Investigation of Carbon Nanotube Performance under External Mechanical Stresses and Moisture

Due to its remarkable properties, carbon nanotube (CNT) was widely used in different areas, especially in electronic packaging for the improvement of the adhesion and thermal conductivity. CNT as an emerging thermal interface material (TIM) is now widely used to improve thermal dissipation in electronic packaging. CNTs suffer from moisture or high interfacial stresses from the mismatch of the thermal expansion coefficient between different layers in packages during fabrication and assembly. Both of these factors have an effect on the material performance of CNTs. To apply CNTs in electronic packaging, it is important for us to understand these loading effects on the thermal performance of CNTs at an atomic level. Molecular dynamics (MD) simulation is a proper method to study these material properties of CNTs. In this study MD simulations were conducted to investigate the thermal conduction of CNT under different conditions, including mechanical stresses and moisture. A series of MD models were built using the Materials studio software (Accelrys, Inc). Based on Fourier's law, thermal conductivities of the SWCNT under different conditions were calculated. The MD simulation results showed that the thermal conductivity of SWCNT subjected to axial stress decreased with the stress changing from the compression to tension. Both of moisture and torsion stress degraded the intrinsic thermal conductivity of CNT. This MD simulation gave a basic understanding of the surrounding effect on thermal performance of CNTs and provided information for the assembly of CNT in electronic packaging.