Coil parts

Abstract

To provide a coil component with improved heat dissipation around a through conductor.SOLUTION: In a coil component 1, since the cross-sectional areas S1 and S2 of inner ends 41b and 42b of planar coils 41 and 42 are designed to be relatively wide, heat generated in through conductors 41c and 42c is easily transmitted to the inner ends 41b and 42b. Thus, in the coil component 1, heat is efficiently transferred from the through conductors 41c and 42c to the inner ends 41b and 42b, such that high heat dissipation can be achieved around the through conductors 41c and 42c.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a coil component. [Background technology]

[0002] Conventionally, coil components having multiple coils provided within an element body have been known. Patent Document 1 listed below discloses a four-terminal coil component having two coils provided within an element body, in which planar coils provided on both sides of an insulating substrate are connected to each other via through conductors. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-130472 Summary of the Invention [Problem to be solved by the invention]

[0004] In the coil component described above, the temperature around the through conductor may become excessively high during operation, which may impair the stability of the element characteristics. The inventors have conducted extensive research into heat dissipation around the through conductor and have discovered a new technology that can improve heat dissipation.

[0005] An object of the present invention is to provide a coil component with improved heat dissipation around a through conductor. [Means for solving the problem]

[0006] A coil component according to one aspect of the present invention comprises a pair of coil sections having a base body, an insulating substrate provided within the base body, a pair of planar coils wound parallel to each other on the insulating substrate, and a pair of through conductors that overlap the inner ends of adjacent planar coils and pass through the insulating substrate, and in a cross section perpendicular to the insulating substrate, the cross-sectional area of ​​the inner ends of the planar coils is wider than the cross-sectional area of ​​the planar coils outside the inner ends and is also wider than the cross-sectional area of ​​the through conductors.

[0007] In the coil component, the cross-sectional area of ​​the through conductor is relatively narrow, and the current density of the current flowing through the planar coil during operation is high in the through conductor, making it easy for heat to be generated. However, because the cross-sectional area of ​​the inner end of the planar coil that overlaps with the through conductor is wider than the cross-sectional area of ​​the planar coil on the outer side, heat generated in the through conductor is easily transferred to the inner end. In this way, the coil component efficiently transfers heat from the through conductor to the inner end, achieving high heat dissipation around the through conductor.

[0008] In a coil component according to another aspect of the present invention, the height of the inner end of the planar coil is lower than the height of the planar coil in a portion outside the inner end.

[0009] In a coil component according to another aspect of the present invention, the width of the inner end of the planar coil is wider than the width of the planar coil in a portion outside the inner end.

[0010] In a coil component according to another aspect of the present invention, a planar coil is covered with an insulating material, and the thickness of the insulating material covering the inner end of the planar coil is greater than the thickness of the insulating material covering a portion of the planar coil outside the inner end.

[0011] In a coil component according to another aspect of the present invention, the thickness of the insulating substrate is thinner than the thickness of the inner end portion of the planar coil.

[0012] In a coil component according to another aspect of the present invention, the thicknesses of the inner ends of the pair of planar coils are different from each other.

[0013] In a coil component according to another aspect of the present invention, the thickness of the insulating substrate is thinner than the dimension of the through conductor in the extending direction of the insulating substrate.

[0014] In a coil component according to another aspect of the present invention, the through conductor has a narrowed cross section in a cross section perpendicular to the insulating substrate.

[0015] In a coil component according to another aspect of the present invention, the through conductors are biased outward relative to the inner end of the planar coil. [Effects of the Invention]

[0016] According to the present invention, a coil component is provided in which heat dissipation around the through conductor is improved. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic perspective view of a coil component according to an embodiment. [Figure 2] FIG. 2 is a diagram showing the inside of the coil component of FIG. [Figure 3] FIG. 3 is an exploded view of the coil shown in FIG. [Figure 4] 4 is a cross-sectional view of the coil device shown in FIG. 2 taken along line IV-IV. [Figure 5] 5 is a cross-sectional view of the coil device shown in FIG. 2 taken along line VV. [Figure 6] FIG. 6 is a plan view of the coil shown in FIG. [Figure 7] FIG. 7 is an enlarged view of a main part of the cross-sectional view shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same elements or elements having the same functions will be denoted by the same reference numerals, and redundant description will be omitted.

[0019] The coil component 1 according to the embodiment is, for example, a balun coil. The balun coil is used, for example, when a near field communication circuit (NFC circuit) is installed in a cellular terminal. The balun coil converts between an unbalanced signal from an antenna and a balanced signal from the NFC circuit, thereby realizing a connection between an unbalanced circuit and a balanced circuit. The coil component 1 can also be used as a common mode filter or a transformer.

[0020] As shown in FIG. 1, the coil component 1 is composed of an element body 10, a coil structure 20 embedded in the element body 10, and two pairs of external terminal electrodes 60A, 60B, 60C, and 60D provided on the surface of the element body 10.

[0021] The element body 10 has a rectangular parallelepiped outer shape and six faces 10a to 10f. As an example, the element body 10 is designed with dimensions of a long side of 2.0 mm, a short side of 1.25 mm, and a height of 0.65 mm. Of the faces 10a to 10f of the element body 10, the end face 10a (first end face) and the end face 10b (second end face) are parallel to each other, the top face 10c and the bottom face 10d are parallel to each other, and the side face 10e and the side face 10f are parallel to each other. The top face 10c of the element body 10 is the face that faces parallel to the mounting surface of the mounting board on which the coil component 1 is mounted.

[0022] The element body 10 is made of a resin 12 containing a metal magnetic powder, which is a type of magnetic material. The resin 12 containing a metal magnetic powder is a binder powder in which metal magnetic powder is bound by a binder resin. The metal magnetic powder in the resin 12 containing a metal magnetic powder is made of, for example, an iron-nickel alloy (permalloy alloy), carbonyl iron, an amorphous, non-crystalline, or crystalline FeSiCr-based alloy, sendust, or the like. The binder resin is, for example, a thermosetting epoxy resin. In this embodiment, the content of the metal magnetic powder in the binder powder is 80 to 92 vol% in volume percent and 95 to 99 wt% in mass percent. From the viewpoint of magnetic properties, the content of the metal magnetic powder in the binder powder may be 85 to 92 vol% in volume percent and 97 to 99 wt% in mass percent. The magnetic powder in the resin 12 containing a metal magnetic powder may be a powder having one type of average particle size or a mixed powder having multiple types of average particle sizes.

[0023] The metal magnetic powder-containing resin 12 of the element body 10 integrally covers the coil structure 20, which will be described later. Specifically, the metal magnetic powder-containing resin 12 covers the coil structure 20 from above and below, and also covers the outer periphery of the coil structure 20. The metal magnetic powder-containing resin 12 also fills the inner periphery of the coil structure 20.

[0024] The coil structure 20 is configured to include an insulating substrate 30, an upper coil structure 40A provided on the upper side of the insulating substrate 30, and a lower coil structure 40B provided on the lower side of the insulating substrate 30.

[0025] The insulating substrate 30 has a flat plate shape, extends between the end faces 10a, 10b of the element body 10, and is designed to be perpendicular to the end faces 10a, 10b. The insulating substrate 30 also extends parallel to the upper face 10c and the lower face 10d of the element body 10. As shown in FIG. 3 , the insulating substrate 30 has an elliptical ring-shaped coil forming portion 31 that extends along the long side of the element body 10, and a pair of frame portions 34A, 34B that extend along the short side of the element body 10 and sandwich the coil forming portion 31 from both sides. An elliptical opening 32 that extends along the long side of the element body 10 is provided in the center of the coil forming portion 31.

[0026] The insulating substrate 30 is made of a non-magnetic insulating material. The thickness of the insulating substrate 30 can be designed to be in the range of 10 to 60 μm, for example. In this embodiment, the insulating substrate 30 has a configuration in which glass cloth is impregnated with epoxy resin. The resin constituting the insulating substrate 30 is not limited to epoxy resin, and may be BT resin, polyimide, aramid, etc. The constituent material of the insulating substrate 30 may be ceramic or glass. The constituent material of the insulating substrate 30 may be a mass-produced printed circuit board material. The constituent material of the insulating substrate 30 may be a resin material used for BT printed circuit boards, FR4 printed circuit boards, or FR5 printed circuit boards.

[0027] Upper coil structure 40A is provided on substrate upper surface 30a in coil forming portion 31 of insulating substrate 30. As shown in Figures 2 and 3, upper coil structure 40A is configured to include first planar coil 41, second planar coil 42, and upper insulator 50A. First planar coil 41 and second planar coil 42 are wound adjacent to each other in parallel on upper surface 30a of insulating substrate 30.

[0028] The first planar coil 41 is a substantially oval spiral air-core coil wound around the opening 32 of the coil-forming portion 31 in the same layer on the upper surface 30a of the insulating substrate 30. The number of turns of the first planar coil 41 may be one or more. In this embodiment, the number of turns of the first planar coil 41 is three to four. The first planar coil 41 has an outer end 41a and an inner end 41b. The outer end 41a is provided on the frame portion 34A and exposed from the end surface 10a of the element body 10. The inner end 41b is provided on the edge of the opening 32. A first through conductor 41c extending in the thickness direction of the insulating substrate 30 is provided in the insulating substrate 30 at a position overlapping with the inner end 41b of the first planar coil 41 so as to penetrate the insulating substrate 30. The first planar coil 41 is made of, for example, Cu and can be formed by electrolytic plating.

[0029] Like the first planar coil 41, the second planar coil 42 is a substantially oval spiral air-core coil wound around the opening 32 of the coil-forming portion 31 in the same layer on the upper surface 30a of the insulating substrate 30. The second planar coil 42 is wound adjacent to the first planar coil 41 on the inner circumferential side of the first planar coil 41. The number of turns of the second planar coil 42 may be one turn or multiple turns. In this embodiment, the number of turns of the second planar coil 42 is the same as the number of turns of the first planar coil 41. The second planar coil 42 has an outer end portion 42a and an inner end portion 42b. Like the outer end portion 41a of the first planar coil 41, the outer end portion 42a of the second planar coil 42 is provided on the frame portion 34A and exposed from the end surface 10a of the element body 10. An inner end 42b of the second planar coil 42 is provided on the edge of the opening 32 and adjacent to the inner end 41b of the first planar coil 41. A second through conductor 42c extending in the thickness direction of the insulating substrate 30 is provided in the insulating substrate 30 at a position overlapping with the inner end 42b of the second planar coil 42 so as to penetrate the insulating substrate 30. The second through conductor 42c is adjacent to the first through conductor 41c. Like the first planar coil 41, the second planar coil 42 is made of, for example, Cu and can be formed by electrolytic plating.

[0030] The upper insulator 50A is provided on the upper surface 30a of the insulating substrate 30. The upper insulator 50A includes a thick-film resist patterned by known photolithography. The thick-film resist of the upper insulator 50A defines plating growth regions for the first planar coil 41 and the second planar coil 42. In this embodiment, as shown in FIG. 4 , the upper insulator 50A integrally covers the first planar coil 41 and the second planar coil 42, more specifically, covers the side and top surfaces of the first planar coil 41 and the second planar coil 42. In this embodiment, the upper insulator 50A includes an insulating resin film that covers the top surfaces of the first planar coil 41 and the second planar coil 42. As shown in FIGS. 5 and 6 , a portion of the upper insulator 50A extends from the inside of the element body 10 between the outer end 41a and the outer end 42a to the end surface 10a of the element body 10 and is exposed at the end surface 10a. 5 and 6, a portion of upper insulator 50A extends along substrate upper surface 30a from the inside of element body 10 to end surface 10b and is exposed at end surface 10b. Upper insulator 50A is thicker than first planar coil 41 and second planar coil 42. Upper insulator 50A is made of, for example, epoxy resin.

[0031] Lower coil structure 40B is provided on substrate lower surface 30b in coil forming portion 31 of insulating substrate 30. As shown in Figures 2 and 3, lower coil structure 40B is configured to include first planar coil 41, second planar coil 42, and lower insulator 50B. First planar coil 41 and second planar coil 42 are wound adjacent to each other in parallel on lower surface 30b of insulating substrate 30.

[0032] The first planar coil 41 and the second planar coil 42 of the lower coil structure 40B are symmetrical to the first planar coil 41 and the second planar coil 42 of the upper coil structure 40A. More specifically, the first planar coil 41 and the second planar coil 42 of the lower coil structure 40B have a shape obtained by inverting the first planar coil 41 and the second planar coil 42 of the upper coil structure 40A around an axis parallel to the short side of the base body 10.

[0033] An outer end 41a of the first planar coil 41 of the lower coil structure 40B is provided on the frame portion 34B and exposed from the end surface 10b of the element body 10. An inner end 41b of the first planar coil 41 of the lower coil structure 40B overlaps a first through conductor 41c provided on the insulating substrate 30. Therefore, the inner end 41b of the first planar coil 41 of the lower coil structure 40B is electrically connected to the inner end 41b of the first planar coil 41 of the upper coil structure 40A via the first through conductor 41c. The first planar coil 41 of the lower coil structure 40B is made of, for example, Cu and can be formed by electrolytic plating.

[0034] The outer end 42a of the second planar coil 42 of the lower coil structure 40B is provided on the frame portion 34B and exposed from the end surface 10b of the element body 10. The inner end 42b of the second planar coil 42 of the lower coil structure 40B overlaps with a second through conductor 42c provided in the insulating substrate 30. Therefore, the inner end 42b of the second planar coil 42 of the lower coil structure 40B is electrically connected to the inner end 42b of the second planar coil 42 of the upper coil structure 40A via the second through conductor 42c. The second planar coil 42 of the lower coil structure 40B is made of, for example, Cu and can be formed by electrolytic plating.

[0035] The lower insulator 50B is provided on the lower surface 30b of the insulating substrate 30. The lower insulator 50B includes a thick-film resist patterned by known photolithography. Like the thick-film resist of the upper insulator 50A, the thick-film resist of the lower insulator 50B defines plating growth regions of the first planar coil 41 and the second planar coil 42. In this embodiment, as shown in FIG. 4 , the lower insulator 50B integrally covers the first planar coil 41 and the second planar coil 42, more specifically, covers the side and top surfaces of the first planar coil 41 and the second planar coil 42. In this embodiment, the lower insulator 50B includes an insulating resin film that covers the top surfaces of the first planar coil 41 and the second planar coil 42. Like the upper insulator 50A, a portion of the lower insulator 50B extends from the inside of the element body 10 between the outer end 41a and the outer end 42a to the end face 10b of the element body 10 and is exposed at the end face 10b. A portion of the lower insulator 50B also extends from the inside of the element body 10 along the substrate lower surface 30b to the end face 10a and is exposed at the end face 10a. The thickness of the lower insulator 50B is greater than the thicknesses of the first planar coil 41 and the second planar coil 42. The thickness of the lower insulator 50B may be the same as the thickness of the upper insulator 50A. The lower insulator 50B is made of, for example, epoxy resin.

[0036] The element body 10 includes a pair of coil portions C1 and C2 that form a double coil structure. The first coil portion C1 is composed of a first planar coil 41 of an upper coil structure 40A provided on the upper surface 30a of the insulating substrate 30, a first planar coil 41 of a lower coil structure 40B provided on the lower surface 30b of the insulating substrate 30, and a first through conductor 41c that connects the first planar coils 41 on both surfaces. In the first coil portion C1, the outer end 41a of the first planar coil 41 of the upper coil structure 40A forms a first end, and the outer end 41a of the first planar coil 41 of the lower coil structure 40B forms a second end. The second coil portion C2 is composed of the second planar coil 42 of the upper coil structure 40A provided on the upper surface 30a of the insulating substrate 30, the second planar coil 42 of the lower coil structure 40B provided on the lower surface 30b of the insulating substrate 30, and a second through conductor 42c connecting the second planar coils 42 on both surfaces. In the second coil portion C2, the outer end 42a of the second planar coil 42 of the upper coil structure 40A constitutes a first end, and the outer end 42a of the second planar coil 42 of the lower coil structure 40B constitutes a second end.

[0037] Two pairs of external terminal electrodes 60A, 60B, 60C, and 60D are provided on the parallel end faces 10a and 10b of the element body 10, one pair each.

[0038] Of the pair of external terminal electrodes 60A, 60B provided on the end face 10a, the external terminal electrode 60A is connected to the outer end 41a of the first planar coil 41 of the upper coil structure 40A, and the external terminal electrode 60B is connected to the outer end 42a of the second planar coil 42 of the upper coil structure 40A. As shown in Fig. 6, when viewed from the end face 10a side, the external terminal electrode 60A is biased toward the side face 10f and covers the end face 10a up to the vicinity of the side face 10f. Furthermore, the external terminal electrode 60B is biased toward the side face 10e and covers the end face 10a up to the vicinity of the side face 10e. When viewed from the end face 10a side, the external terminal electrodes 60A and 60B are spaced apart by a predetermined uniform width.

[0039] Of the pair of external terminal electrodes 60C, 60D provided on the end face 10b, the external terminal electrode 60C is connected to the outer end 41a of the first planar coil 41 of the lower coil structure 40B, and the external terminal electrode 60D is connected to the outer end 42a of the second planar coil 42 of the lower coil structure 40B. The external terminal electrode 60C is biased toward the side face 10f and covers the end face 10b up to the vicinity of the side face 10f. The external terminal electrode 60D is biased toward the side face 10e and covers the end face 10b up to the vicinity of the side face 10e. When viewed from the end face 10b side, the external terminal electrodes 60C and 60D are spaced apart by a predetermined uniform width.

[0040] The external terminal electrode 60A on the end face 10a and the external terminal electrode 60C on the end face 10b are provided at positions corresponding to each other in the long side direction of the element body 10. Similarly, the external terminal electrode 60B on the end face 10a and the external terminal electrode 60D on the end face 10b are provided at positions corresponding to each other in the long side direction of the element body 10.

[0041] Each of the external terminal electrodes 60A, 60B, 60C, and 60D is bent in an L-shape and continuously covers the end faces 10a, 10b and the upper face 10c. In this embodiment, the external terminal electrodes 60A, 60B, 60C, and 60D are made of resin electrodes, for example, made of a resin containing Ag powder.

[0042] Next, the configurations of the inner end portions 41b, 42b and the through conductors 41c, 42c of the planar coils 41, 42 will be described with reference to Fig. 7. Fig. 7 shows a cross section perpendicular to the insulating substrate 30 and passing through the through conductors 41c, 42c, and is an enlarged view of a main portion of the cross section of Fig. 4. In the following description, the configurations of the planar coils 41, 42 in the upper coil structure 40A will be described, but the configurations of the planar coils 41, 42 in the lower coil structure 40B are the same or similar.

[0043] As shown in Fig. 7, the cross-sectional area S1 of the inner end 41b of the first planar coil 41 and the cross-sectional area S2 of the inner end 42b of the second planar coil 42 are both designed to be wider than the cross-sectional area s of the planar coils 41, 42 of the turns outer than the inner ends 41b, 42b. In the embodiment shown in Fig. 7, the width W1 of the inner end 41b of the first planar coil 41 and the width W2 of the inner end 42b of the second planar coil 42 are both wider than the width w of the planar coils 41, 42 of the turns outer than the inner ends 41b, 42b. Furthermore, in the embodiment shown in Fig. 7, the thickness D1 of the insulating material covering the inner end 41b of the first planar coil 41 and the thickness D2 of the insulating material covering the inner end 42b of the second planar coil 42 are both thicker than the thickness d of the insulating material covering the planar coils 41, 42 of the turns outer than the inner ends 41b, 42b.

[0044] The cross-sectional area S1 of the inner end 41b of the first planar coil 41 and the cross-sectional area S2 of the inner end 42b of the second planar coil 42 are designed to be different from each other. The cross-sectional areas S1 and S2 may be designed to be the same. In the embodiment shown in FIG. 7, the cross-sectional area S1 of the inner end 41b of the first planar coil 41 is larger than the cross-sectional area S2 of the inner end 42b of the second planar coil 42. The thickness H1 of the inner end 41b of the first planar coil 41 and the thickness H2 of the inner end 42b of the second planar coil 42 are designed to be different from each other. In the embodiment shown in FIG. 7, the thickness H1 of the inner end 41b of the first planar coil 41 is thicker than the thickness H2 of the inner end 42b of the second planar coil 42. Regarding the thickness of upper insulator 50A, thickness D1 of the insulating material in the portion covering inner end 41b of first planar coil 41 is thinner than thickness D2 of the insulating material in the portion covering inner end 42b of second planar coil 42. Note that thicknesses D1 and D2 may be the same. Width W1 of inner end 41b of first planar coil 41 may be the same as or different from width W2 of inner end 42b of second planar coil 42.

[0045] The first through conductor 41c overlapping the inner end 41b of the first planar coil 41 and the second through conductor 42c overlapping the inner end 42b of the second planar coil 42 have the same thickness as the thickness t of the insulating substrate 30. The first through conductor 41c and the second through conductor 42c have circular cross sections in the thickness direction of the insulating substrate 30. The thickness of the insulating substrate 30 is designed to be thinner than the diameters of the first through conductor 41c and the second through conductor 42c (i.e., the dimensions in the extending direction of the insulating substrate 30). The cross-sectional area s1 of the first through conductor 41c is smaller than the cross-sectional area S1 of the inner end 41b of the first planar coil 41. Furthermore, the cross-sectional area s2 of the second through conductor 42c is smaller than the cross-sectional area S2 of the inner end 42b of the second planar coil 42. The first through conductor 41c and the second through conductor 42c both have a constricted cross-sectional shape, and become narrower from the top and bottom surfaces 30a, 30b of the insulating substrate 30 toward the inside. The first through conductor 41c and the second through conductor 42c are both biased toward the outer periphery of the coil (to the right in FIG. 7) with respect to the inner ends 41b, 42b of the planar coils 41, 42. The first through conductor 41c and the second through conductor 42c may not be biased toward the outer periphery of the coil (for example, may be aligned with the center positions of the inner ends 41b, 42b).

[0046] As described above, the cross-sectional areas s1 and s2 of the through conductors 41c and 42c are relatively narrow (for example, narrower than the cross-sectional areas S1 and S2 of the inner ends 41b and 42b of the planar coils 41 and 42). This increases the current density of the current flowing through the planar coils 41 and 42 when the coil device 1 is driven, making the through conductors 41c and 42c more susceptible to heat generation. In particular, excessive heat is likely to occur in a configuration in which the through conductors 41c and 42c are adjacent to each other, as in the coil device 1. Furthermore, if the cross-sectional shapes of the through conductors 41c and 42c are narrowed, the current density increases and heat is more likely to be generated.

[0047] In the coil device 1, the cross-sectional areas S1 and S2 of the inner ends 41b and 42b of the planar coils 41 and 42 are designed to be relatively large (for example, larger than the cross-sectional area s of the planar coils 41 and 42 in their outer portions), so that heat generated in the through conductors 41c and 42c is easily transferred to the inner ends 41b and 42b. In this way, in the coil device 1, heat is efficiently transferred from the through conductors 41c and 42c to the inner ends 41b and 42b, so that high heat dissipation is achieved around the through conductors 41c and 42c.

[0048] The present invention is not limited to the above-described embodiment, but can take various forms.

[0049] For example, the number of turns of the first coil portion and the second coil portion can be increased or decreased as appropriate. Also, the coil portion element may include three or more coil portions. [Explanation of symbols]

[0050] 1...coil component, 10...element body, 12...resin containing metal magnetic powder, 30...insulating substrate, 41...first planar coil, 42...second planar coil, 41b, 42b...inner end portion, 41c, 42c...through conductor, C1...first coil portion, C2...second coil portion.

Claims

1. The base body and an insulating substrate provided within the element body and having an opening; a pair of coil sections including a pair of planar coils wound parallel to each other around the opening on the insulating substrate, and a pair of through conductors that overlap inner ends of adjacent planar coils at edges on the same side with respect to the opening and that penetrate the insulating substrate; a cross-sectional area of ​​an inner end of the planar coil is wider than a cross-sectional area of ​​a portion of the planar coil outer than the inner end and is also wider than a cross-sectional area of ​​the through conductor in a cross section perpendicular to the insulating substrate, and thicknesses of the inner ends of the pair of planar coils are different from each other.

2. The coil component according to claim 1 , wherein the height of an inner end of the planar coil is lower than the height of a portion of the planar coil outside the inner end.

3. The coil component according to claim 1 or 2, wherein the width of an inner end of the planar coil is wider than the width of a portion of the planar coil outside the inner end.

4. The coil component according to any one of claims 1 to 3, wherein the planar coil is covered with an insulating material, and the thickness of the insulating material covering the inner end of the planar coil is thicker than the thickness of the insulating material covering the planar coil in a portion outer than the inner end.

5. 5. The coil component according to claim 1, wherein the insulating substrate has a thickness smaller than a thickness of an inner end portion of the planar coil.

6. 6. The coil component according to claim 1, wherein the insulating substrate has a thickness smaller than a dimension of the through conductor in the extending direction of the insulating substrate.

7. 7. The coil component according to claim 1, wherein the through conductor has a constricted cross-sectional shape in a cross section perpendicular to the insulating substrate.

8. The coil component according to any one of claims 1 to 7, wherein the through conductor is biased outward relative to an inner end of the planar coil.

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