An effective method for cooling electronics using graphene-based film has been developed by researchers at Chalmers University of Technology.
The thermal conductivity capacity of the film is four times greater than copper’s. Not only that, but the graphene film can be attached to electronic components made of silicon. This gives favourable performance compared to typical graphene characteristics shown in earlier, similar experimental films.
Today’s electronic systems generate a great deal of heat. This is mostly because the ever-increasing demand on functionality.
Disposal of of excess heat in an efficient manner is indispensable for prolonging electronics lifespan, and also could lead to a significant lowering of energy usage. According to one study, roughly half the energy required to run computer servers is used just for cooling purposes.
A team of researchers led by Chalmers’ Johan Liu, had earlier demonstrated that graphene was able to have a cooling effect on silicon-based electronics. This marked a milestone for researchers doing work on the cooling of silicon-based electronics using graphene.
“But the methods that have been in place so far have presented the researchers with problems”, Professor Liu says. “It has become evident that those methods cannot be used to rid electronic devices off great amounts of heat, because they have consisted only of a few layers of thermal conductive atoms. When you try to add more layers of graphene, another problem arises, a problem with adhesiveness. After having increased the amount of layers, the graphene no longer will adhere to the surface, since the adhesion is held together only by weak van der Waals bonds.
We have now solved this problem by managing to create strong covalent bonds between the graphene film and the surface, which is an electronic component made of silicon.”
The stronger covalent bonds are the result of the addition of a property-altering molecule to the graphene.
After tested various additives, the Chalmers researchers concluded that an addition of (3-Aminopropyl) triethoxysilane (APTES) molecules has the optimal effect. When heated and put through hydrolysis, it creates silane bonds between the graphene and the electronic component.
Using silane coupling doubles the thermal conductivity of the graphene. The team showed that the in-plane thermal conductivity of the graphene-based film, with 20 micrometer thickness, can achieve a thermal conductivity value of 1600 W/mK, quadruple that of copper.
Yong Zhang, Haoxue Han, Nan Wang, Pengtu Zhang, Yifeng Fu, Murali Murugesan, Michael Edwards, Kjell Jeppson, Sebastian Volz andJohan Liu
Improved Heat Spreading Performance of Functionalized Graphene in Microelectronic Device Application
Advanced Functional Materials DOI: 10.1002/adfm.201500990
Illustration: Riley Porter/flickr
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