Electronics Protection - March/April 2012 - (Page 18)

Thermal UC Riverside is Keeping Electronics Cool A University of California, Riverside engineering professor and a team of researchers have made a breakthrough discovery with graphene, a material that could play a major role in keeping laptops and other electronic devices from overheating. Alexander Balandin, a professor of electrical engineering at the UC RiversideBourns College of Engineering, and researchers from The University of Texas at Austin, The University of Texas at Dallas and Xiamen University in China, have shown that the thermal properties of isotopically engineered graphene are far superior to those of graphene in its natural state. The research efforts were led by the Professor Rodney S. Ruoff of UT Austin and Balandin, a corresponding author for the paper, “Thermal conductivity of isotopically modified graphene.” The results bring grapheme, a single-atom thick carbon crystal with unique properties, including superior electrical and heat conductivity, mechanical strength and unique optical absorption, one step closer to being used as a thermal conductor for managing heat dissipation in everything from electronics to photovoltaic solar cells to radars. “The important finding is the possibility of a strong enhancement of thermal conduction properties of isotopically pure graphene without substantial alteration of electrical, optical and other physical properties,” Balandin said. “Isotopically pure graphene can become an excellent choice for many practical applications provided that the cost of the material is kept under control. The experimental data on heat conduction in isotopically engineered graphene is also crucially important for developing an accurate theory of thermal conductivity in graphene and other two-dimensional crystals.” The research used the optothermal Raman method, a thermal conductivity measuring technique developed by Balandin. In 2008, Balandin and his group members demonstrated experimentally that graphene is an excellent heat conductor. They also developed the first detailed theory of heat conduction in graphene and related two-dimensional crystals. The work shows that the thermal conductivity of isotopically engineered graphene is strongly enhanced compared to graphene in its natural state. Naturally occurring carbon materials, including graphene, are made up of two stable isotopes; about 99 percent of 12C (referred to as carbon 12) and 1 percent of 13C (referred to as carbon 13). The difference between isotopes is in the atomic mass of the carbon atoms. The removal of just about 1 percent of carbon 13, also called isotopic purification, modifies the dynamic properties of crystal lattices and affects their thermal conductivity. The importance of the present research is explained by practical needs for materials with high thermal conductivity. Heat removal has become a crucial issue for continuing progress in the electronics industry, owing to increased levels of dissipated power as the devices become smaller and smaller. The search for materials that conduct heat well has become essential for the design of the next generation of integrated circuits and three-dimensional electronics. Balandin believes graphene will gradually be incorporated into different devices. Intially, it will likely be used in some niche applications such as thermal interface materials for chip packaging or transparent electrodes in photovoltaic solar cells or flexible displays. In a few years, it could be used with silicon in computer chips, for example as interconnect wiring or heat spreaders. It also has the potential to benefit other electronic applications, including analog high-frequency transistors, which are used in wireless communications, radar, security systems and imaging. ity,” said Andrew Dereka, Laird Technologies product manager. “As a result, in similar sized form factors, these thermal management systems achieve much higher cooling capacities and have higher heat flux densities than conventional heat sink fan mechanisms. They also have a unique ability to concentrate cooling at the active source and route the heat away without introducing additional heat to the electronics, thus making the overall system more efficient.” Laird Technologies Expands Portfolio with Liquid Cooling Systems Product Line Laird Technologies, Inc. has expanded its thermal management solutions portfolio with the addition of its Liquid Cooling Systems (LCS) product line. Laird Technologies’ liquid cooling solutions are self-contained units that remove large amounts of heat from densely packed electronic environments by re-circulating a coolant to a predefined temperature set point. Temperature stabilization has especially become critical, as require precise temperature control. Being unconstrained, the units save customers time with specifying pumps, heat exchangers and liquid circuits, thereby freeing up resources to focus on end instrument design. The company’s standard product offering includes liquid heat exchanger systems that cool to ambient and re-circulating chillers that cool to well below ambient. The cooling systems are designed to circulate either water, water-glycol (anti-freeze) or transformer oil. Standard heat transfer mechanisms are either liquid-to-air or liquid-to-liquid configurations. “Heat transfer conducted by water is superior over conventional air cooling mechanisms due to its high thermal conductiv18 Caliente Releases New Product Plans Calienté, LLC is proud to announce plans for an upcoming product line, Sensore. Sensore will manufacture sensor technology products. Unlike traditional sensors that measure a single point, Sensore sensors can measure multiple points spread over a larger area. This technology allows measurement of temperature, pressure, moisture, continuity, resistance, surface integrity and chemicals. The Sensore line will share the company’s heater pad technology by utilizing printed thick film, which creates a very flexible, responsive element. “Anytime we can build upon our core products while adding innovation into new products, is a win for us and for our customers,” says Mike, Kelly, president, Caliente. “We’ve listened to our customers and built something that creates a benefit.and provides them with advanced technology.” March/April 2012 www.ElectronicsProtectionMagazine.com http://www.ElectronicsProtectionMagazine.com

Table of Contents for the Digital Edition of Electronics Protection - March/April 2012

Electronics Protection - March/April 2012
Surge Stopper Shields Electronics From Transients Beyond 100 V
The Lowdown on IP Codes – Ingress Protection of Electrical Products
A Case for Safety - AC Arc Fault Circuit Interruption for PV Systems with Microinverters or AC Modules
Enclosure Design: IVC’s new Lightweight Explosion-Proof Camera Enclosure System
Portable Shock and Vibration Protection
Polycase Offers New Options for NEMA 4X Plastic Enclosures
New Circuit Board Shielding from Leader Tech
Laird Technologies Releases new Liquid Cooling Systems Product Line
ASI Releases New UL489 Hydraulic Magnetic Circuit Breakers
PEM C.A.P.S. Captive Panel Screws Offered in Three Mounting Styles26
SolarFocus Releases new SolarKindle Case
Indsutry News
Coherent Integrates Marway’s Power Distribution Solution into Energy Efficient, Direct-Diode Laser System Design

Electronics Protection - March/April 2012