Patterned UV Silicone-Phosphor Layer for LED Light Extraction
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Solution Overview
Problem
The existing methods for forming a phosphor layer over light emitting diodes (LEDs) on submount tiles often require costly and time-consuming etching processes to remove undesired phosphor from reflective metallization and wire bond electrodes, leading to inefficiencies and increased costs.
Innovation Solution
A method involving a pre-formed UV sensitive silicone layer infused with phosphor, which is laminated or deposited over the LED dies, using masking and UV exposure to selectively remove the phosphor layer without etching, allowing reflective metallization and wire bonding while ensuring uniform light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If phosphor is deposited over the entire surface of the tile including reflective metallization, then complete phosphor coverage is achieved, but reflective metallization is covered and light reflection efficiency is reduced
Solution Approach 1:
The patent applies different treatments to different areas: the phosphor layer is removed from areas requiring reflection (metallization) while being retained on LED dies. This local differentiation allows each region to have the quality it needs - reflective areas remain reflective while LED areas get phosphor conversion.
Solution Approach 2:
The patent performs preliminary masking before phosphor deposition to prevent phosphor from landing on areas where it shouldn't stick, or performs preliminary deposition followed by selective removal using solvents or etchants. This preliminary action avoids the need for costly etching steps later.
2Manufacturing precision
If phosphor is deposited over wire bond electrodes, then complete phosphor coverage is achieved, but wire bonding capability is lost
Solution Approach 1:
The patent creates local exceptions in the phosphor layer by using masks or selective removal processes to preserve wire bond electrodes. This ensures that specific critical areas maintain their original properties while the rest of the surface receives the phosphor treatment.
Solution Approach 2:
The patent uses preliminary masking techniques to protect wire bond areas before phosphor deposition, or uses selective solvent/etch removal after deposition to clear these areas. This preliminary action prevents phosphor from interfering with subsequent wire bonding operations.
3Manufacturing precision
If etching process is used to remove undesired phosphor, then phosphor removal precision is achieved, but processing time and cost increase
Solution Approach 1:
The patent replaces the mechanical/chemical etching process with a simpler removal method using solvents or selective adhesion properties. This substitution maintains the precision of phosphor removal while dramatically reducing processing time and cost by avoiding complex etching equipment and chemicals.
Solution Approach 2:
The patent changes the removal mechanism from etching (chemical reaction) to dissolution (solvent action) or selective adhesion. This parameter change in the removal process maintains precision while improving speed and reducing cost by using simpler, faster removal mechanisms.
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 eliminates the need for etching, enhancing light efficiency, achieving uniform color distribution, and enabling quick, clean, and cost-effective production of phosphor-converted LEDs by preserving reflective metallization and allowing wire bonding.
Implementation Method 1
UV light is then applied to the silicone/phosphor layer exposed through the mask, which creates a cross-linked material that will remain after the silicone/phosphor layer is developed using a solvent
Implementation Method 2
the light from an LED die to be converted to a different color, such as white light, by depositing a phosphor over the LED die
Data Source
AI summary
LED dies are mounted a single submount tile (or wafer). The LED dies have a light emitting top surface. A uniformly thick layer of UV sensitive silicone infused with phosphor is then deposited over the tile, including over the tops and sides of the LED dies. Only the silicone/phosphor over the top and sides of the LED dies is desired, so the silicone/phosphor directly on the tile needs to be removed. The silicone/phosphor layer is then masked to expose the areas that are to remain to UV light, which creates a cross-linked silicone. The unexposed silicone/phosphor layer is then dissolved with a solvent and removed from the tile surface. The silicone/phosphor layer may be defined to expose a wire bond electrode on the LED dies. The tile is ultimately singulated to produce individual phosphor-converted LEDs.