| 1. |
- Liu, Johan, 1960, et al.
(författare)
-
1. Thermal Characterization of Power Devices Using Graphene-based Film
- 2014
-
Ingår i: Proceedings - Electronic Components and Technology Conference. - 0569-5503. - 9781479924073 ; , s. 459 - 463
-
Konferensbidrag (refereegranskat)abstract
- Due to its atomic structure with sp2 hybrid orbitals and unique electronic properties, graphene has an extraordinarily high thermal conductivity which has been reported to be up to 5000 W/mK. As a consequence, the use of graphene-based materials for thermal management has been subject to substantial attention during recent years in both academia and industry. In this paper, the development of a new type of graphene-based thin film for heat dissipation in power devices is presented. The surface of the developed graphene based film is primarily composed of functionalized graphene oxide, that can be bonded chemically to the device surface and thus minimize the interface thermal resistance caused by surface roughness. A very high in-plane thermal conductivity with a maximum value of 1600 W/mK was detected by laser flash machine regarding to the graphene-based films. To investigate the structure of the graphene-based films, scanning electron microscopy (SEM) and raman spectroscopy were carried out. Finally, LED demonstrators were built to illustrate the thermal performance of graphene-based film and the functional layers. IR camera recorded a 5°C lower temperature of a LED demonstrator with SHT G1000 as the binding layer instead of a commercial thermal conductive adhesive.
|
|
| 2. |
|
|
| 3. |
- Zhao, Changhong, 1984, et al.
(författare)
-
Graphene oxide based coatings on Nitinol for biomedical implant applications: Effectively promote mammalian cell growth but kill bacteria
- 2016
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 6:44, s. 38124-38134
-
Tidskriftsartikel (refereegranskat)abstract
- © The Royal Society of Chemistry 2016. An important clinical challenge is the development of implant surfaces which have good integration with the surrounding tissues and simultaneously inhibit bacterial colonization thus preventing infection. Recently, graphene oxide (GO) a derivative of graphene, has gained considerable attention in the biomedical field owing to its biocompatibility, surface functionalizability and promising antimicrobial activity. In this study gelatin-functionalized graphene oxide (GOGel) was synthesized by a simple one step modification where GO and GOGel were used to develop surface coatings on nitinol substrates. Mouse osteoblastic cell (MC3T3-E1) functions including cell attachment, proliferation and differentiation were investigated on GO-based coatings. The results indicated that MC3T3-E1 cell functions were significantly enhanced on both GO coated nitinol (GO@NiTi) and GOGel coated nitinol (GOGel@NiTi) compared with the control nitinol without coating (NiTi). Especially, the GOGel@NiTi surface exhibited the best performance for cell adhesion, proliferation and differentiation. Additionally the antimicrobial property of GO-based coatings against E. coli was studied with the evaluation of colony forming units (CFU) counting, live/dead fluorescent staining and scanning electron microscope (SEM). We found that the growth of E. coli was inhibited on GOGel@NiTi and particularly on GO@NiTi. SEM images revealed that the cell membrane of bacteria lost their integrity and live/dead fluorescent images confirmed the low live/dead ratio of E. coli after incubation on GOGel@NiTi and GO@NiTi. We conclude that GO-based coatings on NiTi combine the antimicrobial activity and improved biocompatibility and therefore present a remarkable potential in biomedical implant applications.
|
|
| 4. |
- Bao, Jie, et al.
(författare)
-
Application of two-dimensional layered hexagonal boron nitride in chip cooling
- 2016
-
Ingår i: Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and Engineering. - 1005-0930. ; 24:1, s. 210-217
-
Tidskriftsartikel (refereegranskat)abstract
- © 2016, The Editorial Board of Journal of Basic Science and Engineering. All right reserved.Research into layered hexagonal boron nitride(h-BN)has recently intensified, due to its superior physicochemical properties compared to that of a typical two-dimensional material. H-BN can be utilized in power chips as both an insulating layer as well as a heat spreader for local hotspots with high heat flux. Single layer h-BN film grown by CVD and h-BN microparticles are respectively transferred onto the surfaces of the thermal evaluation chips, where the influence of h-BN on the heat dissipation performance of the chips can be observed at different power values. The resistance-temperature curve method and infrared thermal imager are both used to measure the temperature of hotspots on the thermal evaluation chips, which can be reduced by between 3~5℃ at 1W after the transfer of h-BN. The cooling efficiency is improved and it can be found that single layer h-BN film shows better heat dissipation ability.
|
|
| 5. |
- Bao, Jie, et al.
(författare)
-
Synthesis and Applications of Two-Dimensional Hexagonal Boron Nitride in Electronics Manufacturing
- 2016
-
Ingår i: Electronic Materials Letters. - : Springer Science and Business Media LLC. - 1738-8090 .- 2093-6788. ; 12:1, s. 1-16
-
Forskningsöversikt (refereegranskat)abstract
- In similarity to graphene, two-dimensional (2D) hexagonal boron nitride (hBN) has some remarkable properties, such as mechanical robustness and high thermal conductivity. In addition, hBN has superb chemical stability and it is electrically insulating. 2D hBN has been considered a promising material for many applications in electronics, including 2D hBN based substrates, gate dielectrics for graphene transistors and interconnects, and electronic packaging insulators. This paper reviews the synthesis, transfer and fabrication of 2D hBN films, hBN based composites and hBN-based van der Waals heterostructures. In particular, this review focuses on applications in manufacturing electronic devices where the insulating and thermal properties of hBN can potentially be exploited. 2D hBN and related composite systems are emerging as new and industrially important materials, which could address many challenges in future complex electronics devices and systems.
|
|
| 6. |
- Bao, Jie, 1982, et al.
(författare)
-
Two-dimensional hexagonal boron nitride as lateral heat spreader in electrically insulating packaging
- 2016
-
Ingår i: Journal of Physics D: Applied Physics. - : IOP Publishing. - 1361-6463 .- 0022-3727. ; 49:July 2016, s. 265501-
-
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.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
- Chen, Huang, et al.
(författare)
-
A portable micro glucose sensor based on copper-based nanocomposite structure
- 2019
-
Ingår i: New Journal of Chemistry. - : Royal Society of Chemistry (RSC). - 1369-9261 .- 1144-0546. ; 43:20, s. 7806-7813
-
Tidskriftsartikel (refereegranskat)abstract
- Precisely detecting the concentration of glucose in the human body is an attractive way to prevent or treat diabetes. Portable glucose sensors with non-enzymatic catalytic materials have received great attention in recent years. Herein, a facile strategy for fabricating a high-performance electrochemical sensor is proposed. A non-enzymatic three-electrode integrated glucose sensor device based on CuO nano-coral arrays/nanoporous Cu (NCA/NPC) is designed and fabricated. The portable NCA/NPC glucose sensor device exhibits high catalytic activity for glucose. The great performance of the NCA/NPC glucose sensor device derives from the excellent conductivity of the NPC substrate and the high electrocatalytic activity of CuO nano-coral arrays. This device exhibits a high sensitivity of 1621 μA mM -1 cm -2 in the linear range of 0.0005-5.0 mM, low detection limit of 200 nM (S/N = 3), fast response time of 3 s, good anti-interference performance, excellent repeatability and considerable stability for glucose detection. This work will certainly provide an efficient structure and proper catalytic material choices for future non-enzymatic glucose sensors.
|
|
| 10. |
- Chen, S., et al.
(författare)
-
An overview of carbon nanotubes based interconnects for microelectronic packaging
- 2017
-
Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2017, Goteborg, Sweden, 18-20 June 2017. - 9781538630556 ; , s. 113-119
-
Konferensbidrag (refereegranskat)abstract
- Owing to the great demand in more functions and miniaturization in microelectronic packaging, the dimensions of interconnects has decreased extremely, which has resulted in electrical, thermal, and mechanical reliability issues. To address these issues, carbon nanotube (CNT) has been selected as a promising alternative material for the interconnects in packaging due to its large current density, high thermal conductivity, great flexibility, and low coefficient of thermal expansion (CTE). In this paper, the development of CNTs based vertical interconnects was reviewed. However, the resistivity of CNTs based interconnects was much higher than that of copper interconnects. Thus, this review focused on the resistivity of CNTs-based interconnects in different fabrication process and pointed out what improves the resistivity. In the future, CNTs-Cu nanocomposite with unique properties could be the suitable material for bumps to reduce the resistivity of CNTs based bumps further.
|
|
| 11. |
- Daon, J., et al.
(författare)
-
Chemically enhanced carbon nanotubes based Thermal Interface Materials
- 2015
-
Ingår i: THERMINIC 2015 - 21st International Workshop on Thermal Investigations of ICs and Systems 2015. - 9781467397056
-
Konferensbidrag (refereegranskat)abstract
- With progress in microelectronics the component density on a device increases drastically. As a consequence the power density reaches levels that challenge device reliability. New heat dissipation strategies are needed to efficiently drain heat. Thermal Interface Materials (TIMs) are usually used to transfer heat across interfaces, for example between a device and its packaging. Vertically Aligned Carbon Nanotubes (VACNTs) can be used to play this role. Indeed, carbon nanotubes are among the best thermal conductors (similar to 3.000 W/mK) and in the form of VACNT mats, show interesting mechanical properties. On one side, VACNTs are in contact with their growth substrate and there is a low thermal resistance. On the other side, good contact must be created between the opposite substrate and the VACNTs in order to decrease the contact thermal resistance. A thin-film deposition of an amorphous material can be used to play this role. This paper reports a chemically enhanced carbon nanotube based TIM with creation of chemical bonds between the polymer and VACNTs. We show that these covalent bonds enhance the thermal transfer from VACNTs to a copper substrate and can dramatically decrease local resistances. Implementation processes and thermal characterizations of TIMs are studied and reported.
|
|
| 12. |
- Daon, J., et al.
(författare)
-
Electrically conductive thermal interface materials based on vertically aligned carbon nanotubes mats
- 2014
-
Ingår i: IEEE 20th International Workshop on Thermal Investigation of ICs and Systems (Therminic). Greenwich, London, United Kingdom, 24-26 September 2014. - 9781479954155
-
Konferensbidrag (refereegranskat)abstract
- In power microelectronics, the trends towards miniaturization and higher performances result in higher power densities and more heat to be dissipated. In most electronic assembly, thermal interface materials (TIM) help provide a path for heat dissipation but still represent a bottleneck in the total thermal resistance of the system. VA-CNTs mats are typically grown on HR silicon substrate with Al2O3 diffusion barrier layer using Thermal CVD process. In many cases, 'die attach' thermal interface materials need to be electrically conductive and the growth of dense VA-CNT mats on an electrically conductive substrate remains a challenge. This paper presents the growth of dense VA-CNT mats on doped silicon with Al2O3 and TiN diffusion barrier layer. Processes, thermal and electrical characterization of VA-CNTs based thermal interface materials are studied and reported.
|
|
| 13. |
- Darmawan, C. C., et al.
(författare)
-
Graphene-CNT hybrid material as potential thermal solution in electronics applications
- 2017
-
Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging (NordPac). - 9781538630556 ; , s. 190-193
-
Konferensbidrag (refereegranskat)abstract
- Graphene and CNT have great potential in electronics applications. This work explored the possibility of integrating 1D CNT and 2D graphene into a 3D covalently bonded structure, i.e. a graphene-CNT hybrid material for thermal management application. The graphene-CNT hybrid material was later investigated morphologically and thermally to observe its heat dissipation capability.
|
|
| 14. |
|
|
| 15. |
- Enmark, Markus, 1991, et al.
(författare)
-
A Critical Assessment of Nano Enhanced Vapor Chamber Wick Structures for Electronics Cooling
- 2021
-
Ingår i: 2021 23rd European Microelectronics and Packaging Conference and Exhibition, EMPC 2021.
-
Konferensbidrag (refereegranskat)abstract
- The increasing need for high thermal dissipation in small electronic products puts tough requirements on effective cooling solutions. Two of the most effective passive cooling devices in electronics today are vapor chambers and heat pipes. With new advancements in materials science and nanotechnology comes the possibility to further increase cooling capacity and at the same time make devices lighter. This study is a critical assessment on recent progress in the field of nanomaterial enhanced wick structures in vapor chambers and heat pipes. In this paper, nano-enhanced wick structures are divided into five different sub-categories based on material type. Publication trends for the different types of nano-enhanced wicks are studied by plotting them on a timeline. It is found that nanostructured metal wicks is the most studied field in recent years. A plot showing wick performance in terms of superheat temperatures for given heat flux is created to be used for benchmarking of new wick structures when pool boil experiments are carried out. An attempt to find correlation between publication trends, type of wick and performance is done. On the basis of the gathered data it is deemed difficult to find a distinct correlation, this is mainly due to difficulty in comparing performance between different studies, especially when different heat fluxes are used. There is no unambiguous answer to which category of nano-enhanced wicks that should be target for future studies. Graphene coating and pure carbon nanomaterials such as aerogels and graphene foam are still relatively unexplored and believed to have great potential if they can be attached to envelope materials.
|
|
| 16. |
- Enmark, Markus, 1991, et al.
(författare)
-
Reliability Characterization of Graphene Enhanced Thermal Interface Material for Electronics Cooling Applications
- 2022
-
Ingår i: 2022 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2022.
-
Konferensbidrag (refereegranskat)abstract
- Graphene-based products are gaining popularity in thermal management applications in high performance electronics systems. The ultra-high thermal conductivity of graphene together with its relatively low density makes it a suitable material for reaching high cooling capability in lightweight applications. An example of products that are starting to enter the market is graphene enhanced thermal interface materials (TIMs). Pristine graphene enhanced TIMs are well characterized and show high thermal conductivity and low thermal interface resistance. Before these TIMs can take the next step from being a niche product to reach high volume sales on the market, it needs to be proven that they have stable performance over time when conditioned and aged according to industry reliability standards. In this work, a set of customized test rigs was designed, and graphene enhanced TIMs of three different thicknesses were tested. The TIMs were compressed by 30% and then subjected to three different industry standard reliability tests; thermal aging, temperature cycling and damp heat. The thermal resistance was measured sequentially during each test to monitor change over time. The reliability tests are still ongoing and so far the tested graphene enhanced TIMs have stable performance over time with some observable trends for the different tests. At the current test time the maximum degradation in thermal resistance is 13%, measured after 511 cycles in the thermal cycling test. The used test method is deemed promising for reliability comparison and future requirement standardization on thermal pads.
|
|
| 17. |
- Fan, X., et al.
(författare)
-
Reliability of carbon nanotube bumps for chip on glass application
- 2014
-
Ingår i: Proceedings of the 5th Electronics System-Integration Technology Conference, ESTC 2014. - 9781479940264 ; , s. Art. no. 6962753-
-
Konferensbidrag (refereegranskat)abstract
- Carbon nanotubes (CNTs) are an ideal candidate material for electronic interconnects due to their extraordinary thermal, electrical and mechanical properties. In this study, densified CNT bumps utilizing the paper-mediated controlled method were applied as the interconnection for chip on glass (COG) applications, and the silicon chip with patterned CNT bumps was then flipped and bonded onto a glass substrate using anisotropic conductive adhesive (ACA) at a bonding pressure of 127.4 Mpa, 170°C for 8 seconds. The electrical properties of the COG were evaluated with the contact resistance of each bump measured using the four-point probe method. Three different structure traces, marked as Trace A, Trace B, and Trace C, were tested, respectively. Thermal cycling (-40 to 85°C, 800 cycles) and damp heat tests (85°C/85% RH, 1000 hours) were also conducted to evaluate the reliability of the CNT-COG structure. The average contact resistance of the samples was recorded during these tests, in which there was no obvious electrical failure observed after both the thermal cycling and damp heat tests. The results of these tests indicated that the COG has good reliability and the CNT bumps have promising potential applications in COG.
|
|
| 18. |
|
|
| 19. |
- Fan, Yi, et al.
(författare)
-
A study of fluid coolant with carbon nanotube suspension for MicroChannel coolers
- 2008
-
Ingår i: 2008 International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2008; Pudong, Shanghai; China; 28 July 2008 through 31 July 2008. - 9781424427406
-
Konferensbidrag (refereegranskat)abstract
- In this work, silicon microchannel coolers were made using the Deep Ion Reactive Etching (DIRE) technique. Stable and homogeneous Carbon NanoTube (CNT) suspension was also prepared. Meanwhile, a closed-loop cooling test system was developed to investigate the heat removal of the silicon microchannel cooler with different coolants. The experimental setup included a test module, a minipump for providing controllable flow, and a fan system for cooling the circular fluid. Beside the inlet and outlet of the test module, two thermocouples and pressure gauges were set up to measure the temperature and pressure of the fluids. The heat removal of the silicon microchannel cooler using different CNT volume fraction of suspension coolant was studied. The results show that the microchannel cooler with CNT suspension as coolant could strengthen the heat removal capability of microchannel cooler. In addition to heat transfer enhancement, the microchannel cooler with CNT suspension coolant did not produce extra pressure drop in the present study.
|
|
| 20. |
|
|
| 21. |
- Fazi, Andrea, 1992, et al.
(författare)
-
Multiple growth of graphene from a pre-dissolved carbon source
- 2020
-
Ingår i: Nanotechnology. - : IOP Publishing. - 1361-6528 .- 0957-4484. ; 31:34, s. 345601-
-
Tidskriftsartikel (refereegranskat)abstract
- Mono- to few-layer graphene materials are successfully synthesized multiple times using Cu-Ni alloy as a catalyst after a single-chemical vapor deposition (CVD) process. The multiple synthesis is realized by extracting carbon source pre-dissolved in the catalyst substrate. Firstly, graphene is grown by the CVD method on Cu-Ni catalyst substrates. Secondly, the same Cu-Nicatalyst foils are annealed, in absence of any external carbon precursor, to grow graphene using the carbon atoms pre-dissolved in the catalyst during the CVD process. This annealing process is repeated to synthesize graphene successfully until carbon is exhausted in the Cu-Ni foils. After the CVD growth and each annealing growth process, the as-grown graphene is removed using a bubbling transfer method. A wide range of characterizations are performed to examine the quality of the obtained graphene material and to monitor the carbon concentration in the catalyst substrates. Results show that graphene from each annealing growth process possesses a similar quality, which confirmed the good reproducibility of the method. This technique brings great freedom to graphene growth and applications, and it could be also used for other 2D material synthesis.
|
|
| 22. |
|
|
| 23. |
- Fu, Yifeng, 1984, et al.
(författare)
-
A complete carbon-nanotube-based on-chip cooling solution with very high heat dissipation capacity
- 2012
-
Ingår i: Nanotechnology. - : IOP Publishing. - 1361-6528 .- 0957-4484. ; 23:4
-
Tidskriftsartikel (refereegranskat)abstract
- Heat dissipation is one of the factors limiting the continuous miniaturization of electronics. In the study presented in this paper, we designed an ultra-thin heat sink using carbon nanotubes (CNTs) as micro cooling fins attached directly onto a chip. A metal-enhanced CNT transfer technique was utilized to improve the interface between the CNTs and the chip surface by minimizing the thermal contact resistance and promoting the mechanical strength of the microfins. In order to optimize the geometrical design of the CNT microfin structure, multi-scale modeling was performed. A molecular dynamics simulation (MDS) was carried out to investigate the interaction between water and CNTs at the nanoscale and a finite element method (FEM) modeling was executed to analyze the fluid field and temperature distribution at the macroscale. Experimental results show that water is much more efficient than air as a cooling medium due to its three orders-of-magnitude higher heat capacity. For a hotspot with a high power density of 5000 W cm(-2), the CNT microfins can cool down its temperature by more than 40 degrees C. The large heat dissipation capacity could make this cooling solution meet the thermal management requirement of the hottest electronic systems up to date.
|
|
| 24. |
- Fu, Yifeng, 1984, et al.
(författare)
-
Application of through silicon via technology for in situ temperature monitoring on thermal interfaces
- 2010
-
Ingår i: Journal of Micromechanics and Microengineering. - : IOP Publishing. - 1361-6439 .- 0960-1317. ; 20:2, s. id 025027 (5 pp)-
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, a series of micro-machining processes have been developed to fabricate a test platform with the ability of in situ temperature monitoring on thermal interface behaviour. Through silicon vias (TSVs) with an aspect ratio up to 13 using Cu as a conductor have been applied to connect an array of platinum-based temperature sensors directly deposited on the thermal interfaces to be measured. The sensors are subsequently calibrated by an industry standard resistance temperature detector. Results show that the temperature sensors function normally in a temperature range up to 250 degrees C. This demonstrates the successful deposition of temperature-sensing materials and their good connection to the TSVs. The realization of direct precise temperature measurement on the thermal interface of this test platform enables thermal characterization with a high accuracy.
|
|
| 25. |
- Fu, Yifeng, 1984, et al.
(författare)
-
Carbon nanotube growth on different underlayers for thermal interface material application
- 2016
-
Ingår i: IMAPS Nordic Annual Conference 2016 Proceedings. - 9781510827226
-
Konferensbidrag (refereegranskat)abstract
- Thermal interface material (TIM) is a critical component in thermal management of high density packaging systems since both the reliability and lifetime of microsystems are dependent on how the heat is dissipated. Carbon nanotubes (CNTs) are promising candidate for development of TIMs due to their excellent thermal and mechanical properties. The thermal conductivity of CNTs can be up to 3000 W/mK in the longitudinal direction which acts as ideal heat transfer path. However, the huge interfacial thermal resistance between CNTs and contact surface hinders the exploitation of CNTs as TIMs. In this paper, we will focus on the growth of CNTs on various substrates and underlayers and analyze the interaction between catalyst and underlayer materials. Microscopic analysis is performed to characterize the quality of the CNT materials and monitor the diffusion of Fe particles into different barrier layers. Thermal conductivity of the CNT TIMs will be measured to examine the performance of the materials.
|
|
| 26. |
|
|
| 27. |
- Fu, Yifeng, 1984
(författare)
-
Carbon Nanotubes for Electronic Packaging: Growth, Novel Devices and 3D Networks
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Carbon nanotubes (CNTs) have shown great potential of application in electronics because of their attractive physical properties, such as high surface-to-volume ratio, high electron mobility, high Young’s modulus, high thermal conductivity, low thermal expansion coefficient, etc. However, many obstacles are yet to be removed to use CNTs as building blocks in electronic systems. This thesis is attempting to overcome some of the challenges that hinder the implementation of CNTs in electronic packaging.The first section concerns about the most essential issue in CNT application, the growth of CNTs. A new method is presented and it is capable of highly selective growth of CNTs, which is one of the main challenges in the CNT technology field. By growing CNTs on gold films using thermal chemical vapor deposition (TCVD) method, the number of CNT walls can be well controlled and statistical study shows that a selectivity of 79.4% can be achieved for double-walled CNTs.The second section presents the design and fabrication of a CNT based on-chip cooler, attempting to utilize CNTs for heat dissipation from electronic systems. A test platform with integrated heating elements and temperature sensors is designed and fabricated for this purpose. A new CNT transfer technology is developed to transplant the CNT microfins with pre-defined structures to desired positions on the test platform. Electrical and mechanical characterizations demonstrate that the CNT-substrate interface has been dramatically improved after the transfer process therefore addressed two of the most challenging tasks on integrating CNTs into electronics, i.e. decreasing the huge interfacical contact resistance and improving the weak adhesion between CNTs and substrates. A double-coated single photoresist structure for thick materials deposition is also developed to facilitate and simplify the CNT transfer process. Multi-scale modeling is performed to help design the CNT microfin structure. A molecular dynamics simulation (MDS) is carred out to investigate the interaction between water and CNTs at the nanoscale and a finite element method (FEM) modeling is executed to analyze the fluid field and temperature distribution at the macroscale. A novel packaging process using polydimethylsiloxane (PDMS) is also developed to assemble the CNT microfins, the test platform, the fluid channel and the supporting substrate into an integrated system. Cooling experiments have demonstrated the high efficiency of the CNT-based on-chip cooler.The third section describes a novel concept to grow covalently bonded three dimensional CNT networks, which is potentially applicable to facilitate thermal transportation in micro systems. A nickel nitrate dissolved polymer is electrospun into inter-connected porous nano fiber networks acting as precursor. The polymer fibers are then burned out and nickel nitrate is decomposed at high temperature into nickel oxide fibers. These fibers are subsequently reduced into pure nickel in hydrogen environment. The as-reduced nickel nano fiber network serves as catalyst to grow graphite layers on their surfaces. Ultimately, the nickel core is etched by iron chloride so that graphite tubes, i.e. CNT structures are left. Since the nickel fibers are inter-connected with each other and graphite layers can only grow on the surface, the as-grown CNT network is covalently bonded. Atomic force microscopy (AFM) based bending tests show that the Young’s modulus of the as-grown CNTs is about 〖391〗_(-172)^(+270) GPa, and the covalently bonded CNT structure can effectively distribute external loading throughout the network to improve the mechanical strength of the material.
|
|
| 28. |
|
|
| 29. |
- Fu, Yifeng, 1984, et al.
(författare)
-
Development of a test platform for thermal characterization using through-silicon-via technology
- 2009
-
Ingår i: IMAPS Nordic Annual Conference 2009; Tonsberg; Norway; 13 September 2009 through 15 September 2009. - 9781622761838 ; , s. 35-38
-
Konferensbidrag (refereegranskat)abstract
- In order to look into the heat transfer mechanism and improve the thermal performance of an electronic component, a thermal test platform has been designed and fabricated. A series of micro-machining processes have been developed to make the test platform. The Through-Silicon-Via technique using Cu as a conductor has been used to fabricate the temperature sensors in order to realize an in-situ temperature monitoring on a thermal interface. Pt-based temperature sensor array has been deposited on the chip and calibrated by an industry standard RTD. Results show that the Pt sensors work well which demonstrates the successful deposition of temperature sensing materials and good interconnection between through-hole vias and IC components. This indicates that the test platform can be used for thermal interface material characterization as well as 3D electronics reliability studies.
|
|
| 30. |
- Fu, Yifeng, 1984, et al.
(författare)
-
Graphene related materials for thermal management
- 2020
-
Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 7:1
-
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.
|
|
| 31. |
- Fu, Yifeng, 1984, et al.
(författare)
-
Post-Growth Processing of Carbon Nanotubes for Interconnect Applications - A Review
- 2016
-
Ingår i: 2016 6th Electronic System-Integration Technology Conference (Estc). - 9781509014026 ; , s. Article no 7764713-
-
Konferensbidrag (refereegranskat)abstract
- Interconnect is one of the most important functions of packaging technology. It delivers power and signals into and out of electronic systems. The performance and reliability of microsystems are dependent on the interconnect quality. This paper reviews the chip-level interconnects based on carbon nanotubes (CNTs), this includes their applications for both on-chip and off-chip interconnects. Various post-growth processing of CNTs, such as doping, densification, transfer, metallization, etc., for the improvement of their performance will be reviewed.
|
|
| 32. |
- Fu, Yifeng, 1984, et al.
(författare)
-
Selective growth of double-walled carbon nanotubes on gold films
- 2012
-
Ingår i: Materials Letters. - : Elsevier BV. - 1873-4979 .- 0167-577X. ; 72, s. 78-80
-
Tidskriftsartikel (refereegranskat)abstract
- Growth of high-quality vertical aligned carbon nanotube (CNT) structures on silicon supported gold (Au) films by thermal chemical vapor deposition (TCVD) is presented. Transmission electron microscopy (TEM) images show that the growth is highly selective. Statistical study reveals that 79.4% of the as-grown CNTs are double-walled. The CNTs synthesized on Au films are more porous than that synthesized on silicon substrates under the same conditions. Raman spectroscopy and electrical characterization performed on the as-grown double-walled CNTs (DWNTs) indicate that they are competitive with those CNTs grown on silicon substrates. Field emission tests show that closed-ended DWNTs have lower threshold field than those open-ended.
|
|
| 33. |
- Fu, Yifeng, 1984, et al.
(författare)
-
Templated Growth of Covalently Bonded Three-Dimensional Carbon Nanotube Networks Originated from Graphene
- 2012
-
Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 24:12, s. 1576-1581
-
Tidskriftsartikel (refereegranskat)abstract
- A template-assisted method that enables the growth of covalently bonded three-dimensional carbon nanotubes (CNTs) originating from graphene at a large scale is demonstrated. Atomic force microscopy-based mechanical tests show that the covalently bonded CNT structure can effectively distribute external loading throughout the network to improve the mechanical strength of the material.
|
|
| 34. |
- Fu, Yifeng, 1984, et al.
(författare)
-
Thermal Characterization of Low-Dimensional Materials by Resistance Thermometers
- 2019
-
Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 12:11
-
Forskningsöversikt (refereegranskat)abstract
- The design, fabrication, and use of a hotspot-producing and temperature-sensing resistance thermometer for evaluating the thermal properties of low-dimensional materials are described in this paper. The materials that are characterized include one-dimensional (1D) carbon nanotubes, and two-dimensional (2D) graphene and boron nitride films. The excellent thermal performance of these materials shows great potential for cooling electronic devices and systems such as in three-dimensional (3D) integrated chip-stacks, power amplifiers, and light-emitting diodes. The thermometers are designed to be serpentine-shaped platinum resistors serving both as hotspots and temperature sensors. By using these thermometers, the thermal performance of the abovementioned emerging low-dimensional materials was evaluated with high accuracy.
|
|
| 35. |
- Fu, Yifeng, 1984, et al.
(författare)
-
Thick film patterning by lift-off process using double-coated single photoresists
- 2012
-
Ingår i: Materials Letters. - : Elsevier BV. - 1873-4979 .- 0167-577X. ; 76, s. 117-119
-
Tidskriftsartikel (refereegranskat)abstract
- A novel method using lift-off process for patterning very thick materials is developed and demonstrated. Unlike conventional lift-off processes, no special lift-off resist is used in this method. Instead, only a double-coated single photoresist is needed. Demonstrations using two commercial photoresists show that good patterning morphology and obvious undercuts as high as 15 mu m are obtained for lift-off, which is very difficult to achieve by existing methods. The application and feasibility of this approach is demonstrated by a carbon nanotube transfer process. This simple and effective method offers wider option to pattern very thick materials in high quality which are in strong demands.
|
|
| 36. |
- Fu, Yifeng, 1984, et al.
(författare)
-
Ultrafast Transfer of Metal Enhanced Carbon Nanotubes at Low Temperature for Large Scale Electronics Assembly
- 2010
-
Ingår i: Advanced Materials. - : Wiley. - 0935-9648 .- 1521-4095. ; 22:44, s. 5039-5042
-
Tidskriftsartikel (refereegranskat)abstract
- An indium-assisted ultrafast carbon nanotube (CNT) transfer method with a yield rate over 90% is described. Metal-coated as-transferred CNT structures exhibit excellent electrical performance that is at least one order of magnitude better than the previously published results. Shear test results show that the adhesion between CNTs and the substrate is greatly improved and excellent flexibility is obtained after the transfer process.
|
|
| 37. |
- Gao, Zhaoli, 1986, et al.
(författare)
-
Graphene Heat Spreader for Thermal Management of Hot Spots
- 2013
-
Ingår i: Proceedings - Electronic Components and Technology Conference. - 0569-5503. - 9781479902330 ; , s. 2075-2078
-
Konferensbidrag (refereegranskat)abstract
- Monolayer graphene was fabricated using thermal chemical vapor deposition (TCVD) as heat spreaders in electronic packaging. Platinum (Pt) thermal evaluation chips were utilized to evaluate the thermal performance of the graphene heat spreaders. Temperature of hot spot driven at a heat flux of up to 430W·cm -2 was decreased by about 13 °C with the attaching of the graphene heat spreader. We demonstrate the potentials of using CMOS compatible TCVD process to make graphene as heat spreader for power dissipation needs. © 2013 IEEE.
|
|
| 38. |
- Gao, Zhaoli, et al.
(författare)
-
Graphene Heat Spreader for Thermal Management of Hot Spots in Electronic Packaging
- 2012
-
Ingår i: Proceedings of the 18th Therminic International Workshop on Thermal Investigations of ICs and Systems. - 9782355000225 ; , s. 217-220
-
Konferensbidrag (refereegranskat)abstract
- Monolayer graphene was fabricated using thermal CVD for the application of heat spreader in electronic packaging. Platinum (Pt) micro-heater embedded thermal testing chips were utilized to evaluate the thermal performance of the graphene heat spreader. The hot spot temperature was decreased by about 5 degrees C at a heat flux of up to 800W/cm2. It is possible to further improve the thermal performance of graphene heat spreader by optimizing the synthesis parameters and transfer process.
|
|
| 39. |
- Guo, Sihua, et al.
(författare)
-
Toward ultrahigh thermal conductivity graphene films
- 2023
-
Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 10:1
-
Tidskriftsartikel (refereegranskat)abstract
- With increasing demands of high-performance and functionality, electronics devices generate a great amount of heat. Thus, efficient heat dissipation is crucially needed. Owing to its extremely good thermal conductivity, graphene is an interesting candidate for this purpose. In this paper, a two-step temperature-annealing process to fabricate ultrahigh thermal conductive graphene assembled films (GFs) is proposed. The thermal conductivity of the obtained GFs was as high as 3826 +/- 47 W m(-1) K-1. Extending the time of high-temperature annealing significantly improved the thermal performance of the GF. Structural analyses confirmed that the high thermal conductivity is caused by the large grain size, defect-free stacking, and high flatness, which are beneficial for phonon transmission in the carbon lattice. The turbostratic stacking degree decreased with increasing heat treatment time. However, the increase in the grain size after long heat treatment had a more pronounced effect on the phonon transfer of the GF than that of turbostratic stacking. The developed GFs show great potential for efficient thermal management in electronics devices.
|
|
| 40. |
- han, Hao xue, et al.
(författare)
-
Enhanced Heat Spreader Based on Few-Layer Graphene Intercalated With Silane-Functionalization Molecules
- 2014
-
Ingår i: IEEE 20th International Workshop on Thermal Investigation of ICs and Systems (Therminic). Greenwich, London, United Kingdom, 24-26 September 2014. - 9781479954155 ; , s. 1-4
-
Konferensbidrag (refereegranskat)abstract
- We studied the heat-spreading enhancement of supported few-layer graphene by inserting silane-functionalization molecules between graphene sheets. We calculated the overall thermal resistance of graphene-substrate interface and the in-plane thermal conductivity of graphene sheets by equilibrium molecular dynamics simulations. We probed the spectral phonon transmission coefficient by non-equilibrium Green's function to characterize the local heat conduction through the interface. Our results show that the overal thermal resistance between the substrate graphene and the upper two-layer graphene underwent a three-fold increase by the presence of the molecules, while the local heat conduction from the hot spot to the graphene sheets through the molecules was largely intensified. Furthermore, the in-plane thermal conductivity of the few-layer graphene increased by 60% compared with the supported graphene non-bonded to the substrate through the molecules. This increase is attributed to the refrained cross-plane phonon scattering which in turn reinforces the in-plane heat conduction of the few-layer graphene. In summary, we proved that by inserting silane-functionalization molecules, the few-layer graphene becomes an ideal candidate for heat spreading by guiding heat more efficiently away from the heat source.
|
|
| 41. |
- Han, H. X., et al.
(författare)
-
Functionalization mediates heat transport in graphene nanoflakes
- 2016
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- The high thermal conductivity of graphene and few-layer graphene undergoes severe degradations through contact with the substrate. Here we show experimentally that the thermal management of a micro heater is substantially improved by introducing alternative heat-escaping channels into a graphene-based film bonded to functionalized graphene oxide through amino-silane molecules. Using a resistance temperature probe for in situ monitoring we demonstrate that the hotspot temperature was lowered by similar to 28 degrees C for a chip operating at 1,300 Wcm(-2). Thermal resistance probed by pulsed photothermal reflectance measurements demonstrated an improved thermal coupling due to functionalization on the graphene-graphene oxide interface. Three functionalization molecules manifest distinct interfacial thermal transport behaviour, corroborating our atomistic calculations in unveiling the role of molecular chain length and functional groups. Molecular dynamics simulations reveal that the functionalization constrains the cross-plane phonon scattering, which in turn enhances in-plane heat conduction of the bonded graphene film by recovering the long flexural phonon lifetime.
|
|
| 42. |
- Hansson, Josef, 1991, et al.
(författare)
-
Effects of high temperature treatment of carbon nanotube arrays on graphite : Increased crystallinity, anchoring and inter-tube bonding
- 2020
-
Ingår i: Nanotechnology. - : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 31:45
-
Tidskriftsartikel (refereegranskat)abstract
- Thermal treatment of carbon nanotubes (CNTs) can significantly improve their mechanical, electrical and thermal properties due to reduced defects and increased crystallinity. In this work we investigate the effect of annealing at 3000 degrees C of vertically aligned CNT arrays synthesized by chemical vapor deposition (CVD) on graphite. Raman measurements show a drastically reduced amount of defects and, together with transmission electron microscope (TEM) diffraction measurements, an increased average crystallite size of around 50%, which corresponds to a 124% increase in Young's modulus. We also find a tendency for CNTs to bond to each other with van der Waals (vdW) forces, which causes individual CNTs to closely align with each other. This bonding causes a densification effect on the entire CNT array, which appears at temperatures >1000 degrees C. The densification onset temperature corresponds to the thermal decomposition of oxygen containing functional groups, which otherwise prevents close enough contact for vdW bonding. Finally, the remaining CVD catalyst on the bottom of the CNT array is evaporated during annealing, enabling direct anchoring of the CNTs to the underlying graphite substrate.
|
|
| 43. |
- Hu, Zhili, 1983, et al.
(författare)
-
Detecting single molecules inside a carbon nanotube to control molecular sequences using inertia trapping phenomenon
- 2012
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 101:13, s. Art. no. 133105-
-
Tidskriftsartikel (refereegranskat)abstract
- Here we show the detection of single gas molecules inside a carbon nanotube based on the change inresonance frequency and amplitude associated with the inertia trapping phenomenon. As its directimplication, a method for controlling the sequence of small molecule is then proposed to realize theconcept of manoeuvring of matter atom by atom in one dimension. The detection as well as theimplication is demonstrated numerically with the molecular dynamics method. It is theoreticallyassessed that it is possible for a physical model to be fabricated in the very near future.
|
|
| 44. |
|
|
| 45. |
- Huang, Shirong, et al.
(författare)
-
Graphene Based Heat Spreader for High Power Chip Cooling Using Flip-chip Technology
- 2013
-
Ingår i: 2013 IEEE 15th Electronics Packaging Technology Conference (EPTC 2013). - 9781479928330 ; , s. 347-352
-
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.
|
|
| 46. |
- Huang, S., et al.
(författare)
-
Improved reliability of electrically conductive adhesives joints on Cu-Plated PCB substrate enhanced by graphene protection barrier
- 2017
-
Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2017, Goteborg, Sweden, 18-20 June 2017. - 9781538630556 ; , s. 143-146
-
Konferensbidrag (refereegranskat)abstract
- Graphene protection barrier was introduced to the interface between the ECAs and Cu-plated wire to enhance the reliability of the ECAs joints on Cu-Plated PCB substrate due to its excellent properties of impermeability to all gases/salts as well as its thermal/chemical stability. The results of shear test indicated graphene protection barrier can improve the shear strength of the ECAs joints on Cu-plated PCB substrate by almost 22% after 500 hours high temperature and high humidity cyclic test. Characterizations by optical microscope and XPS were further performed to explain the mechanism. To sum up, it can be believed that the graphene protection barrier can dramatically enhance the reliability of the ECAs joints on Cu-Plated PCB substrate.
|
|
| 47. |
- Huang, Shirong, et al.
(författare)
-
Infrared Emissivity Measurement for Vertically Aligned Multiwall Carbon Nanotubes (CNTs) Based Heat Spreader Applied in High Power Electronics Packaging
- 2016
-
Ingår i: 6th Electronic System-integration Technology Conference (ESTC 2016). - 9781509014026 ; , s. Article no 7764696-
-
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
|
|
| 48. |
- Huang, Shirong, et al.
(författare)
-
Reliability of Graphene-based Films Used for High Power Electronics Packaging
- 2015
-
Ingår i: 16th International Conference on Electronic Packaging Technology, ICEPT 2015, Changsha, China, 11-14 August 2015. - 9781467379991 ; , s. 852-855
-
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.
|
|
| 49. |
- Huang, Shirong, et al.
(författare)
-
The Effects of Graphene-Based Films as Heat Spreaders for Thermal Management in Electronic Packaging
- 2016
-
Ingår i: 2016 17th International Conference on Electronic Packaging Technology, ICEPT 2016. - 9781509013968 ; , s. Art no 7583272; Pages 889-892
-
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.
|
|
| 50. |
- Jeppson, Kjell, 1947, et al.
(författare)
-
Hotspot test structures for evaluating carbon nanotube microfin coolers and graphene-like heat spreaders
- 2016
-
Ingår i: 29th IEEE International Conference on Microelectronic Test Structures (ICMTS), Yokohama, Japan, Mar 28-31, 2016. - 1071-9032. ; 2016-May, s. 32-36
-
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).
|
|
