Definition
A vapor chamber is a sealed, flattened two-phase heat-transfer device, essentially a planar heat pipe, that spreads concentrated heat from a chip across a much larger surface area. It contains a wick structure and a small charge of working fluid in equilibrium with its own vapor, giving it an effective thermal conductivity far higher than solid copper of the same dimensions.
How it works
Heat from the chip evaporates the fluid at the hot zone. The vapor spreads two-dimensionally across the chamber, condenses against the cooler outer wall where a heatsink or fins reject the heat, and capillary action in the wick returns the liquid to the hot spot. Unlike a one-dimensional heat pipe that ferries heat to a remote sink, a vapor chamber spreads heat laterally to a local sink, which suits a hot ASIC die feeding a finned heatsink.
Relevance to mining hardware
Stock ASIC hashboards rely on long aluminum heatsink bars, but compact builds such as Bitaxe-class single-chip miners and some high-density designs benefit from vapor-chamber spreaders because the BM-series chip concentrates heat in a small footprint. By flattening hot spots, a vapor chamber lets a smaller, lighter sink do the work of a much heavier copper block, lowering chip temperature for the same airflow. It is a heat spreader, not a complete cooling solution: it still needs a heatsink and moving air or liquid to actually shed the energy.
For the upstream and downstream pieces of the same thermal path, see the entries for Heatsink and Thermal Paste.
Compare cooling approaches in the cooling methods comparison.
In Simple Terms
A vapor chamber is a sealed, flattened two-phase heat-transfer device, essentially a planar heat pipe, that spreads concentrated heat from a chip across a much…