Photosensitive Resin Composition for Touch Panel Migration Resistance
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Solution Overview
Problem
Capacitive touch panels face challenges in achieving high sensitivity, thinness, and high definition due to poor moisture and heat resistance, particularly in terms of migration resistance under high temperature and high humidity conditions, with existing inorganic and transparent photosensitive materials failing to provide reliable performance.
Innovation Solution
A photosensitive resin composition combining an acrylic polymer with a polymerizable group and a cardo based resin having both polymerizable and alkali-soluble groups, applied at specific weight ratios, which forms a cured film suitable as an interlayer insulating film for metal wires, enhancing migration resistance and substrate adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic materials such as SiO2 and SiNx are used for protective films and insulating films, then moisture and heat resistance is improved, but the number of manufacturing processes increases and manufacturing cost rises due to requirements for high-temperature film formation and photolithography patterning
Solution Approach 1:
The patent combines multiple functions into a single transparent photosensitive resin composition that can simultaneously serve as protective film, insulating film, and interlayer insulating film. This eliminates the need for separate inorganic material deposition processes while maintaining adequate moisture and heat resistance through the organic resin formulation containing polymerizable monomers and photopolymerization initiators.
Solution Approach 2:
The transparent photosensitive resin composition is designed to perform multiple functions: it acts as a protective film for metal wires, an insulating film, and an interlayer insulating film simultaneously. This multi-functional material reduces the overall number of manufacturing steps while providing comprehensive protection and insulation in the touch panel structure.
2Ease of manufacture
If transparent photosensitive materials are used for insulating films to reduce manufacturing cost, then the number of processes decreases, but outgassing occurs in later steps and wire resistance increases
Solution Approach 1:
The patent modifies the chemical composition parameters of the transparent photosensitive resin by incorporating specific polymerizable monomers (acrylate, vinyl ether, vinyl ester groups) and controlling the molecular weight and functional group content. These parameter changes enhance the material's thermal stability and reduce outgassing while maintaining low wire resistance through optimized dielectric properties.
Solution Approach 2:
The transparent photosensitive resin composition functions as a composite material system containing multiple components: polymerizable monomers, photopolymerization initiators, and functional additives. This composite structure provides both the cost advantages of photosensitive materials and the performance reliability needed to prevent outgassing and maintain stable wire resistance.
3Ease of manufacture
If conventional transparent photosensitive materials are used as insulating films for metal wires, then manufacturing cost is reduced, but migration resistance under high temperature and high humidity conditions is poor
Solution Approach 1:
The patent applies local quality enhancement by incorporating specific functional groups (carboxyl groups with pKa 4.0 or less) at controlled concentrations (0.1-10 mmol/g) within the transparent photosensitive resin. This localized functional group distribution provides enhanced migration resistance and adhesion to metal wires specifically where needed, while maintaining the overall cost-effectiveness of the photosensitive material system.
Solution Approach 2:
The carboxyl groups in the transparent photosensitive resin act as intermediary functional groups that enhance adhesion between the insulating film and metal wires, particularly under high temperature and humidity conditions. These functional groups serve as chemical mediators that prevent metal ion migration by creating a stable interface between the organic resin and metallic conductors.
4Reliability
If the touch panel is increased in size to improve sensitivity, then sensitivity increases, but the requirements for moisture and heat resistance become more critical due to increased susceptibility to short circuit from metal ion migration
Solution Approach 1:
The transparent photosensitive resin composition incorporates preventive measures against metal ion migration by including carboxyl groups and other functional groups that create a protective chemical environment. This preliminary anti-action prevents migration before it can occur, addressing the heightened susceptibility of larger touch panels to short circuits under high temperature and humidity conditions.
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 provides a cured film with improved photosensitivity, migration resistance, and substrate adhesiveness under high temperature and high humidity conditions, suitable for use in capacitive touch panels, addressing the limitations of existing materials.
Implementation Method 1
a photopolymerization initiator (B)
Data Source
AI summary
An object of the present invention is to provide a transparent photosensitive material that is usable as an interlayer insulating film for metal wires, is excellent in migration resistance and substrate adhesiveness under high temperature and high humidity conditions, and is satisfactory in patternability. The photosensitive resin composition of the present invention contains an acrylic polymer (A1) having, in a side chain thereof, a polymerizable group, a cardo based resin (A2) having a polymerizable group and an alkali-soluble group, and a photopolymerization initiator (B), and contents of the acrylic polymer (A1) and the cardo based resin (A2) satisfy a weight ratio of 1:10 to 10:1.