| 1. |
- Bao, Jie, et al.
(författare)
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Measurement of Dielectric Properties of Ultrafine BaTiO3 Using an Organic-Inorganic Composite Method
- 2015
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Ingår i: Journal of Electronic Materials. - : Springer Science and Business Media LLC. - 1543-186X .- 0361-5235. ; 44:7, s. 2300-2307
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Tidskriftsartikel (refereegranskat)abstract
- Ultrafine BaTiO3, unlike traditional ferroelectric materials, demonstrates some interesting dielectric properties, such as a gradual transition from paraelectric to ferroelectric phase, which is similar to dielectric relaxation ferroelectrics. Although several methods have been recently proposed to measure the dielectric properties of ultrafine BaTiO3, the problem still remains unsolved. This paper proposes a new method to estimate the dielectric properties of ultrafine BaTiO3 by measuring and analyzing the dielectric properties of BaTiO3-epoxy composites. The Novocontrol dielectric measuring system was employed to measure the dielectric response of the composites. The dielectric behavior and relaxation characteristics of the BaTiO3 filler were estimated by modeling and calculating the dielectric constant based on different mixture theories. Results reveal that the effect of surface states yields dielectric relaxation in ultrafine BaTiO3.
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| 2. |
- Chen, Si, 1981, et al.
(författare)
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A High Performance Ag Alloyed Nano-scale n-type Bi2Te3 Based Thermoelectric Material
- 2015
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Ingår i: Materials Today: Proceedings. - : Elsevier BV. - 2214-7853. ; 2:2, s. 610-619
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Konferensbidrag (refereegranskat)abstract
- A silver alloyed n-type bismuth telluride (Bi2Te3) thermoelectric (TE) bulk material with nano crystalline structure was studied and characterized in this paper. The Bi2Te3 nanopowders used in this study were first fabricated via a patented explosion based process. Then, the various concentrations of Ag nanoparticles (0-20 wt. %) were added into the Bi2Te3 nanopowders in order to increase the electrical conductivity. Combining the benefits of high electrical conductivity (1.51x10(5) S.m(-1)) and low thermal conductivity (0.441 W.m(-1).K-1), the dimensionless figure of merit (ZT value) of 1.48 for this n-type Bi2Te3 TE material is achieved at 300 K temperature.
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| 3. |
- Chen, Si, 1981, et al.
(författare)
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Sn-3.0Ag-0.5Cu Nanocomposite Solder Reinforced With Bi2Te3 Nanoparticles
- 2015
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Ingår i: IEEE Transactions on Components, Packaging and Manufacturing Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 2156-3985 .- 2156-3950. ; 5:8, s. 1186-1196
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Tidskriftsartikel (refereegranskat)abstract
- Nanocomposite solders are regarded as one of the most promising interconnect materials for the high-density electronic packaging due to their high mechanical strength and fine microstructure. However, the developments of nanocomposite solders have been limited by the inadequate compatibility between nanoparticles and solder matrix with respect to density, hardness, coefficient of thermal expansion, and surface activity. The compatibility issue will lead to a huge loss of nanoparticles from the solder matrix after the reflow soldering process. The thermal fatigue resistance of solder joint will also become degraded. Therefore, aiming to solve this problem, a novel nanocomposite solder consisting of Bi2Te3 semiconductor nanoparticles and Sn-3.0Ag-0.5Cu (SAC305) solder is presented. The effect of nanoparticles on the viscosity of solder paste and the void content of solder bump was first studied. Then, a series of analysis on the composition and microstructure of the solder bump were completed using transmission electron microscopy, X-ray diffraction, inductively coupled plasma-mass spectrometry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The survival rate of nanoparticles in the solder bump after reflow soldering process reaches as high as 80%. The refined microstructure was observed from the cross section of the nanocomposite solders. The shear test showed that the average mechanical strength of SAC305 solder after the addition of Bi2Te3 nanoparticles was higher. Meanwhile, no thermal fatigue resistance degradation was detected in the nanocomposite solder after 1000 thermal cycles in the range of -40 degrees C to 115 degrees C.
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| 4. |
- Daon, J., et al.
(författare)
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Chemically enhanced carbon nanotubes based Thermal Interface Materials
- 2015
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Ingår i: THERMINIC 2015 - 21st International Workshop on Thermal Investigations of ICs and Systems 2015. - 9781467397056
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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.
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| 5. |
- Huang, Shirong, et al.
(författare)
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Reliability of Graphene-based Films Used for High Power Electronics Packaging
- 2015
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Ingår i: 16th International Conference on Electronic Packaging Technology, ICEPT 2015, Changsha, China, 11-14 August 2015. - 9781467379991 ; , s. 852-855
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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.
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| 6. |
- Jeong, Seung Hee, et al.
(författare)
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Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor.
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| 7. |
- Jeong, Seung Hee, et al.
(författare)
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Thermal Elastomer Composites for Soft Transducers
- 2015
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Ingår i: 2015 Transducers - 2015 18th International Conference on Solid-State Sensors, Actuators and Microsystems, TRANSDUCERS 2015. - : IEEE conference proceedings. - 9781479989553 ; , s. 1873-1876
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Konferensbidrag (refereegranskat)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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| 8. |
- Jiang, Di, 1983, et al.
(författare)
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Vertically stacked carbon nanotube-based interconnects for through silicon via application
- 2015
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Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 36:5, s. 499-501
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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.
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| 9. |
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| 10. |
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