Optical Stack Structure for Metal Nanowire Adhesive Compatibility

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Solution Overview

Problem

Metal nanowires in touch devices face reliability issues due to incompatibility with optical clear adhesives, leading to electromigration and failure to meet specification requirements for product reliability testing.

Innovation Solution

An optical stack structure comprising a metal nanowire layer and an organic polymer layer with a crosslinking degree of 80-100% and volatile organic compound content ≤1%, ensuring compatibility and preventing corrosion of metal nanowires, along with a passivation layer and a cover plate with controlled elemental content to enhance reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If metal nanowires are used to fabricate touch electrodes or peripheral circuits, then flexibility and transparency are improved, but compatibility with optical clear adhesive deteriorates leading to corrosion and electromigration

Engineering Contradiction:

ImproveflexibilityVSAvoidcompatibility with optical clear adhesive

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces an organic polymer layer as an intermediary between the metal nanowires and the optical clear adhesive. This intermediate layer has specific properties (crosslinking degree 80-100%, volatile organic compound content ≤1%) that prevent it from attacking the metal nanowires, thereby resolving the incompatibility issue while maintaining both flexibility and reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the chemical and physical parameters of the organic polymer layer, specifically controlling the crosslinking degree to be 80-100% and volatile organic compound content to be ≤1%. These parameter changes ensure the polymer layer is chemically stable and non-corrosive to metal nanowires, solving the compatibility problem

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional organic polymer layers are used, then ease of manufacture is improved, but corrosion of metal nanowires occurs due to high volatile organic compound content

Engineering Contradiction:

Improveease of manufactureVSAvoidcorrosion of metal nanowires

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The patent modifies the manufacturing parameters of the organic polymer layer by strictly controlling the volatile organic compound content to be ≤1% and crosslinking degree to be 80-100%. This parameter control eliminates corrosion while maintaining manufacturing simplicity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential harm of organic polymer layers (corrosion due to volatile organic compounds) into a benefit by precisely controlling the volatile organic compound content to ≤1%. This transformation allows the use of organic polymers while eliminating their harmful effects

Inventive Principle:

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

3Strength

If optical clear adhesive with high polymer content is used, then adhesion is improved, but electromigration of metal nanowires increases reducing reliability

Engineering Contradiction:

ImproveadhesionVSAvoidelectromigration resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The organic polymer layer serves as a protective intermediary between the metal nanowires and the optical clear adhesive. It provides the necessary adhesion strength while simultaneously protecting the metal nanowires from electromigration caused by the polymer content in the adhesive

Inventive Principle:

Principle #24Intermediary (Mediator)

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 optical stack structure achieves high touch sensitivity and meets product reliability testing specifications by preventing corrosion and electromigration, ensuring stable performance under high-temperature/high-humidity conditions.

Implementation Method 1

a crosslinking degree of the organic polymer layer is greater than or equal to 80% and less than or equal to 100%

Methodology Applied

Scientific EffectCrosslinking: Chemical Bonding

Implementation Method 2

a content of volatile organic compounds in the organic polymer layer is less than or equal to 1%

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS12032119B2Optical stack structure

Publication Date: 2024.07.09 TPK ADVANCED SOLUTIONS

AI summary

An optical stack structure includes a metal nanowire layer and an organic polymer layer. A crosslinking degree of the organic polymer layer is greater than or equal to 80% and less than or equal to 100%, and a content of volatile organic compounds in the organic polymer layer is less than or equal to 1%. The content of the volatile organic compounds in the organic polymer layer is defined as a difference between a thermal weight loss of the organic polymer layer measured at a measuring temperature and a water content of the organic polymer layer measured at the measuring temperature.