Wavelength Conversion Laminate Silica Confining Layer
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Solution Overview
Problem
Conventional methods for preparing wavelength converting members often result in uneven shrinkage and light reflection during calcination, leading to impaired shape and reduced light transmittance due to the interaction between the glass melt and confining layers, particularly when alumina is used.
Innovation Solution
A laminate comprising a green sheet with a glass matrix and inorganic phosphor powder, surrounded by confining layers made of silica powder on both sides, which are not in contact with the green sheet, allowing calcination at 800°C or lower while maintaining high light transmittance and refractive index, and enabling the removal of confining layers post-calcination to prevent light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a confining layer is laminated on only one side of the green sheet and calcined, then the manufacturing process is simplified, but the green sheet shrinks unevenly during calcination, impairing the shape of the wavelength converting member
Solution Approach 1:
The confining layer is segmented into multiple independent layers, with at least one confining layer positioned on each side of the green sheet. This segmentation allows each confining layer to independently control the shrinkage of its adjacent side, ensuring uniform overall shape while maintaining manufacturing simplicity through modular construction.
2Manufacturing precision
If alumina powder is used as a confining layer component, then the confining layer provides good shape control, but the glass melt penetrates between alumina particles during calcination to form a thin layer that reflects light, reducing light transmittance
Solution Approach 1:
A silica-based confining layer is introduced as an intermediary between the green sheet and the alumina particles. This silica layer prevents direct contact and penetration between the glass melt and alumina particles, thereby eliminating the light-reflecting thin layer formation while preserving the shape control benefits of the alumina-containing confining layer structure.
3Reliability
If the confining layer is removed by polishing and/or etching after calcination, then the interface layer is completely removed, but this additional processing step increases manufacturing complexity and time
Solution Approach 1:
The removal method transitions from mechanical/chemical processing (polishing and etching) to thermal processing by changing the temperature parameter. By heating to a temperature that softens or decomposes the confining layer material, the interface layer is removed through thermal degradation rather than mechanical abrasion or chemical etching, eliminating the need for complex post-calcination processing steps.
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 process ensures a wavelength converting member with high light transmittance, refractive index, and maintained shape, suitable for LED applications by preventing light reflection and ensuring even calcination without compromising optical characteristics.
Implementation Method 1
Light emitting diodes (LEDs) used for conventional lighting and the like are generally composed of blue LEDs and wavelength converting members that absorb blue light emitted from the blue LEDs and achieve white light through the emission of yellow, green, or red light.
Implementation Method 2
the layer formed between the green sheet and the confining layer is not completely removed but remains on the surface of the wavelength converting member, thereby reflecting light emitted from a light source. Thus, it has a disadvantage that the amount of light to reach a phosphor is reduced.
Data Source
AI summary
The present invention relates to a laminate for preparing a wavelength converting member and a process for preparing a wavelength converting member. More particularly, the present invention relates to a laminate for preparing a wavelength converting member, which can be calcined at a temperature of 800° C. or lower, preferably 700° C. or lower and has a high light transmittance, a high refractive index, and a good shape upon the calcination, whereby it can be advantageously used for LEDs, and a process for efficiently preparing the wavelength converting member using a confining layer comprised of specific components.