Centrifugal Segmentation of Fluorescent Sealing Layers for Moisture Resistance
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Solution Overview
Problem
Conventional fluoride fluorescent materials activated with Mn4+ in light emitting devices suffer from optical output reduction and chromaticity deviation due to reaction with atmospheric moisture, leading to manganese dioxide formation, which complicates their application in reliable backlighting for liquid crystal display devices.
Innovation Solution
A light emitting device manufacturing method involving a package with a recess, where a sealing material containing fluoride fluorescent particles with tetravalent manganese ions is centrifugally sedimented to form a two-layer sealing member, with a first layer covering the light emitting element and a second layer devoid of fluorescent particles, effectively blocking moisture and maintaining a lower manganese ion concentration on the surface to prevent manganese dioxide formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fluoride fluorescent materials with Mn4+ are used to achieve narrow emission peak half width and high color purity, then chromaticity reproduction is improved, but optical output reduction and chromaticity deviation occur due to manganese dioxide formation from moisture reaction
Solution Approach 1:
The sealing member is divided into two distinct layers: a first sealing member portion containing fluorescent material particles that contacts the light emitting element, and a second sealing member portion without fluorescent material particles that forms the outer protective layer. This segmentation allows the inner layer to maintain optical functionality while the outer layer provides moisture barrier protection, preventing manganese dioxide formation and ensuring long-term optical output stability.
Solution Approach 2:
The sealing material composition is made non-uniform by creating a two-layer structure with different properties. The first layer has high fluorescent material content for optimal light conversion, while the second layer has zero fluorescent material content to provide superior moisture resistance. This local quality differentiation resolves the contradiction between maintaining chromaticity reproduction and preventing moisture-induced degradation.
2Manufacturing precision
If a single-layer sealing member containing fluorescent material is used to maintain optical performance, then chromaticity is maintained, but moisture penetration occurs leading to manganese dioxide formation
Solution Approach 1:
The second sealing member portion acts as an intermediary protective layer between the external environment and the fluorescent material-containing first sealing member portion. This intermediary layer provides a moisture barrier function, preventing atmospheric moisture from reaching the fluorescent materials and causing manganese dioxide formation, while the first layer maintains chromaticity through efficient light conversion.
3Use of energy by moving object
If fluorescent material particles are distributed throughout the entire sealing member for optimal light conversion, then optical efficiency is improved, but moisture resistance deteriorates due to increased reaction sites
Solution Approach 1:
The sealing member is segmented into two functional zones: the first sealing member portion contains fluorescent material particles optimized for light conversion efficiency, while the second sealing member portion is free of fluorescent material particles and provides enhanced moisture resistance. This segmentation concentrates fluorescent materials only where optically necessary, reducing overall moisture reaction sites while maintaining optical efficiency.
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
This approach suppresses optical output reduction and chromaticity deviation, ensuring long-term reliability and durability of the light emitting device by preventing manganese dioxide formation and maintaining high moisture resistance.
Implementation Method 1
injecting a sealing material in the recess of the package, sedimenting centrifugally the fluorescent material particles toward a bottom surface in the recess to form a sealing member that includes a first sealing member portion and a second sealing member portion
Data Source
AI summary
A method of manufacturing a light emitting device includes providing a package; disposing a light emitting element in a recess of the package; injecting a sealing material in the recess, the sealing material including fluorescent material particles and a binder, the fluorescent material particles including particles of fluoride fluorescent material that include a surface region and an inner region, both the surface region and the inner region having a composition including: tetravalent manganese ions, at least one element or compound selected from the group consisting of alkali metal elements and NH4+, and at least one element selected from the group consisting of Group 4 and Group 14 elements; sedimenting centrifugally the fluorescent material particles toward a bottom surface in the recess to form a sealing member that comprises a first sealing member portion and a second sealing member portion; and curing the binder to form a cured sealing member.