Assessment of Cooling Microelectronics using Piezoelectric Bimorphs

Abstract

As the heat generation of processors for notebook computers continues to increase, so does the need for smaller, more efficient cooling systems. The cooling capabilities of the piezoelectric bimorph were assessed to determine if it could fulfill this need. This was accomplished by first analyzing the current methods used to cool notebook computers using heat transfer theory. Using this data and the known properties of the cooling system, two techniques were applied to try and predict the temperature profile of a processor. By predicting this profile it would be possible to determine the amount of convective cooling required to dissipate the heat for a specific processor.

The cooling capabilities of the piezoelectric bimorph were assessed by looking at the theoretical volumetric flow rates and flow velocities it was able to produce through bulk air flow. It was found that the flow rate increases while the flow velocity decreases as the length of the bimorph increases. This was further supported by experimental testing with a heat source that could be regulated to output a specified amount of power. Testing also showed that there exists an optimal bimorph length and optimal gap between the bimorph and heat source, where maximum cooling is obtained.

By comparing the cooling requirements of a processor and the cooling capabilities of a piezoelectric bimorph it was found that the bimorph's capabilities are not sufficient for current high power microelectronics. Instead the bimorph was found to be comparable to a heat sink for an older Pentium® processor, which means the bimorph could be viable for low power devices.