Winding Conductive Trace Design for Flexible Display Crack Resistance
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Solution Overview
Problem
Conventional conductive traces in flexible electronic devices are prone to cracking and delamination due to repeated bending, leading to reduced performance and reliability.
Innovation Solution
A winding conductive trace design with alternating crests and troughs, featuring wider metal trace lines with caps in low-stress regions to prevent crack propagation, and splitting into multiple sub-traces that converge back into a single trace to maintain electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conductive traces are used in flexible electronic devices, then the device can be manufactured with standard designs, but the traces are prone to cracking and delamination during repeated bending
Solution Approach 1:
The conductive trace is divided into multiple segments including winding sections, straight sections, and crests/troughs. This segmentation allows each section to handle stress differently, with winding sections and crests absorbing bending stresses while straight sections maintain electrical connectivity, preventing crack propagation through the entire trace.
Solution Approach 2:
The trace incorporates winding sections with curved paths and crests/troughs instead of straight lines. These curved geometries distribute mechanical stress more evenly during bending, preventing stress concentration at sharp corners or straight transitions, thereby reducing crack initiation and propagation.
2Reliability
If the metal trace line width is increased to prevent cracking, then crack resistance improves, but the area occupied by the trace increases
Solution Approach 1:
The trace width is varied locally according to functional requirements. Caps at crests and troughs have increased width to prevent crack propagation at high-stress points, while intermediate sections maintain narrower widths to minimize area consumption. This local quality variation ensures reliability at critical points without unnecessarily increasing overall trace area.
Solution Approach 2:
Caps are added at crests and troughs of the winding trace before cracking can occur. These caps act as preventive measures that widen the trace at potential crack initiation points, providing a buffer against stress concentration and crack propagation, thereby maintaining electrical connectivity even under repeated bending.
3Adaptability or versatility
If the trace is designed to be flexible to accommodate bending, then adaptability improves, but the trace becomes more susceptible to mechanical damage
Solution Approach 1:
The trace is segmented into flexible winding sections with crests/troughs that accommodate bending movements, and stronger straight sections that maintain structural integrity. This segmentation allows the trace to be adaptable to flexible substrate bending while maintaining mechanical strength in critical connection areas.
Solution Approach 2:
The design merges flexible winding sections with straight sections and adds caps at crests/troughs to create a composite structure. This combination leverages the flexibility of winding paths while incorporating straight sections and caps that provide enhanced mechanical strength and crack resistance at critical points.
Data Source
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Figure 2A
AI summary
A conductive trace design is described that minimizes the possibility of crack initiation and propagation in conductive traces during bending. The conductive trace design has a winding trace pattern that is more resistant to the formation of cracks at high stress points in the conductive traces. The conductive trace design includes a cap that helps ensure electrical connection of the conductive trace even though one or more cracks may begin to form in the conductive portion of the conductive trace.