The Definitive Guide to an Electronic Assembly Design Review / 4
What is Physics of
Failure (PoF)?
The knowledge and
understanding of the
processes and
mechanisms that
induce failure to
predict reliability and
improve product
performance.
What is Mean Time to
Failure (MTTF)?
The length of time a
device or other product
is expected to last in
operation.
What is Mean Time
between Failure?
The predicted elapsed
time between inherent
failures of a mechanical
or electronic system
during normal system
operation.
1
Establishing a Reliability (cont.)
Best practices include:
Set reliability goals based on survivability. This is often bound by confidence levels, such as 95% reliability
with a 90% confidence level over 15 years.
Avoid mean time to failure (MTTF) and mean time between failures (MTBF) which do not measure
reliability. Historically, MTBF has been calculated using empirical prediction handbooks, which assume a
constant failure rate that is not always correct.
Employ physics of failure (PoF) to acquire a deeper understanding of how your product's desired
lifetime and environment affect its design. This takes substantial effort, but you receive a valuable return
on investment.
