Curable Silicone Composition for Optical Semiconductor Sealing
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Solution Overview
Problem
Curable silicone compositions used in optical semiconductor devices develop cracks and yellow discoloration when exposed to high temperatures, leading to diminished adhesion and transparency, and existing heat-resistant additives like cerium-containing organopolysiloxanes cause yellow coloration, compromising transparency.
Innovation Solution
A curable silicone composition comprising a straight-chain organopolysiloxane, an organopolysiloxane with silicon-bonded hydrogen atoms, a cerium-containing organopolysiloxane, and a hydrosilylation catalyst, with specific molecular ratios and additives to prevent cracking and yellow discoloration, while maintaining transparency and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a curable silicone composition is used for sealing in optical semiconductor devices, then it forms a transparent cured product with good rubber-like properties, but it develops cracks and yellow discoloration when used at high temperatures (200°C or higher) for long periods
Solution Approach 1:
The patent changes the chemical composition parameters by introducing a specific organopolysiloxane with controlled vinyl group content (0.01-5 mass%) and using a platinum complex catalyst with specific ligands. This compositional parameter change enables the cured product to maintain transparency and adhesion while achieving heat resistance up to 200°C without cracking or yellow discoloration.
Solution Approach 2:
The patent creates a composite curable silicone composition by combining multiple components: organopolysiloxane (A), straight-chain organopolysiloxane with alkenyl groups (B), crosslinking agent (C), and platinum complex catalyst (D). This composite formulation synergistically achieves both transparency and high-temperature resistance, resolving the contradiction between optical properties and thermal stability.
2Temperature
If cerium-containing organopolysiloxane is added to improve heat resistance, then the curable silicone composition becomes more heat resistant, but it causes yellow coloration that compromises transparency
Solution Approach 1:
The patent extracts and eliminates the cerium-containing organopolysiloxane component that causes yellow discoloration. Instead, it uses a platinum complex catalyst system with specific organopolysiloxane formulations that achieve heat resistance without compromising transparency, thus removing the harmful effect while preserving the beneficial heat resistance property.
Solution Approach 2:
The patent replaces the cerium-containing additive with a platinum complex catalyst system that does not cause yellowing. The new formulation uses disposable organic ligands in the catalyst complex that maintain stability at high temperatures without producing unwanted coloration, effectively substituting a transparent solution for a yellowing one.
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 forms a cured product that is resistant to thermal aging, maintains high optical transmittance, and exhibits improved flame resistance, ensuring the reliability and performance of optical semiconductor devices.
Implementation Method 1
Curable silicone compositions which cure in response to a hydrosilylation reaction
Implementation Method 2
adding a cerium-containing organopolysiloxane is a well-known method of improving the heat resistance of a curable silicone composition
Data Source
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AI summary
This invention relates to a curable silicone composition comprising: (A) a straight-chain organopolysiloxane having at least two alkenyl groups in a molecule; (B) an organopolysiloxane represented by the following average unit formula: (R1SiO3/2)a (R1 2SiO2/2)b (R1 3SiO1/2)c (SiO4/2)d (XO1/2)e wherein, R1 each independently represent an alkyl group having from 1 to 12 carbons, an alkenyl group having from 2 to 12 carbons, an aryl group having from 6 to 20 carbons, an aralkyl group having from 7 to 20 carbons, or a group in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms, with the proviso that at least two R1 in a molecule are the alkenyl groups, X is a hydrogen atom or an alkyl group, a is a number from 0 to 0.3, b is 0 or a positive number, c is a positive number, d is a positive number, e is a number from 0 to 0.4, a + b + c + d = 1, c/d is a number from 0 to 10, and b/d is a number from 0 to 0.5; (C) an organopolysiloxane having at least two silicon-bonded hydrogen atoms in a molecule; (D) a cerium-containing organopolysiloxane; and (E) a hydrosilylation reaction catalyst. The curable silicone composition does not develop cracks due to thermal aging and can form a cured product having little yellow discoloration.