Transparent Conductive Film Surface Shape for Low Visibility
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Solution Overview
Problem
Conventional transparent conductive films using thin metal wires face challenges in achieving both low visibility and low electrical resistance due to inherent reflection issues, with existing solutions either increasing resistance or visibility, making them unsuitable for touch panels and display devices.
Innovation Solution
A transparent conductive film with a specific surface shape characterized by Ra2/Sm > 0.01 μm and a metal volume content of 35% or more, where Ra is the arithmetic average roughness and Sm is the average distance between convex portions, reduces specular reflectance and enhances visibility while maintaining low resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If thin metal wire is used to reduce visibility, then the conductive pattern becomes less visible, but electrical resistance increases
Solution Approach 1:
The patent applies local quality by creating a surface shape that is specific to the conductive pattern areas. The surface shape treatment (Ra2/Sm > 0.01 μm) is applied locally to the metal wiring portion to reduce specular reflectance, while the bulk metal volume content is maintained at 35% or more to ensure low electrical resistance. This localized surface modification allows different regions to have different optical properties without affecting the overall electrical conductivity.
Solution Approach 2:
The patent changes the surface shape parameters (Ra and Sm) of the metal wiring portion to control optical reflection. By controlling the surface roughness (Ra) and the average distance between convex portions (Sm) such that Ra2/Sm > 0.01 μm, the specular reflectance is reduced. This parameter change affects only the optical properties while maintaining the electrical properties through sufficient metal volume content (≥35%).
2Reliability
If calender treatment is applied to reduce electrical resistance, then metal volume content increases, but light reflection increases making the pattern more visible
Solution Approach 1:
The patent applies local quality by creating a surface shape that is specific to the conductive pattern areas. The surface shape treatment (Ra2/Sm > 0.01 μm) is applied locally to the metal wiring portion to reduce specular reflectance, while the bulk metal volume content is maintained at 35% or more to ensure low electrical resistance. This localized surface modification allows different regions to have different optical properties without affecting the overall electrical conductivity.
Solution Approach 2:
The patent changes the surface shape parameters (Ra and Sm) of the metal wiring portion to control optical reflection. By controlling the surface roughness (Ra) and the average distance between convex portions (Sm) such that Ra2/Sm > 0.01 μm, the specular reflectance is reduced. This parameter change affects only the optical properties while maintaining the electrical properties through sufficient metal volume content (≥35%).
3Object-affected harmful factors
If blackening layer is stacked to reduce visibility, then conductive pattern becomes less visible, but conductivity is reduced
Solution Approach 1:
The patent applies local quality by creating a surface shape that is specific to the conductive pattern areas. The surface shape treatment (Ra2/Sm > 0.01 μm) is applied locally to the metal wiring portion to reduce specular reflectance, while the bulk metal volume content is maintained at 35% or more to ensure low electrical resistance. This localized surface modification allows different regions to have different optical properties without affecting the overall electrical conductivity.
Solution Approach 2:
The patent changes the surface shape parameters (Ra and Sm) of the metal wiring portion to control optical reflection. By controlling the surface roughness (Ra) and the average distance between convex portions (Sm) such that Ra2/Sm > 0.01 μm, the specular reflectance is reduced. This parameter change affects only the optical properties while maintaining the electrical properties through sufficient metal volume content (≥35%).
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 film achieves both reduced visibility and low electrical resistance, making it suitable for applications in touch panels and display devices with improved reliability.
Implementation Method 1
at least a part of the metal wiring portion has a surface shape satisfying the condition of Ra2/Sm>0.01 μm... reduces specular reflectance
Data Source
AI summary
A transparent conductive film comprises a transparent substrate and a metal wiring portion formed thereon. A thin metal wire contained in an electrode portion in the metal wiring portion has a surface shape satisfying the condition of Ra2/Sm>0.01 μm and has a metal volume content of 35% or more. Ra represents an arithmetic average roughness in micrometers and is equal to or smaller than the thickness of a metal wiring located in a position where the surface roughness is measured. Sm represents an average distance between convex portions and is 0.01 μm or more.