Thick Polyimide Film Surface Quality via Parameter A Control
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Solution Overview
Problem
Thick polyimide films often suffer from surface defects due to bubbles formed during the imidization process, which impede adhesion and increase the risk of short circuits in microelectronic parts, especially in high-thickness applications where gas discharge paths are lengthened.
Innovation Solution
The polyimide film is manufactured by controlling the viscosity of the polyamic acid solution, number average molecular weight, and thickness within specific ranges to minimize bubble formation, using the parameter A (log((V·Mn)2·√{T})−21, where V is viscosity, Mn is molecular weight, and T is thickness, to ensure a smooth surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thickness of the polyimide film is increased to provide better insulation and protection for circuit boards, then the insulating performance and protection capability are improved, but the likelihood of bubble formation and surface protrusions increases due to longer gas discharge paths
Solution Approach 1:
The patent applies parameter changes by precisely controlling the viscosity of the polyamic acid solution (200,000-250,000 cP at 23°C), the number average molecular weight of polyamic acid (100,000-150,000 g/mole), and the film thickness (55-110 μm) to satisfy parameter A within 0.4-1.13. This systematic parameter optimization resolves the contradiction by enabling thick film production while maintaining surface quality free of bubbles and protrusions.
2Strength
If the viscosity of the polyamic acid solution is increased to reduce solvent content and improve film strength, then the mechanical properties are enhanced, but the gas discharge path becomes more restricted and bubble formation increases
Solution Approach 1:
The patent resolves this contradiction by optimizing the viscosity parameter to a specific range (200,000-250,000 cP at 23°C) and correlating it with the number average molecular weight (100,000-150,000 g/mole) and thickness (55-110 μm) to satisfy parameter A within 0.4-1.13. This balanced parameter set achieves both high film strength and effective gas discharge, preventing bubble formation.
3Strength
If the number average molecular weight of polyamic acid is increased to improve film mechanical properties, then the strength and durability are enhanced, but the viscosity increases and gas discharge becomes more difficult
Solution Approach 1:
The patent resolves this contradiction by establishing an optimal number average molecular weight range (100,000-150,000 g/mole) and correlating it with viscosity (200,000-250,000 cP at 23°C) and thickness (55-110 μm) to satisfy parameter A within 0.4-1.13. This coordinated parameter optimization achieves both enhanced mechanical properties and facilitated gas discharge.
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 controlled parameters result in a polyimide film with a smooth surface, superior adhesion, and enhanced mechanical properties, such as high modulus, elongation, and tensile strength, while preventing bubble-related defects even at high thicknesses.
Implementation Method 1
a polyimide film may be manufactured through 'Imidization' in which the amic acid group in polyamic acid is converted into an imide group through heat
Implementation Method 2
a large amount of gas is generated due to evaporation of the water and the solvent
Data Source
AI summary
The present invention provides a polyimide film in which a parameter A for the relationship of the viscosity (V) of a polyamic acid solution, the number average molecular weight (Mn) of polyamic acid, and the thickness (T) of a polyimide film falls within a range from 0.4 to 1.13.