Graphene nanoflake-based films developed as thermal interface materials

Monday 23 May 2016
Graphene nanoflake-based films developed as
thermal interface materials

IDTechEx
Cambridge, UK

Graphene nanoflake-based films developed as
thermal interface materials
by Rachel
Gordon, Technology Analyst, IDTechEx

Researchers at Chalmers University of
Technology in Sweden have developed a new approach to cooling electronics using
graphenenanoflake-based film.

Heat dissipation in electronics and
optoelectronics is a major obstacle to further technology development. It
limits further miniaturisation, power, performance and reliability. The
escalation of power densities in electronic devices has made efficient heat
removal a crucial issue for progress in information, communication, energy
harvesting, energy storage and lighting technologies, according to IDTechEx
Research report Thermal InterfaceMaterials 2016-2026.

Theoretical studies have indicated
that the graphene-based thermal interface materials can outperform those with
carbon nanotubes, metal nanoparticles and other fillers owing to graphene’s
geometry, mechanical flexibility and lower interfacial thermal resistance at
the graphene–base material interface.

XG Science have semi-commercial
results improving the thermal conductivity of polycarbonate using graphene nanoplatelets, with higher aspect
ratios yielding better results, according to IDTechEx Research report Graphene, 2D Materialsand Carbon Nanotubes 2016-2026.

Johan Liu, Professor of Electronics
Production at Chalmers University of Technology in Sweden, and his team
described experiments in which they managed to increase the efficiency of heat
transfer by 76 per cent. The graphene-based film was enhanced by adding
functionalised amino-based and azide-based silane molecules.

“This is the first time that such
systematic research has been done,” Liu said. “The present work is much more
extensive than previously published results from several involved partners and
it covers more functionalisation molecules and also more extensive direct
evidence of the thermal contact resistance measurement.”

They are now getting closer to
pilot-scale production. There are many potential uses of this kind of film.
There has been an increasing interest in new and advanced materials for thermal
interface materials (TIM) and heat conduction in all areas of the electronics
market, including aerospace, automotive, consumer, communications, industrial,
medical, and military.

Aiping Yu at the Center for Nanoscale Science and Engineering,
Departments of Chemistry and Chemical and Environmental Engineering, University
of California Riverside has researched Graphite Nanoplatelet−Epoxy Composite Thermal
Interface Materials. Fully exfoliated graphene has been shown to outperform
SWCNTs. Further improvements can stem from improving the chemistry between
graphene and the host polymer.

Graphite has been commercially
available as a TIM for 10 years. It does not change with time or temperature
cycling by releasing volatiles or creeping. This means in LED lighting
applications there is no fogging. The high stability means it is used in
chip-testing equipment. It can work at higher temperatures than polymeric TIMs,
so enables the performance of higher power density lightingdisplays. It is
electrically conductive, so for some applications a dielectric coating must be
used, to make it electrically insulating and prevent short-circuiting.

Pyrolytic Graphite Sheet (PGS) is a
thermal interface material made from a highly oriented graphite polymer film.
It is synthetically made and has high thermal conductivity (700-1950 W/m.K). It
is very thin, making it suitable for providing thermal management in limited
spaces, and very lightweight. This material is flexible and can be cut into
customizable shapes.