Vapor Chamber A vapor chamber, sometimes called a planar heat pipe or a vapor chamber heat spreader, is a two-phase device used to spread heat from a heat source to a heat sink. For electronics cooling applications, the heat transfer is usually to a heat sink in very close proximity to the heat source; a local as opposed to a remote heat sink. The use of vapor chambers has increased markedly as both the total power and, as a result of shrinking die sizes, the power density has skyrocketed. In terms of price and application flexibility, today’s vapor chambers are both more capable and lower cost than even a decade ago.

Like heat pipes, vapor chamber thermal conductivity increases with length. This means that a vapor chamber the same size as the heat source will offer little advantage over a solid piece of copper. A good rule of thumb says that the area of the vapor chamber should be equal to or greater than 10X the area of the heat source. In situations where the thermal budget is large or when a lot of airflow drives a small fin stack this may not be an issue. However, it’s often the case that the base of the sink needs to be considerably larger than the heat source.