Touch Panel Conductive Film Coating for Flexible Corrosion Resistance
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Solution Overview
Problem
Existing touch panels face issues with lead-out wiring disconnection due to corrosion from sulfur, halogen, and iodine in the environment, particularly in thin and flexible designs, and require a protective layer that maintains flexibility and reduces thickness without increasing the panel's overall thickness.
Innovation Solution
A conductive film with a protective layer formed from a photosensitive resin composition containing (meth)acrylate monomers and clay minerals, with specific particle size and aspect ratios, applied to a transparent flexible substrate to cover the metal wiring, providing corrosion resistance and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the thickness of the protective layer is reduced to achieve thinner touch panels, then the overall panel thickness is reduced, but the corrosion resistance of the lead-out wiring deteriorates
Solution Approach 1:
The patent uses a composite resin composition containing epoxy resin, polyimide resin, and specific inorganic particles (silica, alumina, titania) with controlled sizes and ratios. This composite structure provides both the thin profile (1-5 μm) and enhanced corrosion resistance by creating a multi-phase barrier that prevents sulfur and iodine penetration while maintaining mechanical integrity.
Solution Approach 2:
The patent optimizes multiple parameters simultaneously: resin composition ratios (epoxy to polyimide), inorganic particle size distribution (0.1-2 μm silica, 0.01-0.1 μm alumina), and protective layer thickness (1-5 μm). These parameter changes create a protective layer with tailored properties that achieve both thinness and superior corrosion resistance against sulfur and iodine.
2Area of stationary object
If the line width of lead-out wirings is reduced for frame narrowing, then the screen display area is increased, but the wiring becomes more susceptible to disconnection by environmental corrosion
Solution Approach 1:
The composite resin system with epoxy resin providing adhesion, polyimide resin providing chemical resistance, and multi-size inorganic particles creating a tortuous path for corrosive agents, collectively protects the thinned lead-out wirings from sulfur and iodine corrosion while enabling the reduced line width design for larger display areas.
Solution Approach 2:
The protective layer is applied specifically to the lead-out wiring regions with optimized local composition and thickness (1-5 μm), providing enhanced corrosion resistance exactly where the thinned wirings are most vulnerable to environmental factors, while allowing other areas of the touch panel to be optimized for transparency and touch sensitivity.
3Adaptability or versatility
If the protective layer thickness is reduced to enable flexible bending, then the touch panel flexibility is improved, but the protection against sulfur and halogen corrosion is weakened
Solution Approach 1:
The patent employs a flexible protective layer only 1-5 μm thick made from a composite of epoxy resin, polyimide resin, and fine inorganic particles. This thin film structure provides the necessary flexibility for bending applications while the composite composition maintains effective barrier properties against sulfur and halogen corrosion through its multi-phase structure and optimized material selection.
Solution Approach 2:
The composite material system combines the flexibility of thin polymer resin layers with the chemical stability of inorganic particles. The specific combination of epoxy and polyimide resins with silica, alumina, and titania particles creates a flexible yet corrosion-resistant protective layer that can withstand bending while protecting against environmental degradation.
4Ease of manufacture
If conventional resin compositions are used for the protective layer, then the manufacturing process is simple, but the adhesion to metal wiring and resistance to iodine corrosion are insufficient
Solution Approach 1:
The patent uses a composite resin composition that can be applied using conventional coating and curing processes, maintaining manufacturing simplicity. The composite contains epoxy resin for adhesion, polyimide resin for chemical resistance, and inorganic particles for structural stability and corrosion barrier properties. This composite approach achieves superior adhesion to metal wiring and resistance to iodine corrosion without requiring complex manufacturing steps.
Solution Approach 2:
The patent optimizes the chemical composition parameters of the resin system (epoxy to polyimide ratio, inorganic particle types and sizes) to enhance both adhesion to metal surfaces and resistance to iodine corrosion. These compositional changes are implemented within existing coating and curing process parameters, maintaining ease of manufacture while significantly improving reliability.
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 solution effectively suppresses metal wire disconnection and allows for bending at small curvatures, maintaining the panel's integrity and flexibility while preventing corrosion from environmental factors.
Implementation Method 1
a photopolymerization initiator, wherein a viscosity of the photosensitive resin composition is 5000 mPa·s or higher
Data Source
AI summary
In a conductive film, a cured film formed of a photosensitive resin composition including at least one of monomers represented by Formulae (1) and (2), a clay mineral, and a photopolymerization initiator is provided as a protective layer of a lead-out wiring part of the conductive film that functions as a touch sensor.