Using optical correlation to measure leak rates in sealed packages.
An optical correlation technique has been shown to accurately measure leak conduction rates from 10(-1) to 10(-6) atm cc/sec. Using hybrid microcircuit packages with glass capillary leakers, dimensional changes were detected as the packages were exposed to a small increase in external pressure. The rate at which the package returns to its original dimensions is measured and used, along with the internal free volume, to compute the leak rate. Because of its several advantages, the technique has the potential to become a useful nondestructive quality-control technique.
The back-pressurising technique of leak-testing
Abstract The technique of leak-testing sealed objects is examined in which the object is first pressurised in a tracer gas and afterwards tested for re-emission of the gas. The minimum siz maximum sizes of leaks detectable are evaluated as functions of the sensitivity of the detector, the applied pressure and time of pressurising, the time lapse before the final tests, and the internal volume of the object. Formulae are derived for specifying pressurising conditions for desired sensitivities and for determining sensitivities resulting from a given test. Examples are quoted from practical experience in leak-testing fuel elements for nuclear reactors.
Leak detection and detectors
Abstract While continuous advances in the design of vacuum components and in the techniques of construction have gradually reduced the incidence of “built-in” leaks in vacuum systems, the parallel development of leak detectors has facilitated the detection of smaller leaks until, at the present time, the lowest pressure attainable in a metal vacuum system is governed by the rate of outgassing of the constructional materials and in a glass system by the rate of diffusion of atmospheric helium through the glass.