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Measurements of true leak rates of MEMS packages.

Han B - Sensors (Basel) (2012)

Bottom Line: Gas transport mechanisms that characterize the hermetic behavior 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 nanoscale leak channels (gas conduction) that are produced randomly during the solder reflow 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.

View Article: PubMed Central - PubMed

Affiliation: CALCE Electronic Products and Systems Center, Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA. bthan@umd.edu

ABSTRACT
Gas transport mechanisms that characterize the hermetic behavior 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 nanoscale leak channels (gas conduction) that are produced randomly during the solder reflow 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.

No MeSH data available.


Cap surface topographical contour maps (the units in the scale are μm and the cavity location is indicated by the dotted box) at the beginning and the end of (a) bombing stage and (b) release stage.
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f12-sensors-12-03082: Cap surface topographical contour maps (the units in the scale are μm and the cavity location is indicated by the dotted box) at the beginning and the end of (a) bombing stage and (b) release stage.

Mentions: After the calibration curve was obtained, the package was subjected to a constant bombing pressure of 4 atm (gage) and the deflections were measured as a function of time. The bombing pressure was maintained for 600 h. There was no noticeable deflection change after 600 h, indicating that the cavity pressure was equal to the bombing pressure. At this point, the “release” stage was initiated by closing the helium gas valve and opening the chamber to the atmospheric environment (0 atm of helium). The surface deflection was also documented regularly during the release stage. Representative fringe images and corresponding 3D maps are shown in Figure 12(a,b) for the bombing and release stages, respectively.


Measurements of true leak rates of MEMS packages.

Han B - Sensors (Basel) (2012)

Cap surface topographical contour maps (the units in the scale are μm and the cavity location is indicated by the dotted box) at the beginning and the end of (a) bombing stage and (b) release stage.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376579&req=5

f12-sensors-12-03082: Cap surface topographical contour maps (the units in the scale are μm and the cavity location is indicated by the dotted box) at the beginning and the end of (a) bombing stage and (b) release stage.
Mentions: After the calibration curve was obtained, the package was subjected to a constant bombing pressure of 4 atm (gage) and the deflections were measured as a function of time. The bombing pressure was maintained for 600 h. There was no noticeable deflection change after 600 h, indicating that the cavity pressure was equal to the bombing pressure. At this point, the “release” stage was initiated by closing the helium gas valve and opening the chamber to the atmospheric environment (0 atm of helium). The surface deflection was also documented regularly during the release stage. Representative fringe images and corresponding 3D maps are shown in Figure 12(a,b) for the bombing and release stages, respectively.

Bottom Line: Gas transport mechanisms that characterize the hermetic behavior 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 nanoscale leak channels (gas conduction) that are produced randomly during the solder reflow 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.

View Article: PubMed Central - PubMed

Affiliation: CALCE Electronic Products and Systems Center, Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA. bthan@umd.edu

ABSTRACT
Gas transport mechanisms that characterize the hermetic behavior 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 nanoscale leak channels (gas conduction) that are produced randomly during the solder reflow 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.

No MeSH data available.