Hermetic Seals

Hermetic seals provide a vacuum or leak-tight seal, insulate or channel electricity, and prevent the ingress of contaminants. They are made of ceramic, glass, or metal materials and joined in a specific configuration by furnace brazing. Containers that use hermetic sealing are able to withstand high temperatures and hold pressures up to 150,000 pounds per square inch (psi). Common types of hermetic seals include metal-to-metal seals, ceramic-to-metal seals, and glass-to-metal-seals. Metal-to-metal hermetic seals are created by firing two or more metal components with the addition of gold, silver, nickel or copper filler materials. Ceramic-to-metal hermetic seals are run through a high-temperature furnace to create a final assembly with a permanent hermetic bond. The hermetic seal is then coated with a metallic pattern. There are two types of glass-to-metal hermetic seals: matched seals and mismatched (compression) seals. Matched glass-to-metal hermetic seals are made of metal alloys and components that share similar thermal expansion characteristics. Mismatched or compression glass to metal hermetic seals feature a steel or stainless steel metal housing that has a higher thermal expansion rate than the glass component. Upon cooling, the metal housing contracts around the glass, creating a hermetic seal that is reinforced both chemically and mechanically.

Hermetic seals are used in a variety of applications and industries. Ceramic-to-metal hermetic seals are used in automotive, aerospace, and medical applications. Products that create a component hermetic seal are also used in the nuclear power industry. Hermetic glass seals are used in many food processing applications to prevent contamination and ensure the delivery of safe, usable products. Glass-to-metal seals are suitable for high-pressure environments and protect electronic components from dirt, dust, and microbial growth. These hermetic seals are also excellent electrical conductors. The glass not only provides the seal, but functions as an insulator between the metal housing and other metal components such as connector pins.

• Hermetic Sealing with Laser Technology
  Conventional hermetic sealing methods of the past - epoxies, solder seals and mechanical seals - cannot fulfill the microwave electronics requirement of 100% protection against moisture. Many...
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• Designer's Guide for Laser Hermetic Sealing
  Electronic circuits exposed to corrosive conditions, or required to have extreme performance characteristics, are sealed hermetically into special packages. Epoxy gluing, resistance welding,...
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• Radial Shaft Seals
  Want to go a long way toward preventing those excess costs associated with seal failure? Understanding and improving seal system performance starts with a thorough understanding of seal composition,...
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Part Numbers for Hermetic Seals