Opaque Wiring Electrode Masking via Photolithography
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Solution Overview
Problem
Touch panel sensors with opaque wiring electrodes face issues of reduced conductivity due to metal oxidation and visibility problems caused by positional deviations between metal wiring and low reflective layers, especially when using existing darkening treatments or inkjet-based methods.
Innovation Solution
A method involving the formation of an opaque wiring electrode on a transparent substrate, followed by applying a positive photosensitive composition and exposing it to create a functional layer that masks the wiring electrode, ensuring high conductivity and reduced visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an opaque wiring electrode containing metal material is used, then sensitivity and screen size are improved, but the wiring electrode becomes visually recognizable due to metallic gloss
Solution Approach 1:
A light shielding layer is introduced as an intermediary substance between the transparent substrate and the opaque wiring electrode. This layer shields the metallic gloss of the wiring electrode from view, making it hardly visible, while not interfering with its electrical function. The light shielding layer acts as a mediator that blocks optical information without affecting electrical conductivity.
Solution Approach 2:
The light shielding layer is designed with specific optical properties (black or dark color) to absorb or block light, thereby changing the visual appearance of the underlying metallic wiring electrode. By applying this colored/shielding layer, the reflective metallic surface is converted into a non-reflective, hidden surface that is hardly visible to the human eye.
2Object-affected harmful factors
If metal darkening treatment is applied to suppress reflection, then visibility is reduced, but conductivity is reduced due to oxidation of metal
Solution Approach 1:
Instead of directly treating the metal surface (which causes oxidation and conductivity loss), a separate light shielding layer is applied as an intermediary. This layer provides the necessary optical shielding function without chemically interacting with or oxidizing the metal, thereby preserving the metal's original high conductivity while achieving the desired visibility reduction.
Solution Approach 2:
The functions of electrical conduction and optical shielding are segmented into separate components: the opaque wiring electrode handles electrical conduction, while the separate light shielding layer handles optical shielding. This segmentation allows each component to optimize its specific function without compromising the other, avoiding the conductivity loss that occurs when attempting to combine both functions in a single treatment.
3Object-affected harmful factors
If a low reflective layer is formed by inkjet method, then visibility is reduced, but fine processing is difficult and positional deviation occurs
Solution Approach 1:
The light shielding layer is formed by transferring the pattern from a photomask through photolithography, creating a precise copy of the desired pattern. This copying process ensures high positional accuracy and fine processing that cannot be achieved with inkjet methods, as the photomask defines the exact pattern geometry and position, which is then replicated in the light shielding layer.
Solution Approach 2:
The inkjet deposition method is replaced with a photolithography process that uses optical fields and chemical reactions instead of mechanical droplet placement. This substitution enables much higher precision in pattern formation, as photolithography can achieve sub-micrometer accuracy compared to the limitations of inkjet printing, thereby eliminating positional deviation issues.
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 method results in a substrate with a fine patterned wiring electrode that is both conductive and minimally visible, addressing the conductivity and visibility issues of previous technologies.
Implementation Method 1
exposing and developing the positive photosensitive composition using the opaque wiring electrode as a mask to form a functional layer at a portion corresponding to the opaque wiring electrode
Data Source
AI summary
The present invention provides a method for manufacturing a substrate equipped with a wiring electrode which has a fine pattern and is excellent in conductivity and in which an opaque wiring electrode is hardly visible. Disclosed is a method for manufacturing a substrate equipped with a wiring electrode including the steps of forming an opaque wiring electrode on at least one side of a transparent substrate, applying a positive photosensitive composition on one side of the transparent substrate, and exposing and developing the positive photosensitive composition using the opaque wiring electrode as a mask to form a functional layer at a portion corresponding to the opaque wiring electrode.