Dr. Kaveh Azar

Thermal Design and Characterization of Flat Miniature Heat Pipes . by Dr. Kaveh Azar,

Micro & Mini Flat Heat Pipe (MMFHP) can be used at the base of a heat sink, coldplate  or on top of an electronic package to effectively disperse the heat over the entire available surface for cooling. Therefore, they can become and attractive option for managing spreading resistance on low and high power chips when the solid is no longer adequate to address the problem. Hence, thermal design and characterization of MMFHPs requires special attention since up front design of these heat pipes play a major role not only in their thermal performance but also final cost of product.

In this presentation   design, manufacturing, characterization and modeling of MMFHPs will be presented. Salient issues such as the shape of the channels required to provide the best capillary and manufacturing challenges to fabricate them will be reviewed. The presentation will highlight the results of an experimental work of a prototypic MMFHP whose results are used to develop models for thermal design in addition to the experimental characterization. In this study water was used as the working fluid.  The presentation also includes the comparison between the heat pipe thermal resistance to the heat conduction thermal resistance of a copper plate having the same dimensions as the tested MMFHP.

The presentation concludes with showing a model, which allows for the simulation of different shapes of microchannels to predict the maximum heat transfer capacity of the flat heat pipe. In addition, important parameters such as optimal fluid mass, fluid flow and thermal parameters can be readily obtained from these models that are essential for the design and fabrication of the Flat Heat Pipes. The results of several experiments will further corroborate that the use of higher conductivity materials or MMFHPs on top of the package or at the base of a heat sink or coldplate will significantly reduce the temperature gradient, hence, spreading resistance. The mitigation and management of such temperature gradients  will enable the deployment of higher power devices with effective thermal management.