Characterization Of The Performance Of Thermal Interface Materials Based On Nanotube/Nanowire Arrays

With rapidly increasing power densities in electronic devices,advanced thermal interface materials(TIMs)with higher thermal conductance become a crucial issue to meet the heat dissipation requirements.Vertically aligned carbon nanotube(CNT)arrays and copper nanowire(CuNW)arrays are promising for advanced thermal interface materials(TIMs)since they possess high mechanical compliance and high intrinsic thermal conductivity.An experimental apparatus based on phase sensitive thermal reflectance thermometry is designed for the characterization of the performance of CNT array thermal interface materials.The thermal properties of TIMs are obtained by MATLAB numerical analysis of the experimental data.Previous work has been revealed that less than 10%of the tubes were effectively in contact with the mating surfaces.Therefore,improving the contact quality is critical in achieving better thermal performance at interface.Hence,transferred the vertically aligned CNT arrays were transferred to a flexible polymer substrate to their contact to the Cu surface effectively.Most of the previous work was conducted with smooth surfaces such as glass and Si.However,the surfaces in real applications are usually coarse,and the thermal resistance is contributed by the voids between interfaces.In this work,the thermal performances of CNT arrays with controlled surfaces roughness were systematically studied.The nanoscale feature of CNTs and their unique mechanical properties were expected to ensure their accommodations at rough interfaces,and make effective thermal contact.However,our work reveals that the roughness of the target surfaces could significantly affect the contact of CNT arrays,as the result of the interaction between the nanotubes.On the other hand,CuNW arrays,due to the fabrication technique,can achieve much higher array density and free of entanglement between the wires.Therefore,CuNW array TIMs are expected to have a better thermal performance than CNT array TIMs.Our work could provide guidelines to enhance the contact thermal conductance of new TIMs and to shed a light on future high performance TIM development.