LED Encapsulant Index-Matched Thixotropic Agent
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Solution Overview
Problem
Conventional LED packages using thixotropic agents suffer from light scattering due to refractive index differences between the agent and the encapsulant, leading to reduced emission efficiency and a cloudy appearance.
Innovation Solution
Incorporating a thixotropic agent with a refractive index matching or closely matching that of the encapsulant, allowing for reduced or eliminated scattering and enhanced mechanical and thermal properties without impacting optical clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a thixotropic agent with different refractive index is used to maintain encapsulant shape, then the encapsulant maintains desired shape, but light scattering occurs and emission efficiency decreases
Solution Approach 1:
The patent changes the refractive index parameter of the thixotropic agent to match the encapsulant material, eliminating light scattering while maintaining shape-maintaining properties. This parameter adjustment resolves the contradiction between shape maintenance and emission efficiency.
Solution Approach 2:
The patent creates optical homogeneity by matching the refractive index of the thixotropic agent with the encapsulant material, making the composite material optically uniform and eliminating scattering interfaces that would reduce emission efficiency.
2Stability of the object's composition
If thixotropic agent is added to maintain shape, then shape stability is improved, but optical clarity deteriorates due to scattering
Solution Approach 1:
The refractive index parameter of the thixotropic agent is specifically adjusted to match the encapsulant, allowing the agent to be present in sufficient quantities for shape stability without creating optical inhomogeneity that would reduce clarity.
Solution Approach 2:
The thixotropic agent is selected or modified to have the same optical properties (refractive index) as the encapsulant material, making it optically indistinguishable and thus maintaining clarity while providing shape stability.
3Strength
If higher percentage of thixotropic agent is used to enhance mechanical properties, then mechanical strength is improved, but optical properties are compromised due to scattering
Solution Approach 1:
By changing the refractive index parameter of the thixotropic agent to match the encapsulant, the patent enables use of higher percentages of the agent for enhanced mechanical strength without the usual penalty of increased light scattering.
Solution Approach 2:
The patent creates an optically homogeneous composite material where the thixotropic agent and encapsulant form a unified optical medium, allowing the composite to benefit from the mechanical enhancement of the agent without optical degradation.
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 solution results in increased LED package emission efficiency and reduced clouding, enabling higher percentages of thixotropic agents to be used for enhanced mechanical and thermal properties without compromising optical properties.
Implementation Method 1
A thixotropic agent with index matched to the encapsulant is disclosed. The thixotropic agent can have a refractive index that is within plus or minus n=0.05 of the refractive index of the encapsulant.
Implementation Method 2
Many thixotropic agents can have an index of refraction that is different from the LED package encapsulant. This difference in index of refraction between the thixotropic agent and the encapsulant can result in the encapsulant exhibiting scattering characteristics for the light passing through the encapsulant from the LED.
Implementation Method 3
Many encapsulants used in conventional LED packages utilize a thixotropic or thickening agent/material that can help the encapsulant maintain the desired shape. The thixotropic agent helps the encapsulant maintain a hemispheric shape particularly in the time between when the encapsulant is dispensed or molded, and when it is cured.
Data Source
AI summary
Emitter packages are disclosed having a thixotropic agent or material, with the encapsulant exhibiting significant reduction of thixotropic agent scattering. The packages exhibit a corresponding reduction or elimination of encapsulant clouding and increased package emission efficiency. This allows for the thixotropic agents to be included in the encapsulant to alter certain properties (e.g. mechanical or thermal) while not significantly altering the optical properties of the encapsulant. One embodiment of a light emitting diode (LED) package according to the present invention comprises an LED chip with an encapsulant over the LED chip. The encapsulant has an encapsulant refractive index and also has a thixotropic material with a refractive index that is substantially the same as the encapsulant refractive index.