What Are the Different Types of Vacuum Feedthroughs?

Vacuum feedthroughs are essential components in high-vacuum (HV) and ultra-high vacuum (UHV) systems. They allow the transfer of electricity, fluids, gases, or mechanical motion from the atmospheric side to the vacuum side while maintaining the integrity of the vacuum seal.

Understanding the different types of vacuum feedthroughs helps in selecting the right solution for applications such as semiconductor manufacturing, thin-film deposition, research chambers, and cryogenic systems.

This guide explores the main categories of vacuum feedthroughs and their subtypes.

1. Electrical Feedthroughs

Electrical feedthroughs transmit electrical power or signals into a vacuum environment. They are designed to accommodate different voltage, current, and signal requirements.

(1).High-Current Power Feedthroughs1
Ideal for low-voltage (typically under 50 V) but high-current applications (hundreds to thousands of amps).
Commonly used in:

  • Deposition sources
  • Sputtering targets
  • Substrate heating

Typical examples include 400 A and 1000 A feedthroughs, often with optional water cooling for higher thermal loads.

(2).Thermocouple Feedthroughs2
Designed specifically for temperature measurement, ensuring accurate readings without compromising vacuum integrity.

(3).Multipin Feedthroughs3
Provide multiple electrical connections in a single unit, suitable for instrumentation, sensors, and control signals.

(4).Coaxial Feedthroughs
Feature shielded conductors to support high-frequency signals with minimal interference.

(5).RF Feedthroughs
Optimized for radio-frequency power transmission, minimizing signal loss in RF plasma or deposition systems.

Common materials include oxygen-free copper conductors and PTFE or ceramic insulators for reliable performance in high-vacuum environments.

2. Fluid and Gas Feedthroughs

Fluid and gas feedthroughs allow liquids or gases to pass into a vacuum chamber, commonly for cooling, purging, or process gas delivery.

(1).Non-Cryogenic Feedthroughs4
Designed for standard fluids and gases.
Features include:

  • Stainless steel tubing
  • VCR or Swagelok fittings
  • High bakeout temperature capability

(2).Cryogenic Feedthroughs
Engineered for ultra-low-temperature fluids such as:

  • Liquid nitrogen (LN₂)
  • Liquid helium (LHe)

These feedthroughs incorporate thermal insulation shields to reduce heat transfer and prevent condensation.

Both types are available in single-tube or double-tube configurations and can be rated for HV or UHV applications.

3. Rotary Motion Feedthroughs

Rotary motion feedthroughs transmit rotational movement into the vacuum chamber. They are commonly used for: Sample manipulatio、Beam steering、Rotating sputtering targets.

Elastomer-Sealed Rotary Feedthroughs:

  • Use O-ring seals
  • Suitable for lower RPM applications
  • Serviceable and cost-effective
  • Provide good torque at moderate speeds

Ferro-Sealed (Ferrofluid) Rotary Feedthroughs:

  • Designed for high RPM and high torque
  • Use magnetic ferrofluid seals
  • Produce minimal particles
  • Ideal for demanding UHV and clean applications

These feedthroughs typically feature stainless steel shafts, precision bearings, and robust housings for long-term reliability.

4. Transition Feedthroughs

Transition feedthroughs, also known as baseplate feedthroughs, provide adaptable interfaces for vacuum chamber ports.

Flange-Based Transition Feedthroughs5
Compatible with standard vacuum flanges such as:

  • ConFlat (CF)
  • ISO-QF (KF)

Commonly used for mounting gauges, sensors, or additional components.

Fitting-Based Transition Feedthroughs:

  • Female NPT threads
  • Quick disconnects
  • Blank plugs

Transition feedthroughs add flexibility to system design without requiring major chamber modifications.

5.Key Considerations for Choosing Vacuum Feedthroughs

Selecting the right vacuum feedthrough depends on your application requirements. Important factors include:

  • Type of transfer (electrical, fluid/gas, motion, or transition)
  • Vacuum level (HV vs. UHV)
  • Operating temperature and bakeout requirements
  • Electrical current and voltage ratings
  • Material compatibility
  • Flange and connection standards

Choosing the correct feedthrough ensures system efficiency, reliability, and leak-free operation. For specialized or high-performance systems, consulting with vacuum component experts is highly recommended.

6.Frequently Asked Questions（FAQ）

Q. What is the main purpose of a vacuum feedthrough?

A.Vacuum feedthroughs maintain a hermetic seal while allowing the transfer of power, signals, fluids, gases, or mechanical motion between atmospheric and vacuum environments.

Q. What are the most common flange types for vacuum feedthroughs?

A.The most common flange types are:

  • ConFlat (CF) — used for ultra-high vacuum applications
  • ISO-QF (KF) — commonly used in high-vacuum systems for quick installation and maintenance

Q. Can vacuum feedthroughs be used in cryogenic applications?

A.Yes. Specialized cryogenic feedthroughs are designed for low-temperature fluids such as liquid nitrogen and include insulation features to minimize heat leakage.

7.Conclusion

If you’re building or upgrading a vacuum system, explore a range of high-quality vacuum feedthroughs tailored to these applications. Contact a qualified supplier for custom solutions or detailed specifications.

  1. Find out how High-Current Power Feedthroughs enhance performance in high-power applications. ↩

  2. Understand the importance of Thermocouple Feedthroughs in accurate temperature measurement. ↩

  3. Explore the advantages of Multipin Feedthroughs for efficient electrical connections. ↩

  4. Learn about the specialized design of Cryogenic Feedthroughs for low-temperature applications. ↩

  5. Explore the versatility of Transition Feedthroughs in vacuum system design. ↩

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Vacuum Feedthrough

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