Borrowing the FIT calculation from Mil-Handbook-217F, it can be seen that the final failure rate is multiplied by several environmental and electrical factors. The most dominating is the voltage factor as shown in the calculation on this slide. The calculation of the temperature and voltage factors are shown with tables for typical values. The highest factor for the temperature at 125°C is 5.62, or at 125°C, the failure rate is 5.62 times the failure rate at 25°C, because of the temperature. For the voltage, because the exponential factor is 17, the failure rate multiplier increases exponentially as the voltage exceeds 60%. It still has a near unity factor at 50% rated voltage, but the failure rate doubles at 60%, jumping to a multiplier of 14.7 at 70%, 134 at 80%, and close to 1000 at 90%. For this capacitor type, exceeding the recommended derating voltage can lead to very high failure rates.