Coil component

Abstract

To suppress the diffusion of ferrite particles in a coil component that has a sintered ferrite body and a coil conductor.SOLUTION: A coil component 100 includes a ferrite sintered body 10 having main surfaces 11, 12 and a side surface 13 located opposite to each other, a coil conductor 30 arranged on the main surface 11 side of the ferrite sintered body 10, and a resin layer 20 covering at least a part of the main surface 11, the main surface 12 and the side surface 13 of the ferrite sintered body 10. This makes it possible to suppress diffusion of ferrite particles.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a coil component having a structure in which a planar coil is arranged on one surface of a plate-shaped ferrite via a magnetic holder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-184390 Summary of the Invention [Problem to be solved by the invention]

[0004] However, since ferrite, which is a sintered body, is brittle, there is a problem in that ferrite particles diffuse into electronic devices using the coil component described in Patent Document 1.

[0005] In the present disclosure, a technique for suppressing the diffusion of ferrite particles in a coil component having a ferrite sintered body and a coil conductor is described. [Means for solving the problem]

[0006] A coil component according to one embodiment of the present disclosure comprises a ferrite sintered body having a first main surface, a second main surface located opposite the first main surface, and a side surface connecting the outer peripheral edge of the first main surface and the outer peripheral edge of the second main surface, a coil conductor arranged on the first main surface side of the ferrite sintered body, and a resin layer covering at least a portion of the first main surface, the second main surface, and the side surface of the ferrite sintered body. [Effects of the Invention]

[0007] According to the present disclosure, a technique for suppressing the diffusion of ferrite particles in a coil component having a ferrite sintered body and a coil conductor is provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic cross-sectional view showing the appearance of a coil device 100 according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic plan view showing the appearance of the coil device 100, as viewed from one surface side. [Figure 3] FIG. 3 is a schematic plan view showing the appearance of the coil device 100, as viewed from the other surface side. [Figure 4] FIG. 4 is an enlarged view of area 40 shown in FIG. [Figure 5] FIG. 5 is a partial cross-sectional view of a coil component according to a first modified example. [Figure 6] FIG. 6 is a partial cross-sectional view of a coil component according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0010] Fig. 1 is a schematic cross-sectional view showing the appearance of a coil device 100 according to an embodiment of the present disclosure. Fig. 2 and Fig. 3 are schematic plan views showing the appearance of the coil device 100, viewed from opposite sides.

[0011] As shown in FIGS. 1 to 3 , the coil component 100 according to this embodiment is disk-shaped and includes a ferrite sintered body 10, a resin layer 20 covering the surface of the ferrite sintered body 10, and a coil conductor 30. While the coil component 100 according to this embodiment has a substantially circular planar shape, the planar shape of the coil component 100 is not particularly limited and may be, for example, rectangular. The ferrite sintered body 10 functions as a magnetic path for the magnetic flux generated by the coil conductor 30. The magnetic permeability of the ferrite sintered body 10 may be 100 to 200. In contrast, in the case of a magnetic sheet in which metal magnetic powder is mixed with a resin, the magnetic permeability of the magnetic sheet is approximately 20 to 80. As such, since the ferrite sintered body 10 is used as the magnetic path in this embodiment, the magnetic permeability is higher than when a magnetic sheet or the like is used, and the inductance of the coil conductor 30 is further increased.

[0012] The ferrite sintered body 10 is made of a rigid bulk ferrite material and has a first main surface 11 and a second main surface 12 located opposite each other, and a side surface 13 connecting the outer peripheral edge 11A of the main surface 11 and the outer peripheral edge 12A of the main surface 12. The main surfaces 11 and 12 are substantially parallel to each other, and the main surfaces 11, 12 and the side surface 13 are substantially perpendicular to each other. However, because manufacturing errors and variations may occur during the manufacturing of the ferrite sintered body 10, the main surfaces 11 and 12 do not have to be strictly parallel, and the main surfaces 11, 12 and the side surface 13 do not have to be strictly perpendicular. Furthermore, the outer peripheral edge 11A of the main surface 11 and the outer peripheral edge 12A of the main surface 12 may be curved as shown in FIG. 1. The thickness T10 of the ferrite sintered body 10, i.e., the distance between the main surfaces 11 and 12, is, for example, several tens of micrometers.

[0013] The resin layer 20 covers the entire main surfaces 11, 12 of the ferrite sintered body 10, and also wraps around from the outer peripheral edges 11A, 12A of the main surface 11 to part of the side surface 13, thereby covering at least part of the side surface 13. Of the resin layer 20, the part covering the main surface 11 of the ferrite sintered body 10 constitutes a first resin region 21, the part covering the main surface 12 of the ferrite sintered body 10 constitutes a second resin region 22, and the part covering the side surface 13 of the ferrite sintered body 10 constitutes a third resin region 23.

[0014] The thickness T21 of the first resin region 21 of the resin layer 20 and the thickness T22 of the second resin region 22 of the resin layer 20 may both be thinner than the thickness T10 of the ferrite sintered body 10. The thickness T21 of the first resin region 21 and the thickness T22 of the second resin region 22 may be, for example, 10 to 20 μm. The thickness T21 of the first resin region 21 and the thickness T22 of the first resin region 22 may be the same as each other.

[0015] The first resin region 21, the second resin region 22, and the third resin region 23 of the resin layer 20 may be integral. In this case, the entire surface of the ferrite sintered body 10, consisting of the main surfaces 11 and 12 and the side surface 13, is covered with the resin layer 20 without being exposed. Alternatively, the first resin region 21 and a portion of the third resin region 23 covering the first side surface region 13A of the side surface 13 may be integral, the second resin region 22 and a portion of the third resin region 23 covering the second side surface region 13B of the side surface 13 may be integral, and the portion covering the first side surface region 13A of the side surface 13 of the ferrite sintered body 10 and the portion covering the second side surface region 13B of the side surface 13 of the ferrite sintered body 10 may be connected to each other. In other words, the first resin region 21 and the second resin region 22 of the resin layer 20 may be connected to each other via the third resin region 23. However, it is not necessary for the entire side surface 13 of the ferrite sintered body 10 to be covered with the resin layer 20, and a part of the side surface 13 of the ferrite sintered body 10 may be exposed without being covered with the resin layer 20. In addition, in this embodiment, the resin layer 20 covers the surface of the ferrite sintered body 10 in a tight contact state, but a part of the resin layer 20 may cover the surface via a gap.

[0016] In this way, since most or all of the ferrite sintered body 10 is covered with the resin layer 20, even if ferrite particles are generated, the particles are prevented from diffusing to the outside. In particular, particles are likely to be generated at the outer peripheral edges 11A, 12A of the ferrite sintered body 10, and the diffusion of particles is effectively prevented by covering these parts with the resin layer 20. As a result, even when the coil component 100 according to this embodiment is mounted in an electronic device such as a portable wireless terminal, ferrite particles are unlikely to diffuse into the electronic device, thereby improving the reliability of the electronic device.

[0017] The coil conductor 30 is disposed on the main surface 11 side of the ferrite sintered body 10 so as to be embedded in the first resin region 21 of the resin layer 20. The surface of the coil conductor 30 is exposed from the first resin region 21 of the resin layer 20, so that the first resin region 21 of the resin layer 20 is located between the main surface 11 of the ferrite sintered body 10 and the coil conductor 30. In the example shown in FIG. 2, the coil conductor 30 winds about four times in a planar spiral shape. One end (inner peripheral end) of the coil conductor 30 forms the terminal portion 30A, and the other end (outer peripheral end) of the coil conductor 30 forms the terminal portion 30B. In the example shown in FIG. 2, the planar shape of the terminal portions 30A and 30B is substantially circular, and the diameter thereof is larger than the pattern width of the coil conductor 30 in regions other than the terminal portions 30A and 30B.

[0018] As shown in FIG. 1 , a coil component 100 according to this embodiment has a through hole 110. The through hole 110 is composed of a first through hole 10A that penetrates the ferrite sintered body 10, a second through hole 21A that penetrates the first resin region 21 of the resin layer 20, and a third through hole 22A that penetrates the second resin region 22 of the resin layer 20. The through hole 110 is provided at a position overlapping with the terminal portion 30A of the coil conductor 30, so that the terminal portion 30A of the coil conductor 30 is exposed at the bottom of the through hole 110. Another through hole 120 provided in the coil component 100 penetrates the ferrite sintered body 10, the first resin region 21 of the resin layer 20, and the second resin region 22 of the resin layer 20, and is provided at a position overlapping with the terminal portion 30B of the coil conductor 30, so that the terminal portion 30B of the coil conductor 30 is exposed at the bottom of the another through hole 120. By providing such through holes 110, 120, when the coil component 100 according to this embodiment is mounted in an electronic device, it becomes possible to connect to the coil conductor 30 from the second resin region 22 side of the resin layer 20. The inner walls of the through holes 110, 120 do not constitute the surface of the ferrite sintered body 10 covered with the resin layer 20.

[0019] FIG. 4 is an enlarged view of area 40 shown in FIG.

[0020] As shown in FIG. 4 , the coil conductor 30 is embedded in the first resin region 21 of the resin layer 20 so that a portion of the coil conductor 30 is exposed from the surface 21B of the first resin region 21 of the resin layer 20. The coil conductor 30 includes a seed portion S containing resin and a main portion M made of a metal material, laminated on the second surface S2 of the seed portion S. The first surface S1 of the seed portion S is exposed from the first resin region 21 of the resin layer 20. The first surface S1 and the second surface S2 are located on opposite sides of each other. The coil conductor 30 may have a shape having a portion whose radial width narrows from the seed portion S side toward the main portion M side. Here, the radial direction refers to the direction from the inner periphery to the outer periphery of the coil conductor 30. The coil conductor 30 is formed on the surface of a substrate (not shown), but the substrate may be subsequently peeled off. In this case, the coil component 100 does not include a substrate. This reduces the thickness of the coil component 100 in the coil axis direction.

[0021] The coil conductor 30 is embedded in the first resin region 21 of the resin layer 20 so that the first surface S1 of the seed portion S is exposed from the surface 21B of the first resin region 21 of the resin layer 20. The metal material constituting the main body portion M of the coil conductor 30 may be Cu. The seed portion S may contain a material that functions as a catalyst when the main body portion M is plated. The thickness of the main body portion M may be thicker than the thickness of the seed portion S. This makes it possible to reduce the resistance value of the coil conductor 30.

[0022] The main body portion M may be entirely embedded in the first resin region 21 of the resin layer 20 without being exposed from the first resin region 21 of the resin layer 20. Alternatively, a portion of the main body portion M, for example, a portion covering the side surface of the seed portion S, may be exposed from the first resin region 21 of the resin layer 20. Also, a portion of the side surface of the portion of the main body portion M laminated on the second surface S2 of the seed portion S may be exposed from the first resin region 21 of the resin layer 20. In the example shown in FIG. 4, the seed portion S is also embedded in the first resin region 21 of the resin layer 20, and the surface 21B of the first resin region 21 of the resin layer 20 and the first surface S1 of the seed portion S form the same plane.

[0023] The first resin region 21 of the resin layer 20 includes a portion located between the coil conductor 30 and the ferrite sintered body 10 so as to be sandwiched between them. The first resin region 21 of the resin layer 20 includes filler particles F and a binder resin R. The filler particles F may be spherical. By using spherical filler particles F, the strength of the first resin region 21 of the resin layer 20 is increased while voids are less likely to occur around the coil conductor 30.

[0024] The filler particles F may be made of a non-magnetic inorganic material such as alumina, or may be made of a magnetic material such as ferrite or an Fe-based alloy magnetic material. Examples of Fe-based alloy magnetic materials include permalloy, sendust, Fe-Si-Cr, Fe-Si, carbonyl iron, Fe-based alloy amorphous powder containing at least Fe-Si-B, or Fe-based alloy nanocrystalline powder containing at least Fe-BP-Cu. If a magnetic material is used as the filler particles F, the inductance of the coil conductor 30 can be further increased. The average particle size (D 50 ) is, for example, 2 to 10 μm. The average particle size is the D50 value in laser diffraction particle size distribution measurement.

[0025] Examples of materials for the binder resin R include acrylic resin, polyester resin, polyethylene resin, polyvinyl chloride resin, polyvinyl butyral resin, polyurethane resin, polyester urethane resin, cellulose resin, ABS (acrylonitrile-butadiene-styrene) resin, nitrile-butadiene rubber, styrene-butadiene rubber, epoxy resin, phenol resin, amide resin, polyester elastomer, polyamide elastomer, etc. The elongation percentage determined by a tensile test of the resin used as the binder resin R may be greater than 400%.

[0026] The second resin region 22 of the resin layer 20 may have the same configuration as the first resin region 21 of the resin layer 20 described above. The third resin region 23 of the resin layer 20 may also have the same configuration as the first resin region 21 of the resin layer 20 described above.

[0027] The ferrite sintered body 10 may be an aggregate of pieces 14 divided by cracks extending in the thickness direction, which is the coil axis direction. This makes it possible to prevent damage to the ferrite sintered body 10. The extension direction of the cracks does not need to be strictly the thickness direction; cracks inclined relative to the thickness direction or cracks extending in the planar direction may be included. Furthermore, the binder resin R constituting the resin layer 20 may permeate the gaps (cracks) between the pieces 14 of the ferrite sintered body 10. This fixes the pieces 14 together with the binder resin R, thereby increasing the strength of the ferrite sintered body 10. Note that the permeation of the binder resin R into the gaps between the pieces 14 of the ferrite sintered body 10 may be limited to only some of the gaps, or may be limited to the surface layer of the ferrite sintered body 10.

[0028] 4, the surface of the main body M constituting the terminal portion 30A of the coil conductor 30 may be covered with plating layers P1 and P2. The plating layer P1 is made of, for example, Ni, and the plating layer P2 is made of, for example, Au. By using the plating layer P2 made of, for example, Au on the surface of the terminal portion 30A exposed at the bottom of the through hole 110 instead of the main body M made of, for example, Cu, the reliability of the coil component 100 is improved. Although not shown, the surface of the main body M constituting the terminal portion 30B of the coil conductor 30 may also be covered with plating layers P1 and P2.

[0029] As described above, in the coil component 100 according to this embodiment, the ferrite sintered body 10 and the coil conductor 30 are arranged to overlap in the axial direction, and the surface of the ferrite sintered body 10 is covered with the resin layer 20, which makes it possible to suppress the diffusion of ferrite particles. Moreover, since the coil conductor 30 is embedded in the first resin region 21 of the resin layer 20, it is possible to reduce the overall thickness of the coil component 100.

[0030] The above describes the embodiments of the present disclosure, but the present disclosure is not limited to the above embodiments, and various modifications are possible within the scope of the present disclosure, and it goes without saying that these modifications are also included within the scope of the present disclosure.

[0031] For example, in the resin layer 20, when the portions of the first resin region 21 and the third resin region 23 that cover the first side region 13A of the side surface 13 are integral, and the portions of the second resin region 22 and the third resin region 23 that cover the second side region 13B of the side surface 13 are integral, the first resin region 21 of the resin layer 20 and the second resin region 22 of the resin layer 20 may be connected so as to overlap on the side surface 13, as shown in Figure 5, or the ends of the first resin region 21 and the second resin region 22 of the resin layer 20 may be folded outward and the folded portions may be connected to each other, as shown in Figure 6.

[0032] The technology according to the present disclosure includes, but is not limited to, the following configuration examples.

[0033] A coil component according to an embodiment of the present disclosure includes a ferrite sintered body having a first main surface, a second main surface opposite the first main surface, and a side surface connecting an outer peripheral edge of the first main surface with an outer peripheral edge of the second main surface, a coil conductor disposed on the first main surface side of the ferrite sintered body, and a resin layer covering at least a portion of the first main surface, the second main surface, and the side surface of the ferrite sintered body, thereby making it possible to suppress diffusion of ferrite particles.

[0034] In the coil component, the resin layer may have a first resin region covering the first main surface of the ferrite sintered body, a second resin region covering the second main surface of the ferrite sintered body, and a third resin region covering the side surface of the ferrite sintered body, and the first and second resin regions of the resin layer may be connected to each other via the third resin region, thereby making it possible to more effectively suppress the diffusion of ferrite particles.

[0035] In the coil component, the first and second main surfaces and side surfaces of the ferrite sintered body may be entirely covered with a resin layer, which prevents ferrite particles from diffusing.

[0036] In the coil component, the resin layer may contain filler particles, which increases the strength of the resin layer. In this case, the filler particles may contain a magnetic material. This allows the ferrite sintered body and the resin layer as a whole to function as a magnetic path for magnetic flux, thereby increasing the inductance of the coil conductor.

[0037] In the coil component, the thickness of the resin layer may be thinner than the thickness of the ferrite sintered body, which makes it possible to reduce the overall thickness while maintaining high inductance.

[0038] In the coil component, the resin layer may include a portion located between the first main surface of the ferrite sintered body and the coil conductor, which enables communication with an external device located on the first main surface side of the ferrite sintered body and allows a substrate including a metal member to be located on the second main surface side of the ferrite sintered body.

[0039] In the coil component, the coil conductor may be embedded in a resin layer, which allows the overall thickness to be reduced.

[0040] In the coil component, the coil conductor includes a seed portion containing resin and having first and second surfaces opposite each other, and a body portion made of a metallic material laminated on the second surface of the seed portion, and the coil conductor may be embedded in the resin layer so that the first surface of the seed portion is exposed from the resin layer, thereby protecting the body portion made of a metallic material by the seed layer exposed to the outside.

[0041] In the coil component, the ferrite sintered body has a first through hole, a portion of the resin layer covering the first main surface of the ferrite sintered body has a second through hole, and a portion of the resin layer covering the second main surface of the ferrite sintered body has a third through hole, and the first through hole, the second through hole, and the third through hole may overlap with an end of the coil conductor, thereby enabling connection to the coil conductor from the second main surface side of the ferrite sintered body. [Explanation of symbols]

[0042] 10 Ferrite sintered body 11,12 Main surfaces 11A, 12A outer edge 13 Side 13A First Side Region 13B Second lateral area 14 pieces 20 Resin layer 21 First Resin Area 21B Surface of first resin region 22 Second Resin Area 23 The third resin area 30 Coil conductor 30A,30B terminal section 40 areas 100 Coil parts 110,120 Through holes F filler particles M Main body P1, P2 plating layer R Binder resin S Seed Section

Claims

1. a ferrite sintered body having a first main surface, a second main surface located opposite to the first main surface, and a side surface connecting an outer peripheral edge of the first main surface and an outer peripheral edge of the second main surface; a coil conductor disposed on the first main surface side of the ferrite sintered body; a resin layer covering at least a portion of the first main surface, the second main surface, and the side surface of the ferrite sintered body; Equipped with Coil parts.

2. the resin layer has a first resin region covering the first main surface of the ferrite sintered body, a second resin region covering the second main surface of the ferrite sintered body, and a third resin region covering the side surface of the ferrite sintered body, the first resin region and the second resin region of the resin layer are connected to each other via the third resin region; The coil component according to claim 1 .

3. the first main surface, the second main surface, and the side surface of the ferrite sintered body are entirely covered with the resin layer; The coil component according to claim 1 .

4. The resin layer contains filler particles. The coil component according to claim 1 .

5. the filler particles include a magnetic material; The coil component according to claim 4 .

6. The thickness of the resin layer is thinner than the thickness of the ferrite sintered body. The coil component according to claim 1 .

7. the resin layer includes a portion located between the first main surface of the ferrite sintered body and the coil conductor. The coil component according to claim 1 .

8. The coil conductor is embedded in the resin layer. The coil component according to claim 7 .

9. the coil conductor includes a seed portion including a resin and having first and second surfaces opposite to each other, and a body portion made of a metal material and laminated on the second surface of the seed portion; the coil conductor is embedded in the resin layer such that the first surface of the seed portion is exposed from the resin layer. The coil component according to claim 8 .

10. the ferrite sintered body has a first through hole, a portion of the resin layer covering the first main surface of the ferrite sintered body has a second through hole, and a portion of the resin layer covering the second main surface of the ferrite sintered body has a third through hole; the first through hole, the second through hole, and the third through hole overlap with an end of the coil conductor; The coil component according to claim 7 .

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