Optical Waveguide Resin Composition for Low Warpage
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Solution Overview
Problem
Current resin compositions for optical waveguides face challenges in achieving high transparency and a low linear expansion coefficient, leading to warpage and stress issues due to the difference in thermal expansion coefficients between the resin and substrate, which disrupts electrical conduction and can cause chip fracture.
Innovation Solution
A resin composition comprising a solid epoxy resin with one or less hydroxyl group, a liquid epoxy resin with one or less hydroxyl group, a cationic curing agent, and nanosize silica sol with an average particle size of 5 nm to 20 nm, and a pH of 4.7 to 8.5, which eliminates compounds with multiple hydroxyl groups to prevent cohesion and turbidity, allowing for a dry film with improved transparency and reduced linear expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a resin material with high transparency is used for the optical waveguide, then no filler can be compounded therewith, but the linear expansion coefficient becomes high causing warpage
Solution Approach 1:
The patent applies composite materials by combining transparent resin with nanosize particles (5-20 nm) that have low linear expansion coefficients. The nanosize particles are dispersed in the resin matrix to create a composite material that maintains transparency while reducing the overall linear expansion coefficient to match the substrate, preventing warpage.
Solution Approach 2:
The patent changes the particle size parameter to nanoscale (5-20 nm) to achieve transparency while modifying the linear expansion coefficient. By controlling the particle size within this specific range and optimizing the concentration (1-10 parts by mass per 100 parts of resin), the material achieves both transparency and low linear expansion.
2Stability of the object's composition
If nanosize particles are compounded with liquid material to reduce linear expansion coefficient, then transparency is improved, but hydroxyl groups cause cohesion and white turbidity
Solution Approach 1:
The patent uses a silane coupling agent as an intermediary substance between the nanosize particles and the resin matrix. This coupling agent modifies the particle surface to reduce hydroxyl group interactions that cause cohesion and white turbidity, while maintaining the dispersibility and adhesion of particles in the resin, thus preserving transparency.
Solution Approach 2:
The patent optimizes the concentration of nanosize particles (1-10 parts by mass per 100 parts of resin) and controls the particle size (5-20 nm) to prevent excessive interaction between hydroxyl groups. By maintaining particles within the nanoscale range and limiting their concentration, the material remains transparent while achieving low linear expansion.
3Productivity
If dry film material is used instead of liquid material for forming optical waveguide, then productivity is improved, but transparency and handling are compromised
Solution Approach 1:
The patent transforms the material from liquid to dry film form by controlling the moisture content and physical state parameters. The dry film is prepared with specific thickness and density characteristics that enable it to be handled as a solid material while maintaining the optical properties of the cured resin. This phase change allows vacuum laminator processing while preserving transparency.
Solution Approach 2:
The patent prepares the resin composition in advance as a dry film that can be stored and handled before use. The dry film is pre-formed with the nanosize particle reinforcement already incorporated, allowing it to be directly applied using vacuum lamination without requiring on-site mixing or curing of liquid materials, thus improving productivity while maintaining optical properties.
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 resin composition that forms a transparent, flexible dry film with a low linear expansion coefficient, reducing warpage and stress, enabling reliable optical waveguide formation and photoelectric composite wiring boards with minimal light loss and enhanced handleability.
Implementation Method 1
a resin composition for an optical waveguide, including: (A) an epoxy resin constituted by a solid epoxy resin with one or less hydroxyl group in a molecule, and a liquid epoxy resin with one or less hydroxyl group in a molecule; (B) a curing agent with one or less hydroxyl group in a molecule; and (C) a nanosize silica sol
Implementation Method 2
Where two or more hydroxyl groups are present in one compound from among the resin composition, curing agent, and other additives constituting the dry film, those hydroxyl groups act together with the hydroxyl groups on the surface of nanosize particles, causing cohesion which results in white turbidity
Implementation Method 3
a resin composition for an optical waveguide, including: (A) an epoxy resin constituted by a solid epoxy resin with one or less hydroxyl group in a molecule, and a liquid epoxy resin with one or less hydroxyl group in a molecule; (B) a curing agent with one or less hydroxyl group in a molecule
Data Source
AI summary
Provided are a resin composition which offers both high transparency and a low linear expansion coefficient and can be used as a material for a dry film, and also a dry film obtained from this composition, an optical waveguide, and a photoelectric composite wiring board. The resin composition for an optical waveguide includes: (A) an epoxy resin constituted by a solid epoxy resin with one or less hydroxyl group in a molecule, and a liquid epoxy resin with one or less hydroxyl group in a molecule; (B) a curing agent with one or less hydroxyl group in a molecule; and (C) a nanosize silica sol, and contains no compound including two or more hydroxyl groups in a molecule as a resin component.