Layered CSP White LED Phosphor Structure for Moisture Reliability
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Solution Overview
Problem
Manganese-activated fluoride photoluminescence materials are costly and require high usage amounts in light emitting devices, leading to increased manufacturing costs and stability issues due to moisture sensitivity.
Innovation Solution
A packaged white light emitting device design featuring a layered photoluminescence structure with a first layer comprising 75 wt % to 100 wt % manganese-activated fluoride photoluminescence material, and a second layer generating light in the green to red region, which reduces the overall usage of manganese-activated fluoride material and enhances moisture reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If manganese-activated fluoride photoluminescence material is used to achieve high color gamut and color rendering, then color quality is improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent divides the photoluminescence conversion function into multiple layers: a first layer containing manganese-activated fluoride phosphor for red light conversion, and a second layer containing green/yellow phosphor for complementary color conversion. This segmentation allows optimization of each layer's function, reducing the total amount of expensive manganese-activated fluoride material needed while maintaining high color gamut and color rendering quality.
2Illumination intensity
If high usage amount of manganese-activated fluoride phosphor is used to achieve target color point, then color quality is improved, but manufacturing cost increases
Solution Approach 1:
The patent segments the phosphor conversion function across two layers, with the first layer optimized for red light conversion using manganese-activated fluoride phosphor and the second layer handling green/yellow conversion. This segmentation reduces the total quantity of expensive manganese-activated fluoride phosphor required while achieving the same color point and quality metrics.
Solution Approach 2:
The patent optimizes the thickness and composition parameters of each layer to maximize conversion efficiency. By carefully controlling the parameters of the first layer (manganese-activated fluoride phosphor concentration, layer thickness) and the second layer, the system achieves target color points with reduced phosphor usage amounts.
3Illumination intensity
If high loading of photoluminescence material in silicone is used to achieve desired color point, then color quality is improved, but dispensing process stability deteriorates
Solution Approach 1:
The patent segments the high-loading photoluminescence function into two separate layers, allowing each layer to have optimized material concentrations that maintain dispensing stability. The first layer can contain higher manganese-activated fluoride phosphor loading without compromising process reliability, while the second layer provides complementary conversion with its own optimized composition.
4Illumination intensity
If manganese-activated fluoride phosphor is used for color conversion, then color quality is improved, but moisture sensitivity increases leading to reduced reliability
Solution Approach 1:
The patent segments the photoluminescence conversion into two layers, with the second layer positioned to protect the moisture-sensitive manganese-activated fluoride phosphor in the first layer. This structural segmentation provides a barrier against moisture ingress while maintaining the color conversion functionality of both layers.
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 reduces the usage of manganese-activated fluoride photoluminescence material by up to 60%, lowers manufacturing costs, and improves moisture reliability, while maintaining effective color conversion and stability.
Implementation Method 1
Photoluminescence wavelength converted light emitting LEDs include one or more photoluminescence materials, which absorb a portion of the excitation light and re-emit light of a different color
Implementation Method 2
the absorption capability of manganese-activated fluoride phosphors is substantially lower than that of europium-activated red nitride phosphor materials
Data Source
AI summary
A light emitting device includes a Chip Scale Packaged (CSP) LED, the CSP LED including an LED chip that generates blue excitation light; and a photoluminescence layer that covers a light emitting face of the LED chip, wherein the photoluminescence layer comprises from 75 wt % to 100 wt % of a manganese-activated fluoride photoluminescence material of the total photoluminescence material content of the layer. The device/CSP LED can further include a further photoluminescence layer that covers the first photoluminescence and that includes a photoluminescence material that generates light with a peak emission wavelength from 500 nm to 650 nm.