Coil component, wire bonding method, and coil component manufacturing method

Abstract

The invention relates to a coil component, a wire bonding method, and a coil component manufacturing method. The coil component includes a core, a wire, and an external electrode. The core has a winding core portion and a pair of flange portions. A specified axis orthogonal to the central axis is set as a first axis, one direction along the first axis is set as a first positive direction, and a direction opposite to the first positive direction is set as a first negative direction. The external electrode covers a surface facing the first positive direction among the outer surfaces of the flange portion. The wire has a linear portion wound around the winding core portion, and a joining portion located at an end portion of the wire and connected to the external electrode. In a cross section orthogonal to the central axis and including the bonding portion, an end portion on the first negative direction side of the bonding portion is located on the first negative direction side with respect to an end portion on the first positive direction side of the external electrode. The dimension of the joining portion in the direction along the first axis from the end portion on the first negative direction side to the end portion on the first positive direction side is larger than the wire diameter of the linear portion.

Description

Technical Field

[0001] The present invention relates to a coil component, a method for joining wire materials, and a method for manufacturing a coil component. Background Art

[0002] The coil component described in patent document 1 has a core body. The core body has a winding core portion and two flange portions. The winding core portion is in the shape of a quadrangular prism. The two flange portions are connected to the two ends of the winding core portion. Each flange portion extends outward relative to the outer surface of the winding core portion in a direction orthogonal to the central axis of the winding core portion. In addition, the coil component has a first external electrode and a second external electrode. The first external electrode is located on the upper surface of one flange portion. The second external electrode is located on the upper surface of the other flange portion. In addition, the coil component has a wire. The wire is a coated conductor. The wire is wound on the winding core portion. The first end of the wire is hot-pressed to the first external electrode. In addition, the second end of the wire is hot-pressed to the second external electrode. The hot-pressing bonding is performed by crimping a heating plate to the wire.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2005-294307 Summary of the invention

[0004] In the coil component described in Patent Document 1, when the end of the wire is joined to the external electrode, heat and pressure are applied to the end of the wire, so that the end of the wire is compressed and thinned. External force is easily concentrated on the thinned portion of the wire, so the wire is easily broken.

[0005] In order to solve the above-mentioned problems, the present invention provides a coil component, comprising: a core body having a columnar winding core portion and a pair of flange portions connected to the ends of the winding core portion along the direction of the central axis; a wire rod wound on the winding core portion; and an external electrode covering the outer surface of the flange portion, wherein when a specified axis orthogonal to the central axis is set as a first axis, one of the directions along the first axis is set as a positive direction, and the direction opposite to the positive direction is set as a negative direction, the flange portion extends toward the positive direction side relative to the outer surface of the winding core portion, and the external electrode covers the surface of the outer surface of the flange portion facing the positive direction, the wire rod having a linear portion wound on the winding core portion, and a joining portion located at the end of the wire rod and connected to the external electrode, in a cross section orthogonal to the central axis and including the joining portion, the end of the joining portion on the negative direction side is located on the negative direction side relative to the end of the external electrode on the positive direction side, and the dimension of the joining portion from the end on the negative direction side to the end on the positive direction side in the direction along the first axis is larger than the wire diameter of the linear portion.

[0006] In addition, in order to solve the above-mentioned problems, the present invention provides a method for joining wires, comprising: a ball portion forming step, in which the wire is melted to form a ball portion having a diameter larger than the wire diameter of the linear portion before melting at the end of the wire; and a joining step, in which the ball portion is irradiated with a laser while the ball portion is in contact with an external electrode covering the outer surface of a core body, thereby forming a joining portion connected to the external electrode at the end of the wire.

[0007] In addition, in order to solve the above-mentioned problems, a method for manufacturing a coil component is provided, comprising: a preparation step of preparing a core body, the core body having a columnar winding core portion and a pair of flange portions connected to the ends of the winding core portion along the direction of the central axis, and forming an external electrode covering the outer surface of the flange portion; a winding step of winding a wire on the winding core portion; a ball portion forming step of melting the wire to form a ball portion at the end of the wire having a diameter larger than the wire diameter of the linear portion before melting; and a joining step of irradiating the ball portion with a laser while making the ball portion contact with the external electrode, thereby forming a joining portion connected to the external electrode at the end of the wire.

[0008] In the above structure, the thickness of the joint portion in the wire is greater than the thickness of the linear portion. Therefore, even if a slight external force acts on the joint portion, the wire is not easily broken at the joint portion and at the boundary between the joint portion and the linear portion.

[0009] The wire material is prevented from being broken at the joining portion and at the boundary portion between the joining portion and the linear portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a three-dimensional diagram of the coil component.

[0011] Figure 2 This is an enlarged view of the vicinity of the second joining portion when viewed in the first negative direction.

[0012] Figure 3 It is along Figure 2 Cross-sectional view along line 3-3.

[0013] Figure 4 This is a diagram for explaining a method for manufacturing a coil component.

[0014] Figure 5 This is a diagram for explaining a method for manufacturing a coil component.

[0015] Figure 6 This is a diagram for explaining a method for manufacturing a coil component.

[0016] Figure 7 This is a diagram for explaining a method for manufacturing a coil component.

[0017] Figure 8 This is a diagram for explaining a method for manufacturing a coil component.

[0018] Fig. 9 This is a diagram for explaining a method for manufacturing a coil component.

[0019] Fig.10 This is a diagram for explaining a method for manufacturing a coil component.

[0020] Fig.11 This is a diagram for explaining a method for manufacturing a coil component.

[0021] Fig.12 This is a diagram for explaining a method for manufacturing a coil component.

[0022] Fig.13 This is a diagram for explaining a method for manufacturing a coil component.

[0023] Fig.14 It is a cross-sectional view of a coil component according to a modification example.

[0024] Description of Reference Numerals

[0025] A1…first dimension; A2…second dimension; BP…ball part; C…center axis; CP…transparent component; P1…dimension; X…first axis; X1…first positive direction; X2…first negative direction; 10…coil component; 10C…core body; 11…winding core part; 20…flange part; 40…external electrode; 50…wire material; 50A…conductor; 50B…insulating coating; 51…joining part; 52…linear part; 53…temporary fixing part; 54…buried part. DETAILED DESCRIPTION

[0026] Hereinafter, one embodiment of the coil component will be described with reference to the accompanying drawings. In addition, the accompanying drawings may enlarge the components for easy understanding. The dimensional ratios of the components may be different from the actual ones or from those in other drawings.

[0027] <About the overall structure>

[0028] like Figure 1 As shown, the coil component 10 includes a core body 10C and a top plate 12 .

[0029] The core 10C includes a columnar winding core 11, a first flange 21, and a second flange 22. In the following, when it is not necessary to distinguish between the first flange 21 and the second flange 22, they may be collectively referred to as the flange 20.

[0030] The core 11 is in the shape of a quadrangular prism. The cross section of the core 11 perpendicular to the central axis C is in the shape of a rectangle. In addition, the "rectangular shape" mentioned here only needs to have four sides and be a rectangular shape as a whole, and also includes a shape obtained by chamfering the corners of the rectangle. The material of the core 11 is a non-conductive material. Specifically, the material of the core 11 is, for example, Ni-Zn ferrite, alumina, synthetic resin, and a mixture thereof.

[0031] Here, a designated axis orthogonal to the central axis C of the winding core 11 is set as the first axis X. In the present embodiment, when viewed in the direction along the central axis C, the first axis X is parallel to two of the four sides of the winding core 11. In addition, an axis orthogonal to both the first axis X and the central axis C is set as the second axis Y. In the present embodiment, when viewed in the direction along the central axis C, the second axis Y is parallel to the remaining two of the four sides of the winding core 11. In addition, an axis parallel to the central axis C is set as the third axis Z. Moreover, one of the directions along the first axis X is set as the first positive direction X1, and the direction opposite to the first positive direction X1 is set as the first negative direction X2. Similarly, one of the directions along the second axis Y is set as the second positive direction Y1, and the direction opposite to the second positive direction Y1 is set as the second negative direction Y2. In addition, one of the directions along the third axis Z is set as the third positive direction Z1, and the direction opposite to the third positive direction Z1 is set as the third negative direction Z2.

[0032] like Figure 1 As shown, the first flange portion 21 is connected to the end portion of the third positive direction Z1 of the core portion 11, that is, the first end. The first flange portion 21 is a flat, approximately square plate. The thickness direction of the first flange portion 21 is along the direction of the third axis Z. When viewed in the direction along the third axis Z, the sides of the first flange portion 21 are parallel to the sides of the core portion 11. In addition, the first flange portion 21 extends outward relative to the outer surface of the core portion 11 in the direction along the first axis X and in the direction along the second axis Y. That is, the first flange portion 21 also extends to the first positive direction X1 side relative to the outer surface of the core portion 11.

[0033] The second flange portion 22 is connected to the end portion on the third negative direction Z2 side of the winding core portion 11, that is, the second end. The second flange portion 22 is symmetrical with the first flange portion 21. That is, the second flange portion 22 is substantially square plate-shaped. The second flange portion 22 extends outward relative to the outer surface of the winding core portion 11 in the direction along the first axis X and the direction along the second axis Y. That is, the second flange portion 22 also extends to the first positive direction X1 side relative to the outer surface of the winding core portion 11.

[0034] The material of the first flange portion 21 and the second flange portion 22 is the same material as that of the winding core portion 11. In addition, the first flange portion 21 and the second flange portion 22 are integrally molded with the winding core portion 11.

[0035] The top plate 12 is in the shape of a flat rectangular plate. The thickness direction of the top plate 12 is along the direction of the first axis X. The long side of the top plate 12 is parallel to the third axis Z. The short side of the top plate 12 is parallel to the second axis Y. The top plate 12 is located on the first negative direction X2 side relative to the core 10C. The top plate 12 is connected to both the surface of the first flange portion 21 facing the first negative direction X2 side and the surface of the second flange portion 22 facing the first negative direction X2 side. That is, the top plate 12 is mounted between the first flange portion 21 and the second flange portion 22. The material of the top plate 12 is the same material as that of the winding core portion 11.

[0036] The coil component 10 includes a first external electrode 41 and a second external electrode 42. The first external electrode 41 covers the entire area of ​​the surface of the outer surface of the first flange portion 21 that faces the first positive direction X1. The second external electrode 42 covers the entire area of ​​the surface of the outer surface of the second flange portion 22 that faces the first positive direction X1. In addition, hereinafter, when there is no need to distinguish between the first external electrode 41 and the second external electrode 42, they are sometimes collectively referred to as the external electrode 40.

[0037] like Figure 3 As shown, each external electrode 40 has a base layer L0, a first layer L1, a second layer L2, and a third layer L3. The base layer L0 is located on the side closest to the first negative direction X2 among the layers of the external electrode 40. That is, the base layer L0 directly covers the surface of the outer surface of the flange portion 20 facing the first positive direction X1. The base layer L0 contains Ag. The first layer L1 covers the surface of the base layer L0 facing the first positive direction X1. The first layer L1 contains Ni. The second layer L2 covers the surface of the first layer L1 on the first positive direction X1 side. The second layer L2 contains Cu.

[0038] The third layer L3 covers the surface of the second layer L2 on the first positive direction X1 side. That is, the third layer L3 is the outermost layer on the outer side of the external electrode 40. Therefore, when the base layer L0, the first layer L1, and the second layer L2 are used as inner layers, the third layer L3 is an outer layer located on the opposite side of the outer surface of the flange portion 20 relative to the inner layer. The third layer L3 contains Sn. The first layer L1, the second layer L2, and the third layer L3 are plating layers for the base layer L0. In addition, Figure 1 , it is illustrated that these layers in each external electrode 40 have no boundaries.

[0039] <About Wire>

[0040] like Figure 1 As shown, the coil component 10 includes a wire 50 wound around a winding core 11. Figure 2As shown, the wire 50 has a conductor 50A and an insulating coating 50B. The conductor 50A is linear. The conductor 50A is made of Cu, for example. In the present embodiment, the diameter of the conductor 50A is about 10 μm. The insulating coating 50B covers the outer peripheral surface of the conductor 50A. The insulating coating 50B is made of a synthetic resin such as polyurethane and polyamide-imide. In the present embodiment, the thickness of the insulating coating 50B is about 2.5 μm. The wire 50 is roughly circular in a cross section perpendicular to the direction in which the wire 50 extends.

[0041] like Figure 1 As shown, the wire 50 has a first joint 51A, a second joint 51B, and a linear portion 52. In addition, in the following, when it is not necessary to distinguish between the first joint 51A and the second joint 51B, they are sometimes collectively referred to as the joint 51. The first joint 51A is located at the end of the wire 50 on the third positive direction Z1 side. The first joint 51A is connected to the first external electrode 41. The second joint 51B is located at the end of the wire 50 on the third negative direction Z2 side. The second joint 51B is connected to the second external electrode 42. The joint 51 does not have an insulating film 50B, but only has a conductor 50A. At least a part of the interface between the joint 51 and the third layer L3 is a Cu-Sn alloy. In addition, the above-mentioned "only has a conductor 50A" allows the presence of a trace of a tiny insulating film 50B. Specifically, when the joint 51 is observed toward the first negative direction X2, as long as the proportion of the conductor 50A is 97% or more, it is "only has a conductor 50A".

[0042] The linear portion 52 is a portion of the wire 50 other than the joint 51. That is, the linear portion 52 is wound around the winding core 11. The linear portion 52 includes an insulating coating 50B and a conductor 50A. That is, based on the dimensional relationship between the conductor 50A and the insulating coating 50B, the wire diameter of the linear portion 52 is about 15 μm.

[0043] <About temporary fixing of wires>

[0044] like Figure 2 As shown, the linear portion 52 of the wire 50 has a temporary fixing portion 53. The temporary fixing portion 53 is located on the winding core 11 side relative to the second joining portion 51B. In addition, the temporary fixing portion 53 is adjacent to the second joining portion 51B in the extending direction of the wire 50.

[0045] The temporary fixing portion 53 is bonded to the third layer L3 of the second external electrode 42. Specifically, the end of the temporary fixing portion 53 on the first negative direction X2 side is located on the first negative direction X2 side relative to the end of the third layer L3 on the first positive direction X1 side. That is, the temporary fixing portion 53 is at least partially buried in the second external electrode 42 in a state with the insulating coating 50B.

[0046] <Regarding the dimensional relationship between the external electrode and the wire>

[0047] The dimensional relationship between each external electrode 40 and each bonding portion 51 will be described. Hereinafter, the dimensional relationship between the second external electrode 42 and the second bonding portion 51B will be described as a representative, but the dimensional relationship between the first external electrode 41 and the first bonding portion 51A is also the same.

[0048] like Figure 3 As shown, it is assumed that a cross-sectional observation is performed in a specified cross section that is orthogonal to the central axis C and includes the second bonding portion 51B. The second bonding portion 51B is buried in the second external electrode 42. That is, the end of the second bonding portion 51B on the first negative direction X2 side is located on the first negative direction X2 side relative to the end of the second external electrode 42 on the first positive direction X1 side. In particular, the entirety of the second bonding portion 51B is buried in the second external electrode 42. Specifically, in the direction along the first axis X, the end of the second bonding portion 51B on the first positive direction X1 side coincides with the end of the second external electrode 42 on the first positive direction X1 side.

[0049] The end surface of the second bonding portion 51B on the first positive direction X1 side is a flat surface parallel to the second axis Y and the central axis C. The end surface of the second bonding portion 51B on the first positive direction X1 side is substantially coplanar with the end of the second external electrode 42 on the first positive direction X1 side.

[0050] In addition, for the end portion of the second external electrode 42 on the first positive direction X1 side, the contour of the second external electrode 42 is obtained by image processing using an electron microscope in a specified cross section. Then, the portion of the contour that is closest to the first positive direction X1 is taken as the end portion of the second external electrode 42 on the first positive direction X1 side.

[0051] In the above-mentioned specific cross section, the end of the second bonding portion 51B on the first negative direction X2 side is located on the first positive direction X1 side relative to the end of the second layer L2 on the first positive direction X1 side. That is, the second bonding portion 51B is located in the third layer L3 and does not reach the second layer L2.

[0052] In a given cross section, a dimension P1 of the second bonding portion 51B from the end portion on the first negative direction X2 side to the end portion on the first positive direction X1 side along the first axis X is approximately 21 μm. That is, a dimension P1 of the second bonding portion 51B from the end portion on the first negative direction X2 side to the end portion on the first positive direction X1 side along the first axis X is larger than the wire diameter of the linear portion 52.

[0053] In the specified cross section, the portion of the second bonding portion 51B located on the first negative direction side relative to the end portion of the second external electrode 42 in the first positive direction X1 is defined as the buried portion 54. In the present embodiment, the portion of the second bonding portion 51B in the specified cross section other than the end surface on the first positive direction X1 side corresponds to the buried portion 54. In the specified cross section, the maximum dimension of the buried portion 54 along the direction of the second axis Y is defined as the first dimension A1. The first dimension A1 is approximately 63 μm. Therefore, the first dimension A1 is larger than the wire diameter of the linear portion 52.

[0054] Furthermore, a dimension of the buried portion 54 on the first positive direction X1 side relative to the first dimension A1 in the direction along the second axis Y is referred to as a second dimension A2. The second dimension A2 is smaller than the first dimension A1.

[0055] <Regarding the Manufacturing Method of Coil Component>

[0056] like Figure 4 As shown, the manufacturing method of the coil component 10 includes a preparation step S11, a first end ball forming step S12, a first end pressing step S13, a first end joining step S14, a first end removing step S15, and a winding step S16. In addition, the manufacturing method of the coil component 10 includes a second end temporary pressing step S17, a second end temporary fixing step S18, a wire cutting step S19, a second end ball forming step S20, a second end pressing step S21, a second end joining step S22, and a second end removing step S23.

[0057] In addition, among the above-mentioned steps, the first end ball portion forming step S12 to the first end removing step S15 and the second end temporary pressing step S17 to the second end removing step S23 are steps related to the method of joining the wires 50 .

[0058] First, the preparation step S11 is performed. In the preparation step S11, a core 10C having an external electrode 40 is prepared. The core 10C is formed by mixing a synthetic resin binder with Ni-Zn ferrite powder and firing a molded body formed by press molding. Thus, a core 10C having the above-mentioned winding core portion 11, the first flange portion 21, and the second flange portion 22 is formed. Then, a conductive paste containing Ag is applied to the surface of the first flange portion 21 of the core 10C facing the first positive direction X1. By evaporating the paste, a base layer L0 is formed. In addition, electroplating is performed on the base layer L0 to form a first layer L1, a second layer L2, and a third layer L3. Thus, a first external electrode 41 is formed. Similarly, a second external electrode 42 is formed on the surface of the second flange portion 22 facing the first positive direction X1. Then, the core 10C having the external electrode 40 formed is clamped from the outside of each flange portion 20 by a pair of rotating chucks RC. Thus, the core 10C is supported so as to be rotatable about the central axis C as the rotation center.

[0059] Next, the first end ball portion forming step S12 is performed. In the stage before the first end ball portion forming step S12, the first end of the wire 50 has the conductor 50A and the insulating film 50B. Figure 5 As shown, in the first end ball portion forming step S12, the first end of the wire 50 is irradiated with laser. At the irradiated portion, the insulating film 50B melts, thereby exposing the conductor 50A. Figure 6 As shown, at the irradiated portion, the conductor 50A melts to form a substantially spherical ball portion BP having a diameter larger than the wire diameter of the linear portion 52. In this state, a portion of the insulating film 50B may remain on the surface.

[0060] Next, the first end pressing step S13 is performed. Figure 6 As shown, in the first end pressing step S13, the ball BP is pressed against the first external electrode 41 using a transparent member CP made of a material that transmits laser light. Specifically, the ball BP is sandwiched between the transparent member CP and the first external electrode 41. The transparent member CP only needs to be made of a material that transmits laser light, such as borosilicate glass, sapphire glass, etc. In addition, by pressing the transparent member CP against the ball BP, the insulating coating 50B remaining on the ball BP is welded to the transparent member CP.

[0061] Next, the first end bonding step S14 is performed. Figure 7As shown, in the first end bonding process S14, the ball part BP is irradiated with laser from one side of the transparent member CP while the ball part BP is sandwiched between the transparent member CP and the first external electrode 41. Therefore, in this state, the ball part BP is in contact with the first external electrode 41. Thus, a first bonding portion 51A connected to the first external electrode 41 is formed at the first end of the wire 50. In addition, due to the pressing force of the transparent member CP, the ball part BP is buried in the melted and softened third layer L3, thereby forming a buried portion 54. In addition, due to the pressing force of the transparent member CP, the end face of the first positive direction X1 of the first bonding portion 51A is formed as a flat surface.

[0062] Next, the first end removal step S15 is performed. In the first end removal step S15, the transparent member CP is removed from the wire 50. In the first end removal step S15, the insulating film 50B remaining on the ball portion BP is removed from the wire 50 together with the transparent member CP.

[0063] Next, the winding step S16 is performed. In the winding step S16 , the core body 10C is rotated together with the rotary chuck RC about the central axis C as the rotation center, and the wire 50 is wound around the winding core 11 .

[0064] Next, the second end temporary pressing step S17 is performed. Figure 8 As shown, in the second end temporary pressing step S17, the wire 50 is drawn out from the portion wound on the winding core 11 so that the wire 50 is located on the second external electrode 42. Then, the wire 50 is sandwiched between the transparent member CP and the second external electrode 42. Thus, the position of the wire 50 is temporarily determined.

[0065] Next, the second end temporary fixing step S18 is performed. Fig. 9 As shown, in the second end temporary fixing process S18, laser is irradiated from one side of the transparent member CP to the temporary fixing portion in the second external electrode 42. As a result, the temporary fixing portion 53 on the side of the winding core portion 11 relative to the predetermined portion where the second joining portion 51B is formed in the wire 50 is joined to the temporary fixing portion. At this time, the third layer L3 is melted at the temporary fixing portion irradiated with laser. Then, the temporary fixing portion 53 of the wire 50 is pressed against the melted temporary fixing portion, so that the temporary fixing portion 53 is buried and joined to the temporary fixing portion. As a result, the temporary fixing portion 53 is formed in the linear portion 52. In addition, in the second end temporary fixing process S18, the laser is not irradiated directly to the wire 50, but to the third layer L3 of the second external electrode 42. Specifically, the laser is irradiated along the extending direction of the wire 50. As a result, the insulating coating 50B remains in the temporary fixing portion 53 without being melted.

[0066] Next, the wire cutting step S19 is performed. Fig.10As shown, in the wire cutting step S19, first, the transparent member CP is removed from the wire 50. Next, the laser is irradiated to the portion of the wire 50 on the opposite side of the temporary fixing portion 53 and the portion wound on the winding core portion 11 in the extending direction of the wire 50. As a result, the wire 50 is cut to form the second end of the wire 50.

[0067] Next, the second end ball portion forming step S20 is performed. Fig.11 As shown, in the second end ball portion forming step S20, the second end of the wire 50 is irradiated with laser. The insulating film 50B melts at the irradiated portion, thereby exposing the conductor 50A. Then, at the irradiated portion, the conductor 50A melts to form a substantially spherical ball portion BP having a diameter larger than the wire diameter of the linear portion 52. In addition, in this state, a part of the insulating film 50B may remain on the surface.

[0068] Next, the second end pressing step S21 is performed. Fig.12 As shown, in the second end pressing step S21, the ball portion BP is pressed against the second external electrode 42 using the transparent member CP. Specifically, the ball portion BP is sandwiched between the transparent member CP and the second external electrode 42. By pressing the transparent member CP against the ball portion BP, the insulating film 50B remaining on the ball portion BP is welded to the transparent member CP.

[0069] Next, the second end bonding step S22 is performed. Fig.13 As shown, in the second end bonding process S22, the ball part BP is irradiated with laser from one side of the transparent member CP while the ball part BP is sandwiched between the transparent member CP and the second external electrode 42. Therefore, in this state, the ball part BP is in contact with the second external electrode 42. Thus, a second bonding part 51B connected to the second external electrode 42 is formed at the second end of the wire 50. In addition, due to the pressing force of the transparent member CP, the ball part BP is buried in the melted and softened third layer L3, thereby forming a buried part 54. In addition, due to the pressing force of the transparent member CP, the end face of the first positive direction X1 of the second bonding part 51B is formed into a flat surface.

[0070] Next, the second end removal step S23 is performed. In the second end removal step S23, the transparent member CP is removed from the wire 50. That is, in the second end removal step S23, the insulating film 50B remaining on the ball portion BP is removed from the wire 50 together with the transparent member CP.

[0071] <Effects of the present embodiment>

[0072] (1) In the above embodiment, the thickness of each joint portion 51 in the wire 50 is greater than the thickness of the linear portion 52. Therefore, even if a slight external force acts on each joint portion 51, the wire 50 is unlikely to break at the boundary between each joint portion 51 and the linear portion 52.

[0073] (2) In the above embodiment, the first dimension A1 is larger than the wire diameter of the linear portion 52. This can increase the contact area between each joining portion 51 and the external electrode 40. Therefore, it is possible to suppress the wire 50 from falling off from the external electrode 40.

[0074] (3) In the above embodiment, the second dimension A2 is smaller than the first dimension A1. Therefore, in a given cross section, the buried portion 54 includes a portion formed in a shape in which the dimension along the direction of the second axis Y decreases as it approaches the first positive direction X1. That is, a portion of the joint 51 is covered by the external electrode 40 from the outside. Therefore, the joint 51 is not easily detached from the external electrode 40.

[0075] (4) In the above embodiment, the wire 50 includes the conductor 50A and the insulating film 50B. In addition, each joint 51 includes only the conductor 50A. With this structure, the insulating film 50B is unlikely to hinder the electrical connection between the joint 51 and the external electrode 40.

[0076] (5) In the above embodiment, the temporary fixing portion 53 includes the conductor 50A and the insulating film 50B. According to this structure, the conductor 50A in the temporary fixing portion 53 does not directly contact the external electrode 40. Therefore, it is possible to prevent the components of the conductor 50A from eluting into the external electrode 40 and the conductor 50A from becoming thinner.

[0077] (6) In the above embodiment, the end of the bonding portion 51 on the first negative direction X2 side is located on the first positive direction X1 side relative to the end of the second layer L2 on the first positive direction X1 side. That is, the bonding portion 51 does not reach the interface between the third layer L3 and the second layer L2. Assuming that, for example, in the second end pressing step S21, the bonding portion 51 reaches the interface between the third layer L3 and the second layer L2, the bonding portion 51 may receive a reaction force from the interface. As a result, external force may be excessively applied to the bonding portion 51. According to the above structure, such external force applied to the bonding portion 51 can be suppressed.

[0078] (7) In the above embodiment, the third layer L3 contains Sn. Sn is a relatively soft metal among metals. Therefore, when the bonding portion 51 is connected to the external electrode 40, the external force on the bonding portion 51 can be suppressed.

[0079] (8) In the above embodiment, the linear portion 52 has the temporary fixing portion 53 joined to the third layer L3. In addition, the third layer L3 contains Sn. Therefore, the melting point of the third layer L3 is relatively low, and it is easy to melt it using a laser or the like. As a result, in the second end temporary fixing step S18, the temporary fixing portion 53 can be formed by pressing the linear portion 52 against the melted third layer L3. By forming the temporary fixing portion 53, the wire material 50 is less likely to be displaced when the second joining portion 51B is formed.

[0080] (9) In the above embodiment, the end surface of the joint portion 51 on the first positive direction X1 side is parallel to the second axis Y and the central axis C. With this configuration, the posture of the coil component 10 is stabilized when the coil component 10 is connected to the substrate using solder or the like.

[0081] (10) In the above embodiment, the method for joining the wire 50 includes the second end ball forming step S20 and the second end joining step S22. In addition, the method for joining the wire 50 includes the second end pressing step S21 after the second end ball forming step S20 and before the second end joining step S22. By performing the second end pressing step S21, the ball BP can be buried deeper in the second external electrode 42. In this regard, the first end pressing step S13 is also the same.

[0082] (11) In the above embodiment, the wire 50 has the conductor 50A and the insulating coating 50B at a stage before the second end ball forming step S20. Furthermore, the method for joining the wire 50 includes a second end removal step S23 of removing the transparent member CP from the wire 50 together with the insulating coating 50B remaining on the ball portion BP after the second end joining step S22. By performing the second end removal step S23, the conductor 50A is exposed on the end surface of the second joint portion 51B on the first positive direction X1 side. Therefore, compared with a structure in which the end surface of the second joint portion 51B on the first positive direction X1 side includes the insulating coating 50B, according to the above structure, when the second external electrode 42 is connected to the substrate using solder or the like, the wettability of the solder is improved. In this regard, the first end removal step S15 is also the same.

[0083] (12) In the above embodiment, in the first end pressing step S13 and the second end pressing step S21, the insulating film 50B is welded to only a part of the transparent member CP. By utilizing the portion to which the insulating film 50B is not welded, the same transparent member CP can be reused in the joining step of the wire 50. Therefore, the transparent member CP can be reused instead of being thrown away after being used once, thereby suppressing the increase in the cost required for the above process.

[0084] (13) In the above embodiment, the third layer L3 of the external electrode 40 contains Sn. In addition, the conductor 50A contains Cu. That is, each joint 51 contains Cu. Therefore, a Cu-Sn alloy can be generated at the boundary between the joint 51 and the external electrode 40. If the Cu-Sn alloy is generated at the boundary in this way, the electrical characteristics of the joint 51 are stabilized.

[0085] <Change Example>

[0086] The above-described embodiment and the following modified examples can be implemented in combination with each other within the scope of no technical contradiction.

[0087] The structure of the coil component 10 is not limited. For example, the coil component 10 may omit the top plate 12 .

[0088] The winding core 11 may not be in a quadrangular column shape. For example, the cross-sectional shape of the winding core 11 may be a circle, an ellipse, or a polygonal shape other than a quadrangle.

[0089] The wire diameter of the linear portion 52 of the wire 50 is not limited to the above-described embodiment. A dimension P1 of the joining portion 51 along the first axis X from the end in the first negative direction X2 to the end in the first positive direction X1 may be larger than the wire diameter of the linear portion 52 .

[0090] The layer structure of the external electrode 40 is not limited to the example of the above embodiment. The external electrode 40 only needs to have at least one conductive layer. In this case, the layer constitutes the outermost layer on the outer side. In addition, in the above embodiment, the material of each layer of the external electrode 40 is not limited to the example of the above embodiment.

[0091] The end of the bonding portion 51 on the first negative direction X2 side may also be located on the first negative direction X2 side relative to the end of the second layer L2 on the first positive direction X1 side. That is, the end of the bonding portion 51 on the first negative direction X2 side may also be located on the first negative direction X2 side relative to the end of the inner layer on the first positive direction X1 side.

[0092] The joint portion 51 may include an insulating coating 50B in addition to the conductor 50A. The joint portion 51 and the external electrode 40 may be electrically connected.

[0093] In a given cross section, the first dimension A1 may not be the dimension of the portion of the buried portion 54 that has the largest dimension along the second axis Y. In a given cross section, the dimension along the second axis Y at any portion of the buried portion 54 along the first axis X may be set as the first dimension A1. In addition, when the dimension along the second axis Y of the buried portion 54 on the first positive direction X1 side relative to the portion of the first dimension A1 is set as the second dimension A2, the effect of (3) can be obtained as long as the second dimension A2 is smaller than the first dimension A1.

[0094] The joint portion 51 need not be entirely buried in the external electrode 40 as long as at least a portion of it is buried in the external electrode 40. Fig.14 In the example shown, in a given cross section, the end of the bonding portion 51 on the first negative direction X2 side is located on the first negative direction X2 side relative to the end of the external electrode 40 on the first positive direction X1 side. On the other hand, in a given cross section, the end of the bonding portion 51 on the first positive direction X1 side is located on the first positive direction X1 side relative to the end of the external electrode 40 on the first positive direction X1 side. Fig.14 In the example shown, a dimension P1 of the joint portion 51 in the specified cross section from the end portion on the first positive direction X1 side to the end portion on the first negative direction X2 side along the first axis X is also larger than the wire diameter of the linear portion 52. Fig.14 In the example shown, the second dimension A2 is larger than the first dimension A1. Fig.14 In the example shown, in a given cross section, the maximum dimension of the buried portion 54 along the direction of the second axis Y is smaller than the line diameter of the linear portion 52 .

[0095] As long as the joining portion 51 is connected to the external electrode 40 , the linear portion 52 may not have the temporary fixing portion 53 . In this case, in the method of joining the wire material 50 , the second end temporary pressing step S17 and the second end temporary fixing step S18 may be omitted.

[0096] In the method for joining the wire 50, the first end pressing step S13, the first end removing step S15, the second end pressing step S21, and the second end removing step S23 can be omitted. That is, as long as the joint 51 is connected to the external electrode 40, the transparent member CP can be omitted in the method for joining the wire 50.

[0097] The method for manufacturing the coil component is not limited to the example of the above-described embodiment. For example, after the preparation step S11, the winding step S16 may be performed, and then the first end ball portion forming step S12 and the first end joining step S14 may be performed.

[0098] <Note>

[0099] The following describes technical ideas derived from the above-mentioned embodiments and modified examples.

[0100] [1] A coil component comprising: a core having a columnar winding core and a pair of flanges connected to ends of the winding core in a direction along a central axis; a wire wound around the winding core; and an external electrode covering an outer surface of the flange, wherein when a predetermined axis orthogonal to the central axis is defined as a first axis, one direction along the first axis is defined as a positive direction, and a direction opposite to the positive direction is defined as a negative direction, the flange extends toward the positive direction relative to an outer surface of the winding core, and the external electrode covers a surface of the outer surface of the flange facing the positive direction, the wire having a linear portion wound around the winding core, and a junction located at an end of the wire and connected to the external electrode, wherein, in a cross section orthogonal to the central axis and including the junction, an end of the junction on the negative direction side is located on the negative direction side relative to an end of the external electrode on the positive direction side, and a dimension of the junction from the end on the negative direction side to the end on the positive direction side in the direction along the first axis is larger than a wire diameter of the linear portion.

[0101] [2] According to the coil component described in [1], when an axis orthogonal to the above-mentioned central axis and the above-mentioned first axis is set as a second axis, and in the above-mentioned cross section, a portion of the above-mentioned joint portion that is located on the above-mentioned negative direction side at the end portion on the above-mentioned positive direction side relative to the above-mentioned external electrode is set as a buried portion, in the above-mentioned cross section, the maximum dimension of the above-mentioned buried portion along the direction of the above-mentioned second axis is larger than the wire diameter of the above-mentioned linear portion.

[0102] [3] According to the coil component described in [1] or [2], when an axis orthogonal to both the central axis and the first axis is set as the second axis, in the cross section, a portion of the joint portion located on the negative direction side at the end portion on the positive direction side relative to the external electrode is set as a buried portion, and in the cross section, a dimension of the buried portion along the second axis at any portion along the first axis is set as a first dimension, and a dimension of the buried portion along the second axis at a portion on the positive direction side relative to the first dimension is set as a second dimension, the second dimension is smaller than the first dimension.

[0103] [4] According to any one of [1] to [3], the wire material has a linear conductor and an insulating coating covering the outer peripheral surface of the conductor, the linear portion has the insulating coating and the conductor, and the joint portion has only the conductor.

[0104] [5] According to any one of [1] to [4], the external electrode comprises an inner layer and an outer layer located on the opposite side of the outer surface of the flange portion relative to the inner layer, and in the cross section, the end of the negative direction side of the joint is located on the positive direction side relative to the end of the positive direction side of the inner layer.

[0105] [6] The coil component according to any one of [1] to [5], wherein the external electrode has an outermost layer which is the outermost layer of the external electrode, and the outermost layer contains Sn.

[0106] [7] According to the coil component described in [6], the linear portion has a temporary fixing portion joined to the outermost layer.

[0107] [8] A method for joining wires, comprising: a ball forming step, in which the wire is melted to form a ball having a diameter larger than the diameter of the linear portion before melting at the end of the wire; and a joining step, in which the ball is irradiated with a laser while the ball is in contact with an external electrode covering the outer surface of a core body, thereby forming a joining portion connected to the external electrode at the end of the wire.

[0108] [9] According to the wire joining method described in [8], there is a pressing step after the above-mentioned ball portion forming step and before the above-mentioned joining step. In the pressing step, the ball portion is clamped by a transparent member made of a material that transmits the above-mentioned laser and the above-mentioned external electrode, and the above-mentioned ball portion is pressed against the above-mentioned external electrode. In the above-mentioned joining step, the above-mentioned laser is irradiated from one side of the above-mentioned transparent member while the above-mentioned ball portion is clamped by the above-mentioned transparent member and the above-mentioned external electrode.

[0109]

[10] According to the wire joining method described in [9], the wire has a linear conductor and an insulating coating covering the outer peripheral surface of the conductor in a stage before the above-mentioned ball portion forming step, and after the above-mentioned joining step, there is a removal step of removing the above-mentioned transparent member together with the above-mentioned insulating coating remaining on the above-mentioned ball portion from the above-mentioned wire.

[0110]

[11] A method for manufacturing a coil component, comprising: a preparation step of preparing a core body having a columnar winding core portion and a pair of flange portions connected to the ends of the winding core portion along a central axis, and forming an external electrode covering the outer surface of the flange portion; a winding step of winding a wire material around the winding core portion; a ball portion forming step of melting the wire material to form a ball portion having a diameter larger than the wire diameter of the linear portion before melting at the end of the wire material; and a joining step of irradiating the ball portion with a laser while the ball portion is in contact with the external electrode, thereby forming a joining portion connected to the external electrode at the end of the wire material.

[0111]

[12] According to the manufacturing method of the coil component described in

[11] , there is a pressing step after the above-mentioned ball portion forming step and before the above-mentioned joining step. In the pressing step, the ball portion is clamped by the above-mentioned transparent member made of a material that transmits the above-mentioned laser and the above-mentioned external electrode, and the above-mentioned ball portion is pressed against the above-mentioned external electrode. In the above-mentioned joining step, the above-mentioned laser is irradiated from one side of the above-mentioned transparent member while the above-mentioned ball portion is clamped by the above-mentioned transparent member and the above-mentioned external electrode.

[0112]

[13] According to the method for manufacturing a coil component described in

[12] , the wire material has a linear conductor and an insulating coating covering the outer peripheral surface of the conductor in a stage before the ball portion forming step, and after the joining step, there is a removal step of removing the transparent member together with the insulating coating remaining on the ball portion from the wire material.

[0113]

[14] According to any one of

[11] to

[13] , the external electrode has an outermost layer which is the outermost layer of the external electrode and contains Sn, and the temporary fixing step is included before the ball portion forming step. The temporary fixing step irradiates the laser to the temporary fixing portion of the external electrode, thereby joining the temporary fixing portion of the wire material on the side of the winding core portion relative to the predetermined portion for forming the joint portion to the temporary fixing portion.

Claims

1. A coil component, wherein: have: A core body having a columnar winding core portion and a pair of flange portions connected to the ends of the winding core portion in the direction along the central axis; A wire material is wound on the winding core; as well as an external electrode covering an outer surface of the flange portion, When a designated axis orthogonal to the central axis is defined as a first axis, one direction along the first axis is defined as a positive direction, and a direction opposite to the positive direction is defined as a negative direction, The flange portion extends toward the positive direction relative to the outer surface of the winding core portion. The external electrode covers the surface of the outer surface of the flange portion facing the positive direction, The wire material includes a linear portion wound around the winding core, and a junction portion located at an end of the wire material and connected to the external electrode. In a cross section that is orthogonal to the center axis and includes the joint, the end of the joint on the negative direction side is located on the negative direction side relative to the end of the external electrode on the positive direction side, and a dimension of the joint along the first axis from the end on the negative direction side to the end on the positive direction side is larger than the wire diameter of the linear portion.

2. The coil component according to claim 1, wherein An axis orthogonal to both the central axis and the first axis is defined as a second axis, In the cross section, when a portion of the bonding portion located on the negative direction side with respect to the end portion on the positive direction side of the external electrode is regarded as a buried portion, In the cross section, a maximum dimension of the buried portion along the second axis direction is larger than a line diameter of the linear portion.

3. The coil component according to claim 1 or 2, wherein: An axis orthogonal to both the central axis and the first axis is defined as a second axis, In the cross section, a portion of the bonding portion that is located on the negative direction side relative to the end portion on the positive direction side of the external electrode is defined as a buried portion, In the cross section, when a dimension along the second axis at any position of the buried portion along the first axis is set as a first dimension, and a dimension along the second axis at a position on the positive direction side relative to the first dimension is set as a second dimension, The second size is smaller than the first size.

4. The coil component according to any one of claims 1 to 3, wherein The wire material has a linear conductor and an insulating film covering an outer peripheral surface of the conductor. The linear portion includes the insulating coating and the conductor, The joining portion has only the conductor.

5. The coil component according to any one of claims 1 to 4, wherein The external electrode includes an inner layer and an outer layer located on the opposite side of the outer surface of the flange portion relative to the inner layer. In the cross section, an end portion of the joining portion on the negative direction side is located on the positive direction side with respect to an end portion of the inner layer on the positive direction side.

6. The coil component according to any one of claims 1 to 5, wherein: The external electrode includes an outermost layer which is the outermost layer of the external electrode. The outermost layer contains Sn.

7. The coil component according to claim 6, wherein The linear portion has a temporary fixing portion joined to the outermost layer.

8. A method for joining wires, wherein: have: a ball portion forming step of melting the wire material to form a ball portion at an end of the wire material having a larger diameter than the wire diameter of the linear portion before melting; and In the joining step, the ball portion is irradiated with laser light in a state where the ball portion is in contact with an external electrode covering the outer surface of the core body, thereby forming a joining portion connected to the external electrode at the end of the wire.

9. The wire bonding method according to claim 8, wherein: After the ball portion forming step and before the bonding step, A pressing step is provided, wherein the ball portion is pressed against the external electrode by sandwiching the ball portion between a transparent member made of a material through which the laser light is transmitted and the external electrode, In the bonding step, the laser beam is irradiated from one side of the transmissive member in a state where the ball portion is sandwiched between the transmissive member and the external electrode.

10. The wire bonding method according to claim 9, wherein: The wire material has a linear conductor and an insulating film covering the outer peripheral surface of the conductor at a stage before the ball portion forming step. After the bonding step, there is a removal step of removing the transparent member from the wire material together with the insulating coating remaining on the ball portion.

11. A method for manufacturing a coil component, wherein: have: A preparation step of preparing a core body having a columnar winding core portion and a pair of flange portions connected to ends of the winding core portion along a central axis, and having an external electrode formed to cover an outer surface of the flange portion; A winding step of winding the wire material on the winding core; a ball portion forming step of melting the wire material to form a ball portion at an end of the wire material having a larger diameter than the wire diameter of the linear portion before melting; as well as In the joining step, a joining portion connected to the external electrode is formed at an end of the wire by irradiating the ball portion with a laser beam while the ball portion is in contact with the external electrode.

12. The method for manufacturing a coil component according to claim 11, wherein: After the ball portion forming step and before the bonding step, A pressing step is provided, wherein the ball portion is pressed against the external electrode by sandwiching the ball portion between a transparent member made of a material through which the laser light is transmitted and the external electrode, In the bonding step, the laser beam is irradiated from one side of the transmissive member in a state where the ball portion is sandwiched between the transmissive member and the external electrode.

13. The method for manufacturing a coil component according to claim 12, wherein: The wire material has a linear conductor and an insulating film covering the outer peripheral surface of the conductor at a stage before the ball portion forming step. After the bonding step, there is a removal step of removing the transparent member from the wire material together with the insulating coating remaining on the ball portion.

14. The method for manufacturing a coil component according to any one of claims 11 to 13, wherein: The external electrode has an outermost layer which is the outermost layer of the external electrode and contains Sn, The temporary fixing step is included before the ball portion forming step, wherein the temporary fixing step irradiates the laser to the temporary fixing portion of the external electrode to join the temporary fixing portion of the wire material on the side of the winding core portion relative to the predetermined portion for forming the joining portion to the temporary fixing portion.

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