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Nano-SiO 2 porous thermal insulating material (TIM) has drawn tremendous research interests due to its advantages of low density, high porosity and low thermal conductivity. However, its long-term stability in humid environment can be severely deteriorated by the high hydrophilicity resulting from tetrahedral coordination of oxygen and capillary effect of porous structure. It is still a great challenge to cost-effectively fabricate bulk TIM with superior hydrophobicity and consequent remarkable self-cleaning capability. Herein, via an oil-in-water microemulsion treatment, we have proposed a new strategy to construct 3D superior hydrophobic nano-SiO 2 porous TIM. The polymethylhydrosiloxane-modified TIM exhibits a large water contact angle of 166°, and corresponding excellent self-cleaning characteristic while maintaining low thermal conductivity of 0.031 W/m·K. Moreover, our high hydrophobicity of TIM exhibits excellent durability under high temperature up to 400 °C, high humidity of 100%, and chemical erosions. Detailed knowledge of the physical chemistry basis of the superior hydrophobic nano-SiO 2 porous TIM can provide great opportunity to fabricate advanced self-cleaning and heat insulating devices especially targeted for harsh environments. [ABSTRACT FROM AUTHOR]

With the development of electronic components towards high power, high packaging density, and miniaturization of device size, heat dissipation and the electromagnetic interference problems between the electronic components are emerging. In order to solve the undesirable electromagnetic wave and heat emissions produced by electronic device simultaneously, the electronic packaging materials with high thermal conductivity and anti-electromagnetic interference are highly expected. In this work, NiFe2O4-modified short carbon fibers (SCF) were designed and prepared. NiFe2O4 were in situ grown on the surface of SCF by hydrothermal method. The chemical structure and morphology of SCF-NiFe2O4 were characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The microwave absorbing performance test shows that SCF-NiFe2O4 possess superior microwave absorbing performance, where the minimum reflection loss is − 20.7 dB. Finally, SCF-NiFe2O4/epoxy resin composites were prepared by introducing SCF-NiFe2O4 as thermal conductive filler into epoxy resin. The surface-modified SCF with NiFe2O4 is more easily infiltrated by resin and exhibits strong interfacial interaction with the matrix. With the increase of the content of SCF-NiFe2O4, the thermal conductivity of the composites increases obviously. When the content of SCF-NiFe2O4 reaches 20 vol%, the composites show better thermal conductivity, and the thermal conductivity reaches 1.03 W/m K. [ABSTRACT FROM AUTHOR]

Abstract: The production of composites of epoxy molding compounds (EMCs), which can feature a good balance between thermal conductivity and flame-retardant behavior in terms of flammability and burning behavior, was achieved by incorporating high thermal conductivity Si3N4 and flame retardant Al(OH)3 (ATH) fillers in the epoxy matrix. The experimental results were obtained from thermal conductivity measurements and limiting oxygen index (LOI) and UL-94 tests. These results showed that the Si3N4 filler has a great influence on thermal conductivity, which markedly increased for Si3N4 volume fractions >40%, whereas the ATH filler greatly improved the flame resistance of EMCs. The simultaneous presence of both Si3N4 and ATH fillers in the EMCs positively influenced both properties. The aim of this study was to produce composites suitable for electronic packaging applications: an optimum combination of the two fillers was determined for a total volume fraction of fillers in EMC of 60vol.% and a volume ratio of Si3N4:ATH at 3:2; this composite had a thermal conductivity of 2.15W/mK, an LOI of 53.5, and a UL-94 vertical burning test ranking of V-0. [Copyright &y& Elsevier]

The article presents a study regarding the thermal conductivity in epoxy molding compounds (EMCs). The study used epoxy resin and multi-fillers of Si3N4 matrix and SiO2 filler. Results showed that the microstructure and morphology of the top of EMC indicated the formation of continuous network that anticipates heat conductivity. Moreover, the dielectric constant of EMC samples increased with Si3N4 content.

For new-generation miniaturized and high-frequency electronics, it is of vital importance to develop advanced electronic packaging materials, which combine high electromagnetic interference (EMI) shielding effectiveness (SE) and efficient thermal management capabilities, including heat absorption, thermal conductivity (TC) and heat dissipation. However, high EMI SE and efficient thermal management usually cannot complement each other for the same packaging material, because EMI shielding devices convert electromagnetic radiation directly into heat consumption, leading to consequent severe challenge to dispose heat dissipation. Herein, we have newly developed a high-performance phase change composites, in which MXene is confined in shape-stabilized phase change material (PCM) for simultaneous achievement of high EMI SE and efficient thermal management. Regarding high EMI, MXene can effectively shield electromagnetic radiation by converting the radiation into heat consumption. As for thermal management, PCM enables efficient heat absorption via the phase change process, and MXene enhances the thermal conductivity (TC) of MXene/PCM composite to facilitate heat dissipation. As a result, our developed MXene/PCM composite can achieve a high EMI SE of 64.7 dB in X-band, with an improved TC of 0.74 W/m·K. Furthermore, the interlayer capillary effect of MXene inhibits the leakage of liquid PCM during the solid-liquid phase transition, which can maintain the PCM shape stability. Our newly-designed shape-stabilized MXene/PCM composites with high EMI SE and large TC shed new light on designing EMI shielding materials with prolonged exposure to electromagnetic radiation, which can be envisioned to exhibit vast implications for advanced new-generation miniaturized and high-frequency electronics. [Display omitted] [ABSTRACT FROM AUTHOR]

The high integration density of microelectronic devices leads to local heat accumulation, and effective heat dissipation and signal transmission of packaging materials have become the primary issues to be solved. However, existing polymer materials have difficulty meeting the requirements due to their unsatisfactory thermal conductivity and thermal expansion properties. In this work, we proposed the use of digital light processing (DLP) printing technology to construct a triply periodic minimum surface (TPMS) skeleton, and a continuous and efficient heat conduction path was successfully constructed in epoxy resin by impregnating h-BN on the skeleton surface. When the loading of h-BN was 20 vol%, the thermal conductivity of the TPMS(SiO 2)@BN/EP(BN) composites was 1.86 W/(m·K), which was 786 % higher than that of pure epoxy resin. In addition, the thermal expansion coefficient of the composites decreased by more than 70 %. At the test frequencies of 3∼10 MHz, the composites showed stable dielectric properties, and the dielectric constant was always maintained in a low range, between 3.85 and 4.15. This work has realized the transformation of the method for constructing a heat conduction path from disordered to ordered and from random to repeatable. This provides a new strategy for the selection of microelectronic packaging materials. [ABSTRACT FROM AUTHOR]

This paper presents that polyethylene glycol (PEG) synthesizes a form-stable phase change material (FS-PCM) with high thermal conductivity and considerable heat storage density. PEG was confined to the chain structure of epoxy resin (EP) via high-temperature melt blending and curing, which solves the leakage problem of PCMs during phase transformation. In order to increase the thermal conductivity and stability of the PEG/EP while maintaining good heat storage capacity and insulation ability, a low loading of reticulated porous Al 2 O 3 ceramic (RPC) was introduced into the PEG/EP matrix. RPC increases the thermal conductivity of FS-PCM by 5.5 times and the heat storage rate by 4 times. In addition, FS-PCM filled with 13.8 vol% RPCs has a coefficient of thermal expansion (CTE) of 80 ppm/K at 85–150 °C -a decrease of 62% over the matrix. Furthermore, the BN network is formed on RPC by vacuum impregnation technology, which further improves the thermal conductivity. This novel FS-PCM has excellent comprehensive properties and does not need for case package, indicating great prospects in thermal management and thermal storage. [ABSTRACT FROM AUTHOR]

• Polymer-matrix composites. • 3-Dimensional reinforcement. • Thermal properties. • Syntactic foams. • Hollow glass microspheres. Electronic packaging materials with low dielectric constant (D k) and high thermal conductivity (TC) are of vital importance in mitigating signal delay and enhancing heat dissipation efficiency in modern electronics. However, low D k and high TC are difficult to complement each other, because high TC filler usually possesses a high D k. Herein, we have newly designed a composite material simultaneously with low D k and high TC through hollow glass microspheres (HGMs), boron nitride particles, epoxy resin and reticulated porous ceramic (RPC). The composite material prepared by sintering HGMs and RPC is more effective in improving TC while keeping low D k. Specifically, the D k of the newly designed composite is lower than 3.0 with a large TC of 0.96 W/m·K. This new epoxy-matrix composite with both low D k and high TC can shed new light on designing electronic packaging materials for advanced miniaturized electronics. [ABSTRACT FROM AUTHOR]

• MXene/AgNWs aerogels with interpenetrating double-network structure were fabricated. • The porous structure contributes to higher attenuation of electromagnetic waves. • 3D network provides channel for electron and phonon transmission in epoxy composites. • The composites possess remarkable EMI SE and thermal conductivity. The novel multifunctional materials with anti-electromagnetic interference (EMI) and effective thermal management are ideal for modern electronic industry. Generally, the EMI shielding effectiveness (SE) and thermal conductivity (TC) of materials can be effectively enhanced by compounding with high electrically and thermally conductive fillers. However, it seems that the high-performance cannot be compensated without sacrificing the high fillers loading. Herein, from one-dimensional silver nanowires (AgNWs) and two-dimensional MXene, three-dimensional MXene/AgNWs aerogels were designed as electric and heat transferring skeletons for epoxy nanocomposites by directional-freezing and freeze-drying methods. The resultant MXene/AgNWs/Epoxy nanocomposites with a low MXene/AgNWs content of 8.2 wt% combine a high electrical conductivity of 1532 S/m, and an exceptional EMI SE value of 94.1 dB with 3 mm thickness at the X-band frequency, as well as an improved TC of 2.34 W/m·K. The fabricated MXene/AgNWs/Epoxy nanocomposites possess excellent comprehensive properties enable valuable applications in electronic devices for EMI shielding and thermal management. [ABSTRACT FROM AUTHOR]

Effects of Li2O on the densification and the thermal conductivity of AlN ceramics sintered at a low temperature were studied by using Li2CO3, CaF2 and Y2O3 as additives. DTA and XRD were employed to identify the formation of the liquid and the changes of the phase compositions during the sintering. SEM and TEM were used to observe the microstructures of AlN specimens sintered at 1650 °C. The results show that Li2O is an effective sintering aid, leading to high densification and high thermal conductivity at low sintering temperatures. AlN specimens with full densification and thermal conductivity were achieved with Li2O addition. The high densification comes from the promotion of the liquid containing Li and CaYAlO4. The high thermal conductivity is attributed to the purification of the AlN lattice, the enhancement of the density and the elimination of some grain-boundary phases. [Copyright &y& Elsevier]