Water-Soluble Polymer Conductive Patterns for Touch Screens

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Solution Overview

Problem

Current methods for forming conductive patterns in display devices, such as touch screens, are costly and inefficient due to the use of expensive materials like indium tin oxide (ITO) and require complex vacuum deposition processes, while existing water-insoluble polymers used in electroless plating are not environmentally friendly and require toxic organic solvents.

Innovation Solution

A method using a water-soluble, crosslinkable reactive polymer with pendant photosensitive non-aromatic unsaturated carbocyclic groups that can be patterned with UV radiation and processed in aqueous solutions, allowing for the formation of fine conductive metal lines through electroless plating without the need for expensive equipment or toxic solvents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ITO coatings are used to create capacitive patterns, then transparency and conductivity are achieved, but the cost increases due to expensive rare earth metal and vacuum deposition equipment

Engineering Contradiction:

Improvetransparency and conductivityVSAvoidcost and equipment complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the material parameters from expensive ITO ceramic coatings to affordable water-soluble polymer compositions containing silver particles. This substitution maintains the required transparency and conductivity while eliminating the need for expensive vacuum deposition equipment, using instead simple aqueous coating processes

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs disposable water-soluble polymer-based conductive compositions that can be applied via simple aqueous coatings. These compositions replace the expensive, equipment-intensive ITO vacuum deposition process with a low-cost, environmentally friendly alternative using water as the sole solvent

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Ease of manufacture

If water-insoluble polymers are used in electroless plating, then conductive patterns can be formed, but toxic organic solvents are required which are not environmentally friendly

Engineering Contradiction:

Improveconductive pattern formationVSAvoidtoxicity and environmental impact

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent fundamentally changes the solvent parameter from toxic organic solvents to water as the sole medium. The conductive polymer composition is formulated to be water-soluble, enabling electroless plating processes to occur in environmentally benign aqueous solutions while maintaining effective pattern formation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the typically harmful combination of polymer-based plating and organic solvents into a beneficial process by using water-soluble polymers. This eliminates toxic emissions and waste while maintaining the effectiveness of electroless plating for creating conductive patterns

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If fine metal lines are produced to achieve high conductivity, then line width must be reduced to 5-6 μm, but manufacturing precision requirements increase

Engineering Contradiction:

ImproveconductivityVSAvoidline width control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent employs self-aligned electroless plating processes where the polymer composition itself guides the metal deposition. The water-soluble polymer matrix automatically directs silver particle distribution and electroless plating growth, achieving consistent 5-6 μm line widths without requiring ultra-precise external alignment equipment

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS9069248B1Forming conductive metal patterns using water-soluble copolymers

Publication Date: 2015.06.30 EASTMAN KODAK CO

AI summary

A conductive pattern can be formed using a polymeric layer that contains a reactive composition that comprises a reactive polymer that is metal ion-complexing, water-soluble, and crosslinkable. This reactive polymer comprises photosensitive non-aromatic unsaturated carbocyclic groups as well as metal ion-complexing and water solubilizing groups. The reactive composition can be patternwise exposed to suitable radiation to induce crosslinking within the reactive polymer. The reactive composition and reactive polymer in the non-exposed regions can be removed due to their aqueous solubility, but the exposed regions of the polymeric layer are contacted with electroless seed metal ions, which are then reduced. The resulting electroless seed metal nuclei are electrolessly plated with a suitable metal to form the desired conductive pattern. Various articles can be prepared during this process, and the product article can be incorporated into various electronic devices.