Vacuum Requirements in Coating Systems
Thin film deposition processes require different vacuum levels depending on the technique:
- Thermal or electron-beam evaporation: typically ≤10⁻⁵ Pa
- Magnetron sputtering: base pressure ≤10⁻⁵ Pa, often down to 10⁻⁷ Pa
- Optical coating systems: high purity and stability requirements
These vacuum levels exceed the effective range of Pirani gauges.
Why Cold Cathode Measurement Is Required
Cold cathode vacuum gauges operate based on gas discharge phenomena under high electric fields and are specifically suited for high vacuum measurement.
They do not rely on hot filaments, making them:
- Robust against sudden exposure to the atmosphere
- Resistant to reactive gases
- Suitable for industrial environments
Typical Operating Scenarios
During pump-down, Pirani gauges are used until the pressure enters the effective range of cold cathode gauges.
In steady-state operation, cold cathode gauges provide stable monitoring of high vacuum conditions, though they are best suited for process monitoring rather than precision metrology.
Ignition and Control Considerations
Cold cathode gauges exhibit characteristic ignition behavior:
- ~2 s at 10⁻⁴ Torr
- ~1 min at 10⁻⁵ Torr
- ~5 min at 10⁻⁶ Torr
Control systems typically enable or disable the gauge automatically based on pressure thresholds.
What’s more?
Check our VG-SM225 Cold Cathode Vacuum Gauge
Check another application: Cold Cathode Vacuum Gauge for Vacuum Furnaces & Heat Treatment Systems
Check another application: Cold Cathode Vacuum Gauge for Space Simulation & Environmental Test Chambers
Or
Check our VG-SP205 Pirani Vacuum Gauge