Polyimide Film Adhesion via Diamine Composition
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Solution Overview
Problem
Polyimides based on 3,3′,4,4′-biphenyltetracarboxylic dianhydride exhibit low adhesion and moisture permeation rates, leading to issues like foaming and peeling during high-temperature treatments, and existing solutions compromise electrical properties or require complex and costly processes.
Innovation Solution
A novel polyimide film with improved adhesion and moisture permeation rates is achieved by using 3,3′,4,4′-biphenyltetracarboxylic dianhydride as the tetracarboxylic dianhydride component and an aromatic diamine with a specific structure, specifically between 0.5 and 30 mole percent, which enhances surface adhesion and moisture permeation without surface treatment, maintaining high elastic modulus and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If 3,3′,4,4′-biphenyltetracarboxylic dianhydride-based polyimide is used to achieve heat resistance and dimensional stability, then thermal properties and electrical properties are improved, but adhesion strength deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the polyimide by incorporating specific diamines (aromatic diamines with bulky groups, aliphatic diamines, or cyclic carbamate compounds) into the polymer structure. This compositional parameter change enables the polyimide to simultaneously achieve high heat resistance and improved adhesion strength without compromising either property
Solution Approach 2:
The patent creates a composite polyimide structure by combining multiple diamine components with 3,3′,4,4′-biphenyltetracarboxylic dianhydride. The synergistic effect of different diamine types (aromatic, aliphatic, cyclic carbamate) within the composite polymer structure enables simultaneous achievement of heat resistance and adhesion strength
2Stability of the object's composition
If polyimide film with low moisture absorption is used to achieve dimensional stability, then stability against environmental changes is improved, but moisture permeation rate deteriorates, causing foaming and peeling during high-temperature soldering
Solution Approach 1:
The patent modifies the molecular structure parameters of the polyimide by incorporating diamines with specific molecular characteristics (bulky groups, aliphatic chains, cyclic carbamate structures). These parameter changes create free volume and hydrophilic pathways in the polymer structure that enhance moisture permeation while preserving dimensional stability through the rigid 3,3′,4,4′-biphenyltetracarboxylic dianhydride backbone
3Strength
If adhesion of polyimide film is improved by adding tin, bismuth or antimony compounds, then adhesion strength is improved, but electrical insulation properties deteriorate
Solution Approach 1:
The patent replaces expensive and problematic metal compounds (tin, bismuth, antimony) with organic diamine molecules that provide adhesion functionality without compromising electrical insulation. The organic-based solution achieves adhesion improvement through molecular-level interaction rather than metal compound addition, avoiding electrical property degradation
Solution Approach 2:
The patent changes the chemical composition parameters by incorporating specific diamine structures into the polyimide backbone. This compositional modification provides adhesion enhancement through the diamine functional groups while maintaining the electrical insulation properties inherent to the polyimide structure, avoiding the need to add metal compounds
4Strength
If adhesion is improved by plasma discharge treatment, then adhesion strength is improved, but productivity deteriorates due to complex post-treatment steps
Solution Approach 1:
The patent incorporates adhesion-enhancing functional groups directly into the polyimide molecular structure during the polymerization process. This preliminary action embeds the adhesion functionality within the material itself, eliminating the need for subsequent plasma discharge treatment or other post-processing steps, thereby maintaining high productivity
Solution Approach 2:
The patent creates a self-adhesive polyimide material where the diamine-containing polymer structure inherently provides adhesion functionality. The material serves its own adhesion needs through its molecular structure, eliminating dependence on external surface treatment processes and enabling direct use in applications requiring adhesion
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 polyimide film achieves improved surface adhesion and moisture permeation with high elastic modulus and heat resistance, preventing foaming and peeling during high-temperature treatments, while maintaining excellent electrical properties and industrial applicability.
Implementation Method 1
the trace moisture remaining on the base cannot permeate the cover lay film
Data Source
AI summary
A polyimide wherein a tetracarboxylic dianhydride including 3,3′,4,4′-phenyltetracarboxylic dianhydride as the essential component is the starting tetracarboxylic dianhydride component, and an amine comprising between 0.5 and 30 mole percent of a diamine represented by the following general formula is the starting diamine component.(wherein A is a direct bond or a crosslinking group, and R1-R4 each represent a substituent). It is possible to obtain a polyimide, a polyimide film and a laminated body with an improved adhesion property and an improved moisture permeation rate, even without surface treatment, comprising, as the essential tetracarboxylic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride which has conventionally only yielded polyimides with low adhesive strength.