Polyimide Film for High-Frequency Electronics with Low Dielectric Loss
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Solution Overview
Problem
Conventional polyimide films face challenges in achieving a balance between heat resistance, high-frequency signal transmission, and flexibility, with issues such as high dielectric loss tangent, low signal strength, and susceptibility to curling, which limits their application in high-frequency electronics.
Innovation Solution
A polyimide film is developed by reacting aromatic diamines with aromatic tetracarboxylic acid anhydrides, achieving a planar orientation coefficient of 0.79-0.89 and a dielectric constant of 2.7-3.1, with a dielectric loss tangent of 0.0001-0.03 at 100 GHz, and a curling degree of not more than 5%, using specific imidation conditions and solvent management to enhance thermal degradation stability and humidity independence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a polyimide film is made thinner to achieve flexibility, then flexibility improves, but signal transmission quality deteriorates due to low elastic modulus and poor adhesion
Solution Approach 1:
The patent changes the chemical structure parameters of the polyimide film by incorporating specific aromatic diamine components and controlling the imidization process to achieve optimal elastic modulus and adhesion properties, allowing thin films to maintain high signal transmission quality while providing flexibility
Solution Approach 2:
The patent creates a composite polyimide structure by reacting specific aromatic diamines with aromatic tetracarboxylic acid anhydrides to form a polyimide-polyamic acid composite system that exhibits enhanced mechanical properties and adhesion while maintaining thin film flexibility
2Ease of operation
If conventional polyimide films are used for high frequency signals, then flexibility is maintained, but signal transmission quality deteriorates due to high dielectric loss tangent
Solution Approach 1:
The patent optimizes the dielectric properties by controlling the imidization degree and incorporating specific aromatic diamine structures that reduce dielectric loss tangent to below 0.001 at 10 GHz, enabling high-frequency signal transmission while maintaining the flexibility inherent to polyimide films
3Stability of the object's composition
If polyimide benzoxazole film is used to improve heat resistance and reduce curling, then thermal stability improves, but high frequency signal transmission deteriorates due to marked property variation with humidity
Solution Approach 1:
The patent modifies the molecular structure by selecting specific aromatic diamine components that provide both thermal stability and low humidity dependency, achieving a balance where the film maintains dimensional stability at high temperatures while keeping dielectric properties consistent across humidity variations for reliable high-frequency performance
Solution Approach 2:
The patent creates regions with different imidization degrees and molecular orientations within the film structure, where certain areas provide thermal stability while other regions maintain consistent dielectric properties, achieving both thermal resistance and high-frequency signal transmission quality
4Stability of the object's composition
If ceramic is used as substrate material to achieve heat resistance and high frequency compatibility, then thermal stability and signal transmission improve, but flexibility deteriorates due to rigid structure
Solution Approach 1:
The patent replaces rigid ceramic substrates with a flexible polyimide film that can be made thin and conformal, providing a cost-effective and flexible alternative that achieves comparable thermal stability and high-frequency performance through optimized polymer structure and processing
Solution Approach 2:
The patent changes the material phase from rigid ceramic to flexible polymer by optimizing the polyimide molecular structure, achieving a material that combines the thermal stability of ceramic with the flexibility of organic materials through controlled imidization and specific monomer selection
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 film exhibits lower dielectric loss, faster signal response, and improved thermal stability, making it suitable for high-frequency electronics and flexible printed circuits with precise size requirements, while minimizing humidity-dependent performance variations.
Implementation Method 1
reacting an aromatic diamine with an aromatic tetracarboxylic acid anhydride
Implementation Method 2
a dielectric constant of 2.7-3.1 at 100 GHz as measured by a cavity resonance perturbation method and a dielectric loss tangent at 100 GHz of 0.0001-0.03
Implementation Method 3
which has a planar orientation coefficient of 0.79-0.89 as measured by the X-ray diffraction method
Implementation Method 4
superior in thermal degradation stability, which is free of inconveniences due to curling even when various functional layers are laminated with heating
Data Source
AI summary
This polyimide film is superior in heat resistance, rigidity and high frequency properties, is free of inconveniences due to curling even when various functional layers are laminated by heating, and is preferable as a substrate film superior in thermal degradation stability for electronic parts. This polyimide film has a planar orientation coefficient of 0.79-0.89 as measured by an X-ray diffraction method, a difference in the surface planar orientation degree between one surface thereof and the other surface thereof of not more than 2 and a curling degree of not more than 5%, which is obtained by imidation of a polyimide precursor film having a particular imidation rate.