Coil component

Abstract

To provide a method for restraining deterioration of magnetic characteristics in a miniaturized coil component.SOLUTION: A coil component 1 includes a base 10 including a plurality of metal magnetic particles, and a coil conductor wound around a coil axis Ax in the base, the coil conductor having a first winding part 25a1 wound with a plurality of turns, and a second winding part 25b1 arranged below the first winding part 25a1 and wound with a plurality of turns. The base has a first magnetic portion 11 provided outside the coil conductor in a radial direction centered on the coil axis, and a second magnetic portion 12 provided inside the first magnetic portion in the radial direction. A first filling rate indicating the filling rate of metal magnetic particles in the first magnetic portion is 0.9 to 1.1 times of a second filling rate indicating the filling rate of metal magnetic particles in the second magnetic portion.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The disclosure herein relates primarily to coil components and methods of manufacturing coil components. [Background technology]

[0002] Coil components are mounted on various electronic devices. For example, coil components are used to remove noise from power lines and signal lines of circuits. A typical coil component includes a base body made of a magnetic material and a coil conductor provided on the base body.

[0003] The base described in JP 2021-163859 A has a magnetic core having a columnar portion that serves as a winding axis of a coil conductor, and an exterior member that covers the coil conductor. Such a coil component is produced by winding a coil conductor around the columnar portion of the magnetic core and providing an exterior member to cover the coil conductor. Both the magnetic core and the exterior member are formed by compression molding a mixed resin composition containing a resin and a magnetic powder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-163859 A Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for miniaturized coil components. As described in Patent Document 1, studies are being conducted on miniaturizing coil components by thinning the exterior member.

[0006] However, when producing an exterior member from the mixed resin composition, it becomes difficult to fill the thinned exterior member with the metal magnetic particles contained in the mixed resin composition, which results in a problem that the magnetic properties of coil components having a thinned exterior member are deteriorated.

[0007] It is an object of the invention disclosed herein to solve or alleviate at least some of the above-mentioned problems. A more specific object of the invention disclosed herein is to suppress deterioration of magnetic properties in a miniaturized coil component.

[0008] Objects of the invention disclosed in this specification other than those mentioned above will become apparent by referring to the entire specification. The invention disclosed in this specification may solve the problems understood from the description of this specification instead of or in addition to the above problems. [Means for solving the problem]

[0009] A coil component according to one or more embodiments of the present invention includes a base including a plurality of metal magnetic particles, and a coil conductor wound around a coil axis within the base. The base has a first magnetic portion provided outside the coil conductor in a radial direction centered on the coil axis, and a second magnetic portion provided inside the first magnetic portion in the radial direction. A first filling rate indicating the filling rate of the metal magnetic particles in the first magnetic portion is 0.9 to 1.1 times the second filling rate indicating the filling rate of the metal magnetic particles in the second magnetic portion. Effect of the Invention

[0010] According to one embodiment of the invention disclosed in this specification, it is possible to suppress the deterioration of magnetic characteristics in a miniaturized coil component. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view illustrating a coil component according to a first embodiment. [Diagram 2] 2 is a cross-sectional view that illustrates a schematic cross section of the coil component of FIG. 1 taken along line II. [Diagram 3] 2 is a cross-sectional view showing a first magnetic portion of a base body provided in the coil component of FIG. 1. [Figure 4]3 is an enlarged cross-sectional view showing a part of the cross section of FIG. 2 in an enlarged manner. [Diagram 5] FIG. 6 is a cross-sectional view showing a coil component according to a second embodiment. [Figure 6] 6 is a cross-sectional view showing a first magnetic portion of a base provided in the coil component of FIG. 5. [Figure 7] FIG. 11 is a cross-sectional view illustrating a coil component according to a third embodiment. [Figure 8] 8 is a cross-sectional view showing a first magnetic portion of a base provided in the coil device of FIG. 7. [Figure 9a] FIG. 2 is a schematic diagram for illustrating a step of preparing a mixed resin composition in the method for manufacturing the coil component. [Figure 9b] FIG. 4 is a schematic diagram illustrating a step of molding a first molded body in the method for manufacturing the coil component. [Figure 9c] 5A to 5C are schematic diagrams illustrating a step of placing a coil conductor in a method for manufacturing a coil component. [Figure 9d] FIG. 4 is a schematic diagram illustrating a step of molding a second molded body in the method for manufacturing the coil component. [Figure 9e] 5A to 5C are schematic diagrams illustrating a grinding step for exposing lead-out portions of coil conductors in a manufacturing method of the coil component. [Figure 9f] 5A to 5C are schematic diagrams for explaining a polishing step in the manufacturing method of the coil component. [Figure 9g] 5A to 5C are schematic diagrams illustrating a step of forming external electrodes in a manufacturing method of the coil component. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Various embodiments of the present invention will be described below with reference to the drawings as appropriate. Note that components common to multiple drawings are given the same reference numerals throughout the multiple drawings. Please note that the drawings are not necessarily drawn to scale for the sake of convenience. The embodiments of the present invention described below do not limit the invention according to the claims. Elements described in the following embodiments are not necessarily essential to the solution of the invention.

[0013] 1. First embodiment A coil component 1 according to a first embodiment of the present invention will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a perspective view of the coil component 1 according to the first embodiment of the present invention, and Fig. 2 is a vertical cross-sectional view of the coil component 1 mounted on a mounting substrate 2. The mounting substrate 2 is not shown in Fig. 1.

[0014] The drawings accompanying this specification show a W-axis, an L-axis, and a Z-axis that are perpendicular to each other. In this specification, unless otherwise understood in the context, the "length" direction, the "width" direction, and the "thickness" direction of the coil component 1 are defined as the "L-axis" direction, the "W-axis" direction, and the "T-axis" direction, respectively. In this specification, the orientation and arrangement of the components of the coil component 1 may be described based on the L-axis direction, the W-axis direction, and the Z-axis direction.

[0015] The coil component 1 can be used as an inductor, a transformer, a filter, a reactor, and various other inductance elements. The coil component 1 may also be a coupled inductor, a choke coil, and various other magnetically coupled coil components. Applications of the coil component 1 are not limited to those explicitly described in this specification.

[0016] 1, the coil component 1 includes an insulating base 10, a coil conductor 25 provided on the base 10, a first external electrode 21 provided on the surface of the base 10, and a second external electrode 22 provided on the surface of the base 10 at a position spaced apart from the first external electrode 21. In the illustrated embodiment, the coil conductor 25 is provided inside the base 10. For ease of explanation, the coil conductor 25 is illustrated in FIG. 1 through the base 10, the first external electrode 21, and the second external electrode 22.

[0017] As shown in Fig. 2, the coil component 1 may be mounted on a mounting board 2. The mounting board 2 is provided with land portions 3a and 3b. The coil component 1 is mounted on the mounting board 2 by joining the first external electrode 21 to the land portion 3a and connecting the second external electrode 22 to the land portion 3b. The mounting board 2 on which the coil component 1 is mounted may be mounted on various electronic devices. Electronic devices on which the mounting board 2 may be mounted include smartphones, tablets, game consoles, automotive electrical equipment, servers, and various other electronic devices.

[0018] The base 10 is made of a magnetic material and has a generally rectangular parallelepiped shape. In one embodiment of the present invention, the base 10 is configured so that the dimension (length dimension) in the L-axis direction is larger than the dimension (width dimension) in the W-axis direction and the dimension (height dimension) in the T-axis direction. In order to miniaturize the coil component 1, the base 10 is configured to be compact. For example, the length dimension of the base 10 is in the range of 0.5 mm to 3.0 mm, the width dimension is in the range of 0.5 mm to 3.0 mm, and the height dimension is in the range of 0.3 mm to 0.5 mm. The dimensions of the base 10 are not limited to the dimensions specifically described in this specification. In this specification, the term "rectangular parallelepiped" or "rectangular parallelepiped shape" does not mean only "rectangular parallelepiped" in the mathematically strict sense. The dimensions and shape of the base 10 are not limited to those explicitly described in this specification.

[0019] The base 10 has a first main surface 10a, a second main surface 10b, a first end surface 10c, a second end surface 10d, a first side surface 10e, and a second side surface 10f. The outer surface of the base 10 is defined by these six surfaces. The first main surface 10a and the second main surface 10b form the surfaces at both ends of the height direction of the base 10, the first end surface 10c and the second end surface 10d form the surfaces at both ends of the length direction of the base 10, and the first side surface 10e and the second side surface 10f form the surfaces at both ends of the width direction of the base 10. The upper surface 10a and the lower surface 10b are spaced apart by the height dimension of the base 10, the first end surface 10c and the second end surface 10d are spaced apart by the length dimension of the base 10, and the first side surface 10e and the second side surface 10f are spaced apart by the width dimension of the base 10. 1, the first main surface 10a is located on the upper side of the base 10, and therefore the first main surface 10a may be referred to as the "upper surface." Similarly, the second main surface 10b may be referred to as the "lower surface." The coil component 1 is disposed so that the second main surface 10b faces the substrate 2, and therefore the second main surface 10b may be referred to as the "mounting surface."

[0020] In the illustrated embodiment, each of the faces 10a-10f of the base 10 is illustrated as a flat surface, but each of the faces 10a-10f may be a curved surface. Also, each of the faces 10a-10f is illustrated as being perpendicular to the adjacent faces, but each of the faces 10a-10f may not be perpendicular to the adjacent faces. Each vertex of the base 10 may be rounded, and the ridgeline of the base 10 (the line showing the boundary between adjacent faces among the faces 10a-10f) may not be a straight line but may be curved according to the shape and arrangement of each of the faces 10a-10f.

[0021] The base 10 is made from a mixed resin composition containing magnetic powder and resin, for example, by compression molding. The magnetic powder is an aggregate of a large number of metal magnetic particles. In one embodiment, adjacent metal magnetic particles in the base 10 are bonded to each other via an insulating material. The insulating material is, for example, an insulating binder made of a thermosetting resin with excellent insulating properties, such as an epoxy resin. In this case, adjacent metal magnetic particles in the base 10 are bonded to each other by the binder. In one embodiment, the binder is a cured resin contained in the mixed resin composition.

[0022] At least a portion of the coil conductor 25 is spirally wound around the coil axis Ax. The coil axis Ax is an imaginary axis that intersects with the upper surface 10a and the lower surface 10b. The coil axis Ax may be, for example, an axis that extends along a straight line that passes through the geometric center of gravity of the upper surface 10a and the geometric center of gravity of the lower surface 10b when the coil component 1 is viewed from the T-axis direction. The coil axis Ax may extend in a direction perpendicular to the upper surface 10a and the lower surface 10b. In this specification, the direction along the coil axis Ax may be referred to as the "axial direction," and the direction perpendicular to the axial direction centered on the coil axis Ax may be referred to as the "radial direction."

[0023] In the illustrated embodiment, the coil conductor 25 has a first winding portion 25a1 wound around the coil axis Ax for a plurality of turns, a first lead-out portion 25a2 connected to one end of the first winding portion 25a1 and extending along the T-axis to the lower surface 10b of the base 10, a second winding portion 25b1 arranged below the first winding portion 25a1 and wound around the coil axis Ax for a plurality of turns, and a second lead-out portion 25b2 connected to one end of the second winding portion 25b1 and extending along the T-axis to the lower surface 10b of the base 10. An end of the first winding portion 25a1 opposite to an end connected to the first lead-out portion 25a2 is connected to an end of the second winding portion 25b1 opposite to an end connected to the second lead-out portion 25b2 via a connection portion (not shown). The coil conductor 25 may have a single-layer structure. When the coil conductor 25 has a single-layer structure, the coil conductor 25 does not need to have the second winding portion 25b1.

[0024] The lower end of the first lead portion 25a2 and the lower end of the second lead portion 25b2 are each exposed from the lower surface 10b to the outside of the base 10. The first lead portion 25a2 is connected to the first external electrode 21 at an end surface exposed from the lower surface 10b, and the second lead portion 25b2 is connected to the second external electrode 22 at an end surface exposed from the lower surface 10b.

[0025] In the illustrated embodiment, the first external electrode 21 is provided so as to contact the lower surface 10b, the first end surface 10c, the first side surface 10e, and the second side surface 10f of the base 10, but the shape and arrangement of the first external electrode 21 are not limited to the illustrated embodiment. For example, the first external electrode 21 may be provided on the base 10 so as to contact only the lower surface 10b of the base 10. In another embodiment, the first external electrode 21 may be provided on the base 10 so as to contact both the upper surface 10a of the base 10. The shape and arrangement of the second external electrode 22 are not limited to the illustrated embodiment. Like the first external electrode 21, the second external electrode 22 may also be provided on the base 10 so as to contact only the lower surface 10b of the base 10, or may also be provided on the base 10 so as to contact both the upper surface 10a of the base 10.

[0026] The coil conductor 25 is formed by coating a metal wire made of a metal material with excellent electrical conductivity with an insulating coating. For example, one or more of Cu, Al, Ni, and Ag, or an alloy containing any of these metals, can be used as the metal material for the coil conductor 25. The insulating coating provided around the conductor wire is made of, for example, polyesterimide, polyamide, or other insulating material with excellent insulating properties.

[0027] In the illustrated embodiment, the first winding portion 25a1 and the second winding portion 25b1 are each wound around the coil axis Ax for approximately three turns. Thus, the illustrated coil conductor 25 is wound around the coil axis Ax for a total of six turns. The number of turns of the coil conductor 25 is determined to be, for example, any number between 1 turn and 6 turns. In order to reduce the size of the coil component 1, the coil conductor 25 may be wound around the coil axis Ax for a small number of turns, for example, 6 turns or less. The number of turns of the coil conductor 25 may be 4 turns or less.

[0028] Next, a more detailed structure of the base 10 will be described mainly with reference to Figs. 2 to 4. The base 10 has a first magnetic part 11 and a second magnetic part 12. The first magnetic part 11 is provided outside the coil conductor 25 in the radial direction centered on the coil axis Ax. The first magnetic part 11 covers the outside of the coil conductor 25, and is therefore also called an exterior member. The second magnetic part 12 is provided inside the first magnetic part 11 in the radial direction. The cross section of the base 10 cut along the coil axis Ax is observed with a scanning electron microscope (SEM), and the first magnetic part 11 and the second magnetic part can be identified from the difference in contrast (brightness) of the electron microscope image obtained by this observation.

[0029] The first magnetic part 11 has a first base part 11a and a wall part 11b protruding from the first base part 11a toward the lower surface 10b along the T-axis direction. The first magnetic part 11 has a bottomed recess 11d recessed from the lower surface 10b toward the upper surface 10a. The recess 11d is defined by the first base part 11a and the wall part 11b.

[0030] The second magnetic part 12 is housed in the recess 11d of the first magnetic part 11. The second magnetic part 12 has a second base part 12a and a protruding part 12b that protrudes from the center of the second base part 12a toward the upper surface 10a along the T-axis direction. The lower surface 10b of the base body 10 is defined by the second base part 12a. The first winding part 25a1 and the second winding part 25b1 of the coil conductor 25 are wound around the protruding part 12b.

[0031] The first magnetic part 11 will be further described with reference to FIG. 3. The wall part 11b of the first magnetic part 11 protrudes from the periphery of the first base part 11a toward the lower surface 10b. Thus, the first end surface 10c, the second end surface 10d, the first side surface 10e, and the second side surface 10f of the base body 10 are defined by the outer peripheral surface of the wall part 11b. The upper surface 10a of the base body 10 is defined by the first base part 11a. The bottom surface 11a1 of the recess 11d is defined by a surface facing the upper surface 10a of the first base part 11a, and the side surface 11b1 of the recess 11d is defined by the inner peripheral surface of the wall part 11b.

[0032] The coil conductor 25 is housed in the recess 11d of the first magnetic part 11. The outer circumferential surface of the coil conductor 25 may be in contact with the side surface 11b1 of the first magnetic part 11. The outer circumferential surface of the coil conductor 25 may be spaced apart from the side surface 11b1 of the first magnetic part 11.

[0033] The microstructure of the coil component will be further described with reference to FIG. 4. When the coil component 1 is mounted on a mounting substrate 2, the distance T2 between the end face 11c of the wall 11b of the first magnetic part 11 and the surface of the mounting substrate 2 is greater than the distance T1 between the lower face 10b of the base 10 (the lower face of the second base part 12a of the second magnetic part 12) and the surface of the mounting substrate 2. In other words, the end face 11c of the wall 11b is recessed toward the upper face 10a side from the lower face 10b of the base 10. Since the end face 11c of the wall 11b is recessed from the lower face 10b of the base 10, a step may be generated between the end face 11c of the wall 11b and the lower face 10b of the base 10. In another embodiment, the end face 11c of the wall 11b may be smoothly connected to the lower face 10b of the base 10.

[0034] In one embodiment, the first surface roughness representing the surface roughness of the end face 11c of the wall portion 11b is greater than the second surface roughness representing the surface roughness of the upper face 10a, the first end face 10c, the second end face 10d, the first side face 10e, or the second side face 10f of the base 10. As described later, when the base 10 is produced by molding the mixed resin composition, the upper face 10a, the first end face 10c, the second end face 10d, the first side face 10e, and the second side face 10f are formed as molding surfaces that come into contact with a mold, and therefore are all formed smooth. In contrast, the end face 11c of the wall portion 11b is formed by the metal magnetic particles and resin in the molded body being dropped by barrel polishing, and therefore is a rough surface. Therefore, the first surface roughness representing the surface roughness of the end face 11c may be greater than any of the surface roughnesses of the upper face 10a, the first end face 10c, the second end face 10d, the first side face 10e, and the second side face 10f. On the other hand, the lower surface 10b is a surface formed by grinding the molded body in the manufacturing process in order to expose the end surface of the coil conductor 25, as described later, and is roughened by this grinding. Thus, in one embodiment, the first surface roughness representing the surface roughness of the end surface 11c of the wall portion 11b is smaller than the third surface roughness representing the surface roughness of the lower surface 10b. The surface roughness is an index indicating the smoothness of the surface, and means, for example, the "arithmetic mean roughness (Ra)" specified in JIS B 0601:2001. The arithmetic mean roughness can be calculated using a laser microscope equipped with a line roughness analysis function. Specifically, an image is captured from the surface of the observation target by the laser microscope, line segments of a reference length are extracted at 10 different positions in the image, and the arithmetic mean roughness of the extracted line segments can be calculated. As the laser microscope equipped with the line roughness analysis function, a commercially available microscope can be used.

[0035] In order to reduce the size of the coil component 1 in the radial direction, the wall 11b is thinned. When the size of the wall 11b in the radial direction is not uniform, it is preferable that the minimum wall thickness indicating the minimum value of the size of the wall 11b in the radial direction is 100 μm or less. The average wall thickness indicating the average size of the wall 11b in the radial direction may be 100 μm or less. In one embodiment, the minimum wall thickness of the wall 11b is larger than the average particle size of the first metal magnetic particles described later. By making the minimum wall thickness of the wall 11b larger than the average particle size of the first metal magnetic particles, the metal magnetic particles (first metal magnetic particles) can be filled in the wall 11b. It is preferable that the size of the wall 11b in the radial direction centered on the coil axis Ax is 100 μm or less. In order to further reduce the size of the coil component 1, it is preferable that the size of the wall 11b in the radial direction is 50 μm or less. The radial dimension of the wall portion 11b is desirably 10 μm or more to ensure the mechanical strength of the wall portion 11b. For example, in the example shown in FIG. 4, the dimension L0 of the wall portion 11b in the L-axis direction may be 100 μm or less. The wall portion 11b is provided on the radial outside of the coil conductor 25 so as to cover the coil conductor 25. The wall portion 11b covers the entire first winding portion 25a and the second winding portion 25b1 of the coil conductor 25 in the radial direction.

[0036] Next, the configurations of the first magnetic part 11 and the second magnetic part 12 will be described by comparing the two. First, the voids contained in the first magnetic part 11 and the second magnetic part 12 will be described. As described above, the first magnetic part 11 and the second magnetic part 12 are formed by compression molding a mixed resin composition containing a magnetic powder and a resin and curing the resin. A molded product formed by compression molding inevitably contains voids. In one embodiment, the first magnetic part 11 is formed to have fewer voids than the second magnetic part 12. By making the voids contained in the first magnetic part 11 less than the voids contained in the second magnetic part 12, the mechanical strength of the first magnetic part 11 can be improved. Since the wall part 11b of the first magnetic part 11 is thinned, it is easily peeled off from the outer circumferential surface of the coil conductor 25 or the second magnetic part 12 when the coil component 1 is mounted on the mounting board 2 or when the coil component 1 is handled. By reducing the content of voids in the first magnetic part 11 including the wall part 11b, the mechanical strength of the wall part 11b can be improved. This makes it possible to suppress damage to the wall portion 11b when the coil component 1 is mounted on the mounting board 2 or when the coil component 1 is handled.

[0037] The ratio of the voids contained in the first magnetic part 11 and the second magnetic part 12 can be expressed by a void ratio indicating the area ratio of the voids in each part. In one embodiment, in a cross section of the base 10 cut along a cut surface along the coil axis Ax, a first void ratio indicating the void ratio in the first magnetic part 11 is smaller than a second void ratio indicating the void ratio in the second magnetic part 12. When determining the void ratio, first, the base 10 is cut along its thickness direction (T-axis direction) to expose the cross section, and the cross section is photographed at a predetermined magnification (for example, 10,000 times) with a scanning electron microscope (SEM) to obtain an SEM image with a part of the cross section of the base 10 as an observation field. Next, the SEM image obtained by this photographing is subjected to image processing such as binarization processing to distinguish between voids and areas other than voids, and the area of ​​the area classified as voids is determined. Multi-value processing may be performed instead of binarization processing. The void areas in the observation field thus determined are then summed up, and the total void area in the observation field is divided by the area of ​​the observation field to calculate the void ratio. The void ratio expressed as a percentage is expressed by the following formula: Porosity (%) = (total area of ​​voids in the observation field / total area of ​​the observation field) x 100

[0038] The first magnetic part 11 may be formed from a first mixed resin composition containing a magnetic powder consisting of a plurality of first metal magnetic particles and a first resin, and the second magnetic part 12 may be formed from a first mixed resin composition containing a magnetic powder consisting of a plurality of second metal magnetic particles and a second resin. The first metal magnetic particles may be, for example, Fe-based metal magnetic particles made of a Fe-based soft magnetic material. The first metal magnetic particles may contain Si, Al, Cr, and other additive elements in addition to Fe. The second metal magnetic particles may have the same composition as the first metal magnetic particles, or may have a different composition from the first metal magnetic particles. The second resin may be the same type of resin as the first resin, or may be a different type of resin. The ratio of the metal magnetic particles in the first magnetic part 11 and the second magnetic part 12 may be 70 to 90 vol%. The ratio of the area not occupied by the metal magnetic particles in the first magnetic part 11 and the second magnetic part 12 may be 10 to 30 vol%. In the first magnetic portion 11 and the second magnetic portion 12, the areas not occupied by metal magnetic particles are occupied by a binder or voids.

[0039] Next, the filling rate of the metal magnetic particles in each of the first magnetic part 11 and the second magnetic part 12 will be described. As described above, the first magnetic part 11 and the second magnetic part 12 are formed from a mixed resin composition containing magnetic powder and resin, and therefore each of the first magnetic part 11 and the second magnetic part 12 contains metal magnetic particles. Since the wall part 11b of the first magnetic part 11 is thinned, metal magnetic particles are unlikely to enter the wall part 11b during the manufacture of the coil component 1. For this reason, in the conventional coil component, there is a problem that the filling rate of the metal magnetic particles in the part corresponding to the wall part 11b is low (for example, see paragraph

[0005] of the above-mentioned Patent Document 1). In contrast to this, in the coil component 1, the first filling rate indicating the filling rate of the metal magnetic particles in the first magnetic part 11 is the same or almost the same as the second filling rate indicating the filling rate of the metal magnetic particles in the second magnetic part 12, and specifically, is 0.9 times or more and 1.1 times or less. In one aspect, the first filling rate may be equal to or more than the second filling rate.

[0040] The filling rate of the metal magnetic particles in the first magnetic part 11 and the second magnetic part 12 can be calculated as follows. First, the substrate 10 is cut along the T axis to expose the cross section, and the cross section is photographed at a magnification of 10,000 times with a scanning electron microscope (SEM) to obtain an SEM image. Next, the region where the metal magnetic particles exist is identified from the brightness difference in this SEM image, and the area of ​​this region where the metal magnetic particles exist is measured. Then, the ratio of the area of ​​the region where the metal magnetic particles exist to the total area of ​​the observation field is calculated, and the calculated ratio expressed as a percentage is taken as the filling rate.

[0041] The problem in the prior art that metal magnetic particles are difficult to penetrate into a thinned portion of the first magnetic part 11 (for example, wall part 11b), resulting in a decrease in the filling rate of the metal magnetic particles in such a thinned portion, can be solved by molding the first magnetic part 11 prior to molding the second magnetic part 12 during the manufacture of the coil component 1. Details of a manufacturing method for improving the first filling rate will be described later. In one embodiment, by making a first average particle size indicating the average particle size of the first metal magnetic particles contained in the first magnetic part 11 smaller than a second average particle size indicating the average particle size of the second metal magnetic particles contained in the second magnetic part 12, the thinned wall part 11b can also be easily filled with metal magnetic particles, thereby improving the filling rate of the metal magnetic particles in the wall part 11b.

[0042] Next, the ratio of the binder contained in each of the first magnetic part 11 and the second magnetic part 12 will be described. As described above, in the first magnetic part 11 and the second magnetic part 12, the metal magnetic particles are bonded to each other via the binder. In the coil component 1, the binder ratio (first binder ratio) indicating the ratio of the binder in the first magnetic part 11 is greater than the binder ratio (second binder ratio) indicating the ratio of the binder in the second magnetic part 12. The binder ratio indicating the ratio of the binder in the first magnetic part 11 and the second magnetic part 12 can be calculated as follows. First, the base 10 is cut along the T axis to expose the cross section, and the cross section is photographed at a magnification of 10,000 times with a scanning electron microscope (SEM) to obtain an SEM image. Next, the region where the binder is present is identified from the brightness difference in this SEM image, and the area of ​​the region where the binder is present is measured. Then, the ratio of the area of ​​the region where the binder is present to the total area of ​​the observation field is calculated, and the calculated ratio expressed as a percentage is taken as the binder ratio.

[0043] In the first magnetic part 11, the ratio of the area occupied by the binder is greater than the ratio of the area occupied by the voids. In other words, the first binder ratio is greater than the first void ratio. Similarly, in the second magnetic part 12, the ratio of the area occupied by the binder is greater than the ratio of the area occupied by the voids. In other words, the second binder ratio is greater than the second void ratio.

[0044] The average particle size of the first metal magnetic particles contained in the first magnetic part 11 is obtained as follows. First, the substrate 10 is cut along its thickness direction (T-axis direction) to expose a cross section, and an SEM image of the region of the cross section corresponding to the first magnetic part 11 is obtained by photographing the region of the cross section at a magnification of about 10,000 to 50,000 times with a scanning electron microscope (SEM). Next, in the obtained SEM image, the circle equivalent diameter (Heywood diameter) of the metal magnetic particles is obtained by image analysis, and the average value of the circle equivalent diameters of each metal magnetic particle can be regarded as the average particle size of the first metal magnetic particles. The average particle size of the first metal magnetic particles may be determined by selecting a predetermined number (for example, 10) of metal magnetic particles in descending order of circle equivalent diameter from the multiple metal magnetic particles contained in the SEM image, and the average value of the circle equivalent diameters of the selected metal magnetic particles is regarded as the average particle size of the first metal magnetic particles. The average particle size of the first metal magnetic particles contained in the first magnetic part 11 may be 1 μm to 30 μm. The average particle size of the second metal magnetic particles contained in the second magnetic part 12 can be determined in the same manner as the average particle size of the first metal magnetic particles. The average particle size of the second metal magnetic particles contained in the second magnetic part 12 may be 0.5 μm to 5 μm.

[0045] As described above, in the coil component 1, by improving the filling rate of the metal magnetic particles in the wall portion 11b, the magnetic properties of the base 10 can be improved. In conventional coil components, the filling rate of the metal magnetic particles in a thinned portion such as the wall portion 11b is low, which has the problem of leading to deterioration of the magnetic properties. However, in the coil component 1, the filling rate (first filling rate) of the metal magnetic particles in the first magnetic portion 11 including the thinned wall portion 11b is set to be the same or nearly the same as the filling rate (second filling rate) of the metal magnetic particles in the second magnetic portion 12, thereby making it possible to suppress deterioration of the magnetic properties due to the thinned wall portion 11b.

[0046] Furthermore, according to the coil device 1, by increasing the filling rate of the metal magnetic particles in the wall portion 11b, the metal magnetic particles can be firmly bonded to each other within the wall portion 11b, thereby improving the mechanical strength of the wall portion 11b.

[0047] As described above, according to the coil device 1, the first porosity representing the porosity of the first magnetic portion 11 is smaller than the second porosity representing the porosity of the second magnetic portion 12, and therefore the mechanical strength of the first magnetic portion 11 is improved. Therefore, damage to the thinned wall portion 11b of the first magnetic portion 11 can be suppressed.

[0048] Furthermore, in coil component 1, end surface 11c of wall portion 11b is recessed from lower surface 10b of base 10, which makes it possible to prevent the end of wall portion 11b from colliding with mounting board 2 or a gripping member of a mounter when coil component 1 is mounted on mounting board 2 or when coil component 1 is handled. This makes it possible to further prevent damage to wall portion 11b when coil component 1 is mounted or handled.

[0049] 2. Second embodiment Next, a coil component 101 according to a second embodiment will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a vertical cross-sectional view of the coil component 101 according to the second embodiment, and Fig. 6 is a schematic cross-sectional view of a first magnetic portion 111 provided in the coil component 101. The coil component 101 differs from the coil component 1 in that the coil component 101 includes a first magnetic portion 111 instead of the first magnetic portion 11, and includes a second magnetic portion 112 instead of the second magnetic portion 12.

[0050] 6, the first magnetic part 111 has a first base part 111a and a wall part 111b protruding from the first base part 111a toward the lower surface 10b along the T-axis direction. The first magnetic part 111 has a recessed part 111d. The second magnetic part 112 is housed in the recessed part 111d of the first magnetic part 111.

[0051] The wall portion 111b has an outer peripheral surface extending along the T-axis direction and an inner peripheral surface 111b1 inclined relative to the outer peripheral surface. In one embodiment, in a cross section of the base 10 cut along the coil axis Ax, the angle of the inner peripheral surface 111b1 relative to the wall portion 111b is set to be 3° or more and 5° or less. The inner peripheral surface 111b1 of the wall portion 111b is inclined relative to the outer peripheral surface of the wall portion 111b so that the thickness in the vicinity of the first base portion 111a is thicker than the thickness in the vicinity of the end face 111c. More specifically, due to the inclination of the inner surface 111b1 relative to the outer surface of the wall portion 111b, a first wall thickness L1 indicating the radial dimension of the wall portion 111b at a first position in the axial direction along the coil axis Ax is thicker than a second wall thickness L2 indicating the radial dimension of the wall portion 111b at a second position that is distal from the first base 11a (closer to the lower surface 10b) than the first position in the axial direction.

[0052] Coil device 101 provides the following additional effect in addition to the same effect as coil device 1. That is, coil device 101 can improve the mechanical strength of the portion near the base of wall portion 111b (the portion near first base portion 111a), so that even if stress acts on wall portion 111b during mounting or handling of coil device 101, wall portion 111b is firmly supported near the base, and therefore damage to wall portion 111b can be suppressed.

[0053] 3. Third embodiment Next, a coil component 201 according to a third embodiment will be described with reference to Fig. 7 and Fig. 8. Fig. 7 is a vertical cross-sectional view of the coil component 201 according to the third embodiment, and Fig. 8 is a schematic cross-sectional view of a first magnetic portion 211 provided in the coil component 201. The coil component 201 differs from the coil component 101 in that the coil component 201 includes a first magnetic portion 211 instead of the first magnetic portion 111, and includes a second magnetic portion 212 instead of the second magnetic portion 112.

[0054] 8, the first magnetic part 211 has a first base part 211a and a wall part 211b protruding from the first base part 211a toward the lower surface 10b along the T-axis direction. The first magnetic part 211 has a recessed part 211d. The second magnetic part 212 is housed in the recessed part 211d of the first magnetic part 211.

[0055] The inner circumferential surface 211b1 of the wall portion 211b is not flat but has projections and recesses. The projections and recesses are defined by at least one small protrusion 213 and at least one small recess 214 formed on the inner circumferential surface 211b1 of the wall portion 211b. The inner circumferential surface 211b1 of the wall portion 211b may have a plurality of small protrusions 213 and a plurality of small recesses 214 as the projections and recesses. In the illustrated embodiment, the inner circumferential surface 211b1 has two small protrusions 213 and two small recesses 214 as the projections and recesses. In a cross section of the base 10 cut along the coil axis Ax, a virtual line Bx is assumed that connects the position where the lower end of the wall 211b contacts the second magnetic portion 212 and the position where the wall 211b intersects with the first base portion 211a, and the portion of the wall 211b that is radially inward from the virtual line Bx is the small convex portion 213, and the portion of the wall 211b that is radially outward from the virtual line Bx is the small concave portion 214. The height of the small convex portion 213 based on the virtual line Bx is larger than the average particle size of the first metal magnetic particles contained in the first magnetic portion 211. The height of the small convex portion 213 means the length of a perpendicular line drawn from the portion of the wall 211b that is the furthest radially inward from the virtual line Bx to the virtual line Bx. The depth of the small recess 214 based on the virtual line Bx is larger than the average particle size of the first metal magnetic particles contained in the first magnetic part 211. The depth of the small recess 214 means the length of a perpendicular line drawn from the wall part 211b located at the most distal part from the virtual line Bx toward the inside in the radial direction to the virtual line Bx. In a cross section of the base 10 cut along the coil axis Ax, the vicinity of the boundary between the first magnetic part 211 and the second magnetic part 212 is set as an observation field, and this observation field is observed by a scanning electron microscope (SEM). The first magnetic part 211 and the second magnetic part 212 can be distinguished from each other based on the difference in contrast (brightness) of the electron microscope image obtained by this observation. At this time, it can be confirmed that unevenness larger than the average particle size of the first metal magnetic particles occurs at the boundary between the first magnetic part 211 and the second magnetic part 212.

[0056] The small convex portion 213 and the small concave portion 214 may be provided over the entire inner circumferential surface 211b1 of the wall portion 211b, or may be provided only in a partial region of the inner circumferential surface 211b1. For example, the small convex portion 213 and the small concave portion 214 may be provided in a region of the inner circumferential surface 211b1 of the wall portion 211b that is closer to the lower surface 10b (the end surface 211 side c) than the midpoint in the T-axis direction, and may not be provided in a region of the inner circumferential surface 211b1 that is closer to the upper surface 10a than the midpoint.

[0057] The coil device 201 provides the following additional effect in addition to the same effect as the coil device 101. That is, according to the coil device 201, the unevenness provided on the inner circumferential surface 211b1 of the wall portion 211b increases the bonding strength between the first magnetic portion 211 and the second magnetic portion 212. Therefore, even if a force in the T-axis direction acts on the second magnetic portion 212 when the coil device 201 is mounted, handled, or used, the first magnetic portion 211 can be prevented from peeling off from the second magnetic portion 212.

[0058] 4 Manufacturing method Next, an example of a method for manufacturing the coil component 1 will be described with reference to Fig. 9a to Fig. 9g. First, as shown in Fig. 9a, a first mixed resin composition containing a magnetic powder consisting of a plurality of first metal magnetic particles and a first resin is molded into a plate shape, and the plate-shaped mixed resin composition is semi-cured to obtain a semi-cured body M1, which is set so as to cover the cavity of a mold 301. The semi-cured body M1 is a molded body containing a plurality of first metal magnetic particles and a semi-cured first resin. The first resin is a thermosetting resin with excellent insulating properties, such as epoxy resin, benzocyclobutene (BCB), phenol resin, unsaturated polyester resin, vinyl ester resin, polyimide resin (PI), polyphenylene ether oxide resin (PPO), bismaleimide triazine cyanate ester resin, fumarate resin, polybutadiene resin, polyvinyl benzyl ether resin, or the like.

[0059] Next, the punch 302 is lowered to push the semi-hardened body M1 into the cavity of the mold 301, and the mold 301 and the punch 302 press the semi-hardened body M1. Thereafter, the punch 302 is raised to obtain a first molded body M11 having a shape corresponding to the cavity of the mold 301, as shown in FIG. 9b. The first molded body M11 has a bottom M11a and a side wall M11b. The first molded body M11 has a recess defined by the bottom M11a and the side wall M11b. By adjusting the dimensions of the mold 301 and the punch 302, the dimension of the side wall M11b can be set in the range of 10 μm to 100 μm.

[0060] The first molded body M11 may be produced without using the semi-cured body M1. For example, the first molded body M11 may be produced from a mixed resin composition by transfer molding or any other known molding method.

[0061] Next, as shown in FIG. 9c, a coil conductor 25 that has been prepared in advance is set in the recess of the first compact M11.

[0062] Next, as shown in FIG. 9d, a second mixed resin composition containing a magnetic powder consisting of a plurality of second metal magnetic particles and a second resin is filled into the recess of the first molded body M11, and the filled second mixed resin composition is pressed together with the first molded body M11 and the coil conductor 25 by a punch (not shown). The second mixed resin composition may be molded into a plate shape, and the plate-shaped mixed resin composition may be semi-cured to obtain a semi-cured body, which may be set on the recess of the first molded body M11, and the semi-cured body may be pushed into the recess of the first molded body M11 by a punch. The average particle size of the second metal magnetic particles contained in the second mixed resin composition is preferably larger than the average particle size of the first metal magnetic particles contained in the second mixed resin composition. The second resin is a thermosetting resin with excellent insulating properties. The second resin may be the same type of resin as the first resin, or may be a different type of resin. By pressurizing the second mixed resin composition that has entered the recesses of the first molded body M11, the second resin contained in the second mixed resin composition reaches the first molded body M11 through the gaps in the coil conductor 25 and penetrates into the inside of the first molded body M11. Therefore, the gaps in the first molded body M11 are filled with the second resin, and the porosity of the first molded body M11 is reduced. Instead of pressurizing the second mixed resin composition that has entered the recesses of the first molded body M11, the second mixed resin composition may be heated at a temperature equal to or lower than the curing temperature of the second resin to melt the second resin in the second mixed resin composition, and the molten second resin may penetrate into the inside of the first molded body M11 through the gaps in the coil conductor 25. Both pressurization and heating may be performed on the second mixed resin composition.

[0063] By heating the first molded body M11 and the second mixed resin composition filled in the recesses of the first molded body M11 at a molding temperature equal to or higher than the curing temperature of the first resin and the second resin, the first magnetic portion 11 is formed from the first molded body M11, and the second magnetic portion 12 is formed from the second mixed resin composition filled in the recesses of the first molded body M11. When an epoxy resin is used as the first resin and the second resin, the molding temperature can be about 150°C. In one embodiment, the compression molding of the second mixed resin composition and the curing of the first resin and the second resin are performed in parallel by applying a molding temperature equal to or higher than the curing temperature of the first resin and the second resin during compression molding of the second mixed resin composition. In another aspect, the second mixed resin composition filled in the recess of the first molded body M11 is pressurized at a temperature below the curing temperature of the first resin and the second resin to form a second molded body M12 contained in the recess of the first molded body M11, and then the first molded body M11 and the second molded body M12 are baked at a temperature above the curing temperature of the first resin and the second resin to form a first magnetic part 11 from the first molded body M11 and a second magnetic part 12 from the second molded body M12.

[0064] Next, the intermediate compact 51 including the first magnetic part 11 and the second magnetic part 12 formed as described above is removed from the mold 301, and one surface of the intermediate compact 51 is ground with a cutting blade or a laser to expose the end surface of the coil conductor 25 from the second magnetic part 12. This grinding results in the intermediate compact 52 shown in FIG. 9e. In the intermediate compact 52, one end surface and the other end surface of the coil conductor 25 are exposed from the second magnetic part 12. The intermediate compact 52 has a roughly rectangular parallelepiped shape.

[0065] Next, the intermediate compact 52 is subjected to barrel polishing to round off the corners and ridges of the intermediate compact 52. In this barrel polishing, the metal magnetic particles and resin near the tip of the wall portion 11b of the first magnetic portion 11 tend to fall off from the intermediate compact 52, so that after the barrel polishing, the tip of the wall portion 11b recedes from the surface of the second magnetic portion 12 (the surface where the end face of the coil conductor 25 is exposed) as shown in Fig. 9f.

[0066] Next, as shown in FIG. 9g, a conductive paste is applied to cover one end face of the coil conductor 25 and a first region of the end face 11c of the wall portion 11b, thereby forming a first external electrode 21, and a conductive paste is applied to cover the other end face of the coil conductor 25 and a second region of the end face 11c of the wall portion 11b, thereby forming a second external electrode 22. The first external electrode 21 and the second external electrode 22 are formed to cover the end face of the coil conductor 25 exposed from the second magnetic portion 12 and the end face 11c at the tip of the wall portion 11b. This conductive paste contains a conductive material with excellent conductivity, such as Ag, Pd, Cu, Al, Ni, or an alloy thereof. A plating layer may be formed on each surface of the first external electrode 21 and the second external electrode 22. This plating layer may be two or more layers. The two plating layers may include a Ni plating layer and a Sn plating layer provided on the outside of the Ni plating layer.

[0067] In the above manner, the coil component 1 is manufactured. According to the above manufacturing method, the first compact M11, which is the precursor of the first magnetic portion 11, is molded before the second mixed resin composition, which is the raw material of the second magnetic portion 12, is added, so that even if the wall portion 11b is thinned, the filling of the first metal magnetic particles into the wall portion 11b is not hindered. Therefore, the wall portion 11b can contain the first metal magnetic particles at a high filling rate, so that the deterioration of the magnetic properties caused by the insufficient filling rate of the first metal magnetic particles in the wall portion 11b can be suppressed. In addition, the wall portion 11b can contain the first metal magnetic particles at a high filling rate, so that the mechanical strength of the wall portion 11b can be improved. In addition, according to the above manufacturing method, the wall portion 11b can contain the first metal magnetic particles and the resin at a high filling rate, so that the mechanical strength of the wall portion 11b can be improved.

[0068] In addition, according to the above manufacturing method, the second mixed resin composition in the recess of the first molded body M11 is pressurized and / or heated, so that the second resin in the second mixed resin composition penetrates into the voids inside the first molded body M11, thereby reducing the porosity of the first molded body M11. This also reduces the porosity of the first magnetic part 11 formed by curing the first molded body M11. Therefore, the above manufacturing method can improve the mechanical strength of the first magnetic part 11, and in particular, the mechanical strength of the thinned wall part 11b can be improved. By reducing the porosity of the wall part 11b and increasing the filling rate of the first metal magnetic particles, the mechanical strength of the wall part 11b can be further improved.

[0069] According to the above manufacturing method, by performing barrel polishing on the intermediate molded body 52 including the first magnetic part 11 and the second magnetic part 12, the end face 11c of the thinned wall part 11b can be recessed from the lower face 10b of the base 10, so that it is possible to prevent the end of the wall part 11b from colliding with the mounting board 2 or the gripping member of the mounter when mounting the coil component 1 on the mounting board 2 or handling the coil component 1. This makes it possible to prevent damage to the wall part 11b when mounting or handling the coil component 1. Furthermore, by making the thickness of the end face 11c of the wall part 11b 100 μm or less, when performing barrel polishing on the intermediate molded body 52, the part of the intermediate molded body 52 that is the precursor of the wall part 11b is easily removed, so that the end face 11c of the wall part 11b can be recessed farther than the lower face 10b of the base 10, and the entire wall part 11b can be recessed.

[0070] Furthermore, according to the above manufacturing method, since more metal magnetic particles can be dropped off at the tip of the wall portion 11b of the first magnetic portion 11 by barrel polishing, the surface roughness of the end face 11c of the wall portion 11b can be made larger than the surface roughness of the upper face 10a, the first end face 10c, the second end face 10d, the first side face 10e, or the second side face 10f of the base 10. Since the first external electrode 21 and the second external electrode 22 are each formed so as to cover the end face 11c of the wall portion 11b, the first external electrode 21 and the second external electrode 22 can be firmly joined to the base 10.

[0071] Furthermore, according to the above manufacturing method, among the outer surfaces that define the base 10, the top surface 10a, the first end surface 10c, the second end surface 10d, the first side surface 10e, and the second side surface 10f can be formed as smooth molded surfaces by a mold. Therefore, defects and insulation deterioration due to processing such as grinding do not occur in the top surface 10a, the first end surface 10c, the second end surface 10d, the first side surface 10e, and the second side surface 10f. In this way, according to the above manufacturing method, five of the six surfaces of the base 10 (surfaces other than the bottom surface 10b) can be formed smoothly.

[0072] Some of the steps included in the above manufacturing method may be omitted as appropriate. In the manufacturing method of the coil component 1, steps not explicitly described in this specification may be performed as necessary. Some of the steps included in the manufacturing method of the coil component 1 may be performed in a different order as needed, as long as the steps do not deviate from the spirit of the present invention. Some of the steps included in the manufacturing method of the coil component 1 may be performed simultaneously or in parallel, if possible.

[0073] In the above manufacturing method, instead of the mold 301, the intermediate molded body 51 can be formed using a frame partly made of resin having a recess or through hole of the same shape as the cavity of the mold 301. By molding the raw material using a frame partly made of resin, the side of the molded body is less likely to be scratched when the molded body is removed from the frame part made of resin. By reducing scratches on the side of the molded body, the insulation of the surface of the coil component manufactured from the molded body can be increased, and there is an advantage that the mechanical strength is increased because there are fewer structural defects on the surface. In addition, since the post-processing can be performed while the molded body is held in the frame body, the manufacturing process can be made more efficient and highly accurate. When manufacturing small coil components (e.g., one side is 2 mm or less), it is difficult to handle the extremely small intermediate body (molded body) generated in the manufacturing process. However, by manufacturing the coil components using a frame partly made of resin, the intermediate bodies can be handled collectively. Therefore, by using a frame partly made of resin for manufacturing small coil components, the manufacturing process can be made more efficient and highly accurate.

[0074] 4 Notes The dimensions, materials, and arrangements of each component described in the various embodiments above are not limited to those explicitly described in each embodiment, and each component can be modified to have any dimensions, materials, and arrangements that may fall within the scope of the present invention.

[0075] Components not explicitly described in this specification may be added to each of the above-described embodiments, and some of the components described in each embodiment may be omitted.

[0076] The designations "first," "second," "third," and the like in this specification are given to identify components, and do not necessarily limit the number, order, or content. Furthermore, numbers for identifying components are used in different contexts, and a number used in one context does not necessarily indicate the same configuration in another context. Furthermore, a component identified by a certain number does not prevent the component from also having the function of a component identified by another number.

[0077] 5. Supplementary Notes The embodiments disclosed herein also include the following. [Appendix 1] A substrate including a plurality of metal magnetic particles; a coil conductor wound around a coil axis within the base; Equipped with the base body has a first magnetic portion provided outside the coil conductor in a radial direction centered on the coil axis, and a second magnetic portion provided inside the first magnetic portion in the radial direction, a first filling rate indicating the filling rate of the metal magnetic particles in the first magnetic portion is 0.9 to 1.1 times a second filling rate indicating the filling rate of the metal magnetic particles in the second magnetic portion; Coil parts. [Appendix 2] The first filling rate is equal to or greater than the second filling rate. A coil component described in [Appendix 1]. [Appendix 3] a first average particle size indicating an average particle size of the first metal magnetic particles contained in the first magnetic portion among the plurality of metal magnetic particles is smaller than a second average particle size indicating an average particle size of the second metal magnetic particles contained in the second magnetic portion; A coil component according to [Appendix 1] or [Appendix 2]. [Appendix 4] the base has a first surface that intersects with the coil axis and a second surface that faces the first surface, the first magnetic portion has a recess recessed from the first surface toward the second surface, The second magnetic portion is accommodated in the recess. A coil component according to any one of [Appendix 1] to [Appendix 3]. [Appendix 5] The first magnetic portion has a first base portion that defines a bottom surface of the recess, and a wall portion that protrudes from the first base portion along the coil axis toward the first surface. A coil component according to any one of [Appendix 1] to [Appendix 4]. [Appendix 6] A minimum wall thickness indicating the minimum value of the dimension of the wall in the radial direction centered on the coil axis is 100 μm or less. A coil component according to any one of [Appendix 1] to [Appendix 5]. [Appendix 7] the second magnetic portion has a second base portion that defines at least a portion of the first surface of the base body, and a protrusion portion that protrudes from the second base portion toward the first surface, The coil conductor is wound around the protrusion. A coil component according to any one of [Appendix 1] to [Appendix 6]. [Appendix 8] the base has a third surface connecting the first surface and the second surface and a fourth surface opposing the third surface, the third surface and the fourth surface are defined by an outer circumferential surface of the wall portion, A side surface of the recess is defined by an inner circumferential surface of the wall portion, The inner circumferential surface of the wall portion is inclined with respect to the outer circumferential surface of the wall portion such that a first wall thickness indicating a dimension of the wall portion in a radial direction centered on the coil axis at a first position in the axial direction along the coil axis is thicker than a second wall thickness indicating a dimension of the wall portion in the radial direction at a second position in the axial direction that is closer to the first surface than the first position. A coil component according to any one of [Appendix 1] to [Appendix 7]. [Appendix 9] A side surface of the recess is defined by an inner circumferential surface of the wall portion, The inner circumferential surface is formed with projections and recesses. A coil component according to any one of [Appendix 1] to [Appendix 8]. [Appendix 10] the coil conductor has a winding portion extending in a circumferential direction around the coil axis, a first lead-out portion extending from one end of the winding portion to the first surface, and a second lead-out portion extending from the other end of the winding portion to the first surface, The wall portion covers the winding portion of the coil conductor from the radially outer side. A coil component according to any one of [Appendix 1] to [Appendix 9]. [Appendix 11] the coil conductor has a winding portion extending in a circumferential direction around the coil axis, a first lead-out portion extending from one end of the winding portion to the first surface, and a second lead-out portion extending from the other end of the winding portion to the first surface, The winding portion is wound around the coil shaft by fewer than six turns. A coil component according to any one of [Appendix 1] to [Appendix 10]. [Appendix 12] The winding portion is wound around the coil shaft by fewer than four turns. A coil component according to any one of [Appendix 1] to [Appendix 11]. [Appendix 13] a first external electrode provided on at least the first surface of the base and connected to the first lead portion; a second external electrode provided on at least the first surface of the base and connected to the second lead portion; A coil component according to any one of [Appendix 1] to [Appendix 12]. [Explanation of symbols]

[0078] 1, 101, 201 Coil parts 10 Base 11, 111, 211 First magnetic part (exterior member) 11a 1st base 11b, 111b, 211b wall section 11c, 111c, 211c end face 12, 112, 212 2nd magnetic part

Claims

1. A substrate including a plurality of metal magnetic particles; a coil conductor wound around a coil axis within the base; Equipped with the base body has a first magnetic portion provided outside the coil conductor in a radial direction centered on the coil axis, and a second magnetic portion provided inside the first magnetic portion in the radial direction, a first filling rate indicating the filling rate of the metal magnetic particles in the first magnetic portion is 0.9 to 1.1 times a second filling rate indicating the filling rate of the metal magnetic particles in the second magnetic portion; Coil parts.

2. The first filling rate is equal to or greater than the second filling rate. The coil component according to claim 1 .

3. a first average particle size indicating an average particle size of the first metal magnetic particles contained in the first magnetic portion among the plurality of metal magnetic particles is smaller than a second average particle size indicating an average particle size of the second metal magnetic particles contained in the second magnetic portion; The coil component according to claim 1 .

4. the base body has a first surface intersecting the coil axis and a second surface opposite to the first surface, the first magnetic portion has a recess recessed from the first surface toward the second surface, The second magnetic portion is accommodated in the recess. The coil component according to claim 1 .

5. The first magnetic portion has a first base portion that defines a bottom surface of the recess, and a wall portion that protrudes from the first base portion along the coil axis toward the first surface. The coil component according to claim 4 .

6. A minimum wall thickness indicating the minimum value of the dimension of the wall in the radial direction centered on the coil axis is 100 μm or less. The coil component according to claim 5 .

7. the second magnetic portion has a second base portion that defines at least a portion of the first surface of the base body, and a protrusion portion that protrudes from the second base portion toward the first surface, The coil conductor is wound around the protrusion. The coil component according to claim 4 .

8. the base has a third surface connecting the first surface and the second surface and a fourth surface opposing the third surface, the third surface and the fourth surface are defined by an outer circumferential surface of the wall portion; A side surface of the recess is defined by an inner circumferential surface of the wall portion, an inner circumferential surface of the wall portion is inclined with respect to an outer circumferential surface of the wall portion such that a first wall thickness indicating a dimension of the wall portion in a radial direction centered on the coil axis at a first position in the axial direction along the coil axis is thicker than a second wall thickness indicating a dimension of the wall portion in the radial direction at a second position in the axial direction that is closer to the first surface than the first position; The coil component according to claim 5 .

9. A side surface of the recess is defined by an inner circumferential surface of the wall portion, The inner circumferential surface is formed with projections and recesses. The coil component according to claim 5 .

10. the coil conductor has a winding portion extending in a circumferential direction around the coil axis, a first lead-out portion extending from one end of the winding portion to the first surface, and a second lead-out portion extending from the other end of the winding portion to the first surface, The wall portion covers the winding portion of the coil conductor from the radially outer side. The coil component according to claim 5 .

11. the coil conductor has a winding portion extending in a circumferential direction around the coil axis, a first lead-out portion extending from one end of the winding portion to the first surface, and a second lead-out portion extending from the other end of the winding portion to the first surface, The winding portion is wound around the coil shaft by fewer than six turns. The coil component according to claim 4 .

12. The winding portion is wound around the coil shaft by fewer than four turns. The coil component according to claim 11.

13. a first external electrode provided on at least the first surface of the base body and connected to the first lead portion; a second external electrode provided on at least the first surface of the base and connected to the second lead portion; The coil component according to claim 12 , further comprising:

Images