Microstructure-Dependent Heat Transfer Modeling of Carbon Nanotube Arrays for Thermal Interface Applications

A growing interest has developed in the use of carbon nanotube (CNT) arrays as thermal interface materials (TIMs). However, theoretical modeling of CNT TIMs has largely been limited to semi-empirical methods without detailed consideration of array microstructure, primarily due to the inherent randomness of the microstructure and the computational complexity involved in full atomistic modeling of CNTs. In this work, we report combined thermo-mechanical simulation of CNT arrays with a coarse-grain approach for the mechanics modeling and a thermal network approach for the heat transfer modeling. Parametric studies on the effects of CNT height on the Young’s modulus and buckling load of CNT arrays are reported. The thermal network model is used to estimate the pressure dependence of diffusive and tip contact resistances of CNT arrays; the predictions are compared with thermal resistance measurements using the photoacoustic method. The resulting simulation framework enables a particularly rich and broad thermo-mechanical data set. Selected parametric variations are computed to assess the stress-strain behavior, effective conductivity within the CNT array, and aspects of the contact topologies of the CNT-substrate interface.