| 51. |
- Jeong, Seung Hee, et al.
(author)
-
Thermal Elastomer Composites for Soft Transducers
- 2015
-
In: 2015 Transducers - 2015 18th International Conference on Solid-State Sensors, Actuators and Microsystems, TRANSDUCERS 2015. - : IEEE conference proceedings. - 9781479989553 ; , s. 1873-1876
-
Conference paper (peer-reviewed)abstract
- There is a need for thermal elastomer composites (TEC) which are stretchable, electrically insulating and easily processablefor soft and stretchable sensor or actuator systems as a thermal conductor or heat spreader at an interface or in a package.A novel TEC was made by embedding a gallium based liquid alloy (Galinstan) as a droplet in polydimethylsiloxane (PDMS,Elastosil RT 601) matrix with a high speed mechanical mixing process.
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| 52. |
- Jeppson, Kjell, 1947, et al.
(author)
-
Hotspot test structures for evaluating carbon nanotube microfin coolers and graphene-like heat spreaders
- 2016
-
In: 29th IEEE International Conference on Microelectronic Test Structures (ICMTS), Yokohama, Japan, Mar 28-31, 2016. - 1071-9032. ; 2016-May, s. 32-36
-
Conference paper (peer-reviewed)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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| 53. |
- Jiang, Di, 1983, et al.
(author)
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A flexible and stackable 3D interconnect system using growth-engineered carbon nanotube scaffolds
- 2017
-
In: Flexible and Printed Electronics. - : IOP Publishing. - 2058-8585. ; 2:2
-
Journal article (peer-reviewed)abstract
- One of the critical challenges for realizing flexible electronic systems for a wide range of applications is the development of materials for flexible and stackable interconnects. We propose and demonstrate a three-dimensional (3D)interconnect structure embedded in a polymeric substrate using metal-coated carbon nanotube (CNT)scaffolds. By using two different underlayer materials for the catalyst, onestep synthesis of a dual-height CNT interconnect scaffold was realized. The CNT scaffolds serve as flexible cores for both annular metal through-substrate-vias and for horizontal metal interconnect. The 3D-CNT network was fabricated on a silicon substrate, and once the scaffolds were covered by metal, they were embedded in a polymer serving as a flexible substrate after peel-off from the silicon substrate. The 3D-CNT interconnect network was exposed to mechanical bending and stretching tests while monitoring its electrical properties. Even after 300 cycles no significant increase of resistances was found. Electrically there is a trade-off between flexibility and conductivity due to the surface roughness of the scaffold. However, this is to some extent alleviated by the metalized sidewalls giving the horizontal wires a cross-sectional area larger than indicated by their footprint. For gold wires 200 nm thick, measurements indicated a resistivity of 18 μΩ.cm, a value less than one order of magnitude larger than that of bulk gold, and a value that is expected to improve as technology improves. The mechanical properties of the metalized scaffolds were simulated using a finite element model. The potential scale-up capability of the proposed 3D-CNT network was demonstrated by the stacking of two such polymer-embedded interconnect systems.
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| 54. |
- Jiang, Di, 1983, et al.
(author)
-
Embedded Fin-Like Metal/CNT Hybrid Structures for Flexible and Transparent Conductors
- 2016
-
In: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 12:11, s. 1521-1526
-
Journal article (peer-reviewed)abstract
- In this paper, an embedded fin-like metal-coated carbon nanotube (Fin-M/CNT) structure is demonstrated for flexible and transparent conductor wire applications. Embedded in a polydimethylsiloxane polymeric substrate, Fin-M/CNT wires with a minimum width of 5 μm and a minimum pitch of 10 μm have been achieved. Direct current resistances of single Fin-M/CNT wires, where the supporting CNT structures have been covered by Ti/Al/Au metal coatings of different thicknesses, have been measured. The high aspect ratio of the fin-like structures not only improves the adhesion between the wires and the polymeric substrate, but also yields a low resistance at a small surface footprint. In addition, transparent Fin-M/CNT grid lines with hexagonal patterns, with a sheet resistance of as low as 45 Ω sq−1, have been achieved at an optical transmittance of 88%. The robustness of the Fin-M/CNT structures has been demonstrated in bending tests up to 500 cycles and no significant changes in wire resistances are observed.
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| 55. |
- Jiang, Di, 1983, et al.
(author)
-
Vertically stacked carbon nanotube-based interconnects for through silicon via application
- 2015
-
In: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 36:5, s. 499-501
-
Journal article (peer-reviewed)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.
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| 56. |
- Kabiri Samani, Majid, 1976, et al.
(author)
-
Improving Thermal Transport at Carbon Hybrid Interfaces by Covalent Bonds
- 2018
-
In: Advanced Materials Interfaces. - : Wiley. - 2196-7350. ; 5:15
-
Journal article (peer-reviewed)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.
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| 57. |
- Kabiri Samani, Majid, 1976, et al.
(author)
-
Thermal conductivity enhancement of carbon@ carbon nanotube arrays and bonded carbon nanotube network
- 2019
-
In: Materials Research Express. - : IOP Publishing. - 2053-1591. ; 6:8
-
Journal article (peer-reviewed)abstract
- Carbon nanotubes (CNTs) are long considered as a promising material for thermal applications. However, problems such as low volume CNT fraction abhorrent to practical applications have been raising the demand for novel architecture of this material. Here we demonstrate two fabrication methods, in which a self-assembly method for fabricating covalent-bonded CNT network (3D CNT) and another method for covalent-bonded C to CNTs (C@CNT) network, and presented both as a potential method to enhance thermal conductivity of CNT arrays. We utilized pulsed photothermal reflectance technique and using new four-layer heat conduction model based on the transmission-line theory to measure thermal conductivity of the samples. The 3D CNT with thermal conductivity of 21 W mK(-1) and C@CNT with thermal conductivity of 26 W mK(-1) turn out to be an excellent candidate for thermal interface material as the thermal conductivity increased by 40% and 70% respectively as compared to conventional CNT arrays. The improvement is attributed to the efficient thermal routines constructed between CNTs and secondary CNTs in 3D CNT and between C layer and CNTs in C@CNT. The other factor to improve thermal conductivity of the samples is decreasing air volume fraction in CNT arrays. Our fabrication methods provide a simple method but effective way to fabricate 3D CNT and C@CNT and extend the possibility of CNTs towards TIM application.
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| 58. |
- Kabiri Samani, Majid, 1976, et al.
(author)
-
Thermal conductivity measurement of densified carbon nanotube bundles by pulsed photothermal reflectance technique
- 2016
-
In: IMAPS Nordic Annual Conference 2016 Proceedings. - 9781510827226
-
Conference paper (peer-reviewed)abstract
- Carbon nanotubes (CNTs) were proposed as a promising interconnection material in future miniaturized electronics, owing to their exceptional electrical and thermal properties. A series of CNT bundles with 1 mm diameter were grown on silicon substrate by thermal Chemical Vapor Deposition (CVD) at temperature 700 oC. The as grown CNT bundles were densified by a vapor densification method. SEM analysis shows that the vapor densification is densified the CNT forests, which reduces the air volume fraction to increase thermal conductivity of the CNT bundles. The pulsed photothermal reflectance technique is applied to measure thermal conductivity of the CNT bundle before and after densification and the results show the thermal conductivity of densified CNT bundles increases and capability of making CNT filled through silicon via with better thermal and electrical performance.
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| 59. |
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| 60. |
- Li, Haohao, et al.
(author)
-
Atomic Layer Deposition of Buffer Layers for the Growth of Vertically Aligned Carbon Nanotube Arrays
- 2019
-
In: Nanoscale Research Letters. - : Springer Science and Business Media LLC. - 1556-276X .- 1931-7573. ; 14
-
Journal article (peer-reviewed)abstract
- Vertically aligned carbon nanotube arrays (VACNTs) show a great potential for various applications, such as thermal interface materials (TIMs). Besides the thermally oxidized SiO 2 , atomic layer deposition (ALD) was also used to synthesize oxide buffer layers before the deposition of the catalyst, such as Al 2 O 3 , TiO 2 , and ZnO. The growth of VACNTs was found to be largely dependent on different oxide buffer layers, which generally prevented the diffusion of the catalyst into the substrate. Among them, the thickest and densest VACNTs could be achieved on Al 2 O 3 , and carbon nanotubes were mostly triple-walled. Besides, the deposition temperature was critical to the growth of VACNTs on Al 2 O 3 , and their growth rate obviously reduced above 650 °C, which might be related to the Ostwald ripening of the catalyst nanoparticles or subsurface diffusion of the catalyst. Furthermore, the VACNTs/graphene composite film was prepared as the thermal interface material. The VACNTs and graphene were proved to be the effective vertical and transverse heat transfer pathways in it, respectively.
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