| 391. |
- Wang, D., et al.
(författare)
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Experimental investigation of gas flow in copper channel carbon nanotubes coated micro coolers
- 2011
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Ingår i: Proceedings - 12th International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2011, Shanghai, 8-11 August 2011. - 9781457717680 ; , s. 560-563
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Konferensbidrag (refereegranskat)abstract
- As the integrity of micro electronic devices improves, the heat power of chips is getting higher and higher. How to reduce the temperature of micro electronic devices effectively becomes more and more important. In this paper, a micro-channel cooler test system is set up. By measuring the temperature and pressure at inlet and outlet of the micro cooler and the average temperature of micro cooler bottom, the heat transfer performance of the copper based CNTs coated micro cooler is researched. The thermal resistance of copper and silicon based CNTs coated micro cooler are compared. It is shown that the copper based CNTs coated micro cooler has good thermal dissipation capacity than that of the Silicon based CNTs coated micro cooler.
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| 392. |
- Wang, Nan, 1988, et al.
(författare)
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Development and Characterization of Graphene Enhanced Thermal Conductive Adhesives
- 2016
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Ingår i: 2016 6th Electronic System-Integration Technology Conference (Estc). - 9781509014026 ; , s. Article no 7764682-
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Konferensbidrag (refereegranskat)abstract
- In this paper, a graphene enhanced thermal conductive adhesive (G-TCA) was developed for thermal management of power devices. The developed G-TCA has many advantages, including high thermal conductivity, lower density, good dispensing ability. and cost effective. To fabricate G-TCAs. few-layer graphene was utilized as fillers to improve the thermal conductivity of the TCA. The graphene nanosheets were fabricated through a high-speed shear mixing process in a mixed solvent. Compared to many reported liquid exfoliation process, the graphene fabrication process shows many advantages, such as high process efficiency, mass production, low-cost, clean and safe process. G-TCA sample with a hybrid filler ratio of 73% Ag and 3% graphene shows the highest thermal conductivity of 8 W/m K, which is almost four times higher than reference TCAs. A Joule heating setup was built to simulate G-TCA's function in a real electronic component and demonstrate the superior heat dissipation properties of the G-TCAs. Viscosities of the G-TCA samples were regulated in an acceptable range of many dispensing processes to be able to make uniform and fine patterns. Therefore, the developed G-TCA could be widely used for thermal management of power devices and electronic packaging area to decrease their working temperatures and extend the lifetime of devices.
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| 393. |
- Wang, Nan, 1988, et al.
(författare)
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Efficient surface modification of carbon nanotubes for fabricating high performance CNT based hybrid nanostructures
- 2017
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223. ; 111, s. 402-410
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nanotubes (CNTs) were chemically modified to achieve strong binding strength with the attached functional components as well as good dispersability and nanoparticle size-uniformity. An efficient multi-oxidation process was developed to create porous out layer with many nanoscale defects on the surface of CNTs for metallic nanoparticle close attachment and bond sufficient oxygen-containing groups, which assisted the dispersion of CNTs in the aqueous solution. The surface modified CNTs have advantages of strong binding capability, large surface area, high mechanical strength and good dispersability, which show great potential as building blocks for hybrid nanomaterials. Monodispersed silver nano particles with an average size of 3 nm were formed from inside the created nanoscale defects on the surface of CNTs without any obvious agglomerations. The fabricated hybrid exhibited much enhanced anti-bacterial performance compared to commercial silver nanoparticles due to the combined antibacterial effects of CNTs and silver nanoparticles. With these superior properties, the developed surface modification process could be widely used for improving the performances of many CNT based hybrid nanomaterials in diverse applications.
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| 394. |
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| 395. |
- Wang, Nan, 1988, et al.
(författare)
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Flexible Multifunctionalized Carbon Nanotubes-Based Hybrid Nanowires
- 2015
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-3028 .- 1616-301X. ; 25:26, s. 4135-4143
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Tidskriftsartikel (refereegranskat)abstract
- In this work, flexible multifunctionalized carbon nanotube (CNT)-based hybrid nanowires are synthesized through surface modification processes. The good dispersability of the hybrid nanowire in polar solvents facilitates directly making fine patterns with a minimum width of 40 μm for applications of flexible and stretchable circuits (FSCs). The hybrid nanowire possesses a flexible and highly conductive structure which demonstrates stable electro-mechanical properties on polydimethylsiloxane (PDMS) substrates under large structural deformation. FSCs fabricated from the hybrid nanowires show a constant resistance of 0.096 Ω □-1 (equivalent of a resistivity 0.96 Ω μm) under repeated bending cycles. The FSCs also have a low and stable sheet resistance of 0.4 Ω □-1 for strains up to 30%, which is almost four orders of magnitude lower than that of pure CNT samples (1316 Ω □-1). Further improved stretchability and electro-mechanical properties (0.1 Ω □-1, at the strain of 100%) are achieved with a prestrain PDMS substrate. Repeated deformation tests demonstrate the high reliability of FSCs. The observed stable and reliable electro-mechanical performance of FSCs suggests the potential use of the material in wearable and portable electronics. Multifunctionalized hybrid nanowires based on carbon nanotubes are prepared through different surface modification processes. These hybrid nanowires exhibit both the high electrical conductivity of metal and excellent mechanical properties of carbon nanotubes together with good dispersability. Flexible and stretchable electrodes based on the hybrid nanowires demonstrate stable electro-mechanical properties under large structural deformations.
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| 396. |
- Wang, Nan, et al.
(författare)
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Highly thermal conductive and electrically insulated graphene based thermal interface material with long-term reliability
- 2019
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Ingår i: Proceedings - Electronic Components and Technology Conference. - 0569-5503. ; 2019-May, s. 1564-1568
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Konferensbidrag (refereegranskat)abstract
- High density packaging in combination with increased transistor integration inevitably leads to challenging power densities in terms of thermal management. The conventional TIMs that are widely used in the microelectronic industry today are experiencing more and more stress due to their limited thermal performance and poor reliability. Composed by particle laden polymer matrix, thermal conductivity (K) of conventional TIMs is generally limited to 5 W/mK, and such values can be even lower for electrically insulated TIMs. Conventional TIMs also suffer from severe pump-out and dry-out failures, which brought great threat to the performance and lifetime of the electronic devices. Here, we solve these problems by applying a novel highly thermal conductive, electrically insulated and reliable graphene based TIMs (I-GTs). Composed by vertical graphene structures, I-GTs provide a continuous heat pathway from top to bottom, which enables superfast heat dissipation at through-plane direction. The highest bulk through-plane thermal conductivity of the conductive body can reach up to 1000 W/mK, which is orders of magnitude higher than conventional TIMs, and even outperforms the pure indium TIMs by over ten times. The highly flexible and foldable nature of I-GT enables at least 100% compressibility upon small applied pressures. As excellent gap fillers, I-GT can provide complete physical contact between two surfaces and thereby minimize the contact resistance to heat flow. The measured minimum thermal resistance for I-GTs reaches about 30 Kmm2/W. Such values are significantly higher than the randomly dispersed composites presented above. To ensure fully electrical insulation, a smooth and soft adhesive layer with a thickness of few microns was coated on the surface of I-GT. The breakdown voltage of I-GT reaches up to 950 V. Thermal cycling test shows the highly stable nature of I-GT. The good compressibility and elasticity of I-GT ensures continued proper TIM contact with substrates, which counteracts the effect of internal stress induced by the mismatch of coefficient of thermal expansion (CTE) during temperature cycling. In addition, the I-GTs have the advantages of low density and good maintainability. The resulting I-GTs thus opens new opportunities for addressing large heat dissipation issues for form-factor driven electronics and other high power driven systems.
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| 397. |
- Wang, Nan, et al.
(författare)
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Highly Thermally Conductive and Light Weight Copper/Graphene Film Laminated composites for Cooling Applications
- 2018
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Ingår i: 2018 19TH INTERNATIONAL CONFERENCE ON ELECTRONIC PACKAGING TECHNOLOGY (ICEPT). - 9781538663868 - 9781538663868 ; , s. 1588-1592
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Konferensbidrag (refereegranskat)abstract
- A light-weight, robust and highly thermal conductive copper/graphene film laminated structure was developed as novel heat spreading materials for thermal management applications. The advantages of the copper/graphene film laminated structure lie in its ability to combine both good mechanical properties of metals and excellent thermal properties of graphene film. Graphene films (GFs) were fabricated via self-assembly of graphene oxide (GO) sheets and post-treated by high temperature graphitization and mechanical pressing. The resulted GFs show excellent flexibility and greatly improved tensile strength which is over 3 times higher than commercial PGS. The successful lamination between copper and GFs was realized by indium bonding. Thin indium layers can provide complete physical contact between copper and GFs, and thereby, minimize the contact resistance induced by surface roughness. The measured contact thermal resistance between copper and GFs bonded by indium is in the range of 2-5 Kmm(2)/W for a working temperature between 20 degrees C to 100 degrees C. This value is orders magnitude lower than other bonding methods, including direct hot pressing of copper and GFs, tape bonding and thermal conductive adhesive (TCA) bonding. By tailoring the thickness of GFs, desirable laminated composites with optimized thermal conductivity can be obtained, which offers an efficient heat dissipation solution for power driven systems.
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| 398. |
- Wang, Nan, 1988, et al.
(författare)
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Improved Interfacial Bonding Strength and Reliability of Functionalized Graphene Oxide for Cement Reinforcement Applications
- 2020
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Ingår i: Chemistry - A European Journal. - : Wiley. - 1521-3765 .- 0947-6539. ; 26:29, s. 6561-6568
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Tidskriftsartikel (refereegranskat)abstract
- Poor bonding strength between nanomaterials and cement composites inevitably lead to the failure of reinforcement. Herein, a novel functionalization method for the fabrication of functionalized graphene oxide (FGO), which is capable of forming highly reliable covalent bonds with cement hydration products, and therefore, suitable for use as an efficient reinforcing agent for cement composites, is discussed. The bonding strength between cement and aggregates was improved more than 21 times with the reinforcement of FGO. The fabricated FGO also demonstrated many important features, including high reliability in cement pastes, good dispersibility, and efficient structural refinement of cement hydration products. With the incorporation of FGO, cement mortar samples demonstrated up to 40 % increased early and ultimate strength. Such results make the fast demolding and manufacture of light constructions become highly possible, and show strong advantages on improving productivity, saving cost, and reducing CO2 emissions in practical applications.
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| 399. |
- Wang, Nan, et al.
(författare)
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Light-weight Compressible and Highly Thermal Conductive Graphene-based Thermal Interface Material
- 2018
-
Ingår i: 2018 7th Electronic System-Integration Technology Conference (ESTC). - 9781538668146
-
Konferensbidrag (refereegranskat)abstract
- High density packaging in combination with increased transistor integration inevitably leads to challenging power densities in terms of thermal management. Thermal interface materials (TIMs) play a key role in thermal management by transferring heat from the surface of power devices. The conventional TIMs used in the microelectronics industry today basically are particle laden polymer matrix composites, which have the advantages of good reliability and ease of use. However, the thermal conductivity (K) of these composites is generally limited to 10 W/mK, which is hard to meet the goal for efficient thermal management in power devices. Here, we solve the problem by applying a novel highly thermal conductive and compressible graphene based TIMs (GTs). Composed by vertical graphene structures, GTs provide a continuous high thermal conductivity phase along the path of thermal transport, which lead to outstanding thermal properties. By tailoring ratios of graphene in the polymer binder, bulk thermal conductivity of GTs can be varied from 50 to 1000 W/mK. This result isorders of magnitude higher than conventional TIMs, and even outperforms the pure indium TIMs by over ten times. Meanwhile, the highly flexible and foldable nature of vertical graphene enables at least 20% compressibility of the GTs upon small applied pressures (≤ 400 KPa). As excellent gap fillers, GT can provide complete physical contact between two surfaces and thereby minimize the contact resistance to heat flow. The measured minimum thermal resistance and maximum effective thermal conductivity for GTs reaches to ∼ Kmm2/W and ∼ W/mK, respectively. Such values are significantly higher than the randomly dispersed composites presented above, and show almost comparable thermal performance as pure indium bonding. In addition, the GTs has more advantages than indium/solder bonding, including low weight (density <2g/cm3), low complexity during assembly and maintainability. The resulting GTs thus opens new opportunities for addressing large heat dissipation issues both in through-plane and in-plane directions for form-factor driven electronics and other high power driven systems.
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| 400. |
- Wang, Nan, 1988, et al.
(författare)
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Reliability investigation of nano-enhanced thermal conductive adhesives
- 2012
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Ingår i: Proceedings of the IEEE Conference on Nanotechnology. - 1944-9399 .- 1944-9380. - 9781467321983
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Konferensbidrag (refereegranskat)abstract
- This paper deals with silver (Ag) coated silicon carbide nanoparticles (SiC@Ag NPs) for thermal conductive interconnect and die attach applications.
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