Touch Screen Panel Selective Etching for Electrode Defect Reduction
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Solution Overview
Problem
The existing electrostatic capacitive touch screen panels face defects in sensing electrodes and outer lines due to overetching, as the first and second metal layers are etched together, leading to inefficiencies in manufacturing.
Innovation Solution
The touch screen panel design includes a touch substrate with first and second sensing electrodes and outer lines, where the first sensing metal layer, second sensing metal layer, and first outer metal layer are on the same layer, and the first transparent sensing electrode layer, second transparent sensing electrode layer, and transparent outer electrode layer are on the same layer, preventing overetching by using selective etching techniques and materials like silver nano-wire and PEDOT-PSS for the sensing electrodes and ITO, IZO, or IGZO for the transparent layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the first and second metal layers are etched together to form sensing electrodes, then the etching process can be simplified, but overetching occurs leading to defects in the sensing electrodes and outer lines
Solution Approach 1:
The patent segments the etching process into two distinct stages: first etching the transparent electrode layer to form patterns, then selectively etching the metal layers. This segmentation prevents overetching by controlling which layers are removed at each stage, thereby maintaining manufacturing precision while keeping the overall process manageable.
Solution Approach 2:
The patent applies preliminary action by first forming a transparent electrode layer pattern before metal layer deposition and etching. The transparent electrode layer serves as a preliminary structure that guides subsequent etching steps, ensuring precise patterning of the sensing electrodes and outer lines without overetching.
2Ease of manufacture
If the first metal layer and second metal layer have similar electronegativity values, then material selection is simplified, but selective etching becomes difficult causing overetching
Solution Approach 1:
The patent applies local quality by using different material compositions for the first metal layer and second metal layer in different regions. The first metal layer uses a material with higher electronegativity (e.g., aluminum) that etches faster, while the second metal layer uses a material with lower electronegativity (e.g., molybdenum or tungsten) that etches slower. This local differentiation enables selective etching without compromising overall material selection simplicity.
Solution Approach 2:
The patent changes the electronegativity parameter of the metal layer materials to enable selective etching. By selecting materials with different electronegativity values, the etching process can selectively remove the first metal layer while preserving the second metal layer, thereby preventing overetching and improving sensing electrode reliability.
3Area of stationary object
If outer lines are disposed in the touch non-active area, then the touch active area is maximized, but the outer lines are more susceptible to etching defects
Solution Approach 1:
The patent applies preliminary action by first forming the transparent electrode layer pattern that defines the outer line positions before metal layer deposition. This preliminary pattern serves as a template that guides subsequent metal layer etching, ensuring precise outer line formation even in the touch non-active area where the lines are more susceptible to etching defects.
Solution Approach 2:
The patent changes the etching parameters (such as etchant concentration, temperature, and etching time) specifically for the outer line regions to compensate for their susceptibility to etching defects. This parameter optimization ensures precise outer line patterning while maintaining the maximized touch active area.
Data Source
AI summary
A touch screen panel includes a touch substrate, first sensing electrodes, second sensing electrodes, and outer lines. The touch substrate includes a touch active area and a touch non-active area. The first and second sensing electrodes are disposed in the touch active area and insulated from each other while crossing each other. Each first sensing electrode includes a first sensing metal layer and a first transparent sensing electrode layer. Each second sensing electrode includes a second sensing metal layer and a second transparent sensing electrode layer. Each outer line includes a first outer metal layer, a transparent outer electrode layer, and a second outer metal layer.