A vapor chamber functions through the continuous evaporation, transport, and condensation of a working fluid (ultra-pure water) within a sealed flat copper cavity. The working fluid evaporates at the heat source, the vapor travels across the VC cavity to the condenser region, condenses back to liquid, and is returned to the evaporator by the capillary wick structure. This phase-change cycle operates under the vapor pressure of the working fluid — which, for water, is approximately 3.2 kPa at 25°C. For the cycle to function, the internal pressure of the vapor chamber must be equal to or lower than this vapor pressure: any non-condensable gas (NCG) present inside the sealed VC adds to the internal pressure beyond the working fluid vapor pressure, reducing the effective partial pressure available for evaporation, suppressing the phase-change cycle, and degrading thermal performance.

The relationship between NCG content and VC thermal performance is not linear — even trace quantities of non-condensable gas cause measurable thermal resistance increase. A vapor chamber that degasses to 99% NCG removal still contains enough residual gas to cause 5-15% thermal resistance increase compared to a fully degassed VC at operating temperature. In high-performance thermal solutions for AI servers, data centre CPUs, and mobile processors where the VC is operating near its thermal design power limit, this residual NCG thermal resistance degradation is the difference between a passing and a failing unit at the performance test station.

Vapor chamber degassing is technically more demanding than heat pipe degassing for three reasons. First, the VC’s flat cavity geometry has a much larger internal volume-to-port-area ratio than a cylindrical heat pipe — evacuation takes longer and requires a vacuum system with sufficient pumping speed for the cavity volume. Second, the thin copper walls of the VC panel (typically 0.2-0.8mm) are more susceptible to deformation under differential pressure during evacuation, requiring controlled ramp-down of pressure to avoid panel distortion that would affect the internal wick structure. Third, the working fluid must remain inside the VC during evacuation — the vacuum system must manage evacuation at a temperature and pressure where the working fluid stays in liquid phase, not above its boiling point at the evacuation pressure.

Complete non-condensable gas removal — not just partial degassing — is the quality standard for vapor chambers in AI server, data centre, and high-performance mobile thermal solutions. The degassing machine either achieves it or the VC fails at performance test.