Electronic systems available today produce a great deal of heat, mostly due to the ever-increasing demand on functionality. Getting rid of excess heat in efficient ways is critical for both prolonging electronic lifespan and to reduce energy usage. Studies have shown that approximately half the energy required to run computer servers is for cooling purposes alone.

Now, researchers at Chalmers University of Technology have developed a method for efficiently cooling electronic circuitry using a graphene-based film. The film has a thermal conductivity capacity that is four times that of copper.

The increased thermal capacity could lead to several new applications for graphene. Graphene-based film would be highly appropriate for cooling microelectronic devices and systems including highly efficient Light Emitting Diodes (LEDs), lasers and radio frequency (RF) components. Graphene-based film could also pave the way for faster, smaller, more energy efficient, sustainable high-power electronics.

The new graphene film adheres well to silicon components, demonstrating improved performance compared to graphene characteristics from previous research work, when a research team led by Johan Liu, professor at Chalmers University of Technology, were the first to show that graphene can have a cooling effect on silicon-based electronics. This was the starting point for researchers conducting research on the graphene cooling for silicon-based electronics.

“…[However] those methods cannot be used to rid electronic devices of great amounts of heat, because they consisted only of a few layers of thermal conductive atoms,” Johan Liu says. Additionally, after increasing the number of layers, the graphene no longer adhered to the surface.

The team has now solved the problem by creating strong covalent bonds between the graphene film and the surface, in this case an electronic component made of silicon.

The stronger bonds result from what the team calls “functionalization” 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 offered the most significant benefits. When heated and put through hydrolysis, it creates what is called a silane bond between the graphene and the electronic component.

Functionalization using silane coupling actually doubles the thermal conductivity of the graphene. The researchers have shown that the in-plane thermal conductivity of graphene-based film, with 20 µm thickness, can reach a thermal conductivity value of 1600 W/mK, which is four times that of copper.

The results were recently published in the renowned journal Advanced Functional Materials. The research was conducted in collaboration with Shanghai University in China, Ecole Centrale Paris and EM2C – CNRS in France, and SHT Smart High Tech AB in Sweden.

While graphene production was originally seen as prohibitively expensive, new research at institutions such as MIT and the University of Michigan show promise for large-scale graphene production through chemical vapor deposition and roll-to-roll manufacture.

Source: Chalmers University and Cleantech Concepts