Electrolytic Capacitor Porous Anode Interface for Moisture Sealing

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Solution Overview

Problem

The package body of electrolytic capacitors often fails to come into close contact with the anode leading part, allowing air and moisture to enter, which deteriorates the solid electrolyte layer and increases equivalent series resistance (ESR).

Innovation Solution

The electrolytic capacitor design includes a porous portion on the surface of the second part of the anode foil, with the first part in close contact with the package body and an external electrode, and optionally uses an insulating member and spacers to enhance contact and prevent air ingress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the package body is formed using injection molding, then the manufacturing process is simple and efficient, but the package body fails to come into close contact with the anode leading part, allowing air and moisture to enter

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidsealing performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The anode leading part is formed with a porous portion on its surface before the injection molding process. This preliminary surface treatment creates capillary structures that will later enable the package body to come into close contact with the anode leading part, preventing air and moisture ingress while maintaining manufacturing simplicity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A porous portion is formed on the surface of the anode leading part, creating capillary structures that facilitate close contact with the package body during injection molding. The porous structure allows the resin to penetrate and form strong adhesion, ensuring reliable sealing without complex manufacturing processes

Inventive Principle:

Principle #31Porous materials

2Reliability

If the package body is formed to enclose the capacitor element, then the internal components are protected, but air and moisture can still enter through the boundary interface

Engineering Contradiction:

Improveprotection of internal componentsVSAvoidair and moisture ingress

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The porous portion on the anode leading part creates capillary structures that enable the package body resin to penetrate and form intimate contact. This eliminates gaps and interfaces where air and moisture could ingress, while maintaining the protective enclosure function

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The combination of the porous anode leading part surface and the injection-molded package body resin creates a composite interface structure. The resin penetrates the porous structure, forming a strong bond that eliminates pathways for harmful factors while maintaining component protection

Inventive Principle:

Principle #40Composite materials

3Stability of the object's composition

If air enters inside the electrolytic capacitor, then the solid electrolyte layer deteriorates, but the equivalent series resistance increases

Engineering Contradiction:

Improvesolid electrolyte layer stabilityVSAvoidequivalent series resistance

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The porous portion is formed on the anode leading part before assembly, creating a structure that prevents air and moisture from reaching the solid electrolyte layer. This preliminary protective structure stops the deterioration process before it can increase ESR

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The injection-molded package body resin, combined with the porous interface structure, creates an inert barrier environment that isolates the solid electrolyte layer from oxygen and moisture. This prevents oxidation and deterioration, maintaining low ESR over time

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design improves the reliability and reduces ESR by preventing air and moisture entry, ensuring a stable and low-resistance connection between the anode and external electrode.

Implementation Method 1

at least a surface (specifically, a surface layer) of the second part has a porous portion

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Data Source

PatentUS12476053B2Electrolytic capacitor and manufacturing method thereof

Publication Date: 2025.11.18 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

To provide an electrolytic capacitor with improved reliability. The electrolytic capacitor including: at least one capacitor element including an anode foil having a first part including a first end, and a second part including a second end, a dielectric layer formed on at least a surface of the second part, and a cathode part covering at least part of the dielectric layer, a package body enclosing the capacitor element; and an external electrode. At least a surface of the second part has a porous portion, and at least an end face of the first end is exposed from the package body and is in contact with the external electrode.