Conductive Pattern Using Ultra-Long Silver Nanowires

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Solution Overview

Problem

Conductive patterns in touch panels face issues with conductivity, manufacturing costs, and electrical disconnection due to cracks, particularly in capacitive touch panels using silver nanowires which have high sheet resistance and are not suitable for flexible displays.

Innovation Solution

A conductive pattern with a high ratio of nanostructures having opposite ends in contact with edges, forming a network that increases conductivity and reduces crack occurrence by intersecting connections, using silver nanofibers with a high aspect ratio and a conductive matrix to prevent oxidation and enhance adhesion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional silver nanowires with small diameter (100 nm) and short length (5-10 µm) are used to achieve high transmissivity, then optical transmissivity is improved, but conductivity is lowered due to many disconnections between nanowires

Engineering Contradiction:

Improveoptical transmissivityVSAvoidconductivity

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The patent changes the key parameters of silver nanowires by using nanowires with larger diameter (1-10 µm) and much longer length (100 µm to several mm), fundamentally altering the aspect ratio from conventional values. This parameter change reduces the number of intersections needed for electrical connection while maintaining optical transmissivity, thereby resolving the contradiction between transmissivity and conductivity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a size dimension transformation by using ultra-long nanowires that span across the electrode pattern in a different spatial scale compared to conventional short nanowires. This dimensional change allows fewer nanowires to achieve the same conductive effect, reducing intersection points and improving both conductivity and transmissivity simultaneously

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of manufacture

If ITO is used as transparent electrode material, then manufacturing process is established, but sheet resistance is high, manufacturing costs are high, and it is not available for flexible display

Engineering Contradiction:

Improvemanufacturing process availabilityVSAvoidsheet resistance and flexibility

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces expensive ITO material with silver nanowire network that can be manufactured at lower cost. The silver nanowire structure provides both flexibility and low sheet resistance, eliminating the need for rigid ITO coatings while reducing material costs and enabling flexible display applications

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent uses composite structure of silver nanowires embedded in transparent polymer matrix, combining the advantages of metal conductivity with polymer flexibility and processability. This composite approach achieves low sheet resistance, flexibility, and ease of manufacture simultaneously

Inventive Principle:

Principle #40Composite materials

3Device complexity

If transparent electrode is formed by patterning transparent conductive sheet with short silver nanowires, then electrode pattern is created, but many disconnections occur between nanowires lowering conductivity

Engineering Contradiction:

Improveelectrode pattern formationVSAvoidconductivity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent segments the electrode pattern into multiple isolated conductive regions, each formed by a small number of ultra-long nanowires. This segmentation reduces the total number of nanowire intersections needed while maintaining overall conductivity, as each segment independently provides conductive pathways

Inventive Principle:

Principle #1Segmentation

4Ease of manufacture

If conventional transparent electrode with short nanowires is used, then manufacturing is simplified, but electrical disconnection occurs due to cracks from external shocks

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidcrack resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent employs ultra-long nanowires that span across potential crack paths before external shocks occur. These nanowires act as pre-positioned conductive bridges that can bridge gaps formed by cracks, providing beforehand cushioning against electrical disconnection from mechanical damage

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS11360612B2Conductive pattern

Publication Date: 2022.06.14 DONGWOO FINE CHEM CO LTD

AI summary

Provided is a conductive pattern having at least one unit conductive pattern forming one touch pixel according to an aspect of the present invention. The at least one unit conductive pattern includes a plurality of nanostructures each having opposite ends. A ratio of nanostructures, both opposite ends of which are in contact with edges of the at least one unit conductive pattern to all nanostructures included in the at least one unit conductive pattern is 70% or more.