Vertically Aligned Multi-Walled Carbon Nanotube Arrays as Thermal Interface Materials and Measurement Technique

State-of-the-art thermal interface materials are briefly reviewed with an emphasis on the emerging trend of using carbon nanotubes to increase interface thermal performance. Vertically aligned multi-walled carbon nanotube (MWCNT) arrays were grown and applied as thermal interfacial enhancing materials. It is expected that the highly thermally conductive channels directly bridging the mating surfaces would significantly enhance the interface thermal conductance. We extended the all-optical pump and probe phase sensitive transient thermo-reflectance (PSTTR) method and used it to measure the interfacial properties of a three-layer sample of a vertically aligned MWCNT array grown on silicon (Si) substrate dry adhered to a glass plate. The dominant thermal resistance is identified as the dry adhered MWCNT-glass interface with a thermal conductance of ~5.9 × 104 W/m2·K, compared with MWCNT-Si interface of almost two orders of magnitude higher. Tentative explanations on the difference in the two interfaces and ways for future improvements are provided. The PSTTR measurement principle and issues are also discussed in the context.