Transparent Conductive Substrate Nanowire Orientation Control
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Solution Overview
Problem
Transparent electrically conductive substrates using metallic nanowires exhibit anisotropy in surface resistance due to alignment of nanowires with the film transport direction, leading to higher resistance in the machine direction compared to the transverse direction, limiting their isotropic conductivity.
Innovation Solution
Introducing a forced draft from the transverse direction during the drying process of the substrate, after reducing the wet layer thickness to 13 μm or less, to alter the orientation of metallic nanowires and achieve uniform surface resistance in both directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metallic nanowires are applied in a coating liquid and dried, then a conductive stratum is formed on the substrate, but the nanowires become aligned with the film transport direction causing anisotropy in surface resistance
Solution Approach 1:
The patent applies a forced draft from the transverse direction during the drying process to dynamically alter the orientation of metallic nanowires. This dynamic intervention changes the nanowire alignment from the default machine direction orientation to a more isotropic distribution, resolving the anisotropy problem while maintaining conductive network formation.
Solution Approach 2:
The patent changes the drying conditions by introducing a forced draft from the transverse direction. This parameter change in the drying process affects the orientation behavior of nanowires during solvent evaporation, transforming them from aligned to non-aligned orientation and achieving isotropic surface resistance.
2Productivity
If the film transport speed is increased to reduce nanowire alignment, then productivity improves, but the shear velocity cannot be sufficiently controlled due to equipment constraints
Solution Approach 1:
The patent introduces a forced draft as an intermediary element during the drying process. This intermediary airflow from the transverse direction mediates the nanowire orientation by counteracting the alignment effect caused by film transport, enabling orientation control without requiring changes to the film transport speed or drying equipment capacity.
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
The method significantly improves the anisotropy of surface resistance, achieving a ratio of transverse to machine direction resistance between 0.8 to 1.2, making the substrates suitable for isotropic applications like touch panels.
Implementation Method 1
introduction of a forced draft from the TD of the substrate film immediately after application of the coating liquid
Implementation Method 2
a process of applying a coating liquid containing metallic nanowires dispersed in a solvent onto a substrate to form a wet layer thereon, a process of drying the wet layer on the substrate to remove the solvent therefrom
Data Source
AI summary
Method of manufacturing a transparent electrically conductive substrate having an application process whereby a wet layer is formed by applying onto a substrate film a coating liquid comprising metallic nanowires dispersed in a solvent, and a drying process whereby the solvent contained in the abovementioned wet layer is removed by drying, characterised in that the abovementioned drying process includes a process whereby the orientation of the abovementioned metallic nanowires is altered by introducing a forced draft facing towards the substrate from a direction that is different from the longitudinal direction of the substrate film.