Flowable Adhesive Bonding Optical Components
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Solution Overview
Problem
Commercially available adhesives for optical applications face challenges with high thermal expansion, leading to reduced transmission efficiency, and those with low thermal expansion often incorporate fillers that increase haze and decrease transparency, making them unsuitable for many optical applications.
Innovation Solution
A method for bonding optical components using a flowable adhesive composition containing surface-modified silica nanoparticles dispersed in an epoxy resin, cured with actinic radiation, which provides a low coefficient of thermal expansion and maintains optical clarity by preventing nanoparticle aggregation and using a specific surface modification process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional fillers are added to reduce thermal expansion, then the coefficient of thermal expansion decreases, but haze increases and transparency decreases
Solution Approach 1:
The patent changes the particle size parameter of the filler material, using nanoparticles (1-100 nm) instead of conventional larger fillers. This parameter change allows the material to reduce thermal expansion while remaining below the wavelength of visible light, preventing light scattering and maintaining optical clarity.
Solution Approach 2:
The patent creates a composite adhesive material combining epoxy resin with surface-modified silica nanoparticles. This composite structure provides both the low thermal expansion properties of the inorganic nanoparticles and the adhesive properties of the organic resin, while the surface modification ensures compatibility and prevents aggregation.
2Stability of the object's composition
If silica nanoparticles are used to reduce thermal expansion, then thermal stability improves, but nanoparticle aggregation occurs causing haze
Solution Approach 1:
The patent uses surface-modifying agents as intermediaries between the silica nanoparticles and the epoxy resin matrix. These modifiers create a compatible interface that prevents nanoparticle aggregation while maintaining the low thermal expansion benefits, ensuring the particles remain dispersed and do not scatter light.
Solution Approach 2:
The patent controls the surface chemistry parameters of the nanoparticles through modification, changing their surface energy and compatibility characteristics. This prevents aggregation by ensuring the nanoparticles are well-dispersed in the epoxy matrix, maintaining optical clarity while achieving thermal stability.
3Object-affected harmful factors
If optically clear adhesives are used for bonding, then transmission efficiency is maintained, but thermal expansion causes fiber movement and transmission loss
Solution Approach 1:
The patent develops a composite adhesive that combines the optical clarity of organic adhesives with the low thermal expansion of inorganic fillers. The epoxy resin matrix provides transparency and adhesion, while the embedded silica nanoparticles provide thermal stability, preventing fiber movement during temperature variations.
Solution Approach 2:
The patent changes the thermal expansion parameter of the adhesive by incorporating nanoparticles, reducing it from typical adhesive levels to match that of the optical fibers. This parameter change eliminates the differential thermal expansion that causes fiber movement, while the small particle size ensures optical transmission is not compromised.
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 method achieves a thermally stable, optically clear bond with low thermal expansion, suitable for optical communication wavelengths, and prevents light scattering, ensuring high transmission efficiency and compatibility with optical components.
Implementation Method 1
treated with a cation exchange resin to lower the pH between 2 and 3
Implementation Method 2
treated with ammonium hydroxide to increase the pH to 9 and 9.5
Implementation Method 3
a silane surface modifying agent having hydrolysable groups
Implementation Method 4
surface-modifier covalently attached to the silica nanoparticles
Implementation Method 5
heating the surface modification mixture to at least 50 °C to form non-aggregated, surface-modified silica nanoparticles
Implementation Method 6
curing the adhesive composition in the presence of actinic radiation to bond the first article to the second article
Implementation Method 7
allows transmission at wavelengths typically used for communication applications (e.g., 800 to 1650 nanometers)
Data Source
AI summary
A method of bonding a first article to a second article is provided. The method involves the use of a flowable, adhesive composition that contains non-aggregated, surface-modified silica nanoparticles dispersed in an epoxy resin.