Hermetic connectors are designed to prevent ingress of air, gases and other liquids into the vacuum-sealed connector in extremely harsh environments. In testing, these connectors should show no detectable gas or fluid leakage.
They should be able to withstand high pressures of 10,000 psi or more, ensuring a stable pressure differential on both sides of the assembly. Ideally, hermetic seals must withstand low to high pressures and altitudes seen in military applications, offshore applications to extreme depths, and commercial and industrial operations.
Most hermetic connectors are glass sealed because the glass creates a rigid form for the metal shell to compress against. This compression creates the hermetic seal. The glass is bonded to and supports the contacts.
They also must withstand extreme temperature variations, from approximately -100° to 200°C and resist damaging vibration.
These connectors can use stranded or solid plated copper conductors, insulated conductors, copper, brass or Nickel iron pin contacts and fiber optic cables. They can be designed into a helium gas-tight bulkhead or harness assembly with connectors preinstalled.
Because they are manufactured to operate in harsh environments, most hermetic connectors are made of durable metals, including stainless steel, glass and Nickel iron. However, while glass is the most effective insulating material it can add unnecessary weight in some applications. Here, epoxy seals are used. Additionally, aluminum alloy shells can cut the weight in half.