Touchpad Flexible Trace Layout for Narrow Borders and Durability
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Solution Overview
Problem
Conventional large-size touchpads face issues with excessive border width due to wider trace convergence areas and susceptibility to wire breakage at the bending portion, affecting usability and yield rate.
Innovation Solution
A touchpad design featuring a substrate with sensing traces, a flexible connecting board with thinner extending traces, and a cover, utilizing different materials for the connecting board and sensing panel to minimize border width and prevent wire breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sensing panel uses a membrane material with printed sensing traces, then the manufacturing cost is reduced, but the border area width increases and the traces are prone to breakage
Solution Approach 1:
The patent divides the sensing panel structure into multiple layers: a flexible substrate layer, a sensing trace layer, and a protective cover layer. The sensing traces are embedded within the flexible substrate rather than printed on a separate membrane, segmenting the functions of structural support and electrical conduction. This segmentation allows the traces to be protected by the substrate structure, reducing breakage while maintaining manufacturing feasibility.
Solution Approach 2:
The patent employs composite material construction where the flexible substrate integrates multiple functional properties: mechanical flexibility, electrical conductivity pathways, and structural protection. The combination of flexible polymer materials with conductive trace layers creates a composite structure that simultaneously achieves durability against breakage and flexibility for large-size applications, while maintaining cost-effectiveness through integrated manufacturing processes.
2Reliability
If the sensing traces converge at the connecting portion, then the electrical connection to the controller is achieved, but a wider border area is required reducing the active touch area
Solution Approach 1:
The patent utilizes multi-layer vertical stacking to resolve the trace convergence problem. Instead of spreading traces horizontally across a wide border area, the sensing traces from different regions converge vertically through the flexible substrate to connection points. This dimensional transition from 2D horizontal spreading to 3D vertical convergence allows electrical connections to be achieved with minimal border width, maximizing the active touch area.
Solution Approach 2:
The patent implements nested routing where sensing traces are embedded within the flexible substrate structure, and multiple trace paths are nested within the same physical space. The traces are routed through layered configurations where inner traces are protected by outer structural layers, allowing dense trace convergence without requiring additional border width. This nesting approach enables efficient space utilization for electrical connections.
Data Source
AI summary
A touchpad has a substrate, a sensing panel and a cover stacked in a sequence. The sensing panel has multiple sensing traces formed thereon. At least one flexible connecting board is connected between the sensing panel and the substrate via its end. The connecting board has multiple extending traces formed thereon, which are thinner than the sensing traces, to form an electrical connection between the sensing traces and the controller on the substrate. The flexible connecting board is used to avoid the problem of trace breakage caused by direct bending of the end of the sensing panel, and the sensing traces are collected by extending traces with smaller line widths so as to reduce the width of the boundary area effectively.