Coil component and core component for coil component

Abstract

This core component for a coil component is provided with a drum-shaped core, and an external electrode (40). The drum-shaped core comprises a columnar winding section and a pair of flange sections (20). The external electrode (40) covers an outer surface of the flange sections (20). The external electrode (40) covers a surface, of the outer surface of the flange sections (20), that faces a first positive direction (Y1). The external electrode (40) is provided with an underlying electrode layer (41), and an Sn plating layer (42) layered onto the underlying electrode layer (41). The underlying electrode layer (41) has an electrode concavity (50) that is depressed toward a first negative direction (Y2). The thickness (S1) of the Sn plating layer (42) in a first region (A1) is greater than the thickness (S2) of the Sn plating layer (42) in a second region (A2), when, viewed in the first negative direction (Y2), the first region (A1) is a region of the external electrode (40) in which the electrode concavity (50) exists and the second region (A2) is a region adjacent to the first region (A1) in a direction along a second axis Z.

Description

Coil components and core components for coil components

[0001] The present disclosure relates to coil components and core components for coil components.

[0002] The coil component described in Patent Document 1 includes a winding core and two flanges. The winding core is rectangular prism-shaped. The two flanges are connected to both ends of the winding core. The winding core and flanges form the core of the coil component. The coil component described in Patent Document 1 also includes an electrode and a wire. The electrode is attached to the flange. The electrode includes a base electrode and a Sn plating layer. The wire is wound around the winding core. The wire includes a conductor and a coating that covers the conductor. The end of the wire is attached to the electrode by thermocompression bonding.

[0003] Japanese Patent Application Laid-Open No. 2017-162897

[0004] In the coil component described in Patent Document 1, when the wire end is thermocompression-bonded, a jig such as a heater tip is pressed against the wire end. Pressing the jig against the wire end melts the wire coating. The molten coating may displace a portion of the Sn (tin) plating layer. As a result, the underlying nickel film and base electrode may be exposed through the Sn plating layer.

[0005] In order to solve the above problems, the present disclosure provides a drum-shaped core including a columnar winding core and a pair of flanges connected to the winding core in a direction along the central axis of the winding core, and an external electrode covering an outer surface of the flange, wherein when a specific axis perpendicular to the central axis is defined as a first axis, one of the directions along the first axis is defined as a positive direction, a direction opposite to the positive direction is defined as a negative direction, and an axis perpendicular to both the first axis and the central axis is defined as a second axis, the external electrode covers the surface of the outer surface of the flange facing the positive direction, and the external electrode is disposed between the flange and the first axis. and a Sn plating layer laminated on the base electrode layer on the positive-direction side, wherein the base electrode layer has an electrode recess recessed toward the negative direction, and when viewed in the negative direction, a region of the external electrode where the electrode recess exists is defined as a first region, and a region adjacent to the first region in a direction along the second axis is defined as a second region, and the thickness of the Sn plating layer in the first region is greater than the thickness of the Sn plating layer in the second region.

[0006] The present disclosure also provides a drum-shaped core having a columnar winding core and a pair of flanges connected to the winding core in a direction along the central axis of the winding core, an external electrode covering an outer surface of the flange, and a wire wound around the winding core and joined to the external electrode, wherein when a specific axis perpendicular to the central axis is defined as a first axis, one of the directions along the first axis is defined as a positive direction, a direction opposite to the positive direction is defined as a negative direction, and an axis perpendicular to both the first axis and the central axis is defined as a second axis, the external electrode covers the surface of the outer surface of the flange facing the positive direction, and the external electrode is a base electrode layer in contact with the flange and a wire on the positive direction side. and a Sn plating layer laminated on the base electrode layer, wherein the base electrode layer has an electrode recess recessed toward the negative direction, and when viewed in a perspective manner in the negative direction, a region of the external electrode where the electrode recess is present is defined as a first region, and a region adjacent to the first region in a direction along the second axis is defined as a second region, the wire has a joint portion joined to the first region, and the Sn plating layer is adjacent to the joint portion in a direction along the second axis and has a trace portion containing an organic component, and when viewed in a perspective manner in the negative direction, the trace portion is located within the first region.

[0007] According to the above configuration, it is possible to prevent the base electrode layer from being exposed from the Sn plating layer.

[0008] FIG. 1 is a perspective view of a core component. FIG. 2 is a schematic end view showing a portion of a cross section of the core component perpendicular to the central axis. FIG. 3 is a perspective view of a coil component including a core component. FIG. 4 is a plan view showing the periphery of an external electrode of a coil component including a core component. FIG. 5 is a schematic end view showing a portion of a cross section taken along line 5-5 in FIG. 4. FIG. 6 is a plan view showing the periphery of an external electrode of a coil component including a core component of a modified example. FIG. 7 is a plan view showing the periphery of an external electrode of a coil component including a core component of a modified example. FIG. 8 is a schematic end view showing a portion of a cross section taken along line 8-8 in FIG. 7. FIG. 9 is a schematic end view showing a portion of a cross section taken along line 9-9 in FIG. 7. FIG. 10 is a schematic end view showing a portion of a cross section of the core component of a modified example perpendicular to the central axis.

[0009] Hereinafter, an embodiment of a core component for a coil component and a coil component will be described with reference to the drawings. Note that the drawings may show components enlarged for ease of understanding. The dimensional ratios of the components may differ from those in the actual drawings or from those in other drawings.

[0010] 1, the core part 100 includes a drum-shaped core 10C. The drum-shaped core 10C includes a columnar winding core portion 11, a first flange portion 21, and a second flange portion 22.

[0011] The winding core 11 has a rectangular prism shape. The material of the winding core 11 is, for example, alumina, Ni-Zn ferrite, synthetic resin, or a mixture thereof. The first flange 21 is connected to a first end of the winding core 11 in the direction along the central axis X. The second flange 22 is connected to a second end of the winding core 11 in the direction along the central axis X. The first flange 21 and the second flange 22 are made of the same material as the winding core 11. Furthermore, the first flange 21 and the second flange 22 are integrally molded with the winding core 11.

[0012] Here, a specific axis perpendicular to the central axis X of the winding core 11 is referred to as the first axis Y. In this embodiment, the first axis Y is parallel to two of the four sides of the winding core 11 when viewed in the direction along the central axis X. An axis perpendicular to both the central axis X and the first axis Y is referred to as the second axis Z. In this embodiment, the second axis Z is parallel to the remaining two of the four sides of the winding core 11 when viewed in the direction along the central axis X. One of the directions along the central axis X is referred to as the positive direction X1, and the direction opposite to the positive direction X1 is referred to as the negative direction X2. In this embodiment, the positive direction X1 coincides with the direction along the central axis X from the winding core 11 toward the first flange 21. The negative direction X2 coincides with the direction along the central axis X from the winding core 11 toward the second flange 22. One of the directions along the first axis Y is defined as a first positive direction Y1, and the direction opposite to the first positive direction Y1 is defined as a first negative direction Y2. Similarly, one of the directions along the second axis Z is defined as a second positive direction Z1, and the direction opposite to the second positive direction Z1 is defined as a second negative direction Z2.

[0013] When viewed from the direction along the central axis X, the first flange 21 protrudes outward relative to the winding core 11 in the directions along the first axis Y and the second axis Z. The first flange 21 has a shape that is plane-symmetrical with respect to an imaginary plane that passes through the central axis X and is parallel to the central axis X. The first flange 21 also has a flat shape in which the dimension along the central axis X is smaller than the dimension along the first axis Y and the dimension along the second axis Z.

[0014] The second flange 22 and the first flange 21 have shapes that are plane-symmetrical with respect to an imaginary plane that passes through the center of the winding core 11 and is parallel to the first axis Y and the second axis Z. That is, when viewed from the direction along the central axis X, the second flange 22 protrudes outward from the winding core 11 in the direction along the first axis Y and the direction along the second axis Z. In the following description, when there is no need to distinguish between the first flange 21 and the second flange 22, the first flange 21 and the second flange 22 will be referred to as flange 20.

[0015] The core component 100 includes two external electrodes 40. One external electrode 40 covers the entire surface of the first flange 21 facing in the first positive direction Y1 and a portion of the surface adjacent to the surface facing in the first positive direction Y1. The other external electrode 40 covers the entire surface of the second flange 22 facing in the first positive direction Y1 and a portion of the surface adjacent to the surface facing in the first positive direction Y1.

[0016] 2, each flange 20 has a core recess 30. The core recess 30 is recessed in the first negative direction Y2 relative to a plane of the flange 20 that is closest to the first positive direction Y1. When viewed in the first negative direction Y2, the core recess 30 is located in the center of the flange 20 in the direction along the second axis Z.

[0017] The core recess 30 extends to the edge on the positive direction X1 side and the edge on the negative direction X2 side on the surface of the flange portion 20 facing the first positive direction Y1. That is, the core recess 30 is open to the positive direction X1 side and the negative direction X2 side. When viewed in the first negative direction Y2, the edge on the second positive direction Z1 side and the edge on the second negative direction Z2 side of the core recess 30 are both parallel to the central axis X. Therefore, when viewed in the first negative direction Y2, the core recess 30 has a substantially rectangular shape.

[0018] As shown in FIG. 2 , the external electrode 40 includes a base electrode layer 41 and a Sn plating layer 42. The base electrode layer 41 is in contact with the outer surface of the flange 20 facing the first positive direction Y1 and a portion of the surface adjacent thereto. That is, the base electrode layer 41 directly covers the outer surface of the flange 20. For example, the base electrode layer 41 is made of a material primarily composed of silver. The Sn plating layer 42 is laminated on the base electrode layer 41. As described above, a portion of the base electrode layer 41 covers the outer surface of the flange 20 facing the first positive direction Y1, and therefore a portion of the Sn plating layer 42 is laminated on the base electrode layer 41 on the first positive direction Y1 side. Note that the end surface of the core component 100 facing the first positive direction Y1, on which each external electrode 40 is located, is the mounting surface that faces the substrate when the core component 100 is mounted on the substrate.

[0019] <Electrode Recesses of Core Component> As shown in FIG. 2 , the base electrode layer 41 has an electrode recess 50. The electrode recess 50 is a portion of the base electrode layer 41 that is recessed in the first negative direction Y2. When viewed in the first negative direction Y2, the electrode recess 50 is located within the range of the core recess 30. The electrode recess 50 also follows the recess shape of the core recess 30. That is, the shape of the electrode recess 50 is substantially the same rectangular shape as the shape of the core recess 30. The electrode recess 50 extends to the edges on the positive direction X1 side and the negative direction X2 side on the surface of the base electrode layer 41 facing the first positive direction Y1. That is, the electrode recess 50 is open to the positive direction X1 side and the negative direction X2 side.

[0020] 1 , when viewed in the first negative direction Y2, a region of the external electrode 40 in which the electrode recesses 50 are present is defined as a first region A1. When viewed in the first negative direction Y2, a region adjacent to the first region A1 in the direction along the second axis Z is defined as a second region A2. That is, the second region A2, the first region A1, and the second region A2 are arranged in this order from the second positive direction Z1 toward the second negative direction Z2.

[0021] As shown in FIG. 2 , the boundary between the first region A1 and the second region A2 is defined by the edge of the electrode recess 50. The edge of the electrode recess 50 is a set of points of contact between an imaginary plane circumscribing the outer surface of the base electrode layer 41 and the base electrode layer 41 that are closest to the center of the electrode recess 50. As described above, since the electrode recess 50 has a rectangular shape when viewed in the first negative direction Y2, the first region A1 also has a rectangular shape. Furthermore, the edge of the first region A1 on the second positive direction Z1 side and the edge on the second negative direction Z2 side are parallel to the central axis X. Note that in FIGS. 1 and 2 , the imaginary boundary between the first region A1 and the second region A2 is illustrated by a dashed line.

[0022] The surface of the Sn plating layer 42 facing the first positive direction Y1 is generally flat, regardless of whether it is in the first region A1 or the second region A2. Furthermore, the surface of the Sn plating layer 42 facing the first positive direction Y1 is generally perpendicular to the first axis Y. The Sn plating layer 42 fills the interior of the electrode recess 50 without any gaps. As a result, the thickness S1 of the Sn plating layer 42 in the first region A1 is greater than the thickness S2 of the Sn plating layer 42 in the second region A2. The "thickness of the Sn plating layer 42" refers to the shortest distance from the outer surface of the Sn plating layer 42 to the outer surface of the base electrode layer 41. Furthermore, when the thickness of the Sn plating layer 42 varies within each region, if the average thickness of the Sn plating layer 42 within the first region A1 is greater than the average thickness of the Sn plating layer 42 within the second region A2, it can be said that the thickness S1 of the Sn plating layer 42 in the first region A1 is greater than the thickness S2 of the Sn plating layer 42 in the second region A2. In this embodiment, the thickness S2 of the Sn plating layer 42 within the second region A2 is approximately constant. Furthermore, in this embodiment, when viewed in the first negative direction Y2, the area of ​​the first region A1 is greater than the total area of ​​the second region A2.

[0023] <Coil Component Having Wire Wound Around Core Component> Next, a coil component 10 employing the above-described core component 100 will be described. As shown in Fig. 3, the coil component 10 includes, in addition to the core component 100, a wire 60 wound around the winding core portion 11. Although not shown, the wire 60 includes a conductor and an insulating coating. The insulating coating covers the outer surface of the conductor. When viewed in cross section perpendicular to the direction in which the wire 60 extends, the shape of the wire 60 is substantially circular.

[0024] A first end of the wire 60 is joined by thermocompression to the external electrode 40 on the first flange 21 side. A second end of the wire 60 is joined by thermocompression to the external electrode 40 on the second flange 22 side. When viewed in the negative direction X2, the wire 60 is wound around the winding core 11 so as to progress counterclockwise from the first end to the second end.

[0025] 4, the wire 60 has a joint EP. The joint EP is a portion of the wire 60 that is joined to the outer surface of the external electrode 40. Specifically, the joint EP is joined to the first region A1 of the Sn plating layer 42. Specifically, the joint EP is located within the first region A1 and does not extend into the second region A2.

[0026] The joint EP is compressed by thermocompression bonding, making its thickness along the first axis Y thinner than other portions. The dimension of the joint EP along the first axis Y is approximately 10 μm. When viewed in the first negative direction Y2, the joint EP has a generally elliptical shape. The tip of the joint EP faces in an oblique direction inclined with respect to both the central axis X and the second axis Z.

[0027] In the coil component 10, the Sn plating layer 42 has two trace portions TP. Each trace portion TP is a portion of the external electrode 40 that contains an organic component. Each trace portion TP is adjacent to the joint EP in the direction along the second axis Z. Specifically, one trace portion TP is located on the second positive direction Z1 side of the joint EP. The other trace portion TP is located on the second negative direction Z2 side of the joint EP. Note that "adjacent to the joint EP" does not necessarily mean that the trace portion TP is continuous with the joint EP; the joint EP and the trace portion TP may be located with a gap between them. Note that the trace portion TP is a portion that contains an organic component, such as a carbon component, when surface analysis is performed using a scanning electron microscope (SEM) using energy dispersive X-ray spectroscopy (EDX). As will be described later, this trace TP is formed by the insulating coating of the wire 60 melting when the wire 60 is joined, and remaining on the external electrode 40 .

[0028] As shown in Fig. 5, in this embodiment, the trace portion TP is recessed from the plane of the Sn plating layer 42 located furthest in the first positive direction Y1 toward the first negative direction Y2. The bottom of the trace portion TP does not reach the base electrode layer 41. The outer edge of the trace portion TP does not need to be clearly visible. In Figs. 3 to 5, the trace portion TP is illustrated schematically.

[0029] 4, each trace portion TP has an elliptical shape that extends longitudinally along the central axis X. Both of the two trace portions TP are located within the first region A1 when viewed in the first negative direction Y2.

[0030] When viewed in the first negative direction Y2, the area of ​​each trace portion TP is approximately half the area of ​​the joint portion EP. When viewed in the first negative direction Y2, the area of ​​the first region A1 is three times or more the area of ​​the joint portion EP.

[0031] Here, when viewed in the first negative direction Y2, an imaginary line V is drawn in the direction along the central axis X, passing through a point of the joint EP that is farthest from the winding core 11 and a point of the joint EP that is closest to the winding core 11. In the present embodiment, the point of the joint EP that is closest to the winding core 11 is a linear point of the joint EP that overlaps with the edge of the external electrode 40 on the negative direction X2 side. In this case, the midpoint of the linear point is defined as the point of the joint EP that is closest to the winding core 11. The maximum dimension H1 of the first region A1 in a direction perpendicular to the imaginary line V when viewed in the first negative direction Y2 is three or more times the maximum dimension H2 of the joint EP in the direction perpendicular to the imaginary line V when viewed in the first negative direction Y2.

[0032] <Regarding the Formation of the Trace> When joining the wire 60 to the core component 100 by thermocompression bonding, first, the end of the wire 60 is placed on the first region A1. Then, a heater tip heated to a predetermined temperature is pressed against the end of the wire 60 for a predetermined time. This compresses the end of the wire 60, forming a joint EP where the wire 60 is joined to the external electrode 40. In this process of forming the joint EP, the insulating coating melts in a portion of the wire 60 that contacts the heater tip. The molten insulating coating spreads between the heater tip and the external electrode 40, pushing aside a portion of the Sn plating layer 42. In particular, the molten insulating coating spreads in the direction along the second axis Z. The molten insulating coating also adheres to the surface of the heater tip. When the heater tip is then moved away from the core component 100, a portion of the molten insulating coating adheres to the heater tip and is removed from the external electrode 40 along with the heater tip. In this way, the trace of the spread of the molten insulating coating becomes a trace portion TP containing organic components derived from the insulating coating.

[0033] The trace portions TP are formed on both sides of the joint portion EP in the direction along the second axis Z. The trace portions TP are recessed in the first negative direction Y2 with respect to the surface of the external electrode 40 that is located closest to the first positive direction Y1. When the wire 60 is joined to the core component 100 by thermocompression bonding, the end of the wire 60 is positioned to avoid the vicinity of the end of the first region A1 in the direction along the second axis Z, so that the trace portions TP are formed within the first region A1.

[0034] Effects of the Present Embodiment (1) In the above embodiment, in the core component 100 before the wire 60 is joined, the thickness S1 of the Sn plating layer 42 in the first region A1 is greater than the thickness S2 of the Sn plating layer 42 in the second region A2. Therefore, by joining the end of the wire 60 to the first region A1, the trace TP generated during thermocompression bonding can also be contained within the first region A1. By positioning the trace TP within the first region A1, the trace TP is less likely to penetrate the Sn plating layer 42 than when the trace TP is positioned within the second region A2. Therefore, with the above configuration, exposure of the base electrode layer 41 from the Sn plating layer 42 can be suppressed.

[0035] (2) In the above embodiment, when viewed in the first negative direction Y2, the electrode recess 50 is located within the range of the core recess 30. That is, the electrode recess 50 is formed to reflect the shape of the core recess 30. Therefore, the electrode recess 50 can be formed without special processing of the base electrode layer 41, and the processing process of the core component 100 is not made complicated.

[0036] (3) In the above embodiment, when viewed in the first negative direction Y2, the area of ​​the first region A1 is three or more times the area of ​​the joint EP. The area of ​​each trace portion TP is approximately half the area of ​​the joint EP. Furthermore, the area of ​​each trace portion TP is at most approximately the area of ​​the joint EP. Therefore, if the area of ​​the first region A1 when viewed in the first negative direction Y2 is three or more times the area of ​​the joint EP, the trace portion TP can be more reliably contained within the first region A1.

[0037] (4) In the above embodiment, the maximum dimension H1 of the first region A1 in a direction perpendicular to the imaginary line V when viewed in the first negative direction Y2 is at least three times the maximum dimension H2 of the joint EP in a direction perpendicular to the imaginary line V when viewed in the first negative direction Y2. The imaginary line V can be said to be the extension direction of the joint EP on the external electrode 40. Because the trace TP is formed adjacent to the joint EP, it tends to have a shape that follows the extension direction of the joint EP. Furthermore, as described above, the trace TP tends to be formed on both sides of the joint EP in the direction along the second axis Z. Therefore, if the maximum dimension H1 of the first region A1 in a direction perpendicular to the imaginary line V when viewed in the first negative direction Y2 is at least three times the maximum dimension H2 of the joint EP in a direction perpendicular to the imaginary line V when viewed in the first negative direction Y2, the trace TP can be more reliably contained within the first region A1.

[0038] <Modifications> The above embodiment and the following modifications can be implemented in combination with each other within the scope of technical compatibility.

[0039] In the above embodiment, the configuration of the coil component 10 is not limited to the above configuration. For example, the coil component 10 may further include a plate-shaped core that spans between the first flange portion 21 and the second flange portion 22.

[0040] In the above embodiment, the shape of the winding core 11 is not limited to the example in the above embodiment. For example, the shape of the winding core 11 may be an elliptical cylinder, or a polygonal cylinder other than a rectangular cylinder. In the above embodiment, the coil device 10 may include two or more wires 60. Note that when there are two wires 60, the coil device 10 may further include two external electrodes 40.

[0041] In the above embodiment, the shape of the wire 60 is not limited to the example of the above embodiment. When viewed in a cross section perpendicular to the direction in which the wire 60 extends, the shape of the wire 60 may be an ellipse other than a circle, or a polygon.

[0042] In the above embodiment, the material of each base electrode layer 41 is not limited to the silver exemplified in the above embodiment. For example, the material of each base electrode layer 41 may be copper, nickel, or the like. Furthermore, the base electrode layer 41 may have at least one conductive layer, and may have two or more layers. Furthermore, when the base electrode layer 41 has two or more layers, at least one of a nickel layer and a copper layer may be laminated on the silver exemplified in the above embodiment, or an alloy layer with the Sn plating layer 42 (e.g., a Cu—Sn alloy layer) may be formed on the surface. Furthermore, the material of the Sn plating layer 42 is not limited to the example of the above embodiment. For example, a layer of gold may be further formed on the Sn plating layer 42.

[0043] In the above embodiment, the material of the drum-shaped core 10C is not limited to the example of the above embodiment. For example, the material of the drum-shaped core 10C is not limited to Ni-Zn ferrite, but may be Mn-Zn ferrite, etc. Furthermore, the material of the drum-shaped core 10C may be ferrite, alumina, synthetic resin, a mixture thereof, etc.

[0044] In the above embodiment, the shape of the first region A1 when viewed in the first negative direction Y2 is not limited to the example of the above embodiment. For example, in the example shown in FIG. 6 , the first region A1 is a parallelepiped. Specifically, the edge of the first region A1 on the second positive direction Z1 side and the edge on the second negative direction Z2 side are both inclined with respect to the central axis X and the second axis Z. These two edges extend generally along the imaginary straight line V of the joint EP. In other words, the end of the wire 60 is joined to the external electrode 40 while being positioned along the inclination of the edge of the first region A1. Note that in FIG. 6 , the imaginary boundary between the first region A1 and the second region A2 is illustrated by a dashed line.

[0045] In the above embodiment, the electrode recesses 50 in the first region A1 may have a step. In the example shown in FIGS. 7 to 9 , the core recesses 30 are recessed relative to the plane of the flange 20 located closest to the first positive direction Y1. As shown in FIG. 8 , the core recesses 30 can be broadly divided into a first recess 31 that is a first distance T1 from the plane of the flange 20 located closest to the first positive direction Y1, and a second recess 32 that is a second distance T2 greater than the first distance T1 from the plane of the flange 20 located closest to the first positive direction Y1. As shown in FIG. 9 , the first recess 31 is located on the positive direction X1 side of the second recess 32. The first recess 31 is located at the end of the first region A1 on the positive direction X1 side.

[0046] In the above example, as shown in Fig. 8, the base electrode layer 41 has an electrode recess 50. The electrode recess 50 is a portion of the base electrode layer 41 that covers the core recess 30. Therefore, the shape of the electrode recess 50 is substantially the same as the shape of the core recess 30. The electrode recess 50 can be broadly divided into a first electrode recess 51 that covers the first recess 31 and a second electrode recess 52 that covers the second recess 32. That is, in the above example, a step is generated between the first electrode recess 51 and the second electrode recess 52.

[0047] As shown in Fig. 7 , when viewed in the first negative direction Y2, the region of the external electrode 40 where the electrode recess 50 is present is defined as the first region A1. In the example shown in Fig. 7 , the bottom surface of the first region A1 has a step due to the step between the first electrode recess 51 and the second electrode recess 52. When viewed in the first negative direction Y2, the region adjacent to the first region A1 in the direction along the second axis Z is defined as the second region A2. The joints EP and the traces TP are located within the first region A1. Specifically, the joints EP and the traces TP are located within the first region A1 on the second electrode recess 52.

[0048] 7 , the joint EP and the trace TP are located within the first region A1 on the second electrode recess 52, making it difficult for the trace TP to penetrate the Sn plating layer 42. Furthermore, when the wire 60 is thermocompression-bonded to the external electrode 40, after the joint EP is formed, the portion of the wire 60 that protrudes beyond the joint EP in the positive direction X1 may be cut off. In such a case, the wire 60 can be easily cut off by hooking it on the step between the first electrode recess 51 and the second electrode recess 52 and pulling it.

[0049] In the above embodiment, the core component 100 does not necessarily have to have a core recess 30 as long as it has an electrode recess 50. In the example shown in Fig. 10, the surface of each flange 20 facing the first positive direction Y1 is flat. That is, the base electrode layer 41 of each external electrode 40 is in contact with a flat portion of the outer surface of the flange 20. The Sn plating layer 42 is laminated on the base electrode layer 41 on the first positive direction Y1 side.

[0050] 10 , when viewed in the first negative direction Y2, a region of the external electrode 40 where the electrode recess 50 is present is defined as a first region A1, and a region adjacent to the first region A1 in the direction along the second axis Z is defined as a second region A2. That is, the first region A1 covers a planar portion of the outer surface of the flange portion 20. In the example shown in FIG. 10 , the thickness S1 of the Sn plating layer 42 in the first region A1 is greater than the thickness S2 of the Sn plating layer 42 in the second region A2.

[0051] 10 , the electrode recesses 50 in the base electrode layer 41 can be formed, for example, by forming the base electrode layer 41 with a uniform thickness and then etching a part of the base electrode layer 41 from the outer surface side. The method for forming the electrode recesses 50 is not limited to this, and the electrode recesses 50 can also be formed by applying the base electrode layer 41 before hardening with varying thicknesses.

[0052] In the above embodiment, the maximum dimension H1 of the first region A1 in a direction perpendicular to the imaginary line V when viewed in the first negative direction Y2 may be less than three times the maximum dimension H2 of the joint EP in a direction perpendicular to the imaginary line V when viewed in the first negative direction Y2.

[0053] In the above embodiment, when viewed in the first negative direction Y2, the area of ​​the first region A1 may be less than three times the area of ​​the joint EP. In other words, as long as the trace TP is located within the first region A1 when viewed in the first negative direction Y2, the relationship between the areas of the joint EP and the first region A1 is not limited to that of the above embodiment.

[0054] In the above embodiment, the direction in which the joint EP extends is not limited to the example of the above embodiment. For example, the joint EP may extend so that the imaginary line V when viewed in the first negative direction Y2 is parallel to the central axis X. Furthermore, the joint EP may extend so that the imaginary line V when viewed in the first negative direction Y2 is parallel to the second axis Z.

[0055] In the above embodiment, it is sufficient that the core component 100 has at least one first region A1 and at least one second region A2. In the above embodiment, the core recess 30 does not have to reach the edge on the positive direction X1 side of the surface of each flange portion 20 facing the first positive direction Y1. Similarly, the electrode recess 50 does not have to reach the edge on the positive direction X1 side of the surface of each base electrode layer 41 facing the first positive direction Y1.

[0056] In the coil component 10 of the above embodiment, the Sn plating layer 42 may have at least one trace portion TP. The trace portion TP may also be adjacent to the joint portion EP in the direction along the central axis X. A trace portion TP located on the second positive direction Z1 side of the joint portion EP and a trace portion TP located on the second negative direction Z2 side of the joint portion EP may be connected by a trace portion TP located on the positive direction X1 side of the joint portion EP.

[0057] In the above embodiment, the trace portion TP may penetrate the Sn plating layer 42. Even in the case where the trace portion TP penetrates the Sn plating layer 42, the configuration of the above embodiment can reduce the area where the trace portion TP penetrates the Sn plating layer 42.

[0058] In the above embodiment, the trace portion TP does not have to be recessed in the first negative direction Y2. The trace portion TP can be identified as a location containing an organic component. The method for detecting whether or not an organic component is contained is not limited to the example of the above embodiment. Any method may be used as long as it can perform component analysis on the surface of the Sn plating layer 42 facing the first positive direction Y1.

[0059] <Supplementary Notes> The technical ideas that can be understood from the above-described embodiments and modified examples will be described. [1] A drum-shaped core having a columnar winding core and a pair of flanges connected to the winding core in a direction along the central axis of the winding core, and an external electrode covering an outer surface of the flange, wherein a specific axis perpendicular to the central axis is defined as a first axis, one of the directions along the first axis is defined as a positive direction, a direction opposite to the positive direction is defined as a negative direction, and an axis perpendicular to both the first axis and the central axis is defined as a second axis, the external electrode covers the surface of the outer surface of the flange facing the positive direction, and the external electrode is disposed on the outer surface of the flange. and a Sn plating layer laminated on the base electrode layer on the positive-direction side, wherein the base electrode layer has an electrode recess recessed toward the negative direction, and when viewed in the negative direction, a region of the external electrode where the electrode recess exists is defined as a first region, and a region adjacent to the first region in a direction along the second axis is defined as a second region, the thickness of the Sn plating layer in the first region is greater than the thickness of the Sn plating layer in the second region.

[0060] [2] A core part for a coil part described in [1], wherein the flange portion has a core recess recessed toward the negative direction, and when viewed in the negative direction, the electrode recess is located within the range of the core recess.

[0061] [3] A core part for a coil component according to [1], wherein a part of the outer surface of the flange is flat, and the first region covers the flat portion of the outer surface of the flange. [4] A core part for a coil component according to [1], comprising: a cylindrical winding core and a pair of flanges connected to the winding core in a direction along the central axis of the winding core; an external electrode covering the outer surface of the flange; and a wire wound around the winding core and joined to the external electrode, wherein when a specific axis perpendicular to the central axis is defined as a first axis, one of the directions along the first axis is defined as a positive direction, a direction opposite to the positive direction is defined as a negative direction, and an axis perpendicular to both the first axis and the central axis is defined as a second axis, the external electrode covers the surface of the outer surface of the flange facing the positive direction, and the external electrode comprises a base electrode layer in contact with the flange and a base electrode layer on the positive direction side. a Sn plating layer laminated on the base electrode layer, wherein the base electrode layer has an electrode recess recessed toward the negative direction, and when viewed in perspective in the negative direction, a region of the external electrode where the electrode recess is present is defined as a first region, and a region adjacent to the first region in a direction along the second axis is defined as a second region, the wire has a joint portion joined to the first region, and the Sn plating layer has a trace portion adjacent to the joint in a direction along the second axis and containing an organic component, and when viewed in perspective in the negative direction, the trace portion is located within the first region.

[0062] [5] The coil component according to [4], wherein when viewed in the negative direction, an area of ​​the first region is three times or more the area of ​​the joint. [6] The coil component according to [4] or [5], wherein when viewed in the negative direction, an imaginary line is drawn in a direction along the central axis, passing through a point of the joint farthest from the winding core portion and a point of the joint closest to the winding core portion, and the maximum dimension of the first region in a direction perpendicular to the imaginary line when viewed in the negative direction is three times or more the maximum dimension of the joint in the direction perpendicular to the imaginary line when viewed in the negative direction.

[0063] A1...First region A2...Second region EP...Joint portion TP...Trace portion V...Virtual straight line X...Central axis Y1...First positive direction Y2...First negative direction 10...Coil component 10C...Drum-shaped core 11...Winding core portion 20...Flange portion 40...External electrode 41...Base electrode layer 42...Sn plating layer 50...Electrode recess 60...Wire 100...Core component

Claims

1. A drum-shaped core having a columnar winding core and a pair of flanges connected to the winding core in a direction along the central axis of the winding core, and an external electrode covering the outer surface of the flange, wherein a specific axis perpendicular to the central axis is defined as a first axis, one of the directions along the first axis is defined as a positive direction, the direction opposite to the positive direction is defined as a negative direction, and an axis perpendicular to both the first axis and the central axis is defined as a second axis, the external electrode covers the surface of the outer surface of the flange facing the positive direction, the external electrode comprises a base electrode layer in contact with the outer surface of the flange, and a Sn plating layer laminated on the base electrode layer on the positive direction side, the base electrode layer has an electrode recess that is recessed toward the negative direction, when viewed in the negative direction, a region of the external electrode where the electrode recess exists is defined as a first region, and a region adjacent to the first region in a direction along the second axis is defined as a second region, A core component for a coil component, wherein the thickness of the Sn plating layer in the first region is greater than the thickness of the Sn plating layer in the second region.

2. A core component for a coil component as set forth in claim 1, wherein the flange has a core recess recessed toward the negative direction, and when viewed in the negative direction, the electrode recess is located within the range of the core recess.

3. A core component for a coil component according to claim 1, wherein a portion of the outer surface of the flange is flat, and the first region covers the flat portion of the outer surface of the flange.

4. A drum-shaped core having a columnar winding core and a pair of flanges connected to the winding core in a direction along the central axis of the winding core, an external electrode covering the outer surface of the flange, and a wire wound around the winding core and joined to the external electrode, wherein when a specific axis perpendicular to the central axis is defined as a first axis, one of the directions along the first axis is defined as a positive direction, the direction opposite to the positive direction is defined as a negative direction, and an axis perpendicular to both the first axis and the central axis is defined as a second axis, the external electrode covers the surface of the outer surface of the flange facing the positive direction, and the external electrode comprises a base electrode layer in contact with the flange, and a Sn plating layer laminated on the base electrode layer on the positive direction side, and the base electrode layer has an electrode recess recessed toward the negative direction, When viewed in the negative direction, a region of the external electrode where the electrode recess exists is defined as a first region, and a region adjacent to the first region in a direction along the second axis is defined as a second region, the wire has a joint portion joined to the first region, the Sn plating layer is adjacent to the joint portion in a direction along the second axis, and has a trace portion containing an organic component, and when viewed in the negative direction, the trace portion is located within the first region.

5. The coil component according to claim 4, wherein, when viewed in the negative direction, the area of ​​the first region is at least three times the area of ​​the joint.

6. A coil component according to claim 4 or 5, wherein when viewed in the negative direction, an imaginary line is drawn in a direction along the central axis, passing through a point of each of the joints farthest from the winding core and a point of each of the joints closest to the winding core, and the maximum dimension of each of the first regions in a direction perpendicular to the imaginary line when viewed see-through in the negative direction is three times or more the maximum dimension of each of the joints in a direction perpendicular to the imaginary line when viewed in the negative direction.

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