• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.10
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• pp.798-804
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• 2012

This paper focuses on thermal properties of a newly prepared composite material by nano-silica and micro-silica mixture. Nano-silica and micro-silica mixture composites were made by dispersing surface treated nano-silica(average radius: 10 nm) and micro-size silica in epoxy resin. To investigate the effects of nano-silica and micro-size silica mixture(ENMC), the glass transition temperature (Tg), coefficients of thermal expansion(CTE) and elastic modulus of DMA properties by DSC, TMA and DMA devices were measured for the ENMC according to increase nano-silica addition contents and EMC. All properties of the neat epoxy were improved by the addition of micro-silica, which was improved much further by the addition of surface treated nano-silica to the EMC system.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.6
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• pp.767-773
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• 2019

The thermal diffusion performance of the electronic device is a factor for evaluating the stability of the electronic device. Therefore, many of research have been conducted to improve the thermal characteristics of thermal interface materials, which are materials for thermal diffusion of electronic products. In this study, nano thermal grease was prepared by blending graphene, silver and copper nano powders into a thermal grease, a type of thermal interface materials, and the heat transfer rate was measured and compared for the purpose of investigating the improved thermal properties. As a result, the thermal properties were good in the order of graphene, silver and copper, which is thought to be due to the different thermal properties of the nano powder itself.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.11
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• pp.895-901
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• 2012

In order to application for high voltage heavy electric equipments, epoxy/microsilica 60 wt%/nano layered silicate composites (EMNC_60) and epoxy/microsilica 65 wt%/nano layered silicate composites (EMNC_65) respectively was synthesized by our electric field dispersion method and the result was obtained completely dispersion state. Thermal properties such as glass transition temperature (Tg) and thermal expansion coefficient, and DMA characteristics were studied, and mechanical properties such as tensile and flexural tests were performed. AC electrical insulation strength was also tested. The study on thermal property, EMNC_65 was better than EMNC_60 and mechanical, electrical properties much improved EMNC_60 compared with EMNC_65.

• Transactions on Electrical and Electronic Materials
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• v.1 no.4
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• pp.25-29
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• 2000

In this paper, PET(Ployethylene Terephthalate) films with semiconducting and interface layers were investigated, The electrical properties, such as volume resistivity, tan$\delta$(dissipation factor) and breakdown strength at various temperatures were measured. Thermal analysis of PET and semiconducting films were measured and compared by differential scanning calorimeter(DSC) of each film. It is found that the volume resistivity of films(dependence on semiconducting interface layers)and electrical properties of PET films are changed ,Breakdown strength and dissipation factor of PET films with semiconducting layer (PET/S/PET) are decreased more greatly than PET and PET/PET films, due to the increase of charge density of charges at two contacted interfaces between PET and semiconductor, The dissipation factor of each films in increased with temperature,. For PET/S/PET film, is depended on temperature more than PET of PET/PET. However, the breakdown strength is increased up to 85$\^{C}$ and then decreased over 100$\^{C}$The electrical properties of PET films with semiconducting/interface layer are worse than without it It is due to a result of temperature dependency, which deeply affects thermal resistance property of PET film more than semiconducting/interface layers.

• Transactions on Electrical and Electronic Materials
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• v.14 no.2
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• pp.53-58
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• 2013

Graphene-based polymer nanocomposites are very promising candidates for new high-performance materials that offer improved mechanical, barrier, thermal and electrical properties. Herein, an approach is presented to improve the mechanical, thermal and electrical properties of unsaturated polyester resin (UPR) by using graphene nano sheets (GNS). The extent of dispersion of GNS into the polymer matrix was also observed by using the scanning electron microscopy (SEM) which indicated homogeneous dispersion of GNS through the UPR matrix and strong interfacial adhesion between the GNS and UPR matrix were achieved in the UPR composite, which enhanced the mechanical properties. The tensile strength of the nanocomposites improved at a tune of 52% at a GNS concentration of 0.05%. Again the flexural strength also increased around 92% at a GNS concentration of 0.05%. Similarly the thermal properties and the electrical properties for the nanocomposites were also improved as evidenced from the differential scanning caloriemetry (DSC) and dielectric strength measurement.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.7
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• pp.627-633
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• 2003

The effects of alloying-element additions to Ag sheath on thermal conductivity and mechanical properties of Bi-2223 superconductor tapes have been evaluated. In order to evaluate the effects of sheath alloys and their configuration on the properties of tape, various combinations of Ag and Ag alloys were selected as the inner and outer sheath. Thermal conductivity of the tapes was evaluated by using thermal integral method at 10 ∼120 K. It was observed that the addition of Mg, Sb, and Au to Ag sheath significantly decreased the thermal conductivity at low temperature probably due to the alloying effect. Specifically, the thermal conductivity of AgMg, AgSb, and AgAu at 40 K were 411.4, 142.3, and 109.7 W/(m·K), respectly, which is about 2∼9 times lower than that of Ag (1004.6 W/(m·K)). In addition, the thermal conductivity of alloy-sheathed tape was significantly dependent on their thermal conductivities of constituent sheath materials. The mechanical properties of alloy-sheathed tapes were also evaluated. Yield strength and tensile strength were improved but workability decreased for alloy-sheathed tapes.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.58-62
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• 2000

The fabrication process and analysis of thermal properties of 50~76vo1% SiCp/Al metal matrix composites(MMCs) for heatsink materials in electronic packaging were investigated. The 50~76vo1% SiCp/Al MMCs fabricated by pressure infiltration casting process showed that thermal conductivities were 85~170W/mK and coefficient of thermal expansion(CTE) were ranged 10~6ppm1k. Specially, the thermal conductivity and CTE of 71vo1%SiCp/Al MMCs were ranged 115~156W/mK and 6~7ppm/K. respectively, which showed a improved thermal properties than the conventional electronic packaging materials such as ceramics and metals.

• Transactions on Electrical and Electronic Materials
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• v.12 no.3
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• pp.98-101
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• 2011

A 10 nm nano-silica was introduced to a conventional 3 ${\mu}M$ micro-silica composite to develop an eco-friendly new electric insulation material for heavy electric equipment. Thermal and mechanical properties, such as glass transition temperature (Tg), dynamic mechanical analysis, tensile and flexural strength, were studied. The mechanical results were estimated by comparing scale and shape parameters in Weibull statistical analysis. The thermal and mechanical properties of conventional epoxy/micro-silica composite were improved by the addition of nano-silica. This was due to the increment of the compaction via the even dispersion of the nano-silica among the micro-silica particles.

• Structural Engineering and Mechanics
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• v.57 no.2
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• pp.369-387
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• 2016

In this work, random homogenization analysis for the effective thermal properties of a three-dimensional composite material with unidirectional fibers is presented by combining the equivalent inclusion method with Random Factor Method (RFM). The randomness of the micro-structural morphology and constituent material properties as well as the correlation among these random parameters are completely accounted for, and stochastic effective thermal properties as thermal expansion coefficients as well as their correlation are then sought. Results from the RFM and the Monte-Carlo Method (MCM) are compared. The impact of randomness and correlation of the micro-structural parameters on the random homogenized results is revealed by two methods simultaneously, and some important conclusions are obtained.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.4
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• pp.347-355
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• 2014

Thermal problems that are directly related to the lifetime of an electronic device are becoming increasingly important owing to the miniaturization of electronic devices. To solve thermal problems, it is essential to study thermal stability through thermal diffusion and insulation. A honeycomb sandwich plate has anisotropic thermal conductivity. To analyze the thermal deformation and temperature distribution of a system that employs a honeycomb sandwich plate, the thermal and elastic properties need to be determined. In this study, the thermal and elastic properties of a honeycomb sandwich plate, such as thermal conductivity, coefficient of thermal expansion, elastic modulus, Poisson's ratio, and shear modulus, are predicted. The properties of a honeycomb sandwich plate vary according to the hexagon size, thickness, and material properties.