Burn-In Arrhenius Acceleration Factor and FIT Rate Calculator
Burn-in and HTOL turn a few weeks at high temperature into years of equivalent field life. This calculator applies the Arrhenius model so you can see the acceleration factor, the equivalent use time and the FIT from your results.
Your numbers
Depends on the failure mechanism. 0.7 eV is a common default for generic assessments; use your qualified value if you have it.
Junction, not oven ambient. Include self-heating.
Your results
Arrhenius acceleration covers thermally activated mechanisms only. Voltage, humidity and thermal cycling need other models. A point estimate is not a reliability claim: use a chi-square upper confidence bound and your qualification standard (for example JEDEC JESD47 and JESD85) for customer FIT reporting.
Acceleration factor vs activation energy
Sweeps Activation energy from 0.3 to 1.2, holding your other inputs fixed.
Reliability data tied to lots and ERP records
Optional: ask how to link burn-in results to lot genealogy and supplier data in your own systems.
Optional. The tool and every export work without this. No spam.
How to use the calculator
Enter the activation energy for the mechanism you are screening, the junction temperature in use and under stress, the device count, stress hours and observed failures. The tool returns the acceleration factor, total equivalent device hours, equivalent years per device and a point-estimate FIT. Move the activation energy slider to see how sensitive the result is: a small change in Ea makes a large change in acceleration, which is the main uncertainty in any burn-in claim.
- Use junction temperature, including self-heating from power.
- Use the Ea your qualification data supports for the mechanism.
- Do not combine mechanisms with different Ea in one run.
The Arrhenius model
The acceleration factor is AF = exp[(Ea/k) x (1/Tuse minus 1/Tstress)], where k is Boltzmann's constant, 8.617 times 10 to the minus 5 electron volts per kelvin, and temperatures are in kelvin. FIT is failures per 10 to the 9 device hours, so FIT = failures / (devices x hours x AF) x 10 to the 9. For a zero-failure result, the point estimate is zero, so use a chi-square-based upper bound at your chosen confidence level for any customer commitment.
Worked example
With Ea of 0.7 eV, 55 C use and 125 C stress, the acceleration factor is about 78. A 1000 hour stress on 231 devices gives roughly 18 million equivalent device hours, or about 8.9 years of use per device. One failure would give a point FIT of about 55. With zero failures, the 60% confidence upper bound is commonly computed with a chi-square of 1.83 for two degrees of freedom, but check the factor required by your standard.
Common mistakes
Using oven ambient instead of junction temperature will understate the stress. Using the same Ea for every failure type overstates acceleration for low-Ea mechanisms. Reporting zero FIT from a zero-failure test is another error. Finally, check that the hours you enter are actual powered stress hours, not the calendar duration including loading, cooldown and readpoint downtime.
Frequently Asked Questions
Which activation energy should I use?
Use the value that your qualification data or the relevant standard supports for the specific failure mechanism. Many generic assessments use 0.7 eV, but oxide, metallization and contamination mechanisms have different values, so a single number is a simplification.
Why is junction temperature required?
Failure mechanisms respond to the temperature at the die, not the oven air. At high power the junction can be many degrees above ambient. Using ambient understates stress and overstates the time the test represents.
What is FIT?
FIT means failures in time: one failure per billion device hours. A part with 50 FIT is expected to fail at a rate of 50 per billion hours of operation under the stated conditions.
Can I use this for thermal cycling or humidity tests?
No. Those use different acceleration models, such as Coffin-Manson for cycling and Peck for temperature, humidity and bias. This tool covers Arrhenius temperature acceleration only.
If your reliability results live in spreadsheets and test systems, Netray can help build a private reporting layer that links lots, stress conditions and FIT calculations to your ERP and quality records.
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