Wonder material Graphene has one more use – as a coolant for components in electronic circuitry including chips – a new research has revealed.
A team of scientists led by Johan Liu, professor at Chalmers University of Technology, had shows two years ago that Graphene can have a cooling effect on silicon-based electronics currently in use. Taking this forward, researches at the same university have developed a method for efficiently cooling electronics using graphene-based film.
Researchers say that their film has a thermal conductivity capacity that is four times that of copper and as the graphene film is attachable to electronic components made of silicon, it can be used without any special lubricants. Further, this also favours the film’s performance compared to typical graphene characteristics shown in previous, similar experiments.
Two years back when scientists had first shown the cooling properties of graphene, the methods used at the time were rather crude and had many problems according to Johan Liu.
Soon after researchers conducted a few experiments, it was apparent that the 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 more layers graphene are added, 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,” Johan Liu says.
The stronger bonds result from so-called functionalisation of the graphene, i.e. the addition of a property-altering molecule. Having tested several different additives, the Chalmers researchers concluded that an addition of (3-Aminopropyl) triethoxysilane (APTES) molecules has the most desired effect. When heated and put through hydrolysis, it creates so-called silane bonds between the graphene and the electronic component.
Moreover, functionalisation using silane coupling doubles the thermal conductivity of the graphene. The researchers have shown that the in-plane thermal conductivity of the graphene-based film, with 20 micrometer thickness, can reach a thermal conductivity value of 1600 W/mK, which is four times that of copper.
Electronic systems available today accumulate a great deal of heat, mostly due to the ever-increasing demand on functionality. Getting rid of excess heat in efficient ways is imperative to prolonging electronic lifespan, and would also lead to a considerable reduction in energy usage. According to an American study, approximately half the energy required to run computer servers, is used for cooling purposes alone.
“Increased thermal capacity could lead to several new applications for graphene,” says Johan Liu. “One example is the integration of graphene-based film into microelectronic devices and systems, such as highly efficient Light Emitting Diodes (LEDs), lasers and radio frequency components for cooling purposes. Graphene-based film could also pave the way for faster, smaller, more energy efficient, sustainable high power electronics.”