Capacitor Electrode Foil Embossing for Surface Area

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Solution Overview

Problem

Conventional electrochemical etching methods for producing electrode foils for capacitors result in reduced mechanical stability, significant weight loss, and high acidic waste generation, while also being time-consuming and costly due to the need for high-purity metal foils with specific crystalline textures.

Innovation Solution

A method involving reshaping metal foils using embossing to transfer microstructures onto their surface, creating trenches with high aspect ratios, which increases the surface area without substance loss or liquid waste, allowing for more stable and cost-effective production of electrode foils with enhanced capacitance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If electrochemical etching is used to increase surface area, then capacitance increases, but mechanical strength decreases and weight loss occurs

Engineering Contradiction:
Improvesurface areaVSAvoidmechanical strength
Core Design Contradiction:
Area of moving objectVSStrength

Solution Approach 1:

The patent replaces the electrochemical etching process with a mechanical embossing process. A patterned roller mechanically imprints microstructures (grooves, protrusions, pillars) onto the metal foil surface, creating high surface area without chemical material removal. This mechanical approach preserves the foil's bulk integrity and mechanical strength while achieving the desired surface area increase for capacitance enhancement.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Area of moving object

If electrochemical etching is used to increase surface area, then capacitance increases, but acid consumption increases and liquid waste is generated

Engineering Contradiction:
Improvesurface areaVSAvoidacidic waste
Core Design Contradiction:
Area of moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent substitutes the chemical etching process with a mechanical embossing process using a patterned roller. This eliminates the need for acidic etchants entirely, replacing chemical material removal with physical deformation. The result is increased surface area for capacitance without generating acidic liquid waste or consuming hazardous chemicals.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If high-purity metal foils with cubic texture are used for controlled etching, then etching precision improves, but production time increases and cost increases

Engineering Contradiction:
Improveetching controlVSAvoidproduction time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent replaces the multi-step thermal processing required to create cubic texture with a direct mechanical embossing process. The patterned roller imprints microstructures onto standard metal foil without requiring high-purity materials or cubic crystallographic texture. This eliminates time-consuming annealing steps and complex rolling processes while maintaining precise control over microstructure geometry.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the fundamental approach from chemical etching (which requires specific material properties like high purity and cubic texture) to mechanical embossing (which works with standard metal foils). This parameter change in the manufacturing process eliminates the need for specialized material preparation and reduces production complexity and time.

Inventive Principle:
Principle #35Parameter changes

4Manufacturing precision

If complex rolling steps and annealing are used to create cubic texture, then etching uniformity improves, but device complexity increases and cost increases

Engineering Contradiction:
Improveetching uniformityVSAvoidproduction process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex thermal-mechanical processing (multiple rolling steps at different temperatures followed by annealing) with a single mechanical embossing step using a patterned roller. The roller directly imprints the desired microstructure geometry onto the foil surface, achieving uniformity through precise mechanical replication rather than controlled crystallographic texture development.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent performs the microstructure formation action in advance using a pre-patterned roller. The roller itself contains the desired microstructure pattern, which is transferred to the foil in a single pass. This preliminary preparation of the tooling enables consistent, uniform microstructures without requiring complex in-process controls or material preparation steps.

Inventive Principle:
Principle #10Preliminary action

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 method produces electrode foils with a surface area up to 20 times larger than unshaped foils, enabling stable oxide layers for high-voltage applications and reducing production costs by eliminating the need for complex rolling processes and high-purity foils.

Implementation Method 1

the metal foil is plastically deformed into a different shape

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

metal foils, which may be made of a valve metal such as aluminum, are treated using an electrochemical etching process

Methodology Applied
Scientific EffectElectrochemical etching: Electrolysis

Implementation Method 3

a metal oxide layer can be produced on the metal foil as a dielectric. As already described above, this can be achieved by means of electrochemical processes, in particular anodic oxidation

Methodology Applied
Scientific EffectAnodization: Anodising

Data Source

PatentEP3229988B1Process for the manufacture of electrode foils for capacitors, electrode foils and capacitors with the electrode foils
Publication Date: 2019.08.07 TDK ELECTRONICS AG
  • EP3229988B1 patent drawingFigure 1a~1c
  • EP3229988B1 patent drawingFigure 2a~2b
  • EP3229988B1 patent drawingFigure 3

AI summary

The invention relates to a method for producing electrode foils (1) for capacitors (10), said method comprising the steps of: A) providing a metal foil (1); B) transferring microstructures (2) located on a punch to a main surface of the metal foil using a shaping process.