coil components

Abstract

This invention provides a coil component that, by employing a magnetic sheet, easily induces magnetic saturation within the magnetic sheet, thereby reducing the DC superposition characteristics of the coil component. However, the inner edge of the coil structure is recessed relative to the inner edge of the magnetic sheet, creating a structure where the magnetic flux generated in the coil can easily rotate. Therefore, the reduction in DC superposition characteristics caused by the use of the magnetic sheet is suppressed.

Description

Technical Field

[0001] This invention relates to a coil component. Background Technology

[0002] Currently, coil components with a pair of coils overlapping each other in the coil axis are known. Japanese Patent Application Publication No. 2018-137421 discloses a coil component in which a PCB substrate is located between the pair of coils, and a high coupling coefficient is obtained through the PCB substrate, which is a non-magnetic body. Summary of the Invention

[0003] [The technical problem that the invention aims to solve]

[0004] It is believed that in the above-mentioned prior art coil components, when a magnetic sheet is used as a magnetic body instead of a PCB substrate as a non-magnetic body, magnetic saturation is easily generated in the magnetic sheet, and the DC superposition characteristics of the coil component are reduced.

[0005] The inventors conducted in-depth research and discovered a new technology that can suppress the reduction of DC superposition characteristics even when magnetic sheets are used.

[0006] According to the present invention, a coil component capable of suppressing the reduction of DC superposition characteristics is provided.

[0007] [Technical solutions used to solve technical problems]

[0008] One aspect of the present invention provides a coil component comprising: a base body made of a resin containing metal powder; a pair of coil structures disposed within the base body, each comprising a pair of coils, the pair of coils having a pair of ends that overlap each other in the coil axial direction and extend to a surface of the base body; two pairs of external terminals disposed on the surface of the base body and respectively connected to the ends of the pair of coils; and a magnetic sheet disposed within the base body, located between the pair of coil structures in the coil axial direction, wherein through holes extending along the coil axial direction are respectively provided on the pair of coil structures and the magnetic sheet, and the inner edge of at least one of the pair of coil structures is recessed relative to the inner edge of the magnetic sheet.

[0009] In the coil component, the inner edge of the coil structure is recessed relative to the inner edge of the magnetic sheet. Therefore, the magnetic flux generated by the coil can easily rotate, mitigating the local concentration of magnetic flux and suppressing the reduction of DC superposition characteristics.

[0010] In another coil component, for at least one of a pair of coil structures, the inner edge of the coil axially away from the magnetic sheet is positioned further back than the inner edge of the coil closer to the magnetic sheet.

[0011] In another coil component, on a cross section containing the coil axis, the outlines of a pair of coil structures are linearly symmetrical with respect to a line orthogonal to the coil axis.

[0012] In another coil component, the magnetic sheet is in contact with the metal powder contained in the resin containing metal powder that forms the body in the inner edge.

[0013] In another coil component, the thickness of the body portion that overlaps with a pair of coil structures in the coil axial direction is equal. Attached Figure Description

[0014] Figure 1 This is a schematic perspective view of the coil component in the embodiment.

[0015] Figure 2 It means Figure 1 A diagram of the interior of the coil component.

[0016] Figure 3 yes Figure 2 An exploded perspective view of the coil structure shown.

[0017] Figure 4 It means Figure 3 A top view of the magnetic sheet shown.

[0018] Figure 5 yes Figure 2 The figure shown is a cross-sectional view of the V-V line.

[0019] Figure 6 yes Figure 2 The figure shown is a cross-sectional view along line VI-VI.

[0020] Figure 7 It is Figure 6 The main part of the cross-sectional view shown is enlarged.

[0021] Figure 8 It means manufacturing Figure 1 Cross-sectional view of the magnetic sheet and a pair of coil structures in the intermediate stage of the coil component.

[0022] Figure 9 It means manufacturing Figure 1 Cross-sectional view of the magnetic sheet and a pair of coil structures in the intermediate stage of the coil component. Detailed Implementation

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and repeated descriptions are omitted.

[0024] The coil component 1 in this embodiment is a so-called coupled coil. The coupled coil contains two coils in a single component, enabling a reduction in the number of components and a smaller mounting area. The coupled coil can be used as a smoothing coil in switching power supplies, such as DC / DC converters in various electronic devices.

[0025] like Figure 1 , Figure 2 As shown, the coil component 1 is composed of a body 10, a coil structure 20 embedded in the body 10, and two pairs of external terminal electrodes 60A, 60B, 60C, and 60D disposed on the surface of the body 10.

[0026] The body 10 has a rectangular parallelepiped shape and six faces 10a to 10f. As an example, the body 10 is designed with a long side of 2.0 mm, a short side of 1.25 mm, and a height of 0.45 mm. Of the faces 10a to 10f of the body 10, end faces 10a and 10b are parallel to each other, the upper surface 10c and the lower surface 10d are parallel to each other, and the side surfaces 10e and 10f are parallel to each other. The upper surface 10c of the body 10 is parallel to the mounting surface of the mounting substrate of the coil component 1.

[0027] The base material 10 is composed of a magnetic material, namely a resin 12 containing metallic magnetic powder. The resin 12 containing metallic magnetic powder comprises metal powder and resin; more specifically, the metallic magnetic powder is a binder powder bonded by a binder resin. The metallic magnetic powder in the resin 12 can be, for example, an iron-nickel alloy (permalloy), carbonyl iron, amorphous, amorphous, or crystalline FeSiCr alloys, aluminum-silicon-iron powder, etc. The binder resin is, for example, a thermosetting epoxy resin. In this embodiment, the content of metallic magnetic powder in the binder powder is 80–92 vol% by volume and 95–99 wt% by mass. From the viewpoint of magnetic properties, the content of metallic magnetic powder in the binder powder can also be 85–92 vol% by volume and 97–99 wt% by mass. The magnetic powder in the resin 12 containing metallic magnetic powder can be a powder having a single average particle size or a mixture of powders having multiple average particle sizes.

[0028] The resin 12 containing metallic magnetic powder of the base body 10 integrally covers the coil structure 20 described later. Specifically, the resin 12 containing metallic magnetic powder covers the coil structure 20 from top to bottom and covers the outer periphery of the coil structure 20. In addition, the resin 12 containing metallic magnetic powder fills the inner periphery region of the coil structure 20.

[0029] like Figure 2 , Figure 3As shown, the coil structure 20 comprises a magnetic sheet 30, an upper coil structure 40A disposed on the upper side of the magnetic sheet 30, and a lower coil structure 40B disposed on the lower side of the magnetic sheet 30. The coil structure 20 is a laminate formed by sequentially stacking the upper coil structure 40A, the magnetic sheet 30, and the lower coil structure 40B. In the stacking direction, the magnetic sheet 30 is provided between the upper coil structure 40A and the lower coil structure 40B.

[0030] The magnetic sheet 30 has a flat, plate-like shape (e.g., sheet-like or layered) and extends between the end faces 10a and 10b of the body 10, designed to be orthogonal to the end faces 10a and 10b. Furthermore, the magnetic sheet 30 extends parallel to the upper surface 10c and lower surface 10d of the body 10. Figure 4 As shown, the magnetic sheet 30 has: an elliptical annular coil overlap portion 31 extending along the long side of the body 10; and a pair of frame portions 34A and 34B extending along the short side of the body 10 and sandwiching the coil overlap portion 31 from both sides. An elliptical opening (through hole) 32 extending along the long side of the body 10 is provided in the central portion of the coil overlap portion 31. The thickness t of the magnetic sheet 30 can be designed, for example, within 10 to 100 μm (30 μm as an example).

[0031] The magnetic sheet 30 is made of a magnetic material. In this embodiment, the magnetic sheet 30 comprises resin and magnetic powder (magnetic material powder), and has a structure in which the magnetic powder is dispersed in the resin. The resin of the magnetic sheet 30 is, for example, an epoxy resin. The magnetic powder of the magnetic sheet 30 may be, for example, composed of ferrite, permalloy, aluminum-silicon-iron powder, Fe-based magnetic materials, etc. The magnetic powder of the magnetic sheet 30 may be in the form of flat or needle-like shapes, or in the form of spheres. For example, when the magnetic powder of the magnetic sheet 30 is flat, the magnetic powder may also extend in a direction intersecting the thickness direction of the magnetic sheet 30 (for example, a direction orthogonal to the thickness direction of the magnetic sheet 30). The magnetic sheet 30 may also be an amorphous foil, amorphous ribbon, or amorphous layer made of a magnetic material.

[0032] The magnetic sheet 30 of this embodiment has a structure in which ferrite flat powder is dispersed substantially uniformly in epoxy resin, and the ferrite flat powder extends in a direction orthogonal to the thickness direction of the magnetic sheet 30. Therefore, for the magnetic sheet 30, the magnetic permeability in the direction orthogonal to the thickness direction is higher than that in the thickness direction. In addition, the ferrite flat powder extends substantially parallel to the extension direction of the magnetic sheet 30, thus suppressing the thickening of the magnetic sheet 30 and improving the magnetic permeability.

[0033] like Figure 3As shown, the upper coil structure 40A is disposed on the upper surface 30a of the coil overlap portion 31 of the magnetic sheet 30. The upper coil structure 40A is composed of an insulating layer 30A, a first upper planar coil 41, a second upper planar coil 42, a first upper insulator 51, and a second upper insulator 52, and has a through hole 45A.

[0034] The insulating layer 30A has a flat, plate-like shape (e.g., sheet-like or layered) and extends parallel to the magnetic sheet 30. Viewed in the thickness direction, the insulating layer 30A has substantially the same shape as the magnetic sheet 30. That is, like the magnetic sheet 30, the insulating layer 30A has: an elliptical annular coil overlap portion 31 extending along the long side of the body 10; and a pair of frame portions 34A, 34B extending along the short side of the body 10 and sandwiching the coil overlap portion 31 from both sides. An elliptical opening 32 extending along the long side of the body 10 is provided in the central portion of the coil overlap portion 31. The thickness t1 of the insulating layer 30A can be designed within, for example, a range of 10 to 50 μm (15 μm as an example). The insulating layer 30A is made of an insulating material, for example, a resin material such as BT resin.

[0035] The first upper planar coil 41 is a generally elliptical spiral-shaped hollow coil wound around the opening 32 of the coil overlap portion 31 within the same layer on the upper surface 30a of the insulating layer 30A. The first upper planar coil 41 has a coil axis Z along the thickness direction of the body 10. The number of turns of the first upper planar coil 41 can be one turn or multiple turns. In this embodiment, the number of turns of the first upper planar coil 41 is 2 to 3. The first upper planar coil 41 has an outer end portion 41a and an inner end portion 41b. The outer end portion 41a is provided on the frame portion 34A, extends to the end face 10a of the body 10, and is exposed from the end face 10a. The inner end portion 41b is provided at the edge of the opening 32. On the insulating layer 30A, a through conductor 47 extending along the thickness direction of the insulating layer 30A is provided at a position overlapping the inner end portion 41b of the first upper planar coil 41 in a manner that penetrates the insulating layer 30A. The first upper planar coil 41 is made of Cu, for example, and can be formed by electroplating. In this embodiment, the first upper planar coil 41 has an auxiliary outer end 41c, which overlaps with the outer end 42a of the second upper planar coil 42 (described later) by sandwiching an insulating layer 30A. The auxiliary outer end 41c is electrically connected to the outer end 42a via a through conductor (not shown) penetrating the insulating layer 30A. By providing the auxiliary outer end 41c and making the outer end a double-layer structure, the contact area between the outer end and the external terminal electrode is increased, and the connectivity is improved.

[0036] The second upper planar coil 42 is symmetrical to the first upper planar coil 41. More specifically, the second upper planar coil 42 has a shape that reverses the shape of the first upper planar coil 41 about an axis parallel to the short side of the body 10. The second upper planar coil 42 and the first upper planar coil 41 share a coil axis Z. The outer end portion 42a of the second upper planar coil 42 is provided in the frame portion 34B, extends to the end face 10b of the body 10, and protrudes from the end face 10b. The inner end portion 42b of the second upper planar coil 42 overlaps with the through conductor 47 provided in the insulating layer 30A. Therefore, the inner end portion 42b of the second upper planar coil 42 is electrically connected to the inner end portion 41b of the first upper planar coil 41 via the through conductor 47. The second upper planar coil 42 is made of Cu, for example, and can be formed by electroplating. In this embodiment, the second upper planar coil 42 has an auxiliary outer end portion 42c, which overlaps with the outer end portion 41a of the first upper planar coil 41, sandwiching an insulating layer 30A. The auxiliary outer end portion 42c is electrically connected to the outer end portion 41a via a through conductor (not shown) penetrating the insulating layer 30A. By providing the auxiliary outer end portion 42c, the outer end portion is made into a double-layer structure, increasing the contact area between the outer end portion and the external terminal electrode, thus improving connectivity.

[0037] The thicknesses of the first upper planar coil 41 and the second upper planar coil 42 can be designed within a range of, for example, 20 to 40 μm (30 μm as an example). The thicknesses of the first upper planar coil 41 and the second upper planar coil 42 can be the same or different. In the upper coil structure 40A, the first upper planar coil 41, the second upper planar coil 42, and the through conductor 47 disposed in the insulating layer 30A are used to form a first coil C1 having a coil axis Z.

[0038] The first upper insulator 51 and the second upper insulator 52 are covered by an insulating layer 30A, a first upper planar coil 41, and a second upper planar coil 42 sandwiched in the thickness direction of the substrate 10. Both the first upper insulator 51 and the second upper insulator 52 are made of insulating resin. For example, they may be made of PP resin or BT resin. The first upper insulator 51 and the second upper insulator 52 may also be composite components containing resin and glass fiber (so-called prepreg). The first upper insulator 51 and the second upper insulator 52 can be formed, for example, by vacuum-pressing an insulating resin sheet from the thickness direction of the substrate 10. Thus, the wires of the first upper planar coil 41 and the second upper planar coil 42 are buried between resin materials, and the inner and outer surfaces of the first upper planar coil 41 and the second upper planar coil 42 are covered by resin materials. As described later, the first upper insulator 51 and the second upper insulator 52 are formed by sandblasting.

[0039] The thickness of the first upper insulator 51 and the thickness of the second upper insulator 52 can be designed within a range of, for example, 40 to 50 μm (45 μm as an example). The thickness of the first upper insulator 51 and the thickness of the second upper insulator 52 can be the same or different.

[0040] like Figure 3 As shown, the lower coil structure 40B is disposed on the lower surface 30b of the coil overlap portion 31 of the magnetic sheet 30. The lower coil structure 40B is composed of an insulating layer 30B, a first lower planar coil 43, a second lower planar coil 44, a first lower insulator 53, and a second lower insulator 54, and has a through hole 45B.

[0041] Similar to the insulating layer 30A of the upper coil structure 40A, the insulating layer 30B of the lower coil structure 40B has a flat plate shape (e.g., sheet or layer) and extends parallel to the magnetic sheet 30. Viewed in the thickness direction, the insulating layer 30B has substantially the same shape as the magnetic sheet 30. Like the magnetic sheet 30 and the insulating layer 30A, the insulating layer 30B has: an elliptical annular coil overlap portion 31 extending along the long side of the body 10; and a pair of frame portions 34A, 34B extending along the short side of the body 10 and sandwiching the coil overlap portion 31 from both sides. An elliptical opening 32 extending along the long side of the body 10 is provided in the central portion of the coil overlap portion 31. The thickness t2 of the insulating layer 30B can be designed within, for example, a range of 10 to 50 μm (15 μm as an example). The thickness t2 of the insulating layer 30B can be the same as or different from the thickness t1 of the insulating layer 30A. Similar to insulating layer 30A, insulating layer 30B is made of insulating material, for example, it may be made of resin material such as BT resin.

[0042] The first lower planar coil 43 is a generally elliptical spiral-shaped hollow coil wound around the opening 32 of the coil overlap portion 31 within the same layer on the upper surface 30a of the insulating layer 30B. The first lower planar coil 43 shares a coil axis Z with the upper planar coils 41 and 42. The number of turns of the first lower planar coil 43 can be one or more turns. In this embodiment, the number of turns of the first lower planar coil 43 is 2 to 3. The first lower planar coil 43 has an outer end portion 43a and an inner end portion 43b. The outer end portion 43a is provided on the frame portion 34A, extends to the end face 10a of the body 10, and is exposed from the end face 10a. The inner end portion 43b is provided at the edge of the opening 32. A through conductor 48 extending along the thickness direction of the insulating layer 30B is provided on the insulating layer 30B in such a way that it penetrates the insulating layer 30B at a position overlapping with the inner end portion 43b of the first lower planar coil 43. The first lower planar coil 43 is made of Cu, for example, and can be formed by electroplating. In this embodiment, the first lower planar coil 43 has an auxiliary outer end 43c, which overlaps with the outer end 44a of the second lower planar coil 44 (described later) by sandwiching an insulating layer 30B. The auxiliary outer end 43c is electrically connected to the outer end 44a via a through conductor (not shown) penetrating the insulating layer 30B. By providing the auxiliary outer end 43c, the outer end is made into a double-layer structure, increasing the contact area between the outer end and the external terminal electrode and improving connectivity.

[0043] The second lower planar coil 44 is symmetrical to the first lower planar coil 43. More specifically, the second lower planar coil 44 has a shape that reverses the first lower planar coil 43 about an axis parallel to the short side of the body 10. The second lower planar coil 44 shares a coil axis Z with the upper planar coils 41 and 42 and the first lower planar coil 43. The outer end portion 44a of the second lower planar coil 44 is provided in the frame portion 34B, extends to the end face 10b of the body 10, and is exposed from the end face 10b. The inner end portion 44b of the second lower planar coil 44 overlaps with a through conductor 48 provided in the insulating layer 30B. Therefore, the inner end portion 44b of the second lower planar coil 44 is electrically connected to the inner end portion 43b of the first lower planar coil 43 via the through conductor 48. The second lower planar coil 44 is made of Cu, for example, and can be formed by electroplating. In this embodiment, the second lower planar coil 44 has an auxiliary outer end portion 44c, which overlaps with the outer end portion 43a of the first lower planar coil 43, sandwiched by an insulating layer 30B. The auxiliary outer end portion 44c is electrically connected to the outer end portion 43a via a through conductor (not shown) penetrating the insulating layer 30B. By providing the auxiliary outer end portion 44c, the outer end portion is made into a double-layer structure, increasing the contact area between the outer end portion and the external terminal electrode, thus improving connectivity.

[0044] The thicknesses of the first lower planar coil 43 and the second lower planar coil 44 can be designed within, for example, a range of 20 to 40 μm (30 μm as an example). The thicknesses of the first lower planar coil 43 and the second lower planar coil 44 can be the same or different. In the lower coil structure 40B, the first lower planar coil 43, the second lower planar coil 44, and the through conductor 48 disposed in the insulating layer 30B are used to form a second coil C2 having a coil axis Z.

[0045] The first lower insulator 53 and the second lower insulator 54 are covered by an insulating layer 30B, a first lower planar coil 43, and a second lower planar coil 44 sandwiched in the thickness direction of the substrate 10. Both the first lower insulator 53 and the second lower insulator 54 are made of insulating resin. For example, they may be made of PP resin or BT resin. The first lower insulator 53 and the second lower insulator 54 may also be composite components containing resin and glass fiber (so-called prepreg). The first lower insulator 53 and the second lower insulator 54 can be formed, for example, by vacuum-pressing an insulating resin sheet from the thickness direction of the substrate 10. Thus, the wires of the first lower planar coil 43 and the second lower planar coil 44 are buried between resin materials, and the inner and outer surfaces of the first lower planar coil 43 and the second lower planar coil 44 are covered by resin materials. As described later, the first lower insulator 53 and the second lower insulator 54 are formed by sandblasting.

[0046] The thickness of the first lower insulator 53 and the thickness of the second lower insulator 54 can be designed within a range of, for example, 40 to 50 μm (45 μm as an example). The thickness of the first lower insulator 53 and the thickness of the second lower insulator 54 can be the same or different.

[0047] In this embodiment, such as Figure 6 As shown, the thickness T1 of the portion of the body 10 overlapping with the upper coil structure 40A on the upper surface 10c side and the thickness T2 of the portion of the body 10 overlapping with the lower coil structure 40B on the lower surface 10d side are designed to be equal. However, the thicknesses T1 and T2 can also be different.

[0048] Two pairs of external terminal electrodes 60A, 60B, 60C, and 60D are each provided on the parallel end faces 10a and 10b of the body 10.

[0049] Of the pair of external terminal electrodes 60A and 60B disposed on end face 10a, external terminal electrode 60A is connected to the outer end 43a of the first lower planar coil 43 of the lower coil structure 40B, and external terminal electrode 60B is connected to the outer end 41a of the first upper planar coil 41 of the upper coil structure 40A. When viewed from end face 10a, external terminal electrode 60A is biased towards side 10f and covers the vicinity of side 10f on end face 10a. External terminal electrode 60B is biased towards side 10e and covers the vicinity of side 10e on end face 10a. When viewed from end face 10a, external terminal electrodes 60A and 60B are separated by a predetermined uniform width.

[0050] Of the pair of external terminal electrodes 60C and 60D disposed on end face 10b, external terminal electrode 60C is connected to the outer end 44a of the second lower planar coil 44 of the lower coil structure 40B, and external terminal electrode 60D is connected to the outer end 42a of the second upper planar coil 42 of the upper coil structure 40A. External terminal electrode 60C is biased toward side 10f and covers the vicinity of side 10f on end face 10b. External terminal electrode 60D is biased toward side 10e and covers the vicinity of side 10e on end face 10b. When viewed from end face 10b, external terminal electrode 60C and external terminal electrode 60D are separated by a predetermined uniform width.

[0051] External terminal electrodes 60A on end face 10a and 60C on end face 10b are positioned at corresponding locations along the long side of the body 10. Similarly, external terminal electrodes 60B on end face 10a and 60D on end face 10b are positioned at corresponding locations along the long side of the body 10.

[0052] External terminal electrodes 60A, 60B, 60C, and 60D are all bent into an L-shape, continuously covering end faces 10a and 10b and the upper surface 10c. In this embodiment, external terminal electrodes 60A, 60B, 60C, and 60D are made of resin electrodes, for example, of resin containing Ag powder.

[0053] In coil component 1, when a voltage is applied between external terminal electrodes 60B and 60D, current flows through the first coil C1 of the upper coil structure 40A, generating magnetic flux around the first coil C1. Similarly, when a voltage is applied between external terminal electrodes 60A and 60C, current flows through the second coil C2 of the lower coil structure 40B, generating magnetic flux around the second coil C2. At this time, magnetic coupling can be generated between the first coil C1 and the second coil C2, which share the same coil axis Z.

[0054] like Figure 4 As shown, in the magnetic sheet 30 of coil component 1, the coil overlap portion 31 overlapping with coils C1 and C2 is elliptical and annular. Both the portion corresponding to the inner circumferential region of coils C1 and C2 and the portion corresponding to the outer circumferential region of coils C1 and C2 are removed. The inner and outer circumferential portions of the through holes 45A and 45B of coil structure 40A and 40B of coil component 1 are also removed. Therefore, the inner core and outer core of coils C1 and C2 are formed by filling the two portions with the magnetic material constituting the body 10.

[0055] In coil component 1, such as Figure 7As shown, the inner edges of the coil structures 40A and 40B (i.e., the edges dividing the through holes 45A and 45B) recede relative to the inner edge of the magnetic sheet 30 (i.e., the edge dividing the through hole 32). In this embodiment, the inner edges of the magnetic sheet 30 and the inner edges of the coil structures 40A and 40B have a cross-sectional shape that is bent into a dog-leg shape, and the inner edges of the coil structures 40A and 40B gradually recede as they move away from the magnetic sheet 30 in the coil axis Z direction. For example, considering two points in the coil axis Z direction, the inner edge of position P1 on the side away from the magnetic sheet 30 recedes more than the inner edge of position P2 on the side closer to the magnetic sheet 30. Furthermore, in this embodiment, the coil axis Z... Figure 7 In the cross-section shown, the shapes of the coil structures 40A and 40B are approximately linearly symmetrical with respect to the imaginary straight line L orthogonal to the coil axis Z. Furthermore, in this embodiment, the magnetic sheet 30 is in contact with the metal powder contained in the resin 12 containing metallic magnetic powder that constitutes the body 10 within its inner edge.

[0056] Here, the method for forming the cross-sectional shape of the magnetic sheet 30 and the coil structures 40A and 40B described above will be explained.

[0057] Figure 8 This indicates the state after vacuum stamping of the magnetic sheet 30 and coil structures 40A and 40B, i.e., before the through holes are formed. In this state, sandblasting is performed from the top and bottom (i.e., the Z-direction of the coil axis) using a photoresist mask M to form the magnetic sheet 30 and coil structures 40A and 40B. The result is as follows: Figure 9 As shown, through holes 32 are provided on the magnetic sheet 30, and through holes 45A and 45B are provided on the coil structures 40A and 40B. Simultaneously, the outer edges of the magnetic sheet 30 and the coil structures 40A and 40B are formed. At this time, by appropriately adjusting the sandblasting conditions (e.g., particle size and projection pressure), the aforementioned dog-leg shape cross-sectional shape is obtained. Furthermore, the bending condition of the dog-leg shape can be adjusted.

[0058] Furthermore, the outer periphery of coil structures 40A and 40B can be either removed or not removed.

[0059] In coil component 1, leakage flux is easily generated due to the magnetic sheet 30 located between the first coil C1 and the second coil C2 (i.e., magnetic flux passing only through the first coil C1 and only through the second coil C2). The coupling coefficient can be adjusted by increasing or decreasing the leakage flux using the magnetic sheet 30. In this embodiment, the inner edge of the magnetic sheet 30 is in contact with the metal powder contained in the resin 12 containing metallic magnetic powder constituting the body 10 (i.e., there is no gap between the magnetic sheet 30 and the metal powder), therefore, the magnetic flux generated in coils C1 and C2 easily surrounds the magnetic sheet 30. For example, by increasing the permeability of the magnetic sheet 30, the leakage flux can be increased and the coupling coefficient can be reduced. In addition, by increasing the thickness of the magnetic sheet 30, the permeability of the magnetic sheet 30 can be increased. In this embodiment, the magnetic permeability of the magnetic sheet 30 is higher than that of the substrate material constituting the body 10 (i.e., the resin 12 containing metallic magnetic powder), and it is designed to have a higher permeability than that of the insulators 52 and 53 adjacent to the magnetic sheet 30 in the thickness direction. In particular, by increasing the permeability of the magnetic sheet 30 in the planar direction (the direction orthogonal to the coil axis Z), the leakage flux is effectively increased. The permeability of the magnetic sheet 30 can be adjusted by, for example, the thickness of the magnetic sheet 30, or the form, type, and proportion of the magnetic powder.

[0060] In this embodiment, such as Figure 7 As shown, the magnetic powder p contained in the magnetic sheet 30 is flat, and each magnetic powder extends along the surface direction of the magnetic sheet 30. In this magnetic sheet 30, the permeability in the surface direction is higher than the permeability in the thickness direction.

[0061] In coil component 1, it is believed that due to the use of magnetic sheet 30, magnetic saturation is easily generated on the magnetic sheet 30, thus reducing the DC superposition characteristics of coil component 1. However, as... Figure 7 As shown, because the inner edges of coil structures 40A and 40B are recessed relative to the inner edge of magnetic sheet 30, they form a structure in which the magnetic flux generated in coils C1 and C2 can easily be wound around, thus suppressing the reduction in DC superposition characteristics caused by the use of magnetic sheet 30. Alternatively, either the inner edge of coil structures 40A and 40B may be recessed relative to the inner edge of magnetic sheet 30.

[0062] Furthermore, the coil structures 40A and 40B are configured such that their outer edges are also recessed relative to the outer edge of the magnetic sheet 30, thus making it easier for the magnetic flux generated in coils C1 and C2 to circulate. This further suppresses the reduction in DC superposition characteristics caused by the use of the magnetic sheet 30. Alternatively, either the outer edge of the coil structures 40A and 40B may be recessed relative to the outer edge of the magnetic sheet 30.

[0063] Furthermore, the present invention is not limited to the embodiments described above, and various methods can be employed. For example, the number of turns of the planar coil constituting the coil can be appropriately increased or decreased. Alternatively, it can be configured to include three or more coils within a single coil body. The coils contained in each coil structure are not limited to a two-layer structure of planar coils; they can be a single-layer structure or composed of three or more layers. In addition, the insulating layer and insulator (upper insulator, lower insulator) contained in each coil structure can be appropriately omitted.

Claims

1. A coil component, wherein, have: The base body is made of resin containing metal powder; A pair of coil structures disposed within the body, each comprising a pair of coils having a pair of ends that overlap each other in the coil axial direction and extend to the surface of the body; Two pairs of external terminals are disposed on the surface of the body and are respectively connected to the ends of the pair of coils; as well as A magnetic sheet is disposed within the body of the coil and positioned axially between the pair of coil structures. Through holes extending along the axial direction of the coils are respectively provided on the pair of coil structures and the magnetic sheet, and the inner edge of at least one of the pair of coil structures gradually recedes from the position closest to the inner edge of the magnetic sheet to the position farthest from the inner edge.

2. The coil component according to claim 1, wherein, Either of the pair of coil structures recedes relative to the inner edge of the magnetic sheet.

3. The coil component according to claim 1, wherein, With respect to at least one of the pair of coil structures, the inner edge of the coil on the side axially away from the magnetic sheet is positioned further back than the inner edge on the side closer to the magnetic sheet.

4. The coil component according to any one of claims 1 to 3, wherein, In a cross section containing the coil axis, the shape of the pair of coil structures is linearly symmetrical with respect to a line orthogonal to the coil axis.

5. The coil component according to any one of claims 1 to 3, wherein, The magnetic sheet is in contact with the metal powder contained in the resin containing metal powder that constitutes the body in the inner edge.

6. The coil component according to any one of claims 1 to 3, wherein, The thickness of the body portions that overlap with the pair of coil structures along the axial direction of the coil is equal.

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