Photosensitive Epoxy Resin Composition for Optical Waveguide Core Layers
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Solution Overview
Problem
Conventional photosensitive resin compositions for optical waveguide core layers in hybrid flexible printed wiring boards face challenges with R-to-R process adaptability due to surface tackiness and trade-offs between flexibility and patterning resolution, requiring a material with higher transparency, reflow resistance, and improved patternability.
Innovation Solution
A photosensitive epoxy resin composition is developed, comprising a cresol novolak polyfunctional epoxy resin and a liquid epoxy resin with a fluorene skeleton, blended in a specific weight ratio, along with a photoacid generator, to enhance transparency, reflow resistance, and patternability while maintaining R-to-R adaptability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a liquid photosensitive resin composition is used to achieve high photo-curing sensitivity, then patterning resolution is improved, but the coating film becomes liable to break due to surface tackiness in R-to-R process
Solution Approach 1:
The invention changes the physical state parameter of the photosensitive resin from liquid to solid at ordinary temperature. This parameter change eliminates surface tackiness while maintaining photo-curing sensitivity, allowing the film to withstand R-to-R processing without breaking
Solution Approach 2:
The invention uses a composite material system combining a solid photosensitive resin with specific molecular weight characteristics. This composite approach achieves both high patterning resolution and film integrity by balancing molecular weight parameters
2Ease of operation
If the molecular weight of the polymer material is increased to improve flexibility of the uncured film, then adaptability to R-to-R process is improved, but patterning resolution is reduced
Solution Approach 1:
The invention optimizes the molecular weight parameter within a specific range (10,000-100,000) to achieve the optimal balance between flexibility and patterning resolution. This precise parameter control allows the uncured film to be flexible enough for R-to-R processing while maintaining high curing sensitivity
3Manufacturing precision
If the molecular weight of the polymer material is reduced to improve patterning resolution, then manufacturing precision is improved, but flexibility of the uncured film is reduced
Solution Approach 1:
The invention sets the molecular weight within the optimal range of 10,000-100,000, avoiding both excessively high and low values. This parameter optimization ensures sufficient flexibility for handling while maintaining high patterning resolution capability
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 higher transparency, improved reflow resistance, and enhanced patternability without compromising R-to-R adaptability, resulting in a core layer with excellent performance in optical waveguides for hybrid flexible printed wiring boards.
Implementation Method 1
the core layer is irradiated with ultraviolet (UV) radiation via a photo mask to be thereby formed into a desired core pattern
Data Source
AI summary
The present invention provides a photosensitive epoxy resin composition which contains: (A) a cresol novolak polyfunctional epoxy resin; (B) a liquid epoxy resin having a fluorene skeleton in its main chain; and (C) a photoacid generator; wherein the components (A) and (B) are present in a mixing weight ratio of (A)/(B)=40/60 to 60/40. Where the inventive photosensitive epoxy resin composition is used as an optical waveguide forming material, particularly as an optical waveguide core layer forming material for formation of a core layer, the optical waveguide core layer can be formed as having excellent reflow resistance and a lower loss through a coating process and a roll-to-roll process without altering the conventional production process.