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Calculating Failure In Time (FIT) Rate for KEMET Capacitors

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Understanding the performance of a component over time can help to estimate your device’s operational lifetime. Changes in applied voltage and temperature will have an effect on an individual component’s lifetime. As a baseline, KEMET provides data that can be used with the MIL-HDBK-217[sre.org] formula to calculate Failures In Time (FIT) for ceramic and tantalum capacitors. Measuring the number of failures over time provides a failure rate (λ). The failure rate that occurs during one billion device hours is called the Failure In Time (FIT). In other words,

FIT as Device Hour Failures

Equation 1: FIT

The Mean Time Between Failure (MTBF), or for components, the Mean Time To Failure (MTTF) is the distribution for a population of parts. MTTF can be determined by taking the reciprocal of FIT (λ).

MTTF Equation

Equation 2: MFFT

Failure In Time (FIT) Example

This application note walks through an example of calculating FIT for a capacitor. The example uses a KEMET ceramic capacitor and the KEMET FIT Calculator tool.

Related: KEMET FIT Manual

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