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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.


(a) Representative fringe patterns and 3-D deformation maps obtained during the calibration process (the units in the scale are μm and the cavity location is indicated by the dotted box); (b) calibration curve (the encircled values correspond to the fringes in (a).
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f11-sensors-12-03082: (a) Representative fringe patterns and 3-D deformation maps obtained during the calibration process (the units in the scale are μm and the cavity location is indicated by the dotted box); (b) calibration curve (the encircled values correspond to the fringes in (a).

Mentions: In order to obtain the calibration curve, the pressure in the chamber was increased to 4 atm (gauge) in steps of 0.25 atm and the surface deformation was recorded at each step. The deformation-induced deflections are plotted as a function of the applied external pressure and bombing time in Figure 11(a). Three data points marked by a dotted circle were obtained from the representative fringe patterns and the corresponding 3-D maps shown in Figure 11(b). From this plot the following linear relationship between pressure differential, Δp, and the maximum deflection, Wmax, of the specimen was obtained:(23)Wmax=309.58 (Δp)where the units for pressure and deformation are atm and nm, respectively. It is worth noting that the above relationship is valid for both bombing and release stages since the deformation is within the elastic range. This was confirmed again in the actual measurement for cavity pressure evolution.


Measurements of true leak rates of MEMS packages.

Han B - Sensors (Basel) (2012)

(a) Representative fringe patterns and 3-D deformation maps obtained during the calibration process (the units in the scale are μm and the cavity location is indicated by the dotted box); (b) calibration curve (the encircled values correspond to the fringes in (a).
© Copyright Policy
Related In: Results  -  Collection

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

f11-sensors-12-03082: (a) Representative fringe patterns and 3-D deformation maps obtained during the calibration process (the units in the scale are μm and the cavity location is indicated by the dotted box); (b) calibration curve (the encircled values correspond to the fringes in (a).
Mentions: In order to obtain the calibration curve, the pressure in the chamber was increased to 4 atm (gauge) in steps of 0.25 atm and the surface deformation was recorded at each step. The deformation-induced deflections are plotted as a function of the applied external pressure and bombing time in Figure 11(a). Three data points marked by a dotted circle were obtained from the representative fringe patterns and the corresponding 3-D maps shown in Figure 11(b). From this plot the following linear relationship between pressure differential, Δp, and the maximum deflection, Wmax, of the specimen was obtained:(23)Wmax=309.58 (Δp)where the units for pressure and deformation are atm and nm, respectively. It is worth noting that the above relationship is valid for both bombing and release stages since the deformation is within the elastic range. This was confirmed again in the actual measurement for cavity pressure evolution.

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.