ALESSIO MUNARI
PhD Research Postgraduate (2005-2008)

e: alessio.munari@ul.ie

t: +353-61-202471

Alessio Munari has been awarded a postgraduate scholarship to study at Stokes, funded under Enterprise Ireland's Industry-Led Research Programme in Power Electronics.

PhD Project Title: Characterisation of Nanotube Thermal Interface Material

Background: Packaging of semiconductor power electronic devices is a challenge due to progressive increases in the power level of operating devices. In the near future, power levels will rise to about 200W, an effective heat flux of 80W/m2 (~500 W/in2). In contemporary high-power electronics modules, the heat generated by the power device is transferred to the ambient environment by attaching a heat sink or heat spreader to the semiconductor package. One of the main limitations in power semiconductor device cooling is the microscopic unevenness and non-planarity between the mating surfaces – die and heat sink – which prevent the two surfaces from forming a contact with low thermal resistance. Thermal interface materials are therefore used to provide a reliable heat conduction path between the two solid surfaces. Commercially available thermal interface material (TIM) has thermal conductivity in the range of 10-30 W/mK. There is a clear imperative to fabricate and characterise an electrically isolated thermal interface layer using different types of nanotubes and nanowires as a filler material in order to enhance the thermal conductivity of the present state of the art material.

This project is being performed as part of a larger effort, in collaboration with the Tyndall National Institute, with the overall objective of developing an electrically insulated die level thermal interface material system. It is proposed that the scholarship will involve extensive interaction with Tyndall in order to gain experience in the development of nanotube materials. In addition, thermal, electrical and mechanical characterisation will be conducted. Thermal characterisation will involve measurement of both the thermal conductivity of the bulk material and its contact resistance when deployed between two solid surfaces. To this end, a novel characterisation facility will be designed, fabricated and commissioned in order to extract thermophysical properties from the response of the material to transient thermal stimuli. Infra-red micro-spectroscopy will be used to obtain thermal profiles through the material with high spatial and temporal resolution. Furthermore, thermal multiscale and percolation simulations will be performed, and these will be compared to experimental results in order to create a model for the thermal characteristics of the material. The outcome of this project will be the development of a nanotube material with a comprehensive understanding of its thermal, electrical and mechanical characteristics. A technology demonstrator will also be constructed in conjunction with Tyndall.

The research project is being performed at the Stokes Institute, University of Limerick, in collaboration with the Tyndall National Institute.

Publications to date

Razeeb, K.M., Munari, A., Dalton, E., Roy, S. and Punch, J., 2007, “Thermal Properties of Carbon Nanotube-Polymer Composites for Thermal Interface Material Applications”, submitted to the ASME-JSME Thermal Engineering and Summer Heat Transfer Conference, HT2007-321596, Vancouver, BC, Canada, July 8-12.