Multi-Layer Touch Electrode Via Design for Flexible OLED Reliability
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Solution Overview
Problem
The existing OLED on-cell touch display technology faces challenges in achieving uniform light emission and high bending reliability due to the limitations of low-temperature dry etching processes, which result in structural weaknesses and increased risks of open circuits in flexible screens, particularly with the use of single-layer bridge connecting via designs.
Innovation Solution
A touch display device is designed with touch driving and sensing electrodes on different layers, utilizing metal mesh structures arranged according to specific patterns to prevent inconsistencies in optical effects and reduce risks associated with low-temperature dry etching, while also improving bending reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low-temperature dry etching processes are used to form vias for connecting touch electrodes, then touch electrode conduction is achieved, but structural strength is weakened and open circuit risks increase
Solution Approach 1:
The patent divides the touch electrode connections into two separate layers: the first touch electrode layer connects to bridge electrodes through vias in the insulating layer, while the second touch electrode layer connects to the same bridge electrodes through additional vias. This segmentation allows each layer to have optimized connection paths, reducing the need for excessive via etching in a single layer and thereby maintaining structural strength while ensuring conduction reliability.
Solution Approach 2:
The patent transitions from a single-layer touch electrode structure to a multi-layer structure with first and second touch electrode layers separated by an insulating layer. This dimensional change distributes the conduction paths across multiple layers, reducing the density of vias required in any single layer and preserving the structural integrity of the flexible display while maintaining electrical connectivity.
2Measurement precision
If more touch electrodes are added to improve touch accuracy, then touch accuracy is improved, but the number of metal bridge contacts and via positions increases, creating process challenges
Solution Approach 1:
The patent segments the touch electrode system into two distinct layers, allowing high-density touch electrodes to be arranged in each layer without proportionally increasing the number of vias. The bridge electrodes serve as shared connection points for both layers, reducing the total via count while maintaining high touch accuracy through the multi-layer electrode arrangement.
Solution Approach 2:
The bridge electrodes positioned in the insulating layer serve multiple functions: they connect to the first touch electrode layer through vias, connect to the second touch electrode layer through additional vias, and provide electrical continuity across both layers. This multi-functionality reduces the total number of separate connection structures needed, simplifying the manufacturing process while supporting high-density touch electrodes for improved accuracy.
3Reliability
If bridge electrodes and vias are used to connect touch electrodes in a single layer, then conduction is achieved, but bending reliability is reduced due to structural weaknesses
Solution Approach 1:
The patent distributes the conduction function across multiple layers by placing bridge electrodes in the insulating layer and connecting them to both the first and second touch electrode layers. This multi-layer architecture reduces the mechanical stress concentration that would occur in a single-layer structure during bending, improving the overall bending reliability while maintaining conduction effectiveness.
Solution Approach 2:
The patent creates different structural characteristics in different regions: the bridge electrodes in the insulating layer provide localized connection points that are optimized for both electrical conduction and mechanical flexibility. The via structures are strategically positioned and sized to provide adequate electrical connection while minimizing mechanical disruption to the flexible display structure during bending operations.
Data Source
AI summary
A touch display device is provided by the present application, including a display module and a touch module stacked, the touch module includes a first touch electrode layer, a second touch electrode layer, and an insulating layer; and each of first leads of the first touch electrode layer extends from one of first touch electrodes to a bonding area and extends to the second touch electrode layer through a via provided in the insulating layer to electrically connect one of pads, and each of second leads of the second touch electrode layer extends from one of second touch electrodes to the bonding area to electrically connect one of the pads.