LED Device Dual Encapsulant Hardness and Light Transmissivity
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Solution Overview
Problem
Conventional LED devices using epoxy encapsulants suffer from thermal and photo degradation, especially under ultraviolet light, leading to reduced light transmissivity and output, while silicone encapsulants offer low hardness and rigidity, causing mechanical issues during assembly and handling.
Innovation Solution
A light-emitting diode (LED) device with an elastomeric encapsulant in a receptacle, surrounded by a second rigid encapsulant, providing high hardness and thermal conductivity, and using a receptacle material with a higher refractive index to minimize light loss, combined with a manufacturing process that includes injection molding or transfer molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy encapsulant is used, then hardness and rigidity are improved, but thermal and photo degradation occur leading to reduced light transmissivity
Solution Approach 1:
The patent uses a composite encapsulation system combining silicone elastomer (providing flexibility and thermal stability) with rigid support structures (mold cup, flange, rim) to achieve both mechanical strength and optical clarity. This composite approach allows the encapsulant to protect against degradation while maintaining light transmissivity, resolving the contradiction between hardness and reliability.
2Reliability
If silicone encapsulant is used, then thermal stability and light transmissivity are improved, but hardness and rigidity are reduced causing mechanical issues
Solution Approach 1:
The patent applies local quality by providing rigid support only where mechanically necessary (mold cup, flange, and rim structures) while allowing the silicone encapsulant to remain soft where it contacts the LED chip and bond wires. This localized rigidity provides mechanical support during assembly and handling, while the soft encapsulant maintains its excellent optical and thermal properties throughout the device.
3Reliability
If elastomeric encapsulant is used, then mechanical stress and degradation are reduced, but structural support and rigidity are insufficient
Solution Approach 1:
The patent segments the encapsulation function into multiple components: the elastomeric silicone encapsulant provides durability and stress relief, while separate rigid structures (mold cup, flange, rim) provide structural support. This segmentation allows each component to optimize its specific function without compromise, resolving the contradiction between durability and rigidity.
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 enhances the durability and light transmissivity of LED devices, reducing mechanical stress and degradation, while maintaining high thermal stability and ease of assembly, thus improving the reliability and efficiency of LED devices.
Implementation Method 1
using a receptacle material with a higher refractive index to minimize light loss
Implementation Method 2
surrounded by a second rigid encapsulant, providing high hardness and thermal conductivity
Data Source
AI summary
A light-emitting diode (“LED”) device has an LED chip attached to a substrate. The terminals of the LED chip are electrically coupled to leads of the LED device. Elastomeric encapsulant within a receptacle of the LED device surrounds the LED chip. A second encapsulant is disposed within an aperture of the receptacle on the elastomeric encapsulant.