Transparent Polyimide Film for Low Dielectric Applications
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Solution Overview
Problem
Conventional polyimides with high thermal stability and low dielectric constants are limited by their dark color and high dielectric constants, making them unsuitable for applications requiring transparency and optical properties in electronic materials.
Innovation Solution
A polyimide is synthesized by polymerizing a diamine with an acid dianhydride containing a nitrogen atom, such as nitrogen-containing piperazine-disuccinic anhydride, to achieve high transparency and a low dielectric constant, while maintaining thermal stability and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a wholly aromatic polyimide is used to achieve high thermal stability and mechanical strength, then the dielectric constant becomes high and transparency deteriorates
Solution Approach 1:
The patent changes the chemical structure parameters of the polyimide by introducing alicyclic structures and fluorinated groups. Specifically, it uses alicyclic tetracarboxylic dianhydrides (such as CPDA, CBDA, CHDA) and fluorinated compounds to modify the polymer backbone, which reduces electron density and improves light transmittance while maintaining thermal stability through the rigid cyclic structures.
Solution Approach 2:
The patent creates composite polyimide structures by combining alicyclic monomers with aromatic monomers in specific ratios. This composite approach allows the material to inherit the thermal stability of aromatic structures while the alicyclic components provide transparency. The fluorinated groups further enhance this by reducing dielectric constant and improving optical properties.
2Illumination intensity
If a polyimide is designed for high transparency using alicyclic structures, then the dielectric constant decreases, but thermal stability may be compromised
Solution Approach 1:
The patent optimizes the molecular weight and degree of polymerization of the alicyclic polyimide to achieve a balance between transparency and thermal stability. By controlling the polymerization process and selecting specific alicyclic monomers with appropriate ring sizes and substitutions, the material achieves high light transmittance while maintaining sufficient heat resistance for electronic applications.
3Strength
If conventional aromatic diamines and tetracarboxylic dianhydrides are used, then mechanical strength and heat resistance are achieved, but the material shows dark amber color and high dielectric constant
Solution Approach 1:
The patent introduces fluorinated groups into the polyimide structure, which significantly reduces the dielectric constant by decreasing the electron density and polarizability of the polymer chains. The fluorine atoms, being highly electronegative and small, create a low-density electron cloud that reduces dielectric losses while maintaining the mechanical integrity provided by the aromatic and alicyclic backbone structures.
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 polyimide exhibits a dielectric constant of 3.3 or less at 1 GHz and 80% or more transmittance at 550 nm, making it suitable for electronic and optical communication materials.
Implementation Method 1
the polyimide thus obtained has a low degree of polymerization and has to be improved in heat resistance, and furthermore, the optical properties required thereof are not satisfactory
Implementation Method 2
a polyimide, which exhibits high thermal stability, a low dielectric constant, and high light transmittance
Data Source
Figure 1
AI summary
This invention relates to a polyimide and a film using the same and, more particularly, to a polyimide, which can exhibit a low dielectric constant while retaining the superior properties thereof, and can thus be utilized as electronic materials such as protective materials or insulating materials for liquid crystal displays or semiconductors, and optical communication materials such as optical waveguide materials, and to a polyimide film including the same.