| 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. |
- 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.
|
|
| 3. |
|
|
| 4. |
- Kabiri Samani, Majid, 1976, et al.
(författare)
-
Improving Thermal Transport at Carbon Hybrid Interfaces by Covalent Bonds
- 2018
-
Ingår i: Advanced Materials Interfaces. - : Wiley. - 2196-7350. ; 5:15
-
Tidskriftsartikel (refereegranskat)abstract
- Graphene and carbon nanotubes have received much attention for thermal management application due to their unique thermal performance. Theoretical work suggests that a covalent bond can combine 1D carbon nanotubes with 2D graphene together to extend the excellent thermal property to three dimensions for heat dissipation. This paper experimentally demonstrates the high heat dissipation capability of a freestanding 3D multiwall carbon nanotube (MWCNT) and graphene hybrid material. Using high-resolution transmission electron microscopy and pulsed photothermal reflection measurement method, the covalent bonds between MWCNT and planar graphene are microscopically and numerically demonstrated. Thermal resistance at the junction with covalent bonds is 9×10^−10 Kelvin square meter per watt, which is three orders of magnitude lower than van der Waals contact. Joule heating method is used to verify the extra cooling effect of this 3D hybrid material compared to graphite film. A demonstrator using high power chip is developed to demonstrate the applicability of this hybrid material in thermal application. Temperature at hot spots can be decreased by around 10°C with the assistance of this hybrid material. These findings are very significant for understanding the thermal conduction during combining 1D and 2D carbon material together for future thermal management application.
|
|
| 5. |
- 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.
|
|
| 6. |
- 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.
|
|
| 7. |
- Jiang, Di, 1983, et al.
(författare)
-
Vertically stacked carbon nanotube-based interconnects for through silicon via application
- 2015
-
Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 36:5, s. 499-501
-
Tidskriftsartikel (refereegranskat)abstract
- Stacking of silicon chips with carbon nanotube (CNT)-based through-silicon vias (TSVs) is experimentally demonstrated. Polymer filling is used to improve the transfer quality of CNTs into pre-etched silicon holes. Special hexagonal CNTs are designed to achieve high aspect ratio (10:1) CNT vias. TSVs filled with closely packed CNTs show a highly linear dc I - V response. The proposed process works at room temperature, which makes it compatible with existing device fabrication flow.
|
|
| 8. |
- Nylander, Andreas, 1988, et al.
(författare)
-
RF properties of carbon nanotube / Copper composite through silicon via based CPW structure for 3D integrated circuits
- 2019
-
Ingår i: 2019 IEEE 14th Nanotechnology Materials and Devices Conference, NMDC 2019.
-
Konferensbidrag (refereegranskat)abstract
- The development of integrated circuits (ICs) has seen exponential growth in performance over the last couple of decades and has pushed the boundaries for how we use our electronics in our daily lives. The scaling of ICs, and therefore also the performance development, is now starting to slow down when the physical designs are reaching critical dimensions where quantum effects starts to become noticeable. One proposed route to circumvent these issues for a continued scaling is based on the implementation of 3D integration by chip stacking for an increased miniaturization potential. Miniaturisation will soon also result in interconnect dimensions that surpass the mean free path (MFP) in Cu, the commonly used material for interconnects today, with a sharp increase in resistivity as a result. By changing the through silicon via (TSV) interconnect material from Cu to a carbon nanotube (CNT)/Cu composite, continued scaling can be ensured both in terms of electrical conductivity, ampacity and signal delays. Furthermore, a reduced skin effect can be achieved ensuring lower signal losses at higher RF frequencies making the CNT/Cu composite an ideal candidate to replace tranditional Cu interconnects. In this paper, we are demonstrating a coplanar waveguide (CPW) test structure using CNT/Cu filled TSVs connected to Au transmission lines on SiO2-passivated high resistivity Si substrates. The parasitic losses of the CNT/Cu TSV based CPW test structure were measured using a Sparameters test setup. The results showed that the CNT/Cu TSVs with affiliated contacts increased the signal losses up to S21 = -5.5 dB compared to Au reference transmission lines. These results are in line with previous results using CNT based TSVs and will serve as a basis for future improvements of CNT based interconnect technology for 3D integration.
|
|
| 9. |
- Sun, Shuangxi, 1986, et al.
(författare)
-
Cooling hot spots by hexagonal boron nitride heat spreaders
- 2015
-
Ingår i: Proceedings - Electronic Components and Technology Conference. - 0569-5503. - 9781479986095 ; http://www.grapchina.com/Fhzt/view/id/96.html
-
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.
|
|
| 10. |
- Nylander, Andreas, 1988, et al.
(författare)
-
Reliability investigation of a carbon nanotube array thermal interface material
- 2019
-
Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 12:11
-
Tidskriftsartikel (refereegranskat)abstract
- As feature density increases within microelectronics, so does the dissipated power density, which puts an increased demand on thermal management. Thermal interface materials (TIMs) are used at the interface between contacting surfaces to reduce the thermal resistance, and is a critical component within many electronics systems. Arrays of carbon nanotubes (CNTs) have gained significant interest for application as TIMs, due to the high thermal conductivity, no internal thermal contact resistances and an excellent conformability. While studies show excellent thermal performance, there has to date been no investigation into the reliability of CNT array TIMs. In this study, CNT array TIMs bonded with polymer to close a Si-Cu interface were subjected to thermal cycling. Thermal interface resistance measurements showed a large degradation of the thermal performance of the interface within the first 100 cycles. More detailed thermal investigation of the interface components showed that the connection between CNTs and catalyst substrate degrades during thermal cycling even in the absence of thermal expansion mismatch, and the nature of this degradation was further analyzed using X-ray photoelectron spectroscopy. This study indicates that the reliability will be an important consideration for further development and commercialization of CNT array TIMs.
|
|
