Polyamideimide Resin for Flexible Metal-Clad Laminates
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Solution Overview
Problem
Current flexible metal-clad laminates and printed circuit boards face challenges in achieving excellent heat resistance, flexibility, low thermal expansion, and colorless transparency, particularly for applications requiring transparent film substrates, as existing materials like all-aromatic polyimide films are colored due to charge-transfer complexes and have limitations in elongation and solubility.
Innovation Solution
A polyamideimide resin with an alicyclic structure, specifically using cyclohexane tricarboxylic acid anhydride as a main monomer, is developed, which offers inherent viscosity between 0.8 and 2.5 dl/g, ensuring high heat resistance, flexibility, and colorless transparency, along with a thermal expansion coefficient not exceeding 40 ppm/K, and light transmittance of at least 80% at 500 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If all-aromatic polyimide is used for flexible metal-clad laminate, then heat resistance is improved, but colorless transparency is deteriorated due to yellowish brown color from charge-transfer complex formation
Solution Approach 1:
The patent changes the chemical structure parameters of the polyimide by introducing alicyclic groups (cyclohexane rings) into the main chain, replacing traditional aromatic structures. This structural parameter change eliminates the charge-transfer complex formation that causes yellowing, achieving colorless transparency while maintaining heat resistance through the inherent thermal stability of the alicyclic polyimide structure.
Solution Approach 2:
The patent creates a composite molecular structure combining alicyclic groups (for transparency and flexibility) with aromatic groups (for heat resistance) in the polyimide main chain. This composite approach at the molecular level allows simultaneous achievement of colorless transparency and high heat resistance by integrating the beneficial properties of both structural types.
2Illumination intensity
If alicyclic diamine is used to achieve colorless transparency and high heat resistance, then transparency is improved, but flexibility is deteriorated due to high rigidity and linearity of the polyimide main chain
Solution Approach 1:
The patent modifies the structural parameters of the alicyclic groups by introducing methyl substituents at the 2-position of the cyclohexane ring. This parameter change in the molecular structure creates steric effects and disrupts chain linearity, reducing the rigidity of the polyimide main chain while preserving the colorless transparency property, thereby achieving both transparency and flexibility.
3Ease of operation
If alicyclic polyimide with high flexibility is used, then flexibility is improved, but heat resistance is deteriorated as glass transition temperature is lower than 270°C
Solution Approach 1:
The patent creates a composite molecular structure integrating alicyclic groups (providing flexibility) with aromatic groups (providing heat resistance) in the polyimide main chain. This molecular-level composite allows the material to simultaneously exhibit the flexibility of alicyclic structures and the high-temperature stability of aromatic structures, achieving both flexibility and heat resistance.
4Illumination intensity
If alicyclic polyimide is used for colorless transparency, then transparency is improved, but productivity is deteriorated due to poor solubility requiring high-temperature heating treatment
Solution Approach 1:
The patent changes the solubility parameters of the polyimide by introducing methyl substituents and adjusting the alicyclic-aromatic structure ratio. This structural parameter modification improves the solubility of the polyimide in conventional solvents, enabling solution processing at lower temperatures and eliminating the need for high-temperature heating treatment, thereby significantly improving productivity while maintaining colorless transparency.
Data Source
AI summary
This disclosure relates to a polyamideimide resin containing a structure represented by formula (1):