Experimental study of multidimensional wire-plate/sintered hybrid mini heat pipes for electronics

Abstract

The experimental study concerning new two and three dimensional mini heat pipes, proposed for cooling electronic components in printed circuit boards is presented. These heat pipes can capture the heat from electronic components and conduct it to the cabinet wall, through the narrow spaces available between boards. As the location and dissipation of the electronic components vary, several different heat pipes are necessary for a complex electronic equipment, which should operate at different temperatures and orientations. A hybrid wick structure, composed by sintered copper powder and wire-plate technologies along the device are proposed. Four different types of hybrid mini heat pipes, in up to three generations, were designed and constructed, using diffusion bonding fabrication technique. Two different testing setups were developed. First, the thermal performance of the hybrid heat pipes was accessed, resulting in the selection of the appropriated working fluid and its volume. Second, the devices were tested in rigs that mimic actual electronic equipment geometries and operational conditions. The several hybrid multidimensional heat types worked well, even against gravity. Besides, the present work shows that the wire-plate wick structure, up to this date considered only in academic studies, resulted in very flexible heat pipes, able to start up easily, in several adverse geometric and gravitational conditions, especially when combined with more conventional technologies, such as sintered porous media. Besides, the fabrication process developed that includes diffusion bonding, can be considered a novelty.