DUV LED Packaging With Fluororesin Encapsulation and Stress Buffering
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Solution Overview
Problem
Conventional deep ultraviolet LED (DUV LED) packaging structures face issues with large size, high cost, low light emitting efficiency due to refractive index mismatch, and reliability problems caused by DUV light damage to silicone rubber encapsulants, leading to chip separation and reduced reliability.
Innovation Solution
A light-emitting device design featuring a substrate with a first and second chip, a first buffer layer to relieve stress, and an encapsulating layer made of fluorine-containing resin, which reduces the contact area between chips and the encapsulating layer, thereby alleviating stress and enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional DUV LED packaging structure uses a bowl-shaped ceramic carrier substrate with a cavity, then the LED chip can be received and protected, but the device size becomes large and the cost increases
Solution Approach 1:
The patent extracts and eliminates the bowl-shaped ceramic carrier substrate with cavity from the packaging structure. Instead, it uses a planar substrate with the LED chip directly mounted on the surface, removing the unnecessary three-dimensional cavity structure that increased device volume while providing equivalent chip protection and support functions
Solution Approach 2:
The patent employs a planar substrate configuration that provides a flat, thin mounting surface for the LED chip, replacing the bulky three-dimensional ceramic carrier. This planar approach reduces the vertical height and overall volume of the packaging structure while maintaining mechanical support and protection functions
2Device complexity
If a planar ceramic substrate with molded silicone rubber is used, then the structure is simplified, but the silicone rubber cracks under prolonged DUV light exposure and releases stress causing chip separation
Solution Approach 1:
The patent replaces the molded silicone rubber encapsulant with a fluoropolymer resin coating that can be applied as a thin film. This material, while simpler to apply, provides long-term stability under DUV irradiation without cracking or stress release, eliminating the reliability issues associated with silicone rubber
Solution Approach 2:
The patent changes the material parameters by selecting fluoropolymer resin with specific properties: high resistance to DUV light degradation, appropriate refractive index for light extraction, and stress-compatible mechanical properties. This material substitution fundamentally changes the degradation behavior under ultraviolet exposure, preventing the cracking and stress release that occur with silicone rubber
3Reliability
If molded silicone rubber is used as encapsulant, then the chip is protected, but the transmittance to DUV light is low and light emitting efficiency is reduced
Solution Approach 1:
The patent changes the optical parameter by selecting fluoropolymer resin with superior transmittance properties in the DUV wavelength range. This material has lower absorption and scattering coefficients for DUV light compared to silicone rubber, allowing more emitted light to escape the packaging structure and improving overall light extraction efficiency
Solution Approach 2:
The patent uses fluoropolymer resin as the encapsulating material that combines protective functions with optimized optical properties. The resin formulation is designed to provide both mechanical protection for the chip and high transmittance for DUV light, creating a composite material solution that simultaneously addresses protection and light extraction requirements
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 improves the reliability and light emitting efficiency of DUV LEDs by reducing stress-related issues and enhancing the encapsulating layer's resistance to ultraviolet radiation, while maintaining mechanical strength and heat dissipation properties.
Implementation Method 1
an active layer that is interposed between the first type semiconductor layer and the second type semiconductor layer and that is configured to emit a light
Implementation Method 2
The first buffer layer is disposed on the top surface of the second chip so as to relieve stress
Implementation Method 3
The encapsulating layer is made of fluorine-containing resin and disposed on the first surface of the substrate to allow the first chip, the first buffer layer and the second chip to be encapsulated between the substrate and the encapsulating layer
Data Source
AI summary
A light-emitting device includes a substrate, first and second chips, a first buffer layer, and an encapsulating layer. The substrate includes first and second surfaces opposite to each other. Each of the first and second chips is disposed on the first surface of the substrate, and is formed with top and bottom surfaces opposite to each other and side surfaces that are connected to the top surface and the bottom surface. The first buffer layer is disposed on the top surface of the second chip. The substrate has two edges spaced apart from each other in one of a first direction and a second direction. Each of the first and second chips has a minimum distance distant from one of the two edges in one of the two directions. Another light-emitting device is also disclosed.