LED Dies with Phosphor Binder for Uniform White Light
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Solution Overview
Problem
The high cost and complexity of LED-based lighting systems, particularly in broad-area general lighting applications, due to the need for multiple LEDs and active current control systems, as well as challenges in integrating phosphors uniformly for white light production, which affects efficiency and reliability.
Innovation Solution
A method involving semiconductor dies coated with a polymeric binder containing wavelength-conversion materials like phosphors, forming a composite wafer that is then separated into discrete portions with uniform binder thickness, allowing for uniform phosphor integration and reduced complexity in lighting systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple packaged LEDs operating at different wavelengths are used to generate white light, then the desired light intensity and color are achieved, but the system cost and complexity increase due to multiple LEDs and active control systems
Solution Approach 1:
The patent combines multiple LED dies and phosphor materials into a single integrated package, eliminating the need for separate control systems for multiple LEDs. The different wavelength LEDs are mounted on a common substrate with phosphors applied to convert wavelengths, creating one unified light source that outputs white light without requiring complex active control of individual LED currents.
Solution Approach 2:
Phosphor materials serve as intermediaries that convert light from LEDs of one wavelength to different wavelengths. The phosphors absorb light from blue or UV LEDs and re-emit at different wavelengths, effectively mediating the wavelength conversion process and eliminating the need for multiple controlled LED drivers.
2Illumination intensity
If phosphors are applied as a layer with binder material to convert LED wavelength, then white light is generated, but uniformity and reproducibility of light characteristics become difficult to achieve
Solution Approach 1:
The patent segments the phosphor application into discrete controlled regions on the substrate, with each region receiving specific phosphor materials in controlled amounts. This segmentation allows precise control over phosphor distribution and thickness, ensuring uniform light conversion characteristics across the entire device area.
Solution Approach 2:
The patent controls phosphor layer parameters such as thickness, composition, and particle size distribution to optimize light conversion uniformity. By precisely controlling these parameters during the phosphor application and curing process, consistent white light output is achieved across different manufacturing batches.
3Shape
If phosphor layer thickness varies across the LED surface, then the geometry affects light characteristics, but non-uniform color and light output result
Solution Approach 1:
The patent applies a release material to the substrate surface before phosphor application. This preliminary action creates a controlled interface that prevents phosphor binder from adhering to the substrate, ensuring uniform phosphor layer formation. The release material is removed after phosphor application, leaving a uniformly thick phosphor layer with consistent light conversion properties.
Solution Approach 2:
The patent uses a thin film release material that can be easily applied and removed, allowing precise control over phosphor layer thickness. The flexible nature of the thin film enables it to conform to the substrate surface and ensure uniform phosphor distribution without creating thickness variations that would affect color uniformity.
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 enables cost-effective and efficient integration of phosphors with LEDs, improving the uniformity and reliability of white light production, reducing the need for multiple LEDs and complex control systems, and enhancing the overall efficiency of lighting solutions.
Implementation Method 1
the phosphor layer absorbs a portion of the incident short-wavelength radiant flux and re-emits long-wavelength radiant flux
Implementation Method 2
Phosphors are typically composed of phosphorescent particles such as Y3A15012:Ce3+ (cerium-activated yttrium-aluminum-garnet, or YAG:Ce)
Data Source
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AI summary
Semiconductor dies such as light-emitting elements (LEEs) are coated with a polymeric binder, which is subsequently cured to form a composite wafer of a solid binder material and the dies suspended therein. The composite wafer may be divided into free-standing "white dies" each composed of the die and a portion of the cured binder that at least partially surrounds the die. The binder may advantageously contain wavelength-conversion material such as a phosphor or a collection of quantum dots. Various mold substrates and/or molds may be utilized to secure the semiconductor dies and/or to prevent coating of the contacts of the dies during the coating process.