Curable Silicone Composition for Optical Semiconductor Sealing
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Solution Overview
Problem
Curable silicone compositions for sealing optical semiconductor elements face challenges in maintaining moldability and preventing surface tack, flashing, and voids during transfer molding or compression molding due to viscosity decline at elevated temperatures, which affects the reliability and quality of the resin-sealed products.
Innovation Solution
A curable silicone composition comprising an organopolysiloxane with silicon-bonded vinyl groups, an organopolysiloxane with a specific average unit formula, and a hydrosilylation reaction catalyst, which provides a viscosity range of 3,000 to 10,000 mPa·s at 25°C and a viscosity ratio that stabilizes at elevated temperatures, ensuring excellent moldability and mechanical strength, and a method of resin-sealing using transfer molding or compression molding with a controlled gel time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a curable silicone composition with high hot strength is used for injection molding, then the molding temperature can be maintained, but the viscosity declines significantly at elevated temperatures causing flashing and voids during transfer molding or compression molding
Solution Approach 1:
The patent modifies the chemical composition parameters of the silicone system by incorporating specific crosslinking agents and adjusting the ratio of base polymer to crosslinker, which changes the viscosity-temperature relationship to maintain stability at elevated temperatures while preserving hot strength
Solution Approach 2:
The patent creates a composite silicone system combining multiple polymer components with different thermal properties, where the synergistic interaction between components maintains both high hot strength and stable viscosity at molding temperatures
2Ease of operation
If the viscosity of the silicone composition is reduced to improve moldability, then the composition becomes easier to mold, but the mechanical strength of the cured product declines
Solution Approach 1:
The patent incorporates preliminary crosslinking structures within the polymer chains before molding, which maintain adequate viscosity for moldability while pre-establishing the framework for high mechanical strength after complete curing
Solution Approach 2:
The patent optimizes the molecular weight distribution and functional group concentration to achieve a viscosity range that ensures good moldability while maintaining sufficient chain entanglement and crosslinking potential for high mechanical strength
3Strength
If the composition is cured to achieve high mechanical strength, then the structural integrity is improved, but surface tack and adhesiveness increase
Solution Approach 1:
The patent creates different physical properties at different locations within the cured product by controlling crosslinking density and surface composition, resulting in high mechanical strength in the bulk while maintaining low surface tack through selective surface chemistry
Solution Approach 2:
The patent adjusts the crosslinking parameters and surface energy characteristics to achieve a state where internal mechanical strength is maximized while surface adhesiveness is minimized through controlled surface composition
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 efficiently performs resin sealing with low surface tack, minimal flashing, and few voids, enhancing the reliability and quality of the resin-sealed optical semiconductor elements by maintaining excellent moldability and mechanical properties.
Implementation Method 1
a curable silicone composition comprising: (A) an organopolysiloxane that has at least two silicon-bonded vinyl groups in one molecule... (C) an organohydrogenpolysiloxane that has at least three silicon-bonded hydrogen atoms in one molecule... and (D) a hydrosilylation reaction catalyst
Data Source
Figure 1
AI summary
A curable silicone composition for sealing an optical semiconductor element, comprising: (A) an organopolysiloxane that has at least two silicon-bonded vinyl groups in one molecule, that has C1-10 alkyl for the other silicon-bonded organic groups therein, and that lacks a siloxane unit represented by the following formula: SiO4/2; (B) an organopolysiloxane represented by an average unit formula; (C) an organopolysiloxane that has at least three silicon-bonded hydrogen atoms in one molecule, that has C1-10 alkyl for the silicon-bonded organic groups therein, and that contains from 0.7 to 1.6 mass% of silicon-bonded hydrogen atoms; and (D) a hydrosilylation reaction catalyst, wherein a viscosity at 25 °C and a viscosity at 100 °C of this composition lacking component (D) reside in a specific relationship, can efficiently perform resin sealing by transfer molding or compression molding while exhibiting an excellent moldability and can provide a cured product that has a low surface tack.