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News

ICREA Workshop on Phonon Engineering: Registration Open!

Registration for the ICREA workshop on Phonon Engineering 2010 to be held in Sant Feliu de Guixols, Girona, Spain on 24-27th May is now open!

www.regonline.com/phononengineering2010

TOPICS

Energy Conversion
Micro to Nanoscale thermal management
Phononic crystals
Photon-phonon interactions
Electron-phonon interactions in low dimensions
Phonons in Metrology and in Biology
Coherent acoustic phonons and Phonon sources
Phonon-polaritons transport

Announcement: ICREA Workshop on Phonon Engineering

ICREA Workshop on Phonon Engineering

Dates: 25-28 May 2010
Location: Hotel Eden Roc Sant Feliux de Guixols, Barcelona, Spain

Main fields covered: Nanophononics, Energy Conversion; Micro- to Nano-scale thermal management; Hypersonic (Phononic) crystals; Photon-phonon interactions in low dimensions; Electron-phonon interactions in low dimensions; Phonons in Metrology; Quantum information processing; Phonon-polariton transport; Near field radiation.

Session on Nanoscale thermal transport I
- Mesoscopic thermal transport, A Majumdar, UC Berkeley, USA
- Molecular dynamics of Phonon Heat Transfer, tba
- Thermal Memories, Baowen Li, Singapore National University,
Session on Energy Conversion
- Nanostructures thermoelectric Materials, Gang Chen, MIT, USA
- Theory of thermoelectricity, Natalio Mongo, CEA-Grenoble, France
Session on Phonons in Nanotechnology II
- Thermal management in microelectronic devices and interfaces, Bruno Michel, IBM
- Phonons in Nanometrology, Juerg Dual, ETH Zurich, Switzerland
Session on Nanoscale thermal Transport II
- Ultra-low thermal conductivity, Ravi S Prasher, Arizona State University, USA
- Theory of phonon polariton heat conduction in nanostrcutres, ENSMA Poitiers,
Other sessions ...
- Phonons in Biomaterials, Michael Stroscio, North Carolina University, USA
- Phonon Engineering: from Nanowires to graphene, Alexander Balandin, UC Riverside,
- Status of Bulk Acoustic Waves Devices, Tuomas Pensala, VTT, Finland
- Photon-Phonon coupling for ICT, Garnett Bryant, NIST, Washington, USA
- Low frequency acoustic waves for information processing, J-L Thomas, U P7M Curie

IBM: IEEE Harvey Rosten Award for Excellence 2008

Congratulations to the IBM team for the IEEE Harvey Rosten Award for Excellence 2008!

Alongside the IEEE Semitherm conference in San Jose, on March 19, Ryan Linderman, Thomas Brunschwiler, Urs Kloter, Hilton Toy and Bruno Michel were rewarded for their outstanding work in the field of thermal analysis of electronic equipment.

Harvey Rosten Award 1

Awarded were the concept, implementation and application of:

directing particle placement by means of channels cut into the surface of a chip or heatsink and,
reducing the gap thickness despite higher viscosity andhigher particle fill factor by means of a hierarchical set of channels.
formulating a thermal paste with higher matrix viscosity to delay the onset of particle stacking to higher fill factors

The award committee especially mentioned the exemplary way how research from different fields like biology, physics, materials sciences, and engineering was combined in an interdisciplinary fashion and how a research concept was brought to a technological application in a short time.

The NANOPACK consortium is very proud that the scientific and technical excellence of one partner is world wide recognized. Congratulations!

12-Month Milestones successfully achieved

M2.3: First nanofiller based thermal conductive phase change material for characterization

“The first nanofiller based thermally conductive phase change material for characterization” was defined as the third milestone of Work Package 2 “Development of Materials” of Nanopack. This milestone has been achieved and will be presented in the form of technical report at Nanopack meeting to be held on 28th November 2008 in Vienna. The first nanofiller reinforced thermally conductive phase change material has been prepared using phase change materials incorporated with carbon nanofiber (CNF) and their thermal resistance has been measured. The milestone includes the selection of phase change material (PCM), optimisation of CNF dispersion into PCM, uniformity evaluation of CNF in PCM, measurement of thermal resistance and the dependence of Rth on mixing time, and finally CNF-PCM samples have been prepared for performance evaluation and for further work.

M3.1: First demonstration of successfully modified surfaces for thermal interfaces

The Milestone focuses on IBM’s Hierarchically Nested Channel (HNC) technology for modified solid interfaces while mentioning other surface modification techniques under investigation later in the task. We present results of the HNC technology with a number of thermal pastes, discuss the phenomena that affect bondline formation, and highlight applications that may benefit from modified surfaces for thermal interfaces.Hierarchically nested channel (HNC) technology fabricates channels in the thermal interface of two solids. It was developed at IBM to reduce the thermal resistance of an electronic package and has been demonstrated with interfacial areas ranging 1-250 cm2. This surface modification technology is expected to allow lower operating temperatures and/or higher power and shows promise for automotive, power electronics, optical, RF, and microprocessor applications.

M4.1: First designs of intelligent test chip, thin film heaters and assembled test systems for characterisation

Three types of test systems have been designed through the milestone M4.1 and are briefly presented here:

A 3-omega setup has been designed and is under construction to measure the thermal conductivity of samples produced at room temperature. A future update of the experiment will incorporate a cryostat enabling measurements of thermal properties in the range 8 – 500K.
A static TIM tester is also under construction. The basic idea of the design is to use the micromachining facility provided by the recent technology of integrated circuits. In this way the realization of very small sized sample holders becomes possible, with temperature sensors positioned in extreme tight vicinity of the investigated TIM layer. A Rth resolution of 0,03 Kmm²/W is expected for nominal measurements as low as 2 to 5 Kmm²/W.
Test System for mono-metal TIMs: The idea of this test system is to measure the thermal conductivity of very highly conductive metal-based TIMs with the help of a steady state technique. Solders as well as sintered mono-metal layers could be tested with this method, which should yield good results up to thermal conductivities of 100 W/mK within an accuracy of < 10 %. The advantage is that the thermal conductivity is measured under processing conditions as in real applications.

M6.1: First results from packed particle model with twice enhanced conductivity

FEM models have been developed to investigate thermal properties of random and ordered packed particle formations with comparison to percolation models. A cubic cell model has been established to evaluate the effective thermal conductivity of the thermal conductive adhesive (TCA) consisting of a polymer matrix and conductive fillers. This model has been applied to the Ag filler in epoxy matrix. Primary results show that a thermal conductivity of 20W/mk can be reached.

M6.2: First results for phonons from particles on SOI surface The main objective of milestone

M6.2 was to build new numerical tools, based on FDTD method, to calculate the phonon dispersion relations and transport in structures constituted by a membrane supporting an array of particles. For periodical array of cylindrical dots deposited on a thin plate, the phonon band structure displays a low frequency gap that persists for various combinations of the materials constituting (plate and dots) and is associated with resonant modes of the individual dots. In addition, the transmission spectrum of normally incident phonons was calculated between two substrates through a periodic set of particles. The calculated spectrum shows fast oscillations and gaps, related to the periodicity of the structure, materials used, and dimensions of dots.

Annoucement for a Postdoctoral Position in IEMN

Post-doctoral position in
Institut d’Electronique, Microélectronique et Nanotechnologies (IEMN), UMR CNRS 8520, Université des Sciences et Technologies de Lille (http://www.iemn.univ-lille1.fr/ )
Equipe de Physique des Ondes, Nanostructures et Interfaces (EPHONI)

The postdoctoral position is proposed in the frame of the FP7-ICT integrating project “Nano Packaging technology for Interconnect and Heat Dissipation (Nanopack)”, involving 14 partners from 8 European countries (see the website http://www.nanopack.org )

Title: Numerical modelling of phonon transport and thermal conductivity of nanoparticles on SOI substrates

Context of the project:
Thermal management of chip based electronic devices is becoming one of the largest bottlenecks to increased performance and integration density. Modern silicon microelectronics is now firmly in the nanoscale regime with many experiments demonstrating significantly reduced thermal transport due to the close proximity of interfaces and phonon confinement in sub 50nm SOI type structures. The consequence of phonon quantisation in the thin silicon channel is reduced group velocity and, consequently, reduced thermal conduction inside the silicon film. Moreover, the proposed novel designs in this area while showing improvements in electrical performance create additional thermal dissipation and/or thermal resistance due to size restrictions in the thermal contact area that also lead to phonon scattering related resistance increases. The overall objective of the NANOPACK project is to develop new thermal interface technologies for low thermal resistance by employing nano-modified surfaces and materials along with methods to characterize and simulate them with respect to thermal, electrical and reliability-related properties. On the theoretical side, the general aim of the project is to use simulative and nano-analytical methods to understand heat transport on a nano/micro scale.

Objectives of the research project:
Two types of generic structures have been proposed to be investigated, namely lamellar structures of SOI type materials and nanoparticles on SOI substrates. Our objectives are to develop simulation techniques to calculate the vibrational spectra of these structures and mostly evaluate the effect of phonon dispersion, as well as geometrical and material parameters, on their thermal conductivities. For this purpose, the candidate will be familiarized with some simulation techniques such as finite difference time domain, finite element and plane wave expansion methods already developed in the frame of elasticity theory by the group in Lille. These methods enable us to calculate the band structure and phonon transport in inhomogeneous materials and, in particular, in phononic crystals constituted by a periodic repetition of inclusions in a background material. The development of atomic force field models for small nanostructures would be also welcome. The main purpose of the project is to use these results to obtain the thermal conductivity in the above structures. A first approximation, assuming the coherence of the phonons in the whole structure, would consist of using the Landauer’s approach to calculate the phonon transmission and thermal conductance. In contrast, a Boltzmann transport equation approach should be developed to emphasize the effect of diffuse scattering at the contacts between the nanoparticles and/or thin films. Transport of heat can be tested versus different assumptions about the phonon mean free path and relaxation time. The ultimate objective is the optimum proposition of geometries and materials for the best thermal performance.
Finally, depending on the available time, the simulation methods developed during the project can also be used to investigate light scattering by phonons in SOI structures, in collaboration with the Raman experiments performed by other partners.

Duration: One or possibly two years.

The Candidate should hold a PhD in solid state physics or material science, or in mechanical or electrical engineering. A good background in physics and simulation techniques and an experience with transport phenomena (in particular on the basis of Boltzmann equation techniques) are required.

Contact: Interested candidates should send their resume, publication list and contact information to:
Yan Pennec (yan.pennec@univ-lille1.fr ) or
Bahram Djafari Rouhani (bahram.djafari-rouhani@univ-lille1.fr ).
Application will be accepted until position is filled

Milestone M2.2 Achieved

“The first nano-filler based thermally conductive adhesive for characterization” was defined as the second milestone of Work Package 2 “Development of Materials” of Nanopack as described in DOW. This milestone has been achieved and will be presented in the form of technical report at Nanopack meeting, which will be held on 23rd September 2008 in Rome. The first nano-filler based thermally conductive adhesive has been prepared using high temperature-treated carbon nanofiber (CNF) as the nano-filler and their thermal performance has been studied. The milestone includes the successfully selection of matrix epoxy, optimisation of CNF dispersion into the matrix epoxy, measurement of thermal resistance and the dependence of Rth on CNF content, and finally the study of curing parameters.

Dow Corning annouces a new high perf TIM for sale

The Dow Corning Electronics Group (Midland, Mich.) said it is now selling a thermally conductive compound developed for use with Intel Corp.’s newest mobile microprocessor, the Core2 Extreme mobile processor. the TC-5688 compound offers extremely low thermal resistance at 0.05°C-cm2/W and a high level of thermal conductivity at 5.67 W/m·K.