Phosphor Slurry Application on Heated LED Substrates
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Solution Overview
Problem
Conventional methods for applying phosphor and other optical materials to semiconductor light emitting devices face challenges such as increased cost, complexity, non-uniformity, and difficulty in controlling the geometry and thickness of the phosphor layer, leading to inconsistent color temperature and emission characteristics.
Innovation Solution
Applying optical materials, such as phosphors, to heated semiconductor light emitting devices using a method that includes spraying the materials onto the device with a pressurized fluid or mechanical delivery mechanism, and exposing them to a curing agent like heat or radiation to achieve rapid curing and uniformity, particularly effective for non-planar substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional dispensing or stencil printing methods are used to apply phosphor to LEDs, then the phosphor layer can be applied, but the geometry and thickness of the phosphor layer cannot be controlled uniformly, resulting in non-uniform color temperature
Solution Approach 1:
The patent applies a phosphor slurry with controlled viscosity parameters to the LED surface, where the slurry flows to conformal coverage and then cures. By controlling the viscosity and flow characteristics of the phosphor slurry, uniform thickness and geometry are achieved across the LED surface, resolving the non-uniformity issue of conventional methods
Solution Approach 2:
The patent replaces the mechanical stencil printing or dispensing systems with a flow-based phosphor slurry application method. The slurry is applied and allowed to flow conformally over the LED surface, eliminating the need for precise mechanical positioning and stencil alignment, thereby achieving uniform phosphor layer geometry
2Reliability
If multiple LEDs are arranged with precise spacing and phosphor is applied using stencil, then coverage can be achieved, but the process becomes complex and difficult to reproduce consistently
Solution Approach 1:
The patent employs a universal phosphor slurry application process that can be used for individual LEDs or arrays of LEDs without requiring different equipment or procedures. The same slurry formulation and application method work consistently across multiple devices, simplifying the manufacturing process and improving reproducibility
Solution Approach 2:
The patent extracts the phosphor application step from the complex multi-LED assembly process by using a separate, standardized phosphor slurry application method. This allows the phosphor coating to be applied independently and consistently to each LED or LED array, decoupling the phosphor application complexity from the LED positioning complexity
3Ease of manufacture
If phosphor-containing encapsulant material is dispensed over the LED, then the LED is covered, but the phosphor layer thickness and geometry are difficult to control
Solution Approach 1:
The patent modifies the phosphor material into a slurry form with specific viscosity parameters that enable controlled flow and conformal coverage. The slurry's rheological properties are tuned to allow it to spread uniformly over the LED surface and then maintain a consistent thickness during curing, achieving both ease of application and manufacturing precision
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 results in a conformal, uniform, and consistent optical material layer with improved control over phosphor distribution, reducing settling and stratification, and enhancing the thermal conductivity and color rendering properties of the LED devices.
Implementation Method 1
The luminescent solution is sprayed directly on the heated LED structure to provide a conformal layer including phosphor particles that is cured by the thermal energy of the heated LED structure
Implementation Method 2
The volatile solvent is evaporated by the thermal energy of the heated LED structure from the luminescent solution
Implementation Method 3
The luminescent solution is atomized and sprayed directly on the heated LED structure using a flow of pressurized gas
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
Methods are disclosed including heating an optical element. An optical material is applied to the heated optical element to provide a conformal layer that is cured via the thermal energy in the heated optical element.