Flexible Display Crack Propagation Control via Patterned Inorganic Film
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Solution Overview
Problem
During the mass production of flexible OLED displays, the cutting process of plastic film substrates can lead to deformation and errors due to physical impacts, causing cracks to spread from the cut line to the display area, which affects the quality and reliability of individualized flexible display devices.
Innovation Solution
The implementation of a patterned inorganic film layer and a dummy pattern layer in the outside-the-cell region of the flexible display device, where the inorganic film layer is partially removed and the dummy pattern layer is formed to absorb and buffer the energy of nascent cracks, preventing their propagation into the display area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the plastic film substrates are cut after separation from the carrier substrate, then individual flexible display devices can be produced, but deformation and cracks occur due to physical impacts during dicing
Solution Approach 1:
The patent applies preliminary action by forming the inorganic film layer continuously across the entire plastic film substrate before the dicing process. This pre-formed continuous layer provides structural support that prevents deformation during subsequent cutting operations. The continuous inorganic film is then selectively removed from non-display areas after dicing, but its presence during cutting is crucial for maintaining display area integrity.
Solution Approach 2:
The patent applies segmentation by selectively removing the inorganic film layer from non-display areas (such as the cell outer region) while maintaining it in the display area. This creates a segmented structure where the inorganic film provides protection where needed and allows clean separation where not needed, enabling individual device extraction without affecting display quality.
2Reliability
If the inorganic film layer is removed from the outside-the-cell region, then crack propagation is prevented, but the structural support in non-display areas is reduced
Solution Approach 1:
The patent applies local quality by creating spatial variation in the inorganic film layer configuration. The film is maintained with full thickness and continuity in the display area where mechanical strength and crack resistance are critical, while being selectively removed or thinning in the non-display cell outer region. This local differentiation optimizes both crack propagation resistance in functional areas and structural support where needed.
Solution Approach 2:
The patent converts the potential harm of crack propagation during dicing into a benefit by using the continuous inorganic film layer as a crack-arresting barrier. The film's continuity across the substrate during the dicing process prevents cracks from propagating into the display area, and its subsequent selective removal from non-display areas eliminates the barrier only where it is no longer needed for protection.
3Ease of manufacture
If a continuous inorganic film layer is formed across the entire substrate, then manufacturing simplicity is maintained, but crack propagation to display area cannot be prevented
Solution Approach 1:
The patent applies preliminary action by forming the continuous inorganic film layer across the entire substrate before the dicing process occurs. This timing is crucial because the continuous film provides crack propagation resistance during the high-stress dicing operation. After dicing is complete, the film is then selectively removed from non-display areas, achieving both the ease of initial continuous formation and the reliability of crack protection during manufacturing.
Solution Approach 2:
The patent applies segmentation by selectively removing portions of the initially continuous inorganic film layer from non-display areas after dicing. This creates a segmented configuration where the film remains continuous and protective in display areas while being removed in cell outer regions, achieving both manufacturing simplicity (single initial formation step) and crack propagation prevention.
Data Source
AI summary
A flexible display device includes: a display substrate which is divided into a first region corresponding to a within-cell region of an integrated devices sheet from which the flexible display device is cut and into a second region corresponding to an outside-the-cell region of the integrated devices sheet, where within the first region there is provided a display unit including a light emitting element layer; a patterned inorganic film layer formed to be substantially continuously present within the first region of the display substrate and to be not present or not substantially continuously present within the second region of the display substrate; and a thin film encapsulation layer formed on the inorganic film layer to encapsulate the substantially continuously present portion of the inorganic film layer that is within the first region and the display unit, wherein an outer boundary of the thin film encapsulation layer is located more inwardly and toward an outer boundary of the display unit than is an outer boundary of the substantially continuously present portion of the inorganic film layer.