Flexible Display Device Composite Substrate Impact Resistance
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Solution Overview
Problem
Conventional flexible display devices are vulnerable to external physical impact due to their substrate materials, and the laser lift-off process used in manufacturing can lead to substrate peeling issues, limiting their application and reliability.
Innovation Solution
A flexible display device structure incorporating a support substrate made of glass and a buffer substrate made of a flexible plastic material, with specific thicknesses and materials chosen to enhance rigidity and prevent crack propagation, along with a manufacturing method that avoids the laser lift-off process to improve durability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible substrate made of plastic material is used to allow flexibility, then the device can be bent and rolled, but the substrate becomes vulnerable to external physical impact
Solution Approach 1:
The patent employs a composite substrate structure consisting of a first substrate (flexible material like plastic) and a second substrate (rigid material like glass) bonded together. This composite construction combines the flexibility of the first substrate with the impact resistance of the second substrate, resolving the contradiction between flexibility and durability against external physical impact.
2Ease of manufacture
If a laser lift-off process is performed on a carrier substrate for the flexible substrate, then the flexible substrate can be obtained, but the substrate may peel off together with the carrier substrate when uniformity of laser irradiation is lowered
Solution Approach 1:
The patent introduces a buffer layer as an intermediary between the first substrate and the carrier substrate during the laser lift-off process. This buffer layer acts as a mediator that prevents direct peeling between the first substrate and carrier substrate when laser irradiation uniformity is compromised, thereby maintaining substrate integrity while still enabling the lift-off process.
Solution Approach 2:
The buffer layer is positioned in advance between the first substrate and carrier substrate to provide protective cushioning during the laser lift-off process. This pre-positioned protective layer prevents damage and peeling issues before they occur, ensuring reliable substrate separation even when laser irradiation is non-uniform.
3Reliability
If the substrate is made flat to prevent damage of built-in components and wiring, then component protection is improved, but the application scope of the display device is limited
Solution Approach 1:
The patent employs a dynamic substrate system where the second substrate (rigid layer) can be selectively removed or detached after the display device is fabricated. During manufacturing, the substrate provides flat protection for components, but after fabrication, the device can be bent or rolled by removing the rigid constraint, thus enabling both component protection during manufacturing and flexible applications in use.
Data Source
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AI summary
The present disclosure provides a flexible display device comprising: a support substrate having a first thickness and made of a first material; a buffer substrate disposed on the support substrate, wherein the buffer substrate has a second thickness smaller than the first thickness and is made of a second material more flexible than the first material; a thin-film transistor array disposed on the buffer substrate, wherein the buffer substrate is disposed between the thin-film transistor array and the support substrate; and a sealing substrate fixedly disposed above the thin-film transistor array, wherein the thin-film transistor array is disposed between the buffer substrate and the sealing substrate.