Composite Encapsulation Material for Uniform LED Phosphor Dispersion
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Solution Overview
Problem
Conventional light-emitting diode (LED) packaging technologies face issues with uneven phosphor powder distribution, leading to non-uniform white light emission and poor light extraction efficiency due to sedimentation and dispersion problems, as well as difficulty in maintaining the shape of the encapsulation material after dispensing.
Innovation Solution
A composite encapsulation material comprising a polymer glue material and a viscosity modifier with functional groups capable of forming non-covalent interactions, which creates a tangled net structure that maintains shape under stress and improves viscosity ratios, preventing sedimentation and enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If phosphor powder and glue are mixed with conventional methods, then the phosphor powder can be coated on the LED surface, but the phosphor powder sediments and disperses unevenly due to density difference, causing non-uniform light emission
Solution Approach 1:
The patent modifies the rheological parameters of the encapsulation material by adding viscosity modifiers and using polymer glue materials with specific viscosity characteristics. The material exhibits shear-thinning behavior where viscosity decreases at higher shear rates during dispensing, then recovers to maintain phosphor suspension stability after coating, preventing sedimentation and ensuring uniform distribution.
Solution Approach 2:
The patent creates a composite encapsulation material system combining polymer glue material with viscosity modifiers. This composite formulation achieves both processability during dispensing and suspension stability for phosphor powder, resolving the contradiction between coating application and uniform distribution maintenance.
2Stress or pressure
If conventional glue material is used with good wetting effect, then adhesion to substrate is improved, but the glue material spreads and cannot maintain shape after dispensing, affecting light extraction efficiency
Solution Approach 1:
The patent employs a dynamic viscosity model where the encapsulation material's viscosity changes with shear rate. During dispensing (high shear rate), viscosity is low allowing easy application and substrate wetting. After dispensing (low shear rate), viscosity increases to maintain the desired shape and prevent spreading, while adhesion to the substrate is maintained through the polymer glue material's bonding properties.
3Ease of operation
If the encapsulation material is dispensed with high flowability, then the dispensing process is easier, but the material spreads and cannot form an ideal lens shape
Solution Approach 1:
The patent utilizes shear-thinning rheological behavior where the encapsulation material exhibits low viscosity at high shear rates during dispensing, enabling easy flow and filling. Once dispensing stops and shear rate decreases, viscosity increases dramatically to maintain the formed lens shape and prevent spreading, achieving both ease of operation and shape retention.
4Shape
If the viscosity of the encapsulation material is increased to prevent spreading, then shape retention is improved, but the dispensing process becomes more difficult
Solution Approach 1:
The patent changes the viscosity parameter dynamically through shear rate variation. The encapsulation material is formulated with viscosity modifiers to exhibit shear-thinning characteristics, where viscosity is low during high-shear dispensing operations for ease of operation, then increases at low shear rates to maintain shape retention, resolving the contradiction between dispensing ease and shape control.
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 composite encapsulation material ensures uniform phosphor distribution, maintains shape during dispensing, and improves light extraction efficiency by adjusting viscosity based on shear rate, addressing the limitations of conventional materials.
Implementation Method 1
The viscosity modifier (B) has a functional group that is capable of forming a non-covalent interaction with the polymer glue material (A)
Implementation Method 2
At room temperature, the ratio (log(η0)/log(η∞)) of the a logarithm of the a viscosity (log(η0)) of the composite encapsulation material at a shear rate of 1×10−3 s−1 to the a logarithm of the a viscosity (log(η∞)) of the composite encapsulation material at a shear rate of 1×102 s−1 is 1.1-2.5
Data Source
AI summary
A composite encapsulation material is provided, which includes (A) a polymer glue material and (B) a viscosity modifier. The viscosity modifier (B) has a functional group capable of forming non-covalent interaction with the polymer glue material (A). At room temperature, the ratio (log(η0)/log(η28 )) of the logarithm of the viscosity ((log(η0)) of the composite encapsulation material at the shear rate of 1×10−3 s−1 to the logarithm of the viscosity (log(η∞)) of the composite encapsulation material at the shear rate of 1×102 s−1 is 1.1-2.5.