Routing Line Adhesion in Flexible OLED Bending Areas
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Solution Overview
Problem
Flexible organic light emitting display devices face issues with cracking and disconnection in the routing line due to low adhesion between the substrate and the routing line, especially when bending, which can lead to film gaps and bezel size problems.
Innovation Solution
Incorporating a lower layer made of inorganic insulating materials like SiO2 or SiNx between the substrate and the routing line to enhance adhesion and minimize stress, along with a second planarization layer to prevent cracking and absorb external impacts, and optionally using a micro-coating layer to adjust the neutral plane during bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the buffer layer and the insulating layer are removed from the bending area to enable easy bending, then the flexibility and ease of bending is improved, but the adhesion between the routing line and the substrate deteriorates, causing film gaps
Solution Approach 1:
The patent divides the insulating layer into two distinct segments: a first insulating layer in the display area and a second insulating layer in the bending area. This segmentation allows each layer to be optimized for its specific function - the first layer provides adhesion where needed, while the second layer enables flexibility where bending occurs.
Solution Approach 2:
The patent applies different properties to different areas of the device. The first insulating layer has high adhesion properties for the display area, while the second insulating layer has low adhesion properties for the bending area. This local differentiation resolves the contradiction by providing adhesion only where necessary while maintaining flexibility where bending is required.
2Shape
If bending is increased to reduce bezel size, then the device compactness and bezel size is improved, but the buffer layer and insulating layer are broken, causing cracks in the routing line
Solution Approach 1:
The insulating layer is segmented into first and second layers, allowing the second layer in the bending area to be designed with crack-resistant properties while the first layer maintains structural integrity in the display area.
Solution Approach 2:
The patent introduces a buffer layer and a second insulating layer beforehand in the bending area to cushion and absorb the stress generated during bending. These layers act as protective elements that prevent cracks from forming in the routing line when the device is folded to reduce bezel size.
3Adaptability or versatility
If the buffer layer and insulating layer are removed from the bending area, then the flexibility is improved, but film gaps are generated due to low adhesion
Solution Approach 1:
The insulating layer is divided into first and second layers with different adhesion characteristics, allowing the device to achieve flexibility through the second layer while maintaining manufacturing precision and preventing film gaps through the first layer's high adhesion properties.
Solution Approach 2:
Different adhesion qualities are applied locally - the first insulating layer provides high adhesion to prevent film gaps in the display area, while the second insulating layer provides low adhesion to enable flexibility in the bending area, thus resolving the contradiction between flexibility and film gap prevention.
Data Source
AI summary
An organic light emitting display device is disclosed, which enhances an adhesion between a substrate and a routing line and minimizes a crack of the routing line. The organic light emitting display device comprises a substrate having a display area and a bending area; a routing line arranged on the bending area of the substrate; and a lower layer formed between the substrate and the routing line.