Touch Substrate Corner Lead Layout for Bend Crack Resistance
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Solution Overview
Problem
The challenge of cracking in touch signal wires at the corners of flexible touch display screens due to large-angle cover plate attachment, which reduces yield and increases production costs.
Innovation Solution
A touch substrate design where the corner lead of the touch lead is located entirely in the bending region, with the first lead portion extending from the bending region to the flat region, avoiding overlap with the bending boundary, and incorporating a stacked lead layer structure with via holes to relieve stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the corner lead is located in the flat region, then the touch lead structure is simpler, but the bending boundary overlaps with the corner lead causing cracks and reducing reliability
Solution Approach 1:
The touch lead is divided into two segments: a corner lead located entirely in the bending region and a first lead portion extending into the flat region. This segmentation allows the corner lead to be positioned away from the bending boundary, avoiding overlap and crack formation, while the first lead portion maintains electrical connection. The segmentation resolves the contradiction by separating the functions of stress resistance (corner lead) and electrical conduction (first lead portion).
Solution Approach 2:
The corner lead is designed to extend in a direction perpendicular to the bending boundary, utilizing the vertical dimension to position the lead away from the bending boundary in the horizontal plane. This dimensional change allows the corner lead to be located in the bending region without overlapping the bending boundary, thereby avoiding cracks while maintaining structural integrity.
2Reliability
If the corner lead is located in the bending region away from the bending boundary, then crack resistance is improved, but the lead portion extending to flat region may overlap the bending boundary causing stress concentration
Solution Approach 1:
The first lead portion is designed with different local characteristics: it extends from the bending region into the flat region but is positioned to avoid overlapping the bending boundary. This local quality design ensures that the lead portion experiences minimal bending stress while maintaining electrical connection. The corner lead and first lead portion are positioned to optimize both crack resistance and stress distribution.
3Adaptability or versatility
If the touch lead structure is optimized for flexibility, then bendability is improved, but manufacturing precision requirements increase due to precise positioning
Solution Approach 1:
The corner lead is pre-positioned entirely within the bending region during the design stage, with its location determined by the bending region boundaries rather than requiring high-precision alignment. This preliminary positioning action simplifies manufacturing by using the bending region boundaries as natural reference markers, reducing the need for complex precision alignment during assembly.
Data Source
AI summary
A touch substrate includes multiple touch electrodes and multiple touch leads, and has a touch region and a non-touch region. The touch electrodes are located in the touch region, and the touch leads are located in the non-touch region and provide signals for the touch electrodes. The touch substrate is divided into a flat region and a bending region(s) by a bending boundary. The touch substrate includes: a first side, a second side and a corner between the first side and the second side. The bending boundary substantially extends in the extension direction of the first edge and intersects with the second edge. A touch lead includes: a corner lead, an end of the corner lead is connected with a first lead portion, and the corner lead is completely located in the bending region and does not overlap with the bending boundary.