Planar-Radial Structured Thermoelectric Cooler for Local Hot Spot Cooling in Mobile Electronics

Abstract

In recent years, clock speed and power density have increased rapidly, improving the performance of mobile devices, and thus, thermal management issues for local hot spots of chips are increasing. Dynamic thermal management (DTM) through frequency modulation and passive cooling components such as heat pipes is currently being used as a cooling strategy for mobile devices. However, DTM has an inverse relationship with chip performance, and passive cooler occupy too much space for local hot spot cooling. From the point of view of local hot spot cooling, a solid-state thermoelectric cooler (TEC) has the advantage of enabling on/off control and site-specific cooling. However, most of the research on TECs focuses on the material or interfacial properties of TECs, not the design rule or structure of TECs for practical applications. This study proposes an active cooling device using a TEC with a unique planar-radial structure that can selectively cool only locally generated hot spots and minimize form factor designs with 2D structures, making this cooling device highly applicable to mobile devices. A 5-pair TEC using the optimized TE leg thickness (n-Bi <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Te <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> 5.05 μm and p-Sb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Te <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> 5.45 μm) and radial structure enhanced the Peltier effect and confirmed the maximum junction temperature difference of 2.4 °C. By adopting a hybrid cooling system combining active and passive coolers in a mobile device, we obtained an effective cooling area ratio of 4 and a cooling effect (~3.87 °C).