| 521. |
- Zhang, Yong, 1982, et al.
(författare)
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Graphene-based heater
- 2016
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Ingår i: IMAPS Nordic Annual Conference 2016; Tonsberg; Norway; 5-7 June 2016. - 9781510827226
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Konferensbidrag (refereegranskat)abstract
- The excellent thermal conductivity and optical transmittance of graphene make it tremendously interesting as a material for heating applications. In this paper, we demonstrate graphene can be used as a new heating element. The graphene is synthesized by chemical vapor deposition (CVD) on Cu foil. The heating performance is studied in terms of applied voltage, heating rate and input power density. A two-layer graphene film based heater can reach an equilibrium temperature up to 90C when 60 V voltage is applied for 2 min. A maximum heating rate of 1.1 C/s was observed under an applied voltage of 60 V. The results indicate that the graphene-based heater holds great promise for many applications such as defrosting and antifogging devices.
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| 522. |
- Zhang, Y., et al.
(författare)
-
Heat transfer analysis of phase change materials with metal foams
- 2021
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Ingår i: 2021 22nd International Conference on Electronic Packaging Technology, ICEPT 2021.
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Konferensbidrag (refereegranskat)abstract
- With the development of electronic products towards high-density integration, high performance and multifunction, the working frequencies and power consumption rate of electronic components and devices increase substantially. The resulting temperature rise has a great impact on the operation and lifetime of electronic products. Transient temperature control and efficient heat dissipation are essential to the stability and reliability of the electronic components and products. Paraffin wax, as one of the most commonly used phase change materials, has been widely applied in many products requiring transient temperature control due to its melting temperature lying in the range of electronics operation conditions. However, the applicable scopes of phase change materials were limited due to their shortcomings of low thermal conductivity and heat dissipation. In the present paper, both metal forms and carbon nanomaterials are used as thermal enhancers to increase the conduction of paraffin wax, and the heat transfer characters of the composites are investigated by numerical method. The simulation results show that the introduction of Cu or Ni foam as heat conductive enhancers can significantly increase the effective thermal conductivity of paraffin wax composite. The thermal conductivity of the composite with Ni foams is 3.684 times higher than that of the paraffin wax, and the increase is 12.485 times when Cu foam is used instead of Ni foam. Furthermore, the heat transfer of the composites can be strengthened by adding carbon nanomaterials into the paraffin wax so as to increase the thermal conductivity of the matrix. The simulation results show that the impact of dispersed carbon nanomaterials on thermal enhancement of the composites is less significant than that of metal foams.
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| 523. |
- Zhang, Yong, 1982, et al.
(författare)
-
Improved Heat Spreading Performance of Functionalized Graphene in Microelectronic Device Application
- 2015
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Ingår i: Advanced Functional Materials. - : Wiley. - 1616-3028 .- 1616-301X. ; 25:28, s. 4430-4435
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Tidskriftsartikel (refereegranskat)abstract
- It is demonstrated that a graphene-based film (GBF) functionalized with silane molecules strongly enhances thermal performance. The resistance temperature detector results show that the inclusion of silane molecules doubles the heat spreading ability. Furthermore, molecular dynamics simulations show that the thermal conductivity () of the GBF increased by 15%-56% with respect to the number density of molecules compared to that with the nonfunctionalized graphene substrate. This increase in is attributed to the enhanced in-plane heat conduction of the GBF, resulting from the simultaneous increase of the thermal resistance between the GBF and the functionalized substrate limiting cross-plane phonon scattering. Enhancement of the thermal performance by inserting silane-functionalized molecules is important for the development of next-generation electronic devices and proposed application of GBFs for thermal management.
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| 524. |
- Zhang, Yong, 1982, et al.
(författare)
-
Improved Thermal Properties of Three-Dimensional Graphene Network Filled Polymer Composites
- 2022
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Ingår i: Journal of Electronic Materials. - : Springer Science and Business Media LLC. - 1543-186X .- 0361-5235. ; 51:1, s. 420-425
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the improved thermal property of three-dimensional (3D) graphene network modified polydimethylsiloxane (PDMS) composites. It shows that with a 2 wt.% loading of graphene foams (GF), the thermal conductivity of GF/PDMS composite was successfully increased from 0.19 W/mK to 0.42 W/mK, which is 2.2 times higher than that of neat PDMS. However, if GF was transformed into graphene sheets (GS) by sonication, the thermal conductivity of GS/PDMS was decreased to 0.28 W/mK. The remarkable improvement of the thermal properties is attributed to the 3D interconnected graphene network in GF, which form continuous heat transfer networks. Furthermore, the finite element analysis was conducted to evaluate the effect of GFs in composites, where some parameters such as thickness and thermal conductivity were analyzed and discussed. Our results indicate that the continuous 3D GFs holds great potential as fillers to improve the thermal property of polymer materials.
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| 525. |
|
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| 526. |
- Zhang, Yan, et al.
(författare)
-
MDS Investigation on the Heat Transfer Properties of CNT Micro-Channel Cooler
- 2010
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Ingår i: IEEE CPMT Electronics System Integration Conference (ESTC). - 9781424485536
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- With the continuously increasing packaging density, the corresponding techniques for heat dissipation are vital to high performance components. During the system operation, the heat generated by components must be efficiently transferred outside of the electronic package. To meet the heat removal requirement of the electronic devices with a high power, several liquid cooling schemes have been suggested, among which the micro-channel cooler have gained the most attention. Simultaneously, the carbon nanotube (CNT) has attracted a significant interest in the material properties and exploratory application. Some studies have been recently conducted to evaluate the thermal performance of the CNTs and their applicability for heat removal in integrated circuit (IC) devices. By utilizing the adhesive transfer process to form the CNT bundles as the fins during the micro-channel development, the devices can be immune from the high temperature required by the CNT growth process. In the present paper, the interface heat transfer in the CNT-based micro-channel cooler has been investigated. The thermal resistances introduced by the interface between the CNT and the epoxy due to adhesive transfer and the interface between the CNT and water have been simulated by molecular dynamics simulation (MDS) method. And the thermal resistance at the interface between the CNT and the epoxy is about 1.0-1.5 × 10 -8 Km 2 /W. The obtained MDS results are likely to provide the microscopic understanding of the thermal performance of the CNT micro-channel cooler as well as provide references to the macroscopic evaluation of the thermal efficiency for the micro-channel cooler design and optimization.
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| 527. |
- Zhang, Yan, et al.
(författare)
-
MDS Investigation on the Melting and Solidification of Silver Nanoparticles
- 2018
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Ingår i: 2018 19th International Conference on Electronic Packaging Technology (ICEPT). - 9781538663868 - 9781538663868 ; , s. 5-9
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Konferensbidrag (refereegranskat)abstract
- Nano-silver pastes have been widely used in electronic packaging because of its outstanding characteristics in the electrical, thermal and mechanical aspects. The sintering process of silver nanoparticles has a great impact on the material features, performances and reliabilities. In the present paper, molecular dynamics (MD) simulations have been carried out, and the melting and solidification process of silver nanoparticles are studied. The phase transformation processes of nanoparticles were analyzed, and various temperature ranges has been considered. The relationship between the temperature and the system energy reflects the melting process, and the atom distributions at characteristic temperature points were observed. The structural development during the sintering of nanoparticles was studied, and there appears the coexistence of different structures in the crystallization.
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| 528. |
- Zhang, Y., et al.
(författare)
-
MDS study on tensile properties of defective graphene sheet
- 2021
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Ingår i: 2021 23rd European Microelectronics and Packaging Conference and Exhibition, EMPC 2021.
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Konferensbidrag (refereegranskat)abstract
- Low-dimensional materials such as graphene exhibit superior electrical, mechanical and thermal properties. However, structural defects occur during the growth or treatment process of carbon nanomaterial and greatly affect the material properties. In this paper, molecular dynamics simulation methods are used to study the effects of atomic defects in graphene sheets on the tensile strength, and the vacancy type and defect orientation are considered in the cases of graphene sheets under various mechanical loadings. The simulation results show that for the graphene sheets with structural defects, the fracture starts near the original vacancy position. The tensile strength of the graphene sheets with X1-type vacancy defects under zigzag direction is reduced by about 26.9% compared with that of the defect-free graphene sheet, while the graphene sheet with X2-type vacancy defects shows the least decrease in magnitude, which is 9.5% lower than that of the perfect graphene sheet. When stretched in the armchair direction, the tensile strength of the graphene sheet with H2 vacancy defects was greatly reduced by 27.1%, and the X1 vacancy defects shows the least influence, where tensile strength of the graphene sheets was reduced by 11.2%.
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| 529. |
- Zhang, Y., et al.
(författare)
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Molecular dynamics simulation for the bonding energy of metal-SWNT interface
- 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. 506-509
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Konferensbidrag (refereegranskat)abstract
- For this paper, we carried out molecular dynamics simulation to calculate the bonding energy of the metal-SWNT interface. Three kinds of metal, namely iron, nickel and gold, were studied. The results show that the iron-SWNT interface has the strongest bonding energy, and then nickel and gold. To confirm these results, tensile loading tests were also performed to study the breaking force of the metal-SWNT interface. The force needed to debond the metal-SWNT interface is at the order of nano-newton. The more adhesion energy the interface has, the bigger force that must be loaded to break the joint.
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| 530. |
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