| 1. |
- Zhang, Yong, 1982, et al.
(författare)
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2D HEAT DISSIPATION MATERIALS FOR MICROELECTRONICS COOLING APPLICATIONS
- 2016
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Ingår i: China Semiconductor Technology International Conference 2016, CSTIC 2016. - 9781467388047
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Konferensbidrag (refereegranskat)abstract
- The need for faster and smaller, as well as more reliable and efficient consumer electronic products has resulted in microelectronic components that produce progressively more heat. The resultant reliability issues from the increased heat flux are serious and hinder technological development. One solution for microelectronics cooling applications is 2D materials applied as heat spreaders and these include monolayer graphene, graphene based films, and monolayer hexagonal boron nitride and BN based films. In addition, thermal performances of the graphene heat spreader were also studied under different packaging structures, including wire bonding, cooling fins and flip chips. Finally, 2D hexagonal Boron nitride (h-BN) heat spreaders, fabricated by different methods, had their heat dissipation performances characterized by different thermal characterization methods, such as resistance temperature detector (RTD) and Infrared (IR) methods. In conclusion, these new novel 2D materials developed show great potential for microelectronics cooling applications.
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| 2. |
- Zhang, Yong, 1982, et al.
(författare)
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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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| 3. |
- Zhang, Yong, 1982, et al.
(författare)
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Properties of Undoped Few-Layer Graphene-Based Transparent Heaters
- 2020
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- In many applications like sensors, displays, and defoggers, there is a need for transparent and efficient heater elements produced at low cost. For this reason, we evaluated the performance of graphene-based heaters with from one to five layers of graphene on flexible and transparent polyethylene terephthalate (PET) substrates in terms of their electrothermal properties like heating/cooling rates and steady-state temperatures as a function of the input power density. We found that the heating/cooling rates followed an exponential time dependence with a time constant of just below 6 s for monolayer heaters. From the relationship between the steady-state temperatures and the input power density, a convective heat-transfer coefficient of 60 W·m−2·°C−1 was found, indicating a performance much better than that of many other types of heaters like metal thin-film-based heaters and carbon nanotube-based heaters.
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| 4. |
- 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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| 5. |
- Edwards, Michael, 1986, et al.
(författare)
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Finite element simulation of 2D-based materials as heat spreaders
- 2016
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Ingår i: IMAPS Nordic Annual Conference 2016 Proceedings. - 9781510827226
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Konferensbidrag (refereegranskat)abstract
- Since the discovery of graphene, the first discovered 2D material, by Novoselov and Geim in 2004, the field of 2D materials has taken off and about 20 further 2D materials have been found. One of the most promising of these materials for the passive cooling of chips is hBN. HBN has the very unusual combination of being electrically insulating and thermally conductive, which potentially makes it an ideal material for both laterally spreading heat and passivating hotspots on chips. This gives hBN an advantage over graphene, where the chip requires a SiO2 passivation layer to prevent short circuits. To help evaluate the performance of these heat spreading films, a finite element model has been devised to support the experimental work undertaken in various publications. This model has been validated with experimental data and suggests that both graphene-And hBN-based materials have significant potential in lateral heat spreading applications.
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| 6. |
- Jeppson, Kjell, 1947, et al.
(författare)
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Hotspot test structures for evaluating carbon nanotube microfin coolers and graphene-like heat spreaders
- 2016
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Ingår i: 29th IEEE International Conference on Microelectronic Test Structures (ICMTS), Yokohama, Japan, Mar 28-31, 2016. - 1071-9032. ; , s. 32-36
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Konferensbidrag (refereegranskat)abstract
- The design, fabrication, and use of a hotspot-producing and temperature-sensing test structure for evaluating the thermal properties of carbon nanotubes, graphene and boron nitride for cooling of electronic devices in applications like 3D integrated chip-stacks, power amplifiers and light-emitting diodes is described. The test structure is a simple meander-shaped metal resistor serving both as the hotspot and the temperature thermo-meter. By use of this test structure, the influence of emerging materials like those mentioned above on the temperature of the hotspot has been evaluated with good accuracy).
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| 7. |
- Mu, Wei, 1985, et al.
(författare)
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Tape-Assisted Transfer of Carbon Nanotube Bundles for Through-Silicon-Via Applications
- 2015
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Ingår i: Journal of Electronic Materials. - : Springer Science and Business Media LLC. - 1543-186X .- 0361-5235. ; 44:8, s. 2898-2907
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Tidskriftsartikel (refereegranskat)abstract
- Robust methods for transferring vertically aligned carbon nanotube (CNT) bundles into through-silicon vias (TSVs) are needed since CNT growth is not compatible with complementary metal–oxide–semiconductor (CMOS) technology due to the temperature needed for growing high-quality CNTs (∼700°C). Previous methods are either too complicated or not robust enough, thereby offering too low yields. Here, a facile transfer method using tape at room temperature is proposed and experimentally demonstrated. Three different kinds of tape, viz. thermal release tape, Teflon tape, and Scotch tape, were applied as the medium for CNT transfer. The CNT bundle was adhered to the tape through a flip-chip bonder, and the influence of the bonding process on the transfer results was investigated. Two-inch wafer-scale transfer of CNT bundles was realized with yields up to 97% demonstrated. After transfer, the use of several different polymers was explored for filling the gap between the transferred CNT bundle and the sidewalls of the TSV openings to improve the filling performance. The current–voltage characteristic of the CNT TSVs indicated good electrical performance, and by measuring the via resistance as a function of via thickness, contact resistances could be eliminated and an intrinsic CNT resistivity of 1.80 mΩ cm found.
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| 8. |
- Sun, Shuangxi, 1986, et al.
(författare)
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Cooling hot spots by hexagonal boron nitride heat spreaders
- 2015
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Ingår i: Proceedings - Electronic Components and Technology Conference. - 0569-5503. - 9781479986095 ; http://www.grapchina.com/Fhzt/view/id/96.html
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Konferensbidrag (refereegranskat)abstract
- As the electronic systems become smaller and faster, a thinner and higher-efficiency heat spreader is demanded to meet the thermal dissipation requirement. In this work, we proposed a layered hBN film based heat spreader to dissipate the thermal energy generated by hot spots on high power chips. The liquid phase exfoliation method was employed to synthesize hBN flakes. Different layers of hBN film were characterized using SEM, TEM and Raman spectroscopy. Afterwards, the films were directly attached onto the target power chips. The power chips were integrated with temperature sensor and hot spot in order to analyze the thermal performance of the hBN heat spreader. IR Camera was used to capture the heat spreading effect of the hBN heat spreader and monitor the temperature distribution around the hot spot. The temperature at the hot spot driven by a heat flux of around 600W/cm2 was decreased by about 20% compared to the sample without the BN film. The potential of using hBN heat spreader for cooling hot spots was demonstrated in this work.
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| 9. |
- Zhang, Yong, 1982, et al.
(författare)
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Characterization and simulation of liquid phase exfoliated graphene-based films for heat spreading applications
- 2016
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Ingår i: Carbon. - : Elsevier BV. - 0008-6223. ; 106, s. 195-201
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Tidskriftsartikel (refereegranskat)abstract
- This paper concerns the thermal properties of graphene-based films for heat spreading applications. Following liquid phase exfoliation (LPE) films were made by two different methods, vacuum filtration and drop coating. Temperature decreases of up to 6 °C and 4 °C were measured at a heat flux density of 1200 W/cm2 for the vacuum filtrated and drop coated films respectively. For the first time in this paper, three different methods were combined to evaluate and predict the thermal performance of such graphene-based films. Resistance thermometers were used to monitor the hotspot temperature decrease versus the Joule heat flow as a result of using graphene-based heat spreaders. The 3ω method was used to experimentally determine the in-plane and through-plane thermal conductivities of such films. A finite element model of the hotspot test structure was setup using the in-plane and through-plane thermal conductivities (110 and 0.25 W/mK, respectively) obtained from the 3ω measurements. Simulations were performed to predict the hotspot temperature decrease with excellent agreement obtained between all methods. The results indicate that the alignment and purity of the graphene-based films, as well as their thermal boundary resistance with respect to the chip, are key parameters when determining the thermal performance of graphene-based heat spreaders.
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| 10. |
- Zhang, Yong, 1982, et al.
(författare)
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Chemical vapor deposition grown graphene on Cu-Pt alloys
- 2017
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Ingår i: Materials Letters. - : Elsevier BV. - 1873-4979 .- 0167-577X. ; 193, s. 255-258
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, the results from a series of experiments where graphene was grown on copper-platinum (Cu-Pt) alloy foils by chemical vapor deposition (CVD) are presented. By using Raman spectroscopy to analyze graphene films grown on Pt-Cu alloy foils with different Cu/Pt weight ratios (75/25, 50/50 and 25/75), we could show how the Cu/Pt weight ratio affected both the quality and the number of layers in the as-synthesized graphene films. Furthermore, graphene growth was shown to occur at temperatures as low as 750 °C due to what we believe is the strong catalytic ability of the Cu-Pt alloy foils. By keeping the flow rate of the CH4 precursor gas as low as 1.5 sccm, a low growth rate was obtained where the growth rates of monolayer and bilayer graphene could be controlled by simply adjusting the growth time.
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