Glass-to-Metal Sealing Technology

Feedthroughs which are produced with glass-to-metal sealing technology allow the electrical connection into hermetic packages.

Glass-to-Metal seals are produced using a special purpose furnace with an inert atmosphere. Within this process, the glass preforms are first molten and then establish the seal to housing and pins during the cooling phase. Depending on requirements, the Feedthroughs can be designed as compression seals or matched seals.

With our in-house developed specialty furnace equipment, the Dietze Group is perfectly suited to assist you with high precision glass-to-metal seals.

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About the product

About the sector

Compression Seals

Compression seals employ a different coefficient of thermal expansion between glass, housing and pins. The hermetic seal between glass and metal is established because of the material compression after cooling down. Housing materials with a high CTE such as stainless steel or titanium are therefore suited for compression seals. Depending on design, a compression seal can withstand a very high level of pressure (up to 3000 bars possible). This type of glass-to-metal seal is among other uses perfectly suited for high pressure sensors.

Matched Seals

In a matched glass-to-metal seal the coefficient of thermal expansion of glass, housing and pins are matched as close as possible. Matched seals have the advantage that only small levels of residual stress are present and that the feedthrough can withstand very high temperatures. The seal between glass and metal is mainly established chemically by an oxide layer. Typically, Kovar is used as a housing material for matched seals. This type of glass-to-metal seal is often used for electronics packages.

Compression Seal Matched Seal
Sealing principle Thermal compression chemical
Typical housing material Steel, stainless steel, titanium, … Kovar, alloy 42, …
Special Properties High bust pressure

Very robust

Chemically very inert

High-Temperature capability

High insulation resistance

Very high hermeticity

Applications Sensor-housings, hermetic connectors, sight glasses, power  feedthrougs Electronic-housings

Our Products and Services

The Dietze Group provides custom interconnection solutions from concept to series production. All our products are designed in close collaboration with our customers and engineered to the application’s specific needs.

Glass-to-Metal Seals

Our Glass-to-Metal Seals provide electrical connections to components in hermetic packages even under extreme conditions.

Connector Pins & Stamping

Our high precision contact pins and stamping parts guarantee reliable electrical connections in demanding applications.


Lead-In-Wires provide the hermetic seal as well as the connection between the cathode or burner and the base in many types of light sources.