Semiconductor Light Emitting Device Phosphor Layer Uniformity
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Solution Overview
Problem
Conventional semiconductor light emitting devices manufactured using electrophoresis for forming phosphor layers often suffer from reduced light extraction efficiency due to conductive films and have phosphor layers with low mechanical strength, making them prone to damage.
Innovation Solution
A method involving the formation of a conductive film on a semiconductor light emitting element, charging phosphor particles with an electrolyte containing a metallic salt, electrophoresis to create a phosphor layer, and subsequent removal of the conductive film using wet etching, along with a heat treatment for stabilization, to enhance light extraction efficiency and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conductive film is formed on the LED chip surface to define the electrophoresis region, then the phosphor layer can be uniformly formed in the desired region, but light extraction efficiency deteriorates due to the conductive film
Solution Approach 1:
The conductive film formation process is segmented into two distinct stages: first, a conductive film is formed on the LED chip surface to enable uniform phosphor layer deposition through electrophoresis; second, after phosphor layer formation, the conductive film is selectively removed using wet etching. This segmentation allows the conductive film to serve its temporary purpose during manufacturing while eliminating its harmful effect on light extraction in the final product.
Solution Approach 2:
The conductive film is formed preliminarily before phosphor layer deposition to establish the necessary electrical conductivity for uniform electrophoresis. This preliminary action enables precise control of phosphor distribution, and the conductive film is subsequently removed after it has fulfilled its manufacturing function, thereby eliminating light loss while preserving the benefit of uniform phosphor layer formation.
2Manufacturing precision
If electrophoresis is used to form the phosphor layer, then uniform thickness is achieved, but the phosphor layer has relatively low mechanical strength and is easily damaged
Solution Approach 1:
The phosphor layer is formulated as a composite material containing phosphor particles, binder resin, and solvent. The binder resin provides mechanical strength and cohesion to the phosphor particles, creating a robust composite structure that maintains uniform thickness from electrophoresis while resisting mechanical damage. This composite approach combines the deposition precision of electrophoresis with the mechanical durability of a resin matrix.
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 reduces light loss caused by the conductive film and improves the mechanical strength and uniformity of the phosphor layer, thereby enhancing the light emitting efficiency and stability of the semiconductor light emitting device.
Implementation Method 1
A phosphor layer is formed on the conductive film by electrophoresing the phosphor particles
Implementation Method 2
Phosphor particles are charged by mixing phosphor particles with an electrolyte having a metallic salt dissolved therein
Implementation Method 3
The conductive film is removed using wet etching
Implementation Method 4
the wet etching may be performed using an acidic solution as an etchant
Implementation Method 5
The method may further include performing a heat treatment for stabilizing the phosphor layer
Data Source
AI summary
A method of manufacturing a semiconductor light emitting device, includes forming a conductive film on a surface of a semiconductor light emitting element. Phosphor particles are charged by mixing phosphor particles with an electrolyte having a metallic salt dissolved therein. The semiconductor light emitting element having the conductive film formed thereon is immersed in the electrolyte having the charged phosphor particles. A phosphor layer on the conductive film is formed by electrophoresing the phosphor particles. The conductive film is removed using wet etching.