When people ask what “harsh-environment packaging” actually means at Heisler, we point to our hermetic work. It is the capability that most defines why we exist: building parts, on US soil, that have to survive where ordinary packages do not.
Hermetic gets treated as a checkbox — a line item that is either present or absent on a datasheet. It is not. Hermetic is a leak rate you qualify against and hold for the life of the part. A package that passes a gross-leak check can still fail a fine-leak test, and the number that matters is the fine-leak rate measured against the spec your program qualifies to — not just the absence of a visible leak at time-zero.
What hermetic actually covers
Doing it properly is a sequence of deliberate steps, each of which can quietly undo the one before it:
- Seam and seal on metal and ceramic, with a controlled internal atmosphere — dry nitrogen, or better where the application warrants it.
- Fine- and gross-leak testing, screening per the relevant MIL-STD-883 method so the result is traceable, not anecdotal.
- Pre-seal bake and moisture control, so the cavity is not sealing a failure inside the part.
- Re-verification after thermal and mechanical stress — because what matters is whether the seal holds after the part has lived a little, not whether it held the day it was built.
Skip the pre-seal bake and you trap moisture. Test only for gross leak and you ship parts that were never close to sealed. Verify only at time-zero and you learn nothing about how the seal behaves under the conditions the part will actually see. The discipline is in the order and the proof, not in owning a sealing chamber.
Why domestic, and why us
The programs that need true hermetic packaging — defense electronics, RF and mmWave modules, MEMS and sensor devices, life-limited builds — are also the programs that increasingly need a domestic, traceable supply chain. That combination is harder to find than it should be. Plenty of shops can place a lid; far fewer will stand behind a fine-leak rate, hold it across stress, and hand you the documentation that proves it.
That is the work we have built around: hermetic and harsh-environment construction, on US soil, with the materials traceability and reliability screening that defense and bio customers have to be able to audit. It is the capability that put a finished hermetic package in our hands as the thing we point to when we describe what we do — and it is the reason a growing set of programs in the region treat us as the process partner for the parts that have to survive.
If you have a build that has to pass a real leak spec and hold it — not just check a box — that is exactly the conversation we want to have.