UV LED Encapsulation Structure for Higher Light Extraction
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Solution Overview
Problem
Semiconductor light emitting devices face challenges in achieving high light extraction efficiency, particularly for ultraviolet light, due to limitations in reflective materials and encapsulating member designs that lead to significant light loss within the encapsulating member.
Innovation Solution
A semiconductor light emitting device design featuring a flip chip with a light-transmitting thermoplastic resin encapsulating member that has at least 90% transmissivity for UV light, combined with a conductive layer and barrier structure that minimizes internal reflection, and a conductive layer with reduced reflectivity for UV light, allowing for efficient light distribution and extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional encapsulating member design is used, then structural integrity is maintained, but light extraction efficiency deteriorates due to significant internal reflection and light loss
Solution Approach 1:
The patent changes the material parameters of the encapsulating member by using a light-transmitting thermoplastic resin with specific optical properties (high UV transmissivity of at least 90%, controlled refractive index) instead of conventional encapsulating materials. This parameter change reduces internal reflection and improves light extraction efficiency while maintaining structural integrity through the material's inherent properties.
Solution Approach 2:
The patent employs a composite structure combining the light-transmitting thermoplastic resin encapsulating member with a flip chip design and conductive layers. This composite approach integrates multiple functional elements (optical transmission, structural support, electrical connection) to simultaneously achieve high light extraction efficiency and maintain structural reliability.
2Loss of energy
If reflective materials are used to manage light, then light distribution may improve, but UV light reflectivity limitations cause significant light loss
Solution Approach 1:
The patent extracts the light management function from conventional reflective materials and transfers it to the encapsulating member itself. By designing the encapsulating member with high UV transmissivity and appropriate refractive index, the system eliminates the need for separate reflective materials that have poor UV reflectivity, thereby reducing light loss without compromising manufacturability.
Solution Approach 2:
The light-transmitting thermoplastic resin acts as an intermediary between the light source and the external environment, performing both structural and optical functions. This intermediary material with tailored optical properties (high transmissivity, controlled refraction) replaces the need for specialized reflective materials, solving both the light loss problem and the material availability constraint.
3Illumination intensity
If the encapsulating member transmissivity for UV light is increased, then light extraction efficiency improves, but internal reflection increases leading to light loss
Solution Approach 1:
The patent optimizes multiple parameters of the encapsulating member simultaneously: high UV transmissivity (at least 90%) combined with a specifically controlled refractive index. This multi-parameter optimization allows the material to transmit UV light effectively while minimizing internal reflection through refractive index matching, thereby improving light extraction efficiency without significant energy loss.
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 design significantly increases light extraction efficiency by reducing internal reflection and enhancing light distribution, particularly for ultraviolet light, while maintaining structural integrity and manufacturing efficiency.
Implementation Method 1
a light-transmitting thermoplastic resin encapsulating member that has at least 90% transmissivity for UV light
Implementation Method 2
a conductive layer with reduced reflectivity for UV light, allowing for efficient light distribution and extraction
Implementation Method 3
a plurality of semiconductor layers including an active layer adapted to generate ultraviolet light by recombination of electrons and holes
Data Source
AI summary
Disclosed is a semiconductor light emitting device including: A semiconductor light emitting device comprising: a semiconductor light emitting device chip including a plurality of semiconductor layers, and electrodes electrically connected to the plurality of semiconductor layers, the plurality of semiconductor layers including an active layer adapted to generate light by recombination of electrons and holes; an encapsulating member of a lens shape made of a light-transmitting thermoplastic resin having at least 90% transmissivity for light of a wavelength band ranging from 100 nm to 400 nm, for surrounding the semiconductor light emitting device chip; and an external substrate including conductive layers electrically connected to the electrodes of the semiconductor light emitting device chip. The encapsulating member is formed in a way that all faces of the encapsulating member are exposed to outside, except for a portion of the lower face thereof in contact with the external substrate.