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  • Ozolins, O., et al. (författare)
  • 7×149 Gbit/s PAM4 transmission over 1 km multicore fiber for short-reach optical interconnects
  • 2018
  • Ingår i: Optics InfoBase Conference Papers. - : Optics Info Base, Optical Society of America. - 9781557528209
  • Konferensbidrag (refereegranskat)abstract
    • We transmit 80 Gbaud/λ/core PAM4 signal enabled by 1.55 μm EML over 1 km 7-core fiber. The solution achieves single-wavelength and single-fiber 1.04 Tbit/s post-FEC transmission enhancing bandwidth-density for short-reach optical interconnects.
  • Sun, Jie, 1977, et al. (författare)
  • Direct Chemical Vapor Deposition of Large-Area Carbon Thin Films on Gallium Nitride for Transparent Electrodes: A First Attempt
  • 2012
  • Ingår i: IEEE Transactions on Semiconductor Manufacturing. - 0894-6507. ; 25:3, s. 494-501
  • 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.
  • Tao, W., et al. (författare)
  • Reliability characterisation of bi-modal high temperature stable Isotropic Conductive Adhesives
  • 2010
  • Ingår i: Proceedings - 2010 11th International Conference on Electronic Packaging Technology and High Density Packaging, ICEPT-HDP 2010, Xian, 16-19 August 2010. ; :Article number 5582437, s. 225-228
  • Konferensbidrag (refereegranskat)abstract
    • Conductive adhesives are generally considered to be one of the strongest candidates for replacement of solder in electronics industry. However, some problems related to the performance have so far limited wider applications of conductive adhesives. One of the major problems is tendency to degrade during temperature and humidity aging. In this paper, two kinds of Isotropic Conductive Adhesives (ICA) with high temperature stable matrix and different fillers were fabricated. The first one was fabricated by simply adding silver flakes into matrix as filler using this high temperature stable matrix based on highly cross-linked aromatic functional groups. For the second one, in addition to silver flakes, nanosilver particles with different weight percentages were also added as filler into matrix to form a bi-modal ICA. The weight percentages of nano-silver particles in filler are 1wt%, 2wt% and 3wt% respectively. The filler content of these two ICAs are both 75wt% in total. All test samples were cured at 150°for 1 hour. The random distribution of the silver flakes in the adhesive was observed by SEM. The bulk resistivity of the ICAs with different fillers was investigated to characterize the electrical conductivity of the ICA. The results show that addition of small amount of nano-silver particles improve the electric conductivity of the ICA but the excessive amount of nano-silver particles led to the increase of the ICA's bulk resistivity. The humidity (85°/85RH) test was carried out and the resistances of the samples were measured. It was shown that some electrical resistance increase was observed during the humidity testing with time. The addition of the nano-particles has also some negative effect of the electrical resistance change. But the effect is limited in a few percentage range of the nano-particle addition.
  • Wang, Nan, et al. (författare)
  • Highly thermal conductive and electrically insulated graphene based thermal interface material with long-term reliability
  • 2019
  • Ingår i: Proceedings - Electronic Components and Technology Conference. - 0569-5503. ; 2019-May, s. 1564-1568
  • Konferensbidrag (refereegranskat)abstract
    • High density packaging in combination with increased transistor integration inevitably leads to challenging power densities in terms of thermal management. The conventional TIMs that are widely used in the microelectronic industry today are experiencing more and more stress due to their limited thermal performance and poor reliability. Composed by particle laden polymer matrix, thermal conductivity (K) of conventional TIMs is generally limited to 5 W/mK, and such values can be even lower for electrically insulated TIMs. Conventional TIMs also suffer from severe pump-out and dry-out failures, which brought great threat to the performance and lifetime of the electronic devices. Here, we solve these problems by applying a novel highly thermal conductive, electrically insulated and reliable graphene based TIMs (I-GTs). Composed by vertical graphene structures, I-GTs provide a continuous heat pathway from top to bottom, which enables superfast heat dissipation at through-plane direction. The highest bulk through-plane thermal conductivity of the conductive body can reach up to 1000 W/mK, which is orders of magnitude higher than conventional TIMs, and even outperforms the pure indium TIMs by over ten times. The highly flexible and foldable nature of I-GT enables at least 100% compressibility upon small applied pressures. As excellent gap fillers, I-GT can provide complete physical contact between two surfaces and thereby minimize the contact resistance to heat flow. The measured minimum thermal resistance for I-GTs reaches about 30 Kmm2/W. Such values are significantly higher than the randomly dispersed composites presented above. To ensure fully electrical insulation, a smooth and soft adhesive layer with a thickness of few microns was coated on the surface of I-GT. The breakdown voltage of I-GT reaches up to 950 V. Thermal cycling test shows the highly stable nature of I-GT. The good compressibility and elasticity of I-GT ensures continued proper TIM contact with substrates, which counteracts the effect of internal stress induced by the mismatch of coefficient of thermal expansion (CTE) during temperature cycling. In addition, the I-GTs have the advantages of low density and good maintainability. The resulting I-GTs thus opens new opportunities for addressing large heat dissipation issues for form-factor driven electronics and other high power driven systems.
  • Wang, Nan, et al. (författare)
  • Highly Thermal Conductive and Light -weight Craphene-based Heatsink
  • 2019
  • Konferensbidrag (refereegranskat)abstract
    • With the developing trend ofminiaturization and integration of modem electronic devices, commercial hearsinks ivaterigh, like copper and ii iv are facing mare and mare challenges, such as inefficient cooling performance, large size turd heavy weight. Here, we salve the probletn by developing a novel highly thermal conductive and 11Mo-weight graphene heatsink. Cornposed by vertically-aligned and continUOUS graphene structures, heat transport was highly efficiero from the base 1o fin Ii: ininside the heatsink, The maximum through-platre thermal catuluctivity ofgraphene heatsink can be up to 1000 1500 Ward( which is over 7 times higher than aluminum, and even outperforms copper about 4 times_ Gmphene heatsink demonstrated outstanding cooling perffrmance which wm superior to copper heatsink with the same dimension and same power input. Noticeably, the graphene hearsink also has anportant advantagas of light-weight and high emissions,. The measured density (1 1 g cmli is only onroeighth of copper and lam than hoor of aluminum and emissivity is about ten times hiher than pure rapper and aluminum. The resulting graphene heatsink thus opertS rim opportunities for addressing large heat dissMatMn issues in weight' driven electronics and othm high power smions.
  • Wang, Nan, et al. (författare)
  • Highly thermal conductive and light-weight graphene-based heatsink
  • 2019
  • Ingår i: 2019 22nd European Microelectronics and Packaging Conference and Exhibition, EMPC 2019.
  • Konferensbidrag (refereegranskat)abstract
    • With the developing trend of miniaturization and integration of modern electronic devices, commercial heatsinks materials, like copper and aluminum, are facing more and more challenges, such as inefficient cooling performance, large size and heavy weight Here, we solve the problem by developing a novel highly thermal conductive and light-weight graphene heatsink. Composed by vertically-aligned and continuous graphene structures, heat transport was highly efficient from the base to fin structures inside the heatsink The maximum through-plane thermal conductivity of graphene heatsink can be up to 1000 1500 W/mK, which is over 7 times higher than aluminum, and even outperforms copper about 4 times. Graphene heatsink demonstrated outstanding cooling performance which was superior to copper heatsink with the same dimension and same power input. Noticeably, the graphene heatsink also has important advantages of light-weight and high emissivity. The measured density (1.1 g/cm) is only one-eighth of copper and less than half of aluminum and emissivity is about ten times higher than pure copper and aluminum. The resulting graphene heatsink thus opens new opportunities for addressing large heat dissipation issues in weight driven electronics and other high power systems.
  • Wang, Teng, 1983, et al. (författare)
  • Development of Carbon Nanotube Bumps for Ultra Fine Pitch Flip Chip Interconnection
  • 2006
  • Ingår i: 1st Electronics Systemintegration Technology Conference; Dresden, Saxony; Germany; 5 September 2006 through 7 September 2006. ; 2, s. 892-895
  • Konferensbidrag (refereegranskat)abstract
    • Since 1991, carbon nanotubes have been considered for successful applications in various fields due to their unique properties. In the present work, carbon nanotubes are applied in integrated circuit packaging, as the bump interconnection for flip chip. The reason for choosing carbon nanotubes as the bump material is their special electrical, mechanical and thermal properties, which may promote both the performance and reliability of the flip chip packaging. Moreover, carbon nanotubes can be formed according to a precisely predefined small-scale pattern, which makes extremely high density interconnection possible. Vertically aligned carbon nanotubes are grown on silicon in the form of square arrays of different sizes, heights and pitches. Attempts to use thermal compression and anisotropic conductive adhesive to bond chips carrying carbon nanotube bumps with ceramic substrates are also executed. Mechanical testing is performed afterward to determine the strength of the bonding interfaces. The strength of the bonding by thermal compression is very weak, in the range from 1.9 to 7.0 g/mm2. The bonding by anisotropic conductive adhesive is much stronger, indicating a possible approach to bond chips carrying carbon nanotube bumps.
  • Wang, Teng, 1983, et al. (författare)
  • Low temperature transfer and formation of carbon nanotube arrays by imprinted conductive adhesive
  • 2007
  • Ingår i: Applied Physics Letters. - 0003-6951 .- 1077-3118. ; 91:9
  • Tidskriftsartikel (refereegranskat)abstract
    • This letter demonstrates the transfer and formation of aligned carbon nanotube (CNT) arrays at low temperature by imprinted conductive adhesive. A thermoplastic isotropic conductive adhesive is patterned by an imprint and heat transfer process. The CNTs grown by thermal chemical vapor deposition are then transferred to another substrate by the conductive adhesive, forming predefined patterns. The current-voltage response of the transferred CNT bundles verifies that good electrical connection has been established. This process can enable the integration of CNTs into various temperature-sensitive processeses and materials.
  • Wang, Teng, 1983, et al. (författare)
  • Through silicon vias filled with planarized carbon nanotube bundles
  • 2009
  • Ingår i: Nanotechnology. - 0957-4484 .- 1361-6528. ; 20:48
  • Tidskriftsartikel (refereegranskat)abstract
    • The feasibility of using carbon nanotube (CNT) bundles as the fillers of through silicon vias (TSVs) has been demonstrated. CNT bundles are synthesized directly inside TSVs by thermal chemical vapor deposition (TCVD). The growth of CNTs in vias is found to be highly dependent on the geometric dimensions and arrangement patterns of the vias at atmospheric pressure. The CNT-Si structure is planarized by a combined lapping and polishing process to achieve both a high removal rate and a fine surface finish. Electrical tests of the CNT TSVs have been performed and their electrical resistance was found to be in the few hundred ohms range. The reasons for the high electrical resistance have been discussed and possible methods to decrease the electrical resistance have been proposed.
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Liu, Johan, 1960 (521)
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