Coil components

Abstract

To prevent a wire from breaking at a joint portion and at a boundary between the joint portion and a linear portion.SOLUTION: A coil component includes a core, a wire, and external electrodes 40. The core has a winding core portion and a pair of flange portions. A specific axis perpendicular to a central axis is defined to be a first axis X, one of the directions along the first axis X is defined as a first positive direction X1, and an opposite direction to the first positive direction X1 is defined as a first negative direction X2. The external electrodes 40 each cover an outer surface of the flange portion facing the first positive direction X1. The wire includes: a linear portion wound around the winding core portion; and a joint portion 51 located at each end of the wire and connected to each of the external electrodes. In a cross section perpendicular to the central axis and including the joint portion 51, an end of the joint portion 51 on the first negative direction X2 side is located on the first negative direction X2 side with respect to an end of the external electrode 40 on the first positive direction X1 side. Moreover, a dimension P1 in a direction along the first axis X from the end of the joint portion 51 on the first negative direction X2 side to the end thereof on the first positive direction X1 side is larger than a wire diameter of the linear portion.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a coil part Product .

Background Art

[0002] The coil component described in Patent Document 1 includes a core. The core has a bobbin part and two flange parts. The bobbin part is quadrangular prism-shaped. The two flange parts are connected to both ends of the bobbin part. Each flange part protrudes outward with respect to the outer surface of the bobbin part in a direction orthogonal to the central axis of the bobbin part. Further, 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 part. The second external electrode is located on the upper surface of the other flange part. Further, the coil component includes a wire. The wire is a coated conductor. The wire is wound around the bobbin part. The first end of the wire is thermocompression-bonded to the first external electrode. Also, the second end of the wire is thermocompression-bonded to the second external electrode. The thermocompression bonding is performed by pressing a heater tip against the wire.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a coil component as described in Patent Document 1, when joining the end of the wire to the external electrode, heat and pressure are applied to the end of the wire, so the end of the wire is crushed and thinned. Since an external force easily concentrates on this thinned part of the wire, disconnection of the wire easily occurs.

Means for Solving the Problems

[0005] To solve the above problems, the present invention provides a core having a columnar winding core and a pair of flanges connected to the ends in the direction along the central axis of the winding core, a wire wound around the winding core, and an external electrode covering the outer surface of the flanges, wherein a specific axis perpendicular to the central axis is defined as the first axis, one direction along the first axis is defined as the positive direction, and the direction opposite to the positive direction is defined as the negative direction, the flanges protrude toward the positive direction side relative to the outer surface of the winding core, and the external electrode is located on the outer surface of the flanges, with respect to the positive direction side. The coil component covers the surface facing a particular direction, and the wire has a linear portion wound around the core and a joint portion located at the end of the wire and connected to the external electrode. The cross-section, perpendicular to the central axis and including the joint, has the negative-direction end of the joint positioned on the negative side relative to the positive-direction end of the external electrode, and the dimension along the first axis from the negative-direction end to the positive-direction end of the joint is larger than the wire diameter of the linear portion.

[0008] In the above configuration, the thickness of the wire at the joint is greater than the thickness of the linear portion. As a result, even if some external force is applied to the joint, the wire is less likely to break at the joint and at the boundary between the joint and the linear portion. [Effects of the Invention]

[0009] This prevents wire breakage at the joint and at the boundary between the joint and the linear section. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a perspective view of a coil component. [Figure 2] Figure 2 is an enlarged view of the vicinity of the second joint when viewed in the first negative direction. [Figure 3] Figure 3 is a cross-sectional view along the line 3-3 in Figure 2. [Figure 4] Figure 4 illustrates the manufacturing method of a coil component. [Figure 5] Figure 5 illustrates the manufacturing method of a coil component. [Figure 6] Figure 6 is a diagram illustrating the manufacturing method of a coil component. [Figure 7] Figure 7 illustrates the manufacturing method of a coil component. [Figure 8] Figure 8 illustrates the manufacturing method of a coil component. [Figure 9] Figure 9 is a diagram illustrating the manufacturing method of a coil component. [Figure 10] Figure 10 is a diagram illustrating the manufacturing method of a coil component. [Figure 11] Figure 11 is a diagram illustrating the manufacturing method of a coil component. [Figure 12] Figure 12 illustrates the manufacturing method of a coil component. [Figure 13] Figure 13 illustrates the manufacturing method of a coil component. [Figure 14] Figure 14 is a cross-sectional view of the modified coil component. [Modes for carrying out the invention]

[0011] An embodiment of a coil component will be described below with reference to the drawings. Note that the drawings may show enlarged versions of the components for easier understanding. The dimensional ratios of the components may differ from those shown in the actual components or in other drawings.

[0012] <About the overall structure> As shown in Figure 1, the coil component 10 comprises a core 10C and a top plate 12. The core 10C comprises a columnar winding core portion 11, a first flange portion 21, and a second flange portion 22. In the following text, the first flange portion 21 and the second flange portion 22 may be collectively referred to as the flange portion 20 when there is no need to distinguish between them.

[0013] The core part 11 is quadrangular prism-shaped. The cross-section orthogonal to the central axis C of the core part 11 is rectangular. Here, the "rectangular shape" means that it has four sides and is rectangular as a whole, and also includes a shape with rounded corners of the rectangle. The material of the core part 11 is a non-conductive material. Specifically, the material of the core part 11 is, for example, Ni-Zn ferrite, alumina, synthetic resin, and mixtures thereof, etc.

[0014] Here, a specific axis orthogonal to the central axis C of the core part 11 is defined 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 core part 11. Also, an axis orthogonal to both the first axis X and the central axis C is defined 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 core part 11. Also, an axis parallel to the central axis C is defined as the third axis Z. Then, one of the directions along the first axis X is defined as the first positive direction X1, and the direction opposite to the first positive direction X1 is defined as the first negative direction X2. Similarly, one of the directions along the second axis Y is defined as the second positive direction Y1, and the direction opposite to the second positive direction Y1 is defined as the second negative direction Y2. Also, one of the directions along the third axis Z is defined as the third positive direction Z1, and the direction opposite to the third positive direction Z1 is defined as the third negative direction Z2.

[0015] As shown in FIG. 1, the first flange part 21 is connected to the first end which is the end in the third positive direction Z1 of the core part 11. The first flange part 21 is a flat substantially square plate shape. The thickness direction of the first flange part 21 is the direction along the third axis Z. When viewed in the direction along the third axis Z, each side of the first flange part 21 is parallel to each side of the core part 11. Also, the first flange part 21 projects outward with respect to the outer surface of the core part 11 in the directions along the first axis X and the second axis Y. That is, the first flange part 21 also projects to the first positive direction X1 side with respect to the outer surface of the core part 11.

[0016] The second flange portion 22 is connected to the second end which is the end of the core portion 11 on the second negative direction Z2 side. The second flange portion 22 has a shape that is symmetric with the first flange portion 21 in terms of surface. That is, the second flange portion 22 is substantially in the shape of a square plate. The second flange portion 22 protrudes outward with respect 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 second flange portion 22 also protrudes toward the first positive direction X1 side with respect to the outer surface of the core portion 11.

[0017] The materials of the first flange portion 21 and the second flange portion 22 are the same as the material of the core portion 11. Also, the first flange portion 21 and the second flange portion 22 are integrally formed with the core portion 11. The top plate 12 is in the shape of a flat rectangular plate. The thickness direction of the top plate 12 is the direction along 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 with respect 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 spanned between the first flange portion 21 and the second flange portion 22. The material of the top plate 12 is the same as the material of the core portion 11.

[0018] The coil component 10 includes a first external electrode 41 and a second external electrode 42. The first external electrode 41 covers the entire surface of the outer surface of the first flange portion 21 facing the first positive direction X1. The second external electrode 42 covers the entire surface of the outer surface of the second flange portion 22 facing the first positive direction X1. Incidentally, hereinafter, when there is no need to distinguish between the first external electrode 41 and the second external electrode 42, they may be collectively referred to as the external electrode 40.

[0019] As shown in Figure 3, 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 furthest to the first negative direction X2 among the layers of the external electrode 40. That is, the base layer L0 directly covers the outer surface of the flange portion 20 that faces the first positive direction X1. The base layer L0 contains Ag. The first layer L1 covers the surface of the base layer L0 that faces the first positive direction X1. The first layer L1 contains Ni. The second layer L2 covers the surface of the first layer L1 that faces the first positive direction X1. The second layer L2 contains Cu.

[0020] 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 of the external electrode 40. Therefore, when the base layer L0, the first layer L1, and the second layer L2 are considered inner layers, the third layer L3 is an outer layer located on the opposite side of the outer surface of the flange portion 20 from the inner layers. The third layer L3 contains Sn. The first layer L1, the second layer L2, and the third layer L3 are plating layers on the base layer L0. Note that in Figure 1, the boundaries of these layers on each external electrode 40 are shown as being absent.

[0021] <About the wire> As shown in Figure 1, the coil component 10 includes a wire 50 wound around a winding core 11. As shown in Figure 2, the wire 50 has a conductor 50A and an insulating coating 50B. The conductor 50A is linear. The conductor 50A is made of, for example, Cu. In this embodiment, the diameter of the conductor 50A is about 10 μm. The insulating coating 50B covers the outer surface of the conductor 50A. The insulating coating 50B is made of a synthetic resin such as polyurethane and polyamide-imide. In this embodiment, the thickness of the insulating coating 50B is about 2.5 μm. The wire 50 has a substantially circular shape in cross-section perpendicular to the direction in which the wire 50 extends.

[0022] As shown in Figure 1, the wire 50 has a first joint 51A, a second joint 51B, and a linear portion 52. In the following description, the first joint 51A and the second joint 51B may be collectively referred to as the joint 51 when there is no need to distinguish between them. 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 coating 50B and only has a conductor 50A. At least a portion of the interface between the joint 51 and the third layer L3 is a Cu-Sn alloy. The phrase "only has a conductor 50A" above means that the presence of a trace amount of insulating coating 50B is permitted. Specifically, when the joint 51 is observed facing the first negative direction X2, if the proportion occupied by the conductor 50A is 97% or more, it is considered to "have only the conductor 50A".

[0023] The linear portion 52 is the part of the wire 50 other than the joint portion 51. That is, the linear portion 52 is wound around the winding core portion 11. The linear portion 52 has an insulating coating 50B and a conductor 50A. That is, due to the dimensional relationship between the conductor 50A and the insulating coating 50B, the diameter of the linear portion 52 is approximately 15 μm.

[0024] <Regarding the temporary fixing point of the wire> As shown in Figure 2, 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 portion 11 side relative to the second joint portion 51B. Also, the temporary fixing portion 53 is adjacent to the second joint portion 51B in the extension direction of the wire 50.

[0025] 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, with an insulating coating 50B, is embedded in the second external electrode 42 in at least a portion thereof.

[0026] <Regarding the dimensional relationship between the external electrode and the wire> The dimensional relationship between each external electrode 40 and each joint 51 will be explained below. In the following explanation, the dimensional relationship between the second external electrode 42 and the second joint 51B will be described as representative, but the dimensional relationship between the first external electrode 41 and the first joint 51A is similar.

[0027] As shown in Figure 3, assume a cross-sectional view taken at a specific cross-section perpendicular to the central axis C and including the second joint 51B. The second joint 51B is embedded in the second external electrode 42. That is, the end of the second joint 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 entire second joint 51B is embedded in the second external electrode 42. Specifically, in the direction along the first axis X, the end of the second joint 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.

[0028] The end face of the second joint 51B on the first positive direction X1 side is a flat surface parallel to the second axis Y and the central axis C. Furthermore, the end face of the second joint 51B on the first positive direction X1 side is substantially flush with the end of the second external electrode 42 on the first positive direction X1 side.

[0029] The end of the second external electrode 42 on the first positive direction X1 side is determined by acquiring the contour of the second external electrode 42 in a specific cross-section using an electron microscope and image processing. The point of this contour that is closest to the first positive direction X1 is then defined as the end of the second external electrode 42 on the first positive direction X1 side.

[0030] In the specific cross-section described above, the end of the second joint 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 joint 51B is located in the third layer L3 and does not extend to the second layer L2.

[0031] In a specific cross-section, the dimension P1 along the first axis X from the end of the second joint 51B on the first negative direction X2 side to the end on the first positive direction X1 side is approximately 21 μm. That is, the dimension P1 along the first axis X from the end of the second joint 51B on the first negative direction X2 side to the end on the first positive direction X1 side is larger than the wire diameter of the linear portion 52.

[0032] In a specific cross-section, the portion of the second joint 51B located on the first negative side relative to the end of the second external electrode 42 on the first positive direction X1 side is defined as the embedded portion 54. In this embodiment, the portion of the second joint 51B in the specific cross-section, excluding the end face on the first positive direction X1 side, corresponds to the embedded portion 54. In a specific cross-section, the maximum dimension of the embedded portion 54 in the direction along 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.

[0033] Furthermore, with respect to the location at the first dimension A1, the dimension of the embedded portion 54 along the second axis Y on the first positive direction X1 side is defined as the second dimension A2. The second dimension A2 is smaller than the first dimension A1.

[0034] <About the manufacturing method of coil components> As shown in Figure 4, the manufacturing method for the coil component 10 includes a preparation step S11, a first end ball portion formation step S12, a first end pressing step S13, a first end joining step S14, a first end removal step S15, and a winding step S16. The manufacturing method for the coil component 10 also includes a second end temporary pressing step S17, a second end temporary fixing step S18, a wire cutting step S19, a second end ball portion formation step S20, a second end pressing step S21, a second end joining step S22, and a second end removal step S23.

[0035] Of the above steps, the steps from the first end ball formation step S12 to the first end removal step S15, and the steps from the second end temporary pressing step S17 to the second end removal step S23 are steps related to the joining method of the wire 50.

[0036] First, preparation step S11 is performed. In preparation step S11, a core 10C on which the external electrode 40 is formed is prepared. The core 10C is formed by mixing Ni-Zn ferrite powder with a synthetic resin binder and firing a molded body formed by press molding. This forms a core 10C having the winding core portion 11 and the first flange portion 21 and second flange portion 22 as described above. 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 vapor deposition of the paste, a base layer L0 is formed. Furthermore, electroplating is performed on the base layer L0 to form the first layer L1, the second layer L2, and the third layer L3. This forms the first external electrode 41. Similarly, the 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 on which the external electrodes 40 are formed is clamped from the outside of each flange portion 20 by a pair of rotating chucks RC. This supports the core 10C so that it can rotate around the central axis C as the center of rotation.

[0037] Next, the first end ball formation process S12 is performed. Prior to the first end ball formation process S12, the first end of the wire 50 has a conductor 50A and an insulating coating 50B. As shown in Figure 5, in the first end ball formation process S12, a laser is irradiated onto the first end of the wire 50. At the irradiated area, the insulating coating 50B melts, exposing the conductor 50A. Then, as shown in Figure 6, at the irradiated area, the conductor 50A melts, forming a roughly spherical ball portion BP with a diameter larger than the wire diameter of the linear portion 52. Note that in this state, some of the insulating coating 50B may remain on the surface.

[0038] Next, the first end pressing step S13 is performed. As shown in Figure 6, in the first end pressing step S13, the ball portion BP is pressed against the first external electrode 41 using a laser-transmitting member CP, which is made of a material that allows laser light to pass through. Specifically, the ball portion BP is sandwiched between the laser-transmitting member CP and the first external electrode 41. The laser-transmitting member CP can be made of any material that allows laser light to pass through, such as borosilicate glass or sapphire glass. By pressing the laser-transmitting member CP against the ball portion BP, the insulating coating 50B remaining on the ball portion BP is welded to the laser-transmitting member CP.

[0039] Next, the first end joining process S14 is performed. As shown in Figure 7, in the first end joining process S14, the ball portion BP is sandwiched between the transparent member CP and the first external electrode 41, and a laser is irradiated onto the ball portion BP from the side of the transparent member CP. Therefore, in this state, the ball portion BP is in contact with the first external electrode 41. As a result, a first joint portion 51A is formed at the first end of the wire 50, connected to the first external electrode 41. Also, due to the pressing force of the transparent member CP, the ball portion BP is embedded in the molten and softened third layer L3, so that an embedded portion 54 is formed. Furthermore, due to the pressing force of the transparent member CP, the end face of the first joint portion 51A in the first positive direction X1 is formed as a flat surface.

[0040] 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 this first end removal step S15, the insulating coating 50B remaining on the ball portion BP is removed from the wire 50 together with the transparent member CP.

[0041] Next, the winding process S16 is performed. In the winding process S16, the core 10C is rotated together with the rotary chuck RC with the central axis C as the center of rotation, and the wire 50 is wound around the winding core 11. Next, the second end temporary pressing step S17 is performed. As shown in Figure 8, in the second end temporary pressing step S17, the wire 50 is pulled out from the portion wound around the core 11 and positioned on the second external electrode 42. Then, the wire 50 is sandwiched between the transparent member CP and the second external electrode 42. This temporarily sets the position of the wire 50.

[0042] Next, the second end temporary fixing process S18 is performed. As shown in Figure 9, in the second end temporary fixing process S18, a laser is irradiated from the side of the transparent member CP onto the temporary fixing point on the second external electrode 42. This joins the temporary fixing point 53 on the winding core 11 side to the temporary fixing point where the second joint 51B on the wire 50 is to be formed. At this time, the third layer L3 melts at the temporary fixing point where the laser is irradiated. Then, by pressing the temporary fixing point 53 of the wire 50 onto the melted temporary fixing point, the temporary fixing point 53 is embedded in the temporary fixing point and joined. As a result, the temporary fixing point 53 is formed on the linear portion 52. Note that in the second end temporary fixing process S18, the laser is not irradiated directly onto the wire 50, but onto the third layer L3 of the second external electrode 42. Specifically, the laser is irradiated along the direction in which the wire 50 extends. As a result, the insulating coating 50B remains unmelted at the temporary fixing point 53.

[0043] Next, the wire cutting process S19 is performed. As shown in Figure 10, in the wire cutting process S19, first, the transparent member CP is removed from the wire 50. Next, in the stretching direction of the wire 50, a laser is irradiated onto the portion of the wire 50 opposite to the portion wound around the core 11 relative to the temporary fixing portion 53. This cuts the wire 50, and the second end of the wire 50 is formed.

[0044] Next, the second end ball formation process S20 is performed. As shown in Figure 11, in the second end ball formation process S20, the second end of the wire 50 is irradiated with a laser. At the irradiated area, the insulating coating 50B melts, exposing the conductor 50A. At the irradiated area, the conductor 50A melts, forming a roughly spherical ball portion BP with a diameter larger than the wire diameter of the linear portion 52. Note that in this state, some of the insulating coating 50B may remain on the surface.

[0045] Next, the second end pressing step S21 is performed. As shown in Figure 12, in the second end pressing step S21, the ball portion BP is pressed against the second external electrode 42 using the permeable member CP. Specifically, the ball portion BP is sandwiched between the permeable member CP and the second external electrode 42. By pressing the permeable member CP against the ball portion BP, the insulating coating 50B remaining on the ball portion BP is welded to the permeable member CP.

[0046] Next, the second end joining process S22 is performed. As shown in Figure 13, in the second end joining process S22, the ball portion BP is sandwiched between the transparent member CP and the second external electrode 42, and a laser is irradiated onto the ball portion BP from the side of the transparent member CP. Therefore, in this state, the ball portion BP is in contact with the second external electrode 42. As a result, a second joint portion 51B is formed at the second end of the wire 50, connected to the second external electrode 42. Also, due to the pressing force of the transparent member CP, the ball portion BP is embedded in the molten and softened third layer L3, so that an embedded portion 54 is formed. Furthermore, due to the pressing force of the transparent member CP, the end face of the second joint portion 51B in the first positive direction X1 is formed as a flat surface.

[0047] 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 coating 50B remaining on the ball portion BP is removed from the wire 50 together with the transparent member CP.

[0048] <Effects of this embodiment> (1) In the above embodiment, the thickness of each joint 51 of the wire 50 is greater than the thickness of the linear portion 52. As a result, even if some external force is applied to each joint 51, the wire 50 is less likely to break at the boundary between each joint 51 and the linear portion 52.

[0049] (2) In the above embodiment, the first dimension A1 is larger than the wire diameter of the linear portion 52. This increases the contact area between each joint 51 and the external electrode 40. As a result, it is possible to prevent the wire 50 from coming off the external electrode 40.

[0050] (3) In the above embodiment, the second dimension A2 is smaller than the first dimension A1. Therefore, the embedded portion 54 includes a portion in a specific cross-section in which the dimension in the direction along the second axis Y becomes smaller as it moves toward the first positive direction X1. In other words, a portion of the joint 51 is covered by the external electrode 40 from the outside. Therefore, the joint 51 is less likely to come off the external electrode 40.

[0051] (4) In the above embodiment, the wire 50 has a conductor 50A and an insulating coating 50B. Each joint 51 has only the conductor 50A. With this configuration, the insulating coating 50B is less likely to hinder the electrical connection between the joint 51 and the external electrode 40.

[0052] (5) In the above embodiment, the temporary fixing portion 53 has a conductor 50A and an insulating coating 50B. With this configuration, the conductor 50A in the temporary fixing portion 53 is not in direct contact with the external electrode 40. Therefore, it is possible to suppress the leaching of components of the conductor 50A into the external electrode 40 and the thinning of the conductor 50A.

[0053] (6) In the above embodiment, the end of the joint 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 joint 51 does not reach the interface between the third layer L3 and the second layer L2. If, for example, the joint 51 were to reach the interface between the third layer L3 and the second layer L2 in the second end pressing step S21, the joint 51 would be subjected to a reaction force from that interface. As a result, there is a risk that an excessive external force will be applied to the joint 51. With the above configuration, such an external force applied to the joint 51 can be suppressed.

[0054] (7) In the above embodiment, the third layer L3 contains Sn. Sn is a relatively soft metal. Therefore, when connecting the joint 51 to the external electrode 40, the external force acting on the joint 51 can be suppressed.

[0055] (8) In the above embodiment, the linear portion 52 has a temporary fixing portion 53 joined to the third layer L3. 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 with 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 molten third layer L3. By forming the temporary fixing portion 53, the wire 50 is less likely to shift position when the second joint portion 51B is formed.

[0056] (9) In the above embodiment, the end face of the joint 51 on the first positive direction X1 side is an end face parallel to the second axis Y and the central axis C. With this configuration, the orientation of the coil component 10 is stabilized when the coil component 10 is connected to the substrate with solder or the like.

[0057] (10) In the above embodiment, the method for joining the wire 50 includes a second end ball portion forming step S20 and a second end joining step S22. The method for joining the wire 50 also includes a second end pressing step S21 after the second end ball portion forming step S20 and before the second end joining step S22. By performing the second end pressing step S21, the ball portion BP can be deeply embedded in the second external electrode 42. The same applies to the first end pressing step S13.

[0058] (11) In the above embodiment, the wire 50 has a conductor 50A and an insulating coating 50B in the step prior to the second end ball portion formation step S20. The method of joining the wire 50 includes a second end removal step S23 after the second end joining step S22, in which the transparent member CP is removed from the wire 50 together with the insulating coating 50B remaining on the ball portion BP. By performing the second end removal step S23, the end face of the second joint portion 51B on the first positive direction X1 side is exposed to the conductor 50A. Therefore, compared to a configuration in which the end face of the second joint portion 51B on the first positive direction X1 side includes the insulating coating 50B, the above configuration improves the wettability of the solder when connecting the second external electrode 42 to the substrate with solder or the like. The same applies to the first end removal step S15.

[0059] (12) In the above embodiment, in the first end pressing step S13 and the second end pressing step S21, the insulating coating 50B is welded only to a portion of the transparent member CP. By utilizing the portion where the insulating coating 50B is not welded, the same transparent member CP can be used again in the wire joining step 50. Therefore, since the transparent member CP can be reused instead of being discarded after a single use, an increase in the cost of the above steps can be suppressed.

[0060] (13) In the above embodiment, the third layer L3 of the external electrode 40 contains Sn. Also, the conductor 50A contains Cu. That is, each joint 51 contains Cu. Therefore, a Cu-Sn alloy may be formed at the boundary between the joint 51 and the external electrode 40. If a Cu-Sn alloy is formed at the boundary in this way, the electrical properties of the joint 51 will be stable.

[0061] <Example of changes> The above embodiments and the following modifications can be combined and implemented to the extent that they do not conflict with each other technically.

[0062] The configuration of the coil component 10 is not limited. For example, the top plate 12 can be omitted from the coil component 10. The core portion 11 does not have to be a rectangular prism. For example, the cross-sectional shape of the core portion 11 may be circular, elliptical, or a polygon other than a rectangle.

[0063] The wire diameter of the linear portion 52 of the wire 50 is not limited to the example of the above embodiment. It is sufficient that the dimension P1 in the direction along the first axis X from the end of the joint 51 on the first negative direction X2 side to the end on the first positive direction X1 side is larger than the wire diameter of the linear portion 52.

[0064] The layer structure of the external electrode 40 is not limited to the examples of the above embodiment. The external electrode 40 only needs to have at least one conductive layer. In that case, that one layer constitutes the outermost layer. Also, in the above embodiment, the material of each layer of the external electrode 40 is not limited to the examples of the above embodiment.

[0065] The end of the joint 51 on the first negative direction X2 side may 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 joint 51 on the first negative direction X2 side may be located on the first negative direction X2 side relative to the end of the inner layer on the first positive direction X1 side.

[0066] The joint 51 may have an insulating coating 50B in addition to the conductor 50A. It is sufficient that the joint 51 and the external electrode 40 are electrically connected. - In a specific cross-section, the first dimension A1 does not have to be the dimension of the location where the buried portion 54 is the maximum dimension in the direction along the second axis Y. In a specific cross-section, the first dimension A1 may be the dimension in the direction along the second axis Y at any location along the first axis X of the buried portion 54. Furthermore, when the second dimension A2 is the dimension of the buried portion 54 in the direction along the second axis Y on the first positive direction X1 side with respect to the location of the first dimension A1, the effect in (3) is obtained if the second dimension A2 is smaller than the first dimension A1.

[0067] The joint portion 51 does not need to be entirely embedded in the external electrode 40, as long as at least a part of it is embedded in the external electrode 40. For example, in the example shown in Figure 14, in a specific cross section, the end of the joint 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 specific cross section, the end of the joint 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. In this example shown in Figure 14 as well, the dimension P1 in the direction along the first axis X from the end of the joint portion 51 on the first positive direction X1 side to the end on the first negative direction X2 side in a specific cross section is larger than the wire diameter of the linear portion 52. Also, in the example shown in Figure 14, the second dimension A2 is larger than the first dimension A1. Furthermore, in the example shown in Figure 14, in a specific cross-section, the maximum dimension of the embedded portion 54 in the direction along the second axis Y is smaller than the wire diameter of the linear portion 52.

[0068] If the joint portion 51 is connected to the external electrode 40, the linear portion 52 does not need to have a temporary fixing portion 53. In this case, the second end temporary pressing step S17 and the second end temporary fixing step S18 can be omitted in the method of joining the wire 50.

[0069] In the method for joining the wire 50, the first end pressing step S13, the first end removal step S15, the second end pressing step S21, and the second end removal step S23 can be omitted. That is, if the joint 51 is connected to the external electrode 40, the permeable member CP does not need to be used in the method for joining the wire 50.

[0070] The method for manufacturing the coil component is not limited to the examples of the above embodiments. For example, after the preparation step S11, the winding step S16 may be performed, followed by the first end ball portion forming step S12 and the first end joining step S14.

[0071] <Note> The technical concepts that can be derived from the above embodiments and modifications are described below. [1] A core having a columnar winding core and a pair of flanges connected to the ends in the direction along the central axis of the winding core, a wire wound around the winding core, and external electrodes covering the outer surfaces of the flanges, wherein a specific axis perpendicular to the central axis is defined as the first axis, one direction along the first axis is defined as the positive direction, and the direction opposite to the positive direction is defined as the negative direction, the flanges protrude toward the positive direction relative to the outer surface of the winding core, and the external electrodes face toward the positive direction on the outer surface of the flanges. A coil component that covers a surface, wherein the wire has a linear portion wound around the core and a joint portion located at the end of the wire and connected to the external electrode, and in a cross section perpendicular to the central axis and including the joint portion, the negative-direction end of the joint portion is located on the negative-direction side relative to the positive-direction end of the external electrode, and the dimension along the first axis from the negative-direction end to the positive-direction end of the joint portion is larger than the wire diameter of the linear portion.

[0072] [2] The coil component according to [1], wherein the second axis is perpendicular to both the central axis and the first axis, and in the cross-section, the portion of the joint located on the negative side relative to the positive end of the external electrode is defined as the embedded portion, and in the cross-section, the maximum dimension of the embedded portion in the direction along the second axis is larger than the wire diameter of the linear portion.

[0073] [3] The coil component described in [1] or [2], wherein the second axis is an axis perpendicular to both the central axis and the first axis, and in the cross-section, the portion of the joint located on the negative side with respect to the positive side end of the external electrode is defined as the embedded portion, and in the cross-section, the dimension in the direction along the second axis at any point in the direction along the first axis of the embedded portion is defined as the first dimension, and the dimension of the embedded portion in the direction along the second axis on the positive side with respect to the location of the first dimension is defined as the second dimension, wherein the second dimension is smaller than the first dimension.

[0074] [4] The coil component according to any one of [1] to [3], wherein the wire has a linear conductor and an insulating coating covering the outer surface of the conductor, the linear portion has the insulating coating and the conductor, and the joint portion has only the conductor.

[0075] [5] The coil component according to any one of [1] to [4], wherein the external electrode has an inner layer and an outer layer located on the opposite side of the inner layer from the outer surface of the flange, and in the cross-section, the negative end of the joint is located on the positive side relative to the positive end of the inner layer.

[0076] [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. [7] The coil component according to [6], wherein the linear portion has a temporary fixing portion joined to the outermost layer.

[0077] [8] A wire joining method comprising: a ball forming step of forming a ball portion having a diameter larger than the wire diameter of the linear portion before melting at the end of the wire by melting the wire; and a joining step of forming a joint portion connected to the external electrode at the end of the wire by irradiating the ball portion with a laser while the ball portion is in contact with an external electrode covering the outer surface of a core.

[0078] [9] A wire joining method according to [8], wherein, after the ball portion forming step and before the joining step, the ball portion is pressed against the external electrode by sandwiching it between a transparent member made of a material through which the laser passes and the external electrode, and in the joining step, the laser is irradiated from the side of the transparent member while the ball portion is sandwiched between the transparent member and the external electrode.

[0079]

[10] The wire joining method according to [9], wherein the wire has a linear conductor and an insulating coating covering the outer surface of the conductor in a step prior to the ball portion forming step, and after the joining step, the transparent member is removed from the wire together with the insulating coating remaining on the ball portion.

[0080]

[11] A method for manufacturing a coil component, comprising: a preparation step of preparing a core having a columnar winding core and a pair of flanges connected to the ends in a direction along the central axis of the winding core, wherein external electrodes covering the outer surfaces of the flanges are formed on the core; a winding step of winding a wire around the winding core; a ball portion forming step of melting the wire 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 of irradiating the ball portion with a laser while the ball portion is in contact with the external electrodes to form a joint portion at the end of the wire connected to the external electrodes.

[0081]

[12] A method for manufacturing a coil component according to

[11] , comprising a pressing step in which, after the ball portion forming step and before the joining step, the ball portion is pressed against the external electrode by sandwiching it between a transparent member made of a material through which the laser passes and the external electrode, and in the joining step, the laser is irradiated from the side of the transparent member while the ball portion is sandwiched between the transparent member and the external electrode.

[0082]

[13] The method for manufacturing a coil component according to

[12] , wherein the wire has a linear conductor and an insulating coating covering the outer surface of the conductor in a step prior to the ball portion forming step, and after the joining step, the method further comprises a removal step of removing the transparent member from the wire together with the insulating coating remaining on the ball portion.

[0083]

[14] The method for manufacturing a coil component according to any one of

[11] to

[13] , wherein the external electrode has an outermost layer which is the outermost layer of the external electrode and contains Sn, and before the ball portion forming step, the laser is irradiated onto the temporary fixing location of the external electrode to join the temporary fixing location on the winding core side to the location on the wire where the joint portion is to be formed. [Explanation of symbols]

[0084] A1…First dimension A2…Second dimension BP...Ball Club C…Central axis CP...Transparent material P1... Dimensions X…1st axis X1…first positive direction X2…1st negative direction 10…Coil components 10C... Core 11…Core section 20... Guard part 40...External electrode 50... Wire 50A...Conductor 50B...Insulating coating 51…Joint part 52…Linear part 53... Temporary fixing part 54...Buried part

Claims

1. A core having a columnar winding core and a pair of flanges connected to the ends in the direction along the central axis of the winding core, The wire wound around the aforementioned core, An external electrode covering the outer surface of the flange portion, Equipped with, The external electrode has an outermost layer, which is the outermost layer of the external electrode. The outermost layer contains Sn, When a specific axis perpendicular to the central axis is defined as the first axis, and an axis perpendicular to both the central axis and the first axis is defined as the second axis, and one direction along the first axis is defined as the positive direction, and the direction opposite to the positive direction is defined as the negative direction, The flange portion protrudes in the forward direction relative to the outer surface of the core portion. The external electrode covers the surface of the flange portion that faces the forward direction. The wire has a linear portion wound around the core and a connecting portion located at the end of the wire and connected to the external electrode. In a cross-section perpendicular to the central axis and including the joint, the negative-direction end of the joint is located on the negative-direction side relative to the positive-direction end of the external electrode, and the dimension along the first axis from the negative-direction end to the positive-direction end of the joint is larger than the wire diameter of the linear portion. In the cross-section, the portion of the joint located on the negative side with respect to the positive end of the external electrode is defined as the embedded portion. In the aforementioned cross-section, when the dimension in the direction along the second axis at any point along the first axis of the embedded portion is defined as the first dimension, and the dimension in the direction along the second axis on the positive side of the location of the first dimension is defined as the second dimension, The second dimension is smaller than the first dimension. Coil components.

2. In the cross-section, the maximum dimension of the embedded portion in the direction along the second axis is larger than the wire diameter of the linear portion. The coil component according to claim 1.

3. The wire comprises a linear conductor and an insulating coating covering the outer surface of the conductor. The linear portion has the insulating coating and the conductor, The joint portion has only the conductor. The coil component according to claim 1.

4. The external electrode has an inner layer and an outer layer located on the opposite side of the inner layer from the outer surface of the flange. In the cross-section, the negative-direction end of the joint is located on the positive-direction side relative to the positive-direction end of the inner layer. The coil component according to claim 1.

5. The linear portion has a temporary fixing portion joined to the outermost layer. The coil component according to claim 1.

Images