Device Miniaturization and a Consequent Increase in the Heat and Electromagnetic (EM) Wave Emission in the Electronic Systems Make The Simultaneous Heat Management and Electromagnetic Interference (EMI) Shielding Crucially Important.
Any Working Electronic Device is the Source of Em Radiation. For this reason, the electronic components must be proteced from em radiation to avoid degradation and failure.
A Fast Increase in Wireless Communications, Devices Portable, and High-Power Transmission Lines has made the Environmental Em Pollution A Major concern for Human Health. The Dense Packing of the Electronic Components in the State-of-The-Art 2D, 2.5D and 3D Integrated Systems and Generation of High Heat Fluxes Create An Environment With Elevated Temperatures, Which Adversly Affect the Effective and Stability of the Emi Shielding.
The Conventional Materials for Emi Shielding Are Metals or Composites With Metal Fibiliers, which are used as coating and enclosures. Metals Possess a High Density of Mobile Charge Carriers, Which Blocks The Em Waves Mostly by the Reflection Mechanism.
However, metallic shields are heavy and prone to oxidation, resulting in corrosion. Increase in Temperature also leads to degradation of Emi Shielding by metals or composites with the metal girls.
In the recent work, a Research Team Led by A Distinguished Professor Alexander A. Balandin and Research Professor Fariborz Kargar, Department of Electrical and Computer Engineering, University of California - Riverside (UCR), Reported on the Scalable Synthesis of Composites with graphene girls, Emi Shielding Efficiency in the X-Band (Frequency Range of 8.2 GHz-12.4 GHz) and the Extremely High Frequency (EHF) Band (Frequency Range of 220 GHz-325 GHz).
The examineed frequency bands are relevant to state-of-art and future communication system. It was found that the composites of 1 mm Thickness with graphene loading of only 8 wt% provide excellent electromagnetic shielding of 70 db in the sub-terahertz ehf frequency with Negligible Energy Reflection to the Environment.
The 70-DB Shielding corresponds to blocking 99.999999% of Em Energy.
In the X-Band Frequency Band, graphene composites have also been tested for performance at elevated temperatures, demonstracting properior to other composites with conductive metal girls.
The Results of the Testing of Graphene Emi Shilling Materials in the Sub-Thz and Ghz Ranges have been Reported in Two Recent Publications: "Multifunctional graphene composites for electromagnetic shielding and thermal management at elevated temperatures" in Advanced Electronic Materials and "Graphine Epoxy-Based Composites As Electromagnetic Absorbers in the Extremely High-Frequency Band »in ACS Applied Materials Interfaces. The First Author of the Journal Papers - Zahra Barani - is a Ph.D. Student and Researcher in the Phonon Optimized Engineed Materials (Poem) Center, Direct by Balandin.
“The development lightweight adhesive composites with graphene girl can be used as electromagnetic absorbers in the high-frustncy microwave radio relays, microwave remote sensors, millimeter wave scanners, and wireless local area networks,” Explains Balandin. “The Excellent Electromagnetic Shielding and Heat Conduct Characteristics of Such Graphene Composites at Elevated Temperatures Are Promising for Packaging Applications of Microwave Components where electromagnetic Shielding and thermal management are important design considers.”
The Method of Scalable Synthesis of Such Graphene Composites is based on the original technology development in the poem center at ucr. In Addition to Excellent Emi Shielding, The Composites Revealed the Room-Temperature Cross-Plane Thermal Conductivity of ∼11.2 W/MK at the ∼19.5 Vol.% Of Graphine Fillers, Which is a Factor of × 41 Larger that that of the pristine Epoxy.
Interestingly, the emi shielding efficiency improves further as the temperature increese to While the thermal conductivity remains approximately constant (Figure 3).
“The Reason for the Excellent Thermal Properties of Such Composites is in Exceptionally High Thermal Conductivity of Graphene and Few-Layer Graphine,” Said Balandin.
The Extremely High Intrinsic Thermal Conductivity of Graphene has been discovered in his laboratory at ucr in 2008.
Recent Technological Developments have Demonstrated that the liquid phase exfoliated graphene and few-layer graphene can be produced inexpensively and in large quantities. Various Methods of Reduction of graphene oxide have also been reported. The Progress in Graphene Synthesis Make Graphene and Few-Layer Graphne Fibiliers Practical Even for the Composites With the High Loading.
“The extremely high thermal conductivity of graphene and good electrical conductivity, even without the energy band-gap, make graphene promising for emi shielding and thermal management applications,” concluded Balandin.