Interfacial Thermal Resistance Measurements of Solution Deposited CNT Films on Copper Substrates

Abstract

Carbon nanotubes (CNTs) have been regarded as one of the most promising materials for electronics applications during the past two decades according to their outstanding electrical properties. However, the fabrication method of CNTs is an important matter since the materials need to be managed easily as well as placed precisely when being applied in electronics. Xu and Hamilton [1] - [2] found an effective solution based application method which can meet those requirements while the process is done at room temperature. This is better than some of the most commonly found methods, such as chemical vapor deposition (CVD), which needs high fabrication temperatures. High fabrication temperatures can cause deformation due to any coefficient of thermal expansion (CTE) mismatches. Their groundbreaking work showed that the electrical properties of CNTs didn’t have a large influence during the fabrication process through both experiment and modeling. However, the thermal interfacial behavior of solution deposited CNT films needed to be characterized. In this thesis, the interfacial thermal impedance of the CNTs, which were fabricated by the method of Xu and Hamilton [1] - [2] was studied. A TIM Tester Model 1400 using ASTM D5470 method by Analysis Tech Inc. was used to characterize the thermal resistance of inkjet CNT films. Copper Alloy 110 disks were used as fabrication substrates on which the ink was printed. The volumes of CNT dispersion were controlled for 2 mL, 4mL, 6 mL and 8 mL. Two groups of samples which were single sided and double sided were tested under four different pressures: 20 psi, 40 psi, 60 psi and 80 psi. Every single test was repeated for 10 times in order to obtain reliable data. The average heat resistances of the last five tests are shown in Table 3.10. All data is listed in appendix. A group of bare copper substrates without MWNTs films was also tested under same conditions as a control reference. The results show a heat insulating, electrical conducting CNTs film using this kind of solution-based application method was obtained.