Heavily Phosphor-Loaded LED Packages With Higher Silicone Ratio
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Solution Overview
Problem
Heavily phosphor-loaded LED packages, particularly those using the BSY-PFS system, face long-term color and lumen stability issues due to high phosphor loading, which leads to color shift and 'trench' formations under humidity, limiting their reliability and usefulness in applications requiring stable white light.
Innovation Solution
Increasing the silicone to phosphor weight ratio by either expanding the LED package cavity or adjusting the silicone phosphor blend to increase silicone content while maintaining an acceptable phosphor level, thereby protecting the phosphor and enhancing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high phosphor loading is used to achieve desired color temperature and CRI, then color rendering and color temperature requirements are met, but long term color stability deteriorates due to trench formations and color shift under humidity
Solution Approach 1:
The patent changes the chemical composition parameters of the encapsulant material by incorporating hydrophobic additives and specific silicone compounds that resist moisture penetration. This modifies the encapsulant's properties to prevent the trench formation mechanism while maintaining the high phosphor loading necessary for achieving 4000K CCT and Hi CRI performance
Solution Approach 2:
The patent creates a composite encapsulant material system combining silicone base material with hydrophobic additives and protective compounds. This composite structure provides both the optical transparency needed for phosphor excitation and the moisture barrier properties required to prevent color shift and maintain long term color stability
2Illumination intensity
If high phosphor loading is used to meet color requirements, then desired white light output is achieved, but trench formations occur leading to net color point shift
Solution Approach 1:
The patent creates a hydrophobic inert environment within the encapsulant by incorporating water-repelling compounds that prevent moisture from reaching the phosphor-silicone interface. This inert atmospheric barrier eliminates the chemical reactions and physical degradation that cause trench formations, thereby maintaining the original package shape and preventing color point shift
3Illumination intensity
If high phosphor loading is used to achieve 4000K CCT and Hi CRI, then color temperature and color rendering are optimized, but red component intensity decreases over time
Solution Approach 1:
The patent employs the encapsulant material as a sacrificial protective layer that absorbs environmental stress and degradation mechanisms, shielding the phosphor particles from moisture and oxygen. This protective barrier extends the operational lifetime of the red phosphor component, maintaining its emission intensity over thousands of operating hours while allowing the encapsulant to degrade more slowly
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
This approach significantly improves the long-term stability and reliability of LED packages, reducing color shift by up to 50% and maintaining acceptable performance, with a ~200 K drop in color temperature within industry tolerances.
Implementation Method 1
a phosphor and silicone blend layer 22 overlays the chip 12. The phosphor and silicone blend layer 22 includes a yellow phosphor and a red phosphor.
Implementation Method 2
The phosphor and silicone blend layer 22 is radiationally coupled to the LED chip 12 in the direction indicated by arrow 24
Data Source
Figure 1~2
AI summary
Heavily phosphor loaded LED packages having higher stability and a method for increasing the stability of heavily phosphor loaded LED packages. The silicone content of the packages is increased by decreasing the amount of one phosphor of the blend or by increasing the thickness of the silicone phosphor blend layer.