WO2023120383A1

WO2023120383A1 - Electrolytic capacitor and production method thereof

Info

Publication number: WO2023120383A1
Application number: PCT/JP2022/046246
Authority: WO
Inventors: 健汰佐藤; 宗史門川; 淳一栗田; 明子松居
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2021-12-23
Filing date: 2022-12-15
Publication date: 2023-06-29

Abstract

This electrolytic capacitor is provided with: at least one capacitor element including a positive electrode section and a negative electrode section; an exterior body that seals the capacitor element; and a plurality of external electrodes that are electrically connected to the positive electrode section and the negative electrode section, respectively. An end surface of at least one among the positive electrode section and the negative electrode section of the capacitor element is exposed from at least one outer surface of the exterior body. The exposed end surface and the outer surface are covered with the external electrode. An electroless Ag plating layer covering at least the outer surface is interposed between the outer electrode and the outer surface. The electroless Ag plating layer covers the outer surface through or without a base layer which is a non-plating layer.

Description

Electrolytic capacitor and manufacturing method thereof

The present disclosure relates to electrolytic capacitors and manufacturing methods thereof.

An electrolytic capacitor includes a capacitor element, an exterior body that seals the capacitor element, and a plurality of external electrodes that are electrically connected to the anode side and the cathode side of the capacitor element, respectively. The capacitor element includes an anode body having a first portion (also referred to as an anode lead-out portion) including a first end and a second portion (also referred to as a cathode formation portion) including a second end; and a cathode portion covering at least a portion of the dielectric layer in the second portion. In the capacitor element, the anode body constitutes the anode portion.

In general, the anode part or the cathode part and the external electrode are formed by connecting one end of a wire, tab, or frame-shaped lead to the anode part or the cathode part, and pulling out the other end of the lead from the exterior body. It is often connected to an external electrode. In some cases, the end face of the anode part or the cathode part is exposed to the outer surface of the package, and the exposed end face and the external electrode are electrically connected.

For example, in Patent Document 1, a rectangular parallelepiped resin molded body including a laminate including a capacitor element and a sealing resin for sealing the periphery of the laminate, and formed on a first end surface of the resin molded body, a first external electrode electrically connected to the anode exposed from the first end surface; and a first external electrode formed on the second end surface of the resin molding and electrically connected to the cathode exposed from the second end surface. a second external electrode, a third external electrode formed on the first end surface side of the bottom surface of the resin molded body, and a fourth external electrode formed on the second end surface side of the bottom surface of the resin molded body; wherein the first external electrode, the second external electrode, the third external electrode, and the fourth external electrode each comprise a base electrode layer formed on the resin molding, and the a plating layer formed on the base electrode layer, the base electrode layer of the first external electrode and the base electrode layer of the third external electrode are separated from each other, and the base electrode layer of the second external electrode is separated from the base electrode layer of the third external electrode; An electrolytic capacitor is proposed in which the base electrode layer and the base electrode layer of the fourth external electrode are separated from each other.

JP 2020-141059 A

In Patent Document 1, a plated layer is formed on the end faces of the anode and the cathode exposed at the end face of the exterior body (the above resin molded body), and the external electrodes are formed via this plated layer. Since the plating layer is formed on the very small exposed end face of the anode or cathode, there is a limit to increasing the adhesion strength between the end face of the anode or cathode and the external electrode.

A first aspect of the present disclosure provides at least one capacitor element including an anode portion and a cathode portion;
an exterior body that seals the capacitor element;
a plurality of external electrodes electrically connected to each of the anode portion and the cathode portion;
at least one end surface of the anode portion and the cathode portion of the capacitor element is exposed from at least one outer surface of the exterior body;
The exposed end surface and the outer surface are covered with the external electrode,
An electroless Ag plating layer covering at least the outer surface is interposed between the external electrode and the outer surface,
The electroless Ag plating layer covers the outer surface with or without an underlying layer, and the underlying layer is a non-plating layer.

A second aspect of the present disclosure includes at least one capacitor element including an anode section and a cathode section, and sealing the capacitor element with at least one end face of the anode section and the cathode section exposed from at least one outer surface. a step of preparing a precursor comprising an outer body that
forming an electroless Ag plating layer by performing electroless Ag plating so as to cover the at least one outer surface of the exterior body;
forming an external electrode covering the electroless Ag plating layer to obtain an electrolytic capacitor.

It is possible to increase the adhesion between the end face exposed from the outer surface of the exterior body of the anode part or the cathode part and the external electrode.

1 is a cross-sectional view schematically showing an electrolytic capacitor according to an embodiment of the present disclosure; FIG. 2 is a cross-sectional view schematically showing the structure of a capacitor element that constitutes the electrolytic capacitor of FIG. 1; FIG. FIG. 4 is a cross-sectional view schematically showing an electrolytic capacitor according to another embodiment of the present disclosure;

While the novel features of the present invention are set forth in the appended claims, the present invention, both as to construction and content, together with other objects and features of the present invention, will be further developed by the following detailed description in conjunction with the drawings. will be well understood.

In Patent Document 1, a small end surface of the anode part or the cathode part is exposed from the outer surface of the exterior body, the exposed end face is covered with an inner layer plating layer, and the inner layer plating layer and the outer surface of the exterior body are mixed with Ag filler and resin. By covering with a resin electrode layer formed by printing a paste containing and covering the resin electrode layer with an outer layer plating layer, an external electrode covering the outer surface is formed. The inner layer plating layer is formed of a Ni plating layer covering the exposed end surface and an Ag plating layer covering the Ni plating layer. However, since the inner plated layer is formed on a very small end surface of the anode portion or the cathode portion, it is difficult to ensure high adhesion strength. Therefore, when an external stress is applied to an electrolytic capacitor, cracks may occur between the inner plating layer and the resin electrode layer or within the resin electrode layer, causing peeling within the resin electrode layer, or cracking between the resin electrode layers. Separation may occur between the contacting members (for example, the inner plated layer, the exterior body, the substrate) or between the inner plated layer and the end surface of the anode part or the cathode part. When such cracks or peeling occurs, the electrical conductivity is lowered, and the barrier properties of the electrolytic capacitor are lowered, making it easier for air to enter the inside of the electrolytic capacitor.

In view of the above, (1) the electrolytic capacitor according to the first aspect of the present disclosure includes at least one capacitor element including an anode portion and a cathode portion, an exterior body that seals the capacitor element, the anode portion and the cathode and a plurality of external electrodes electrically connected to each of the portions. At least one end surface of the anode portion and the cathode portion of the capacitor element is exposed from at least one outer surface of the exterior body. The exposed end surface and the outer surface are covered with the external electrode. An electroless Ag plating layer covering at least the outer surface is interposed between the outer electrode and the outer surface. The electroless Ag-plated layer covers the outer surface with or without an underlying layer, which is a non-plated layer.

As described above, in the electrolytic capacitor according to the first aspect of the present disclosure, in the structure in which the outer surface of the exterior body is covered with the external electrode, together with the end face exposed from the exterior surface of the exterior body, at least one of the anode portion and the cathode portion , an electroless silver-plated layer (sometimes referred to as an electroless Ag-plated layer) covering at least the outer surface is interposed between the external electrode and the outer surface. By forming the electroless Ag plating layer so as to cover the outer surface of the package, not only the end face exposed from the outer surface of the anode part or the cathode part, but also a large area of the outer surface of the package is covered with the electroless Ag plating layer. . Also, in electroless Ag plating, a relatively dense plating layer is formed. As a result, the electroless Ag plating layer has a high anchoring effect on the outer surface of the exterior body. The electroless Ag plating layer has a high affinity with external electrodes. Therefore, the electroless Ag-plated layer can enhance the adhesion between the exposed end face of the anode part or the cathode part, the outer surface of the outer package, and the external electrode. As a result, excellent electrical connection between the exposed end face of the anode portion or the cathode portion and the external electrode can be ensured, thereby suppressing an increase in initial equivalent series resistance (ESR). In general, if the adhesion between the exposed end face of the anode part or the cathode part and the external electrode is low, cracks or peeling may easily occur during the manufacturing process or the distribution process, resulting in a large difference in ESR between individual electrolytic capacitors. variability tends to increase. On the other hand, in the present disclosure, by providing an electroless Ag plating layer, it is possible to ensure high adhesion between the exposed end surface of the anode part or the cathode part, the outer surface of the exterior body, and the external electrode. Initial ESR variability can be reduced between individuals. Therefore, high reliability of the electrolytic capacitor can be obtained. In addition, even if external stress is applied to the electrolytic capacitor, peeling or cracking can be suppressed between the exposed end face of the anode or cathode and the external electrode, resulting in high barrier properties against air (in particular, high oxygen barrier properties). performance) can be obtained, and intrusion of air into the electrolytic capacitor can be suppressed. Since deterioration of the capacitor element due to intruding oxygen or moisture is suppressed, an increase in ESR can be suppressed even if the electrolytic capacitor is used for a long period of time. Therefore, also from this point, high reliability of the electrolytic capacitor can be obtained.

The outer surface of the exterior body is the surface that forms the outer shape of the exterior body. For example, in the case where the capacitor element is sealed with the package and the package has a shape such as a rectangular parallelepiped or a cube, the six surfaces of the rectangular parallelepiped or cube correspond to the outer surfaces of the package. The outer surface of the armor includes surfaces referred to as main surfaces, side surfaces, end surfaces, and the like of the armor. For example, when a capacitor element is mounted on a substrate and sealed with an outer package, and the sealed object has a shape such as a rectangular parallelepiped or a cube, one surface (for example, the bottom surface) corresponds to the surface of the substrate. , the remaining five surfaces may correspond to the outer surface of the armor.

The end face of the anode part exposed from the outer surface of the package may be the end face of the anode part (more specifically, the first part (in other words, the anode lead-out part)). It may be the end face of the lead connected to the . The end face of the cathode portion exposed from the outer surface of the outer package may be the end face of the cathode portion (more specifically, the end face of the member (for example, metal foil) constituting the cathode portion). It may be the end face of a lead that is physically connected. The lead whose end face is exposed may be wire-shaped, but preferably tab-shaped or frame-shaped, or may be sheet-shaped.

(2) In (1) above, the electroless Ag plating layer may include a silver mirror plating layer.

(3) In (1) or (2) above, the external electrode may include a conductive paste layer covering the electroless Ag plating layer and a Ni/Sn plating layer covering the conductive paste layer.

(4) In any one of the above (1) to (3), the electroless Ag plating layer may cover the exposed end face without the underlayer.

(5) In any one of (1) to (3) above, a first plating layer may be interposed between the exposed end surface and the electroless Ag plating layer.

(6) In (5) above, the first plating layer may contain at least one selected from the group consisting of Ag, Ni, Cu and Zn.

(7) In (5) or (6) above, the first plating layer may include a plurality of plating layers.

(8) In any one of (1) to (7) above, even if the end face of the anode portion is exposed from the first outer surface of the outer package and is covered with the first external electrode together with the first outer surface. good. An end surface of the cathode portion may be exposed from the second outer surface of the exterior body and covered with a second external electrode together with the second outer surface. The electroless Ag plating layer may be interposed between the first outer surface and the first external electrode covering the first outer surface. The electroless Ag plating layer may be interposed between the second outer surface and the second external electrode covering the second outer surface.

(9) In any one of (1) to (7) above, the electrolytic capacitor may include a plurality of stacked capacitor elements.

(10) In (9) above, even if the end face of the anode portion of each of the plurality of capacitor elements is exposed from the first outer surface of the exterior body and is covered with a first external electrode together with the first outer surface. good. An end surface of the cathode portion of each of the plurality of capacitor elements may be exposed from the second outer surface of the exterior body and covered with a second external electrode together with the second outer surface. The electroless Ag plating layer may be interposed between the first outer surface and the first external electrode covering the first outer surface. The electroless Ag plating layer may be interposed between the second outer surface and the second external electrode covering the second outer surface.

(11) In (9) above, an end surface of the anode part of a part of the capacitor elements may be exposed from the first outer surface of the exterior body and covered with a first external electrode together with the first outer surface. . An end surface of the anode portion of the remaining capacitor element may be exposed from a second outer surface opposite to the first outer surface and covered with a third outer electrode together with the second outer surface. The electroless Ag plating layer may be interposed between the first outer surface and the first external electrode covering the first outer surface. The electroless Ag plating layer may be interposed between the second outer surface and the third outer electrode covering the second outer surface.

(12) In any one of (1) to (11) above, the electroless Ag plating layer may have a thickness of 0.01 μm or more and 10 μm or less.

The present disclosure includes a step of forming an electroless Ag-plated layer by performing electroless Ag plating so as to cover the outer surface of the exterior body where at least one end face of the anode part and the cathode part of the capacitor element is exposed; Forming an external electrode covering the Ag plating layer to obtain an electrolytic capacitor is also included.

More specifically, (13) the method for manufacturing an electrolytic capacitor of the present disclosure comprises:
A precursor comprising: at least one capacitor element including an anode portion and a cathode portion; and an exterior body sealing the capacitor element with at least one end surface of the anode portion and the cathode portion exposed from at least one outer surface. a step of preparing
forming an electroless Ag plating layer by performing electroless Ag plating so as to cover the at least one outer surface of the exterior body;
and forming an external electrode covering the electroless Ag plating layer to obtain an electrolytic capacitor.

(14) In (13) above, the method for manufacturing an electrolytic capacitor may include a step of forming a first plating layer so as to cover the end faces. In the step of forming the electroless Ag plating layer, the electroless Ag plating may be performed so as to cover the first plating layer and the at least one outer surface of the exterior body.

(15) Regarding (13) or (14) above, in the step of forming the electroless Ag plating layer, silver mirror plating is performed so as to cover the at least one outer surface of the exterior body, and the electroless Ag plating is performed. A silver mirror plating layer may be formed as a layer.

(16) Regarding any one of the above (13) to (15), in a region other than the exposed end surface of the at least one outer surface of the exterior body, between the outer surface and the electroless Ag plating layer The base layer may be formed on the outer surface so that the base layer, which is a non-plating layer, is interposed.

(17) Regarding (13) above, in a state where the exposed end face is masked, in a region other than the exposed end face of the at least one outer face of the exterior body, between the outer face and the electroless Ag plating layer The base layer may be formed on the outer surface so that the base layer, which is a non-plating layer, is interposed in the outer surface.

In the following, the electrolytic capacitor of the present disclosure and its manufacturing method will be described in more detail, including the above (1) to (17). At least one of the above (1) to (17) may be combined with at least one of the elements described below within a technically consistent range.

[Electrolytic capacitor]
(Electroless Ag plating layer)
In the electrolytic capacitor of the present disclosure, at least one end surface of the anode portion and the cathode portion of the capacitor element is exposed from at least one outer surface of the outer package, and the exposed end surface and outer surface are covered with the external electrode. In such a state, the electroless Ag plating layer is formed between the external electrode and the external surface of the external body where the end surface of the anode portion or the cathode portion is exposed so as to cover at least the external surface.

The electroless Ag plating layer may be formed so as to cover the entire outer surface of one of the exterior bodies where the end face of the anode part or the cathode part is exposed, and covers the exposed end face and one of the outer surfaces of the exterior body. It may be formed so as to cover the part. For example, when the end surface of the anode portion is exposed from the first outer surface among the plurality of outer surfaces of the outer package, the electroless electrolyte is applied so as to cover the exposed end surface and at least the peripheral region of the exposed end surface of the first outer surface. An Ag plating layer may be formed. Alternatively, an electroless Ag plating layer may be formed so as to cover the entire first outer surface. Similarly, for example, when the end face of the cathode portion is exposed from the second outer surface, an electroless Ag plating layer is formed so as to cover the exposed end face and at least the peripheral region of the exposed end face of the second outer surface. Alternatively, an electroless Ag plating layer may be formed to cover the entire second outer surface. When electroless Ag plating layers are formed on a plurality of outer surfaces, the composition of the electroless Ag plating layers on at least two outer surfaces may be the same, and the composition of the electroless Ag plating layers on all outer surfaces is different. It's okay to be there.

The electroless Ag plating layer may cover the outer surface of the exterior body via the underlying layer, or may cover the outer surface of the exterior body without the underlying layer (in other words, it is in direct contact with the outer surface. can also be used).

The underlying layer is a non-plating layer. Such a base layer may be a coating layer (or an undercoat layer) used as a base for the electroless Ag plating layer. The underlayer may be, for example, a coating layer formed of a coating agent containing a resin. If necessary, the surface of the underlayer may be subjected to, for example, a cleaning treatment for removing stains such as oils and fats, or a hydrophilic treatment. When the base layer is not provided, the outer surface of the exterior body (including the end surface of the separation layer, which will be described later, exposed from the exterior surface of the exterior body, and the end surface of the insulating spacer, which will be described later, exposed from the exterior surface of the exterior body), If necessary, the above washing treatment, hydrophilization treatment, and the like may be performed.

　The resins contained in the base layer include thermoplastic resins and curable resins. Examples of the resin include at least one selected from the group consisting of alkyd resins, phenolic resins, epoxy resins, acrylic resins, benzoguanamine resins, polyurethane resins, silicone resins, polyester resins, cellulose ethers, cellulose esters, and vinyl chloride resins. is mentioned. Polyester resins also include phenoxy resins. However, the resin contained in the underlayer is not limited to these specific examples. The coating agent may contain a coupling agent (alkoxysilane compound, alkoxytitanium compound (ester, etc.), etc.), metal oxide, etc., in addition to the resin. As the coating agent, a paint containing a curable resin material is preferable. The curable material may be either of the one-component curing type and the two-component curing type. The underlayer may be insulating.

The electroless Ag plating layer should be formed so as to cover the outer surface of the exterior body. The electroless Ag plating layer preferably includes a plating film formed by, for example, a reduction type electroless Ag plating method.

From the viewpoint of easily ensuring a higher anchoring effect on the insulating outer surface, the electroless Ag plating layer preferably contains a silver mirror plating layer. Since silver mirror plating utilizes a silver mirror reaction, the plating film is formed by entering into minute recesses on the surface of the exterior body, and a relatively uniform plating film is formed. Therefore, it is considered that a higher anchor effect can be obtained for the insulating outer surface. The electroless Ag-plated layer may be composed of only a silver mirror-plated layer, or may be composed of a silver mirror-plated layer and at least one other electroless Ag-plated layer. From the viewpoint of obtaining a higher anchor effect, at least the silver mirror-plated layer is formed on the outer surface side of the exterior body (more specifically, in contact with the underlying layer or the outer surface) in the entire electroless Ag-plated layer. preferably. The other electroless Ag plating layer formed so as to cover the silver mirror plating layer may be formed by electroless Ag plating methods such as reduction type, substitution type, and autocatalytic type. Moreover, it is also preferable to configure the electroless Ag plating layer only with a silver mirror plating layer. In this case, a high affinity between the silver mirror-plated layer and the external electrodes is obtained, so that even higher adhesion between the exposed end faces of the anode part or the cathode part and the exterior body and the external electrodes is achieved through the silver mirror-plated layer. can be secured.

The silver mirror-plated layer contains, for example, metallic silver such as pure silver (in other words, simple silver). The silver mirror-plated layer may contain a small amount of impurities (for example, metallic elements other than silver and non-metallic elements such as carbon). Silver mirror plating for electronic materials, for example, can be used to form the silver mirror plating layer.

The thickness of the electroless Ag plating layer is, for example, 0.01 μm or more and 10 μm or less, and may be 0.05 μm or more and 5 μm or less. When the electroless Ag plating layer has such a thickness, it is easier to form a uniform plating film over the entire region of the outer surface covered with the electroless Ag plating layer, resulting in higher adhesion between the exterior body and the external electrodes. easy to obtain. Moreover, since the amount of silver used can be kept relatively low, it is advantageous in terms of cost.

In this specification, the thickness of each layer constituting the plating layer and the external electrode is arbitrarily selected from 10 or more points of each layer based on a cross-sectional image including at least a portion from the outer surface of the exterior body to the external electrode. It is obtained by measuring the thickness by averaging.

In addition, the type or composition of each layer that constitutes the plating layer and the external electrode can be specified by analyzing the components (for example, metal components and non-metal components) contained in each layer. The composition ratio of the elements in each plating layer is determined by, for example, an electron probe microanalyzer (EPMA).

Since the electroless Ag plating layer is interposed between the outer surface of the exterior body and the external electrode, it covers not only the outer surface of the exterior body but also the end face of the anode part or the cathode part exposed from the outer surface. From the viewpoint of ensuring high conductivity, it is preferable that an electroless Ag plating layer is formed (in other words, in contact) on the end face exposed from the outer surface of the anode part or the cathode part without an underlying layer intervening. preferable. Another plated layer (referred to as a first plated layer) may be interposed between the exposed end surface and the electroless Ag plated layer. In this case, the exposed end face is covered with a first plating layer, and the first plating layer and the outer surface of the exterior body are covered with an electroless Ag plating layer (second plating layer). As will be described later, an insulating separation layer may be provided to separate the anode portion and the cathode portion, and the end face of the separation layer may be exposed from the outer surface of the exterior body. In this case, the end face of the separation layer may be covered with an electroless Ag plating layer with or without an underlying layer. Further, when the electrolytic capacitor includes a plurality of stacked capacitor elements, conductive or insulating spacers may be arranged between the ends of adjacent anode portions or between the ends of adjacent cathode portions. be. When the electrolytic capacitor includes an insulating spacer, the end surface of the spacer may be exposed from the outer surface of the package. In this case, the end face of the spacer may be covered with an electroless Ag plating layer with or without an underlying layer. When silver mirror plating is used to form the electroless Ag plating layer, the plating layer can be formed on the outer surface of the exterior body without forming a base layer, and a high anchor effect can be ensured. When the end face of the separation layer or the end face of the insulating spacer is exposed from the outer surface of the exterior body, the silver mirror plating layer is formed with high adhesion even on these end faces without the interposition of the underlying layer. be able to.

The end face exposed from the outer surface of the exterior body of the anode part or the cathode part may be pretreated as necessary prior to the formation of the electroless Ag plating layer or the first plating layer. Examples of such pretreatment include known pretreatments for plating (degreasing, etching, acid treatment, desmutting, zincate treatment, etc.). The pretreatment may be performed before or after forming the base layer on the outer surface of the exterior body.

(First plating layer)
The first plating layer is formed, for example, so as to cover the end surface of the anode portion or the cathode portion exposed from the outer surface of the exterior body. The first plating layer may cover the outer surface of the exterior body around the exposed end surface of the anode part or the cathode part, but the area that covers the outer surface is preferably small, and the first plating layer is selected so as to cover only the exposed end surface. It is preferable to form the When the end face of the separation layer is exposed from the outer surface, it may be covered with the first plating layer, but it is preferably covered with the electroless Ag plating layer without being covered with the first plating layer. .

The first plating layer may contain, for example, at least one selected from the group consisting of Ag (silver), Ni (nickel), Cu (copper) and Zn (zinc). Such a first plating layer facilitates maintaining high adhesion between the exposed end face of the anode portion or the cathode portion and the electroless Ag plating layer, and is advantageous in keeping the interfacial resistance low. The first plating layer may contain a simple substance of the above metal, or may contain an alloy containing the above metal. The first plating layer may be formed by either electroplating or electroless plating.

The first plating layer may include a single plating layer, or may include a plurality of plating layers. For example, the first plating layer may include at least an electroless Ni plating layer. From the viewpoint of enhancing the adhesion of the electroless Ni plating layer to the end face of the anode portion or the cathode portion, zincate treatment may be performed before forming the electroless Ni plating layer. When the exposed end face of the anode part or the cathode part is subjected to zincate treatment and electroless Ni plating is performed, the first plated layer can be selectively formed on the exposed end face. The first plating layer may include an electroless Ni plating layer and an Ag plating layer covering the electroless Ni plating layer. A known method may be employed to form the first plating layer.

The electroless Ni plating layer may contain at least one element selected from phosphorus (P) and boron (B) elements. These elements originate, for example, from reducing agents (sodium diphosphite, dimethylamine-borane, etc.) added to the plating bath. When the electroless Ni plating layer contains phosphorus (P), the corrosion resistance and oxidation resistance of the electroless Ni plating layer are improved.

The electroless Ni plating layer may consist essentially of Ni only. Here, "the electroless Ni plating layer consists essentially of Ni" means that the proportion of elements other than Ni in the electroless Ni plating layer is less than 0.1% by mass. In this case, although the plating takes time, a dense and highly corrosion-resistant plating layer can be obtained, which is advantageous for further reducing the ESR.

The thickness of the electroless Ni plating layer may be 0.1 μm or more and 10 μm or less.

The Ag-plated layer covering the electroless Ni-plated layer may be an electrolytic Ag-plated layer, or may be an electroless Ag-plated layer having a composition different from that of the electroless Ag-plated layer covering the outer surface of the exterior body. For example, the electroless Ag plating layer covering the outer surface of the exterior body may include a silver mirror plating layer, and the Ag plating layer constituting the first plating layer may be formed by electroless Ag plating different from silver mirror plating. The electroless Ag plating layer that constitutes the first plating layer may be formed by, for example, substitution type, reduction type, autocatalytic type, or other electroless Ag plating methods.

The thickness of the Ag plating layer that constitutes the first plating layer may be, for example, 0.1 μm or more and 50 μm or less. The thickness of the electroless Ag plating layer forming the first plating layer may be, for example, 0.1 μm or more and 1 μm or less. The thickness of the electrolytic Ag plating layer forming the first plating layer may be, for example, 0.1 μm or more and 50 μm or less, or may be 0.1 μm or more and 10 μm or less.

In the present disclosure, an electroless Ag-plated layer (silver mirror-plated layer, etc.) is formed so as to cover the end face of the anode portion or the cathode portion exposed from the outer surface of the exterior body and the outer surface of the exterior body. The electroless Ag-plated layer such as the silver mirror-plated layer can suppress an increase in resistance between the end face of the anode portion or the cathode portion and the external electrode, and can suppress the initial ESR to a low level. In addition, it is possible to reduce variations in initial ESR among individual electrolytic capacitors (for example, individual pieces from the same lot). Therefore, the effect of reducing the initial ESR can be obtained without providing the first plating layer such as the electroless Ni plating layer or the electroless Ni plating layer and the Ag plating layer on the exposed end faces. Moreover, when the first plating layer is not provided, the effect of reducing the initial ESR variation is enhanced.

(external electrode)
The external electrode includes, for example, a metal layer (plated layer, etc.). The metal layer contains, for example, at least one selected from the group consisting of nickel (Ni), copper (Cu), zinc (Zn), tin (Sn), silver (Ag), and gold (Au).

The external electrode may include, for example, a laminated structure of Ni layers and Sn layers. The external electrodes may include Ni/Sn plating layers. The Ni/Sn plating layer is a plating layer containing Ni and Sn, and includes, for example, two layers of a Ni plating layer and a Sn plating layer formed on the Ni plating layer. In the Ni/Sn plating layer, Ni in the Ni plating layer may diffuse to the Sn plating side, Sn in the Sn plating layer may diffuse to the Ni plating layer side, and an alloy layer of Ni and Sn may be formed.

At least the outer surface of the external electrode may be a metal with excellent wettability with solder. Such metals include, for example, at least one selected from the group consisting of Sn, Au, Ag, and Pd. Therefore, the outer surface of the Ni/Sn plating layer is preferably the outer surface of the external electrode.

The total thickness of the metal layers (plated layers, etc.) forming the external electrodes may be, for example, 0.1 μm or more and 100 μm or less, or may be 1 μm or more and 50 μm or less, or 1 μm or more and 20 μm or less. For example, the thickness of each of the Ni plating layer and the Sn plating layer may be 0.1 μm or more and 50 μm or less, or may be 0.5 μm or more and 10 μm or less.

The external electrode may include a conductive paste layer covering the electroless Ag plating layer and the metal layer covering the conductive paste layer. When the external electrode includes a conductive paste layer, cracks or peeling are likely to occur in and around the conductive paste layer when an external stress is applied to the electrolytic capacitor. In the present disclosure, even when the external electrode includes a conductive paste layer, the conductive paste layer is in contact with an electroless Ag plating layer such as silver mirror plating, so that the interface resistance can be kept low and the electroless Ag plating Since the adhesion between the layer and the external electrode is enhanced and the occurrence of cracks or peeling can be suppressed, the initial ESR can be reduced. Among the above, the Ni/Sn plating layer is preferable as the metal layer covering the conductive paste layer. When the external electrodes include a conductive paste layer and a Ni/Sn plating layer, it is possible to ensure higher adhesion between the electroless Ag plating layer and the external electrodes, and to ensure high wettability with solder. .

The conductive paste layer contains, for example, conductive particles and a resin material. Therefore, the conductive paste layer may be referred to as a conductive resin layer. The resin material acts as a binder. Examples of resin materials include curable resins such as epoxy resins and compositions thereof. Conductive particles include, for example, particles of a conductive inorganic material. Examples of conductive inorganic materials include metals and conductive carbon materials. Examples of metals include silver, silver alloys, copper, copper alloys, and the like. Examples of conductive carbon materials include carbon black, graphite, carbon nanofibers, and carbon nanotubes. When a silver paste layer containing at least one selected from the group consisting of silver particles and silver alloy particles is used as the conductive paste layer, it has a high affinity with the electroless Ag plating layer and is conductive with the electroless Ag plating layer. It is possible to obtain a higher adhesion with the paste layer and to keep the interfacial resistance low.

The electrolytic capacitor has a plurality of external electrodes electrically connected to each of the anode portion and the cathode portion. For example, when the end face of the anode portion is exposed from the first outer surface of the exterior body, the exposed end face is covered with the first external electrode together with the first outer surface. When the end surface of the cathode portion is exposed from the second outer surface of the exterior body, the exposed end surface is covered with the second external electrode together with the second outer surface. The electroless Ag plating layer may be interposed between at least one of the first outer surface and the first external electrode covering the first outer surface and between the second outer surface and the second outer electrode covering the second outer surface. good. From the viewpoint of ensuring higher reliability of the electrolytic capacitor, it is preferable to interpose both between the first outer surface and the first outer electrode and between the second outer surface and the second outer electrode.

The external electrode may be formed so as to cover the entire electroless Ag plating layer on one outer surface of the exterior body, or may be formed so as to cover the entire outer surface of the exterior body on which the electroless Ag plating layer is formed. good. In addition, in addition to the outer surface (e.g., side surface) of the exterior body on which the electroless Ag plating layer is formed, it is continuously formed so as to cover a part of the outer surface (e.g., top surface or bottom surface) that intersects with this outer surface. may

The electrolytic capacitor has at least one capacitor element, and may have a plurality of capacitor elements. A plurality of capacitor elements may be stacked. In this case, the orientations of the first portions of the plurality of capacitor elements may be the same or different. For example, the cathode portions of a plurality of capacitor elements may be alternately overlapped via a conductive adhesive so that the first portions of adjacent capacitor elements face opposite sides. Also, the capacitor elements may be stacked such that the first portions face the opposite direction in any order.

As for the configuration of the electrolytic capacitor, only the end face of the anode portion may be exposed from the outer surface of the exterior body and electrically connected to the external electrode. Only the end face of the cathode portion may be exposed from the outer surface of the outer package and electrically connected to the external electrode. An end surface of the anode portion and an end surface of the cathode portion may be exposed from the outer surface of the exterior body and electrically connected to separate external electrodes (eg, the first external electrode and the second external electrode, respectively). The electroless Ag plating layer is formed between at least one of the plurality of external electrodes and the outer surface of the exterior body covered by this external electrode, and between all the external electrodes and the external surface covered by each external electrode. may be formed.

When the electrolytic capacitor includes a plurality of laminated capacitor elements, for example, when the end surfaces of the anode portions of the plurality of capacitor elements are exposed from the first outer surface of the package, the exposed end surfaces of the anode portions are The first outer surface may be covered with the first outer electrode. When the end faces of the cathode portions of the plurality of capacitor elements are exposed from the second outer surface of the exterior body, the exposed end faces of the respective cathode portions may be covered with the second outer electrode together with the second outer surface. The electroless Ag plating layer is interposed between at least one of the first outer surface and the first outer electrode and between the second outer surface and the second outer electrode. From the viewpoint of ensuring higher reliability, the electroless Ag plating layer should be interposed both between the first outer surface and the first external electrode and between the second outer surface and the second external electrode. is preferred. The composition of each electroless Ag plating layer may be the same or different. In such a configuration, a plurality of capacitor elements are stacked such that the first portions and the second portions of each capacitor element overlap each other. The second outer surface may be located opposite the first outer surface.

When the electrolytic capacitor includes a plurality of laminated capacitor elements, the end surfaces of the anode portions of some of the capacitor elements are exposed from the first outer surface of the package, and the end surfaces of the anode portions of the remaining capacitor elements are exposed from the first outer surface. may be exposed from a different outer surface (for example, a second outer surface opposite to the first outer surface). In this case, the plurality of capacitor elements may be stacked such that the first portions and the second portions are alternately stacked, for example. The end face of the anode portion exposed from the first outer surface is covered with the first outer electrode together with the first outer surface, and the end face of the anode portion exposed from the second outer surface is covered with the third outer electrode together with the second outer surface. good. The first external electrode and the third external electrode are both external electrodes on the anode side, and are provided apart from each other. The electroless Ag plating layer may be interposed between at least one of the first outer surface and the first outer electrode and between the second outer surface and the third outer electrode. From the viewpoint of ensuring higher reliability, the electroless Ag plating layer should be interposed both between the first outer surface and the first external electrode and between the second outer surface and the third external electrode. is preferred. The external electrode on the cathode portion side is formed so as to cover an external surface other than the first external surface and the second external surface (for example, one external surface (third external surface) between the first external surface and the second external surface) of the external body. may be For example, the end face of the cathode portion of each capacitor element exposed from the third outer surface is covered with the second outer electrode together with the third outer surface. An electroless Ag plating layer may be interposed between the third outer surface and the second external electrode. When an electroless Ag plating layer is formed on each of the first outer surface, the second outer surface, and the third outer surface, the composition of the at least two electroless Ag plating layers may be the same, and all the electroless Ag plating The composition of the layers can be different.

The end face exposed from the outer surface of at least one of the anode part and the cathode part may be flush with the outer surface. However, this is not the only case, and the exposed end surface does not necessarily have to be on the same plane as the outer surface of the exterior body, and the exposed end surface may protrude from the outer surface or may be recessed.

Components other than the external electrodes of the electrolytic capacitor of the present disclosure and the connection structure between the external electrodes and the outer surface of the exterior body will be described in more detail below.

(Anode body)
The anode body has a first portion including one end (sometimes referred to as a first end) and the other end opposite to the one end (sometimes referred to as a second end). and a second portion comprising. A cathode portion is formed in the second portion of the anode body.

The anode body may contain, for example, a valve metal, an alloy containing a valve metal, and a compound containing a valve metal (such as an intermetallic compound). These materials may be used singly or in combination of two or more. Examples of valve metals include aluminum, tantalum, niobium, and titanium. The anode body may be a foil of a valve action metal, an alloy containing a valve action metal, or a compound containing a valve action metal, and particles of a valve action metal, an alloy containing a valve action metal, or a compound containing a valve action metal. or a sintered body thereof (porous sintered body).

When a metal foil is used for the anode body, a porous portion is usually formed on the surface of at least the second portion of the anode foil in order to increase the surface area. Such anode foil has a core portion and a porous portion formed on the surface of the core portion. The porous portion is formed, for example, by forming unevenness on the surface of the anode body. The anode body having the porous portion may be formed, for example, by roughening the surface of at least the second portion of the anode foil by etching (electrolytic etching or the like). After arranging a predetermined masking member on the surface of the first portion, it is also possible to perform surface roughening treatment such as etching treatment. On the other hand, it is also possible to roughen the entire surface of the anode foil by etching or the like. In the former case, an anode foil having no porous portion on the surface of the first portion and a porous portion on the surface of the second portion is obtained. In the latter case, a porous portion is formed on the surface of the first portion in addition to the surface of the second portion. As the etching treatment, a known method may be used, for example, electrolytic etching. The masking member is not particularly limited, and may be a conductor containing a conductive material, but is preferably an insulator such as resin. The masking member is removed prior to formation of the solid electrolyte layer.

When the entire surface of the anode foil is roughened, the surface of the first portion has a porous portion. For this reason, the adhesion between the porous portion and the exterior body is not sufficient, and air (specifically, oxygen and moisture) may enter the inside of the electrolytic capacitor through the contact portion between the porous portion and the exterior body. In order to suppress this, at least part of the porous portion formed in the first portion may be previously removed or compressed to crush the pores of the porous portion. As a result, it is possible to reduce the intrusion of air into the electrolytic capacitor through the porous portion from the end portion side of the first portion exposed from the exterior body. In addition, it is possible to suppress deterioration in the reliability of the electrolytic capacitor due to the intrusion of the air.

When stacking a plurality of capacitor elements, the first ends of the anode bodies of the capacitor elements may be bundled, connected to leads, and electrically connected to external electrodes. However, if the end faces of the plurality of first end portions are exposed from the outer surface of the exterior body without being bundled and electrically connected to the external electrodes, it is not necessary to secure the length for bundling them into the first portion. Therefore, when electrical connection is made by exposing the end face, compared to the case of bundling a plurality of first portions, the proportion of the first portion in the anode body can be made smaller and the capacity can be increased. can reduce the contribution to ESR due to

(dielectric layer)
The dielectric layer is formed, for example, by anodizing the valve metal on the surface of at least the second portion of the anode body by chemical conversion treatment or the like. The dielectric layer contains an oxide of a valve metal. For example, the dielectric layer contains aluminum oxide when aluminum is used as the valve metal. The dielectric layer is formed along at least the surface of the second portion where the porous portion is formed (including the inner wall surfaces of the pores of the porous portion). Note that the method for forming the dielectric layer is not limited to this, as long as an insulating layer that functions as a dielectric can be formed on the surface of the second portion. The dielectric layer may also be formed on the surface of the first portion (for example, the porous portion on the surface of the first portion).

In the chemical conversion treatment, for example, the surface of the anode body is impregnated with the chemical conversion liquid by immersing the anode body in the chemical conversion liquid, and a voltage is applied between the anode body used as the anode and the cathode immersed in the chemical conversion liquid. It can be done by When the surface of the anode body has a porous portion, the dielectric layer is formed along the irregularities on the surface of the porous portion.

(cathode)
A cathode portion is formed on a second portion of the anode body having a dielectric layer. In some cases, the cathode portion covers the surface of the separation layer on the second portion side.

The cathode section includes, for example, a solid electrolyte layer that covers at least part of the dielectric layer, and a cathode extraction layer that covers at least part of the solid electrolyte layer. The cathode section is formed by forming a solid electrolyte so as to cover at least a portion of the dielectric layer, and forming a cathode extraction layer so as to cover at least a portion of the solid electrolyte layer. A capacitor element is obtained by forming a cathode part on a part of an anode body having a dielectric layer.

(Solid electrolyte layer)
The solid electrolyte layer contains, for example, a conductive polymer (conjugated polymer, dopant, etc.). As the conjugated polymer, for example, a π-conjugated polymer (polypyrrole, polythiophene, polyaniline, derivatives thereof, etc.) may be used. For example, polythiophene derivatives include poly(3,4-ethylenedioxythiophene) (PEDOT) and the like. As a dopant, polystyrene sulfonic acid (PSS) or the like may be used, or naphthalene sulfonic acid, toluene sulfonic acid, or the like may be used. The solid electrolyte layer is formed by, for example, using at least one of chemical polymerization and electrolytic polymerization of a conjugated polymer precursor (monomer, oligomer, etc.) and a dopant (naphthalenesulfonic acid, toluenesulfonic acid, etc.) on the dielectric layer. It can be formed by polymerization. Alternatively, a solid electrolyte layer may be formed by applying a solution in which a conjugated polymer and a dopant are dissolved or a dispersion in which a conjugated polymer and a dopant are dispersed, to the dielectric layer and drying it. Dispersion media (solvents) include, for example, water, organic solvents, and mixtures thereof. The solid electrolyte layer may contain a manganese compound.

(Cathode extraction layer)
The cathode extraction layer includes, for example, a conductive layer that contacts the solid electrolyte layer and covers at least a portion of the solid electrolyte layer. The cathode extraction layer includes at least a first layer covering at least a portion of the solid electrolyte layer. The cathode extraction layer may include a first layer covering at least part of the solid electrolyte layer and a second layer covering at least part of the first layer.

For example, the cathode extraction layer may be composed of a metal foil as the first layer. The metal foil may be, for example, Al foil, Cu foil, valve metal (aluminum, tantalum, niobium, etc.), or metal foil made of an alloy containing valve metal. If necessary, the surface of the metal foil may be roughened. The surface of the metal foil may be provided with a chemical conversion coating, or may be provided with a coating of a metal (dissimilar metal) different from the metal constituting the metal foil (dissimilar metal) or a non-metal coating. Examples of dissimilar metals and non-metals include metals such as titanium and nickel, and non-metals such as carbon (such as conductive carbon). The metal foil may be a sintered foil, a vapor-deposited foil, or a coated foil obtained by coating the surface of a metal foil (eg, Al foil, Cu foil) with a conductive film by vapor deposition or coating. The vapor-deposited foil may be an Al foil having Ni vapor-deposited on its surface. Examples of conductive films include Ti, TiC, TiO, and C (carbon) films. The conductive film may be a carbon coating film.

In the cathode extraction layer, the film of the different metal or non-metal (eg, conductive carbon) may be used as the first layer, and the metal foil may be used as the second layer.

The cathode extraction layer may include, for example, a layer containing conductive carbon as a first layer (also referred to as a carbon layer) and a metal-containing layer (for example, a layer containing metal powder or metal foil) as a second layer. good.

Examples of the conductive carbon contained in the carbon layer as the first layer include graphite (artificial graphite, natural graphite, etc.).

The layer containing metal powder as the second layer can be formed, for example, by laminating a composition containing metal powder on the surface of the first layer. Examples of such a second layer include a metal paste layer formed using a composition containing metal powder and resin (binder resin). The metal paste layer includes a silver paste layer containing silver particles and resin. As the resin, a thermoplastic resin can be used, but it is preferable to use a thermosetting resin such as an imide resin or an epoxy resin.

Examples of the metal foil as the second layer include the metal foils exemplified for the first layer.

The metal foil may be attached to the solid electrolyte layer or the first layer (carbon layer, etc.) via a conductive adhesive. Examples of conductive adhesives include adhesives containing conductive carbon, adhesives containing metal particles such as silver particles, and the like.

When the cathode portion contains a metal foil, the end face of the metal foil can be exposed from the outer surface of the exterior body, and electrical connection can be easily made with the external electrode via the electroless Ag plating layer, which is advantageous. . When the electrolytic capacitor includes a plurality of laminated capacitor elements, the metal foil may be provided on at least one of the plurality of capacitor elements, or may be provided so that the metal foil is interposed between adjacent capacitor elements. good. For example, one metal foil may be shared between adjacent capacitor elements. For example, if the electrolytic capacitor includes a plurality of stacked capacitor elements, a metal foil may be sandwiched between adjacent capacitor elements.

(separator)
When a metal foil is used for the cathode extraction layer, a separator may be arranged between the metal foil and the anode foil. The separator is not particularly limited, and for example, a nonwoven fabric containing fibers of cellulose, polyethylene terephthalate, vinylon, polyamide (eg, aromatic polyamide such as aliphatic polyamide and aramid) may be used.

(separation layer)
An insulating separation layer may be provided to electrically separate the first portion and the cathode portion. The separation layer is formed before forming the cathode section. The separation layer may be provided adjacent to the cathode section so as to cover at least part of the surface of the first section. Preferably, the separation layer is in close contact with the first portion and the exterior body. As a result, air can be prevented from entering the inside of the electrolytic capacitor. An isolation layer may be disposed over the first portion with a dielectric layer interposed therebetween. Such an isolation layer is provided after formation of the dielectric layer. Not limited to this case, if necessary, it may be provided before the formation of the dielectric layer.

The separation layer contains, for example, a resin, and those exemplified for the exterior body described later can be used. Insulation may be imparted by compressing and densifying the dielectric layer formed on the porous portion of the first portion.

The separation layer may be provided by, for example, attaching a sheet-like insulating member (resin tape, etc.) to the first portion. When using an anode foil having a porous portion on its surface, the porous portion of at least a portion of the first portion may be removed or compressed to be flattened, and then the insulating member may be adhered to the first portion. It is preferable that the sheet-like insulating member has an adhesive layer on the surface thereof to be attached to the first portion.

Alternatively, the insulating member may be formed by coating or impregnating at least a portion of the first portion with a liquid resin to form an insulating member that is in close contact with the first portion. In the method using the liquid resin, the insulating member may be formed so as to fill the unevenness of at least the surface layer of the porous portion of the first portion. In this case, the liquid resin can easily enter the concave portions of the surface layer of the porous portion, and the insulating member can be easily formed in the concave portions as well. In this case, since the porous portion of the surface layer of the anode body is protected by the insulating member, the end portion of the anode body is partially removed together with the exterior body to form the outer surface of the exterior body, and the end face of the anode body is removed. Collapse of the porous portion of the anode body is suppressed when the anode body is exposed from the outer surface. Since the surface layer of the porous portion of the anode body and the insulating member are firmly adhered to each other, when the end portion of the anode body is partially removed together with the outer package, the insulating member may be removed from the surface of the porous portion of the anode body. Peeling is suppressed.

As the liquid resin, for example, a curable resin composition exemplified for the exterior body described later may be used, or a solution obtained by dissolving the resin in a solvent may be used. Also, a sheet-shaped insulating member may be used while applying or impregnating a liquid resin.

(Spacer)
The spacers are arranged, for example, at least one of between the ends of adjacent anode portions and between the ends of adjacent cathode portions of a plurality of laminated capacitor elements. The spacer may be conductive (such as made of metal) or insulating. When insulating spacers are used, the spacers may be exposed from the outer surface of the outer package together with the end faces of the anode portion or the cathode portion. In this case, a high anchor effect can be ensured by forming an electroless Ag plating layer such as a silver mirror plating layer not only on the outer surface but also on the exposed end surfaces of the insulating spacers. The insulating spacers are made of thermoplastic resin or curable resin, for example. As a material for the spacer, a resin or the like exemplified for the material for the exterior body may be used.

(substrate)
A capacitor element (or a plurality of stacked capacitor elements) may be mounted on the substrate via a conductive adhesive. Of the plurality of laminated capacitor elements, the cathode forming portion of the capacitor element closest to the substrate may have a metal foil on the substrate side. This metal foil may be in contact with the substrate via a conductive adhesive as required.

The substrate may be an insulating substrate or a metal substrate, or may be a laminated substrate (printed substrate, etc.) with wiring patterns formed on the front and back surfaces.

When using a laminated substrate, an external electrode (such as a second external electrode electrically connected to the cathode portion) may be formed in advance on the side of the laminated substrate opposite to the side on which the element laminate is placed. By placing, the external electrode (such as the second external electrode) is connected to the anode portion of the capacitor element via the wiring pattern formed on the laminated substrate and the through hole connecting the wiring pattern on the front surface and the wiring pattern on the back surface. Alternatively, it can be electrically connected to the cathode section (usually the cathode section). In this case, the second external electrode is electrically connected to the cathode of each capacitor element through the substrate. Depending on the wiring pattern on the back surface, the second external electrode (cathode) can be arbitrarily arranged in the central region of the bottom surface of the electrolytic capacitor. For example, the second external electrode may be arranged close to the first external electrode.

A metal substrate may have, for example, a lead frame structure in which a metal plate processed into a predetermined shape is bent. A part of the metal plate may be exposed from the outer package and electrically connected to the external electrode.

(Exterior body)
A capacitor element (or a plurality of laminated capacitor elements) is sealed by being covered with an exterior body. The capacitor element may be sealed so that at least one end surface of the anode part and the cathode part is exposed from the outer surface of the outer package, and after sealing, the outer package is partially removed to form the outer surface. , at least one end face of the anode portion and the cathode portion may be exposed from the outer surface. The other end of the lead electrically connected to one of the anode part and the cathode part is sealed with the outer body so as to be pulled out from the outer body, and the other end of the lead and the external electrode are connected. good too. In addition, a plate-shaped external lead terminal bent into a predetermined shape is applied to the surface of the cathode portion exposed on the capacitor element (or the bottom layer or top layer of a plurality of laminated capacitor elements) via a conductive paste or the like. The electrical connection between the capacitor element and the lead terminal may be established by attaching the capacitor element to the lead terminal.

The exterior body preferably contains, for example, a cured product of a curable resin composition, and may contain a thermoplastic resin or a composition containing it.

The exterior body may be formed using a molding technique such as injection molding, for example. The exterior body may be formed, for example, by filling a curable resin composition or a thermoplastic resin (composition) using a predetermined mold into predetermined locations so as to cover the capacitor element.

The curable resin composition may contain, in addition to the curable resin, at least one selected from fillers, curing agents, polymerization initiators, catalysts, and the like. A thermosetting resin is exemplified as the curable resin. Curing agents, polymerization initiators, catalysts and the like are appropriately selected according to the type of curable resin.

Curable resins include epoxy resins, phenolic resins, urea resins, polyimides, polyamideimides, polyurethanes, diallyl phthalate, unsaturated polyesters, and the like. Examples of thermoplastic resins include polyphenylene sulfide (PPS) and polybutylene terephthalate (PBT). A thermoplastic resin composition containing a thermoplastic resin and a filler may be used.

As the filler, for example, insulating particles and insulating fibers are preferable. Examples of the insulating material that constitutes the filler include insulating compounds (oxides, etc.) such as silica and alumina, glass, mineral materials (talc, mica, clay, etc.), and the like. The exterior body may contain one type of these fillers or may contain two or more types in combination.

From the viewpoint of adhesion between the separation layer and the exterior body, it is preferable that the insulating member and the exterior body each contain a resin. The exterior body adheres more easily to the insulating member containing the resin than the first portion containing the valve metal or the dielectric layer containing the oxide of the valve metal.

From the viewpoint of increasing the strength of the exterior body, the exterior body preferably contains a filler.
On the other hand, the separation layer preferably contains a filler with a smaller particle size than the outer casing, and more preferably does not contain a filler. When the separation layer is formed by impregnating the first portion with a liquid resin, the liquid resin preferably contains a filler having a smaller particle size than the outer casing, and more preferably does not contain a filler. In this case, the liquid resin is easily impregnated into the deep recesses on the surface of the porous portion of the first portion, and the separation layer is easily formed. In addition, it is easy to form a separation layer having a small thickness so that a plurality of capacitor elements can be stacked.

(Manufacturing method of electrolytic capacitor)
Electrolytic capacitors, for example,
Preparing a precursor comprising at least one capacitor element including an anode portion and a cathode portion, and an exterior body sealing the capacitor element with at least one end face of the anode portion and the cathode portion exposed from at least one outer surface process and
forming an electroless Ag plating layer by performing electroless Ag plating to cover at least one outer surface;
forming an external electrode covering the electroless Ag plating layer to obtain an electrolytic capacitor. The electroless Ag-plated layer may be formed after forming a base layer, which is a non-plated layer, so as to cover at least one outer surface of the exterior body.

(Step of preparing precursor)
The precursor may be prepared by sealing the capacitor element so that at least one end face of the anode part and the cathode part of the capacitor element is exposed from the outer surface of the package. After the capacitor element is sealed with the exterior body, at least one end of the anode portion and the cathode portion is partially removed together with the exterior body to form the outer surface of the exterior body, and the anode portion and the cathode portion are formed. You may prepare by exposing at least one end surface of a part from an outer surface.

When the outer casing is partially removed, for example, after sealing with the outer casing, the end surface of the first portion of the anode body of the capacitor element is formed and exposed from the outer casing. More specifically, on the end side of the first portion of the anode body of the capacitor element, at least the anode body is partially removed together with the outer casing, so that at least the end face of the first end of the anode body is exposed from the outer casing. Let As a method of exposing the end face of the first end portion from the exterior body, for example, after covering the capacitor element with the exterior body, the exterior body is covered so that the end of the anode body on the first portion side is exposed from the exterior body. A method of polishing the surface or cutting off a part of the exterior body can be used. Also, a portion of the first portion that does not include the porous portion may be cut off together with a portion of the exterior body. In this case, the end face that does not include the porous portion and is not formed with the natural oxide film can be easily exposed from the outer surface of the exterior body, and the resistance between the first portion and the external electrode is small and reliable. A connection state with high reliability can be obtained. Dicing is preferable as a method for cutting the outer package. When the outer package is cut by dicing, the surface roughness of the cut surface is increased compared to polishing, etc., and the anchor effect of the electroless Ag plating layer can be further enhanced, resulting in higher adhesion. By partially cutting the outer package, the exposed end surface of the first end of the first portion appears on the cut surface. At least one of the cut surfaces becomes the first outer surface. In addition, in a plurality of stacked capacitor elements, if there are two kinds of capacitor elements with the first portions having different orientations, when a part of the first part is cut off together with a part of the exterior body, it is cut at two places. There is a need to. One of the two cut surfaces is the first outer surface, and the other is the second outer surface opposite to the first outer surface.

When the capacitor element (or a plurality of laminated capacitor elements) includes a metal foil in the cathode extraction layer, the metal foil may be partially removed together with the outer package to expose the end face of the metal foil from the outer package. . As a method for exposing the end face of the metal foil from the outer package, the same method as in the case of exposing the end face of the anode part on the first end side from the outer package can be used. The outer surface where the end surface of the metal foil is exposed is preferably different from the outer surface where the end surface on the first end side of the anode portion is exposed. By appropriately designing the shapes of the anode portion and the metal foil, the end surface of the metal foil and the end surface of the anode portion on the first end side may be exposed at different locations on the same outer surface.

On the end side of the capacitor element (or a plurality of laminated capacitor elements), the anode part and the insulating member are partially removed together with the outer package, and the end surface of the first end side and the end surface of the insulating member are removed from the outer package. It may be exposed from the outside. In this case, the anode part and the insulating member are each formed with flush end faces exposed from the exterior body. Thereby, the end face of the anode portion and the end face of the insulating member which are flush with the surface of the exterior can be easily exposed from the exterior. Further, when insulating spacers are arranged between at least one of the ends of adjacent anode portions and between the ends of adjacent cathode portions on the end side of a plurality of laminated capacitor elements, The anode portion or the cathode portion and the spacer may be partially removed together with the exterior body to expose the end face of the anode portion or the cathode portion and the end face of the spacer from the outer surface of the exterior body.

When the end face of the anode portion (first end portion) where the natural oxide film is not formed (and the end face of the metal foil included in the cathode portion) is exposed from the outside by partial removal of the above-mentioned exterior body, etc., the anode A connection state with low resistance and high reliability is easily obtained between the portion (more specifically, the first portion) and the external electrode, and between the metal foil included in the cathode portion and the external electrode.

When an electroless Ag plating layer is formed on the outer surface of the exterior body without forming a base layer, the outer surface may be washed to remove dirt such as grease. Moreover, the outer surface may be subjected to a hydrophilic treatment. Hydrophilization treatment may be performed after washing treatment. For the cleaning treatment and hydrophilization treatment, a known method that is performed as a pretreatment for an electroless Ag plating layer can be employed. When the end face of the separation layer or the end face of the insulating spacer is exposed from the outer surface of the outer package, these end faces may also be subjected to the above-described cleaning treatment and hydrophilization treatment.

(Step of forming first plating layer)
The method for manufacturing an electrolytic capacitor may include forming a first plating layer so as to cover the exposed end face of the anode portion or the cathode portion. The step of forming the first plating layer is performed prior to the step of forming the base layer and the step of forming the electroless Ag plating layer. The first plating layer or each plating layer constituting the first plating layer may be formed by a known method.

(Step of forming base layer)
The underlayer is formed, for example, by applying a coating agent containing resin. The resin contained in the coating agent is selected from the resins exemplified for the underlayer. A coating film formed by coating may be solidified or cured (or semi-cured) by drying or heating, if necessary.

The surface of the base layer may be washed to remove dirt such as grease. Moreover, the surface of the underlayer may be subjected to hydrophilic treatment. Hydrophilization treatment may be performed after washing treatment. For the cleaning treatment and hydrophilization treatment, a known method that is performed as a pretreatment for an electroless Ag plating layer can be employed.

In the case of forming the base layer, from the viewpoint of ensuring high conductivity, the base layer includes the end face exposed from the outer surface of the anode part or the cathode part and the area other than the surface of the first plating layer (for example, the exterior It is preferably formed in an insulating region such as the outer surface of the body). More specifically, the base layer does not cover the end surface of the anode part or the cathode part exposed from the outer surface of the exterior body and the surface of the first plating layer, and does not cover the outer surface of the exterior body (insulating separator or spacer is If exposed, it is preferably formed so as to cover these exposed portions and the entire outer surface of the exterior body (that is, the surface of the insulating portion). In this case, the underlying layer is formed, for example, in a state in which the exposed end face of the anode part or the cathode part or the surface of the first plating layer is masked.

(Step of forming electroless Ag plating layer)
The electroless Ag plating layer is formed so as to cover the outer surface of the exterior body. The end face of the anode portion or the cathode portion exposed from the outer surface may be directly covered with the electroless Ag plating layer (for example, it may be covered with the electroless plating layer without an underlying layer). When forming the first plating layer, an electroless Ag plating layer is formed so as to cover the first plating layer and the outer surface of the exterior body. The electroless plated layer preferably covers the surface of the first plated layer without the underlayer.

The electroless Ag plating layer is formed, for example, by a reduction type electroless Ag plating method. The electroless Ag plating layer may be formed by a known method, for example.

It is preferable to form a silver mirror-plated layer as an electroless Ag-plated layer by performing silver mirror plating so as to cover the outer surface of the exterior body. Since the silver mirror-plated layer is dense, a higher anchor effect can be obtained. Therefore, the adhesion between the exterior body and the external electrodes is further improved, and the reliability of the electrolytic capacitor can be further improved.

A silver mirror-plated layer is formed, for example, by a known procedure. The silver mirror-plated layer may be formed, for example, by applying a silver mirror-plating solution containing a silver ammonia solution and a reducing agent to at least the outer surface of the exterior body or a base layer formed on the outer surface. At this time, the silver mirror plating solution is also applied to the end face of the anode part or the cathode part exposed from the outer surface of the package, or the surface of the first plating layer. In addition, when the separation layer or spacers are exposed from the outer surface of the package, the silver mirror plating solution is also applied to the end faces of these. The silver mirror-plated layer may be formed, for example, by using two liquids, an ammoniacal silver nitrate solution and a solution containing a reducing agent and an alkaline component. By mixing the two liquids, an oxidation-reduction reaction proceeds and metallic silver is deposited to form a silver mirror-plated layer. For example, the two liquids may be mixed and applied to the outer surface or the underlying layer, or the two liquids may be applied separately so that the two liquids are mixed on the outer surface or the underlying layer. The application of each of the silver mirror plating solution and the two solutions can be performed using, for example, spray coating. Examples of reducing agents include glucose, aldehyde compounds (glyoxal, etc.), hydrazine compounds, and the like. The silver mirror plating solution and each solution of the two solutions may contain known additives. The silver mirror-plated layer may be washed with deionized water or the like, if necessary.

(Step of forming external electrodes)
In this step, an external electrode is formed so as to cover the electroless Ag plating layer. This electrically connects at least one of the anode portion and the cathode portion to the external electrode. Thus, an electrolytic capacitor with external electrodes is obtained.

When the external electrode includes a metal layer (such as a plating layer), the metal layer is formed by, for example, electroplating, electroless plating, sputtering, vacuum deposition, chemical vapor deposition (CVD), cold spraying, thermal spraying, and the like. may be formed using the film forming technique of

The metal layer may be formed so as to be in contact with the electroless Ag plating layer. Also, the external electrode may include a conductive paste layer (or a conductive resin layer) covering the electroless Ag plating layer and a metal layer covering the conductive paste layer. In this case, a conductive paste layer is formed prior to forming the metal layer.

The conductive paste layer may be formed, for example, by applying a conductive paste containing conductive particles, a resin material, and optionally a dispersion medium to the surface of the electroless Ag plating layer. As for the conductive particles and the resin material, the description of the conductive paste layer can be referred to. Dispersion media include, for example, water, organic solvents, and mixed solvents thereof. The conductive paste may contain additives such as surfactants and dispersants, if necessary.

　The application of the conductive paste is not particularly limited, and can be performed by a dipping method, a transfer method, a printing method, a dispensing method, or the like. A coating film formed by coating is usually solidified by drying or heating. When the conductive paste contains a curable resin or a composition thereof, the resin material is cured by heating or the like. Thus, a conductive paste layer (in other words, a conductive resin layer) covering the electroless Ag plating layer is formed.

The external electrode is formed on the outer surface of the exterior body where at least one end face of the anode part and the cathode part is exposed. For example, when the end face of the anode part is exposed from the first outer surface, the first outer electrode may be formed so as to cover the first outer surface. When the end face of the cathode portion is exposed from the second outer surface, the second outer electrode may be formed so as to cover the second outer surface. When the end faces of the anode portions of some of the stacked capacitor elements are exposed from the first outer surface and the end faces of the remaining anode portions are exposed from the second outer surface opposite to the first outer surface, the first A first external electrode may be formed to cover the outer surface, and a third external electrode may be formed to cover the second outer surface. The end faces of the cathode portions of the plurality of laminated capacitor elements may be exposed from an outer surface other than the first outer surface and the second outer surface (for example, the third outer surface). In this case, the second external electrode is formed to cover the third external surface. An electroless Ag plating layer is formed in at least one portion between each outer surface and the external electrode. From the viewpoint of ensuring higher reliability, it is preferable to form an electroless Ag plating layer entirely between each outer surface and the external electrodes.

(Other processes)
The method for manufacturing an electrolytic capacitor may include the steps of forming a capacitor element and sealing the capacitor element with an outer package. Moreover, the manufacturing method may include a step of stacking a plurality of capacitor elements. In this case, in the sealing step, the laminated plural capacitor elements are sealed with the outer package. In the sealing step, sealing may be performed so that at least one end surface of the anode portion and the cathode portion is exposed from the outer surface of the exterior body. Alternatively, after the sealing step, a step of exposing at least one end surface of the anode portion and the cathode portion from the outer surface of the exterior body may be performed. For each step, the description of each configuration of the electrolytic capacitor can be referred to.

Hereinafter, the structure of the electrolytic capacitor of the present disclosure will be described more specifically by taking several embodiments as examples with reference to the drawings. However, the electrolytic capacitor of the present disclosure is not limited to only the following embodiments.

FIG. 1 is a cross-sectional view schematically showing the structure of an electrolytic capacitor according to one embodiment of the present disclosure. 2 is a cross-sectional view showing the structure of a capacitor element that constitutes the electrolytic capacitor of FIG. 1. FIG.

As shown in FIG. 1, an electrolytic capacitor 100 includes a plurality of laminated capacitor elements 10, an outer package 14 that seals the capacitor elements 10, a first external electrode 21, and a second external electrode 22. . In the illustrated example, a plurality of laminated capacitor elements 10 are supported by a substrate 17 .

Each capacitor element 10 includes an anode body 3 as an anode portion and a cathode portion 6 . Anode body 3 is, for example, an anode foil. Anode body 3 has porous portion 5 on its surface, and a dielectric layer (not shown) is formed on at least a part of porous portion 5 . Cathode part 6 covers at least part of the dielectric layer. Cathode section 6 includes solid electrolyte layer 7 and cathode extraction layer 19 .

One end (first end) 1A of the capacitor element 10 is not covered with the cathode portion 6, and the anode body 3 is exposed. The other end (second end) 2A of capacitor element 10 is covered with cathode portion 6 . A portion of anode body 3 covered with cathode portion 6 (in particular, solid electrolyte layer 7 ) is referred to as second portion 2 , and the remaining portion is referred to as first portion 1 . The first part 1 is not covered with the cathode part 6 of the anode body 3 . The end of the first portion 1 is the first end 1A, and the end of the second portion 2 is the second end 2A.

In the illustrated example, the second portion 2 has a core portion 4 and a porous portion 5 formed on the surface of the core portion 4 . The first portion 1 may or may not have the porous portion 5 on its surface. The dielectric layer is formed along at least the surface of the porous portion 5 formed in the second portion 2 . At least part of the dielectric layer covers the inner wall surfaces of the pores of the porous portion 5 and is formed along the inner wall surfaces.

The cathode section 6 includes a solid electrolyte layer 7 that covers at least part of the dielectric layer, and a cathode extraction layer 19 that covers at least part of the solid electrolyte layer 7 . The surface of the dielectric layer has an uneven shape corresponding to the shape of the surface of anode body 3 . The solid electrolyte layer 7 is formed, for example, so as to fill such unevenness of the dielectric layer. The cathode extraction layer 19 includes, for example, a first layer 8 such as a carbon layer covering at least a portion of the solid electrolyte layer 7, and a metal foil 20 as a second layer covering at least a portion of the first layer 8. may

The metal foil 20 is interposed between the second portions 2 of the capacitor elements 10 adjacent in the stacking direction. Metal foil 20 constitutes a part of cathode portion 6 of capacitor element 10 and is shared between capacitor elements 10 adjacent in the stacking direction. A conductive adhesive layer 9 may be interposed between the metal foil 20 and the capacitor element 10 . A conductive adhesive, for example, is used for the adhesive layer 9 . The adhesion layer 9 contains silver, for example.

An insulating separation layer (or insulating member) 12 may be formed so as to cover the surface of the anode body 3 at least in a portion adjacent to the cathode part 6 among the regions of the anode body 3 not facing the cathode part 6 . good. This restricts contact between cathode portion 6 and the exposed portion (first portion 1 ) of anode body 3 . The separation layer 12 is, for example, an insulating resin layer.

The exterior body 14 has a substantially rectangular parallelepiped outer shape, and the electrolytic capacitor 100 also has a substantially rectangular parallelepiped outer shape. In the illustrated example, the exterior body 14 has a first outer surface 14a and a second outer surface 14b opposite to the first outer surface 14a. The end surface of first end portion 1A of anode body 3, which is the anode portion of each capacitor element 10, is exposed at first outer surface 14a. An end surface 20a of the metal foil 20 forming the cathode portion 6 is exposed from the exterior body at the second outer surface 14b.

Each of the end surfaces of the metal foil 20 exposed from the exterior body 14 and the second outer surface 14b are covered with the second external electrodes 22. A first plating layer 15 is formed on the end surface 20a of the metal foil 20 so as to cover the end surface 20a. An electroless Ag plating layer 18 is formed between the second outer surface 14 b and the second external electrode 22 . The electroless Ag plating layer 18 is a dense coating and covers the entire second outer surface 14b with or without an underlying layer. Therefore, a high anchor effect can be obtained with respect to the second outer surface 14b. The second external electrode 22 is electrically connected through the electroless Ag plating layer 18 and the first plating layer 15 to the end surface 20a of the metal foil 20 forming the cathode section 6 .

In the electrolytic capacitor 100 , each of the end surfaces 1 a of the first ends 1 A of the plurality of anode bodies 3 exposed from the exterior body 14 and the first outer surface 14 a are covered with the first external electrode 21 . A first plated layer 15 is formed on the end surface 1a of the anode body 3 so as to cover the end surface 1a. An electroless Ag plating layer 18 is formed between the first outer surface 14 a and the first external electrode 21 . The electroless Ag plating layer 18 covers the entire first outer surface 14a with or without an underlying layer. Therefore, similarly to the above, the electroless Ag plating layer 18 provides a high anchoring effect to the first outer surface 14a. In the illustrated example, the end face of the separation layer 12 is also exposed from the first outer surface 14 a of the outer package 14 , and the exposed end face is also covered with the electroless Ag plating layer 18 . First external electrode 21 is electrically connected to end surface 1 a of anode body 3 via electroless Ag plating layer 18 and first plating layer 15 .

The first plating layer 15 includes at least an electroless Ni plating layer, for example. The first plating layer may include, for example, an electroless Ni plating layer and an electroless Ag plating layer covering the electroless Ni plating layer. The electroless Ag plating layer forming the first plating layer has a composition different from that of the electroless Ag plating layer 18 . Although the illustrated example shows the case where the first plating layer 15 is formed, the present invention is not limited to this case, and the first plating layer 15 may not be formed. In this case, from the viewpoint of ensuring high conductivity, the end surface 1a of the anode body 3 or the end surface 20a of the metal foil 20 is preferably covered with the electroless Ag plating layer 18 without an underlying layer.

The first external electrode 21 includes, for example, a conductive paste layer 21A such as a silver paste layer, and a Ni/Sn plating layer 21B covering the conductive paste layer 21A. Similarly, the second external electrode 22 includes, for example, a conductive paste layer 22A such as a silver paste layer, and a Ni/Sn plating layer 22B covering the conductive paste layer 22A. Each of the

conductive paste layers

21A and 22A covers the electroless Ag plating layer 18 entirely. The conductive paste that forms the

conductive paste layers

21A and 22A has a high affinity with the electroless Ag plating layer 18, and can easily ensure high adhesion. In addition, the electroless Ag plating layer 18 provides a high anchoring effect to the first outer surface 14a or the second outer surface 14b of the package 14 . Therefore, high adhesion between the exterior body 14 and the first external electrode 21 and the second external electrode 22 can be obtained, and the adhesion within the

conductive paste layer

21A or 22A or between the

conductive paste layer

21A or 22A and the member in contact therewith can be achieved. The occurrence of cracks or peeling in is suppressed, and an increase in ESR can be suppressed. Therefore, high reliability of the electrolytic capacitor can be obtained. Although the illustrated example shows the case where the electroless Ag plating layer 18 is interposed between both the first external electrode 21 and the second external electrode 22 and the exterior body 14, the present invention is not limited to this case. An electroless Ag plating layer 18 may intervene on one side.

The first external electrode 21 covers the entire first outer surface 14a of the exterior body 14, and also covers a third outer surface perpendicular to the first outer surface 14a and part of the substrate 17 on the first outer surface 14a side. Similarly, the second external electrode 22 covers the entire second outer surface 14b, and also covers a third outer surface 14c perpendicular to the second outer surface 14b and part of the substrate 17 on the second outer surface 14b side. Such a configuration can further enhance the adhesion between the first external electrode 21 and the first outer surface 14a and between the second external electrode 22 and the second outer surface 14b. A first external electrode 21 and a second external electrode 22 covering part of the substrate 17 are exposed at the bottom surface of the electrolytic capacitor 100 . These exposed portions constitute the anode and cathode terminals of electrolytic capacitor 100, respectively.

The separation layer 12 does not necessarily have to be exposed from the exterior body 14 as in the illustrated example, and only the end surface 1a of the anode body 3 may be exposed. The exposed end surface 1 a may be composed of only the core portion 4 or may include the porous portion 5 . It is advantageous for end face 1 a not to include porous portion 5 in terms of preventing air from entering capacitor element 10 .

FIG. 3 is a cross-sectional view schematically showing the structure of an electrolytic capacitor according to another embodiment of the present disclosure. The electrolytic capacitor 101 shown in FIG. 3 includes a plurality of stacked capacitor elements 10, an exterior body 14 that seals the capacitor elements 10, a first external electrode 21, a second external electrode 22, and a third external electrode 23. , provided. The first external electrode 21 and the third external electrode 23 are electrically connected to the anode body 3 which is the anode portion, and the second external electrode 22 is electrically connected to the metal foil 20 constituting the cathode portion 6. connected to. FIG. 3 differs from FIGS. 1 and 2 only in the lamination direction of capacitor element 10, the arrangement of metal foil 20, and the arrangement of external electrodes.

In FIG. 3, the plurality of capacitor elements 10 are arranged such that the first portion 1 of the anode body 3 faces the second portion 2 in one direction (the direction toward the first outer surface 14a of the package 14). and a second capacitor element 10b in which the first portion 1 of the anode body 3 faces the second portion 2 in the direction opposite to that of the first capacitor element 10a (the direction toward the second outer surface 14b of the package 14). have. The end surface 1a of the first end portion 1A of the first capacitor element 10a is exposed from the exterior body at the first outer surface 14a. The end surface 1a of the first end portion 1A of the second capacitor element 10b is exposed from the exterior body at the second outer surface 14b opposite to the first outer surface 14a. A first plated layer 15 is formed on each end face 1a. A first external electrode 21 is formed to cover the first outer surface 14a, and a third external electrode 23 is formed to cover the second outer surface 14b. Electroless Ag plating layers 18 are interposed between the first outer electrode 21 and the first outer surface 14a and between the third outer electrode 23 and the second outer surface 14b. The first external electrode is electrically connected to end surface 1a of anode body 3 of first capacitor element 10a via first plating layer 15 and electroless Ag plating layer 18 . Similarly, the third external electrode is electrically connected to end face 1a of anode body 3 of second capacitor element 10b via first plating layer 15 and electroless Ag plating layer . The first external electrode 21 covers the entire first external surface 14a, and also partially covers the third external surface 14c intersecting the first external surface 14a and the surface of the substrate 17 on the first external surface 14a side. Similarly, the third external electrode 23 covers the entire second external surface 14b, and also partially covers the surfaces of the substrate 17 and the third external surface 14c intersecting the second external surface 14b on the side of the first external surface 14a.

On the other hand, although not shown, at least one of a fourth outer surface intersecting the first outer surface 14a and the second outer surface 14b and a fifth outer surface opposite to the fourth outer surface, the cathode of the first capacitor element 10a and the second capacitor element 10b An end surface of the metal foil 20 forming the portion 6 is exposed from the exterior body 14 and electrically connected to the second external electrode 22 . The exposed end face of the metal foil 20 may be covered with the first plating layer 15 . An electroless Ag plating layer 18 may be interposed between the second external electrode 22 and at least one of the fourth outer surface and the fifth outer surface. The second external electrode 22 covers at least one of the fourth outer surface and the fifth outer surface, and also continuously covers part of the first outer surface of the surface of the substrate 17 .

Thus, the first external electrode 21 and the third external electrode exposed on the bottom surface of the electrolytic capacitor 101 (the surface of the substrate 17) constitute an anode terminal, and the second external electrode constitutes a cathode terminal.

In the example of FIG. 3, the first capacitor elements 10a and the second capacitor elements 10b are alternately laminated. However, this is not the only case, and the electrolytic capacitor may include at least one of the adjacently stacked first capacitor element 10a and the adjacently stacked second capacitor element 10b.

[Example]
EXAMPLES The present disclosure will be specifically described below based on examples and comparative examples, but the present disclosure is not limited to the following examples.

<<Electrolytic capacitors E1 to E3 and C1>>
Electrolytic capacitors (electrolytic capacitors E1 to E3 and C1) including seven stacked capacitor elements 10 as shown in FIG. 1 were produced in the following manner, and their characteristics were evaluated. In E1 to E3, a silver mirror-plated layer was formed as the electroless Ag-plated layer 18 . However, in E1, the first plating layer 15 was not formed. In E2, only an electroless Ni plating layer was formed as the first plating layer. In E3, as first plating layers, an electroless Ni-plating layer covering the end surface 1a of the anode body 3 and the end surface 20a of the metal foil 20 and an electroless Ag-plating layer covering the electroless Ni-plating layer were formed. This electroless Ag plating layer is different from the silver mirror plating layer. In C1, the same first plating layer as in E3 was formed, and the electroless Ag plating layer 18 was not formed. The configuration of capacitor element 10 is the same as the configuration of capacitor element 10 in FIG.

(1) Preparation of Anode Body 3 Anode body 3 was produced by roughening both surfaces of an aluminum foil (thickness: 100 μm) as a base material by etching.

(2) Formation of Dielectric Layer The second portion of anode body 3 was immersed in a chemical solution, and a DC voltage of 7 V was applied for 20 minutes to form a dielectric layer containing aluminum oxide.

(3) Formation of Solid Electrolyte Layer 7 Separation layer 12 was formed on first end portion 1A of anode body 3 . A solid electrolyte layer 7 containing a conductive polymer was formed so as to cover the second portion of anode body 3 on which separation layer 12 was formed.

(4) Formation of cathode extraction layer 19 and lamination of capacitor element 10 Anode body 3 obtained in (3) above is immersed in a dispersion of graphite particles in water, removed from the dispersion, and dried by heating. Thus, a carbon layer was formed as the first layer 8 on at least the surface of the solid electrolyte layer 7 .

An aluminum foil (thickness of 20 μm) is interposed between the first layers 8 of the adjacent elements so that the first layers 8 overlap each other. and laminated. At this time, the metal foil 20 of the second layer was attached to the adjacent first layer 8 via the adhesive layer 9 using a conductive adhesive. In this way, the cathode extraction layer 19 including the first layer 8 and the metal foil 20 as the second layer was formed, and the capacitor element 10 including the cathode extraction layer 19 was completed. In each capacitor element 10 , cathode portion 6 includes solid electrolyte layer 7 and cathode extraction layer 19 .

(5) Sealing with exterior body 14 The seven stacked capacitor elements 10 obtained in (4) above are placed on a substrate 17 using a conductive adhesive, and the capacitor elements 10 are molded by molding. An exterior body 14 made of an insulating resin was formed around it. A side portion of the exterior body 14 was cut by dicing to form a first outer surface 14a and a second outer surface 14b. At this time, the exterior body 14 was cut so that the end surface 1a of the anode body 3 of each capacitor element 10 was exposed from the first outer surface 14a and the end surface 20a of the metal foil 20 was exposed from the second outer surface 14b. Thus, a precursor was obtained in which the end surface 1a of the anode body 3 was exposed from the first outer surface 14a and the end surface 20a of the metal foil 20 constituting the cathode portion 6 was exposed from the second outer surface 14b. The first outer surface 14a and the second outer surface 14b of the outer package 14 and the end surface of the separation layer 12 exposed from the first outer surface 14a were subjected to cleaning treatment and hydrophilization treatment.

(6) Formation of Plating Layer (a) Formation of First Plating Layer 15 In E2, E3 and C3, the precursor obtained in (5) is used to form end surface 1a of anode body 3 exposed from first outer surface 14a. An electroless Ni plating solution containing a phosphorus-containing reducing agent was used to form an electroless Ni plating layer (5 μm thick) so as to cover the . In E3 and C3, an electroless Ag plating layer (thickness: 0.3 μm) was formed on the electroless Ni plating layer using a reduced electroless Ag plating solution. In this way, in E2, E3 and C3, the first plating layer 15 composed of the electroless Ni plating layer or the electroless Ni plating layer and the electroless Ag plating layer was formed.

(b) Formation of Electroless Ag Plating Layer 18 A two-liquid type silver mirror plating solution was mixed and spray-coated on the entirety of each of the first outer surface 14a and the second outer surface 14b. Thus, metallic silver was deposited on the entirety of the first outer surface 14a and the second outer surface 14b, thereby forming a silver mirror-plated layer as the electroless Ag-plated layer 18 . After the silver mirror-plated layer was formed, an antiseptic was spray-coated on the surface, allowed to blend in for a while, washed with water, air-dried, and dried by heating.

(7) Formation of first external electrode 21 and second external electrode 22 In E1 to E3, the first external electrode 21 and the second external electrode 21 are formed so as to cover the electroless Ag plating layer 18 obtained in (6)(b) above. External electrodes 22 were formed respectively. In C1, the first external electrode 21 and the second external electrode 22 are respectively formed so as to cover the first plating layer 15 formed in (6)(a) above and the first outer surface 14a and the second outer surface 14b. bottom.

More specifically, a conductive paste containing silver particles and a resin is applied to the electroless Ag plating layer or the outer surface of the exterior body and dried by heating to form

conductive paste layers

21A and 22A having a thickness of 50 μm. formed respectively. Next, the exterior body on which the

conductive paste layers

21A and 22A are formed is immersed in an electrolytic solution for electrolytic Ni plating to perform electrolytic Ni plating. An electrolytic Ni plating layer of 5 μm was formed. Next, the exterior body on which the electrolytic Ni plating layer was formed was immersed in an electrolytic solution for electrolytic Sn plating to perform electrolytic Sn plating, thereby forming an electrolytic Sn plating layer having a thickness of 5 μm. Thus, Ni/

Sn plating layers

21B and 22B were formed. By washing the surface of the plated layer with water and drying it, an electrolytic capacitor having the first external electrode 21 and the second external electrode 22 was obtained. A total of 20 electrolytic capacitors were produced for each example in the same manner.

(8) Evaluation The following evaluation was performed using the obtained electrolytic capacitor.
(a) Initial ESR
Under an environment of 20 ° C., using an LCR meter for 4-terminal measurement, for each of the 20 electrolytic capacitors, the initial ESR (mΩ) at a frequency of 100 kHz was measured, and the average value (mΩ) and standard deviation σ ( mΩ) was obtained.

(b) Adhesion JIS standard: JIS C5101-25: JIS C5101-25: Percent change in capacitance when bending the substrate to which the electrolytic capacitor is fixed in accordance with the 2009 "4.9 Printed board bending resistance" test. (Specifically, the capacity reduction rate) was determined. The test was performed under the following conditions.
Substrate: TAN-01 (size: 100 x 40 x t1.6 mm)
Solder: M705-PLG-32-11 (manufactured by Senju Metal)
Metal mask: MASK-01 (t=0.15mm)
Capacity change rate at deflection amount of 1 mm: ≤ ± 10% (calculation formula: ΔC / C)
JIS C5101-22:2014 (High Dielectric Constant Capacitor) is applied to the rate of change. The measurement was performed three times for each amount of deflection, and the average value was obtained. The deflection amount was changed from 0 mm to 10 mm. The capacity reduction rate (%) was obtained when the capacity when the amount of deflection was 0 mm was defined as 100%, and was used as an index for evaluating adhesion. The larger the capacity reduction rate, the lower the terminal strength, and the lower the adhesion strength (or adhesion) between the exposed end face of the anode portion or the cathode portion and the external electrode. E1 and C1 were evaluated for adhesion.

(c) Barrier property The electrolytic capacitor was subjected to reflow treatment according to IPC/JEDEC J-STD-020D. Specifically, the electrolytic capacitor was preheated at a holding temperature of 150 to 200° C. and a holding time of 180 seconds or less. The preheated electrolytic capacitor was heated at a temperature of 255° C. or higher (maximum temperature of 260° C.) for 30 seconds. The heating at the maximum temperature of 260° C. at this time was within 10 seconds. It was then cooled to 25° C. over 10 minutes and this heating and cooling was repeated two more times (ie a total of 3 times). Next, the capacitance (C ₀ ) of the electrolytic capacitor was measured at 25° C. in the same procedure as in (a) above. Then, the electrolytic capacitor was allowed to stand for 100 hours in a constant temperature bath at 85° C. and 85% RH. The electrolytic capacitor was taken out from the constant temperature bath and cooled to 25° C., and the capacitance (C ₁ ) of the electrolytic capacitor was measured in the same manner as in (a) above. The rate of increase in capacitance (C ₁ −C ₀ ) (%) when C ₀ is 100% was obtained. Note that the rate of increase obtained here is due to moisture and is an apparent rate of increase, so there is a tendency for the measured value to increase as the amount of moisture absorbed by the electrolytic capacitor increases. Therefore, the higher the apparent capacity increase rate, the lower the barrier properties. Evaluation of barrier properties was performed on E1 and C1.

Table 1 shows the adhesion evaluation results. Table 2 shows initial ESR and barrier property evaluation results. In Tables 1 and 2, E1 to E3 are examples and C1 is a comparative example.

As shown in Table 1, in E1 in which the electroless Ag plating layer was formed so as to cover the outer surface of the exterior body, deflection was greater than in C1 in which the external electrodes were formed without forming the electroless Ag plating layer. Even if it becomes large, the capacity reduction rate can be kept low. A scanning electron micrograph of the cross section of the electrolytic capacitor C1 revealed that cracks were formed in the conductive paste layer, and cracks or cracks were formed between the conductive paste layer and the exposed end faces of the outer casing and the anode or cathode. Peeling was confirmed. Therefore, it is considered that C1 is more difficult to extract the capacity than E1, and the capacity decrease rate is large when the deflection is large. In other words, in E1, cracking or peeling as in C1 was reduced, and high adhesion between the exposed end faces of the anode and cathode portions and the external electrodes was obtained.

As shown in Table 2, when an electroless Ag plating layer is formed so as to cover the outer surface of the exterior body, the initial ESR can be kept low, and excellent electrical connection between the anode part or the cathode part and the external electrode can be achieved. can be ensured (compare C1 with E1-E3). Since high adhesion can be ensured between the ends of the anode part or the cathode part and the external electrode, the variation (standard deviation) of ESR between individuals can be reduced. A first plating layer may be provided on the exposed end of the anode part or the cathode part. Inter-individual ESR variability can be suppressed (compare E1 with E2 and E3). Also, E1 provided a higher barrier property than C1. This is thought to be because E1 suppresses cracking or peeling as in C1, so even if the electrolytic capacitor is exposed to a high-temperature, high-humidity environment for a long period of time, it is less susceptible to the effects of humidity. .

Although the present invention has been described in terms of its presently preferred embodiments, such disclosure should not be construed as limiting. Various alterations and modifications will no doubt become apparent to those skilled in the art to which the invention pertains after reading the above disclosure. Therefore, the appended claims are to be interpreted as covering all variations and modifications without departing from the true spirit and scope of the invention.

The electrolytic capacitor according to the present disclosure has high adhesion between the end face exposed from the outer surface of the exterior body of the anode part or the cathode part and the external electrode, so that the ESR can be kept low and the variation in ESR between individuals can be reduced. . Therefore, the electrolytic capacitor according to the present disclosure can be used in various applications that require high reliability.

1 First part (anode lead-out part)
1A first end 1a end face of first end 2 second portion (cathode forming portion)
2A second end portion 2a end face of second end portion 3 anode body 4 core portion 5 porous portion 6 cathode portion 7 solid electrolyte layer 8 first layer 9 adhesive layer 10 capacitor element 10a first capacitor element 10b second capacitor element 12 Separation layer (insulating material)
14 exterior body 14a first outer surface of exterior body 14b second exterior surface of exterior body 14c third exterior surface of exterior body 15 first plating layer 17 substrate 18 electroless Ag plating layer 19 cathode extraction layer 20 metal foil 20a end surface of

metal foil

21 , 23 first

external electrode

21A, 23A

conductive paste layer

21B, 23B Ni/Sn plating layer 22 second external electrode 22A conductive paste layer 22B Ni/

Sn plating layer

100, 101 electrolytic capacitor

Claims

at least one capacitor element comprising an anode portion and a cathode portion;
an exterior body that seals the capacitor element;
a plurality of external electrodes electrically connected to each of the anode portion and the cathode portion;
at least one end surface of the anode portion and the cathode portion of the capacitor element is exposed from at least one outer surface of the exterior body;
The exposed end surface and the outer surface are covered with the external electrode,
An electroless Ag plating layer covering at least the outer surface is interposed between the external electrode and the outer surface,
The electrolytic capacitor, wherein the electroless Ag plating layer covers the outer surface with or without an underlying layer that is a non-plating layer.
The electrolytic capacitor according to claim 1, wherein the electroless Ag plating layer includes a silver mirror plating layer.
3. The electrolytic capacitor according to claim 1, wherein said external electrode includes a conductive paste layer covering said electroless Ag plating layer and a Ni/Sn plating layer covering said conductive paste layer.
The electrolytic capacitor according to any one of claims 1 to 3, wherein the electroless Ag plating layer covers the exposed end face without interposing the underlying layer.
The electrolytic capacitor according to any one of claims 1 to 3, wherein a first plating layer is interposed between the exposed end face and the electroless Ag plating layer.
The electrolytic capacitor according to claim 5, wherein the first plating layer contains at least one selected from the group consisting of Ag, Ni, Cu and Zn.
The electrolytic capacitor according to claim 5 or 6, wherein the first plating layer includes a plurality of plating layers.
an end surface of the anode portion is exposed from the first outer surface of the outer package and covered with a first external electrode together with the first outer surface;
an end face of the cathode portion is exposed from the second outer surface of the exterior body and covered with a second external electrode together with the second outer surface;
The electroless Ag plating layer is interposed between the first outer surface and the first external electrode covering the first outer surface,
8. The electrolytic capacitor according to claim 1, wherein said electroless Ag plating layer is interposed between said second outer surface and said second outer electrode covering said second outer surface.
The electrolytic capacitor according to any one of claims 1 to 7, comprising a plurality of stacked capacitor elements.
an end surface of the anode portion of each of the plurality of capacitor elements is exposed from a first outer surface of the exterior body and covered with a first external electrode together with the first outer surface;
an end surface of the cathode portion of each of the plurality of capacitor elements is exposed from a second outer surface of the exterior body and covered with a second external electrode together with the second outer surface;
The electroless Ag plating layer is interposed between the first outer surface and the first external electrode covering the first outer surface,
10. The electrolytic capacitor according to claim 9, wherein said electroless Ag plating layer is interposed between said second outer surface and said second outer electrode covering said second outer surface.
an end surface of the anode portion of some of the capacitor elements is exposed from the first outer surface of the outer package and covered with a first external electrode together with the first outer surface;
an end surface of the anode portion of the remaining capacitor element is exposed from a second outer surface opposite to the first outer surface, and is covered with a third external electrode together with the second outer surface;
The electroless Ag plating layer is interposed between the first outer surface and the first external electrode covering the first outer surface,
10. The electrolytic capacitor according to claim 9, wherein said electroless Ag plating layer is interposed between said second outer surface and said third outer electrode covering said second outer surface.
The electrolytic capacitor according to any one of claims 1 to 11, wherein the electroless Ag plating layer has a thickness of 0.01 µm or more and 10 µm or less.
A precursor comprising: at least one capacitor element including an anode portion and a cathode portion; and an exterior body sealing the capacitor element with at least one end surface of the anode portion and the cathode portion exposed from at least one outer surface. a step of preparing
forming an electroless Ag plating layer by performing electroless Ag plating so as to cover the at least one outer surface of the exterior body;
forming an external electrode covering the electroless Ag plating layer to obtain an electrolytic capacitor.
Forming a first plating layer so as to cover the end face,
14. The method of manufacturing an electrolytic capacitor according to claim 13, wherein in the step of forming the electroless Ag plating layer, the electroless Ag plating is performed so as to cover the outer surface of the at least one of the first plating layer and the exterior body. .
13. In the step of forming the electroless Ag plating layer, silver mirror plating is performed so as to cover the at least one outer surface of the exterior body to form a silver mirror plating layer as the electroless Ag plating layer. 15. The method for producing an electrolytic capacitor according to 14.
In a region other than the exposed end surface of the at least one outer surface of the exterior body, the lower layer is formed on the outer surface so that a base layer, which is a non-plating layer, is interposed between the outer surface and the electroless Ag plating layer. 16. The method for manufacturing an electrolytic capacitor according to any one of claims 13 to 15, wherein a stratum is formed.
With the exposed end face masked, in a region other than the exposed end face of the at least one outer surface of the exterior body, a base layer that is a non-plating layer is provided between the outer surface and the electroless Ag plating layer. 14. The method of manufacturing an electrolytic capacitor according to claim 13, wherein the underlayer is formed on the outer surface so as to be interposed.