Review of test methods used for the measurement of hermeticity in packages containing small cavities

This paper presents a critical review of the traditional and newly proposed test methods used for the measurement of hermeticity in packages with very small cavity volumes. Closed-form expressions of the minimum and maximum true leak rates achievable are provided for the helium fine leak test method. These expressions are shown to provide practical guidelines for the accurate testing of hermeticity for ultrasmall packages. A portfolio of hermeticity test methods is also presented outlining the limitations and advantages of each method.