Flexible Micro Display Panel Backup Traces for Bending Reliability
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Solution Overview
Problem
Flexible micro device display panels face signal transmission issues and yield reduction due to broken trace lines in bending areas, as bending stress can damage internal structures and cut off signal paths.
Innovation Solution
A flexible micro device display panel design featuring a backup conductive line in the bending area, electrically connected to the primary trace line through conductive vias, allowing for multiple signal transmission paths across different metal layers to ensure continuous signal transmission even if one metal layer is damaged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single trace line is used in the bending area, then the device structure is simple, but the trace line may be broken due to bending stress causing signal transmission failure
Solution Approach 1:
The conductive line is segmented into multiple independent trace lines (first trace line and second trace line) disposed at different metal layers. Each trace line can independently transmit signals, and if one trace line is broken due to bending stress, the other trace line can still maintain signal transmission, thereby improving reliability without requiring a completely redundant backup system
Solution Approach 2:
The patent transitions from a single-plane trace line configuration to a multi-layer three-dimensional configuration. The first trace line is disposed at a first metal layer while the second trace line is disposed at a second metal layer, utilizing the vertical dimension to create spatial separation. This dimensional change allows both trace lines to coexist without interfering with each other while providing redundancy against bending-induced failures
2Reliability
If multiple metal layers with backup conductive lines are added, then signal transmission reliability is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The backup conductive line is merged with the existing multi-metal-layer structure of the flexible display device. Rather than adding a completely separate backup layer, the patent utilizes the existing second metal layer to accommodate the second trace line, which serves both as part of the normal circuit structure and as a backup pathway. This merging approach reduces manufacturing complexity compared to adding entirely new structural layers
Solution Approach 2:
The second metal layer serves dual functions: it contains the second trace line for signal transmission and simultaneously acts as a backup conductive path when the first trace line is compromised. This multi-functionality eliminates the need for dedicated backup structures, simplifying the manufacturing process while maintaining reliability
3Adaptability or versatility
If trace lines are disposed in the bending area, then the display can be flexible and curved, but the trace lines are susceptible to breaking from bending stress
Solution Approach 1:
The patent applies different structural configurations to different regions of the conductive system. In the bending area, multiple trace lines at different metal layers are used to provide redundancy and distribute bending stress. In non-bending areas, the standard single trace line configuration is maintained. This local differentiation allows the display to maintain flexibility where needed while preserving trace line integrity through targeted reinforcement in stress-prone regions
Data Source
AI summary
The present invention discloses a flexible micro device display panel which comprises a substrate, a plurality of micro light emitting units, a first trace line, and a backup conductive line. The substrate comprises a display region having a bending area and a non-bending area. The plurality of micro light emitting units are disposed on the substrate within the display region. The first trace line is arranged from the non-bending area to the bending area. The backup conductive line is disposed at a second metal layer and coupled with the first trace line. The first metal layer and the second metal layer are disposed on the substrate, and the distance between the substrate and the first metal layer is different from the distance between the substrate and the second metal layer. The backup conductive line is not disposed within the non-bending area.