Vapor chambers operate under the same working principles as heat pipes. They have a metal enclosure that is vacuum-sealed, an internal wick structure attached to the inside walls, and move the liquid around the system using capillary action. Unlike heat pipes, vapor chambers can achieve an impressive 60:1 width-to-height aspect ratio (flattened heat pipes are on the order of 4:1).
Vapor Chambers When You Need to“Isothermalize”
Vapor chambers are ideal for applications where high power densities need to be dispersed quickly, hot spots across the die face need to be minimized, or 2+ heat sources are required to be close in temperature. When the goal is to achieve as uniform a temperature as possible, vapor chambers trump heat pipes by their large contiguous surface area that moves heat in every direction. Heatpipes only move heat in a linear direction.
Vapor Chambers When Heat Sink Height is Constrained, Yet Fin Area Needs to Grow. Typically, heat pipes run through the center of a fin stack to maximize contact area and therefore transfer as much heat to the fins as possible. The downside – the fin area is reduced. While this is not a problem if you’ve got the room to increase in height, it poses a problem when that metric is constrained, as it is here in an add-in desktop graphics card application. A vapor chamber cooling design frees up the needed fin area and provided direct contact with the heat source resulting in a 6-degree performance gain.
As mentioned in the opening of this article, heat sink performance improvement of 5-10 °C can be had by using a vapor chamber in place of heat pipes because they make direct contact with the heat source, and can more evenly distribute heat across a large base, and allow for maximum fin.