Coil component and method for manufacturing same

Abstract

The present invention relates to a coil component comprising: a core having a winding core part and flange parts provided at both ends of the winding core part; a wire wound around the winding core part; a base electrode layer provided to the entirety of one side surface of the flange part and a part of each of the surfaces connected to the one side surface; and a first metal layer provided so as to cover the base electrode layer. The flange part has a first main surface and a second main surface intersecting the axial direction of the winding core part, and a first, second, third, and fourth side surface connecting the first main surface and the second main surface. The first main surface is on the side closer to the winding core part than the second main surface. The first, second, third, and fourth side surfaces are adjacent in the stated order, one side surface is the first side surface, and the length of the first metal layer at a second ridge formed by the second side surface and the second main surface is greater than the length of the first metal layer in a first ridge formed by the second side surface and the first main surface.

Description

Coil component and manufacturing method thereof

[0001] The present disclosure relates to a coil component and a method for manufacturing the same.

[0002] A wire-wound coil component is known that has a core, a wire wound around the core, and an external electrode, the external electrode being provided on an end surface of a flange of the core (see Patent Document 1).The external electrode can be formed by metal plating the flange of the core (see Patent Document 2).

[0003] Japanese Utility Model Application Publication No. 6-31112 and Japanese Patent Application Publication No. 2018-98372

[0004] In conventional coil components, there is a risk of contact between the external electrodes and the wire wound around the core.

[0005] On the other hand, if the external electrode on the flange is made small in size in order to avoid contact between the external electrode and the wire wound around the core, the adhesion of the external electrode to the flange may be reduced, which may cause the external electrode itself to peel off from the flange.

[0006] An object of the present disclosure is to provide a highly reliable coil component that solves the above problems.

[0007] The present disclosure provides a core including a winding core portion and flange portions provided on both ends of the winding core portion; a wire wound around the winding core portion; a base electrode layer provided on the entire one side surface of the flange portion and on a portion of each surface connected to the one side surface; and a first metal layer provided so as to cover the base electrode layer, wherein the flange portion has a first main surface and a second main surface that intersect with the axial direction of the winding core portion, and first, second, third, and fourth side surfaces that connect the first main surface and the second main surface, the first main surface being a main surface closer to the winding core portion than the second main surface, the first, second, third, and fourth side surfaces being adjacent in this order, and the one side surface being the first side surface, A coil component is provided in which the length of the first metal layer at the second edge formed by the second side surface and the second main surface is longer than the length of the first metal layer at the first edge formed by the second side surface and the first main surface.

[0008] The present disclosure also provides a method for manufacturing a coil component, including: preparing a core having a winding core portion and flange portions provided on both ends of the winding core portion; forming a base electrode layer on one side of the flange portions; forming a first metal layer on the base electrode layer and the flange portions by barrel plating; winding a wire around the winding core portion; and electrically connecting ends of the wire to the first metal layer.

[0009] The present disclosure provides a highly reliable coil component that solves the above problems. Specifically, the coil component of the present disclosure is highly reliable in terms of both coil characteristics and adhesion between the flange portion and the external electrode.

[0010] The method for manufacturing a coil component according to the present disclosure can manufacture a highly reliable coil component that solves the above problems. More specifically, the method for manufacturing a coil component according to the present disclosure can manufacture a highly reliable coil component in terms of both coil characteristics and adhesion between the flange portion and the external electrode.

[0011] FIG. 1 is a schematic perspective view of a coil component according to an embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view of a coil component according to an embodiment of the present disclosure. FIG. 3 is a schematic partial front view of a coil component according to an embodiment of the present disclosure. FIG. 4 is a schematic partial cross-sectional view of a coil component according to an embodiment of the present disclosure. FIG. 5A is a schematic side view of a coil component according to an embodiment of the present disclosure when viewed from the second main surface side. FIG. 5B is a schematic side view of a coil component according to an embodiment of the present disclosure when viewed from the first main surface side. FIG. 6A is a schematic partial cross-sectional view of the coil component taken along line A-A in FIG. 5A. FIG. 6B is a schematic partial cross-sectional view of the coil component taken along line B-B in FIG. 5A. FIG. 7A is a schematic cross-sectional view of a coil component according to the prior art. FIG. 7B is a schematic cross-sectional view of a coil component according to the prior art. FIG. 7C is a schematic cross-sectional view of a coil component according to the prior art.

[0012] The coil component of the present disclosure will be described in more detail below. While the description will be made with reference to drawings as necessary, the various elements in the drawings are merely shown schematically and exemplarily to facilitate understanding of the coil component of the present disclosure, and the appearance and / or dimensional ratios may differ from those of the actual components.

[0013] The various numerical ranges mentioned in this specification are intended to include the lower and upper limits themselves. That is, for example, a numerical range of 1 to 10 can be interpreted as including the lower limit of "1" and the upper limit of "10."

[0014] <Coil Component> Fig. 1 is a schematic perspective view of a coil component according to an embodiment of the present disclosure, and Fig. 2 is a schematic cross-sectional view of the coil component according to an embodiment of the present disclosure.

[0015] The coil component 1 of the present disclosure comprises a core 10 having a winding core portion 11 and flange portions 12 provided on both ends of the winding core portion 11, a wire 20 wound around the winding core portion 11, a base electrode layer 33 provided on one side of the flange portion 12, and a first metal layer 31 provided on the base electrode layer 33 and the flange portion 12.

[0016] The core 10 has a winding core portion 11 and flange portions 12 provided on both ends of the winding core portion 11. The core 10 may be made of a magnetic material. Examples of the magnetic material include a sintered body containing a metal oxide such as Ni-Zn or Ni-Cu-Zn ferrite, and a molded body of a resin containing magnetic powder. The core 10 shown in FIGS. 1 and 2 is a so-called drum core, and is H-shaped overall.

[0017] The winding core 11 has a shape that extends in one direction from one end to the other end. The shape of the winding core 11 shown in Figures 1 and 2 is a rectangular parallelepiped, but it may have another shape, such as a cylindrical shape.

[0018] The flanges 12 are provided on both ends of the winding core 11. Specifically, a first flange is provided on one end of the winding core 11, and a second flange is provided on the other end of the winding core 11.

[0019] The flange portion 12 has a first main surface 12A and a second main surface 12B that intersect with the axial direction of the winding core portion 11, and a first side surface 12a, a second side surface 12b, a third side surface 12c, and a fourth side surface 12d that connect the first main surface 12A and the second main surface 12B. The first, second, third, and fourth side surfaces are adjacent in this order.

[0020] The first main surface 12A is a main surface closer to the winding core portion 11 than the second main surface 12B. As shown in FIGS. 1 and 2 , the first main surface 12A is a surface that contacts one end of the winding core portion. In one flange portion, the first main surface A and the second main surface B may face each other and be parallel to each other. When the winding core portion 11 is the center of the coil device 1, the first main surface 12A can be considered to be the inner main surface of the coil device 1. A base electrode layer 33 and a first metal layer 31 are provided on a portion of the first main surface 12A.

[0021] The second main surface 12B is a main surface that is more distal to the winding core 11 than the first main surface 12A. As shown in Figures 1 and 2, the second main surface 12B is a surface that does not contact one end of the winding core. If the winding core 11 is the center of the coil device 1, the second main surface 12B can be considered to be the outer main surface of the coil device 1. A base electrode layer 33 and a first metal layer 31 are provided on a part of the second main surface 12B.

[0022] The first side surface 12a may be parallel to the third side surface 12c. The first side surface 12a is the side surface on which the base electrode layer 33 is provided over the entire surface. As shown in Fig. 2, the first side surface 12a is the side surface on which one end 21 (or the other end 22) of the wire 20 is provided. In other words, the first side surface 12a faces the mounting surface of a substrate or the like and is the side surface that will be coupled to the mounting surface of the substrate or the like by solder or the like.

[0023] The second side surface 12b is a side surface that extends in a direction intersecting the first side surface 12a, the third side surface 12c, the first main surface 12A, and the second main surface 12B. It is a side surface that is connected to the first side surface 12a. The first to fourth side surfaces are adjacent to each other in this order, and in the example shown in Figures 1 and 2, the second side surface 12b is the side surface located on the near side. As shown in Figure 2, a base electrode layer 33 is provided on a portion of the second side surface 12b.

[0024] The third side surface 12c is a surface facing the first side surface 12a. The third side surface 12c and the first side surface 12a may be parallel to each other.

[0025] The fourth side surface 12 d is a surface facing the second side surface 12 b. In the side views of the coil component shown in Figures 5A and 5B, the second side surface 12 b and the fourth side surface 12 d may be parallel to each other. A base electrode layer 33 is provided on a part of the fourth side surface 12 d.

[0026] In this disclosure, when simply referring to a "collar portion," it refers to each of the first and second collar portions. For example, the first main surface of the collar portion includes the first main surface of the first collar portion and the first main surface of the second collar portion.

[0027] As shown in FIG. 1 , the flange 12 has a ridge formed between two surfaces. In the present disclosure, a ridge refers to the boundary between two surfaces that are connected at an angle to each other. In other words, a ridge can be considered as the portion where two surfaces intersect. For example, the flange 12 has a first ridge Ab formed by the first main surface 12A and the second side surface 12b. Also, as shown in FIG. 1 , the flange 12 has a second ridge 12Bb formed by the second main surface B and the second side surface b. Each of the first ridge Ab and the second ridge Bb extends in one direction in FIG. 1 . Furthermore, the first ridge Ab and the second ridge Bb may extend parallel to each other.

[0028] The wire 20 is wound around the winding core 11. The wire 20 is wound spirally as a whole with the axial direction of the winding core 11 as the central winding axis. As shown in FIG. 2 , one end 21 and the other end 22 of the wire 20 are each connected to an external electrode 30. The wire 20 may be made of copper, silver, gold, or an alloy thereof. The wire 20 may be coated with a resin, such as polyurethane, polyamideimide, or polypolyesterimide.

[0029] The base electrode layer 33 is provided on the flange 12. As shown in Fig. 2, the base electrode layer 33 is provided on the first side surface 12a of the flange and on a part of the surrounding surface connected to the first side surface 12a. Here, the surrounding surface connected to the first side surface 12a means the first main surface 12A, the second main surface 12B, the second side surface 12b, and the fourth side surface 12d, as shown in Fig. 2.

[0030] The base electrode layer 33 is provided over the entire first side surface 12 a. The base electrode layer 33 may completely cover the entire first side surface 12 a. The base electrode layer 33 may form a pattern over the entire first side surface 12 a.

[0031] In the cross-sectional view shown in Fig. 2, the base electrode layer 33 provided on a part of the surrounding surface connected to the first side surface 12a is connected to the base electrode layer 33 provided on the first side surface 12a. The base electrode layers 33 provided on each of the surrounding surfaces connected to the first side surface 12a are also connected to each other. By providing the base electrode layer 33 in this manner, the base electrode layer 33 is formed in a U-shape (or C-shape or U-shape) as shown in Fig. 2.

[0032] The base electrode layer may be made of a metal such as Au, Ag, Cu, or an alloy thereof. The base electrode layer may be a sintered body. For example, the base electrode layer may be a sintered body formed by baking a conductive paste such as an Ag glass paste applied by a dip method.

[0033] The first metal layer 31 is directly applied to the base electrode layer 33 and the flange 12. As shown in FIG. 2, the first metal layer 31 is provided on the first side surface 12a of the flange and on a portion of the surrounding surface connected to the first side surface 12a. Here, the surrounding surface connected to the first side surface 12a refers to the first main surface 12A, the second main surface 12B, the second side surface 12b, and the fourth side surface 12d. The first metal layer 31 forms the external electrode 30 together with the base electrode layer 33. The first metal layer 31 may be a metal layer formed by plating. Sn can be used as the material for the first metal layer 31.

[0034] The first metal layer 31 provided on a part of the surrounding surface connected to the first side surface 12 a is connected to the first metal layer 31 provided on the first side surface 12 a. In addition, the first metal layers 31 provided on each of the surrounding surfaces connected to the first side surface 12 a are also connected to each other.

[0035] In terms of configuration, the first metal layer 31 is provided so as to cover the base electrode layer 33 provided on the flange 12. In other words, the first metal layer 31 is provided so as to cover both the flange 12 and the base electrode layer 33. The first metal layer 31 may completely cover the base electrode layer 33 provided on the flange 12. The first metal layer 31 may partially cover the base electrode layer 33 provided on the flange 12. The first metal layer 31 may not partially cover the first side surface 12a, and may not partially cover the surrounding surface connected to the first side surface 12a.

[0036] In one embodiment, a second metal layer may be provided between the first metal layer and the underlying electrode layer, and the second metal layer may form an external electrode together with the first metal layer and the underlying electrode layer.

[0037] The second metal layer may be provided on the first side surface of the flange and on a portion of the surrounding surface connected to the first side surface. The second metal layer provided on the portion of the surrounding surface connected to the first side surface may be connected to the second metal layer provided on the first side surface. Furthermore, the second metal layers provided on each of the surrounding surfaces connected to the first side surface may also be connected to each other.

[0038] The second metal layer may be provided so as to cover the base electrode layer provided on the flange portion. In other words, the second metal layer may be provided so as to cover both the flange portion and the base electrode layer. The second metal layer may completely cover the base electrode layer provided on the flange portion. The second metal layer may partially cover the base electrode layer provided on the flange portion 12. The second metal layer may not partially cover the first side surface, and may not partially cover the surrounding surface connected to the first side surface 12a.

[0039] The second metal layer may be a metal layer formed by plating, and may be made of Ni or Cu.

[0040] In one embodiment, a second metal layer and a third metal layer may be provided between the first metal layer and the base electrode layer. The first metal layer, the second metal layer, and the third metal layer may be provided in this order on the flange portion. The first metal layer is a metal layer exposed to the outside, and the third metal layer is a metal layer provided so as to be in direct contact with the base electrode layer. The second metal layer and the third metal layer, together with the first metal layer and the base electrode layer, can form an external electrode.

[0041] The third metal layer is provided between the base electrode layer and the second metal layer. The third metal layer may be provided on the flange and the base electrode layer in the same manner as the second metal layer described above. The second metal layer may have the same configuration as the second metal layer described above.

[0042] The third metal layer may be a metal layer formed by plating. The third metal layer may be made of Ni and Cu. The second metal layer may be made of Ni and Cu.

[0043] The coil component of the present disclosure has the following features in the above configuration.

[0044] In the coil component of the present disclosure, the length of the first metal layer at the second edge formed by the second side surface and the second main surface is longer than the length of the first metal layer at the first edge formed by the second side surface and the first main surface. As shown in Figures 1 and 2, the vertical length from the first side surface 12a of the flange 12 to the tip portion 31P of the first metal layer 31 at the second edge 12Bb is longer than the vertical length from the first side surface 12a of the flange 12 to the tip portion 31P of the first metal layer 31 at the first edge 12Ab. In other words, the first metal layer 31 at the second edge 12Bb extends further toward the third side surface 12c than the first metal layer 31 at the first edge 12Ab.

[0045] By making the length of the first metal layer at the second ridge longer than the length of the first metal layer at the first ridge, it is possible to address both the deterioration of coil characteristics and the deterioration of adhesion strength between the flange portion and the external electrode.

[0046] A conventional coil component is shown in FIGS. 7A and 7B . As shown in FIG. 7A , there was a risk that the external electrode 30′ provided on the flange 12′ would come into contact with the wire 20′ wound around the winding core 11′, resulting in a deterioration in coil characteristics. For example, when the external electrode 30′ is fabricated by forming a metal layer on a base electrode layer by plating, the metal layer may also be formed in areas of the flange other than the base electrode layer. In other words, plating is likely to result in protruding portions 31X′ of the metal layer. In particular, when a metal layer is provided over a wide area of ​​the flange 12′ in order to improve adhesion between the flange 12′ and the metal layer, protruding portions 31X′ of the metal layer are likely to occur. If the protruding portions 31X′ of the metal layer come into contact with the wire 20′, the coil characteristics may be reduced.

[0047] On the other hand, if the external electrode 30' is formed small on the flange 12' as shown in Fig. 7B from the viewpoint of making it difficult for the external electrode 30' to come into contact with the wire 20' wound around the winding core 11', the adhesion of the external electrode 30' to the flange 12' is likely to be weak. If the adhesion of the external electrode 30' to the flange 12' is weak, there is a risk that the external electrode 30' itself will peel off from the flange.

[0048] In the coil component of the present disclosure, the length of the first metal layer at the second ridge 12Bb is increased, thereby increasing the area where the first metal layer and the flange are in close contact with each other. The increased contact area between the first metal layer and the flange can increase the adhesion strength. As shown in FIGS. 1 and 2 , the first metal layer 31 at the second ridge 12Bb is spaced apart from the wire 20 wound around the winding core 11. Therefore, even if the length of the first metal layer 31 at the second ridge 12Bb is increased to increase the contact area, the first metal layer 31 and the wound wire 20 are less likely to come into contact with each other.

[0049] Adjusting the formation area of ​​the first metal layer 31 on the first main surface 12A so that the first metal layer 31 and the wire 20 wound around the winding core 11 are less likely to come into contact with each other can change the adhesion strength between the first metal layer 31 and the flange 12. For example, forming the first metal layer 31 away from the wire 20 reduces the formation area of ​​the first metal layer 31, which can reduce the adhesion strength between the first metal layer 31 and the flange 12. On the other hand, in the coil component disclosed herein, as described above, the first metal layer 31 at the second ridge makes it easy to increase the adhesion strength between the first metal layer 31 and the flange 12. Therefore, it is easy to form a first metal layer that improves the adhesion strength between the first metal layer 31 and the flange 12 and separates the wire 20 and the first metal layer so that they are less likely to come into contact with each other.

[0050] 3 , when the flange portion 12 of the coil component is viewed from the front, the length L2 of the first metal layer at the second edge 12Bb is longer than the length L1 of the first metal layer at the first edge 12Ab. When measuring the lengths L1 and L2 of the first metal layer, the surface 31S of the first metal layer on the first side surface is used as the reference plane for the lengths. In other words, the lengths L1 and L2 of the first metal layer can be obtained by measuring the distance from the surface 31S of the first metal layer to the tip portions 31P of the first metal layer at the first edge 12Ab and the second edge 12Bb.

[0051] Note that when the flange portion 12 of the coil component is viewed from the front direction, it means when the second side surface is viewed from the extension direction of the first main surface 12A, the second main surface 12A, the first side surface 12a, and the third side surface 12c, as shown in Figure 3.

[0052] The lengths L1 and L2 of the first metal layer at the first edge 12Ab and the second edge 12Bb, respectively, can be measured by observing the flange portion 12 of the coil component from the front direction using a microscope, as shown in Fig. 3. Specifically, in an image magnified and observed using the microscope, the lengths L1 and L2 can be obtained by measuring the perpendicular lengths from the surface 31S of the first metal layer provided on the first side surface 12a to the ends of the first metal layer at the first edge 12Ab and the second edge 12Bb.

[0053] The length L2 of the first metal layer at the second ridge may be 10% to 300% longer than the length L1 of the first metal layer at the first ridge. From the viewpoint of increasing the adhesive strength between the first metal layer and the base electrode layer, the length L2 of the first metal layer at the second ridge may be preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, and particularly preferably 50% or more longer than the length L1 of the first metal layer at the first ridge. From the viewpoint of manufacturing efficiency of the coil component, the length L2 of the first metal layer at the second ridge may be preferably 200% or less, more preferably 150% or less, even more preferably 100% or less, and particularly preferably 70% or less longer than the length L1 of the first metal layer at the first ridge.

[0054] 1 and 2, an edge portion 31A that defines the outline of the first metal layer 31 exists on the peripheral surface that is connected to the first side surface 12a. The edge portion 31A of the first metal layer surrounds the flange portion 12.

[0055] The edge portion 31A of the first metal layer has a non-linear shape. Specifically, the shape of the edge portion 31A of the first metal layer is irregular, wavy, sawtooth, or a combination thereof. The shape of the edge portion 31A of the first metal layer is a shape resulting from the manufacturing method of the coil component of the present disclosure, which will be described later.

[0056] In one embodiment, in the coil component 1 of the present disclosure, the thickness of the first metal layer 31 at the edge 31A on the surrounding surface connected to the first side surface 12a may be thinner than the thickness of the first metal layer 31 at the end of the surrounding surface connected to the first side surface 12a. As shown in the cross-sectional view of Fig. 4, the thickness T2 of the first metal layer at the edge 31A on the surrounding surface connected to the first side surface 12a is thinner than the thickness T1 of the first metal layer at the end of the surrounding surface connected to the first side surface 12a.

[0057] The end of the surrounding surface connected to the first side surface 12a refers to the portion where the surrounding surface begins to curve or bend. As an example, in FIG. 4, the first main surface 12B connected to the first side surface 12a begins to curve at a curvature start portion 120A. The portion where the curvature begins is the end of the first main surface 12B. Note that the end of the surrounding surface connected to the first side surface 12a refers to the curvature start portion (or bent portion) that is proximal to and along the connecting portion. Furthermore, the surrounding surface connected to the first side surface 12a may be one or more surfaces selected from the group consisting of the first main surface 12A, the second main surface 12B, the second side surface 12b, and the fourth side surface 12d.

[0058] When measuring the thicknesses T1 and T2 of the first metal layer, the reference surface for the thickness is the peripheral surface connected to the first side surface 12 a. That is, the thicknesses T1 and T2 of the first metal layer can be obtained by measuring the thickness of the edge portion 31A and the thickness of the end portion of the first metal layer on the peripheral surface connected to the first side surface 12 a.

[0059] From the viewpoint of making it difficult for cracks to occur in the flange portion 12, the thickness T2 of the first metal layer may be thinner than the thickness T1 of the first metal layer by 5% or more, preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more. From the viewpoint of improving the adhesive strength of the first metal layer, the thickness T2 of the first metal layer may be thinner than the thickness T1 of the first metal layer by 50% or less, preferably 45% or less, more preferably 40% or less, and even more preferably 35% or less.

[0060] In one embodiment, the thickness of the first metal layer may be gradually reduced from the end of the peripheral surface connected to the first side surface toward the edge of the first metal layer. As shown in FIG. 4 , the thickness of the first metal layer on the second main surface and / or the first main surface is gradually reduced from the first side surface toward the third side surface. In other words, the first metal layer on the second main surface may have a tapered shape. Similarly, the first metal layer on the first main surface may have a tapered shape. In one aspect, the thickness of the first metal layer may be gradually reduced from the end of the peripheral surface connected to the first side surface toward the edge of the first metal layer.

[0061] 3, the thickness of the first metal layer is relatively thick on the first side surface 12a side and relatively thin on the edge side of the first metal layer, so that the appearance of the flange portion 12 on the first side surface 12a side is generally tapered from the first side surface to the third side surface. In other words, the first metal layer may be provided on the base metal layer so as to form a taper that tapers from the first side surface to the third side surface.

[0062] In one embodiment, among the surrounding surfaces connected to the first side surface 12a, the edge 31A of the first metal layer on the second main surface 12B may be located closer to the third side surface 12c than the edge 31A of the first metal layer on the first main surface 12A. In FIGS. 1 to 4, the edge 31A of the first metal layer is located on both the first main surface 12A and the second main surface 12B. Comparing the side view of FIG. 5A, which is viewed from the second main surface side, with the side view of FIG. 5B, which is viewed from the first main surface side, the edge 31A of the first metal layer on the second main surface 12B shown in FIG. 5A is located closer to the third side surface 12c as a whole than the edge 31A of the first metal layer on the first main surface 12A. In the above configuration, the area of ​​the metal layer covering the second main surface is larger than the area of ​​the metal layer covering the first main surface.

[0063] By adopting the above configuration, it becomes more difficult for the first metal layer 31 and the wire 20 wound around the winding core 11 to come into contact with each other on the first main surface 12A side. Furthermore, on the second main surface 12B side, the area where the first metal layer 31 is in close contact with the second main surface 12B is expanded, which can further improve the adhesion strength of the first metal layer 31. Therefore, reliability is likely to be improved in terms of both the coil characteristics and the adhesion with the flange and the external electrode.

[0064] In the coil component of the present disclosure, a gap may be provided between at least a portion of the edge of the first metal layer and the flange portion. Figures 6A and 6B show cross-sectional views of the edge portion 31A of the first metal layer taken along lines A-A and B-B in Figure 5A. In Figure 6A, the flange portion 12 and the edge portion 31A of the first metal layer are in direct contact with each other.

[0065] 6B , the flange 12 and the edge 31A of the first metal layer are not in direct contact with each other, with a gap 40 provided between them. In other words, the edge 31A of the first metal layer is spaced apart from the flange 12. The edge 31A of the first metal layer is also thinner than the thickness of the first metal layer 31 that is in contact with the flange 12. In other words, the edge 31A of the first metal layer can be considered to be thin and floating.

[0066] In the conventional coil component shown in FIG. 7C , the edge of the first metal layer contacts the flange 12′ as shown in FIG. 6A . The edge of the first metal layer and the flange 12′ are in close contact with each other. Of the portions of the flange 12′ that are in close contact with the external electrode 30′, cracks 50′ are likely to occur in the portions of the flange 12′ that are in close contact with the edge of the external electrode 30′. Specifically, the external electrode 30′ itself applies stress to the flange 12′, and stress is more likely to concentrate at the edge of the external electrode 30′. For example, if the coil is deformed due to bending of the coil when mounted, stress may concentrate at the edge of the external electrode 30′, causing cracks 50′ in the flange.

[0067] In the coil component of the present disclosure, a gap may be provided between at least a portion of the edge of the first metal layer and the flange portion. In such an embodiment, the space between at least a portion of the edge of the first metal layer and the flange portion relieves stress applied from the edge of the first metal layer to the flange portion, making it easier to suppress cracks from occurring in the flange portion.

[0068] In the coil component of the present disclosure, it is not necessary to provide gaps in all of the edges of the first metal layer, but rather it is sufficient that gaps are provided between at least some of the edges of the first metal layer and the flange. In other words, the edge 31A of the first metal layer surrounding the flange 12 may have both a configuration in which the flange 12 and the edge 31A of the first metal layer are in contact with each other as shown in Fig. 6A and a configuration in which the flange 12 and the edge 31A of the first metal layer are separated from each other as shown in Fig. 6B. If a gap is provided between at least a portion of the edge 31A of the first metal layer and the flange 12, cracks are less likely to occur in the flange.

[0069] The presence or absence of a gap between the edge of the first metal layer and the flange can be confirmed by observing the edge of the first metal layer under magnification using a scanning electron microscope (SEM) or the like.

[0070] In one embodiment, the surface of the first metal layer may be smooth. In particular, the edge of the first metal layer may be smooth. The smooth surface of the first metal layer means that there are portions on the surface of the first metal layer with fewer irregularities. For example, the surface of the first metal layer may have fewer protrusions and depressions than the surface of the flange. When the surface of the first metal layer is smooth, the wettability of the solder is likely to be improved. Furthermore, when mounting the coil component on a substrate, the smooth surface of the first metal layer makes it easier to stably place it on the surface of the substrate, etc., and therefore, mounting stability is likely to be improved.

[0071] The surface smoothness of the first metal layer can be measured by observing the surface of the first metal layer using a laser microscope, a scanning probe microscope (SPM), etc. In the case of a laser microscope or an SPM, the surface of the first metal layer is observed in an area of ​​10 μm square to calculate Sa, and if Sa is 1 μm or less, it is considered to be smooth.

[0072] The smooth surface of the first metal layer is also a feature resulting from the manufacturing method of the coil component of the present disclosure. In the manufacturing method of the coil component of the present disclosure, which will be described in detail below, the first metal layer is formed on the base electrode layer and the flange portion by barrel plating. During barrel plating, the first metal layer of the coil component being stirred in the barrel and the media or the like collide with each other, and the first metal layer may be struck by the media or the like. By being struck by the media or the like, the surface of the first metal layer is leveled and becomes smooth.

[0073] In one embodiment, among the edges of the first metal layer, the edge of the first metal layer at the second ridge may be the furthest from the first side surface. As shown in FIGS. 1 to 5 , the edge 31A of the first metal layer is positioned so as to go around the flange 12, and the edge 31A of the first metal layer at the second ridge 12Bb is the furthest from the first side surface 12a. By adopting the above configuration, the area where the first metal layer and the flange 12 are in close contact with each other at the second ridge 12Bb is increased, which can further strengthen the adhesion between the first metal layer 31 and the flange 12. This feature is also a feature that relies on the manufacturing method of the coil component 1 of the present disclosure.

[0074] From the viewpoint of improving the adhesion strength of the first metal layer, as shown in Fig. 3, the length L2 of the edge portion of the first metal layer at the second ridge 12Bb may be 20% or more, preferably 25% or more, more preferably 30% or more, and even more preferably 35% or more of the length L3 from the surface 31S of the first metal layer to the third side surface 12c. From the viewpoint of the manufacturing efficiency of the coil component, the length L2 of the edge portion of the first metal layer at the second ridge 12Bb may be 80% or less, preferably 75% or less, more preferably 70% or less, and even more preferably 65% ​​or less of the length L3 from the surface 31S of the first metal layer to the third side surface 12c.

[0075] A method for manufacturing a coil component according to an embodiment of the present disclosure will be described below.

[0076] The method for manufacturing a coil component according to the present disclosure includes carrying out a core preparation step, a base electrode layer formation step, a first metal layer formation step, and a coil formation step in this order.

[0077] Specifically, the manufacturing method of the coil component of the present disclosure includes: preparing a core having a winding core portion and flange portions provided on both ends of the winding core portion; forming a base electrode layer on one side of the flange portions; forming a first metal layer on the base electrode layer and the flange portions by barrel plating; winding a wire around the winding core portion; and electrically connecting ends of the wire to the first metal layer.

[0078] The manufacturing method of the coil component of the present disclosure may further include, after the base electrode layer forming step and before the first metal layer forming step, the following second metal layer forming step: forming a second metal layer on the base electrode layer and the flange portion by barrel plating.

[0079] The manufacturing method of the coil component of the present disclosure may further include, after the base electrode layer forming step and before the first metal layer forming step, the following third metal layer forming step: forming a third metal layer on the base electrode layer and the flange portion by barrel plating, and then forming a second metal layer.

[0080] [Core Preparation Step] In the core preparation step, a core is prepared. For example, the core may be formed by a step of compressing a core material using a mold to form a compact, and a step of firing the compact. This allows the preparation of a core having a winding core portion and flange portions provided on both ends of the winding core portion.

[0081] [Base Electrode Layer Forming Process] In the base electrode layer forming process, a base electrode layer is formed on the flange portion of the core. Specifically, the base electrode layer is formed over the entire one side surface of the flange portion. The base electrode layer is formed, for example, by dipping one side surface of the flange portion with a conductive paste using a dip coating method and baking the coating film. The conductive paste contains, for example, glass (or silica), a conductive powder, and a resin component. The conductive powder is, for example, Ag powder. The dip coating method can be performed using a known dip coating device or the like.

[0082] When the base electrode layer is formed over the entire one side surface of the flange, the base electrode layer may also be formed on the surface connected to the one side surface on which the base electrode layer is provided. In particular, in the dip coating method, the flange is immersed in the conductive paste, so that the one side surface of the flange and a portion of the surface connected to the one side surface of the flange can also be immersed in the conductive paste. Therefore, by subsequent baking, the base electrode layer can also be formed on the portion of the surface connected to the one side surface of the flange.

[0083] [First Metal Layer Forming Process] In the first metal layer forming process, a first metal layer is formed on the base electrode layer and the flange portion. The first metal layer is formed by barrel plating. In barrel plating, a barrel containing a core after the base electrode layer has been formed is immersed in an electrolyte, and the first metal layer is formed on the base electrode layer and the flange portion by plating while rotating the barrel. From the viewpoint of efficiently forming the first metal layer, by storing multiple cores in the barrel, the first metal layer can be formed on the flange portions of multiple cores at once. Sn can be used as the first metal layer.

[0084] In the coil component manufacturing method of the present disclosure, the first metal layer is formed by barrel plating, so that the coil component has a characteristic appearance. Specifically, as described above, in the coil component obtained by the coil component manufacturing method of the present disclosure, the length of the first metal layer at the second edge formed by the second side surface and the second main surface is longer than the length of the first metal layer at the first edge formed by the second side surface and the first main surface.

[0085] The length of the first metal layer at the second edge is longer than the length of the first metal layer at the first edge because an external force is applied to the first metal layer formed on the flange of the core during barrel plating. During barrel plating, the cores in the barrel are stirred while the barrel is rotating. The cores in the barrel come into contact with the barrel and / or other cores housed in the barrel. This contact applies an external force to the first metal layer formed on the flange of the core, and the first metal can be stretched by the external force.

[0086] Here, when the core is stirred by barrel rotation, the second main surface, which is on the outer side of the flange, is more likely to come into contact with the barrel and / or other cores than the first main surface, which is on the inner side of the flange. As shown in Figures 1 and 2 , the first main surface 12A of the flange 12 is positioned so that it is less likely to come into contact with the barrel and / or other cores due to the presence of the winding core 11 and the other flange 12. Therefore, the first metal layer 31 provided on the second main surface 12B is subjected to an external force during barrel plating and may be stretched more than the first metal layer 31 provided on the first main surface 12A. For the above reasons, in the coil component 1 of the present disclosure, the length of the first metal layer at the second ridge is longer than the length of the first metal layer at the first ridge.

[0087] When the first metal layer is stretched by an external force, a portion of the first metal layer may be stretched away from the flange. For example, when an impact is applied to the first metal layer, the impact may cause the edge of the first metal layer to spread apart without contacting the flange. This phenomenon may result in a gap between the edge of the first metal layer and the flange, as shown in FIG. 6B .

[0088] During barrel plating, current tends to concentrate on the first edge 12Ab and the second edge 12Bb of the flange 12, accelerating plating. In other words, the first metal layer 31 is more likely to be formed on the first edge 12Ab and the second edge 12Bb than on other parts of the flange. Therefore, in the manufacturing method of a coil component according to the present disclosure, the first metal layer formed on the flange can be formed longer on the first edge 12Ab and the second edge 12Bb than on other parts of the flange.

[0089] In one embodiment, the first metal layer may be formed using media during barrel plating. That is, media may be housed in the barrel together with the core, and barrel plating may be performed. By using media, the media comes into contact with the first metal layer formed on the flange portion during barrel plating, making it easier to elongate the first metal layer. In other words, the first metal layer formed on the flange portion is hammered by the media during barrel plating, making it easier to elongate the first metal layer.

[0090] From the viewpoint of making it easier to extend the first metal layer at the second edge, it is preferable that the media be harder than the first metal layer. From the same viewpoint, it is preferable that the media be denser than the first metal layer. By adopting the above-mentioned embodiment, it becomes easier to apply a stronger external force to the first metal layer during barrel plating, and the first metal layer can be further extended. From the same viewpoint, it is preferable to increase the rotation speed of the barrel to increase the opportunities for contact between the first metal layer and the media.

[0091] From the viewpoint of making it easier to extend the first metal layer at the second ridge, it is preferable that the media be larger than the core. By using media larger than the core, the media are less likely to come into contact with the first main surface of the flange, making it easier to prevent the first metal layer at the first ridge from becoming longer.

[0092] [Second Metal Layer Forming Step] In one embodiment, the following second metal layer forming step may be included after the base electrode layer forming step and before the first metal layer forming step. Specifically, the second metal layer may be formed on the base electrode layer and the flange portion by barrel plating. The second metal layer may be formed by the same method as the first metal layer. Ni or Cu may be used as the second metal layer.

[0093] In one embodiment, the method may further include a third metal layer forming step and a second metal layer forming step after the base electrode layer forming step and before the first metal layer forming step. Specifically, after the base electrode layer forming step and before the first metal layer forming step, the third metal layer may be formed on the base electrode layer and the flange portion by barrel plating, and then the second metal layer may be formed. In other words, the third metal layer, the second metal layer, and the first metal layer may be formed in this order on the base electrode layer and the flange portion by barrel plating. The second metal layer and the third metal layer may be formed by the same method as the first metal layer. Ni and Cu may be used for the third metal layer. Ni or Cu may be used for the second metal layer.

[0094] [Coil Forming Process] In the coil forming process, the wire is wound around the winding core, and the end of the wire is electrically connected to the first metal layer. The electrical connection between the first metal layer and the end of the wire may be achieved by thermocompression bonding or the like.

[0095] Through the above steps, the coil component according to the present disclosure can be manufactured.

[0096] In the method for manufacturing a coil component according to the present disclosure, by adjusting the barrel plating conditions in the first metal layer forming step, it becomes easier to adjust the area in which the first metal layer is formed on the base electrode layer and the flange portion.

[0097] In the past, an insulator layer or the like was sometimes provided on a portion of the base electrode layer or the flange portion to control the formation area of ​​the first metal layer. Because a metal layer is difficult to plate on such an insulator layer, it becomes easier to prevent the metal layer from being formed in unintended locations on the flange portion. However, a step of providing the insulator layer is required, and the increased number of manufacturing steps tends to increase the manufacturing costs of the coil component. The manufacturing method of the coil component disclosed herein does not require the provision of an insulator layer or the like, making it easier to control the formation area of ​​the first metal layer and suppress increases in manufacturing costs.

[0098] Another method for controlling the area where the metal layer is formed is to modify the surface of the flange by laser irradiation and then metal-plating the modified surface. Because metal plating is more easily formed on the modified surface, it becomes easier to control the shape of the external electrode that is formed, but the strength of the laser-irradiated area decreases and cracks are more likely to occur.

[0099] Furthermore, since the adhesion between the modified surface and the metal plating tends to be strong, the flange that is in close contact with the edge of the plating is more susceptible to stress concentration and more likely to develop cracks.The manufacturing method of the coil component disclosed herein does not require modification of the flange surface, and can prevent cracks from developing on the flange surface due to modification.

[0100] The coil component and the manufacturing method thereof according to the present disclosure have been described above, but they are merely typical examples. Therefore, those skilled in the art will easily understand that the coil component and the manufacturing method thereof according to the present disclosure are not limited to these, and that various embodiments are possible.

[0101] The coil component and its manufacturing method according to the present disclosure are as follows: <1> A core having a winding core portion and flange portions provided on both ends of the winding core portion, a wire wound around the winding core portion, a base electrode layer provided on the entire one side surface of the flange portion and on a portion of each surface connected to the one side surface, and a first metal layer provided so as to cover the base electrode layer, wherein the flange portion has a first main surface and a second main surface that intersect with the axial direction of the winding core portion, and first, second, third, and fourth side surfaces that connect the first main surface and the second main surface, the first main surface being a main surface closer to the winding core portion than the second main surface, the first, second, third, and fourth side surfaces being adjacent in this order, and the one side surface being the first side surface, A coil component in which the length of the first metal layer at a second ridge formed by the second side surface and the second main surface is longer than the length of the first metal layer at a first ridge formed by the second side surface and the first main surface. <2> The coil component described in <1>, in which the first metal layer at the second ridge extends further toward the third side surface than the first metal layer at the first ridge. <3> The coil component described in <1> or <2>, in which the length of the first metal layer at the second ridge is 10% to 300% longer than the length of the first metal layer at the first ridge. <4> The coil component described in any one of <1> to <3>, in which an edge of the first metal layer is present on a peripheral surface connected to the first side surface, and in which the thickness of the first metal layer at the edge on the peripheral surface connected to the first side surface is thinner than the thickness of the first metal layer at an end of the peripheral surface connected to the first side surface. <5> The coil component according to claim 4, wherein the thickness of the first metal layer gradually decreases from the end of the first side surface toward the edge of the first metal layer. <6> The coil component according to <4>, wherein, on a peripheral surface connected to the first side surface, the edge of the first metal layer on the second main surface is located closer to the third side surface than the edge of the first metal layer on the first main surface. <7> The coil component according to <4>, wherein a gap is provided between at least a part of the edge of the first metal layer and the flange. <8> The coil component according to <4>, wherein the surface of the first metal layer at the edge is smooth.<9> The coil component according to <4>, wherein, among the edge portions of the first metal layer, the edge portion of the first metal layer at the second ridge is farthest from the first side surface. <10> The coil component according to any one of <1> to <9>, wherein a second metal layer is provided between the base electrode layer and the first metal layer. <11> The coil component according to <10>, wherein a third metal layer is provided between the base electrode layer and the second metal layer. <12> A method for manufacturing a coil component, comprising: preparing a core having a winding core portion and flange portions provided on both ends of the winding core portion; forming a base electrode layer on one side of the flange portions; forming a first metal layer on the base electrode layer and the flange portions by barrel plating; winding a wire around the winding core portion; and electrically connecting an end of the wire to the first metal layer. <13> The method for manufacturing a coil component according to <12>, wherein the first metal layer is formed using a media during the barrel plating.

[0102] The coil components of the present disclosure can be used in a wide variety of applications, such as the electrical, information, and communications fields where electrical and electronic devices are used, household and small-scale industrial applications, large-scale industrial applications, the transportation systems field, power system applications, medical applications, the IoT field, and space and deep-sea applications.

[0103] DESCRIPTION OF SYMBOLS 1 Coil component 10 Core 11, 11' Winding core portion 12, 12' Flange portion 12A First main surface 12Ab First ridge 120A Curve start portion 12B Second main surface 12Bb Second ridge 12a First side surface 12b Second side surface 12c Third side surface 12d Fourth side surface 20, 20' Wire 30, 30' External electrode 31 First metal layer 31A Edge portion of first metal layer 31S Surface of first metal layer 31P Tip portion of first metal layer 31X' Protruding portion of metal layer 33 Base electrode layer 40 Gap 50' Crack L1 Length of first metal layer at first ridge L2 Length of first metal layer at second ridge L3 Length from surface of first metal layer to third side surface

Claims

1. A core having a winding core portion and flange portions provided on both ends of the winding core portion; a wire wound around the winding core portion; a base electrode layer provided on the entirety of one side surface of the flange portion and on a portion of each surface connected to the one side surface; and a first metal layer provided so as to cover the base electrode layer, wherein the flange portion has a first main surface and a second main surface that intersect in the axial direction of the winding core portion, and first, second, third, and fourth side surfaces that connect the first main surface and the second main surface, wherein the first main surface is a main surface closer to the winding core portion than the second main surface, and the first, second, third, and fourth side surfaces are adjacent in this order, and the one side surface is the first side surface, A coil component, wherein a length of the first metal layer at a second edge formed by the second side surface and the second main surface is longer than a length of the first metal layer at a first edge formed by the second side surface and the first main surface.

2. A coil component as described in claim 1, wherein the first metal layer at the second edge extends further toward the third side surface than the first metal layer at the first edge.

3. A coil component as described in claim 1 or 2, wherein the length of said first metal layer at said second ridge is greater than or equal to 10% and less than or equal to 300% of the length of said first metal layer at said first ridge.

4. A coil component as described in any one of claims 1 to 3, wherein an edge of the first metal layer is present on a surrounding surface connected to the first side surface, and the thickness of the first metal layer at the edge on the surrounding surface connected to the first side surface is thinner than the thickness of the first metal layer at an end of the surrounding surface connected to the first side surface.

5. A coil component as described in claim 4, wherein the thickness of said first metal layer gradually decreases from the end of the peripheral surface connected to said first side surface toward the edge of said first metal layer.

6. A coil component as described in claim 4 or 5, wherein, among the surrounding surfaces connected to the first side surface, an edge of the first metal layer on the second main surface is located closer to the third side surface than an edge of the first metal layer on the first main surface.

7. A coil component according to any one of claims 4 to 6, wherein a gap is provided between at least a part of the edge of the first metal layer and the flange portion.

8. A coil component according to any one of claims 4 to 7, wherein the surface of the first metal layer at the edge is smooth.

9. A coil component according to any one of claims 4 to 8, wherein, among the edges of the first metal layer, the edge of the first metal layer at the second ridge is the furthest from the first side surface.

10. A coil component according to any one of claims 1 to 9, wherein a second metal layer is provided between the base electrode layer and the first metal layer.

11. The coil component according to claim 10, further comprising a third metal layer provided between the base electrode layer and the second metal layer.

12. A method for manufacturing a coil component, comprising: preparing a core having a winding core portion and flange portions provided on both ends of the winding core portion; forming a base electrode layer on one side of the flange portions; forming a first metal layer on the base electrode layer and the flange portions by barrel plating; winding a wire around the winding core portion; and electrically connecting ends of the wire to the first metal layer.

13. The method for manufacturing a coil component according to claim 12, wherein the first metal layer is formed using a media in the barrel plating.

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