阅读说明：本技术 线圈部件和该线圈部件中使用的磁性粉末混合树脂材料的制造方法 (Coil component and method for producing magnetic powder mixed resin material used for the same ) 是由 石田启一 井田浩一 大井秀朗 于 2020-09-28 设计创作，主要内容包括：本发明提供维持高磁导率并且能够提高直流叠加特性的线圈部件和用于得到这样的线圈部件的磁性粉末混合树脂的制造方法。本发明的线圈部件(10)具备包含线圈导体(16)和磁性体部(14)的单元体(12)以及与线圈导体(16)的引出部(22a,22b)电连接并配置于单元体(12)的表面的外部电极(30),该线圈导体(16)是将导线卷绕而形成的,该磁性体部(14)含有由绝缘被膜(14a1)被覆的金属磁性体粒子(14a)、树脂和绝缘体粒子(15)。绝缘体粒子(15)的特征在于,相对磁导率低于金属磁性体粒子(14a),且绝缘体粒子(15)和绝缘被膜(14a1)的主成分为相同种类的化合物。另外,是用于得到这样的线圈部件(10)的磁性粉末混合树脂材料的制造方法。(The invention provides a coil component capable of maintaining high magnetic permeability and improving direct current superposition characteristics, and a method for manufacturing a magnetic powder mixed resin for obtaining the coil component. A coil component (10) is provided with a unit body (12) including a coil conductor (16) and a magnetic body section (14), and an external electrode (30) which is electrically connected to lead-out sections (22a, 22b) of the coil conductor (16) and is disposed on the surface of the unit body (12), wherein the coil conductor (16) is formed by winding a wire, and the magnetic body section (14) contains metallic magnetic particles (14a) covered with an insulating film (14a1), a resin, and insulating particles (15). The insulator particles (15) are characterized in that the relative permeability is lower than that of the metallic magnetic particles (14a), and the main components of the insulator particles (15) and the insulating coating (14a1) are the same type of compound. Also disclosed is a method for producing a magnetic powder mixed resin material for obtaining such a coil component (10).)

1. A coil component is characterized by comprising a unit body and an external electrode,

the unit body includes a coil conductor and a magnetic body,

the coil conductor is formed by winding a wire,

the magnetic body portion contains metallic magnetic particles coated with an insulating film, a resin, and insulating particles,

the external electrode is electrically connected to the lead-out portion of the coil conductor and disposed on the surface of the unit body,

the insulating particles have a lower relative permeability than the metallic magnetic particles, and the main components of the insulating particles and the insulating film are the same kind of compound.

2. The coil component of claim 1, wherein the insulator particles are non-magnetic.

3. The coil component according to claim 1 or 2, wherein the insulating film has a thickness of 10nm to 250nm and an average thickness of 30nm or more.

4. The coil component according to any one of claims 1 to 3, wherein a ratio of a volume of the insulator particles to a volume of the magnetic body portion is 1.0 vol% to 4.0 vol%.

5. The coil component according to any one of claims 1 to 4, wherein a ratio of a volume of the insulator particles to a volume of the metal magnetic particles is 1.2 vol% to 4.8 vol%.

6. The coil component according to any one of claims 1 to 5, wherein the insulating film and the insulating particles contain glass.

7. A method for manufacturing a magnetic powder mixed resin material, characterized by comprising:

a step of mixing the metallic magnetic particles with an insulating material,

a step of forming an insulating film on the surface of the metal magnetic particles by using a part of the insulating material by mechanochemical treatment, and

mixing the metallic magnetic particles coated with the insulating film, the remaining part of the insulating material, and a resin material;

the insulator material has a relative permeability lower than that of the metallic magnetic particles.

8. The method for manufacturing a magnetic powder mixed resin material according to claim 7, wherein the insulator material is nonmagnetic.

9. The method for producing a magnetic powder mixed resin material according to claim 7 or 8, wherein a content of a remaining portion of the insulator material in the magnetic powder mixed resin material is 1.0 vol% to 4.0 vol%.

10. The method for producing a magnetic powder mixed resin material according to any one of claims 7 to 9, wherein a content of a remaining portion of the insulator material is 1.2 vol% to 4.8 vol% with respect to a content of the metal magnetic particles in the magnetic powder mixed resin material.

11. The method for producing a magnetic powder mixed resin material according to any one of claims 7 to 10, wherein the insulator material contains glass.

Technical Field

The present invention relates to a coil component and a method for producing a magnetic powder mixed resin material used for the coil component.

Background

Conventional coil components and the like may use magnetic members. Such coil components are required to be miniaturized, and magnetic members are required to have high magnetic permeability and high saturation magnetic flux density. Therefore, a magnetic sheet for manufacturing a coil component having such a magnetic member with a high magnetic permeability and a high saturation magnetic flux density is disclosed (for example, see patent document 1).

Patent document 1 discloses that such a magnetic sheet is composed of a magnetic sheet in which a magnetic filler contains a binder resin and the filling rate of the magnetic filler is at least 90 wt% in order to have high permeability and high saturation magnetic flux density. The magnetic filler is a magnetic sheet containing at least 1 metal particle of amorphous metal and/or crystalline metal subjected to an insulating surface treatment and having a surface resistance value of 106 Ω/□ or more. That is, the magnetic sheet disclosed in patent document 1 is highly filled with a magnetic filler.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2014-127624

Disclosure of Invention

However, as described above, the magnetic sheet disclosed in patent document 1 is highly filled with metallic magnetic particles in order to improve magnetic permeability, and therefore, when a coil component is manufactured using such a magnetic sheet, there is a problem that direct current superposition characteristics, which are one of characteristics of the coil component, are deteriorated.

Accordingly, a primary object of the present invention is to provide a coil component that can improve direct current superposition characteristics while maintaining high magnetic permeability.

Another object of the present invention is to provide a method for producing a magnetic powder mixed resin material for obtaining a coil component that can improve direct current superposition characteristics while maintaining high magnetic permeability.

The coil component of the present invention is characterized by comprising a unit body including a coil conductor formed by winding a lead wire, and a magnetic body portion containing metallic magnetic particles, resin, and insulator particles coated with an insulating film, and an external electrode electrically connected to a lead portion of the coil conductor and disposed on a surface of the unit body, wherein the insulator particles have a lower relative permeability than the metallic magnetic particles, and main components of the insulator particles and the insulating film are the same kind of compound.

The method for producing a magnetic powder mixed resin material according to the present invention is a method for producing a magnetic powder mixed resin material, including the steps of: a step of mixing the metallic magnetic particles with an insulator material, a step of forming an insulating film on the surface of the metallic magnetic particles by using a part of the insulator material through mechanochemical treatment, and a step of mixing the metallic magnetic particles coated with the insulating film, the remaining part of the insulator material, and a resin material; the insulator material has a lower relative permeability than the metallic magnetic particles.

In the coil component of the present invention, since the insulator particles having a lower magnetic property than the metal magnetic particles are dispersed and arranged in the entire magnetic body portion, the insulating film of the insulator particles and the metal magnetic particles dispersed in the magnetic body portion interrupts the flow of the magnetic flux, and the dc superimposition characteristic can be improved, and the flow of the magnetic flux is not completely interrupted, and therefore, the reduction of the inductance value can be suppressed.

Further, since the insulating particles and the material of the insulating film are the same in composition, it is not necessary to remove the insulating particles that have to be removed in the production process, and a magnetic powder mixed resin material that can obtain the coil component as described above can be produced.

According to the present invention, a coil component capable of improving direct current superposition characteristics while maintaining high magnetic permeability can be provided.

Further, according to the present invention, it is possible to provide a method for producing a magnetic powder mixed resin material for obtaining a coil component capable of improving direct current superposition characteristics while maintaining high magnetic permeability.

The above and other objects, features and advantages of the present invention will be further apparent from the following description of the modes for carrying out the invention with reference to the accompanying drawings.

Drawings

Fig. 1 is an external perspective view schematically showing an embodiment of a coil component according to the present invention.

Fig. 2 is a perspective view of a magnetic section in which a coil conductor is embedded in the coil component shown in fig. 1.

Fig. 3 is a sectional view taken along line III-III of fig. 1 showing a coil component according to the present invention.

Fig. 4 shows a cross-sectional view taken along line IV-IV of fig. 1 of the coil component of the present invention.

Fig. 5(a) is a schematic cross-sectional view of a unit body of the coil component of the present invention, and (b) is a partially enlarged view of a portion a.

Fig. 6(a) is a perspective view showing a modified example of the unit cell of the coil component according to the embodiment of the present invention, and (b) is a perspective view seen from a direction different from (a).

Description of the symbols

10 coil component

12. 112 unit body

12a, 112a first main surface 1

12b, 112b the 2 nd main surface

12c, 112c 1 st side

12d, 112d side 2

12e, 112e 1 st end face

12f, 112f 2 nd end face

14. 114 magnetic body

14a1 insulating film

114a 1 st magnetic body

114b 2 nd magnetic body

16. 116 coil conductor

15 insulator particles

20. 120 winding part

22a, 122a No. 1 lead-out part

22b, 122b No. 2 lead-out part

24a 1 st exposed part

24b 2 nd exposed part

30 external electrode

30a 1 st external electrode

30b No. 2 external electrode

32a first base electrode layer

32b No. 2 base electrode layer

34a 1 st plating layer

34b second plating layer

36a layer of 1 st Ni plating

36b No. 2 Ni plating layer

38a 1 st Sn plating layer

38b second Sn plating layer

40 protective layer

x direction of pressure (height direction)

y width direction

z longitudinal direction

Detailed Description

1. Coil component

Hereinafter, the coil component of the present invention will be described in detail with reference to the drawings.

Fig. 1 is an external perspective view schematically showing an embodiment of a coil component according to the present invention. Fig. 2 is a perspective view of a magnetic section in which a coil conductor is embedded in the coil component shown in fig. 1. Fig. 3 is a sectional view taken along line III-III of fig. 1 showing a coil component according to the present invention. Fig. 4 is a sectional view taken along line IV-IV of fig. 1 showing a coil component according to the present invention. Fig. 5(a) is a schematic cross-sectional view of a unit body of the coil component of the present invention, and fig. 5(b) is a partially enlarged view of a portion a.

The coil component 10 includes a cube-shaped unit body 12 and an external electrode 30.

(A) Unit body

The unit body 12 includes a magnetic body 14 and a coil conductor 16 embedded in the magnetic body 14. The unit body 12 has a1 st main surface 12a and a 2 nd main surface 12b facing in the pressing direction x, a1 st side surface 12c and a 2 nd side surface 12d facing in the width direction y orthogonal to the pressing direction x, and a1 st end surface 12e and a 2 nd end surface 12f facing in the length direction z orthogonal to the pressing direction x and the width direction y. The size of the unit body 12 is not particularly limited.

(B) Magnetic body

As shown in fig. 5, the magnetic body 14 includes metallic magnetic particles 14a, a resin material 14b, and insulator particles 15.

The resin material is not particularly limited, and examples thereof include organic materials such as epoxy resin, phenol resin, polyester resin, polyimide resin, and polyolefin resin. The number of resin materials may be only 1, or may be 2 or more.

The metal magnetic particles 14a are made of 1 st metal magnetic particles. The metal magnetic particles may further include 2 nd metal magnetic particles.

The 1 st metal magnetic particles may have an average particle diameter of 10 μm or more. The 1 st metal magnetic particles preferably have an average particle diameter of 200 μm or less, more preferably 100 μm or less, and still more preferably 80 μm or less. By setting the average particle diameter of the 1 st metal magnetic particles to 10 μm or more, the filling ratio of the metal magnetic particles can be increased, and the effective permeability of the magnetic body portion can be improved.

The 2 nd metal magnetic particles have an average particle diameter smaller than that of the 1 st metal magnetic particles. The 2 nd metal magnetic particles have an average particle diameter of 10 μm or less. As described above, since the average particle diameter of the 2 nd metal magnetic particles is smaller than the average particle diameter of the 1 st metal magnetic particles, the filling property of the metal magnetic particles in the magnetic body portion 14 is further improved, and the magnetic characteristics of the coil component 10 can be improved.

Here, the average particle diameter refers to an average particle diameter D50 (particle diameter corresponding to a cumulative percentage of 50% on a volume basis). The average particle diameter D50 can be measured, for example, by a dynamic light scattering particle size analyzer (UPA, manufactured by japan electronics corporation).

The 1 st metal magnetic particle and the 2 nd metal magnetic particle are not particularly limited, and examples thereof include iron, cobalt, nickel, gadolinium, and an alloy containing 1 or 2 or more of them. Preferably, the 1 st metallic magnetic particles are iron or an iron alloy. The iron alloy is not particularly limited, and examples thereof include Fe-Si, Fe-Si-Cr, and Fe-Si-Al. The number of the 1 st metal magnetic particle and the number of the 2 nd metal magnetic particle may be only 1, or may be 2 or more.

As shown in fig. 5, the surfaces of the 1 st metal magnetic particle and the 2 nd metal magnetic particle are covered with an insulating film 14a 1. The insulating film 14a1 covers the surfaces of the metal magnetic particles, thereby increasing the resistivity inside the magnetic body 14.

The material of the insulating film 14a1 has a lower relative permeability than the metallic magnetic particles 14 a. More preferably non-magnetic. Specifically, the material of the insulating film 14a1 is phosphate glass. An insulating film formed of zinc phosphate glass subjected to mechanochemical treatment is particularly preferable. The glass component contains at least one of Si, P, Bi, B, Ba, V, Sn, Te, K, Ca, Zn, Na, and Li.

The thickness of the insulating film 14a1 is not particularly limited, and may be preferably 5nm to 500nm, more preferably 10nm to 250 nm. The average thickness of the insulating film 14a1 is preferably 30nm or more. By further increasing the thickness of insulating film 14a1, the resistivity of magnetic body 14 can be further increased. Further, by increasing the thickness of the insulating film, short-circuiting between the metallic magnetic particles and the coil conductor can be prevented when the metallic magnetic particles are highly filled, and improvement in dielectric breakdown voltage can be expected. On the other hand, by further reducing the thickness of the insulating film 14a1, the amount of metal magnetic particles in the magnetic section 14 can be further increased, and the magnetic properties of the magnetic section 14 can be improved.

The film thickness of the insulating film 14a1 of the metal magnetic particles is measured by observation with a TEM (transmission electron microscope) after FIB (focused ion beam) processing. Since the film thickness varies, for example, 15 spots (5 particles, 3 spots per 1 particle) or more are observed, and the average film thickness is determined by averaging the observed spots. The observation magnification is preferably about 50000 to 500000 times.

The content of the 1 st metal magnetic particles and the 2 nd metal magnetic particles in the magnetic body portion 14 is preferably 50 vol% or more, more preferably 60 vol% or more, and further preferably 70 vol% or more of the entire magnetic body portion. By setting the content of the 1 st metal magnetic particle and the 2 nd metal magnetic particle within this range, the magnetic characteristics of the coil component of the present invention are improved. The content of the 1 st metal magnetic particles and the 2 nd metal magnetic particles is preferably 99 vol% or less, more preferably 95 vol% or less, and still more preferably 90 vol% or less of the entire magnetic body 14. By setting the content of the 1 st metal magnetic particles and the 2 nd metal magnetic particles in this range, the resistivity of the magnetic body portion 14 can be further increased.

In the surface portion of the magnetic body 14, the region adjacent to the coil conductor 16 may be removed. By removing the magnetic body portion 14 in the region adjacent to the coil conductor 16, the gap between the magnetic body portion 14 and the coil conductor 16 becomes large, and the exposed area of the coil conductor 16 increases. This increases the area of connection between the coil conductor 16 and the external electrode 30, and thus can improve the bonding strength and reduce the dc resistance.

The insulator particles 15 have a lower relative permeability than the metallic magnetic particles 14 a. More preferably, the insulator particles 15 are non-magnetic. The insulator particles 15 preferably contain a glass component. The glass component contains at least one of Si, P, Bi, B, Ba, V, Sn, Te, K, Ca, Zn, Na, and Li.

The insulating particles 15 and the insulating film 14a1 covering the metallic magnetic particles 14a are made of the same type of compound as the main component.

The insulator particles 15 contained in the magnetic body 14 are determined as follows. That is, the components can be determined by exposing the cross section of the magnetic body 14 by ion milling, polishing, or the like, and performing elemental analysis of the insulating coating 14a1 of the metallic magnetic particles 14a and the insulating particles 15 contained in the magnetic body 14 by EDX (Energy Dispersive X-ray spectroscopy). In the case where the judgment as to whether or not the compounds are of the same type deviates from the stoichiometric ratio, the compounds are regarded as being of the same type.

In particular, when the glass component is zinc phosphate glass, if the amount of the insulator particles 15 is too large, a decrease in inductance due to a moisture-resistant setting test (hereinafter referred to as moisture-resistant failure) occurs, and therefore, the ratio of the area of the insulator particles to the area of the cross section of the magnetic portion is preferably 0.1% to 5.0%, and more preferably 0.1% to 4.0% with respect to the content of the insulator particles. The content of the insulator particles is more preferably 1.0% to 2.0% of the area of the insulator particles relative to the area of the cross section of the magnetic body.

The content of the insulator particles is preferably 0.1% to 6.0%, more preferably 0.1% to 4.8%, of the area of the insulator particles in the cross section of the magnetic body relative to the area of the metallic magnetic particles. More preferably 1.2% to 2.4%.

This can significantly improve the dc superimposition characteristics of the coil component 10.

The ratio of the area of each of the above-described insulator particles (area ratio) was calculated as follows.

That is, first, the cross section of the coil component 10 is exposed using a cross-section milling apparatus, and observed by an SEM (scanning electron microscope). Since the insulator particles are observed with a contrast different from that of the metallic magnetic particles, the external electrode, the coil conductor, and the resin material, the observation is easy. In the observed cross section, the content of the insulator particles was calculated as an area ratio. The magnification for observation is preferably about 500 to 2000 times.

In the present embodiment, the ratio of the area of the insulator particles is substantially equal to the ratio of the volume of the insulator particles.

The main components of the materials of the insulating film 14a1 covering the insulating particles 15 and the metallic magnetic particles 14a are the same. In this way, the edge particles 15 can be added as a result by directly mixing the insulating particles 15 into the magnetic body portion 14 without removing the residues of the insulating particles 15 generated by the coating treatment of the metallic magnetic particles 14 a.

The non-magnetic layer is inserted into the magnetic section 14 so as to sandwich the coil conductor 16. This can improve the dc superimposition characteristics of the coil component 10. The nonmagnetic layer is preferably made of the same component as that of the magnetic section 14. This makes it difficult for the nonmagnetic layer in the magnetic section 14 to be peeled off from the other layers.

(C) Coil conductor

The coil conductor 16 includes a winding portion 20 formed by winding a conductive wire including a conductive material in a coil shape, a1 st lead portion 22a led out to one side of the winding portion 20, and a 2 nd lead portion 22b led out to the other side of the winding portion 20.

The winding portion 20 is formed by winding 2 layers. The coil conductor 16 is formed by winding a rectangular wire into an alpha-coil shape. The dimension of the rectangular wire in the width direction y is preferably 15 to 200 μm, and the dimension of the rectangular wire in the pressing direction x is preferably 50 to 500 μm.

The 1 st lead portion 22a is exposed from the 1 st end surface 12e of the unit body 12, and the 1 st exposed portion 24a is disposed, and the 2 nd lead portion 22b is exposed from the 2 nd end surface 12f of the unit body 12, and the 2 nd exposed portion 24b is disposed.

Here, a modification of the unit body 12 of the coil component 10 according to the embodiment of the present invention is shown.

Fig. 6(a) is a perspective view showing a modified example of the unit cell of the coil component according to the embodiment of the present invention, and fig. 6(b) is a perspective view seen from a direction different from (a).

As shown in fig. 6(a) and (b), the unit body 112 includes a magnetic body portion 114 and a coil conductor 116 embedded in the magnetic body portion 114. The cell body 112 is formed in a substantially cubic shape, and has a1 st main surface 112a and a 2 nd main surface 112b facing in the height direction x, a1 st side surface 112c and a 2 nd side surface 112d facing in the width direction y orthogonal to the height direction x, and a1 st end surface 112e and a 2 nd end surface 112f facing in the length direction z orthogonal to the height direction x and the width direction y.

The magnetic body portion 114 includes a1 st magnetic body portion 114a disposed inside the unit body 112 and a 2 nd magnetic body portion 114b covering the 1 st magnetic body portion 114a and the coil conductor 116.

The coil conductor 116 includes a winding portion 120 disposed on one surface side of the 1 st magnetic body portion 114a and formed by winding a conductive wire including a conductive material in a coil shape, a1 st lead portion 122a led out to one side of the winding portion 120, and a 2 nd lead portion 122b led out to the other side of the winding portion 120. The 1 st lead portion 122a is led out to the 1 st end surface 112e side of the 2 nd main surface 112b of the unit body 112 and exposed, and the 2 nd lead portion 122b is led out to the 2 nd end surface 112f side of the 2 nd main surface 112b of the unit body 112 and exposed.

In this manner, the 1 st drawn part 122a may be formed and disposed on the 2 nd main surface 112b of the cell body 112, and the 2 nd drawn part 122b may be formed and disposed on the 2 nd main surface 112b of the cell body 112.

The coil conductor 16 is constituted by a wire or a wire (wire). The conductive material of the coil conductor 16 is not particularly limited, and examples thereof include Ag, Au, Cu, Pd, Ni, and the like. Preferably, Cu is used as the conductive material. The number of the conductive materials may be only 1, or may be 2 or more.

The wire forming the coil conductor 16 is coated with an insulating material to form an insulating coating. By covering the conductive wires forming the coil conductors 16 with an insulating material, the coil conductors 16 wound around each other and the coil conductors 16 and the magnetic body portions 14 can be insulated more reliably.

No insulating film is formed on the 1 st exposed portion 24a and the 2 nd exposed portion 24b of the coil conductor 16. Therefore, the external electrode 30 is easily formed by the plating treatment. In addition, the resistance value in the electrical connection between the coil conductor 16 and the external electrode 30 can be further reduced.

The insulating material of the insulating film is not particularly limited, and examples thereof include urethane resin, polyester resin, epoxy resin, and polyamideimide resin. Preferably, a polyamideimide resin is used as the insulating film.

The thickness of the insulating film is preferably 2 μm to 10 μm.

(D) External electrode

External electrodes 30 are disposed on the 1 st end face 12e side and the 2 nd end face 12f side of the unit cell 12. The external electrode 30 has a1 st external electrode 30a and a 2 nd external electrode 30 b.

The 1 st external electrode 30a is disposed on the surface of the 1 st end face 12e of the unit cell 12. The 1 st external electrode 30a may be formed to extend from the 1 st end face 12e to cover a portion of each of the 1 st main face 12a, the 2 nd main face 12b, the 1 st side face 12c, and the 2 nd side face 12d, or may be formed to extend from the 1 st end face 12e to the 2 nd main face 12b to cover a portion of each of the 1 st end face 12e and the 2 nd main face 12 b. As shown in fig. 6, when the 1 st lead portion 122a of the coil conductor 116 is formed and exposed from the 2 nd main surface 112b, the 1 st external electrode 30a may be formed so as to cover a part of the 2 nd main surface 112 b. At this time, the 1 st external electrode 30a is electrically connected to the 1 st lead portion 22a of the coil conductor 16.

The 2 nd external electrode 30b is disposed on the surface of the 2 nd end face 12f of the unit cell 12. The 2 nd external electrode 30b may be formed to extend from the 2 nd end face 12f to cover a portion of each of the 1 st main face 12a, the 2 nd main face 12b, the 1 st side face 12c, and the 2 nd side face 12d, or may be formed to extend from the 2 nd end face 12f to the 2 nd main face 12b to cover a portion of each of the 2 nd end face 12f and the 2 nd main face 12 b. As shown in fig. 6, when the 2 nd lead portion 122b of the coil conductor 116 is formed and exposed from the 2 nd main surface 112b, the 2 nd external electrode 30b may be formed so as to cover a part of the 2 nd main surface 112 b. At this time, the 2 nd external electrode 30b is electrically connected to the 2 nd lead portion 22b of the coil conductor 16.

The thickness of each of the 1 st external electrode 30a and the 2 nd external electrode 30b is not particularly limited, and may be, for example, 1 μm to 50 μm, and preferably 5 μm to 20 μm.

The 1 st external electrode 30a includes a1 st underlying electrode layer 32a and a1 st plating layer 34a disposed on a surface of the 1 st underlying electrode layer 32 a. Similarly, the 2 nd external electrode 30b includes a 2 nd underlying electrode layer 32b and a 2 nd plating layer 34b disposed on a surface of the 2 nd underlying electrode layer 32 b.

The 1 st underlying electrode layer 32a is disposed on the surface of the 1 st end face 12e of the unit cell 12. The 1 st underlying electrode layer 32a may be formed to extend from the 1 st end surface 12e and cover a portion of each of the 1 st main surface 12a, the 2 nd main surface 12b, the 1 st side surface 12c, and the 2 nd side surface 12d, or may be formed to extend from the 1 st end surface 12e and cover a portion of each of the 1 st end surface 12e and the 2 nd main surface 12 b. In addition, as shown in fig. 6, when the 1 st lead portion 122a of the coil conductor 116 is formed and exposed from the 2 nd main surface 112b, the 1 st underlying electrode layer 32a may be formed so as to cover a part of the 2 nd main surface 112 b.

The 2 nd underlying electrode layer 32b is disposed on the surface of the 2 nd end face 12f of the unit cell 12. The 2 nd underlying electrode layer 32b may be formed to extend from the 2 nd end surface 12f to cover a portion of each of the 1 st main surface 12a, the 2 nd main surface 12b, the 1 st side surface 12c, and the 2 nd side surface 12d, or may be formed to extend from the 2 nd end surface 12f to cover a portion of each of the 2 nd end surface 12f and the 2 nd main surface 12 b. In addition, as shown in fig. 6, when the 2 nd lead portion 122b of the coil conductor 116 is formed and exposed from the 2 nd main surface 112b, the 2 nd underlying electrode layer 32b may be formed so as to cover a part of the 2 nd main surface 112 b.

The 1 st and 2 nd base electrode layers 32a and 32b are made of a conductive material, preferably 1 or more than 1 metal material selected from Au, Ag, Pd, Ni, and Cu.

The 1 st underlying electrode layer 32a and the 2 nd underlying electrode layer 32b are formed by applying, sputtering, and plating a conductor paste.

The 1 st plating layer 34a is configured to cover the 1 st base electrode layer 32 a. Specifically, the 1 st plating layer 34a may be disposed so as to cover the 1 st underlying electrode layer 32a disposed on the 1 st end surface 12e, may be further disposed so as to extend from the 1 st end surface 12e and cover the surface of the 1 st underlying electrode layer 32a provided on the 1 st main surface 12a, the 2 nd main surface 12b, the 1 st side surface 12c, and the 2 nd side surface 12d, or may be disposed so as to cover the 1 st underlying electrode layer 32a, and the 1 st underlying electrode layer 32a may be disposed so as to extend from the 1 st end surface 12e and cover a portion of each of the 1 st end surface 12e and the 2 nd main surface 12 b. As shown in fig. 6, when the 1 st lead portion 122a of the coil conductor 116 is formed and led directly to the 2 nd main surface 112b, the 1 st underlying electrode layer 32a disposed on the 2 nd main surface 112b may be formed so as to be covered.

The 2 nd plating layer 34b is configured to cover the 2 nd base electrode layer 32 b. Specifically, the 2 nd plating layer 34b may be disposed so as to cover the 2 nd underlying electrode layer 32b disposed on the 2 nd end surface 12f, may be disposed so as to extend from the 2 nd end surface 12f and cover the surface of the 2 nd underlying electrode layer 32b disposed on the 1 st main surface 12a, the 2 nd main surface 12b, the 1 st side surface 12c, and the 2 nd side surface 12d, or may be disposed so as to cover the 2 nd underlying electrode layer 32b, and the 2 nd underlying electrode layer 32b may be disposed so as to extend from the 2 nd end surface 12f and cover a part of each of the 2 nd end surface 12f and the 2 nd main surface 12 b. As shown in fig. 6, when the 2 nd lead portion 122b of the coil conductor 116 is formed and led directly to the 2 nd main surface 112b, the 2 nd underlying electrode layer 32b disposed on the 2 nd main surface 112b may be formed so as to be covered.

As the metal material of the 1 st plating layer 34a and the 2 nd plating layer 34b, for example, at least 1 kind selected from Cu, Ni, Ag, Sn, Pd, Ag — Pd alloy, Au, or the like is contained.

The 1 st plating layer 34a and the 2 nd plating layer 34b may be formed in multiple layers.

The 1 st plating layer 34a has a 2-layer structure of a1 st Ni plating layer 36a and a1 st Sn plating layer 38a formed on the surface of the 1 st Ni plating layer 36 a. The 2 nd plating layer 34b has a 2 nd layer structure of a 2 nd Ni plating layer 36b and a 2 nd Sn plating layer 38b formed on the surface of the 2 nd Ni plating layer 36 b.

(E) Protective layer

In the present embodiment, the protective layer 40 is formed on the surface of the unit body 12 except for the 1 st exposed portion 24a exposed at the 1 st end face 12e and the 2 nd exposed portion 24b exposed at the 2 nd end face 12f of the unit body 12. The protective layer 40 is made of a resin material having high electrical insulation, such as acrylic resin, epoxy resin, or polyimide. In the present invention, the protective layer is not essential and may not be present.

In the coil component 10, if the dimension in the longitudinal direction z is set to L dimension, the L dimension is preferably 1.0mm to 12.0 mm. When the dimension y of the coil component 10 in the width direction is set to the dimension W, the dimension W is preferably 0.5mm to 12.0 mm. If the dimension of the coil component 10 in the pressing direction x is set to the T dimension, the T dimension is preferably 0.5mm to 6.0 mm.

2. Method for manufacturing coil component

Next, a method for manufacturing the coil component will be described. First, a method for producing a magnetic powder mixed resin material will be described.

(A) Preparation of metallic magnetic particles

First, metallic magnetic particles are prepared. The metallic magnetic particles are not particularly limited, and for example, Fe-based soft magnetic material powders such as α -Fe, Fe-Si-Cr, Fe-Si-Al, Fe-Ni, and Fe-Co can be used. The material form of the metallic magnetic particles is preferably amorphous having good soft magnetic properties, but is not particularly limited thereto, and may be crystalline.

The metal magnetic particles may be 2 or more kinds of metal magnetic particles having different average particle diameters. The metal magnetic particles are dispersed in the resin material. From the viewpoint of improving the filling efficiency of the metallic magnetic particles, for example, metallic magnetic particles having different average particle diameters, such as 1 st metallic magnetic particles having an average particle diameter of 10 to 40 μm and 2 nd metallic magnetic particles having an average particle diameter of 5 μm or less, can be used.

(B) Formation of insulating coating

Next, the surfaces of the metallic magnetic particles are coated with an insulating film. Here, when the insulating film is formed by a mechanical method, the metal magnetic particles and the insulating material powder are put into a rotary container, and the particles are combined by a mechanochemical treatment, whereby the surface of the magnetic powder is coated with the insulating film.

The insulating film is preferably formed to a thickness of 10nm to 250nm, and the average film thickness is 30nm or more. The thickness of the insulating film can be controlled by adjusting the treatment time and the amount of the insulating material powder added during the mechanochemical treatment. That is, the thickness of the insulating film can be increased by increasing the amount of the insulating material powder to be added and extending the treatment time of the mechanochemical treatment.

(C) Preparation of insulator particles

Next, insulator particles are prepared. The insulator particles are insulator particles having a lower magnetic property than the metallic magnetic particles. More preferably, the insulator particles are non-magnetic. The insulator particles preferably contain a glass component. The glass component contains at least one of Si, P, Bi, B, Ba, V, Sn, Te, K, Ca, Zn, Na, and Li.

The insulating particles and the insulating film covering the metal magnetic particles have the same main component.

(D) Production of magnetic sheet

Next, metal magnetic particles coated with an insulating film are prepared.

Next, a resin material and insulator particles are added to the metal magnetic particles, and the mixture is mixed in a wet manner to produce a magnetic powder mixed resin material. The resin material is not particularly limited, and for example, an epoxy resin, a phenol resin, a polyester resin, a polyimide resin, a polyolefin resin, or the like can be used.

In this way, the magnetic powder is mixed with the resin material to form a slurry, and then, the slurry is subjected to a molding process using a doctor blade method or the like, and then dried to produce a magnetic sheet.

The amount of the insulator particles to be added is preferably 0.1 to 5.0 vol%, more preferably 0.1 to 4.0 vol%, and still more preferably 1.0 to 2.0 vol% with respect to the magnetic powder mixed resin material. The content of the insulator particles is preferably 0.1 to 6.0 vol%, more preferably 0.1 to 4.8 vol%, and still more preferably 1.2 to 2.4 vol% of the amount of the insulator particles added to the amount of the metallic magnetic particles added.

(E) Production of aggregate matrices

Next, an α -coil shaped coil conductor 16 made of a rectangular wire having Cu as a wire conductor and covered with an insulating film was prepared.

Next, the unit body 12 in which the coil conductor 16 is embedded is manufactured.

First, a1 st mold is prepared, and the coil conductors 16 are arranged in a matrix on the 1 st mold.

Next, a1 st magnetic material sheet containing a mixture of 1 st metallic magnetic material particles, 2 nd metallic magnetic material particles, a resin material, and insulator particles is superimposed on the coil conductors 16, and then the 1 st magnetic material sheet is sandwiched between a1 st die and a 2 nd die and is subjected to 1-time press molding. By the 1-time press molding, at least a part of the coil conductor 16 was embedded in the sheet, and the mixture was filled in the coil conductor 16 to prepare a1 st molded body.

Next, the 1 st molded body having the coil conductor 16 embedded therein obtained by 1-time press molding was released from the 1 st mold, and then another 2 nd magnetic material sheet was superimposed on the exposed surface of the coil conductor 16. Then, the 2 nd magnetic sheet is press-molded 2 times by sandwiching it between the 1 st-time molded body on the 2 nd mold and the 3 rd mold.

The aggregate matrix (2 nd molded body) in which the entire coil conductor 16 is embedded in the 1 st and 2 nd magnetic material sheets is manufactured by 2-time press molding as described above.

(F) Production of cell bodies

Subsequently, the 2 nd mold and the 3 rd mold were separated to obtain an aggregate matrix. Then, the assembly base is cut and singulated using a cutting tool such as a dicer, thereby producing the unit body 12 in which the coil conductor 16 is embedded such that the 1 st exposed portion 24a and the 2 nd exposed portion 24b of the coil conductor 16 are exposed from both end surfaces of the unit body 12. The collective substrate can be divided into the unit cells 12 by using a dicing blade, various laser devices, a dicer, various cutters, and a die. In a preferred embodiment, the cut surface of each unit cell 12 is polished by a roller.

Next, a protective layer 40 is formed on the entire surface of the cell body 12 obtained above. The protective layer 40 may be formed by electrodeposition coating, spray coating, dipping, or the like.

By irradiating the periphery of the portion of the coil conductor 16 of the unit cell 12 covered with the protective layer 40, where the 1 st exposed portion 24a and the 2 nd exposed portion 24b are arranged, with laser light, the protective layer and the insulating film covering the metallic magnetic particles and the metallic magnetic particles around the portion of the coil conductor 16, where the 1 st exposed portion 24a and the 2 nd exposed portion 24b are arranged, are removed, and the metallic magnetic particles are melted.

(G) Formation of external electrodes

Next, the 1 st external electrode 30a is formed on the 1 st end face 12e of the unit cell 12, and the 2 nd external electrode 30b is formed on the 2 nd end face 12 f.

First, the unit 12 is plated with Cu by electrolytic barrel plating to form an underlying electrode layer. Next, a Ni plating layer is formed by Ni plating on the surface of the base electrode layer, and a Sn plating layer is further formed by Sn plating to form the external electrode 30. Thus, the 1 st exposed portion 24a of the coil conductor 16 is electrically connected to the 1 st external electrode 30a, and the 2 nd exposed portion 24b of the coil conductor 16 is electrically connected to the 2 nd external electrode 30 b.

The coil component 10 is manufactured as above.

In the mechanochemical treatment in the step of forming the insulating film on the metallic magnetic particles, if an excessive amount of the insulating film material is charged, not all of the insulating film material may be formed, and some of the insulating film material may be left as a residue. The residues may be mixed into the magnetic body 14 to function as insulator particles. Therefore, it is not necessary to remove the material of the insulating film which becomes the residue in this embodiment.

In the mechanochemical treatment in the step of forming the insulating film on the surface of the metal magnetic particles, the film thickness of the insulating film of the metal magnetic particles and the content of the insulating particles in the magnetic body portion 14 can be adjusted by adjusting the amount of the insulating material powder to be charged. The content of the insulator particles in the magnetic body 14 can also be adjusted by removing the residue of the insulator material powder.

The removal of the residue of the insulator material powder may be performed by air classification, washing, or screen treatment.

In the coil component 10 shown in fig. 1, since the magnetic part 14 contains insulator particles having a magnetic property lower than that of the metallic magnetic particles, the dc bias characteristic is improved.

In the coil component 10 shown in fig. 1, since the insulator particles having a lower magnetic property than the metal magnetic particles are dispersed and arranged in the entire magnetic body 14, the insulating film of the insulator particles and the metal magnetic particles dispersed in the magnetic body 14 interrupts the flow of the magnetic flux, and the dc superimposition characteristic can be improved, and the flow of the magnetic flux is not completely interrupted, and therefore, the decrease in inductance can be suppressed.

Further, in the coil component 10 shown in fig. 1, the distance between the metal magnetic particles can be increased by increasing the thickness of the insulating film covering the metal magnetic particles to, for example, 30nm or more, and therefore, the dc superimposition characteristics are similarly improved, and the reduction in inductance value can also be suppressed.

Therefore, by including insulator particles having a lower magnetic property than the metallic magnetic particles in the magnetic section 14 and increasing the thickness of the insulating film covering the metallic magnetic particles, the coil component 10 having improved dc superimposition characteristics can be obtained.

In addition, if the amount of the insulator particles added is 0.1 vol% to 4.0 vol% based on the magnetic powder mixed resin material, it is possible to suppress a decrease in the L value of the coil component due to the moisture-resistant setting test. Further, if the ratio of the addition amount of the insulator particles to the addition amount of the metallic magnetic particles is 0.1 vol% to 4.8 vol%, a decrease in the L value due to the moisture-resistant setting test can be suppressed. This can improve the reliability of the coil component 10.

3. Examples of the experiments

Next, in order to confirm the effect of the coil component using the magnetic powder mixed resin material of the present invention, experiments for evaluating the effective permeability, the saturation magnetic flux density, and the L value reduction rate after the moisture resistance standing test were performed.

(1) Specification of the sample

The specifications of the samples used in this experiment are as follows.

The dimensions (design values) of the coil component were 1.6mm in L-dimension, 0.8mm in W-dimension, and 0.8mm in T-dimension.

Material of the magnetic body

1 st metal magnetic particle: fe-based alloy (Fe-Si-Cr-based alloy), average particle diameter: 35 μm

2 nd metal magnetic particles: fe-based alloy (Fe-Si-Cr-based alloy), average particle diameter: 5 μm

Material of the insulating coating: phosphate glass

Insulator particles: phosphate glass

Resin: epoxy resin

Material of the coil conductor: cu

Material of the protective layer: acrylic resin, film thickness: 4 μm

Structure of external electrode

3-layer structure of Cu-plated, Ni-plated and Sn-plated

The addition amounts of the insulator particles added to the respective samples are shown in table 1.

(2) Calculation of effective permeability

The effective permeability of the coil component as each sample was calculated as follows.

The inductance of the coil component was measured by an impedance analyzer, and the inductance at 1MHz was measured. For example, when a coil component is manufactured using a material having an effective permeability of 20 and a saturation magnetic flux density Bs of 0.90, the coil component is manufactured by trial using a coil conductor having an inductance L of 0.26 μ H and a dc saturation current Isat of 5.0A. Since the inductance varies linearly with respect to the effective permeability, the inductance is thereby converted into the effective permeability.

(3) Measurement of saturation magnetic flux density

The saturation magnetic flux density of each coil component as a sample was measured as follows.

The change in inductance when a direct current was applied was measured, and the current value at which the inductance was reduced by 30% from the initial inductance was defined as the direct current saturation current. For example, when a coil component is manufactured using a material having the above effective permeability of 20 and the saturation magnetic flux density Bs of 0.90, the coil component is manufactured by trial using a coil conductor having a known inductance L of 0.26 μ H and a dc saturation current Isat of 5.0A. Since the saturation magnetic flux density is related to the dc saturation current, the dc saturation current is converted into the saturation magnetic flux density.

(4) Method for measuring moisture-proof standing test

The coil components as the respective samples were subjected to a wet-proof set test as follows. That is, the L values at the initial stage of the test and after 1000 hours were measured under the conditions of 85 ℃ and 85% RH (relative humidity), and the reduction rate was calculated.

(5) Method for measuring thickness of insulating film

The film thickness of the insulating film of the metal magnetic particles is measured by observation with a TEM (transmission electron microscope) after FIB (focused ion beam) treatment. Specifically, 5 particles were selected, and 3 sites and 15 sites in total were observed for each particle, and the average value thereof was calculated as the average film thickness. The observation magnification is 50000 to 500000 times.

The evaluation results of the "effective permeability", "saturation magnetic flux density", "the rate of decrease in L value after the moisture-resistant standing test" and "the average thickness of the insulating film" of the samples in each of the examples and comparative examples are shown in table 1.

(6) Evaluation results

First, from table 1, it was confirmed that if the addition amount of the insulator particles is increased relative to the magnetic powder mixed resin material, the effective permeability is slightly decreased. Further, from table 1, it was confirmed that if the amount of the insulator particles added to the magnetic powder mixed resin material is increased, the saturation magnetic flux density increases. Further, from table 1, it was confirmed that if the ratio of the insulator particles to the amount of the magnetic powder mixed resin material added exceeds 2.0 vol%, the L value is greatly reduced.

When the coil components of the samples of examples 1 to 5 were compared with the coil component of the sample of comparative example, it was confirmed that the increase rate of the saturation magnetic flux density was larger than the decrease rate of the effective magnetic permeability although the coil components of the samples of examples 1 to 5 contained the insulator particles.

In addition, when the coil components of the samples of example 5 and example 6 were compared, it was confirmed that the coil component of the sample of example 5 had a coil component having a high saturation magnetic flux density because the average thickness of the insulating coating film was 30 nm.

Further, in examples 1 to 4, if the amount of the insulator particles added to the magnetic portion is 1.0 vol% to 4.0 vol%, the decrease in L value after the moisture resistance leaving test can be suppressed to-8.0%. It was also found that if the amount of the insulating particles added to the metallic magnetic particles is 1.2 vol% to 4.8 vol%, the decrease in L value after the moisture resistance setting test can be suppressed to-8.0%.

Further, in examples 1 and 2, if the amount of the edge body particles added is 1.0 vol% to 2.0 vol%, the rate of decrease in L value after the moisture resistance standing test can be suppressed to-2.5%. It was also found that if the amount of the insulating particles added to the metallic magnetic particles is 1.2 vol% to 2.4 vol%, the decrease in L value after the moisture resistance leaving test can be suppressed to-2.5%.

The coil parts of the samples of examples 5 and 6, which contain zinc phosphate glass having a relatively high moisture resistance as the insulator particles, exhibited a high reduction rate of the L value after the moisture-resistant leaving test. This is considered to be because of the following reason. That is, if the environment is such as a humidity resistance standing test, the zinc phosphate glass as the insulator particles dissolves, and therefore, the metallic magnetic particles rust due to moisture entering from the gap formed after the dissolution, and the inductance (L value) is considered to be lowered.

As described above, the embodiments of the present invention are disclosed in the above description, but the present invention is not limited thereto.

That is, various modifications may be made to the mechanism, shape, material, number, position, arrangement, and the like of the above-described embodiments without departing from the scope of the technical idea and object of the present invention, and these are included in the present invention.