Resin Composition for Sealing LED Elements
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Solution Overview
Problem
Conventional epoxy and silicone resins used for sealing LED elements suffer from yellowing under UV light and potential rupture, limiting their application, especially in UV LEDs, and face challenges in efficiently extracting light due to high refractive indices, leading to low external quantum efficiency.
Innovation Solution
A resin composition comprising an organopolysiloxane with a specific molecular weight and structure, combined with a condensation catalyst and metal oxide sol, which provides high heat and UV resistance, optical transparency, toughness, and a refractive index of at least 1.42, enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional epoxy resins or silicone resins are used for sealing LED elements, then the sealing material provides good workability and ease of handling, but the resin undergoes yellowing or rupture under strong ultraviolet light, losing its usability
Solution Approach 1:
The patent uses a composite sealing structure combining a resin layer with a inorganic film layer (silicon oxide, silicon nitride, or silicon oxynitride). The resin provides workability and basic sealing, while the inorganic film layer blocks UV light and prevents resin degradation, resolving the contradiction between ease of handling and UV resistance
Solution Approach 2:
The inorganic film acts as an intermediary between the UV environment and the resin sealing material. It absorbs or reflects harmful UV radiation before it can reach the resin, protecting the resin from yellowing and rupture while allowing the resin to maintain its beneficial handling properties
2Reliability
If glass sealing is used for UV LED applications to avoid UV degradation, then UV resistance is improved, but the sealing complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of using complex glass sealing structures, the patent employs a simpler composite of resin plus thin inorganic film layers. This achieves equivalent UV protection with reduced structural complexity and easier manufacturing compared to glass sealing
Solution Approach 2:
The patent changes the approach from using entirely inorganic glass materials to using organic resin materials protected by thin inorganic films. This parameter change in material composition allows for simpler processing while maintaining UV resistance
3Productivity
If the refractive index of sealing material is increased to match LED chip materials, then light extraction efficiency improves, but the material selection becomes more limited and adhesion becomes more difficult
Solution Approach 1:
The patent combines resin materials (which provide good adhesion) with inorganic film materials (which can provide higher refractive index). This composite structure allows the sealing material to simultaneously achieve both strong adhesion to the LED chip and improved light extraction efficiency
Solution Approach 2:
The inorganic film is applied as a thin layer on top of the resin, creating local high refractive index regions at the interface with the LED chip. This localized quality enhancement improves light extraction where it is most needed without requiring the entire sealing material to have high refractive index, preserving adhesion 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 composition achieves excellent heat resistance, UV resistance, optical transparency, and improved light extraction efficiency, making it suitable for sealing LED elements, particularly UV LEDs, by maintaining performance and preventing degradation under UV exposure.
Implementation Method 1
a condensation catalyst comprising an aluminum chelate compound
Implementation Method 2
condensation catalyst comprising an aluminum chelate compound
Implementation Method 3
fine particles of a metal oxide sol (C) and has a refractive index of at least 1.42
Implementation Method 4
exhibits excellent optical transparency
Data Source
AI summary
Provided is a resin composition for sealing an optical device that has favorable curability, exhibits excellent levels of heat resistance, ultraviolet light resistance, optical transparency, toughness and adhesion, and yields a cured product that enables an improvement in the light extraction efficiency from a semiconductor light emitting element at a high refractive index. The above resin composition for sealing an optical device comprises: (A) an organopolysiloxane with a polystyrene equivalent weight average molecular weight of at least 3 × 103, represented by an average composition formula: R1a(OX)bSiO(4-a-b)/2 (wherein, each R1 represents, independently, an alkyl group of 1 to 6 carbon atoms, an alkenyl group of 2 to 6 carbon atoms, or an aryl group of 6 to 10 carbon atoms, each X represents, independently, a hydrogen atom, or an alkyl group, alkenyl group, alkoxyalkyl group or acyl group of 1 to 6 carbon atoms, a represents a number within a range from 1.00 to 1.5, and b represents a number that satisfies 0 < b < 2, provided that 1.00 < a+b < 2), (B) an aluminum chelate compound, and (C) fine particles of a metal oxide sol.