CALCE Electronic Products and Systems Center, Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA
Gas transport mechanisms that characterize the hermetic behaviour of MEMS packages are fundamentally different depending upon which sealing materials are used in the packages. In metallic seals, gas transport occurs through a few nano-scale leak channels (gas conduction) that are produced randomly during the solder re-flow process, while gas transport in polymeric seals occurs through the bulk material (gas diffusion). In this review article, the techniques to measure true leak rates of MEMS packages with the two sealing materials are described and discussed: a Helium mass spectrometer based technique for metallic sealing and a gas diffusion based model for polymeric sealing.
Key Words: MEMS package; hermeticity; helium mass spectrometer; true leak rate; gas conduction; gas diffusion; metallic seals; polymeric seals.
Complete article is available from the publisher and to the CALCE Consortium Members.