Touch Panel Fabrication with Transparent Bridge Lines
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Solution Overview
Problem
Capacitive touch panels face issues with high resistance leading to low sensitivity and metal oxidation, which reduces reliability and lifespan, especially when metallic materials are exposed without an uppermost insulating layer, increasing manufacturing costs.
Innovation Solution
A method involving a substrate with a touch-sensing circuit layer, an insulating layer, and a transparent conductive layer is used, where the insulating layer covers the touch-sensing circuit layer, and the transparent conductive layer is formed on top, using materials like ITO, IZO, and AZO to prevent metal exposure and oxidation, while reducing manufacturing processes to three.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the uppermost insulating layer is omitted to simplify the fabrication process and reduce manufacturing costs, then the manufacturing complexity and cost are reduced, but the metallic bridge portions are directly exposed to external surroundings causing metal oxidation and significant reduction of reliability and lifespan
Solution Approach 1:
A transparent conductive layer is introduced as an intermediary between the metallic bridge portions and the external environment. This layer serves dual purposes: it protects the metallic materials from oxidation by acting as a barrier, and it maintains optical transparency to preserve touch sensitivity. The transparent conductive layer is formed through a separate sputtering process, creating a protective interface that resolves the contradiction between manufacturing simplicity and reliability.
2Reliability
If metallic materials are used for bridge portions to reduce resistance and improve touch sensitivity, then the resistance of sensing series is reduced and touch sensitivity is improved, but the metallic materials are exposed to external surroundings causing metal oxidation and significant reduction of reliability and lifespan
Solution Approach 1:
The transparent conductive layer acts as a protective intermediary that covers the metallic bridge portions. This layer prevents direct exposure of metallic materials to oxygen and moisture in the external environment, thereby preventing oxidation while maintaining the low-resistance electrical pathways needed for touch sensitivity. The protective function extends the lifespan without compromising performance.
3Reliability
If the transparent conductive layer completely covers the peripheral circuits in the peripheral region, then the peripheral circuits are protected from oxidation, but the contact pads cannot be properly connected to external circuits
Solution Approach 1:
The transparent conductive layer is applied with spatially varying properties: in the touch-sensing region, it completely covers the metallic bridge portions to provide full protection, while in the peripheral region, it selectively covers only the internal circuits that require protection, leaving contact pads exposed through dedicated contact windows. This local differentiation enables simultaneous protection of sensitive circuits and accessibility of connection points.
Solution Approach 2:
The peripheral region is segmented into different functional zones: areas with transparent conductive layer coverage for protected circuits, and areas with contact windows for external connections. This segmentation allows the same structure to fulfill multiple functions - protection where needed and connectivity where required - resolving the contradiction between circuit protection and external connection accessibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces manufacturing costs, enhances touch panel reliability by preventing metal oxidation, and improves sensitivity without increasing costs, making the touch panel suitable for mass production.
Implementation Method 1
The transparent conductive layer includes a plurality of second transparent bridge lines and a plurality of transparent contact pads. Each of the second transparent bridge lines is electrically connected to two adjacent second meshed metal sensing pads through two first contact windows.
Implementation Method 2
An insulating layer is formed on the substrate to cover the touch-sensing circuit layer... the insulating layer has a plurality of first contact windows and a plurality of second contact windows. The first contact windows expose a portion of the second meshed metal sensing pads.
Implementation Method 3
a transparent conductive layer is formed on the insulating layer located in the touch-sensing region... prevent metal oxidation and significantly reduction of reliability and the life span of the touch panel
Data Source
AI summary
A method of fabricating a touch panel is provided. A substrate having a touch-sensing region and a peripheral region is provided. A touch-sensing circuit layer including first sensing series, and second meshed metal sensing pads is formed on the touch-sensing region of the substrate. An insulating layer having first contact windows is formed on the substrate to cover the touch-sensing circuit layer. The first contact windows expose a portion of the second meshed metal sensing pads. A plurality of second transparent bridge lines are formed on the insulating layer located in the touch-sensing region. Each second transparent bridge line is electrically connected to two adjacent second meshed metal sensing pads through two first contact windows. The second transparent bridge lines completely cover the portion of the second meshed metal sensing pads exposed by the first contact windows.