Tack-Free Silicone Rubber for LED Embedding
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Solution Overview
Problem
Silicone rubber compositions used in electronic parts face issues with surface tack leading to dust deposition and poor crack resistance, while traditional light-emitting semiconductor devices suffer from moisture durability, light transmittance, and refractive index-related efficiency problems.
Innovation Solution
A silicone rubber composition combining an organopolysiloxane with SiO2 units, aliphatic unsaturated bonds, and a platinum group metal catalyst, which cures to a tack-free, adhesive, and transparent material with improved hardness and crack resistance, suitable for light-emitting semiconductor devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If silicone rubber composition is used for coating electronic parts, then rubbery properties and weathering resistance are improved, but surface tack causes dust deposition
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating specific resinous organopolysiloxane components (Formula 1 and Formula 2) with controlled ratios and molecular structures. This modifies the surface properties of the cured silicone rubber to eliminate tackiness while preserving bulk rubbery properties through parameter optimization rather than fundamental material change.
Solution Approach 2:
The invention creates a composite silicone rubber system by combining multiple organopolysiloxane components (Formula 1, Formula 2, and Formula 3) with specific functional groups. The composite structure integrates the rubbery properties from Formula 3 with the surface properties from Formulas 1 and 2, achieving both dust resistance and elastic characteristics in a single material system.
2Strength
If resinous organopolysiloxane is compounded to improve strength, then strength is enhanced, but surface tack remains causing dust deposition
Solution Approach 1:
The patent applies local quality by differentiating between bulk properties and surface properties. Formula 3 provides bulk strength and rubbery characteristics, while Formulas 1 and 2 specifically address surface tackiness. This localized functional distribution allows the material to exhibit different properties at different levels (bulk vs. surface).
Solution Approach 2:
The invention optimizes the molecular weight, functional group composition, and ratio parameters of the organopolysiloxane components to achieve the desired balance between strength and surface properties, demonstrating parameter change as a key solution mechanism.
3Object-affected harmful factors
If high-hardness silicone resin is used to eliminate surface tack, then dust deposition is reduced, but adhesion to housing decreases
Solution Approach 1:
The patent optimizes the hardness parameter by controlling the molecular structure and crosslinking density of the organopolysiloxane components. The specific formulas and their ratios enable tuning of the material to achieve moderate hardness that provides dust resistance while maintaining adequate adhesion to ceramic and plastic housings.
4Illumination intensity
If traditional epoxy resin is used for embedding, then transparency is achieved, but moisture durability and light transmittance deteriorate
Solution Approach 1:
The invention creates a composite silicone-based embedding material that combines the transparency needed for optical applications with the moisture and thermal stability of silicone chemistry. The multi-component organopolysiloxane system provides both optical clarity and enhanced environmental durability compared to traditional epoxy systems.
Solution Approach 2:
The patent replaces traditional epoxy resins with a silicone-based system that offers superior long-term durability in moisture and thermal environments, effectively substituting a material with shorter service life under harsh conditions (epoxy) with one designed for extended reliability (silicone).
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 effectively eliminates surface tack, enhances adhesion and light transmittance, and improves thermal shock resistance, maintaining high emission efficiency and preventing dust deposition, thus addressing the limitations of existing silicone rubber and resin compositions.
Implementation Method 1
a platinum group metal catalyst
Implementation Method 2
silicone rubber composition of the addition cure type
Data Source
AI summary
A silicone rubber composition comprising (A) an organopolysiloxane containing at least two aliphatic unsaturated bonds, (B) an organopolysiloxane of resin structure comprising SiO2 units, R3nR4pSiO0.5 units and R3qR4rSiO0.5 units wherein R3 is vinyl or allyl, R4 is a monovalent hydrocarbon group free of aliphatic unsaturation, n is 2 or 3, p is 0 or 1, n+p=3, q is 0 or 1, r is 2 or 3, q+r=3, (C) an organohydrogenpolysiloxane having at least two SiH groups, and (D) a platinum catalyst cures into a silicone rubber having excellent rubbery and strength properties and little surface tack.