The North Carolina State University researchers have developed an efficient and inexpensive way of cooling electronic devices that generate a lot of heat, such as lasers and power devices. The technique uses a heat-sink made of a copper-graphene composite, which is attached to the electronic device using an indium-graphene interface film. Apparently, copper-graphene composite cools down things 25% faster than pure copper.
Both the copper-graphene and indium-graphene have higher thermal conductivity, allowing the device to cool efficiently. The copper-graphene composite is also low-cost and easy to produce. Copper is expensive, so replacing some of the copper with graphene actually lowers the overall cost.
Samples of graphene composites with matrix of copper were prepared by electrochemical codeposition from CuSO4 solution with graphene oxide suspension. The thermal conductivity of the composite samples with different thickness and that of electrodeposited copper was determined by the three-omega method. Copper-graphene composite films with thickness greater than 200 micron showed an improvement in thermal conductivity over that of electrolytic copper from 380 W/m·K to 460 W/m·K at 300 K (27°C). The thermal conductivity of copper-graphene films decreased from 510 W/m·K at 250K (–23°C) to 440 W/m·K at 350 K (77°C).
Effective medium approximation (EMA) was used to model the thermal conductivity of the composite samples and determine the interfacial thermal conductance between copper and graphene. The values of interface thermal conductance greater than 1.2 GW/m2.K obtained from the acoustic and the diffuse mismatch models and from the EMA modeling of the experimental results indicate that the interface thermal resistance is not a limiting factor to improve the thermal conductivity of the copper-graphene composites.
