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Ceramic Seals manufactures a broad range of ceramic-to-metal seals, vacuum feedthroughs and electrical isolator assemblies. In addition to standard designs, we work closely with customers to develop bespoke seal assemblies tailored to specific electrical, mechanical or environmental requirements.

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Single-pin Feedthroughs

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01 - Product Info

Single-pin feedthroughs provide a single conducting path through a hermetic ceramic-to-metal seal, ideal for applications where electrical isolation and leak-tight performance are critical. These typically fall into one of four categories:

  • High-voltage
  • High-current
  • High-power
  • Instrumentation

These are often specified as single-pin feedthroughs for vacuum chambers, high-voltage systems and instrumentation ports. In addition to maintaining hermetic integrity, our feedthroughs are designed to withstand extreme conditions, including high temperatures, cryogenic environments, high pressures, ultra-high vacuum, and chemically aggressive atmospheres.

02 - Key Features

High Voltage/Current: Ceramic-to-metal feedthroughs rated up to 150kV DC or 1000A, suitable for power feedthroughs or instrumentation signals.
U.H.V Application: All units are leak-tested to below 1 × 10⁻⁹ mbar l/s and manufactured using vacuum-compatible materials.
Compact Design: Single-pin feedthroughs offer a minimal footprint, making them ideal for systems where space is restricted or where electrical paths must be kept discrete.
Highly Customisable: Offered with various standard conductor types and flange mountings, with the ability to customise terminations, conductor materials, and body geometry to suit system requirements.

Multi-pin Feedthroughs

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01 - Product Info

Multi-pin feedthroughs allow multiple isolated conductors to pass through a single U.H.V body or flange, reducing vacuum penetrations and simplifying chamber design. In many vacuum system applications, this can improve efficiency and be more cost-effective than using multiple single-pin feedthroughs. Multiple-pin feedthroughs are typically mated to a secure plug that offers easy connect/disconnect.

For working voltages up to 3.5kV DC (pin-to-pin and pin-to-ground), a compact multi-pin socket can be used. This configuration allows a high density of electrical connections to be housed within a small-diameter vacuum flange, preserving space without compromising performance.

For higher voltage requirements, between 3.5kV and 10kV DC, individual single-pin feedthroughs are required for each pin to ensure electrical isolation and safety.

02 - Key Features

Dense Configuration: Multi-pin feedthroughs allow multiple isolated circuits to pass through a single flange, optimising space and reducing the number of vacuum penetrations.
Configurable Pin Layouts: Available in a wide range of standard configurations, from 2 to 19 pins, with custom layouts easily produced to suit specific system requirements.
Plug/Socket Compatibility: Multi-pins be supplied as plug and socket pairs for quick disconnect, and simplified assembly in restricted spaces or modular systems.
U.H.V Applications: All units are leak-tested to below 1 × 10⁻⁹ mbar l/s and manufactured using vacuum-compatible materials.

Coaxial Feedthrough Connectors

Browse Co-axial Connectors

01 - Product Info

We offer a wide range of coaxial feedthrough connectors, available in four standard mating interface styles to suit both defence and commercial applications:

  • BNC: 500V DC, 3A, 10¹³ Ω (at 1 kV DC), bayonet
  • MHV: 5kV DC, 3A, 10¹³ Ω (at 1 kV DC), bayonet
  • SHV: 10kV DC, 3A, 10¹³ Ω (at 1 kV DC), bayonet
  • SMA: 700V DC, 1A, 10¹³ Ω (at 1 kV DC), screw

These are hermetic ceramic-to-metal coaxial feedthroughs designed for high-vacuum compatibility and high insulation resistance. All coaxial connectors can be supplied for welding or screwing directly into vacuum flanges or chambers. Alternatively, they can be pre-welded into U.H.V Conflat, Klein™, or O-ring flanges, as single or multi-pin assemblies.

With the plug connected, the operating temperature range is -65°C to +165°C. When the plug is removed, the socket can be safely thermocycled to 450°C at a controlled rate of < 6 °C per minute. These miniature couplings are ideally suited for U.H.V environments, as well as high-temperature applications.

02 - Key Features

Broad Voltage Performance: Coaxial connectors cover working voltages from 500V to 10kV DC, offering signal integrity in highly sensitive applications.
Quick-Connect Interface: Choose from bayonet or threaded interfaces depending on application requirements, installation preferences, and voltage safety considerations.
Flexible Mounting: Connectors can be supplied ready to weld-in, or pre-mounted into a range of vacuum flanges, including Conflat, O-ring, or custom geometries.
U.H.V Applications: All units are leak-tested to below 1 × 10⁻⁹ mbar l/s and manufactured using vacuum-compatible materials.

Thermocouple Feedthroughs

Browse Thermocouple Feedthroughs

01 - Product Info

Our ceramic thermocouple feedthroughs enable accurate temperature measurement through vacuum and controlled environments, supporting continuous use from -185°C to +1600°C.

All feedthrough conductors and connector contacts are manufactured from materials matched to the thermocouple type, ensuring accurate, error-free signal transmission. Conductor material are housed in standard feedthrough bodies and support direct operating temperatures up to 450°C; where miniature thermocouple connectors are used, the maximum temperature is limited to 200°C.

All thermocouple feedthroughs are fully compatible with U.H.V environments.

02 - Key Features

Wide Temperature Range: Designed for continuous use from -185°C to +1600°C, with standard assemblies supporting vacuum-side temperatures upwards of 450°C.
U.H.V Compatible: All units are leak-tested to below 1 × 10⁻⁹ mbar l/s and manufactured using vacuum-compatible materials.
Type-Matched Conductors: All thermocouple feedthroughs use conductor materials matched to the thermocouple type, ensuring accurate, error-free temperature measurements.
Flexible Termination/Mounting: Available with a range of terminations, including bare wires, connectors, or plugs, and can be supplied for welding or pre-mounted in U.H.V flanges.

Electrical Isolators

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01 - Product Info

Our electrical isolators and vacuum breaks use proven ceramic-to-metal sealing technology to provide electrical isolation, mechanical strength and environmental resistance across vacuum, pressure, cryogenic and high-temperature conditions.

Cryogenic Liquid/Gas Isolators: Compression-jointed ceramic-to-metal seals provide outstanding mechanical strength and resistance to thermal shock, making them ideal for use as isolators in cryogenic fluid and refrigerant systems where a voltage differential exists.

Small Diameter Isolators: These isolators, similar in construction to cryogenic feedthroughs, are suitable for use in vacuum systems or within liquid and gas feed circuits. They can be welded directly into customer equipment or supplied pre-welded into a variety of standard vacuum flanges.

Vacuum Breaks: Designed for larger-scale applications, vacuum breaks offer electrical isolation across vacuum lines and are available with static or rotatable flanges stainless steel flanges to simplify alignment during assembly. All designs are U.H.V compatible and suitable for repeated bake-out cycles up to 450°C.

Heat Sink Isolators: These isolators combine good thermal conductivity and excellent electrical insulation, making them ideal for applications requiring heat transfer across an electrically isolating barrier.

02 - Key Features

Electrical Isolation: Maintains voltage separation between systems whilst providing excellent dielectric strength under vacuum, pressure, cryogenic, and high-temperature conditions.
Shock Resistant: Our isolators feature robust metallisation, joint design, and material selection to provide excellent resistance to thermal shock.
U.H.V Compatible: All units are leak-tested to below 1 × 10⁻⁹ mbar l/s and manufactured using vacuum-compatible materials.
Non-Magnetic Options: Where required, isolators can be built using non-magnetic materials to support applications in any environment.

Sapphire Viewports

Browse Sapphire Viewports

01 - Product Info

Our hermetic sapphire viewports are engineered for durability and performance in U.H.V environments. Single-crystal sapphire (melting point 2040°C) combines outstanding optical, mechanical, and chemical properties.

Sapphire features broad optical transmission, covering infrared, visible, and ultraviolet spectra:

  • 0.2 - 0.4µm ~70% transmission
  • 0.5 - 4.0µm ~85% transmission
  • 5.0 - 6.0µm ~50% transmission

Sapphire viewports are supplied as hermetic vacuum viewports and optical feedthroughs. This makes sapphire viewports ideal for demanding diagnostic and monitoring applications. In addition to standard windows, bespoke windows and sapphire lenses can be supplied to customer specifications.

02 - Key Features

Broad Optical Range: Sapphire lenses offer excellent transmission across ultraviolet, visible, and infrared wavelengths, making them ideal for diagnostics, spectroscopy, and laser applications.
Chemically Inert: Sapphire offers excellent resistance to a wide range of corrosive gases and liquids, making these viewports ideal for use in aggressive chemical, plasma, or process environments.
U.H.V Compatible: All units are leak-tested to below 1 × 10⁻⁹ mbar l/s and manufactured using vacuum-compatible materials.
Exceptional Strength: Single-crystal sapphire provides outstanding strength and hardness, with a high resistance to thermal shock.

Frequently Asked Questions:

What is the typical service life of ceramic-to-metal seal assemblies / feedthroughs?

When correctly designed and manufactured, ceramic-to-metal seal assemblies and electrical feedthroughs can operate reliably for decades. Their service life is primarily governed by operating environment rather than calendar time.

Key factors influencing longevity include:

  • Operating temperature range and thermal cycling severity
  • Applied voltage and electric field intensity
  • Vacuum level or pressure differential
  • Mechanical loading and vibration
  • Compatibility between ceramic, metallisation, braze alloy and metal components

High-purity alumina ceramics exhibit excellent chemical stability, low outgassing and minimal ageing effects. When combined with controlled metallisation and brazing processes, the resulting hermetic joint forms a stable ceramic-to-metal interface that does not degrade under normal operating conditions.

In high-vacuum and high-voltage applications, properly specified ceramic feedthroughs routinely achieve service lifetimes in excess of 20 years, with many assemblies remaining in service for significantly longer.

How does ceramic-to-metal sealing work?

Ceramic-to-metal sealing is achieved by permanently bonding a ceramic insulator to metal components using a high-temperature brazing process to create a hermetic, electrically insulating joint.

The process typically involves:

  1. Metallization of the ceramic:
    A thin metallized layer is deposited onto the ceramic surface and fired at high temperature to form a chemically bonded, conductive interface suitable for subsequent processes.
  2. Plating of the metallized surface:
    A nickel layer is applied to provide a braze or solder-compatible surface.
  3. Brazing to metal components:
    A controlled-atmosphere or vacuum brazing cycle melts a braze alloy between the plated ceramic and the metal parts, forming a metallurgical bond on cooling.

The resulting joint provides:

  • Hermetic sealing (leak-tight to ultra-high vacuum levels)
  • High dielectric strength
  • Mechanical robustness
  • Resistance to thermal cycling

This ceramic-to-metal sealing technology forms the basis of hermetic ceramic feedthroughs, electrical isolators and vacuum windows used in high-reliability systems.

Need More Information?

Our technical team are happy to answer any questions you may have, or work to develop partial / fully-bespoke designs to suit your specific design requirements.

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