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Microelectromechanical Systems and Microstructures in Aerospace Applications 11

to final mission success. Handling and contamination control is discussed relative to
the full life cycle from the very basic wafer level processing phase to the orbit
deployment phase. MEMS packaging will drive the need to tailor the handling and
contamination control plans in order to assure adequacy of the overall program on a
program-by-program basis. Plan elements are discussed at length to assist the user in
preparing and implementing effective plans for both handling and contamination
control to prevent deleterious effects.
The space environment provides for a number of material challenges for MEMS
devices, which will be discussed in Chapter 14. This chapter addresses both the
known failure mechanisms such as stiction, creep, fatigue, fracture, and material
incompatibility induced in the space environment. Environmentally induced
stresses such as shock and vibration, humidity (primarily terrestrial), radiation,
electrical stresses and thermal are reviewed along with the potential for combin-
ations of stress factors. The chapter provides an overview on design and material
precautions to overcome some of these concerns.
Chapter 15 begins with a discussion on several approaches for assessing the
reliability of MEMS for space flight applications. Reliability for MEMS is a
developing field and the lack of a historical database is truly a barrier to the
insertion of MEMS in aerospace applications. The use of traditional statistically
derived reliability approaches from the microelectronic military specification arena
and the use of physics of failure techniques, are introduced.
Chapter 16 on ‘‘Quality Assurance Requirements, Manufacturing and Test’’
addresses the concerns of the lack of historical data and well-defined test method-
ologies to be applied for assuring final performance for the emerging MEMS in
space. The well-defined military and aerospace microcircuit world forms the basis
for assurance requirements for microelectromechanical devices. This microcircuit
base, with its well-defined specifications and standards, is supplemented with
MEMS-specific testing along with the end item application testing as close to a
relevant environment as possible. The objective of this chapter is to provide a
guideline for the user rather than a prescription; that is, each individual application
will need tailored assurance requirements to meet the needs associated with each
unique situation.

1.5 CONCLUSION
Within the next few years, there will be numerous demonstrations of MEMS and
microstructures in space applications. MEMS developments tend to look more like
the growth of the Internet rather than the functionality growth seen in microcircuits
and quantified by Moore’s law. Custom devices in new applications will be found
and will be placed in orbit. As shown in this overview, many of the journeys of
MEMS into space, to date, have been of university or academic grade, and have yet
to find their way into critical embedded systems. This book may be premature as it
is not written on a vast basis of knowledge gleaned from the heritage flights for
MEMS and microstructures. However, it is hoped that this work will help prepare
the way for the next generation of MEMS and microsystems in space.

© 2006 by Taylor & Francis Group, LLC