6 – Fine Leak Measurements Using a Helium Leak Detector

Publisher Summary This chapter discusses various aspects of fine leak measurements using a helium leak detector. The value of the standard leak decreases with time, because helium is leaking out of the standard leak. The smaller the leak, the more linear the decrease becomes with time. The chapter elaborates that packages with porous glass to metal seals can have a considerable amount of helium attached to the external surface. It is found that the seals may be hermetic if the porosity is confined to the surface of the glass. Repetitive leaks at the same pin location may be an indication of an inadequate package design. Cracks in a ceramic package may also indicate a package design fault or excessive mechanical stresses. The method of finding the location of the leak consists of connecting the leak detector to the inside of the package and supplying helium to the outside of the package.