Solid Electrolytic Capacitor Through-Electrode ESR Reduction

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Solution Overview

Problem

Existing solid electrolytic capacitors face challenges in designing thin devices with low equivalent series resistance (ESR) and equivalent series inductance (ESL) due to long distances between capacitance generation portions and outer electrodes, and the interposition of substrates in mounting configurations, which hinder the increase of capacitance generation volume ratio.

Innovation Solution

A solid electrolytic capacitor design featuring a valve action metal base with a porous portion, a dielectric layer, a solid electrolyte layer, and a conductor layer, where a sealing layer and cathode outer electrodes are strategically positioned to minimize non-capacitance generation volume, using metal foil for the conductor layer and through-electrodes to reduce ESR and ESL, and an insulating layer to enhance airtightness and separate materials for improved design reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a terminal extends from the capacitor element to an outer electrode in a plane direction, then electrical connection is achieved, but the distance to the outer electrode becomes long, increasing ESR and ESL

Engineering Contradiction:

Improveelectrical connectionVSAvoiddistance to outer electrode

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The patent transitions from planar terminal extension to three-dimensional vertical integration by forming through-electrodes that extend perpendicular to the capacitor element surface. The outer electrodes are positioned adjacent to the capacitance generation portion, creating a short current path that reduces ESR and ESL while maintaining reliable electrical connection.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The through-electrodes are embedded within the sealing layer, with the sealing layer enclosing the capacitor element and conductive paths. This nested structure integrates multiple functions (electrical connection, sealing, and mechanical support) into a compact configuration that minimizes distance without compromising connection reliability.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Quantity of substance

If the volume of the capacitance generation portion is increased, then electrostatic capacity is improved, but the volume of the entire capacitor increases, making it difficult to design thin capacitors

Engineering Contradiction:

Improvecapacitance generation volumeVSAvoidtotal capacitor volume

Core Design Contradiction:

Quantity of substanceVSVolume of moving object

Solution Approach 1:

The patent employs a thin sealing layer that encloses the capacitor element while maintaining structural integrity. The outer electrodes are positioned immediately adjacent to the capacitance generation portion, eliminating the need for thick terminal extensions. This allows maximum capacitance generation volume within a minimal overall thickness, achieving high volumetric efficiency.

Inventive Principle:

Principle #30Flexible shells and thin films

3Reliability

If high-conductivity fillers like silver are used in the conductor layer, then ESR is reduced, but manufacturing costs increase

Engineering Contradiction:

Improveelectrical conductivityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive silver filler with cost-effective conductive materials such as carbon black or metal powder in the conductive polymer composition. The conductor layer achieves sufficient conductivity for practical applications without requiring premium materials, significantly reducing manufacturing costs while maintaining acceptable ESR levels.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Volume of moving object

If the sealing layer is made thin to reduce capacitor thickness, then airtightness may be compromised, but making it thick increases overall capacitor thickness

Engineering Contradiction:

Improvecapacitor thicknessVSAvoidairtightness

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The sealing layer is formulated as a composite material incorporating filler particles (such as metal powder or ceramic particles) within a polymer matrix. This composite structure provides enhanced barrier properties and mechanical strength, enabling the sealing layer to maintain excellent airtightness at reduced thickness, thus achieving both thin profile and high reliability.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS11282653B2Solid electrolytic capacitor and method for manufacturing the same

Publication Date: 2022.03.22 MURATA MFG CO LTD

AI summary

A solid electrolytic capacitor is provided that includes a capacitor element having a valve action metal base with a porous portion on a first main surface of a core portion, a dielectric layer disposed on a surface of the porous portion, a solid electrolyte layer disposed on the dielectric layer, and a conductor layer disposed on the solid electrolyte layer. Moreover, the capacitor includes a sealing layer that seals a first main surface of the capacitor element, a cathode outer electrode electrically connected to the conductor layer, and an anode outer electrode electrically connected to the valve action metal base. The sealing layer and the cathode outer electrode are disposed on the conductor layer and a cathode through-electrode extends through the sealing layer on the conductor layer. The conductor layer and the cathode outer electrode are connected to each other with the cathode through-electrode interposed therebetween.