Datasheet
5© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 • 864-963-6300 • www.kemet.com A4034_PEH200 • 4/5/2018
Screw Terminal Aluminum Electrolytic Capacitors – PEH200, +85°C
Reliability
The reliability of a component can be dened as the probability that it will perform satisfactorily under a given set of
conditions for a given length of time.
In practice, it is impossible to predict with absolute certainty how any individual component will perform. Therefore, we
must utilize probability theory. It is also necessary to clearly dene the level of stress involved (e.g., operating voltage, ripple
current, temperature and time.) Finally, the meaning of satisfactory performance must be dened by specifying a set of
conditions which determine the end of life of the component.
Reliability as a function of time, R(t), is normally expressed as: R(t) = e-
λt
,where R(t) is the probability that the component will
perform satisfactorily for time t, and λ is the failure rate.
Failure Rate
The failure rate is the number of components failing per unit of time. The failure rate of most electronic components follows
the characteristic pattern:
• Early failures are removed during the manufacturing process.
• The operational life is characterized by a constant failure rate.
• The wear out period is characterized by a rapidly increasing failure rate.
The failures in time (FIT) are given with a 60% condence level for the various type codes. By convention, FIT is expressed
as 1 x 10
-9
failures per hour. Failure rate is also expressed as a percentage of failures per 1,000 hours, e.g., 100 FIT = 1 x 10
-7
failures per hour = 0.01%/1,000 hours.
End of Life Denition
Catastrophic Failure: short circuit, open circuit or safety vent operation
Parametric Failure:
• Change in capacitance > ±10%
• Leakage current > specied limit
• ESR > 2 x initial ESR value