Electronic component

Abstract

The present invention provides an electronic component capable of suppressing migration of impurity atoms between a conductor and an external electrode. A coil component (1) as the electronic component includes: a substrate (10); a conductor (25); an external electrode (21) electrically connected to the conductor (25); an external electrode (22) electrically connected to the conductor (25); and a metal film (23) located between the conductor (25) and the external electrode (21). When a size of one metal particle (MP) contained in the metal film (23) in a direction parallel to an interface (BI) is defined as a, and a size of the one metal particle (MP) in a direction perpendicular to the interface (BI) is defined as b, an average value of b / a is 0.8 or more and 1.2 or less.

Description

Technical Field

[0001] The invention described in this specification relates to an electronic component. Background Art

[0002] As an electronic component, a coil component such as an inductor is known. A coil component of the prior art typically includes: a magnetic substrate made of a magnetic material; a conductor wound around a coil axis and disposed within the magnetic substrate; and external electrodes connected to the ends of the conductor. The coil component is mounted, for example, by electrically connecting the external electrodes to a substrate using solder, and can be used as a component of various electronic devices. A coil component of the prior art is disclosed, for example, in Patent Document 1.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-140371 Summary of the Invention

[0006] Technical Problem to be Solved by the Invention

[0007] Between the conductor and the external electrode of an electronic component, due to heat or voltage application, etc., migration of impurity atoms contained in solder or the like sometimes occurs. When migration occurs, since the impurity atoms form an alloy with the conductor or the material constituting the external electrode, voids are formed in the conductor and / or the external electrode. As a result, there is a problem that the bonding strength between the conductor and the external electrode is reduced.

[0008] One object of the present invention is to provide an electronic component capable of suppressing the migration of impurity atoms between the conductor and the external electrode. Other objects of the present invention will be clarified by the description throughout the specification.

[0009] Technical Solution for Solving the Technical Problem

[0010] An electronic component according to an embodiment of the present invention includes: a substrate; a conductor disposed inside or outside the substrate; a first external electrode electrically connected to the conductor; a second external electrode electrically connected to the conductor; and a metal film located between the conductor and the first external electrode. When the size of one metal particle contained in the metal film in the direction parallel to the interface between the conductor and the metal film is set as a, and the size of the one metal particle in the direction perpendicular to the interface is set as b, the average value of b / a is 0.8 or more and 1.2 or less.

[0011] In one embodiment of the present invention, at least a part of the conductor and the metal film may be connected by a metal bond.

[0012] In one embodiment of the present invention, it is also possible that an oxide film is provided between the conductor and the metal film, and the thickness of the oxide film is 200 nm or less.

[0013] In one embodiment of the present invention, it is also possible that, in a direction perpendicular to the interface, the particle size of the metal particles on the conductor side is smaller than the particle size of the metal particles on the first external electrode side.

[0014] In one embodiment of the present invention, it is also possible that the metal film is a sputtered film.

[0015] In one embodiment of the present invention, it is also possible that the voids at the interfaces between the metal particles contained in the metal film are 5 or less in terms of the corresponding amount of atoms constituting the metal particles.

[0016] In one embodiment of the present invention, it is also possible that the metal film contains Cu, Ag, or an alloy containing at least one of Cu and Ag.

[0017] In one embodiment of the present invention, it is also possible that it includes another metal film located between the conductor and the second external electrode. When the size of a metal particle contained in the other metal film in a direction parallel to the other interface between the conductor and the other metal film is defined as a, and the size of the metal particle in a direction perpendicular to the other interface is defined as b, the average value of b / a is 0.8 or more and 1.2 or less.

[0018] In one embodiment of the present invention, it is also possible that at least a part of the conductor and the other metal film are connected by a metallic bond.

[0019] In one embodiment of the present invention, it is also possible that another oxide film is provided between the conductor and the other metal film, and the thickness of the other oxide film is 200 nm or less.

[0020] In one embodiment of the present invention, it is also possible that, in a direction perpendicular to the other interface, the particle size of the metal particles on the conductor side is smaller than the particle size of the metal particles on the second external electrode side.

[0021] In one embodiment of the present invention, it is also possible that the other metal film is a sputtered film.

[0022] In one embodiment of the present invention, it is also possible that the voids in the interfaces between the metal particles contained in the other metal film are 5 or less in terms of the corresponding amount of atoms constituting the metal particles.

[0023] In one embodiment of the present invention, it is also possible that the other metal film contains Cu, Ag, or an alloy containing at least one of Cu and Ag.

[0024] In one embodiment of the present invention, it is also possible that the ionization tendency of the main component of the metal contained in the first external electrode and the second external electrode is smaller than the ionization tendency of the main component of the metal contained in the conductor.

[0025] In one embodiment of the present invention, it is also possible that the conductor includes a portion wound around the coil axis.

[0026] One embodiment of the present invention relates to a circuit board including any of the above-described electronic components. Further, one embodiment of the present invention relates to an electronic device including the above-described circuit board.

[0027] Advantages of the Invention

[0028] According to the present invention, an electronic component capable of suppressing the migration of impurity atoms between a conductor and an external electrode can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 FIG. is a perspective view schematically showing a coil component as an electronic component according to one embodiment of the present invention.

[0030] Figure 2 is Figure 1 an enlarged cross-sectional view schematically showing a cross-section of a magnetic substrate of the coil component of

[0031] Figure 3 is Figure 1 an enlarged cross-sectional view showing, in an enlarged manner, a periphery of a joint portion between an end portion of a conductor of the coil component and an external electrode.

[0032] Figure 4 is a schematic diagram of an electron microscope image of a cross-section of a joint portion between an end face of a conductor of the coil component and a metal film.

[0033] Figure 5A is a schematic diagram of a transmission electron microscope image showing metal particles contained in a metal film of the coil component.

[0034] Figure 5B is a schematic diagram of a transmission electron microscope image showing metal particles contained in a general metal film.

[0035] Figure 6A is schematically showing Figure 5A a diagram of grain boundaries of metal particles of the metal film shown in

[0036] Figure 6B is schematically showing Figure 5B a diagram of grain boundaries of metal particles of the general metal film shown in

[0037] Figure 7A is schematically showing Figure 5ADiagram of the movement path of atoms in the metal film shown

[0038] Figure 7B Schematically represents Figure 5B Diagram of the movement path of atoms in the ordinary metal film shown

[0039] Figure 8 Is a perspective view schematically showing a coil component according to another embodiment of the present invention

[0040] Figure 9 Is a cross-sectional view schematically showing a capacitor as an electronic component according to another embodiment of the present invention

[0041] Explanation of reference numerals

[0042] 1, 100... Coil components (electronic components), 10... Magnetic substrate, 11... First metal magnetic particles, 12... Second metal magnetic particles, 13... Binding material, 21... External electrode (first external electrode), 22... External electrode (second external electrode), 23... Metal film, 25... Conductor, 25a1... Lead conductor (one end), 25b1... Lead conductor (the other end), 200... Capacitor (electronic component), BI... Interface Detailed description of the embodiments

[0043] Hereinafter, various embodiments of the present invention will be described with reference to appropriate drawings. Among them, the same constituent elements in the plurality of drawings are denoted by the same reference numerals in the plurality of drawings. For convenience of explanation, it should be noted that the respective drawings are not necessarily drawn strictly to scale

[0044] Refer to Figure 1 , and the outline of the coil component 1 as an electronic component according to one embodiment of the present invention will be described Figure 1 Is a perspective view schematically showing the coil component 1. As Figure 1 Shown, the coil component 1 includes: a substrate 10; a coil conductor 25 provided inside the substrate 10; an external electrode (first external electrode) 21 provided on the surface of the substrate 10; and an external electrode (second external electrode) 22 provided on the surface of the substrate 10 at a position spaced apart from the external electrode 21

[0045] In this specification, unless otherwise interpreted in the context, the "length" direction, "width" direction, and "thickness" direction of the coil component 1 are respectively taken as Figure 1 The "L-axis" direction, "W-axis" direction, and "T-axis" direction of. The "thickness" direction is sometimes also referred to as the "height" direction

[0046] The coil component 1 is mounted on a circuit board (not shown). Two pad portions are provided on the circuit board. The coil component 1 can be mounted on the circuit board by joining the external electrodes 21 and 22 to the pad portions corresponding to the external electrodes 21 and 22 respectively. The electronic devices on which the circuit board can be mounted include smartphones, tablet computers, game consoles, and various other electronic devices. The circuit board can also be mounted on an electronic mounting component of an automobile, which is a type of electronic device.

[0047] The coil component 1 can be applied to inductors, transformers, filters, reactors, and various other coil components. The coil component 1 can also be applied to coupled inductors, choke coils, and various other magnetically coupled coil components. The uses of the coil component 1 are not limited to the components clearly shown in this specification.

[0048] The substrate 10 is made of an insulating material. In one embodiment, the substrate 10 is mainly made of a magnetic material and is formed in a rectangular parallelepiped shape. The substrate 10 of the coil component 1 according to one embodiment of the present invention is formed such that the length dimension (dimension in the L-axis direction) is 1.0 mm to 4.5 mm, the width dimension (dimension in the W-axis direction) is 0.5 mm to 3.2 mm, and the height dimension (dimension in the T-axis direction) is 0.5 mm to 5.0 mm. The dimensions of the substrate 10 are not limited to the dimensions specifically described in this specification. In this specification, the term "rectangular parallelepiped" or "rectangular parallelepiped shape" does not only refer to the "rectangular parallelepiped" in the strict mathematical sense.

[0049] The substrate 10 has a first main surface 10a, a second main surface 10b, a first end surface 10c, a second end surface 10d, a first side surface 10e, and a second side surface 10f. The outer surface of the substrate 10 is defined by these six surfaces. The first main surface 10a and the second main surface 10b respectively form the surfaces at both ends in the height direction, the first end surface 10c and the second end surface 10d respectively form the surfaces at both ends in the length direction, and the first side surface 10e and the second side surface 10f respectively form the surfaces at both ends in the width direction.

[0050] As Figure 1 shown, since the first main surface 10a is located on the upper side of the substrate 10, the first main surface 10a is sometimes referred to as the "upper surface". Similarly, the second main surface 10b is sometimes referred to as the "lower surface". The coil component 1 is arranged such that the first main surface 10a faces the circuit board, so the first main surface 10a is sometimes referred to as the "mounting surface". When referring to the up-down direction of the coil component 1, it is based on the up-down direction of Figure 1 .

[0051] Next, with reference to Figure 2 , the magnetic substrate 10 will be further described. Figure 2It is an enlarged cross-sectional view that magnifies and schematically shows the cross-section of the substrate 10. As shown in the figure, the substrate 10 includes a plurality of first metal magnetic particles 11, a plurality of second metal magnetic particles 12, and a binding material 13. The binding material 13 bonds the plurality of first metal magnetic particles 11 and the plurality of second metal magnetic particles 12 to each other. In other words, the substrate 10 is composed of the binding material 13 and the plurality of first metal magnetic particles 11 and the plurality of second metal magnetic particles 12 bonded together by the binding material 13.

[0052] The plurality of first metal magnetic particles 11 have a larger average particle diameter than the plurality of second metal magnetic particles 12. That is, the average particle diameter of the plurality of first metal magnetic particles 11 (hereinafter referred to as the first average particle diameter.) is different from the average particle diameter of the plurality of second metal magnetic particles 12 (hereinafter referred to as the second average particle diameter.). The first average particle diameter is, for example, 30 μm, and the second average particle diameter is, for example, 0.1 μm, and they may also be average particle diameters different from them. In one embodiment of the present invention, the substrate 10 may further include a plurality of third metal magnetic particles (hereinafter referred to as the third average particle diameter for the average particle diameter of the third metal magnetic particles.) not shown having an average particle diameter different from the first average particle diameter and the second average particle diameter. The third average particle diameter may be smaller than the first average particle diameter and larger than the second average particle diameter, or may be smaller than the second average particle diameter. In the following description, in this specification, when it is not necessary to distinguish the first metal magnetic particles 11, the second metal magnetic particles 12, and the third metal magnetic particles from each other, the first metal magnetic particles 11, the second metal magnetic particles 12, and the third metal magnetic particles contained in the magnetic substrate 10 are collectively referred to as "metal magnetic particles".

[0053] The first metal magnetic particles 11 and the second metal magnetic particles 12 are composed of various soft magnetic materials. The first metal magnetic particles 11 are mainly composed of Fe, for example. Specifically, the first metal magnetic particles 11 are (1) metal particles such as Fe and Ni, (2) crystalline alloy particles such as Fe-Si-Cr alloy, Fe-Si-Al alloy, and Fe-Ni alloy, (3) amorphous alloy particles such as Fe-Si-Cr-B-C alloy and Fe-Si-Cr-B alloy, or (4) mixed particles obtained by mixing them. The composition of the metal magnetic particles contained in the magnetic substrate 10 is not limited to the above composition. The first metal magnetic particles 11 contain, for example, 85 wt% or more of Fe. Thereby, a magnetic substrate 10 having excellent magnetic permeability can be obtained. The composition of the second metal magnetic particles 12 may be the same as or different from the composition of the first metal magnetic particles 11. When the magnetic substrate 10 includes a plurality of third metal magnetic particles not shown, the composition of the third metal magnetic particles, like the composition of the second metal magnetic particles 12, may be the same as or different from the composition of the first metal magnetic particles 11.

[0054] The surface of the metal magnetic particles can be covered with an insulating film (not shown). For example, the insulating film is formed of glass, resin, or other materials with excellent insulation properties. For example, the insulating film is formed on the surface of the first metal magnetic particles 11 by mixing the first metal magnetic particles 11 and glass material powder in a friction mixer (not shown). The insulating film formed of the glass material adheres tightly to the surface of the first metal magnetic particles 11 through compressive friction in the friction mixer. The glass material may contain ZnO and P2O5. The insulating film can be formed of various glass materials. The insulating film 14 can be formed of alumina powder, zirconia powder, or powder of other oxides with excellent insulation properties instead of or on the basis of glass powder. The thickness of the insulating film is, for example, 100 nm or less.

[0055] The second metal magnetic particles 12 can be covered with an insulating film different from that of the first metal magnetic particles 11. The insulating film can be an oxide film that can be formed by oxidizing the second metal magnetic particles 12. The thickness of the insulating film is, for example, 20 nm or less. The insulating film can also be an oxide film formed on the surface of the second metal magnetic particles 12 by heat-treating the second metal magnetic particles 12 in an atmospheric atmosphere. The insulating film can also be an oxide film containing Fe and an element contained in the second metal magnetic particles 12 other than that. The insulating film can also be an iron phosphate film formed on the surface of the second metal magnetic particles 12 by putting the second metal magnetic particles 12 into phosphoric acid and stirring. The insulating film of the first metal magnetic particles 11 can be an oxide film that can be formed by oxidizing the first metal magnetic particles 11, and the insulating film of the second metal magnetic particles 12 can also be a covering film provided separately without relying on the oxidation of the second metal magnetic particles 12.

[0056] The binding material 13 is, for example, a thermosetting resin with excellent insulation properties. Regarding the binding material 13, for example, epoxy resin, polyimide resin, polystyrene (PS) resin, high-density polyethylene (HDPE) resin, polyoxymethylene (POM) resin, polycarbonate (PC) resin, polyvinylidene fluoride (PVDF) resin, phenolic resin, polytetrafluoroethylene (PTFE) resin, or polybenzoxazole (PBO) resin can be used. In addition, glass or the like can also be used as the binding material 13, and the binding material 13 can also contain insulating fillers and the like.

[0057] The conductor 25 is formed in a prescribed pattern. In the illustrated embodiment, the conductor 25 is wound around the coil axis Ax (see Figure 1 ). The conductor 25 is, for example, in a spiral shape, a bent shape, a straight shape, or a shape formed by combining them when viewed from above.

[0058] The conductor 25 is formed by plating with Cu, Ag, or other conductive materials. The entire region of the surface of the conductor 25 except for the end faces 25a2 and 25b2 can be covered by an insulating film. As shown in the figure, when the conductor 25 is wound around the coil axis Ax for multiple turns, the turns of the conductor 25 can be spaced apart from adjacent other turns. In this case, there is a base body 10 between adjacent turns.

[0059] The conductor 25 has a lead-out conductor 25a1 at one end and a lead-out conductor 25b1 at the other end. An end face 25a2 is formed at the end of the lead-out conductor 25a1, and an end face 25b2 is formed at the end of the lead-out conductor 25b1. The lead-out conductor 25a1 as one end of the conductor 25 is electrically connected to the external electrode 21, and the lead-out conductor 25b1 as the other end of the conductor 25 is electrically connected to the external electrode 22.

[0060] In one embodiment of the present invention, the external electrode 21 is provided on a part of the first main surface 10a, the second main surface 10b, the second end face 10c, the first side face 10e, and the second side face 10f of the base body 10. The external electrode 22 is provided on a part of the first main surface 10a, the second main surface 10b, the second end face 10d, the first side face 10e, and the second side face 10f of the base body 10. The external electrodes 21 and 22 are arranged at intervals from each other. The shapes and arrangements of the external electrodes 21 and 22 are not limited to the illustrated examples. The lead-out conductor 25a1 and the lead-out conductor 25b1 are respectively led out to the first main surface (i.e., the mounting surface) 10a of the base body 10, and the end face 25a2 of the lead-out conductor 25a1 and the end face 25b2 of the lead-out conductor 25b1 are exposed from the base body 10 on the first main surface 10a. That is, the end face 25a2 of the lead-out conductor 25a1 and the end face 25b2 of the lead-out conductor 25b1 are exposed from the base body 10 on the same surface. The end face 25a2 of the lead-out conductor 25a1 and the end face 25b2 of the lead-out conductor 25b1 may also be exposed from the base body 10 on different surfaces from each other.

[0061] The external electrodes 21 and 22 can be entirely made of metal, or can contain materials other than metal such as resin in part. As an example of containing materials other than metal such as resin in part, there is a conductive resin film. A plating layer can also be provided on the surface of this conductive resin film, for example. The plating layer can be a single-layer plating layer such as a Ni plating layer or a Sn plating layer, or can be a plating layer formed of two layers including a nickel plating layer and a tin plating layer formed on this nickel plating layer.

[0062] Figure 3 is an enlarged cross-sectional view showing an enlarged view of the periphery of the joint portion between one end of the conductor 25 of the coil component 1 and the external electrode 21. As Figure 1 shown. Figure 3As shown, the coil component 1 has a metal film 23 located between the external electrode 21 and one end of the conductor 25 (i.e., the lead-out conductor 25a1). That is, the external electrode 21 and one end of the conductor 25 are electrically connected via the metal film 23. In addition, the coil component 1 has another metal film (not shown) located between the external electrode 22 and the other end of the conductor 25 (i.e., the lead-out conductor 25b1). The metal film 23 and the other metal film are, for example, sputtering films. In the illustrated embodiment, the metal film 23 and the other metal film have the same function, material, and shape. In the following description, unless otherwise specified, the description of the metal film 23 can also be applied to the other metal film. Additionally, Figures 3 to 7B is a diagram for explaining the metal film 23 and can also be applied to the other metal film.

[0063] The material of the metal film 23 is, for example, a metal such as Ag, Au, Pd, Pt, Cu, Ni, Ti, Ta, or an alloy thereof. The metal used for the metal film 23 is preferably a metal that is not easily oxidized or a metal that can be easily reduced even if oxidized. In addition, for the metal film 23, a material with a low volume resistivity is preferably used. The thickness of the metal film 23 is not particularly limited and can be, for example, 1 μm or more and 5 μm or less. It is preferable that the ionization tendency of the main component of the metal contained in the metal film 23 is smaller than the ionization tendency of the metal constituting the conductor 25. Here, the "main component of the metal contained in the metal film 23" refers to the metal component that accounts for more than half of the metal weight by weight % among the metals constituting the metal film 23. If the type of metal contained in the metal film 23 is one type, the main component refers to that metal component. As an example, when the material of the conductor 25 is Cu, the metal contained in the metal film 23 can be Ag.

[0064] The metal film 23 and at least a part of one end of the conductor 25 (i.e., the end face 25a2) are connected by metal bonding. Here, "at least a part of one end of the conductor 25" refers to any region of the end face 25a2. For example, the metal film 23 and the end 25a1 are connected by metal bonding at the periphery PP of the end face 25a2 (see Figure 3 ). Figure 3 An example is shown in which the metal film 23 and the end 25a1 of the conductor 25 are connected by metal bonding over the entire surface of the end face 25a2. In Figure 3 's example, the metal film 23 and the end 25a1 are also metal-bonded at the periphery PP of the end face 25a2.

[0065] Next, with reference to Figure 4 , Figure 5A , Figure 6A , the metal film 23 will be described in detail. Figure 4It is a schematic diagram of an electron microscope image of a cross section of a joint portion between an end face 25a2 of a conductor 25 of a coil component 1 and a metal film 23. Figure 5A It is a schematic diagram of a transmission electron microscope image of metal particles contained in a metal film 23 of a coil component 1. Figure 6A It schematically shows Figure 5A a diagram of grain boundaries of metal particles of the metal film 23 shown in

[0066] As Figure 4 shown, in a direction perpendicular to the interface BI between the metal film 23 and the end portion 25a1 of the conductor 25 (i.e., the thickness direction Tn of the metal film 23), the particle size of the metal particles MP on the end portion 25a1 side is smaller than the particle size of the metal particles MP on the external electrode 21 side. The interface BI has multiple irregularities microscopically. In this specification, when defining a direction based on the interface BI, the interface BI can be understood as a flat surface extending in one direction. As an example, it can also be that the average particle size of the metal particles MP on the end portion 25a1 side, which is closer to the end portion 25a1 than half of the thickness direction Tn of the metal film 23, is 50 nm or more and 100 nm or less, and the average particle size of the metal particles MP on the external electrode 21 side, which is closer to the external electrode 21 than half of the thickness direction Tn of the metal film 23, is 100 nm or more and 500 nm or less. It can also be contrary to the illustrated embodiment, where the particle size of the metal particles MP on the end portion 25a1 side is larger than the particle size of the metal particles MP on the external electrode 21 side.

[0067] As Figure 5A shown, the average aspect ratio of the metal particles MP contained in the metal film 23 is 0.8 or more and 1.2 or less. Here, the aspect ratio of the metal particle MP refers to the value of b / a when the dimension of a metal particle MP contained in the metal film 23 in a direction parallel (horizontal) to the interface BI (i.e., the plane direction Sf) is set as a, and the dimension of the metal particle MP in a direction perpendicular to the interface BI (i.e., the thickness direction Tn) is set as b. The average aspect ratio of the metal particles MP can be, for example, the average value of the aspect ratios of multiple metal particles MP such as 5 or 10. In addition, as Figure 6A shown, the metal particles MP contained in the metal film 23 are metallically bonded to each other. Therefore, the voids in the interfaces between the metal particles MP contained in the metal film 23 are 5 or less corresponding amounts of atoms constituting the metal particles MP. In the illustrated embodiment, there are no impurities or voids in the interfaces between the metal particles MP. In the interfaces between the metal particles MP, the atoms constituting the metal particles MP are periodically arranged and have continuity.

[0068] Next, a method for manufacturing a coil component 1, which is an electronic component according to an embodiment of the present invention, will be described. First, a conductor 25 formed in a coil shape from a metal material or the like and a mixed resin composition are placed in a molding die and compression molded so that the end faces 25a2 of the lead conductors 25a1 of the conductor 25 and the end faces 25b2 of the lead conductors 25b1 are exposed on the surface. The mixed resin composition is prepared by mixing a particle group containing first metal magnetic particles 11 and second metal magnetic particles 12 with a binding material 13 formed from a resin or the like. The conductor 25 formed in a coil shape is, for example, a conductor formed by winding a wire into a spiral shape. However, in addition to winding, it may also be formed into a planar coil, and the coil shape is not particularly limited. The conductor 25 may also have an insulating coating. By curing the resin in the molded body, a magnetic substrate 10 in which the conductor 25 is embedded can be obtained.

[0069] Next, the surface of the magnetic substrate 10 where the end faces 25a2 of the lead conductors 25a1 of the conductor 25 and the end faces 25b2 of the lead conductors 25b1 are exposed is smoothed and the oxide is removed. Here, polishing is performed using an abrasive, and then plasma etching is performed. As the particle size of the abrasive, an abrasive having a particle size smaller than that of the first metal magnetic particles 11 is preferably used. For example, if the average particle size of the first metal particles 11 is 30 μm, a particle size of 25 μm is preferably used. The etching may be a method such as plasma etching that can remove the oxide on the surface of the magnetic substrate.

[0070] Next, a metal film 23 is formed. As a method for forming the metal film 23, for example, there is a sputtering deposition method, particularly a high-density sputtering deposition method. The high-density sputtering deposition method is a method in which by applying a large amount of electric energy only for a short time, the sputtered film is prevented from becoming high temperature and a dense film is obtained. During sputtering, by cooling the specimen, a larger amount of electric energy can be applied and a more dense sputtered film can be obtained. By this method, when using the above-mentioned metal, the sputtering efficiency is high, and the metal film 23 can be formed efficiently. In this specification, a metal film formed by the sputtering deposition method is referred to as a sputtered film. The method for forming the metal film 23 may be any method that can metallically bond the end face 25a2 of the conductor 25 to the metal film 23, and the metal film 23 may also be formed by a method other than the sputtering deposition method.

[0071] The metal film 23 formed by the sputtering deposition method can reduce the particle size of the metal particles MP constituting the metal film 23. Thus, the metal film 23 is as Figure 4As shown, a dense film can be formed. As a specific example, the average particle size of the metal particles MP is 10 nm to 50 nm from the interface BI to the thickness of the metal film 23 of 200 nm, 50 nm to 150 nm from the thickness of the metal film 23 of 200 nm to 500 nm, and 150 nm to 300 nm when the thickness of the metal film 23 is 500 nm or more. In addition, in this method, the aspect ratio in the thickness direction of the metal film 23 of the metal particles MP constituting the metal film 23 can be, for example, 0.8 to 1.5. More preferably, the aspect ratio of the metal particles MP constituting the metal film 23 can be 0.8 to 1.2. Therefore, a dense film in which the proportion (density) of the metal particles MP occupying the metal film 23 is 99% or more can be formed. This proportion can be confirmed by the fact that the proportion of voids in the bright-field image at 500,000 times magnification using TEM (transmission electron microscope) is less than 1%.

[0072] In the case of implementing the sputtering deposition method using a sputtering device (not shown), for example, the settings of the device are as follows. First, components are placed in the device to make the inside of the device in a high-vacuum state, the oxygen inside the device is exhausted, and the rare gas is ionized. The film formation surface is cleaned by reverse sputtering, and then the metal target (the metal that becomes the material of the metal film 23) is sputtered. The metal atoms rebounding from the metal target are deposited on the mounting surface 10a of the component body with high energy. In this way, by the sputtering deposition method, a metal film 23 with few impurities and no oxides can be formed. The end faces 25a2 of the lead-out conductor 25a1 and the end faces 25b2 of the lead-out conductor 25b1 are respectively exposed on the mounting surface 10a, so this method can form the metal film 23 and other metal films simultaneously. In addition, a metal material that is easily oxidized can also be used. In particular, when the ionization tendency of the metal of the metal target is smaller than the ionization tendency of the metal of the end faces 25a2 and 25b2, the metal atoms rebounding from the metal target are less likely to be oxidized compared to the metal of the end face 25a2. Therefore, a metal film 23 without oxides can be formed.

[0073] Finally, the external electrodes 21 and 22 are formed by sputtering or the like. The coil component 1 can be manufactured according to the above content. The manufactured coil component 1 is mounted on the circuit board by soldering the external electrodes 21 and 22 to the pad portions of the circuit board respectively.

[0074] Next, with reference to Figures 5A to 7B , the operation and effect of the coil component 1 according to an embodiment of the present invention will be described. Figure 5B is a schematic diagram showing a transmission electron microscope image of metal particles contained in a normal metal film. Figure 6B is schematically showing Figure 5B the grain boundaries of the metal particles of the normal metal film shown in Figure 7A is schematically showing Figure 5ADiagram of the movement path of atoms in the metal film 23 shown Figure 7B Schematically represents Figure 5B Diagram of the movement path of atoms in a general metal film shown

[0075] As Figure 5A shown, the coil component 1 of an embodiment of the present invention has a metal film 23. When the dimension of a metal particle MP contained in the metal film 23 in the direction parallel (horizontal) to the interface BI between one end 25a1 of the conductor 25 and the metal film 23 is set as a, and the dimension of the metal particle MP in the direction perpendicular to the interface BI is set as b, the average value of b / a is 0.8 or more and 1.2 or less. As Figure 5B shown, the average aspect ratio of metal particles contained in a general metal film is greater than 2. Therefore, in a general metal film, when impurity atoms move in the direction perpendicular to the interface BI (i.e., the thickness direction Tn), the probability of colliding with the metal particles contained in the metal film is low (refer to Figure 7B ). As the type of impurity atoms, for example, tin contained in the solder for mounting the coil component 1 on a circuit board can be cited. In contrast, as in the coil component 1 of an embodiment of the present invention, by making the average value of b / a 0.8 or more and 1.2 or less, when impurity atoms move in the direction perpendicular to the interface, the probability of colliding with the metal particles contained in the metal film becomes larger, and the mean free path becomes shorter. As a result, the number of times the impurity atoms move in the direction Sf increases, and the moving distance required to pass through the metal film 23 becomes longer (refer to Figure 7A and Figure 7B ). As an example, when the diffusion rate in the metal film 23 is set as 1, the diffusion rate in a general metal film is 10e 3 ~ 7 level. Therefore, migration between the conductor 25 and the external electrode 21 can be suppressed

[0076] In addition, as Figure 6A shown, the voids at the interface between the metal particles MP contained in the metal film 23 can be 5 or less of the corresponding amount of atoms constituting the metal particles MP. As Figure 6B shown, there are obvious voids at the interface between metal particles in a general metal film, and the continuity of the lattice arrangement is truncated. Therefore, when impurity atoms move in the metal film, it is easy to pass through the interface between metal particles. In contrast, in the metal film 23 of the coil component 1 of an embodiment of the present invention, the voids at the interface between the metal particles MP are 5 or less of the corresponding amount of atoms, so impurity atoms are not likely to move at the interface between metal particles. Therefore, migration between the conductor 25 and the external electrode 21 can be suppressed

[0077] Next, referring toFigure 8 , a coil component 100 according to another embodiment of the present invention will be described. Figure 8 FIG. is a perspective view schematically showing the coil component 100. As shown in the figure, the coil component 100, like the coil component 1, has: a base body 10; a coil conductor 25 provided inside the base body 10; an external electrode 21 provided on the surface of the base body 10; and an external electrode 22 provided on the surface of the base body 10 at a position spaced apart from the external electrode 21. The coil component 100 includes an insulating plate 50 provided inside the base body 10, and the conductor 25 is provided on the upper and lower surfaces of the insulating plate 50, which is different from the coil component 1.

[0078] The coil component 100, like the coil component 1, also has a metal film 23 located between the external electrode 21 and one end of the conductor 25, and the aspect ratio of the metal particles MP contained in the metal film 23 is 0.8 or more and 1.2 or less. Therefore, for the same reason as the coil component 1, migration of impurity atoms between the conductor 25 and the external electrode 21 can be suppressed.

[0079] The electronic component of the present invention is not limited to the coil component, and may be, for example, a capacitor. Figure 9 FIG. is a cross-sectional view schematically showing a capacitor 200 as an electronic component according to another embodiment of the present invention. As Figure 9 shown, the capacitor 200 includes: a base body 210; a conductor 225 provided inside the base body 210; and external electrodes 202 and 203 provided outside the base body 210. In Figure 9 the embodiment shown, the capacitor 200 is a so-called MLCC, and the conductor 225 includes a plurality of first electrode layers 221 and a plurality of second electrode layers 222. The first electrode layers 221 and the second electrode layers 222 are alternately arranged with the base material 210 interposed therebetween. The portion of the base material 210 located between the first electrode layer 221 and the second electrode layer 222 functions as a dielectric. The capacitor 200, like the coil component 1, has: a metal film 23 located between the external electrode 202 and the conductor 225; and another metal film located between the external electrode 203 and the conductor 225.

[0080] The above-described capacitor 200, like the coil component 1, also has a metal film 23 located between the conductor 225 and the external electrode 202; and another metal film located between the conductor 225 and the external electrode 203, and the aspect ratio of the metal particles MP contained in the metal film 23 and the other metal film is 0.8 or more and 1.2 or less. Therefore, for the same reason as the coil component 1, migration of impurity atoms between the conductor 225 and the external electrode 202 can be suppressed.

[0081] In each of the above-described embodiments, the dimensions, materials, and arrangements of the respective components are not limited to those explicitly described in the embodiments, and each of these components can have any dimensions, materials, and arrangements that can be deformed to be included within the scope of the present invention. In addition, components not explicitly described in this specification can be added to each of the above-described embodiments, and a part of the components described in each embodiment can be omitted.

[0082] For example, the coil member 1 and the coil member 100 may each further have an oxide film between one end portion 25a1 of the conductor 25 and the metal film 23, and between the other end portion 25b1 of the conductor 25 and another metal film. The thickness of the oxide film is formed to be a thickness through which a tunneling current or a Schottky current can flow. As an example, the thickness of the oxide film can be formed to be 200 nm or less. Since the diffusion rate in the oxide film is slower than the diffusion rate in the external electrodes 21 and 22, according to this structure, migration of impurity atoms between the conductor 25 and the external electrodes 21 and 22 can be further suppressed.

Claims

1. An electronic component, characterized in that, Comprising: A substrate; A conductor disposed inside or outside the substrate; A first external electrode electrically connected to the conductor; A second external electrode electrically connected to the conductor; And A metal film located between the conductor and the first external electrode, When the size of a metal particle contained in the metal film in a direction parallel to the interface between the conductor and the metal film is set as a, and the size of the metal particle in a direction perpendicular to the interface is set as b, the average value of b / a is 0.8 or more and 1.2 or less. An oxide film is provided between the conductor and the metal film.

2. The electronic component according to claim 1, wherein: At least a part of the conductor and the metal film are connected by metallic bonding.

3. The electronic component according to claim 1, wherein: The thickness of the oxide film is 200 nm or less.

4. The electronic component according to any one of claims 1 to 3, wherein: In a direction perpendicular to the interface, the particle size of the metal particles on the conductor side is smaller than that of the metal particles on the first external electrode side.

5. The electronic component according to any one of claims 1 to 3, wherein: The metal film is a sputtered film.

6. The electronic component according to any one of claims 1 to 3, wherein: The voids at the interfaces between the metal particles contained in the metal film are 5 or less in terms of the corresponding amount of atoms constituting the metal particles.

7. The electronic component according to any one of claims 1 to 3, wherein: The metal film contains Cu, Ag, or an alloy containing at least one of Cu and Ag.

8. The electronic component according to any one of claims 1 to 3, wherein: It includes another metal film located between the conductor and the second external electrode, When the size of a metal particle contained in the other metal film in a direction parallel to the other interface between the conductor and the other metal film is set as a, and the size of the metal particle in a direction perpendicular to the other interface is set as b, the average value of b / a is 0.8 or more and 1.2 or less.

9. The electronic component according to claim 8, wherein: At least a part of the conductor and the other metal film are connected by metallic bonding.

10. The electronic component according to claim 8, wherein: Another oxide film is provided between the conductor and the other metal film, The thickness of the other oxide film is 200 nm or less.

11. The electronic component according to claim 8, wherein: In a direction perpendicular to the other interface, the particle size of the metal particles on the conductor side is smaller than that of the metal particles on the second external electrode side.

12. The electronic component according to claim 8, wherein: The other metal film is a sputtered film.

13. The electronic component according to claim 8, wherein: The voids in the interfaces between the metal particles contained in the other metal film are 5 or less in terms of the corresponding amount of atoms constituting the metal particles.

14. The electronic component according to claim 8, wherein: the other metal film contains Cu, Ag, or an alloy containing at least one of Cu and Ag.

15. The electronic component according to any one of claims 1 to 3, wherein: the ionization tendency of the main component of the metal contained in the first external electrode and the second external electrode is smaller than the ionization tendency of the main component of the metal contained in the conductor.

16. The electronic component according to any one of claims 1 to 3, wherein: the conductor includes a portion wound around the coil axis.

17. A circuit board, wherein: it includes the electronic component according to any one of claims 1 to 16.

18. An electronic device, wherein: it includes the circuit board according to claim 17.

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