Multi-Objective Optimization of Graphite Heat Spreader for Portable Systems Applications

The advancement made in portable electronic systems has primarily been due to miniaturization of electronic devices. This results in an increase in power density that 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). The challenge of 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. In this paper, a multi-objective optimization is utilized that considers weight of the graphite heat spreader as objective functions. The data is then compared to published data that utilizes graphite in a laptop.