The Highly Effective EMI Shielding Materials for Electric and Magnetic Fields Over the Wide Range of Frequency in Near-Field Region

ACS Appl. Mater. Interfaces

et al. 2022

Highly conductive polymer foam with light weight, flexibility, and high-performance electromagnetic interference (EMI) shielding is highly desired in the fields of aerospace, communication, and high-power electronic equipment, especially in the board-level packaging. However, traditional technology for preparing conductive polymer foam such as electroless plating and electroplating involves serious pollution, a complex fabrication process, and high cost. It is urgent to develop a facile method for the fabrication of highly conductive polymer foam. Herein, we demonstrated a lightweight and flexible silver-wrapped melamine foam (Ag@ME) via in situ sintering of metal–organic decomposition (MOD) at a low temperature (200 °C) on the ME skeleton modified with poly(ethylene imine). The Ag@ME with a continuous 3D conductive network exhibits good compressibility, an excellent conductivity of 158.4 S/m, and a remarkable EMI shielding effectiveness of 63 dB in the broad frequency of 8.2–40 GHz covering X-, Ku-, K-, and Ka-bands, while the volume content is only 2.03 vol %. The attenuation mechanism of Ag@ME for EM waves is systematically investigated by both EM simulation and experimental analysis. Moreover, the practical EMI shielding application of Ag@ME in board-level packaging is demonstrated and it shows outstanding near-field shielding performance. This novel strategy for fabrication of highly conductive polymer foam with low cost and non-pollution could potentially promote the practical applications of Ag@ME in the field of EMI shielding.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Metallized Skeleton of Polymer Foam Based on Metal–Organic Decomposition for High-Performance EMI Shielding

ACS Appl. Mater. Interfaces

et al. 2022

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“…Generally speaking, the EM wave radiation in the commonly rectangular waveguide test method is classified as far-field radiation, in which EM waves can be regarded as plane waves, where SE E (SE of the electric field) is equal to SE M (SE of the magnetic field) . The EMI SE of materials measured by the rectangular waveguide test method is regarded as far-field EMI shielding performance in research work, while the EMI SE of shielding materials applied in electronic equipment is usually evaluated by near-field shielding, in which SE E and SE M are not equal, and they can vary with the distance from the source. , The shielding models for electronic devices with and without a shield in practical application are shown in Figure a,b, respectively. The EM radiation from an analog chip without EMI shielding materials will interfere with the surrounding electronic equipment and harm human health (Figure a), while the EM radiation will be decreased due to the formation of a Faraday cage by the EMI shielding material and the surrounding lid (Figure b).…”

Section: Resultsmentioning

confidence: 99%

Graphene Oxide/Carbon Tube Composite Films with Tunable Porous Structures for Electromagnetic Interference Shielding

Huang

et al. 2022

ACS Appl. Nano Mater.

Carbon nanomaterials have received extensive academic attention in the field of electromagnetic interference (EMI) shielding due to their light weight and high electrical conductivity. Employing one-dimensional carbon tubes to construct macro-assembly EMI shielding material architectures accompanied by generating pores in materials remains crucial. Herein, we employed a new type of carbon tube with a whisker structure and excellent electrical conductivity, named as whisker CT (wCT), and used graphene oxide (GO) as a bridging and foaming agent to achieve a porous reduced graphene oxide/wCT film (rGWF) by the vacuum-assisted filtration and annealing process. The rGWF with an average thickness of ∼30 μm exhibited outstanding electrical conductivity of 4.96 × 103 S/m and excellent EMI shielding effectiveness of 45–58 dB in the broad frequency range of 8.2–40 GHz. In addition, EM simulation was conducted by using the COMSOL software, and it confirmed that the porous structures induced by GO during the thermal reduction process changed the polarization direction and distribution of the electric field of attenuated EM waves. Moreover, the remarkable near-field shielding performance of 25–50 dB in the frequency range of 1–9 GHz was evaluated, which demonstrates the potential application of rGWF in electronic packaging.

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Near-field and far-field EMI shielding response of lightweight and flexible MXene-decorated polyester textiles

Materials Today Physics

Wan

et al. 2022