Touch Sensor Bridge Structure to Prevent ITO Re-Crystallization
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Solution Overview
Problem
Conventional touch panels face issues with incomplete etching of the second ITO layer due to re-crystallization, leading to short or open circuits and poor touch-sensing functions, as the etching solution cannot effectively pattern the non-crystalline indium tin oxide layer without damaging the crystalline indium tin oxide layer.
Innovation Solution
An intermediate conductive layer is introduced between the first and second conductive layers of touch sensors, made of transparent conductive materials like tin oxide or zinc oxide, to prevent re-crystallization and ensure complete etching of the second conductive layer without direct contact, thereby isolating the layers and maintaining their respective properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the second ITO layer is made of non-crystalline indium tin oxide to enable selective etching, then the etching process can pattern the second layer without damaging the first crystalline ITO layer, but the non-crystalline ITO layer easily produces re-crystallization during fabrication processes causing incomplete etching
Solution Approach 1:
A buffer layer is introduced between the first crystalline ITO layer and the second non-crystalline ITO layer. This buffer layer acts as an intermediary that prevents re-crystallization of the second ITO layer while allowing the etching process to work effectively. The buffer layer is positioned at the overlapping region where the two ITO layers would otherwise directly contact and cause unwanted crystallization effects.
Solution Approach 2:
The problematic direct contact interface between the first and second ITO layers is extracted and replaced with the buffer layer. By removing the direct interaction between the two ITO layers, the re-crystallization issue is eliminated while preserving the selective etching capability of the non-crystalline second layer.
2Device complexity
If the first and second ITO layers are made of the same material to simplify material selection, then material consistency is achieved, but the etching solution cannot selectively etch the second layer without damaging the first layer
Solution Approach 1:
Different crystalline states are assigned to different ITO layers: the first layer uses crystalline ITO for stability, while the second layer uses non-crystalline ITO for etching responsiveness. The buffer layer provides local isolation to maintain this differentiated structure. This local differentiation enables selective etching while maintaining overall material consistency (all layers are still ITO).
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 solution prevents short-circuits and ensures reliable touch-sensing functions by preventing re-crystallization and incomplete etching, enhancing the yield of touch panels by maintaining the integrity of both conductive layers during the fabrication process.
Implementation Method 1
The second ITO layer made of the non-crystalline indium tin oxide easily produces a re-crystalline phenomenon during the fabrication processes of conventional touch panels. An intermediate conductive layer is disposed between a first conductive layer and a second conductive layer of touch sensors, such that the second conductive layer is not recrystallized.
Implementation Method 2
an etching solution, which can only etch the non-crystalline indium tin oxide and cannot etch the crystalline indium tin oxide, is used to etch the non-crystalline indium tin oxide of the second ITO layer to avoid damaging the first ITO layer
Implementation Method 3
the intermediate conductive layer has conductivity and electrically connects each of the bridge lines with the corresponding second conductive units
Data Source
AI summary
A touch-sensor structure includes a first conductive layer, a second conductive layer, insulating isolation portions, and an intermediate conductive layer. The first conductive layer includes first conductive units, connection lines and second conductive units. Each connection line connects to two first conductive units. The second conductive layer includes bridge lines. Each bridge line is electrically connected to two second conductive units. The insulating isolation portion is disposed between the connection line and the bridge line. The intermediate conductive layer is at least disposed at an overlapping position between the bridge lines and the second conductive units to isolate the first conductive layer from the second conductive layer. The intermediate conductive layer electrically connects each bridge line to the corresponding second conductive units.