SGER: Exploratory Study of Imbedded Carbon Nanotubes to Improve Thermal Performance of Flexible Electronics Packages

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Large heating loads in high performance microelectronics often require high thermal conductivity materials to maintain the health and performance of the electronics. In flex-based circuitry, where the need for flexibility limits the use of such highly conductive but stiff materials like diamond, thermal vias or solder bumps can only slightly enhance the thermal performance of the polymeric substrates. Recent studies suggest that carbon nanotubes (CN) can dramatically improve the thermal management of flex circuits. Preliminary results indicate that the nanoscale diameter and high aspect ratio of the highly conductive CN (~ 3000 W/mK in the axial direction) allow CN/polymer composites to achieve unusually high thermal conductivities, unlike polymers composited with the traditional microscale particles. Initial tests performed at our laboratory on a commercial epoxy composited with 1 wt% of randomly dispersed CN showed that the thermal conductivity was enhanced by a factor of 1.7, while theory predicts this number to reach 100 if the CN were aligned.Based on the results of our limited experiments, we propose to fabricate and evaluate the thermal performance of two different types of CN/Polyimide composites with (a) randomly oriented and (b) vertically aligned CN. The proposed project is both high-risk and high-payoff. It is especially suitable for SGER funding due to the fact that the physical properties of CN are not well understood and the microelectronics industry can potentially benefit tremendously from the highly conductive polymer composite developed by the project. Intellectual Merit of Proposed ActivityThe proposed project is important to the fields of nanotechnology and microelectronics. It not only impacts the design of future electronics packaging but also significantly enhances our current knowledge of CN materials. The proposed work is very novel, original, and organized, and the proposal team is well qualified to perform the required work. The PI's have extensive experience in such diverse but complementary areas as MEMS, simulation, and heat transfer. Additionally, the team has access to a complete line of micro fabrication facilities in an on-campus cleanroom. Broader Impacts of Proposed ActivityThe proposed project will generate significant educational opportunities for students at both the college and high school levels. The UA graduate and undergraduate students supported under this effort will benefit greatly from the experience of carrying out the proposed nanotechnology research. The K-12 students and teachers recruited for the project will become more aware of nanotechnology, which can lead to more K-12 students pursuing science and engineering as a career path. The PI will actively recruit underrepresented students through his current role as a mentor for women and minority engineering students. The processing techniques developed and equipment purchased for the project will significantly enhance the capability of the multi-user micro fabrication facilities at UA.