Hermeticity Tests

This chapter discusses the Hermicity Tests in detail. Hermeticity testing is a technology that deals with the transfer of media (gasses) in and out of sealed enclosures based on vacuum science, physics, and chemistry. The chapter aims to establish an understanding of the different seal test methodologies for MEMS packages. The hermeticity classes are explained. Method for measuring package and seal Integrity using helium as the tracer gas defines and quantifies these classes differently but uses the same wording. Only three nondestructive leak tests possess high enough measurement sensitivity for modern inertial sensors. The relevant hermeticity tests for MEMs packages are membrane resonance, Kr 85 radioactive tracer gas tests, optical deformation, internal pressure measurement, helium leak test, IR transmission tests, and Q factor monitoring. The neon ultra-fine leak test is an elaborated hermeticity test environment with a dedicated vacuum prediction model (vacuum lif etime model) based on quality factor monitoring of micro resonating devices. The neon ultra-fine leak test procedure for a new device starts with measuring a calibration curve for Q factor over a relevant pressure range, using selected open devices. The calculation regarding the vacuum lifetime model can be done easily in an analytical way such as cavity with ideal getter and getter saturation. The calculation will be much easier if we can assume molecular flow in the hole leak channel.