Electrode Foil Crack Layout for High-Capacitance Capacitors

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Solution Overview

Problem

Existing electrode foils for electrolytic capacitors face challenges in achieving high capacitance per unit volume while maintaining mechanical strength, as reducing foil thickness or increasing capacitance per projected area leads to decreased strength and workability, and forming grooves or dividing portions results in reduced maximum tensile load and capacitance.

Innovation Solution

The electrode foil features an enlarged surface portion with cracks formed obliquely to the width direction, allowing for increased capacitance per unit volume without compromising mechanical strength by distributing stress effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the foil thickness is reduced to increase capacitance per unit volume, then capacitance per unit volume increases, but the strength of the electrode foil decreases

Engineering Contradiction:

Improvecapacitance per unit volumeVSAvoidstrength of electrode foil

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The electrode foil is segmented into a core portion and an enlarged surface portion, where the enlarged surface portion contains a spongy structure with numerous fine pits. This segmentation allows the core portion to provide mechanical strength while the enlarged surface portion provides high capacitance, resolving the contradiction between thickness reduction and strength maintenance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the electrode foil are given different properties: the core portion maintains sufficient thickness for strength, while the enlarged surface portion has a roughened structure with fine pits to maximize capacitance per projected area. This local differentiation allows simultaneous optimization of both strength and capacitance density.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If the capacitance per projected area is increased by forming fine pits at high density, then capacitance per projected area increases, but the electrode foil becomes hard and brittle reducing workability

Engineering Contradiction:

Improvecapacitance per projected areaVSAvoidworkability of electrode foil

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The electrode foil is divided into a core portion and an enlarged surface portion, where only the enlarged surface portion contains the fine pits at high density. This segmentation confines the brittleness to the surface layer while the core portion remains ductile and workable, allowing the foil to be processed despite the high-density pit structure.

Inventive Principle:

Principle #1Segmentation

3Strength

If the foil thickness is increased to maintain strength, then strength is maintained, but capacitance per unit volume decreases

Engineering Contradiction:

Improvestrength of electrode foilVSAvoidcapacitance per unit volume

Core Design Contradiction:

StrengthVSQuantity of substance

Solution Approach 1:

The electrode foil employs local quality differentiation where the core portion has sufficient thickness for strength, while the enlarged surface portion has a roughened structure that increases capacitance per projected area. This allows the overall capacitance per unit volume to increase without compromising the strength provided by the core portion.

Inventive Principle:

Principle #3Local quality

4Stability of the object's composition

If dividing portions are formed in the enlarged surface portion to disperse stress, then tensile elongation at break improves, but maximum tensile load decreases

Engineering Contradiction:

Improvetensile elongation at breakVSAvoidmaximum tensile load

Core Design Contradiction:

Stability of the object's compositionVSForce

Solution Approach 1:

The enlarged surface portion is segmented into regions separated by dividing portions, which disperse stress and improve tensile elongation at break. The core portion remains intact and continuous, maintaining the maximum tensile load capacity of the overall electrode foil structure.

Inventive Principle:

Principle #1Segmentation

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

The solution enhances capacitance per unit volume and maintains maximum tensile load, improving workability during winding and reducing capacitor size without significant decreases in strength.

Implementation Method 1

a crack is formed in the enlarged surface portion in an oblique direction with respect to the width direction... distributing stress effectively

Methodology Applied

Scientific EffectStress distribution:

Data Source

PatentUS12381042B2Electrode foil for electrolytic capacitor and electrolytic capacitor

Publication Date: 2025.08.05 JAPAN CAPACITOR IND CO LTD

AI summary

An electrode foil having high capacitance per unit volume is provided. The electrode foil is an electrode foil for an electrolytic capacitor. The electrode foil is an electrode foil extending in a longitudinal direction and having a width direction orthogonal to the longitudinal direction, the electrode foil including an enlarged surface portion on a surface of the electrode foil, wherein a crack is formed in the enlarged surface portion in a direction oblique to the width direction.