Modified Polyhedral Polysiloxane for Optical Semiconductor Encapsulation
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Solution Overview
Problem
Polysiloxane compositions used as encapsulants for optical semiconductor devices face challenges with low heat resistance, light resistance, thermal shock resistance, and gas-barrier properties, which affect their performance, especially in applications requiring high reliability like white LEDs, and they also suffer from handleability issues due to low viscosity and phosphor settling during handling.
Innovation Solution
A modified polyhedral polysiloxane composition is developed through hydrosilylation of an alkenyl group-containing polyhedral polysiloxane compound with a hydrosilyl group-containing compound, resulting in a material with improved heat resistance, light resistance, thermal shock resistance, and gas-barrier properties, and suitable viscosity for handling, achieved by incorporating specific siloxane units and catalysts to enhance cross-linking and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polysiloxane compositions are used as encapsulants for optical semiconductor devices, then heat resistance, cold resistance, weather resistance, light resistance, chemical stability, electrical characteristics, flame retardancy, water resistance, transparency, and colorability are improved, but gas-barrier properties deteriorate
Solution Approach 1:
The patent uses a composite encapsulant system comprising a polysiloxane resin (providing heat resistance, light resistance, and optical properties) combined with an inorganic barrier layer (providing gas-barrier properties). This composite structure allows each material to contribute its strengths, resolving the contradiction between optical/thermal performance and gas barrier properties.
Solution Approach 2:
The encapsulant is divided into multiple functional layers: an inner polysiloxane resin layer for optical and thermal protection, and an outer inorganic barrier layer for gas prevention. This segmentation allows each layer to specialize in specific functions, with the polysiloxane handling optical/thermal requirements and the inorganic layer handling gas barrier requirements.
2Illumination intensity
If encapsulants containing phosphors are used for blue light emitting devices, then white light production and color rendition are improved, but viscosity decreases causing phosphor settling and color variation
Solution Approach 1:
The patent modifies the polysiloxane resin parameters by incorporating specific functional groups (oxetanyl, epoxy, or carboxyl groups) and controlling molecular weight and crosslinking density to optimize viscosity. This ensures the encapsulant remains sufficiently viscous to prevent phosphor settling while maintaining adequate flowability for application and device performance.
3Illumination intensity
If oxetanyl and epoxy groups are used in polysiloxane compositions, then light extraction efficiency and refractive index are improved, but heat resistance and light resistance deteriorate
Solution Approach 1:
The patent applies different functional groups to different regions or aspects of the material structure: oxetanyl groups are used specifically for enhancing light extraction efficiency and refractive index in the bulk resin, while epoxy or carboxyl groups are incorporated at lower concentrations or in specific molecular configurations to provide crosslinking and thermal stability without compromising the optical benefits.
4Object-affected harmful factors
If acrylic resin coating is applied to metal members before silicone resin encapsulation, then gas-barrier properties are improved, but productivity deteriorates due to extra encapsulation steps
Solution Approach 1:
The patent merges the gas-barrier function and optical encapsulation function into a single integrated polysiloxane composition with optimized gas barrier properties, eliminating the need for separate acrylic resin coating and separate encapsulation steps. This consolidation maintains gas-barrier performance while significantly improving manufacturing efficiency.
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 modified polyhedral polysiloxane composition demonstrates high heat resistance, light resistance, and thermal shock resistance, along with excellent gas-barrier properties and improved handleability, effectively addressing the limitations of existing polysiloxane compositions for encapsulating optical semiconductor devices.
Implementation Method 1
A modified polyhedral polysiloxane, which is obtained by hydrosilylation of an alkenyl group-containing polyhedral polysiloxane compound (a) and a hydrosilyl group-containing compound (b)
Data Source
AI summary
An object of the present invention is to provide a polyhedral polysiloxane composition that has high heat resistance and high light resistance, is excellent in gas-barrier properties and thermal shock resistance, and exhibits good handleability when used to encapsulate an optical semiconductor device. The polyhedral polysiloxane composition of the present invention is characterized by including a modified polyhedral polysiloxane which is obtained by hydrosilylation of an alkenyl group-containing polyhedral polysiloxane compound (a) and a hydrosilyl group-containing compound (b) and has a structure derived from an organic silicon compound (a') having one alkenyl group per molecule.