Development of Ultra-Thin Thermal Ground Planes by Using Stainless-Steel Mesh as Wicking Structure

Abstract

Ultra-thin thermal ground planes (TGPs), which utilize phase-change heat transfer to achieve high performance heat spreading, are of great importance for thermal management of thickness-constrained microsystems. However, both fabrication challenges and performance limitation are encountered when the TGP thickness reduces to 0.5 mm. In this letter, we introduce an ultra-thin TGP by bonding single-layer stainless steel mesh with copper micropillars via electroplating to form a hybrid wicking structure, which enables both high capillary pressure and low flow resistance. Copper-cladded kapton is used as the casing material, and electroplated copper pillars are used to support the casing over a vapor space. The assembled TGP has an active area of 10 cm × 5 cm with a total thickness of 0.28 mm. This TGP can operate with a heat load up to 7.9 W over a heating area of 8 mm × 8 mm, rendering an effective thermal conductivity of 1398 W/m-K.