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Johan Liu: Thermal Management of Electronics Using Carbon Nanotubes

posted 12 Jul 2011, 06:44 by info admin
Electronic systems today generate a large amount of heat due to increased demand in miniaturization and more functionality. According to Eric Pop, out of the total electricity used for running data servers in USA in 2006, Over 50% were used to cool the systems. Similar to the rest of the electronics industry, mobile communication electronics hardware for instance, radio-base stations are also producing a huge amount of heat that has to be dissipated. Next generation radio base stations consist of more than 5-6 DSPs in many cases (each of them produces more than 5-6 W on a size of less than 0,25 cm2) dissipating roughly 30 W per radio base station unit. Locally, the heat intensity can be up to 25-30 W/cm2 in this case. With this constant heat generated, it is obvious that mobile communication electronics industry has also to look for new cooling technologies to manage the heat dissipation.

The above-mentioned is just a few examples of the heat dissipation problems that are facing electronics industry. In fact, heat dissipation provides great challenges in many applications including also automotive electronics, power electronics and LED business sectors. In automotive electronics systems, single device can pump out up to 80 W continuously and in transient stage up to 300 W (within 10 nanoseconds). LED devices can have heat intensity between 1000 and 2000 W/cm2 due to its extremely small size. Therefore, we anticipate that thermal management of heat dissipation will be of strategic importance for the development of many future products.

To cope with this issue, we have developed a number of carbon nanotube thermal management technologies such as dry densification of carbon nanotube bundles, rapid and low temperature transfer of carbon nanotubes using Indium as well as vertical interconnect using Carbon Nanotube based TSV concept for thermal and electrical path. Major publications are Fu et al, Adv. Mat, DOI: 10.1002/adma.201002415, Wang et al, DOI: 10.1002/smll.201100615, Wang et al, DOI: 10.1016/j.carbon.2010.06.042. 

To fully achieve the large potential of carbon nanotubes in thermal control of electronics, progresses in a number of aspects must be made in the future. For the first, we need to investigate the long term reliability of 3 D carbon nanotube thermal dissipation systems and demonstrate this against copper based technology 

Dr Johan Liu graduated with a master and Ph D degree in materials science from the Royal Institute of Technology, Sweden. Before joining Chalmers University of Technology, he served in various positions at the Swedish Institute for Production Research (IVF) as project manager, group leader and division manager. He is currently full professor in electronics production, Department of Microtechnology and Nanoscience in Chalmers University of Technology, Sweden. He is also director of SMIT Center both at Chalmers University of Technology and Shanghai University, China (A joint center between Sweden and China). As a member of the Royal Swedish Academy of Engineering Sciences and a Fellow of IEEE, he has published 2 books, 370 papers in journals, proceedings and 14 book chapters with a Hirsch index of 19 and with an citation of over 1096 times, He has 21 patents accepted or filed and has given about 35 key note/invited talks during the last 20 years. He has also received many awards including IEEE Exceptional Technical Achievement Award, IEEE CPMT Transaction Best paper Award in “Advanced Packaging”. His research field covers mainly nanopackaging materials and process for electronics and MEMS including 3D CNT TSV technology, CNT Cooling technology, CNT Bumping, high temperature stable conductive adhesives, nano soldering, nano thermal interface materials, nanomaterials for thermo-electrical applicatoins and nanoscaffolds for biomedical applications.Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg, Sweden
SMIT Center and School of Mechatronics and Mechanical Engineering, Shanghai University, China, Email:jliu@chalmers.se