US-12626869-B2 - Solid electrolytic capacitor

US12626869B2US 12626869 B2US12626869 B2US 12626869B2US-12626869-B2

Abstract

A solid electrolytic capacitor includes an element stack, an anode terminal, a cathode terminal, and an exterior member. The element stack includes a plurality of capacitor elements stacked on each other, and a conductive material interposed between two adjacent capacitor elements in the plurality of capacitor elements. Each of the plurality of capacitor elements includes an anode part and a cathode part, and the conductive material is disposed on the cathode part. The anode terminal is connected to the anode part. The cathode terminal is connected to the cathode part via a conductive paste. The cathode terminal has a facing surface facing a tip end of the element stack with a gap interposed between the facing surface and the tip end, and at least a part of the gap is filled with a sealing material.

Inventors

Yuichiro Yamada
Katsuhiro OGASAWARA
Atsushi Tanaka
Masahiro Sato
TOMOKI SUGIMOTO

Assignees

PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20210827
Priority Date: 20200917

Claims (18)

1 . A solid electrolytic capacitor comprising: an element stack including a plurality of capacitor elements stacked on each other and a conductive material disposed between two adjacent capacitor elements in the plurality of capacitor elements, the plurality of capacitor elements including a first capacitor element and a second capacitor element, each of the first capacitor element and the second capacitor element including an anode part and a cathode part, the conductive material being disposed on the cathode part; an anode terminal connected to the anode part; a cathode terminal connected to the cathode part via a conductive paste; and an exterior member that covers the element stack, the anode terminal, and the cathode terminal in a state where a part of each of the anode terminal and the cathode terminal is exposed, wherein: the first capacitor element is closest to a connection part of the cathode terminal, the connection part connecting to the element stack, the cathode terminal has a facing surface facing a tip end of the element stack with a gap between the facing surface and the tip end, in a stacking direction of the plurality of capacitor elements, which is parallel to a normal direction of an upper surface of the connection part of the cathode terminal, a height of the facing surface from the upper surface of the connection part of the cathode terminal is greater than a height of an upper surface of the first capacitor element from the upper surface of the connection part of the cathode terminal, at least a part of the gap is filled with a sealing material, the sealing material is made of a same material as the exterior member and continuous from the exterior member, the sealing material contains a filler, and a dimension of gap in a facing direction between the tip end of the element stack and the facing surface is 1.5 times greater than a maximum size of the filler.
2 . The solid electrolytic capacitor according to claim 1 , wherein the conductive paste is not present in a region of the gap, the region being between the facing surface of the cathode terminal and all of the plurality of capacitor elements except the first capacitor element.
3 . The solid electrolytic capacitor according to claim 1 , wherein the conductive material is not in contact with the facing surface in a region of the gap, the region being between the facing surface of the cathode terminal and all of the plurality of capacitor elements except the first capacitor element.
4 . The solid electrolytic capacitor according to claim 1 , wherein the sealing material is filled in a region of the gap, the region being between the facing surface of the cathode terminal and all of the plurality of capacitor elements except the first capacitor element.
5 . The solid electrolytic capacitor according to claim 1 , wherein the sealing material is filled to be continuously present along the stacking direction of the plurality of capacitor elements.
6 . The solid electrolytic capacitor according to claim 1 , wherein the gap is entirely filled with the sealing material.
7 . The solid electrolytic capacitor according to claim 1 , wherein a dimension of the gap is more than or equal to 40 μm.
8 . The solid electrolytic capacitor according to claim 1 , wherein the facing surface of the cathode terminal is inclined with respect to the stacking direction so that a dimension of the gap in a direction parallel to the upper surface of the connection part of the cathode terminal between the facing surface of the cathode terminal and the tip end of the element stack is increased along the stacking direction from the connection part of the cathode terminal.
9 . The solid electrolytic capacitor according to claim 8 , wherein an angle formed by the facing surface and the stacking direction is less than or equal to 30 degrees.
10 . The solid electrolytic capacitor according to claim 1 , wherein: the sealing material is a cured product of a composition containing a main agent and a curing agent, and the main agent contains a first component having a biphenyl skeleton.
11 . The solid electrolytic capacitor according to claim 10 , wherein the first component is a biphenyl aralkyl epoxy resin.
12 . The solid electrolytic capacitor according to claim 10 , wherein the main agent further contains a second component other than the first component.
13 . The solid electrolytic capacitor according to claim 12 , wherein a proportion of the first component in the main agent is more than 50 mass %.
14 . The solid electrolytic capacitor according to claim 1 , wherein a molding shrinkage rate of the sealing material is less than or equal to 0.5%.
15 . The solid electrolytic capacitor according to claim 1 , wherein: a content proportion of the filler in the sealing material is in a range from 80 mass % to 92 mass %, inclusive.
16 . The solid electrolytic capacitor according to claim 1 , wherein the second capacitor element is stacked on the first capacitor element, the anode part of the second capacitor element is stacked on the anode part of the first capacitor element in the stacking direction, the anode terminal includes a connecting part which is connected to the anode part of the first capacitor element, and the connecting part is covered with the exterior member.
17 . The solid electrolytic capacitor according to claim 16 , wherein the connecting part of the anode terminal is connected to a lower surface of the anode part of the first capacitor element, in the stacking direction, the height of the facing surface from the upper surface of the connection part of the cathode terminal is greater than a height of the lower surface of the anode part of the first capacitor element from the upper surface of the connection part of the cathode terminal.
18 . A solid electrolytic capacitor comprising: an element stack including a plurality of capacitor elements stacked on each other and a conductive material disposed between two adjacent capacitor elements in the plurality of capacitor elements, the plurality of capacitor elements including a first capacitor element and a second capacitor element, each of the first capacitor element and the second capacitor element including an anode part and a cathode part, the conductive material being disposed on the cathode part; an anode terminal connected to the anode part; a cathode terminal connected to the cathode part via a conductive paste; and an exterior member that covers the element stack, the anode terminal, and the cathode terminal in a state where a part of each of the anode terminal and the cathode terminal is exposed, wherein: the first capacitor element is closest to a connection part of the cathode terminal, the connection part connecting to the element stack, the cathode terminal has a facing surface facing a tip end of the element stack with a gap between the facing surface and the tip end, in a stacking direction of the plurality of capacitor elements, which is parallel to a normal direction of an upper surface of the connection part of the cathode terminal, a height of the facing surface from the upper surface of the connection part of the cathode terminal is greater than a height of an upper surface of the first capacitor element from the upper surface of the connection part of the cathode terminal, the facing surface of the cathode terminal is inclined with respect to the stacking direction so that a dimension of the gap in a direction parallel to the upper surface of the connection part of the cathode terminal between the facing surface of the cathode terminal and the tip end of the element stack is increased along the stacking direction from the connection part of the cathode terminal, an angle formed by the facing surface and the stacking direction is less than or equal to 30 degrees, at least a part of the gap is filled with a sealing material, and the sealing material is made of a same material as the exterior member and continuous from the exterior member.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a U.S. national stage application of the PCT International Application No. PCT/JP2021/031468 filed on Aug. 27, 2021, which claims the benefit of foreign priority of Japanese patent application No. 2020-156129 filed on Sep. 17, 2020, the contents all of which are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to a solid electrolytic capacitor. BACKGROUND There has been conventionally known a solid electrolytic capacitor including a plurality of capacitor elements each having a cathode part, a cathode terminal connected to the cathode part via a conductive paste, and an exterior member covering these components (for example, Unexamined Japanese Patent Publication No. 2011-091444). In Unexamined Japanese Patent Publication No. 2011-091444, the equivalent series resistance (ESR) of the solid electrolytic capacitor is reduced by connecting the cathode parts of the plurality of capacitor elements with a conductive film. SUMMARY An aspect of the present disclosure relates to a solid electrolytic capacitor. The solid electrolytic capacitor includes an element stack, an anode terminal, a cathode terminal, and an exterior member that covers the element stack, the anode terminal, and the cathode terminal in a state where a part of each of the anode terminal and the cathode terminal is exposed. The element stack includes a plurality of capacitor elements stacked on each other, and a conductive material disposed between two adjacent capacitor elements in the plurality of capacitor elements. Each of the plurality of capacitor elements includes an anode part and a cathode part, and the conductive material is disposed on the cathode part. The anode terminal is connected to the anode part. The cathode terminal is connected to the cathode part via a conductive paste. The cathode terminal has a facing surface facing a tip end of the element stack with a gap between the facing surface and the tip end, and at least a part of the gap is filled with a sealing material. According to the present disclosure, a solid electrolytic capacitor having high airtightness can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view illustrating a configuration of a solid electrolytic capacitor according to the present disclosure. FIG. 2 is a sectional view illustrating a configuration of a capacitor element according to the present disclosure. FIG. 3 is a sectional view illustrating another configuration of the solid electrolytic capacitor according to the present disclosure. FIG. 4 is a sectional view illustrating still another configuration of the solid electrolytic capacitor according to the present disclosure. DESCRIPTION OF EMBODIMENT Prior to the description of exemplary embodiments, problems in the conventional technology will be briefly described below. Solid electrolytic capacitors desirably have structures having excellent airtightness to avoid deterioration of characteristics of a plurality of capacitor elements. However, improvement in airtightness of structures of solid electrolytic capacitors has not conventionally been sufficiently studied. In such a circumstance, the present disclosure provides a solid electrolytic capacitor having high airtightness. Hereinafter, an exemplary embodiment of a solid electrolytic capacitor according to the present disclosure will be described by way of examples. The present disclosure is not limited to the examples described below. In the following description, specific numerical values and materials may be exemplified, but other numerical values and materials may be applied as long as the effects of the present disclosure can be obtained. (Solid Electrolytic Capacitor) A solid electrolytic capacitor according to the present disclosure includes an element stack, an anode terminal, a cathode terminal, and an exterior member. These will be described below. (Element Stack) The element stack includes a plurality of capacitor elements stacked on each other and a conductive material. The plurality of capacitor elements each includes an anode part and a cathode part. The anode parts of the plurality of capacitor elements are overlapped and electrically connected to each other. The plurality of anode parts may be joined to each other by welding, for example. The conductive material is disposed between the cathode parts of two adjacent capacitor elements in the plurality of capacitor elements. The conductive material may electrically connect and integrate the cathode parts of the plurality of overlapped capacitor elements with each other. The conductive material may be, for example, a paste containing metal or a film containing metal. (Anode Terminal) The anode terminal is connected to the anode parts of the capacitor elements. The anode terminal may be made of, for example, copper or copper alloy. The anode terminal is formed by, for example, punching a metal foil to form a metal frame having a