| 1. |
- Davies, Stuart J., et al.
(författare)
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ForestGEO: Understanding forest diversity and dynamics through a global observatory network
- 2021
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207. ; 253
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Tidskriftsartikel (refereegranskat)abstract
- ForestGEO is a network of scientists and long-term forest dynamics plots (FDPs) spanning the Earth's major forest types. ForestGEO's mission is to advance understanding of the diversity and dynamics of forests and to strengthen global capacity for forest science research. ForestGEO is unique among forest plot networks in its large-scale plot dimensions, censusing of all stems ≥1 cm in diameter, inclusion of tropical, temperate and boreal forests, and investigation of additional biotic (e.g., arthropods) and abiotic (e.g., soils) drivers, which together provide a holistic view of forest functioning. The 71 FDPs in 27 countries include approximately 7.33 million living trees and about 12,000 species, representing 20% of the world's known tree diversity. With >1300 published papers, ForestGEO researchers have made significant contributions in two fundamental areas: species coexistence and diversity, and ecosystem functioning. Specifically, defining the major biotic and abiotic controls on the distribution and coexistence of species and functional types and on variation in species' demography has led to improved understanding of how the multiple dimensions of forest diversity are structured across space and time and how this diversity relates to the processes controlling the role of forests in the Earth system. Nevertheless, knowledge gaps remain that impede our ability to predict how forest diversity and function will respond to climate change and other stressors. Meeting these global research challenges requires major advances in standardizing taxonomy of tropical species, resolving the main drivers of forest dynamics, and integrating plot-based ground and remote sensing observations to scale up estimates of forest diversity and function, coupled with improved predictive models. However, they cannot be met without greater financial commitment to sustain the long-term research of ForestGEO and other forest plot networks, greatly expanded scientific capacity across the world's forested nations, and increased collaboration and integration among research networks and disciplines addressing forest science.
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| 2. |
- Zhang, Dongsheng, et al.
(författare)
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Thermal properties of TIM using CNTs forest in electronics packaging
- 2016
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Ingår i: 2016 17th International Conference on Electronic Packaging Technology, ICEPT 2016; Wuhan Optics Valley Kingdom Hotel Wuhan; China; 16 August 2016 through 19 August 2016. ; , s. 1355-1359
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Konferensbidrag (refereegranskat)abstract
- Thermal interface material (TIM) is applied to fill the air gaps of interfaces, which provides a path for interfacial heat transfer. Owing to the exceptional thermal properties of carbon nanotubes (CNT), TIMs based on CNTs have received much attention in recent years. In this study, heat dissipation performance of vertically aligned carbon nanotubes (VACNT) arrays as TIM in electronic packing was analyzed. Vertically aligned carbon nanotubes with length of 245?m and 763?m were synthesized on a silicon substrate by chemical vapor deposition respectively. Morphology of the vertically aligned carbon nanotubes was characterized by scanning electron microscope. The hotspot temperature of thermal test chip with vertically aligned carbon nanotubes were characterized by resistance temperature detector method and infrared imaging method.
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| 3. |
- Bao, Jie, 1982, et al.
(författare)
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Two-dimensional hexagonal boron nitride as lateral heat spreader in electrically insulating packaging
- 2016
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Ingår i: Journal of Physics D: Applied Physics. - : IOP Publishing. - 1361-6463 .- 0022-3727. ; 49:July 2016, s. 265501-
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Tidskriftsartikel (refereegranskat)abstract
- The need for electrically insulating materials with a high in-plane thermal conductivity for lateral heat spreading applications in electronic devices has intensified studies of layered hexagonal boron nitride (h-BN) films. Due to its physicochemical properties, h-BN can be utilised in power dissipating devices such as an electrically insulating heat spreader material for laterally redistributing the heat from hotspots caused by locally excessive heat flux densities. In this study, two types of boron nitride based heat spreader test structures have been assembled and evaluated for heat dissipation. The test structures separately utilised a few-layer h-BN film with and without graphene enhancement drop coated onto the hotspot test structure. The influence of the h-BN heat spreader films on the temperature distribution across the surface of the hotspot test structure was studied at a range of heat flux densities through the hotspot. It was found that the graphene-enhanced h-BN film reduced the hotspot temperature by about 8–10°C at a 1000 W/cm2 heat flux density, a temperature decrease significantly larger than for h-BN film without graphene enhancement. Finite element simulations of the h-BN film predict that further improvements in heat spreading ability are possible if the thermal contact resistance between the film and test chip are minimised.
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| 4. |
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| 5. |
- Huang, Shirong, et al.
(författare)
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Graphene Based Heat Spreader for High Power Chip Cooling Using Flip-chip Technology
- 2013
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Ingår i: 2013 IEEE 15th Electronics Packaging Technology Conference (EPTC 2013). - 9781479928330 ; , s. 347-352
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Konferensbidrag (refereegranskat)abstract
- Monolayer graphene was synthesized through thermal chemical vapor deposition (TCVD) as heat spreader for chip cooling. Platinum (Pt) serpentine functioned as hot spot on the thermal testing chip. The thermal testing chip with monolayer graphene film attached was bonded using flip-chip technology. The temperature at the hot spot with a monolayer graphene film as heat spreader was decreased by about 12°C and had a more uniform temperature compared to those without graphene heat spreader when driven by a heat flux of about 640W/cm 2 . Further improvements to the cooling performance of graphene heat spreader could be made by optimizing the synthesis parameters and transfer process of graphene films. © 2013 IEEE.
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| 6. |
- Huang, Shirong, et al.
(författare)
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Infrared Emissivity Measurement for Vertically Aligned Multiwall Carbon Nanotubes (CNTs) Based Heat Spreader Applied in High Power Electronics Packaging
- 2016
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Ingår i: 6th Electronic System-integration Technology Conference (ESTC 2016). - 9781509014026 ; , s. Article no 7764696-
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Konferensbidrag (refereegranskat)abstract
- Vertically-aligned multiwall carbon nanotubes were deposited on silicon substrate by low pressure chemical vapor deposition (LPCVD), which can be utilized as heat spreaders in high power electronic packaging due to their remarkable thermal conductivity. The infrared emissivity of the vertically aligned multiwall carbon nanotubes was then characterized based on the FLIR SC600 infrared imaging system. The average infrared emissivity of the multiwall carbon nanotubes sample was about 0.92, which agrees well with experimental results reported before. Scanning electron microscopy (SEM) images of the multiwall carbon nanotubes were further analyzed to explain its high emissivity, and the reason can be attributed to the homogeneous sparseness and aligned structure of the vertically aligned multiwall carbon nanotubes
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| 7. |
- Huang, Shirong, et al.
(författare)
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Reliability of Graphene-based Films Used for High Power Electronics Packaging
- 2015
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Ingår i: 16th International Conference on Electronic Packaging Technology, ICEPT 2015, Changsha, China, 11-14 August 2015. - 9781467379991 ; , s. 852-855
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Konferensbidrag (refereegranskat)abstract
- Graphene-base film was fabricated with chemical conversion process, including graphene oxide (GO) prepared by Hummer's method, graphene oxide reduced with L-ascorbic acid (LAA), graphene based film deposited by vacuum filtration process. Meanwhile, the functionalization of the graphene-based film was performed to decrease the thermal interface resistance between the graphene-based film and substrate. Characterization data showed that the graphene-based film possessed high reliability after 500 hours under 85°C aging test. In summary, the graphene-based film can be a promising solution in thermal management of high power electronics.
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| 8. |
- Huang, Shirong, et al.
(författare)
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The Effects of Graphene-Based Films as Heat Spreaders for Thermal Management in Electronic Packaging
- 2016
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Ingår i: 2016 17th International Conference on Electronic Packaging Technology, ICEPT 2016. - 9781509013968 ; , s. Art no 7583272; Pages 889-892
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Konferensbidrag (refereegranskat)abstract
- Graphene-based films (GBF) were fabricated using a chemical conversion process including graphene oxide (GO) preparation by use of Hummer’s method, graphene oxide reduction using L-ascorbic acid (LAA), and finally film formation by vacuum filtration. GBF is considered as a candidate material for thermal management, i.e. for removing heat from hotspots in power electronic packaging, due to its high thermal conductivity. In this work, the GBF heat spreading performance in 3D TSV packaging was analysed using finite element methods (FEM) implemented in the COMSOL software. Both size effects and the influence of the thermal conductivity of the GBF heat spreader on the thermal performance of the 3D TSV package were evaluated. Furthermore, the size effects of the thermal conductive adhesive (TCA) underfill between the chip and the printed circuit board (PCB) were analysed. The results obtained are critical for proper design of graphene-based lateral heat spreaders in high power electronic packaging.
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| 9. |
- Lu, Xiuzhen, et al.
(författare)
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The influence of sintering process on thermal properties of nano-silver paste
- 2018
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Ingår i: 2018 19TH INTERNATIONAL CONFERENCE ON ELECTRONIC PACKAGING TECHNOLOGY (ICEPT). - 9781538663868 - 9781538663868 ; , s. 1157-1160
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Konferensbidrag (refereegranskat)abstract
- Nano-silver paste with low sintering temperature and high operation temperature was introduced to the application of bonding materials for GaN and SiC devices. Thermal properties are critical issues for die attach materials due to the heat dissipation requirements of high power devices. The influence of sintering process parameters for nano-silver paste on the thermal properties was investigated. The thermal conductivity of sintered nano-silver paste increased with the increase of sintering temperature and sintering time because of the dense structure due to high temperature and long sintering time. To improve the thermal property, Ag coated micro-SiC particles were used as an alternative to partly replace pure nano-Ag particles. The results demonstrate that the SiC particles can reduce the voids and improve the density of the sintered silver structure. Moreover, the addition of SiC particles can also contribute to the increase of thermal diffusivity. As a result, the thermal conductivity of sintered silver paste with 1.5 wt.% Ag coated SiC particles was two times as compared to that without SiC particles with the same Ag concentration.
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| 10. |
- Mu, Wei, 1985, et al.
(författare)
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Enhanced Cold Wall CVD Reactor Growth of Horizontally Aligned Single-walled Carbon Nanotubes
- 2016
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Ingår i: Electronic Materials Letters. - : Springer Science and Business Media LLC. - 1738-8090 .- 2093-6788. ; 12:3, s. 329-337
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Tidskriftsartikel (refereegranskat)abstract
- Synthesis of horizontally-aligned single-walled carbon nanotubes (HA-SWCNTs) by chemical vapor deposition (CVD) directly on quartz seems very promising for the fabrication of future nanoelectronic devices. In comparison to hot-wall CVD, synthesis of HA-SWCNTs in a cold-wall CVD chamber not only means shorter heating, cooling and growth periods, but also prevents contamination of the chamber. However, since most synthesis of HA-SWCNTs is performed in hot-wall reactors, adapting this well-established process to a cold-wall chamber becomes extremely crucial. Here, in order to transfer the CVD growth technology from a hot-wall to a cold-wall chamber, a systematic investigation has been conducted to determine the influence of process parameters on the HA-SWCNT’s growth. For two reasons, the cold-wall CVD chamber was upgraded with a top heater to complement the bottom substrate heater; the first reason to maintain a more uniform temperature profile during HA-SWCNTs growth, and the second reason to preheat the precursor gas flow before projecting it onto the catalyst. Our results show that the addition of a top heater had a significant effect on the synthesis. Characterization of the CNTs shows that the average density of HA-SWCNTs is around 1-2 tubes/μm with high growth quality as shown by Raman analysis.
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