Ceramic Phosphor Plate Glass Composition for LED Reliability
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Solution Overview
Problem
Conventional white LED lighting using a resin matrix with oxide phosphors faces issues such as discoloration due to blue light energy, heat emission, and whitening due to compositional reactions with glass, limiting color temperature variability and reliability.
Innovation Solution
A ceramic phosphor plate is produced using a glass composition of 75-85 mol% SiO2, B2O3, and ZnO, with less than 25 mol% B2O3, 10-15 mol% alkali metal carbonate, and 1-5 mol% Al2O3, processed through ball milling, melting, and quenching to create a glass frit with a specific particle size, mixed with phosphors and fired to form a stable ceramic matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If oxide phosphors are used in a resin matrix for white LED lighting, then the structure is simple and easy to manufacture, but the resin deteriorates due to blue light energy causing discoloration and heat emission issues
Solution Approach 1:
The patent changes the fundamental material parameter from organic resin to inorganic glass-ceramic matrix, and adjusts the glass composition parameters (SiO2: 70-80 wt%, B2O3: 10-20 wt%, ZnO: 5-15 wt%) to achieve both manufacturability and high reliability under blue LED excitation and heat conditions
Solution Approach 2:
The patent creates a composite glass-ceramic matrix combining multiple oxide components (SiO2, B2O3, ZnO) with phosphor particles, where the glass matrix provides structural stability and heat resistance while the phosphor particles provide light conversion functionality
2Temperature
If glass is used as the matrix material for a phosphor plate to improve heat resistance, then heat emission is improved, but whitening occurs due to compositional reaction of moisture and glass elements over time
Solution Approach 1:
The patent optimizes the glass composition parameters, specifically controlling B2O3 content at 10-20 wt% (less than 25 mol%) and adding ZnO at 5-15 wt%, which changes the chemical stability parameters of the glass matrix to resist moisture-induced whitening while maintaining heat resistance
Solution Approach 2:
The patent introduces ZnO as an intermediary component that mediates between the glass matrix and moisture environment, forming a stable chemical structure that prevents the compositional reactions causing whitening, while allowing the glass to maintain its heat dissipation function
3Adaptability or versatility
If multiple phosphors (red and yellow) are mixed to achieve various color temperatures, then color temperature variability is improved, but the sintering temperature must be reduced because these phosphors are vulnerable to heat
Solution Approach 1:
The patent changes the matrix material parameter from conventional glass to a specifically formulated glass-ceramic composition with ZnO (5-15 wt%) and controlled B2O3 (10-20 wt%), which lowers the melting and sintering temperatures to be compatible with heat-sensitive red and yellow phosphors, enabling color temperature variability
4Reliability
If B2O3 content in glass is increased to improve glass composition for phosphor plate, then the glass properties are enhanced, but elements based on B, Na, and Li promote whitening due to hydrate formation
Solution Approach 1:
The patent precisely controls the B2O3 content parameter at 10-20 wt% (less than 25 mol%) and introduces ZnO at 5-15 wt%, which changes the chemical composition parameters to maintain glass stability while minimizing the hydrate formation that causes whitening
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 solution prevents whitening and maintains high optical properties and reliability under high temperature and humidity conditions, allowing for varied color temperatures and improved light efficiency.
Implementation Method 1
mixing the composition for 40 to 50 hours using a ball mill
Implementation Method 2
melting the composition at a temperature in a range of 1300 to 1600°C through a melting furnace
Implementation Method 3
preparing a glass cullet by quenching the melted composition in a twin roll
Implementation Method 4
firing the compressed mixture to produce the phosphor plate
Data Source
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AI summary
Provided is a glass composition for a ceramic phosphor plate, including: 75 to 85 mol% of an oxide mixture composed of Si02, B2O3 and ZnO; 10 to 15 mol% of at least one carbonate compound including an alkali metal; and 1 to 5 mol% of Al2O3, wherein a content of B2O3 is less than 25 mol%.