Negative Photosensitive Resin for Organic EL Displays
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Solution Overview
Problem
Conventional photosensitive resin compositions for organic electroluminescence (EL) display devices face challenges in achieving high sensitivity, light-shielding capability, and forming small-tapered patterns without excessive crosslinking or reflow issues, leading to inconsistencies in pixel design and reduced yield in panel production.
Innovation Solution
A negative type photosensitive resin composition comprising an alkali-soluble resin, a radical polymerizable compound, a photo initiator, and a black colorant, specifically using polyimide, polybenzoxazole, or polysiloxane as the alkali-soluble resin and fluorene or indane backbone-containing compounds for improved heat resistance and pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a coloring agent such as pigment is added to a photosensitive resin composition to enhance light-shielding capability, then light-shielding capability is improved, but sensitivity during light exposure decreases
Solution Approach 1:
The patent uses a specific black colorant (Da) with defined properties (absorption coefficient, particle size distribution) to optimize both light-shielding capability and sensitivity. The colorant has a specific absorption coefficient at 365nm and controlled particle size (D50: 0.5-2.0μm, D90: 3.0-5.0μm) to balance light blocking with UV penetration for exposure
Solution Approach 2:
The patent creates a composite photosensitive resin composition combining alkali-soluble resin (A), radical polymerizable compound (B), photoinitiator (C1), and black colorant (Da). This composite formulation achieves synergistic effects where each component contributes to both light-shielding and sensitivity requirements
2Manufacturing precision
If exposure energy is increased to accelerate UV curing and allow deep film curing, then sensitivity is improved, but excessive crosslinking occurs leading to reflow property deterioration
Solution Approach 1:
The patent optimizes the molecular weight and structure of the radical polymerizable compound (B) to control crosslinking density. The compound has specific molecular weight (1,000-10,000) and functional group content to enable sufficient curing at moderate exposure energies while maintaining reflow properties
Solution Approach 2:
The patent creates different crosslinking densities at different film depths by using the specific radical polymerizable compound structure. The compound allows adequate curing at the deep parts of the film without causing excessive crosslinking at the surface, maintaining local reflow properties where needed
3Reliability
If a small-tapered pattern shape is formed in the pixel dividing layer, then electrode disconnection is prevented, but pattern formation becomes more difficult
Solution Approach 1:
The patent adjusts the viscosity and molecular weight of the photosensitive resin composition to enable small-tapered pattern formation. The specific molecular weight range of the radical polymerizable compound (1,000-10,000) provides optimal flow characteristics for forming narrow tapered patterns while maintaining structural integrity
Solution Approach 2:
The patent uses the alkali-soluble resin (A) as a mediator that facilitates pattern formation. The resin provides a matrix that allows controlled flow and taper formation during processing while maintaining the structural definition needed for small-tapered patterns
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 composition provides a high-sensitivity, light-shielding cured film that maintains small-tapered patterns after development and heat curing, reducing differences in patterned opening widths and enhancing the production yield of organic EL display devices.
Implementation Method 1
a photo initiator (C1)
Implementation Method 2
a black colorant (Da)
Data Source
AI summary
The invention aims to provide a cured film that is high in sensitivity, able to form a pattern having a small-tapered shape after a development step and after a heat curing step, helpful to depress the difference in the width of patterned openings between before and after the heat curing step, and high in light-shielding capability and also aims to provide a negative type photosensitive resin composition that serves for the production thereof. The negative type photosensitive resin composition includes an alkali-soluble resin (A), a radical polymerizable compound (B), a photo initiator (C1), and a black colorant (Da); the alkali-soluble resin (A) including a first resin (A1) containing one or more selected from the group consisting of polyimide (A1-1), polyimide precursor (A1-2), polybenzoxazole (A1-3), polybenzoxazole precursor (A1-4), and polysiloxane (A1-5); and the radical polymerizable compound (B) including one or more selected from the group consisting of a fluorene backbone-containing radical polymerizable compound (B1) and an indane backbone-containing radical polymerizable compound (B2).