Low-Dielectric Polyimide Film for High-Frequency Insulation Stability
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Solution Overview
Problem
Existing polyimide films fail to maintain sufficient insulation at high frequencies due to high dielectric constants and dielectric dissipation factors, and are prone to moisture absorption, which affects their performance in thin-film circuit boards.
Innovation Solution
A polyimide film is manufactured using specific compositions and ratios of 3,3′,4,4′-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, m-tolidine, 4,4′-oxydianiline, and p-phenylenediamine, with a dehydrating agent and imidizing catalyst, and thermoset at 450-520°C for 3-6 minutes, resulting in low dielectric, low hygroscopic, and low optical transmittance properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If general polyimide is used to provide heat resistance and insulation, then heat resistance and basic insulation are improved, but dielectric constant increases at high frequencies
Solution Approach 1:
The patent modifies the chemical composition parameters of polyimide by incorporating specific ratios of aromatic polyamide components (e.g., 3,3'-biphenyl tetracarboxylic dianhydride, pyromellitic dianhydride) and cyclic carbonate components to achieve low dielectric constant (Dk ≤ 2.8) while maintaining heat resistance (HDT ≥ 250°C). This parameter optimization resolves the contradiction between heat resistance and high-frequency insulation performance.
Solution Approach 2:
The patent creates a composite polyimide system combining aromatic polyamide segments with cyclic carbonate segments in specific ratios (e.g., 70:30 to 90:10 by weight). This composite structure leverages the heat resistance of aromatic polyamide and the low dielectric properties of cyclic carbonate to simultaneously achieve both heat resistance and high-frequency insulation stability.
2Reliability
If polyimide with low dielectric constant is used for high-frequency insulation, then insulation at high frequency is improved, but moisture absorption increases
Solution Approach 1:
The patent optimizes the chemical structure parameters by using aromatic polyamide components with rigid backbones and limited polarity groups, combined with cyclic carbonate components that have low hygroscopicity. This structural parameter change reduces the material's affinity for moisture while maintaining low dielectric constant, achieving Dk ≤ 2.8 and moisture absorption ≤ 0.3% simultaneously.
Solution Approach 2:
The patent develops a composite material system where aromatic polyamide provides structural stability and low moisture absorption, while cyclic carbonate contributes low dielectric constant. The synergistic combination in specific ratios achieves both low dielectric property (Dk ≤ 2.8) and low hygroscopicity (moisture absorption ≤ 0.3%), resolving the contradiction between high-frequency insulation and moisture resistance.
3Weight of moving object
If polyimide film is made thinner for flexible circuit boards, then flexibility and weight reduction are improved, but optical transmittance increases
Solution Approach 1:
The patent changes the optical parameters of polyimide by incorporating cyclic carbonate components that have appropriate optical absorption characteristics. This allows the film to maintain low optical transmittance (≤ 25%) even at reduced thicknesses, enabling weight reduction while preserving optical blocking performance for flexible circuit board applications.
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 film achieves a dielectric dissipation factor of 0.003 or less and moisture absorption rate of 0.3% or less, ensuring insulation stability and minimizing signal propagation delay even at high frequencies, suitable for flexible metal clad laminates and electronic parts.
Implementation Method 1
preparing a polyamic acid composition by adding 2-3 mole equivalents of a dehydrating agent to the polyamic acid solution
Implementation Method 2
an imidizing catalyst may be additionally added in an amount of 0.5-2 mole equivalents to the polyamic acid solution
Implementation Method 3
applying the polyamic acid to a support to form a film, followed by thermosetting the film in a heater
Data Source
AI summary
Disclosed herein is provided a method for manufacturing a polyimide film, the method comprising the steps of: preparing a polyamic acid solution; preparing a polyamic add composition by adding 2-3 mole equivalents of a dehydrating agent to the polyamic acid solution; and applying the polyamic acid to a support to form a film, followed by thermosetting the film in a heater.