Cerium Oxide Dispersion Layer for LED Resin Color Stability
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Solution Overview
Problem
Conventional LED devices experience a decrease in luminance due to the coloring of silicone sealing resins under high-temperature and high-humidity conditions, which affects the luminescent efficiency, and the addition of metal oxides as thermal stabilizers can decrease transparency.
Innovation Solution
An LED device with a cerium oxide-dispersed composition layer, containing 0.005 to 0.03 parts by weight of cerium oxide per 100 parts by weight of silicone resin, is applied to the LED element to prevent coloring and maintain transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal oxide is added to silicone resin as thermal stabilizer, then heat resistance and ultraviolet light resistance are improved, but transparency decreases and visible light transmission is reduced
Solution Approach 1:
The patent changes the concentration parameter of cerium oxide from conventional high levels (0.1-5 parts by weight) to a specific low range (0.005-0.03 parts by weight), which maintains the thermal stabilizer function while minimizing the adverse effect on transparency and visible light transmission
Solution Approach 2:
The patent applies cerium oxide specifically as a thermal stabilizer in the silicone resin composition, concentrating the stabilizing function in this particular metal oxide rather than using general-purpose stabilizers, thereby achieving better compatibility with transparency requirements
2Illumination intensity
If large current is applied to LED element to increase luminance, then luminance is improved, but temperature of LED chip and silicone sealing resin increases causing coloring
Solution Approach 1:
The patent incorporates cerium oxide as a thermal stabilizer in advance into the silicone resin composition before sealing the LED element, so that when high current is applied and temperature increases, the stabilizer is already present to prevent oxidation and coloring of organic components, thereby maintaining luminance without degradation
Solution Approach 2:
The patent converts the harmful effect of high temperature (which causes coloring) into a beneficial opportunity by using the temperature increase to activate the thermal stabilizer function of cerium oxide, which prevents oxidation and protects organic components, thereby transforming the harmful thermal effect into a protective mechanism
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 cerium oxide-dispersed composition effectively prevents the silicone resin from coloring under high-temperature and high-humidity conditions, ensuring no decrease in transmission and maintaining high luminescent efficiency.
Implementation Method 1
cerium oxide, titanium oxide, or iron oxide is added and blended as a thermal stabilizer in order to improve the heat resistance
Implementation Method 2
metal oxide such as cerium oxide, titanium oxide, or iron oxide is added and blended as a thermal stabilizer in order to improve the heat resistance and ultraviolet light resistance
Data Source
AI summary
An LED device includes: a substrate; an LED element provided on the substrate; a cerium oxide-dispersed composition layer containing a silicone resin and cerium oxide in an amount of 0.005 parts by weight or more and 0.03 parts by weight or less with respect to 100 parts by weight of the silicone resin, for covering the LED element; and a sealing material containing no cerium oxide for covering the cerium oxide-dispersed composition layer.