Electrical Feedthroughs Information
Image Credit: Nor-Cal Products, Inc.
Electrical feedthroughs transmit electrical current through the walls of a pressurized or vacuum system through a hermetic seal. Electrical feedthroughs are designed to maintain the integrity of the walls of a vacuum system up to a specified vacuum rating.
Types of Electrical Feedthroughs
Types of electrical feedthroughs include coaxial, multi-pin or instrumentation, power, thermocouple, and RF feedthroughs.
In coaxial feedthroughs, one conductor is insulated with a dielectric material and then surrounded by the other conductor. This is usually referred to as the center conductor and shield. The shield is typically a serve, braid, or foil braid configuration. Typical applications are video, RF, and microwave.
Instrumentation or multi-pin feedthroughs are commonly used for the transmission of electrical signals or low power applications. They are typically referred to as Instrumentation feedthroughs because of their use in instrumentation applications such as electron microscopy, surface analysis and semiconductor process controls.
Power feedthroughs are solid or stranded conductors surrounded by insulation, shielding, and a protective jacket. They are designed for high voltages and are found in many applications including vacuum furnaces, sample heating, biasing and in-vacuum coating applications such as electron beam evaporation, resistive heating evaporation and DC plasma sputtering.
Thermocouple feedthroughs are used for measuring temperature. They function via a pair of wires of dissimilar metals (as copper and iron) that are joined, with the free ends of the wires connected to an instrument (as a voltmeter) that measures the difference in potential created at the junction of the two metals. Thermocouple feedthroughs are not specifically temperature sensing devices. They are components used to conduct the thermocouple's voltage (EMF) through the bulkhead of a chamber to external instrumentation.
RF Electrical Feedthroughs
RF electrical feedthroughs are specifically designed for the transmission of Radio Frequency power in to the vacuum environment. Differences conventional DC power feedthroughs and RF feedthroughs are found in the construction materials. High conductivity, nonmagnetic materials are utilized in the RF feedthroughs, as they are less susceptible to the effects of current induction.
DSCC-DWG-87036 - CONNECTOR, RECEPTACLE, ELECTRICAL, SERIES SMA, FEEDTHROUGH, HERMETIC
MIL-DTL-83517/13 - CONNECTOR, RECEPTACLE, ELECTRICAL, COAXIAL, RADIO FREQUENCY, SERIES SMA, (SOCKET CONTACT) FEEDTHROUGH, HERMETIC