Multilayered Wiring Structure for Flexible Display Devices
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Solution Overview
Problem
Flexible display devices face issues with wiring disconnection when bent, leading to display defects due to the inability of existing technologies to maintain reliable electrical connections across the substrate's curvature.
Innovation Solution
A multilayered wiring structure is implemented, where a first conductive layer and a second conductive layer are electrically connected through specific connection portions, with these layers being separated to prevent direct contact and maintain conductivity even when the substrate is bent, using a combination of conductive thin films and insulating layers to manage bending stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer wiring structure is used, then the device structure is simple, but the wiring disconnects when bent causing display defects
Solution Approach 1:
The wiring is divided into multiple conductive layers (first conductive layer and second conductive layer) stacked vertically. This segmentation allows each layer to independently carry signals, so if one layer disconnects during bending, the other layer maintains electrical connectivity, thereby preventing display defects while maintaining reasonable structural complexity.
Solution Approach 2:
The patent transitions from a single-plane (2D) wiring layout to a multi-layer (3D) stacked wiring structure. By adding the vertical dimension with multiple conductive layers separated by insulating films, the wiring system gains redundancy and flexibility, allowing signals to be transmitted through alternative paths when bent, thus improving reliability without excessive complexity.
2Reliability
If multiple conductive layers are stacked, then wiring connection reliability improves, but device complexity increases
Solution Approach 1:
Multiple conductive layers are merged into a unified wiring system where the first and second conductive layers work together to transmit signals. The insulating films are merged to provide both electrical isolation and mechanical support. This merging creates a cohesive multi-layer structure that enhances reliability while managing complexity through integrated design.
Solution Approach 2:
The multi-layer wiring structure serves multiple functions simultaneously: electrical signal transmission, mechanical flexibility during bending, and structural support. The insulating films not only provide electrical isolation but also act as spacers and mechanical reinforcement. This multi-functionality justifies the increased structural complexity by delivering multiple benefits beyond simple connectivity.
3Reliability
If conductive layers are separated by insulating layers, then wiring disconnection is prevented, but manufacturing complexity increases
Solution Approach 1:
Insulating films are deposited between the conductive layers during the manufacturing process before final assembly. This preliminary action of placing insulating layers in advance ensures proper spacing and electrical isolation are built into the structure from the start, preventing wiring disconnection issues before they occur and simplifying subsequent manufacturing steps.
Solution Approach 2:
The insulating films act as intermediary layers between the first and second conductive layers. These intermediary films provide necessary electrical isolation while maintaining mechanical integrity during bending. By introducing this intermediary element, the patent achieves reliable wiring connection without requiring complex direct-contact bonding structures, thus improving manufacturability.
Data Source
AI summary
A display device includes a substrate having an edge portion, a display region located on the substrate and separated from the edge portion, a drive circuit region between the display region and the edge portion, a terminal region on the edge portion; and wirings in the display region, the drive circuit region, and an area between the drive circuit region and the terminal region, wherein at least one wiring of the wirings include a first conductive layer, a second conductive layer overlapping the first conductive layer in a plan view and separated from the first conductive layer, a first connection portion where the first conductive layer and the second conductive layer are electrically connected, a second connection portion where the first conductive layer and the second conductive layer are electrically connected, and the first connection portion is separated from the second connection portion.