Transparent RF Antenna and EMI Shield With CNT-Graphene Cu Mesh
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Solution Overview
Problem
Existing radio frequency (RF) antennas and electromagnetic interference (EMI) shields face challenges in achieving optimal performance, particularly in the 5G frequency range, due to limitations in transparency, conductivity, and frequency range coverage.
Innovation Solution
The integration of carbon nanotubes (CNTs) and/or graphene with a copper (Cu) mesh in transparent circuit structures enhances RF properties, providing improved RF shielding and transmission/reception benefits. This combination is used in both RF antennas and EMI shields, with the CNT and/or graphene ink acting as an etch mask during chemical etching or being patterned using a "kiss"-type automated cutter system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal mesh layer is used to achieve low sheet resistance, then electrical conductivity is improved, but transparency deteriorates
Solution Approach 1:
The patent divides the continuous metal mesh into a grid pattern with specific pitch and line width dimensions. This segmentation allows light to pass through the gaps between mesh lines while maintaining electrical conductivity through the conductive paths formed by the mesh lines and intersecting points.
Solution Approach 2:
The patent optimizes specific parameters of the metal mesh including pitch (50-500 microns), line width (1-50 microns), and line height (0.5-5 microns) to achieve the desired balance between sheet resistance (0.2-1 ohm/sq) and visible light transmission (85%-90%).
2Ease of manufacture
If CNT ink is printed to create conductive patterns, then manufacturing flexibility is improved, but chemical etching complexity increases
Solution Approach 1:
The printed CNT ink layer serves multiple functions: it acts as the conductive pattern definition layer, serves as an etch mask to protect underlying metal mesh during chemical etching, and provides the final transparent conductive pathway. This multi-functionality simplifies the overall manufacturing process.
Solution Approach 2:
The CNT ink is printed and dried to form a protective mask layer before the chemical etching process begins. This preliminary action prevents etchant from attacking the metal mesh in areas where conductivity should be maintained, eliminating the need for complex masking steps.
3Illumination intensity
If metal mesh dimensions are reduced to improve transparency, then light transmission is improved, but electrical conductivity deteriorates
Solution Approach 1:
The patent systematically optimizes the interrelated parameters of mesh pitch, line width, and line height to achieve the optimal balance. By adjusting these parameters within specific ranges, the patent achieves both high transparency (85%-90% VLT) and low sheet resistance (0.2-1 ohm/sq).
Solution Approach 2:
The patent combines the metal mesh layer with a transparent conductive oxide layer or printed CNT ink layer to create a composite structure. This composite approach allows the metal mesh to provide the primary conductive pathway while the additional conductive layer enhances conductivity and the transparent nature of all components maintains high light transmission.
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 CNT and/or graphene with Cu mesh structure achieves low sheet resistance values (0.2 to 1 ohm/sq) while maintaining high transparency (85%-90% visible light transmission), leading to enhanced antenna performance and EMI shielding effectiveness across a wide frequency range, including the 5G band.
Implementation Method 1
A chemical etchant is used to dissolve the exposed regions where the CNTs are not printed to create the conductive pattern
Implementation Method 2
the printed CNT and/or graphene ink has to also act as an etch mask
Implementation Method 3
The CNT and/or graphene hybrid film structure can be used as a high-performance EMI shielding film
Data Source
AI summary
This disclosure includes, and results in the creation of, a printed carbon nanotube and/or graphene hybrid antenna and/or EMI shield, comprised of a conductive layer that comprises a metal mesh (MM) layer or a nanowire layer on a substrate, with a printed Signal Enhancement Layer (SEL) on the conductive layer. The SEL includes an ink that includes one or both of carbon nanotube (CNT) and graphene. The circuit pattern results after the “exposed” conductive layer (i.e., the regions where the CNT/graphene ink is not printed) is removed via chemical etching or mechanical cutting. The structure (the antenna/EMI shield) is preferably but not necessarily transparent.