Electromagnetic Wave Absorbing, Thermal-Conductive Flexible Membrane with Shape-Modulated FeCo Nanobelts

Abstract

Electromagnetic wave (EMW)-absorbing materials, manufactured with composites of magnetic particles, are essential for maintaining a high complex permeability and modulated permittivity for impedance matching. However, commonly available EMW-absorbing materials are unsatisfactory owing to their low complex permeability in the high-frequency band. Herein, we report a thin, flexible EMW-absorbing membrane comprising shape-modulated FeCo nanobelts/boron nitride nanoparticles, which enables enhanced complex permeability in the S, C, and X bands (2–12 GHz). The boron nitride nanoparticles that are introduced to the FeCo nanobelts demonstrate control of the complex permittivity, leading to an effective impedance matching close to 1, consequently resulting in a high reflection loss value of −42.2 dB at 12.0 GHz with only 1.6 mm thickness. In addition, the incorporation of boron nitride nanoparticles improves the thermal conductivity for the heat dissipation of the absorbed electromagnetic wave energy. Overall, the comprehensive study of nanomaterial preparation and shape modulation technologies can lead to the fabrication of an excellent EMW-absorbing flexible composite membrane.

Absorption-Dominant mmWave EMI Shielding Films with Ultralow Reflection using Ferromagnetic Resonance Frequency Tunable M-Type Ferrites

“…Moreover, not only at these specific frequencies, the film shows ultralow reflection of less than 5% in two bands, including each frequency (36.9-41.4 GHz and 50.5-54.4 GHz), and low reflection less than 20% in a broad frequency band (34.5-58.5 GHz). It should be noted that the first ultralow reflection band covers the whole n260 band (37)(38)(39)(40). This implies that the proposed shielding film can solve EMI problems in 39 and 52 GHz telecommunication bands.…”

“…Then, the absorption shielding effectctiveness (SEA) of the material is defined as [ 4 ]: where is the attenuation constant of the electromagnetic waves in the material, and t is the material thickness. For a non-conducting material, e.g., the composite layer of the proposed shielding film, the attenuation constant is given as [ 38 ]: …”

“…Magnetic material-based composites have also been of interest due to their low conductivity and high magnetic loss [26,36]. There have been various attempts to increase the magnetic loss of magnetic materials including one-dimensional magnetic chain [37][38][39], core-shell structures [40][41][42][43], and regulated structural defects [44]. However, as most common magnetic materials, e.g., Fe or Co, lose their magnetic characteristics over 30 GHz, their EMI shielding performance is usually unsatisfactory in mmWave frequency bands.…”

“…GHz band(37)(38)(39)(40) is known as the 5G Band n260, and most major carriers in the US, including AT&T and Verizon, already acquired this band through a frequency band auction by the Federal Communication Commission[95]. The composite layer of this film includes 70 wt% SrFe 10.9 Co 0.55 Ti 0.55 O 19 which is SrM with an FMR frequency near 39 GHz.…”

A review: From the whole process of making thermal conductive polymer, the effective method of improving thermal conductivity

“…In addition, NH 2 ‐GnPs and PBZ modifications can reduce interface defects and thermal resistance. Chang et al 170 produced a thin, flexible EMW (Electromagnetic wave) absorbing film consisting of shaped‐modulated FeCo nanoribbons/boron nitride nanoparticles that enhance the composite permeability in the S, C, and X‐bands (2–12 GHz). The boron nitride nanoparticles introduced into the FeCo nanoribbons exhibit control over the composite dielectric constant, resulting in an effective impedance match close to 1, resulting in a high reflection loss value of −42.2 dB at 12.0 GHz with a thickness of only 1.6 mm.…”