Optical Waveguide Epoxy Resin Composition for Flexible PCBs
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Solution Overview
Problem
Optical waveguide cladding materials face challenges in achieving high flexibility, low refractive index, and excellent patternability while maintaining a suitable glass transition temperature, especially in roll-to-roll processes where dry film techniques are used, leading to increased waveguide loss due to core resin infiltration and surface tension issues.
Innovation Solution
A specific optical waveguide forming epoxy resin composition comprising a liquid epoxy resin, a solid resin, and a photoacid generator, where the liquid epoxy resin is represented by a specific formula as the major component, balancing flexibility and refractive index, and preventing core resin infiltration during the drying process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the amount of long-chain bi-functional aliphatic epoxy resin is increased to improve flexibility, then flexibility is improved, but the glass transition temperature Tg decreases
Solution Approach 1:
The patent changes the chemical structure parameters of the epoxy resin by introducing a specific liquid epoxy resin with formula (1) containing ethyleneoxy or propyleneoxy groups, which modifies the molecular chain flexibility and intermolecular forces, thereby achieving both high flexibility and high Tg simultaneously
Solution Approach 2:
The patent creates a composite resin system by blending the specific liquid epoxy resin (formula 1) with solid epoxy resins and other components in defined proportions, where the liquid component provides flexibility while the solid components maintain high Tg, achieving a balance between conflicting properties
2Shape
If a leveling agent is added to improve surface smoothness, then surface smoothness is improved, but surface tension decreases causing repellency in subsequent coating
Solution Approach 1:
The patent removes the leveling agent from the formulation entirely, instead relying on the inherent surface properties of the specific epoxy resin composition to achieve adequate surface smoothness without introducing harmful surface tension effects
Solution Approach 2:
The patent converts the potential harm of poor surface smoothness into a benefit by using the specific liquid epoxy resin's molecular structure to naturally provide both smoothness and appropriate surface tension, eliminating the need for separate leveling agents
3Shape
If a higher boiling point solvent is used to increase surface smoothness, then surface smoothness is improved, but core resin infiltrates into the under-cladding film during drying
Solution Approach 1:
The patent removes the higher boiling point solvent from the formulation, instead achieving surface smoothness through the inherent properties of the specific epoxy resin composition, thereby preventing core resin infiltration during the drying process
Solution Approach 2:
The patent uses the specific liquid epoxy resin (formula 1) as an intermediary substance that provides both surface smoothness and prevents core resin infiltration, acting as a barrier between the core layer and under-cladding film during processing
4Productivity
If dry film technique is used for roll-to-roll process, then productivity is improved, but material design flexibility is reduced due to requirements for lower tackiness and flexibility
Solution Approach 1:
The patent changes the rheological and surface property parameters of the epoxy resin composition to achieve the right balance between tackiness and flexibility, enabling the material to be processed in roll-to-roll format while maintaining design flexibility for various applications
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 achieves a higher glass transition temperature, increased flexibility, and improved patternability, reducing waveguide loss and maintaining low refractive index, making it suitable for both dry and wet processes in optical waveguide production.
Implementation Method 1
a photoacid generator (C)
Data Source
AI summary
An excellent optical waveguide forming epoxy resin composition is provided, comprising:(A) a liquid epoxy resin;(B) a solid resin; and(C) a photoacid generator;wherein the liquid epoxy resin (A) comprises a liquid epoxy resin represented by the following general formula (1) as a major component thereof in a proportion of 50 to 80 wt % based on an overall amount of a resin component of the resin composition:wherein R1 and R2 are each a hydrogen atom or a methyl group; R3 to R6 are each a hydrogen atom, a methyl group, a chlorine atom or a bromine atom; X is a C2 to C15 alkylene group, an ethyleneoxy group, a di(ethyleneoxy) group, a tri(ethyleneoxy) group, a propyleneoxy group, a propyleneoxypropyl group, a di(propyleneoxy) propyl group or a tri(propyleneoxy)propyl group; and n is a natural number and has an average value of 1.2 to 5.