Fluorinated Encapsulation for LED Stress and Thickness
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Solution Overview
Problem
Current methods for encapsulating light-emitting diodes (LEDs) using fluoro polymers face challenges such as insufficient thickness, uniformity issues, and durability problems due to volatility and stress-induced damage, leading to reduced light-emitting brightness and conduction failures.
Innovation Solution
A curable composition comprising a perfluoro polymer with specific carbon-carbon double bonds, a perfluorocyclic monoene, and a perfluorocyclic polyene, along with a polymerization initiator, is used to create a fluorinated cured product that provides excellent transparency, light resistance, and mechanical strength, allowing for a stress-free encapsulation of LEDs in a light-transmitting manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluoro polymer is used as a coating agent for LED encapsulation, then light resistance and transparency are improved, but the coating film thickness cannot reach the necessary 100 μm due to low polymer concentration (around 25 mass%)
Solution Approach 1:
The patent changes the concentration parameter of the fluoro polymer in the coating agent from around 25 mass% to 30-80 mass%, enabling the formation of coating films with thickness of 100 μm or more while maintaining excellent light resistance and transparency properties
Solution Approach 2:
The patent creates a composite coating agent system combining fluoro polymer with specific fluorinated solvents and additives, achieving both high polymer concentration (30-80 mass%) for sufficient thickness and excellent processability for uniform coating formation
2Length of stationary object
If the coating agent is applied repeatedly to increase thickness, then coating film thickness is improved, but uniform encapsulation becomes difficult due to crack formation and foaming
Solution Approach 1:
The patent optimizes the solvent composition parameter (using fluorinated solvents with specific boiling points and properties) and polymer concentration (30-80 mass%) to enable single-step or reduced-step coating processes that form uniform 100 μm thick films without crack formation or foaming, eliminating the need for repeated coating applications
Solution Approach 2:
The patent develops a coating formulation that replicates the desired final coating properties (uniformity, thickness, absence of defects) in a single application step, rather than requiring multiple sequential coating steps that each introduce potential defects
3Illumination intensity
If bulk polymerization of fluoromonomer is used to produce high transmittance molded product, then transparency is improved, but heat resistance becomes insufficient and volume control becomes difficult due to monomer volatility
Solution Approach 1:
The patent performs preliminary polymerization of fluoromonomer to produce pre-formed fluoro polymer chains with controlled molecular weight and structure before using them in the final coating formulation, ensuring both high transparency and heat resistance in the cured coating
Solution Approach 2:
The patent changes the physical state parameter from volatile fluoromonomer to non-volatile fluoro polymer, eliminating volume control issues during curing while maintaining high UV transmittance and adding heat resistance through the polymer's inherent thermal stability
4Productivity
If radical bulk polymerization of fluoromonomer is used, then polymerization speed is improved, but stress formation damages devices and electrodes due to volume shrinkage
Solution Approach 1:
The patent performs preliminary polymerization to form pre-polymer or oligomer structures with reduced shrinkage potential before final curing, allowing rapid polymerization to proceed while minimizing stress formation that could damage encapsulated devices
Solution Approach 2:
The patent incorporates flexible segments or plasticizers in the fluoropolymer structure that act as cushioning elements during polymerization, absorbing the volume shrinkage stress before it can propagate to damage sensitive electronic components
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 resulting fluorinated cured product exhibits high transparency, heat resistance, and mechanical strength, reducing stress-induced damage and maintaining LED brightness and conduction integrity even under thermal stress and long-term use.
Implementation Method 1
a curable composition comprising a perfluoro polymer (a) containing a unit derived from a perfluorodiene having two polymerizable carbon-carbon double bonds
Data Source
Figure 1
AI summary
To provide a curable composition which provides a fluorinated cured product excellent in transparency, light resistance, heat resistance and mechanical strength and hardly damaged by stress concentration. A curable composition comprising a perfluoro polymer (a) containing a unit derived from a perfluorodiene having two polymerizable carbon-carbon double bonds, wherein two carbon atoms in one carbon-carbon double bond form the main chain, and the other carbon-carbon double bond forms a side chain; a perfluorocyclic monoene (b) having at least 8 carbon atoms, which has an alicyclic structure made of carbon atoms and optionally containing an oxygen atom, and one polymerizable carbon-carbon double bond, wherein at least one of two carbon atoms forming the carbon-carbon double bond is a carbon atom constituting the alicyclic structure; and a polymerization initiator (i).