CNT Shielding Sheet Structure for Thin Millimeter-Wave Attenuation
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Solution Overview
Problem
Existing electromagnetic wave shielding materials using carbon nanotubes face challenges with insufficient electromagnetic wave shielding performance, handling difficulties, and weak strength, particularly for millimeter waves and terahertz waves, due to issues with dispersion and adhesion in resin-based materials.
Innovation Solution
A high-strength electromagnetic wave shielding sheet is developed using a carbon nanotube unwoven cloth impregnated or laminated with a bismaleimide resin, optionally containing inorganic materials, to achieve a specific resistance of not larger than 0.005 Ω·cm and a thickness of not larger than 1 mm, enhancing conductivity and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon nanotubes are dispersed in resin to create shielding material, then electromagnetic wave shielding performance is improved, but handling difficulty and insufficient strength worsen
Solution Approach 1:
The patent combines carbon nanotube unwoven cloth with resin to create a composite shielding sheet. The carbon nanotube cloth provides electromagnetic wave shielding functionality while the resin matrix provides mechanical strength and ease of handling. This composite structure resolves the contradiction by integrating the functional advantages of carbon nanotubes with the structural advantages of resin.
Solution Approach 2:
The patent uses a thin film structure (thickness not larger than 1 mm) of carbon nanotube unwoven cloth impregnated with resin. This thin film configuration provides both the electromagnetic wave shielding performance needed and the flexibility for practical handling and installation, addressing the handling difficulty issue while maintaining shielding effectiveness.
2Reliability
If carbon nanotubes are used as shielding material, then electromagnetic wave shielding performance is improved, but strength and mechanical properties worsen
Solution Approach 1:
The resin-impregnated carbon nanotube unwoven cloth creates a composite material where the resin matrix provides mechanical strength and structural integrity while the carbon nanotube network provides electromagnetic wave shielding. This composite approach allows both shielding performance and mechanical strength to be achieved simultaneously.
Solution Approach 2:
The resin acts as an intermediary material that binds the carbon nanotube fibers together, providing mechanical strength and structural coherence to the shielding material. The resin matrix transfers and distributes mechanical loads while maintaining the conductive network of carbon nanotubes for electromagnetic shielding.
3Reliability
If carbon nanotubes are dispersed in resin, then electromagnetic wave shielding performance is improved, but dispersion difficulty and processing complexity worsen
Solution Approach 1:
Instead of dispersing carbon nanotubes in resin (which is difficult), the patent inverts the approach by using resin to impregnate pre-formed carbon nanotube unwoven cloth. This reversal of the process simplifies manufacturing significantly, as the resin simply needs to permeate the existing cloth structure rather than achieving uniform dispersion of individual nanotubes.
Solution Approach 2:
The carbon nanotube unwoven cloth has a porous, open structure that allows resin to easily penetrate and impregnate the material. This porous structure facilitates simple manufacturing through impregnation processes while maintaining the conductive network needed for electromagnetic wave shielding performance.
4Length of stationary object
If shielding material thickness is reduced, then thin-film and lightweight properties are improved, but electromagnetic wave shielding performance worsens
Solution Approach 1:
The patent achieves superior electromagnetic wave shielding performance in a thin film (not larger than 1 mm) by optimizing the specific resistance of the carbon nanotube unwoven cloth to be not larger than 0.005 Ω·cm. This parameter optimization allows high shielding effectiveness despite the reduced thickness, resolving the contradiction between thinness and shielding performance.
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 shielding sheet provides superior electromagnetic wave shielding performance with a specific resistance of not larger than 0.005 Ω·cm, achieving a shielding effect of not lower than 50 dB in the frequency band of 10 to 300 GHz, suitable for high-speed communication devices and vehicle installations.
Implementation Method 1
a highly electrically conductive carbon nanotube unwoven cloth having a thickness of not larger than 1 mm and a specific resistance of not larger than 0.005 Ω·cm
Implementation Method 2
a cured or uncured electromagnetic wave shielding sheet with a highly electrically conductive carbon nanotube unwoven cloth having a thickness of not larger than 1 mm and a specific resistance of not larger than 0.005 Ω·cm being impregnated with a resin (particularly, bismaleimide resin) and/or with the resin being laminated on the carbon nanotube unwoven cloth
Data Source
AI summary
Provided is a cured or uncured electromagnetic wave shielding sheet with a carbon nanotube unwoven cloth having a thickness of not larger than 1 mm being impregnated with a resin and/or with the resin being laminated thereon, the sheet exhibiting a superior electromagnetic wave shielding performance with respect to millimeter waves and terahertz waves. The sheet may for example be one with a carbon nanotube unwoven cloth having a thickness of not larger than 1 mm and a specific resistance of not larger than 0.005 Ω·cm being impregnated with a resin and/or with the resin being laminated thereon; or one with a carbon nanotube unwoven cloth having a thickness of not larger than 1 mm, an air permeability of not larger than 0.5 cm3/cm2·s and a specific resistance of not larger than 0.005 Ω·cm being impregnated with a resin.