Mean time (to) first failure (MTFF, sometimes MTTFF) is a concept in reliability engineering, which describes time to failure for non-repairable components like an integrated circuit soldered on a circuit board. For

repairable A repairable component is a component of a finished good that can be designated for repair. Overview Repairable components tend to be more expensive than non-repairable components (consumables). This is because for items that are inexpensive to ...

components like a replaceable light bulb the concept of

mean time between failures Mean time between failures (MTBF) is the predicted elapsed time between inherent failures of a mechanical or electronic system during normal system operation. MTBF can be calculated as the arithmetic mean (average) time between failures of a system ...

is used to describe the failure rate. MTFF and MTTF (mean time to failure) have identical meanings. The key is that this is a non-repairable and non-recoverable failure. For example, the failure of a TV typically isn't measured by this criterion because the TV can be repaired. However, if this failure was due to a burned out integrated circuit that circuit itself can't be repaired and must be replaced. The failure of that circuit is measured by mean time to failure. It's generally used to predict the first failure after manufacturing

References

Engineering failures Reliability engineering {{Engineering-stub