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Reliability is the probability of a part
performing its specified purpose for the period intended under the operating
conditions encountered. This definition stresses three elements: performance, time, and operating
conditions. These factors play an important role in the part’s
reliability.
a. Performance is satisfactory operation in
accordance with clearly specified, described, or defined criteria. The military
uses performance specifications (e.g., MIL-PRF-38535 for Microcircuits or
MIL-PRF-19500 for Discrete Semiconductors) for part types described in this
document/database. Performance specifications are described in each
section.
b. Time is the period during which a specified
degree of performance is expected. It is the cornerstone of reliability because
without a knowledge of the probabilities of individual parts functioning for a
given time, there is no way of assessing the probability of the system
performing a function for a given time.”
c. Operating conditions comprise the environment in
which a part is expected to function. Typical factors are temperature, humidity,
shock, and vibration. MIL-HDBK-338B, Electronic Reliability Design Handbook,
should be used in conjunction with this
document/database.