Practical analytical steady-state temperature solution for annealed pyrolytic graphite spreader: Partial results

The capability to efficiently transfer the heat away from high powered electronic devices is a ceaseless challenge. More than ever, the aluminium or copper heat spreaders seem less suitable for maintaining the component sensitive temperature below manufacturer operating limits. Emerging materials, such as Annealed Pyrolytic Graphite (APG), propose a new alternative to conventional solid conduction without the gravity dependence of a heat-pipe solution. Unfortunately, the ultrahigh performance rising of APG core is restricted to in-plane thermal conductivities which can be 200 times higher than its through-the-thickness conductivity. So a lower-than-anticipated cross-plane thermal conductivity or a higher-than-anticipated interlayer thermal resistance would compromise APG-based material as efficient heat spreaders. In order to analyse the sensitivity of these parameters on the effective thermal performances, an analytical model for predicting the temperature distribution over an APG flat-plate was developed. To demonstrate its relevance, it was compared to numerical simulations for a set of boundary conditions. The comparison shows a high agreement between both calculations to predict the centroid and average temperatures of heating sources. The pertinence of the practical expression used for modelling APG flat-plates thermal behaviour appears quite relevant for early stage design, our concern.