CNT Nonwoven Shielding Sheet for Thin, Conductive EMI Covering
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Solution Overview
Problem
Existing electromagnetic (EM)-shielding materials using carbon nanotubes (CNTs) face challenges in achieving sufficient conductivity, thickness, and handling ease, particularly in miniaturized electronic devices, and are not suitable for covering electronic parts and connections effectively.
Innovation Solution
An EM-shielding sheet comprising a multilayer film of carbon nanotube nonwoven fabric with a resistivity of 0.00005 to 0.05 Ω·cm and a thickness of 1 to 500 µm, combined with a resin, a pressure-sensitive adhesive layer, and a release film, which can be in various laminate configurations to enhance conductivity and reduce thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon nanotube paste or aqueous coating materials are used for EM shielding, then EM-shielding performance can be achieved, but the materials are awkward to handle and have insufficient electro-conductivity
Solution Approach 1:
The patent uses carbon nanotube nonwoven fabric as a composite material that combines the EM-shielding properties of CNTs with the structural advantages of nonwoven fabric, achieving both high electro-conductivity (0.00005 to 0.05 Ω·cm) and ease of handling. The nonwoven fabric structure allows the material to be easily applied while maintaining sufficient conductivity for effective EM shielding.
2Reliability
If the thickness of CNT sheet is increased to achieve equivalent shielding performance to metal foils, then EM-shielding performance improves, but it becomes problematic for mounting in miniaturized devices
Solution Approach 1:
The patent changes the key parameter of electro-conductivity by using high-quality carbon nanotube nonwoven fabric with resistivity of 0.00005 to 0.05 Ω·cm. This parameter change allows the material to achieve equivalent EM-shielding performance to metal foils at a much reduced thickness of 1 to 500 μm, making it suitable for miniaturized devices.
3Stability of the object's composition
If carbon nanotubes are used in fine fibril form with large specific surface area, then dispersion is improved, but the amount of CNT that can be dispersed is limited and conductivity remains insufficient
Solution Approach 1:
The patent employs carbon nanotube nonwoven fabric as a thin film structure that provides both good dispersion of carbon nanotubes and sufficient electro-conductivity. The nonwoven fabric format allows extensive surface area for dispersion while maintaining continuous conductive pathways through the entangled CNT network, resolving the contradiction between dispersion quality and conductivity.
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 multilayer structure provides equivalent EM-shielding performance with reduced thickness, making it suitable for covering electronic parts and connections while being easy to handle and applicable in miniaturized devices.
Implementation Method 1
an electronic equipment will malfunction by the interference of surrounding electromagnetic waves... there is the demand for EM-shielding material having EM-shielding performance in the microwave, EHF and terahertz bands
Implementation Method 2
The CNTs used therein are of fine fibril form, have a large specific surface area, and cannot be dispersed in a large amount. The resulting materials have an insufficient electro-conductivity below the practically acceptable level
Implementation Method 3
a pressure-sensitive adhesive layer disposed on one outermost surface of the multilayer film
Data Source
Figure 1A~1C
Figure 2
Figure 3
AI summary
An electromagnetic-shielding sheet (1a, 1b or 1c) is provided comprising a multilayer film including at least two layers (2) of carbon nanotube nonwoven fabric, a pressure-sensitive adhesive layer (5), and a release film (6). The sheet exerts the electromagnetic-shielding effect while minimizing the thickness of carbon nanotube nonwoven fabric, is easy to handle, and is used to cover electronic parts and connections within electronic equipment.