Glass Ceramic Substrate with Oriented Flat Fillers for LED Reflectance
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Solution Overview
Problem
Existing glass ceramic substrates for light emitting devices face challenges in achieving high reflectance while maintaining sufficient strength and preventing void formation, which can lead to breakage and connection defects due to stress and poor sintering properties.
Innovation Solution
A glass ceramic body with a glass matrix and flat fillers dispersed in the same direction, where the flat fillers have a specific length and thickness ratio, are used to enhance reflectance and strength, reducing void formation and improving sintering properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If fine ceramic particles (0.3 to 1.0 μm) are incorporated in a large amount in glass to increase reflectance, then the reflectance is improved, but the sintering property deteriorates, strength decreases, and voids are likely to be formed at the surface and inside the substrate
Solution Approach 1:
The patent changes the particle size parameter of ceramic fillers from fine particles (0.3 to 1.0 μm) to medium particles (1.0 to 3.0 μm), and controls the occupation area ratio within a specific range (20 to 50%). This parameter optimization allows achieving high reflectance while maintaining good sintering properties and substrate strength, preventing void formation.
Solution Approach 2:
The patent uses a composite material system comprising glass and ceramic particles with specific size and concentration ranges. This composite structure enables simultaneous achievement of high reflectance (through ceramic particle interfaces) and good mechanical properties (through controlled sintering), resolving the contradiction between reflectance improvement and strength maintenance.
2Illumination intensity
If the occupation area of ceramic particles is increased to improve reflectance, then the reflectance is improved, but the sintering property deteriorates and voids are likely to be formed
Solution Approach 1:
The patent optimizes the occupation area ratio of ceramic particles to a specific range (20 to 50%) rather than maximizing it. This parameter control ensures sufficient reflectance (through adequate ceramic particle interfaces) while maintaining good sintering properties and preventing void formation, thus improving reliability.
3Strength
If glass ceramic substrate is used to achieve high reflectance and strength, then reflectance and strength are improved, but firing shrinkage unevenness occurs, reducing productivity
Solution Approach 1:
The patent controls the particle size of ceramic fillers within a specific range (1.0 to 3.0 μm) and occupation area ratio (20 to 50%), which optimizes the balance between strength enhancement and firing shrinkage control. This parameter optimization ensures uniform sintering and reduces shrinkage unevenness, improving productivity.
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 reflectance and strength, minimizing voids and breakage, and preventing defects such as connection defects by optimizing the orientation and proportion of flat fillers within the glass ceramic substrate.
Implementation Method 1
The glass ceramic substrate comprises a glass powder and a ceramic powder such as an alumina powder, and it has a large difference in refractive index between glass and ceramics and many interfaces between them, whereby the glass ceramic substrate has a higher reflectance than conventional ceramic substrates
Implementation Method 2
a substrate is required to have a high thermal conductivity, be able to quickly dissipate heat generated from the light-emitting element
Data Source
AI summary
To provide a glass ceramic body, whereby light which transmits through the substrate and leaks (i.e. emits) out of the incident direction is reduced, and the number of voids at the surface of the substrate and in the inside of the substrate is low,A glass ceramic body 10 comprising a glass matrix 11 and flat fillers 12 dispersed therein, wherein the flat fillers 12 are dispersed in the glass matrix 11 so that their individual thickness directions would be substantially in the same direction; and in a cross-section along the thickness direction of the flat filler 12 in the glass matrix 11, the occupation area of the flat fillers 12 having a length in their flat direction of from 0.5 to 20 μm and a length in their thickness direction of from 0.02 to 0.25 μm per unit area of the cross-section is from 30 to 48%.