Thin TFT Glass Support Substrate with Polyimide to Prevent Yellowing
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Solution Overview
Problem
Existing support substrates for flexible organic EL display devices face issues with yellowing of the organic resin layer during high-temperature processing, preventing the integration of camera modules on the rear surface of display devices like smartphones.
Innovation Solution
A support substrate comprising a TFT glass substrate with a thickness of 10 μm to 150 μm and a polyimide resin layer with a thickness of 150 nm or less, which provides high heat resistance and transparency, preventing yellowing during high-temperature processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a thin glass substrate is used to achieve flexibility and thinning, then the display device becomes flexible and thin, but the substrate turns yellow during high-temperature processing
Solution Approach 1:
A polyimide resin layer is introduced as an intermediary between the thin glass substrate and the TFT circuitry layer. This resin layer has high heat resistance and prevents yellowing during high-temperature processing, while the thin glass substrate maintains its flexibility. The resin layer acts as a protective mediator that withstands thermal stress without degrading in appearance.
Solution Approach 2:
The support substrate is constructed as a composite structure combining a thin glass substrate (10-150 μm) with a polyimide resin layer. This composite material approach allows the glass substrate to provide flexibility while the polyimide resin provides heat resistance and prevents yellowing, achieving both desired properties simultaneously.
2Illumination intensity
If the organic resin layer thickness is reduced to achieve transparency, then the display device becomes more transparent, but the substrate loses heat resistance
Solution Approach 1:
The polyimide resin layer serves as a thermal intermediary that protects the thin glass substrate from high-temperature damage. It has high heat resistance and prevents the substrate from turning yellow during TFT circuitry formation at elevated temperatures, while maintaining the overall transparency of the display device.
Solution Approach 2:
The invention changes the material parameters by selecting a polyimide resin with specific thermal properties (high heat resistance) and controlling its thickness (150 nm or less). This parameter optimization allows the resin layer to provide thermal protection while minimizing impact on light transmission.
3Strength
If a thick glass substrate is used to achieve strength, then the substrate becomes stronger, but the display device loses flexibility
Solution Approach 1:
The invention uses a thin glass substrate (10-150 μm) that functions as a flexible shell, providing sufficient mechanical strength while enabling flexibility. This thin film approach replaces traditional thick glass substrates, allowing the display device to be bent without breaking while maintaining structural integrity.
Solution Approach 2:
The composite structure of thin glass substrate combined with polyimide resin layer provides both strength and flexibility. The thin glass substrate contributes strength and dimensional stability, while the polyimide resin adds flexibility and heat resistance, creating a balanced composite material system.
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 substrate enables the production of transparent, thin, and flexible organic EL display devices with high transparency and flexibility, allowing for the integration of camera modules on the rear surface.
Implementation Method 1
a polyimide resin layer having a thickness of 150 nm or less and having high heat resistance installed in contact with the TFT glass substrate
Implementation Method 2
a TFT glass substrate having a thickness of 10 μm to 150 μm, and a polyimide resin layer having a thickness of 150 nm or less
Data Source
AI summary
The present disclosure is directed to providing a support substrate for a display device capable of obtaining high transparency while accomplishing thinning and flexibility of an organic EL display device.In view of the above, the present disclosure provides a support substrate for a display device including a TFT glass substrate having a thickness of 10 μm to 150 μm, and a polyimide resin layer having a thickness of 150 nm or less installed in contact with the TFT glass substrate.