Flexible Display Substrate Layout to Prevent Bending-Area Cracks
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Solution Overview
Problem
The challenge in manufacturing organic light-emitting display devices is ensuring stable adhesion of the carrier substrate to the flexible base substrate, which can lead to reliability issues due to cracking of inorganic layers in the bending area and residual photoresist in the peripheral area, affecting the display device's performance.
Innovation Solution
The solution involves forming a base substrate with an organic film and an inorganic barrier film extending outwardly from the edge, using a mask to expose specific areas for etching, and ensuring the inorganic barrier film remains in contact with the carrier substrate to prevent cracking and residual photoresist, with a width of at least 3 mm to enhance adhesion and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the carrier substrate is stably adhered to the flexible base substrate, then adhesion strength is improved, but cracking of inorganic layers in the bending area occurs
Solution Approach 1:
The patent segments the base substrate structure by extending the inorganic barrier film outwardly from the edge of the organic film, creating distinct functional zones: a bending area with removed inorganic layers and a peripheral area with extended inorganic barrier film for adhesion. This segmentation allows the bending area to flex without cracking while the peripheral area provides stable adhesion to the carrier substrate.
Solution Approach 2:
The patent applies local quality by having different inorganic layer configurations in different areas: the bending area has removed inorganic layers to prevent cracking during flexing, while the peripheral area has an extended inorganic barrier film (width ≥3 mm) that contacts the carrier substrate to provide strong adhesion. Each area is optimized for its specific function.
2Area of stationary object
If the inorganic barrier film extends outwardly from the edge of the organic film with width ≥3 mm, then adhesion area is improved, but manufacturing complexity increases
Solution Approach 1:
The patent uses preliminary action by designing the mask pattern before etching to automatically define the extended inorganic barrier film region. The mask includes a first mask pattern for the display area and a second mask pattern for the peripheral area, which pre-determines where the inorganic barrier film will extend outwardly from the organic film edge, simplifying the subsequent etching process.
Solution Approach 2:
The patent introduces a mask as an intermediary tool to control the etching process. The mask pattern acts as a mediator that defines the boundary of the extended inorganic barrier film, allowing precise control of the adhesion area without requiring complex direct patterning methods. The mask enables the creation of the ≥3 mm width extension in a controlled manner.
3Reliability
If photoresist is exposed at the edge area during manufacturing, then adhesion is improved, but residual photoresist defects occur
Solution Approach 1:
The patent extracts the photoresist exposure function to a specific peripheral area only. The mask pattern is designed with a second mask pattern that limits light exposure to the peripheral area where the inorganic barrier film extends, preventing photoresist exposure in the display area. This extraction of the exposure function to a dedicated peripheral zone prevents residual photoresist defects in the display area while maintaining adhesion benefits.
Data Source
AI summary
A display device includes a supporting substrate including a polymeric material, base substrate disposed on an upper surface of the supporting substrate, a pixel array disposed in a display area of the base substrate, a transfer wiring disposed in a bending area of the base substrate and electrically connected to the pixel array, and an organic filling portion disposed under the transfer wiring in the bending area. The base substrate includes an organic film including a polymeric material, and an inorganic barrier film overlapping the organic film and extending outwardly from an edge of the organic film. The organic filling portion contacts the organic film of the base substrate.