Siloxane Curable Composition for LED Encapsulation
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Solution Overview
Problem
Current encapsulation materials for LEDs, such as epoxy resin and silicone resin, face issues with low light transmittance, poor light resistance, and inadequate heat resistance, while silicone resin also exhibits a sticky surface and low heat resistance, necessitating a material with high refractive index, crack resistance, surface hardness, adhesive strength, and thermal shock resistance.
Innovation Solution
A curable composition comprising a mixture of a siloxane oligomeric compound and a linear polysiloxane with an alkenyl group bound to a silicon atom, cured via a hydrosilylation reaction, which maintains high refractive index, viscosity, and hardness, and includes a silicon compound with hydrogen atoms for cross-linking, ensuring excellent crack resistance and thermal shock resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy resin is used as LED encapsulation material, then adhesive property and dynamic durability are improved, but light transmittance in blue to UV wavelength ranges deteriorates
Solution Approach 1:
The invention uses a composite material system comprising a siloxane oligomeric compound (with specific siloxane units M, D, T, Q) as the base resin and a polyhydric alcohol compound as the crosslinking agent. This composite formulation achieves both high light transmittance in the blue-UV range and excellent adhesive properties, resolving the contradiction between transparency and adhesion that plagues pure epoxy resin systems.
2Strength
If epoxy resin is used as LED encapsulation material, then adhesive property is improved, but light resistance deteriorates
Solution Approach 1:
The siloxane-based composite material system provides inherent resistance to UV degradation and yellowing while maintaining strong adhesive bonding. The specific combination of siloxane oligomers with units M, D, T, and Q, crosslinked with polyhydric alcohol compounds, creates a network structure that resists photodegradation, thereby achieving both adhesion and light resistance simultaneously.
3Reliability
If silicone resin is used as encapsulation material, then light resistance is improved, but heat resistance deteriorates
Solution Approach 1:
The invention modifies the silicone resin system by carefully controlling the molecular weight, functional group content, and crosslinking density of the siloxane oligomeric compound. By adjusting these parameters—specifically the ratios of units M, D, T, Q and the crosslinking agent content—the material achieves both excellent light resistance and improved heat resistance, overcoming the thermal limitations of conventional silicone resins.
4Reliability
If silicone resin is used as encapsulation material, then light resistance is improved, but surface stickiness after curing deteriorates
Solution Approach 1:
The invention controls the crosslinking reaction parameters by selecting appropriate polyhydric alcohol compounds and optimizing their content relative to the siloxane oligomeric compound. This parameter optimization ensures complete crosslinking that eliminates surface stickiness while preserving the light resistance benefits of the silicone-based system. The specific stoichiometric balance between alkenyl groups and hydrogen atoms in the crosslinking reaction is critical.
5Illumination intensity
If high refractive index is achieved in encapsulation material, then light extraction efficiency is improved, but manufacturing complexity deteriorates
Solution Approach 1:
The invention achieves high refractive index (1.40 or more) by incorporating specific high-refractive-index siloxane units (particularly units D and T with aromatic substituents) into the oligomeric compound structure. This is accomplished through straightforward selection of monomers during synthesis rather than complex multi-step manufacturing processes, thereby achieving high light extraction efficiency without significantly increasing manufacturing complexity.
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 curable composition demonstrates excellent processability, high refractive index, low moisture permeability, and enhanced thermal and mechanical properties, preventing surface stickiness and color change under high-temperature or high-humidity conditions, making it suitable for LED encapsulation.
Implementation Method 1
the curable composition may be a composition that is cured by a hydrosilylation reaction
Data Source
AI summary
A curable composition and use thereof are provided. The exemplary curable composition can show excellent processability and workability. Also, the curable composition can have a high refractive index before or after curing. The composition has low moisture permeability before or after curing and shows excellent crack resistance, thermal shock resistance, adhesive property and hardness. In addition, the composition does not cause color change such as whitening, under a high-temperature or high-humidity condition, and does not exhibit stickiness on a surface thereof. The curable composition may be used as an adhesive material or as an encapsulation material for semiconductor devices such as an LED, a CCD, a photo coupler, or a photovoltaic cell.