A feedthrough is a critical component of a vacuum chamber that allows electrical power, signals, fluids, or mechanical motion to be transmitted from the external environment into the vacuum environment without compromising the chamber's vacuum integrity. It serves as a sealed interface, maintaining the required pressure differential. The feedthrough creates a hermetic seal where a conductor, tube, or shaft penetrates the chamber wall. This is achieved using specialized sealing techniques such as glass-to-metal seals, ceramic-to-metal seals, or elastomer O-rings, depending on the application's vacuum level, temperature, and media requirements. Feedthroughs are available in various configurations to suit different applications. Electrical feedthroughs can have 1 to 50 conductors, with current ratings per pin from 1 to 200 A and voltage ratings from 50 to 1000 V. They are designed to maintain leak rates as low as 1e-10 mbar·L/s for ultra-high vacuum (UHV) applications, up to 1e-6 mbar·L/s for high vacuum. Temperature ranges span from -196°C to 450°C, depending on sealing materials: Viton (FKM) is suitable up to 200°C, while ceramic seals can handle up to 450°C. Pressure ranges from 1e-10 bar (internal vacuum) to 10 bar (external pressure). Common body materials include 304 and 316L stainless steel, with 316L offering enhanced corrosion resistance. Conductors are typically made of copper, Kovar, or molybdenum, chosen for conductivity or matched sealing. Insulation materials include alumina ceramic (Al2O3) for high temperature and UHV, or glass for cost-effective solutions. Seal types include ceramic-to-metal, glass-to-metal, or O-ring, with O-rings suitable for low vacuum and ceramic for UHV and high temperature. Mounting flanges are available in CF, KF, or ISO styles, with flange sizes from DN16 to DN250. Mechanical feedthroughs have a service life of 10,000 to 50,000 cycles. Always verify model-specific values and standards with the legal manufacturer or supplier.
The feedthrough creates a hermetic seal where a conductor, tube, or shaft penetrates the chamber wall. This is achieved using specialized sealing techniques such as glass-to-metal seals, ceramic-to-metal seals, or elastomer O-rings, depending on the application's vacuum level, temperature, and media requirements. The seal must maintain the pressure differential between the vacuum interior and the external environment, preventing leakage. For electrical feedthroughs, the conductor is insulated from the metal body using ceramic or glass, which also provides mechanical support. For fluid or mechanical feedthroughs, the moving shaft or tube is sealed with dynamic seals like O-rings or bellows. The choice of sealing method depends on factors such as temperature, pressure, and the need for electrical isolation. The feedthrough must be designed to withstand thermal cycling and mechanical stress without compromising the vacuum integrity.
