Coil component and power supply device

Abstract

To provide a coil component of which a DC superposition characteristic is high.SOLUTION: A coil component includes: a core part containing a soft-magnetic metal magnetic material; and a winding part to which a conductor is wound, and is formed so that the winding part is formed in an internal part of the core part. The core part includes: an inner core part positioned to a part surrounded by an inner diameter of the winding part; and an outer casing part positioned to a part other than the inner core part. The inner core part includes a first inner core part and a second inner core part that are made from a different material each other. The second inner core part is arranged to a circumference of the first inner core part. A height of the winding part in a cross section containing a center of a winding shaft of the winding part is H. When a cross-sectional area of the inner core part in a cross section vertical to the center of the winding shaft of the winding part is S, the cross sectional area of the first inner core part is S1, the H, the S, and the S1 are within a specific range.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a coil component and a power supply device. [Background technology]

[0002] US Pat. No. 5,399,633 discloses a magnetic component including various T-shaped magnetic cores.

[0003] Patent Document 2 discloses an inductance element in which a magnetic material with a relatively high magnetic permeability is arranged in an air core portion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 9,959,965 [Patent Document 2] JP 2003-168610 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a coil component having excellent DC bias characteristics. [Means for solving the problem]

[0006] The coil component according to the present disclosure comprises: A coil component having a core portion including a soft magnetic metal magnetic body and a winding portion formed by winding a conductor, the winding portion being formed inside the core portion, The core portion has a central core portion located in a portion surrounded by an inner diameter of the winding portion, and an exterior portion located in a portion other than the central core portion, The core portion has a first core portion and a second core portion made of different materials, the second core portion is disposed around the first core portion; The material constituting the first core portion is different from the material constituting the exterior portion, The height of the winding portion in a cross section including the center of the winding axis of the winding portion is defined as H, The cross-sectional area of ​​the center core portion in a cross section perpendicular to the center of the winding axis of the winding portion is defined as S, and the cross-sectional area of ​​the first center core portion is defined as S1. The range of X defined by the following formula is 0.50 or more and 0.90 or less.

number

[0007] A power supply device according to the present disclosure includes the above-described coil component. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view of an inductor according to an example of the present embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a cross section taken along line II in FIG. [Diagram 3] 1 is a schematic diagram showing the positional relationship of each member used in the process of manufacturing an inductor according to an example of this embodiment before thermocompression bonding. [Figure 4] 1 is a schematic diagram showing the positional relationship of each member used in the process of manufacturing an inductor according to an example of this embodiment before thermocompression bonding. [Diagram 5] 1 is a schematic diagram showing the positional relationship of each member used in the process of manufacturing an inductor according to an example of this embodiment before thermocompression bonding. [Figure 6] 1 is a schematic diagram showing the positional relationship of each member used in the process of producing an inductor of a comparative example before thermocompression bonding. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. The embodiment of the present disclosure described below is an example for explaining the present disclosure. Various components according to an embodiment of the present disclosure, such as numerical values, shapes, materials, and manufacturing processes, can be modified or changed within the scope of technical problems.

[0010] Furthermore, the shapes and the like shown in the drawings of this disclosure do not necessarily correspond to the actual shapes and the like, since the shapes and the like may be modified for the purpose of explanation.

[0011] 1, an inductor 2, which is a type of coil component according to an embodiment of the present disclosure, has a winding portion 4 and a core portion 6. The winding portion 4 is formed by winding a conductor 5 in a coil shape. The core portion 6 has a center portion located in a portion surrounded by the inner diameter of the winding portion 4, and an exterior portion which is the other portion.

[0012] In the inductor 2 according to the embodiment of the present disclosure, the upper and lower surfaces of the core portion 6 are perpendicular to the Z axis, and the side surface of the core portion 6 is perpendicular to a plane including the X axis and the Y axis. In addition, the winding axis of the winding portion 4 is parallel to the Z axis. However, the shape of the core portion 6 is not limited to the shape in FIG. 1.

[0013] In this disclosure, "parallel" does not only mean completely parallel, but also includes substantially parallel. In other words, "parallel" in this disclosure may include an error within the range of manufacturing tolerance, or may include an error beyond the range of manufacturing tolerance. Specifically, when line A is parallel to line B, it means that the angle between line A and line B is 0° or more and 10° or less, unless otherwise specified. The same applies when one or both of the lines are replaced with a surface.

[0014] In this disclosure, "perpendicular" includes not only perfect perpendicularity but also substantial perpendicularity. In other words, "perpendicular" in this disclosure may include an error within the range of manufacturing tolerance, or may include an error beyond the range of manufacturing tolerance. Specifically, when line A is perpendicular to line B, it means that the angle between line A and line B is 80° or more and 100° or less, unless otherwise specified. The same applies when one or both of the lines are replaced with a surface.

[0015] The size of the inductor 2 according to the embodiment of the present disclosure is not particularly limited. The lower limit of the size of the part excluding the parts not shown (for example, the lead part and terminals described later) 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 part excluding the parts not shown may be the size of a cube with a bottom surface of 25 mm×25 mm and a height of 25 mm. The height is the length in the Z-axis direction in FIG. 1. In FIG. 1, the lead parts, terminals, etc. of the winding part 4 are omitted from the illustration. Lead parts may be formed on both ends of the conductor constituting the winding part 4, and may be taken out to the outside of the core part 6.

[0016] The conductor (conductor wire) 5 constituting the winding portion 4 is coated on its outer periphery with an insulating coating layer as necessary. There is no particular limit to 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 is no particular limit to the material of the insulating coating layer. The material of the insulating coating layer may be, for example, polyurethane, polyamide-imide, polyimide, polyester, polyester-imide, and / or polyester-nylon.

[0017] There is no particular limitation on the cross-sectional shape of the conductor 5. Examples of the cross-sectional shape include a circular shape and a rectangular shape. In the embodiment of the present disclosure, the cross-sectional shape of the conductor 5 is a circular shape.

[0018] The core portion 6 has at least a soft magnetic metal magnetic material. For example, the core portion 6 may be a dust core having soft magnetic metal particles, which is a type of soft magnetic metal magnetic material, or a sintered metal core having soft magnetic metal particles, which is a type of soft magnetic metal magnetic material. The core portion 6 may be a core obtained by winding a soft magnetic metal ribbon, which is a type of soft magnetic metal magnetic material, or a core obtained by laminating soft magnetic metal ribbons, which is a type of soft magnetic metal magnetic material. Hereinafter, a case where the core portion 6 has soft magnetic metal particles as a soft magnetic metal magnetic material will be described.

[0019] The material of the soft magnetic metal particles is not particularly limited. The material of the soft magnetic metal particles may be, for example, ferrite such as Mn-Zn ferrite and Ni-Cu-Zn ferrite, or soft magnetic alloy such as Fe-Si alloy, Fe-Si-Al alloy, Fe-Si-Cr alloy, or permalloy (Fe-Ni alloy). The microstructure of the soft magnetic metal particles is not particularly limited. The microstructure of the soft magnetic metal particles may be amorphous or may contain crystals. When the soft magnetic metal particles are amorphous, the soft magnetic metal particles may be flattened in advance using a grinder or the like. When the soft magnetic metal particles contain crystals, the crystal grain size is also not particularly limited. The crystal grain size may be, for example, 1 μm or less.

[0020] The core 6 may have a thermosetting resin (binder). There is no particular limitation on the type of thermosetting resin. Examples of the thermosetting resin include epoxy resin, diallyl phthalate resin, phenol resin, polyimide, polyamideimide, silicone resin, and combinations thereof.

[0021] The core portion 6 has a central core portion located in a portion surrounded by the inner diameter of the winding portion 4, and an exterior portion 6c located in a portion other than the central core portion. The central core portion has a first central core portion 6a and a second central core portion 6b disposed around the first central core portion 6a. The gap between the central core portion (second central core portion 6b) and the winding portion 4 is sufficiently small. The volume of the gap is 5% or less, with the volume of the portion surrounded by the inner diameter of the winding portion 4 being 100%.

[0022] The first core portion 6a and the second core portion 6b are made of different materials. The first core portion 6a and the exterior portion 6c may be made of the same material or different materials. A part of the exterior portion 6c may be made of the same material as the first core portion 6a, and in particular, a part of the exterior portion 6c overlapping with a part of the first core portion 6a extended in the Z-axis direction and / or in the opposite direction to the Z-axis direction may be made of the same material as the first core portion 6a. The second core portion 6b and the exterior portion 6c may be made of the same material or different materials. When the second core portion 6b and the majority of the exterior portion 6c are made of different materials, a part of the exterior portion 6c may be made of the same material as the second core portion 6a, and in particular, a part of the exterior portion 6c overlapping with a part of the second core portion 6a extended in the Z-axis direction and / or in the opposite direction to the Z-axis direction may be made of the same material as the second core portion 6b. Furthermore, the portion of the first central core portion 6a and / or the second central core portion 6b that is adjacent to the exterior portion 6c in the Z-axis direction may be made of the same material as the exterior portion 6c.

[0023] The first central core portion 6a and the second central core portion 6b can be distinguished by observing a cross section perpendicular to the winding axis direction of the winding portion 4 with a general-purpose image analyzer such as an SEM. This is because a difference in contrast occurs between the first central core portion 6a and the second central core portion 6b. The difference in contrast may occur due to, for example, a difference in particle size, a difference in material, a difference in average aspect ratio, a difference in average orientation, or a difference in packing density of the soft magnetic metal particles contained in each central core portion. The difference in contrast may also occur due to a difference in the type of organic compound (resin) or inorganic substance contained in each central core portion, or a difference in the content of the organic compound or inorganic substance. That is, between the first central core portion 6a and the second central core portion 6b, there is one or more differences selected from a difference in material, a difference in average aspect ratio, a difference in average orientation, a difference in packing density, a difference in the type of organic compound or inorganic substance contained in each central core portion, a difference in the content of the organic compound or inorganic substance, a difference in density of each central core portion, and the like of the soft magnetic metal particles contained in each central core portion.

[0024] In particular, the first core portion 6a and the second core portion 6b may have different magnetic permeabilities. The first core portion 6a and the exterior portion 6c may have different magnetic permeabilities. In particular, when the first core portion 6a has a large magnetic permeability, the DC superposition characteristics of the inductor 2 are likely to be improved.

[0025] Generally, the smaller the content of organic compounds in the core (hereinafter, sometimes simply referred to as the amount of organic matter), the greater the magnetic permeability of the core. The amount of organic matter in the first core 6a may be smaller than the amount of organic matter in the second core 6b. In that case, the magnetic permeability of the material constituting the first core 6a is likely to be greater than the magnetic permeability of the material constituting the second core 6b. The amount of organic matter in the first core 6a may be 1.5% by weight or less.

[0026] At least a part of the core 6 may be substantially free of organic compounds, and the first central core 6a may be substantially free of organic compounds. Note that "substantially free of organic compounds" means that the amount of organic matter is 0% by weight or more and 0.1% by weight or less.

[0027] The first core portion 6a, the second core portion 6b, and / or the exterior portion 6c may be a compact containing soft magnetic metal particles and a resin, that is, the core portion 6 may have a compact containing soft magnetic metal particles and a resin.

[0028] There is no particular limitation on the method for measuring the amount of organic matter. For example, thermogravimetry-differential thermal analysis (TG-DTA) may be used. Ignition loss measured by TG-DTA may be regarded as the amount of organic matter.

[0029] When the average particle size of the soft magnetic metal particles contained in the first core portion 6a is large, the magnetic permeability of the first core portion 6a is likely to be large. The average particle size of the soft magnetic metal particles contained in the first core portion 6a may be 0.5 μm or more and 50 μm or less. The average particle size of the soft magnetic metal particles contained in the second core portion 6b may be 0.1 μm or more and 40 μm or less. The average particle size of the soft magnetic metal particles contained in the first core portion 6a may be larger than the average particle size of the soft magnetic metal particles contained in the second core portion 6b. Specifically, the average particle size of the soft magnetic metal particles contained in the first core portion 6a may be 105% or more larger than the average particle size of the soft magnetic metal particles contained in the second core portion 6b.

[0030] The average degree of orientation of the soft magnetic metal particles contained in the first central core portion 6a in the winding axis direction of the wound portion may be different from the average degree of orientation of the soft magnetic metal particles contained in the second central core portion 6b in the winding axis direction of the wound portion. When the average degree of orientation of the soft magnetic metal particles contained in the first central core portion 6a in the winding axis direction is high, the magnetic permeability of the first central core portion 6a tends to be high.

[0031] The magnetic permeability in the first central core portion 6a tends to be greater when the composition of the soft magnetic metal particles contained in the first central core portion 6a contains a smaller amount of inevitable impurities such as phosphorus, carbon, and oxygen compared to the composition of the soft magnetic metal particles contained in the second central core portion 6b.

[0032] The filling rate of the soft magnetic metal particles contained in the first core portion 6a may be greater than the filling rate of the soft magnetic metal particles contained in the second core portion 6b. The greater the filling rate of the soft magnetic metal particles contained in the first core portion 6a, the greater the magnetic permeability of the first core portion 6a. The filling rate of the soft magnetic metal particles contained in the first core portion 6a may be 70% or more. The value obtained by dividing the filling rate of the soft magnetic metal particles contained in the first core portion 6a by the filling rate of the soft magnetic metal particles contained in the second core portion 6b may be 1.03 or more. The area ratio of the soft magnetic metal particles calculated from SEM images of the cross sections of the first core portion 6a and the second core portion 6b is defined as the filling rate of the soft magnetic metal particles.

[0033] The first core portion 6a, the second core portion 6b, and / or the exterior portion 6c may be a sintered body. The sintered body may be produced by sintering a green compact. The sintered body is likely to be produced so as to be substantially free of organic compounds.

[0034] In the following description of the present disclosure, unless otherwise specified, the first center core portion 6a, the second center core portion 6b and the exterior portion 6c are each uniform.

[0035] The shape of the first central core portion 6a may be, for example, a cylindrical shape as shown in Figures 1 and 2. In addition, the shape of the first central core portion 6a is not limited to a cylindrical shape. The shape of the first central core portion 6a may be, for example, an elliptical cylindrical shape or a square cylindrical shape.

[0036] As shown in Figure 1, the height of winding portion 4 in a cross section including the center of the winding axis of winding portion 4 is defined as H. As shown in Figures 1 and 2, the cross-sectional area of ​​the center core portion in a cross section perpendicular to the center of the winding axis of winding portion 4 is defined as S, and the cross-sectional area of ​​first center core portion 6a is defined as S1. In this case, the range of X defined by the following formula is 0.50 or more and 0.90 or less.

[0037]

number

[0038] In the past, when one type of material was used for the central core and the entire central core was uniform, it was thought that the inductance and DC bias characteristics would be improved by making the gap between the central core and the winding portion 4 as small as possible. Similarly, when the central core includes a portion with a higher magnetic permeability than the other portions, it was thought that the inductance and DC bias characteristics would be improved by making the proportion of the other portions in the central core as small as possible. In the following description, it is assumed that the gap between the central core (second central core portion 6b) and the winding portion 4 is sufficiently small.

[0039] The inventors have found that when the product of the inner diameter of the winding portion 4 (equivalent to the diameter of a circle equivalent to the area of ​​the center core portion) divided by the height (H) of the winding portion 4 and the diameter of the first center core portion 6a (diameter of a circle equivalent to the area of ​​the center core portion) divided by the inner diameter of the winding portion 4 (equivalent to the diameter of a circle equivalent to the area of ​​the center core portion) is X, there is a correlation between X and the DC superposition characteristics of the inductor 2. Furthermore, they have found that the DC superposition characteristics of the inductor 2 are improved when the above X is within a specific range.

[0040] Specifically, when the above-mentioned range of X is equal to or greater than 0.50 and equal to or less than 0.90, the DC bias characteristic of the inductor 2 is improved.

[0041] Next, a method for manufacturing the inductor 2 shown in FIG. 1 will be described with reference to FIGS.

[0042] (Production method 1) 3, the inductor 2 produced by the method 1 for producing the inductor 2 according to the embodiment of the present disclosure is produced by integrating a first center core 6a1 that will ultimately become mainly the first center core portion 6a, a base core 6c1 and a cover core 6c2 that will ultimately become mainly the second center core portion 6b and the exterior portion 6c, and an insert member 4a1 having a winding portion 4 made of an air-core coil or the like. A core material (not shown) that will ultimately become mainly the second center core portion 6b and / or the exterior portion 6c may also be used.

[0043] In FIG. 3, the length of the first center core 6a1 in the Z-axis direction is the same as the length of the winding portion 4 in the Z-axis direction. However, the length of the first center core 6a1 in the Z-axis direction may be longer than the length of the winding portion 4 in the Z-axis direction. In that case, the protruding portion of the first center core 6a, i.e., the portion of the first center core 6a around which the winding portion 4 does not exist, is pushed and deformed by the cover core 6c2 during thermocompression bonding described below, and moves mainly to the first center core portion 6a, and is filled in the first center core portion 6a. In addition, the protruding portion of the first center core 6a may be finally filled in a portion of the exterior portion 6c that overlaps with a portion of the first center core portion 6a extended in the Z-axis direction and / or in the opposite direction to the Z-axis direction. Even in this case, the DC superposition characteristics of the inductor 2 are improved.

[0044] (First center core 6a1) As materials for the first center core 6a1, soft magnetic metal powder containing soft magnetic metal particles and resin are prepared.

[0045] There is no particular limitation on the shape of the soft magnetic metal particles contained in the soft magnetic metal powder. The shape of the soft magnetic metal particles may be, for example, spherical, flat, or acicular. There is no particular limitation on the average particle size of the soft magnetic metal powder. For example, the average particle size may be 0.5 to 50 μm. A soft magnetic metal powder obtained by mixing multiple types of soft magnetic metal particles having different shapes, average particle sizes, etc. may be prepared.

[0046] The resin is not particularly limited, but examples thereof include epoxy resin, phenol resin, polyimide resin, polyamide-imide resin, and silicone resin. Alternatively, a resin that is a suitable combination of these resins may be prepared.

[0047] Next, the soft magnetic metal powder and the resin are mixed and granulated to obtain granules. There are no particular limitations 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 appropriately adjusted.

[0048] The content of the resin is not particularly limited, but may be, for example, 1.0 to 6.0 parts by weight per 100 parts by weight of the soft magnetic metal powder.

[0049] 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, the insulating film may be a SiO2 film formed by a sol-gel method.

[0050] The resin may be added to the soft magnetic metal powder, stirred, and then passed through a mesh to remove coarse granules. The resin may also be diluted with a solvent when added to the magnetic powder. Examples of the solvent include ketones.

[0051] Next, the first center core 6a1 is prepared by compression molding. Specifically, the obtained granules are filled into a mold and pressurized to obtain the first center core 6a1. The first center core 6a1 prepared by compression molding is a green compact containing soft magnetic metal particles and resin.

[0052] There is no particular limit to the pressure applied when the pressure is applied, and the higher the pressure, the greater the packing rate of the soft magnetic metal particles tends to be. For example, the pressure may be 400 MPa to 1000 MPa.

[0053] When molding the first center core 6a1, pressure may be applied while a magnetic field is being applied. By controlling the direction and / or magnitude of the applied magnetic field, it may be possible to change the orientation of the soft magnetic metal particles.

[0054] Furthermore, the first center core 6a1 prepared by compression molding may be sintered by firing. For example, the firing time may be 0.5 to 3 hours, the firing temperature may be 700 to 900°C, and the firing atmosphere may be nitrogen. By sintering the first center core 6a1, the organic compounds contained in the first center core 6a1 can be reduced, and ultimately the first center core portion 6a can be made to substantially not contain organic compounds.

[0055] (Base core 6c1) A base core 6c1 having a shape shown in FIG. 3 is prepared. There is no particular limitation on the method for producing the base core 6c1, and it may be the same as the method for producing the first center core 6a1. The soft magnetic metal powder used for producing the base core 6c1 may be the same as or different from the soft magnetic metal powder used for producing the first center core 6a1. The resin used for producing the base core 6c1 may be the same as or different from the resin used for producing the first center core 6a1.

[0056] (Cover core 6c2) A cover core 6c2 having a shape shown in FIG. 3 is prepared. There is no particular limitation on the method for producing the cover core 6c2, and it may be the same as the method for producing the first center core 6a1. The soft magnetic metal powder used for producing the cover core 6c2 may be the same as or different from the soft magnetic metal powder used for producing the first center core 6a1. The resin used for producing the cover core 6c2 may be the same as or different from the resin used for producing the first center core 6a1.

[0057] (Core material) When using a core material, there is no particular restriction on the type of the core material. For example, it may be a mixture of a 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 to prepare the first center core, or 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 to prepare the base core, or 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 to prepare the cover core, or may be different. The resin used in the core material may be the same type as the resin used to prepare the first center core, or may be different. The resin used in the core material may be the same type as the resin used to prepare the base core, or may be different. The resin used in the core material may be the same type as the resin used to prepare the base core, or may be different. The resin used in the core material may be the same type as the resin used to prepare the cover core, or may be different.

[0058] Furthermore, there is no particular limitation on the shape of the mixture of the soft magnetic metal powder containing the soft magnetic metal particles and the resin. For example, it may be granular or paste. When preparing a paste, the mixture may be heated as necessary.

[0059] (Insert material) An insert member 4a1 having a winding portion 4 formed by winding a conductor in a coil shape is prepared. Both ends of the conductor constituting the winding portion 4 are drawn out to the outside of the winding portion 4 as lead wires. The terminal may be connected to the lead wire after molding, which will be described later. The terminal may be connected to the lead wire in advance before molding, which will be described later. The connection portion between the terminal and the lead wire may be located outside the exterior portion 6c, or may be located inside the exterior portion 6c. In addition, the shape of the winding portion 4 is not limited to a circle when viewed from the winding axis direction. The shape of the winding portion 4 may be an ellipse or a rectangle when viewed from the winding axis direction. Lead wires and terminals are omitted in Figures 3 to 5. In addition, although the number of turns is illustrated differently in Figures 3 to 5 from Figures 1 and 2, the number of turns can be changed as appropriate.

[0060] (Integration of the first center core, base core, cover core, and insert member) First, the base core 6c1 is inserted into the mold, and then the insert member 4a1 and the first center core 6a1 are placed at predetermined positions on the base core 6c1 as shown in FIG.

[0061] Next, the cover core 6c2 is inserted into the mold and placed in a predetermined position on the insert member 4a, the first center core 6a1, and the base core 6c1 as shown in Fig. 3. Note that the mold may be appropriately filled with a core material before the cover core 6c2 is inserted into the mold, but the following description will be given assuming that the core material is not filled.

[0062] Next, molding is performed by thermocompression. Specifically, each core inserted in a mold is heated to a temperature at which the resin softens, and then the base core 6c1, the first center core 6a1, the cover core 6c2, and the insert member 4a1 inserted in the mold are thermocompression-bonded. Each core and the insert member may be heated (preheated) in advance. Also, the frame of the mold and punches may be heated. The direction of pressure is the winding axis direction of the coil. The coil and the core are thermocompression-bonded and integrated by the pressure. Each core is deformed by thermocompression, and the gaps shown in FIG. 3 are appropriately filled with each core. There is no particular limit to the pressure during thermocompression. For example, it is 100 MPa to 400 MPa. There is no particular limit to the temperature during thermocompression. For example, it is 50°C to 100°C.

[0063] The base core 6c1, the first center core 6a1, and the cover core 6c2 are integrally molded by thermocompression to obtain the core portion 6. That is, the core portion 6 having the first center core portion 6a, the second center core portion 6b, and the exterior portion 6c is obtained.

[0064] After the thermocompression bonding, the inductor 2 is removed from the mold and heated to further harden the resin. There is no particular limit to the heating temperature. For example, the heating temperature may be 150°C to 200°C.

[0065] (Production Method 2) Hereinafter, the manufacturing method 2 will be described, but unless otherwise specified, it is the same as the manufacturing method 1.

[0066] As shown in Figure 4, the inductor 2 manufactured by manufacturing method 2 of inductor 2 in one embodiment of the present disclosure is manufactured by integrating a first center core 6a1 which will ultimately become mainly the first center core portion 6a, a base core 6c1 which will ultimately become mainly the second center core portion 6b and the exterior portion 6c, a cover core 6c2 which will ultimately become mainly the exterior portion 6c, and an insert member 4a1 having a winding portion 4 composed of an air core coil or the like.

[0067] In the manufacturing method 1 shown in Fig. 3, both the base core 6c1 and the cover core 6c2 have a pot-like shape. In contrast, in the manufacturing method 2 shown in Fig. 4, the base core 6c1 has a pot-like shape, and the cover core 6c2 has a flat plate shape.

[0068] (Production Method 3) Hereinafter, the preparation method 3 will be described, but unless otherwise specified, it is the same as the preparation method 2.

[0069] As shown in Figure 5, the inductor 2 manufactured by manufacturing method 3 for inductor 2 in one embodiment of the present disclosure is manufactured by integrating a first core core 6a1 that will ultimately become mainly the first core portion 6a, a second core core 6b1 that will ultimately become mainly the second core portion 6b, a base core 6c1 that will ultimately become mainly the exterior portion 6c, a cover core 6c2 that will ultimately become mainly the exterior portion 6c, and an insert member 4a1 having a winding portion 4 composed of an air core coil or the like.

[0070] In the manufacturing method 2 shown in Fig. 4, the base core 6c1 has a shape similar to a pot type. In contrast, in the manufacturing method 3 shown in Fig. 5, the inner cylindrical portion of the base core 6c1 in the manufacturing method 2 shown in Fig. 4 is separated as a second center core 6b1.

[0071] In manufacturing methods 1 and 2, it is easy to manufacture an inductor 2 in which the second center core portion 6b and the exterior portion 6c are made of the same material. In contrast, in manufacturing method 3, it is easy to manufacture an inductor 2 in which the second center core portion 6b and the exterior portion 6c are made of different materials by using a material for the second center core 6b1 that is different from the materials for the other cores.

[0072] (Other preparation methods) The method for producing the inductor 2 according to the present disclosure is not limited to the above method. In particular, there is no particular limitation on the shape and number of cores as long as the inductor 2 shown in Fig. 1 is finally obtained. Also, as shown in the present disclosure, it may be an integrated molded coil component, that is, a coil component in which the entire coil component except for the lead portion of the conductor is sealed with resin.

[0073] The coil component according to the present disclosure is not limited to an inductor. For example, it may be a coil component such as a transformer or a reactor. However, considering that the coil component according to the present disclosure is easy to improve inductance and that it is difficult to mold a transformer or a reactor into an integrated type, the coil component according to the present disclosure may be an inductor.

[0074] A power supply device according to the present disclosure includes the coil component described above, and may be, for example, a DC-DC converter, a switching power supply, or the like. EXAMPLES

[0075] The present disclosure will be described below based on more detailed examples, but the present disclosure is not limited to these examples.

[0076] Experimental Example 1 A method for fabricating the inductor samples in each of the examples and comparative examples (except for sample No. 7) shown in Table 1 will be described.

[0077] First, a first center core 6a1, a base core 6c1, and a cover core 6c2 each having the shape shown in Fig. 3 were prepared. Furthermore, an insert member 4a1 having a winding portion 4, a lead wire, and a terminal was prepared. Note that the lead wire and the terminal are omitted in Fig. 3.

[0078] (First center core) A soft magnetic metal powder containing soft magnetic metal particles and a resin were prepared as materials for the first center core 6a1. The material of the soft magnetic metal particles was an Fe-Si alloy (Fe 95.5 wt %, Si 4.5 wt %). The average particle size of the soft magnetic metal powder was 25 μm. Epoxy resin was used as the resin.

[0079] Next, an insulating film was formed on the surface of the soft magnetic metal particles. Specifically, the insulating film was a SiO2 film formed by the sol-gel method. The thickness of the insulating film was about 40 nm.

[0080] Next, the 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 content ratio of the resin was set so that the amount of organic matter in the first central core portion 6a in the finally obtained inductor sample would be the value shown in Table 1. The type of resin was epoxy resin. The resin was added to the soft magnetic metal powder, stirred, and then passed through a mesh to remove coarse granules. Specifically, the mixture was passed through a mesh with an opening of 100 μm. The average particle size of the finally obtained granules was about 60 μm.

[0081] Next, the obtained granules were filled into a mold and core-molded to obtain a cylindrical first center core 6a1. The dimensions of the first center core 6a1 were set so that, in the finally obtained inductor sample, the S1 of the first center core portion 6a would be the value shown in Table 1, the amount of organic matter in the portion corresponding to the first center core portion 6a would all be the value shown in Table 1, and the amount of organic matter in the portion corresponding to the exterior portion 6c would all be the value shown in Table 1. The molding pressure was 600 MPa. The pressure direction was set to be parallel to the winding axis direction of the coil in the finally obtained coil component.

[0082] (base core, cover core) The shape of the base core 6c1 was the shape shown in Fig. 3, and was the shape that would become the second center core portion 6b and the exterior portion 6c in the finally obtained inductor sample. The method for producing the base core 6c1 was the same as the method for producing the first center core 6a1, except for the following points.

[0083] The resin content of base core 6c1 was set so that the amount of organic matter in second core portion 6b and the amount of organic matter in exterior portion 6c in the finally obtained inductor sample would be the values ​​shown in Table 1. In producing base core 6c1, the material of the soft magnetic metal particles was 95.5% by weight Fe and 4.5% by weight Si, the average particle size of the soft magnetic metal powder was approximately 25 μm, and the molding pressure was approximately 600 MPa.

[0084] The cover core 6c2 had a shape as shown in Fig. 3, which was a shape that would become the second central core portion 6b and the exterior portion 6c in the finally obtained inductor sample. The method for producing the cover core 6c2 was the same as the method for producing the base core 6c1.

[0085] The material, average particle size, molding pressure, amount of resin, etc. of the base core 6c1 and the cover core 6c2 were controlled so that the inductance L0 before the application of DC current was about 100 μH. Specifically, the amount of resin was changed from the manufacturing method of the first center core. Furthermore, if necessary, the average particle size of the soft magnetic metal powder and / or the molding pressure, etc. were finely adjusted from the manufacturing method of the first center core.

[0086] (Insert material) The dimensions of the winding portion 4 in the insert member 4a1 were as follows: outer diameter 4.67 mm, inner diameter 2.80 mm, wire diameter (diameter of the conductor 5) 0.22 mm, number of turns N 61.5 ts., and height H 4.16 mm. The material of the conductor 5, the lead wire, and the terminal was Cu.

[0087] (Integration of the first center core, base core, cover core, and insert member) First, the base core 6c1 was inserted into the mold. Next, the insert member 4a1 and the first center core 6a1 were placed in predetermined positions on the base core as shown in Fig. 3. Furthermore, the cover core 6c2 was placed in a predetermined position as shown in Fig. 3.

[0088] Next, molding was performed by thermocompression bonding. Specifically, the base core 6c1, the first center core 6a1, the insert member 4a1, and the cover core 6c2 inserted in a mold were heated at 80°C to soften the resin, and then pressure was applied. The pressure was applied in the direction of the coil's winding axis. The coil and each core were thermocompression bonded and integrated by the pressure. The molding pressure during thermocompression bonding was controlled between 100 MPa and 300 MPa so that the inductance L0 before the application of DC current was about 100 μH.

[0089] After molding by thermocompression bonding, the inductor 2 was removed from the mold and heated to harden the resin. The heating temperature was 150° C. to 200° C., and the heating time was 1 hour to 3 hours.

[0090] Through the above steps, the inductor 2 shown in Fig. 1 was obtained. The dimensions of the exterior part 6c of the inductor 2 were 5.50 mm x 5.50 mm x 5.15 mm, and the height was 5.15 mm.

[0091] Sample No. 7, a comparative example shown in Table 1, was made under the same conditions as samples Nos. 1 to 6, except that the first center core 6a1 was not used, and a base core 6c1 and a cover core 6c2 having the shapes shown in FIG. 6 were used.

[0092] In all of the examples of Experimental Examples 1 to 5 (except for the examples in which the first center core described below is sintered), the filling rates of the soft magnetic metal particles in the first center core portion, the second center core portion and the exterior portion were all 69%, and the average orientation degree of the soft magnetic metal particles was all 0.0.

[0093] The filling rate of the soft magnetic metal particles was calculated using an SEM image of the cross section of the measurement location.

[0094] The definition and measurement method of the average orientation degree of the soft magnetic metal particles are shown below.

[0095] The average degree of orientation of soft magnetic metal particles is measured using an SEM image of a cross section parallel to the winding axis direction of the coil. The magnitude of the angle between the winding axis direction of the coil and the major axis of soft magnetic metal particle i is defined as the deflection angle θi of soft magnetic metal particle i with respect to the winding axis direction of the coil. If the number of soft magnetic metal particles is N, the average value of cos2θ of the soft magnetic metal particles is calculated as Σcos2θi / N (i = 1, 2, ..., N). The size of the cross-sectional SEM image is set so that N ≥ 100. Σcos2θi / N is defined as the average degree of orientation of soft magnetic metal particles.

[0096] The direct current resistance Rdc was measured for the inductors of Samples No. 1 to 7. The Rdc was measured using an impedance analyzer (IM3570 manufactured by Hioki E.E.C.). The results are shown in Table 1.

[0097] The inductance L0 before application of a direct current was measured for the inductors of Samples No. 1 to 7. The measurement of L0 was performed using an RF impedance material analyzer (4491A manufactured by Agilent Technologies) at a measurement frequency of 1 MHz and a measurement voltage of 500 mV. The results are shown in Table 1.

[0098] For the inductors of samples No. 1 to No. 7, Isat was measured to evaluate the DC bias characteristics. Specifically, for each inductor, a DC current was applied starting from 0, and the magnitude of the DC current when the inductance decreased to 0.70×L0, relative to the inductance L0 when the DC current was 0, was defined as Isat(-30%). The results are shown in Table 1. When Isat(-30%) was 2.60A or more, it was determined that the DC bias characteristics were good.

[0099] The amount of organic matter in the first core portion 6a, the second core portion 6b and the exterior portion 6c of each of the inductors of Samples No. 1 to 6 was confirmed using a simultaneous thermogravimetry and differential thermal analysis device (STA7200RV manufactured by Hitachi High-Tech). The temperature range for thermogravimetry and differential thermal analysis (TG-DTA) was 30 to 850°C, and the atmospheric gas was nitrogen gas. The ignition loss measured by the TG-DTA method was considered to be the amount of organic matter. When comparing the first core portion 6a, the second core portion 6b and the exterior portion 6c, the conditions other than the amount of organic matter are essentially the same. Therefore, it is presumed that the less the amount of organic matter, the greater the magnetic permeability.

[0100] [Table 1]

[0101] From Table 1, the DC bias characteristics were good in the examples where X, calculated from S, S1, and H, was in the range of 0.50 or more and 0.90 or less. In contrast, the comparative examples where X was outside the above range had inferior DC bias characteristics compared to the examples.

[0102] Experimental Example 2 A method for producing inductor samples in each of the examples and comparative examples shown in Table 2 will be described.

[0103] The embodiment, sample No. 9, comparative example, and sample No. 8 of Experimental Example 2 have different dimensions of the insert member 4a1 from samples Nos. 1 to 7 of Experimental Example 1. The dimensions of the winding portion 4 in the insert member 4a1 were as follows: outer diameter 4.70 mm, inner diameter 2.90 mm, wire diameter (diameter of the conductor 5) 0.21 mm, number of windings N 55.5 ts., and height H 3.63 mm. The results are shown in Table 2.

[0104] [Table 2]

[0105] From Table 2, the examples in which X was in the range of 0.50 or more and 0.90 or less had good DC bias characteristics. In contrast, the comparative examples in which X was outside the above range had inferior DC bias characteristics compared to the examples.

[0106] Experimental Example 3 A method for producing inductor samples in each of the examples and comparative examples shown in Table 3 will be described.

[0107] Each embodiment of Experimental Example 3 has a different dimension of the insert member 4a1 from that of Experimental Example 1. The dimensions of the winding portion 4 in the insert member 4a1 were as follows: outer diameter 4.70 mm, inner diameter 2.90 mm, wire diameter (diameter of the conductor 5) 0.21 mm, number of windings N 55.5 ts., and height H 3.63 mm.

[0108] Furthermore, the first center core 6a1 was sintered, unlike in Experimental Example 1. The sintering temperature was 700° C., the sintering time was 1 hour, and the sintering atmosphere was nitrogen. The results are shown in Table 3.

[0109] In each embodiment of Experimental Example 3, the amount of organic matter in the first core portion 6a is less than the amount of organic matter in the first core portion 6a in each embodiment of Experimental Examples 1 and 2. Therefore, it is presumed that the magnetic permeability of the first core portion 6a is greater than the magnetic permeability of the first core portion 6a in each embodiment of Experimental Examples 1 and 2.

[0110] [Table 3]

[0111] From Table 3, the DC bias characteristics were good in the examples where X was in the range of 0.50 or more and 0.90 or less. In contrast, the DC bias characteristics were inferior to those of the examples in the comparative examples where X was outside the above range.

[0112] Experimental Example 4 A method for producing the inductor samples in each example shown in Table 4 will be described.

[0113] Each embodiment of Experimental Example 4 has a different size of the insert member 4a1 from that of Experimental Example 1. The dimensions of the winding portion 4 in the insert member 4a1 were as follows: outer diameter 4.90 mm, inner diameter 3.10 mm, wire diameter (diameter of the conductor 5) 0.21 mm, number of windings N 52.5 ts., and height H 3.50 mm. In addition, for Samples No. 15 to 17, the first center core 6a1 was sintered in the same manner as in each embodiment of Experimental Example 3. The results are shown in Table 4.

[0114] In sample No. 14 of Experimental Example 4, the magnetic permeability of the first central core portion 6a is estimated to be approximately equal to the magnetic permeability of the first central core portion 6a in each embodiment of Experimental Examples 1 and 2. In samples No. 15 to 17 of Experimental Example 4, the magnetic permeability of the first central core portion 6a is estimated to be approximately equal to the magnetic permeability of the first central core portion 6a in each embodiment of Experimental Example 3.

[0115] [Table 4]

[0116] From Table 4, it can be seen that the DC bias characteristics were excellent in each of the examples in which X was in the range of 0.50 or more and 0.90 or less.

[0117] Experimental Example 5 A method for producing an inductor sample in the embodiment, sample No. 18, shown in Table 5 will be described.

[0118] In Experimental Example 5, as shown in Fig. 5, an inductor sample was fabricated by integrating a first center core 6a1, a second center core 6b1, a base core 6c1, a cover core 6c2, and an insert member 4a1 having a winding portion 4 composed of an air-core coil or the like. The only difference between the inductor sample obtained in Experimental Example 5 and the inductor sample No. 14 was the amount of organic matter in the second center core portion and the amount of organic matter in the exterior portion. The results are shown in Table 5.

[0119] [Table 5]

[0120] From Table 5, even when the organic matter amounts in the first center core portion, the second center core portion, and the exterior portion were all different, the examples in which X was in the range of 0.50 or more and 0.90 or less had good DC bias characteristics.

[0121] Experimental Example 6 A method for producing inductor samples of Examples 19 to 21 shown in Table 6 will be described.

[0122] In Experimental Example 6, the dimensions of the insert member, S1 and S, were the same as those of Sample No. 14.

[0123] In sample No. 14, the amount of organic matter in the first core part was reduced compared to the amount of organic matter in the second core part and exterior part. In contrast, in samples No. 19 to 21, the amount of organic matter in the first core part was increased from that in sample No. 14 to be the same as the amount of organic matter in the second core part and exterior part.

[0124] In sample No. 19, the average particle size of the soft magnetic metal powder used to make the first center core was changed from approximately 25 μm to approximately 27 μm.

[0125] In sample No. 20, the molding pressure of the first center core was changed so that the filling rate of the soft magnetic metal particles in the first center core portion increased from 69% to 71%.

[0126] In sample No. 21, the average orientation degree of the soft magnetic metal particles in the first central core portion was changed from 0.0 to 0.3. Specifically, a cylindrical first central core was not directly produced by pressure molding, but instead a sufficiently large rectangular prism-shaped core was produced by pressure molding. When producing the rectangular prism-shaped core, the pressure direction was set perpendicular to the winding axis direction of the coil in the coil component finally obtained. In addition, the mold was appropriately heated during molding. Then, the rectangular prism-shaped core was cut to produce a cylindrical first central core.

[0127] [Table 6]

[0128] As can be seen from Table 6, even when other parameters were changed in place of the organic matter amount in the first core portion, each Example in which X was in the range of 0.50 or more and 0.90 or less had good DC bias characteristics. Sample No. 14, which had an organic matter amount of 1.5 wt%, had a high Isat and good DC bias characteristics compared to samples Nos. 19 to 21, which had an organic matter amount of 2.4 wt%.

[0129] [Note] The technology according to the present disclosure includes the following configuration examples, but is not limited to these.

[0130] A coil component according to one configuration example of the present disclosure includes: A core particle and an insulating film formed on a surface of the core particle, A coil component having a core portion including a soft magnetic metal magnetic body and a winding portion formed by winding a conductor in a coil shape, the winding portion being formed inside the core portion, The core portion has a central core portion located in a portion surrounded by an inner diameter of the winding portion, and an exterior portion located in a portion other than the central core portion, The core portion has a first core portion and a second core portion made of different materials, the second core portion is disposed around the first core portion, The height of the winding portion in a cross section including the center of the winding axis of the winding portion is defined as H, The cross-sectional area of ​​the center core portion in a cross section perpendicular to the center of the winding axis of the winding portion is defined as S, and the cross-sectional area of ​​the first center core portion is defined as S1. X, as defined by the following formula, is 0.2500 or more and 0.9050 or less.

number

[0131] In the coil component, the second center core portion may be made of a different material from the exterior portion.

[0132] In any of the coil components described above, the first center core portion may have a higher magnetic permeability than the second center core portion.

[0133] In any of the coil components described above, a content ratio of the organic compound in the first central core portion may be smaller than a content ratio of the organic compound in the second central core portion.

[0134] In any of the coil components described above, at least a portion of the core portion may be substantially free of an organic compound.

[0135] In any of the coil components described above, the first center core portion may have an organic compound content of 1.5% by weight or less.

[0136] In any of the coil components described above, the first central core portion and the second central core portion contain soft magnetic metal particles as the soft magnetic metal magnetic material, The average particle size of the soft magnetic metal particles contained in the first core portion may be larger than the average particle size of the soft magnetic metal particles contained in the second core portion.

[0137] In any of the coil components described above, the first central core portion and the second central core portion contain soft magnetic metal particles as the soft magnetic metal magnetic material, The filling rate of the soft magnetic metal particles contained in the first core portion may be greater than the filling rate of the soft magnetic metal particles contained in the second core portion.

[0138] In any of the coil components described above, the first central core portion and the second central core portion contain soft magnetic metal particles as the soft magnetic metal magnetic material, The average orientation of the soft magnetic metal particles contained in the first central core portion with respect to the winding axis direction of the winding portion may be different from the average orientation of the soft magnetic metal particles contained in the second central core portion with respect to the winding axis direction of the winding portion.

[0139] A power supply device according to one configuration example of the present disclosure includes any one of the coil components described above. [Explanation of symbols]

[0140] 2... Inductor 4… Winding section 5… Conductor 6a... 1st center core part 6b... 2nd center core part 6c...Exterior part 4a1…insert member 6a1... First center core 6b1... 2nd center core 6c1... Base core 6c2… Cover core

Claims

1. A coil component having a core portion including a soft magnetic metal magnetic body and a winding portion formed by winding a conductor, the winding portion being formed inside the core portion, The core portion has a central core portion located in a portion surrounded by an inner diameter of the winding portion, and an exterior portion located in a portion other than the central core portion, The core portion has a first core portion and a second core portion made of different materials, the second core portion is disposed around the first core portion; The height of the winding portion in a cross section including the center of the winding axis of the winding portion is defined as H, The cross-sectional area of ​​the center core portion in a cross section perpendicular to the center of the winding axis of the winding portion is S, and the cross-sectional area of ​​the first center core portion is S 1 As, A coil component, wherein X defined by the following formula is 0.50 or more and 0.90 or less. [0010]

2. The coil component according to claim 1 , wherein a material constituting the second core portion is different from a material constituting the exterior portion.

3. The coil component according to claim 1 or 2, wherein the first center core portion has a higher magnetic permeability than the second center core portion.

4. The coil component according to claim 1 , wherein a content ratio of the organic compound in the first central core portion is smaller than a content ratio of the organic compound in the second central core portion.

5. The coil component according to claim 1 , wherein at least a portion of the core portion is substantially free of an organic compound.

6. The coil component according to claim 1 or 2, wherein the content of the organic compound in the first central core portion is 1.5% by weight or less.

7. the first core portion and the second core portion contain soft magnetic metal particles as the soft magnetic metal magnetic body, 3. The coil component according to claim 1, wherein an average grain size of the soft magnetic metal particles contained in the first central core portion is larger than an average grain size of the soft magnetic metal particles contained in the second central core portion.

8. the first core portion and the second core portion contain soft magnetic metal particles as the soft magnetic metal magnetic body, The coil component according to claim 1 , wherein a filling rate of the soft magnetic metal particles contained in the first central core portion is greater than a filling rate of the soft magnetic metal particles contained in the second central core portion.

9. the first core portion and the second core portion contain soft magnetic metal particles as the soft magnetic metal magnetic body, A coil component as described in claim 1 or 2, wherein the average orientation of the soft magnetic metal particles contained in the first central core portion with respect to the winding axis direction of the winding portion is different from the average orientation of the soft magnetic metal particles contained in the second central core portion with respect to the winding axis direction of the winding portion.

10. A power supply device comprising the coil component according to claim 1 or 2.

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