Touch Sensor Bridge Visibility Reduction via Passivation Layer
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Solution Overview
Problem
The visual recognition of the bridge area is a problem in touch sensors when the bridge is formed using the upper connection method, as the conductive metal layer is selectively etched, affecting the transparent conductive layer and causing visibility issues.
Innovation Solution
A touch sensor configuration with a base layer, electrode layer, insulation layer, and bridges, where dummy holes with the same shape, area, and spacing as contact holes are formed, and the bridge is made narrower than the contact hole, with a passivation layer filling the etching holes to prevent visibility and allow for low-resistance material selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If selective etching is performed in the bridge formation process to form a conductive metal layer bridge, then the bridge can be formed to connect sensing cells, but the transparent conductive layer is etched together causing the bridge area to be visually recognized
Solution Approach 1:
A pattern layer is formed in advance covering the bridge area before the etching process. This preliminary protective layer prevents the transparent conductive layer from being etched during bridge formation, thereby avoiding visual recognition of the bridge area while still allowing the conductive metal layer bridge to be formed through selective etching.
Solution Approach 2:
The pattern layer acts as an intermediary protective element between the etching process and the transparent conductive layer. It selectively protects the bridge area during etching, preventing harmful etching effects while allowing the bridge formation process to proceed.
2Object-affected harmful factors
If the bridge width is reduced to minimize visual recognition, then the aesthetic appearance is improved, but the resistance of the bridge increases
Solution Approach 1:
The patent changes the material parameter of the bridge from transparent conductive oxide to conductive metal, which has superior electrical conductivity. This parameter change allows the bridge to maintain low resistance even with reduced width, thereby minimizing visual recognition while preserving electrical performance.
3Device complexity
If conventional etching is used for bridge formation, then the process is simple, but the transparent conductive layer is damaged causing visual defects
Solution Approach 1:
The pattern layer serves as an intermediary protective layer during the etching process. It is applied over the bridge area before etching and prevents the etchant from damaging the transparent conductive layer, thereby eliminating visual defects while maintaining process simplicity.
Solution Approach 2:
The pattern layer is formed preliminarily before the etching step to protect the transparent conductive layer. This preliminary protective measure prevents damage during the subsequent etching process without adding significant complexity to the overall manufacturing流程.
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 configuration minimizes the visibility of the bridge area during etching, allowing for easy and quick bridge etching without resistance limitations, enabling the use of low-resistance materials and preventing obstacles in the bridge formation process.
Implementation Method 1
the passivation layer may fill the etching hole
Data Source
AI summary
A touch sensor includes a base layer; an electrode layer including, on the base layer, first array sensing cells connected and arranged in a first direction and second array sensing cells spaced apart from the first array sensing cells and arranged spaced apart in a second direction, the first and second sensing cells being provided with dummy holes; an insulation layer formed on the electrode layer and being provided with contact holes connecting the neighboring second array sensing cells in the second direction; and bridges formed on the contact hole and the insulation layer to electrically connect the neighboring second array sensing cells.