Foldable Display Panel Lead Layout for Bend Stress Relief
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Solution Overview
Problem
Existing OLED display panels face challenges in maintaining the integrity of connecting leads during bending, leading to increased risk of breakage due to tensile stress, which affects yield and reliability.
Innovation Solution
The display panel design includes a substrate layer with a buffer layer having an accommodating structure that houses the connecting lead between two stacked substrates, allowing the lead to be closer to a neutral layer during bending, reducing tensile stress and improving yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the connecting lead is positioned in the bending region to enable flexible display, then the display panel achieves flexibility and bendability, but the connecting lead is subjected to tensile stress during bending which causes breakage and reduces yield
Solution Approach 1:
The connecting lead is repositioned from a planar arrangement to a three-dimensional stacked configuration between the first and second substrates. This vertical dimensionality change allows the connecting lead to be located in the bending region while being protected from tensile stress by positioning it within the substrate thickness, effectively resolving the contradiction between flexibility and integrity.
Solution Approach 2:
The connecting lead is nested within the space between the first substrate and the second substrate, utilizing the layered structure for protection. This nesting approach allows the connecting lead to be shielded from external mechanical stress while maintaining its electrical connection function, thereby improving reliability during bending operations.
2Reliability
If the connecting lead is positioned closer to the neutral layer to reduce tensile stress, then the risk of breakage is reduced, but the structural complexity increases due to the need for buffer layers and accommodating structures
Solution Approach 1:
The substrate structure is segmented into multiple functional layers including a first substrate, a buffer layer with accommodating structure, and a second substrate. This segmentation allows the connecting lead to be positioned optimally for stress reduction while distributing the structural complexity across separate, manageable layers that can be manufactured independently and then assembled.
Solution Approach 2:
The buffer layer acts as an intermediary structure between the first substrate and the second substrate, providing the accommodating structure that houses the connecting lead. This intermediary layer simplifies the overall design by providing a dedicated space for stress reduction without requiring complex modifications to the primary substrate structures.
3Reliability
If the optical adhesive layer extends through the fan-out and bending regions to manage stress, then signal line breakage is prevented, but the manufacturing process becomes more complex
Solution Approach 1:
The optical adhesive layer is applied in advance during the assembly process, extending through the fan-out and bending regions before the final product is delivered to the user. This preliminary action ensures that stress management and signal line protection are built into the structure during manufacturing, simplifying subsequent operations and ensuring reliability without complicating the end-use process.
Data Source
AI summary
A display panel has a display area and a peripheral area including: a first fan-out region, a bending region, and a second fan-out region. The display panel includes: a substrate layer, at least one connecting lead and at least one first-type signal line. The substrate layer includes a first substrate and a second substrate. The at least one connecting lead is between the first and second substrates and extends from a side of the bending region to another side of the bending region through the bending region. The at least one first-type signal line is located on a side of the second substrate away from the first substrate. A first-type signal line is in at least one of the first fan-out region or the display area. The first-type signal line is electrically connected to a connecting lead through a via hole in the second substrate.