Cooling High-Power Electronic components in Small Packages

Vapor chambers are essentially flat or planar heat pipes that use the evaporation and condensation of a working fluid to produce a very high-conductivity thermal plane. Bulk conductivities have been measured at over 30 times the conductivity of copper and over 10 times the conductivity of pyrolytic graphite and diamond. Vapor chambers are evacuated vessels with a wick on the evaporator side that have a small amount of working fluid backfilled into the interior. Vapor chambers can be bonded into an existing extrusion or can be used as the base itself, in which case fins can be soldered directly to it. To illustrate the thermal performance improvement that a vapor chamber can provide to an all-metallic heat sink, we now examine the same heat sink described, but with a vapor chamber integrated into the heat sink base. With the different heat sink, the heat is much more evenly spread across the entire heat sink, causing a drop in overall thermal resistance of 37%. The heat sink used in this example, with an embedded vapor chamber, with all of the parameters held constant, shows a resistance of only 0.29 °C/watt