Coil component

Abstract

To prevent such a cohesive failure from occurring to an adhesive agent that a second core is peeled off from a first core.SOLUTION: A coil component comprises a drum core 10C as a first core, and a top plate 10F as a second core. The coil component also includes a wire, and an adhesive 50. The adhesive 50 contains a bisphenol F-type resin 51, a magnetic powder 52, and a hardening agent 53. The cross section orthogonal to an adhesive surface AS between the adhesive 50 and the drum core 10C is defined as a specific cross section, the direction orthogonal to the adhesive surface AS is defined as a thickness direction, and the direction orthogonal the thickness direction in the specific cross section is defined as an extending direction. In the specific cross section, the adhesive 50 has a resin part 60 between the drum core 10C and the top plate 10F in the thickness direction where a region not including the magnetic powder 52 continuously spans 3 μm or more in the extension direction.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a coil component. [Background technology]

[0002] The coil component described in Patent Document 1 includes a core. The core has a winding core portion and two flange portions. The winding core portion is in the shape of a rectangular prism. The two flange portions are connected to both sides of the winding core portion. Each flange portion protrudes outward from the winding core portion in a direction perpendicular to the central axis of the winding core portion. The core is made of a magnetic material. The coil component also includes a top plate. The top plate is in the shape of a substantially rectangular plate. The top plate is connected to the core so as to bridge the two flange portions. The coil component includes an adhesive. The adhesive is interposed between the top plate and the core. The adhesive bonds the top plate and the core to each other. The adhesive also includes magnetic powder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2013 / 229254 Summary of the Invention [Problem to be solved by the invention]

[0004] The adhesive applied to the coil component described in Patent Document 1 contains magnetic powder, and therefore the magnetic permeability of the adhesive is higher than that of an adhesive that does not contain magnetic powder. On the other hand, the magnetic powder contained in the adhesive does not contribute to improving the adhesive strength of the adhesive. Therefore, an adhesive that contains a large amount of magnetic powder may cause internal failure starting from the interface of the magnetic powder, i.e., cohesive failure. [Means for solving the problem]

[0005] In order to solve the above problems, the present invention provides a coil component comprising a first core, a second core, a wire wound around the first core, and an adhesive interposed between the first core and the second core and adhering the first core and the second core, the adhesive containing a synthetic resin, a magnetic powder, and a curing agent for the synthetic resin, and when a cross section perpendicular to a bonding surface between the adhesive and the first core is defined as a specific cross section, a direction perpendicular to the bonding surface is defined as a thickness direction, and a direction perpendicular to the thickness direction in the specific cross section is defined as an extension direction, in the specific cross section, the adhesive has a resin portion in which a portion in the thickness direction from the first core to the second core that does not contain the magnetic powder extends continuously for 3 μm or more in the extension direction. Effect of the Invention

[0006] According to the above configuration, it is possible to prevent the adhesive from experiencing cohesive failure that would cause the second core to peel off from the first core. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view of a coil component. [Diagram 2] FIG. 2 is an exploded perspective view of the coil component. [Diagram 3] FIG. 3 is a schematic diagram of the adhesive before hardening. [Figure 4] FIG. 4 is a cross-sectional view of a specific cross section of the coil component. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of 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.

[0009] <Overall structure of coil parts> As shown in FIG. 1, the coil device 10 includes a drum core 10C as a first core, and a top plate 10F as a second core.

[0010] The drum core 10C has a winding core 11. The winding core 11 is a square prism having a central axis 11C. A cross section of the winding core 11 perpendicular to the central axis 11C is rectangular. The "rectangular shape" referred to here may be any shape having four sides and generally rectangular, and may also include a shape with chamfered corners. The material of the winding core 11 is, for example, alumina, Ni-Zn ferrite, synthetic resin, or a mixture thereof. In this embodiment, the material of the winding core 11 is Ni-Zn ferrite, which is a type of magnetic material.

[0011] Here, a specific axis perpendicular to the central axis 11C of the winding core 11 is defined as the first axis X. In this embodiment, the first axis X is parallel to the two short sides of the winding core 11 when viewed in the direction along the central axis 11C. An axis perpendicular to both the first axis X and the central axis 11C is defined as the second axis Y. In this embodiment, the second axis Y is parallel to the two long sides of the winding core 11 when viewed in the direction along the central axis 11C. An axis parallel to the central axis 11C is defined as the third axis Z. One of the directions along the first axis X is defined as the first positive direction X1, and the opposite direction to the first positive direction X1 is defined as the first negative direction X2. Similarly, one of the directions along the second axis Y is defined as the second positive direction Y1, and the opposite direction to the second positive direction Y1 is defined as the second negative direction Y2. Moreover, one of the directions along the third axis Z is defined as a third positive direction Z1, and the direction opposite to the third positive direction Z1 is defined as a third negative direction Z2.

[0012] As shown in FIG. 1, the drum core 10C has two flanges 20 connected to both ends of the winding core 11 in the direction along the central axis 11C. The two flanges 20 are specifically a first flange 21 and a second flange 22. The first flange 21 is connected to a first end of the winding core 11 in the third positive direction Z1. The first flange 21 has a flat, substantially rectangular plate shape. The thickness direction of the first flange 21 is a direction along the third axis Z. When viewed in the direction along the third axis Z, each side of the first flange 21 is substantially parallel to each side of the winding core 11. The first flange 21 protrudes outward from the outer surface of the winding core 11 in the direction along the first axis X and the direction along the second axis Y. That is, when viewed in a direction along the third axis Z, the first flange portion 21 protrudes from the outer surface of the winding core portion 11 over the entire circumference of 360 degrees.

[0013] The first flange 21 has a first recess 21A. The first recess 21A is recessed with respect to an end face of the first flange 21 in the first positive direction X1. The first recess 21A is located at the center of the first flange 21 in the direction along the second axis Y. The first recess 21A is open to both sides of the first flange 21 in the direction along the third axis Z. As a result, the end face of the first flange 21 on the first positive direction X1 side is divided into two parts with the first recess 21A in between.

[0014] The second flange 22 is connected to a second end of the winding core 11 on the third negative direction Z2 side. The second flange 22 has a shape that is plane-symmetrical to the first flange 21. That is, the second flange 22 is a substantially rectangular plate shape. The second flange 22 protrudes outward from the outer surface of the winding core 11 in the direction along the first axis X and the direction along the second axis Y. That is, the second flange 22 protrudes 360 degrees from the outer surface of the winding core 11 when viewed in the direction along the third axis Z. The second flange 22 has a second recess 22A similar to the first recess 21A of the first flange 21. The material of the first flange 21 and the second flange 22 is Ni-Zn ferrite, the same as that of the winding core 11. That is, the drum core 10C is made of a magnetic material. Moreover, the first flange portion 21 and the second flange portion 22 are integrally molded with the winding core portion 11.

[0015] The top plate 10F is a flat rectangular plate. The thickness direction of the top plate 10F is along the first axis X. The long side of the top plate 10F is parallel to the third axis Z. The short side of the top plate 10F is parallel to the second axis Y. The top plate 10F is located on the first negative direction X2 side with respect to the drum core 10C. The top plate 10F is connected to both the surface of the first flange portion 21 facing the first negative direction X2 side and the surface of the second flange portion 22 facing the first negative direction X2 side. In other words, the top plate 10F is connected to the drum core 10C so as to bridge between the first flange portion 21 and the second flange portion 22. The material of the top plate 10F is the same as that of the winding core portion 11. In other words, the top plate 10F is Ni-Zn ferrite, which is a type of magnetic material. The top plate 10F forms a closed magnetic circuit together with the drum core 10C. In this embodiment, the top plate 10F, on which the wires described later are not directly wound, and the flange portion 20 of the drum core 10C, on which the wires are not wound, are also considered to be the core or a part of the core.

[0016] The coil component 10 includes an adhesive 50. The adhesive 50 is interposed between the drum core 10C and the top plate 10F. That is, the adhesive 50 bonds the drum core 10C and the top plate 10F. In other words, the top plate 10F is connected to the two flanges 20 via the adhesive 50. In this embodiment, the drum core 10C and the top plate 10F are in direct contact with the adhesive 50. Details of the adhesive 50 will be described later.

[0017] The coil component 10 includes four external electrodes 30. Specifically, the coil component 10 includes a first electrode 31, a second electrode 32, a third electrode 33, and a fourth electrode 34. The first electrode 31 is located on an end face of the outer surface of the first flange portion 21 on the first positive direction X1 side. The first electrode 31 is located on the outer surface of the first flange portion 21 on the second positive direction Y1 side with respect to the central axis 11C. Specifically, the first electrode 31 is located on the second positive direction Y1 side with respect to the first recess 21A.

[0018] The second electrode 32 is located on the end face on the first positive direction X1 side of the outer surface of the first flange 21. The second electrode 32 is located on the second negative direction Y2 side with respect to the central axis 11C of the outer surface of the first flange 21. Specifically, the second electrode 32 is located on the second negative direction Y2 side with respect to the first recess 21A.

[0019] The third electrode 33 is located on the end face on the first positive direction X1 side of the outer surface of the second flange 22. The third electrode 33 is located on the second positive direction Y1 side with respect to the central axis 11C of the outer surface of the second flange 22. Specifically, the third electrode 33 is located on the second positive direction Y1 side with respect to the second recess 22A.

[0020] The fourth electrode 34 is located on the end face on the first positive direction X1 side of the outer surface of the second flange 22. The fourth electrode 34 is also located on the second negative direction Y2 side with respect to the central axis 11C of the outer surface of the second flange 22. Specifically, the fourth electrode 34 is located on the second negative direction Y2 side with respect to the second recess 22A.

[0021] Although not shown in the figure, the external electrode 30 has a metal layer and a plating layer. The material of the metal layer is silver. The metal layer is formed on the outer surfaces of the first flange portion 21 and the second flange portion 22. The plating layer is made of three layers. The plating layer is formed by stacking copper, nickel, and tin in this order on the surface of the metal layer. The end face of the coil component 10 on the first positive direction X1 side is a mounting surface that faces the board when the coil component 10 is mounted on the board.

[0022] 1, the coil device 10 includes a first wire 41 and a second wire 42. The first wire 41 and the second wire 42 are wound around the winding core portion 11 of a drum core 10C.

[0023] Although not shown, the first wire 41 has a copper wire and an insulating coating. The insulating coating covers the outer surface of the copper wire. The first wire 41 has a substantially circular shape in a cross section perpendicular to the direction in which the first wire 41 extends. The second wire 42 has the same configuration as the first wire 41. That is, the second wire 42 has a copper wire and an insulating coating. Note that in FIG. 1, the first wire 41 is colored with dots.

[0024] A first wire end 41A of the first wire 41 is connected to the first electrode 31. A second wire end 41B of the first wire 41 is connected to the third electrode 33. The first wire end 41A and the second wire end 41B are connected to the corresponding external electrodes 30 by thermocompression bonding.

[0025] In addition, the first wire 41 is wound around the winding core 11 so as to progress clockwise from the first wire end 41A side to the second wire end 41B side when viewed in the third negative direction Z2.

[0026] A first end 42A of the second wire 42 is connected to the second electrode 32. A second end 42B of the second wire 42 is connected to the fourth electrode 34. The first end 42A and the second end 42B are connected to the corresponding electrodes by thermocompression.

[0027] Furthermore, the second wire 42 is wound around the winding core 11 so as to progress clockwise as it travels from the first wire end 42A to the second wire end 42B when viewed in the third negative direction Z2. That is, the second wire 42 is wound in the same direction as the first wire 41. The second wire 42 is wound around the winding core 11 from the outside relative to the first wire 41.

[0028] <About adhesives> As shown in FIG. 2, the adhesive 50 covers the entire surface of the first flange 21 facing the first negative direction X2. The adhesive 50 connects the first flange 21 and the top plate 10F without any gaps. Similarly, the adhesive 50 covers the entire surface of the second flange 22 facing the first negative direction X2. The adhesive 50 connects the second flange 22 and the top plate 10F without any gaps. In other words, the top plate 10F is connected to the two flanges 20.

[0029] As shown in Fig. 3, the adhesive 50 contains a bisphenol F type resin 51 as a synthetic resin. The adhesive 50 also contains a magnetic powder 52, a curing agent 53, a curing accelerator 54, a silane coupling agent 55, and a dispersant 56. Note that the adhesive 50 shown in Fig. 3 is in a state before curing. Also, in Fig. 3, only some of the magnetic powder 52, the curing agent 53, and the curing accelerator 54 are labeled with reference numerals.

[0030] Specifically, the adhesive 50 is manufactured as follows. First, the bisphenol F type resin 51, the curing agent 53, the curing accelerator 54, the silane coupling agent 55, the dispersant 56, and the magnetic powder 52 are mixed for 5 minutes at a rotation speed of 30 rpm using a kneader (model number: Hibismix (registered trademark) 2P-03 (manufactured by Primix Corporation)). Then, the mixture is kneaded at a clearance of 6 μm and 230 rpm using a disperser (model number: EXAKT 80E (manufactured by Nagase Screen Printing Laboratory Co., Ltd.)) to manufacture the adhesive 50 before curing.

[0031] In this embodiment, the bisphenol F type resin 51 is a bisphenol F type epoxy resin. Specifically, the bisphenol F type resin 51 is CAS No. 9003-36-5. In this embodiment, the bisphenol F type resin 51 is collectively referred to as the bisphenol F type resin 51 regardless of whether it is a monomer or a polymer.

[0032] The number average molecular weight of the bisphenol F resin 51 is 312 g / mol. The number average molecular weight can be measured using a GPC (model number: HLC-8120GPC (manufactured by Tosoh Technosystems)). GPC stands for gel permeation chromatography. In the measurement using this device, the column temperature was set to 40° C. In addition, tetrahydrofuran was used as the solvent in the measurement. The flow rate of the solution containing the solvent was set to 1.0 ml / min. In addition, the standard sample was monodisperse polystyrene.

[0033] In this embodiment, the magnetic powder 52 is nickel powder. Specifically, the magnetic powder 52 is CAS No. 7440-02-0. The magnetic powder 52 includes particles having a particle size of 0.1 μm or more and 11 μm or less. In this embodiment, the magnetic powder 52 includes particles having a particle size of 0.1 μm or more and 3.0 μm or less. The particle size of the magnetic powder 52 is calculated as follows. First, the cross section of the adhesive 50 is observed with an electron microscope. Then, in the observed range, the outline of the magnetic powder 52 is obtained by image processing. Then, the area of ​​one magnetic powder 52 is calculated. Then, a circle having the calculated area is assumed. The diameter of the circle is calculated as the particle size of the magnetic powder 52.

[0034] In the particle size distribution of the magnetic powder 52, the median particle size (D50) is 0.5 μm or more and 0.96 μm or less. The median particle size (D50) of the magnetic powder 52 is calculated, for example, as follows. First, the magnetic powder 52 is sampled using a scanning electron microscope to obtain the particle size distribution. Next, in the particle size distribution, the frequency of each particle size is integrated from the smallest particle size to the largest particle size. The particle size at which the integrated value is 50% is defined as the median particle size (D50).

[0035] The curing agent 53 is a curing agent for the bisphenol F type resin 51. In this embodiment, the curing agent 53 is dicyandiamide. Specifically, the curing agent 53 is CAS No. 461-58-5.

[0036] The curing accelerator 54 is a curing accelerator for the bisphenol F type resin 51. In this embodiment, the curing accelerator 54 is an amine adduct. Specifically, the curing accelerator 54 is CAS No. 134091-75-1.

[0037] The dispersant 56 is for dispersing the magnetic powder 52 in the adhesive 50. In this embodiment, the dispersant 56 is a modified carboxyl group-containing polymer. Specifically, the dispersant 56 is a modified carboxyl group-containing polymer having an acid value of 55 mgKOH / g.

[0038] In this embodiment, the silane coupling agent 55 is glycidoxypropyltrimethoxysilane. Specifically, the silane coupling agent 55 is CAS No. 253-83-8.

[0039] <Cross-section of adhesive in coil components> In the state of the coil component 10, the adhesive 50 is in a cured state. The adhesive 50 is cured, for example, by baking at 100 degrees. In the cured adhesive 50, the bisphenol F resin 51, the curing agent 53, and the curing accelerator 54 are polymerized. The adhesive 50 is in a state in which the magnetic powder 52 is dispersed in the cured polymer containing the bisphenol F resin 51 as a main component.

[0040] 4, a cross section perpendicular to an adhesive surface AS between the adhesive 50 and the drum core 10C is defined as a specific cross section. In this embodiment, the specific cross section is a cross section along a first axis X and a second axis Y.

[0041] Here, the direction perpendicular to the adhesive surface AS is the thickness direction. Also, the direction perpendicular to the thickness direction in a specific cross section is the stretching direction. In this embodiment, the adhesive surface AS is defined as follows. First, in a cross section including the adhesive 50 and the drum core 10C, in a section where the adhesive 50 and the drum core 10C contact each other, 10 points of contact between the adhesive 50 and the drum core 10C are identified at equal intervals. In FIG. 4, these 10 points are indicated by black dots. Then, an approximate straight line of the 10 points is calculated. For example, the approximate straight line is calculated by the least squares method. Then, a surface along the calculated approximate straight line is determined as the adhesive surface AS. Note that the thickness direction perpendicular to the adhesive surface AS may be inclined with respect to the first axis X.

[0042] In the specific cross section, the dimension in the thickness direction of the end portion in the stretching direction of the adhesive 50 is slightly larger than the dimension in the thickness direction of the center portion in the stretching direction. In addition, in the specific cross section, the average dimension H in the thickness direction of the adhesive 50 is 1 μm or more and 11 μm or less. The average dimension H in the thickness direction of the adhesive 50 is calculated as follows. First, the specific cross section is photographed with an electron microscope. Next, a range in the direction along the outer surface of the adhesive 50 on the drum core 10C side is specified for the photographed image. In this range, the cross-sectional area of ​​the adhesive 50 is calculated by image processing for a measurement range of at least 5 μm or more. Then, the dimension in the thickness direction of the adhesive 50 is calculated by dividing the cross-sectional area of ​​the adhesive 50 in the calculated measurement range by the length of the measurement range. In other words, the average dimension H in the thickness direction of the adhesive 50 is the dimension in the measurement range. Note that the average dimension H in the thickness direction shown in FIG. 4 is an example and is not limited to the illustrated dimension.

[0043] As shown in FIG. 4, the adhesive 50 has two resin parts 60 in the specific cross section. Each resin part 60 is a part where the part not containing the magnetic powder 52 extends continuously for 3 μm or more in the extension direction between the drum core 10C and the top plate 10F in the thickness direction in the specific cross section. In other words, the resin part 60 is a part where the minimum distance between the magnetic powders 52 in the extension direction is 3 μm or more. In this embodiment, not containing the magnetic powder 52 refers to the case where the magnetic powder 52 is not detected when the specific cross section is observed in a backscattered electron image at 1000 times magnification with a scanning electron microscope. In this embodiment, the resin part 60 contains the bisphenol F type resin 51 as a main component, and also contains the curing agent 53, the curing accelerator 54, the silane coupling agent 55, and the dispersant 56. The curing agent 53, the curing accelerator 54, the silane coupling agent 55, and the dispersant 56 may be included in the resin part 60 in an unreacted state, or may form a polymer together with the bisphenol F type resin 51.

[0044] Of the two resin parts 60, one resin part 60 is located near the end of the adhesive 50 on the second positive direction Y1 side in the specific cross section. The other resin part 60 is located near the end of the adhesive 50 on the second negative direction Y2 side in the specific cross section. That is, the resin parts 60 are present on both sides of the center of the adhesive 50 in the extension direction. One of the two resin parts 60 has a length P1 along the extension direction of about 7 μm. The other of the two resin parts 60 has a length P2 along the extension direction of about 15 μm. The lengths P1 and P2 of these resin parts 60 along the extension direction are examples and may be 3 μm or more.

[0045] In the specific cross section, the proportion of the resin part 60 in the adhesive 50 is 10% or more. The proportion of the resin part 60 in the adhesive 50 is calculated as follows. First, the specific cross section is photographed with a scanning electron microscope. Next, for the photographed image, two end points in the stretching direction of the adhesive surface AS with the drum core 10C are identified. Then, for the image, the length between the two points in the stretching direction is identified. Next, for the photographed image, the total length of the resin part 60 in the stretching direction is identified. Then, the value obtained by dividing the identified total length of the resin part 60 by the length between the two end points of the adhesive surface AS is determined as the proportion of the resin part 60 in the adhesive 50.

[0046] In the specific cross section, the ratio of the magnetic powder 52 to the adhesive 50 is 20% or more and 40% or less. The ratio of the magnetic powder 52 to the adhesive 50 is calculated as follows. First, an observation image of the specific cross section is obtained by a scanning electron microscope using a backscattered electron image at 1000 times magnification. Next, the obtained observation image is binarized. Next, the outer edge of the magnetic powder 52 is determined by performing a morphology process, specifically, a shrinkage process, once on the observation image. Next, the total cross-sectional area of ​​the magnetic powder 52 and the cross-sectional area of ​​the entire adhesive 50 are calculated by image processing for the same image. Then, the ratio of the magnetic powder 52 to the adhesive 50 is calculated by dividing the total cross-sectional area of ​​the magnetic powder 52 by the cross-sectional area of ​​the entire adhesive 50.

[0047] <Growth of resin during the adhesive curing process> In one step of the manufacturing process of the coil component 10, the adhesive 50 before curing is applied to the drum core 10C. Specifically, the adhesive 50 before curing is applied to substantially the entire end face of the first flange portion 21 on the first negative direction X2 side and substantially the entire end face of the second flange portion 22 on the first negative direction X2 side. Then, the top plate 10F is attached to the drum core 10C via the adhesive 50. Then, the drum core 10C to which the top plate 10F is attached with the adhesive 50 is baked at 100°C or higher. At a temperature near 100°C, the bisphenol F type resin 51 begins to harden with the hardener 53 as a core. Then, the bisphenol F type resin 51 with the hardener 53 as a core pushes aside the magnetic powder 52 during the hardening process and expands its hardening range. As a result, a resin portion 60 is formed that does not contain the magnetic powder 52 between the drum core 10C side and the top plate 10F and extends continuously over 3 μm in the extension direction.

[0048] As described above, in the specific cross section, the dimension in the thickness direction of the end portion in the stretching direction of the adhesive 50 is slightly larger than the dimension in the thickness direction of the center portion in the stretching direction. Therefore, in the adhesive 50 before curing, the bisphenol F type resin 51 is likely to accumulate at the end portion. As a result, the resin portion 60 is likely to be formed near the end portion in the stretching direction of the adhesive 50 in the specific cross section.

[0049] <Effects of this embodiment> (1) In the above embodiment, the adhesive 50 contains the magnetic powder 52, and therefore has a better magnetic permeability than a configuration that does not contain the magnetic powder 52. In the adhesive 50 of the above configuration, the resin portion 60 does not contain the magnetic powder 52. Moreover, the resin portion 60 extends over 3 μm or more in the extension direction. In this way, the resin portion 60 without the interface of the magnetic powder 52 exists in a chunk shape with a considerable length, and therefore the resin portion 60 can ensure the adhesive strength between the drum core 10C and the top plate 10F. In other words, it is possible to suppress the adhesive 50 from experiencing cohesive failure that would cause the top plate 10F to peel off from the drum core 10C.

[0050] (2) In the above embodiment, the magnetic powder 52 contains particles having a particle size of 0.1 μm or more and 11 μm or less. That is, by containing the magnetic powder 52 having such a particle size, the magnetic permeability of the adhesive 50 is improved.

[0051] (3) In the above embodiment, the top plate 10F is connected to the two flange portions 20 via the adhesive 50. That is, in the above embodiment, the coil device 10 has a closed magnetic circuit made up of the drum core 10C and the top plate 10F. In this way, using the adhesive 50 of the above embodiment as the adhesive 50 for bonding the drum core 10C and the top plate 10F that form the closed magnetic circuit is particularly suitable for improving the characteristics of the coil device 10 as a whole.

[0052] (4) In the above embodiment, the drum core 10C and the top plate 10F are in direct contact with the adhesive 50. If another member is interposed between the adhesive 50 and the drum core 10C, a structure is required to bond the other member to the drum core 10C. In other words, according to the above structure, since no additional structure is required for bonding, the size of the coil device 10 can be prevented from increasing. In this regard, the direct contact between the top plate 10F and the adhesive 50 provides the same effect.

[0053] (5) In the above embodiment, in the specific cross section, the proportion of the resin portion 60 in the adhesive 50 is 10% or more. When the adhesive 50 has the resin portion 60 at such a proportion, cohesive failure in the adhesive 50 can be more effectively suppressed.

[0054] (6) In the above embodiment, in the specific cross section, the proportion of the magnetic powder 52 in the adhesive 50 is 20% or more and 40% or less. Since the adhesive 50 having the resin portion 60 has the magnetic powder 52 in such a proportion, it is possible to obtain good magnetic permeability while ensuring adhesive strength.

[0055] (7) In the above embodiment, the adhesive 50 contains an epoxy resin as a synthetic resin. The adhesive 50 also contains dicyandiamide as a curing agent. By using these materials, the resin portion 60 can be formed efficiently.

[0056] (8) In the above embodiment, the synthetic resin of the adhesive 50 is bisphenol F type epoxy resin. This configuration can prevent the viscosity of the adhesive 50 from increasing before hardening. As a result, for example, it can prevent air bubbles from being generated at the interfaces between the adhesive 50 and the drum core 10C and the top plate 10F.

[0057] (9) In the above embodiment, in the case of particles with a small particle size, the filling rate of the magnetic powder 52 in the adhesive 50 can be increased, but the particle interface increases, which may weaken the passage of magnetic flux in the adhesive 50. In the above embodiment, the median particle size (D50) of the magnetic powder 52 is 0.5 μm or more and 0.96 μm or less. According to such a range of the median particle size (D50), the filling rate of the magnetic powder 52 in the adhesive 50 can be increased. Furthermore, in this embodiment, it is highly likely that the magnetic powder 52 contains particles with a relatively large particle size of 0.96 μm or more. Therefore, it is possible to suppress the weakening of the passage of magnetic flux in the adhesive 50.

[0058] (10) In the above embodiment, in the specific cross-sectional view, the average dimension H of the adhesive 50 in the thickness direction is 1 μm or more and 11 μm or less. If the dimension of the adhesive 50 in the thickness direction is too large, it is difficult to form the resin portion 60 extending from the drum core 10C to the top plate 10F. On the other hand, if the dimension of the adhesive 50 in the thickness direction is too small, the adhesive strength may decrease. With the above configuration, these problems can be effectively suppressed.

[0059] (11) In the above embodiment, in the specific cross-sectional view, the resin parts 60 are present on both sides of the center of the adhesive 50 in the extension direction. Since the resin parts 60 having a relatively high adhesive strength are present on both sides in this manner, an unbalanced state in which the adhesive strength is high on one side of the adhesive 50 and low on the other side of the adhesive 50 is unlikely to occur. In other words, the adhesive strength of the adhesive 50 can be made uniform, so that peeling of the adhesive 50 starting from a point with low adhesive strength can be prevented.

[0060] <Example of change> The above embodiment and the following modified examples can be implemented in combination with each other to the extent that no technical contradiction occurs.

[0061] <Examples of changes to coil parts> The shape of the winding core 11 is not limited to the example of the above embodiment. For example, the shape of the winding core 11 may be a cylinder or a polygonal prism other than a quadrangular prism.

[0062] The configuration of the drum core 10C is not limited to the example of the above embodiment. For example, the drum core 10C may not have the first recess 21A and the second recess 22A. In this case, for example, it is sufficient that the first electrode 31 and the second electrode 32 are separated from each other, and the third electrode 33 and the fourth electrode 34 are separated from each other. The drum core 10C may have at least the winding core portion 11 and the flange portion 20.

[0063] The material and shape of the external electrode 30 are not limited to those in the above embodiment. For example, the material of the plating layer of the external electrode 30 may be an alloy of tin or nickel. The external electrode 30 may not have a plating layer. In that case, the portion where the conductive metal layer is exposed may be used as the external electrode 30.

[0064] The coil device 10 may include at least one wire. When the number of wires is one, one external electrode 30 may be provided on the first flange 21 and one external electrode 30 may be provided on the second flange 22.

[0065] The coil component 10 is not limited to a configuration including a drum core 10C and a top plate 10F. The coil component 10 may have a first core around which a wire is wound and a second core connected to the first core via an adhesive 50. The first core and the second core may be bonded by the adhesive 50. The drum core 10C and the top plate 10F may not be in direct contact with the adhesive 50. For example, a flat metal terminal may be fixed to the first flange 21 and the second flange 22 of the drum core 10C, and the adhesive 50 may be applied onto the metal terminal. That is, even when the drum core 10C and the adhesive 50 are in contact with each other via another member, the adhesive 50 is considered to bond the drum core 10C and the top plate 10F. This is also true when another member is interposed between the top plate 10F and the adhesive 50.

[0066] The material of the drum core 10C and the top plate 10F is not limited to a magnetic material, but may be a non-magnetic material such as alumina or synthetic resin. In a particular cross section, the average dimension H of the adhesive 50 in the thickness direction may be less than 1 μm or may be greater than 11 μm.

[0067] In the specific cross section, the proportion of the resin portion 60 in the adhesive 50 may be less than 10%. In the above embodiment, it is sufficient that there is at least one resin portion 60 in the specific cross section.

[0068] The specific cross section is not limited to the example of the above embodiment. For example, the specific cross section does not have to be a cross section in a direction along the second axis Y. Also, a cross section perpendicular to the adhesive surface between the adhesive 50 and the second flange portion 22 may be the specific cross section.

[0069] In the above embodiment, if there is one or more specific cross sections in which the resin part 60 is observed, the adhesive 50 is deemed to have the resin part 60 in the specific cross sections. For example, when the resin part 60 is cylindrical, the minimum interval between the magnetic powder particles 52 in the extension direction may be less than 3 μm in a certain specific cross section. Even in this case, the adhesive 50 is deemed to have the resin part 60 if the minimum interval between the magnetic powder particles 52 in the extension direction is 3 μm or more in another specific cross section. In order to more effectively suppress cohesive failure of the adhesive 50 that would cause the drum core 10C and the top plate 10F to peel off, it is preferable that the minimum interval between the magnetic powder particles 52 is 3 μm or more in a cross section perpendicular to the adhesive surface AS and perpendicular to the specific cross section. That is, it is more preferable that the shape of the resin part 60 is a cylinder with a diameter of 3 μm or more, or a columnar shape such as a square column with one side of 3 μm or more.

[0070] <Examples of changes to adhesives> The adhesive 50 may contain at least a synthetic resin, a magnetic powder 52, and a hardener 53. The types of the synthetic resin, the magnetic powder 52, and the hardener 53 are not limited to those in the above embodiment. The type of the hardener 53 may be one that corresponds to the synthetic resin in the adhesive 50. For example, in the above embodiment, an amine adduct may be used as the hardener 53, and the hardener accelerator 54 may be omitted.

[0071] The number average molecular weight of the bisphenol F type resin 51 in the adhesive 50 is not limited to the example in the above embodiment. Taking into consideration the adhesive strength, viscosity, and the like, it is sufficient to use a bisphenol F type resin 51 having an appropriate number average molecular weight.

[0072] The adhesive 50 does not necessarily need to contain the silane coupling agent 55, the dispersant 56, and the curing accelerator 54. In addition, the types of the silane coupling agent 55, the dispersant 56, and the curing accelerator 54 are not limited to those in the above embodiment.

[0073] The median particle size (D50) of the magnetic powder 52 in the adhesive 50 may be less than 0.5 μm or greater than 0.96 μm. The magnetic powder 52 does not have to contain particles having a particle size of 0.1 μm or more and 11 μm or less. In other words, the particle size of the magnetic powder 52 may all be less than 0.1 μm or greater than 11 μm.

[0074] In a specific cross section, the proportion of the magnetic powder 52 in the adhesive 50 may be less than 20% or more than 40%. The proportion of the magnetic powder 52 in the adhesive 50 may be appropriately selected in consideration of the magnetic permeability and adhesive strength of the entire adhesive 50, etc.

[0075] <Additional Notes> The technical ideas that can be derived from the above-described embodiments and modifications will be described below. [1] A coil component comprising a first core, a second core, a wire wound around the first core, and an adhesive interposed between the first core and the second core and adhering the first core and the second core, the adhesive containing a synthetic resin, a magnetic powder, and a curing agent for the synthetic resin, wherein when a cross section perpendicular to an adhesive surface between the adhesive and the first core is defined as a specific cross section, a direction perpendicular to the adhesive surface is defined as a thickness direction, and a direction perpendicular to the thickness direction in the specific cross section is defined as an extension direction, the adhesive has a resin portion in which a portion not containing the magnetic powder between the first core and the second core in the thickness direction extends continuously for 3 μm or more in the extension direction in the specific cross section.

[0076] [2] The coil component according to [1], wherein the magnetic powder contains particles having a particle size of 0.1 μm or more and 11 μm or less. [3] The coil component described in [1] or [2], wherein the first core has a columnar winding core portion having a central axis and two flange portions connected to both ends of the winding core portion in a direction along the central axis, and the second core is connected to the two flange portions via the adhesive.

[0077] [4] The coil component according to any one of [1] to [3], wherein the first core and the second core are in direct contact with the adhesive. [5] The coil component according to any one of [1] to [4], wherein in the specific cross section, the resin portion accounts for 10% or more of the adhesive.

[0078] [6] The coil component according to any one of [1] to [5], wherein the magnetic powder accounts for 20% or more and 40% or less of the adhesive in the specific cross section. [7] The coil component according to any one of [1] to [6], wherein the synthetic resin is an epoxy resin, and the curing agent includes one or more selected from the group consisting of dicyandiamide and an amine adduct.

[0079] [8] The coil component according to [7], wherein the synthetic resin is a bisphenol F type epoxy resin. [9] The coil component according to any one of [1] to [8], wherein the magnetic powder has a median particle size (D50) of 0.5 μm or more and 0.96 μm or less.

[0080]

[10] The coil component according to any one of [1] to [9], wherein the average dimension of the adhesive in the thickness direction in the specific cross section is 1 μm or more and 11 μm or less. [Explanation of symbols]

[0081] AS…adhesive surface H…Average dimension 10...Coil parts 10C…Drum core 10F…Tabletop 11...Core 20…Flange 30...External electrode 41…First wire 42…Second wire 50…Glue 51...Bisphenol F resin 52...Magnetic powder 53... Hardener 54...Cure accelerator 55...Silane coupling agent 56...Dispersants 60…Resin part

Claims

1. A first core; A second core; A wire wound around the first core; an adhesive interposed between the first core and the second core and bonding the first core and the second core; It is equipped with The adhesive contains a synthetic resin, a magnetic powder, and a curing agent for the synthetic resin, When a cross section perpendicular to the adhesive surface between the adhesive and the first core is defined as a specific cross section, a direction perpendicular to the adhesive surface is defined as a thickness direction, and a direction perpendicular to the thickness direction in the specific cross section is defined as an extension direction, In the specific cross section, the adhesive has a resin portion in which a portion not containing the magnetic powder between the first core and the second core in the thickness direction extends continuously for 3 μm or more in the extension direction. Coil parts.

2. The magnetic powder contains particles having a particle size of 0.1 μm or more and 11 μm or less. The coil component according to claim 1 .

3. The first core has a columnar winding core portion having a central axis and two flange portions connected to both ends of the winding core portion in a direction along the central axis, The second core is connected to the two flange portions via the adhesive. The coil component according to claim 1 .

4. The first core and the second core are in direct contact with the adhesive. The coil component according to claim 1 .

5. In the specific cross section, the resin portion accounts for 10% or more of the adhesive. The coil component according to claim 1 .

6. In the specific cross section, the magnetic powder accounts for 20% or more and 40% or less of the adhesive. The coil component according to claim 1 .

7. The synthetic resin is an epoxy resin, The curing agent includes one or more selected from dicyandiamide and an amine adduct. The coil component according to claim 1 .

8. The synthetic resin is a bisphenol F type epoxy resin. The coil component according to claim 7.

9. The median particle size (D50) of the magnetic powder is 0.5 μm or more and 0.96 μm or less. The coil component according to claim 1 .

10. In the specific cross section, the average dimension of the adhesive in the thickness direction is 1 μm or more and 11 μm or less. The coil component according to claim 1 .

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