Foldable Display Wiring Layout to Reduce Bending-Area Cracking
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Solution Overview
Problem
Organic light-emitting display apparatuses experience cracking in the bending area due to wiring stress, which compromises the durability and reliability of the display.
Innovation Solution
A display apparatus design that includes a substrate with a bending area, an inorganic insulating layer, a pixel circuit, a display element, and a connection wire with specific layer configurations to minimize cracking, featuring a buried organic layer and a connection wire with metal patterns connected via contact holes, along with a planarization insulating layer and optical functional layer to enhance structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wiring is arranged in the bending area to provide electrical connection, then electrical connectivity is ensured, but stress concentration occurs leading to cracking
Solution Approach 1:
The patent extracts the wiring from the bending area by routing it through an opening in the inorganic insulating layer. The connection wire is positioned to extend through the bending area without being constrained by the rigid inorganic layer, thereby maintaining electrical connectivity while avoiding stress-induced cracking.
Solution Approach 2:
The inorganic insulating layer with an opening acts as an intermediary structure. It provides a pathway for the connection wire through the bending area, allowing the wire to maintain electrical connection while avoiding direct contact with the rigid inorganic material that would cause cracking under bending stress.
2Reliability
If inorganic insulating layer is used to provide insulation, then insulation performance is improved, but cracking occurs in the bending area due to rigidity
Solution Approach 1:
The inorganic insulating layer is segmented by creating an opening that passes through it. This segmentation allows the layer to maintain its insulation performance in non-bending areas while providing a flexible pathway in the bending area, preventing crack propagation through the rigid material.
Solution Approach 2:
The inorganic insulating layer has different structural properties in different locations: it remains intact and rigid in areas requiring insulation, but contains a localized opening in the bending area where flexibility is needed. This local modification maintains insulation performance while preventing cracking.
3Reliability
If connection wire is routed through bending area, then electrical connection is maintained, but stress concentration leads to wiring failure
Solution Approach 1:
The connection wire is extracted from the constrained environment within the inorganic insulating layer and routed through an opening. This allows the wire to pass through the bending area with minimal stress concentration, maintaining electrical connection while reducing the harmful effects of bending stress.
Data Source
AI summary
A display apparatus in which wiring in a bending area cracks less includes a substrate including a display area, a peripheral area, and a bending area which is at least a portion of the peripheral area that is bendable, an inorganic insulating layer arranged on the substrate and overlapping the display area and the peripheral area and defining an opening, a pixel circuit in the display area, a planarization insulating layer on the pixel circuit, a pad portion on an end of the peripheral area, a first organic layer arranged in the bending area and including the same material as a material included in the planarization insulating layer, and a connection wire extending on the pad portion. The connection wire includes first metal patterns under the first organic layer, and second metal patterns on the first organic layer and electrically connected to the first metal patterns.