Coil components and power supply devices

Abstract

A coil component, which has a core portion including a soft magnetic metal magnetic body and a winding portion formed by winding a conductor, wherein the coil component is formed by the winding portion being formed inside the core portion. The core portion has a central core portion located in a portion surrounded by the inner diameter of the winding portion and an outer portion located outside the central core portion. The central core portion has a first central core portion and a second central core portion made of different materials. The second central core portion is arranged around the first central core portion. The height of the winding portion in a cross section including the center of the winding shaft of the winding portion is set to H. The cross-sectional area of ​​the central core portion in a cross section perpendicular to the center of the winding shaft of the winding portion is set to S, and the cross-sectional area of ​​the first central core portion is set to S1, and H, S and S1 are within a specific range.

Description

Technical Field

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

[0002] Patent Document 1 discloses a magnetic component including various T-shaped magnetic cores.

[0003] Patent Document 2 discloses an inductor element in which a magnetic body having a large magnetic permeability is disposed in a hollow core portion.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: U.S. Patent No. 996965

[0007] Patent Document 2: Japanese Patent Application Publication No. 2003-168610 Summary of the invention

[0008] Problems to be solved by the invention

[0009] The present invention provides a coil component having high DC superposition characteristics.

[0010] Technical solutions to solve problems

[0011] The present disclosure provides a coil component having a core portion including a soft magnetic metal magnetic body and a winding portion formed by winding a conductor, wherein the coil component is formed by the winding portion being formed inside the core portion, wherein:

[0012] The core portion includes a central core portion located in a portion surrounded by the inner diameter of the winding portion and an outer covering portion located outside the central core portion.

[0013] The core portion includes a first core portion and a second core portion made of different materials.

[0014] The second core portion is arranged around the first core portion,

[0015] The height of the winding portion in the cross section including the winding axis center of the winding portion is denoted as H,

[0016] The cross-sectional area of ​​the core portion in a cross section perpendicular to the center of the winding axis of the winding portion is denoted as S, and the cross-sectional area of ​​the first core portion is denoted as S1.

[0017] X defined by the following formula is 0.50 or more and 0.90 or less.

[0018]

Mathematical formula 1

[0019]

[0020] The power supply device disclosed in the present invention includes the coil component. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of a cross section of an inductor according to an example of the present embodiment.

[0022] Figure 2 It is along Figure 1 Schematic diagram of the cross section of line II.

[0023] Figure 3 This is a schematic diagram showing the positional relationship of each component before thermocompression bonding used in the process of manufacturing the inductor according to an example of the present embodiment.

[0024] Figure 4 This is a schematic diagram showing the positional relationship of each component before thermocompression bonding used in the process of manufacturing the inductor according to an example of the present embodiment.

[0025] Figure 5 This is a schematic diagram showing the positional relationship of each component before thermocompression bonding used in the process of manufacturing the inductor according to an example of the present embodiment.

[0026] Figure 6 This is a schematic diagram showing the positional relationship of each component used in the process of manufacturing the inductor of the comparative example before thermocompression bonding. DETAILED DESCRIPTION

[0027] Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings. The embodiment of the present disclosure described below is an example for illustrating the present disclosure. Various components of an embodiment of the present disclosure, such as numerical values, shapes, materials, manufacturing processes, etc., can be changed or altered within the scope that does not cause technical problems.

[0028] In addition, the shapes and the like shown in the drawings of the present disclosure do not necessarily correspond to the actual shapes and the like, and the shapes and the like may be changed for the purpose of explanation.

[0029] like Figure 1 As shown, an inductor 2 as a type of coil component according to an embodiment of the present disclosure includes 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 includes a central core portion located in a portion surrounded by the inner diameter of the winding portion 4 and an outer portion as other portions.

[0030] In the inductor 2 of one embodiment of the present disclosure, the upper and lower surfaces of the core 6 are perpendicular to the Z axis, and the side surfaces of the core 6 are perpendicular to the 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 6 is not limited to Figure 1 shape.

[0031] In addition, the term "parallel" in the present disclosure includes not only completely parallel but also substantially parallel. That is, the term "parallel" in the present disclosure may include an error within the range of manufacturing tolerance, or may include an error beyond the range of manufacturing tolerance. Specifically, the term "line A and line B are parallel" means that the angle formed by line A and line B is greater than 0° and less than 10° unless otherwise specified. The same applies to replacing one or two lines with a plane.

[0032] In addition, the term "perpendicular" in the present disclosure includes not only completely perpendicular but also substantially perpendicular. That is, the term "perpendicular" in the present invention may include an error within the range of manufacturing tolerance, or may include an error beyond the range of manufacturing tolerance. Specifically, the term "perpendicular" between line A and line B means that the angle between line A and line B is greater than 80° and less than 100° unless otherwise specified. The same applies to replacing one or two lines with a plane.

[0033] The size of the inductor 2 of the embodiment of the present disclosure is not particularly limited. The lower limit of the size of the portion other than the portion not shown (e.g., the lead portion and the terminal described later) may be the size of a rectangular parallelepiped with a bottom of 2 mm × 2 mm and a height of 1 mm. The upper limit of the size of the portion other than the portion not shown may be the size of a cube with a bottom of 25 mm × 25 mm and a height of 25 mm. The height is Figure 1 The length in the Z-axis direction. Figure 1 In the figure, the lead wire part, the terminal, etc. of the winding part 4 are omitted. The lead wire part may be formed at both ends of the conductor which comprises the winding part 4, and may be taken out to the outside of the core part 6.

[0034] The conductor (conducting wire) 5 constituting the winding portion 4 is coated with an insulating coating layer as required. The material of the conductor 5 is not particularly limited. For example, the conductor 5 may be composed of Cu, Al, Fe, Ag, Au, or an alloy containing these metals. The material of the insulating coating layer is not particularly limited. The material of the insulating coating layer may also be, for example, polyurethane, polyamide-imide, polyimide, polyester, polyester-imide, and / or polyester-nylon.

[0035] The cross-sectional shape of the conductor 5 is not particularly limited. As the cross-sectional shape, a circular shape and a flat shape are exemplified. In the embodiment of the present disclosure, the cross-sectional shape of the conductor 5 is a circular shape.

[0036] The core 6 has at least a soft magnetic metal magnetic body. For example, the core 6 may be a powder core having soft magnetic metal particles as a kind of soft magnetic metal magnetic body, or a sintered metal core having soft magnetic metal particles as a kind of soft magnetic metal magnetic body. In addition, the core 6 may be a core obtained by winding a soft magnetic metal thin strip as a kind of soft magnetic metal magnetic body, or a core obtained by stacking soft magnetic metal thin strips as a kind of soft magnetic metal magnetic body. The following describes the case where the core 6 has soft magnetic metal particles as the soft magnetic metal magnetic body.

[0037] There is no particular restriction on the material of the soft magnetic metal particles. The material of the soft magnetic metal particles may be, for example, ferrites such as Mn-Zn ferrite, Ni-Cu-Zn ferrite, soft magnetic alloys such as Fe-Si alloy, Fe-Si-Al alloy, Fe-Si-Cr alloy, and Permalloy (Fe-Ni alloy). There is no particular restriction on the microstructure of the soft magnetic metal particles. The microstructure of the soft magnetic metal particles may be amorphous or may contain crystals. In the case where the soft magnetic metal particles are amorphous, the soft magnetic metal particles may be flattened in advance using a crusher or the like. There is no particular restriction on the grain size when the soft magnetic metal particles contain crystals. The grain size may be, for example, less than 1 μm.

[0038] The core 6 may also contain a thermosetting resin (binder). The type of thermosetting resin is not particularly limited. Examples of the thermosetting resin include epoxy resin, diallyl phthalate resin, phenolic resin, polyimide, polyamide-imide, silicone resin, and a combination thereof.

[0039] The core portion 6 includes a central core portion located in a portion surrounded by the inner diameter of the winding portion 4 and an outer covering portion 6c located in a portion other than the central core portion. The central core portion includes 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 less than 5% when the volume of the portion surrounded by the inner diameter of the winding portion 4 is 100%.

[0040] The first core part 6a and the second core part 6b are made of different materials. The first core part 6a and the outer part 6c can be made of the same material or different materials. A part of the outer part 6c can be made of the same material as the first core part 6a, and in particular, the part of the outer part 6c that repeats the part that extends the first core part 6a in the Z-axis direction and / or the opposite direction of the Z-axis direction can also be made of the same material as the first core part 6a. The second core part 6b and the outer part 6c can be made of the same material or different materials. In the case where the second core part 6b and the outer part 6c are mostly made of different materials, a part of the outer part 6c can be made of the same material as the second core part 6b, and in particular, the part of the outer part 6c that repeats the part that extends the second core part 6b in the Z-axis direction and / or the opposite direction of the Z-axis direction can also be made of the same material as the second core part 6b. In addition, a portion of the first core portion 6a and / or the second core portion 6b located near the exterior portion 6c in the Z-axis direction may be made of the same material as that of the exterior portion 6c.

[0041] The difference between the first core portion 6a and the second core portion 6b can be made, for example, by observing a cross section perpendicular to the winding axis direction of the winding portion 4 using a general image analysis device such as SEM. This is because the difference in contrast is produced in the first core portion 6a and the second core portion 6b. The difference in contrast is sometimes caused by, for example, the difference in particle size of the soft magnetic metal particles contained in each core portion, the difference in material, the difference in average aspect ratio, the difference in average orientation, and the difference in filling density. In addition, the difference in contrast is sometimes caused by the difference in the type of organic compound (resin) or inorganic substance contained in each core portion, and the difference in the content of organic compound or inorganic substance. That is, there is a difference between the first core portion 6a and the second core portion 6b, selected from the difference in material of the soft magnetic metal particles contained in each core portion, the difference in average aspect ratio, the difference in average orientation, the difference in filling density, the difference in the type of organic compound or inorganic substance contained in each core portion, the difference in the content of organic compound or inorganic substance, the difference in density of each core portion, etc.

[0042] 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 outer portion 6c may have different magnetic permeabilities. In particular, when the magnetic permeability of the first core portion 6a is large, the DC superposition characteristics of the inductor 2 are easily improved.

[0043] Generally, the smaller the content ratio of the organic compound in the core portion (hereinafter sometimes referred to as the amount of organic matter), the easier it is for the magnetic permeability of the core portion to become larger. The amount of organic matter in the first core portion 6a may be smaller than the amount of organic matter in the second core portion 6b. In this case, the magnetic permeability of the material constituting the first core portion 6a is likely to be larger than the magnetic permeability of the material constituting the second core portion 6b. In addition, the amount of organic matter in the first core portion 6a may also be less than 1.5% by weight.

[0044] At least a portion of the core portion 6 may contain substantially no organic compound, and the first middle core portion 6a may contain substantially no organic compound. In addition, “contain substantially no organic compound” means “the amount of organic matter is 0 wt% to 0.1 wt%”.

[0045] The first core portion 6a, the second core portion 6b and / or the outer casing 6c may be a powder compact containing soft magnetic metal particles and a resin. That is, the core portion 6 may have a powder compact containing soft magnetic metal particles and a resin.

[0046] The method for measuring the amount of organic matter is not particularly limited. For example, thermogravimetric differential thermal analysis (TG-DTA) may be used. The amount of organic matter may be regarded as the amount of strong heat loss by the TG-DTA method.

[0047] 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 tends to increase. The average particle size of the soft magnetic metal particles contained in the first core portion 6a may also be greater than 0.5 μm and less than 50 μm. The average particle size of the soft magnetic metal particles contained in the second core portion 6b may also be greater than 0.1 μm and less than 40 μm. The average particle size of the soft magnetic metal particles contained in the first core portion 6a may also be greater 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 also be greater than the average particle size of the soft magnetic metal particles contained in the second core portion 6b by more than 105%.

[0048] The average orientation degree of the winding part of the soft magnetic metal particles contained in the first core part 6a relative to the winding axis direction and the average orientation degree of the winding part of the soft magnetic metal particles contained in the second core part 6b relative to the winding axis direction may also be different. When the average orientation degree of the soft magnetic metal particles contained in the first core part 6a in the winding axis direction is high, the magnetic permeability of the first core part 6a tends to increase.

[0049] When the composition of the soft magnetic metal particles contained in the first core portion 6a contains less inevitable impurities such as phosphorus, carbon, and oxygen than the composition of the soft magnetic metal particles contained in the second core portion 6b, the magnetic permeability of the first core portion 6a tends to be high.

[0050] The filling rate of the soft magnetic metal particles contained in the first core portion 6a may also 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 easier it is for the magnetic permeability of the first core portion 6a to increase. The filling rate of the soft magnetic metal particles contained in the first core portion 6a may also be greater than 70%. 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 also be greater than 1.03. The area ratio of the soft magnetic metal particles calculated from the 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.

[0051] In addition, the first core portion 6a, the second core portion 6b and / or the outer casing 6c may be a sintered body. The sintered body may be produced by sintering a powder compact. The sintered body can be easily produced without substantially containing an organic compound.

[0052] In the following description of the present disclosure, unless otherwise specified, the first core portion 6 a , the second core portion 6 b , and the exterior portion 6 c are uniform.

[0053] The shape of the first core portion 6a may also be as follows, for example Figure 1 and Figure 2 The first core portion 6a is shown as a cylindrical shape. In addition, the shape of the first core portion 6a is not limited to a cylindrical shape. The shape of the first core portion 6a may be, for example, an elliptical column shape or a quadrangular column shape.

[0054] like Figure 1 As shown in FIG. 1 , the height of the winding portion 4 in the cross section including the winding axis center of the winding portion 4 is denoted as H. Figure 1 , Figure 2 As shown, the cross-sectional area of ​​the core portion in the cross section perpendicular to the winding axis center of the winding portion 4 is S, and the cross-sectional area of ​​the first core portion 6a is S1. In this case, the range of X defined by the following formula is 0.50 or more and 0.90 or less.

[0055]

Mathematical formula 1

[0056]

[0057] In the case where the material used in the core portion is one type and the core portion is uniform as a whole, it is believed that the inductance and DC superposition characteristics are improved by reducing the gap between the core portion and the winding portion 4 as much as possible. Similarly, in the case where the core portion includes a portion having a greater magnetic permeability than other portions, it is believed that the inductance and DC superposition characteristics are improved by reducing the proportion of the other portions in the core portion as much as possible. In the following description, the gap between the core portion (the second core portion 6b) and the winding portion 4 is sufficiently small.

[0058] The present inventors have found that when the product of the value obtained by dividing the inner diameter of the winding portion 4 (the same as the area circle equivalent diameter of the core portion) by the height (H) of the winding portion 4 and the value obtained by dividing the diameter of the first core portion 6a (the same as the area circle equivalent diameter of the first core portion 6a) by the inner diameter of the winding portion 4 (the same as the area circle equivalent diameter of the core portion) is set as X, there is a correlation between X and the DC superposition characteristics of the inductor 2. Furthermore, it has been found that the DC superposition characteristics of the inductor 2 are improved by setting the above X within a specific range.

[0059] Specifically, when the range of X is 0.50 or more and 0.90 or less, the DC superposition characteristic of the inductor 2 is improved.

[0060] Next, use Figure 3 to Figure 5 illustrate Figure 1 The manufacturing method of the inductor 2 shown.

[0061] (Production method 1)

[0062] like Figure 3 As shown, the inductor 2 manufactured by the manufacturing method 1 of the inductor 2 in one embodiment of the present disclosure is manufactured by integrating the first core magnetic core 6a1 which will eventually become the first core portion 6a, the base core 6c1 and the cover core 6c2 which will eventually become the second core portion 6b and the outer portion 6c, and the insertion member 4a having the winding portion 4 composed of an air-core coil, etc. Alternatively, a core material (not shown) which will eventually become the second core portion 6b and / or the outer portion 6c may be used.

[0063] exist Figure 3 In the embodiment, the length of the first core magnetic 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 core magnetic core 6a1 in the Z-axis direction may be longer than the length of the winding portion 4 in the Z-axis direction. In this case, the exposed portion of the first core magnetic core 6a1, that is, the portion of the first core magnetic core 6a1 without the winding portion 4 around it is pushed and deformed by the cover core 6c2 during the heat pressing described later, and mainly moves to the first core portion 6a and fills the first core portion 6a. In addition, the exposed portion of the first core magnetic core 6a1 may be filled to the portion that finally overlaps with the portion of the outer casing 6c that extends the first core portion 6a in the Z-axis direction and / or the direction opposite to the Z-axis direction. Even in this case, the DC superposition characteristics of the inductor 2 are improved.

[0064] (First core 6a1)

[0065] As materials for the first center magnetic core 6a1, soft magnetic metal powder containing soft magnetic metal particles and resin are prepared.

[0066] The shape of the soft magnetic metal particles contained in the soft magnetic metal powder is not particularly limited. The shape of the soft magnetic metal particles can be, for example, spherical, flat, or needle-shaped. The average particle size of the soft magnetic metal powder is not particularly limited. For example, the average particle size can also be 0.5 μm to 50 μm. It is also possible to prepare a soft magnetic metal powder obtained by mixing a plurality of soft magnetic metal particles having different shapes, average particle sizes, etc.

[0067] The resin is not particularly limited, and examples thereof include epoxy resins, phenolic resins, polyimide resins, polyamide-imide resins, and silicone resins. In addition, a resin obtained by appropriately combining these resins may be prepared.

[0068] Next, the soft magnetic metal powder and the resin are mixed and granulated to obtain particles. The granulation method is not particularly limited. For example, the resin can be added to the soft magnetic metal powder, stirred and dried. In addition, the average particle size and particle size distribution of the particles can also be appropriately adjusted.

[0069] The content ratio of the resin is not particularly limited, and may be, for example, 1.0 to 6.0 parts by weight relative to 100 parts by weight of the soft magnetic metal powder.

[0070] Before mixing the soft magnetic metal powder and the resin, an insulating film may be formed on the surface of the soft magnetic metal particles. For example, a SiO2 film, that is, an insulating film, may be formed by a sol-gel method.

[0071] Coarse particles can also be removed by adding a resin to the soft magnetic metal powder and stirring the mixture and then passing it through a mesh screen. In addition, the resin can also be diluted with a solvent when added to the soft magnetic metal powder. For example, ketones are used as solvents.

[0072] Next, the first center magnetic core 6a1 is prepared by compression molding. Specifically, the obtained particles are filled into a mold and pressed to obtain the first center magnetic core 6a1. The first center magnetic core 6a1 prepared by compression molding is a powder compact containing soft magnetic metal particles and resin.

[0073] The pressure during pressurization is not particularly limited, and the higher the pressure, the higher the filling rate of the soft magnetic metal particles tends to be. For example, it may be 400 MPa to 1000 MPa.

[0074] When forming the first center core 6a1, a magnetic field may be applied while applying pressure. In some cases, the orientation degree of the soft magnetic metal particles can be changed by controlling the direction of application of the magnetic field and / or the magnitude of the magnetic field.

[0075] Furthermore, the first core 6a1 prepared by compression molding may be sintered by firing. For example, the firing time may be set to 0.5 to 3 hours, the firing temperature may be set to 700 to 900° C., and the firing atmosphere may be set to nitrogen. By sintering the first core 6a1, the organic compound contained in the first core 6a1 can be reduced, and finally the first core portion 6a is substantially free of organic compounds.

[0076] (Core 6c1)

[0077] Prepare to have Figure 3 The base core 6c1 is of the shape shown. The method for making the base core 6c1 is not particularly limited, and may be the same as the method for making the first center core 6a1. The soft magnetic metal powder used to make the base core 6c1 may be the same as or different from the soft magnetic metal powder used to make the first center core 6a1. The resin used to make the base core 6c1 may be the same as or different from the resin used to make the first center core 6a1.

[0078] (Cover core 6c2)

[0079] Prepare to have Figure 3 The cover core 6c2 is shaped as shown. The method for making the cover core 6c2 is not particularly limited, and can be the same as the method for making the first core magnetic core 6a1. The soft magnetic metal powder used to make the cover core 6c2 can be the same as or different from the soft magnetic metal powder used to make the first core magnetic core 6a1. The resin used to make the cover core 6c2 can be the same as or different from the resin used to make the first core magnetic core 6a1.

[0080] (Core material)

[0081] In the case of using a core material, there is no particular limitation on the type of 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 for the core material may be the same as or different from the soft magnetic metal powder used to make the first center core magnetic core. The soft magnetic metal powder used for the core material may be the same as or different from the soft magnetic metal powder used to make the base core. The soft magnetic metal powder used for the core material may be the same as or different from the soft magnetic metal powder used to make the cover core. The resin used for the core material may be the same as or different from the resin used to make the first center core magnetic core. The resin used for the core material may be the same as or different from the resin used to make the base core. The resin used for the core material may be the same as or different from the resin used to make the cover core.

[0082] In addition, the shape of the mixture of the soft magnetic metal powder containing soft magnetic metal particles and the resin is not particularly limited. For example, it can be particles or paste. In the case of making a paste, the mixture can also be heated as needed.

[0083] (Insert Part)

[0084] An insertion component 4a1 having a winding portion 4 formed by winding a conductor into a coil shape is prepared. Both ends of the conductor constituting the winding portion 4 are led out to the outside of the winding portion 4 as leads. The terminals may be connected to the leads after the forming described below. The terminals may be connected to the leads in advance before the forming described below. The connection portion between the terminal and the lead may be located on the outside of the outer casing 6c or on the inside of the outer casing 6c. In addition, the shape of the winding portion 4 is not limited to a circle when viewed from the direction of the winding axis. The shape of the winding portion 4 may also be an ellipse, a quadrilateral, or the like when viewed from the direction of the winding axis. Figure 3 to Figure 5 The leads and terminals are omitted. Figure 3 to Figure 5 In the case of winding number and Figure 1 , Figure 2 Although different modes are shown in the figure, the number of windings can be changed appropriately.

[0085] (Integration of the first core magnetic core, base core, cover core, and insert component)

[0086] First, insert the core 6c1 into the mold. Figure 3 As shown in FIG. 1 , the insert member 4a1 and the first center magnetic core 6a1 are arranged at predetermined positions on the base core 6c1.

[0087] Next, the cover core 6c2 is inserted into the mold, as shown in FIG. Figure 3 As shown, the core material may be appropriately filled into the mold before the cover core 6c2 is inserted into the mold. The following description assumes that the core material is not filled.

[0088] Next, forming is performed by heat pressing. Specifically, after heating each core inserted into the mold to a temperature at which the resin softens, the base core 6c1, the first center core magnetic core 6a1, the cover core 6c2 and the insertion component 4a1 inserted into the mold are heat pressed. Each core or insertion component may be heated (preheated) in advance. In addition, the frame or punch of the mold may also be heated. The direction of pressurization is the winding direction of the coil. By applying pressure, the coil and the core are heat pressed and integrated. Each core is deformed by heat pressing. Figure 3 The gap shown is filled with each core appropriately. The pressure during the thermocompression bonding is not particularly limited. For example, it is 100 MPa to 400 MPa. The temperature during the thermocompression bonding is not particularly limited. For example, it is 50° C. to 100° C.

[0089] The base core 6c1, the first center core 6a1, and the cover core 6c2 are integrally formed by thermocompression bonding 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 outer portion 6c is obtained.

[0090] The inductor 2 removed from the mold after thermocompression bonding may be heated to further cure the resin. The heating temperature at this time is not particularly limited and may be set to 150°C to 200°C, for example.

[0091] (Production method 2)

[0092] Hereinafter, Production Method 2 will be described, but points not particularly described are the same as Production Method 1.

[0093] like Figure 4 As shown, the inductor 2 manufactured by the manufacturing method 2 of the inductor 2 in one embodiment of the present disclosure is manufactured by integrating a first core magnetic core 6a1 which will eventually become mainly the first core portion 6a, a base core 6c1 which will eventually become mainly the second core portion 6b and the outer portion 6c, a cover core 6c2 which will eventually become mainly the outer portion 6c, and an insertion component 4a1 having a winding portion 4 composed of an air-core coil, etc.

[0094] exist Figure 3 In the manufacturing method 1 shown in FIG. 1 , the base core 6c1 and the cover core 6c2 both have a shape similar to a can. Figure 4 In the manufacturing method 2 shown, the base core 6c1 has a shape similar to a can, and the cover core 6c2 has a flat plate shape.

[0095] (Production method 3)

[0096] Hereinafter, Production Method 3 will be described, but points not particularly described are the same as Production Method 2.

[0097] like Figure 5 As shown, the inductor 2 manufactured by the manufacturing method 3 of the inductor 2 in one embodiment of the present disclosure is manufactured by integrating a first core magnetic core 6a1 which will eventually become the first core portion 6a, a second core magnetic core 6b1 which will eventually become the second core portion 6b, a base core 6c1 which will eventually become the outer portion 6c, a cover core 6c2 which will eventually become the outer portion 6c, and an insertion component 4a having a winding portion 4 composed of an air-core coil or the like.

[0098] exist Figure 4 In the manufacturing method 2 shown in FIG. 1 , the base core 6c1 has a shape similar to a can. Figure 5 In the production method 3 shown, Figure 4 In the manufacturing method 2 shown, the inner cylindrical portion of the base core 6c1 is separated as the second center magnetic core 6b1.

[0099] In the manufacturing methods 1 and 2, it is easy to manufacture the inductor 2 in which the second core portion 6b and the outer portion 6c are made of the same material. In contrast, in the manufacturing method 3, by making the material of the second core magnetic core 6b1 different from the materials of the other cores, it is easy to manufacture the inductor 2 in which the second core portion 6b and the outer portion 6c are made of different materials.

[0100] (Other production methods)

[0101] The method for making the inductor 2 disclosed in the present invention is not limited to the above method. In particular, as for the shape and number of the cores, as long as the final Figure 1 The inductor 2 shown is not particularly limited. In addition, as shown in the present disclosure, a molded integral type coil component may be used, that is, a coil component in which the entire coil component except for the lead wire portion of the conductor wire is sealed with resin.

[0102] The coil component of the present disclosure is not limited to an inductor. For example, it may also be a coil component such as a transformer or a reactor. However, if it is considered that the coil component of the present disclosure is easy to increase the inductance, and that the transformer and the reactor are difficult to mold into an integral type, the coil component of the present disclosure may also be an inductor.

[0103] The power supply device of the present disclosure includes the above-mentioned coil component and may be a power supply device such as a DC-DC converter or a switching power supply, for example.

[0104] [Example]

[0105] Hereinafter, the present disclosure will be described based on more detailed examples, but the present disclosure is not limited to these examples.

[0106] Experimental Example 1

[0107] The method for producing the inductor samples in each of the examples and comparative examples (excluding sample No. 7) shown in Table 1 will be described.

[0108] First, prepare Figure 3 The first center core 6a1, base core 6c1 and cover core 6c2 of the shape shown in the figure are provided. Furthermore, an insertion component 4a1 having a winding portion 4, lead wires and terminals is prepared. Figure 3 Leads and terminals are omitted.

[0109] (First core)

[0110] Soft magnetic metal powder containing soft magnetic metal particles and resin are prepared as materials for the first center core 6a1. The material of the soft magnetic metal particles is Fe-Si alloy (Fe 95.5 wt%, Si 4.5 wt%). The average particle size of the soft magnetic metal powder is 25 μm. Epoxy resin is used as the resin.

[0111] Next, an insulating film is formed on the surface of the soft magnetic metal particles. Specifically, a SiO2 film, that is, an insulating film, is formed by a sol-gel method. The thickness of the insulating film is about 40 nm.

[0112] Next, the soft magnetic metal powder and the resin are mixed and granulated to obtain particles. Specifically, the resin is added to the soft magnetic metal powder and stirred, and then dried at 40°C for 10 hours. In terms of the resin content, the amount of organic matter in the first core portion 6a of the final inductor sample is the value shown in Table 1. The type of resin is epoxy resin. After adding the resin to the soft magnetic metal powder and stirring, the powder is passed through a mesh to remove coarse particles. Specifically, the powder is passed through a mesh with a mesh size of 100 μm. The average particle size of the particles finally obtained is about 60 μm.

[0113] Next, the obtained particles are filled into a mold for core forming, thereby obtaining a first center core magnetic core 6a1 as a cylinder. The first center core magnetic core 6a1 has the following dimensions in the final inductor sample: S1 of the first center core portion 6a is the value shown in Table 1, the amount of organic matter in the portion corresponding to the first center core portion 6a is all the value shown in Table 1, and the amount of organic matter in the portion corresponding to the outer portion 6c is all the value shown in Table 1. The forming pressure is 600 MPa. The pressurizing direction is parallel to the winding axis direction of the coil in the final coil component.

[0114] (Base core, cover core)

[0115] The shape of the core 6c1 is Figure 3 The shape shown is the shape of the second core portion 6b and the outer portion 6c in the finally obtained inductor sample. The method of manufacturing the base core 6c1 is the same as the method of manufacturing the first core 6a1 except for the following points.

[0116] Regarding the resin content ratio of the base core 6c1, the organic matter content of the second core portion 6b and the organic matter content of the outer portion 6c in the final inductor sample are the values ​​shown in Table 1. In the production of the base core 6c1, the material of the soft magnetic metal particles is Fe 95.5 wt % and Si 4.5 wt %, the average particle size of the soft magnetic metal powder is approximately 25 μm, and the molding pressure is approximately 600 MPa.

[0117] The shape of the cover core 6c2 is Figure 3 The shape shown is the shape of the second core portion 6b and the outer covering portion 6c in the finally obtained inductor sample. The method for manufacturing the cover core 6c2 is the same as the method for manufacturing the base core 6c1.

[0118] The material, average particle size, molding pressure, resin amount, etc. of the base core 6c1 and the cover core 6c2 are controlled so that the inductance L0 before the DC current is applied is about 100 μH. Specifically, the resin amount is changed according to the method for making the first core. Furthermore, if necessary, the average particle size and / or molding pressure of the soft magnetic metal powder are finely adjusted according to the method for making the first core.

[0119] (Insert Part)

[0120] The dimensions of the winding portion 4 in the insert 4a1 are 4.67 mm in outer diameter, 2.80 mm in inner diameter, 0.22 mm in wire diameter (diameter of the conductor 5), 61.5 ts. in winding number, and 4.16 mm in height H. The conductor 5, lead wires, and terminals are made of Cu.

[0121] (Integration of the first core magnetic core, base core, cover core, and insert component)

[0122] First, insert the core 6c1 into the mold. Figure 3 As shown in FIG. 1 , the insert component 4a1 and the first center core 6a1 are arranged at predetermined positions on the base core. Figure 3 As shown, the cover core 6c2 is arranged at a predetermined position.

[0123] Next, the molding is performed by hot pressing. Specifically, the base core 6c1, the first center core 6a1, the insertion component 4a1 and the cover core 6c2 inserted into the mold are heated at 80°C to soften the resin and then pressurized. The pressurization direction is the winding axis direction of the coil. By pressurizing, the coil and each core are hot pressed and integrated. The molding pressure during hot pressing is controlled between 100MPa and 300MPa, so that the inductance L0 before applying the DC current is about 100μH.

[0124] After forming by thermocompression bonding, the inductor 2 removed from the mold is heated to cure the resin. The heating temperature is set to 150° C. to 200° C., and the heating time is set to 1 hour to 3 hours.

[0125] Through the above process, we can obtain Figure 1 The inductor 2 shown in FIG. 1 has an outer casing 6 c of 5.50 mm×5.50 mm×5.15 mm in size and a height of 5.15 mm.

[0126] Comparative Example No. 7 shown in Table 1 does not use the first center core 6a1 but uses Figure 6 The base core 6c1 and the cover core 6c2 of the shapes shown were manufactured under the same conditions as those of Samples Nos. 1 to 6 except for this point.

[0127] In all examples of Experimental Examples 1 to 5 (except for the example of sintering the first core magnetic core described later), the filling rate of the soft magnetic metal particles in the first core portion, the second core portion and the outer portion was 69%, and the average orientation degree of the soft magnetic metal particles was 0.0.

[0128] The filling rate of the soft magnetic metal particles was calculated using a SEM image of a cross section of the measured portion.

[0129] The definition and measurement method of the average orientation degree of soft magnetic metal particles are as follows.

[0130] The average orientation degree of the soft magnetic metal particles is determined using an SEM image of a cross section parallel to the winding axis direction of the coil. The angle formed by the winding axis direction of the coil and the long axis of the soft magnetic metal particle i is set as the deflection angle θi of the soft magnetic metal particle i relative to the winding axis direction of the coil. The number of soft magnetic metal particles is set to N, and the average value of cos2θ of the soft magnetic metal particles is calculated as ∑cos2θi / N (i=1, 2, ..., N). The size of the SEM image of the cross section is set so that N≥100. ∑cos2θi / N is defined as the average orientation degree of the soft magnetic metal particles.

[0131] The direct current resistance Rdc of the inductors of Sample Nos. 1 to 7 was measured. The Rdc was measured using an impedance analyzer (IM3570 manufactured by Hioki Electric Co., Ltd.). The results are shown in Table 1.

[0132] The inductance L0 before applying a direct current was measured for the inductors of Samples No. 1 to 7. The measurement of L0 was performed at a measurement frequency of 1 MHz and a measurement voltage of 500 mV using an RF impedance material analyzer (4491A manufactured by Agilent Technologies, Inc.).

[0133] For the inductors of samples No. 1 to 7, Isat was measured to evaluate the DC superposition characteristics. Specifically, for each inductor, a DC current was applied from 0, and the magnitude of the DC current when the inductance was reduced to 0.70×L0 relative to the inductance L0 when the DC current was 0 was set as Isat (-30%). The results are shown in Table 1. When Isat (-30%) was 2.60A or more, the DC superposition characteristics were good.

[0134] In each inductor of sample No. 1 to 7, the amount of organic matter in the first core part 6a, the second core part 6b and the outer part 6c was confirmed using a thermogravimetric / differential thermal simultaneous measurement device (STA7200RV manufactured by Hitachi High-Technologies). The temperature range of the thermogravimetric / differential thermal analysis method (TG-DTA method) is 30 to 850°C, and the atmospheric gas is nitrogen. The strong heat loss based on the TG-DTA method is regarded as the amount of organic matter. When comparing the first core part 6a, the second core part 6b and the outer part 6c, the conditions other than the amount of organic matter are essentially the same. Therefore, it is inferred that the less the amount of organic matter, the greater the magnetic permeability.

[0135]

Table 1

[0136]

[0137] According to Table 1, the DC superposition characteristics of each Example are good when X calculated from S, S1 and H is within the range of 0.50 to 0.90. In contrast, the DC superposition characteristics of the Comparative Examples where X is outside the above range are inferior to those of the Examples.

[0138] Experimental Example 2

[0139] The method for producing the inductor samples in the examples and comparative examples shown in Table 2 will be described.

[0140] The example, sample No. 9, and the comparative example, sample No. 8 of Experimental Example 2 are different in the dimensions of the insert member 4a1 from the samples No. 1 to 7 of Experimental Example 1. The dimensions of the winding portion 4 in the insert member 4a1 are as follows: the outer diameter is 4.70 mm, the inner diameter is 2.90 mm, the wire diameter (diameter of the conductor 5) is 0.21 mm, the number of windings N is 55.5 ts., and the height H is 3.63 mm. The results are shown in Table 2.

[0141]

Table 2

[0142]

[0143] According to Table 2, the DC superimposition characteristics of the examples in which X was within the range of 0.50 to 0.90 were good, whereas the DC superimposition characteristics of the comparative examples in which X was outside the above range were inferior to those of the examples.

[0144] Experimental Example 3

[0145] The method for producing the inductor samples in the respective examples and comparative examples shown in Table 3 will be described.

[0146] The dimensions of the insert member 4a1 of each embodiment of Experimental Example 3 are different from those of Experimental Example 1. The dimensions of the winding portion 4 in the insert member 4a1 are as follows: the outer diameter is 4.70 mm, the inner diameter is 2.90 mm, the wire diameter (diameter of the conductor 5) is 0.21 mm, the number of windings N is 55.5 ts., and the height H is 3.63 mm.

[0147] Furthermore, unlike Experimental Example 1, the first center core 6a1 was sintered at a sintering temperature of 700°C and a sintering time of 1 hour in a nitrogen atmosphere. The results are shown in Table 3.

[0148] The amount of organic matter in the first core portion 6a of each embodiment of Experimental Example 3 is less than that in each embodiment of Experimental Examples 1 and 2. Therefore, it is estimated that the magnetic permeability of the first core portion 6a is greater than that of the first core portion 6a of each embodiment of Experimental Examples 1 and 2.

[0149]

Table 3

[0150]

[0151] According to Table 3, the DC superimposition characteristics of each Example in which X is within the range of 0.50 to 0.90 are good. In contrast, the DC superimposition characteristics of the Comparative Examples in which X is outside the above range are inferior to those of the Examples.

[0152] Experimental Example 4

[0153] The method for producing the inductor samples in the respective examples shown in Table 4 will be described.

[0154] The dimensions of the insert member 4a1 of each embodiment of Experimental Example 4 are different from those of Experimental Example 1. The dimensions of the winding portion 4 in the insert member 4a1 are as follows: the outer diameter is 4.90 mm, the inner diameter is 3.10 mm, the wire diameter (diameter of the conductor 5) is 0.21 mm, the number of windings N is 52.5 ts., and the height H is 3.50 mm. In addition, the first center core 6a1 of Sample Nos. 15 to 17 is sintered in the same manner as the embodiments of Experimental Example 3. The results are shown in Table 4.

[0155] It is estimated that the magnetic permeability of the first core portion 6a of sample No. 14 of Experimental Example 4 is equivalent to the magnetic permeability of the first core portion 6a in each embodiment of Experimental Examples 1 and 2. It is estimated that the magnetic permeability of the first core portion 6a of sample Nos. 15 to 17 of Experimental Example 4 is equivalent to the magnetic permeability of the first core portion 6a in each embodiment of Experimental Example 3.

[0156]

Table 4

[0157]

[0158] According to Table 4, the DC superimposition characteristics of each Example in which X was within the range of 0.50 or more and 0.90 or less were good.

[0159] Experimental Example 5

[0160] The method for producing the inductor samples in Example and Sample No. 18 shown in Table 5 will be described.

[0161] In Experimental Example 5, Figure 5 As shown in FIG. 1 , the inductor sample is produced by integrating the first center core 6a1, the second center core 6b1, the base core 6c1, the cover core 6c2, and the insertion member 4a1 having the winding portion 4 composed of an air-core coil or the like. The difference between the inductor sample obtained in Experimental Example 5 and the inductor sample of Sample No. 14 is substantially only the amount of organic matter in the second center core portion and the amount of organic matter in the outer portion. The results are shown in Table 5.

[0162]

Table 5

[0163]

[0164] As can be seen from Table 5, even when the organic matter amounts of the first core portion, the second core portion, and the outer casing portion are all different, the DC superposition characteristics of the Examples in which X is within the range of 0.50 to 0.90 are good.

[0165] Experimental Example 6

[0166] The method for producing the inductor samples of the examples and sample Nos. 19 to 21 shown in Table 6 will be described.

[0167] In Experimental Example 6, the dimensions S1 and S of the insert member are the same as those of Sample No. 14.

[0168] In sample No. 14, the amount of organic matter in the first core part was reduced from that in the second core part and the outer part. In contrast, in samples Nos. 19 to 21, the amount of organic matter in the first core part was increased from sample No. 14 to the same as that in the second core part and the outer part.

[0169] In sample No. 19, the average particle size of the soft magnetic metal powder used to make the first center magnetic core was changed from approximately 25 μm to approximately 27 μm.

[0170] In Sample No. 20, the molding pressure of the first core magnetic core was changed so that the filling rate of the soft magnetic metal particles in the first core portion was increased from 69% to 71%.

[0171] In sample No. 21, the average orientation degree of the soft magnetic metal particles in the first core portion is changed from 0.0 to 0.3. Specifically, instead of directly making a cylindrical first core magnetic core by press forming, a sufficiently large quadrangular prism-shaped core is made by press forming. When making a quadrangular prism-shaped core, the pressurizing direction is perpendicular to the winding axis direction of the coil in the final coil component. In addition, the mold is appropriately heated during forming. Then, the quadrangular prism-shaped core is cut to make a cylindrical first core magnetic core.

[0172]

Table 6

[0173]

[0174] According to Table 6, even if other parameters are changed instead of the amount of organic matter in the first core portion, the DC superposition characteristics of each embodiment in the range of X being 0.50 or more and 0.90 or less are good. Sample No. 14 with an organic matter amount of 1.5 wt% has a higher Isat and a good DC superposition characteristic compared to Samples Nos. 19 to 21 with an organic matter amount of 2.4 wt%.

[0175] [Note]

[0176] The technology based on the present disclosure includes the following configuration examples, but is not limited thereto.

[0177] A coil component according to a structural example of the present disclosure includes a core particle and an insulating film formed on a surface of the core particle.

[0178] The invention also comprises a core part including a soft magnetic metal magnetic body and a winding part formed by winding a conductor into a coil shape, wherein the winding part is formed inside the core part, wherein:

[0179] The core portion includes a central core portion located in a portion surrounded by the inner diameter of the winding portion and an outer covering portion located outside the central core portion.

[0180] The core portion includes a first core portion and a second core portion made of different materials.

[0181] The second core portion is arranged around the first core portion.

[0182] The height of the winding portion in the cross section including the winding axis center of the winding portion is denoted as H.

[0183] The cross-sectional area of ​​the central core portion in a cross section perpendicular to the center of the winding axis of the winding portion is denoted as S, and the cross-sectional area of ​​the first central core portion is denoted as S1.

[0184] X defined by the following formula is 0.2500 or more and 0.9050 or less.

[0185]

Mathematical formula 1

[0186]

[0187] In the coil component, the second core portion may be formed of a material different from a material of the exterior portion.

[0188] In any of the coil components described above, the magnetic permeability of the first core portion may be greater than the magnetic permeability of the second core portion.

[0189] In any of the coil components described above, the content ratio of the organic compound in the first core portion may be smaller than the content ratio of the organic compound in the second core portion.

[0190] In any of the above coil components, at least a portion of the core portion may contain substantially no organic compound.

[0191] In any of the above coil components, the content of the organic compound in the first core portion may be 1.5 wt % or less.

[0192] In any of the coil components described above, the first core portion and the second core portion may contain soft magnetic metal particles as the soft magnetic metal magnetic body.

[0193] The average particle size of the soft magnetic metal particles contained in the first core portion is larger than the average particle size of the soft magnetic metal particles contained in the second core portion.

[0194] In any of the coil components described above, the first core portion and the second core portion may contain soft magnetic metal particles as the soft magnetic metal magnetic body.

[0195] The filling rate of the soft magnetic metal particles contained in the first core portion is greater than the filling rate of the soft magnetic metal particles contained in the second core portion.

[0196] In any of the coil components described above, the first core portion and the second core portion may contain soft magnetic metal particles as the soft magnetic metal magnetic body.

[0197] The average orientation degree of the soft magnetic metal particles contained in the first core portion with respect to the winding axis direction of the winding portion is different from the average orientation degree of the soft magnetic metal particles contained in the second core portion with respect to the winding axis direction of the winding portion.

[0198] A power supply device according to a configuration example of the present disclosure includes any of the above-mentioned coil components.

[0199] Description of Reference Numerals

[0200] 2…Inductor

[0201] 4…Winding section

[0202] 5…Conductor

[0203] 6a…first core portion

[0204] 6b…Second core part

[0205] 6c…Exterior

[0206] 4a1…Insert components

[0207] 6a1…First core magnetic core

[0208] 6b1…Second core magnetic core

[0209] 6c1…Core

[0210] 6c2…cover core.

Claims

1. A coil component, wherein: The coil component comprises a core portion including a soft magnetic metal magnetic body and a winding portion formed by winding a conductor, wherein the winding portion is formed inside the core portion. The core portion includes a central core portion located in a portion surrounded by the inner diameter of the winding portion and an outer covering portion located outside the central core portion. The core portion includes a first core portion and a second core portion made of different materials. The second core portion is arranged around the first core portion, The height of the winding portion in the cross section including the winding axis center of the winding portion is denoted as H, The cross-sectional area of ​​the core portion in a cross section perpendicular to the center of the winding axis of the winding portion is denoted as S, and the cross-sectional area of ​​the first core portion is denoted as S1. X defined by the following formula is 0.50 or more and 0.90 or less, 【Mathematical formula 1】 2. The coil component according to claim 1, wherein The material constituting the second core portion is different from the material constituting the exterior portion.

3. The coil component according to claim 1 or 2, wherein: The magnetic permeability of the first core portion is greater than the magnetic permeability of the second core portion.

4. The coil component according to claim 1 or 2, wherein: The content ratio of the organic compound in the first core portion is smaller than the content ratio of the organic compound in the second core portion.

5. The coil component according to claim 1 or 2, wherein: At least a portion of the core is substantially free of organic compounds.

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

7. The coil component according to claim 1 or 2, wherein: The first core portion and the second core portion contain soft magnetic metal particles as the soft magnetic metal magnetic body. The average particle size of the soft magnetic metal particles contained in the first core portion is larger than the average particle size of the soft magnetic metal particles contained in the second core portion.

8. The coil component according to claim 1 or 2, wherein: The first core portion and the second core portion contain soft magnetic metal particles as the soft magnetic metal magnetic body. The filling rate of the soft magnetic metal particles contained in the first core portion is greater than the filling rate of the soft magnetic metal particles contained in the second core portion.

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

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