Physics / mechanism
Vapor chambers are planar two-phase heat spreaders. A sealed evacuated cavity contains a small charge of working fluid (typically water, though ethanol or ammonia for lower temps). The evaporator side absorbs localized heat flux, vaporizing the fluid; vapor expands across the cavity and condenses at cooler regions; a sintered-powder, mesh, or micropillar wick structure returns condensate via capillary action. Effective thermal conductivity reaches 10,000–50,000 W/m·K in-plane—20–100× copper. State of the art: sub-0.3 mm total thickness (smartphone-grade), operating heat fluxes >300 W/cm², isothermal spread <2°C ΔT across 100 mm. Key parameters are wick permeability, capillary pressure limit, and vapor-core aspect ratio.
Competitive landscape
Heat pipes (1D, tubular, lower cost) are the incumbent for many applications. Loop heat pipes offer longer transport distances. Graphite and graphene composite spreaders (anisotropic, k ~700–1500 W/m·K in-plane) are solid-state alternatives with no reliability risk but lower absolute performance. Thermoelectric coolers add active pumping but consume power and are expensive at scale.
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.