Abstract
Thermal material properties play a fundamental role in the thermal management of microelectronic systems. The porous nature of carbon nanotube (CNT) arrays results in a very high surface area to volume ratio, which makes the material attractive for surface driven heat transfer mechanisms. Here, we report on the heat transfer performance of lithographically defined micropins made of carbon nanotube (CNT) nanofoam, directly grown on microhotplates (MHPs). The MHP is used as an in situ characterization platform with controllable hot-spot and integrated temperature sensor. Under natural convection, and equivalent power supplied, we measured a significant reduction in hot-spot temperature when augmenting the MHP surface with CNT micropins. In particular, a strong enhancement of convective and radiative heat transfer towards the surrounding environment is recorded, due to the high aspect ratio and the foam-like morphology of the patterned CNTs. By combining electrical characterizations with high-resolution thermographic microscopy analysis, we quantified the heat losses induced by the integrated CNT nanofoams and we found a unique temperature dependency of the equivalent convective heat transfer coefficient, Hc. The obtained results with the proposed non-destructive characterization method demonstrate that significant improvements can be achieved in microelectronic thermal management and hierarchical structured porous material characterization.
Highlights
IntroductionIt is well known that carbon allotropes and their derivatives possess superior thermal properties.[13]
The performance of microelectronic and optoelectronic devices is often severely limited by high temperatures and insufficient heat management.[1,2] when considering device fabrication and packaging, it is important to select materials based on their thermal performance
By combining electrical characterizations with high-resolution thermographic microscopy analysis, we quantified the heat losses induced by the integrated carbon nanotube (CNT) nanofoams and we found a unique temperature dependency of the equivalent convective heat transfer coefficient, Hc
Summary
It is well known that carbon allotropes and their derivatives possess superior thermal properties.[13]. By combining the nanoporous morphology of vertically aligned CNTs with different nanoscale conformal coatings, we have the unique opportunity to control the functionality and tune the material properties.[19] it has been demonstrated that by using thin coatings of only a few nanometers we can give a high elastic recovery to the CNT nanofoam while maintaining a high compliancy.[20] This makes the nanofoam promising for thermal interface material, replacing the contaminating and difficult to apply pastes They have great potential to be used as low weight framework for a broad range of applications, from three-dimensional carbon electrodes,[21] to thermoacoustic transducers,[22] to thermochromic displays,[23] to nanotexturing for solar devices.[24]. The present work demonstrates the effectiveness of lithographically defined CNT nanofoam structures as on-chip cooling solutions for consumer electronics
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