notches 37a and 37b and is exposed forward.

[0067] like Figure 3 As shown in FIG. 1 , recesses 39a and 39b are formed on the first surface 32a. When viewed from the X-axis direction, the recesses 39a and 39b are separated along the Y-axis direction. The recesses 39a and 39b are recessed toward the rear of the side wall portion 32. Figure 2 As shown in FIG. 1 , a portion of the terminal 5a is disposed in the recess 39a in a plan view. Also, a portion of the terminal 5b is disposed in the recess 39b in a plan view.

[0068] like Figure 3 As shown in FIG. 1 , a convex portion 38 is formed between the concave portion 39a and the concave portion 39b. The convex portion 38 protrudes forward from the bottom of the concave portions 39a and 39b. Figure 3 The length of the convex portion 38 in the Y-axis direction decreases as it moves forward and increases as it moves rearward. The length of the convex portion 38 in the Y-axis direction is not particularly limited and may be, for example, at least one-quarter or at least one-third of the length of the side wall portion 32 in the Y-axis direction. Furthermore, the length of the convex portion 38 in the X-axis direction (in other words, the depth of the concave portion 39a or 39b) is not particularly limited and may be, for example, at least one-tenth and no more than one-third of the length of the side wall portion 32 in the X-axis direction.

[0069] like Figure 4 As shown, the terminals 5a and 5b include a mounting portion 50, a first side portion 51, a second side portion 52, a connection portion 53, and a rivet portion 54. The terminals 5a and 5b are formed of a plate-shaped conductor such as metal.

[0070] like Figure 2 and Figure 4 As shown, the mounting portion 50 is arranged along the bottom surface of the first core 3. The mounting portion 50 is connected to a mounting substrate (not shown) by solder or a conductive adhesive.

[0071] The first side portion 51 of the terminal 5a is arranged along the third surface 32c. Furthermore, the first side portion 51 of the terminal 5b is arranged along the fourth surface 32d. The first side portion 51 is continuous with the mounting portion 50, perpendicular to the mounting portion 50. The length of the first side portion 51 in the X-axis direction is not particularly limited, but is longer than the length of the mounting portion 50 in the X-axis direction. A fillet such as solder or a conductive adhesive is formed on the first side portion 51.

[0072] The second side portion 52 is continuous with the first side portion 51 so as to be orthogonal to the first side portion 51. The second side portion 52 is arranged along the first surface 32a. More specifically, the second side portion 52 of the terminal 5a is arranged along the first surface 32a so as to be accommodated in the recess 39a. The second side portion 52 of the terminal 5b is arranged along the first surface 32a so as to be accommodated in the recess 39b.

[0073] The connecting portion 53 is continuous with the second side portion 52 in a manner perpendicular to the second side portion 52. Figure 2 When the terminal 5a is connected to the connection portion 53, at least a portion of the connection portion 53 is accommodated in the recess 39a. Figure 2 When the terminal 5b is at least partially accommodated in the recess 39b, the terminal 5a's connecting portion 53 is connected to the lead portion 21. The terminal 5b's connecting portion 53 is connected to the lead portion 22.

[0074] The rivet portion 54 is configured to be bendable relative to the connection portion 53. The rivet portion 54 of the terminal 5a and the rivet portion 54 of the terminal 5b are not particularly limited and are bent in a direction toward each other. The rivet portion 54 of the terminal 5a clamps the lead portion 21 that is led out to the connection portion 53 of the terminal 5a. The rivet portion 54 of the terminal 5b clamps the lead portion 22 that is led out to the connection portion 53 of the terminal 5b. The lead portions 21 and 22 are connected to the connection portions 53 of the terminals 5a and 5b by, for example, laser welding, solder, conductive adhesive, thermocompression bonding, ultrasonic bonding, resistance brazing, or ultraviolet curing resin bonding. When the connection portion 53 is laser welded, a weld bead is formed on the connection portion 53.

[0075] like Figure 1 As shown, the second core 4 is a plate-shaped core flat in the Z-axis direction. The material constituting the second core 4 is the same as the material constituting the first core 3, but may also be different. The second core 4 is bonded to the Figure 2 The upper surface of the side wall portion 32 is shown. Figure 2 In FIG. 1 , the double-dashed line indicates the adhesive application area, but the adhesive application area is not limited to Figure 2 The area shown.

[0076] like Figure 5 As shown, the winding portion 20 has a dense portion 24 and a sparse portion 25. The dense portion 24 has a relatively large number of layers along the radial direction of the core 30 (wherein, there are multiple layers along the radial direction of the core 30). The sparse portion 25 has a relatively small number of layers along the radial direction of the core 30 (wherein, there are multiple layers along the radial direction of the core 30). The number of layers of the dense portion 24 along the radial direction of the core 30 is more than the number of layers of the sparse portion 25 along the radial direction of the core 30. The number of layers of the dense portion 24 and the number of layers of the sparse portion 25 along the radial direction of the core 30 are both odd numbers, but at least one of them may be an even number. In Figure 5 In the example shown, the number of layers of the dense portion 24 along the radial direction of the core 30 is five, and the number of layers of the sparse portion 25 along the radial direction of the core 30 is three. However, there is no particular limitation on the number of layers of the dense portion 24 and the number of layers of the sparse portion 25 along the radial direction of the core 30. For example, the number of layers of the dense portion 24 along the radial direction of the core 30 may be four (an even number of layers), and the number of layers of the sparse portion 25 along the radial direction of the core 30 may be three (an odd number of layers).

[0077] The dense portion 24 is not particularly limited and is formed of three layers along the axial direction of the core 30. The sparse portion 25 is not particularly limited and is formed of four layers along the axial direction of the core 30. The number of layers of the dense portion 24 along the axial direction of the core 30 is less than the number of layers of the sparse portion 25 along the axial direction of the core 30, but may be the same as or greater than the number of layers.

[0078] In this embodiment, the dense portion 24 is closer to the bottom (bottom surface 36a) of the concave portion 36 than the sparse portion 25. That is, the dense portion 24 is located below the sparse portion 25. Figure 6 As shown, the dense portion 24 and the sparse portion 25 are continuously connected by a connecting portion 23. The connecting portion 23 extends obliquely from the radially outermost layer (third layer) of the sparse portion 25 to the radially innermost layer (first layer) of the dense portion 24.

[0079] like Figure 6 As shown by the arrow in FIG, the winding 2 is wound in a reciprocating manner in the vertical direction in the sparse portion 25. Furthermore, the winding 2 is wound in a reciprocating manner in the vertical direction in the dense portion 24. That is, in this embodiment, the winding 2 is initially wound so as to form the sparse portion 25, and then the winding 2 is wound so as to form the dense portion 24.

[0080] After forming the radially outermost layer of the sparse portion 25, the winding 2 is drawn out to the radially innermost layer of the dense portion 24. This drawn-out portion of the winding 2 serves as the connecting portion 23. Furthermore, the method for winding the winding 2 is not limited to the method described above. For example, the winding 2 may be wound to the third radial layer of the winding portion 20 without distinguishing between the dense portion 24 and the sparse portion 25. Furthermore, the winding 2 may be wound from the fourth to the fifth radial layers of the winding portion 20 in such a manner as to form the dense portion 24.

[0081] like Figure 5 As shown, the winding portion 20 (the dense portion 24 and the sparse portion 25) is in contact with the outer peripheral surface 30a of the core portion 30. More specifically, the inner peripheral surface 20a of the winding portion 20 is in contact with the outer peripheral surface 30a of the core portion 30. However, the winding portion 20 does not need to be in contact with the outer peripheral surface 30a of the core portion 30, and a gap may be formed between the inner peripheral surface 20a of the winding portion 20 and the outer peripheral surface 30a of the core portion 30.

[0082] The dense portion 24 does not contact the side wall portion 32 or the bottom (bottom surface 36a) of the recessed portion 36. Furthermore, the sparse portion 25 does not contact the side wall portion 32. More specifically, the outer peripheral surface 24a of the dense portion 24 does not contact the inner peripheral surface 32e of the side wall portion 32. Furthermore, the bottom (bottom surface) of the dense portion 24 does not contact the bottom surface 36a of the recessed portion 36. Furthermore, the outer peripheral surface 25a of the sparse portion 25 does not contact the inner peripheral surface 32e of the side wall portion 32. However, the bottom of the dense portion 24 may contact the bottom surface 36a of the recessed portion 36.

[0083] By coating (filling) the resin 6 in the recess 36, the resin 6 is attached to the winding portion 20. The resin 6 is not particularly limited, and it can be an epoxy resin, for example. The resin 6 is attached to the outer peripheral surface 24a of the dense portion 24, covering the outer peripheral surface 24a. The resin 6 enters the gap between the outer peripheral surface 24a of the dense portion 24 and the inner peripheral surface 32e of the side wall portion 32, and bonds (connects) the dense portion 24 (the outer peripheral surface 24a of the dense portion 24) and the side wall portion 32 (the inner peripheral surface 32e of the side wall portion 32). Figure 5 In the example shown, the width of the gap between the outer peripheral surface 24a of the dense portion 24 and the inner peripheral surface 32e of the side wall portion 32 is narrower than the diameter of the winding wire 2. However, the width of the gap between the outer peripheral surface 24a of the dense portion 24 and the inner peripheral surface 32e of the side wall portion 32 may be equal to the diameter of the winding wire 2 or may be wider than the diameter of the winding wire 2.

[0084] overlooking Figure 5 When the resin 6 can also fully bond the dense portion 24 and the side wall portion 32. Figure 5 When the resin 6 is partially bonded to the dense portion 24 and the side wall portion 32, the resin 6 may adhere to the outer peripheral surface 24a of the dense portion 24. However, a portion of the resin 6 may also penetrate the interior of the dense portion 24. For example, the resin 6 may adhere not only to the fifth radial layer of the dense portion 24 but also to at least one of the first to fourth radial layers of the dense portion 24. Alternatively, the entire dense portion 24 may be impregnated with the resin 6.

[0085] The resin 6 may be filled without gaps between the outer peripheral surface 24a of the dense portion 24 and the inner peripheral surface 32e of the side wall portion 32. Alternatively, the resin 6 may be filled with gaps between the outer peripheral surface 24a of the dense portion 24 and the inner peripheral surface 32e of the side wall portion 32.

[0086] The resin 6 is filled between the dense portion 24 and the side wall portion 32 from the bottom surface 36a of the recessed portion 36 to the third layer in the Z-axis direction of the dense portion 24. However, the resin 6 may be filled between the dense portion 24 and the side wall portion 32 from the bottom surface 36a of the recessed portion 36 to the second layer in the Z-axis direction of the dense portion 24, without covering the third layer in the Z-axis direction of the dense portion 24. Alternatively, the resin 6 may be filled between the dense portion 24 and the side wall portion 32 from the bottom surface 36a of the recessed portion 36 to the first layer in the Z-axis direction of the dense portion 24, without covering the second and third layers in the Z-axis direction of the dense portion 24.

[0087] The resin 6 is also filled between the dense portion 24 and the bottom (bottom surface 36a) of the recessed portion 36. The resin 6 bonds (connects) the dense portion 24 (bottom surface of the dense portion 24) and the bottom surface 36a of the recessed portion 36. The resin 6 may be filled between the dense portion 24 and the bottom surface 36a of the recessed portion 36 without a gap, or may be filled in a manner that forms a gap. The resin 6 between the dense portion 24 and the bottom surface 36a is bonded to the resin 6 between the dense portion 24 and the side wall portion 32. However, the resin 6 between the dense portion 24 and the bottom surface 36a may not be continuous with the resin 6 between the dense portion 24 and the side wall portion 32. In addition, the resin 6 may not be filled between the dense portion 24 and the bottom of the recessed portion 36. In addition, when the resin 6 is filled between the dense portion 24 and the bottom of the recessed portion 36, the resin 6 may not bond the dense portion 24 and the bottom of the recessed portion 36.

[0088] The thickness of resin 6 between dense portion 24 and side wall portion 32 (this refers to the thickness along the radial direction of dense portion 24) is thicker than the thickness of resin 6 between dense portion 24 and the bottom (bottom surface 36a) of recessed portion 36 (this refers to the thickness along the Z-axis direction of dense portion 24). However, the thickness of resin 6 between dense portion 24 and side wall portion 32 may be equal to or thinner than the thickness of resin 6 between dense portion 24 and the bottom (bottom surface 36a) of recessed portion 36.

[0089] exist Figure 5 In the example shown, resin 6 is not attached to the upper surface of dense portion 24, but may be attached to the upper surface of dense portion 24. In addition, resin 6 attached to the upper surface of dense portion 24 may be connected to resin 6 between dense portion 24 and side wall portion 32.

[0090] The resin 6 does not bond (connect) the sparse portion 25 (the outer peripheral surface 25a of the sparse portion 25) and the side wall portion 32 (the inner peripheral surface 32e of the side wall portion 32), but bonds the dense portion 24 and the side wall portion 32. Therefore, a gap is formed between the outer peripheral surface 25a of the sparse portion 25 and the inner peripheral surface 32e of the side wall portion 32. Figure 5 In the example shown, resin 6 is not attached to outer peripheral surface 25a of sparse portion 25. However, resin 6 may be attached to at least a portion of outer peripheral surface 25a of sparse portion 25, as long as it does not bond sparse portion 25 to sidewall portion 32. In this case, resin 6 attached to outer peripheral surface 25a of sparse portion 25 may also be connected to resin 6 between dense portion 24 and sidewall portion 32.

[0091] The resin 6 does not bond (connect) the core 30 and the winding portion 20 (the dense portion 24 and the sparse portion 25). This is because the outer circumferential surface 30a of the core 30 and the inner circumferential surface 20a of the winding portion 20 (the inner circumferential surface of the dense portion 24 and the inner circumferential surface of the sparse portion 25) are in contact, and the resin 6 does not enter between the outer circumferential surface 30a of the core 30 and the inner circumferential surface 20a of the winding portion 20. However, a small amount of resin 6 may enter between the outer circumferential surface 30a of the core 30 and the inner circumferential surface 20a of the winding portion 20 (the inner circumferential surface of the dense portion 24 and / or the inner circumferential surface of the sparse portion 25).

[0092] like Figure 7 As shown, a recess 60 is formed on the surface 6a of the resin 6. The recess 60 is recessed toward the bottom of the recess 36 between the dense portion 24 and the side wall portion 32. The bottom of the recess 60 is not particularly limited and is located below the upper surface of the dense portion 24.

[0093] The surface 6a of the resin 6 swells as it approaches the dense portion 24 and the side wall portion 32. That is, the surface 6a of the resin 6 tilts upward as it approaches the dense portion 24, and tilts upward as it approaches the side wall portion 32. However, the surface 6a of the resin 6 may be a flat surface parallel to the bottom surface 36a of the recessed portion 36. Alternatively, the surface 6a of the resin 6 may be an inclined surface that tilts upward as it approaches the side wall portion 32.

[0094] Surface 6a of resin 6 bulges more significantly near sidewall 32 than near dense portion 24. Surface 6a of resin 6 is located above the upper surface of dense portion 24 near sidewall 32, although not particularly limited.

[0095] Next, a method for manufacturing the coil device 1 will be described. First, a coil having Figure 1 and Figure 2 The winding portion 20 shown in FIG. 2 includes a winding wire 2, a first core 3, a second core 4, a terminal 5a, and a terminal 5b. Figure 5 As shown, the winding portion 20 has a dense portion 24 having a relatively large number of layers along the radial direction of the winding portion 20, and a sparse portion 25 having a relatively small number of layers along the radial direction of the winding portion 20. In addition, the first core 3 has a columnar core portion 30, a side wall portion 32 surrounding the core portion 30, and a recessed portion 36 located between the core portion 30 and the side wall portion 32.

[0096] Then, if Figure 2 As shown in FIG. 1 , the terminals 5a and 5b are bonded to the outer peripheral surface of the first core 3 by, for example, an adhesive. Figure 5 As shown, a predetermined amount of resin 6 is applied to (or filled with) the recessed portion 36 (e.g., the bottom surface 36a of the recessed portion 36 or the inner circumferential surface 32e of the side wall portion 32), and then the wound portion 20 is accommodated in the recessed portion 36. Furthermore, the resin 6 is allowed to enter between the dense portion 24 (the outer circumferential surface 24a of the dense portion 24) and the side wall portion 32 (the inner circumferential surface 32e of the side wall portion 32). As a result, the resin 6 bonds the dense portion 24 to the side wall portion 32 and also bonds the dense portion 24 to the bottom of the recessed portion 36. Alternatively, after the wound portion 20 is accommodated in the recessed portion 36, a predetermined amount of resin 6 may be applied to (or filled with) the recessed portion 36 (e.g., the bottom surface 36a of the recessed portion 36 or the inner circumferential surface 32e of the side wall portion 32).

[0097] Then, if Figure 4 As shown, the lead portion 21 is clamped by the rivet portion 54 of the terminal 5a, and the lead portion 21, the connection portion 53 and the rivet portion 54 are welded. In addition, the lead portion 22 is clamped by the rivet portion 54 of the terminal 5b, and the lead portion 22, the connection portion 53 and the rivet portion 54 are welded.

[0098] Then, if Figure 1 and Figure 2As shown, the second core 4 is bonded to the upper surface of the side wall portion 32 by, for example, an adhesive. Figure 1 The coil arrangement 1 is shown.

[0099] like Figure 5 As shown, in the coil device 1 of this embodiment, the winding portion 20 has a dense portion 24 having a relatively large number of layers along the radial direction of the winding portion 20, and a sparse portion 25 having a relatively small number of layers along the radial direction of the winding portion 20. Furthermore, the resin 6 does not bond the sparse portion 25 to the side wall portion 32, but bonds the dense portion 24 to the side wall portion 32. By forming the dense portion 24 in the winding portion 20, the distance between the dense portion 24 and the side wall portion 32 becomes relatively short, making it easier to bond the dense portion 24 and the side wall portion 32 with the resin 6. By bonding the dense portion 24 and the side wall portion 32 with the resin 6, heat generated by the winding portion 20 can be dissipated through the resin 6. In particular, because the dense portion 24 is more susceptible to heat generation than the sparse portion 25, by bonding the dense portion 24 and the side wall portion 32 with the resin 6, heat generated by the winding portion 20 can be efficiently dissipated through the resin 6. Furthermore, since a predetermined amount of resin 6 is filled (applied) into the recess 36 so that the dense portion 24 and the side wall portion 32 are bonded together by the resin 6, the amount of resin 6 filled into the recess 36 is less likely to vary. Furthermore, by always filling the recess 36 with the resin 6 so that the resin 6 is filled, for example, near the upper surface of the dense portion 24, variations in the amount of resin 6 filled into the recess 36 can be effectively prevented. Consequently, the amount of heat dissipated from the wound portion 20 is less likely to vary, effectively preventing a temperature increase in the wound portion 20.

[0100] Furthermore, resin 6 does not bond the sparse portion 25 to the side wall portion 32. That is, resin 6 does not cover the entirety of the winding portion 20, and does not bond the entire outer circumference of the winding portion 20 to the inner circumference 32e of the side wall portion 32. Therefore, when the temperature changes, stress caused by the difference in thermal expansion coefficients between the winding portion 20, resin 6, and first core 3 (stress or heat load caused by expansion and contraction of resin 6) is less likely to be generated, thereby preventing fluctuations in the inductance of the coil device 1.

[0101] Furthermore, resin 6 bonds the outer circumferential surface 24a of dense portion 24 to the inner circumferential surface 32e of side wall portion 32. Thus, a heat dissipation path for dissipating heat from dense portion 24 is formed between outer circumferential surface 24a of dense portion 24 and inner circumferential surface 32e of side wall portion 32. Consequently, heat from dense portion 24, which is prone to heat generation, can be efficiently dissipated toward side wall portion 32 via resin 6.

[0102] Furthermore, resin 6 bonds the bottom surface of dense portion 24 to the bottom of recessed portion 36. Therefore, a heat dissipation path for dissipating heat from dense portion 24 is formed between the bottom surface of dense portion 24 and the bottom of recessed portion 36. Consequently, heat from dense portion 24, which is prone to heat generation, can be efficiently dissipated toward sidewall portion 32 via resin 6.

[0103] Furthermore, dense portion 24 is closer to the bottom of recess 36 than sparse portion 25. Therefore, dense portion 24 can be bonded to the bottom of recess 36 via resin 6. This allows efficient heat dissipation from wound portion 20. Furthermore, the amount of resin 6 between dense portion 24 and side wall 32 can be identified through the opening of recess 36. This allows for determination of whether the amount of resin 6 between dense portion 24 and side wall 32 is appropriate (consistent).

[0104] In addition, if Figure 7 As shown, in a cross section parallel to the axial direction of the core 30, the surface 6a of the resin 6 is recessed toward the bottom of the recess 36 between the dense portion 24 and the side wall portion 32, and bulges as it approaches the dense portion 24 and the side wall portion 32. The bulging of the surface 6a of the resin 6 as it approaches the dense portion 24 improves the fixing strength between the resin 6 and the dense portion 24. Furthermore, the bulging of the surface 6a of the resin 6 as it approaches the side wall portion 32 improves the fixing strength between the resin 6 and the side wall portion 32. This facilitates the secure fixing of the winding portion 20 to the side wall portion 32 via the resin 6. Consequently, the position of the winding portion 20 is stabilized, and variations in the inductance characteristics of the coil device 1 can be prevented.

[0105] Furthermore, near the side wall portion 32, the surface 6a of the resin 6 bulges more significantly than near the dense portion 24. This further enhances the fixing strength between the resin 6 and the side wall portion 32. Consequently, the position of the winding portion 20 is stabilized, effectively preventing variations in the inductance characteristics of the coil device 1.

[0106] Furthermore, the resin 6 does not bond the core portion 30 and the dense portion 24. Therefore, stress due to expansion and contraction of the resin 6 is less likely to be generated, and fluctuations in the inductance of the coil device 1 can be prevented.

[0107] Furthermore, dense portion 24 contacts core 30 but does not contact sidewall 32 or the bottom of recess 36. The contact between dense portion 24 and core 30 stabilizes the position of winding portion 20, preventing fluctuations in the inductance of coil device 1. Furthermore, when dense portion 24 does not contact sidewall 32 or the bottom of recess 36, resin 6 easily enters between dense portion 24 and sidewall 32. Furthermore, resin 6 easily enters between dense portion 24 and the bottom of recess 36. Consequently, heat generated by winding portion 20 can be efficiently dissipated via resin 6.

[0108] The manufacturing method of the coil device 1 of this embodiment also includes a step of applying (filling) the resin 6 into the recess 36. Furthermore, the manufacturing method of the coil device 1 of this embodiment includes a step of accommodating the winding portion 20 in the recess 36 and allowing the resin 6 to enter between the dense portion 24 and the side wall portion 32. Therefore, the dense portion 24 and the side wall portion 32 can be bonded together by the resin 6 entering between the dense portion 24 and the side wall portion 32. In this case, a predetermined amount of resin 6 is filled into the recess 36 to bond the dense portion 24 and the side wall portion 32 together. Therefore, the amount of resin 6 filled into the recess 36 is less likely to vary. Furthermore, by consistently filling the recess 36 with the resin 6, for example, until it reaches near the upper surface of the dense portion 24, variations in the amount of resin 6 filled into the recess 36 can be effectively prevented. As a result, the amount of heat dissipated by the winding portion 20 is less likely to vary, effectively preventing a temperature rise in the winding portion 20.

[0109] (Second embodiment)

[0110] Figure 8 The coil device 1A of the second embodiment shown has the same configuration as the coil device 1 of the first embodiment except for the following points. Components that overlap with those of the coil device 1 of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

[0111] The coil device 1A has a winding portion 20A. In addition to the dense portion 24 and the sparse portion 25, the winding portion 20A also has a dense portion 26. That is, the dense portion of this embodiment is composed of two dense portions. The number of layers of the dense portion 26 along the radial direction of the core 30 is equal to the number of layers of the dense portion 24 along the radial direction of the core 30, but can also be more than the number of layers of the dense portion 24 along the radial direction of the core 30, or can also be less than the number of layers of the dense portion 24 along the radial direction of the core 30. The dense portion 24 is located below the dense portion 26 and closer to the bottom of the recess 36 than the dense portion 26. The sparse portion 25 is located between the dense portion 24 and the dense portion 26 along the axial direction of the core 30. The number of layers of the sparse portion 25 along the axial direction of the core 30 is not particularly limited and is three layers. The dense portion 24 and the sparse portion 25 are continuously connected by the connecting portion 23a. The dense portion 26 and the sparse portion 25 are continuously connected by the connecting portion 23b.

[0112] Resin 6 bonds (connects) the dense portion 24 (outer peripheral surface 24a of the dense portion 24) and the side wall portion 32 (inner peripheral surface 32e of the side wall portion 32). Furthermore, resin 6 bonds (connects) the dense portion 24 (the bottom of the dense portion 24) and the bottom of the recessed portion 36. The resin 6 between the dense portion 24 and the side wall portion 32 is connected to the resin 6 between the dense portion 24 and the bottom of the recessed portion 36. However, resin 6 does not necessarily need to be filled between the dense portion 24 and the bottom of the recessed portion 36. Furthermore, when resin 6 is filled between the dense portion 24 and the bottom of the recessed portion 36, resin 6 does not necessarily need to bond the dense portion 24 and the bottom of the recessed portion 36.

[0113] The resin 6 does not adhere (connect) the dense portion 26 (the outer peripheral surface 26a of the dense portion 26) and the side wall portion 32 (the inner peripheral surface 32e of the side wall portion 32). In addition, the resin 6 does not adhere to the sparse portion 25 (the outer peripheral surface 25a of the sparse portion 25) and the side wall portion 32 (the inner peripheral surface 32e of the side wall portion 32). However, the resin 6 may also adhere to the outer peripheral surface 25a of the sparse portion 25. In addition, the resin 6 may also adhere to the outer peripheral surface 26a of the dense portion 26. In this case, the resin 6 adhered to the outer peripheral surface 25a and / or 26a may also be connected to the resin 6 between the dense portion 24 and the side wall portion 32. In addition, the resin 6 may also adhere to the dense portion 26 (the outer peripheral surface 26a of the dense portion 26) and the side wall portion 32 (the inner peripheral surface 32e of the side wall portion 32).

[0114] In this embodiment, the same manufacturing method as that of the first embodiment except for the method of forming the winding portion 20A can be used to manufacture the Figure 8 That is, in this embodiment, when forming the winding portion 20A, first, the winding wire 2 is wound in a reciprocating manner in the vertical direction (see Figure 6 Then, the winding 2 is led out from the outermost layer of the dense portion 26 (the outermost layer of the dense portion 26 along the radial direction of the core 30) to the innermost layer of the sparse portion 25 (the innermost layer of the sparse portion 25 along the radial direction of the core 30). The lead-out portion of the winding 2 becomes the above-mentioned connecting portion 23b. Furthermore, by further winding the winding 2 in a reciprocating manner in the vertical direction (refer to Figure 6 Then, the winding 2 is led out from the outermost layer of the sparse portion 25 (the outermost layer of the sparse portion 25 along the radial direction of the core 30) to the innermost layer of the dense portion 24 (the innermost layer of the dense portion 24 along the radial direction of the core 30). The lead-out portion of the winding 2 becomes the above-mentioned connecting portion 23a. Moreover, by further winding the winding 2 in a reciprocating manner in the vertical direction (refer to Figure 6 ), forming a dense portion 24.

[0115] In this embodiment, the same effect as in the first embodiment can be obtained. In addition, in this embodiment, the dense portion of the winding portion 20A has a dense portion 26 and a dense portion 24 that is closer to the bottom of the recess 36 than the dense portion 26. In addition, the sparse portion 25 is located between the dense portion 24 and the dense portion 26 along the axial direction of the core 30. Moreover, the resin 6 bonds the dense portion 24 and the side wall portion 32. By forming the dense portion 24, the dense portion 26, and the sparse portion 25 in the winding portion 20A, the inter-wire parasitic capacitance is reduced between the dense portion 24 and the sparse portion 25, and the inter-wire parasitic capacitance is reduced between the dense portion 26 and the sparse portion 25. As a result, the frequency characteristics of the impedance of the coil device 1A can be broadbanded in the high-frequency band. In addition, a predetermined amount of resin 6 is filled in the recess 36 to bond the dense portion 24 and the side wall portion 32 through the resin 6, so that the amount of resin 6 filled in the recess 36 is less likely to deviate. Furthermore, by always filling the recessed portion 36 with the resin 6 so that the resin 6 is filled, for example, up to the vicinity of the upper surface of the dense portion 24, it is possible to effectively prevent variations in the amount of resin 6 filled into the recessed portion 36. As a result, the amount of heat dissipated from the wound portion 20A is less likely to vary, and a temperature increase in the wound portion 20A can be effectively prevented.

[0116] Furthermore, resin 6 does not bond dense portion 26 to side wall portion 32, nor does it bond sparse portion 25 to side wall portion 32, but bonds dense portion 24 to side wall portion 32. Therefore, the amount of resin 6 between dense portion 24 and side wall portion 32 can be identified through the opening of recess 36. This makes it possible to determine whether the amount of resin 6 between dense portion 24 and side wall portion 32 is an appropriate amount (constant amount).

[0117] Here, use Figure 8 The coil device 1A shown in FIG. Figures 9A to 9C The results of measuring the rate of change of inductance characteristics under the following conditions (i) to (iii) are shown in FIG. The rate of change of inductance characteristics was measured by moving the mounting substrate with the coil device 1A in and out of a reflow oven at a temperature of 260°C ten times. The number of samples of the coil device 1A was 24. Figures 9A to 9C In the figure, the vertical axis represents the rate of change of the inductance characteristics, and the horizontal axis represents the number of times the mounting substrate passes through the furnace. However, the number of times the mounting substrate passes through the furnace is only two: zero times and ten times.

[0118] (i)If Figure 8 As shown, the resin 6 only bonds the dense portion 24 and the side wall portion 32.

[0119] (ii) with Figure 8 Different from the example shown, the resin 6 bonds the dense portion 24 and the side wall portion 32, and also bonds the sparse portion 25 and the side wall portion 32.

[0120] (iii) with Figure 8Different from the example shown, the resin 6 bonds the dense portion 24 and the side wall portion 32, also bonds the sparse portion 25 and the side wall portion 32, and also bonds the dense portion 26 and the side wall portion 32.

[0121] In the case where the resin 6 only bonds the dense portion 24 and the side wall portion 32, as shown in FIG. Figure 9A As shown in FIG. 1 , the rate of change of inductance does not fall below ±5% of the standard value in all samples. On the other hand, when the resin 6 bonds the dense portion 24 to the side wall portion 32 and also bonds the sparse portion 25 to the side wall portion 32, as shown in FIG. Figure 9B As shown in FIG. 1 , only one sample was confirmed to have a change rate of inductance characteristics lower than the standard value. In addition, when the resin 6 bonds the dense portion 24 to the side wall portion 32, the sparse portion 25 to the side wall portion 32, and the dense portion 26 to the side wall portion 32, as shown in FIG. Figure 9C As shown, eight samples were found whose inductance characteristic variation rates were lower than the standard value. This confirmed that the inductance characteristic variation of coil device 1A can be effectively prevented by bonding only dense portion 24 and side wall portion 32 with resin 6 .

[0122] (Third embodiment)

[0123] Figure 10 The coil device 1B of the third embodiment shown has the same configuration as the coil device 1 of the first embodiment except for the following points. Components that overlap with those of the coil device 1 of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

[0124] Coil device 1B includes winding portion 20B. Winding portion 20B differs from winding portion 20 of the first embodiment in that sparse portion 25 is close to the bottom of recess 36. That is, in this embodiment, the positions of dense portion 24 and sparse portion 25 are switched in the vertical direction.

[0125] Resin 6 does not bond (connect) the sparse portion 25 and the side wall portion 32, but instead bonds (connects) the dense portion 24 and the side wall portion 32. Resin 6 may also enter the interior of the dense portion 24. Alternatively, resin 6 may adhere to the upper and / or lower surfaces of the dense portion 24. Alternatively, resin 6 may adhere to the outer peripheral surface 25a of the sparse portion 25. In this case, resin 6 attached to the outer peripheral surface 25a may also connect to resin 6 between the dense portion 24 and the side wall portion 32.

[0126] A recess 60m is formed on the upper surface 6b of the resin 6. The recess 60m is recessed toward the bottom of the recess 36 between the dense portion 24 and the side wall portion 32. The bottom of the recess 60m is not particularly limited and is located below the upper surface of the dense portion 24.

[0127] The upper surface 6b of the resin 6 bulges as it approaches the dense portion 24 and the side wall portion 32. That is, the upper surface 6b tilts upward as it approaches the dense portion 24, and tilts upward as it approaches the side wall portion 32. However, the upper surface 6b may be a flat surface parallel to the bottom surface 36a of the recessed portion 36.

[0128] In the vicinity of the side wall portion 32, the upper surface 6b of the resin 6 is more raised than in the vicinity of the dense portion 24. The upper surface 6b in the vicinity of the side wall portion 32 is not particularly limited and is located above the upper surface of the dense portion 24.

[0129] A recess 60n is formed on the lower surface 6c of the resin 6. The recess 60n is recessed between the dense portion 24 and the side wall portion 32 toward the opening of the recess 36. The bottom of the recess 60n is not particularly limited and is located above the lower surface of the dense portion 24.

[0130] The lower surface 6c of the resin 6 bulges as it approaches the dense portion 24 and the side wall portion 32. That is, the lower surface 6c slopes downward as it approaches the dense portion 24, and further slopes downward as it approaches the side wall portion 32. However, the lower surface 6c may be a flat surface parallel to the bottom surface 36a of the recessed portion 36.

[0131] In the vicinity of the side wall portion 32, the lower surface 6c of the resin 6 is more raised than in the vicinity of the dense portion 24. The lower surface 6c in the vicinity of the side wall portion 32 is not particularly limited and is located below the lower surface of the dense portion 24.

[0132] In this embodiment, the same manufacturing method as that of the first embodiment except for the method for forming the winding portion 20B and the method for applying the resin 6 can be used to manufacture the Figure 9B That is, in this embodiment, when forming the winding portion 20B, first, the winding wire 2 is wound in a reciprocating manner in the vertical direction (see Figure 6 Then, the winding 2 is led out from the outermost layer of the dense portion 24 (the outermost layer of the dense portion 24 along the radial direction of the core 30) to the innermost layer of the sparse portion 25 (the innermost layer of the sparse portion 25 along the radial direction of the core 30). The lead-out portion of the winding 2 becomes the above-mentioned connecting portion 23a. Furthermore, by further winding the winding 2 in a reciprocating manner in the vertical direction (refer to Figure 6 ), forming the sparse portion 25. Thus, the winding portion 20B can be formed.

[0133] Furthermore, unlike the first embodiment, in this embodiment, resin 6 is not applied to the bottom surface 36a of the recessed portion 36, but rather to the inner circumferential surface 32e of the side wall portion 32 (particularly, the portion of the inner circumferential surface 32e that faces the outer circumferential surface 24a of the dense portion 24). Subsequently, the wound portion 20B is housed in the recessed portion 36. Furthermore, resin 6 is introduced between the dense portion 24 (the outer circumferential surface 24a of the dense portion 24) and the side wall portion 32 (the inner circumferential surface 32e of the side wall portion 32). Alternatively, after the wound portion 20B is housed in the recessed portion 36, resin 6 may be applied to the inner circumferential surface 32e of the side wall portion 32 (particularly, the portion of the inner circumferential surface 32e that faces the outer circumferential surface 24a of the dense portion 24).

[0134] This embodiment also achieves the same effects as the first embodiment. Furthermore, in this embodiment, the dense portion 24 is closer to the opening of the recess 36 than the sparse portion 25. Therefore, it is easier to fill the space between the dense portion 24 and the side wall portion 32 with the resin 6, and the dense portion 24 and the side wall portion 32 are easily bonded together by the resin 6.

[0135] (Fourth embodiment)

[0136] Figure 11 The coil device 1C of the fourth embodiment shown has the same configuration as the coil device 1 of the first embodiment except for the following points. Components that overlap with those of the coil device 1 of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

[0137] In this embodiment, unlike the first embodiment, the resin 6 does not bond (connect) the dense portion 24 and the side wall portion 32 all over the place, but only bonds (connects) them partially. Figure 11 At this time, the resin 6 partially bonds the dense portion 24 (the outer peripheral surface 24a of the dense portion 24) and the side wall portion 32 (the inner peripheral surface 32e of the side wall portion 32) along the path connecting the outer peripheral surface of the winding portion 20 and the terminal 5a or 5b at the shortest distance. Furthermore, in addition to the path connecting the outer peripheral surface of the winding portion 20 and the terminal 5a or 5b at the shortest distance, the resin 6 also partially bonds the dense portion 24 and the side wall portion 32 around the path.

[0138] exist Figure 11In the example shown, the path connecting the outer circumference of the winding portion 20 and the terminal 5a or 5b with the shortest distance is, for example, the path connecting the outer circumference 24a of the dense portion 24 and the second side portion 52 with the shortest distance when viewed from above. However, the path connecting the outer circumference of the winding portion 20 and the terminal 5a or 5b with the shortest distance may also be the path connecting the outer circumference 24a of the dense portion 24 and the first side portion 51 with the shortest distance when viewed from above. Alternatively, the path connecting the outer circumference of the winding portion 20 and the terminal 5a or 5b with the shortest distance may also be the path connecting the outer circumference 24a of the dense portion 24 and the connection portion 53 with the shortest distance when viewed from above. Alternatively, the path connecting the outer circumference of the winding portion 20 and the terminal 5a or 5b with the shortest distance may also be the path connecting the outer circumference 24a of the dense portion 24 and the rivet portion 54 with the shortest distance when viewed from above.

[0139] In this embodiment, the same effect as in the first embodiment can be obtained. Figure 11 When the outer peripheral surface of the winding portion 20 and the terminal 5a or 5b are connected at the shortest distance, the resin 6 partially bonds the dense portion 24 and the side wall portion 32. Therefore, the heat generated by the winding portion 20 is transferred to the side wall portion 32 via the resin 6 along the path connecting the outer peripheral surface of the winding portion 20 and the terminal 5a or 5b at the shortest distance. Moreover, the heat transferred to the side wall portion 32 is transferred to the mounting substrate (not shown) via the terminal 5a or 5b. Therefore, the heat generated by the winding portion 20 can be efficiently dissipated. In addition, by locally bonding the dense portion 24 and the side wall portion 32 with the resin 6, the amount of resin 6 filled (applied) to the recess 36 can be reduced. As a result, the amount of resin 6 filled into the recess 36 is less likely to deviate.

[0140] In addition, the present disclosure is not limited to the above-described embodiment, and various changes can be made within the scope of the present disclosure.

[0141] like Figure 12 As shown, in the first embodiment, the resin 6 that bonds (connects) the dense portion 24 and the side wall portion 32 may also extend to the side of the sparse portion 25 along the inner circumferential surface 32e of the side wall portion 32. Figure 13 As shown, in the third embodiment, the resin 6 bonding (connecting) the dense portion 24 and the side wall portion 32 may extend to the side of the sparse portion 25 along the inner peripheral surface 32 e of the side wall portion 32 .

[0142] Description of Reference Numerals

[0143] 1. 1A, 1B, 1C coil devices

[0144] 2 Winding

[0145] 20, 20A, 20B winding part

[0146] 20a inner circumference

[0147] 24, 26 secret parts

[0148] 24a, 26a outer peripheral surface

[0149] 25. Shubu

[0150] 25a outer surface

[0151] 21, 22 lead-out section

[0152] 23, 23a, 23b connecting portion

[0153] 3First Core

[0154] 30 cores

[0155] 30a outer surface

[0156] 32 side wall

[0157] 32a Page 1

[0158] 32b second side

[0159] 32c third side

[0160] 32d fourth side

[0161] 32e inner surface

[0162] 34 bottom wall

[0163] 36 recesses

[0164] 36a bottom

[0165] 37a, 37b notch

[0166] 38 convex part

[0167] 39a, 39b recesses

[0168] 4 Second core

[0169] 5a, 5b terminals

[0170] 50 installation department

[0171] 51 first side

[0172] 52 second side

[0173] 53 connection section

[0174] 54 riveting department

[0175] 6 resin

[0176] 6a surface

[0177] 6b upper surface

[0178] 6c lower surface

[0179] 60, 60m, 60n recesses

Claims

1. A coil device comprising: a core having a columnar core portion, a sidewall portion surrounding the core portion, and a recessed portion between the core portion and the sidewall portion; a winding having a winding portion accommodated in the recess and having a plurality of layers along a radial direction of the core, and a lead-out portion led out from the winding portion; a resin attached to the winding portion; and a terminal connected to the lead portion and provided on the side wall portion; The winding portion has a dense portion with a relatively large number of layers along a radial direction of the winding portion and a sparse portion with a relatively small number of layers along the radial direction. The resin does not bond the sparse portion to the side wall portion, but bonds the dense portion to the side wall portion.

2. The coil device according to claim 1, wherein The resin bonds the outer peripheral surface of the dense portion and the inner peripheral surface of the side wall portion.

3. The coil device according to claim 2, wherein The resin also bonds the bottom surface of the dense portion and the bottom of the recessed portion.

4. The coil device according to any one of claims 1 to 3, wherein The dense portion is closer to the bottom of the recessed portion than the sparse portion.

5. The coil device according to any one of claims 1 to 3, wherein The dense portion includes a first dense portion and a second dense portion closer to the bottom of the recess than the first dense portion. The sparse portion is located between the first dense portion and the second dense portion along the axial direction of the core. The resin bonds the second dense portion and the side wall portion. The coil device according to claim 5 , wherein: The resin does not bond the first dense portion to the side wall portion, does not bond the sparse portion to the side wall portion, and bonds the second dense portion to the side wall portion.

7. The coil device according to any one of claims 1 to 3, wherein In a cross section parallel to the axial direction of the core, the surface of the resin is recessed between the dense portion and the side wall toward the bottom of the recess and bulges as it approaches the dense portion and the side wall.

8. The coil device according to claim 7, wherein In the vicinity of the side wall portion, the surface of the resin swells more significantly than in the vicinity of the dense portion.

9. The coil device according to any one of claims 1 to 3, wherein The resin does not bond the core portion and the dense portion.

10. The coil device according to any one of claims 1 to 3, wherein The dense portion is in contact with the core portion, but is not in contact with the side wall portion and the bottom of the recessed portion.

11. The coil device according to any one of claims 1 to 3, wherein In a plan view, the resin partially bonds the dense portion and the side wall portion along a path connecting the outer peripheral surface of the wound portion and the terminal at the shortest distance.

12. A method for manufacturing a coil device, comprising: a step of preparing a wound portion having a dense portion with a relatively large number of layers in a radial direction and a sparse portion with a relatively small number of layers in a radial direction; a step of preparing a core having a columnar core portion, a sidewall portion surrounding the core portion, and a recessed portion located between the core portion and the sidewall portion; a step of applying a resin to the concave portion; as well as A step of accommodating the wound portion in the recessed portion and allowing the resin to enter between the dense portion and the side wall portion.

Images