Improving thermally-limited burst performance of microprocessors using high conductivity graphite spreaders
Ravishankar Srikanth, Nandigama Bhargav · 2021
Mobile personal computing comes in various form factors such as clamshells, convertibles, tablets, dual screen laptops etc. These systems are no longer used for simple tasks such as video playback or reading but are expected to perform under several multi-tasking and content creation applications. Snappiness of response such as opening a spreadsheet or browser window quickly are dictated by how much burst power the thermal envelope of microprocessor can handle in addition to the steady state power it is designed for. In thin and light form factors, with weight and thinness of thermal solution being critical, graphite spreaders are considered due to their flexibility to route, assemble and inherent high conductivity. In this paper, we study the transient behavior of directly attaching graphite on existing passive spreaders such as copper plates. A detailed Computational Fluid Dynamics (CFD) model of a detachable tablet device was constructed, and simulations were performed for various cases. Results indicate that, using high conductivity low density graphite can provide up to 40% improvement in burst performance of processors. In addition, the concept of having a direct flexible graphite spreader as the main thermal spreader was also studied to enable thinner and lighter thermal envelopes. It was observed that graphite spreaders have a potential for improving burst performance in low power mobile computing form factors of current and future generations.