Phosphor Sedimentation Control in LED Packaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor light emitting devices with multiple phosphors face challenges in achieving stable color tone due to variations in specific gravity and grain size, leading to decreased production yield and limited color range, especially when using a single kind of phosphor with a blue light emitting element.
Innovation Solution
A semiconductor light emitting device comprising a semiconductor light emitting element, at least two kinds of phosphors that absorb and emit wavelength-converted light, and a sealing resin with the phosphors embedded, where the phosphors are combined using a binder resin to prevent sedimentation and maintain a consistent compounding ratio, and optionally, fine powder is attached to the surface of phosphors to further reduce sedimentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple kinds of phosphors are used to achieve desired emission color and white light, then the achievable color range is improved, but the color tone becomes unstable due to different specific gravities and grain size distributions causing sedimentation and compounding ratio variation
Solution Approach 1:
The patent combines multiple phosphors with different specific gravities and grain sizes into a single integrated phosphor layer using a transparent resin matrix. This merging approach maintains the color benefits of multiple phosphors while preventing their separation through sedimentation, as the resin binds them together into a unified structure that preserves the intended compounding ratio.
Solution Approach 2:
The transparent resin acts as an intermediary medium that suspends and holds the multiple phosphors in their intended positions and ratios. The resin mediates between the conflicting specific gravities of different phosphors, preventing sedimentation while allowing the phosphors to maintain their wavelength-conversion functions. This intermediary solution enables both color versatility and tone stability.
2Manufacturing precision
If a single kind of phosphor is used with a blue light emitting element to simplify manufacturing, then manufacturing precision is improved, but the achievable color range is limited to composites of only two colors
Solution Approach 1:
The transparent resin matrix provides a universal platform that can accommodate multiple types of phosphors with different optical properties. This multi-functional approach allows the same basic structure to achieve various color outputs by simply changing the phosphor composition, maintaining manufacturing simplicity while expanding color range beyond what a single phosphor can provide.
Solution Approach 2:
The patent creates a composite material system consisting of multiple phosphors embedded in a transparent resin. This composite structure combines the advantages of different materials: the phosphors provide wavelength conversion capabilities while the resin provides structural integrity and prevents sedimentation. The composite enables broader color range while maintaining ease of manufacture through a single integrated layer.
3Illumination intensity
If phosphors with different specific gravities and grain sizes are mixed, then the desired emission color can be achieved, but production yield decreases due to sedimentation and compounding ratio variation
Solution Approach 1:
The transparent resin is applied to the phosphors before they can sediment and separate. This preliminary action of encapsulating the phosphors in their intended compounding ratios prevents the sedimentation problem from occurring in the first place, ensuring consistent color quality and reducing production rework or rejection rates.
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 stabilizes the color tone and increases production yield by preventing sedimentation of phosphors, reducing chromaticity variation, and allowing for a broader color range by maintaining a consistent compounding ratio and adjusting the sedimentation rate of phosphors.
Implementation Method 1
at least two kinds of phosphors that absorb the light of the first wavelength and then emit wavelength-converted light
Data Source
AI summary
A semiconductor light emitting device includes a semiconductor light emitting element that emits light of a first wavelength, at least two kinds of phosphors that absorb the light of the first wavelength and then emit wavelength-converted light, sealing resin in which the at least two kinds of phosphors are dispersed and the semiconductor light emitting element is embedded, and binder resin. Combined bodies in which the at least two kinds of phosphors are combined by the binder resin are dispersed in the sealing resin.