Coil component

Abstract

The invention relates to a coil component. The purpose of the present invention is to suppress the occurrence of cohesive failure in an adhesive in which a second core is peeled from a first core. The coil component is provided with a drum-shaped core (10C) as a first core and a top plate (10F) as a second core. In addition, the coil component is provided with a wire rod and an adhesive (50). The adhesive (50) contains a bisphenol F resin (51), a magnetic powder (52), and a curing agent (53). A cross-section orthogonal to the adhesive (50) and an adhesive surface (AS) of the drum-shaped core (10C) is defined as a specific cross-section, a direction orthogonal to the adhesive surface (AS) is defined as a thickness direction, and a direction orthogonal to the thickness direction in the specific cross-section is defined as an extension direction. In a specific cross-section, the adhesive (50) has a resin part (60) that continuously extends over 3 [mu] m or more in the direction of extension in a region that does not contain the magnetic powder (52) from the drum-shaped core (10C) to the top plate (10F) in the thickness direction.

Description

Technical Field

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

[0002] The coil component described in patent document 1 has a core body. The core body has a winding core portion and two flange portions. The winding core portion is in the shape of a quadrangular prism. The two flange portions are connected to the two sides of the winding core portion. Each flange portion extends outward from the winding core portion in a direction perpendicular to the central axis of the winding core portion. The material of the core body is a magnetic body. In addition, the coil component has a top plate. The top plate is in the shape of a roughly rectangular plate. The top plate is connected to the core body in a manner of being mounted on the two flange portions. The coil component has an adhesive. The adhesive is between the top plate and the core body. Moreover, the adhesive bonds the top plate and the core body to each other. In addition, the adhesive contains magnetic powder.

[0003] Patent Document 1: U.S. Patent Application Publication No. 2013 / 229254

[0004] The adhesive used in the coil component described in Patent Document 1 contains magnetic powder, so that the magnetic permeability of the adhesive becomes higher than that of the case where the magnetic powder is not contained. On the other hand, the magnetic powder contained in the adhesive does not contribute to the improvement of the bonding strength of the adhesive. Therefore, the adhesive containing a lot of magnetic powder is likely to be destroyed from the inside starting from the interface of the magnetic powder, that is, cohesive failure occurs. Summary of the invention

[0005] In order to solve the above-mentioned problems, the present invention provides a coil component, comprising: a first core body; a second core body; a wire material, which is wound on the above-mentioned first core body; and an adhesive, which is interposed between the above-mentioned first core body and the above-mentioned second core body and bonds the above-mentioned first core body and the above-mentioned second core body, the above-mentioned adhesive contains a synthetic resin, magnetic powder, and a curing agent for the above-mentioned synthetic resin, when a section perpendicular to the bonding surface of the above-mentioned adhesive and the above-mentioned first core body is set as a specific section, a direction perpendicular to the above-mentioned bonding surface is set as a thickness direction, and a direction perpendicular to the above-mentioned thickness direction in the above-mentioned specific section is set as an extension direction, in the above-mentioned specific section, the above-mentioned adhesive has a resin portion, and the above-mentioned resin portion is formed to continuously extend over 3 μm in the above-mentioned extension direction in a portion that does not contain the above-mentioned magnetic powder between the above-mentioned first core body and the above-mentioned second core body in the above-mentioned thickness direction.

[0006] According to the above configuration, it is possible to suppress the occurrence of cohesive failure in the adhesive, in which the second core is peeled off from the first core. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a three-dimensional diagram of the coil component.

[0008] Figure 2 This is an exploded perspective view of the coil component.

[0009] Figure 3 is a schematic diagram of the structure of the adhesive before curing.

[0010] Figure 4 It is a cross-sectional view at a specific cross section of the coil component.

[0011] Description of Reference Numerals

[0012] AS…bonding surface; H…average size; 10…coil component; 10C…drum-shaped core; 10F…top plate; 11…winding core portion; 20…flange portion; 21…first flange portion; 21A…first recessed portion; 22…second flange portion; 22A…second recessed portion; 30…external electrode; 31…first electrode; 32…second electrode; 33…third electrode; 34…fourth electrode; 41…first wire material; 42…second wire material; 50…adhesive; 51…bisphenol F type resin; 52…magnetic powder; 53…curing agent; 54…curing accelerator; 55…silane coupling agent; 56…dispersant; 60…resin portion. DETAILED DESCRIPTION

[0013] Hereinafter, one embodiment of the coil component will be described with reference to the accompanying drawings. In addition, the accompanying drawings may enlarge the components for easy understanding. The dimensional ratios of the components may be different from the actual ones or from those in other drawings.

[0014] <About the overall structure of the coil component>

[0015] like Figure 1 As shown, the coil component 10 includes a drum-shaped core body 10C as a first core body and a top plate 10F as a second core body.

[0016] The drum-shaped core 10C has a winding core portion 11. The winding core portion 11 is in the shape of a quadrangular prism having a central axis 11C. The cross section perpendicular to the central axis 11C of the winding core portion 11 is in the shape of a rectangle. In addition, the "rectangular shape" mentioned here only needs to have four sides and be a rectangular shape as a whole, and also includes a shape in which the corners of the rectangle are chamfered. The material of the winding core portion 11 is, for example, alumina, Ni-Zn ferrite, synthetic resin, and a mixture thereof. In the present embodiment, the material of the winding core portion 11 is Ni-Zn ferrite, which is a kind of magnetic material.

[0017] Here, a specific axis orthogonal to the central axis 11C of the winding core 11 is set as the first axis X. In the present embodiment, when viewed in the direction along the central axis 11C, the first axis X is parallel to the two short sides of the winding core 11. In addition, an axis orthogonal to both the first axis X and the central axis 11C is set as the second axis Y. In the present embodiment, when viewed in the direction along the central axis 11C, the second axis Y is parallel to the two long sides of the winding core 11. In addition, an axis parallel to the central axis 11C is set as the third axis Z. Moreover, one of the directions along the first axis X is set as the first positive direction X1, and the direction opposite to the first positive direction X1 is set as the first negative direction X2. Similarly, one of the directions along the second axis Y is set as the second positive direction Y1, and the direction opposite to the second positive direction Y1 is set as the second negative direction Y2. In addition, one of the directions along the third axis Z is set as the third positive direction Z1, and the direction opposite to the third positive direction Z1 is set as the third negative direction Z2.

[0018] like Figure 1 As shown, the drum-shaped core 10C has two flange portions 20 connected to both ends of the winding core 11 along the direction of the central axis 11C. Specifically, the two flange portions 20 are a first flange portion 21 and a second flange portion 22. The first flange portion 21 is connected to the first end which is the end of the third positive direction Z1 of the winding core 11. The first flange portion 21 is a flat, approximately square plate. The thickness direction of the first flange portion 21 is along the direction of the third axis Z. When viewed in the direction along the third axis Z, the sides of the first flange portion 21 are approximately parallel to the sides of the winding core 11. In addition, the first flange portion 21 extends outward relative to 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 the direction along the third axis Z, the first flange portion 21 extends over a full 360-degree circumference relative to the outer surface of the winding core 11.

[0019] The first flange portion 21 has a first recessed portion 21A. The first recessed portion 21A is recessed relative to the end surface of the first flange portion 21 in the first positive direction X1. The first recessed portion 21A is located at the center of the first flange portion 21 in the direction along the second axis Y. The first recessed portion 21A is open to both sides of the first flange portion 21 in the direction along the third axis Z. As a result, the end surface of the first flange portion 21 on the first positive direction X1 side is divided into two parts via the first recessed portion 21A.

[0020] The second flange portion 22 is connected to the second end of the winding core portion 11 on the third negative direction Z2 side. The second flange portion 22 is symmetrical with the first flange portion 21. That is, the second flange portion 22 is roughly square plate-shaped. The second flange portion 22 extends outward relative to the outer surface of the winding core portion 11 in the direction along the first axis X and the direction along the second axis Y. That is, when viewed in the direction along the third axis Z, the second flange portion 22 extends over the entire 360-degree circumference relative to the outer surface of the winding core portion 11. The second flange portion 22 has a second recess 22A that is the same as the first recess 21A of the first flange portion 21. The material of the first flange portion 21 and the second flange portion 22 is the same Ni-Zn ferrite as the winding core portion 11. That is, the drum-shaped core 10C is made of a magnetic material. In addition, the first flange portion 21 and the second flange portion 22 are integrally molded with the winding core portion 11.

[0021] The top plate 10F is a flat rectangular plate. The thickness direction of the top plate 10F is along the direction of 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 relative to the drum-shaped core 10C. Moreover, 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. That is, the top plate 10F is connected to the drum-shaped core 10C in a manner of being arranged between the first flange portion 21 and the second flange portion 22. The material of the top plate 10F is the same material as that of the winding core portion 11. That is, the top plate 10F is a Ni-Zn ferrite as a kind of magnetic material. The top plate 10F forms a closed magnetic circuit together with the drum-shaped core 10C. In the present embodiment, the top plate 10F around which each wire described later is not directly wound and the flange portion 20 around which each wire is not wound in the drum-shaped core 10C are also regarded as the core or a part of the core.

[0022] The coil component 10 includes an adhesive 50. The adhesive 50 is disposed between the drum-shaped core 10C and the top plate 10F. That is, the adhesive 50 bonds the drum-shaped core 10C and the top plate 10F. In other words, the top plate 10F is connected to the two flange portions 20 via the adhesive 50. In addition, in the present embodiment, the drum-shaped core 10C and the top plate 10F are in direct contact with the adhesive 50. In addition, the details of the adhesive 50 will be described later.

[0023] 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 the end surface of the outer surface of the first flange portion 21 on the first positive direction X1 side. In addition, the first electrode 31 is located on the outer surface of the first flange portion 21 at a position on the second positive direction Y1 side relative to the central axis 11C. Specifically, the first electrode 31 is located on the second positive direction Y1 side relative to the first recess 21A.

[0024] The second electrode 32 is located on the end surface on the first positive direction X1 side of the outer surface of the first flange portion 21. In addition, the second electrode 32 is located on the second negative direction Y2 side relative to the central axis 11C of the outer surface of the first flange portion 21. Specifically, the second electrode 32 is located on the second negative direction Y2 side relative to the first recess 21A.

[0025] The third electrode 33 is located on the end surface on the first positive direction X1 side of the outer surface of the second flange portion 22. In addition, the third electrode 33 is located on the second positive direction Y1 side relative to the central axis 11C of the outer surface of the second flange portion 22. Specifically, the third electrode 33 is located on the second positive direction Y1 side relative to the second recess 22A.

[0026] The fourth electrode 34 is located on the end surface on the first positive direction X1 side of the outer surface of the second flange portion 22. In addition, the fourth electrode 34 is located on the second negative direction Y2 side relative to the central axis 11C of the outer surface of the second flange portion 22. Specifically, the fourth electrode 34 is located on the second negative direction Y2 side relative to the second recess 22A.

[0027] 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 surface of the first flange portion 21 and the second flange portion 22. The plating layer is composed of three layers. The plating layer is stacked in sequence on the surface of the metal layer. In addition, the end face on the first positive direction X1 side of the coil component 10 is the mounting surface opposite to the substrate when the coil component 10 is mounted on the substrate.

[0028] like Figure 1 As shown, the coil component 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 11 of the drum-shaped core 10C.

[0029] Although not shown in the figure, the first wire 41 has a copper wire and an insulating film. The insulating film covers the outer surface of the copper wire. The first wire 41 is substantially circular in a cross section perpendicular to the direction in which the first wire 41 extends. The second wire 42 has the same structure as the first wire 41. That is, the second wire 42 has a copper wire and an insulating film. Figure 1In FIG. 1 , the first wire material 41 is colored with dots.

[0030] The first end 41A of the first wire 41 is connected to the first electrode 31. The second end 41B of the first wire 41 is connected to the third electrode 33. The first end 41A and the second end 41B are connected to the corresponding external electrodes 30 by thermocompression bonding.

[0031] Furthermore, the first wire rod 41 is wound around the winding core 11 so as to advance clockwise from the first wire end 41A side toward the second wire end 41B side when viewed in the third negative direction Z2.

[0032] The first end 42A of the second wire 42 is connected to the second electrode 32. The 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 bonding.

[0033] In addition, when viewed in the third negative direction Z2, the second wire 42 is wound around the winding core 11 in a clockwise manner as it moves from the first wire end 42A side to the second wire end 42B side. That is, the second wire 42 is wound in the same direction as the first wire 41. Moreover, the second wire 42 is wound around the winding core 11 from the outside relative to the first wire 41.

[0034] <About Adhesive>

[0035] like Figure 2 As shown, the adhesive 50 covers the entire surface of the first flange portion 21 facing the first negative direction X2. Moreover, the adhesive 50 connects the first flange portion 21 and the top plate 10F without a gap. Similarly, the adhesive 50 covers the entire surface of the second flange portion 22 facing the first negative direction X2. The adhesive 50 connects the second flange portion 22 and the top plate 10F without a gap. That is, the top plate 10F is connected to the two flange portions 20.

[0036] like Figure 3 As shown, the adhesive 50 contains bisphenol F type resin 51 as a synthetic resin. In addition, the adhesive 50 contains magnetic powder 52, a curing agent 53, a curing accelerator 54, a silane coupling agent 55 and a dispersant 56. In addition, Figure 3 The adhesive 50 shown in the figure shows the state before curing. Figure 3 In the figure, only a part of the magnetic powder 52, the curing agent 53, and the curing accelerator 54 are denoted by reference numerals.

[0037] Specifically, the adhesive 50 is manufactured as follows. First, a bisphenol F resin 51, a curing agent 53, a curing accelerator 54, a silane coupling agent 55, a dispersant 56, and a magnetic powder 52 are mixed at a rotation speed of 30 rpm for 5 minutes using a sand mixer (model: HIVIS MIX (registered trademark) 2P-03 (manufactured by PRIMIX)). Then, a disperser (model: EXAKT 80E (manufactured by Nagase Screen Printing Research Institute)) is used to mix at a gap of 6 μm and 230 rpm to manufacture the adhesive 50 before curing.

[0038] In the present 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 addition, in the present embodiment, both monomers and polymers are collectively referred to as bisphenol F type resin 51.

[0039] The number average molecular weight of bisphenol F type resin 51 is 312 g / mol. In addition, the number average molecular weight can be measured using GPC (model: HLC-8120GPC (manufactured by Tosoh Corporation)). In addition, GPC refers to gel permeation chromatography (Gel Permeation Chromatography). In the measurement using the device, the column temperature is 40°C. In addition, in the measurement, tetrahydrofuran is used as a solvent. The flow rate of the solution containing the solvent is 1.0 ml / min. In addition, the standard sample is monodisperse polystyrene.

[0040] In the present 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 the present 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, a cross section of the adhesive 50 is observed using an electron microscope. Then, within 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 with the calculated area is assumed. The diameter of the circle is calculated as the particle size of the magnetic powder 52.

[0041] In the particle size distribution of the magnetic powder 52, the median particle size (D50) is greater than or equal to 0.5 μm and less than or equal to 0.96 μm. The median particle size (D50) of the magnetic powder 52 is calculated, for example, as follows. First, the magnetic powder 52 is sampled by a scanning electron microscope to obtain a particle size distribution. Next, in the particle size distribution, the frequency of the particle size is accumulated from the smallest particle size to the largest particle size. The particle size when the cumulative value reaches 50% is set as the median particle size (D50).

[0042] The curing agent 53 is a curing agent for the bisphenol F type resin 51. In the present embodiment, the curing agent 53 is dicyandiamide. Specifically, the curing agent 53 is CAS No. 461-58-5.

[0043] The curing accelerator 54 is a curing accelerator for the bisphenol F type resin 51. In the present embodiment, the curing accelerator 54 is an amine adduct. Specifically, the curing accelerator 54 is CAS No. 134091-75-1.

[0044] The dispersant 56 is used to disperse the magnetic powder 52 in the adhesive 50. In the present embodiment, the dispersant 56 is a modified polymer containing a carboxyl group, and specifically, a modified polymer containing a carboxyl group having an acid value of 55 mgKOH / g.

[0045] In this embodiment, the silane coupling agent 55 is glycidoxypropyltrimethoxysilane. Specifically, the silane coupling agent 55 is CAS No. 253-83-8.

[0046] <About the cross section of the adhesive in the coil component>

[0047] In the state of the coil component 10, the adhesive 50 is in a cured state. The adhesive 50 is cured by, for example, firing at 100 degrees. In the cured adhesive 50, the bisphenol F type resin 51, the curing agent 53, and the curing accelerator 54 are polymerized to form a polymer. Moreover, the adhesive 50 is in a state in which the magnetic powder 52 is dispersed in the cured polymer having the bisphenol F type resin 51 as the main component.

[0048] like Figure 4 As shown in FIG. 1 , a cross section perpendicular to the bonding surface AS between the adhesive 50 and the drum-shaped core 10C is defined as a specific cross section. In the present embodiment, the specific cross section is a cross section along the first axis X and the second axis Y.

[0049] Here, the direction perpendicular to the bonding surface AS is set as the thickness direction. In addition, the direction perpendicular to the thickness direction in a specific cross section is set as the extension direction. In the present embodiment, the bonding surface AS is defined as follows. First, in a cross section including the adhesive 50 and the drum-shaped core 10C, in the area where the adhesive 50 contacts the drum-shaped core 10C, 10 points of contact between the adhesive 50 and the drum-shaped core 10C are determined at equal intervals. Figure 4 In FIG. 1 , the 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 square method. Then, the surface along the calculated approximate straight line is determined as the bonding surface AS. In addition, the thickness direction orthogonal to the bonding surface AS is also inclined relative to the first axis X.

[0050] In a specific cross-section, the dimension in the thickness direction of the end portion of the adhesive 50 in the extension direction is slightly larger than the dimension in the thickness direction of the central portion in the extension direction. In addition, in the specific cross-section, the average dimension H in the thickness direction of the adhesive 50 is greater than 1 μm and less than 11 μm. The average dimension H in the thickness direction of the adhesive 50 is calculated as follows. First, a specific cross-section is photographed using an electron microscope. Next, for the captured image, a range in the direction along the outer surface of the drum-shaped core 10C side of the adhesive 50 is specified. In this range, for a measurement range of at least 5 μm or more, the cross-sectional area of ​​the adhesive 50 is calculated by image processing. Then, the cross-sectional area of ​​the adhesive 50 within the calculated measurement range is divided by the length of the measurement range, thereby calculating the dimension in the thickness direction of the adhesive 50. That is, the average dimension H in the thickness direction of the adhesive 50 is the dimension within the measurement range. In addition, Figure 4 The average dimension H in the thickness direction shown is an example, and the dimension is not limited to the illustrated dimension.

[0051] like Figure 4 As shown, in a specific cross section, the adhesive 50 has two resin parts 60. Each resin part 60 is a part that does not contain magnetic powder 52 in the thickness direction between the drum-shaped core 10C and the top plate 10F in a specific cross section and continuously covers more than 3μm in the extension direction. In other words, the resin part 60 is a part where the minimum interval between the magnetic powders 52 in the extension direction is more than 3μm. In this embodiment, not containing magnetic powder 52 means that when a specific cross section is observed with a backscattered electron image of 1000 times using a scanning electron microscope, no magnetic powder 52 is detected. In this embodiment, the resin part 60 is mainly composed of bisphenol F type resin 51, and in addition, it also contains a curing agent 53, a curing accelerator 54, a silane coupling agent 55 and a dispersant 56. In addition, the curing agent 53, the curing accelerator 54, the silane coupling agent 55 and the dispersant 56 are sometimes contained in the resin part 60 in an unreacted state, and sometimes constitute a polymer together with the bisphenol F type resin 51.

[0052] One of the two resin portions 60 is located near the end portion on the second positive direction Y1 side of the adhesive 50 in a specific cross section. The other resin portion 60 is located near the end portion on the second negative direction Y2 side of the adhesive 50 in a specific cross section. That is, the resin portions 60 are present on both sides of the center of the adhesive 50 in the extension direction. The length P1 of one of the two resin portions 60 along the extension direction is about 7 μm. In addition, the length P2 of the other of the two resin portions 60 along the extension direction is about 15 μm. In addition, the lengths P1 and P2 of these resin portions 60 along the extension direction are examples, and they only need to be 3 μm or more.

[0053] In a specific cross section, the proportion of the resin portion 60 in the adhesive 50 is greater than 10%. The proportion of the resin portion 60 in the adhesive 50 is calculated as follows. First, a specific cross section is photographed using a scanning electron microscope. Next, for the photographed image, two points at the end in the extension direction of the bonding surface AS bonded to the drum-shaped core 10C are specified. Then, in the image, the length between the two points in the extension direction is specified. Next, for the photographed image, the total length of the resin portion 60 in the extension direction is specified. Then, the value obtained by dividing the total length of the specific resin portion 60 by the length between the two points at the end of the bonding surface AS is used as the proportion of the resin portion 60 in the adhesive 50.

[0054] In a specific cross section, the proportion of the magnetic powder 52 in the adhesive 50 is greater than 20% and less than 40%. The proportion of the magnetic powder 52 in the adhesive 50 is calculated as follows. First, for a specific cross section, an observation image is obtained using a scanning electron microscope with a backscattered electron image at 1000 times. Next, the obtained observation image is binarized. Next, in the observation image, a morphological processing, specifically a shrinkage processing, is performed to determine the outer edge of the magnetic powder 52. Next, for this image, the total cross-sectional area of ​​the magnetic powder 52 and the cross-sectional area of ​​the adhesive 50 as a whole are calculated by image processing. Then, the proportion of the magnetic powder 52 in the adhesive 50 is calculated by dividing the total cross-sectional area of ​​the magnetic powder 52 by the cross-sectional area of ​​the adhesive 50 as a whole.

[0055] <Regarding the growth of the resin portion during the curing process of the adhesive>

[0056] In one step of the manufacturing process of the coil component 10, the adhesive 50 before curing is applied to the drum-shaped core 10C. Specifically, the adhesive 50 before curing is applied to substantially the entire end surface of the first flange portion 21 on the first negative direction X2 side and substantially the entire end surface of the second flange portion 22 in the first negative direction X2. Then, the top plate 10F is attached to the drum-shaped core 10C via the adhesive 50. Then, the drum-shaped core 10C to which the top plate 10F is attached with the adhesive 50 is fired at a temperature above 100°C. At a temperature of around 100°C, the bisphenol F type resin 51 begins to cure with the curing agent 53 as the core. Then, during the curing process, the bisphenol F type resin 51 with the curing agent 53 as the core pushes the magnetic powder 52 away while expanding its curing range. As a result, the resin portion 60 is formed which does not contain the magnetic powder 52 and continuously extends over a thickness of 3 μm or more in the extending direction between the drum-shaped core 10C and the top plate 10F.

[0057] In addition, as described above, in a specific cross section, the dimension in the thickness direction of the end portion of the adhesive 50 in the extension direction is slightly larger than the dimension in the thickness direction of the central portion in the extension direction. Therefore, in the adhesive 50 before curing, the bisphenol F type resin 51 is likely to be retained at the end portion. As a result, the resin portion 60 is likely to be formed near the end portion of the adhesive 50 in the extension direction in the specific cross section.

[0058] <Effects of the present embodiment>

[0059] (1) In the above embodiment, the adhesive 50 contains the magnetic powder 52, thereby having a better magnetic permeability than a structure that does not contain the magnetic powder 52. In addition, in the adhesive 50 of the above structure, the resin portion 60 does not have the magnetic powder 52. In addition, the resin portion 60 extends over 3 μm or more in the extension direction. In this way, the resin portion 60 at the interface where the magnetic powder 52 does not exist exists in a block shape with a considerable length, thereby ensuring the bonding strength between the drum-shaped core 10C and the top plate 10F through the resin portion 60. In other words, it is possible to suppress the cohesive failure of the adhesive 50 that causes the top plate 10F to peel off from the drum-shaped core 10C.

[0060] (2) In the above embodiment, the magnetic powder 52 includes particles having a particle size of 0.1 μm or more and 11 μm or less. That is, by including the magnetic powder 52 having such a particle size, the magnetic permeability of the adhesive 50 is improved.

[0061] (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 component 10 has a closed magnetic circuit composed of the drum-shaped core 10C and the top plate 10F. Thus, as the adhesive 50 for bonding the drum-shaped core 10C and the top plate 10F constituting the closed magnetic circuit, the adhesive 50 of the above embodiment is used, which is particularly preferred in terms of improving the overall characteristics of the coil component 10.

[0062] (4) In the above embodiment, the drum-shaped core 10C and the top plate 10F are in direct contact with the adhesive 50. Assuming that other components are between the adhesive 50 and the drum-shaped core 10C, a structure for bonding the other components to the drum-shaped core 10C is required. That is, according to the above structure, since no additional structure for bonding is required, the size expansion of the coil component 10 can be suppressed. At this point, the top plate 10F is in direct contact with the adhesive 50, thereby achieving the same effect.

[0063] (5) In the above embodiment, the ratio of the resin portion 60 to the adhesive 50 in the specific cross section is 10% or more. The adhesive 50 having the resin portion 60 in such a ratio can more effectively suppress cohesive failure in the adhesive 50 .

[0064] (6) In the above embodiment, the ratio of magnetic powder 52 to adhesive 50 in a specific cross section is 20% to 40%. Adhesive 50 having resin portion 60 having magnetic powder 52 at such a ratio can ensure bonding strength and obtain good magnetic permeability.

[0065] (7) In the above embodiment, the adhesive 50 contains epoxy resin as the synthetic resin. In addition, the adhesive 50 contains dicyandiamide as the curing agent. By using these materials, the resin portion 60 can be formed efficiently.

[0066] (8) In the above embodiment, the synthetic resin of the adhesive 50 is bisphenol F type epoxy resin. According to this structure, the viscosity increase of the adhesive 50 before curing can be suppressed. As a result, for example, the generation of bubbles at the interface between the adhesive 50 and the drum-shaped core 10C and the top plate 10F can be suppressed.

[0067] (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. On the other hand, due to the increase in particle interfaces, there is a possibility that the passage of magnetic flux in the adhesive 50 is weakened. In the above embodiment, the median particle size (D50) of the magnetic powder 52 is greater than 0.5 μm and less than 0.96 μm. According to such a range of median particle size (D50), the filling rate of the magnetic powder 52 in the adhesive 50 can be increased. In addition, in the present embodiment, there is a high possibility that particles with a particle size of greater than 0.96 μm, that is, relatively large particles, are included. Therefore, the weakening of the passage of magnetic flux in the adhesive 50 can be suppressed.

[0068] (10) In the above embodiment, when observing a specific cross section, the average dimension H of the adhesive 50 in the thickness direction is greater than or equal to 1 μm and less than or equal to 11 μm. In the case where the dimension of the adhesive 50 in the thickness direction is too large, it is difficult to form the resin portion 60 between the drum-shaped core 10C and the top plate 10F. On the other hand, in the case where the dimension of the adhesive 50 in the thickness direction is too small, there is a concern that the bonding strength is reduced. According to the above structure, these problems can be effectively suppressed.

[0069] (11) In the above embodiment, when observing a specific cross section, the resin portion 60 exists on both sides of the center of the adhesive 50 in the extending direction. In this way, the resin portion 60 having relatively high adhesive strength exists on both sides, thereby making it difficult to produce 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. That is, the adhesive strength of the adhesive 50 can be made uniform, so it is possible to prevent the adhesive 50 from peeling off starting from a portion with low adhesive strength.

[0070] <Change Example>

[0071] The above-described embodiment and the following modified examples can be implemented in combination with each other within the scope of no technical contradiction.

[0072] <About changes related to coil components>

[0073] The shape of the winding core 11 is not limited to the example of the above-mentioned embodiment. For example, the shape of the winding core 11 may be a cylindrical shape, or a polygonal column shape other than a quadrangular column shape.

[0074] The structure of the drum-shaped core 10C is not limited to the example of the above-mentioned embodiment. For example, the drum-shaped core 10C may not include the first recess 21A and the second recess 22A. In this case, for example, 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-shaped core 10C may include at least the winding core 11 and the flange 20.

[0075] The material and shape of the external electrode 30 are not limited to the examples in the above-mentioned embodiment. For example, the material of the plating layer in the external electrode 30 may also be an alloy of tin and nickel. In addition, the external electrode 30 may not have a plating layer. In this case, the portion where the conductive metal layer is exposed can be used as the external electrode 30.

[0076] The coil component 10 only needs to include at least one wire rod. When the number of wire rods is one, one external electrode 30 may be provided on the first flange portion 21 and one external electrode 30 may be provided on the second flange portion 22 .

[0077] ·The coil component 10 is not limited to a structure having a drum-shaped core 10C and a top plate 10F. The coil component 10 only needs to have a first core for winding a wire and a second core connected to the first core via an adhesive 50. Moreover, the first core and the second core are bonded by the adhesive 50. In addition, the drum-shaped 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 portion 21 and the second flange portion 22 of the drum-shaped core 10C, and the adhesive 50 may be applied to the metal terminal. That is, in a case where the drum-shaped core 10C and the adhesive 50 are in contact with each other, it is also considered that the adhesive 50 bonds the drum-shaped core 10C and the top plate 10F. In this regard, the same is true when there are other components between the top plate 10F and the adhesive 50.

[0078] The material of the drum-shaped core 10C and the top plate 10F is not limited to the magnetic material, and may be, for example, a non-magnetic material such as alumina or synthetic resin.

[0079] In a specific cross section, the average dimension H of the adhesive 50 in the thickness direction may be smaller than 1 μm or larger than 11 μm.

[0080] In the specific cross section, the ratio of the resin portion 60 to 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.

[0081] The specific cross section is not limited to the example of the above embodiment. For example, the specific cross section may not be a cross section along the direction of the second axis Y. In addition, a cross section orthogonal to the bonding surface between the adhesive 50 and the second flange portion 22 may be set as the specific cross section.

[0082] In addition, in the above-mentioned embodiment, as long as there is one or more specific cross-sections of the resin part 60 observed, the adhesive 50 is deemed to have the resin part 60 in the specific cross-section. For example, in the case where the resin part 60 is cylindrical, in a certain specific cross-section, the minimum spacing between the magnetic powders 52 in the extension direction is sometimes less than 3 μm. Even in this case, as long as the minimum spacing between the magnetic powders 52 in the extension direction is 3 μm or more in other specific cross-sections, the adhesive 50 is deemed to have the resin part 60. In addition, in order to more effectively suppress the cohesive failure of the adhesive 50 such as the peeling of the drum-shaped core 10C and the top plate 10F, it is preferred that the minimum spacing between the magnetic powders 52 in the cross-section orthogonal to the bonding surface AS and orthogonal to the specific cross-section is also 3 μm or more. That is, the shape of the resin part 60 is more preferably a cylindrical shape with a diameter of 3 μm or more, and a columnar shape such as a quadrangular prism with a side of 3 μm or more.

[0083] <About changes related to adhesives>

[0084] The adhesive 50 may contain at least a synthetic resin, a magnetic powder 52, and a curing agent 53. The types of the synthetic resin, the magnetic powder 52, and the curing agent 53 are not limited to the examples in the above embodiment. The type of the curing agent 53 may correspond to the synthetic resin in the adhesive 50. For example, in the above embodiment, an amine adduct may be used as the curing agent 53, and the curing accelerator 54 may be omitted.

[0085] The number average molecular weight of the bisphenol F type resin 51 in the adhesive 50 is not limited to the example of the above embodiment. As long as the adhesive strength and viscosity are taken into consideration, the bisphenol F type resin 51 having an appropriately preferred number average molecular weight may be used.

[0086] The adhesive 50 may not 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 the examples of the above-mentioned embodiment.

[0087] The median particle size (D50) of the magnetic powder 52 in the adhesive 50 may be smaller than 0.5 μm or larger than 0.96 μm.

[0088] The magnetic powder 52 may not include particles having a particle size of 0.1 μm or more and 11 μm or less. In other words, the particle sizes of the magnetic powder 52 may all be smaller than 0.1 μm or larger than 11 μm.

[0089] In a specific cross section, the proportion of magnetic powder 52 in adhesive 50 may be less than 20% or greater than 40%. The proportion of magnetic powder 52 in adhesive 50 may be appropriately selected in consideration of the overall magnetic permeability and bonding strength of adhesive 50.

[0090] <Note>

[0091] The following describes technical ideas derived from the above-mentioned embodiments and modified examples.

[0092] [1] A coil component comprising: a first core; a second core; a wire material wound around the first core; and an adhesive interposed between the first core and the second core and bonding 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 section perpendicular to a bonding surface between the adhesive and the first core is set as a specific section, a direction perpendicular to the bonding surface is set as a thickness direction, and a direction perpendicular to the thickness direction in the specific section is set as an extension direction, in the specific section, the adhesive has a resin portion that continuously extends over a length of more than 3 μm in the extension direction in a portion that does not contain the magnetic powder between the first core and the second core in the thickness direction.

[0093] [2] The coil component according to [1], wherein the magnetic powder includes particles having a particle size of 0.1 μm or more and 11 μm or less.

[0094] [3] According to the coil component described in [1] or [2], the first core body comprises: a columnar winding core portion having a central axis; and two flange portions connected to both ends of the winding core portion along the direction of the central axis, and the second core body is connected to the two flange portions via the adhesive.

[0095] [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.

[0096] [5] The coil component according to any one of [1] to [4], wherein in the specific cross section, the ratio of the resin portion to the adhesive is 10% or more.

[0097] [6] The coil component according to any one of [1] to [5], wherein in the specific cross section, the ratio of the magnetic powder to the binder is 20% or more and 40% or less.

[0098] [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 dicyandiamide and amine adducts.

[0099] [8] According to the coil component described in [7], the above-mentioned synthetic resin is bisphenol F type epoxy resin.

[0100] [9] The coil component according to any one of [1] to [8], wherein the median particle size (D50) of the magnetic powder is 0.5 μm or more and 0.96 μm or less.

[0101]

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

Claims

1. A coil component, wherein: have: a first core; a second core; A wire is wound around the first core; as well as An adhesive is disposed between the first core and the second core to bond the first core and the second core. The adhesive contains synthetic resin, magnetic powder, and a curing agent for the synthetic resin. When a cross section perpendicular to the 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 formed so as to continuously extend over 3 μm or more in the extending direction at a portion not including the magnetic powder between the first core and the second core in the thickness direction.

2. The coil component according to claim 1, wherein The magnetic powder includes particles having a particle diameter of 0.1 μm or more and 11 μm or less.

3. The coil component according to claim 1 or 2, wherein: The first core has: A cylindrical winding core having a central axis; and Two flanges are connected to both ends of the winding core along the central axis. The second core is connected to the two flange portions via the adhesive.

4. The coil component according to any one of claims 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 claims 1 to 4, wherein: In the specific cross section, a ratio of the resin portion to the adhesive is 10% or more.

6. The coil component according to any one of claims 1 to 5, wherein: In the specific cross section, the ratio of the magnetic powder to the adhesive is 20% or more and 40% or less.

7. The coil component according to any one of claims 1 to 6, wherein: The synthetic resin is an epoxy resin, The curing agent includes at least one selected from dicyandiamide and amine adducts.

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

9. The coil component according to any one of claims 1 to 8, wherein: The median particle size of the magnetic powder, namely D50, is greater than or equal to 0.5 μm and less than or equal to 0.96 μm.

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

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