FIT Rate & Reliability Calculator
Calculate Failures in Time (FIT) and MTBF for electronic components.
Understanding FIT Rate and Reliability
In the world of reliability engineering, specifically regarding semiconductor and electronic components, FIT (Failures In Time) is a standard unit used to express the expected failure rate of a component or system.
What is FIT?
One FIT is defined as one failure per billion ($10^9$) device-hours of operation. It is a statistical measure that helps engineers predict how many components in a large population are likely to fail over a specific timeframe.
The Calculation Formula
The basic formula for calculating the FIT rate based on observed test data is:
FIT = (Number of Failures / Total Device Hours) × 10^9
Where Total Device Hours = Number of Units × Operating Hours per Unit.
FIT vs. MTBF
While FIT describes the frequency of failures, MTBF (Mean Time Between Failures) describes the average time elapsed between failures. They are inversely related:
- MTBF (Hours) = 1,000,000,000 / FIT
- FIT = 1,000,000,000 / MTBF (Hours)
Practical Example:
Suppose you are testing a batch of 500 microcontrollers for 2,000 hours. During this test, 1 unit fails.
- Total Device Hours = 500 units × 2,000 hours = 1,000,000 hours.
- FIT Rate = (1 / 1,000,000) × 1,000,000,000 = 1,000 FIT.
- MTBF = 1,000,000,000 / 1,000 = 1,000,000 hours.
Why FIT Matters in Engineering
FIT rates are critical for calculating the overall reliability of complex systems. For instance, if a circuit board contains 100 components, each with a FIT of 10, the total FIT for the board is 1,000 (assuming a series reliability model), meaning you can expect one board failure every million hours.