Polyimide Film Uniform Imidization for Flexible Display Curl
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Solution Overview
Problem
Polyimide films used as window cover films in flexible display devices often suffer from curl or bending due to differences in heat history and imidization rates between the surface and interior, leading to uneven physical properties and mechanical instability.
Innovation Solution
A polyimide-based film with a thickness direction intensity difference of 0.6 or less, achieved through the use of a polyamide-imide resin containing fluorine-based aromatic diamines, cycloaliphatic dianhydrides, and aromatic diacid dichlorides, with a manufacturing process involving stretching and heat treatment to ensure uniform structure and properties across the film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high temperature heating is applied to imidize polyamic acid, then imidization rate is improved, but difference in heat history between surface and inside increases causing curl and bending
Solution Approach 1:
The patent applies parameter changes by controlling the imidization process to achieve uniform molecular structure throughout the film thickness. Specifically, the patent optimizes heating temperature profiles and imidization conditions to ensure that both surface and interior regions undergo identical thermal histories, eliminating the curl and bending defects caused by non-uniform imidization.
2Manufacturing precision
If high temperature heating is applied to imidize polyamic acid, then imidization is sufficient, but physical properties such as strength become non-uniform between surface and inside
Solution Approach 1:
The patent employs parameter changes to standardize the imidization process across the entire film thickness. By carefully controlling temperature-time profiles and imidization conditions, the patent ensures that polyamic acid converts to polyimide uniformly throughout the material, resulting in consistent physical properties including strength, regardless of position within the film.
3Ease of manufacture
If conventional polyimide film is used, then manufacturing is simple, but dimensional stability is poor causing curl and bending
Solution Approach 1:
The patent applies parameter changes to the imidization process to achieve uniform molecular structure throughout the film. By optimizing heating temperature profiles and imidization conditions to ensure identical thermal histories for surface and interior regions, the patent eliminates dimensional instability while maintaining manufacturing simplicity.
Solution Approach 2:
The patent replaces mechanical adjustments with chemical process control to achieve dimensional stability. Instead of mechanically compensating for curl and bending, the patent uses controlled chemical imidization to create a uniformly structured polyimide film that inherently resists deformation, substituting mechanical problem-solving with chemical process optimization.
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 excellent dimensional stability, reduced curl, improved mechanical properties, and enhanced optical properties, making it suitable for flexible display panels with improved durability and transparency.
Implementation Method 1
a polyamic acid as a precursor is usually prepared and subjected to imidization. In this case, heating of the polyamic acid at a high temperature is required in order to sufficiently imidize the polyamic acid
Implementation Method 2
a manufacturing process involving stretching and heat treatment to ensure uniform structure and properties across the film
Data Source
AI summary
The present invention relates to a polyimide-based film, a window cover film, and a display panel including the same. More specifically, the present invention relates to a polyimide-based film having a difference (ΔI) between the maximum and minimum values of intensity in a thickness direction of 0.6 or less, when an aromatic ring peak of 1610 to 1630 cm−1 was measured by Raman spectroscopy in which an excitation wavelength is 532 nm, a laser spot is 1 to 2 μm, and a thickness direction measurement interval is 1 μm.