Coil component and power supply device

Abstract

To provide a coil component of which an inductance and a DC superposition characteristic are high.SOLUTION: A coil component includes: a core part containing a soft-magnetic metal particle and a resin; 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 winding part includes: an inner peripheral surface; an outer peripheral surface; and an end surface. The core part includes: an inner core center region that is positioned in a region of a predetermined range toward an outer side direction that is vertical from a center of a winding shaft of the winding part; and a coil corner part neighbor region where a distance from a coil corner part in which the inner peripheral surface is crossed to the end surface is within the predetermined range. The soft-magnetic metal particle contains a specific particle of which a particle diameter is 10 μm or more and 50 μm or less, and when a mean inter-particle distance of the specific particle in the inner core center region is D1, and a mean inter-particle distance of the specific particle in the coil corner part neighbor region is D2, the following equation is satisfied: 0<D1 / D2<1.00.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Patent Document 1 describes that the improvement of uniformity inside a green body obtained by pressure molding composite magnetic particles leads to improvement in the DC superposition characteristics of a reactor that uses the green body as a core. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-070885 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a coil component having high inductance and DC bias characteristics. [Means for solving the problem]

[0005] In order to achieve the above object, the coil component according to the present disclosure comprises: A coil component having a core portion including soft magnetic metal particles and a resin, and a winding portion around which a conductor is wound, the winding portion being formed inside the core portion, the winding portion has an inner circumferential surface, an outer circumferential surface, and an end surface; the core portion has a center core region located within a predetermined range from a center of a winding axis of the winding portion in a perpendicular outward direction, and a coil corner vicinity region located within a predetermined range of distance from a coil corner where the inner circumferential surface intersects with the end surface, The soft magnetic metal particles include specific particles having a particle size of 10 μm or more and 50 μm or less, and an average inter-particle distance of the specific particles in the center region of the core is D1, an average inter-particle distance of the specific particles in the coil corner vicinity region is D2, and <D1 / D2<1.00である。

[0006] A power supply device according to the present disclosure includes the above-described coil component. [Brief description of the drawings]

[0007] [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] FIG. 2 is an enlarged view of a main part of FIG. [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. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] 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.

[0009] 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.

[0010] Fig. 1 is a cross section passing through and parallel to the winding axis center 4α of the winding portion 4. Fig. 2 is a schematic diagram of a cross section taken along line II in Fig. 1. As shown in Figs. 1 and 2, 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.

[0011] 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 shapes shown in FIGS. 1 and 2.

[0012] 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.

[0013] 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.

[0014] 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 and FIG. 2, the lead parts, terminals, etc. of the winding part 4 are omitted from the illustration. The conductor constituting the winding part 4 may have lead parts formed at both ends, and may be taken out to the outside of the core part 6.

[0015] 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.

[0016] 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.

[0017] The core portion 6 has at least soft magnetic metal particles. 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, 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). 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. When the soft magnetic metal particles are amorphous, the soft magnetic metal particles may be flattened in advance using a crusher or the like. When the soft magnetic metal particles contain crystals, there is no particular restriction on the crystal grain size. The crystal grain size may be, for example, 1 μm or less.

[0018] The soft magnetic metal particles may include Fe-based soft magnetic particles, that is, soft magnetic particles having an Fe content of 90 at % or more.

[0019] There is no particular limit to the average particle size of the soft magnetic metal particles in the core portion 6. The average equivalent circle diameter of the soft magnetic metal particles when the cross section of the core portion 6 is observed by SEM may be 1 μm or more and 100 μm or less. The equivalent circle diameter is the diameter of a circle with the same area. Hereinafter, the equivalent circle diameter of the particles in the cross section may be simply referred to as the particle size.

[0020] The soft magnetic metal particles include specific particles having a particle size of 10 μm or more and 50 μm or less. There is no particular limit to the ratio of the specific particles contained in the soft magnetic metal particles in the core portion 6. The ratio of the total area of ​​the specific particles to the total area of ​​the soft magnetic metal particles in the cross section of the core portion 6 may be 50% or more.

[0021] The core portion 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, polyamide-imide, silicone resin, and combinations thereof. The core portion 6 may contain an epoxy resin as the thermosetting resin.

[0022] Winding portion 4 has an inner circumferential surface 4β1, an outer circumferential surface 4β4, and a first end face 4β2 and a second end face 4β3 located on opposite sides along winding axis center 4α.

[0023] As shown in Fig. 1, the region within 100 µm from the inner circumferential surface 4β1 toward the winding axis center 4α is the winding inner circumference vicinity region 6β1, the region within 100 µm from the first end surface 4β2 toward the outer direction parallel to the winding axis center 4α is the first end surface vicinity region 6β2, and the region within 100 µm from the second end surface 4β3 toward the outer direction parallel to the winding axis center 4α is the second end surface vicinity region 6β3. The winding portion 4 is located in the outward direction perpendicular to the winding axis center 4α, and the region within 280 µm from the winding axis center 4α in the perpendicular outward direction is the center core central region 6α. The region of the core portion 6 that is within 200 µm from the nearest surface is the outer wall region 6γ.

[0024] There is no particular limitation on the density of the core 6. For example, it may be 5.00 g / cm 3 More than 7.00g / cm 3 It may be the following.

[0025] The density of the core central region 6α may be greater than the density of the outer wall region 6γ. When the density of the core central region 6α is greater than the density of the outer wall region 6γ, the DC bias characteristics of the inductor 2 tend to improve.

[0026] As shown in Fig. 1, the intersection of the inner circumferential surface 4β1 and the first end surface 4β2 or the second end surface 4β3 is defined as the coil corner 4β5. As shown in Fig. 3, the portion that is 20 μm or more and 50 μm or less away from the coil corner 4β5 is defined as the coil corner vicinity region 6β5. That is, t1 = 20 μm, t2 = 50 μm.

[0027] The average interparticle distance of a specific particle in the central core region 6α is D1, and the average interparticle distance of a specific particle in the coil corner vicinity region 6β5 is D2. <D1 / D2<1.00である。0.01≦D1 / D2≦0.99であってもよく、0.19≦D1 / D2≦0.70であってもよく、0.19≦D1 / D2≦0.66であってもよい。

[0028] By having D1 / D2 within the above range, it is possible to obtain an inductor 2 with high inductance and DC bias characteristics. If D1 / D2 is too high, the DC bias characteristics are particularly likely to deteriorate.

[0029] Let R1 be the average particle size of the specific particles in the core central region 6α and R2 be the average particle size of the specific particles in the coil corner vicinity region 6β5. The relationship may be 0.20≦R1 / R2≦5.00, 0.50≦R1 / R2≦2.00, or 0.53≦R1 / R2≦1.84.

[0030] By setting R1 / R2 within the above range, even if the density difference between the core central region 6α and the outer wall region 6γ is small, for example, 0.20 g / cm 3 Even if the value is equal to or less than this, the DC bias characteristics of the inductor 2 are likely to be improved.

[0031] The method for measuring R1, R2, D1 and D2 will be described below.

[0032] First, as shown in FIG. 1, the inductor 2 is cut to pass through the winding axis center 4α to obtain a cross section parallel to the winding axis center 4α. Next, the center core central region 6α and the coil corner vicinity region 6β5 are observed using an SEM to obtain SEM images. There are no particular limitations on the magnification and size of the SEM image, and it is sufficient that the magnification and size allow for proper observation of specific particles contained in each region. The magnification may be, for example, 10 to 1000 times.

[0033] Next, specific particles contained in each region are identified. There is no particular limitation on the method for identifying the specific particles. They may be identified visually or by using image analysis software.

[0034] In the core central region 6α, specific particles are those having a particle size of 10 μm to 50 μm and contained entirely in the core central region 6α, whereas in the coil corner neighborhood region 6β5, specific particles are those having a particle size of 10 μm to 50 μm and at least a part of which is contained in the coil corner neighborhood region 6β5.

[0035] (D1, D2) In each region, the inter-particle distance between specific particles adjacent to each other is measured. First, a line segment is drawn between the surfaces of different specific particles so that the length is the shortest. The length of the line segment is the inter-particle distance between specific particles adjacent to each other.

[0036] The "specific particles adjacent to each other" refers to specific particles where, when drawing the line segment, the line segment does not overlap with other soft magnetic metal particles with a particle size of 10 μm or more.

[0037] In each region, all specific particles adjacent to each other are identified, and the inter-particle distance between specific particles adjacent to each other is measured. Then, D1 and D2 are calculated by averaging the measured inter-particle distances.

[0038] The coil corner vicinity region 6β5 may be two corner vicinity regions 6β5 arranged opposite to each other with respect to the winding axis center 4α. In that case, both of the two corner vicinity regions 6β5 may satisfy 0 < D1 / D2 < 1.00. The DC superposition characteristics of the inductor 2 are likely to be improved.

[0039] The coil corner vicinity region 6β5 may be four corner vicinity regions 6β5. In that case, all of the four corner vicinity regions 6β5 may satisfy 0 < D1 / D2 < 1.00. The DC superposition characteristics of the inductor 2 are likely to be improved.

[0040] Particularly when producing the core portion 6 by thermocompression bonding of soft magnetic metal powder and manufacturing the inductor 2 having the shapes shown in FIGS. 1 and 2, in the vicinity of the edge of the coil, that is, in the coil corner vicinity region 6β5, magnetic flux is likely to concentrate and magnetic saturation is likely to occur.

[0041] Therefore, in order to improve both the inductance and the DC superposition characteristics of the entire inductor 2, for the coil corner vicinity region 6β5, it is preferable to locally reduce the magnetic permeability to make magnetic saturation less likely to occur. Therefore, it is preferable that the inter-particle distance of the soft magnetic metal particles is large.

[0042] On the other hand, in the core part including the core central region 6α, it is preferable that the magnetic path is made as short as possible and the magnetic flux flows straight. Therefore, in the core part, it is preferable to locally increase the magnetic permeability. Therefore, it is preferable that the inter-particle distance of the soft magnetic metal particles is small.

[0043] Therefore, when the coil corner vicinity region 6β5 satisfies 0 < D1 / D2 < 1.00, the inductance and DC superposition characteristics of the inductor 2 are improved.

[0044] (R1, R2) For all specific particles included in each region, the particle size is measured. Then, R1 and R2 are calculated by averaging the measured particle sizes.

[0045] Next, the manufacturing method of the inductor 2 shown in FIG. 1 will be described with reference to FIGS. 4 and 5.

[0046] (Manufacturing Method 1) As shown in FIG. 4, the inductor 2 manufactured by the manufacturing method 1 of the inductor 2 in an embodiment of the present disclosure is manufactured by integrating two preforms 60a and 60b and an insert member 40a having a winding part 4 composed of an air core coil or the like.

[0047] (Preform) Prepare a soft magnetic metal powder containing soft magnetic metal particles and a resin as materials for the preforms 60a and 60b.

[0048] 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 may be, for example, spherical, flat, or needle-like.

[0049] To prepare the preform, one type of soft magnetic metal powder may be used, or two or more types of soft magnetic metal powders with different shapes, average particle diameters, compositions, etc. may be mixed. When one type of soft magnetic metal powder is used, there is no particular limit to the average particle diameter of the soft magnetic metal powder. For example, it may be 1 μm or more and 100 μm or less. It is sufficient that the soft magnetic metal powder contains a large number of soft magnetic metal particles that have a particle diameter of 10 μm or more and 50 μm or less and are likely to become specific particles.

[0050] When two or more kinds of soft magnetic metal powders are mixed and used, there is no particular restriction on the average particle size of each soft magnetic metal powder. For example, a soft magnetic metal powder having an average particle size of 10 μm or more and 50 μm or less, which mainly becomes the specific particles, and a soft magnetic metal powder having an average particle size of 1 μm or more and less than 10 μm, which mainly becomes particles smaller than the specific particles, may be mixed and used.

[0051] 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.

[0052] 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.

[0053] 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.

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

[0055] 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.

[0056] Next, the preforms 60a and 60b are prepared by compression molding. Specifically, the obtained granules are filled into a metal mold and pressurized to obtain the preforms 60a and 60b. The preforms 60a and 60b prepared by compression molding are green compacts containing soft magnetic metal particles and resin.

[0057] There is no particular limit to the pressure at the time of pressing, and the higher the pressure, the easier it is to make the soft magnetic metal particles large and flattened. For example, the pressure may be 400 MPa to 1000 MPa.

[0058] In the manufacturing method 1, the preform 60a has a pot shape as shown in Fig. 4. The preform 60b has an RT shape.

[0059] (Integration of preform and insert parts) First, the preform 60a is inserted into the mold. Next, as shown in FIG. 4, the insert member 40a is placed at a predetermined position on the preform 60a. Next, the preform 60b is placed at a predetermined position on the preform 60a and the insert member 40a. Note that the core material may be appropriately filled into the mold before the preform 60b is inserted into the mold. In the following, the description will be given assuming that the core material is not filled. Note that, although the number of turns is different in FIG. 4 and FIG. 5 from FIG. 1 and FIG. 2, the number of turns can be appropriately changed.

[0060] Next, thermocompression bonding is performed. Specifically, the preforms 60a, 60b inserted in a mold are heated to a temperature at which the resin softens, and then the preforms 60a, 60b and the insert member 40a are thermocompression bonded. The preforms 60a, 60b and the insert member 40a may be heated (preheated) in advance. The mold frame and punches may also be heated. The direction of pressure is the winding axis direction of the coil. The winding portion 4 and the core portion 6 are thermocompression bonded and integrated by the pressure. The preforms 60a, 60b are deformed by thermocompression, and the preforms 60a, 60b are appropriately filled in the gaps shown in FIG. 4. There is no particular limit to the pressure during thermocompression bonding. For example, it is 100 MPa to 400 MPa. There is no particular limit to the temperature during thermocompression bonding. For example, it is 50°C to 100°C.

[0061] The preform 60a and the preform 60b are integrally molded by thermocompression bonding to obtain the core portion 6.

[0062] 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.

[0063] (How to control D1 / D2) When the inductor 2 shown in FIG. 1 is obtained by thermocompression bonding each preform and insert member 40a shown in FIG. 4 using the above method, the coil corner vicinity region 6β5, which is the portion where the inner circumferential surface 4β1 and the second end surface 4β3 in FIG. 1 intersect, is located near the portion where the pot-shaped preform 60a and the RT-shaped preform 60b are compressed together.

[0064] In general, the magnetic permeability of the core portion 6 of the inductor 2 improves as the density of the soft magnetic metal powder increases. Therefore, it is preferable to make the entire core portion 6 high density. Therefore, in order to improve the magnetic permeability, it is preferable to combine the preform 60a having a pot-shaped shape, the preform 60b having an RT-shaped shape, and the insert member 40a so that the preform 60a and the preform 60b are combined without any gaps.

[0065] In the manufacturing method 1 of the inductor 2 according to an embodiment of the present disclosure, a taper may be provided at the tip of the preform 60b having an RT shape, that is, at a portion that will finally be located near the coil corner region 6β5. By providing the taper, a gap is generated in a portion located near the coil corner region 6β5 when the preform 60a, the preform 60b, and the insert member 40a are combined.

[0066] When thermocompression bonding preforms containing soft magnetic metal particles and resin, the resin oozes out at the joint. When a taper is provided at the tip of the preform 60b as described above, a large amount of resin oozes out from the preform 60a and the preform 60b into the gap generated by providing the taper. In contrast, relatively few soft magnetic metal particles move from the preform 60a and the preform 60b into the above gap. Therefore, the density of soft magnetic metal particles decreases in the gap generated by providing the taper and in its vicinity, and the average interparticle distance of specific particles increases. That is, D2 increases in the two corner region vicinities 6β5 which are the portions where the inner peripheral surface 4β1 and the second end surface 4β3 intersect.

[0067] In contrast, the average interparticle distance of specific particles in the core central region 6α hardly changes depending on the presence or absence of the above taper. Therefore, D1 hardly changes depending on the presence or absence of the above taper.

[0068] Therefore, by forming the above taper, it is possible to reduce D1 / D2 to less than 1.00 in the two corner region vicinities 6β5 which are the portions where the inner peripheral surface 4β1 and the second end surface 4β3 intersect. That is, for any of the two corner region vicinities 6α5 arranged opposite to each other with respect to the winding axis center 4α, 0 < D1 / D2 < 1.00 can be satisfied.

[0069] In addition to forming the taper, it is possible to control D1 / D2 by changing various conditions etc. particularly in thermocompression bonding.

[0070] D1 / D2 can be adjusted by adjusting the temperature during thermocompression bonding. Increasing the temperature during thermocompression bonding softens the resin, and more resin seeps into the gap. As a result, D2 increases further and D1 / D2 tends to decrease. Conversely, lowering the temperature during thermocompression bonding hardens the resin, and less resin seeps into the gap. On the other hand, the ease with which the soft magnetic metal particles can move into the gap is unlikely to change. As a result, even if a taper is formed, D2 is unlikely to increase and D1 / D2 is unlikely to decrease.

[0071] Using a soft resin also makes it easier for D1 / D2 to decrease when a taper is formed. Conversely, using a hard resin makes it difficult for D1 / D2 to decrease when a taper is formed.

[0072] It is also possible to control D1 / D2 by controlling the particle size of the soft magnetic metal particles contained in the pot-shaped preform 60a and / or the particle size of the soft magnetic metal particles contained in the RT-shaped preform 60b. By making the particle size of the specific particles contained in the RT-shaped preform 60b relatively small, D1 / D2 tends to decrease.

[0073] By relatively reducing the particle size of the soft magnetic metal particles contained in the preform 60b having an RT type shape, the particle size of the soft magnetic metal particles contained in the center core region 6α becomes smaller, and D1 becomes smaller. On the other hand, soft magnetic metal particles move from both the preform 60a and the preform 60b into the gaps created by the tapering. Therefore, even if the particle size of the soft magnetic metal particles contained in the preform 60b having an RT type shape is relatively reduced, D2 is unlikely to become as small as D1. Therefore, by relatively reducing the particle size of the specific particles contained in the preform 60b having an RT type shape, D1 / D2 is likely to decrease.

[0074] (Production Method 2) Hereinafter, the manufacturing method 2 will be described, but unless otherwise specified, it is the same as the manufacturing method 1.

[0075] In Manufacturing Method 2, the top and bottom of FIG. 4 are reversed. Specifically, first, the preform 60b is inserted into the mold. Next, the insert member 40a is placed at a predetermined position on the preform 60b. Next, the preform 60a is placed at a predetermined position on the preform 60b and on the insert member 40a.

[0076] In this case, different from Manufacturing Method 1, the coil corner vicinity region 6β5, which is the portion where the inner peripheral surface 4β1 and the first end surface 4β2 in FIG. 1 intersect, is located near the portion where the preform 60b having an RT shape and the preform 60a having a pot shape are crimped. By forming a taper on the preform 60b having an RT shape, D1 / D2 can be reduced to less than 1.00 in the two corner vicinity regions 6β5 where the inner peripheral surface 4β1 and the first end surface 4β2 intersect. That is, 0 < D1 / D2 < 1.00 can be satisfied in any of the two corner vicinity regions 6α5 arranged opposite to each other with respect to the spool center 4α.

[0077] (Manufacturing Method 3) Hereinafter, Manufacturing Method 3 will be described. Parts not particularly described are the same as those in Manufacturing Method 1.

[0078] As shown in FIG. 5, the inductor 2 manufactured by Manufacturing Method 3 of the inductor 2 in one embodiment of the present disclosure is manufactured by integrating three preforms 60c to 60e and an insert member 40a having a winding portion 4 composed of an air-core coil or the like.

[0079] (Preform) The preforms 60c to 60e are the same as the preforms 60a and 60b except for the shape.

[0080] In Manufacturing Method 3, as shown in FIG. 5, the preforms 60c and 60e have a pot shape, and the preform 60d has a cylindrical shape.

[0081] (Integration of Preform and Insert Member) First, the preform 60c is inserted into the mold. Next, as shown in FIG. 5, the insert member 40a and the preform 60d are placed at a predetermined position on the preform 60c. Next, the preform 60e is placed at a predetermined position on the preforms 60c, 60d and the insert member 40a. Note that the core material may be appropriately filled into the mold before inserting the preform 60d into the mold or before inserting the preform 60e into the mold. In the following, the explanation will be given assuming that the core material is not filled.

[0082] Next, thermocompression bonding is performed. Specifically, the preforms 60c-60eb inserted in a metal mold are heated to a temperature at which the resin softens, and then the preforms 60c-60e and the insert member 40a are thermocompression bonded. The preforms 60c-60e and the insert member 40a may be heated (preheated) in advance. The mold frame and punches of the metal mold may also be heated. The direction of pressure is the winding axis direction of the coil. The winding portion 4 and the core portion 6 are thermocompression bonded and integrated by the pressure. The preforms 60c-60e are deformed by the thermocompression bonding, and the preforms 60c-60e are appropriately filled into the gaps shown in FIG. 5.

[0083] The preforms 60c to 60e are integrally molded by thermocompression bonding to obtain the core portion 6.

[0084] In the method 3 for producing the inductor 2 according to the embodiment of the present disclosure, the tip of the cylindrical preform 60d, i.e., the portion that will ultimately be located near the coil corner neighborhood region 6β5, may be tapered. The tip of the cylindrical preform 60d may be tapered. By tapering the tip, a gap is generated in the portion that is located near the coil corner neighborhood region 6β5 when the preforms 60c to 60e and the insert member 40a are combined.

[0085] When thermocompression bonding preforms containing soft magnetic metal particles and resin, the resin oozes out at the joint. When tapering the tip of the preform 60d as described above, a large amount of resin oozes out from the preforms 60c to 60e into the gaps formed by the tapering. In contrast, relatively few soft magnetic metal particles move from the preforms 60c to 60e into the above-mentioned gaps. Therefore, in the gaps formed by tapering the tips on both sides of the preform 60d and in the vicinity thereof, the density of the soft magnetic metal particles decreases and the average inter-particle distance of the specific particles increases. That is, D2 increases in the two corner-near regions 6β5 which are the intersections of the inner peripheral surface 4β1 and the first end surface 4β2, and in the two corner-near regions 6β5 which are the intersections of the inner peripheral surface 4β1 and the second end surface 4β3. That is, D2 increases in all of the four corner-near regions 6β5 shown in FIG. 1.

[0086] In contrast, the average inter-particle distance of the specific particles in the core central region 6α hardly changes depending on the presence or absence of the above-mentioned taper. Therefore, D1 hardly changes depending on the presence or absence of the above-mentioned taper.

[0087] Therefore, by forming the above-mentioned taper, D1 / D2 can be reduced to less than 1.00 in all of the four corner-near regions 6β5, and 0 < D1 / D2 < 1.00 can be satisfied.

[0088] In manufacturing method 3, D1 / D2 can be reduced to less than 1.00 in all of the four corner-near regions 6β5 of the inductor 2, and 0 < D1 / D2 < 1.00 can be satisfied. That is, it is easier to improve the inductance and the DC superposition characteristics compared with the inductor 2 manufactured by manufacturing methods 1 and 2.

[0089] (Other manufacturing 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.

[0090] 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.

[0091] A power supply device according to the present disclosure includes the coil component described above. For example, the power supply device may be a switching power supply, a power amplifier, or the like. EXAMPLES

[0092] The present disclosure will be described below based on more detailed examples, but the present disclosure is not limited to these examples.

[0093] Example 1 A method for producing inductor samples in each of the examples and comparative examples shown in Table 1 will be described.

[0094] First, preforms 60a and 60b were prepared, each having the shape shown in Fig. 4. Furthermore, an insert member 40a was prepared, which had a winding portion 4, a lead wire, and a terminal. Note that the lead wire and terminal are omitted in Fig. 4.

[0095] (Preform) A soft magnetic metal powder containing soft magnetic metal particles and a resin were prepared as materials for the preform 60a. The material of the soft magnetic metal particles was an Fe-Si alloy (Fe 93.5 wt %, Si 6.5 wt %). The particle size of the soft magnetic metal powder was set so that R2 had the value shown in Table 1. An epoxy resin was used as the resin.

[0096] 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.

[0097] Next, the soft magnetic metal powder and the 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 of the resin was 2 to 3 parts by weight, with the content of the soft magnetic metal powder being 100 parts by weight. 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.

[0098] Next, the obtained granules were filled into a metal mold and core-molded to obtain a pot-shaped preform 60a shown in Fig. 4. The molding pressure was 6 ton / cm. 2 The density D2 of the preform 60a was set to the value shown in Table 1.

[0099] 4 was produced under the same conditions as preform 60a, except for the shape and the particle size of the soft magnetic metal powder. The particle sizes of the soft magnetic metal powder in preform 60b were set so that R1, R2, and R1 / R2 were the values ​​shown in Table 1. The density of preform 60b was set so that D1, D2, and D1 / D2 were the values ​​shown in Table 1.

[0100] In each example, the tip of the preform 60b was appropriately tapered so that D1 / D2 had the value shown in Table 1.

[0101] (Insert material) The dimensions of the winding portion 4 in the insert member 40a 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.

[0102] (Integration of preform and insert parts) First, the preform 60a was inserted into the mold, and then the insert member 40a and the preform 60b were placed in their respective predetermined positions as shown in FIG.

[0103] Next, thermocompression bonding was performed. Specifically, the preforms 60a, 60b and the insert member 40a inserted in the 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 winding axis. The coil and each preform were thermocompression bonded and integrated by the pressure. The molding pressure during thermocompression bonding was 100 MPa.

[0104] After molding by thermocompression, 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. The heating temperature and heating time were appropriately controlled so that D1 / D2 would have the value shown in Table 1.

[0105] Through the above steps, the inductor 2 shown in Fig. 1 was obtained. The dimensions of the core portion 6 of the inductor 2 were 5.50 mm x 5.50 mm x 5.15 mm, and the height was 5.15 mm.

[0106] R1, R2, D1, and D2 of each sample were calculated from SEM images of the cross section obtained by cutting the inductor of each sample at a cross section including the center of the winding axis. The results are shown in Table 1. The magnification of the SEM images was 500 times. R2 and D2 were measured in each of the two corner vicinity regions 6β5, which are the portions where the inner circumferential surface 4β1 and the second end surface 4β3 intersect. It was confirmed that R2 and D2 were consistent with each other in the two corner vicinity regions 6β5. In calculating R1 and R2, soft magnetic metal particles with a particle size of less than 10 μm or more than 50 μm were not taken into account. In calculating D1 and D2, soft magnetic metal particles with a particle size of less than 10 μm were not taken into account.

[0107] For each sample, the inductance L0 before applying a direct current was measured. The measurement was performed using an RF impedance material analyzer (4491A manufactured by Agilent Technologies) at a measurement frequency of 1.0 MHz and a measurement voltage of 500 mV. The results are shown in Table 1.

[0108] For each sample, Isat was measured to evaluate the DC superposition characteristics. Specifically, for each inductor, a direct current was applied starting from 0, and the magnitude of the direct current when the inductance decreased to 0.8×L0 with respect to the inductance L0 at a direct current of 0 was defined as Isat. The results are shown in Table 1.

[0109] For each sample, L0×Isat was calculated. The results are shown in Table 1. When L0×Isat is 6.0 (H×A), it was considered that the inductance and DC superposition characteristics were good. The results are shown in Table 1.

[0110] In all samples, the density of the central core central region 6α1 was greater than the density of the outer wall region 6γ, and the density difference between the central core central region 6α1 and the outer wall region 6γ was 0.20 g / cm 3 This was confirmed using an X-ray density distribution measuring device to be as follows.

[0111]

Table 1

[0112] From Table 1, the coil component with 0 < D1 / D2 < 1.00 had a higher L0×Isat and better inductance and DC superposition characteristics compared to the coil component with D1 / D2 ≥ 1.00.

[0113] [Supplementary Note] The technology according to the present disclosure includes the following configuration examples, but is not limited thereto.

[0114] A coil component according to one configuration example of the present disclosure is A coil component having a core portion including soft magnetic metal particles and a resin, and a winding portion around which a conductor is wound, the winding portion being formed inside the core portion, the winding portion has an inner circumferential surface, an outer circumferential surface, and an end surface; the core portion has a center core region located within a predetermined range from a center of a winding axis of the winding portion in a perpendicular outward direction, and a coil corner vicinity region located within a predetermined range of distance from a coil corner where the inner circumferential surface intersects with the end surface, The soft magnetic metal particles include specific particles having a particle size of 10 μm or more and 50 μm or less, and an average inter-particle distance of the specific particles in the center region of the core is D1, an average inter-particle distance of the specific particles in the coil corner vicinity region is D2, and <D1 / D2<1.00である。

[0115] In the coil component, R1 may be an average grain size of the specific particles in the central region of the core, and R2 may be an average grain size of the specific particles in the regions near the coil corners, where R1 is an average grain size of the specific particles, and R2 is an average grain size of the specific particles in the regions near the coil corners, and 0.20≦R1 / R2≦5.00.

[0116] In any of the coil components described above, the core portion may have an outer wall region whose distance from a surface of the core portion toward an inside is within a predetermined range, The density of the core central region may be greater than the density of the outer wall region.

[0117] In any one of the coil components described above, the density difference between the central core region and the outer wall region is 0.20 g / cm 3 It may be the following.

[0118] In any of the coil components described above, the soft magnetic metal particles may include Fe-based soft magnetic particles.

[0119] In any of the coil components described above, the resin may include an epoxy resin.

[0120] In any of the above coil components, the region near the coil corner may be two regions near the corners arranged opposite to each other with respect to the center of the winding shaft, and any region near the corner may satisfy 0 < D1 / D2 < 1.00.

[0121] In any of the above coil components, the region near the coil corner may have four regions near the corners, and any of the regions near the corner may satisfy 0 < D1 / D2 < 1.00.

[0122] In any of the above coil components, 0.19 ≤ D1 / D2 ≤ 0.70 may be satisfied.

[0123] The power supply device according to one configuration example of the present disclosure has any of the above coil components.

Description of Reference Numerals

[0124] 2... Inductor element 4... Winding part 4α... Center of the winding shaft 4β1... Inner peripheral surface 4β2... First end surface 4β3... Second end surface 4β4... Outer peripheral surface 4β5... Coil corner 5... Conductor 6... Core part 6α... Central region of the core center 6β1... Region near the inner periphery of the winding 6β2... Region near the first end surface 6β3... Region near the second end surface 6β5... Region near the (coil) corner 6γ... Outer wall region 40a... Insert member 60a~60e... Preform

Claims

1. A coil component having a core portion including soft magnetic metal particles and a resin, and a winding portion around which a conductor is wound, the winding portion being formed inside the core portion, the winding portion has an inner circumferential surface, an outer circumferential surface, and an end surface; the core portion has a center core region located within a predetermined range from a center of a winding axis of the winding portion in a perpendicular outward direction, and a coil corner vicinity region located within a predetermined range of distance from a coil corner where the inner circumferential surface intersects with the end surface, The soft magnetic metal particles include specific particles having a particle size of 10 μm or more and 50 μm or less, and the average inter-particle distance of the specific particles in the central region of the core is D1, the average inter-particle distance of the specific particles in the region near the coil corner is D2, and the coil component satisfies 0 < D1 / D2 < 1.

00.

2. 2. The coil component according to claim 1, wherein R1 is an average particle size of the specific particles in the central region of the core, R2 is an average particle size of the specific particles in the regions near the coil corners, and 0.20≦R1 / R2≦5.

00.

3. the core portion has an outer wall region whose distance from a surface of the core portion toward the inside is within a predetermined range, The coil component according to claim 1 or 2, wherein the density of the central core region is greater than the density of the outer wall region.

4. The density difference between the core central region and the outer wall region is 0.20 g / cm 3 The coil component according to claim 3, wherein:

5. The coil component according to claim 1 , wherein the soft magnetic metal particles include Fe-based soft magnetic particles.

6. The coil component according to claim 1 or 2, wherein the resin includes an epoxy resin.

7. 3. The coil component according to claim 1, wherein the coil corner neighborhood regions are two corner neighborhood regions arranged opposite each other with respect to the center of the winding axis, and both of the corner neighborhood regions satisfy 0<D1 / D2<1.

00.

8. 3. The coil component according to claim 1, wherein the coil corner neighborhood region has four corner neighborhood regions, and all of the corner neighborhood regions satisfy 0<D1 / D2<1.

00.

9. 3. The coil component according to claim 1, wherein 0.19≦D1 / D2≦0.

70.

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

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