JP2023136455A - Coil component, circuit board, electronic equipment, and method for manufacturing coil component - Google Patents

Abstract

To provide a coil component with good magnetic saturation characteristics.SOLUTION: A coil component according to an embodiment includes a circulating portion made of a circulating conductor, and a magnetic substrate that includes a first magnetic portion formed by bonding first metal particles having a particle size distribution in which the first particle size is D90, which represents a particle size of 90% of the cumulative volume, and a second magnetic portion formed by bonding second metal particles having a particle size distribution in which D90 is a second particle size larger than the first particle size to enclose the circulating portion, and includes at least a portion of the first magnetic portion on the outer circumferential side with respect to the circulating portion.SELECTED DRAWING: Figure 4

Description

The present invention relates to a coil component, a circuit board, an electronic device, and a method for manufacturing a coil component.

The characteristics required for coil parts differ depending on the application. When magnetic saturation characteristics are required, Mn-Zn-based ferrite materials are used as the magnetic material, and when miniaturization of the component size is desired, metal magnetic materials are used as the magnetic material. is increasingly being used.

A typical coil component using a metal magnetic material is a coil component called a metal composite, which uses a composite magnetic material in which Fe-based metal magnetic particles and resin are mixed. This type of coil component is being miniaturized to, for example, an external dimension of 2 mm.

Coil parts that use metal magnetic materials are manufactured through a process in which a composite magnetic material made by mixing metal magnetic particles and resin is hardened by applying pressure. Due to this, the filling rate of metal magnetic particles is limited. For this reason, coil parts in which metal magnetic materials are used have low relative permeability as a magnetic body, and their applications are more restricted than coil parts in which ferrite magnetic materials are used. For example, coil components using metallic magnetic materials may not be suitable for applications that require high inductance characteristics.

Coil components using metallic magnetic materials are required to have a wider range of applications by increasing their relative magnetic permeability. As one method for increasing the relative magnetic permeability, a technique has been proposed in which the filling rate of a metal magnetic material is increased by applying high pressure.

In addition, in order to obtain inductance characteristics in coil parts that use metal magnetic materials, the influence of the magnetic material part that exists inside the circulating part of the conductor (circulating part) is large, and the area of the inner magnetic material part is It is known that it is effective to increase the

For example, Patent Document 1 proposes a technique in which the size of the magnetic material is adjusted by polishing or the like so that the areas of the magnetic material portions on the inside and outside of the coil are approximately the same.

Japanese Patent Application Publication No. 2013-183052

In recent years, it has been found that when looking at the magnetic material as a whole, the magnetic material located outside the circumferential portion cannot be used effectively. The reason for this is that while the external shape of a normal magnetic material is a rectangular parallelepiped, the external shape of the surrounding part is circular or elliptical, and the magnetic flux is partially non-uniform due to the difference in the external shape. by. In many cases, the corner portions of a rectangular parallelepiped magnetic material do not take advantage of their original magnetic properties.
However, if the inner side of the circumferential portion is made larger so that the external shape of the circumferential portion is similar to the external shape of the magnetic material, the length of the conductor forming the circumferential portion becomes long, resulting in high resistance. In other words, simply enlarging the circumferential portion will not improve the performance of the coil component.
This situation significantly affects the characteristics of the coil component as the filling rate increases, the area of the core increases, and further downsizing progresses. One particularly significant effect is that the magnetic flux becomes non-uniform on the outside of the circumferential portion, resulting in local concentration of magnetic flux. As a result, the coil component becomes susceptible to magnetic saturation.
Therefore, an object of the present invention is to provide a coil component with good magnetic saturation characteristics.

In order to solve the above problems, a coil component according to one aspect of the present invention includes a circulating part made of a circulating conductor and a coil part having a particle size distribution in which D90, which represents a particle size of 90% of the cumulative volume, is a first particle size. a first magnetic part formed by bonding one metal particle; and a second magnetic part formed by bonding a second metal particle having a particle size distribution in which D90 is a second particle size larger than the first particle size. and a magnetic base that encloses the circumferential portion and includes at least a portion of the first magnetic portion on the outer peripheral side of the circumferential portion.

Further, according to the coil component according to one aspect of the present invention, on the outer circumferential side of the circumferential portion of the magnetic base, a portion of the magnetic substrate having the thinnest thickness in a direction toward and away from the circumferential portion is close to the circumferential portion. The first magnetic portion is included within one half of the side.
Further, according to the coil component according to one aspect of the present invention, on the outer peripheral side of the circumferential portion of the magnetic base, the thickness in the direction toward and away from the circumferential portion is the thinnest, half of the thickness. The above portion is occupied by the first magnetic portion.

Further, according to the coil component according to one aspect of the present invention, at least a portion of the second magnetic portion is located further outside the first magnetic portion, which is included on the outer peripheral side of the circumferential portion.
Further, according to the coil component according to one aspect of the present invention, the short side of the outer shape is 1.0 mm or less.
Further, a circuit board according to one aspect of the present invention includes any of the above coil components and a substrate on which the above coil components are mounted.
Further, an electronic device according to one aspect of the present invention includes the above circuit board.

Further, a method for manufacturing a coil component according to one aspect of the present invention is a manufacturing method for manufacturing any of the above-described coil components, which includes a step of arranging a circumferential portion made of a circumferential conductor, and a step of arranging a circumferential portion made of a circumferential conductor; , a step of forming the first magnetic part to have a thickness three times or more the second grain size, and a step of forming the first magnetic part at a location on the outer peripheral side of the location where the circumferential part is arranged, the first magnetic part being three times or less the second grain diameter. in any order, and at least one of the step of forming the first magnetic part and the step of forming the second magnetic part includes forming the magnetic part integrally with the surrounding part. This is a step of forming a base.

Further, according to the method for manufacturing a coil component according to one aspect of the present invention, at least one of the step of forming the first magnetic part and the step of forming the second magnetic part involves bonding of metal particles by heat treatment. It is a process that includes
Further, according to the method for manufacturing a coil component according to one aspect of the present invention, the step of forming the magnetic substrate is a step that includes bonding the first magnetic part and the second magnetic part by heat treatment.

According to the present invention, a coil component with good magnetic saturation characteristics can be obtained.

FIG. 1 is a perspective view showing a coil component according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the coil component shown in FIG. 1. FIG. It is a figure which shows the coil component of a modification. FIG. 2 is a cross-sectional view of a magnetic base in the coil component shown in FIG. 1. FIG. FIG. 3 is a schematic enlarged view showing the microscopic structure of the first magnetic part. FIG. 3 is a schematic enlarged view showing the microscopic structure of the second magnetic part. It is a figure showing the first stage of a manufacturing process of a coil component. FIG. 3 is a schematic enlarged view of region R1. It is a figure which shows the 2nd stage of the manufacturing process of a coil component. It is a figure which shows the 3rd stage of the manufacturing process of a coil component. FIG. 3 is a schematic enlarged view of region R2. It is a figure which shows the 4th stage of the manufacturing process of a coil component. It is a figure which shows the 1st stage of the manufacturing process in 2nd Embodiment. It is a figure which shows the 2nd stage of the manufacturing process in 2nd Embodiment. It is a figure which shows the 3rd stage of the manufacturing process in 2nd Embodiment. It is a figure which shows the 4th stage of the manufacturing process in 2nd Embodiment. It is a figure which shows the 1st stage of the manufacturing process in 3rd Embodiment. It is a figure which shows the 2nd stage of the manufacturing process in 3rd Embodiment. It is a figure which shows the 3rd stage of the manufacturing process in 3rd Embodiment. It is a figure which shows the 4th stage of the manufacturing process in 3rd Embodiment. It is a figure which shows the 1st stage of the manufacturing process in 4th Embodiment. It is a figure which shows the 2nd stage of the manufacturing process in 4th Embodiment. It is a figure which shows the 3rd stage of the manufacturing process in 4th Embodiment.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that the following embodiments do not limit the present invention, and not all combinations of features described in the embodiments are essential to the configuration of the present invention. The configuration of the embodiment may be modified or changed as appropriate depending on the specifications of the device to which the present invention is applied and various conditions (conditions of use, environment of use, etc.).

The technical scope of the invention is defined by the claims, and is not limited by the following individual embodiments. The drawings used in the following explanation may differ in scale, shape, etc. from the actual structure in order to make each structure easier to understand. Components shown in the drawings described above may be referred to as appropriate in the description of the drawings that follow.

<Structure of coil parts>
FIG. 1 is a perspective view showing a coil component according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the coil component shown in FIG. 2(A) shows a cross section taken along line AA shown in FIG. 1, and FIG. 2(B) shows a cross section taken along line BB shown in FIG. 2(A). ing.
Coil component 1 is mounted on substrate 2a. For example, two land portions 3 are provided on the substrate 2a. Coil component 1 has one magnetic base 11 and two external electrodes 12. The coil component 1 is mounted on the substrate 2a by joining each external electrode 12 and the land portion 3 with solder. A circuit board 2 according to an embodiment of the present invention includes a coil component 1 and a substrate 2a on which the coil component 1 is mounted. The circuit board 2 is included in various electronic devices. Examples of electronic devices including the circuit board 2 include electrical components of automobiles, servers, board computers, and various other electronic devices.
The coil component 1 may be an inductor, a transformer, a filter, a reactor, or various other coil components. The coil component 1 may be a coupled inductor, a choke coil, or various other magnetically coupled coil components. The coil component 1 may be, for example, an inductor used in a DC/DC converter. The uses of the coil component 1 are not limited to those specified in this specification.

In this specification, unless otherwise understood from the context, directions will be described with reference to the "L axis" direction, "W axis" direction, and "H axis" direction in FIG. These are referred to as the "length" direction, "width" direction, and "height" direction. The "height" direction may also be referred to as the "thickness" direction.

The coil component 1 has a rectangular parallelepiped outer shape. That is, the coil component 1 has a first end surface 1a and a second end surface 1b at both ends in the length direction, and a first main surface 1c (upper surface 1c) and a second main surface 1d at both ends in the height direction. (bottom surface 1d), and has a front surface 1e and a rear surface 1f at both ends in the width direction.

The first end surface 1a, the second end surface 1b, the first main surface 1c, the second main surface 1d, the front surface 1e, and the rear surface 1f of the coil component 1 may be flat planes or curved surfaces. It may be a curved surface. Furthermore, the eight corners and 12 ridgeline portions of the coil component 1 may be rounded.

In this specification, a case where a part of the first end surface 1a, second end surface 1b, first main surface 1c, second main surface 1d, front surface 1e, and rear surface 1f of the coil component 1 is curved Also, even when the corners and ridges of the coil component 1 are rounded, such a shape may be referred to as a "cuboid shape." That is, in the present specification, the term "cuboid" or "cuboid shape" does not mean a "cuboid" in a mathematically strict sense.

The coil component 1 in one embodiment of the present invention has a conductor 14 inside a magnetic base 11 . The conductor 14 has a circumferential portion 14 a that circulates inside the magnetic base 11 and a lead-out portion 14 b that is drawn out from the circumferential portion 14 a and connected to the external electrode 12 .

The conductor 14 is formed of a conductive wire including a metal wire such as Ag or Cu and an insulating film provided on the surface of the metal wire. Alternatively, the conductor 14 is formed by covering a metal wire formed by plating with an insulating film. For example, the number of turns of the conductor 14 in the circumferential portion 14a is one turn or more, and when the lead-out portions 14b are provided at positions facing each other around the circumferential portion 14a, the number of turns is 1.5 turns, 2.5 turns, etc. This includes the number of laps that are less than one turn.
In the example shown in FIG. 2, the winding portion 14a is made of a conducting wire that runs around the top surface 1c and bottom surface 1d of the coil component 1, and has a so-called horizontally wound structure.

As shown in FIG. 2(B), the external electrode 12 is, for example, a so-called L-shaped electrode, and has a portion extending from the bottom surface 1d to the first end surface 1a, and a portion extending from the bottom surface 1d to the second end surface 1b. It is formed.
The external electrode 12 is made of a metal such as Ag, Cu, Ti, Ni, or Sn, and has a thickness of 1 to 5 μm, for example. Alternatively, the external electrode 12 may be formed by a combination of multiple types of metal layers, and the total thickness of the combination is 5 to 10 μm. Further, the external electrode 12 may be formed by a combination of metal layers that partially contain resin, and the total thickness of the combination is 10 to 20 μm.

The magnetic base 11 is formed of metal particles containing Fe, Ni, or Co. The magnetic base 11 may contain resin, metal oxide, and ceramic material in addition to metal particles. The metal particles forming the magnetic substrate 11 have soft magnetic properties and are also referred to as metal magnetic particles. In addition to Fe, Ni, and Co, the metal particles may contain any one of Si, Cr, Al, B, and P, or may contain a plurality of Si, Cr, Al, B, and P. The magnetic base 11 may be formed of a combination of multiple types of metal particles.

Further, the shape of the metal particles forming the magnetic substrate 11 is not particularly limited, but is spherical or nearly spherical, and has a particle size of, for example, 1 to 60 μm, and has a certain degree of particle size distribution. The metal particles may be insulated. When the magnetic substrate 11 further contains other particles such as fine metal particles, metal oxides, and ceramic materials having smaller particle sizes, the size of the other particles is 0.01 to 1 μm. When the magnetic substrate 11 contains other particles, the other particles contribute to, for example, reducing voids or supplementing mechanical strength rather than enhancing the magnetic function.

The metal particles forming the magnetic substrate 11 are bound together by a binder such as a resin, a metal oxide, a ceramic material, or the like. The magnetic base 11 contains 85 vol% or more of metal particles, and may further contain 88 vol% or more, with the remainder being an insulating material other than metal particles.
The magnetic base 11 may be a powder compact in which metal particles are bonded to each other without a binder. The material of the magnetic base 11 is not limited to those specified in this specification, and any material known as a material for a magnetic base may be used.

The coil component 1 has an external shape with one side of 4.0 mm or less, 2.0 mm or less, or even 1.0 mm or less when viewed from the height direction H, and a height of 2.0 mm, 1.0 mm, or even 0 mm. .65mm or less. Further, the external shape viewed from the height direction H may be a square or a rectangle, and the height may be smaller than one side. Further, when the outer shape as viewed from the height direction H is a rectangle, the short side is 3.0 mm or less, further 1.0 mm or less.

Here, a modification of the coil component 1 will be described.
FIG. 3 is a diagram showing a modified example of the coil component 1. The shape of the external electrode 12 of the coil component 1 in FIG. 3 is different from the shape of the external electrode 12 of the coil component 1 in FIG.
In the case of the modified example, the coil component 1 is formed with, for example, five-sided electrode type external electrodes 12 that cover both ends of the magnetic base 11 in the length direction L, respectively. The coil component 1 is mounted on the substrate 2a by joining each external electrode 12 and the land portion 3 with solder. The circuit board 2 includes a coil component 1 and a substrate 2a on which the coil component 1 is mounted.

Further, the conductor 14 (not shown) inside the magnetic base 11 has a so-called perpendicular winding structure, which is wound along the first end surface 1a and the second end surface 1b of the coil component 1.
The contribution of each portion of the magnetic base 11 to the magnetic properties of the coil component 1 is mainly determined by the positional relationship with the circumferential portion 14a of the conductor 14. In other words, when the portions of the magnetic substrate 11 are distinguished based on their contribution to the magnetic properties, they are distinguished from, for example, an inner circumferential portion surrounded by the circumferential portion 14a, an outer circumferential portion surrounding the outside of the circumferential portion 14a, and the conductor 14 is horizontal. The same applies to both winding and vertical winding. Therefore, the following explanation will be continued using the example of horizontal winding shown in FIGS. 1 and 2.

<Structure of magnetic substrate>
FIG. 4 is a cross-sectional view of the magnetic base 11 in the coil component 1 shown in FIGS. 1 and 2. FIG. The cross-sectional view in FIG. 4 shows a cross section at the same location as the cross-sectional view in FIG. 2(B), but the illustration focuses on the detailed structure of the magnetic base 11.
The magnetic base 11 includes a first magnetic part 11a and a second magnetic part 11b, and encloses a circumferential part 14a. In the example shown in FIG. 4, the first magnetic part 11a is provided on the outer peripheral side of the circumferential part 14a, and the second magnetic part 11b is provided at a location other than the first magnetic part 11a.

FIG. 5 is a schematic enlarged view showing the microscopic structure of the first magnetic part 11a, and FIG. 6 is a schematic enlarged view showing the microscopic structure of the second magnetic part 11b.
The first magnetic part 11a has a structure in which first metal particles 11c are bonded to each other. The first metal particles 11c have a particle size distribution, and in the particle size distribution, the particle size D90 at which the volume accumulation is 90% is 5 to 20 μm. The particle size D90 of the first metal particles 11c is hereinafter referred to as a first particle size.

The second magnetic part 11b has a structure in which second metal particles 11d are bonded to each other. The second metal particles 11d have a particle size distribution, and in the particle size distribution, the particle size D90 at which the volume accumulation is 90% is 10 to 100 μm. The particle size D90 of the second metal particles 11d is hereinafter referred to as a second particle size.
Since the second particle size is larger than the first particle size, the first magnetic part 11a has higher magnetic saturation characteristics than the second magnetic part 11b, and the second magnetic part 11b has a higher magnetic saturation characteristic than the first magnetic part 11a. High magnetic permeability.
Moreover, the second particle size is larger than 1.5 times and smaller than 3 times the first particle size. By arranging the first metal particles and the second metal particles such that both relative magnetic permeability and magnetic saturation characteristics are improved, the inductance and magnetic saturation performance of the coil component can be maximized.

The particle size D90 of the metal particles is determined using, for example, a laser diffraction type particle size distribution measuring device. Alternatively, the particle size D90 of the metal particles may be determined by observing a cross section of the magnetic substrate 11 using, for example, an optical microscope, measuring particles having a size of 1 μm or more, and calculating from the measurement results.

As shown in FIG. 4, by providing the first magnetic portion 11a on the outer peripheral side of the circumferential portion 14a, the magnetic saturation characteristics of the coil component 1 are improved. By improving the magnetic saturation characteristics, it is possible to reduce the area of the magnetic base 11 on the outer circumferential side of the winding part 14a when viewed in a plane perpendicular to the coil axis of the winding part 14a, so that the coil component 1 can also be made smaller. It becomes possible. Furthermore, since the magnetic base 11 has both the first magnetic part 11a and the second magnetic part 11b, it is possible to improve the magnetic saturation characteristics and maintain high relative magnetic permeability, and the performance as the coil component 1 is improved. do. In other words, since the performance of the coil component 1 is maintained, the size of the coil component 1 can also be reduced.

At least a part of the first magnetic part 11a may be provided on the outer circumferential side of the circumferential part 14a, and another part of the first magnetic part 11a may be provided on the inner circumferential side of the circumferential part 14a. In the example shown in FIG. 4, the second magnetic part 11b is provided further on the outer peripheral side of the first magnetic part 11a located on the outer peripheral side of the circumferential part 14a. The first magnetic part 11a may be provided on the outer peripheral side of the second magnetic part 11b.

Note that if the first magnetic part 11a is provided on the inner circumferential side than the second magnetic part 11b, the first magnetic part 11a will be provided at a location near the circumferential part 14a where magnetic saturation is likely to occur, and the coil component 1 will be Improves magnetic saturation characteristics. Moreover, the relative magnetic permeability is improved by locating the second magnetic part 11b on the outer peripheral side of the first magnetic part 11a, and the inductance characteristics of the coil component 1 are improved.

If at least a part of the first magnetic part 11a is included within half of the outer circumferential side of the circumferential part 14a on the circumferential part 14a side, the magnetic saturation characteristics of the coil component 1 are improved compared to the case where it is not included. do.
If the first magnetic part 11a occupies half or more of the thickness of the magnetic base 11 on the outer peripheral side of the circumferential part 14a, the magnetic saturation characteristics of the coil component 1 will be improved compared to the case where it does not occupy the first magnetic part 11a.

Note that among the portions of the magnetic base 11 located on the outer circumferential side of the surrounding portion 14a, the portions having the thinnest thickness in the direction toward and away from the surrounding portion 14a (for example, the portion shown in FIG. 4) are the parts in the coil component 1. This is the part that most affects magnetic properties. For this reason, it is desirable that the above-described arrangement of the first magnetic portion 11a be realized particularly at a portion where the thickness of the magnetic base 11 is the thinnest. The thinnest portion of the magnetic base 11 has a thickness of, for example, 0.1 mm or less, and further 0.05 mm or less.

When the external shape of the magnetic substrate 11 is rectangular, it is desirable that the circumferential portion 14a has an elliptical shape with a major axis and a minor axis. It is desirable that the elliptical shape of the circumferential portion 14a is arranged such that the short axis and the short side are aligned with each other and the long side and the long axis are aligned with each other with respect to the external shape of the magnetic base 11. In this arrangement, it is desirable that the first magnetic part 11a be provided along the outer periphery of the surrounding part 14a between the long side of the magnetic base 11 and the ellipse of the surrounding part 14a. By providing the first magnetic portion 11a in this manner, the magnetic saturation characteristics of the magnetic substrate 11 are improved in a wide range along the long sides of the magnetic substrate 11, and the magnetic saturation characteristics of the coil component 1 are also improved.

In addition, the magnetic base 11 may have a third magnetic part (not shown) in addition to the first magnetic part 11a and the second magnetic part 11b. The magnetic material of the third magnetic part may be a magnetic material with the same components as the first magnetic part 11a, a magnetic material with the same components as the second magnetic part 11b, or the first magnetic part 11a and the second magnetic part 11b. The magnetic material may have a different component from both of the magnetic parts 11b.

<Manufacturing method of coil parts>
The method for manufacturing the coil component 1 will be described below, focusing on the process of manufacturing the magnetic base 11.
The magnetic base 11 is made from a molded body in which a composite material in which metal particles and resin are mixed to form the first magnetic part 11a and the second magnetic part 11b is compression molded or warm molded. . Hereinafter, formation by compression molding or warm molding will be simply referred to as "molding." The pressure during molding of the magnetic substrate 11 is 10 MPa to 1 GPa, and the temperature is 10 to 200°C.

Molding of the molded body in manufacturing the magnetic substrate 11 may be performed by combining both pressure and heat, and by combining pressure and heat, molding can be performed at a relatively low pressure of 10 to 100 MPa. Examples of molding methods that combine pressure and heat include sheet molding and transfer molding.
In forming the molded body in manufacturing the magnetic substrate 11, for example, the composite material for each of the first magnetic part 11a and the second magnetic part 11b is made by a particle size blending method in which multiple types of metal particles having different particle sizes are combined. By being prepared, the first magnetic part 11a and the second magnetic part 11b having the desired particle size can be obtained. That is, a first composite material containing first metal particles 11c having a first particle size of D90 and a second composite material containing second metal particles 11d having a second particle size of D90 are each prepared in a particle size composition. . The first composite material is used to mold the first magnetic part 11a, and the second composite material is used to mold the second magnetic part 11b.

Alternatively, in the molding of the molded body in manufacturing the magnetic substrate 11, for example, a flow control method that adjusts the molding thickness and the size of the metal particles may be used to form the first magnetic part 11a with the desired particle size and the first magnetic part 11a with the desired particle size. Two magnetic parts 11b are obtained. In other words, during molding, the flow of metal particles with a larger particle size is restricted in areas where the molding thickness is small, so the metal particles contained in the areas where the molding thickness is small end up being larger metal particles. This is due to a decrease in the proportion of Specifically, the first magnetic part 11a is molded with a thickness less than three times the D90 of the metal particles included in the composite material, and the second magnetic part 11b is molded with a thickness three times or more with respect to the D90. be done.

Hereinafter, the specific manufacturing process of the coil component 1 will be explained with reference to the drawings.
7 to 12 are diagrams showing the manufacturing process of the coil component 1. Each of FIGS. 7, 9, and 10 shows a top view (A) and a sectional view (B) showing a cross section taken along line CC in the top view (A). FIG. 8 shows a schematic enlarged view of region R1 shown in FIG. 7, and FIG. 11 shows a schematic enlarged view of region R2 shown in FIG. FIG. 12 shows a cross-sectional view corresponding to the cross-sectional view shown in FIG. 2(B).
In a specific example of the manufacturing process of the coil component 1, the magnetic base 11 is formed separately into a bottom portion 111 on the bottom surface 1d side of the coil component 1 and an upper portion 112 on the top surface 1c side of the coil component 1.

For example, as shown in FIG. 7, a bottom portion 111 is first formed. The bottom portion 111 includes a bottom plate portion 111a that extends along the bottom surface 1d of the coil component 1, and a protrusion portion 111b that projects from the bottom plate portion 111a toward the top surface 1c of the coil component 1 in an elliptical shape. The elliptical shape of the protrusion 111b is such that the circumferential portion 14a of the conductor 14 just fits therein.

The bottom portion 111 is formed by filling the composite material into a mold corresponding to the shapes of the bottom plate portion 111a and the protruding portion 111b. For example, when the bottom part 111 is formed by a flow control method, the metal particles included in the composite material are the second metal particles 11d having a second particle size D90, and the bottom plate part 111a is formed by the second metal particles 11d. becomes the second magnetic part 11b combined.

On the other hand, the thickness d1 (FIG. 8) of the protruding portion 111b is formed to be less than three times the second particle size, and the flow of particles having a large particle size among the second metal particles 11d is restricted. That is, into the part of the mold corresponding to the protruding portion 111b having the thickness d1, small metal particles flow without restriction, whereas large metal particles are restricted from flowing into the mold. As a result, the particle size distribution of the metal particles forming the protrusions 111b changes from the particle size distribution of the second metal particles 11d, and the protrusions 111b are formed by the first metal particles having the first particle size with D90 smaller than the second particle size. 11c becomes the first magnetic part 11a combined.

In forming the bottom portion 111, the first metal particles 11c and the second metal particles 11d may be bonded together by heat treatment. The bonding of the metal particles by heat treatment increases the strength of the bottom portion 111 and strengthens the bond between the bottom plate portion 111a and the protruding portion 111b (that is, the bond between the first magnetic portion 11a and the second magnetic portion 11b).
As shown in FIG. 9, the conductor 14 is arranged inside the elliptical protrusion 111b of the molded body of the bottom 111. As shown in FIG. Note that in the following, for convenience, only the circumferential portion 14a may be illustrated as a representative of the conductor 14.

Thereafter, as shown in FIG. 10, an upper part 112 is molded on the bottom part 111 and the conductor 14 to obtain a molded body 110 that is integrated with the conductor 14. The molded body 110 becomes the magnetic base 11. The upper part 112 has an upper plate part 112a that extends along the upper surface 1c of the coil component 1, and a core part 112b and an outer edge part 112c that protrude from the upper plate part 112a toward the bottom surface 1d. The core portion 112b protrudes from the upper plate portion 112a on the inner circumferential side of the circumferential portion 14a, and the outer edge portion 112c protrudes from the upper plate portion 112a on the outer circumferential side of the circumferential portion 14a.

For example, a mold having the shape of the upper surface 1c of the upper part 112 is placed over the bottom part 111 and the conductor 14, and the mold is filled with the composite material to form the upper part 112. In the molding of the upper part 112, there is no particular restriction on the thickness, and the molding is performed to a sufficient thickness that is three times or more thicker than the second particle size. That is, even in the region R2 where the thickness is the thinnest in the upper portion 112, the thickness d2 is three times or more the second grain size. Therefore, as shown in FIG. 11, the entire upper portion 112 including the thinnest portion of the outer edge portion 112c becomes the second magnetic portion 11b to which the second metal particles 11d are bonded.

In addition, in the example mentioned above, the bottom part 111 and the upper part 112 are molded with the same composite material, but the bottom part 111 and the upper part 112 may be molded with different composite materials. For example, the bottom portion 111 may be formed of a composite material containing the first metal particles 11c, and the upper portion 112 may be formed of a composite material containing the second metal particles 11d. In this case, the entire bottom part 111 becomes the first magnetic part 11a, and the upper part 112 becomes the second magnetic part 11b.
Moreover, in this case, the first magnetic part 11a may be formed thicker than the second magnetic part 11b on the outer circumferential side of the circumferential part 14a, and the first magnetic part 11a on the outer circumferential side of the circumferential part 14a may be formed to be thicker than the second magnetic part 11b. It can occupy more than half of the thickness of 11.

The molded body 110 that is integrated with the conductor 14 and becomes the magnetic base 11 may be further subjected to heat treatment. The heat treatment strengthens the bond between the bottom portion 111 and the top portion 112, and improves the integrity of the conductor 14 and the magnetic substrate 11.
After the magnetic base 11 integrated with the conductor 14 is obtained, as shown in FIG. 12, an external electrode 12 is formed on the outer surface of the magnetic base 11 to obtain the coil component 1. The external electrode 12 is made of the above-mentioned materials such as Ag and Cu, and is formed on the surface of the magnetic substrate 11 by printing a paste, forming a film by sputtering or plating, adhering metal foil, or the like. Alternatively, a portion of the external electrode 12 may be provided before the magnetic substrate 11 is heat-treated.

According to the manufacturing process shown in FIGS. 7 to 12, the magnetic base 11 having the first magnetic part 11a and the second magnetic part 11b is obtained by molding, and integration with the conductor 14 is also realized by molding. Therefore, integration can be reliably achieved without adding any steps such as assembly.

The molded body 110 of the magnetic base 11 can be further heat-treated to improve its mechanical strength.
Further, any part of the magnetic base 11, the conductor 14, and the external electrode 12 may be processed after they are formed. For example, a portion of the lead-out portion 14b of the conductor 14 may be processed to be exposed from the surface of the magnetic base 11. Alternatively, for example, the surface of the magnetic substrate 11 may be processed to create a surface on which the external electrodes 12 will be formed. Further, according to the manufacturing process shown in FIGS. 7 to 12, it is easy to change the arrangement, dimensions, etc. of the first magnetic part 11a and the second magnetic part 11b.

<Other embodiments>
Other embodiments of the coil component 1 will be described below, focusing on the differences from the manufacturing process shown in FIGS. 7 to 12.
13 to 16 are diagrams showing the manufacturing process of the coil component 1 in the second embodiment. Each of FIGS. 13 to 15 shows a top view (A) and a cross-sectional view (B) showing a cross section taken along the line CC in the top view (A). FIG. 16 shows a sectional view corresponding to the sectional view of FIG. 12.
In the second embodiment, the bottom portion 111 of the magnetic base 11 has an elliptical protrusion portion 111b protruding from the bottom plate portion 111a on both the outer circumferential side and the inner circumferential side of the circumferential portion 14a. The thickness of both the outer and inner protrusions 111b is, for example, less than three times the second particle size, and serves as the first magnetic part 11a. That is, in the second embodiment, the first magnetic portion 11a is provided on both the outer circumferential side and the inner circumferential side of the circumferential portion 14a.

In the second embodiment, as shown in FIG. 14, the conductor 14 is arranged in the molded body of the bottom portion 111 so that the circumferential portion 14a fits between the circumferential portions 14a on the outer circumferential side and the inner circumferential side. Then, as shown in FIG. 15, an upper part 112 is molded on the bottom part 111 and the conductor 14 to obtain a molded body 110 that becomes the magnetic base 11 and is integrated with the conductor 14. In the second embodiment, similarly to the first embodiment, the upper portion 112 includes an upper plate portion 112a, a core portion 112b, and an outer edge portion 112c. In the case of the second embodiment, the core portion 112b is located further inside the protruding portion 111b, which is located on the inner peripheral side of the circumferential portion 14a.
In the second embodiment as well, there is no limit to the thickness of the upper portion 112, and the thickness including the thinnest portion is three times or more the second particle size. Therefore, the entire upper part 112 becomes the second magnetic part 11b.

In the second embodiment as well, the coil component 1 is obtained by forming the external electrode 12 on the outer surface of the magnetic base 11 integrally formed with the conductor 14, as shown in FIG. In the case of the second embodiment as well, the coil component 1 has high magnetic saturation characteristics and high inductance characteristics, and can be downsized while maintaining the performance as the coil component 1.

17 to 20 are diagrams showing the manufacturing process of the coil component 1 in the third embodiment. Each of FIGS. 17 to 19 shows a top view (A) and a cross-sectional view (B) showing a cross section taken along line CC in the top view (A). FIG. 20 shows a sectional view corresponding to the sectional view of FIG. 12.

In the third embodiment, the bottom portion 111 of the magnetic base 11 has an elliptical protrusion portion 111b protruding from the bottom plate portion 111a, and also has a core portion 111c protruding toward the inner circumferential side of the circumferential portion 14a. In the third embodiment as well, the thickness of the protruding portion 111b is, for example, less than three times the second particle diameter, and becomes the first magnetic portion 11a. On the other hand, the core portion 111c becomes the second magnetic portion 11b.

In the third embodiment, the conductor 14 is arranged in the molded body of the bottom part 111 so that the circumferential part 14a fits between the protruding part 111b and the core part 111c, as shown in FIG. Then, as shown in FIG. 19, an upper part 112 is molded on the bottom part 111 and the conductor 14 to obtain a molded body 110 that becomes the magnetic base 11 and is integrated with the conductor 14. The upper part 112 in the third embodiment has an upper plate part 112a and an outer edge part 112c, and does not have a core part. In the third embodiment as well, there is no limit to the thickness of the upper portion 112, and the thickness including the thinnest portion is three times or more the second grain size. Therefore, the entire upper part 112 becomes the second magnetic part 11b.

In the third embodiment as well, the external electrode 12 is formed on the outer surface of the magnetic base 11 integrally formed with the conductor 14, as shown in FIG. 20, to obtain the coil component 1. In the case of the third embodiment as well, the coil component 1 has high magnetic saturation characteristics and high inductance characteristics, and can be downsized while maintaining the performance as the coil component 1.

21 to 23 are diagrams showing the manufacturing process of the coil component 1 in the fourth embodiment. Each of FIGS. 21 to 23 shows a top view (A) and a cross-sectional view (B) showing a cross section taken along line CC in the top view (A).
In the fourth embodiment, a coil component 1 having a structure similar to that in the third embodiment is manufactured in a manufacturing process different from that in the third embodiment.

In the fourth embodiment, as shown in FIG. 21, a mold 40 for molding the bottom portion 111 is prepared, and the conductor 14 is placed inside the mold 40. Then, as shown in FIG. 22, a bottom portion 111 having a bottom plate portion 111a, a protruding portion 111b, and a core portion 111c is molded. During this molding, the thickness of the protruding portion 111b is set by the gap between the mold 40 and the circumferential portion 14a. Note that the bottom portion 111 is shown upside down with the bottom surface 1d facing upward.

In the fourth embodiment, since the bottom portion 111 is molded with the conductor 14 in the mold 40, the integrity of the bottom portion 111 and the conductor 14 is higher than in the third embodiment. The molded body in which the bottom portion 111 and the conductor 14 are integrated is removed from the mold 40 and turned upside down.
Thereafter, as shown in FIG. 23, the molded body in which the bottom part 111 and the conductor 14 are integrated is molded with the same upper part 112 as in the third embodiment, and is integrated with the conductor 14. , a molded body 110 that becomes the magnetic substrate 11 is obtained. Also in the fourth embodiment, the external electrode 12 is formed to obtain the coil component 1 (not shown).

Also in the manufacturing process in the fourth embodiment, the coil component 1 having the same structure as in the third embodiment can be manufactured. Furthermore, in the fourth embodiment, the integrity of the conductor 14 and the magnetic base 11 is higher than that in the third embodiment.

1 Coil component 2 Circuit board 2a Board 3 Land part 11 Magnetic base 11a First magnetic part 11b Second magnetic part 11c First metal particle 11d Second metal particle 110 Molded body 111 Bottom part 112 Upper part 111a Bottom plate part 111b Projection part 111c Core part 112a Upper plate portion 112b Core portion 112c Outer edge portion 12 External electrode 14 Conductor 14a Circumferential portion 14b Drawer portion

Claims (10)

a circulating portion made of a circulating conductor;
a first magnetic part formed by bonding first metal particles having a particle size distribution in which D90, which represents a particle size of 90% of the cumulative volume, is the first particle size; and a second magnetic part in which D90 is larger than the first particle size. It has a second magnetic part formed by bonding second metal particles having a particle size distribution that is a particle size, and includes the surrounding part, and includes at least a part of the first magnetic part on the outer peripheral side of the surrounding part. a magnetic substrate;
A coil component characterized by comprising: On the outer circumferential side of the circumferential portion of the magnetic base, at a portion where the thickness in the direction toward and away from the circumferential portion is the thinnest, the first magnetic portion is included within half of the side closer to the circumferential portion. The coil component according to claim 1. A claim characterized in that, on the outer peripheral side of the circumferential portion of the magnetic substrate, at a portion where the thickness in the direction toward and away from the circumferential portion is the thinnest, the first magnetic portion occupies half or more of the thickness. The coil component according to item 1 or 2. 4. At least a part of the second magnetic part is located further outside the first magnetic part, which is included in the outer peripheral side of the circumferential part. coil parts. The coil component according to any one of claims 1 to 4, wherein the short side of the outer shape is 1.0 mm or less. The coil component according to any one of claims 1 to 5,
A circuit board comprising: a board on which the coil component is mounted. An electronic device comprising the circuit board according to claim 6. A manufacturing method for manufacturing the coil component according to any one of claims 1 to 5, comprising:
a step of arranging a circumferential portion made of a circumferential conductor;
forming the second magnetic part with a thickness three times or more the second particle size;
forming the first magnetic part with a thickness less than three times the second particle diameter at a location on the outer peripheral side of the location where the circumferential part is arranged;
in any order,
A method for manufacturing a coil component, wherein at least one of the step of forming the first magnetic part and the step of forming the second magnetic part is a step of forming the magnetic base body integrally with the circumferential part. . The coil component according to claim 8, wherein at least one of the step of forming the first magnetic part and the step of forming the second magnetic part is a step including bonding of metal particles by heat treatment. manufacturing method. 10. The method of manufacturing a coil component according to claim 8, wherein the step of forming the magnetic base includes bonding the first magnetic part and the second magnetic part by heat treatment.

Images