Ceramic Substrate Composition for LED Packages
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Solution Overview
Problem
Conventional ceramic substrates for LED packages face challenges with low flexural strength and reflectance, which can lead to breakage and reduced light intensity, while also requiring high-temperature sintering processes that increase costs and complexity.
Innovation Solution
A glass ceramic material composition comprising borosilicate glass, alumina filler, and high refractive index fillers like titania or zirconia, optimized to achieve high flexural strength and reflectance with low glass crystallinity, allowing for low-temperature co-firing and efficient light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ceramic materials (alumina or aluminum nitride) are used for LED packages, then durability against heat and light is improved, but reflectance deteriorates and process cost increases due to high-temperature sintering requirements
Solution Approach 1:
The patent employs a composite material system consisting of glass matrix combined with ceramic fillers (alumina, aluminum nitride, silicon oxide) to create an LTCC substrate that integrates the heat and light resistance of ceramics with the low-temperature sintering capability of glass, eliminating the need for high-temperature processing while maintaining durability
Solution Approach 2:
The patent changes the sintering temperature parameter from conventional high temperatures (>1500°C) to low temperatures (850-900°C) by utilizing the glass phase's low-temperature flowability, which enables the ceramic composite to be sintered at significantly reduced temperatures while achieving sufficient density and mechanical properties
2Ease of manufacture
If LTCC substrate is used for LED packages, then reflectance and ease of manufacture are improved, but flexural strength deteriorates
Solution Approach 1:
The patent uses a composite formulation with glass as the matrix and incorporates high-volume ceramic fillers (alumina, aluminum nitride, silicon oxide) to reinforce the structure, achieving flexural strength of at least 250 MPa while maintaining the low-temperature sintering and high reflectance characteristics of LTCC
Solution Approach 2:
The patent optimizes the local composition and distribution of ceramic fillers within the glass matrix, ensuring proper particle sizing and arrangement to maximize mechanical strength at critical locations while preserving the overall low-temperature processability and optical properties
3Illumination intensity
If high refractive index filler is added to improve reflectance, then light reflection is improved, but sintering properties deteriorate leading to insufficient flexural strength
Solution Approach 1:
The patent creates a multi-component composite system that balances high refractive index fillers (for reflectance) with sintering aids (alumina, aluminum nitride, silicon oxide) that promote low-temperature sintering and strength development, achieving both optical and mechanical performance targets simultaneously
Solution Approach 2:
The patent optimizes the refractive index parameter of the filler materials to achieve sufficient light reflection while selecting filler combinations and sizes that maintain good sintering characteristics and flexural strength, balancing optical and mechanical requirements through parameter optimization
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 provides a ceramic substrate with high flexural strength, reduced warpage, and enhanced reflectance, enabling cost-effective mass production of LED packages with improved light efficiency and durability.
Implementation Method 1
can be sintered at a low temperature as compared with a conventional ceramic substrate since it is sintered employing low temperature flowability of glass. Commonly, it is capable of being fired at a temperature at a level of from 850° C. to 900° C.
Implementation Method 2
it is characterized by having a high reflectance as compared with an alumina substrate and an aluminum nitride substrate, since light is diffusely reflected on an interface between glass and ceramic particles
Data Source
AI summary
A ceramic material composition comprising from 20 to 50 mass % of a borosilicate glass powder, from 25 to 55 mass % of an alumina filler powder and from 10 to 45 mass % of a filler powder (a high refractive index filler powder) having a refractive index higher than the alumina filler powder, wherein the borosilicate glass powder comprises, as calculated as oxides, from 30 to 70 mass % of SiO2, from 5 to 28 mass % of B2O3, from 5 to 30 mass % of Al2O3, from 3 to 35 mass % of CaO, from 0 to 25 mass % of SrO, from 0 to 25 mass % of BaO, from 0 to 10 mass % of Na2O, from 0 to 10 mass % of K2O, from 0.5 to 10 mass % of Na2O+K2O and from 3 to 40 mass % of CaO+SrO+BaO, and satisfies the following conditions:in the borosilicate glass powder, as represented by mass %, the value of “three times the B2O3 content”+“twice (the CaO content+the SrO content+the BaO content)”+“ten times (the Na2O content+the K2O content)”, is within a range of from 105 to 165.