Graphene provides efficient electronics cooling

9. července 2013 v 8:01 |  Led ceiling light
A layer of graphene can reduce the working temperature in hotspots inside a processor by up to 25 percent - which can significantly extend the working life of computers and other electronics.

An international group of researchers, headed by Chalmers University of Technology in Sweden, are the first in the world to show that graphene has a heat dissipating effect on silicon based electronics.

?"This discovery opens the door to increased functionality and continues to push the boundaries when it comes to miniaturising electronics," said Chalmers Professor Johan Liu who heads the international research project.

Modern electronic systems generate a great deal of heat,

above all due to the constantly increasing demand for more and more functionality. It is important to be able to remove the heat generated in an efficient way to maintain the long life of the system.
LED downlight
One rule of thumb is that a 10-degree Celsius increase in working temperature halves the working life of an electronics system.

During the study, the researchers focused on reducing the temperature in the small area where the electronics work most intensively such as inside a processor, for instance.

These tiny hotspots are found in all electronics. Size wise, they are on a micro or nano scale, in other words a thousandth of a millimetre or smaller.

The normal working temperature in the hotspots we have cooled with a graphene layer has ranged from 55 to 115 degrees Celsius. We have been able to reduce this by up to 13 degrees, which not only improves energy efficiency, it also extends the working life of the electronics.

Efficient cooling is a major challenge in many different applications, such as automotive electronics, power electronics, computers, radio base stations and in various light emitting diodes, or LED downlight.

In automotive electronics systems, any single device in the ignition system can pump out up to 80 W continuously and in transient stage up to 300 W (within 10 nanoseconds). LED devices can have a thermal intensity almost on a par with the sun, up to 600 W/cm2 due to their extremely small size.

Superior cooling of electronics can deliver tremendous advantages. According to a recent study in the US based on data from 2006, around 50 percent of the total electricity used to run data servers goes on cooling the systems.

The research, that has been undertaken in partnership with the Hong Kong University of Science and Technology, Shanghai University in China and Swedish company SHT Smart High Tech AB, has been published in the scientific publication Carbon.

Indium tin oxide (ITO) has become a standard material in light-emitting diodes, flat panel plasma displays, electronic ink and other applications because of its high performance, moisture resistance, and capacity for being finely etched.

But indium is also rare and expensive, and it requires a costly deposition process to make opto-electronic devices and makes for a brittle electrode. Replacing indium as the default material in transparent electrodes is a high priority for the electronics industry.

The TiO2/Ag/TiO2 composite electrode multilayer film the researchers studied has been well characterised in the literature, but the team optimised both the thickness of the silver layer and the manufacturing process so that the multilayer film has a low sheet resistance and high optical transmittance, both properties necessary for highperformance.

The researchers created films with a sheet resistance as low as one sixth of that achieved by previous studies, while maintaining approximately 90 percent optical transmittance.

With the choice of an underlying substrate made of polyethylene napthalate (PEN) -- a sturdy polymer used in a variety of applications from bottling carbonated beverages to manufacturing flexible electronics -- the researchers added additional durability.
 

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