A test for small hermetic parts with no test port, such as electronic packages and sensors. The parts sit in helium at several bar for hours, any leak path lets helium in, and they are then moved to a vacuum chamber on a leak detector that measures the helium escaping. A gross leak can lose all its helium before the measurement starts, so bombing is paired with a gross leak test such as a bubble or dye test.
Lot failed fine leak after bombing at 60 psi for two hours, pull ten more and run gross leak on them too.
Also heard as
- bombing
- pressure-bomb test
- back-pressurization test
Related terms
Helium leak detector
Mass spectrometer tuned to helium that finds and measures leaks by detecting helium drawn into the system.
Gross leak
Leak big enough to stop a system pumping down properly, or to be found without sensitive instruments.
Sniff
To hunt for helium escaping from a pressurized part by sweeping a sniffer probe slowly over joints and welds.