Coil components

Abstract

To reduce the electrostatic capacitance generated between a winding part of a first wire and a winding part of a second wire that are wound around each other around a winding core part in a coil component with two wires wound around it.SOLUTION: In a winding portion 29 of a first wire 27 and a winding portion 30 of a second wire 28, which are wound around a winding core part in a state where they are next to each other, insulation sheaths 33, 34 have a large diameter portion 35 and small diameter portions 37, 38 with a smaller outer diameter than the large diameter portion 35. Large diameter portions 35, 36 and the small diameter portions 37, 38 are distributed over multiple locations along a direction in which the wires 27, 28 extend. A gap 39 caused by a difference in radial dimension between the large diameter portions 35, 36 and the small diameter portions 37, 38 is formed between the first winding portion 29 and the second winding portion 30. The gap 39 contributes to reducing the electrostatic capacitance.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This invention relates to a coil component having a structure in which at least two wires are wound around a core portion provided on a bobbin, and particularly relates to the form of an insulating coating of the wire.

Background Art

[0002] As coil components of interest for this invention, there are, for example, those constituting a common mode choke coil or a transformer. A coil component constituting a common mode choke coil or a transformer includes a bobbin having a core portion for winding a wire, and at least two wires including a first wire and a second wire wound around the core portion respectively.

[0003] Normally, the first wire and the second wire respectively constitute a first winding portion and a second winding portion wound around the core portion, except for respective both ends connected to terminal electrodes.

[0004] As shown in FIG. 9, the first wire 1 and the second wire 2 each have a center conductor 3 and 4 made of a highly conductive metal, and an insulating coating 5 and 6 made of an electrically insulating resin covering the circumferential surfaces of the center conductors 3 and 4. In the above-described first winding portion and second winding portion, the cross-sections of the first wire 1 and the second wire 2 are circular.

[0005] The first wire 1 and the second wire 2 are wound around the core portion adjacent to each other as shown in FIG. 9 in their respective first winding portions and second winding portions. In this state, if a potential difference exists between the first wire 1 and the second wire 2, a capacitance is generated between the first wire 1 and the second wire 2. When the capacitance is large, it will adversely affect the electrical characteristics of the common mode choke coil or the transformer.

[0006] Therefore, it is desirable to reduce capacitance. For example, Japanese Patent Publication No. 2017-537462 (Patent Document 1) describes a structure that reduces capacitance by placing a tube-section-shaped wall made of an electrically insulating material between a first wire wound on the inner layer side and a second wire wound on the outer layer side. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Special Publication No. 2017-537462 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In the structure described in Patent Document 1, the presence of a tube-shaped wall hinders the miniaturization of the coil component, and the need to prepare the tube-shaped wall as a separate component leads to the complexity and increased cost of the coil component manufacturing process.

[0009] Therefore, the objective of this invention is to provide a coil component that can solve the above-mentioned problems, that is, a component that can suppress the generation of stray capacitance without requiring other components such as a wall in the shape of a tube section. [Means for solving the problem]

[0010] This invention relates to a coil component comprising a bobbin having a winding core, and at least two wires, including a first wire and a second wire, each wound around the winding core and having a central conductor and an insulating coating made of an electrically insulating resin covering the circumferential surface of the central conductor.

[0011] The coil component according to this invention has a first winding portion and a second winding portion, respectively, in which the first wire and the second wire are wound adjacent to each other around the winding core. In order to solve the above-mentioned technical problems, the insulating coating in at least one of the first winding portion and the second winding portion has a large diameter portion and a small diameter portion with a smaller outer diameter compared to the large diameter portion, and the large diameter portion and the small diameter portion are distributed over multiple locations along the direction in which the wire extends. [Effects of the Invention]

[0012] According to this invention, the presence of large-diameter and small-diameter portions in the insulating coating of the wire creates a gap between the first and second winding portions due to the difference in radial dimensions between the large-diameter and small-diameter portions. This gap can be filled with air, which has a low dielectric constant, thus contributing to a reduction in the capacitance generated between the first and second winding portions. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view showing the schematic configuration of a coil component 11 according to the first embodiment of this invention. [Figure 2] This is a schematic cross-sectional view along line AA in Figure 1, showing the first winding portion 29 of the first wire 27 and the second winding portion 30 of the second wire 28, which are wound adjacent to each other around the core of the coil component 11 shown in Figure 1. [Figure 3] Figure 2 shows cross-sectional views of the first winding portion 29 of the first wire 27 and the second winding portion 30 of the second wire 28 along line BB. [Figure 4] This is a cross-sectional view corresponding to Figure 2, schematically showing the first winding portion 29 of the first wire 27 and the second winding portion 30 of the second wire 28, which are wound adjacent to each other around the core, for the purpose of illustrating a second embodiment of the present invention. [Figure 5] Figure 4 shows cross-sectional views of the first winding portion 29 of the first wire 27 and the second winding portion 30 of the second wire 28 along line CC. [Figure 6] This is a cross-sectional view corresponding to FIG. 2 for explaining the third embodiment of the present invention, showing the winding portion 29 of the wire 27. [Figure 7] This is a cross-sectional view corresponding to FIG. 2 for explaining the fourth embodiment of the present invention, showing the winding portion 29 of the wire 27. [Figure 8] This is a cross-sectional view corresponding to FIG. 2 for explaining the fifth embodiment of the present invention, showing the winding portion 29 of the wire 27. [Figure 9] This is a cross-sectional view for explaining the background art of the present invention, showing the first winding portion of the first wire 1 and the second winding portion of the second wire 2.

Embodiments for Carrying Out the Invention

[0014] Referring to FIG. 1, the schematic configuration of the coil component 11 according to the first embodiment of the present invention will be described.

[0015] The coil component 11 constitutes, for example, a common mode choke coil. The coil component 11 includes a bobbin 12. The bobbin 12 includes a winding core portion 13, and a first flange portion 15 and a second flange portion 16 provided at opposite ends of the winding core portion 13 in the axial direction, respectively. The bobbin 12 is preferably made of ferrite. The bobbin 12 may be made of a non-conductive material other than ferrite, such as a non-magnetic material like alumina, a resin like plastic, or a resin containing ferrite powder or metal magnetic powder.

[0016] The winding core portion 13, the first flange portion 15, and the second flange portion 16 provided on the bobbin 12 have, for example, a quadrangular prism shape with a quadrangular cross-sectional shape. Also, rounded chamfers may be provided on each ridge line portion of the quadrangular prism-shaped winding core portion 13 and the flange portions 15 and 16. Note that the cross-sectional shapes of the winding core portion 13 and the flange portions 15 and 16 may be polygons such as hexagons, circles, ellipses, or combinations thereof, in addition to quadrangles.

[0017] The first flange portion 15 has a bottom surface 17 that faces the mounting substrate side during mounting, and a top surface 19 that faces in the opposite direction to the bottom surface 17. The second flange portion 16 is the same as the first flange portion 15, and has a bottom surface 18 that faces the mounting substrate side during mounting, and a top surface 20 that faces in the opposite direction to the bottom surface 18.

[0018] Although not shown in detail, the first terminal electrode 21 and the third terminal electrode 23 are provided on the bottom surface 17 of the first flange portion 15 in a state of being arranged in a direction orthogonal to the plane of FIG. 1 and spaced apart from each other. The second terminal electrode 22 and the fourth terminal electrode 24 are provided on the bottom surface 18 of the second flange portion 16 in a state of being arranged in a direction orthogonal to the plane of FIG. 1 and spaced apart from each other. In FIG. 1, the first terminal electrode 21 and the second terminal electrode 22 are shown formed on the outer surfaces of the first flange portion 15 and the second flange portion 16, respectively, and the third terminal electrode 23 and the fourth terminal electrode 24 are shown in cross section together with a part of each of the first flange portion 15 and the second flange portion 16. <00�0094>

[0019] The coil component 11 further includes at least two wires wound around the bobbin portion 13. In this embodiment, the wires include a first wire 27 and a second wire 28. In FIG. 1, in order to make the distinction between the first wire 27 and the second wire 28 on the drawing clearer, the first wire 27 is shaded. The first wire 27 and the second wire 28 each have a first winding portion 29 and a second winding portion 30 wound around the bobbin portion 13. The first wire 27 is wound so as to form an inner layer with the first winding portion 29, and the second wire 28 is wound so as to form an outer layer with the second winding portion 30. Although not shown, both ends of the first wire 27 are respectively connected to the first terminal electrode 21 and the second terminal electrode 22, and both ends of the second wire 28 are respectively connected to the third terminal electrode 23 and the fourth terminal electrode 24. For these connections, for example, thermocompression bonding is applied.

[0020] Figure 2 is a cross-sectional view along line AA in Figure 1, schematically showing an enlarged view of the first winding portion 29 of the first wire 27 and the second winding portion 30 of the second wire 28 wound around the winding core 13 shown in Figure 1. As shown in Figure 2, the first winding portion 29 of the first wire 27 and the second winding portion 30 of the second wire 28 are adjacent to each other. Figure 3 is a further enlarged view of Figure 2, showing a cross-sectional view of the first winding portion 29 of the first wire 27 and the second winding portion 30 of the second wire 28 along line BB in Figure 2.

[0021] Referring to Figures 2 and 3, the first wire 27 and the second wire 28 each have a central conductor 31 and 32 made of a highly conductive metal such as copper, silver, or gold, and insulating coatings 33 and 34 made of an electrically insulating resin such as polyurethane, polyamide-imide, or polyester covering the circumferential surfaces of the central conductors 31 and 32. In the first winding portion 29 and the second winding portion 30 described above, the cross-sections of the central conductors 31 and 32 are circular and have a substantially constant diameter along the direction in which the wires 27 and 28 extend.

[0022] On the other hand, the radial dimensions of the insulating coatings 33 and 34 vary along the direction in which the wires 27 and 28 extend. Specifically, the insulating coating 33 of the first winding portion 29 on the first wire 27 side has a large diameter portion 35 and a small diameter portion 37 with a smaller outer diameter compared to the large diameter portion 35. The insulating coating 34 of the second winding portion 30 on the second wire 28 side has a large diameter portion 36 and a small diameter portion 38 with a smaller outer diameter compared to the large diameter portion 35.

[0023] The large-diameter portion 35 and the small-diameter portion 37 of the insulating coating 33 of the first winding portion 29 are distributed over multiple locations along the direction in which the first wire 27 extends. The large-diameter portion 36 and the small-diameter portion 38 of the insulating coating 34 of the second winding portion 30 are distributed over multiple locations along the direction in which the second wire 28 extends.

[0024] In this embodiment, the large-diameter portion 35 and the small-diameter portion 37 on the first winding portion 29 side are arranged alternately at regular intervals along the direction in which the first wire 27 extends. Similarly, the large-diameter portion 36 and the small-diameter portion 38 on the second winding portion 30 side are arranged alternately at regular intervals along the direction in which the second wire 28 extends.

[0025] Furthermore, with respect to the length measured in the direction of extension of the first wire 27 and the second wire 28, the large diameter portion 35 and the large diameter portion 36 are equal to each other, and the small diameter portion 37 and the small diameter portion 38 are equal to each other.

[0026] Furthermore, the spacing between the large-diameter portion 35 and the small-diameter portion 37 on the first winding portion 29 side is equal to the spacing between the large-diameter portion 36 and the small-diameter portion 38 on the second winding portion 30 side. Also, the large-diameter portion 33 on the first winding portion 29 side faces the small-diameter portion 38 on the second winding portion 30 side, and the small-diameter portion 37 on the first winding portion 29 side faces the large-diameter portion 36 on the second winding portion 30 side.

[0027] Furthermore, in each of the first winding portion 29 and the second winding portion 30, the thickness of the insulating coatings 33 and 34 in the large diameter portions 35 and 36 is preferably twice or less the thickness of the insulating coatings 33 and 34 in the small diameter portions 37 and 38. Also preferably, the thickness of the insulating coatings 33 and 34 in the large diameter portions 35 and 36 is 1.1 times or more the thickness of the insulating coatings 33 and 34 in the small diameter portions 37 and 38.

[0028] Furthermore, in this embodiment, the thickness of the insulating coating 33 in the large-diameter portion 35 of the first winding portion 29 is substantially equal to the thickness of the insulating coating 34 in the large-diameter portion 36 of the second winding portion 30, and the thickness of the insulating coating 33 in the small-diameter portion 37 of the first winding portion 29 is substantially equal to the thickness of the insulating coating 34 in the small-diameter portion 38 of the second winding portion 30.

[0029] As described above, according to this embodiment, the large-diameter portions 35 and 36 and the small-diameter portions 37 and 38 are mixed in the insulating coatings 33 and 34, and a gap 39 is formed between the first winding portion 29 and the second winding portion 30 due to the difference in radial dimensions between the large-diameter portions 35 and 36 and the small-diameter portions 37 and 38. This gap 39 is usually filled with air, which has a low dielectric constant, and thus contributes to reducing the capacitance generated between the first winding portion 29 and the second winding portion 30. In this embodiment, the gap 39 has a size corresponding to the difference in radial dimensions between the large-diameter portions 35 and 36 and the small-diameter portions 37 and 38.

[0030] Furthermore, when the cross-sectional shape of the core is a polygon such as a square, it is preferable that at least one large-diameter portion rests on one side of the polygon, or that at least one large-diameter portion rests on at least one corner of the polygon. When the cross-sectional shape of the core is circular or elliptical, it is preferable that at least one large-diameter portion is located within the range of one full turn.

[0031] Furthermore, in this embodiment, the thickness is configured to vary in two stages, with large-diameter portions 35 and 36 and small-diameter portions 3 and 38. However, the thickness may also vary in three or more stages.

[0032] Next, a second embodiment of the present invention will be described with reference to Figures 4 and 5. Figure 4 is a cross-sectional view corresponding to Figure 2, and Figure 5 is a diagram corresponding to Figure 3. In Figures 4 and 5, elements corresponding to the elements shown in Figures 2 and 3 are denoted by the same reference numerals, and redundant explanations are omitted.

[0033] In this embodiment, the large-diameter portion 35 and the small-diameter portion 37 on the first winding portion 29 side are arranged alternately at an irregular interval along the direction in which the first wire 27 extends. Similarly, the large-diameter portion 36 and the small-diameter portion 38 on the second winding portion 30 side are arranged alternately at an irregular interval along the direction in which the second wire 28 extends.

[0034] Therefore, there is no particular regularity between the large-diameter portion 35 and the small-diameter portion 37 on the first winding portion 29 side and the large-diameter portion 36 and the small-diameter portion 38 on the second winding portion 30 side.

[0035] As a result, the large-diameter portion 35 on the first winding portion 29 side may face the large-diameter portion 36 on the second winding portion 30 side, or it may face the small-diameter portion 38 on the second winding portion 30 side. Similarly, the small-diameter portion 37 on the first winding portion 29 side may face the large-diameter portion 36 on the second winding portion 30 side, or it may face the small-diameter portion 38 on the second winding portion 30 side.

[0036] As described above, in this embodiment as well, the large-diameter portions 35 and 36 and the small-diameter portions 37 and 38 are mixed in the insulating coatings 33 and 34, and a gap 40 is formed between the first winding portion 29 and the second winding portion 30 due to the difference in radial dimensions between the large-diameter portions 35 and 36 and the small-diameter portions 37 and 38. In this embodiment, the gap 40 is largest at its widest point, and is equivalent to twice the difference in radial dimensions between the large-diameter portions 35 and 36 and the small-diameter portions 37 and 38.

[0037] In the first and second embodiments described above, both the first winding portion 29 and the second winding portion 30, which are wound adjacent to each other around the core portion 13, have large-diameter portions 35 and 36 and small-diameter portions 37 and 38. However, either the first winding portion or the second winding portion may have large-diameter portions and small-diameter portions. Even in this case, a gap can be formed between the first winding portion and the second winding portion due to the difference in radial dimensions between the large-diameter portion and the small-diameter portion.

[0038] Furthermore, in the first and second embodiments, the large-diameter portions 35 and 36 had a shape that rose from the small-diameter portions 37 and 38 with a step that rose in a direction perpendicular to the direction in which the wires 27 and 28 extended; in other words, the cross-section was square, but this shape can be arbitrarily changed.

[0039] Figures 6 to 8 illustrate yet another embodiment of the present invention and show modified examples of the large-diameter portion. Note that Figures 6 to 8 only show the winding portion of one of the first and second wires, which are wound adjacent to each other around the core. For example, only the first winding portion 29 of the first wire 27 is shown. Therefore, in Figures 6 to 8, the reference numerals related to the first winding portion 29 of the first wire 27 are the same as those used in Figure 2, and redundant explanations are omitted. Although not shown, the winding portion of the other wire may or may not have a large-diameter portion and a small-diameter portion.

[0040] In the third embodiment shown in Figure 6, a large-diameter portion 35 with a trapezoidal cross-section is provided.

[0041] In the fourth embodiment shown in Figure 7, a large-diameter portion 35 with a triangular cross-section is provided.

[0042] In the fifth embodiment shown in Figure 8, a large-diameter portion 35 with a semi-elliptical cross-section is provided.

[0043] As described in the first to fifth embodiments above, in order to vary the radial dimension of the insulating coatings 33 and 34 along the direction in which the wires 27 and 28 extend, methods such as varying the amount of insulating coating material applied to the circumferential surface of the central conductors 31 and 32 for the formation of the insulating coatings 33 and 34, or forming the insulating coatings 33 and 34 with a uniform thickness and then physically removing a portion of the thickness of the insulating coatings 33 and 34 by locally irradiating them with laser light or applying a sharp rotating blade can be employed. It is preferable that the method of removing a portion of the thickness of the insulating coatings 33 and 34 by irradiating them with laser light be carried out in parallel with the process of winding the wires 27 and 28 around the winding core 13.

[0044] Although the present invention has been described above in relation to the illustrated embodiments, various other embodiments are possible within the scope of this invention.

[0045] For example, although the insulating coatings 33 and 34 are shown to have uniform radial dimensions with respect to the circumferential direction, the radial dimensions may vary with respect to the circumferential direction, or they may vary with respect to both the direction in which the wire extends and the circumferential direction.

[0046] Furthermore, in the illustrated embodiment, a multi-layer winding is employed in which the first wire and the second wire are wound around the core such that one forms the inner layer and the other the outer layer. However, a bifilar winding is also employed in which the first wire and the second wire are adjacent to each other in the axial direction of the core. Alternatively, a winding is employed in which the first wire and the second wire change their relative positions and intersect in some parts. A twisted winding is also employed in which the first wire and the second wire are wound in a twisted state.

[0047] Furthermore, in this invention, since large-diameter and small-diameter portions are mixed in the insulating coating of the wire, a gap is formed between the first and second winding portions due to the difference in radial dimensions between the large-diameter and small-diameter portions, and since the effect of reducing capacitance is sought, it is preferable that the gap be filled with air, which has a low dielectric constant. However, even if the coil component is impregnated with resin, for example, and the gap is filled with resin, the effect of reducing capacitance can be maintained as long as the relative permittivity of the resin is lower than that of the insulating coating.

[0048] Furthermore, although the embodiments described above relate to coil components that constitute a common mode choke coil, they may also relate to components that constitute a transformer or the like.

[0049] Furthermore, the embodiments described above are illustrative, and partial substitution or combination of configurations is possible between different embodiments.

[0050] Embodiments of this invention include the following:

[0051] <1> A bobbin having a winding core, At least two wires, including a first wire and a second wire, each wound around the aforementioned core and having a central conductor and an insulating coating made of an electrically insulating resin covering the circumferential surface of the central conductor, Equipped with, The first wire and the second wire each have a first winding portion and a second winding portion that are wound adjacent to each other around the winding core, In at least one of the first winding portion and the second winding portion, the insulating coating has a large-diameter portion and a small-diameter portion having a smaller outer diameter compared to the large-diameter portion, and the large-diameter portion and the small-diameter portion are distributed over multiple locations along the direction in which the wire extends. Coil components.

[0052] <2> The large-diameter portion and the small-diameter portion are arranged alternately at regular intervals along the direction in which the wire extends. <1> The coil components described above.

[0053] <3> The large-diameter portion and the small-diameter portion are arranged alternately at irregular intervals along the direction in which the wire extends. <1> The coil component described above.

[0054] <4> The thickness of the insulating coating in the large-diameter portion is no more than twice the thickness of the insulating coating in the small-diameter portion. <1> or <3> A coil component as described in any of the following.

[0055] <5> In both the first winding portion and the second winding portion, the first wire and the second wire have a large diameter portion and a small diameter portion. <1> or <4> A coil component as described in any of the following.

[0056] <6> The large-diameter portion on the first winding portion side includes the portion facing the large-diameter portion on the second winding portion side. <5> The coil components described above.

[0057] <7> The large-diameter portion on the first winding portion side includes the portion facing the small-diameter portion on the second winding portion side. <5> or <6> The coil components described above.

[0058] <8> The first wire and the second wire are wound around the core such that one forms the inner layer and the other forms the outer layer. <1> or <7> A coil component as described in any of the following.

[0059] <9> The coil component constitutes a common mode choke coil. <1> or <8> A coil component as described in any of the following.

[0060] <10> The coil component constitutes the transformer. <1> or <8> A coil component as described in any of the following. [Explanation of Symbols]

[0061] 11 Coil components 12 bobbins 13. Core section 27. First wire 28. Second wire 29 Part 1 of Volume 1 30 Part 2 of Volume 2 31,32 Center conductor 33,34 Insulating coating 35,36 Large diameter section 37,38 Small diameter part 39,40 gap

Claims

1. A bobbin having a winding core, At least two wires, including a first wire and a second wire, each wound around the aforementioned core, and each having a central conductor and an insulating coating made of an electrically insulating resin covering the circumferential surface of the central conductor, Equipped with, The first wire and the second wire each have a first winding portion and a second winding portion that are wound adjacent to each other around the winding core, In the first winding portion, the insulating coating has a large diameter portion and a small diameter portion that has a smaller outer diameter over its entire circumference compared to the large diameter portion, and the large diameter portion and the small diameter portion are arranged alternately along the direction in which the wire extends. The large-diameter portion includes the portion that is in contact with the insulating coating of the second wire in the second winding portion. The small-diameter portion includes a portion in which a gap is formed between the small-diameter portion and the insulating coating of the second wire in the second winding portion. Coil components.

2. The coil component according to claim 1, wherein the large-diameter portion and the small-diameter portion are arranged alternately at regular intervals along the direction in which the wire extends.

3. The coil component according to claim 1, wherein the large-diameter portion and the small-diameter portion are arranged alternately at an irregular interval along the direction in which the wire extends.

4. The coil component according to claim 1, wherein the thickness of the insulating coating in the large-diameter portion is no more than twice the thickness of the insulating coating in the small-diameter portion.

5. The coil component according to claim 1, wherein in both the first winding portion and the second winding portion, the first wire and the second wire have a large diameter portion and a small diameter portion.

6. The coil component according to claim 1, wherein the first wire and the second wire are wound around the winding core such that one forms the inner layer and the other forms the outer layer.

7. The coil component according to claim 1, wherein the coil component constitutes a common mode choke coil.

8. The coil component according to claim 1, wherein the coil component constitutes a transformer.

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