Multi Objective Optimization Of Graphite Heat Spreader For Portable Systems Application

The advancement made in portable electronic systems has primarily been due to miniaturization of electronic systems. This in turn leads to an increase in power density which leads to higher temperatures and formation of hot spots. There is a temperature specification of system surfaces for human comfort (such as the surface close to a keyboard on laptops). Challenge in cooling portable devices is that there is not enough room to accommodate heat sinks. It is therefore important to have heat spreaders that can transfer the heat from critical devices to regions where cooling is available. Traditionally, copper has been the best heat spreader due to its high thermal conductivity. However, copper has a relatively high density and correspondingly high weight. Graphite is a suitable alternative. Recent advances in graphite technology have resulted in fairly high conductivity in the planar directions. In spite of these advances, the cost of graphite is an issue. There are many methods for solving these problems, and depends on the type of the system used. The two basic types of methods to analyze the system are: 1) Experimental method, 2) Simulation using a computer aided tool.In this research project simulation using the thermal modeling tool, Icepak; is considered. The prototype model of the laptop is designed, boundary conditions are applied and analysis is done. The results so obtained in this simulation give a detailed idea of the amount of the heat to be dissipated from the system and the locations of the hotspots. Graphite heat spreader is included in the design and simulated, the results interpret that the graphite heat spreader improves the thermal performance of the system. Graphite heat spreader forces the heat flow only through the plane which decreases the overall global temperature and also it reduces the hotspots in the system as heat spreader acts almost like insulator through the thickness. Graphite is very expensive so the size and shape of the heat spreader has to be optimized. Thus, this research project contributes to the enhancement of thermal performance of the laptop. Though this may not be the final solution but definitely can be considered for further studies which may lead to a more efficient design.