Silicone Composition for Optical Devices with Thermo-Optic Stability

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Solution Overview

Problem

Conventional organic lightguides and LED packages suffer from instability when exposed to heat and radiation, leading to loss of transmittance over time, necessitating the development of more stable materials for optical device applications.

Innovation Solution

A silicone composition comprising a combination of high and low viscosity polyorganosiloxanes, a low vinyl content silicone resin, a crosslinker, and a catalyst, with a specific SiH/Vi ratio, is used to create a cured product with improved stability and mechanical properties for optical devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional organic lightguides and LED packages are used, then manufacturing is easier and initial cost is lower, but stability under heat and radiation exposure deteriorates, leading to transmittance loss over time

Engineering Contradiction:

Improvestability under heat and radiationVSAvoidtransmittance retention over time

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical composition parameters by using a specific ratio of polyorganosiloxane viscosities (10:1 to 1:10) and controlling the vinyl content (0.5-5.0 wt%) to achieve both stability and transmittance retention. This parameter optimization allows the material to resist degradation under heat and radiation while maintaining optical properties

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite silicone resin system combining high viscosity polyorganosiloxane (providing stability and mechanical strength) with low viscosity polyorganosiloxane (providing transmittance and flow properties). This composite approach achieves both reliability under environmental stress and long-term optical performance that neither component could achieve alone

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If high brightness LEDs are used to increase lumen output, then illumination performance is improved, but thermal flux and optical flux generation increases, causing greater stability issues with conventional materials

Engineering Contradiction:

Improvelumen outputVSAvoidthermal flux and radiation exposure

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces conventional organic materials with silicone-based materials that have extended service life under high thermal and optical flux conditions. The silicone composition resists degradation from HB LED radiation, effectively creating a long-lasting optical system that can withstand the harsh environment generated by high brightness LEDs

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The invention optimizes the silicone resin parameters including vinyl content (0.5-5.0 wt%) and polyorganosiloxane viscosity ratio to achieve thermal stability and radiation resistance. These parameter changes enable the material to maintain its optical and mechanical properties under the high thermal flux and UV radiation generated by HB LEDs

Inventive Principle:

Principle #35Parameter changes

3Strength

If silicone compositions with high vinyl content are used to improve crosslinking and mechanical strength, then Shore A hardness and tensile strength are improved, but yellowing resistance and optical stability deteriorate

Engineering Contradiction:

Improvetensile strength and hardnessVSAvoidyellowing under radiation

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent precisely controls the vinyl content parameter at 0.5-5.0 wt% to achieve the optimal balance between crosslinking density (for strength) and yellowing resistance. This parameter optimization ensures sufficient mechanical properties while minimizing radiation-induced discoloration

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention creates different local properties within the silicone system by combining low vinyl content resin (for yellowing resistance) with controlled crosslinking (for strength). The crosslinking provides localized mechanical reinforcement without requiring high overall vinyl content, thus maintaining optical stability

Inventive Principle:

Principle #3Local quality

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 cured product exhibits enhanced Shore A hardness, tensile strength, elongation, thermo-optic stability, and resistance to yellowing, significantly improving the longevity and performance of optical devices such as lightguides and LED packages.

Implementation Method 1

a crosslinker, and a catalyst as defined in Claim 1

Methodology Applied

Scientific EffectCrosslinking: Chemical Bonding

Data Source

PatentEP2435516B1Silicone composition for producing transparent silicone materials and optical devices

Publication Date: 2017.03.22 DOW SILICONES CORP

Figure 1a~1c
Figure 2

AI summary

A hydrosilylation curable composition contains a combination of high and low viscosity polyorganosiloxanes, a silicone resin, a crosslinker, and a catalyst. The composition, and the cured product thereof, is useful in optical devices such as charged coupled devices (CCDs), ligh emitting diodes (LEDs), lightguides, optical cameras, photo-couplers, and waveguides. Processes for fabricating the optical devices include various molding techniques, including overmolding.