| 321. |
- Shan, Bo, et al.
(författare)
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Preparation of graphene/aligned carbon nanotube array composite films for thermal packaging applications
- 2019
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Ingår i: Japanese Journal of Applied Physics, Part 1: Regular Papers & Short Notes. - : IOP Publishing. - 0021-4922 .- 1347-4065. ; 58
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Tidskriftsartikel (refereegranskat)abstract
- Vertically aligned carbon nanotube arrays (VACNTs) have been successfully achieved by CVD. The carbon nanotubes were almost triple-walled. Furthermore, the graphene/VACNT composite films have been prepared as thermal interface materials, using photolithographic and densification processes. Compared with pure epoxy resin, the longitudinal thermal conductivity of the composite films was obviously improved, which confirmed that VACNTs provided additional longitudinal heat transfer channels in the films. Furthermore, their longitudinal thermal conductivity was largely dependent on the distribution of VACNTs. The transversal thermal conductivity of the composite film with a pattern size of 300 mu m was about seven times higher than that of pure epoxy resin. This indicated that graphene provided additional horizontal heat transfer channels to achieve the enhancement of transversal thermal conductivity in composite films. (C) 2019 The Japan Society of Applied Physics
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| 322. |
- Shi, Yuqing, et al.
(författare)
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Fabrication and characterization of graphene based film
- 2017
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Ingår i: 2017 IMAPS Nordic Conference on Microelectronics Packaging, NordPac 2017, Goteborg, Sweden, 18-20 June 2017. - 9781538630556 ; , s. 162-166
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Konferensbidrag (refereegranskat)abstract
- Large area, freestanding graphene papers fabricated from 2D graphene nanosheets with optimized microstructure, graphene sheet alignment and superior properties have a wide range of functional applications. In this paper, we propose a novel approach to fabricate graphene film by Electro-spray deposition (ESD), which is considered as the preparation for a roll-to-roll industrial production of the further. Expanded graphite, as the raw materials, was dispersed into N-Methyl-2-pyrrolidone (NMP) which is used as the feeding solution for ESD. It is also shown that high-shear mixing and high ultra-sonication of graphite powder in NMP solvent result in large-scale exfoliation, giving good dispersions of graphene nanosheets. The fabrication of the film with different thicknesses is based on ESD onto the surface of a heated aluminum foil at around 140°C. Brunauer-Emmett-Teller method is used to test the surface area of raw material, which has been reported to reach 1200 m2/g. Raman spectroscopy and scanning electron microscope (SEM) are used to characterize the microstructure and morphology of the film, contributing to the optimization of electrospray's parameters. Joule heating was utilized to quantify thermal conductivity of the film.
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| 323. |
- Sitek, J., et al.
(författare)
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Comparisons of nano-additives influence on properties of the bi-modal solder pastes for special applications
- 2011
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Ingår i: Proceedings - 12th International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2011, Shanghai, 8-11 August 2011. - 9781457717680 ; , s. 183-187
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Konferensbidrag (refereegranskat)abstract
- The paper presented the results of investigation of two solder pastes SnBi and SAC with different nano-particles, which could be applied for special application. It was presented that materials and samples preparation for investigation. The results of SEM analyzer of solder joints executed using these pastes and their shear strength measurements enable to make the comparison of nano-additives influence on properties of the bi-modal solders pastes. It was observed that addition of nano-particles into both solder pastes changed the microstructure of solder joints, and formed a large number of nano-sized grains with uniform distribution. For the SAC solder joints with nano-Ag particles it was also observed that specific Ag3Sn crystallites. We supposed that the Ag3Sn crystals, which created "internal net" and nano-sized grains with uniform distribution must influence the mechanical properties of the solder joints. The results of shear strength measurements of solder joints confirmed the significantly higher shear strength of bimodal solder joints in comparison to reference solder joints without nano-additives.
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| 324. |
- Sitek, J., et al.
(författare)
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Influence of nano additives on mechanical properties and reliability of interconnects made by electrically conductive adhesives on elastic substrates for printed electronics application
- 2014
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Ingår i: 15th International Conference on Electronic Packaging Technology, ICEPT 2014; Wangjiang HotelChengdu; China; 12 August 2014 through 15 August 2014. - 9781479947072 ; :Art. no. 6922625, s. 151-154
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Konferensbidrag (refereegranskat)abstract
- The results of investigations of new compositions of electrically conductive adhesives (ECA) for printed electronics applications with and without nano-additives are presented. The studies covered the influence of nano additives on mechanical properties and reliability of interconnects made by elaborated, improved composition of the ECA based on primary conclusions. The obtained results showed that nano additives influence significantly and positively on mechanical properties of ECA joints, but their impact on the reliability properties of joints manufactured in low temperatures is much lower or even negative.
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| 325. |
- Sun, Jie, 1977, et al.
(författare)
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Controllable chemical vapor deposition of large area uniform nanocrystalline graphene directly on silicon dioxide
- 2012
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 111:4
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Tidskriftsartikel (refereegranskat)abstract
- Metal-catalyst-free chemical vapor deposition (CVD) of large area uniform nanocrystalline graphene on oxidized silicon substrates is demonstrated. The material grows slowly, allowing for thickness control down to monolayer graphene. The as-grown thin films are continuous with no observable pinholes, and are smooth and uniform across whole wafers, as inspected by optical-, scanning electron-, and atomic force microscopy. The sp(2) hybridized carbon structure is confirmed by Raman spectroscopy. Room temperature electrical measurements show ohmic behavior (sheet resistance similar to exfoliated graphene) and up to 13% of electric-field effect. The Hall mobility is similar to 40 cm(2)/ Vs, which is an order of magnitude higher than previously reported values for nanocrystalline graphene. Transmission electron microscopy, Raman spectroscopy, and transport measurements indicate a graphene crystalline domain size similar to 10 nm. The absence of transfer to another substrate allows avoidance of wrinkles, holes, and etching residues which are usually detrimental to device performance. This work provides a broader perspective of graphene CVD and shows a viable route toward applications involving transparent electrodes.
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| 326. |
- Sun, Jie, 1977, et al.
(författare)
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Direct Chemical Vapor Deposition of Large-Area Carbon Thin Films on Gallium Nitride for Transparent Electrodes: A First Attempt
- 2012
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Ingår i: IEEE Transactions on Semiconductor Manufacturing. - : Institute of Electrical and Electronics Engineers (IEEE). - 0894-6507 .- 1558-2345. ; 25:3, s. 494-501
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Tidskriftsartikel (refereegranskat)abstract
- Direct formation of large-area carbon thin films on gallium nitride by chemical vapor deposition without metallic catalysts is demonstrated. A high flow of ammonia is used to stabilize the surface of the GaN (0001)/sapphire substrate during the deposition at 950 degrees C. Various characterization methods verify that the synthesized thin films are largely sp(2) bonded, macroscopically uniform, and electrically conducting. The carbon thin films possess optical transparencies comparable to that of exfoliated graphene. This paper offers a viable route toward the use of carbon-based materials for future transparent electrodes in III-nitride optoelectronics, such as GaN-based light emitting diodes and laser diodes.
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| 327. |
- Sun, Jie, 1977, et al.
(författare)
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Low Partial Pressure Chemical Vapor Deposition of Graphene on Copper
- 2012
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Ingår i: IEEE Transactions on Nanotechnology. - 1941-0085 .- 1536-125X. ; 11:2, s. 255-260
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Tidskriftsartikel (refereegranskat)abstract
- A systematic study of the Cu-catalyzed chemical vapor deposition of graphene under extremely low partial pressure is carried out. A carbon precursor supply of just P-CH4 similar to 0.009 mbar during the deposition favors the formation of large-area uniform monolayer graphene verified by Raman spectra. A diluted HNO3 solution is used to remove Cu before transferring graphene onto SiO2/Si substrates or carbon grids. The graphene can be made suspended over a similar to 12 mu m distance, indicating its good mechanical properties. Electron transport measurements show the graphene sheet resistance of similar to 0.6 k Omega/square at zero gate voltage. The mobilities of electrons and holes are similar to 1800 cm(2)/Vs at 4.2 K and similar to 1200 cm(2)/Vs at room temperature.
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| 328. |
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| 329. |
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| 330. |
- Sun, Peng, 1979, et al.
(författare)
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High temperature aging study of intermetallic compound formation of Sn-3,5Ag and Sn-4.0Ag-0,5Cu solders on electroless Ni(P) metallization
- 2006
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Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388. ; 425:1-2, s. 191-199
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Tidskriftsartikel (refereegranskat)abstract
- The Sn-3.5Ag and Sn-4.0Ag-0.5Cu solders on Au/electroless Ni(P) metallization exhibited different interfacial morphologies after high temperature storage (HTS) at 150 °C. Ni 3 Sn 4 intermetallic compounds (IMCs) were found in the Sn-Ag system, while for the Sn-Ag-Cu system the IMCs consisted of two kinds of interfacial reactions. For the Sn-3.5Ag solder, the Ni 3 Sn 4 IMC particles lost adhesion/contact to the electroless Ni(P) layer and clear gap was observed in the samples after high temperature storage (HTS) aging for 1000 h. In the Sn-4.0Ag-0.5Cu solder joint, both (Cu,Ni) 6 Sn 5 and (Ni,Cu) 3 Sn 4 compounds were observed after HTS aging. Since the difference in nucleation site and growth rate for kinds of IMCs, (Cu,Ni) 6 Sn 5 was observed at top and (Ni,Cu) 3 Sn 4 at bottom when the interfacial compound layer became thicker as a function of thermal aging. Some voids were found between the electroless Ni(P) interface and the Sn-Ag solder after 168 and 500 h of thermal aging, while the clear gap between the solder and the Ni layer existed after 1000 h aging. The formation mechanism for this gap could be the interconnection and growth of the voids. In the Sn-Ag-Cu system, voids were found inside the Sn-Ni-Cu ternary interfacial compounds after 500 and 1000 h. The formation mechanism for these voids was thought to be Kirkendall effect or etching process. The interfacial layer of Sn-Ag-Cu solder on electroless Ni(P) coating showed the better thermal stable than eutectic Sn-Ag solder. © 2006 Elsevier B.V. All rights reserved.
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