JP2023103954A - Coil component - Google Patents

Abstract

To provide a coil component capable of improving close contact between a magnetic body and an external electrode while maintaining direct-current resistance to be low.SOLUTION: A coil component 1 includes: a magnetic body 10 containing a metal magnetic particle 50; a coil 20 embedded inside the magnetic body 10; an external electrode 30 on at least a bottom surface (e.g., first main surface 11) of the magnetic body 10 and electrically connected to the coil 20. The external electrode (e.g., first external electrode 31) includes, in order from a side of the magnetic body 10, an underlayer 31a containing Ag, and a plating layer 31b. An oxide film 61 containing a metal element contained in a metal magnetic particle 51 is between the metal magnetic particle 51 and the underlayer 31a at an interface between the magnetic body 10 and the underlayer 31a. In the inside of the magnetic body 10, an oxide film 62 having a thickness smaller than a thickness of the oxide film 61 between the metal magnetic particle 51 and the underlayer 31a is at a surface of a metal magnetic particle 52 adjacent to the metal magnetic particle 51 positioned at the interface.SELECTED DRAWING: Figure 5

Description

The present invention relates to coil components.

Patent Document 1 discloses a passive component that is a surface-mount component, and includes a base portion having an insulating property, an internal conductor embedded in the base portion, and a mounting surface of the base portion provided on the inner conductor. and an external electrode electrically connected to the mounting surface of the base portion, wherein the external electrode is arranged on a surface substantially parallel to the mounting surface of the base portion and on the mounting surface of the base portion with reference to the substantially parallel surface. A passive component is disclosed having a dome-shaped protrusion raised on the opposite side.

Patent Document 2 discloses a method comprising a substrate and an electrode including a baked electrode provided on the surface of the substrate and formed by baking an electrode paste containing a predetermined electrode material. An electronic component is disclosed in which a glass component resulting from the glass frit contained in the electrode paste is diffused from the contact interface toward the inside of the base by approximately 10 μm or more.

JP 2019-176109 A Japanese Unexamined Patent Application Publication No. 2013-84701

Patent Literature 1 describes a coil component as an example of a passive component. Furthermore, in Patent Document 1, the base portion is, for example, a ferrite material such as Ni-Zn-based or Mn-Zn-based, Fe-Si-Cr-based, Fe-Si-Al-based, or Fe-Si-Cr-Al-based A soft magnetic alloy material such as Fe or Ni, a magnetic metal material such as Fe or Ni, an amorphous magnetic metal material, a nanocrystalline magnetic metal material, or a magnetic material such as a resin containing metal magnetic particles, and the external electrode is , for example consisting of a plurality of metal layers.

In the coil component described in Patent Literature 1, there is a possibility that the base portion and the external electrode cannot be sufficiently adhered to each other.

On the other hand, Patent Document 2 describes a technique for improving the adhesiveness (fixing strength) between the substrate and the electrode by diffusing the glass component contained in the electrode paste into the interior of the substrate by a baking process. .

However, when the electrode paste contains a glass component, the conductor resistance increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a coil component capable of improving adhesion between a magnetic body portion and an external electrode while maintaining a low DC resistance.

A coil component according to the present invention includes a magnetic body portion containing metal magnetic particles, a coil embedded inside the magnetic body portion, and a magnetic body portion provided on at least a bottom surface of the magnetic body portion and electrically connected to the coil. and external electrodes. The external electrode includes, in order from the magnetic body portion side, an underlying layer containing Ag and a plating layer. At the interface between the magnetic portion and the underlayer, an oxide film containing the metal element contained in the metal magnetic particles is present between the metal magnetic particles and the underlayer. Inside the magnetic body portion, the surface of the metal magnetic particle adjacent to the metal magnetic particle located at the interface has a thickness smaller than that of the oxide film existing between the metal magnetic particle and the underlayer. An oxide film is present.

ADVANTAGE OF THE INVENTION According to this invention, the coil component which can improve the adhesiveness of a magnetic body part and an external electrode can be provided, maintaining low DC resistance.

FIG. 1 is a perspective view schematically showing an example of the coil component of the present invention. 2 is a perspective view schematically showing an example of the internal structure of the coil component shown in FIG. 1. FIG. 3 is a cross-sectional view of the coil component shown in FIG. 2 along line III-III. 4 is a cross-sectional view of the coil component shown in FIG. 2 taken along line IV-IV. FIG. 5 is an enlarged schematic diagram of the portion indicated by V in FIG. FIG. 6A is a mapping image of Fe element in the portion shown in FIG. FIG. 6B is a mapping image of O element in the portion shown in FIG. FIG. 6C is a mapping image of Ag element in the portion shown in FIG. FIG. 7 is an enlarged schematic diagram of the portion indicated by VII in FIG. FIG. 8A is a plan view schematically showing an example of a method of forming a magnetic paste layer; FIG. 8B is a plan view schematically showing an example of a method of forming a conductive paste layer on a magnetic paste layer; 8C is a plan view schematically showing an example of a method of forming an insulating paste layer and via conductors on a conductive paste layer; FIG. FIG. 8D is a plan view schematically showing an example of a method of forming a conductive paste layer on the magnetic paste layer and the insulating paste layer; FIG. 8E is a plan view schematically showing an example of a method of forming via conductors on a conductive paste layer; FIG. 8F is a plan view schematically showing an example of a method of forming a conductive paste layer that serves as a base layer for external electrodes.

The coil component of the present invention will be described below.
However, the present invention is not limited to the following embodiments, and can be appropriately modified and applied without changing the gist of the present invention. It should be noted that a combination of two or more of the individual preferred configurations of the invention described below is also the invention.

In this specification, terms indicating the relationship between elements (e.g., "parallel", "perpendicular", "perpendicular", etc.) and terms indicating the shape of elements are not expressions that express only strict meanings, but substantially It is an expression that means to include a difference in an equivalent range, for example, a few percent difference.

The drawings shown below are schematic diagrams, and their dimensions, aspect ratios, etc. may differ from actual products.

FIG. 1 is a perspective view schematically showing an example of the coil component of the present invention. 2 is a perspective view schematically showing an example of the internal structure of the coil component shown in FIG. 1. FIG. The shape, arrangement, etc. of the coil component and each component are not limited to the illustrated example.

A coil component 1 shown in FIGS. 1 and 2 includes a magnetic body portion 10 , a coil 20 and an external electrode 30 . As shown in FIG. 2 , the coil component 1 may further include lead conductors 40 .

The magnetic body part 10 has, for example, a rectangular parallelepiped shape or a substantially rectangular parallelepiped shape having six faces. The magnetic body portion 10 may have rounded corners and ridges. The corner portion is a portion where three surfaces of the magnetic body portion 10 intersect, and the ridge portion is a portion where two surfaces of the magnetic body portion 10 intersect.

In FIGS. 1 and 2, the length direction, width direction, and height direction of the coil component 1 and the magnetic body portion 10 are shown as L direction, W direction, and T direction, respectively. The length direction L, width direction W and height direction T are orthogonal to each other. The mounting surface of the coil component 1 is, for example, a surface parallel to the length direction L and the width direction W (LW surface).

The magnetic body portion 10 shown in FIGS. 1 and 2 has a first main surface 11 and a second main surface 12 facing in the height direction T, and a first main surface 11 and a second main surface 12 facing in the length direction L orthogonal to the height direction T. It has one end face 13 and a second end face 14, and a first side face 15 and a second side face 16 facing each other in a width direction W orthogonal to the length direction L and the height direction T. In the example shown in FIGS. 1 and 2 , the first main surface 11 of the magnetic body portion 10 corresponds to the bottom surface of the magnetic body portion 10 .

3 is a cross-sectional view of the coil component shown in FIG. 2 along line III-III. 4 is a cross-sectional view of the coil component shown in FIG. 2 taken along line IV-IV. FIG. 5 is an enlarged schematic diagram of the portion indicated by V in FIG.

As shown in FIGS. 3 and 4, the magnetic section 10 preferably has a laminated structure. In the examples shown in FIGS. 3 and 4, the stacking direction of the magnetic body part 10 is along the height direction T. In the example shown in FIGS. 3 and 4 show the boundaries between the layers of the laminated structure of the magnetic body portion 10 for convenience of explanation, but the boundaries do not appear clearly in practice.

When the magnetic body part 10 has a laminated structure, the degree of freedom in designing the coil component 1 is increased. For example, when manufacturing the coil component 1 having the external electrodes 30 on the bottom surface (first main surface 11) of the magnetic body part 10, if the magnetic body part 10 has a laminated structure, the coil 20 cannot be pulled out to the bottom side. easier to go.

As shown in FIG. 5 , the magnetic body portion 10 contains metal magnetic particles 50 .

Examples of the metal magnetic material forming the metal magnetic particles 50 include alloys containing Fe and Si, such as Fe--Si alloys and Fe--Si--Cr alloys. These alloys may contain elements such as Cr, Mn, Cu, Ni, P, and S as impurities.

The average particle diameter of the metal magnetic particles 50 is not particularly limited, but is preferably 1 μm or more and 50 μm or less, more preferably 2 μm or more and 20 μm or less.

The average particle size of the metal magnetic particles 50 can be measured by the method described below. First, the coil component 1 is cut to form a cross section. For example, when the coil component 1 includes the external electrodes 30 on the bottom surface (first principal surface 11) of the magnetic body portion 10, the coil component 1 is cut in the height direction T perpendicular to the bottom surface so that the bottom surface form a cross section perpendicular to This section is processed by ion milling. A cross section after processing is observed with a scanning electron microscope (SEM). It is preferable to set the magnifying power of the SEM to approximately 500 times or more and 5000 times or less. The particle size (equivalent circle diameter) of the metal magnetic particles 50 is measured from the obtained SEM image, and the average value of 100 or more metal magnetic particles 50 can be taken as the average particle size of the metal magnetic particles 50 .

Moreover, the average particle size of the metal magnetic particles 50 contained in the finished coil component 1 can be considered to be substantially the same as the average particle size of the raw material metal magnetic powder. The average particle diameter of the raw material metal magnetic powder can be obtained by measuring the volume-based cumulative 50% particle diameter (median diameter) D50 by a laser diffraction/scattering method.

An insulating coating is provided on the surface of the metal magnetic particles 50 . In this case, since the insulation of the magnetic body portion 10 is improved, the voltage resistance of the coil component 1 can be further improved. The insulating film is an oxide film containing a metal oxide, and preferably further contains an oxide film containing an oxide of Si.

The magnetic body portion 10 may further contain components other than the metal magnetic particles 50 . For example, the magnetic body portion 10 may contain at least one element such as Cr, Al, Li, and Zn as an element that is more easily oxidized than Fe.

The magnetic body part 10 may further contain resin. When the magnetic body portion 10 contains a resin, the type of resin is not particularly limited and can be appropriately selected according to desired properties. The magnetic body part 10 is made of, for example, one or more selected from the group consisting of epoxy resin, phenol resin, polyester resin, polyimide resin, polyolefin resin, silicone resin, acrylic resin, polyvinyl butyral resin, cellulose resin, alkyd resin, and the like. It may contain a resin.

The coil 20 is embedded inside the magnetic body portion 10 . The coil 20 may include a plurality of coil conductor layers stacked in the winding axis direction, as shown in FIGS. In the examples shown in FIGS. 2, 3 and 4, the winding axis direction of the coil 20 is along the height direction T. As shown in FIG. Although not shown, adjacent coil conductor layers are connected to each other through via conductors.

The external electrode 30 is provided on at least the bottom surface (first principal surface 11 ) of the magnetic body portion 10 and electrically connected to the coil 20 . In the coil component 1, the bottom surface (first main surface 11) of the magnetic body portion 10 can be used as the mounting surface. That is, mounting on the bottom surface of the coil component 1 becomes possible.

The external electrode 30 includes, for example, a first external electrode 31 and a second external electrode 32 .

The first external electrode 31 is arranged to cover part of the first main surface 11 of the magnetic body portion 10 . Although not shown in FIG. 1 and the like, the first external electrode 31 extends from the first main surface 11 of the magnetic body portion 10 to a portion of the first end surface 13 and a portion of the first side surface 15 . or over a portion of the second side 16 .

The second external electrode 32 is arranged to cover part of the first main surface 11 of the magnetic body portion 10 . Although not shown in FIG. 1 and the like, the second external electrode 32 extends from the first main surface 11 of the magnetic body portion 10 to a portion of the second end surface 14 and a portion of the first side surface 15 . or over a portion of the second side 16 .

The external electrode 30 includes an underlying layer and a plating layer in order from the magnetic body portion 10 side. In the example shown in FIGS. 3 and 4, the first external electrode 31 includes an underlying layer 31a and a plating layer 31b in order from the magnetic body portion 10 side, and the second external electrode 32 includes the magnetic body portion 10 It includes an underlying layer 32a and a plating layer 32b in order from the side.

The base layer of the external electrode 30 is a base electrode containing Ag.

The underlying layer of the external electrodes 30 preferably does not contain a glass component. For example, an increase in conductor resistance can be suppressed by forming the underlying layer using Ag paste that does not contain glass frit.

In addition, "not containing a glass component" means that the content of the glass component is below the detection limit. The presence or absence of the glass component contained in the underlayer is determined, for example, by mapping elemental analysis by energy dispersive X-ray analysis (EDX), and whether or not an element (for example, silicon (Si)) constituting the glass is detected. confirmed by

The plating layer of the external electrode 30 is provided so as to cover the base layer. The plating layer may be one layer, or two or more layers. In the example shown in FIG. 5, the plated layer 31b of the first external electrode 31 includes a first plated layer _31b1 and a second plated layer _31b2 in order from the base layer 31a side. The plating layer 32b of the second external electrode 32 is also the same.

As shown in FIGS. 2 and 3 , both ends of the coil 20 are preferably drawn out to the bottom surface (first main surface 11 ) of the magnetic body portion 10 . Specifically, the coil 20 is preferably electrically connected to the external electrode 30 via the lead conductor 40 on the bottom surface (first main surface 11 ) of the magnetic body portion 10 .

One end of the lead conductor 40 is connected to the coil 20 inside the magnetic body portion 10 . The other end of the lead conductor 40 is connected to the external electrode 30 on the bottom surface (first main surface 11 ) of the magnetic body portion 10 .

The lead conductor 40 includes, for example, a first lead conductor 41 and a second lead conductor 42 .

One end of the first lead conductor 41 is connected to the starting end of the coil 20 . The other end of the first lead conductor 41 is connected to the first external electrode 31 . 2 and 3, the direction extending from one end of the first lead conductor 41 to the other end is along the height direction T. In the example shown in FIGS.

As shown in FIG. 3, the first lead conductor 41 may have a laminated structure. In the example shown in FIG. 3, the stacking direction of the first lead-out conductors 41 is along the height direction T. As shown in FIG. In FIG. 3, for convenience of explanation, the boundaries between the layers of the laminated structure of the first lead conductor 41 are shown, but the boundaries do not appear clearly in practice.

One end of the second lead conductor 42 is connected to the terminal end of the coil 20 . The other end of the second lead conductor 42 is connected to the second external electrode 32 . In the example shown in FIGS. 2 and 3, the direction extending from one end of the second lead conductor 42 to the other end is along the height direction T. As shown in FIG.

Although not shown, the second lead conductor 42 may have a laminated structure.

As shown in FIG. 5, among the metal magnetic particles 50 contained in the magnetic body portion 10, when focusing on the metal magnetic particles 51 located at the interface between the magnetic body portion 10 and the underlayer 31a, the magnetic body portion 10 and At the interface with the underlayer 31a, an oxide film 61 exists between the metal magnetic particles 51 and the underlayer 31a. The oxide film 61 may exist over the entire interface between the magnetic body portion 10 and the underlying layer 31a, or may exist partially.

Although not shown, among the metal magnetic particles 50 contained in the magnetic body portion 10, when focusing on the metal magnetic particles 51 located at the interface between the magnetic body portion 10 and the underlayer 32a, the magnetic body portion 10 and the lower layer 32a are observed. An oxide film 61 is preferably present between the metal magnetic particles 51 and the underlying layer 32a at the interface with the underlying layer 32a. In that case, the oxide film 61 may exist on the entire interface between the magnetic body portion 10 and the underlying layer 32a, or may exist on a part thereof.

Note that the oxide film 61 may exist only at either one of the interface between the magnetic body portion 10 and the underlayer 31a and the interface between the magnetic body portion 10 and the underlayer 32a. An oxide film 61 may be present in the .

Oxide film 61 contains the metal element contained in metal magnetic particles 51 . For example, when the metal magnetic particles 51 contain Fe and Si, the oxide film 61 may be an oxide film containing an oxide of Fe, an oxide film containing an oxide of Si, or an oxide film containing an oxide of Fe and Si. A contained oxide film may also be used. The composition of the oxide film 61 may not be uniform. May be mixed.

FIG. 6A is a mapping image of Fe element in the portion shown in FIG. FIG. 6B is a mapping image of O element in the portion shown in FIG. FIG. 6C is a mapping image of Ag element in the portion shown in FIG.

6A, 6B, and 6C are mapping images of elements obtained by SEM-EDX measurement. 6A, 6B, and 6C, it can be confirmed that an oxide film 61 exists between the metal magnetic particles 51 and the underlayer 31a at the interface between the magnetic body portion 10 and the underlayer 31a.

The thickness of oxide film 61 is not particularly limited, and is, for example, 50 nm or more. The thickness of oxide film 61 is preferably 75 nm or more, more preferably 100 nm or more, still more preferably 200 nm or more, and particularly preferably 1 μm or more. On the other hand, the thickness of the oxide film 61 is, for example, 2 μm or less. The thickness of oxide film 61 may or may not be constant. If the thickness of the oxide film 61 is not constant, there may be a portion where the thickness of the oxide film 61 is 50 nm or more, for example.

In the coil component 1 , the oxide film 61 containing the metal element contained in the metal magnetic particles 51 is interposed at the interface between the magnetic portion 10 and the underlying layer of the external electrode 30 , so that the magnetic portion 10 and the external electrode 30 are separated from each other. The adhesion strength with the electrode 30 is increased.

As described above, in the coil component 1, the oxide film 61 can improve the adhesion between the magnetic body portion 10 and the external electrode 30. Therefore, unlike the technique described in Patent Document 2, an underlayer that does not contain a glass component is formed. be able to. Therefore, an increase in conductor resistance can be suppressed. As described above, the adhesion between the magnetic body portion 10 and the external electrode 30 can be improved while keeping the DC resistance low.

For example, when the metal magnetic particles 51 contain Fe and Si, the Fe contained in the metal magnetic particles 51 has a higher ionization tendency than the Ag contained in the underlying layer of the external electrode 30 and is easily oxidized. On the other hand, since Ag is easily reduced, a thick oxide film 61 is formed on the surface of the metal magnetic particles 51 near the underlying layer of the external electrode 30 .

Therefore, as shown in FIG. 5, the oxide film 61 existing between the metal magnetic particles 51 and the underlayer 31a is the underlayer of the metal magnetic particles 51 located at the interface between the magnetic body portion 10 and the underlayer 31a. It is preferable to exist on the surface on the side of 31a. Similarly, the oxide film 61 existing between the metal magnetic particles 51 and the underlayer 32a exists on the underlayer 32a side surface of the metal magnetic particles 51 located at the interface between the magnetic body portion 10 and the underlayer 32a. preferably.

The thickness of oxide film 61 can be measured by the method described below. First, the coil component 1 is cut to form a cross section, and processed by ion milling. A cross section after processing is observed with a scanning transmission electron microscope (STEM). Mapping elemental analysis is performed by energy dispersive X-ray spectroscopy (EDX), and the thickness of the oxide film 61 is defined as the range in which oxygen (O) is detected. It is preferable to set the enlargement magnification to approximately 10,000 times or more and 500,000 times or less. The same applies to the method of measuring the thickness of oxide films 62 and 63, which will be described later.

The oxide film 61 may further contain elements other than the metal elements contained in the metal magnetic particles 51 . For example, the oxide film 61 may contain at least one element such as Cr, Al, Li, and Zn.

For example, when the oxide film 61 present between the metal magnetic particles 51 and the underlying layer 31a contains Zn, the Zn contained in the oxide film 61 is preferably unevenly distributed on the underlying layer 31a side. Similarly, when the oxide film 61 present between the metal magnetic particles 51 and the underlayer 32a contains Zn, the Zn contained in the oxide film 61 is preferably unevenly distributed on the underlayer 32a side. When Zn is unevenly distributed on the underlayer 31a side or the underlayer 32a side, the insulation between the metal magnetic particles 51 and the underlayer 31a or the underlayer 32a is improved, so that the voltage resistance of the coil component 1 is further improved. can improve.

The fact that the Zn contained in the oxide film 61 is unevenly distributed on the underlayer 31a side or the underlayer 32a side is confirmed by performing the above-described EDX mapping elemental analysis. The range in which zinc (Zn) is detected between is confirmed. In the present disclosure, "the Zn contained in the oxide film 61 is unevenly distributed on the underlayer 31a side or the underlayer 32a side" means that, as a result of the above-described mapping elemental analysis, the maximum peak of Zn is the metal magnetic particle 51. It refers to being positioned closer to the underlayer 31a or underlayer 32a than the center of the underlayer 31a or the center between the metal magnetic particles 51 and the underlayer 32a.

As shown in FIG. 5, a portion of the underlayer 31a may enter between adjacent metal magnetic particles 51 at the interface between the magnetic body portion 10 and the underlayer 31a. Similarly, part of the underlayer 32a may enter between adjacent metal magnetic particles 51 at the interface between the magnetic body portion 10 and the underlayer 32a. In that case, the adhesion strength between the magnetic body portion 10 and the external electrode 30 increases due to the anchor effect.

As shown in FIG. 5 , among the metal magnetic particles 50 contained in the magnetic body portion 10 , in the interior of the magnetic body portion 10 , metal magnetic particles located at the interface between the magnetic body portion 10 and the underlayer 31 a or the underlayer 32 a are present. An oxide film 62 is preferably present on the surface of the metal magnetic particle 52 adjacent to the particle 51 .

The thickness of the oxide film 62 is smaller than the thickness of the oxide film 61 existing between the metal magnetic particles 51 and the underlayer 31a or underlayer 32a. As a result, it is possible to achieve both improvement in adhesion strength and suppression of characteristic deterioration due to oxidation. The metal magnetic particles 50 originally have an oxide film of a metal element derived from the metal magnetic particles 50 on their surfaces. By degreasing and baking this, the thickness of the oxide film varies depending on the position where the metal magnetic particles 50 are present.

The oxide film 62 contains, for example, the metal element contained in the metal magnetic particles 52 . The composition of oxide film 62 may be the same as or different from that of oxide film 61 .

FIG. 7 is an enlarged schematic diagram of the portion indicated by VII in FIG.

As shown in FIG. 7, among the metal magnetic particles 50 contained in the magnetic body portion 10, when focusing on the metal magnetic particles 53 located at the interface between the magnetic body portion 10 and the coil 20, the magnetic body portion 10 and the coil An oxide film 63 may exist between the metal magnetic particles 53 and the coil 20 at the interface with 20 . The oxide film 63 present between the metal magnetic particles 53 and the coil 20 is preferably present on the coil 20 side surface of the metal magnetic particles 53 positioned at the interface between the magnetic body portion 10 and the coil 20 .

The thickness of the oxide film 63 is smaller than that of the oxide film 61 existing between the metal magnetic particles 51 and the underlying layer 31a or underlying layer 32a. As a result, it is possible to achieve both improvement in adhesion strength and suppression of characteristic deterioration due to oxidation.

The oxide film 63 contains, for example, the metal element contained in the metal magnetic particles 53 . The composition of oxide film 63 may be the same as or different from that of oxide film 61 . Also, the composition of the oxide film 63 may be the same as or different from the composition of the oxide film 62 .

The coil component 1 may further include an insulating layer 70 as shown in FIGS.

In the examples shown in FIGS. 2 and 3 , an insulating layer 70 is provided between a plurality of coil conductor layers forming the coil 20 . By arranging the insulating layer 70 between the coil conductor layers, it is possible to prevent a short circuit from occurring between the coil conductor layers, thereby improving the reliability of the coil component 1 .

In the example shown in FIGS. 2 and 3, the insulating layer 70 is arranged only at a position where it overlaps with the coil conductor layer when viewed from the height direction T. As shown in FIG. The arrangement of the insulating layer 70 is not particularly limited, and the insulating layer 70 may be provided at a position not overlapping the coil conductor layer when viewed from the height direction T. From the viewpoint of preventing short circuits, it is preferable that the insulating layers 70 are arranged between adjacent coil conductor layers, as shown in FIGS.

The material forming the insulating layer 70 is not particularly limited as long as it has a higher insulating property than the magnetic body portion 10, and examples thereof include non-magnetic materials, ferrite materials, metal magnetic materials, and the like.

A coil component of the present invention is manufactured, for example, by the following method.

An example of a method of manufacturing the coil component 1 using the printing lamination method will be described below. The coil component of the present invention may be produced using a printing lamination method or may be produced using a sheet lamination method.

First, a magnetic paste is prepared.

For example, a metal magnetic powder such as an Fe—Si alloy or Fe—Si—Cr alloy having a volume-based cumulative 50% particle diameter D50 of 2 μm or more and 20 μm or less (preferably about 10 μm) is prepared. A binder such as cellulose or polyvinyl butyral (PVB) and a solvent such as terpineol or butyl diglycol acetate (BCA) are added to the metal magnetic powder and kneaded to form a magnetic paste containing the metal magnetic particles. make. As a component other than the metal magnetic powder, oxide powder such as Cr, Al, Li, and Zn may be added and kneaded.

When an Fe—Si alloy is used as the metal magnetic powder, the Si content is preferably 2.0 at % or more and 8.0 at % or less. When an Fe--Si--Cr alloy is used as the metal magnetic powder, the Si content is preferably 2.0 at % or more and 8.0 at % or less, and the Cr content is 0.2 at % or more and 6.0 at %. % or less.

An insulating coating is provided on the surface of the metal magnetic powder. The insulating film is an oxide film containing a metal oxide, and preferably further contains an oxide film containing an oxide of Si. Methods for forming an oxide film containing an oxide of Si include, for example, a mechanochemical method and a sol-gel method. Among them, the sol-gel method is preferred. When forming an oxide film containing an oxide of Si by the sol-gel method, for example, a sol-gel coating agent containing a Si alkoxide and a silane coupling agent containing an organic chain are mixed, and the mixture is adhered to the surface of the metal magnetic powder. can be formed by drying at a predetermined temperature after dehydration bonding by heat treatment.

Separately, a conductive paste containing Ag is prepared. The conductive paste preferably does not contain glass frit.

When forming the insulating layer 70, an insulating paste containing an insulating material is also prepared.

A laminate block is produced using the above magnetic paste, conductive paste, and insulating paste.

FIG. 8A is a plan view schematically showing an example of a method of forming a magnetic paste layer;

Although not shown, first, a substrate is prepared by stacking a thermal release sheet and a PET (polyethylene terephthalate) film on a metal plate. A magnetic paste layer 110 is formed by screen-printing a magnetic paste on the substrate a predetermined number of times. This becomes the outer layer of the coil component.

FIG. 8B is a plan view schematically showing an example of a method of forming a conductive paste layer on a magnetic paste layer;

A conductive paste is printed on the magnetic paste layer 110 to form a conductive paste layer 120 that will become the coil conductor layer of the coil 20 . Furthermore, the magnetic paste layer 110 is formed in the area where the conductive paste layer 120 is not formed. Note that the magnetic paste layer 110 and the conductive paste layer 120 may be formed so as to partially overlap at the boundary.

8C is a plan view schematically showing an example of a method of forming an insulating paste layer and via conductors on a conductive paste layer; FIG.

An insulating paste is printed on a predetermined area on the conductive paste layer 120 to form an insulating paste layer 170 . Further, a magnetic paste is printed on regions other than the regions that will become via conductors, which will be described later, and regions other than the regions where the insulating paste layers 170 are formed, thereby forming the magnetic paste layers 110 . Also, via conductors 145 and via conductors 141 for drawing out to the bottom surface are formed on the conductive paste layer 120 in a region to be connected to a coil conductor layer to be printed in the next step. Insulating paste layer 170, via conductors 141, via conductors 145, and magnetic paste layer 110 may be formed so as to partially overlap at the boundaries.

FIG. 8D is a plan view schematically showing an example of a method of forming a conductive paste layer on the magnetic paste layer and the insulating paste layer;

A conductive paste is printed on the magnetic paste layer 110 and the insulating paste layer 170 to form the conductive paste layer 120 that will become the coil conductor layer. Furthermore, a conductive paste is further printed on the via conductors 141 for drawing out to the bottom surface. The conductive paste for forming conductive paste layer 120 and the conductive paste on via conductors 141 are printed at the same time.

The steps described with reference to FIGS. 8C and 8D are repeated a predetermined number of times.

FIG. 8E is a plan view schematically showing an example of a method of forming via conductors on a conductive paste layer;

A conductive paste is printed on the conductive paste layer 120 to form via conductors 141 and 142 for drawing out to the bottom surface. Furthermore, a magnetic paste is printed on the regions where the via conductors 141 and 142 are not formed to form the magnetic paste layer 110 .

The process described in FIG. 8E is repeated a predetermined number of times.

FIG. 8F is a plan view schematically showing an example of a method of forming a conductive paste layer that serves as a base layer for external electrodes.

Finally, a conductive paste layer that serves as a base layer for the external electrodes 30 is formed. Specifically, a conductive paste layer 131a that serves as the base layer 31a of the first external electrode 31 and a conductive paste layer 132a that serves as the base layer 32a of the second external electrode 32 are formed. Furthermore, the magnetic paste layer 110 is formed in the regions where the conductive paste layers 131a and 132a are not formed.

A laminate block is obtained by compressing the laminate produced by the above procedure.

Elements are obtained by cutting the laminate block with a dicer or the like to individualize it. You may separate into pieces after baking.

After degreasing the singulated elements, they are placed in a firing furnace and fired in the atmosphere at 600° C. or higher and 800° C. or lower for 30 minutes or longer and 90 minutes or shorter. At this time, an oxide film is formed on the surface of the metal magnetic powder contained in the magnetic paste.

If necessary, it is impregnated with a resin such as an epoxy resin and heat-cured. By impregnating the resin, the gaps between the metal magnetic particles are filled with the resin, so that the strength of the magnetic body portion 10 can be ensured and the infiltration of the plating solution or moisture can be suppressed.

A plated layer is formed on the underlying layer by electroplating. As the plating layer, for example, a Cu film may be formed, a Ni film and a Sn film may be formed in this order, or a Ni film and a Cu film may be formed in this order. Thereby, the external electrodes 30 are formed.

As described above, the coil component 1 as shown in FIG. 1 can be manufactured. The size of the coil component 1 is, for example, 1.6 mm in the length direction L, 0.8 mm in the width direction W, and 0.4 mm or more and 1.0 mm or less (for example, 0.4 mm) in the height direction T. 64 mm), and the thickness of the coil conductor layer of the coil 20 is 20 μm or more and 90 μm or less.

Although the same conductive paste is used to form the coil 20 and the external electrodes 30 in the above example, the coil 20 and the external electrodes 30 may be formed using different conductive pastes. By properly using the conductive paste, the oxide film 61 formed near the external electrode 30 can be made thicker than the oxide film 63 formed near the coil 20 .

For example, by forming the base layer of the external electrodes 30 using a conductive paste containing Ag particles that are easily sintered, a thick oxide film 61 is formed in the vicinity of the external electrodes 30, so that the bonding strength can be improved. can. On the other hand, by forming the coil conductor layer of the coil 20 using a conductive paste containing Ag particles that are difficult to sinter, a thin oxide film 63 is formed in the vicinity of the coil 20, so deterioration of characteristics due to oxidation can be suppressed. can be done.

As Ag particles that are easily sintered, for example, Ag particles having a small particle size, Ag particles produced by a wet reduction method, or the like can be used. On the other hand, as Ag particles that are difficult to sinter, for example, Ag particles having a large particle size, Ag particles produced by an atomizing method, or the like can be used.

The coil component of the present invention is not limited to the above-described embodiments, and various applications and modifications can be made within the scope of the present invention regarding the configuration of the coil component, manufacturing conditions, and the like.

For example, the coil 20 may or may not have a laminated structure.

The pattern shape of the coil 20 is not particularly limited. By changing the pattern shape of the coil 20, the inductance can be adjusted. For example, the pattern shape of the coil 20 may be linear.

One coil 20 may be arranged inside the magnetic body portion 10, or a plurality of coils 20 may be arranged. By arranging the plurality of coils 20 inside the magnetic body portion 10, the mounting area and the number of mounting points of the coil components can be reduced.

When a plurality of coils 20 are arranged inside the magnetic body portion 10, the configurations of the coils 20 may be the same, or may be partially or wholly different.

When a plurality of coils 20 are arranged inside the magnetic body portion 10, the arrangement of the coils 20 is not particularly limited. The plurality of coils 20 may all be arranged in the same direction, or some or all of them may be arranged in different directions. The plurality of coils 20 may be arranged linearly or may be arranged in a plane. The multiple coils 20 may be arranged regularly or may be arranged irregularly.

The following contents are disclosed in this specification.

<1>
a magnetic body portion containing metal magnetic particles;
a coil embedded inside the magnetic body;
an external electrode provided on at least the bottom surface of the magnetic body portion and electrically connected to the coil,
The external electrode includes, in order from the magnetic body portion side, an underlying layer containing Ag and a plating layer,
an oxide film containing the metal element contained in the metal magnetic particles is present between the metal magnetic particles and the underlayer at the interface between the magnetic material portion and the underlayer,
Inside the magnetic body portion, the surface of the metal magnetic particle adjacent to the metal magnetic particle located at the interface has a thickness smaller than that of the oxide film existing between the metal magnetic particle and the underlayer. Coil parts with oxide film.

<2>
The coil component according to <1>, wherein the oxide film present between the metal magnetic particles and the underlayer has a thickness of 50 nm or more.

<3>
The coil component according to <1>, wherein the oxide film present between the metal magnetic particles and the underlayer has a thickness of 100 nm or more.

<4>
The oxide film present between the metal magnetic particles and the underlayer is present on the underlayer-side surface of the metal magnetic particles located at the interface between the magnetic portion and the underlayer. The coil component according to any one of 1> to <3>.

<5>
The coil component according to any one of <1> to <4>, wherein the underlayer does not contain a glass component.

<6>
the oxide film present between the metal magnetic particles and the underlayer contains Zn;
The coil component according to any one of <1> to <5>, wherein the Zn is unevenly distributed on the underlayer side.

<7>
At the interface between the magnetic body portion and the coil, an oxide film having a thickness smaller than that of the oxide film existing between the metal magnetic particles and the underlayer is provided between the metal magnetic particles and the coil. The coil component according to any one of <1> to <6>, which is present.

<8>
<7>, wherein the oxide film present between the metal magnetic particles and the coil is present on the coil-side surface of the metal magnetic particles positioned at the interface between the magnetic portion and the coil; Coil components listed.

This specification also discloses the following.

<11>
a magnetic body portion containing metal magnetic particles;
a coil embedded inside the magnetic body;
an external electrode provided on at least the bottom surface of the magnetic body portion and electrically connected to the coil,
The external electrode includes, in order from the magnetic body portion side, an underlying layer containing Ag and a plating layer,
an oxide film containing the metal element contained in the metal magnetic particles is present between the metal magnetic particles and the underlayer at the interface between the magnetic material portion and the underlayer,
A coil component, wherein the oxide film present between the metal magnetic particles and the underlayer has a thickness of 50 nm or more.

<12>
The coil component according to <11>, wherein the oxide film present between the metal magnetic particles and the underlayer has a thickness of 100 nm or more.

<13>
The oxide film present between the metal magnetic particles and the underlayer is present on the underlayer-side surface of the metal magnetic particles located at the interface between the magnetic portion and the underlayer. 11> or the coil component according to <12>.

<14>
Inside the magnetic body portion, the surface of the metal magnetic particle adjacent to the metal magnetic particle located at the interface has a thickness smaller than that of the oxide film existing between the metal magnetic particle and the underlayer. The coil component according to any one of <11> to <13>, including an oxide film.

<15>
The coil component according to any one of <11> to <14>, wherein the underlayer does not contain a glass component.

<16>
the oxide film present between the metal magnetic particles and the underlayer contains Zn;
The coil component according to any one of <11> to <15>, wherein the Zn is unevenly distributed on the underlayer side.

<17>
At the interface between the magnetic body portion and the coil, an oxide film having a thickness smaller than that of the oxide film existing between the metal magnetic particles and the underlayer is provided between the metal magnetic particles and the coil. The coil component according to any one of <11> to <16>, which is present.

<18>
<17>, wherein the oxide film present between the metal magnetic particles and the coil is present on the coil-side surface of the metal magnetic particles positioned at the interface between the magnetic portion and the coil; Coil components listed.

REFERENCE SIGNS LIST 1 coil component 10 magnetic body portion 11 first main surface (bottom surface)
12 second main surface 13 first end surface 14 second end surface 15 first side surface 16 second side surface 20 coil 30 external electrode 31 first external electrode 31a underlying layer of first external electrode 31b first external electrode Plated layer of external electrode 31b ₁ First plated layer of first external electrode 31b ₂ Second plated layer of first external electrode 32 Second external electrode 32a Base layer of second external electrode 32b Second plated layer Plated layer of external electrode 40 lead conductor 41 first lead conductor 42 second lead conductor 50 metal magnetic particles 51 metal magnetic particles located at the interface between the magnetic portion and the underlayer 52 the interface between the magnetic portion and the underlayer 53 Metal magnetic particles located at the interface between the magnetic portion and the coil 61 Oxide film existing between the metal magnetic particles and the underlayer 62 Between the magnetic portion and the underlayer Oxide film existing on the surface of the metal magnetic particle adjacent to the metal magnetic particle located at the interface of the 63 Oxide film existing between the metal magnetic particle and the coil 70 Insulating layer 110 Magnetic paste layer 120, 131a, 132a Conductive paste layer 141, 142, 145 via conductor 170 insulating paste layer L length direction T height direction W width direction

Claims (8)

a magnetic body portion containing metal magnetic particles;
a coil embedded inside the magnetic body;
an external electrode provided on at least the bottom surface of the magnetic body portion and electrically connected to the coil,
The external electrode includes, in order from the magnetic body portion side, an underlying layer containing Ag and a plating layer,
an oxide film containing a metal element contained in the metal magnetic particles is present between the metal magnetic particles and the underlayer at the interface between the magnetic material portion and the underlayer,
Inside the magnetic body portion, the surface of the metal magnetic particle adjacent to the metal magnetic particle located at the interface has a thickness smaller than that of the oxide film existing between the metal magnetic particle and the underlayer. Coil parts with oxide film. 2. The coil component according to claim 1, wherein said oxide film present between said metal magnetic particles and said underlayer has a thickness of 50 nm or more. 2. The coil component according to claim 1, wherein said oxide film present between said metal magnetic particles and said underlayer has a thickness of 100 nm or more. The oxide film present between the metal magnetic particles and the underlayer is present on the underlayer-side surface of the metal magnetic particles positioned at the interface between the magnetic portion and the underlayer. 4. The coil component according to any one of items 1 to 3. 4. The coil component according to claim 1, wherein said underlayer does not contain a glass component. the oxide film present between the metal magnetic particles and the underlayer contains Zn;
4. The coil component according to claim 1, wherein said Zn is unevenly distributed on said underlayer side. An oxide film having a smaller thickness than the oxide film existing between the metal magnetic particles and the underlying layer is formed between the metal magnetic particles and the coil at the interface between the magnetic body portion and the coil. A coil component according to any one of claims 1 to 3, present. 8. The method according to claim 7, wherein the oxide film present between the metal magnetic particles and the coil is present on the coil-side surface of the metal magnetic particles positioned at the interface between the magnetic portion and the coil. Coil components listed.

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