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306 MEMS and Microstructures in Aerospace Applications

state is flaccid and must be stretched to provide the mechanical protection
from debris impact. To ensure a taut connection, the CP1 is procured in a taut
configuration, and then epoxied to one side of the window and then cured. Sand-
wiching the CP1 attach between the two windows, reinforces the connection.
With the window assembly in place, the CP1 film is suspended several millimeters
above the shutters, thus providing a barrier layer between the actual die and the
environment.
Electricalconductivityofthefilmisachievedthroughapplication ofathincoating
of indium tin oxide (ITO), a transparent electrical conductor. In sufficiently thin
coatings ITO does not change the IR performance of the window. ITO coating serves
toprotecttheCP1fromdegradationinthepresenceofatomicoxygen.Allthestructural
members of the MEMS shutter array radiator assembly were made of aluminum 6061
and finished with a clear anodize treatment, followed by a yellow irridite.
An exploded view of the MSA radiator assembly is shown in Figure 13.4.
Additional information on the packaging of MEMS devices is found in Chapter 12
but clearly contamination, handling concerns, and functionality are the key ingre-
dients to successful packaging scheme.

13.7 CONCLUSION
For space applications, MEMS devices are susceptible to environment-induced
damage both on-ground and on-orbit. The potential damage may occur at any
stage of the mission but they are especially prone to surface contamination prior
to the prepackage phase.
The damage impact is alleviated by implementing prudent handling and con-
tamination control practices. Facility for manufacturing and assembly must be
maintained at adequate cleanliness conditions with proper procedures established.
Personnel handling MEMS devices must be properly trained with special attention
to preclude ESD damage to the devices. To achieve the best protection, MEMS
devices must be isolated in a hermetic package or protected with covers whenever
possible.
CCP delineates a comprehensive contamination control program for a mission.
MEMS devices as an integral part of the mission must follow handling and
contamination guidelines established in the CCP in order to meet mission require-
ments.

REFERENCES

1. C.H. Mastrangelo and G.S. Saloka, Dry-release method based on polymer columns for
microstructure fabrication, Proceedings of the 1993 IEEE Micro Electro Mechanical
Systems — MEMS, February 7–10 1993, Fort Lauderdale, FL, USA, IEEE, Piscataway,
New Jersey, pp. 77–81 (1993).
2. G.T. Mulhern, D.S. Soane, and R.G. Howe, Supercritical carbon dioxide drying for
microstructures, Proceedings of the 7th International Conference on Solid-State Sensors
and Actuators, Transducers ’93, Yokohama, Japan, pp. 296–299 (1993).

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