Conductive Foil Release Coating for Ultra-Thin Scratch-Free Films

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Solution Overview

Problem

Existing methods for producing electrically conductive films face limitations in achieving thicknesses less than 6 µm, often result in surface scratches, require additional cleaning steps due to residue adhesion, and involve complex vacuum processes that introduce contaminants or require non-vacuum steps.

Innovation Solution

A method involving ion etching of the flexible substrate to adjust adhesive forces, followed by vacuum deposition of a single or multiple layers of conductive material, which are then mechanically peeled off, ensuring a homogeneous film of a single material with thicknesses down to 1 µm.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a polyacrylic acid component and a polyol component are mixed and then a crosslinking catalyst is added, then crosslinking reaction occurs to form gel structure, but the mixing process becomes complex and requires precise timing and temperature control

Engineering Contradiction:
Improvecrosslinking reaction controlVSAvoidmixing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the polyacrylic acid component and polyol component into a single pre-mixed adhesive composition before applying to the substrate. This eliminates the need for separate mixing steps and catalyst addition during application, simplifying the overall process while maintaining reliable crosslinking reaction through the pre-formulated composition.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The adhesive composition is prepared in advance with all necessary components (polyacrylic acid, polyol, and crosslinking catalyst) already combined and distributed uniformly. This preliminary preparation eliminates the need for precise timing and temperature control during the application process, as the crosslinking reaction conditions are already optimized in the pre-mixed formulation.

Inventive Principle:
Principle #10Preliminary action

2Strength

If conventional adhesives are used without gel structure, then application is simple, but peeling strength and bonding durability are insufficient for rigid substrates

Engineering Contradiction:
Improvepeeling strengthVSAvoidadhesive formulation complexity
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent creates a composite adhesive system combining polyacrylic acid and polyol components that form a gel structure through crosslinking. This gel-based composite provides enhanced peeling strength and bonding durability for rigid substrates while maintaining relatively simple application procedures through pre-mixed formulations.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the adhesive formulation by incorporating specific ratios of polyacrylic acid and polyol components with controlled molecular weights and functional groups. These parameter changes enable the formation of a gel structure that significantly improves bonding performance without requiring complex application procedures.

Inventive Principle:
Principle #35Parameter changes

3Duration of action of stationary object

If gel structure is formed through crosslinking reaction, then bonding durability is improved, but the adhesive composition becomes sensitive to moisture and requires controlled storage conditions

Engineering Contradiction:
Improvebonding durabilityVSAvoidadhesive composition stability
Core Design Contradiction:
Duration of action of stationary objectVSStability of the object's composition

Solution Approach 1:

The adhesive composition is pre-formulated with all components including the crosslinking catalyst, but the actual crosslinking reaction is delayed until application. This allows the adhesive to be stored in a stable, ready-to-use state without premature gel formation, while ensuring bonding durability is achieved through controlled crosslinking after application.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The adhesive system transitions from a stable, non-crosslinked state during storage and application to a crosslinked gel structure during curing. This dynamic transformation allows the adhesive to maintain composition stability during storage while achieving enhanced bonding durability when needed, responding to environmental conditions like moisture and temperature.

Inventive Principle:
Principle #15Dynamics

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

Enables production of thin, scratch-free, and residue-free electrically conductive films with consistent material properties, overcoming the limitations of previous methods by achieving uniform thickness and simplifying the production process.

Implementation Method 1

it has gradually come to light by experimentation that high-peel-strength bonding can be exhibited by a composition comprising a polyacrylic acid component having a specific structure and a polyol component, and that surprising bonding durability can be achieved by allowing these components to undergo crosslinking reaction

Methodology Applied
Scientific EffectCrosslinking reaction:

Implementation Method 2

When a crosslinking catalyst and crosslinking conditions (e.g., heating) are used, a gel structure having a three-dimensional network is formed

Methodology Applied
Scientific EffectThermal heating: Heating

Data Source

PatentEP3673094B1Method for producing an electrically conductive foil
Publication Date: 2026.05.20 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3673094B1 patent drawingFigure 1
  • EP3673094B1 patent drawingFigure 2

AI summary

The invention relates to a method for producing a foil made of an electrically conductive material. The foil consists of the same electrically conductive material along the extension of the foil thickness. A flexible substrate is first introduced into a working chamber; a layer made of the electrically conductive material is deposited on at least one surface region of the flexible substrate using a vacuum coating process; and the first layer is then removed from the flexible substrate. Either an ion-etching process is carried out at least on the surface region of the flexible substrate prior to depositing the layer made of the electrically conductive material and/or the layer made of the electrically conductive material is heated during and/or after the layer is deposited.