Coil component and method of manufacturing the same

Abstract

A coil component includes a body and an external electrode. The body includes a coil conductor formed by winding a substantially rectangular wire covered with an insulating film, and a magnetic-body section containing a magnetic-body particle and a resin. The external electrode is electrically connected to an exposed surface of an extended portion of the coil conductor and is disposed at a surface of the body, the exposed surface being exposed at the surface of the body. The body includes first and second principal surfaces that face each other. At the wire, an average thickness of a portion of the insulating film that covers a first surface facing the first principal surface and extending in a direction orthogonal to a winding axis of the coil conductor is larger than average thicknesses of portions of the insulating film that cover other surfaces, orthogonal to the first surface, of the wire.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit of priority to Japanese Patent Application No. 2020-059521, filed Mar. 30, 2020, the entire content of which is incorporated herein by reference.

BACKGROUND

Technical Field

The present disclosure relates to a coil component and a method of manufacturing the same.

Background Art

As a coil component known in the art, a winding-integrated-type coil in which an air-cored coil, such as a coil, is sealed with, for example, a magnetic mold material is disclosed (refer to, for example, Japanese Unexamined Patent Application Publication No. 2011-009618). Such a mold coil is acquired in the following way. That is, in a mold coil in which a wire is sealed with a mold resin, after rounding the corners of a molded item by utilizing the impact of powder accelerated by air, a coil terminal and an external electrode are joined to each other to acquire the mold coil. The mold resin contains magnetic powder.

In a coil component, such as that disclosed in Japanese Unexamined Patent Application Publication No. 2011-009618, since a molded body in which a wire is sealed with a mold resin containing magnetic powder is to be formed, when such a molded body is formed, the magnetic powder may become stuck in or may pierce through an insulating film of the wire. Therefore, a short circuit may occur in a coil conductor.

SUMMARY

Accordingly, the present disclosure provides a coil component that is made highly reliable by making it possible to suppress occurrence of a short circuit in a coil conductor when manufacturing the coil component.

According to preferred embodiments of the present disclosure, there is provided a coil component including a body that includes a coil conductor in which a substantially rectangular wire covered with an insulating film is wound, and a magnetic-body section that contains a metal magnetic-body particle and a resin; and including an external electrode that is electrically connected to an exposed surface of an extended portion of the coil conductor and that is disposed at a surface of the body. The exposed surface is exposed at the surface of the body. In the coil component, the body includes a first principal surface and a second principal surface that faces the first principal surface. At the substantially rectangular wire, an average thickness of a portion of the insulating film that covers a first surface facing the first principal surface and extending in a direction orthogonal to a winding axis of the coil conductor is larger than average thicknesses of portions of the insulating film that cover other surfaces of the substantially rectangular wire, the other surfaces being orthogonal to the first surface.

In the coil component according to preferred embodiments of the present disclosure, since the portion of the insulating film of the substantially rectangular wire that covers a surface which is pressed when manufacturing the coil component has a thickness that is larger than the thicknesses of the portions of the insulating film that cover the other surfaces, impact resistance is increased, as a result of which it is possible to suppress occurrence of short-circuit defects that may occur when the magnetic-body particle pierces through the insulating film. In such a coil component according to preferred embodiments of the present disclosure, since it is possible to increase the molding pressure in compression molding, it is possible to increase the ability to fill with the magnetic-body particle and to thus improve the efficiency with which inductance is obtained.

According to preferred embodiments of the present disclosure, it is possible to provide a coil component that is made highly reliable by making it possible to suppress occurrence of a short circuit in a coil conductor when manufacturing the coil component.

The aforementioned object, other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description of preferred embodiments of the present disclosure with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external perspective view schematically illustrating a coil component according to a first embodiment of the present disclosure;

FIG. 2 is a transparent, perspective view of a magnetic-body section having a coil conductor buried therein in the coil component shown in FIG. 1;

FIG. 3 is a sectional view along line in FIG. 1;

FIG. 4 is a sectional view along line IV-IV in FIG. 1;

FIG. 5 is an enlarged sectional view of a portion a in FIG. 4;

FIG. 6 is an enlarged sectional view of a portion b in FIG. 5;

FIG. 7 is an enlarged sectional view of another example of portion b in FIG. 5;

FIG. 8A is an enlarged sectional view of another example of portion a in FIG. 4;

FIG. 8B is an enlarged sectional view of a portion c;

FIG. 9A is an enlarged sectional view of another example of portion a in FIG. 4;

FIG. 9B is an enlarged sectional view of a portion d;

FIG. 10 is an external perspective view schematically illustrating a coil component according to a second embodiment of the present disclosure;

FIG. 11 is a transparent, perspective view of a magnetic-body section having a coil conductor buried therein in the coil component shown in FIG. 10;

FIG. 12 is a sectional view along line XII-XII in FIG. 10;

FIG. 13 is a sectional view along line XIII-XIII in FIG. 10;

FIG. 14 is an enlarged sectional view of a portion e in FIG. 13;

FIG. 15 is an enlarged sectional view of a portion fin FIG. 14;

FIG. 16 is an enlarged sectional view of another example of portion fin FIG. 14;

FIGS. 17A to 17D are a manufacturing process diagram of an embodiment of manufacturing a first molded body in a method of manufacturing a coil component; and

FIGS. 18A to 18D are a manufacturing process diagram of an embodiment of manufacturing a collective base in the method of manufacturing the coil component.

DETAILED DESCRIPTION

1. Coil Component

Coil components according to the present disclosure are described in detail below with reference to the drawings.

FIG. 1 is an external perspective view schematically illustrating a coil component according to a first embodiment of the present disclosure. FIG. 2 is a transparent, perspective view of a magnetic-body section having a coil conductor buried therein in the coil component shown in FIG. 1. FIG. 3 is a sectional view along line in FIG. 1. FIG. 4 is a sectional view along line IV-IV in FIG. 1. FIG. 5 is an enlarged sectional view of a portion a in FIG. 4.

A coil component 10 includes a substantially rectangular parallelepiped body 12 and external electrodes 40.

(A) Body

The body 12 includes a magnetic-body section 14 and a coil conductor 16 that is buried in the magnetic-body section 14. The body 12 includes a first principal surface 12a and a second principal surface 12b that face each other in a pressing direction x, a first side surface 12c and a second side surface 12d that face each other in a width direction y that is orthogonal to the pressing direction x, and a first end surface 12e and a second end surface 12f that face each other in a length direction z that is orthogonal to the pressing direction x and the width direction y. The dimensions of the body 12 are not particularly limited to certain dimensions.

(B) Magnetic-Body Section

The magnetic-body section 14 contains magnetic-body particles and a resin material.

Although the resin material is not particularly limited to certain resin materials, examples thereof include thermosetting resins, such as organic materials including epoxy resin, phenol resin, polyester resin, polyimide resin, and polyolefin resin. Only one type of such substances above or two or more types of such substances above may be used for the resin material.

Although the magnetic-body particles desirably include first metal magnetic-body particles and second metal magnetic-body particles, the magnetic-body particles may include only the first metal magnetic-body particles.

The first metal magnetic-body particles have an average particle size of about 10 μm or greater. The average particle size of the first metal magnetic-body particles is, desirably, about 200 μm or less, more desirably, about 100 μm or less, and, even more desirably, about 80 μm or less. When the average particle size of the first metal magnetic-body particles is about 10 μm or greater, the magnetic properties of the magnetic-body section are improved.

The second metal magnetic-body particles have an average particle size that is smaller than the average particle size of the first metal magnetic-body particles. The second metal magnetic-body particles have an average particle size of about 5 μm or less. In this way, by causing the average particle size of the second metal magnetic-body particles to be smaller than the average particle size of the first metal magnetic-body particles, the ability with which the metal magnetic-body particles fill the magnetic-body section 14 is increased, as a result of which it is possible to improve the magnetic properties of the coil component 10.

Here, the term “average particle size” refers to an average particle size D50 (a particle size equivalent to 50% in a volume-based cumulative percentage). The average particle size D50 can be measured with, for example, a dynamic light-scattering particle-size analyzer (manufactured by NIKKISO CO., LTD., UPA).

Although the first metal magnetic-body particles and the second metal magnetic-body particles are not particularly limited to certain particles, examples thereof include iron, cobalt, nickel, or cadmium, or an alloy of one type of such substances above or two or more types of such substances above. The first metal magnetic-body particles and the second metal magnetic-body particles are desirably iron particles or iron-alloy particles. Although the iron alloy is not particularly limited to certain iron alloys, examples thereof include Fe—Si, Fe—Si—Cr, Fe—Ni, and Fe—Si—Al. Only one type of such substances above or two or more types of such substances above may be used for the first metal magnetic-body particles and the second metal magnetic-body particles.

A surface of each first metal magnetic-body particle and a surface of each second metal magnetic-body particle may be covered with an insulating film. By covering the surface of each metal magnetic-body particle with an insulating film, it is possible to increase the internal resistance of the magnetic-body section 14. Since the insulating properties of the surfaces of the metal magnetic-body particles are ensured by the insulating film, it is possible suppress short-circuit defects occurring with respect to the coil conductor 16.

Note that the magnetic-body particles may be ferrite particles.

Examples of the material of the insulating film include silicon oxides, phosphate-based glass, and bismuth-based glass. In particular, it is desirable to use an insulating film formed from zinc-phosphate-based glass in which the metal magnetic-body particles are subjected to mechano-chemical treatment.

Although the thickness of the insulating film is not particularly limited to certain thicknesses, the thickness of the insulating film may be, desirably, about 5 nm or greater and about 500 nm or less (i.e., from about 5 nm to about 500 nm), more desirably, about 5 nm or greater and about 100 nm or less (i.e., from about 5 nm to about 100 nm), and, even more desirably, about 10 nm or greater and about 100 nm or less (i.e., from about 10 nm to about 100 nm). When the thickness of the insulating film is made large, it is possible to further increase the resistance of the magnetic-body section 14. When the thickness of the insulating film is made small, it is possible to further increase the quantity of metal magnetic-body particles, as a result of which the magnetic properties of the magnetic-body section 14 are improved.

With respect to the entire magnetic-body section 14, the quantity of first metal magnetic-body particles and the quantity of second metal magnetic-body particles contained in the magnetic-body section 14 are, desirably, about 50 vol % or greater, more desirably, about 60 vol % or greater, and, even more desirably, about 70 vol % or greater. By causing the quantity of first metal magnetic-body particles and second metal magnetic-body particles contained to be in such a range, the magnetic properties of the coil component of the present disclosure are improved. With respect to the entire magnetic-body section 14, the quantity of first metal magnetic-body particles and the quantity of second metal magnetic-body particles contained are, desirably, about 99 vol % or less, more desirably, about 95 vol % or less, and, even more desirably, about 90 vol % or less. By causing the quantity of first metal magnetic-body particles and second metal magnetic-body particles contained to be in such a range, it is possible to further increase the resistance of the magnetic-body section 14.

In a surface portion of the magnetic-body section 14, a region that is adjacent to the coil conductor 16 may be removed. By removing the magnetic-body section 14 at the region adjacent to the coil conductor 16, a gap between the magnetic-body section 14 and the coil conductor 16 is increased and media easily enters when barrel plating is performed, as a result of which a plating film is formed over a wider area of the coil conductor 16. Therefore, an increase in joining strength and a reduction in electrical resistance are expected.

(C) Coil Conductor

The coil conductor 16 includes a winding portion 30 that is formed by winding in the form of a coil a conductive belt body 18, and a first extended portion 32a and a second extended portion 32b. The first extended portion 32a is extended to one side of the winding portion 30 and the second extended portion 32b is extended to the other side of the winding portion 30. The coil conductor 16 is formed by winding the conductive belt body 18 into a substantially alpha shape. The winding portion 30 is wound into two layers.

The first extended portion 32a is exposed from the first end surface 12e of the body 12 to dispose a first exposed portion 34a, and the second extended portion 32b is exposed from the second end surface 12f of the body 12 to dispose a second exposed portion 34b.

As shown in FIGS. 6 to 9, the conductive belt body 18 includes plate surfaces 18a and plate surfaces 18b that face each other, and side end surfaces 18c and side end surfaces 18d that face each other. In the conductive belt body 18 of the coil conductor 16, the plate surfaces 18a and the plate surfaces 18b are orthogonal to the side end surfaces 18c and the side end surfaces 18d. The conductive belt body 18 includes a substantially linear rectangular wire 20 that is substantially rectangular in cross section, and an insulating film 22 that covers a surface of the substantially rectangular wire 20.

In the conductive belt body 18 of the coil conductor 16, the side end surfaces 18c face the first principal surface 12a of the body 12, and the side end surfaces 18d face the second principal surface 12b of the body 12.

As shown in FIGS. 8 and 9, the coil conductor 16 includes a first principal surface 16a of the coil conductor 16 that is formed from the plurality of side end surfaces 18c, a second principal surface 16b of the coil conductor 16 that is formed from the plurality of side end surfaces 18d, a first side surface 16c of the coil conductor 16 that is formed from the plurality of plate surfaces 18a, and a second side surface 16d of the coil conductor 16 that is formed from the plurality of plate surfaces 18b.

The first principal surface 16a of the coil conductor 16 faces the first principal surface 12a of the body 12, and the second principal surface 16b of the coil conductor 16 faces the second principal surface 12b of the body 12.

The first side surface 16c and the second side surface 16d of the coil conductor 16 are orthogonal to the first principal surface 16a and the second principal surface 16b of the coil conductor 16.

As shown in FIG. 2, the winding portion 30 of the coil conductor 16 is wound around a winding axis O as a center. The coil conductor 16 is wound so that the plate surfaces 18a and the plate surfaces 18b overlap each other with the plate surfaces 18a and the plate surfaces 18b of the conductive belt body 18 being substantially parallel to the winding axis O and the side end surfaces 18c and the side end surfaces 18d of the conductive belt body 18 being substantially perpendicular to the winding axis O. Note that, in FIG. 2, the coil conductor 16 may be wound in a substantially oval form, in a substantially elliptical form, or in a circular form.

For example, the width of the substantially rectangular wire 20 at the plate surfaces 18a and 18b is about 15 μm or greater and about 200 μm or less (i.e., from about 15 μm to about 200 μm), and the width of the substantially rectangular wire 20 at the side end surfaces 18c and 18d is about 50 μm or greater and about 500 μm or less (i.e., from about 50 μm to about 500 μm).

The substantially rectangular wire 20 of the conductive belt body 18 is formed from, for example, a metal wire or a wire. Although the conductive material of the substantially rectangular wire 20 is not particularly limited to certain conductive materials, examples thereof include metal components including Ag, Au, Cu, Ni, Sn, and an alloy thereof. As the conductive material, copper is desirably used. As the conductive material, only one type of such substances above or two or more types of such substances above may be used.

A surface of the substantially rectangular wire 20 is covered with an insulating substance to form the insulating film 22. By covering the substantially rectangular wire 20 with an insulating substance, it is possible to more reliably insulate portions of the wound conductive belt body 18 from each other and more reliably insulate the conductive belt body 18 and the magnetic-body section 14 from each other.

Note that the insulating film 22 is not formed at a portion of each of the first exposed portion 34a and the second exposed portion 34b of the conductive belt body 18 that forms the coil conductor 16. Therefore, the external electrodes 40 are easily formed by plating. In addition, it is possible to further reduce the resistance at an electrical connection between the coil conductor 16 and the external electrodes 40.

Although the insulating substance of the insulating film 22 is not particularly limited to certain insulating substances, the insulating substance is at least one type selected from, for example, polyimide resin, polyamide resin, polyurethane resin, polyamide-imide resin, polyester resin, and enamel resin.

As shown in FIG. 6, at the substantially rectangular wire 20, an average thickness t_a1 of a portion of the insulating film 22 that covers each side end surface 18c facing the first principal surface 12a and extending in a direction orthogonal to the winding axis O of the coil conductor 16 is larger than average thicknesses of portions of the insulating film 22 that cover the other surfaces of the substantially rectangular wire 20, that is, an average thickness t_c1 of portions of the insulating film 22 that cover the plate surfaces 18a and the plate surfaces 18b, and an average thickness t_b1 of a portion of the insulating film 22 that covers the side end surfaces 18d. Here, the relationship between the average thicknesses of the portions of the insulating film 22 satisfies t_a1>t_b1≥t_c1. The average thickness t_a1 of the insulating film 22 is desirably about 4 μm or greater and about 20 μm or less (i.e., from about 4 μm to about 20 μm), and the average thickness t_b1 of the insulating film 22 and the average thickness t_c1 of the insulating film 22 are desirably about 1 μm or greater and about 10 μm or less (i.e., from about 1 μm to about 10 μm). Here, when the particle size of the average particle size D50 of the second metal magnetic-body particles is D, it is desirable that the average thickness tai of the insulating film 22 satisfy the relationship of D<t_a1.

As shown in FIG. 7, at the substantially rectangular wire 20, the average thickness t_a1 of the portion of the insulating film 22 that covers the side end surfaces 18c facing the first principal surface 12a and extending in the direction orthogonal to the winding axis O of the coil conductor 16 and the average thickness t_b1 of the portion of the insulating film 22 that covers the side end surfaces 18d facing the second principal surface 12b and extending in the direction orthogonal to the winding axis O of the coil conductor 16 are greater than the average thickness of the portions of the insulating film 22 that cover the other surfaces of the substantially rectangular wire 20, that is, the average thickness t_c1 of the portions of the insulating film 22 that cover the plate surfaces 18a and the plate surfaces 18b. Here, the relationship between the average thicknesses of the portions of the insulating film 22 desirably satisfies t_a1=t_b1>t_c1. The average thickness t_a1 of the insulating film 22 and the average thickness t_b1 of the insulating film 22 are desirably about 4 μm or greater and about 20 μm or less (i.e., from about 4 μm to about 20 μm), and the average thickness t_c1 of the insulating film 22 is desirably about 1 μm or greater and about 10 μm or less (i.e., from about 1 μm to about 10 μm). When the particle size of the average particle size D50 of the second metal magnetic-body particles is D, the average thickness t_a1 and the average thickness t_b1 of the insulating film 22 desirably satisfy the relationship of D<t_a1 and the relationship D<t_b1.

As shown in FIG. 8, the first principal surface 16a and the second principal surface 16b of the coil conductor 16 may be covered with a coil insulating film 24.

At the coil conductor 16, an average thickness t_A of a portion of the coil insulating film 24 that covers the first principal surface 16a of the coil conductor 16 facing the first principal surface 12a and extending in a direction orthogonal to the winding axis O of the coil conductor 16 and an average thickness t_B of a portion of the coil insulating film 24 that covers the second principal surface 16b of the coil conductor 16 facing the second principal surface 12b and extending in the direction orthogonal to the winding axis O of the coil conductor 16 are desirably about 1 μm or greater and about 20 μm or less (i.e., from about 1 μm to about 20 μm). In this case, the average thickness of the insulating film 22 that covers the substantially rectangular wire 20 may be a substantially uniform thickness. Therefore, an average thickness t_A+t_a1 of a portion of the insulating film that forms the first principal surface 16a of the coil conductor 16 extending in the direction orthogonal to the winding axis O of the coil conductor 16 and an average thickness t_B+t_b1 of a portion of the insulating film that forms the second principal surface 16b of the coil conductor 16 extending in the direction orthogonal to the winding axis O of the coil conductor 16 are larger than the average thickness of the portions of the insulating film that cover the first side surface 16c and the second side surface 16d of the coil conductor 16 (that is, the average thickness t_c1 of the portions of the insulating film that cover the plate surfaces 18a and the plate surfaces 18b of the substantially rectangular wire 20). The average thickness t_A+t_a1 of the portion of the insulating film that forms the first principal surface 16a of the coil conductor 16 extending in the direction orthogonal to the winding axis O of the coil conductor 16 and the average thickness t_B+t_b1 of the portion of the insulating film that forms the second principal surface 16b of the coil conductor 16 extending in the direction orthogonal to the winding axis O of the coil conductor 16 are about 5 μm or greater and about 40 μm or less (i.e., from about 5 μm to about 40 μm).

Further, as shown in FIG. 9, the first principal surface 16a and the second principal surface 16b of the coil conductor 16, and the first side surface 16c and the second side surface 16d of the coil conductor 16 may be covered with the coil insulating film 24.

The average thickness t_A of the portion of the coil insulating film 24 that covers the first principal surface 16a of the coil conductor 16 facing the first principal surface 12a and extending in the direction orthogonal to the winding axis O of the coil conductor 16 and the average thickness t_B of the portion of the coil insulating film 24 that covers the second principal surface 16b of the coil conductor 16 facing the second principal surface 12b and extending in the direction orthogonal to the winding axis O of the coil conductor 16 are desirably larger than the average thickness of a portion of the coil insulating film 24 that covers the other surface of the coil conductor 16, that is, an average thickness t_C of the portions of the coil insulating film 24 that cover the first side surface 16c and the second side surface 16d of the coil conductor 16. In this case, the average thickness of the insulating film 22 that covers the substantially rectangular wire 20 may be a substantially uniform thickness. Therefore, the average thickness t_A+t_a1 of the portion of the insulating film that forms the first principal surface 16a of the coil conductor 16 extending in the direction orthogonal to the winding axis O of the coil conductor 16 and the average thickness t_B+t_b1 of the portion of the insulating film that forms the second principal surface 16b of the coil conductor 16 extending in the direction orthogonal to the winding axis O of the coil conductor 16 are larger than an average thickness t_C+t_c1 of the portions of the insulating film that form the first side surface 16c and the second side surface 16d of the coil conductor 16. The average thickness t_A+t_a1 of the portion of the insulating film that forms the first principal surface 16a of the coil conductor 16 extending in the direction orthogonal to the winding axis O of the coil conductor 16 and the average thickness t_B+t_b1 of the portion of the insulating film that forms the second principal surface 16b of the coil conductor 16 extending in the direction orthogonal to the winding axis O of the coil conductor 16 are about 5 μm or greater and about 40 μm or less (i.e., from about 5 μm to about 40 μm).

The insulating film 22 may have two or more layers. In particular, the portion of the insulating film 22 that covers the side end surfaces 18c facing the first principal surface 12a and extending in the direction orthogonal to the winding axis O of the coil conductor 16 desirably has two or more layers.

In addition, at the substantially rectangular wire 20, the portion of the insulating film 22 that covers the side end surfaces 18c facing the first principal surface 12a and extending in the direction orthogonal to the winding axis O of the coil conductor 16 and the portion of the insulating film 22 that covers the side end surfaces 18d facing the second principal surface 12b and extending in the direction orthogonal to the winding axis O of the coil conductor 16 desirably have two or more layers.

This makes it possible to make it less likely for the magnetic-body particles to pierce through the insulating film 22. By forming the portions of the insulating film 22 having two or more layers with different compositions, it is possible to improve the insulating properties of the coil conductor 16, increase the mechanical strength of the coil conductor 16, and increase the ability to join the portions of the substantially rectangular wire 20 to each other.

Further, at the insulating film 22 having two or more layers, an outer layer is desirably covered with a thermal adhesion layer, which is a layer having thermal adhesiveness. Therefore, when the conductive belt body 18 is wound, the portions of the conductive belt body 18 are joined to each other, and thus it is possible to increase the joining strength between the portions of the conductive belt body 18 and to increase the ability to maintain the shape of the coil conductor 16.

It is desirable that the insulating film 22 not be disposed at exposed portions (exposed surfaces) at the end surfaces 12e and 12f of the body 12, where the first exposed portion 34a and the second exposed portion 34b are respectively disposed at the conductive belt body 18 of the coil conductor 16. Therefore, the coil conductor 16 and the external electrodes 40 can be directly electrically connected to each other, and thus it is possible to reduce electrical resistance between the coil conductor 16 and each external electrode 40.

Further, at the metal magnetic-body particles that are in contact with the external electrodes 40, the average thickness of the insulating film that is in contact with the external electrodes 40 is desirably smaller than the average thickness of the insulating film that is not in contact with the external electrodes 40. Therefore, when the external electrodes 40 are formed by plating, it is possible to pass current in a concentrated manner through the metal magnetic-body particles that are positioned near the first extended portion 32a and the second extended portion 32b of the coil conductor 16, which are respectively exposed at the first end surface 12e and the second end surface 12f of the body 12, and to further perform the film plating.

(D) External Electrodes

The external electrodes 40 are each disposed on a corresponding one of a side of the first end surface 12e and a side of the second end surface 12f of the body 12. The external electrodes 40 include a first external electrode 40a and a second external electrode 40b.

The first external electrode 40a is disposed on the first end surface 12e of the body 12. Note that the first external electrode 40a may be formed so as to extend from the first end surface 12e and cover a part of the first principal surface 12a, a part of the second principal surface 12b, a part of the first side surface 12c, and a part of the second side surface 12d, or may be formed so as to extend from the first end surface 12e to the second principal surface 12b and cover a part of the first end surface 12e and a part of the second principal surface 12b. In this case, the first external electrode 40a is electrically connected to the first extended portion 32a of the coil conductor 16.

The second external electrode 40b is disposed on the second end surface 12f of the body 12. Note that the second external electrode 40b may be formed so as to extend from the second end surface 12f and cover a part of the first principal surface 12a, a part of the second principal surface 12b, a part of the first side surface 12c, and a part of the second side surface 12d, or may be formed so as to extend from the second end surface 12f to the second principal surface 12b and cover a part of the second end surface 12f and a part of the second principal surface 12b. In this case, the second external electrode 40b is electrically connected to the second extended portion 32b of the coil conductor 16.

Although the thickness of the first external electrode 40a and the thickness of the second external electrode 40b are not particularly limited to certain thicknesses, the thickness of the first external electrode 40a and the thickness of the second external electrode 40b may be, for example, about 1 μm or greater and about 50 μm or less (i.e., from about 1 μm to about 50 μm) and desirably about 5 μm or greater and about 20 μm or less (i.e., from about 5 μm to about 20 μm).

The first external electrode 40a includes a first underlying electrode layer 42a and a first plating layer 44a that is disposed on a surface of the first underlying electrode layer 42a. Similarly, the second external electrode 40b includes a second underlying electrode layer 42b and a second plating layer 44b that is disposed on a surface of the second underlying electrode layer 42b.

The first underlying electrode layer 42a is disposed on the first end surface 12e of the body 12. Therefore, the first underlying electrode layer 42a is directly in contact with the first exposed portion 34a of the coil conductor 16. Note that the first underlying electrode layer 42a may be formed so as to extend from the first end surface 12e and cover a part of the first principal surface 12a, a part of the second principal surface 12b, a part of the first side surface 12c, and a part of the second side surface 12d, or may be formed so as to extend from the first end surface 12e and cover a part of the first end surface 12e and a part of the second principal surface 12b.

The second underlying electrode layer 42b is disposed on the second end surface 12f of the body 12. Therefore, the second underlying electrode layer 42b is directly in contact with the second exposed portion 34b of the coil conductor 16. Note that the second underlying electrode layer 42b may be formed so as to extend from the second end surface 12f and cover a part of the first principal surface 12a, a part of the second principal surface 12b, a part of the first side surface 12c, and a part of the second side surface 12d, or may be formed so as to extend from the second end surface 12f and cover a part of the second end surface 12f and a part of the second principal surface 12b.

The first underlying electrode layer 42a and the second underlying electrode layer 42b are made of a conductive material, desirably, one or more types of metal materials selected from Au, Ag, Pd, Ni, and Cu. The first underlying electrode layer 42a and the second underlying electrode layer 42b are each formed as a plating electrode. The first underlying electrode layer 42a and the second underlying electrode layer 42b may be formed by electrolytic plating or electroless plating.

The compositions of the main components of the metal materials constituting the first underlying electrode layer 42a and the second underlying electrode layer 42b are desirably the same as the composition of the main components of the metal material constituting the coil conductor 16.

The average thickness of the first underlying electrode layer 42a and the average thickness of the second underlying electrode layer 42b are, for example, about 10 μm.

The first plating layer 44a is disposed so as to cover the first underlying electrode layer 42a. Specifically, the first plating layer 44a may be disposed so as to cover the first underlying electrode layer 42a that is disposed on the first end surface 12e and may further be disposed so as to extend from the first end surface 12e and cover a surface of the first underlying electrode layer 42a, at which the first principal surface 12a, the second principal surface 12b, the first side surface 12c, and the second side surface 12d are disposed, or may be disposed so as to cover the first underlying electrode layer 42a that is disposed so as to extend from the first end surface 12e and cover a part of the first end surface 12e and a part of the second principal surface 12b.

The second plating layer 44b is disposed so as to cover the second underlying electrode layer 42b. Specifically, the second plating layer 44b may be disposed so as to cover the second underlying electrode layer 42b that is disposed on the second end surface 12f and may further be disposed so as to extend from the second end surface 12f and cover a surface of the second underlying electrode layer 42b, at which the first principal surface 12a, the second principal surface 12b, the first side surface 12c, and the second side surface 12d are disposed, or may further be disposed so as to cover the second underlying electrode layer 42b that is disposed so as to extend from the second end surface 12f and cover a part of the second end surface 12f and a part of the second principal surface 12b.

As metal materials of the first plating layer 44a and the second plating layer 44b, for example, at least one substance is selected from Cu, Ni, Ag, Sn, Pd, a Ag—Pd alloy, and Au.

The first plating layer 44a and the second plating layer 44b may each have a plurality of layers.

The first plating layer 44a has a two-layer structure including a first Ni plating layer 46a and a first Sn plating layer 48a that is formed on a surface of the first Ni plating layer 46a. The second plating layer 44b has a two-layer structure including a second Ni plating layer 46b and a second Sn plating layer 48b that is formed on a surface of the second Ni plating layer 46b.

The average thickness of the first Ni plating layer 46a and the average thickness of the second Ni plating layer 46b are, for example, about 5 μm.

The average thickness of the first Sn plating layer 48a and the average thickness of the second Sn plating layer 48b are, for example, about 10 μm.

Note that the first external electrode 40a and the second external electrode 40b may be provided with a structure such as that described below.

For example, the first underlying electrode layer 42a and the second underlying electrode layer 42b may each be a resin electrode containing Ag, and may include an Ag sputter layer, a Cu sputter layer, or a Ti sputter layer, which are formed by sputtering. Note that when the first underlying electrode layer 42a and the second underlying electrode layer 42b are each a resin electrode containing Ag, they may each contain a glass frit. When the first underlying electrode layer 42a and the second underlying electrode layer 42b are formed by sputtering, the Cu sputter layer may be formed on the Ti sputter layer.

The first plating layer 44a and the second plating layer 44b may be such that their outermost layers are constituted by only the Sn plating layer 48a and the Sn plating layer 48b, respectively.

Further, an Ag plating layer or a Ni plating layer may be formed on the body 12 without forming the first underlying electrode layer 42a and the second underlying electrode layer 42b.

(E) Protective Layer

In the embodiment, a protective layer 50 is provided on a surface of the body 12 excluding a portion where the first exposed portion 34a is exposed at the first end surface 12e of the body 12 and a portion where the second exposed portion 34b is exposed at the second end surface 12f of the body 12. The protective layer 50 is made of, for example, a resin material having a high electrical insulation performance, such as acrylic resin, epoxy resin, phenol resin, or polyimide resin. Note that, although in the present disclosure, the protective layer 50 is provided, the protective layer 50 need not be provided.

When a dimension in the length direction z of the coil component 10 is a dimension L, the dimension L is desirably about 1.0 mm or greater and about 12.0 mm or less (i.e., from about 1.0 mm to about 12.0 mm). When a dimension in the width direction y of the coil component 10 is a dimension W, the dimension W is desirably about 0.5 mm or greater and about 12.0 mm or less (i.e., from about 0.5 mm to about 12.0 mm). When a dimension in the pressing direction x of the coil component 10 is a dimension T, the dimension T is about 0.5 mm or greater and about 6.0 mm or less (i.e., from about 0.5 mm to about 6.0 mm).

At the substantially rectangular wire 20, since the average thickness t_a1 of the portion of the insulating film 22 that covers the side end surfaces 18c facing the first principal surface 12a and extending in the direction orthogonal to the winding axis O of the coil conductor 16 is larger than the average thicknesses of the portions of the insulating film 22 that cover the other surfaces of the substantially rectangular wire 20, that is, the average thickness t_c1 of the portions of the insulating film 22 that covers the plate surfaces 18a and the plate surfaces 18b, and the average thickness t_b1 of the portion of the insulating film 22 that covers the side end surface 18d, the coil component 10 shown in FIG. 1 has increased impact resistance, and thus is capable of suppressing occurrence of short-circuit defects that occur when magnetic-body particles pierce through the insulating film 22. In such a coil component according to the present disclosure, since it is possible to increase the molding pressure in compression molding, it is possible to increase the ability to fill with the magnetic-body particles and to thus improve the efficiency with which inductance is obtained.

Compared with when the insulating film 22 on the entire substantially rectangular wire 20 is thick, it is possible to reduce the volume of the magnetic-body section 14 and to suppress a reduction in magnetic permeability.

Next, a coil component 110 according to a second embodiment of the present disclosure is described.

FIG. 10 is an external perspective view schematically illustrating the coil component according to the second embodiment of the present disclosure. FIG. 11 is a transparent, perspective view of a magnetic-body section having a coil conductor buried therein in the coil component shown in FIG. 10. FIG. 12 is a sectional view along line XII-XII in FIG. 10. FIG. 13 is a sectional view along line XIII-XIII in FIG. 10. FIG. 14 is an enlarged sectional view of a portion e in FIG. 13.

A body 112 includes a magnetic-body section 114 and a coil conductor 116 that is buried in the magnetic-body section 114. The body 112 includes a first principal surface 112a and a second principal surface 112b that face each other in a height direction x, a first side surface 112c and a second side surface 112d that face each other in the width direction y that is orthogonal to the height direction x, and a first end surface 112e and a second end surface 112f that face each other in the length direction z that is orthogonal to the height direction x and the width direction y.

The coil conductor 116 includes a winding portion 130 that is formed by winding in the form of a coil a conductive belt body 118, which is one type of coil wire rod, and a first extended portion 132a and a second extended portion 132b. The first extended portion 132a is extended to one side of the winding portion 130 and the second extended portion 132b is extended to the other side of the winding portion 130. The coil conductor 116 is formed by winding the conductive belt body 118 into a substantially alpha shape. The conductive belt body 118 is wound in the form of an edgewise coil.

The first extended portion 132a is exposed from the first end surface 112e of the body 112 to dispose a first exposed portion 134a, and the second extended portion 132b is exposed from the second end surface 112f of the body 112 to dispose a second exposed portion 134b.

The conductive belt body 118 includes plate surfaces 118a and plate surfaces 118b that face each other, and side end surfaces 118c and side end surfaces 118d that face each other. The conductive belt body 118 includes a substantially linear rectangular wire 120 that is substantially rectangular in cross section, and an insulating film 122 that covers a surface of the substantially rectangular wire 120.

In the conductive belt body 118 of the coil conductor 116, the plate surfaces 118a face the first principal surface 112a of the body 112, and the plate surfaces 118b face the second principal surface 112b of the body 112.

As shown in FIG. 14, the coil conductor 116 includes a first principal surface 116a of the coil conductor 116 that is formed from the plate surfaces 118a, a second principal surface 116b of the coil conductor 116 that is formed from the plate surfaces 118b, a first side surface 116c of the coil conductor 116 that is formed from the plurality of side end surfaces 118c, and a second side surface 116d of the coil conductor 116 that is formed from the plurality of side end surfaces 118d.

The first principal surface 116a of the coil conductor 116 faces the first principal surface 112a of the body 112, and the second principal surface 116b of the coil conductor 116 faces the second principal surface 112b of the body 112.

As shown in FIG. 11, the winding portion 130 of the coil conductor 116 is wound around a winding axis O as a center. The coil conductor 116 is wound so that the plate surfaces 118a and the plate surfaces 118b overlap each other with the plate surfaces 118a and the plate surfaces 118b of the conductive belt body 118 being substantially perpendicular to the winding axis O and the side end surfaces 118c and the side end surfaces 118d of the conductive belt body 118 being substantially parallel to the winding axis O. Note that, although, in FIG. 11, the coil conductor 116 is wound in a substantially elliptical form, the coil conductor 116 may be wound in a circular form.

For example, the width of the substantially rectangular wire 120 at the side end surfaces 118c and the side end surfaces 118d is about 15 μm or greater and about 200 μm or less (i.e., from about 15 μm to about 200 μm), and the width of the substantially rectangular wire 120 at the plate surfaces 118a and 118b is about 50 μm or greater and about 500 μm or less (i.e., from about 50 μm to about 500 μm).

The substantially rectangular wire 120 of the conductive belt body 118 is formed from, for example, a metal wire or a wire. Although the conductive material of the substantially rectangular wire 120 is not particularly limited to certain conductive materials, examples thereof include metal components including Ag, Au, Cu, Ni, Sn, and an alloy thereof. As the conductive material, copper is desirably used. As the conductive material, only one type of such substances above or two or more types of such substances above may be used.

A surface of the substantially rectangular wire 120 is covered with an insulating substance to form the insulating film 122. By covering the substantially rectangular wire 120 with an insulating substance, it is possible to more reliably insulate portions of the wound conductive belt body 118 from each other and more reliably insulate the conductive belt body 118 and the magnetic-body section 114 from each other.

Note that the insulating film 122 is not formed at a portion of each of the first exposed portion 134a and the second exposed portion 134b of the conductive belt body 118 that forms the coil conductor 116. Therefore, external electrodes 140 are easily formed by plating. In addition, it is possible to further reduce the resistance at an electrical connection between the coil conductor 116 and the external electrodes 140.

Although the insulating substance of the insulating film 122 is not particularly limited to certain insulating substances, the insulating substance is at least one type selected from, for example, polyimide resin, polyamide resin, polyurethane resin, polyamide-imide resin, polyester resin, and enamel resin.

As shown in FIG. 15, at the substantially rectangular wire 120, an average thickness t_a2 of a portion of the insulating film 122 that covers the plate surfaces 118a facing the first principal surface 112a and extending in a direction orthogonal to the winding axis O of the coil conductor 116 is larger than an average thickness t_b2 of a portion of the insulating film 122 that covers the plate surfaces 118b facing the second principal surface 112b and extending in the direction orthogonal to the winding axis O of the coil conductor 116. Here, the relationship between the average thicknesses of the portions of the insulating film 122 satisfies t_a2>t_b2≥t_c2. The average thickness t_a2 of the insulating film 122 is desirably about 4 μm or greater and 20 μm or less (i.e., from about 4 μm to 20 μm), and the average thickness t_b2 of the insulating film 122 and the average thickness t_c2 of the insulating film 122 are desirably about 1 μm or greater and 10 μm or less (i.e., from about 1 μm to 10 μm). Here, when the particle size of the average particle size D50 of second metal magnetic-body particles is D, the average thickness t_a2 of the insulating film 122 desirably satisfy the relationship of D<t_a2.

As shown in FIG. 16, at the substantially rectangular wire 120, the average thickness t_a2 of the portion of the insulating film 122 that covers the plate surfaces 118a facing the first principal surface 112a and extending in the direction orthogonal to the winding axis O of the coil conductor 116 and the average thickness t_b2 of the portion of the insulating film 122 that covers the plate surfaces 118b facing the second principal surface 112b and extending in the direction orthogonal to the winding axis O of the coil conductor 116 are desirably larger than the average thickness of portions of the insulating film 122 that cover the other surfaces of the substantially rectangular wire 120, that is, the average thickness t_c2 of the portions of the insulating film 122 that cover the side end surfaces 118c and the side end surfaces 118d. Here, the relationship between the average thicknesses of the portions of the insulating film 122 desirably satisfies t_a2=t_b2>t_c2. The average thickness t_a2 of the insulating film 122 and the average thickness t_b2 of the insulating film 122 are desirably about 4 μm or greater and about 20 μm or less (i.e., from about 4 μm to about 20 μm), and the average thickness t_c2 of the insulating film 122 is desirably about 1 μm or greater and about 10 μm or less (i.e., from about 1 μm to about 10 μm). When the particle size of the average particle size D50 of the second metal magnetic-body particles is D, it is desirable that the average thickness t_a2 of the insulating film 122 and the average thickness t_b2 of the insulating film 122 desirably satisfy the relationship of D<t_a2 and the relationship D<t_b2, respectively.

The insulating film 122 may have two or more layers. In particular, the portion of the insulating film 122 that covers the plate surfaces 118a facing the first principal surface 112a and extending in the direction orthogonal to the winding axis O of the coil conductor 116 desirably has two or more layers.

In addition, at the substantially rectangular wire 120, the portion of the insulating film 122 that covers the plate surfaces 118a facing the first principal surface 112a and extending in the direction orthogonal to the winding axis O of the coil conductor 116 and the portion of the insulating film 122 that covers the plate surfaces 118b facing the second principal surface 112b and extending in the direction orthogonal to the winding axis O of the coil conductor 116 desirably have two or more layers.

Further, at the insulating film 122 having two or more layers, an outer layer is desirably covered with a thermal adhesion layer, which is a layer having thermal adhesiveness. Therefore, when the conductive belt body 118 is wound, the portions of the conductive belt body 118 are joined to each other, and thus it is possible to increase the joining strength between the portions of the conductive belt body 118 and to increase the ability to maintain the shape of the coil conductor 116.

When, as shown in FIG. 12, the first extended portion 132a of the coil conductor 116 is exposed from the first principal surface 112a, a first external electrode 140a is formed so as to cover a part of the first principal surface 112a. In this case, the first external electrode 140a is electrically connected to the first extended portion 132a of the coil conductor 116.

When, as shown in FIG. 12, the second extended portion 132b of the coil conductor 116 is exposed from the first principal surface 112a, a second external electrode 140b is formed so as to cover a part of the first principal surface 112a. In this case, the second external electrode 140b is electrically connected to the second extended portion 132b of the coil conductor 116.

The first external electrode 140a includes a first underlying electrode layer 142a and a first plating layer 144a that is disposed on a surface of the first underlying electrode layer 142a. Similarly, the second external electrode 140b includes a second underlying electrode layer 142b and a second plating layer 144b that is disposed on a surface of the second underlying electrode layer 142b.

As shown in FIG. 12, when the coil conductor 116 is such that the first extended portion 132a of the coil conductor 116 is exposed from the first principal surface 112a, the first underlying electrode layer 142a is formed on a part of the first principal surface 112a so as to cover the first extended portion 132a of the coil conductor 116.

As shown in FIG. 12, when the second extended portion 132b of the coil conductor 116 is exposed from the first principal surface 112a, the second underlying electrode layer 142b is formed on a part of the first principal surface 112a so as to cover the second extended portion 132b of the coil conductor 116.

Here, the first underlying electrode layer 142a and the second underlying electrode layer 142b are formed from a plurality of crystal particles. The particle size of the crystal particles of the first underlying electrode layer 142a and the second underlying electrode layer 142b is desirably about 100 nm or greater and about 2000 nm or less (i.e., from about 100 nm to about 2000 nm).

As shown in FIG. 12, when the first extended portion 132a of the coil conductor 116 is exposed from the first principal surface 112a, the first plating layer 144a is formed so as to cover the first underlying electrode layer 142a that is disposed on the first principal surface 112a.

As shown in FIG. 12, when the second extended portion 132b of the coil conductor 116 is exposed from the first principal surface 112a, the second plating layer 144b is formed so as to cover the second underlying electrode layer 142b that is disposed on the first principal surface 112a.

The first plating layer 144a and the second plating layer 144b may each have a plurality of layers.

The first plating layer 144a has a two-layer structure including a first Ni plating layer 146a and a first Sn plating layer 148a that is formed on a surface of the first Ni plating layer 146a. The second plating layer 144b has a two-layer structure including a second Ni plating layer 146b and a second Sn plating layer 148b that is formed on a surface of the second Ni plating layer 146b.

The average thickness of the first Ni plating layer 146a and the average thickness of the second Ni plating layer 146b are, for example, about 5 μm.

The average thickness of the first Sn plating layer 148a and the average thickness of the second Sn plating layer 148b are, for example, about 10 μm.

The coil component 110 shown in FIG. 10 provides the same effects as those provided by the coil component 10 shown in FIG. 1.

2. Method of Manufacturing Coil Component

Next, a method of manufacturing a coil component is described.

(A) Preparation of Metal Magnetic-Body Particles

First, metal magnetic-body particles are prepared. Here, the metal magnetic-body particles are not particularly limited to certain particles, and may be, for example, a soft-magnetic-material powder based on Fe, such as α-Fe, Fe—Si, Fe—Si—Cr, Fe—Si—Al, Fe—Ni, or Fe—Co. The material form of the metal magnetic-body particles is desirably an amorphous material having good soft magnetic properties, but is not particularly limited to certain material forms, and may be a crystalline material.

Although the average particle size of the metal magnetic-body particles is not particularly limited to certain average particle sizes, it is desirable to use metal magnetic-body particles having two or more different average particle sizes. That is, the metal magnetic-body particles are dispersed in a resin material. Therefore, from the viewpoint of increasing the filling efficiency of the metal magnetic-body particles, it is desirable to use metal magnetic-body particles having different average particle sizes, such as first metal magnetic-body particles having an average particle size of about 10 μm or greater and about 40 μm or less (i.e., from about 10 μm to about 40 μm) and second metal magnetic-body particles having an average particle size of about 1 μm or greater and about 20 μm or less (i.e., from about 1 μm to about 20 μm).

(B) Formation of Insulating Film

Next, the surfaces of the metal magnetic-body particles are covered with an insulating film. Here, when the insulating film is to be formed by a mechanical method, it is possible to put the metal magnetic-body particles and an insulating-material powder into a rotating container, combine the particles by mechano-chemical treatment, and thereby cover the surfaces of magnetic-body powder with the insulating film.

(C) Fabrication of Magnetic-Body Sheet

Next, the resin material is prepared. The resin material is not particularly limited to certain resin materials, and can be, for example, epoxy resin, phenol resin, polyester resin, polyimide resin, or a polyolefin resin.

Next, the metal magnetic-body particles covered with the insulating film and a filler component (a glass material, ceramic powder, ferrite powder, or the like) is mixed with the resin material into the form of a slurry. Next, the slurry is formed by, for example, a doctor blade method and is then dried, to thereby fabricate a magnetic-body sheet having the filler component dispersed in the resin material and having a thickness of about 50 μm or greater and about 300 μm or less (i.e., from about 50 μm to about 300 μm).

(D) Preparation of Coil Conductor

Next, with Cu as a wire conductor, the coil conductor 16 that is formed by winding into a substantially alpha shape the conductive belt body 18 including the substantially rectangular wire 20 covered with the insulating film 22 is prepared.

The conductive belt body 18 includes the substantially linear rectangular wire 20 that is substantially rectangular in cross section, and the insulating film 22 that covers the surface of the substantially rectangular wire 20. The conductive belt body 18 includes the plate surfaces 18a and the plate surfaces 18b that face each other, and the side end surfaces 18c and the side end surfaces 18d that face each other. In the conductive belt body 18 of the coil conductor 16, the plate surfaces 18a and the plate surfaces 18b are orthogonal to the side end surfaces 18c and the side end surfaces 18d. In order to acquire the conductive belt body 18, first, the entire surface of the substantially rectangular wire 20 is substantially uniformly coated with the insulating film 22. Next, only the side end surfaces 18c of the conductive belt body 18 are further coated with the insulating film 22 to acquire the conductive belt body 18 as that as shown in FIG. 6. Note that only both the side end surfaces 18c and the side end surfaces 18d may be further coated with the insulating film 22. Therefore, the conductive belt body 18 as that shown in FIG. 7 is acquired. The substantially rectangular wire 20 may be coated with the insulating film 22 by, for example, dipping.

In order to acquire the conductive belt body 18, first, the entire surface of the substantially rectangular wire 20 may be substantially uniformly coated with the insulating film 22. Then, the conductive belt body 18 may be wound into a substantially alpha shape and then the first principal surface 16a and the second principal surface 16b of the coil conductor 16 may be coated with the coil insulating film 24, as a result of which it is possible to acquire the coil conductor 16 as that shown in FIG. 8A.

Further, in order to acquire the conductive belt body 18, first, the entire surface of the substantially rectangular wire 20 may be substantially uniformly coated with the insulating film 22. Then, the conductive belt body 18 may be wound into a substantially alpha shape and then the first principal surface 16a and the second principal surface 16b of the coil conductor 16 and the first side surface 16c and the second side surface 16d of the coil conductor 16 may be substantially uniformly coated with the coil insulating film 24. Then, only the first principal surface 16a and the second principal surface 16b of the coil conductor 16 may be further coated with the coil insulating film 24, as a result of which it is possible to acquire the coil conductor 16 as that shown in FIG. 9.

Note that the first side surface 16c and the second side surface 16d of the coil conductor 16 are orthogonal to the first principal surface 16a and the second principal surface 16b of the coil conductor 16.

(E) Fabrication of Collective Base

Next, if necessary, the insulating film 22 at a region that is about 50 μm from an end of the coil conductor 16 is removed by nipper-like scissors. Therefore, although not shown, an insulating film removal portion, which is a portion that is not covered in a substantially annular shape with the insulating film 22 with an extension direction of the coil conductor 16 being a center axis, is formed. Note that the insulating film 22 can be removed by burning off the region as a result of heating it, or by dissolving the region with a chemical liquid or laser.

Next, the body 12 having the coil conductor 16 buried therein is manufactured.

FIGS. 17A to 17D is a manufacturing process diagram of an embodiment of manufacturing a first molded body in the method of manufacturing the coil component. FIGS. 18A to 18D is a manufacturing process diagram of an embodiment of manufacturing the collective base in the method of manufacturing the coil component.

First, as shown in FIG. 17A, a first die 60 is prepared, and coil conductors 16 are disposed in a matrix on the first die 60.

Next, as shown in FIG. 17B, a first magnetic-body sheet 70a including a mixture of the first metal magnetic-body particles, the second metal magnetic-body particles, and the resin material is superimposed upon the coil conductors 16, and, then, as shown in FIG. 17C, a second die 62 is disposed on a side of an upper surface of the first magnetic-body sheet 70a. Then, as shown in FIG. 17D, the first magnetic-body sheet 70a is sandwiched between the coil conductors 16 on the first die 60 and the second die 62, and is subjected to primary press-molding in a direction of the winding axis O. Due to the primary press-molding, at least a part of the coil conductors 16 is buried in the sheet, the inside of such coil conductors 16 is filled with the mixture, as a result of which a first molded body 72 is fabricated.

Next, as shown in FIG. 18A, the first molded body 72 in which the coil conductors 16 acquired by the primary press-molding are buried is separated from the second die 62, is turned upside down, and is disposed on the first die 60. Then, a different second magnetic-body sheet 70b is superimposed upon a surface at which the coil conductors 16 are exposed. Next, as shown in FIG. 18B, a third die 64 is disposed on a side of an upper surface of the second magnetic-body sheet 70b. Then, as shown in FIG. 18C, the second magnetic-body sheet 70b is sandwiched between the first molded body 72 on the first die 60 and the third die 64 to perform a secondary pressing operation in the direction of the winding axis O.

Next, after the secondary pressing operation, as shown in FIG. 18D, the third die 64 is separated, as a result of which the collective base (second molded body) 74 in which all of the coil conductors 16 are buried in the first magnetic-body sheet 70a and the second magnetic-body sheet 70b is fabricated.

(F) Fabrication of Body

Next, the first die 60 and the third die 64 are separated, and, as shown in FIG. 18D, after fabricating the collective base 74, a cutting tool, such as a dicer, is used to cut the collective base 74 along a cutting line into individual pieces, as a result of which the body 12 in which the coil conductor 16 is buried therein so that the first exposed portion 34a and the second exposed portion 34b of the coil conductor 16 are exposed from the respective end surfaces of the body 12 is fabricated. The collective base 74 can divided into each body 12 with a dicing blade, various laser devices, a dicer, various cutting tools, or a die. In a desirable mode, a cut surface of each body 12 is subjected to barrel grinding.

Next, the protective layer 50 is formed on the entire surface of the body acquired above. It is possible to form the protective layer 50 by, for example, electrodeposition, a spray method, or a dip method.

By irradiating with laser the vicinity of a location at which the first exposed portion 34a and the second exposed portion 34b of the coil conductor 16 of the body 12 covered with the protective layer 50 acquired above are disposed, a portion of the insulating film 22 at the vicinity of the location at which the first exposed portion 34a and the second exposed portion 34b of the coil conductor 16 are disposed, a portion of the insulating film that covers the metal magnetic-body particles, and the protective layer 50 are removed, and the metal magnetic-body particles are melted. Note that the method of removing the protective layer 50 can be, in addition to the laser irradiation method, for example, a blasting method or a grinding method.

(G) Formation of External Electrodes

Next, the first external electrode 40a is formed on the first end surface 12e of the body 12, and the second external electrode 40b is formed on the second end surface 12f.

First, the body 12 is subjected to electrolytic barrel plating to plate the body 12 with Cu, as a result of which the underlying electrode layers are formed. Next, the Ni plating layers are formed by plating the surface of each underlying electrode layer with Ni and the Sn plating layers are further formed by plating with Sn, as a result of which the external electrodes 40 are formed. Therefore, the first exposed portion 34a of the coil conductor 16 is electrically connected to the first external electrode 40a, and the second exposed portion 34b of the coil conductor 16 is electrically connected to the second external electrode 40b. Note that the underlying electrode layers formed by the plating with Cu may be formed by electroless plating.

The coil component 10 is manufactured as described above.

Note that the first molded body 72 and the collective base 74 may be manufactured by using granulation powder instead of the first magnetic-body sheet 70a and the second magnetic-body sheet 70b.

In this case, first, the first die is prepared and the coil conductors 16 are disposed on the first die.

Next, the granulation powder is disposed on the coil conductors 16 and is press-molded in the direction of the winding axis O, as a result of which the first molded body 72 is formed. Next, the first molded body 72 is separated from the second die, is turned upside down, and is disposed on the first die 60. Then, the granulation powder is disposed on the first molded body 72 and is press-molded in the direction of the winding axis O, as a result of which the collective base (the second molded body) 74 can be fabricated.

The granulation powder for constituting the magnetic-body section 14 can be acquired by mixing first metal magnetic powder and second metal magnetic powder with thermosetting epoxy resin at a predetermined proportion and kneading the mixture.

When the coil component 110 is to be manufactured, the coil conductor 116 that is formed by winding in the form of an edgewise coil the conductive belt body 118 that is formed from the substantially rectangular wire 120 covered with the insulating film 122 is prepared.

The conductive belt body 118 includes the substantially linear rectangular wire 120 that is substantially rectangular in cross section, and the insulating film 122 that covers the surface of the substantially rectangular wire 120. In order to acquire the conductive belt body 118, first, the entire surface of the substantially rectangular wire 120 is substantially uniformly coated with the insulating film 122. Next, only the plate surfaces 118a of the conductive belt body 118 are further coated with the insulating film 122 to acquire the conductive belt body 118 as that shown in FIG. 15. Note that only both the plate surfaces 118a and the plate surfaces 118b may be further coated with the insulating film 122. Therefore, as shown in FIG. 16, the conductive belt body 118 is acquired. The substantially rectangular wire 120 may be coated with the insulating film 122 by, for example, dipping.

According to the method of manufacturing the coil component according to the embodiment, by using the coil conductor 16, the insulating film 22 that is disposed on the side of the first principal surface 16a of the coil conductor 16 facing the first principal surface 12a of the body 12 is thick. Therefore, impact resistance is increased, as a result of which it is possible to provide a coil component that makes it possible to suppress occurrence of short-circuit defects that occur when the magnetic-body particles that constitute the magnetic-body section 14 pierce through the insulating film 22.

Note that, although the embodiments of the present disclosure are disclosed in the description above in this way, the present disclosure is not limited to such embodiments.

That is, various changes can be made to the embodiments described above in terms of the mechanism, the shape, the material, the quantity, the position, and the configuration, without departing from the scope of the technical idea and the object of the present disclosure, and such changes are included in the present disclosure.

While preferred embodiments of the disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. The scope of the disclosure, therefore, is to be determined solely by the following claims.

Claims

1. A coil component comprising: a body that includes a coil comprising a winding portion which a substantially rectangular wire covered with an insulating film is wound, and an extended portion that extends to the winding portion,a magnetic-body section that contains a magnetic-body particle and a resin, anda first principal surface and a second principal surface that faces the first principal surface, and at the substantially rectangular wire, an average thickness of a portion of the insulating film that covers a first surface of the winding portion facing the first principal surface and extending in a direction orthogonal to a winding axis of the coil of the winding portion is larger than an average thickness of a portion of the insulating film that covers a second surface of the winding portion facing the second principal surface and extending in the direction orthogonal to the winding axis, and is larger than average thicknesses of portions of the insulating film that cover other surfaces of the winding portion, the other surfaces being orthogonal to the first surface; andan external electrode that is electrically connected to an exposed surface of an extended portion of the coil and that is disposed at a surface of the body, the exposed surface being exposed at the surface of the body.

2. The coil component according to claim 1, wherein the magnetic-body particle is a metal magnetic-body particle.

3. The coil component according to claim 2, wherein the metal magnetic-body particle includes at least two or more types of metal magnetic-body particles, andwhen an average particle size D50 of, among the metal magnetic-body particles, the metal magnetic-body particle having the average particle size D50 that is small is D, an average thickness ta of a thicker one of the portions of the insulating film of the coil satisfies a relationship of D<ta.

4. The coil component according to claim 2, wherein at the substantially rectangular wire, the portion of the insulating film that covers the second surface has two or more layers.

5. The coil component according to claim 1, wherein at the substantially rectangular wire, the average thickness of the portion of the insulating film that covers the first surface is from about 4 μm to about 20 μm, andthe average thicknesses of the portions of the insulating film that cover the other surfaces, which are orthogonal to the first surface, of the substantially rectangular wire are from about 1 μm to about 10 μm.

6. The coil component according to claim 5, wherein at the substantially rectangular wire, the average thickness of the portion of the insulating film that covers the second surface is from about 4 μm to about 20 μm.

7. The coil component according to claim 1, wherein at the substantially rectangular wire, the portion of the insulating film that covers the first surface has two or more layers.

8. The coil component according to claim 7, wherein an outermost layer of the portion of the insulating film having the two or more layers contains a thermally adhesive component.

9. A coil component comprising: a body that includes a coil comprising a winding portion which a substantially rectangular wire covered with an insulating film is wound, and an extended portion that extends to the winding portion,a magnetic-body section that contains a magnetic-body particle and a resin, anda first principal surface and a second principal surface that faces the first principal surface, and at the coil, an average thickness of a portion of the insulating film that configures a first surface of the winding portion facing the first principal surface and extending in a direction orthogonal to a winding axis of the coil of the winding portion is larger than an average thickness of a portion of the insulating film that covers a second surface of the winding portion facing the second principal surface and extending in the direction orthogonal to the winding axis, and is larger than average thicknesses of portions of the insulating film that configure other surfaces of the winding portion, the other surfaces being orthogonal to the first surface; andan external electrode that is electrically connected to an exposed surface of an extended portion of the coil and that is disposed at a surface of the body, the exposed surface being exposed at the surface of the body.

10. The coil component according to claim 9, wherein the magnetic-body particle is a metal magnetic-body particle.

11. The coil component according to claim 10, wherein the metal magnetic-body particle includes at least two or more types of metal magnetic-body particles, andwherein, when an average particle size D50 of, among the metal magnetic-body particles, the metal magnetic-body particle having the average particle size D50 that is small is D, an average thickness ta of a thicker one of the portions of the insulating film of the coil satisfies a relationship of D<ta.

12. The coil component according to claim 9, wherein at the coil, the average thickness of the portion of the insulating film that configures the first surface is from about 4 μm to about 20 μm, andthe average thicknesses of the portions of the insulating film that configure the other surfaces, which are orthogonal to the first surface, of the coil are from about 5 μm to about 40 μm.

13. The coil component according to claim 12, wherein at the coil, the average thickness of the portion of the insulating film that configures the second surface is from about 5 μm to about 40 μm.

14. The coil component according to claim 9, wherein at the coil, the portion of the insulating film that configures the first surface has two or more layers.

15. The coil component according to claim 9, wherein at the coil, the portion of the insulating film that configures the second surface has two or more layers.