WO2024101214A1

WO2024101214A1 - Electrolytic capacitor

Info

Publication number: WO2024101214A1
Application number: PCT/JP2023/039188
Authority: WO
Inventors: 克朋有富; 芳正吉野
Original assignee: 株式会社村田製作所
Priority date: 2022-11-11
Filing date: 2023-10-31
Publication date: 2024-05-16

Abstract

An electrolytic capacitor 1 according to the present invention is provided with: a resin molded body 9 which is provided with a multilayer body 30 that comprises a capacitor element 20 and a sealing resin 8 that seals the periphery of the multilayer body; and a positive external electrode 11 and a negative external electrode 13, which are provided on outer surfaces 9a, 9b of the resin molded body 9. The capacitor element 20 comprises: a valve-acting metal substrate 4 which has a core part 4a and a porous part 4b that is formed along the surface of the core part, and an end of which is exposed in the outer surface 9a of the resin molded body 9; a dielectric layer 5 which is formed on the porous part 4b; a solid electrolyte layer 7a which is formed on the dielectric layer 5; and a conductive layer 7b which is formed on the solid electrolyte layer 7a. The negative external electrode 13 is electrically connected to the conductive layer 7b. The positive external electrode 11 comprises a first electrode layer 11a which is in direct contact with the core part 4a of the valve-acting metal substrate 4. The first electrode layer 11a contains flattened particles, each of which has an aspect ratio of 2 or more, and the major axis direction of which is along the outer surface 9a in a cross-section that contains the first electrode layer 11a, while being perpendicular to the main surface of the valve-acting metal substrate 4 and to the outer surface 9a, in which the valve-acting metal substrate 4 is exposed, among the outer surfaces of the resin molded body 9. The first electrode layer 11a contains a metal; and the ratio of the intensity of a peak associated with boric acid to the intensity of a peak associated with the metal in the Fourier transform infrared spectroscopy spectrum of the first electrode layer 11a as obtained by a diffuse reflection method is 5% or less.

Description

Electrolytic capacitor

The present invention relates to an electrolytic capacitor.

Patent Document 1 discloses a method for manufacturing an electronic component, which includes a step of preparing an electronic component body having an internal electrode exposed from its outer surface, and a first electrode layer forming step of forming a first electrode layer by injecting and colliding metal particles onto the outer surface of the electronic component body under conditions below atmospheric pressure.

International Publication No. 2022/168768

Patent document 1 claims to be able to provide a method for manufacturing electronic components that can suppress the occurrence of LC defects and has a simple manufacturing process.

However, there is room for improvement in terms of improving the film formation efficiency of the electrode layer when forming the electrode layer by spraying and colliding metal particles under conditions of less than atmospheric pressure.

The present invention has been made to solve the above problems, and aims to provide an electrolytic capacitor that can be manufactured efficiently.

The electrolytic capacitor of the present invention is an electrolytic capacitor comprising a resin molded body comprising a laminate including a capacitor element and a sealing resin that seals the periphery of the laminate, and an anode external electrode and a cathode external electrode provided on the outer surface of the resin molded body, wherein the capacitor element comprises a valve action metal base having a core portion and a porous portion formed along its surface, the end portion of which is exposed on the outer surface of the resin molded body, a dielectric layer formed on the porous portion, a solid electrolyte layer formed on the dielectric layer, and a conductive layer formed on the solid electrolyte layer, and the cathode external electrode is electrically connected to the conductive layer. The anode external electrode includes a first electrode layer that is in direct contact with the core of the valve metal base, and the first electrode layer is orthogonal to the outer surface of the resin molded body where the valve metal base is exposed and to the main surface of the valve metal base, and includes flat particles with an aspect ratio of 2 or more whose major axis direction is along the outer surface in a cross section including the first electrode layer, and the first electrode layer includes a metal, and in a Fourier transform infrared spectroscopy spectrum of the first electrode layer by a diffuse reflectance method, the ratio of the intensity of the peak derived from boric acid to the intensity of the peak derived from the metal is 5% or less. In this specification, the Fourier transform infrared spectroscopy spectrum by a diffuse reflectance method may be abbreviated as a diffuse reflectance FT-IR spectrum.

The present invention provides an electrolytic capacitor that can be manufactured efficiently.

FIG. 1 is a perspective view illustrating an example of an electrolytic capacitor according to the present invention. FIG. 2 is a cross-sectional view of the electrolytic capacitor shown in FIG. 1 taken along line AA. FIG. 3 is a cross-sectional view that typically shows the vicinity of the valve metal substrate on the first end surface of the resin molded body. FIG. 4 is an enlarged cross-sectional view showing a schematic view of a region surrounded by a dotted line in the first electrode layer shown in FIG. FIG. 5 is a cross-sectional view that illustrates the vicinity of the cathode lead layer on the second end surface of the resin molded body. FIG. 6 is a cross-sectional view illustrating a schematic diagram of another example of the electrolytic capacitor of the present invention. FIG. 7 is a cross-sectional view illustrating an example of a resin molded body. FIG. 8 is a schematic diagram showing a process of forming a first electrode layer by an aerosol deposition method. FIG. 9 shows the results of measuring the diffuse reflectance FT-IR spectrum of the first electrode layer of Example 1. FIG. 10 shows the results of measuring the diffuse reflectance FT-IR spectrum of the first electrode layer of Comparative Example 1. FIG. 11 shows the results of measuring the diffuse reflectance FT-IR spectrum of the first electrode layer of Comparative Example 2.

The electrolytic capacitor of the present invention will now be described.
However, the present invention is not limited to the following configurations, and can be modified as appropriate within the scope of the present invention. Note that the present invention also includes a combination of two or more of the preferred configurations of each embodiment of the present invention described below.

FIG. 1 is a perspective view illustrating an example of an electrolytic capacitor according to the present invention.
FIG. 1 shows a resin molded body 9 that constitutes the electrolytic capacitor 1 .
The shape of the resin molded body constituting the electrolytic capacitor of the present invention is not particularly limited, and any three-dimensional shape can be adopted. The shape of the resin molded body is preferably a rectangular parallelepiped. Moreover, the term "rectangular parallelepiped" does not mean that the resin molded body is a perfect rectangular parallelepiped, and the surface forming the resin molded body may be tapered and not perpendicular to other surfaces, and the corners may be chamfered.

FIG. 1 shows a rectangular parallelepiped resin molded body 9, which has a length direction (L direction), a width direction (W direction), and a thickness direction (T direction).
The resin molded body 9 has, as its outer surfaces, a first end face 9a and a second end face 9b facing each other in the longitudinal direction. An anode external electrode 11 is formed on the first end face 9a, and a cathode external electrode 13 is formed on the second end face 9b.
The resin molded body 9 has, as its outer surfaces, a bottom surface 9c and a top surface 9d which face each other in the thickness direction.
Further, the resin molded body 9 has, as its outer surfaces, a first side surface 9e and a second side surface 9f which face each other in the width direction.

In this specification, a surface extending along the length direction (L direction) and thickness direction (T direction) of an electrolytic capacitor or a resin molding is referred to as an LT surface, a surface extending along the length direction (L direction) and width direction (W direction) is referred to as an LW surface, and a surface extending along the width direction (W direction) and thickness direction (T direction) is referred to as a WT surface.
In the following description, the surface of the outer surface of the resin molded body on which the anode external electrode is provided will be referred to as a first end surface, and the surface on which the cathode external electrode is provided will be referred to as a second end surface. Note that the anode external electrode and the cathode external electrode may be provided on the same surface of the outer surface of the resin molded body.

FIG. 2 is a cross-sectional view of the electrolytic capacitor shown in FIG. 1 taken along line AA.
Capacitor element 20 includes an anode 3 having a dielectric layer 5 on its surface, and a cathode 7 facing anode 3 .
A plurality of capacitor elements 20 are stacked to form a laminate 30, and the periphery of the laminate 30 is sealed with a sealing resin 8 to form a resin molded body 9. In the laminate 30, the stacked capacitor elements 20 may be bonded to each other via a conductive adhesive (not shown). The laminate 30 may include only one capacitor element 20.
An external anode electrode 11 is formed on a first end surface 9a of the resin molded body 9, and the external anode electrode 11 is electrically connected to the anode 3 exposed from the first end surface 9a.
A cathode external electrode 13 is formed on the second end surface 9b of the resin molded body 9, and the cathode external electrode 13 is electrically connected to the cathode 7 exposed from the second end surface 9b. That is, the cathode external electrode 13 is also electrically connected to the conductive layer 7b.
The end of the valve metal base 4 constituting the capacitor element 20 on the side of the second end face 9b is sealed with a sealing resin 8, and the valve metal base 4 is not in direct contact with the solid electrolyte layer 7a or the conductive layer 7b. On the other hand, if the end of the valve metal base 4 on the side of the second end face 9b is covered with a dielectric layer 5 or otherwise insulated, the end of the valve metal base 4 on the side of the second end face 9b may be covered with the solid electrolyte layer 7a and the conductive layer 7b.

FIG. 3 is a cross-sectional view that typically shows the vicinity of the valve metal substrate on the first end surface of the resin molded body.
FIG. 3 is also a cross-sectional view that diagrammatically illustrates the area surrounded by the dotted line in the lower left portion of FIG.
The valve metal base 4 has a core 4a and a porous portion 4b formed along the surface of the core 4a. An end of the valve metal base 4 is exposed at a first end surface 9a of the resin molded body 9.
A dielectric layer 5 is formed on the surface of the porous portion 4b.

The valve metal constituting the valve metal substrate may be, for example, a single metal such as aluminum, tantalum, niobium, titanium, zirconium, magnesium, silicon, or an alloy containing these metals. Among these, aluminum or an aluminum alloy is preferred.

The shape of the valve metal substrate is not particularly limited, but is preferably a flat plate, more preferably a foil, and the porous portion is preferably an etching layer that has been etched with hydrochloric acid or the like.
The thickness of the valve metal base before etching is preferably 60 μm or more and 180 μm or less. Also, the thickness of the valve metal base (core portion) that is not etched after etching is preferably 10 μm or more and 70 μm or less. The thickness of the porous portion is designed according to the withstand voltage and electrostatic capacitance required for the electrolytic capacitor, and the combined thickness of the porous portions on both sides of the valve metal base is preferably 10 μm or more and 120 μm or less.

The dielectric layer is preferably made of an oxide film of the valve metal. For example, when an aluminum foil is used as the valve metal substrate, an oxide film serving as the dielectric layer can be formed by anodizing in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or a sodium salt or ammonium salt thereof.
The dielectric layer is formed along the surface of the porous portion to form pores (recesses). The thickness of the dielectric layer is designed according to the withstand voltage and capacitance required for the electrolytic capacitor, but is preferably 3 nm or more and 200 nm or less.

The anode external electrode 11 is provided on a first end surface 9 a of the resin molded body 9 .
The anode external electrode 11 includes a first electrode layer 11 a in direct contact with the core portion 4 a of the valve metal substrate 4 .
The first electrode layer 11a is orthogonal to the first end face 9a of the resin molded body 9 and the main surface of the valve metal base 4, and contains flat particles with an aspect ratio of 2 or more whose major axis direction is along the first end face 9a of the resin molded body 9 in a cross section including the first electrode layer 11a. That is, the metal particles constituting the first electrode layer contain flat particles.
This will be described with reference to the drawings.

FIG. 4 is an enlarged cross-sectional view showing a schematic view of a region surrounded by a dotted line in the first electrode layer shown in FIG.
The cross section shown in Figure 4 is perpendicular to the first end face 9a of the resin molding 9 and the main surface of the valve metal base 4, and includes the first electrode layer 11a, and is a cross section cut along the LT plane also shown in Figure 2.
This figure is a schematic diagram showing an image of a cross section including the first electrode layer taken by an electron microscope.
The first electrode layer 11a is an electrode layer in which a plurality of particles are laminated, and the first electrode layer 11a includes flat particles 15 having an aspect ratio of 2 or more.
The flat particle 15 is a particle whose major axis direction is along the first end surface 9 a of the resin molded body 9 .
The shape of the flat particles includes plate-like, strip-like, rod-like, etc. In other words, regardless of the shape, it is sufficient that the shape meets the above definition.

The aspect ratio of the particles contained in the first electrode layer is determined as follows. First, for each particle, the longest dimension is taken in the direction along the first end face of the resin molded body. Here, "the direction along the first end face of the resin molded body" does not mean a direction completely parallel to the first end face of the resin molded body, but means that a direction inclined from a direction parallel to the first end face of the resin molded body is also allowed. For example, it may be inclined at about 45° from the first end face, and it is sufficient that the direction is generally along the first end face when viewed macroscopically.
The longest dimension in this direction is taken as the dimension of the particle in the major axis direction (the dimension indicated by the double-headed arrow La in FIG. 4).The longest dimension in the direction perpendicular to the major axis is taken as the dimension of the particle in the minor axis direction (the dimension indicated by the double-headed arrow Lb in FIG. 4).
The aspect ratio is calculated by the ratio of the major axis dimension to the minor axis dimension. If the major axis dimension is twice or more the minor axis dimension, the particle is recognized as a flat particle with an aspect ratio of 2 or more.
In addition, when the particle has a bow-shaped shape, the major axis is not a straight line, but is defined as the longest line passing only through the particle. When the particle has a bow-shaped shape, the major axis is the line along the bow shape. In Figure 4, the major axis along the bow shape is shown as Lc.

In a first electrode layer in which there are flat particles with an aspect ratio of 2 or more whose long axis direction is along the first end face of the resin molded body, the flat particles are stacked from the first end face of the resin molded body to form the first electrode layer. In a first electrode layer of this shape, the contact area between the particles constituting the first electrode layer is larger than in a form in which spherical particles are stacked, so the bond strength between the particles is stronger. In addition, the contact area between the core of the valve metal base, which is the electrode exposed portion of the internal electrode, and the flat particles is also larger, so the bond strength between the core of the valve metal base and the first electrode layer is also stronger. Therefore, when the connection strength between the electrode exposed portion of the internal electrode and the first electrode layer is high and a second electrode layer is formed on the first electrode layer to form an anode external electrode, the anchor effect of the first electrode layer is large, resulting in an electrolytic capacitor with high adhesion between the electrode exposed portion of the internal electrode and the external electrode.

The particles constituting the first electrode layer do not all need to be flat particles. The particles constituting the first electrode layer may contain both flat particles and non-flat particles. Figure 4 also shows a schematic diagram of a particle 16 that is not a flat particle.
In this case, the first electrode layer preferably contains 30% or more flat particles by number. When the first electrode layer contains 30% or more flat particles by number, the adhesive strength between the electrode exposed portion of the internal electrode and the external electrode can be further increased.
The proportion of flat particles contained in the first electrode layer can be calculated by determining the outline of the particles contained within a specified observation area in the first electrode layer as shown in Figure 4, classifying each particle into flat particles and non-flat particles, and determining the proportion of flat particles to all particles.

The major axis dimension (average dimension) of the flat particles contained in the first electrode layer may be 0.3 μm or more, or 1.0 μm or more. The upper limit of the major axis dimension (average dimension) of the flat particles may be 5.0 μm.
The aspect ratio (average value) of the flat particles is preferably 2 or more and 10 or less.
These dimensions and aspect ratios can be calculated by extracting only the flat particles present within the observation area and averaging the dimensions in the major axis direction and the minor axis direction of each flat particle.
It is preferable to use 30 or more flat particles to obtain these average values.

The first electrode layer contains a metal. The first electrode layer preferably contains at least one type selected from the group consisting of Cu, Ni, and Cu-Ni alloys, and more preferably contains Cu. The particles contained in the first electrode layer are preferably at least one type of particles selected from the group consisting of Cu, Ni, and Cu-Ni alloys, and more preferably Cu particles. In addition, the flat particles contained in the first electrode layer are preferably at least one type of particles selected from the group consisting of Cu, Ni, and Cu-Ni alloys, and more preferably Cu particles.

The first electrode layer is preferably an electrode layer formed by an aerosol deposition method or a gas deposition method. In particular, it is preferably an electrode layer formed by an aerosol deposition method. In the aerosol deposition method, metal particles are aerosolized and collided with the first end surface of the resin molded body.

In the past, when using fine particles of Cu or fine particles of an alloy containing Cu in the aerosol deposition method, the fine particles were coated with boric acid on the surface to prevent oxidation. In this case, components derived from boric acid were also included in the electrode layer formed by the aerosol deposition method. However, in the electrode layer formed in this way, boron compounds derived from boric acid were interposed between the metal fine particles, and the metal fine particles did not stack up well. As a result, the film formation efficiency in the electrode layer formation process was low, leaving room for improvement.

In the electrolytic capacitor of the present invention, the ratio of the intensity of the peak derived from boric acid to the intensity of the peak derived from the metal in the diffuse reflectance FT-IR spectrum of the first electrode layer is 5% or less. This makes it possible to prevent the boron compound from being present between the metal fine particles when the first electrode layer is formed, which makes it easier for the metal fine particles to pile up when the first electrode layer is formed by the aerosol deposition method, thereby improving the film formation efficiency of the first electrode layer.
In addition, since the presence of compounds derived from boric acid between the metal fine particles can be suppressed in the formed first electrode layer, the bonding strength between the core of the valve metal base and the first electrode layer is also increased. Therefore, since the connection strength between the electrode exposed portion of the internal electrode and the first electrode layer is increased, when the second electrode layer is formed on the first electrode layer to serve as the anode external electrode, the anchor effect of the first electrode layer is increased, resulting in an electrolytic capacitor with high adhesion between the electrode exposed portion of the internal electrode and the external electrode.

In the electrolytic capacitor of the present invention, the ratio of the intensity of the peak derived from boric acid to the intensity of the peak derived from the metal in the diffuse reflectance FT-IR spectrum of the first electrode layer is preferably 3% or less, and more preferably 1% or less.

In the diffuse reflectance FT-IR spectrum, a peak derived from Cu appears near 1100 cm ⁻¹ , that is, from 1050 cm ⁻¹ to 1150 cm ⁻¹ .
The peak derived from boric acid appears near 1400 cm ^-1 , that is, from 1350 cm ^-1 to 1500 cm ^-1 .

The intensity of the peak derived from the metal is determined by the maximum absorbance value of the peak derived from the metal (see the double-headed arrow A in FIGS. 10 and 11, which will be described later).
The intensity of the peak derived from boric acid is calculated by the following method. First, two points on the rising edge of the peak are connected by a straight line to form a baseline. In the description of the present invention, the baseline is set visually, but for example, a measuring device may calculate two points on the rising edge of the peak approximately and automatically connect them by a straight line. The point at which the height from the baseline is maximum is set as the apex of the peak, and the height from the baseline at the apex of the peak (absorbance at the apex of the peak - absorbance at the baseline) is calculated to form the intensity of the peak derived from boric acid (see double-headed arrow B in Figures 10 and 11 described later).

By performing the aerosol deposition method using metal particles that do not contain boric acid but contain Cu, the ratio of the intensity of the peak derived from boric acid to the intensity of the peak derived from the metal in the diffuse reflectance FT-IR spectrum of the first electrode layer can be made 5% or less, which is preferable.

Metal microparticles that do not contain boric acid but contain Cu can be obtained by forming metal microparticles using the atomization method (gas phase method) without using an antioxidant.

The intensity of the peak derived from boric acid in the diffuse reflectance FT-IR spectrum of the first electrode layer is preferably below the detection limit. In this case, the first electrode layer contains very little boron compounds or does not contain any boron compounds. This can further improve the film formation efficiency of the first electrode layer.

Whether the first electrode layer contains components derived from boric acid can also be confirmed by observing a cross section of the first electrode layer with a scanning electron microscope - energy dispersive X-ray spectroscopy (SEM-EDX). If the cross section of the first electrode layer is subjected to elemental analysis with SEM-EDX and boron is not confirmed, it can be considered that the first electrode layer does not contain components derived from boric acid.

In the diffuse reflectance T-IR spectrum of the first electrode layer, it is preferable that the ratio of the intensity of the highest peak among the peaks at 2800 cm ⁻¹ or more and 3000 cm ⁻¹ or less due to C—H bonds to the intensity of the peak attributable to the metal is 0.5% or less.
In the diffuse reflectance FT-IR spectrum of the first electrode layer, the ratio of the intensity of the highest peak among the peaks at 2800 cm ^or more and 3000 ^cm or less derived from C—H bonds to the intensity of the peak derived from the metal is more preferably 0.3% or less, and even more preferably 0.1% or less.

The peak at 2800 cm ⁻¹ or more and 3000 cm ⁻¹ or less derived from a C—H bond is preferably a peak derived from an organic acid.

When Cu-containing metal particles are used in the aerosol deposition method, metal particles containing an organic acid as an antioxidant are often used. Therefore, when a peak is observed between ²⁸⁰⁰ cm and ^{3000 cm} , the peak is considered to be derived from the organic acid.

The intensity of the peak derived from the C-H bond is calculated as follows. First, the two points at the beginning of the peak are connected by a straight line to form the baseline. In the explanation of the present invention, the baseline is set visually, but for example, the measuring device may calculate the two points at the beginning of the peak approximately and automatically connect them with a straight line. The point at which the height from the baseline is maximum is set as the apex of the peak, and the height from the baseline at this apex of the peak (absorbance at the apex of the peak - absorbance at the baseline) is calculated to form the intensity of the peak derived from the C-H bond (see double-headed arrow C in Figure 11 described later).

When the ratio of the intensity of the highest peak among the peaks at 2800 cm ^-1 or more and 3000 cm ^-1 or less derived from C-H bonds to the intensity of the peak derived from the metal in the diffuse reflectance FT-IR spectrum of the first electrode layer is 0.5% or less, it is possible to suppress the presence of compounds derived from organic acids between metal fine particles when forming the first electrode layer by the aerosol deposition method, thereby improving the film formation efficiency of the first electrode layer.

Examples of organic acids include stearic acid, phosphoric acid compounds, etc. In addition, the compound from which the C-H bond is derived may be something other than an organic acid.

By performing the aerosol deposition method using metal fine particles containing Cu without containing an organic acid, the ratio of the intensity of the highest peak among the peaks at 2800 cm ^-1 or more and 3000 cm ^-1 or less derived from C-H bonds to the intensity of the peak derived from the metal in the diffuse reflectance FT-IR spectrum of the first electrode layer can be made to be 0.5% or less, which is preferable.

Metal microparticles that do not contain organic acids and contain Cu can be obtained by forming metal microparticles using the atomization method without using an antioxidant.

In the diffuse reflectance FT-IR spectrum of the first electrode layer, the intensity of a peak at 2800 cm ^-1 or more and 3000 cm ^-1 or less derived from a C-H bond is preferably below the detection limit. In this case, the first electrode layer contains an extremely small amount of organic acid or does not contain any organic acid. Therefore, the film formation efficiency of the first electrode layer can be further improved.

　A Kubelka-Munk transformation may be performed on the diffuse reflectance FT-IR spectrum. This can reduce the effects of the background.

The thickness of the first electrode layer formed on the core of the valve metal base is preferably 0.2 μm or more and 30 μm or less.
The thickness of the first electrode layer formed on the core of the valve metal base is defined as the thickness of the first electrode layer formed on the core. In Fig. 3, the thickness of the first electrode layer 11a formed on the core 4a of the valve metal base 4 is indicated by a double-headed arrow _T1 .
When the thickness of the first electrode layer is within the above range, the ESR (equivalent series resistance) can be reduced, and the adhesion between the first electrode layer and the second electrode layer formed thereon can be increased.

In a cross section including the first electrode layer, which is perpendicular to the outer surface of the resin molded body where the valve metal base is exposed (the first end face of the resin molded body) and the main surface of the valve metal base, the cross section of the first electrode layer is preferably wedge-shaped. Fig. 3 shows a cross section of the first electrode layer 11a that is wedge-shaped.
When the first electrode layer has a wedge-shaped cross section, the adhesive strength with the second electrode layer formed on the first electrode layer is improved due to the anchor effect, thereby improving the terminal fixing strength.
In this specification, the wedge shape means a shape having a bottom that contacts the valve metal base in the above-mentioned cross-sectional shape, and a width perpendicular to the direction away from the bottom (height direction) that gradually narrows. The shape of the top of the wedge is not particularly limited, and may be pointed, rounded, or flat. In addition, the top of the wedge may appear roughly smooth, but may have irregularities when viewed microscopically.

As shown in FIG. 3, the first electrode layer 11a may be in contact with the sealing resin 8.

It is preferable that the anode external electrode 11 further includes a second electrode layer 11b formed on the first electrode layer 11a.
The second electrode layer 11b is preferably a conductive resin electrode layer containing a conductive component and a resin component.
The conductive component preferably contains Ag, Cu, Ni, Sn or the like as a main component, and the resin component preferably contains epoxy resin, phenol resin or the like as a main component.
In particular, it is preferable that the second electrode layer is a conductive resin electrode layer containing Ag. When the second electrode layer is a conductive resin electrode layer containing Ag, the specific resistance of Ag is small, and therefore the ESR can be reduced.

Moreover, the second electrode layer is preferably a printed resin electrode layer formed by screen printing an electrode paste.
When the second electrode layer is a printed resin electrode layer, the external electrodes can be made flatter than when an electrode paste is formed by dipping, that is, the film thickness uniformity of the external electrodes is improved.

The electrode paste may contain an organic solvent, and as the organic solvent, it is preferable to use a glycol ether-based solvent, such as diethylene glycol monobutyl ether or diethylene glycol monophenyl ether.
If necessary, an additive may be used. The additive is useful for adjusting the rheology of the electrode paste, particularly the thixotropy. The content of the additive is preferably less than 5% by weight based on the weight of the electrode paste.

An outer plating layer may be provided on the surface of the second electrode layer 11b. Fig. 2 shows a third electrode layer 11c which is an outer plating layer provided on the surface of the second electrode layer 11b.
The third electrode layer is preferably a Ni-plated layer or a Sn-plated layer.
When the third electrode layer is two layers, the third electrode layer may have a first outer layer plating layer formed on the surface of the second electrode layer, and a second outer layer plating layer formed on the surface of the first outer layer plating layer.
The first outer plating layer is preferably a Ni plating layer, and the second outer plating layer is preferably a Sn plating layer.

So far, we have explained the configuration related to the anode 3. Next, we will explain the configuration related to the cathode 7 and other components that make up the resin molded body with reference to Figure 2.

The cathode 7 constituting the capacitor element 20 is formed by laminating a solid electrolyte layer 7a formed on the dielectric layer 5, a conductive layer 7b formed on the solid electrolyte layer 7a, and a cathode extraction layer 7c formed on the conductive layer 7b.
An electrolytic capacitor in which a solid electrolyte layer is provided as part of the cathode can be said to be a solid electrolytic capacitor.

Materials constituting the solid electrolyte layer include, for example, conductive polymers with a skeleton of pyrroles, thiophenes, anilines, etc. An example of a conductive polymer with a skeleton of thiophenes is PEDOT [poly(3,4-ethylenedioxythiophene)], which may be composited with polystyrene sulfonic acid (PSS) as a dopant to form PEDOT:PSS.

The solid electrolyte layer is formed, for example, by a method of forming a polymerized film of poly(3,4-ethylenedioxythiophene) or the like on the surface of the dielectric layer using a treatment liquid containing a monomer such as 3,4-ethylenedioxythiophene, or a method of applying a dispersion of a polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the dielectric layer and drying it, etc. It is preferable to form a solid electrolyte layer for an outer layer that covers the entire dielectric layer after forming a solid electrolyte layer for an inner layer that fills the pores (recesses).
The solid electrolyte layer can be formed in a predetermined region by applying the above-mentioned treatment liquid or dispersion onto the dielectric layer by sponge transfer, screen printing, spray application, dispenser, inkjet printing, etc. The thickness of the solid electrolyte layer is preferably 2 μm or more and 20 μm or less.

The conductive layer is provided to electrically and mechanically connect the solid electrolyte layer and the cathode lead layer. For example, it is preferably a carbon layer, a graphene layer, a silver layer, a copper layer, a nickel layer, or the like, formed by applying a conductive paste such as carbon paste, graphene paste, silver paste, copper paste, nickel paste, or the like. It may also be a composite layer in which a silver layer, copper layer, or nickel layer is provided on a carbon layer or graphene layer, or a mixed layer formed by applying a mixed paste in which a carbon paste or graphene paste is mixed with a silver paste, copper paste, or nickel paste.

The conductive layer can be formed by applying a conductive paste such as carbon paste onto the solid electrolyte layer by sponge transfer, screen printing, spray coating, dispenser, inkjet printing, or the like. It is preferable to laminate the cathode lead layer in the next process while the conductive layer is still in a viscous state before drying. The thickness of the conductive layer is preferably 2 μm or more and 20 μm or less.

The cathode extraction layer can be formed of a metal foil.
In the case of a metal foil, it is preferable that the metal foil is made of at least one metal selected from the group consisting of Al, Cu, Ag, and alloys mainly composed of these metals. When the metal foil is made of the above metal, the resistance value of the metal foil can be reduced, and the ESR can be reduced.
In addition, the metal foil may be a metal foil whose surface is coated with carbon or titanium by a film forming method such as sputtering or vapor deposition. It is more preferable to use a carbon-coated Al foil. The thickness of the metal foil is not particularly limited, but from the viewpoints of handling in the manufacturing process, miniaturization, and reducing ESR, it is preferably 20 μm or more and preferably 50 μm or less.

FIG. 5 is a cross-sectional view that illustrates the vicinity of the cathode lead layer on the second end surface of the resin molded body.
FIG. 5 is also a cross-sectional view that diagrammatically illustrates the area surrounded by the dotted line in the lower right portion of FIG.
Cathode lead layer 7 c which is a metal foil is exposed at second end surface 9 b of resin molded body 9 .

The cathode external electrode 13 is provided on the second end surface 9 b which is the outer surface of the resin molded body 9 .
The cathode external electrode 13 may include a first electrode layer 13a in direct contact with the cathode lead layer 7c. The first electrode layer 13a may have a configuration similar to that of the first electrode layer 11a formed on the first end surface 9a of the resin molded body 9.
In a cross section including the first electrode layer, which is perpendicular to an outer surface of the resin molded body where the cathode extraction layer is exposed (a second end face of the resin molded body) and to a main surface of the cathode extraction layer, the cross section of the first electrode layer is preferably wedge-shaped. Fig. 5 shows a cross section of first electrode layer 13a that is wedge-shaped.

When observing an enlarged cross-sectional view of the first electrode layer 13a as in Figure 4, it is preferable that the first electrode layer contains flat particles with an aspect ratio of 2 or more whose major axis direction is along the second end face of the resin molding, which is the outer surface of the resin molding.
Moreover, the first electrode layer 13a preferably contains Cu.
In addition, in the diffuse reflectance FT-IR spectrum of the first electrode layer 13a, the ratio of the intensity of the peak derived from boric acid to the intensity of the peak derived from the metal is preferably 5% or less.

Similar to the anode external electrode 11, the cathode external electrode 13 may include a second electrode layer 13b formed on a first electrode layer 13a, and may also include a third electrode layer 13c.
The second electrode layer 13b and the third electrode layer 13c may have the same configuration as the second electrode layer 11b and the third electrode layer 11c in the anode external electrode 11.

The sealing resin 8 constituting the resin molded body 9 includes at least a resin, and preferably includes a resin and a filler. As the resin, it is preferable to use an insulating resin such as an epoxy resin, a phenol resin, a polyimide resin, a silicone resin, a polyamide resin, or a liquid crystal polymer. The resin molded body 9 may be composed of two or more types of insulating resin. The sealing resin 8 may be in the form of either a solid resin or a liquid resin. As the filler, it is preferable to use inorganic particles such as silica particles, alumina particles, or metal particles. It is more preferable to use a material containing silica particles in a solid epoxy resin and a phenol resin.
As a molding method of the resin molded body, when a solid sealing material is used, it is preferable to use a resin mold such as a compression mold or a transfer mold, and it is more preferable to use a compression mold. When a liquid sealing material is used, it is preferable to use a molding method such as a dispensing method or a printing method. It is preferable to seal a laminate 30 of a capacitor element 20 consisting of an anode 3, a dielectric layer 5, and a cathode 7 with a sealing resin 8 by compression molding to form a resin molded body 9.

FIG. 6 is a cross-sectional view illustrating a schematic diagram of another example of the electrolytic capacitor of the present invention.
In the electrolytic capacitor 2 shown in FIG. 6, a cathode lead layer 7c and a cathode lead portion 7d are formed from an electrode paste, not from a metal foil.
In this case, the cathode lead layer can be formed in a predetermined region by applying the electrode paste onto the conductive layer by sponge transfer, screen printing, spray application, dispenser, inkjet printing, etc. As the electrode paste, an electrode paste containing Ag, Cu, or Ni as a main component is preferable. When the cathode lead layer is formed by the electrode paste, the thickness of the cathode lead layer can be made thinner than when a metal foil is used, and in the case of screen printing, the thickness can be made 2 μm or more and 20 μm or less.

When the cathode lead layer 7c and the cathode lead portion 7d are formed using electrode paste, the second electrode layer 13b can be formed by screen printing the electrode paste without providing a first electrode layer on the cathode side.

Cathode lead layers 7c of each capacitor element 20 are gathered together in the vicinity of second end face 9b as cathode lead portion 7d and exposed at second end face 9b.
Cathode lead portion 7d may be formed from the same electrode paste as cathode lead layer 7c, or the electrode pastes constituting cathode lead portion 7d and cathode lead layer 7c may have different compositions.
When cathode lead layer 7c and cathode lead portion 7d are formed from electrode paste, the adhesion to second electrode layer 13b formed by screen printing of the electrode paste is good.

Although not shown in FIG. 6, an insulating mask may be provided on the anode side. In that case, the insulating mask may be provided on the surface of the dielectric layer.

In another example of the electrolytic capacitor of the present invention shown in FIG. 6, the aforementioned treatment liquid or dispersion liquid may be applied to the dielectric layer by dipping, thereby forming a solid electrolyte layer in a predetermined area. Similarly, a conductive paste such as carbon paste may be applied to the solid electrolyte layer by dipping, thereby forming a conductive layer.

Next, an example of a method for producing the electrolytic capacitor of the present invention will be described.
When manufacturing the electrolytic capacitor of the present invention, it is preferable to form the first electrode layer on the outer surface of the resin molded body by an aerosol deposition method, a gas deposition method, etc. In particular, it is preferable to form the first electrode layer on the outer surface of the resin molded body by an aerosol deposition method.
Hereinafter, a method for manufacturing an electrolytic capacitor will be described, which includes a step of forming a first electrode layer on a first end face, which is an outer surface of a resin molded body, by an aerosol deposition method. The step of forming the first electrode layer will be referred to as a first electrode layer forming step.

First, a resin molded body is prepared in which the valve metal substrate is exposed from a first end surface.
FIG. 7 is a cross-sectional view illustrating an example of a resin molded body.
In the first electrode layer forming step, metal fine particles are sprayed onto the first end face of the resin molded body under a pressure less than atmospheric pressure, and are caused to collide with the first end face to form the first electrode layer.
By forming the first electrode layer by this process, the external electrodes can be formed without using a plating process that is prone to causing corrosion of the internal electrodes, thereby making it possible to suppress leakage current (LC) defects caused by plating solutions.

FIG. 8 is a schematic diagram showing a process of forming a first electrode layer by an aerosol deposition method.
8 shows an aerosol deposition apparatus 51. The aerosol deposition apparatus 51 has a cylinder containing a carrier gas 52, an aerosol generator 54 into which the carrier gas 52 and metal fine particles 53 are introduced to generate an aerosol, a chamber 55 into which the aerosol is introduced, and a stage 57 on which the resin molded bodies 9 are fixed and arranged with their first end faces 9a facing up.
In the aerosol deposition method, metal particles 53 are sprayed from a nozzle 56 provided at the tip of an aerosol generator 54 and collide with the first end surface 9a of the resin molded body 9 to form the first electrode layer.

In the aerosol deposition method, aerosolized metal particles are collided with the first end face of the resin molded body. When a metal particle collides with another metal particle, the metal particle crushes the metal particle. When the metal particles collide repeatedly, the particles stretch and spread in the direction along the first end face of the resin molded body. As a result, the shape of the metal particle becomes flattened.

In addition, by forming the first electrode layer by the aerosol deposition method, the thickness of the first electrode layer can be reduced and the adhesion between the resin molded body and the first electrode layer can be strengthened.

As the metal microparticles, it is preferable to use at least one type of metal microparticle selected from the group consisting of Cu, Ni, and Cu-Ni alloys, it is more preferable to use metal microparticles containing Cu, and it is even more preferable to use metal microparticles of Cu.

The metal particles used do not contain boric acid. This prevents boron compounds from being present between the metal particles when forming the first electrode layer, which makes it easier for the metal particles to pile up when forming the first electrode layer by the aerosol deposition method, improving the film formation efficiency of the first electrode layer.

As the metal fine particles, it is preferable to use metal fine particles that do not contain organic acids. In this case, when forming the first electrode layer, it is possible to prevent compounds derived from organic acids from being present between the metal fine particles. This makes it easier for the metal fine particles to pile up when forming the first electrode layer by the aerosol deposition method, thereby improving the film formation efficiency of the first electrode layer.

The first electrode layer formation process is carried out under conditions of less than atmospheric pressure. The pressure inside the chamber can be made less than atmospheric pressure by evacuating the chamber. It is preferable to set the pressure inside the chamber to 10 Pa or more and 1000 Pa or less. The pressure inside the chamber can be adjusted by increasing or decreasing the gas flow rate. If the gas flow rate is increased so that the pressure inside the chamber is, for example, 100 Pa or more, the film formation speed can be increased, and as a result, the film formation cost can be reduced.

The first electrode layer forming step is preferably carried out at 100° C. or less, and more preferably at room temperature. Since it is not necessary to raise the temperature, damage to the resin molded body can be reduced, and by carrying out the step at room temperature, the equipment can be simplified.
The normal temperature may be the temperature of the working environment, and may be, for example, 10°C or higher and 30°C or lower.
The ratio of flat particles having an aspect ratio of 2 or more contained in the first electrode layer can be adjusted by changing the particle size of the metal microparticles, the nozzle scanning speed, and the amount of metal microparticles ejected per unit time. The aspect ratio can also be controlled by the time for which the metal microparticles are ejected. The aspect ratio can be increased by extending the ejection time, i.e., by ejecting repeatedly or for a long period of time.

From the viewpoint of facilitating the formation of flat particles or improving the efficiency of film formation, the particle size of the metal fine particles is preferably D50 less than 5 μm, more preferably D50 less than 3 μm, and even more preferably D50 2 μm or less. Also, D50 may be 0.5 μm or more.
D50 of the metal particles is the median diameter based on volume distribution measured by a laser diffraction/scattering method.
As an apparatus for measuring D50 of metal particles, for example, MT3300 manufactured by Microtrac Bell Co., Ltd. can be used.

After the first electrode layer is formed, a second electrode layer forming step may be performed in which a second electrode layer containing a conductive component and a resin component is formed on the first electrode layer.
In the second electrode layer forming step, it is preferable to form a printed resin electrode layer as the second electrode layer by screen printing an electrode paste.
When the second electrode layer is formed by screen printing of the electrode paste, the external electrodes can be made flatter than when the electrode paste is formed by dipping, that is, the film thickness uniformity of the external electrodes is improved.

After forming the second electrode layer, a third electrode layer formation process may be performed in which a third electrode layer is formed on the second electrode layer by plating.

Alternatively, a third electrode layer forming step may be performed in which a third electrode layer is formed by plating on the first electrode layer without forming the second electrode layer.
If the first electrode layer is formed in advance on the resin molded body, LC defects are less likely to occur even if the third electrode layer is subsequently formed by plating.

The second end surface of the resin molded body may also be subjected to the first electrode layer forming step in the same manner as the first end surface of the resin molded body, to form a first electrode layer on the second end surface.
By this process, a first electrode layer 13a as shown in FIG. 5 can be formed on the second end surface 9b of the resin molded body.
Thereafter, the second electrode layer 13b and the third electrode layer 13c can be formed in the same manner as on the first end surface side of the resin molded body.
In particular, when the cathode lead layer is a metal foil, providing the first electrode layer in the first electrode layer forming step is effective because it can improve the adhesive strength between the metal foil and the first electrode layer.

Below, examples are presented that evaluate the film formation efficiency of the first electrode layer for the electrolytic capacitor of the present invention. Note that the present invention is not limited to these examples.

Example 1
The laminate having the structure shown in FIG. 1 and FIG. 2 was sealed with a sealing resin containing an epoxy resin and silica particles to obtain a resin molded body.
A first electrode layer having a predetermined thickness was formed on a first end surface of the resin molded body by an aerosol deposition method (AD method). Cu fine particles not containing an antioxidant were used as the metal fine particles. The Cu fine particles not containing an antioxidant were obtained by preparing Cu fine particles by an atomization method without adding an antioxidant such as boric acid or an organic acid.
As the metal fine particles, Cu fine particles having a D50 of 1 μm were used.
A first electrode layer was formed on a second end surface of the resin molded body in the same manner as on the first end surface.

　Then, an electrode paste containing Ag was applied by screen printing to the end faces (first end face and second end face) of the resin molded body, and the second electrode layer was formed by thermal curing. Furthermore, a third electrode layer, a Ni plating layer and a Sn plating layer, was formed on the surface of the second electrode layer to produce an electrolytic capacitor.

Example 2
An electrolytic capacitor was produced in the same manner as in Example 1, except that metal fine particles containing an organic acid, not containing boric acid, were used as the metal fine particles. At this time, the number of coatings in the AD method was adjusted so that the thickness of the first electrode layer in Example 2 was the same as that of the first electrode layer in Example 1. The metal fine particles used in Example 2 were obtained by adding stearic acid as an organic acid, without adding boric acid, when producing Cu fine particles by the atomization method.

(Comparative Example 1)
An electrolytic capacitor was produced in the same manner as in Example 1, except that metal fine particles containing boric acid but not organic acid were used as the metal fine particles. At this time, the number of coatings in the AD method was adjusted so that the thickness of the first electrode layer in Comparative Example 1 was the same as that of the first electrode layer in Example 1. The metal fine particles used in Comparative Example 1 are obtained by adding boric acid without adding an organic acid when producing Cu fine particles by an atomization method.

(Comparative Example 2)
An electrolytic capacitor was produced in the same manner as in Example 1, except that metal fine particles containing boric acid and an organic acid were used as the metal fine particles. At this time, the number of coatings in the AD method was adjusted so that the thickness of the first electrode layer in Comparative Example 2 was the same as that of the first electrode layer in Example 1. The metal fine particles used in Comparative Example 2 were obtained by adding boric acid when producing Cu fine particles by the atomization method, and further adding stearic acid as an organic acid.

[Diffuse Reflectance FT-IR Spectroscopic Analysis]
In the electrolytic capacitors of Examples 1 and 2 and Comparative Examples 1 and 2, the diffuse reflectance FT-IR spectrum of the first electrode layer was measured.

FIG. 9 shows the results of measuring the diffuse reflectance FT-IR spectrum of the first electrode layer of Example 1.
FIG. 10 shows the results of measuring the diffuse reflectance FT-IR spectrum of the first electrode layer of Comparative Example 1.
FIG. 11 shows the results of measuring the diffuse reflectance FT-IR spectrum of the first electrode layer of Comparative Example 2.

9, in Example 1, a peak derived from a metal was observed near 1100 cm ⁻¹ . On the other hand, a peak derived from boric acid and a peak derived from a C—H bond were not observed. This can also be said to mean that the peak derived from boric acid and the peak derived from a C—H bond were below the detection limit.

Although the results of the diffuse reflectance FT-IR spectrum are not shown in the figures, in Example 2, the ratio of the intensity of the highest peak among the peaks attributable to C—H bonds between 2800 cm ⁻¹ and 3000 cm ⁻¹ to the intensity of the peak attributable to the metal was 2.4%.

10, in Comparative Example 1, a peak derived from a metal was observed near 1100 cm ⁻¹ . Also, a peak derived from boric acid was observed near 1400 cm ⁻¹ . On the other hand, no peak derived from a C—H bond was observed.
10, the intensity of the peak derived from the metal is indicated by a double-headed arrow A. The maximum absorbance value of the peak derived from the metal was used as the intensity of the peak derived from the metal.
In Fig. 10, the peak derived from boric acid is indicated by a double-headed arrow B. The intensity of the peak derived from boric acid was calculated by the following method. First, two points at the rise of the peak were connected by a straight line to form a baseline. The point at which the height from this baseline was maximum was defined as the apex of the peak, and the height from the baseline at the apex of the peak (absorbance at the apex of the peak - absorbance at the baseline) was calculated to be the intensity of the peak derived from boric acid.

In Comparative Example 1, the ratio of the intensity of the peak derived from boric acid to the intensity of the peak derived from the metal was 33%.

11, in Comparative Example 2, a peak derived from a metal was observed near 1100 cm ⁻¹ . In addition, a peak derived from boric acid was observed near 1400 cm ⁻¹ . In addition, a peak derived from a C—H bond was observed from 2800 cm ⁻¹ to 3000 cm ⁻¹ .
11, the intensity of the peak derived from the metal is indicated by a double-headed arrow A. The maximum absorbance value of the peak derived from the metal was used as the intensity of the peak derived from the metal.
11, the intensity of the peak derived from boric acid is indicated by a double-headed arrow B. The intensity of the peak derived from boric acid was calculated in the same manner as in Comparative Example 1.
In Fig. 11, the intensity of the highest peak among the peaks derived from C-H bonds between 2800 cm ^-1 and 3000 cm ^-1 is indicated by a double-headed arrow C. The intensity of the peak derived from C-H bonds was calculated by the following method. First, two points at the rise of the peak were connected by a straight line to form a baseline. The point at which the height from this baseline was maximum was defined as the apex of the peak, and the height from the baseline at this apex of the peak (absorbance at the apex of the peak - absorbance at the baseline) was calculated to be the intensity of the peak derived from C-H bonds.

In Comparative Example 2, the ratio of the intensity of the peak derived from boric acid to the intensity of the peak derived from the metal was 34%.
In Comparative Example 2, the ratio of the intensity of the highest peak among the peaks at 2800 cm ^-1 or more and 3000 cm ^-1 or less derived from C--H bonds to the intensity of the peak derived from the metal was 2.4%.

[Deposition efficiency of first electrode layer]
In Examples 1 and 2 and Comparative Examples 1 and 2, the number of coatings in the AD method when forming a first electrode layer of a predetermined thickness was measured, and the film-forming efficiency of the first electrode layer was calculated by taking the reciprocal of the number of coatings. The results are shown in Table 1. The film-forming efficiency of the first electrode layer is shown as a relative value when the film-forming efficiency in Comparative Example 2 is set to 1.

As shown in Table 1, Examples 1 and 2, in which the first electrode layer does not contain components derived from boric acid, had a superior film-forming efficiency for the first electrode layer compared to Comparative Examples 1 and 2. Furthermore, Example 1, in which the first electrode layer does not contain components derived from organic acid, had an even superior film-forming efficiency for the first electrode layer compared to Example 2.

The following items are disclosed in this specification:

＜1＞
a resin molded body including a laminate including a capacitor element and a sealing resin that seals the periphery of the laminate;
an electrolytic capacitor comprising an anode external electrode and a cathode external electrode provided on an outer surface of the resin molded body,
The capacitor element is
a valve metal base having a core and a porous portion formed along the surface of the core, the end of which is exposed on the outer surface of the resin molded body;
a dielectric layer formed on the porous portion;
a solid electrolyte layer formed on the dielectric layer;
a conductive layer formed on the solid electrolyte layer,
the cathode external electrode is electrically connected to the conductive layer,
the anode external electrode includes a first electrode layer in direct contact with the core portion of the valve metal substrate,
the first electrode layer includes flat particles having an aspect ratio of 2 or more, the major axis of which is oriented along the outer surface in a cross section including the first electrode layer and perpendicular to the outer surface of the resin molded body where the valve metal base is exposed and to a main surface of the valve metal base,
the first electrode layer includes a metal;
An electrolytic capacitor characterized in that in a Fourier transform infrared spectrum measured by a diffuse reflectance method of the first electrode layer, the ratio of the intensity of the peak attributable to boric acid to the intensity of the peak attributable to a metal is 5% or less.

＜2＞
The electrolytic capacitor according to <1>, wherein the peak derived from the boric acid is below the detection limit.

＜3＞
The electrolytic capacitor according to <1> or <2>, wherein in a Fourier transform infrared spectroscopy spectrum obtained by a diffuse reflectance method of the first electrode layer, a ratio of an intensity of the highest peak among peaks at 2800 cm ^-1 or more and 3000 cm ^-1 or less derived from a C-H bond to an intensity of a peak derived from the metal is 0.5% or less.

＜4＞
The electrolytic capacitor according to <3>, wherein the peak at 2800 cm ⁻¹ or more and 3000 cm ⁻¹ or less derived from the C—H bond is a peak derived from an organic acid.

＜5＞
The electrolytic capacitor according to <3> or <4>, wherein a peak at 2800 cm ⁻¹ or more and 3000 cm ⁻¹ or less derived from the C—H bond is below a detection limit.

＜6＞
The electrolytic capacitor according to any one of <1> to <5>, wherein the first electrode layer contains Cu.

Reference Signs List

1, 2 Electrolytic capacitor 3 Anode 4 Valve metal base 4a Core portion 4b Porous portion 5 Dielectric layer 7 Cathode 7a Solid electrolyte layer 7b Conductive layer 7c Cathode lead layer 7d Cathode lead portion 8 Sealing resin 9 Resin molded body 9a First end surface of resin molded body (outer surface of resin molded body)
9b: second end surface of resin molded body (outer surface of resin molded body)
9c Bottom surface of resin molded body (outer surface of resin molded body)
9d Upper surface of resin molded body (outer surface of resin molded body)
9e: First side surface of resin molded body (outer surface of resin molded body)
9f: second side surface of resin molded body (outer surface of resin molded body)
11 Anode

external electrode

11a, 13a

First electrode layer

11b, 13b

Second electrode layer

11c, 13c Third electrode layer 13 Cathode external electrode 15 Flat particle 16 Particle other than flat particle 20 Capacitor element 30 Laminate 51 Aerosol deposition device 52 Carrier gas 53 Metal fine particles 54 Aerosol generator 55 Chamber 56 Nozzle 57 Stage

Claims

a resin molded body including a laminate including a capacitor element and a sealing resin that seals the periphery of the laminate;
an electrolytic capacitor comprising an anode external electrode and a cathode external electrode provided on an outer surface of the resin molded body,
The capacitor element is
a valve metal base having a core and a porous portion formed along the surface of the core, the end of which is exposed on the outer surface of the resin molded body;
a dielectric layer formed on the porous portion;
a solid electrolyte layer formed on the dielectric layer;
a conductive layer formed on the solid electrolyte layer,
the cathode external electrode is electrically connected to the conductive layer,
the anode external electrode includes a first electrode layer in direct contact with the core portion of the valve metal substrate,
the first electrode layer includes flat particles having an aspect ratio of 2 or more, the major axis of which is oriented along the outer surface of the resin molded body, in a cross section perpendicular to the outer surface where the valve metal base is exposed and perpendicular to a main surface of the valve metal base and including the first electrode layer;
the first electrode layer includes a metal;
An electrolytic capacitor, characterized in that in a Fourier transform infrared spectrum measured by a diffuse reflectance method of the first electrode layer, the ratio of the intensity of a peak derived from boric acid to the intensity of a peak derived from a metal is 5% or less.
The electrolytic capacitor according to claim 1, in which the peak derived from the boric acid is below the detection limit.
3. The electrolytic capacitor according to claim 1, wherein the ratio of the intensity of the highest peak among the peaks at 2800 cm -1 or more and 3000 cm -1 or less derived from a C-H bond to the intensity of the peak derived from the metal in a Fourier transform infrared spectrum measured by a diffuse reflectance method of the first electrode layer is 0.5% or less.
4. The electrolytic capacitor according to claim 3, wherein the peak at 2800 cm −1 or more and 3000 cm −1 or less derived from the C—H bond is a peak derived from an organic acid.
5. The electrolytic capacitor according to claim 3, wherein a peak at 2800 cm −1 or more and 3000 cm −1 or less derived from the C—H bond is below a detection limit.
The electrolytic capacitor according to claim 1 , wherein the first electrode layer contains Cu.