Hermetic sealing materials are widely used in vacuum containing devices for example vacuum interrupters in the field of the middle voltage sector.

A vacuum interrupter comprises of two contacts, contained in a sealed vacuum enclosure.

Vacuum is an insulating medium; therefore, the current can flow through the interrupter only when contacts are closed. On the other hand, when the contacts are open, the circuit is isolated. To hold this high vacuum over a minimum period of 30 years, brazing materials of a high purity (min. 99.99 %) and with low Zn and Cd contents (< 1 ppm) must be used for this application. Umicore hermetic sealing materials meet the demand for a high purity and clean surface of the brazing alloys

Key features

Vacuum tightness, hermetic sealing, high purity and clean surface, shape supporting manufacturing process, special designed washers for an easy evacuation of tubes

Other Application

• Surge arrestors

A surge arrestor is designed to protect electrical devices from voltage peaks. Surge arrestors regulate the voltage supplied to an electric device by either blocking or shorting to ground voltages above a safe threshold.

• Power tubes

Power tubes have a ceramic or metal housing and are available in miscellaneous forms and designs. Electrodes are attached to leads, which pass through the housing by an airtight seal. Most tubes are designed in a way that the leads are easily pluggable into the tube socket for replacement.

• X-ray tube

In an X-ray tube contains vacuum, in which x-rays are generated by applying an voltage to accelerating electrons on a target material  like Cu or Co. Hit the electrons the target surface characteristic and retardation radiation is emitted. Since the wavelengths of X-ray radiation is short (nm), it is used for characterization of solid-state bodies or in medical applications.

  • High voltage rectifier

Rectifiers are used in the field of electrical engineering to transform alternating current (AC) to direct current (DC). This is done by using semiconducting diodes. The process of rectifying is usually noncontrollabel. Rectifiers are for example used in the field of serving as component for direct current devices or in the high-voltage direct current power transmission.

• Thyristors

A thyristor is a device, which is built of four layers of semiconducting materials with different doping. With this stack of layers a pnpn (p= electron doping, n0 hole doping) transitions is built. In addition to the anode and the cathode, a thyristor has a third pin the gate electrode, which is used to apply voltages for controlling the device. It is a controllable rectifier. Different forms of thyristors are available on market for example silicon controlled rectifier (SCR, trade name of General Electric), where silicon is used as semiconducting material.

• Magnetron

A magnetron is a vacuum containing device, in which coherent microwaves (wavelength: 1 mm-300 mm) a generated by an electron tube with high frequency. The generation is based on the principle of the transition time of electrons between cathode and anode of the tube.

Manufacturing process and delivery forms

Umicore’s hermetic sealing alloys are produced by a vacuum melting process and further processes like continuous casting, extrusion, roll milling or wire drawing. By cutting, bending or punching the final shapes of the materials are fabricated from ribbons or wires.

Download Datasheet: Hermetic Sealing Material