Hermetic Seal

Author: Postek Engineering Team | Reading time: 10 minutes Introduction “Sealed” is one of the most misused terms in component specification. Engineers frequently specify “IP67 rated” switches assuming they are protected against all environmental threats — only to discover that at 50,000 feet, their “sealed” switch has failed because the internal atmosphere equalized with near-vacuum external conditions. This article clarifies the fundamental differences between environmental sealing (IP ratings) and true hermetic sealing, and provides clear decision criteria for when each is appropriate. ...

Why Hermetic Sealing Matters In aerospace, mission-critical, and industrial applications, a switch is not just a switch — it is a potential point of failure. When a limit switch controls a orbital solar array deployment, a flight-critical arming sequence, or a cryogenic valve, the cost of failure is measured in mission loss, not warranty returns. Standard micro switches rely on plastic housings and elastomeric seals. Under thermal cycling, vacuum, radiation, or corrosive atmospheres, these organic materials degrade. The seal fails. Contaminants enter. The switch becomes unreliable — often without visible warning. ...