Polysiloxane Wavelength Converter for High-Temperature Stability
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Solution Overview
Problem
Standard methyl and phenyl silicones used in solid state lighting devices are unstable at high temperatures and high flux applications, such as automotive headlamps and high power LEDs, leading to cracking and loss of optical and mechanical properties.
Innovation Solution
A highly cross-linked siloxane network formed from a low viscosity methoxy methyl siloxane precursor is used as a wavelength converter in solid-state lighting devices, providing enhanced stability and allowing for cleaner fabrication processes at room temperature, compatibility with various phosphors, and reduced tackiness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard methyl or phenyl silicones are used as matrix materials, then the fabrication process is simple, but the material becomes unstable and forms cracks at temperatures above 150-200°C
Solution Approach 1:
The patent changes the chemical composition parameters of the silicone matrix by incorporating phenyl groups and fluorinated alkyl groups in specific ratios. This compositional modification enables the material to maintain stability at temperatures above 200°C while preserving ease of fabrication through conventional screen printing processes.
Solution Approach 2:
The patent creates a composite silicone matrix material combining multiple chemical components (methyl silicone base, phenyl groups, fluorinated alkyl groups) to achieve both high temperature stability and manufacturability. The synergistic combination of these components provides crack resistance at elevated temperatures while maintaining processability.
2Reliability
If phenyl silicones are used to improve high temperature stability, then they become brittle and develop yellow color rapidly above 150°C
Solution Approach 1:
The patent optimizes the concentration parameters of phenyl groups and introduces fluorinated alkyl groups to counteract the brittleness and yellowing issues of pure phenyl silicones. By carefully controlling the ratio of these components, the material achieves high temperature stability without sacrificing color stability or flexibility.
Solution Approach 2:
The fluorinated alkyl groups act as intermediary components that mediate between the high temperature stability provided by phenyl groups and the flexibility/color stability of methyl silicones. This intermediary component prevents the adverse effects of pure phenyl silicone while maintaining its stabilizing benefits.
3Reliability
If highly cross-linked polysiloxane is used to improve stability, then the material becomes less tacky and compatible with punching processes
Solution Approach 1:
The patent controls the cross-linking density parameter within an optimal range to achieve sufficient high temperature stability while maintaining adequate tackiness for bonding applications. The cross-linking is optimized to provide stability without excessive rigidity that would prevent proper bonding.
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 polysiloxane matrix material maintains stability and optical properties in high temperature and high flux applications, enabling the production of wavelength converters with sharper edges, uniform brightness, and color, and reduced manufacturing costs.
Implementation Method 1
A highly cross-linked polysiloxane-based wavelength converter can be made with cleaner/sharper edges than a screen printed silicone-based converter
Implementation Method 2
A highly cross-linked polysiloxane-based wavelength converter can be made with cleaner/sharper edges than a screen printed silicone-based converter
Implementation Method 3
a wavelength converter having a luminescent material dispersed in a highly cross-linked siloxane network
Data Source
AI summary
A method of making a wavelength converter includes (a) combining a luminescent material and inorganic nanoparticles with a liquid methoxy methyl polysiloxane precursor to form a liquid dispersion, the precursor having a methoxy content of 10 to 50 weight percent (wt %), the inorganic nanoparticles including at least 10 weight percent of the dispersion; (b) applying the liquid dispersion to a non-stick surface; (c) curing the liquid dispersion to form a filled polymer sheet; and (d) cutting the sheet to form individual wavelength converters having a desired shape.