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Design and Application of Space-Based MEMS 329

techniques sets the community up for the same problems seen in the EEE world
today.
An additional quandary in turning to the ‘‘known world of integrated circuits’’
is that the program bases its strength in rigid piece-part testing. Technically, the
MEMS-based device falls under the NASA definition of a part. However, in some
cases, a MEMS-based device could fall under the NASA definition of an assembly,
where a functional group of parts such as a hinge assembly and antenna feed of a
deployment boom would be included. Given this cross-level and lack of a direct fit
into standard NASA hardware nomenclature, the traditional test methodologies are
not always a natural fit. The workhorse for EEE parts has been the QPL documents
and MIL-STD-883: General Test Methods for Microcircuits.
The importance of beginning a rigorous test program at the lowest element
possible and building a rugged program cannot be underestimated. However,
building on the current test methods where direct fits are often missing requires
tailoring at each step. In addition, in order to work with new technology and untried
systems, a reliance on good process control must be built in. Plans for inspection,
quality assurance, and specifications are provided as guidelines with the intent of
tailoring and adding process control steps at each interface level.
The original reliability prediction handbook was MIL-HDBK-217, the Military
Handbook for ‘‘Reliability Prediction of Electronic Equipment.’’ MIL-HDBK-217
is published by the Department of Defense based on work done by the Reliability
Analysis Center and Rome Laboratory at Griffiss AFB, NY.
The MIL-HDBK-217 handbook contains failure rate models for the various part
types used in electronic systems, such as active microcircuits, semiconductors, and
passive components such as resistors, capacitors, relays, switches, connectors, etc.
These failure rate models are based on the best field data that could be obtained for
a wide variety of parts and systems; this data is then analyzed and evaluated, with
many simplifying assumptions thrown in, to create usable models. In the absence of
a large utilization and knowledge base for MEMS, the use of MIL-STD-883 for test
method and either MIL-PRF-38535 or MIL-H-38534 are reasonable interim steps.
Each interface level is then available to be qualified along with the series of
electrical, mechanical, and environmental tests meant to assure long life and final
performance. These tests, where definitive, realize the reliability predictions of
MIL-HDBK-217 and are driven by known activation energies of silicon-based
microcircuits. Unfortunately, there is no equivalent to MIL-HDBK-217 for
MEMS; however, using the documents mentioned before for guidelines is a rea-
sonable approach.

15.3 PHYSICS OF FAILURE (POF) APPROACH
Military specifications and reliability work have historically been based on the
MIL-HDBK-217, ‘‘Reliability Prediction of Electronic Equipment,’’ approach.
Transition from statistical-field failure-based models to POF-based models for
reliability assessment has successfully been demonstrated for MEMS. 4–6 Although

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