Graphene/Copper Heterostructures for Thermal Management

Abstract

With the technological developments in the microelectronic systems used in military computers, the number of circuit elements per unit area increases enabling the production of faster and more efficient processors. To be able do this, these circuit elements are required to withstand higher current densities and thus higher temperatures are generated by Joule heating. Overheating (in general non-uniformly) at some specific areas in chips, adversely affects the performance and reliability of electronic devices. Therefore, it is critical to control temperature distribution within the chip and the efficient heat management is one of the most important issues for today’s high power electronic devices and thus, every improvement in the area is very valuable. In this context, to increase the lateral heat conduction, the graphene-copper heterostructures (graphene-copper laminate structures for heat spreaders and graphene-copper porous structures for heat sinks/exchangers) are studied both experimentally and through computational studies. For the experimental studies, first graphene is synthesized on Cu via CVD. The thermal diffusivity measurements, which were performed through the laser flash method, show that the presence of graphene did not make a contribution to the thermal properties in graphene-copper laminate system. These results were also confirmed by the computational studies which showed that to see an increase in the thermal conductivity, the ratio of graphene/copper should be higher than 1/20. Within the scope of these findings, 3D graphene-Cu porous heterostructures are studied to increase the graphene’s contribution to the thermal diffusivity. 3D graphene-Cu porous heterostructures showed an increase in the thermal diffusivity by 10% at the room temperature and 30% at 400 °C. Graphene’s positive effect on the thermal properties is attributed to its high thermal conductivity and the protection of Cu structure against the oxidation at higher temperatures. Our studies show that the graphene-copper porous structures developed in this study can be a good lightweight candidate for a heat sink/exchanger with corrosion resistant and high thermal conductivity.