CROSS REFERENCE TO RELATED APPLICATIONS

This application is entitled to and claims the benefit of Japanese Patent Application No. 2019-081118, filed on Apr. 22, 2019, the disclosure of which including the specification, drawings and abstract is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a solid electrolytic capacitor, and a method for producing the same.

BACKGROUND ART

There is a demand for capacitors having an excellent impedance characteristic in a high-frequency region in accordance with development of high frequency electronic devices. To meet this demand, various solid electrolytic capacitors using a conductive polymer having high electrical conductivity as a solid electrolyte are studied (see, for example, Patent Literature (hereinafter, referred to as PTL) 1).

In recent years, downsizing and increasing in capacity are strongly desired for a solid electrolytic capacitor used in the vicinity of a CPU (central processing unit) of a personal computer and the like. In addition, low ESR (equivalent series resistance) corresponding to high frequency, low ESL (equivalent series inductance) excellent in noise25removal and transient response, and the like are required. Various studies are performed for satisfying these requirements.

A description will be herein given of a multilayer solid electrolytic capacitor disclosed in PTL 1 with reference toFIG. 3.FIG. 3is a side-surface cross-sectional view of the multilayer solid electrolytic capacitor disclosed in PTL 1.

InFIG. 3, solid electrolytic capacitor31includes multilayer unit33, exterior43, anode-side external electrode47, and cathode-side external electrode48.

Multilayer unit33is formed by staking a plurality of capacitor elements32. Capacitor elements32each include: valve action metal substrate34including core35and rough surfaces36formed along surfaces of core35; dielectric coating37formed on rough surfaces36; solid electrolyte layer39formed on dielectric coating37; and current collector layer40formed on solid electrolyte layer39. Current collector layers40of a plurality of capacitor elements32are electrically connected to each other.

Exterior43has an electrical insulation property and covers multilayer unit33in a state where one end face38of valve action metal substrate34is exposed on first end face44.

Anode-side external electrode47is provided on or above first end face44of exterior43and on or above a portion of each of an upper surface and a lower surface adjacent to the end face of exterior43. Further, anode-side external electrode47is electrically connected to core35of valve action metal substrate34

Cathode-side external electrode48is provided on or above second end face45opposite to first end face44of exterior43. Further, cathode-side external electrode48is electrically connected to current collector layer40.

Anode-side external electrode47includes first conductive layer49, second conductive layer50and third conductive layer51. First conductive layer49is formed so as to be in direct contact with core35of valve action metal substrate34and electrically connects between cores35of valve action metal substrates34of adjacent capacitor elements3. Further, first conductive layer49is formed by a dry process, such as sputtering, so as to cover one end faces38of valve action metal substrates34and the entirety of first end faces44of exterior43around one end faces38while extending to a portion of each of an upper surface and a lower surface adjacent to first end face44.

In solid electrolytic capacitor31having the configuration described above, it is made possible to prevent water from entering rough surface36of valve action metal substrates34and/or moisture from entering between rough surface36and exterior43. Further, second conductive layer50is formed on first conductive layer49, so that the adhesion strength can be improved.

CITATION LIST

Patent Literature

PTL 1Japanese Patent No. 6233410

SUMMARY OF INVENTION

Technical Problem

In solid electrolytic capacitor31of PTL 1, core35exposed to one end face38of valve action metal substrate34is formed of a metal foil, such as an Al (aluminum) foil. Further, rough surface36is formed by application of an etching process on the surface of the metal foil, and dielectric coating37is formed on rough surface36.

In addition, when first conductive layer49is formed on one end face38of valve action metal substrate34by a dry process, such as sputtering, dielectric coating37on rough surface36and exterior43composed of a resin material are only mechanically attached to each other using an anchor effect rather than metal bonding having a high bonding strength.

Thus, the bonding strength between dielectric coating37and exterior43is extremely low, and only application of a low pressure at the time of formation of second conductive layer50and third conductive layer51causes peeling.

Further, there arises a concern that moisture enters from the porous structure of rough surface36, due to peeling, at the interface formed by the anchor effect between first conductive layer49and rough surface36.

Likewise, entry of moisture into the entirety of capacitor elements32possibly occurs due to peeling, at the interface between first conductive layer49and exterior43.

Accordingly, there arises a problem in that a quality problem occurs when capacitor elements32are damaged due to expansion between capacitor elements32caused by evaporation of the moisture contained in solid-state electrolytic capacitor31at a high temperature during mounting of solid-state electrolytic capacitor31on a printed circuit board.

An object of an aspect of the present disclosure is to provide a solid electrolytic capacitor with high reliability while maintaining suitable electrical characteristics, and a method for producing the same.

Solution to Problem

A solid electrolytic capacitor according to one aspect of the present disclosure is a capacitor in which a stacked plurality of capacitor elements are covered by an exterior body, in which the stacked plurality of capacitor elements each include: an anode body; a dielectric layer provided on a surface of the anode body and including a plurality of voids; a solid electrolyte layer provided on a surface of the dielectric layer; a cathode body provided on a surface of the solid electrolyte layer; and an insulating layer that includes an insulating resin insulating and separating between an anode side and a cathode side, the insulating layer being provided on the anode side of the dielectric layer, in which the plurality of voids included in the insulating layer are filled with the insulating resin, and an anode portion adhesive resin is provided between a plurality of the insulating layers adjacent to each other.

A method for producing a solid electrolytic capacitor, according to one aspect of the present disclosure includes: element forming of forming a plurality of capacitor elements each including: an anode body; a dielectric layer provided on a surface of the anode body and including a plurality of voids; a solid electrolyte layer provided on a surface of the dielectric layer; a cathode body provided on a surface of the solid electrolyte layer; and an insulating layer that includes an insulating resin insulating and separating between an anode side and a cathode side, the insulating layer being provided on the anode side of the dielectric layer; stacking the plurality of capacitor elements via a conducive material and an anode portion adhesive resin; sealing for forming an exterior body that covers the plurality of capacitor elements; exposing for forming an anode-end face in which an anode terminal portion being an end portion of the anode body, an end portion of the insulating layer, and an end portion of an anode portion adhesive resin are exposed from the exterior body; contact layer forming for forming a contact layer on the anode terminal portion; first electrode forming for forming an anode-side electrode layer that covers the anode end face including the contact layer, and forming a cathode-side electrode layer electrically connected to the cathode body; second electrode forming for forming an anode-side external electrode that covers the anode-side electrode layer, and forming a cathode-side external electrode that covers the cathode-side electrode layer, in which in the element forming, the plurality of voids included in the insulating layer are filled with the insulating resin, and in the stacking, the anode portion adhesive resin is provided between a plurality of the insulating layers adjacent to each other.

Advantageous Effects of Invention

According to the present disclosure, it is made possible to achieve high reliability while maintaining suitable electrical properties in solid electrolytic capacitors.

