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Fu Y.,Chalmers University of Technology | Fu Y.,FOAB Elektronik AB | Nabiollahi N.,Chalmers University of Technology | Wang T.,Chalmers University of Technology | And 9 more authors.
Nanotechnology | Year: 2012

Heat dissipation is one of the factors limiting the continuous miniaturization of electronics. In the study presented in this paper, we designed an ultra-thin heat sink using carbon nanotubes (CNTs) as micro cooling fins attached directly onto a chip. A metal-enhanced CNT transfer technique was utilized to improve the interface between the CNTs and the chip surface by minimizing the thermal contact resistance and promoting the mechanical strength of the microfins. In order to optimize the geometrical design of the CNT microfin structure, multi-scale modeling was performed. A molecular dynamics simulation (MDS) was carried out to investigate the interaction between water and CNTs at the nanoscale and a finite element method (FEM) modeling was executed to analyze the fluid field and temperature distribution at the macroscale. Experimental results show that water is much more efficient than air as a cooling medium due to its three orders-of-magnitude higher heat capacity. For a hotspot with a high power density of 5000Wcm 2, the CNT microfins can cool down its temperature by more than 40°C. The large heat dissipation capacity could make this cooling solution meet the thermal management requirement of the hottest electronic systems up to date. © 2012 IOP Publishing Ltd.

Fu Y.,Chalmers University of Technology | Fu Y.,FOAB Elektronik AB | Ye L.-L.,SHT Smart High. - Technology AB | Liu J.,Chalmers University of Technology | Liu J.,Shanghai University
Materials Letters | Year: 2012

A novel method using lift-off process for patterning very thick materials is developed and demonstrated. Unlike conventional lift-off processes, no special lift-off resist is used in this method. Instead, only a double-coated single photoresist is needed. Demonstrations using two commercial photoresists show that good patterning morphology and obvious undercuts as high as 15 μm are obtained for lift-off, which is very difficult to achieve by existing methods. The application and feasibility of this approach is demonstrated by a carbon nanotube transfer process. This simple and effective method offers wider option to pattern very thick materials in high quality which are in strong demands. © 2012 Elsevier B.V. All rights reserved.

Fu Y.,Chalmers University of Technology | Fu Y.,SHT Smart High. - Technology AB | Wang T.,Chalmers University of Technology | Wang T.,SHT Smart High. - Technology AB | And 3 more authors.
Journal of Micromechanics and Microengineering | Year: 2010

In this paper, a series of micro-machining processes have been developed to fabricate a test platform with the ability of in situ temperature monitoring on thermal interface behaviour. Through silicon vias (TSVs) with an aspect ratio up to 13 using Cu as a conductor have been applied to connect an array of platinum-based temperature sensors directly deposited on the thermal interfaces to be measured. The sensors are subsequently calibrated by an industry standard resistance temperature detector. Results show that the temperature sensors function normally in a temperature range up to 250 °C. This demonstrates the successful deposition of temperature-sensing materials and their good connection to the TSVs. The realization of direct precise temperature measurement on the thermal interface of this test platform enables thermal characterization with a high accuracy. © 2010 IOP Publishing Ltd.

Fu Y.,Chalmers University of Technology | Fu Y.,FOAB Elektronik AB | Chen S.,Chalmers University of Technology | Chen S.,Shanghai University | And 6 more authors.
Materials Letters | Year: 2012

Growth of high-quality vertical aligned carbon nanotube (CNT) structures on silicon supported gold (Au) films by thermal chemical vapor deposition (TCVD) is presented. Transmission electron microscopy (TEM) images show that the growth is highly selective. Statistical study reveals that 79.4% of the as-grown CNTs are double-walled. The CNTs synthesized on Au films are more porous than that synthesized on silicon substrates under the same conditions. Raman spectroscopy and electrical characterization performed on the as-grown double-walled CNTs (DWNTs) indicate that they are competitive with those CNTs grown on silicon substrates. Field emission tests show that closed-ended DWNTs have lower threshold field than those open-ended. © 2011 Elsevier B.V. All rights reserved.

Fu Y.,Chalmers University of Technology | Fu Y.,FOAB Elektronik AB | Qin Y.,Chalmers University of Technology | Qin Y.,SHT Smart High. - Technology AB | And 5 more authors.
Advanced Materials | Year: 2010

An indium-assisted ultrafast carbon nanotube (CNT) transfer method with a yield rate over 90% is described. Metal-coated as-transferred CNT structures exhibit excellent electrical performance that is at least one order of magnitude better than the previously published results. Shear test results show that the adhesion between CNTs and the substrate is greatly improved and excellent flexibility is obtained after the transfer process. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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