Electric feed through
We make over 1,200 different electrical feed through in a wide variety of terminations, maximum voltages, and current carrying capacities.
A major factor in engineering an electric feed through is the type of current and voltage for which it will be used and the requirements it will have to satisfy with respect to vacuum tightness and temperature resistance. The manufacturing processes for feed through are discussed in Feed through with organic insulating materials can only be used for lower voltages. Simple cast-resin feed through are frequently used for moderate current loads, e.g. for measurement currents. Epoxy resin is very well suited as an insulator and as a vacuum seal for moderate temperatures.
Multi-pole glass-molded feed through to which the leads can be soldered on both sides are installed in small flanges. There are also versions with tubes through which leads can be inserted and soldered in place.
This is important when using thermocouples, for example, as solder joints could falsify the measuring voltage. The feed through are cooled with water for high amperages.
With respect to their insulating resistance, feed through with glass-to-metal fusing are suitable for high-voltage and weak-current feed through for electronic devices. Feed through with ceramic insulation offer greater mechanical stability and temperature resistance than glass. In addition, ceramic (e.g. aluminum oxide) can also be produced in an insulating form that is suitable for high voltage. This is why ceramic feed through are superior to glass feed through for high voltages and high performance. Only rigid metal-to-ceramic connections should be considered for the most rigorous electrical, thermal and vacuum technology requirements.
The voltage level must be taken into account for electric feed through, because gas discharges and flashover can occur in the vacuum if there are small clearances between conductors with high voltage differentials. In the vulnerable pressure range between 10-3 und 10 mbar, appropriate clearances must be provided between high-voltage conductors. Potting with cast resin can also be useful in this regard.