阅读说明：本技术 电子部件及其制造方法 (Electronic component and method for manufacturing the same ) 是由 大谷慎士 今枝大树 笹岛菜美子 须永友博 大门正美 吉冈由雅 于 2020-08-05 设计创作，主要内容包括：本发明提供一种能够提高金属磁性粉和金属膜的粘结信赖性的电子部件。电子部件具备由树脂和金属磁性粉的复合材料构成的复合体和配置在上述复合体的外表面上的金属膜,上述金属磁性粉包含Fe,上述金属膜主要包含Ni,与上述树脂和上述金属磁性粉接触。(The invention provides an electronic component capable of improving bonding reliability of metal magnetic powder and a metal film. An electronic component includes a composite body made of a composite material of a resin and a metal magnetic powder, and a metal film disposed on an outer surface of the composite body, wherein the metal magnetic powder contains Fe, and the metal film mainly contains Ni, and is in contact with the resin and the metal magnetic powder.)

1. An electronic component includes: a composite body composed of a composite material of a resin and a metal magnetic powder, and a metal film disposed on an outer surface of the composite body,

the metal magnetic powder contains Fe, and the metal magnetic powder contains Fe,

the metal film mainly contains Ni, and is in contact with the resin and the metal magnetic powder.

2. The electronic component according to claim 1, wherein the metal film is an amorphous film.

3. The electronic component according to claim 1 or 2, wherein the metal film further contains P.

4. The electronic component according to claim 3, wherein a P content relative to the metal film is 1 to 13 wt%.

5. The electronic component according to any one of claims 1 to 4, wherein the metal film further contains Fe.

6. The electronic component according to any one of claims 1 to 5, further comprising:

an inductance wiring extending in parallel with the outer surface within the composite body,

a columnar wiring extending from the inductance wiring perpendicularly to the outer surface, penetrating the inside of the composite body, and being exposed to the outer surface, and

a solder-attracting layer covering the metal film;

the metal film is in contact with the columnar wiring,

the metal film and the solder-attracting layer constitute an external terminal.

7. A method for manufacturing an electronic component by forming a metal film on the outer surface of a composite body made of a composite material of a resin and a metal magnetic powder by electroless plating,

the metal film mainly containing Ni is precipitated on the metal magnetic powder containing Fe by an autocatalytic reduction plating treatment to be in contact with the resin.

Technical Field

The invention relates to an electronic component and a method for manufacturing the same.

Background

Heretofore, as an electronic component, there is one described in japanese patent application laid-open No. 2013-225718 (patent document 1). The electronic component includes a composite (upper core and lower core) made of a composite material of a resin and a metal magnetic powder, and a metal film (terminal electrode) disposed on an outer surface of the composite. The metal magnetic powder contains Fe.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-225718.

Disclosure of Invention

However, in the above conventional electronic component, Cu having high conductivity is generally used for the metal film. On the other hand, since the linear expansion coefficient of the metal magnetic powder containing Fe and the linear expansion coefficient of the metal film containing Cu are greatly different from each other, there is a possibility that the adhesion between the metal magnetic powder and the metal film is reduced at the time of thermal load.

Accordingly, the present disclosure provides an electronic component capable of improving the adhesion reliability between a metal magnetic powder and a metal film, and a method for manufacturing the same.

In order to solve the above problem, an electronic component according to one embodiment of the present disclosure includes:

a composite body composed of a composite material of resin and metal magnetic powder;

a metal film disposed on an outer surface of the composite,

the above-mentioned metal magnetic powder contains Fe,

the metal film mainly contains Ni, and is in contact with the resin and the metal magnetic powder.

Here, the phrase "the metal film mainly contains Ni" means that the content of Ni in the metal film is 80 wt% or more.

According to the above aspect, since the metal magnetic powder contains Fe and the metal film mainly contains Ni, the linear expansion coefficient of the metal film can be made close to the linear expansion coefficient of the metal magnetic powder, and the decrease in the adhesive force between the metal magnetic powder and the metal film under a thermal load can be suppressed. Therefore, the adhesion reliability between the metal magnetic powder and the metal film can be improved.

In one embodiment of the electronic component, the metal film is an amorphous film.

According to the above embodiment, since the metal film is an amorphous film, the surface of the metal film can be formed flat and the thickness of the metal film can be reduced as compared with a crystal structure.

In one embodiment of the electronic component, the metal film further includes P.

According to the above embodiment, the metal film contains P, and therefore the corrosion resistance of the metal film is improved. Further, since Ni starts to precipitate without causing a substitution reaction with Fe, the adhesion between the metal magnetic powder and the metal film can be further improved.

In one embodiment of the electronic component, the content of P in the metal film is 1 to 13 wt%.

According to the above embodiment, the effect of improving the corrosion resistance and the adhesion of the metal film can be reliably obtained by setting the P content to 1 wt% or more with respect to the metal film. Further, the P content of the metal film is 13 wt% or less, and therefore, the film formability of the metal film is improved.

In one embodiment of the electronic component, the metal film further contains Fe.

According to the above embodiment, since the metal film contains Fe, the linear expansion coefficient of the metal film can be made close to that of the metal magnetic powder, and the decrease in the adhesive force between the metal magnetic powder and the metal film under thermal load can be further suppressed.

In one embodiment of the electronic component, the electronic component further includes:

an inductance wiring extending in parallel with the outer surface in the composite body,

a columnar wiring extending from the inductance wiring perpendicularly to the outer surface and penetrating the inside of the composite body to be exposed at the outer surface, and

a solder-attracting layer covering the metal film;

the metal film is in contact with the columnar wiring,

the metal film and the solder-attracting layer constitute an external terminal.

According to the above embodiment, an electronic component in which the bonding reliability between the composite and the external terminal is improved can be provided.

In one embodiment of the method for manufacturing an electronic component,

a method for manufacturing an electronic component by forming a metal film on the outer surface of a composite body made of a composite material of a resin and a metal magnetic powder by electroless plating,

the metal film mainly containing Ni is deposited on the metal magnetic powder containing Fe by an autocatalytic reduction plating treatment, and is brought into contact with the resin.

According to the above embodiment, since the metal magnetic powder contains Fe and the metal film mainly contains Ni, the linear expansion coefficient of the metal film can be made close to that of the metal magnetic powder, and the decrease in the adhesion between the metal magnetic powder and the metal film during thermal recombination can be suppressed. Further, since Ni starts to precipitate without causing a substitution reaction with Fe, the adhesion between the metal magnetic powder and the metal film can be improved. Therefore, an electronic component having improved adhesion reliability between the metal magnetic powder and the metal film can be produced.

According to the electronic component and the method for manufacturing the same of one embodiment of the present disclosure, the adhesion reliability between the metal magnetic powder and the metal film can be improved.

Drawings

Fig. 1A is a perspective plan view showing a first embodiment of an inductance component as an electronic component.

FIG. 1B is a cross-sectional view A-A of FIG. 1A.

Fig. 2 is a partially enlarged view of fig. 1B.

Fig. 3A is an explanatory diagram for explaining a method of manufacturing an inductance component.

Fig. 3B is an explanatory diagram for explaining a method of manufacturing the inductance component.

Fig. 3C is an explanatory diagram for explaining a method of manufacturing the inductance component.

Fig. 3D is an explanatory diagram for explaining a method of manufacturing the inductance component.

Description of the symbols

1 inductance component (electronic component), 2A first inductance element, 2B second inductance element, 10 unit body, 101 first end edge, 102 second end edge, 10a first main surface, 10B first side surface, 10c second side surface, 11 first magnetic layer (composite), 12 second magnetic layer (composite), 21 first inductance wiring, 22 second inductance wiring, 31 first columnar wiring, 32 second columnar wiring, 33 third columnar wiring, 34 fourth columnar wiring, 41 first external terminal, 410 metal film, 411 hydrophilic solder layer, 42 second external terminal, 43 third external terminal, 44 fourth external terminal, 50 insulating film, 61 insulating layer, 100 mother substrate, 135 resin, 136 metal magnetic powder

Detailed Description

Hereinafter, an electronic component according to an embodiment of the present disclosure will be described in detail with reference to the illustrated embodiments. The drawings include a part of schematic drawings, and may not reflect actual dimensions or ratios.

(first embodiment)

(constitution)

Fig. 1A is a perspective plan view showing a first embodiment of an electronic component. FIG. 1B is a cross-sectional view A-A of FIG. 1A. Fig. 2 is a partially enlarged view of fig. 1B.

An example of the electronic component is an inductance component 1. The inductance component 1 is a surface-mount electronic component mounted on a circuit board of an electronic device such as a personal computer, a DVD player, a digital camera, a TV, a mobile phone, or an auto-controller. However, the inductance component 1 may be not only a surface-mounted type but also a substrate-embedded type electronic component. The inductance component 1 is, for example, a rectangular parallelepiped component as a whole. However, the shape of the inductance component 1 is not particularly limited, and may be a cylindrical shape, a polygonal columnar shape, a truncated cone shape, or a polygonal truncated cone shape.

As shown in fig. 1A and 1B, the inductance component 1 includes: the unit body 10 having insulation properties, the first inductance element 2A and the second inductance element 2B disposed in the unit body 10, the first columnar wiring 31, the second columnar wiring 32, the third columnar wiring 33, and the fourth columnar wiring 34 embedded in the unit body 10 so that end surfaces thereof are exposed from the first main surface 10a of the long side shape of the unit body 10, the first external terminal 41, the second external terminal 42, the third external terminal 43, and the fourth external terminal 44 disposed on the first main surface 10a of the unit body 10, and the insulating film 50 provided on the first main surface 10a of the unit body 10. In the figure, a direction parallel to the thickness of the inductance component 1 is a Z direction, a positive Z direction is an upper side, and a negative Z direction is a lower side. In a plane orthogonal to the Z direction, a direction parallel to the length of the long side of the inductance component 1 is defined as an X direction, and a direction parallel to the width of the short side of the inductance component 1 is defined as a Y direction.

The unit cell 10 includes an insulating layer 61, a first magnetic layer 11 disposed on a lower surface 61a of the insulating layer 61, and a second magnetic layer 12 disposed on an upper surface 61b of the insulating layer 61. The first main surface 10a of the unit cell 10 corresponds to the upper surface of the second magnetic layer 12. The cell body 10 may have a 3-layer structure including the insulating layer 61, the first magnetic layer 11, and the second magnetic layer 12, or may have any one of a 1-layer structure including only magnetic layers, a 2-layer structure including only magnetic layers and insulating layers, and a 4-layer or more structure including a plurality of magnetic layers and insulating layers.

The insulating layer 61 has a layer shape having an insulating main surface in a long-sided shape, and the thickness of the insulating layer 61 is, for example, 10 μm to 100 μm. The insulating layer 61 is preferably an insulating resin layer containing no base material such as glass mesh, such as epoxy resin or polyimide resin, and may be a magnetic body such as a ferrite of NiZn series or MnZn series, a sintered body layer made of a nonmagnetic body such as alumina or glass, or may be a resin substrate layer containing a base material such as glass epoxy resin, from the viewpoint of height reduction. When the insulating layer 61 is a sintered body layer, the strength and flatness of the insulating layer 61 can be ensured, and the workability of the laminate on the insulating layer 61 can be improved. When the insulating layer 61 is a sintered body layer, polishing is preferably performed in view of reducing the height, and particularly, polishing is preferably performed from the lower side where there is no stacked object.

First magnetic layer 11 and second magnetic layer 12 have high magnetic permeability, have a long-edge-shaped main surface, and include resin 135 and metal magnetic powder 136 contained in resin 135. That is, the first magnetic layer 11 and the second magnetic layer 12 are made of a composite material of the resin 135 and the metal magnetic powder 136. The resin 135 is an organic insulating material made of, for example, epoxy resin, bismaleimide, liquid crystal polymer, polyimide, or the like. The metal magnetic powder 136 contains Fe, and is a metal material having magnetic properties, such as FeSi alloy such as fesicricrcr, FeCo alloy, Fe alloy such as NiFe, or amorphous alloy thereof. The average particle diameter of the metal magnetic powder 136 is, for example, 0.1 to 5 μm. In the process of manufacturing the inductance component 1, the average particle diameter of the metal magnetic powder 136 can be calculated as a particle diameter corresponding to 50% of the integrated value (so-called D50) in the particle size distribution obtained by the laser diffraction scattering method. The content of the metal magnetic powder 136 is preferably 20 Vol% to 70 Vol% of the entire magnetic layer. When the average particle diameter of the metal magnetic powder 136 is 5 μm or less, the dc superposition characteristics are further improved, and the iron loss at high frequencies can be reduced by the fine powder. Not only the metal magnetic powder but also a magnetic powder of a ferrite such as NiZn-based ferrite or MnZn-based ferrite may be used.

The first and second inductance elements 2A and 2B include first and second inductance lines 21 and 22 arranged in parallel with the first main surface 10a of the unit body 10. Thereby, the first inductance element 2A and the second inductance element 2B can be configured in the direction parallel to the first main surface 10a, and the inductance component 1 can be reduced in height. The first inductance wiring 21 and the second inductance wiring 22 are disposed on the same plane in the unit body 10. Specifically, the first inductance line 21 and the second inductance line 22 are formed only on the upper side of the insulating layer 61, that is, only on the upper surface 61b of the insulating layer 61, and are covered with the second magnetic layer 12.

The first inductance wiring 21 and the second inductance wiring 22 are wound in a planar shape. Specifically, the first inductance wiring 21 and the second inductance wiring 22 are arc-shaped like a half ellipse when viewed from the Z direction. That is, the first inductance line 21 and the second inductance line 22 are curved lines wound around about half a circumference. The first inductance wiring 21 and the second inductance wiring 22 may include straight portions in the middle. In the present application, the "spiral" of the inductance wiring is a curved shape formed by winding in a planar shape including a spiral shape, and includes a curved shape of 1 turn or less such as the first inductance wiring 21 and the second inductance wiring 22, and the curved shape may include a partial linear portion.

The thickness of the first inductance wiring 21 and the second inductance wiring 22 is preferably 40 μm to 120 μm, for example. As an example of the first inductance wiring 21 and the second inductance wiring 22, the thickness was 45 μm, the wiring width was 40 μm, and the inter-wiring gap was 10 μm. The gap between the wirings is preferably 3 μm to 20 μm from the viewpoint of ensuring insulation properties.

The first inductance wiring 21 and the second inductance wiring 22 are made of a conductive material, for example, a low-resistance metal material such as Cu, Ag, or Au. In the present embodiment, the inductance component 1 includes only 1 layer of the first inductance wiring 21 and the second inductance wiring 22, and the height of the inductance component 1 can be reduced. The first inductance wiring 21 and the second inductance wiring 22 may be metal films, and may be configured by forming conductive layers of Cu, Ag, or the like on an underlying layer of Cu, Ti, or the like formed by electroless plating, for example.

The first inductor wiring 21 is electrically connected to the first columnar wiring 31 and the second columnar wiring 32 having the first end and the second end located outside, respectively, and is curved in an arc shape from the first columnar wiring 31 and the second columnar wiring 32 toward the center of the inductor component 1. The first inductance wiring 21 has pad portions having a line width larger than that of the spiral portion at both ends thereof, and is directly connected to the first columnar wiring 31 and the second columnar wiring 32 at the pad portions.

Similarly, the second inductor wiring 22 is electrically connected to the third columnar wiring 33 and the fourth columnar wiring 34 having the first end and the second end located outside, respectively, and is curved from the third columnar wiring 33 and the fourth columnar wiring 34 toward the center of the inductor member 1.

Here, in each of the first inductance wiring 21 and the second inductance wiring 22, a range surrounded by a curve drawn by the first inductance wiring 21 and the second inductance wiring 22 and a straight line connecting both ends of the first inductance wiring 21 and the second inductance wiring 22 is defined as an inner diameter portion. At this time, the first inductance wiring 21 and the second inductance wiring 22 do not overlap each other in inner diameter portions thereof when viewed from the Z direction, and the first inductance wiring 21 and the second inductance wiring 22 are separated from each other.

The lines extend from the positions of connection of the first inductance line 21 and the second inductance line 22 to the first to fourth columnar lines 31 to 34 in the direction parallel to the X direction and outside the inductance component 1, and the lines are exposed outside the inductance component 1. That is, the first inductance wiring 21 and the second inductance wiring 22 have the exposed portions 200 exposed to the outside from the side surfaces (the surfaces parallel to the YZ plane) parallel to the stacking direction of the inductance components 1.

The first inductance line 21 and the second inductance line 22 are formed in the shape in the manufacturing process of the inductance component 1, and then connected to the power supply line when plating is additionally performed. With this feeding wiring, additional plating can be easily performed in the state of the inductor substrate before the inductor component 1 is singulated, and the distance between wirings can be narrowed. Further, by performing additional plating, the distance between the first inductance wiring 21 and the second inductance wiring 22 is narrowed, and the magnetic coupling between the first inductance wiring 21 and the second inductance wiring 22 can be improved, the wiring widths of the first inductance wiring 21 and the second inductance wiring 22 can be increased, and the resistance can be reduced, or the external shape of the inductance component 1 can be reduced.

Further, since the first inductance wiring 21 and the second inductance wiring 22 have the exposed portion 200, it is possible to secure electrostatic breakdown resistance during processing of the inductance substrate. In each of the inductance wirings 21 and 22, the thickness (dimension along the Z direction) of the exposed surface 200a of the exposed portion 200 is preferably 45 μm or more, and is not more than the thickness (dimension along the Z direction) of each of the inductance wirings 21 and 22. By setting the thickness of the exposed surface 200a to be equal to or less than the thickness of the inductance wirings 21, 22, the ratio of the magnetic layers 11, 12 can be increased, and the inductance can be improved. Further, by setting the thickness of the exposed surface 200a to 45 μm or more, the occurrence of disconnection near the exposed surface 200a can be reduced. The exposed surface 200a is preferably an oxide film. Accordingly, a short circuit can be suppressed between the inductance component 1 and its adjacent component.

The first to fourth columnar wirings 31 to 34 extend in the Z direction from the inductance wirings 21 and 22, respectively, and penetrate the inside of the second magnetic layer 12. The first columnar wiring 31 extends upward from the upper surface of one end of the first inductance wiring 21, and the end surface of the first columnar wiring 31 is exposed from the first main surface 10a of the unit body 10. The second columnar wiring 32 extends upward from the upper surface of the other end of the first inductance wiring 21, and the end surface of the second columnar wiring 32 is exposed from the first main surface 10a of the unit cell 10. The third columnar wiring 33 extends upward from the upper surface of one end of the second inductance wiring 22, and the end surface of the third columnar wiring 33 is exposed from the first main surface 10a of the unit cell 10. The fourth columnar wiring 34 extends upward from the upper surface of the other end of the second inductance wiring 22, and the end surface of the fourth columnar wiring 34 is exposed from the first main surface 10a of the unit cell 10.

Therefore, the first columnar wiring 31, the second columnar wiring 32, the third columnar wiring 33, and the fourth columnar wiring 34 linearly extend from the first inductance element 2A and the second inductance element 2B to the end surface exposed from the first main surface 10a in the direction orthogonal to the end surface. Thus, the first external terminal 41, the second external terminal 42, the third external terminal 43, and the fourth external terminal 44 can be connected to the first inductance element 2A and the second inductance element 2B at a shorter distance, and the inductance component 1 can be made low in resistance and high in inductance. The first to fourth columnar wirings 31 to 34 are made of a conductive material, and are made of the same material as the inductance wirings 21 and 22, for example.

The first to fourth external terminals 41 to 44 are disposed on the first main surface 10a of the unit cell 10. The first to fourth external terminals 41 to 44 are metal films disposed on the outer surface of the second magnetic layer 12 (composite). The first external terminal 41 is in contact with an end surface exposed from the first main surface 10a of the unit cell 10 of the first columnar wiring 31, and is electrically connected to the first columnar wiring 31. Thereby, the first external terminal 41 is electrically connected to one end of the first inductance wiring 21. The second external terminal 42 is in contact with an end surface exposed from the first main surface 10a of the unit cell 10 of the second columnar wiring 32, and is electrically connected to the second columnar wiring 32. Thus, the second external terminal 42 is electrically connected to the other end of the first inductance wiring 21.

Similarly, the third external terminal 43 is in contact with an end surface of the third columnar wiring 33, is electrically connected to the third columnar wiring 33, and is electrically connected to one end of the second inductance wiring 22. The fourth external terminal 44 is in contact with an end surface of the fourth columnar wiring 34, is electrically connected to the fourth columnar wiring 34, and is electrically connected to the other end of the second inductance wiring 22.

In the inductance component 1, the first main surface 10a has a first end edge 101 and a second end edge 102 extending linearly corresponding to the sides of the rectangular shape. The first and second end edges 101 and 102 are end edges of the first main surface 10a continuous with the first and second side surfaces 10b and 10c of the unit body 10, respectively. The first external terminal 41 and the third external terminal 43 are arranged along a first edge 101 on the first side surface 10b side of the unit body 10, and the second external terminal 42 and the fourth external terminal 44 are arranged along a second edge 102 on the second side surface 10c side of the unit body 10. The first side surface 10b and the second side surface 10c of the unit body 10 are surfaces along the Y direction, and coincide with the first end edge 101 and the second end edge 102, when viewed from the direction orthogonal to the first main surface 10a of the unit body 10. The arrangement direction of the first external terminal 41 and the third external terminal 43 is a direction connecting the center of the first external terminal 41 and the center of the third external terminal 43, and the arrangement direction of the second external terminal 42 and the fourth external terminal 44 is a direction connecting the center of the second external terminal 42 and the center of the fourth external terminal 44.

The insulating film 50 is provided on the first main surface 10a of the unit cell 10 at a portion where the first to fourth external terminals 41 to 44 are not provided. However, the insulating film 50 can overlap the first to fourth external terminals 41 to 44 in the Z direction by the riding of the end portions of the first to fourth external terminals 41 to 44. The insulating film 50 is made of a resin material having high electrical insulation, such as acrylic resin, epoxy resin, or polyimide. This can improve the insulation between the first to fourth external terminals 41 to 44. The insulating film 50 serves as a mask substitute film for patterning the first to fourth external terminals 41 to 44, thereby improving the manufacturing efficiency. When metal magnetic powder 136 is exposed from resin 135, insulating film 50 covers the exposed metal magnetic powder 136, thereby preventing metal magnetic powder 136 from being exposed to the outside. The insulating film 50 may contain a filler made of an insulating material such as silicon dioxide or barium sulfate.

As shown in fig. 2, first external terminal 41 is a multilayer metal film formed on second magnetic layer 12, having metal film 410 in contact with resin 135 and metal magnetic powder 136, and having 2 layers covering solder-attracting layer 411 on metal film 410. The second, third, and fourth external terminals 42, 44 have the same configuration as the first external terminal 41, and therefore only the first external terminal 41 will be described below.

The metal film 410 mainly contains Ni. Since metal magnetic powder 136 contains Fe and metal film 410 mainly contains Ni, the linear expansion coefficient of metal film 410 can be made close to that of metal magnetic powder 136, and the decrease in the adhesive force between metal magnetic powder 136 and metal film 410 under a thermal load can be suppressed. Specifically, the linear expansion coefficient of Fe is 11.7 [. times.10 ]^-6/K]And the linear expansion coefficient of Ni is 13.3 [. times.10 ]^-6/K]And the coefficient of linear expansion of Cu is 17.7 [. times.10 ]^-6/K]Therefore, the linear expansion coefficient of the metal film containing Ni is closer to that of the metal magnetic powder containing Fe than that of the metal film containing Cu. Further, since Fe of the metal magnetic powder 136 and Ni of the metal film 410 have similar ionization tendencies, a substitution reaction of Fe and Ni is not likely to occur, and a decrease in the adhesive force between the metal magnetic powder 136 and the metal film 410 due to the substitution reaction can be suppressed. Further, since the substitution reaction between Fe and Ni is less likely to occur, the reduction of the metal magnetic powder 136 can be suppressed, and the degradation of the characteristics such as the L value can be suppressed.

Therefore, the reliability of bonding between metal magnetic powder 136 and metal film 410 can be improved. In addition, the inductance component 1 in which the peeling of the external terminal is reduced can be provided.

In this way, in the present application, Fe of the metal magnetic powder and Ni of the metal film have similar ionization tendencies, and a substitution reaction between Fe and Ni is unlikely to occur. On the other hand, as shown in the prior art, when Fe is used as the metal magnetic powder and Cu is used as the metal film, the ionization tendency of Fe and Cu is further increased, and the substitution reaction of Fe and Cu proceeds. Therefore, the concept of the present application is completely different from the prior art. In the prior art, Cu of the metal film is formed by a substitution reaction with Fe of the metal magnetic powder, and therefore, the binding force between the metal magnetic powder and the metal film is small in the substitution reaction. Further, in the prior art, since Fe and Cu undergo a substitution reaction, the amount of metal magnetic powder is reduced, and the characteristics such as L value are sometimes lowered.

Preferably, the metal film 410 is formed by an electroless plating process. Accordingly, the shape of the external terminal can be freely formed as compared with the case where the metal film 410 is formed by the plating process.

Preferably, the metal film 410 is amorphous. Accordingly, the surface of the metal film 410 can be formed flat and the thickness of the metal film can be reduced as compared with the case where the metal film 410 has a crystal structure.

Preferably, the metal film 410 includes P. This improves the corrosion resistance of the metal film 410. Further, P is derived from sodium hypophosphite, which is a reducing agent used in forming the metal film 410 by electroless plating treatment as described later, and since Ni starts to be deposited without causing a substitution reaction with Fe by including P, the binding force between the metal magnetic powder and the metal film can be further improved.

Preferably, the P content relative to the metal film 410 is 1 wt% to 13 wt%. By setting the content of P in the metal film 410 to 1 wt% or more, the effect of improving the corrosion resistance and the adhesion of the metal film 410 can be reliably obtained. When the content of P in the metal film 410 is 13 wt% or less, the metal film 410 is favorably elongated during film formation, and the film formability of the metal film 410 is improved.

Therefore, when the metal film 410 is formed by electroless plating, for example, when the unit cell (composite) is immersed in a Ni plating solution using sodium hypophosphite as a reducing agent, electroless Ni plating as a metal film can be formed. Since sodium hypophosphite is active against Fe in the metal magnetic powder, Ni does not undergo a substitution reaction with Fe and begins to precipitate. That is, Ni is formed by autocatalytic reduction plating treatment. This improves the adhesion between Ni and Fe. At this time, P is co-precipitated in the metal film.

Preferably, the metal film (external terminal) contains Fe. This makes it possible to make the linear expansion coefficient of the metal film close to that of the metal magnetic powder, and further suppress a decrease in the adhesive force between the metal magnetic powder and the metal film under a thermal load. Therefore, when the metal film contains Fe, for example, Fe is contained in the plating solution to form the metal film by the plating treatment. Thus, the metal magnetic powder is less likely to dissolve in the plating liquid, and the reduction of the metal magnetic powder can be suppressed.

The hydrophilic solder layer 411 covers the metal film 410, constituting the outermost layer of the first external terminal 41. The solder attracting layer 411 contains a material having high wettability with solder such as Au or Sn. In the external terminal of the related art, the Cu layer and the Ag layer having high conductivity are formed in the lowermost layer, and the metal film such as the Ni layer and the solder-attracting layer such as Au and Sn are formed thereon in the 3-layer structure, but the first external terminal 41 has the 2-layer structure of the metal film 410 and the solder-attracting layer 411 as described above, and therefore, the external terminal can be made thin and have low resistance.

(production method)

Next, a method for manufacturing the inductance component 1 will be described.

As shown in fig. 3A, the upper surface of the unit cell 10 is ground by polishing or the like in a state where the unit cell 10 covers the plurality of inductance wirings 21 and 22 and the plurality of columnar wirings 31 to 34, so that the end surfaces of the columnar wirings 31 to 34 are exposed from the upper surface of the unit cell 10. Thereafter, as shown in fig. 3B, an insulating film 50 shown by hatching is formed on the entire upper surface of the unit cell 10 by a coating method such as spin coating or screen printing, a dry method such as dry film resist application, or the like. The insulating film 50 is, for example, a photosensitive resist.

Then, in the region where the external terminals are formed, the insulating film 50 is removed by photolithography, laser, drilling, sandblasting, or the like, and the through holes 50a, in which the end faces of the columnar wirings 31 to 34 and a part of the unit cell 10 (second magnetic layer 12) are exposed, are formed in the insulating film 50. At this time, as shown in fig. 3B, the entire end surfaces of the columnar wirings 31 to 34 may be exposed from the through-holes 50a, or a part of the end surfaces of the columnar wirings 31 to 34 may be exposed. Moreover, the end faces of the plurality of columnar wirings 31 to 34 may be exposed from 1 through hole 50 a.

Thereafter, as shown in fig. 3C, a metal film 410 is formed in the through-hole 50a by a method described later, and a solder attracting layer 411 shown by hatching is formed on the metal film 410, thereby forming the mother substrate 100. The metal film 410 and the solder-attracting layer 411 constitute external terminals 41 to 44 before cutting. Thereafter, as shown in fig. 3D, the plurality of inductance wirings 21, 22 sealed as the mother substrate 100 are singulated by the cutting line C from the 2 inductance wirings 21, 22 by using a dicing board or the like, and a plurality of inductance components 1 are manufactured. The metal film 410 and the solder-attracting layer 411 are cut along the cutting lines C to form the external terminals 41 to 44. The method for manufacturing the external terminals 41 to 44 may be a method for cutting the metal film 410 and the solder attracting layer 411 as described above, or a method for removing the insulating film 50 in advance so that the through holes 50a have the shape of the external terminals 41 to 44 and then forming the metal film 410 and the solder attracting layer 411.

(method for producing Metal film 410)

The method for manufacturing the metal film 410 will be described.

As described above, in the state where the through hole 50a is formed in the insulating film 50, the end faces of the columnar wirings 31 to 34 and the unit cell 10 are exposed from the through hole 50 a. An Ni layer is formed as a conductive metal film 410 in contact with the cell body 10 by electroless plating treatment on the end surfaces of the columnar wirings 31 to 34 exposed from the through holes 50a and the upper surface of the cell body 10.

Specifically, the metal film 410 mainly containing Ni is deposited on the metal magnetic powder 136 containing Fe by the autocatalytic reduction plating treatment. For example, the unit cell 10 is immersed in a Ni plating solution using a reducing agent such as sodium hypophosphite, and an electroless Ni plating metal film 410 is formed on the second magnetic layer 12 (composite). The metal film 410 is in contact with the resin 135 and the metal magnetic powder 136 of the second magnetic layer 12.

In order to form the metal film 410 on the columnar wirings (Cu)31 to 34, for example, the metal film 410 deposited on the metal magnetic powder 136 may be grown to extend on the columnar wirings 31 to 34. Alternatively, a Pd layer may be formed as a catalyst layer on the columnar wirings 31 to 34, and the metal film 410 may be formed on the catalyst layer by electroless plating.

The present disclosure is not limited to the above embodiments, and design changes can be made without departing from the scope of the present disclosure.

In the above embodiment, 2 of the first inductance element and the second inductance element are arranged in the unit body, but 3 or more inductance elements may be arranged, and in this case, 6 or more external terminals and column-shaped wirings are provided.

In the above embodiment, the inductance element has the inductance wiring with the number of turns smaller than 1 cycle, but the number of turns of the inductance wiring may be a curve exceeding 1 cycle. The number of inductance wiring layers included in the inductance element is not limited to 1, and may be a multilayer structure having 2 or more layers. The first inductance wiring of the first inductance element and the second inductance wiring of the second inductance element are not limited to being arranged on the same plane parallel to the first main surface, and may be arranged in a direction orthogonal to the first main surface.

The "inductance wiring" is a member that gives inductance to an inductance member by generating magnetic flux in a magnetic layer when current flows, and the structure, shape, material, and the like of the member are not particularly limited. For example, various known wiring shapes such as a hockey (media) wiring can be used.

In the above embodiments, although the metal film is applied as the external terminal of the inductance component, it is not limited thereto, and for example, the metal film may be an internal electrode of the inductance component. The metal film is not limited to the inductance component, and may be applied to other electronic components such as a capacitance component and a resistance component, and may be applied to a circuit board on which these electronic components are mounted. For example, the metal film may be a wiring pattern of a circuit board.

In the above embodiment, the metal film is used for the external terminal, but the metal film can be applied to an inductance wiring. That is, the composite may be used as a substitute for a substrate, and the inductance wiring may be formed on the composite by electroless plating as a metal film. This makes it possible to obtain a metal film having the above-described effects as an inductance wiring, and to form the metal film as described above.