Development of Ultra-Thin Thermal Ground Plane with High Performance Electroplated Wick

Abstract

With continuously increased power and power density, heat pipe and vapor chamber are widely used for electrical device cooling. However, to integrate them into a package for more efficient thermal dissipation is the most critical topic for next generation semiconductor device cooling. Using electroplating process for forming micro-wick structure on the copper plate is the most reasonable process for package level thermal ground plane development, which could be directly produced on the copper clad laminate substrate. The dendritic copper wick resulting from electroplating has the benefit of high performance, gravity against ability, low cost, clean, fast process and the most important thing - using existing substrate manufacturing process. In this paper, different electroplating current density and process time are evaluated for forming pore and dendrite to be the wick. Capillary limit is the dominate factor for the performance of a thermal ground plane, which is proportional to the capillary performance index. The produced wick has the index up to 0.5 um, which is as good as the high performance sintered and composite wicks; the thermal ground plane produced by the electroplated wick has the potential to have high effective thermal conductivity.