Coil component and method for manufacturing the coil component

Abstract

To reduce voids generated in an exterior part.SOLUTION: A method for manufacturing a coil component includes: a step of winding a coated conducting wire 30 around a shaft 12 of a core 10 thereby to form a winding part 32, the core having the shaft 12 and a flange 14 provided at one end of the shaft 12; a step of forming lead-out parts 34a and 34b by leading out the coated conducting wire 30 from a pair of ends of the winding part 32, respectively; a step of forming external electrodes 60a and 60b to which the lead-out parts 34a and 34b are electrically connected, respectively; and a step of forming an exterior part 50 covering the entire of the winding part 32, the step including a step of covering, with a first resin material that forms a first exterior part 52, a first part 36 that is a part of the winding part 32, and a step of covering, with a second resin material that forms a second external part 54, a second part 38 of the winding part 32, the second part being different from the first part 36, after the step of covering with the first resin material.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a coil component and a method for manufacturing a coil component. [Background technology]

[0002] A coil component is known that has a core having an axial portion and a flange portion provided at the end of the axial portion, and a winding portion in which a coated conductor wire is wound around the axial portion. In such a coil component, it is known that the winding portion is covered with an exterior portion containing metal magnetic particles and a resin material in order to increase the inductance (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-031960 A Summary of the Invention [Problem to be solved by the invention]

[0004] Coil components are becoming smaller, and as a result, the conductor wires for forming the winding part are becoming thinner. The thinner the conductor wires, the greater the adhesion between the conductor wires, and the harder it is for air to escape when forming an exterior part that covers the winding part. For this reason, voids may be formed inside and outside the exterior part due to air bubbles contained inside the resin material used to form the exterior part and / or air present in the gaps between the conductor wires. If voids exist inside the exterior part, moisture that penetrates from the outside tends to accumulate in the voids. Furthermore, if voids exist outside the exterior part, they not only impair the color tone of the appearance and cause malfunctions in image inspections, but also lead to defects such as exposed conductor wires or abnormal shapes of the exterior.

[0005] The present invention has been made in consideration of the above problems, and has an object to reduce voids occurring in the exterior portion. [Means for solving the problem]

[0006] The present invention relates to a core having a shaft portion and a flange portion provided at one end of the shaft portion, and includes a step of winding a coated conductor around the shaft portion to form a winding portion, a step of drawing out the coated conductor from a pair of ends of the winding portion to form lead-out portions, and a step of forming an external electrode to which the lead-out portions are electrically connected. On the flange forming a portion of the circumferential portion; A first resin material containing a magnetic material and a resin is applied to only the portion of the circumferential portion. The first exterior part The above covering with a first resin material; a step of hardening the first resin material covering only the portion of the circumferential portion; and Then, a part different from the part of the circumferential portion is A second resin material containing a magnetic material and a resin is applied to the different portion of the circumferential portion. The second exterior part The above and covering the circumferential portion with a second resin material. The first resin material is formed on the flange portion to cover the drawn-out portion, a portion where the drawn-out portion is drawn out from the circumferential portion, and only the portion of the circumferential portion. A method for manufacturing a coil component.

[0007] In the above configuration, The magnetic material in the first resin material is different from the magnetic material in the second resin material, and / or the resin in the first resin material is different from the resin in the second resin material. It can be configured as follows.

[0008] In the above configuration, the second exterior portion may be configured to be formed so as to cover the first exterior portion.

[0009] In the above configuration, the first exterior part can be formed by hardening the first resin material, and the second exterior part can be formed by hardening the second resin material after the first exterior part is formed.

[0011] In the above configuration, the first exterior portion can be formed so as to cover the entire circumference of the shaft portion when viewed from the axial direction of the shaft portion, and can be formed so that the area of ​​the first exterior portion in a cross section passing through the center of the shaft portion and parallel to the axial direction of the shaft portion is smaller than the area of ​​the second exterior portion in a cross section parallel to the axial direction of the shaft portion.

[0012] In the above configuration, the first exterior portion can be formed so as to cover the entire circumference of the shaft portion when viewed from the axial direction of the shaft portion, and can be formed so that the area of ​​the first exterior portion in a cross section passing through the center of the shaft portion and parallel to the axial direction of the shaft portion is larger than the area of ​​the second exterior portion in a cross section parallel to the axial direction of the shaft portion.

[0013] In the above configuration, the first exterior portion can be formed so as to cover a part of the shaft portion while leaving a part of the shaft portion at a contact portion which is an inner surface of the flange portion facing the shaft portion and which contacts the shaft portion, and can be formed so that an area of ​​the first exterior portion in a cross section passing through the circumferential portion and perpendicular to the axial direction of the shaft portion is smaller than an area of ​​the second exterior portion in a cross section perpendicular to the axial direction of the shaft portion.

[0014] In the above configuration, the first exterior portion can be formed so as to cover a part of the shaft portion while leaving a part of the shaft portion at a contact portion which is an inner surface of the flange portion facing the shaft portion and which contacts the shaft portion, and can be formed so that an area of ​​the first exterior portion in a cross section passing through the circumferential portion and perpendicular to the axial direction of the shaft portion is larger than an area of ​​the second exterior portion in a cross section perpendicular to the axial direction of the shaft portion.

[0015] In the above configuration, the core may be configured such that a length in the axial direction of the shaft portion is longer than a length in a direction perpendicular to the axial direction.

[0016] In the above configuration, the core may be configured such that a length in the axial direction of the shaft portion is shorter than a length in a direction perpendicular to the axial direction.

[0017] The present invention relates to a core having a shaft portion and a flange portion provided at one end of the shaft portion, a winding portion in which a coated conductor wire is wound around the shaft portion, a pair of ends of the winding portion, the pair of ends being formed by drawing out the coated conductor wires, and an external electrode provided on the flange portion and electrically connected to the pair of draw-out portions; A part of the circumferential portion only Covering the The first one includes a magnetic material and a resin. A first exterior portion made of a resin material is provided to cover a portion different from the portion of the circumferential portion. a second resin material containing a magnetic material and a resin, the magnetic material and the resin being different from each other in at least one of the magnetic material and the resin of the first resin material;and a second exterior portion made of a resin material, and an exterior portion covering the entire circumferential portion. the first exterior portion is provided on the flange portion to cover the drawn-out portion, a portion of the drawn-out portion drawn out from the winding portion, and only the portion of the winding portion; It is a coil component. Effect of the Invention

[0018] According to the present invention, it is possible to reduce voids occurring in the exterior portion. [Brief description of the drawings]

[0019] [Figure 1] 1(a) to 1(f) are side views illustrating a method for manufacturing a coil component according to the first embodiment. [Diagram 2] 2(a) to 2(f) are side views showing a manufacturing method of a coil component according to a first modification of the first embodiment. [Diagram 3] 3(a) to 3(f) are side views showing a method for manufacturing a coil component according to a second modification of the first embodiment. [Figure 4] 4(a) to 4(d) are side views showing a method for manufacturing a coil component according to a comparative embodiment. [Diagram 5] 5(a) is a cross-sectional view taken along line AA in FIG. 1(c), FIG. 5(b) is a cross-sectional view taken along line AA in FIG. 2(c), and FIG. 5(c) is a cross-sectional view taken along line AA in FIG. 3(c). [Figure 6] 6(a) to 6(c) are cross-sectional views showing an example in which the first exterior portion has a larger area than the second exterior portion. [Figure 7] 7(a) to 7(f) are side views showing a method for manufacturing a coil component according to the second embodiment. [Figure 8] 8(a) to 8(f) are side views showing a method for manufacturing a coil component according to a modified example of the second embodiment. [Figure 9] 9(a) to 9(f) are side views showing a method for manufacturing a coil component according to the third embodiment. [Figure 10] 10(a) to 10(f) are side views showing a method for manufacturing a coil component according to a modified example of the third embodiment. [Figure 11] FIG. 11 is a cross-sectional view taken along line AA in FIG. 9(f) and line AA in FIG. 10(f). [Figure 12] FIG. 12 is a cross-sectional view showing an example in which the first exterior portion has a larger area than the second exterior portion. [Figure 13] FIG. 13 shows an example of a coil component in which the mounting surface is parallel to the axial direction of the shaft portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate. However, the present invention is not limited to the illustrated embodiment. In addition, components common to multiple drawings are given the same reference numerals throughout the multiple drawings. Please note that the drawings are not necessarily drawn to scale for the sake of convenience.

[0021] [First embodiment] 1(a) to 1(f) are side views showing a method for manufacturing a coil component according to a first embodiment. FIG. 1(a) to 1(c) are side views as viewed from the +X side, and FIG. 1(d) to 1(f) are side views as viewed from the +Y side. The X-axis, Y-axis, and Z-axis are mutually orthogonal. In FIG. 1(a) to 1(f), each member may be hatched for clarity (the same applies to similar figures below). In addition, in FIG. 1(b) and FIG. 1(e), the winding part 32 and the like are illustrated by seeing through the first exterior part 52, and in FIG. 1(c) and FIG. 1(f), the first exterior part 52 and the winding part 32 and the like are illustrated by seeing through the second exterior part 54. The coil component may be a power inductor incorporated in a power supply line, an inductor used in a signal line, or the like.

[0022] As shown in FIG. 1(a) and FIG. 1(d), a core 10 is prepared, which is a T-core having a shaft portion 12 whose axial direction is in the Z-axis direction and a flange portion 14 joined to the end of the shaft portion 12 on the -Z side. The length of the illustrated core 10 in the Z-axis direction is longer than the lengths in the X-axis and Y-axis directions. With such a structure, the axial length of the exterior portion 50 is longer, and the effect of the present invention is greater. The effect of the present invention can be obtained even if the length of the core 10 in the Z-axis direction is equal to or shorter than the lengths in the X-axis and Y-axis directions. The coated conductor 30 is wound around the shaft portion 12 of the core 10 to form a winding portion 32, and the coated conductor 30 is drawn out from a pair of ends of the winding portion 32 toward the flange portion 14 to form the drawing portions 34a and 34b. For example, the drawing portion 34a corresponds to the start side of winding the coated conductor 30 around the shaft portion 12, and is drawn out from the end of the winding portion 32 on the -Z side toward the flange portion 14. The lead-out portion 34b corresponds to the winding end side, and is drawn out from the end of the winding portion 32 on the +Z side toward the flange portion 14. The lead-out portions 34a and 34b are drawn out into a recess 22 formed on the surface 20 of the flange portion 14 opposite the shaft portion 12. A metal film 24 is formed on the inner surface of the recess 22. After the lead-out portions 34a and 34b are drawn out into the recess 22, the lead-out portions 34a and 34b are electrically connected to the metal film 24 to form external electrodes 60a and 60b.

[0023] The core 10 is formed by filling a cavity of a mold with a magnetic paste, for example, a mixture of magnetic powder and resin, and press-molding the molded body to form a compact having a shaft portion 12 and a flange portion 14, and then performing a heat treatment (for example, at about 200°C) on the compact. For example, ferrite magnetic powder or metal magnetic powder is used as the magnetic powder. For example, Ni-Zn or Mn-Zn ferrite materials are used as the ferrite magnetic powder. For example, Fe-Si-Cr, Fe-Si-Al, or Fe-Si-Cr-Al soft magnetic alloy materials, Fe or Ni magnetic metal materials, amorphous magnetic metal materials, or nanocrystalline magnetic metal materials are used as the metal magnetic powder. For example, polyvinyl butyral (PVB) resin or epoxy resin or other resin with excellent insulating properties is used as the resin.

[0024] The core 10 may be formed by processing a large lump of molded body into a molded body having the shaft portion 12 and the flange portion 14, and then performing a heat treatment on the molded body. The heat treatment may be performed before processing into a molded body having the shaft portion 12 and the flange portion 14. The core 10 is not limited to being formed by solidifying magnetic powder with resin, and may be formed by bonding magnetic powders together with an inorganic substance. In this case, the core 10 is formed by performing a heat treatment at, for example, 600°C to 1100°C on a molded body obtained by press-molding the magnetic powder.

[0025] The shaft portion 12 of the core 10 has a rectangular cross-sectional shape parallel to the XY plane, for example. The flange portion 14 is, for example, a polygonal column having a thickness in the axial direction (Z-axis direction) of the shaft portion 12. The shaft portion 12 may have a cross-sectional shape of a circle, an ellipse, a polygon having pentagons or more, or a combination of these. The flange portion 14 may be a cylinder, an elliptical cylinder, a polygonal column, or a combination of these having a thickness in the axial direction of the shaft portion 12. The shaft portion 12 is smaller than the outer shape of the flange portion 14 and is joined to the vicinity of the center of the flange portion 14. The size of the core 10 is, for example, 0.9 mm to 3 mm in each of the X-axis direction, the Y-axis direction, and the Z-axis direction. The dimensions in the X-axis direction and the Y-axis direction may be equal or unequal, and the dimension in the Z-axis direction may be the maximum or minimum of the dimensions in the X-axis direction, the Y-axis direction, and the Z-axis direction, or may be neither of them. The relative permeability of the core 10 is 30 to 800, and the specific resistance is 1×10 6 Ω·cm or more.

[0026] The metal film 24 is formed by forming a base layer by, for example, a sputtering method or by applying a conductive paste, and then forming a plating layer on the base layer by a plating method. The metal film 24 is a laminated film in which plating layers such as a nickel layer and a tin layer are provided on a base layer such as copper, silver, palladium, or a silver-palladium alloy.

[0027] The winding portion 32 is formed by winding the coated conductor 30 around the shaft portion 12 while the coated conductor wires 30 are in contact with each other. The winding portion 32 may be formed by winding the coated conductor wires 30 in a single layer around the surface of the shaft portion 12, or may be wound in multiple overlapping layers. The winding portion 32 may be formed by so-called α winding, in which the central portion of the coated conductor wire 30 is wound first, and then the coated conductor wire 30 is wound toward both ends.

[0028] The coated conductor 30 has a core wire made of, for example, copper, the circumferential surface of which is covered with an insulating coating made of polyimide. The core wire may be made of a metal other than copper, for example, silver, palladium, or a silver-palladium alloy. The insulating coating may be made of an insulating material other than polyamideimide, for example, a resin material such as polyamideimide, polyurethane, or polyester. The cross-sectional shape of the core wire may be circular or rectangular. An adhesive layer may be provided on the circumferential surface of the insulating coating.

[0029] The external electrodes 60a and 60b are formed by applying flux to the ends of the lead-out portions 34a and 34b located within the recesses 22, and then heating the ends together with solder to remove the insulating coating of the lead-out portions 34a and 34b and expose the core wires, and then joining the core wires to the metal film 24 with solder.

[0030] As shown in FIG. 1(b) and FIG. 1(e), the first exterior part 52 is formed by covering only a part (referred to as the first part 36) of the winding part 32 with a first resin material made by mixing a magnetic material and a resin. For example, the first resin material is applied only to the first part 36 of the winding part 32 by brushing, roller transfer, dispensing, or the like to form a first resin part, and then hardened to form the first exterior part 52. In the first embodiment, the first exterior part 52 is formed to cover only the first part 36 of the winding part 32 so as to cover the lead-out part 34a and the part 40a where the coated conductor 30 is led out as the lead-out part 34a from the end of the winding part 32. The first exterior part 52 is also formed to cover the entire circumference of the shaft part 12 at the contact part 18 which is the inner surface of the flange part 14 on the shaft part 12 side and is in contact with the shaft part 12.

[0031] The first resin material used to form the first exterior portion 52 is formed by mixing, for example, ferrite and epoxy resin, but may be formed by mixing other magnetic materials and resins. The first resin material may contain a non-magnetic material such as silica particles. The resin contained in the first resin material is a thermosetting resin with excellent insulating properties, and may be, for example, epoxy resin, polyimide resin, polystyrene (PS) resin, high density polyethylene (HDPE) resin, polyoxymethylene (POM) resin, polycarbonate (PC) resin, polyvinylidene fluoride (PVDF) resin, phenolic resin, polytetrafluoroethylene (PTFE) resin, polybenzoxazole (PBO) resin, or any other known resin used to cover a winding in a wound coil component.

[0032] As shown in FIG. 1(c) and FIG. 1(f), the second exterior part 54 is formed by covering the second part 38 of the winding part 32 other than the first part 36 with a second resin material obtained by mixing a magnetic material and a resin. For example, the second resin material is applied to the second part 38 of the winding part 32 by brushing, roller transfer, dispensing, or the like to form a second resin part, and then hardened to form the second exterior part 54. In the first embodiment, the second exterior part 54 is formed to cover the second part 38 of the winding part 32 and the first exterior part 52. As a result, the exterior part 50 is formed, which is made of the first exterior part 52 and the second exterior part 54 and covers the entire winding part 32. The relative permeability of the exterior part 50 is 3 to 30, and the specific resistance is 1×10 7 Ω·cm or more.

[0033] The second resin material used to form the second exterior part 54 is formed by mixing, for example, ferrite and epoxy resin, but may be formed by mixing other magnetic materials and resins. The second resin material may be formed by the same magnetic material and the same resin as the first resin material, or at least one of the magnetic material and the resin may be different. By making the first resin material and the second resin material different, it is possible to give different functions to the first exterior part 52 and the second exterior part 54. The magnetic materials being the same may be when the average particle size of the magnetic particles is the same and the elemental composition of the magnetic particles is the same, or when the average particle size is the same but the composition is different, or when the average particle size is different but the composition is the same. The average particle size being the same means that the difference in the average particle size is 5% or less. The composition being the same means that the difference in the composition ratio of the elements is 5wt% or less (weight percent). The average particle size can be obtained, for example, by observing the cross sections of the first exterior portion 52 and the second exterior portion 54, and calculating the area-average particle size when the area of ​​each particle is approximated to a circle from images taken with a scanning electron microscope that include several hundred magnetic particles present in each exterior portion.

[0034] In this way, the coil component according to the first embodiment is formed. The size of the coil component is not particularly limited, but is, for example, 1 mm to 3 mm in each of the X-axis direction, the Y-axis direction, and the Z-axis direction, for example, 1.6 mm to 8.0 mm in the X-axis direction and the Y-axis direction, and 1.0 mm to 4.5 mm in the Z-axis direction.

[0035] [Modification of the first embodiment] 2(a) to 2(f) are side views showing a method for manufacturing a coil component according to Modification 1 of the first embodiment. FIG. 2(a) to FIG. 2(c) are side views as viewed from the +X side, and FIG. 2(d) to FIG. 2(f) are side views as viewed from the +Y side. In Modification 1 of the first embodiment, as shown in FIG. 2(a) and FIG. 2(d), a core 11 is prepared, which is a drum core having a shaft portion 12 whose axial direction is the Z-axis direction, a flange portion 14 joined to the end of the shaft portion 12 on the -Z side, and a flange portion 16 joined to the end of the shaft portion 12 on the +Z side. The length of the illustrated core 11 in the Z-axis direction is longer than the lengths in the X-axis and Y-axis directions. Other manufacturing steps are the same as those in the first embodiment, and therefore will not be described.

[0036] Figures 3(a) to 3(f) are side views showing a manufacturing method of a coil component according to Modification 2 of the first embodiment. Figures 3(a) to 3(c) are side views as viewed from the +X side, and Figures 3(d) to 3(f) are side views as viewed from the +Y side. In Modification 2 of the first embodiment, as shown in Figures 3(c) and 3(f), the second exterior portion 54 is formed without covering the first exterior portion 52. The other manufacturing steps are the same as those of the first embodiment, and therefore will not be described.

[0037] [Comparative form] Figures 4(a) to 4(d) are side views showing a method for manufacturing a coil component according to a comparative embodiment, where Figures 4(a) and 4(b) are side views as viewed from the +X side, and Figures 4(c) and 4(d) are side views as viewed from the +Y side.

[0038] As shown in Figures 4(a) and 4(c), a coated conductor 130 is wound around the shaft 112 of a core 110 having a shaft 112 and a flange 114 to form a winding portion 132, and the coated conductor 130 is drawn out from a pair of ends of the winding portion 132 to form lead-out portions 134a and 134b. The ends of the lead-out portions 134a and 134b drawn into a recess 122 formed in a surface 120 of the flange 114 are electrically connected to the metal film 124 to form external electrodes 160a and 160b. The manufacturing method for each portion is the same as that of the first embodiment except for the method for forming the exterior portion 150, and therefore description thereof will be omitted.

[0039] 4(b) and 4(d), the entire winding portion 132 is covered with a resin material that is a mixture of a magnetic material and a resin, thereby forming an exterior portion 150 that covers the entire winding portion 132. For example, the resin material is applied to the entire winding portion 132 by brush painting, roller transfer, dispensing, or the like, and then cured to form the exterior portion 150. In this manner, a coil component according to a comparative embodiment is formed.

[0040] According to the comparative embodiment, the entire winding portion 132 is covered with a resin material at once to form the exterior portion 150 that covers the entire winding portion 132. As the coil components become smaller, the coated conductor 130 becomes thinner and the adhesion of the coated conductor 130 increases. For this reason, when the exterior portion 150 is formed by covering the entire winding portion 132 with a resin material at once, the amount of resin material applied is large and the contact area between the resin material and the winding portion 132 is large, making it difficult for air bubbles contained inside the resin material and / or air present in the gaps in the coated conductor 130 to escape. For this reason, many voids are generated inside and outside the exterior portion 150.

[0041] Furthermore, when a resin material obtained by mixing a magnetic material and a resin is used to form the exterior part 150, the proportion of the magnetic material is increased as the thickness of the exterior part 150 decreases due to miniaturization of the coil components. This reduces the wettability and spreadability of the resin material, making it easier for voids to form inside and outside the exterior part 150.

[0042] If many voids are formed inside and outside the exterior part 150, unevenness will be formed on the surface of the exterior part 150, resulting in poor appearance and / or dimensional abnormalities, etc. Furthermore, when the exterior part 150 is formed using a resin material in which a magnetic material and a resin are mixed, the formation of voids will cause variations in the filling rate of the magnetic material, making electrical characteristics such as inductance unstable.

[0043] According to the first embodiment and its modified examples 1 and 2, the first portion 36, which is a part of the winding portion 32, is covered with the first resin material that becomes the first exterior portion 52, and after covering with the first resin material, the second portion 38, which is different from the first portion 36 of the winding portion 32, is covered with the second resin material that becomes the second exterior portion 54, thereby forming the exterior portion 50 that covers the entire winding portion 32. By forming the exterior portion 50 in multiple steps in this manner, it is possible to reduce voids generated inside and outside the exterior portion 50 compared to the case where the exterior portion 150 is formed at one time as in the comparative embodiment. That is, by forming the first exterior portion 52 by covering only the first portion 36, which is a part of the winding portion 32, with the first resin material, the amount of the first resin material applied is reduced and the area where the first resin material contacts the winding portion 32 is reduced, so that air bubbles contained inside the first resin material and air present in the gaps of the coated conductor 30 are easily released, and the number of voids generated inside and outside the first exterior portion 52 is reduced. Similarly, in the second exterior portion 54, the amount of the second resin material applied is small and the area of ​​contact between the second resin material and the circumferential portion 32 is small, so that fewer voids are generated inside and outside the second exterior portion 54. Therefore, fewer voids are generated inside and outside the exterior portion 50. By reducing the number of voids inside and outside the exterior portion 50, irregularities are less likely to be formed on the surface of the exterior portion 50, and the occurrence of poor appearance and dimensional abnormalities is reduced. Note that the exterior portion 50 covering the entire circumferential portion 32 means that the outer surface of the circumferential portion 32 is not exposed from the exterior portion 50, meaning that it is covered 100%.

[0044] Furthermore, when the first exterior portion 52 is formed from a first resin material obtained by mixing a magnetic material with a resin, and the second exterior portion 54 is formed from a second resin material obtained by mixing a magnetic material with a resin, the number of voids inside the exterior portion 50 is reduced, thereby making it possible to keep the variation in the filling rate of the magnetic material low. This makes it possible to keep the variation in electrical properties such as inductance low. Furthermore, the reduction in voids makes it possible to obtain an exterior portion 50 with a high filling rate of the magnetic material.

[0045] In the first embodiment and its first and second modifications, the first exterior part 52 is formed to cover the lead-out part 34a and the part 40a where the coated conductor 30 is led out as the lead-out part 34a from the end of the winding part 32. The coated conductor 30 is densely arranged near the part 40a where the coated conductor 30 is led out as the lead-out part 34a from the end of the winding part 32, so that a large amount of air exists in the gaps between the coated conductor 30. For this reason, the first exterior part 52 is first formed to cover the part 40a where the coated conductor 30 is led out as the lead-out part 34a from the end of the winding part 32, thereby allowing air existing near the lead-out part 40a to escape, thereby reducing voids occurring inside and outside the first exterior part 52. In addition, by forming the first exterior part 52 to cover the lead-out part 40a, the path of air flowing from the winding part 32 along the lead-out part 34a can be sealed or narrowed. As a result, when the second exterior portion 54 is formed after the first exterior portion 52 is formed, air is prevented from flowing toward the first exterior portion 52 and is more likely to flow toward the outside, reducing the number of voids generated inside and outside the exterior portion 50. Also, the path of air flowing from the winding portion 32 along the pull-out portion 34a is sealed or narrowed, thereby preventing moisture from penetrating into the winding portion 32 along the pull-out portion 34a.

[0046] In the first embodiment and its first and second modifications, the lead-out portion 34a is the lead-out portion on the start side of the winding when the coated conductor 30 is wound around the shaft portion 12. The lead-out portion 34a on the start side of the winding is located at either the +Z end or the -Z end of the winding portion 32. On the other hand, the position of the lead-out portion 34b on the end side of the winding cannot be specified depending on the number of turns of the coated conductor 30 to obtain a desired inductance. Therefore, in order to reduce voids generated inside and outside the exterior portion 50 by effectively releasing air in the portion where the coated conductor 30 is drawn out from the end of the winding portion 32, where a large amount of air exists in the gaps in the coated conductor 30, it is preferable that the first exterior portion 52 is formed to cover the lead-out portion 34a on the start side of the winding and the portion 40a where the coated conductor 30 is drawn out as the lead-out portion 34a from the end of the winding portion 32.

[0047] In the first embodiment and its modified example 1, the second exterior portion 54 is formed so as to cover the first exterior portion 52. This makes it possible to suppress the intrusion of moisture into the circumferential portion 32 along the interface between the first exterior portion 52 and the second exterior portion 54. Also, since the boundary between the first exterior portion 52 and the second exterior portion 54 cannot be seen from the outside, a good appearance can be obtained. Furthermore, when the second exterior portion 54 is formed so as to cover the first exterior portion 52, the first exterior portion 52 is formed thin, so that air bubbles contained inside the first resin material can be easily removed when the first resin material is applied, and the number of voids generated inside the first exterior portion 52 is further reduced.

[0048] In the first embodiment and its modified examples 1 and 2, a first resin material is applied to a first portion 36 of the surrounding portion 32 and cured to form the first exterior portion 52, and after the first exterior portion 52 is formed, a second resin material is applied to a second portion 38 of the surrounding portion 32 and cured to form the second exterior portion 54. In this manner, by curing the first resin material and the second resin material separately, the amount of resin on the surface of the first exterior portion 52 is increased, and it is possible to suppress the intrusion of moisture into the surrounding portion 32 through the first exterior portion 52.

[0049] In the first embodiment and its modifications 1 and 2, the length of the cores 10 and 11 in the axial direction (Z-axis direction) of the shaft portion 12 is longer than the length in the directions perpendicular to the axial direction (X-axis direction and Y-axis direction). This allows the number of turns of the winding portion 32 to be increased, resulting in a large inductance.

[0050] FIG. 5(a) is a cross-sectional view taken along line AA in FIG. 1(c), FIG. 5(b) is a cross-sectional view taken along line AA in FIG. 2(c), and FIG. 5(c) is a cross-sectional view taken along line AA in FIG. 3(c). FIG. 5(a) to FIG. 5(c) are cross-sectional views taken along a line parallel to the axial direction (Z-axis direction) of the shaft portion 12, passing through the center of the shaft portion 12. As shown in FIG. 5(a) to FIG. 5(c), the area of ​​the first exterior portion 52 is smaller than that of the second exterior portion 54, and the area of ​​the second exterior portion 54 is larger than that of the first exterior portion 52. In this way, in a cross-sectional view taken along a line parallel to the axial direction of the shaft portion 12, passing through the center of the shaft portion 12, the area of ​​the first exterior portion 52 is smaller than that of the second exterior portion 54, so that the amount of the first resin material applied to form the first exterior portion 52 is reduced. This prevents the first resin material from being applied to unintended locations due to dripping of the first resin material. This prevents the air discharge path from being blocked or narrowed, thereby reducing voids generated inside and outside the exterior part 50. The cross-sectional area of ​​the first exterior part 52 may be ⅓ or less, ¼ or less, or ⅕ or less of the cross-sectional area of ​​the second exterior part 54.

[0051] In the first embodiment and its first and second modifications, in a cross section passing through the center of shaft portion 12 and parallel to the axial direction of shaft portion 12, first exterior portion 52 may be formed to have a larger area than second exterior portion 54. Figures 6(a) to 6(c) are cross sections showing an example in which first exterior portion 52 has a larger area than second exterior portion 54. In this case, the amount of second resin material used to form second exterior portion 54 is reduced and the area of ​​contact between the second resin material and circumferential portion 32 is reduced, making it possible to reduce voids generated inside second exterior portion 54.

[0052] In addition, as in the above-mentioned first embodiment and its modified example 1, when the second exterior part 54 is formed to cover the first exterior part 52, if either the first exterior part 52 or the second exterior part 54 is thin in the part where the first exterior part 52 and the second exterior part 54 are stacked, there is a concern that the mechanical strength of the thinner exterior part will decrease. Therefore, in the part where the first exterior part 52 and the second exterior part 54 are stacked, it is preferable that the thicknesses of the first exterior part 52 and the second exterior part 54 are approximately the same. In this case, in a cross section passing through the center of the shaft part 12 and parallel to the axial direction of the shaft part 12, the first exterior part 52 is formed to have a smaller area than the second exterior part 54.

[0053] [Second embodiment] Fig. 7(a) to Fig. 7(f) are side views showing a method for manufacturing a coil component according to a second embodiment. Fig. 7(a) to Fig. 7(c) are side views as viewed from the +X side, and Fig. 7(d) to Fig. 7(f) are side views as viewed from the +Y side. In the second embodiment, as shown in Fig. 7(a) and Fig. 7(d), both of the drawn-out portions 34a and 34b are drawn out from the end of the winding portion 32 on the +Z side toward the flange portion 14.

[0054] As shown in Figures 7(b) and 7(e), a first exterior portion 52 is formed by covering only a portion of the winding portion 32 (referred to as first portion 36) with a first resin material so as to cover the pull-out portion 34a and a portion 40a where the coated conductor 30 is pulled out from the end of the winding portion 32 as pull-out portion 34a, and also to cover the pull-out portion 34b and a portion 40b where the coated conductor 30 is pulled out from the end of the winding portion 32 as pull-out portion 34b.

[0055] 7(c) and 7(f), the second portion 38 other than the first portion 36 of the circumferential portion 32 is covered with a second resin material to form a second exterior portion 54. In the second embodiment, the +Z side surface of the first exterior portion 52 and the +Z side surface of the second exterior portion 54 are substantially flush with each other.

[0056] The details of the method for manufacturing the coil component according to the second embodiment are the same as those of the method for manufacturing the coil component according to the first embodiment, and therefore the description thereof will be omitted. In this manner, the coil component according to the second embodiment is formed.

[0057] [Modification of the second embodiment] Figures 8(a) to 8(f) are side views showing a manufacturing method of a coil component according to a modified example of the second embodiment. Figures 8(a) to 8(c) are side views as viewed from the +X side, and Figures 8(d) to 8(f) are side views as viewed from the +Y side. In the modified example of the second embodiment, as shown in Figures 8(a) and 8(d), a core 11 is prepared, which is a drum core having a shaft portion 12 and flange portions 14 and 16. The other manufacturing steps are the same as those of the second embodiment, and therefore will not be described.

[0058] In the second embodiment and its modified example, the first portion 36, which is a part of the circumferential portion 32, is covered with a first resin material that becomes a first exterior portion 52, and after covering with the first resin material, a second portion 38 different from the first portion 36 of the circumferential portion 32 is covered with a second resin material that becomes a second exterior portion 54, thereby forming an exterior portion 50 that covers the entire circumferential portion 32. This makes it possible to reduce voids generated inside and outside the exterior portion 50.

[0059] In the second embodiment and its modified example, the first exterior portion 52 is formed to cover the pull-out portion 34a and the portion 40a where the coated conductor 30 is pulled out as the pull-out portion 34a from the end of the winding portion 32, and to cover the pull-out portion 34b and the portion 40b where the coated conductor 30 is pulled out as the pull-out portion 34b from the end of the winding portion 32. This makes it easier for air to escape near the portions 40a and 40b where the coated conductor 30 is pulled out from the end of the winding portion 32, and reduces voids generated inside and outside the first exterior portion 52.

[0060] In the second embodiment and its modified example, the first exterior portion 52 may be formed to cover a portion of the winding portion 32 on the -Z side that does not include the portions 40a and 40b where the coated conductor 30 is led out from the end of the winding portion 32. In this case, even if the formation area of ​​the first exterior portion 52 is made larger, voids generated inside and outside the first exterior portion 52 can be reduced, compared to the case where the first exterior portion 52 is formed to cover the portions 40a and 40b where the coated conductor 30 is led out from the end of the winding portion 32. Therefore, the formation area of ​​the second exterior portion 54 can be made smaller, and voids generated inside and outside the second exterior portion 54 can be suppressed.

[0061] [Third embodiment] 9(a) to 9(f) are side views showing a method for manufacturing a coil component according to the third embodiment. FIG. 9(a) to FIG. 9(c) are side views as viewed from the +X side, and FIG. 9(d) to FIG. 9(f) are side views as viewed from the +Y side. As shown in FIG. 9(a) and FIG. 9(d), a core 10a is prepared, which is a T-core whose length in the Z-axis direction is shorter than its lengths in the X-axis direction and the Y-axis direction. The coated conductor 30 is wound around the shaft portion 12 of the core 10a to form a winding portion 32, and the coated conductor 30 is drawn from a pair of ends of the winding portion 32 toward the flange portion 14 to form the lead-out portions 34a and 34b. The lead-out portions 34a and 34b are electrically connected to the metal film 24 to form the external electrodes 60a and 60b. The manufacturing methods of the winding portion 32, the lead portions 34a and 34b, and the external electrodes 60a and 60b are the same as those in the first embodiment, and therefore will not be described.

[0062] 9(b) and 9(e), a first exterior portion 52 is formed by covering only a portion (referred to as a first portion 36) of the winding portion 32 with a first resin material. In the third embodiment, the first exterior portion 52 is formed so as to cover only the first portion 36 of the winding portion 32 by covering the lead-out portion 34a and the portion 40a where the coated conductor 30 is led out as the lead-out portion 34a from the end of the winding portion 32, and to cover the lead-out portion 34b and the portion 40b where the coated conductor 30 is led out as the lead-out portion 34b from the end of the winding portion 32, and to cover a part of the inner surface of the flange portion 14 on the shaft portion 12 side, leaving only a part of the outer periphery of the shaft portion 12 at the contact portion 18 that contacts the shaft portion 12.

[0063] 9(c) and 9(f), the second portion 38 of the circumferential portion 32 other than the first portion 36 is covered with a second resin material to form a second exterior portion 54. In the third embodiment, the second exterior portion 54 is formed so as to cover the second portion 38 of the circumferential portion 32 without covering the first exterior portion 52.

[0064] The details of the manufacturing method of the coil component according to the third embodiment are the same as those of the manufacturing method of the coil component according to the first embodiment, and therefore the description will be omitted. In this manner, the coil component according to the third embodiment is formed.

[0065] [Modification of the third embodiment] 10(a) to 10(f) are side views showing a method for manufacturing a coil component according to a modified example of the third embodiment. FIG. 10(a) to FIG. 10(c) are side views as viewed from the +X side, and FIG. 10(d) to FIG. 10(f) are side views as viewed from the +Y side. In the modified example of the third embodiment, as shown in FIG. 10(a) and FIG. 10(d), a core 11a is prepared, which is a drum core having a shaft portion 12 and flange portions 14 and 16. The length of the core 11a in the Z-axis direction is shorter than the lengths in the X-axis and Y-axis directions. The other manufacturing steps are the same as those of the third embodiment, and therefore will not be described.

[0066] In the third embodiment and its modified example, the first portion 36, which is a part of the circumferential portion 32, is covered with a first resin material that becomes a first exterior portion 52, and after covering with the first resin material, a second portion 38 different from the first portion 36 of the circumferential portion 32 is covered with a second resin material that becomes a second exterior portion 54, thereby forming an exterior portion 50 that covers the entire circumferential portion 32. This makes it possible to reduce voids generated inside the exterior portion 50.

[0067] In the third embodiment and its modified example, the length of cores 10a and 11a in the axial direction (Z-axis direction) of shaft portion 12 is shorter than the length in the directions (X-axis direction and Y-axis direction) perpendicular to the axial direction. In this way, the short shaft portion 12 allows for a low height, thereby realizing a compact coil component.

[0068] FIG. 11 is a cross-sectional view taken along line AA in FIG. 9(f) and line AA in FIG. 10(f). FIG. 11 is a cross-sectional view that passes through the circumferential portion 32 and is perpendicular to the axial direction (Z-axis direction) of the shaft portion 12. For the sake of explanation, the drawn-out portion 34a and the drawn-out portion 34b that are not shown in this cross-sectional view are illustrated by dashed lines in FIG. 11 (the same applies to FIG. 12 described later). As shown in FIG. 11, the first exterior portion 52 covers the drawn-out portion 34a and the drawn-out portion 34b, and is formed small on the side having the drawn-out portion 34a and the drawn-out portion 34b and on one side adjacent to that side. Since the second exterior portion 54 is formed after the formation of the first exterior portion 52, at the corner portion where the first exterior portion 52 and the second exterior portion 54 meet, the corner portion not occupied by the first exterior portion 52 formed earlier is occupied by the second exterior portion 54. Therefore, the area of ​​the first exterior portion 52 is smaller than the area of ​​the second exterior portion 54 , and the area of ​​the second exterior portion 54 is larger than the area of ​​the first exterior portion 52 .

[0069] In the third embodiment and its modified examples, the first exterior part 52 is formed so as to cover a part of the outer periphery of the shaft part 12 at the contact part 18, which is the inner surface of the flange part 14 on the shaft part 12 side and contacts the shaft part 12. In the first and second embodiments and their modified examples, the first exterior part 52 is formed by applying the first resin material while rotating the cores 10 and 11, but in the third embodiment and its modified examples, the first exterior part 52 can be formed by applying the first resin material without rotating the cores 10a and 11a, improving ease of manufacture. In addition, in order to provide a part of the circumferential part 32 to which the first resin material is not applied, it is preferable to apply the first resin material once rather than applying it multiple times. When applying the first resin material once, it is difficult to apply the first resin material exactly to half of the outer periphery of the circumferential part 32, so it is preferable to apply the first resin material to an area smaller than half of the outer periphery of the circumferential part 32. 11, in a cross section passing through the winding portion 32 and perpendicular to the axial direction of the shaft portion 12, the first exterior portion 52 is formed to have a smaller area than the second exterior portion 54. The cross-sectional area of ​​the first exterior portion 52 may be 1 / 3 or less, 1 / 4 or less, or 1 / 5 or less of the cross-sectional area of ​​the second exterior portion 54. Note that the second resin material only covers the parts of the winding portion 32 that are not covered by the first exterior portion 52, and there is no need to provide parts of the winding portion 32 that are not coated with the second resin material, so there is no problem even if the second resin material is applied multiple times.

[0070] In the third embodiment and its modified example, the first exterior part 52 may be formed to have a larger area than the second exterior part 54 in a cross section passing through the circumferential part 32 and perpendicular to the axial direction of the shaft part 12. FIG. 12 is a cross-sectional view showing an example in which the first exterior part 52 has a larger area than the second exterior part 54. As shown in FIG. 12, the first exterior part 52 covers the drawn-out parts 34a and 34b, and is formed to be larger on the side having the drawn-out parts 34a and 34b and on one side adjacent to that side. Since the second exterior part 54 is formed after the formation of the first exterior part 52, the first exterior part 52 formed earlier occupies the corner where the first exterior part 52 and the second exterior part 54 meet. Therefore, the area of ​​the first exterior part 52 is larger than the area of ​​the second exterior part 54, and the area of ​​the second exterior part 54 is smaller than the area of ​​the first exterior part 52.

[0071] 12, in a cross section passing through the winding portion 32 and perpendicular to the axial direction of the shaft portion 12, the first exterior portion 52 may be formed to have a larger area than the second exterior portion 54. By forming the first exterior portion 52 to be larger, it becomes easy to form it so as to cover the lead-out portion 34a and the portion 40a where the coated conductor 30 is led out as the lead-out portion 34a from the end of the winding portion 32, and to cover the lead-out portion 34b and the portion 40b where the coated conductor 30 is led out as the lead-out portion 34b from the end of the winding portion 32. This makes it easier for air to escape near both the portions 40a and 40b where the coated conductor 30 is led out from the end of the winding portion 32, and reduces the number of voids generated inside the first exterior portion 52. Even in this case, the second resin material only covers the portion of the circumferential portion 32 that is not covered by the first exterior portion 52, and there is no need to provide any portion of the circumferential portion 32 to which the second resin material is not applied, so there is no problem with applying the second resin material multiple times.

[0072] In the above-mentioned embodiments and their modifications, the surface 20 (mounting surface) on which the external electrodes 60a and 60b of the flange portion 14 are provided is perpendicular to the axial direction (Z-axis direction) of the shaft portion 12, but the present invention is not limited to this. FIG. 13 shows a coil component showing an example in which the mounting surface is parallel to the axial direction of the shaft portion 12. As shown in FIG. 13, the external electrode 60a is provided on the flange portion 14, the external electrode 60b is provided on the flange portion 16, and the mounting surface 26 is parallel to the axial direction of the shaft portion 12. The length of the core 11b in the axial direction of the shaft portion 12 may be longer or shorter than the length in the direction perpendicular to the axial direction. In addition, when the length of the coil component is L, the depth is W, and the height is H, the relationship L>W≧H generally holds. The axial direction of the shaft portion 12 may coincide with the length direction of the coil component or may coincide with the width direction. When the axial direction of the shaft portion 12 coincides with the longitudinal direction of the coil component, the number of turns of the winding portion 32 can be increased, and a large inductance can be obtained.

[0073] In the above-described embodiments and their modified examples, a case has been shown in which the first exterior portion 52 is formed by applying a first resin material to the first portion 36 of the surrounding portion 32 and curing the material, and after the first exterior portion 52 is formed, the second resin material is applied to the second portion 38 of the surrounding portion 32 and cured to form the second exterior portion 54. However, the present invention is not limited to this case, and the first resin material may be applied to the first portion 36 of the surrounding portion 32 to form a first resin portion that will become the first exterior portion 52, and the second resin material may be applied to the second portion 38 of the surrounding portion 32 to form a second resin portion that will become the second exterior portion 54, and after applying the first resin material and the second resin material, the first resin material and the second resin material may be cured simultaneously to simultaneously form the first exterior portion 52 from the first resin portion and the second exterior portion 54 from the second resin portion. This can reduce the number of manufacturing steps.

[0074] In the above-described embodiments and their modified examples, the first resin material may be degassed under reduced pressure or degassed under pressure after the first resin material is applied. Similarly, the second resin material may be degassed under reduced pressure or degassed under pressure after the second resin material is applied. This can further reduce voids generated inside the exterior part 50.

[0075] In the above-described embodiments and their modifications, the first exterior portion 52 and the second exterior portion 54 may be formed of a resin material that does not contain a magnetic material, or may be formed of a resin material that contains a nonmagnetic material such as silica particles and a resin. In the above-described embodiments and their modifications, a nonmagnetic portion that does not have magnetic properties may be provided between the winding portion 32 and the first exterior portion 52 and / or between the winding portion 32 and the second exterior portion 54.

[0076] In the above embodiments and their modified examples, the exterior portion 50 is formed in two stages, the first exterior portion 52 and the second exterior portion 54, but it may be formed in three or more stages.

[0077] Although the embodiment of the present invention has been described in detail above, the present invention is not limited to such specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0078] 10, 10a, 11, 11a, 11b Core 12 Shaft 14, 16 Flange 18 Contact part 20 sides 22 Depression 24 Metal Film 26 Mounting surface 30 Insulated conductor 32 Orbital Division 34a, 34b Drawer section 36 Part 1 38 Part 2 40a, 40b Pull-out part 50 Exterior part 52 Part 1 Exterior 54 Part 2 Exterior 60a, 60b External electrodes

Claims

1. a step of winding a coated conductor around a shaft portion of a core having a shaft portion and a flange portion provided at one end of the shaft portion to form a winding portion; forming an extraction portion by extracting the coated conductor from a pair of ends of the winding portion; forming an external electrode on the flange portion to which the lead portion is electrically connected; the step of applying a first resin material containing a magnetic material and a resin to a portion of the circumferential portion to cover only the portion of the circumferential portion with the first resin material which becomes a first exterior portion; the step of hardening the first resin material which has covered only the portion of the circumferential portion; and the step of applying a second resin material containing a magnetic material and a resin to a portion of the circumferential portion different from the portion of the circumferential portion after hardening the first resin material to cover the different portion of the circumferential portion with the second resin material which becomes a second exterior portion, and forming an exterior portion which covers the entire circumferential portion, A method for manufacturing a coil component, wherein the first resin material is formed on the flange portion to cover the pull-out portion, a portion of the pull-out portion where the pull-out portion is pulled out from the winding portion, and only the portion of the winding portion.

2. A method for manufacturing a coil component as described in claim 1, wherein the magnetic material in the first resin material is different from the magnetic material in the second resin material, and / or the resin in the first resin material is different from the resin in the second resin material.

3. The method for manufacturing a coil component according to claim 1 , wherein the second exterior portion is formed so as to cover the first exterior portion.

4. forming the first exterior portion by hardening the first resin material; The method for manufacturing a coil component according to claim 1 , further comprising forming the first exterior portion and then curing the second resin material to form the second exterior portion.

5. 5. The method for manufacturing a coil component according to claim 1, wherein the first exterior portion is formed so as to cover an entire circumference of the shaft portion when viewed in the axial direction of the shaft portion, and is formed so that an area of ​​the first exterior portion in a cross section passing through a center of the shaft portion and parallel to the axial direction of the shaft portion is smaller than an area of ​​the second exterior portion in a cross section parallel to the axial direction of the shaft portion.

6. 5. The method for manufacturing a coil component according to claim 1, wherein the first exterior portion is formed so as to cover an entire circumference of the shaft portion when viewed in the axial direction of the shaft portion, and is formed so that an area of ​​the first exterior portion in a cross section passing through a center of the shaft portion and parallel to the axial direction of the shaft portion is larger than an area of ​​the second exterior portion in a cross section parallel to the axial direction of the shaft portion.

7. 5. The method for manufacturing a coil component according to claim 1, wherein the first exterior portion is formed so as to cover a part of the shaft portion except for a part of the shaft portion at a contact portion that is an inner surface of the flange portion on the shaft portion side and that contacts the shaft portion, and is formed so that an area of ​​the first exterior portion in a cross section passing through the winding portion and perpendicular to the axial direction of the shaft portion is smaller than an area of ​​the second exterior portion in a cross section perpendicular to the axial direction of the shaft portion.

8. 5. The method for manufacturing a coil component according to claim 1, wherein the first exterior portion is formed so as to cover a part of the shaft portion except for a part of the shaft portion at a contact portion that is an inner surface of the flange portion on the shaft portion side and that contacts the shaft portion, and is formed so that an area of ​​the first exterior portion in a cross section passing through the winding portion and perpendicular to the axial direction of the shaft portion is larger than an area of ​​the second exterior portion in a cross section perpendicular to the axial direction of the shaft portion.

9. The method for manufacturing a coil component according to claim 1 , wherein the core has a length in an axial direction of the shaft portion longer than a length in a direction perpendicular to the axial direction.

10. The method for manufacturing a coil component according to claim 1 , wherein a length of the core in an axial direction of the shaft portion is shorter than a length of the core in a direction perpendicular to the axial direction.

11. a core having a shaft portion and a flange portion provided at one end of the shaft portion; a winding portion having a coated conductor wound around the shaft portion; a pair of ends of the winding portion, from which the coated conductor wire is drawn; an external electrode provided on the flange and electrically connected to the lead portion; a first exterior part that is provided to cover only a portion of the winding part and is made of a first resin material containing a magnetic material and a resin, and a second exterior part that is provided to cover a portion other than the portion of the winding part and is made of a second resin material containing a magnetic material and a resin, at least one of the magnetic material and the resin of the first resin material being different from the portion of the winding part, and an exterior part that covers the entire winding part, The first exterior portion is provided on the flange portion to cover the pull-out portion, a portion of the pull-out portion pulled out from the winding portion, and only the portion of the winding portion.

Images