A North Carolina State University researcher has developed a more efficient, less expensive way of cooling electronic devices – particularly devices that generate a lot of heat, such as lasers and power devices, like current generation smartphones.
The technique uses a “heat spreader” made of a copper-graphene composite, which is attached to the electronic device using an indium-graphene interface film “Both the copper-graphene and indium-graphene have higher thermal conductivity, allowing the device to cool efficiently,” says Dr. Jag Kasichainula, an associate professor of materials science and engineering at NC State and author of a paper on the research. Thermal conductivity is the rate at which a material conducts heat. In fact, Kasichainula found that the copper-graphene film’s thermal conductivity allows it to cool approximately 25 percent faster than pure copper, which is what most devices currently use.
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In the research, 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 250 K (–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 indicated that the interface thermal resistance is not a limiting factor to improve the thermal conductivity of the copper-graphene composites.
Which in English aims to reflect on the fact that dissipating heat from electronic devices is important, because devices become unreliable when they become too hot. We’ve all seen the adverse effects of over heating. The paper also lays out the manufacturing process for creating the copper-graphene composite, using an electrochemical deposition process. “The copper-graphene composite is also low-cost and easy to produce,” Kasichainula said. “Copper is expensive, so replacing some of the copper with graphene actually lowers the overall cost.”
The paper, “Thermal Conductivity of Copper-Graphene Composite Films Synthesized by Electrochemical Deposition with Exfoliated Graphene Platelets,” is published in Metallurgical and Materials Transactions B. The research was funded by the National Science Foundation.
Published Date: Apr 10, 2012 10:43 am | Updated Date: Apr 10, 2012 10:43 am