Coil components

Abstract

To provide a coil component which hardly causes short-circuiting.SOLUTION: A coil component comprises: a core part; and a coil part which is obtained by winding a conductor into a coil-like shape. The coil part is formed inside the core part. The core part has a center core part which is located at a portion surrounded by an inner diameter of the coil part. The center core part comprises: a first center core part containing first soft magnetic metal particles; and a second center core part located around the first center core part and containing second soft magnetic metal particles. The first center core part has at least two facing surfaces which face each other. The facing surfaces are parallel to a winding axis direction of the coil part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to coil components. [Background technology]

[0002] Patent Document 1 discloses a coil component that includes a roughly hexagonal core in its central portion.

[0003] Patent document 2 discloses magnetic components including various T-shaped magnetic cores. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] U.S. Patent No. 9318251 [Patent Document 2] U.S. Patent No. 9959965 [Overview of the project] [Problems that the invention aims to solve]

[0005] This disclosure provides a coil component that is less prone to short circuits. [Means for solving the problem]

[0006] A coil component relating to one aspect of this disclosure is A coil component comprising a core portion and a coil portion formed by winding a conductor in a coil shape, wherein the coil portion is formed inside the core portion, The core portion has a central core located in the area surrounded by the inner diameter of the coil portion. The core portion comprises a first core portion containing first soft magnetic metal particles and a second core portion arranged around the first core portion and containing second soft magnetic metal particles, wherein the first core portion has at least two opposing surfaces facing each other, and the opposing surfaces are parallel to the winding axis direction of the coil portion. The average value of the deflection angle of the first soft magnetic metal particles with respect to the winding axis direction of the coil portion is different from the average value of the deflection angle of the second soft magnetic metal particles with respect to the winding axis direction of the coil portion.

[0007] In the above-described coil component, the shape of the first core portion may be a rectangular prism.

[0008] In any of the above coil components, the deflection angle of the first soft magnetic metal particles with respect to the winding axis direction of the coil portion is θα, and the deflection angle of the second soft magnetic metal particles with respect to the winding axis direction of the coil portion is θβ, and the average value of cos2θα may be greater than the average value of cos2θβ.

[0009] In any of the above coil components, let θα be the deflection angle of the first soft magnetic metal particles with respect to the winding axis direction of the coil portion, and θγ be the deflection angle of the third soft magnetic metal particles included in the outer portion of the coil portion with respect to the winding axis direction of the coil portion. The average value of cos2θα may be greater than the average value of cos2θγ.

[0010] In any of the above coil components, the deflection angle of the first soft magnetic metal particles with respect to the winding axis direction of the coil portion is θα, and the average value of cos2θα may be 0.1 or greater.

[0011] In any of the above coil components, the average aspect ratio of the first soft magnetic metal particles contained in the first core portion may be 1.1 or more and 5.0 or less.

[0012] The coil component relating to another aspect of this disclosure is: A coil component comprising a core portion and a coil portion formed by winding a conductor in a coil shape, wherein the coil portion is formed inside the core portion, The core portion has a central core located in the area surrounded by the inner diameter of the coil portion. The core portion consists of a first core portion containing first soft magnetic metal particles and a second core portion disposed around the first core portion and containing second soft magnetic metal particles. The first core portion has at least two opposing surfaces facing each other, and the opposing surfaces are parallel to the winding axis direction of the coil portion.

Brief Description of the Drawings

[0013] [Figure 1] It is a schematic cross-sectional view of an inductor according to an example of the first embodiment. [Figure 2] It is a schematic cross-sectional view taken along the line I-I of FIG. 1. [Figure 3] It is a schematic diagram for explaining the aspect ratio and degree of orientation of soft magnetic metal particles. [Figure 4] It is a perspective view of each member used in the process of manufacturing an inductor according to an example of the first embodiment. [Figure 5] It is a perspective view of each member used in the process of manufacturing an inductor according to an example of the second embodiment.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The embodiments of the present disclosure described below are examples for explaining the present disclosure. Various components according to the embodiments of the present disclosure, such as numerical values, shapes, materials, manufacturing processes, etc., can be modified or changed within a range where no technical problems occur.

[0015] In addition, the shapes and the like shown in the drawings of the present disclosure do not necessarily match the actual shapes and the like. This is because the shapes and the like may be modified for the purpose of explanation.

[0016] (First Embodiment) As shown in FIG. 1, an inductor 2, which is a kind of coil component according to the first embodiment of the present disclosure, has a coil portion 4 and a core portion 6. The coil portion 4 is formed by winding a conductor 5 in a coil shape. The core portion 6 has a core portion located in a portion surrounded by the inner diameter of the coil portion 4 and an outer peripheral portion which is the other portion.

[0017] For the inductor 2 according to the first embodiment of the present disclosure, the upper and lower surfaces of the core portion 6 are perpendicular to the Z-axis, and the side surfaces of the core portion 6 are perpendicular to the plane including the X-axis and the Y-axis. Also, the winding axis of the coil portion 4 is parallel to the Z-axis. However, the shape of the core portion 6 is not limited to the shape shown in FIG. 1.

[0018] Note that "parallel" in the present disclosure includes not only perfect parallelism but also substantial parallelism. That is, "parallel" in the present disclosure may include an error within the range of manufacturing tolerance or may include an error exceeding the range of manufacturing tolerance. Specifically, if line A is parallel to line B, it shall refer to the angle formed by line A and line B being 0° or more and 10° or less, unless otherwise specified. The same applies when one or both lines are replaced with a plane.

[0019] Note that "perpendicular" in the present disclosure includes not only perfect perpendicularity but also substantial perpendicularity. That is, "perpendicular" in the present disclosure may include an error within the range of manufacturing tolerance or may include an error exceeding the range of manufacturing tolerance. Specifically, if line A is perpendicular to line B, it shall refer to the angle formed by line A and line B being 80° or more and 100° or less, unless otherwise specified. The same applies when one or both lines are replaced with a plane.

[0020] The size of the inductor 2 according to the first embodiment of the present disclosure is not particularly limited. For example, the lower limit of the size of the portion excluding the lead portions 5a and 5b may be the size of a rectangular parallelepiped with a bottom surface of 2 mm × 2 mm and a height of 1 mm. The upper limit of the size of the portion excluding the lead portions 5a and 5b may be the size of a cube with a bottom surface of 20 mm × 20 mm and a height of 20 mm. The height is the length in the Z-axis direction in FIG. 1. Note that in FIG. 1, the illustration of the lead portions 5a and 5b of the coil portion 4 shown in FIG. 4 is omitted. The lead portions 5a and 5b formed at both ends of the conductor constituting the coil portion 4 are taken out to the outside of the core portion 6 shown in FIG. 1.

[0021] The conductor (wire) 5 constituting the coil section 4 is covered with an insulating coating layer on its outer circumference as needed. There are no particular restrictions on the material of the conductor 5. For example, the conductor 5 may be made of Cu, Al, Fe, Ag, Au, or an alloy containing these metals. There are no particular restrictions on the material of the insulating coating layer. The insulating coating layer may be made of, for example, polyurethane, polyamide-imide, polyimide, polyester, polyester-imide, and / or polyester-nylon.

[0022] There are no particular restrictions on the cross-sectional shape of the conductor 5. Examples of cross-sectional shapes include circular and rectangular shapes. In the first embodiment of this disclosure, the cross-sectional shape of the conductor 5 is circular.

[0023] The core portion 6 has at least soft magnetic metal particles. There are no particular restrictions on the material of the soft magnetic metal particles. The material of the soft magnetic metal particles is, for example, 、F The soft magnetic alloys may be e-Si alloys, Fe-Si-Al alloys, Fe-Si-Cr alloys, or permalloy (Fe-Ni alloys). There are no particular restrictions on the microstructure of the soft magnetic metal particles. The microstructure of the soft magnetic metal particles may be amorphous or may contain crystals. If the soft magnetic metal particles are amorphous, they may be flattened beforehand using a pulverizer or the like. There are no particular restrictions on the crystal grain size if the soft magnetic metal particles contain crystals. For example, they may be 1 μm or less.

[0024] The core portion 6 may have a thermosetting resin (binder). There are no particular restrictions on the type of thermosetting resin. Examples of thermosetting resins include epoxy resins, diallyl phthalate resins, phenolic resins, polyimides, polyamide-imides, silicone resins, and combinations thereof.

[0025] The core portion 6 has a central core portion located within the inner diameter of the coil portion 4. The central core portion consists of a first central core portion 6a and a second central core portion 6b arranged around the first central core portion 6a. The first central core portion 6a has at least two opposing surfaces that face each other. These opposing surfaces are parallel to the winding axis direction of the coil portion 4 (the Z-axis direction in Figure 1). This makes it easier to improve the inductance of the coil component. Furthermore, high inductance can be obtained even with a low molding pressure during the molding process, which will be described later. Lowering the molding pressure reduces the load on the coil, making it less likely for the coil to short-circuit. In addition, it becomes easier to design coil components with low coil resistance or miniaturized coil components.

[0026] The shape of the first core portion 6a may be any shape having at least two opposing faces. For example, a rectangular prism can be considered. The above-mentioned rectangular prisms include rectangular prisms with chamfered corners and edges, and rectangular prisms with rounded corners and edges. In the following description, the shape of the first core portion 6a will be assumed to be a rectangular prism.

[0027] There are no particular restrictions on the volume ratio of the first core portion 6a to the total core portion. For example, it may be 50% or more and 80% or less.

[0028] The distinction between the first core section 6a and the second core section 6b can be made, for example, by observing a cross-section perpendicular to the winding axis direction of the coil section 4 using an SEM. This is because there is a difference in contrast between the first core section 6a and the second core section 6b. The difference in contrast may be due to differences in the material of the soft magnetic metal particles contained in each core section, differences in the average aspect ratio, differences in the average degree of orientation, and differences in packing density. Furthermore, the difference in contrast may also be due to differences in the type of resin or inorganic material contained in each core section, and differences in the amount of resin or inorganic material contained. In other words, there is one or more differences between the first core section 6a and the second core section 6b, selected from differences in the material of the soft magnetic metal particles contained in each core section, differences in the average aspect ratio, differences in the average degree of orientation, differences in packing density, differences in the type of resin or inorganic material contained in each core section, and differences in the amount of resin or inorganic material contained.

[0029] The average degree of orientation of the soft magnetic metal particles may differ between the first core portion 6a and the second core portion 6b. The average degree of orientation of the soft magnetic metal particles contained in the first core portion 6a may be greater than the average degree of orientation of the soft magnetic metal particles contained in the second core portion, and / or the average degree of orientation of the soft magnetic metal particles contained in portions other than the core portions, particularly outside the coil portion 4. In this disclosure, the degree of orientation refers to the degree of orientation of the coil portion 4 in the winding axis direction.

[0030] Specifically, the deflection angle of the soft magnetic metal particles with respect to the winding axis of the coil section 4 is θ, and the average values ​​of the deflection angles of the soft magnetic metal particles may differ between the first core section 6a and the second core section 6b, and the average values ​​of cos2θ may also differ.

[0031] In the following description, the soft magnetic metal particles contained in the first core portion 6a will be referred to as the first soft magnetic metal particles. The soft magnetic metal particles contained in the second core portion 6b will be referred to as the second soft magnetic metal particles. The soft magnetic metal particles contained in the outer portion of the coil portion 4 as viewed from the winding axis of the coil will be referred to as the third soft magnetic metal particles.

[0032] Let θα be the deflection angle of the first soft magnetic metal particle with respect to the winding axis direction of the coil 4. Let θβ be the deflection angle of the second soft magnetic metal particle with respect to the winding axis direction of the coil 4. Let θγ be the deflection angle of the second soft magnetic metal particle with respect to the winding axis direction of the coil 4. The average value of cos2θα may be greater than the average value of cos2θβ and / or the average value of cos2θγ.

[0033] The mean value of cos2θα may be 0.1 or greater, 0.5 or greater, or 1.0.

[0034] The average aspect ratio of the first soft magnetic metal particles may be 1.1 or greater, 1.1 or greater and 5.0 or less, or 1.5 or greater and 5.0 or less.

[0035] The following describes how to calculate the average aspect ratio and the average value of cos2θα for the first soft magnetic metal particle. The same applies to the second and third soft magnetic metal particles. However, the aspect ratio and cos2θ are measured only for soft magnetic metal particles with a major axis diameter of 10 μm or more in the cross-sectional image described later. Soft magnetic metal particles with a major axis diameter of less than 10 μm in the cross-sectional image described later are not measured because soft magnetic metal particles with a small major axis diameter in the cross-sectional image may be the edges of soft magnetic metal particles that are actually relatively large. In that case, it cannot be said that the soft magnetic metal particle is being observed appropriately. Therefore, if soft magnetic metal particles with a small major axis diameter in the cross-sectional image are measured, the error in the calculated average aspect ratio and the average value of cos2θ may become large.

[0036] First, the inductor 2 is cut along line II in Figure 1. The resulting cross-section is shown in Figure 2. Next, the inductor 2 is cut so that it is parallel to the opposing surfaces of the first core portion 6a. Specifically, the inductor 2 is cut along line AA in Figure 2 to obtain a cross-section along line AA. Furthermore, the inductor 2 is cut along line BB, which is perpendicular to line AA in Figure 2.

[0037] A general-purpose image analysis device is used to observe the cross-section along line AA and obtain a cross-sectional image along line AA. Furthermore, the cross-section along line BB is observed and obtain a cross-sectional image along line BB.

[0038] As shown in Figure 3, when drawing two parallel tangent lines that touch the contour of a soft magnetic metal particle i observed in a cross-sectional image, the line segment connecting the points of contact when the distance between the two tangent lines is longest is the major axis. The length of this major axis is the major axis diameter L of the soft magnetic metal particle i. i Therefore, when determining the major axis, the angle between the two parallel tangents is 0°.

[0039] Furthermore, as shown in Figure 3, when two parallel tangents are drawn perpendicular to each tangent in the case where the distance between the above tangents is longest, and tangent to the contour of the soft magnetic metal particle i observed in the cross-sectional image, the line segment connecting each point of contact in the case where the distance between these two tangents is longest is the minor axis. The length of this minor axis is the minor axis diameter D of the soft magnetic metal particle i. i Therefore, when determining the minor axis, the angle between the two parallel tangents is 0°.

[0040] In each cross-sectional image, the major axis diameter of the soft magnetic metal particle i contained in the first core portion 6a is L. i , the minor axis diameter is D i Let N be the number of soft magnetic metal particles, then Σ(L i / D i Calculate ) / N(i=1, 2, ..., N). There are no particular restrictions on the area of ​​each cross-sectional image, but for example, let's assume it is 200 μm × 200 μm. If the number N of soft magnetic metal particles with a major axis diameter of 10 μm or more in the cross-sectional image is less than 100, obtain multiple cross-sectional images to ensure N ≥ 100. The obtained value is the average aspect ratio of each cross-sectional image.

[0041] The average aspect ratios of each cross-sectional image are compared. The average aspect ratio of the soft magnetic metal particles contained in the first core portion 6a is the larger of the average aspect ratio of the cross-sectional image along line AA and the average aspect ratio of the cross-sectional image along line BB.

[0042] The cross-sectional image with the larger average aspect ratio will be used as the cross-sectional image for calculating the average value of cos2θ for the soft magnetic metal particles, as described later.

[0043] In Figure 3, the winding axis of the coil is the Z-axis. As shown in Figure 3, the deflection angle θ of the soft magnetic metal particle i with respect to the winding axis of the coil i This is the size of the angle between the winding axis of the coil and the major axis of the soft magnetic metal particle i.

[0044] The average value of cos2θ for soft magnetic metal particles is Σcos2θ iIt is calculated by Σcos2θ / N (i = 1, 2, ···, N). Set the size of the cross-sectional image so that N ≥ 100. i Let Σcos2θ / N be the average orientation degree Φ of the soft magnetic metal particles.

[0045] If Φ = 1, all the soft magnetic metal particles are oriented in the winding axis direction of the coil. If Φ = 0, the individual soft magnetic metal particles are randomly oriented with respect to the winding axis direction of the coil, and as a whole, the soft magnetic metal particles are not oriented in any direction. If Φ = -1, all the soft magnetic metal particles are oriented in a direction perpendicular to the winding axis direction of the coil.

[0046] Next, the manufacturing method of the inductor 2 shown in FIG. 1 will be described with reference to FIG. 4.

[0047] As shown in FIG. 4, the inductor 2 manufactured by the manufacturing method of the inductor 2 in the first embodiment of the present disclosure is finally mainly composed of a core core 6a1 that becomes the first core portion 6a1, a base core 6c1 that finally mainly becomes the exterior portion 6c, a core material (not shown) that finally mainly becomes the second core portion 6b and the exterior portion 6d, and an insert member having a coil portion 4 composed of an air-core coil or the like, and is manufactured by integrating them.

[0048] The length of the core core 6a1 in the Z-axis direction may be the same as the length of the coil portion 4 in the Z-axis direction, may be longer than the length of the coil portion 4 in the Z-axis direction, or may be shorter than the length of the coil portion 4 in the Z-axis direction.

[0049] (Core core 6a1) Prepare a soft magnetic metal powder containing soft magnetic metal particles and a resin as the material of the core core 6a1.

[0050] There are no particular restrictions on the shape of the soft magnetic metal particles contained in the soft magnetic metal powder. For example, they may be spherical, flattened, or needle-shaped. There are no particular restrictions on the average particle size of the soft magnetic metal particles. For example, the average particle size may be between 0.5 μm and 50 μm. A soft magnetic metal powder may be prepared by mixing multiple types of soft magnetic metal particles that differ in shape, average particle size, etc. For example, a soft magnetic metal powder may be prepared by mixing soft magnetic metal particles that have not been flattened beforehand with soft magnetic metal particles that have been flattened beforehand.

[0051] The resin is not particularly limited, but examples include epoxy resin, phenolic resin, polyimide resin, polyamide-imide resin, and silicone resin. Alternatively, resins may be prepared by appropriately combining these resins.

[0052] Next, the soft magnetic metal powder and resin are mixed and granulated to obtain granules. There are no particular restrictions on the granulation method. For example, the resin may be added to the magnetic powder, stirred, and then dried. The average particle size and particle size distribution of the granules may also be adjusted as appropriate.

[0053] There are no particular restrictions on the resin content, but for example, it may be 1.0 to 6.0 parts by weight per 100 parts by weight of soft magnetic metal powder.

[0054] Before mixing the soft magnetic metal powder with the resin, an insulating film may be formed on the surface of the soft magnetic metal particles. For example, an insulating film, which is an SiO2 film, can be formed by the sol-gel method.

[0055] The soft magnetic metal powder may be mixed with a resin and then passed through a mesh to remove coarse granules. Alternatively, the resin may be diluted with a solvent when added to the magnetic powder. Examples of solvents include ketones.

[0056] Next, the core 6a1 is prepared by compression molding. Specifically, the obtained granules are filled into a mold and pressurized to obtain the core 6a1. During this process, the soft magnetic metal particles deform and become flattened in the direction perpendicular to the direction of pressurization. As a result, the soft magnetic metal particles become oriented perpendicular to the direction of pressurization. Hereinafter, the process of forming cores such as the core 6a1 by compression molding may be referred to as core molding.

[0057] There are no particular restrictions on the pressure during pressurization; the higher the pressure, the more likely the soft magnetic metal particles are to become larger and flatter. For example, pressures of 300 MPa to 1200 MPa are acceptable.

[0058] During core molding, pressure may be applied while applying a magnetic field. The degree of orientation of the soft magnetic metal particles can also be changed by controlling the direction and / or magnitude of the applied magnetic field. For example, by applying a magnetic field perpendicular to the compression direction, the absolute value of the degree of orientation of the soft magnetic metal particles contained in the core 6a1 can be increased.

[0059] Furthermore, the core 6a1 may be fired. By firing, the resin present between the soft magnetic metal particles decomposes into inorganic matter. In addition, residual stress generated in the core 6a1 by core molding is relieved, and / or the permeability of the core 6a1 is improved. Furthermore, the shape of the core 6a1 becomes less likely to change in the integration process described later. As a result, a coil component with high inductance L can be obtained by firing the core 6a1. Note that the permeability of the core 6a1 improves by firing because the distance between the soft magnetic metal particles contained in the core 6a1 becomes smaller.

[0060] (Base core 6c1) Prepare the base core 6c1. There are no particular restrictions on the method of preparing the base core 6c1, and it may be the same as the method of preparing the core core 6a1. The soft magnetic metal powder used to prepare the base core 6c1 may be the same type as the soft magnetic metal powder used to prepare the core core 6a1, or it may be different. The resin used to prepare the base core 6c1 may be the same type as the resin used to prepare the core core 6a1, or it may be different.

[0061] (Core material) There are no particular restrictions on the core material. For example, it may be a mixture of soft magnetic metal powder containing soft magnetic metal particles and a resin. The soft magnetic metal powder used in the core material may be the same type as the soft magnetic metal powder used in the production of the core core, or it may be different. The soft magnetic metal powder used in the core material may be the same type as the soft magnetic metal powder used in the production of the base core, or it may be different. The resin used in the core material may be the same type as the resin used in the production of the core core, or it may be different. The resin used in the core material may be the same type as the resin used in the production of the base core, or it may be different. In a method for manufacturing a coil component according to one embodiment of this disclosure, when obtaining a coil component having a predetermined inductance L, the higher the resin content in the core material, the less likely the coil is to short-circuit.

[0062] Furthermore, there are no particular restrictions on the form of the mixture of the soft magnetic metal powder containing soft magnetic metal particles and the resin. For example, it may be in the form of granules or a paste. When preparing a paste, the mixture may be heated as needed.

[0063] (Insert material) The coil is prepared by preparing an insert member having a coil portion 4 in which a conductor is wound in a coil shape. Both ends of the conductor 5 constituting the coil portion 4 are led out to the outside of the coil portion 4 as lead portions 5a and 5b. The terminals may be connected to the lead portions 5a and 5b after the main molding process described later. The terminals may be connected to the lead portions 5a and 5b in advance before the main molding process described later. The connection between the terminals and the lead portions 5a and 5b may be located on the outside of the outer casings 6c and 6d, or on the inside of the outer casings 6c and 6d. The shape of the coil portion 4 is not limited to a circle when viewed from the winding axis direction. The shape of the coil portion 4 may be an ellipse or a square when viewed from the winding axis direction.

[0064] (Integration of core, base core, core material, and insert component) First, the base core 6c1 is inserted into the mold. Next, the insert member and the core core 6a1 are placed in predetermined positions on the base core 6c1. At this time, the core core 6a1 is positioned so that the direction of pressure applied to the core core 6a1 is perpendicular to the winding axis direction of the coil. As a result, in the inductor 2 that is finally obtained, the soft magnetic metal particles contained in the first core portion 6a are oriented in the direction of the winding axis direction of the coil, and the average value of cos2θ of the soft magnetic metal particles contained in the first core portion 6a becomes a positive value. Alternatively, the lead portions 5a and 5b may be joined to the lead frame.

[0065] Next, the core material is filled into the mold.

[0066] Next, the main molding process is performed. Specifically, the base core 6c1, core core 6a1, insert member, and core material inserted into the mold are pressurized. The pressurizing direction is in the direction of the coil winding axis. The pressurizing process causes the coil and core to be compressed and integrated. There are no particular restrictions on the pressure during this molding process. For example, it can be between 10 MPa and 600 MPa. When obtaining a coil component having a predetermined inductance L, if the coil component is manufactured using the method for manufacturing a coil component according to one embodiment of this disclosure, the pressure during this molding process can be lower compared to manufacturing the coil component by pressing in the direction of the pressurizing process used during core core manufacturing. As a result, the resulting coil component is less likely to short-circuit. Furthermore, because the pressure during this molding process can be lowered, the lifespan of the mold can be extended.

[0067] This molding process integrally forms the base core 6c1, the core core 6a1, and the core material to obtain the core portion 6. That is, a core portion 6 having a second core portion 6b and an outer casing portion 6d is obtained. Furthermore, the soft magnetic metal particles contained in the second core portion 6b and the outer casing portion 6d may be flattened in the direction of the plane perpendicular to the direction of pressure. As a result, the soft magnetic metal particles contained in the second core portion 6b and the outer casing portion 6d may be oriented in a direction perpendicular to the direction of pressure (the winding axis direction of the coil). That is, the average value of cos2θ of the soft magnetic metal particles contained in the second core portion 6b and the outer casing portion 6d tends to be 0 or negative.

[0068] The core 6a1 may deform slightly during this molding process.

[0069] There are no particular restrictions on the temperature during the main molding process, but it is also acceptable to perform the molding at a temperature at which the resin softens. Molding methods that perform the main molding at a temperature at which the resin softens are generally called warm molding or compression molding. In this case, each core and insert component may be preheated. Additionally, the mold frame and punches may also be preheated.

[0070] After the initial molding process, the inductor 2 removed from the mold may be heated to further harden the resin. There are no particular restrictions on the heating temperature; for example, it may be 150°C to 200°C.

[0071] This molding process forms the second core portion 6b and the outer casing portion 6d. Furthermore, the soft magnetic metal particles contained in the second core portion 6b and the outer casing portion 6d may become flattened in the direction perpendicular to the direction of pressure. As a result, the soft magnetic metal particles contained in the second core portion 6b and the outer casing portion 6d may be oriented perpendicular to the direction of pressure (the winding axis direction of the coil). That is, the average value of cos2θ of the soft magnetic metal particles contained in the second core portion 6b and the outer casing portion 6d tends to be 0 or negative.

[0072] (Second Embodiment) The following describes a second embodiment of this disclosure, which is the same as the first embodiment unless otherwise specified.

[0073] Inductor 2, which is one type of coil component according to the second embodiment of this disclosure, is manufactured using a different method than inductor 2, which is one type of coil component according to the first embodiment.

[0074] In the manufacturing method of the inductor 2 according to the first embodiment, the shape of the base core 6c1 is flat, as shown in Figure 4. In the manufacturing method of the inductor 2 according to the second embodiment, the shape of the base core 6c1 is pot-shaped, as shown in Figure 5. The manufacturing method of the inductor 2 according to the second embodiment has the advantage that the position of the insert member is less likely to shift during the main molding process, and that cracks are less likely to occur during the main molding process if the height of the pot-shaped base core 6c1 is matched to the height of the lead portions 5a and 5b.

[0075] (Integration of core, base core, core material, and insert component) First, a pot-shaped base core 6c1 is inserted into the mold. Next, the insert member and the core core 6a1 are placed in predetermined positions on the base core 6c1. At this time, the core core 6a1 is positioned so that the direction of pressure applied to the core core 6a1 is perpendicular to the winding axis direction of the coil. As a result, in the inductor 2 that is finally obtained, the soft magnetic metal particles contained in the first core portion 6a are oriented in the direction of the winding axis direction of the coil, and the average value of cos2θ of the soft magnetic metal particles contained in the first core portion 6a becomes a positive value. Alternatively, the lead portions 5a and 5b may be joined to the lead frame.

[0076] Next, the core material is filled into the mold.

[0077] Next, the main molding (thermocompression bonding) is performed. Specifically, the base core 6c1, core core 6a1, core material, and insert member inserted into the mold are pressurized. The direction of pressurization is in the direction of the coil winding axis. Pressurization causes the coil and core to be compressed and integrated. There are no particular restrictions on the pressure during molding. For example, it can be between 10 MPa and 600 MPa.

[0078] The above-mentioned core material forms the second core portion 6b. During this molding process, a portion of the core 6a1 and / or base core 6c1 may be deformed to form the second core portion 6b.

[0079] (Other embodiments) The method for manufacturing the inductor 2 according to this disclosure is not limited to the method described above. In particular, there are no particular restrictions on the shape and number of cores, as long as the inductor 2 shown in Figure 1 is ultimately obtained. Furthermore, as shown in the first and second embodiments, a molded, integrated coil component may also be used, that is, a coil component in which the entire coil component, excluding the lead portion of the conductor, is sealed with a magnetic material.

[0080] In the first and second embodiments described above, the core core 6a1 is positioned such that the direction of pressure applied to the core core 6a1 is perpendicular to the winding axis direction of the coil. However, this positioning method is not essential. By applying a magnetic field in the direction of pressure applied during the molding of the core core 6a1, it may be possible to orient the soft magnetic metal particles contained in the core core 6a1 in the direction of pressure. In this case, the core core 6a1 may be positioned such that the direction of pressure applied to the core core 6a1 is parallel to the winding axis direction of the coil.

[0081] The coil component relating to this disclosure is not limited to an inductor. For example, it may be a transformer, a reactor, or other coil component. However, considering that the coil component relating to this disclosure is easy to improve inductance, and that transformers and reactors are difficult to mold as a single unit, the coil component relating to this disclosure may be an inductor. [Examples]

[0082] The present disclosure will be described below with reference to more detailed examples, but the disclosure is not limited to these examples.

[0083] Experimental Example 1 The method for preparing the inductor samples in each example shown in Table 1 (Samples No. 2-4, 6-8, 10-12, 14-16) will be explained below.

[0084] First, the core, base core, insert members, and core material were prepared.

[0085] (Core) A soft magnetic metal powder containing soft magnetic metal particles and a resin were prepared as the core material. The soft magnetic metal particles were made of an Fe-Si alloy (Fe 95.5% by weight, Si 4.5% by weight), and their Vickers hardness was set to 300 HV. The average particle size of the soft magnetic metal powder was 25 μm. Epoxy resin was used as the resin.

[0086] Next, an insulating film was formed on the surface of the soft magnetic metal particles. Specifically, an insulating film made of SiO2 was formed using the sol-gel method. The thickness of the insulating film was approximately 40 nm.

[0087] Next, soft magnetic metal powder and resin were mixed and granulated to obtain granules. Specifically, the resin was added to the soft magnetic metal powder, stirred, and then dried at 40°C for 10 hours. The resin content was 2 to 3 parts by weight, based on a ratio of 100 parts by weight of soft magnetic metal powder. Epoxy resin was used as the resin. After adding the resin to the soft magnetic metal powder and stirring, coarse granules were removed by passing the mixture through a mesh. Specifically, a mesh with a mesh opening of 100 μm was used. The average particle size of the final obtained granules was approximately 60 μm.

[0088] Next, the obtained granules were filled into a mold and core-forming was performed to obtain a core, which is a rectangular prism as shown in Figure 4. The dimensions of the core were 1.0 mm × 1.1 mm × 1.0 mm. During this process, the soft magnetic metal particles deformed and became flattened in the direction perpendicular to the direction of pressure. As a result, the soft magnetic metal particles were oriented perpendicular to the direction of pressure. The molding pressure was set to 400 to 1000 MPa.

[0089] In the final inductor sample, if the average aspect ratio of the first core was 5.0 and the orientation degree (Φ1) of the first core was 1.0, the soft magnetic metal powder was flattened before being mixed with the resin. Specifically, IPA was added to the soft magnetic metal powder as a solvent to prepare a slurry, and then the soft magnetic metal particles contained in the soft magnetic metal powder were pulverized using a wet pulverizer, a bead mill. After pulverization, the IPA was removed by drying with a spray dryer or the like. Furthermore, zinc stearate was added to the granules as a lubricant. The amount added was 0.2 parts by weight or less per 100 parts by weight of granules. Furthermore, the core molding of the core was performed by warm molding. Specifically, the core was molded while heating the mold and granules. The heating temperature was set to near the softening point of the resin. Furthermore, the core molding of the core was performed while applying a magnetic field perpendicular to the direction of pressure.

[0090] When the average aspect ratio of the first core section was to be less than 5.0, the presence and conditions of the flattening treatment, the molding pressure during core molding, the hardness of the soft magnetic metal powder, the hardness of the resin, etc. were appropriately controlled. Specifically, the conditions for the flattening treatment included appropriately controlling the grinding time, the rotation speed of the grinder, the slurry concentration, and the viscosity of the slurry.

[0091] When the orientation degree of the first core was to be less than 1.0, the presence or absence of magnetic field application, the presence or absence of heating during core molding and the heating temperature, and the presence or absence and amount of lubricant were appropriately controlled.

[0092] (Base core) The method for manufacturing the base core was the same as the method for manufacturing the core.

[0093] (Insert material) An insert member having a coil portion 4 as shown in Figure 4 was prepared. The size of the coil portion 4 was set to an inner diameter of 1.5 mm and a height of 1.0 mm, and the material of the coil portion 4 was made of Cu.

[0094] (Core material) A soft magnetic metal powder containing soft magnetic metal particles and a resin were prepared as core materials. The material of the soft magnetic metal particles was an Fe-Si alloy (Fe 95.5% by weight, Si 4.5% by weight), and the Vickers hardness of the soft magnetic metal particles was set to 300 HV. The average particle size of the soft magnetic metal powder was 25 μm. An epoxy resin was used as the resin.

[0095] Next, an insulating film was formed on the surface of the soft magnetic metal particles. Specifically, an insulating film made of SiO2 was formed using the sol-gel method. The thickness of the insulating film was approximately 40 nm.

[0096] Next, soft magnetic metal powder and resin were mixed and granulated to obtain granules. Specifically, resin was added to the soft magnetic metal powder, stirred, and then dried at 40°C for 10 hours. The resin content is shown in Table 1. The resin used was epoxy resin. After adding the resin to the soft magnetic metal powder and stirring, coarse granules were removed by passing the mixture through a mesh. Specifically, a mesh with a mesh opening of 100 μm was used. The average particle size of the final obtained granules was approximately 60 μm.

[0097] (Integration of core, base core, core material, and insert component) First, the base core was inserted into the mold. Next, as shown in Figure 4, the insert member and the core core were placed in predetermined positions on the base core. Table 1 shows the installation direction of the core core at this time. "Perpendicular" is written when the pressurization direction of the core core and the winding axis direction of the coil are perpendicular, and "Parallel" is written when the pressurization direction of the core core and the winding axis direction of the coil are parallel. In the case of "Perpendicular," the installation direction of the core core was such that the direction of the side with a length of 1.1 mm was the height direction.

[0098] Next, the core material was filled into the mold.

[0099] Next, molding was performed. Specifically, the base core, core core, insert member, and core material inserted into the mold were pressurized. The pressurizing direction was along the winding axis of the coil. The coil and core were compressed and integrated by the pressurizing. The molding pressure during molding is shown in Table 1. The temperature during molding was set to be near the softening point of the resin.

[0100] After molding, the inductor 2 was removed from the mold and heated to cure the resin. The heating temperature was 150-200°C, and the heating time was 1-3 hours.

[0101] Through the above process, the inductor shown in Figure 1 was obtained. The dimensions of the inductor were 3 mm × 3 mm × 2 mm, with a height of 2 mm.

[0102] Comparative example No. 1, shown in Table 1, was conducted under the same conditions as samples No. 2 to 4, except that it did not use a core material.

[0103] Comparative examples, samples No. 5, 9, and 13 shown in Table 1 were carried out in the same manner as the other examples, except that the shape of the core was cylindrical, the same shape as the core of the coil.

[0104] In each comparative example, the core of the inductor was not distinguishable between the first core and the second core. For convenience, Table 1 shows the aspect ratio and orientation of the core as the aspect ratio and orientation of the first core.

[0105] For the obtained inductors, the average aspect ratio of the soft magnetic metal particles contained in the first core, the average orientation degree Φ1 of the soft magnetic metal particles contained in the first core, the average orientation degree Φ2 of the soft magnetic metal particles contained in the second core, and the average orientation degree Φ3 of the soft magnetic metal particles contained in the outer casing were measured.

[0106] Specifically, first, the inductor of each sample was cut along the portion corresponding to line II in Figure 1. The obtained cross-section was then cut along the portions corresponding to lines AA and BB in Figure 2. The cross-section along line AA was observed using a general-purpose image analysis device, and a cross-sectional image along line AA was obtained. Furthermore, the cross-section along line BB was observed, and a cross-sectional image along line BB was obtained.

[0107] For each cross-sectional image, the average aspect ratio of the soft magnetic metal particles contained in the first core was measured. The larger value was taken as the average aspect ratio of the soft magnetic metal particles contained in the first core. Furthermore, Φ1, Φ2, and Φ3 were measured using the cross-sectional image with the larger average aspect ratio. It was confirmed that these values ​​matched those shown in Table 1. In each example, the average orientation degree Φ1 of the soft magnetic metal particles contained in the first core was higher than the average orientation degree Φ2 of the soft magnetic metal particles contained in the second core. Furthermore, it was higher than the average orientation degree Φ3 of the soft magnetic metal particles contained in the outer casing.

[0108] The inductance L was measured for the obtained inductors. Inductance was measured at a measurement frequency of 1 MHz and a measurement voltage of 500 mV using an RF impedance material analyzer (Agilent Technologies 4491A). The results are shown in Table 1. An inductance of 0.90 μH or higher was considered good.

[0109] The obtained inductors were subjected to ESD (Electrostatic Discharge) testing in accordance with JEITA ED-4701 / 302A using HBM (Human Body Model). The test voltage was ±2kV. Table 1 shows whether or not the ESD test was passed.

[0110] An impulse breakdown voltage (IWT BDV) test was performed on the obtained inductors. The impulse breakdown voltage test was performed using an impulse winding tester (Chroma 19301A) in the impulse winding test breakdown voltage mode (IWT BDV MODE). Specifically, an AC current pulse signal with a predetermined maximum amplitude was input to the sample (inductor), and a reference pulse waveform was measured. Next, an evaluation pulse signal was input, and the pulse waveform detected as a response to the evaluation pulse signal was acquired. The acquisition of pulse waveforms was performed stepwise while increasing the measurement voltage. The measurement voltage at which the area of ​​the pulse waveform fell below 2.0% of the area of ​​the reference pulse waveform was defined as the dielectric breakdown voltage. That is, if the area of ​​the acquired pulse waveform fell below 2.0% of the area of ​​the reference pulse waveform, it was determined that a short circuit had occurred between the conductors constituting the coil. The measurement voltage range was 50V to 350V (measurement voltage step: 1%), and the number of pulse applications was 1. Table 1 indicates "pass" if dielectric breakdown did not occur at a measured voltage of 350V, i.e., if the dielectric breakdown voltage was above 350V, and "short" if dielectric breakdown occurred at a measured voltage of 350V or less, i.e., if the dielectric breakdown voltage was 350V or less.

[0111] [Table 1]

[0112] Each embodiment having a rectangular prism-shaped first core portion showed a higher inductance L.

[0113] (Experimental Example 2) Experimental Example 2 differed from Experimental Example 1 in that the amount of resin in the core material and the molding pressure during the main molding process were controlled so that the inductance L was 0.90 μH. Other aspects were carried out under the same conditions as Experimental Example 1. The results are shown in Table 2.

[0114] [Table 2]

[0115] When the manufacturing conditions were controlled so that the inductance L was the same for each embodiment having a rectangular prism-shaped first core and each comparative example not having a rectangular prism-shaped first core, the results of the electrostatic discharge test and / or inductance test deteriorated for each comparative example. This is thought to be because the amount of resin in the core material was small and the pressure during the molding was large.

[0116] Each embodiment having a rectangular prism-shaped first core portion was able to maintain a high inductance L even when the amount of resin in the portion other than the rectangular prism-shaped first core portion was increased or the pressure during the molding process was reduced. In other words, it was possible to reduce the load on the coil during manufacturing while maintaining a high inductance. [Explanation of symbols]

[0117] 2… Inductor 4… Coil section 5… Conductor 5a, 5b... Lead section 6a... 1st center core part 6b... 2nd center core part 6c, 6d... Exterior parts 6a1… Core 6c1… Base core

Claims

1. A coil component comprising a core portion and a coil portion formed by winding a conductor in a coil shape, wherein the coil portion is formed inside the core portion, The core portion has a central core located in the area surrounded by the inner diameter of the coil portion. The core portion comprises a first core portion containing first soft magnetic metal particles and a second core portion arranged around the first core portion and containing second soft magnetic metal particles, wherein the first core portion has at least two opposing surfaces facing each other, and the opposing surfaces are parallel to the winding axis direction of the coil portion. The shape of the first core is a rectangular prism, The average value of the deflection angle of the first soft magnetic metal particles with respect to the winding axis direction of the coil portion is different from the average value of the deflection angle of the second soft magnetic metal particles with respect to the winding axis direction of the coil portion. The average aspect ratio of the first soft magnetic metal particles contained in the first core portion is 1.5 or more and 5.0 or less. A coil component in which the deflection angle of the first soft magnetic metal particles with respect to the winding axis direction of the coil portion is θα, and the average value of cos2θα is 0.5 or more and 1.0 or less.

2. The coil component according to claim 1, wherein the deflection angle of the first soft magnetic metal particles with respect to the winding axis direction of the coil portion is θα, and the deflection angle of the second soft magnetic metal particles with respect to the winding axis direction of the coil portion is θβ, and the average value of cos2θα is greater than the average value of cos2θβ.

3. The coil component according to claim 1, wherein the deflection angle of the first soft magnetic metal particles with respect to the winding axis direction of the coil portion is θα, and the deflection angle of the third soft magnetic metal particles included in the outer portion of the coil portion with respect to the winding axis direction of the coil portion is θγ, and the average value of cos2θα is greater than the average value of cos2θγ.

4. The coil component according to claim 1, wherein the deflection angle of the first soft magnetic metal particles with respect to the winding axis direction of the coil portion is θα, and the average value of cos2θα is 0.1 or more.

5. A coil component comprising a core portion and a coil portion formed by winding a conductor in a coil shape, wherein the coil portion is formed inside the core portion, The core portion has a central core located in the area surrounded by the inner diameter of the coil portion. The core portion comprises a first core portion containing first soft magnetic metal particles and a second core portion arranged around the first core portion and containing second soft magnetic metal particles, wherein the first core portion has at least two opposing surfaces facing each other, and the opposing surfaces are parallel to the winding axis direction of the coil portion. The shape of the first core is a rectangular prism, The average aspect ratio of the first soft magnetic metal particles contained in the first core portion is 1.5 or more and 5.0 or less. A coil component in which the deflection angle of the first soft magnetic metal particles with respect to the winding axis direction of the coil portion is θα, and the average value of cos2θα is 0.5 or more and 1.0 or less.

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