Composite Powder for LED Light Reflective Substrate
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Solution Overview
Problem
Existing light reflective substrates for LEDs face challenges in achieving high light reflectance while being sintered at temperatures of 900°C or less, as they can cause short circuits when fired with silver paste for wiring.
Innovation Solution
A composite powder comprising 30-60 vol% glass powder and 40-70 vol% ceramic powder, with specific compositions of SiO2, B2O3, SrO+BaO, Al2O3, and ZnO, is used to create a light reflective substrate that can be densely sintered at 900°C or less, enhancing light reflectance and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light reflective substrate is fired at a high temperature (925°C) to achieve high light reflectance, then the light reflectance increases, but the risk of short circuit in wiring increases due to silver paste melting
Solution Approach 1:
The invention changes the firing temperature parameter from 925°C to 850°C or lower, and modifies the glass composition parameters (increasing B2O3 to 20-40 mass% and SrO+BaO to 20-40 mass%) to achieve dense sintering at the lower temperature, thereby preventing silver paste melting while maintaining high light reflectance
Solution Approach 2:
The invention uses a composite material system consisting of glass powder with specific composition (high B2O3 and SrO+BaO content) combined with ceramic powder, where the glass-ceramic composite enables low-temperature dense sintering that prevents wiring short circuits while achieving high light reflectance
2Stability of the object's composition
If the glass composition contains high SiO2 (45-65 mass %) to improve chemical stability, then the chemical stability increases, but the sintering temperature must be maintained at 925°C which causes wiring short circuit risk
Solution Approach 1:
The invention changes the glass composition parameters by reducing SiO2 to 10-30 mass% and significantly increasing B2O3 to 20-40 mass% and SrO+BaO to 20-40 mass%, which lowers the melting point and enables dense sintering at 850°C or lower while maintaining chemical stability
Solution Approach 2:
The invention discards the conventional high SiO2 glass composition approach and recovers chemical stability through the use of B2O3-rich glass composition with SrO+BaO, which provides both low-temperature sinterability and chemical durability
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 achieves high light reflectance and mechanical strength while preventing short circuits, allowing for efficient use in LED applications with improved low-temperature sintering properties.
Implementation Method 1
the composite powder is sintered densely at a temperature of 900° C. or less
Implementation Method 2
a light reflective substrate having a high light reflectance is required
Data Source
AI summary
A composite powder of the present invention includes a glass powder and a ceramic powder, wherein a content of the glass powder is from 30 vol % to 60 vol %, wherein a content of the ceramic powder is from 40 vol % to 70 vol %, wherein the glass powder includes as a glass composition, in terms of mass %, 10% to 30% of SiO2, more than 20% to 40% of B2O3, 20% to 40% of SrO+BaO, 0% to 10% of Al2O3, and 0% to 15% of ZnO, and wherein the composite powder is used for a light reflective substrate.