Transparent Conductive Circuit With CNT Etch-Mask Metal Mesh
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Solution Overview
Problem
Existing transparent conductive films (TCFs) using silver nanowires (AgNW) face challenges in achieving low sheet resistance (Rs ≤ 1 Ohm per square) and high transparency (≥90% visible light transmittance) due to limitations in manufacturing processes, while chemical etching with wet wiping methods can cause reliability issues and damage to fine circuit traces.
Innovation Solution
A hybrid TCF comprising a metal mesh (MM) layer and a printed CNT ink layer, where the exposed MM regions are removed via chemical etching, utilizing the CNT ink as an etch mask to create a conductive circuit pattern, allowing for lower sheet resistance and high transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet wiping method is used to remove exposed AgNW regions, then manufacturing process is simple, but reliability is compromised due to residual AgNW and potential damage to fine traces
Solution Approach 1:
The patent replaces the mechanical wet wiping process with a chemical etching process. Instead of physically wiping away exposed AgNW regions, chemical etchants are used to selectively dissolve the metal mesh in exposed areas. This substitution eliminates the mechanical contact that causes residual AgNW and trace damage, thereby improving reliability while maintaining manufacturing feasibility.
Solution Approach 2:
The patent changes the processing parameter from mechanical removal to chemical removal. By using chemical etchants that selectively react with and dissolve the metal mesh material, the process achieves complete removal without mechanical stress. This parameter change resolves the contradiction by providing a reliable removal method that doesn't leave residuals or damage fine traces.
2Illumination intensity
If AgNW-based TCF is used, then transparency can be maintained, but sheet resistance cannot achieve ≤1 Ohm per square
Solution Approach 1:
The patent creates a hybrid composite structure combining metal mesh (MM) with carbon nanotube (CNT) ink layer. The MM layer provides the low sheet resistance (≤1 Ohm per square) while the CNT layer maintains transparency (≥90% VLT). This composite material approach resolves the contradiction by combining materials with complementary properties that neither material alone can achieve.
Solution Approach 2:
The patent segments the conductive film into two functional layers: a metal mesh layer for electrical conductivity and a CNT ink layer for transparency and circuit patterning. This segmentation allows each layer to optimize its specific function, with the MM providing low resistance and the CNT layer providing optical performance, thereby resolving the contradiction between sheet resistance and transparency.
3Manufacturing precision
If chemical etching is used to remove exposed MM, then precise circuit patterning is achieved, but CNT ink must serve as etch mask adding process complexity
Solution Approach 1:
The patent makes the CNT ink layer multi-functional: it serves both as the conductive circuit material and as the etch mask. The CNT ink is printed to define the circuit pattern, and the same printed pattern acts as the mask during chemical etching to protect the MM in circuit areas while allowing etching of exposed MM. This multi-functionality reduces overall process complexity despite the precision benefits of chemical etching.
Solution Approach 2:
The patent merges the circuit definition function and the mask function into a single CNT ink printing step. Instead of requiring separate mask fabrication and circuit patterning steps, the printed CNT ink simultaneously defines the circuit geometry and provides the protective mask for etching. This merging simplifies the overall process while achieving precise circuit patterning.
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 hybrid TCF achieves sheet resistance of ≤1 Ohm per square with ≥90% visible light transmittance, overcoming the limitations of AgNW-based TCFs by ensuring precise etching without damaging fine traces and reducing the risk of residual materials.
Implementation Method 1
the exposed MM (i.e., the regions where the CNT ink is not printed) is removed via chemical etching
Implementation Method 2
For chemical etching to work the printed CNT ink should also act as an etch mask
Implementation Method 3
maintaining high transparency. Low sheet resistance (Rs) is important for certain applications... with 85% visible light transmittance (VLT) for the printed transparent conductive film
Data Source
AI summary
A transparent conductive film (TCF) and methods for creating the TCF. The TCF includes a substrate having a surface, a metal mesh layer over at least a portion of the surface of the substrate, and a conductive layer over the metal mesh layer. The conductive layer includes carbon nanotubes and a binder.