| 1. |
- Chen, Shujing, et al.
(författare)
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Manufacturing Graphene-Encapsulated Copper Particles by Chemical Vapor Deposition in a Cold Wall Reactor
- 2019
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Ingår i: ChemistryOpen. - : Wiley. - 2191-1363. ; 8:1, s. 58-63
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Tidskriftsartikel (refereegranskat)abstract
- Functional fillers, such as Ag, are commonly employed for effectively improving the thermal or electrical conductivity in polymer composites. However, a disadvantage of such a strategy is that the cost and performance cannot be balanced simultaneously. Therefore, the drive to find a material with both a cost efficient fabrication process and excellent performance attracts intense research interest. In this work, inspired by the core-shell structure, we developed a facile manufacturing method to prepare graphene-encapsulated Cu nanoparticles (GCPs) through utilizing an improved chemical vapor deposition (CVD) system with a cold wall reactor. The obtained GCPs could retain their spherical shape and exhibited an outstanding thermal stability up to 179 degrees C. Owing to the superior thermal conductivity of graphene and excellent oxidation resistance of GCPs, the produced GCPs are practically used in a thermally conductive adhesive (TCA), which commonly consists of Ag as the functional filler. Measurement shows a substantial 74.6 % improvement by partial replacement of Ag with GCPs.
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| 2. |
- Fu, Yifeng, 1984, et al.
(författare)
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Graphene related materials for thermal management
- 2020
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Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Almost 15 years have gone ever since the discovery of graphene as a single atom layer. Numerous papers have been published to demonstrate its high electron mobility, excellent thermal and mechanical as well as optical properties. We have recently seen more and more applications towards using graphene in commercial products. This paper is an attempt to review and summarize the current status of the research of the thermal properties of graphene and other 2D based materials including the manufacturing and characterization techniques and their applications, especially in electronics and power modules. It is obvious from the review that graphene has penetrated the market and gets more and more applications in commercial electronics thermal management context. In the paper, we also made a critical analysis of how mature the manufacturing processes are; what are the accuracies and challenges with the various characterization techniques and what are the remaining questions and issues left before we see further more applications in this exciting and fascinating field.
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| 3. |
- Liu, Hao, et al.
(författare)
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Thermally Conductive Graphene Film/Indium/Aluminum Laminated Composite by Vacuum Assisted Hot-pressing
- 2020
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Ingår i: 2020 21ST INTERNATIONAL CONFERENCE ON ELECTRONIC PACKAGING TECHNOLOGY (ICEPT). - 9781728168265
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Konferensbidrag (refereegranskat)abstract
- In order to meet the ever more demanding requirements of modern thermal management with the increasing high power density, an easy-fabricated laminated graphene film/indium/aluminum (GF/In/Al) composite was developed. The GF was fabricated through assemble graphene oxide (GO) sheets in a layer-by-layer structure and then subjected to graphitization process at high temperature as well as press forming process. The fabricated GF exhibits ultrahigh in-plane thermal conductivity together with good tensile strength. The GF/In/Al laminated composite was fabricated by hot-pressing indium coated GF and Al layers in vacuum environment. The indium layer was easily coated onto the GF due to its low melting point along with good flowing property. The thermal resistance measurements show that the indium bonding possess greater preponderance of reducing contact resistance than without bonding material and thermal conductive adhesive (TCA) bonding, because indium layer could fill the gap between GF and Al layers, and provide more stable connection. The results show that the obtained laminated composite could be potentially used in the thermal management of high power systems.
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| 4. |
- Liu, Ya, 1991, et al.
(författare)
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Effect of Boron Nitride Particle Geometry on the Thermal Conductivity of a Boron Nitride Enhanced Polymer Composite Film
- 2019
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Ingår i: THERMINIC 2019 - 2019 25th International Workshop Thermal Investigations of ICs and Systems.
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Konferensbidrag (refereegranskat)abstract
- Hexagonal Boron Nitride (h-BN) has been considered as a promising enhancement filler for thermal management due to its high thermal conductivity, structural stability, and super electrical resistivity. Numerus studies have reported using BN as an enhancement filler to achieve high thermally conductive polymer based thermal management materials. However, there are limited data regarding the influence of the flake size of BN sheets to the thermal management property of BN filled composites. In this work, three h-BN size geometries, including microscale h-BN powder, h-BN nanosheets, and a mixture of micro and nanoscale h-BN, were studied regarding its thermal transfer performance. The results show that h-BN nanosheets are able to achieve the highest in-plane thermal conductivity with loading from 0 - 5 wt% while for the through-plane thermal conductivity, all three geometries show similar thermal property when the filler loading less than 5 wt%. Through-plane thermal conductivity exhibits a sudden increase to 5.69 W m-1 K-1 at a loading of 5 wt%..
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| 5. |
- Liu, Ya, 1991, et al.
(författare)
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Graphene based thermal management system for battery cooling in electric vehicles
- 2020
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Ingår i: Proceedings - 2020 IEEE 8th Electronics System-Integration Technology Conference, ESTC 2020.
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Konferensbidrag (refereegranskat)abstract
- In this work, a graphene assembled film integrated heat sink and water cooling technology was used to build an experimental set-up of a thermal management system to demonstrate the possibility to achieve efficient cooling of the propulsion battery in electric vehicles. The experimental results showed that the temperature decrease of a Li-ion battery module can reach 11°C and 9 °C under discharge rates as of 2C and 1C, respectively. The calculated thermal resistance of the graphene based cooling system is about 76% of a similar copper based cooling system. Surface modification was carried out on the graphene sheet to achieve a reliable bonding between the graphene sheet and the battery cell surface. This work provides a proof of concept of a new highly efficient approach for electric vehicle battery thermal management using the light-weight material graphene.
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| 6. |
- Liu, Ya, 1991, et al.
(författare)
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Surface modification of graphene for use as a structural Fortifier in water-borne epoxy coatings
- 2019
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Ingår i: Coatings. - : MDPI AG. - 2079-6412. ; 9:11
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Tidskriftsartikel (refereegranskat)abstract
- Graphene, the typical two-dimensional sp2 hybridized carbon allotrope, is widely used as a filler for improving the mechanical performance of polymers. However, its superhydrophobic surface makes it a big challenge to obtain stable graphene dispersions, especially in water-borne systems. On the contrary, graphene oxide (GO) shows excellent dispersibility in water, but strong oxidants and acids destroy its structure and degrade its mechanical properties. This largely limits its application in water-borne coatings. In this work, graphene from mechanical exfoliation was surface modified by p-aminophenol derived diazonium salt to achieve a homogenous dispersion. Moreover, the hydroxyl groups in p-aminophenol are able to combine with epoxy resins during the curing process to improve mechanical performance of the final coatings. The result shows that functionalized graphene shows a lower coefficient of friction and better abrasion resistance compared to GO.
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| 7. |
- Liu, Ya, 1991, et al.
(författare)
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Thermally Conductive and Electrically Insulating PVP/Boron Nitride Composite Films for Heat Spreader
- 2019
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Ingår i: Proceedings - 2019 IMAPS Nordic Conference on Microelectronics Packaging, NORDPAC 2019. ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- Thermally conductive materials with electrically insulating properties have been extensively investigated for thermal management of electronic devices. The combined properties of high thermal conductivity, structural stability, corrosion resistance and electric resistivity make hexagonal boron nitride (h-BN) a promising candidate for this purpose. Theoretical studies have revealed that h-BN has a high in-plane thermal conductivity up to 400-800 W m-1 K-1 at room temperature. However, it is still a big challenge to achieve high thermally conductive h-BN thick films that are commercially feasible due to its poor mechanical properties. On the other hand, many polymers exhibit advantages for flexibility. Thus, combining the merits of polymer and the high thermal conductivity of h-BN particles is considered as a promising solution for this issue. In this work, orientated PVP/h-BN films were prepared by electrospinning and a subsequent mechanical pressing process. With the optimized h-BN loading, a PVP/h-BN composite film with up to 22 W m-1 K-1 and 0.485 W m-1 K-1 for in-plane and through-plane thermal conductivity can be achieved, respectively. We believe this work can help accelerate the development of h-BN for thermal management applications.
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| 8. |
- Liu, Ya, 1991, et al.
(författare)
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Thermally Conductive and Electrically Insulating PVP/Boron Nitride Composite Films for Heat Spreader
- 2019
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Ingår i: Advancing Microelectronics. - 2222-8748. ; 2019:NOR, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- Thermally conductive materials with electrically insulating properties have been extensively investigated for thermal management of electronic devices. The combined properties of high thermal conductivity, structural stability, corrosion resistance and electric resistivity make hexagonal boron nitride (h-BN) a promising candidate for this purpose. Theoretical studies have revealed that h-BN has a high in-plane thermal conductivity up to 400 - 800 W m−1 K−1 at room temperature. However, it is still a big challenge to achieve high thermally conductive h-BN thick films that are commercially feasible due to its poor mechanical properties. On the other hand, many polymers exhibit advantages for flexibility. Thus, combining the merits of polymer and the high thermal conductivity of h-BN particles is considered as a promising solution for this issue. In this work, orientated PVP/h-BN films were prepared by electrospinning and a subsequent mechanical pressing process. With the optimized h-BN loading, a PVP/h-BN composite film with up to 22 W m-1 K-1 and 0.485 W m-1 K-1 for in-plane and through-plane thermal conductivity can be achieved, respectively. We believe this work can help accelerate the development of h-BN for thermal management applications.
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| 9. |
- 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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| 10. |
- Wang, Nan, et al.
(författare)
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Highly Thermal Conductive and Light -weight Craphene-based Heatsink
- 2019
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Ingår i: 2019 22ND EUROPEAN MICROELECTRONICS AND PACKAGING CONFERENCE & EXHIBITION (EMPC). - 2165-2341. - 9780956808660
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Konferensbidrag (refereegranskat)abstract
- With the developing trend ofminiaturization and integration of modem electronic devices, commercial hearsinks ivaterigh, like copper and ii iv are facing mare and mare challenges, such as inefficient cooling performance, large size turd heavy weight. Here, we salve the probletn by developing a novel highly thermal conductive and 11Mo-weight graphene heatsink. Cornposed by vertically-aligned and continUOUS graphene structures, heat transport was highly efficiero from the base 1o fin Ii: ininside the heatsink, The maximum through-platre thermal catuluctivity ofgraphene heatsink can be up to 1000 1500 Ward( which is over 7 times higher than aluminum, and even outperforms copper about 4 times_ Gmphene heatsink demonstrated outstanding cooling perffrmance which wm superior to copper heatsink with the same dimension and same power input. Noticeably, the graphene hearsink also has anportant advantagas of light-weight and high emissions,. The measured density (1 1 g cmli is only onroeighth of copper and lam than hoor of aluminum and emissivity is about ten times hiher than pure rapper and aluminum. The resulting graphene heatsink thus opertS rim opportunities for addressing large heat dissMatMn issues in weight' driven electronics and othm high power smions.
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