RMQSI Answers Forum › Category: Electrical Component Reliability › Mil HDBK 217F n2 negative temperature
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louis DEQUIDT asked 6 years ago

How can I calculate a failure rate with negative temperature using the “mil HDBK 217F notice 2”?

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rwisniewski Staff answered 6 years ago

Per paragraph 3.4.1 of MIL-HDBK-217F, “Extrapolation of any of the base failure rate models beyond the tabulated values such as high or sub-zero temperature, electrical stress values above 1.0, or extrapolation of any associated model modifiers is completely invalid”.
The temperature tables in MIL-HDBK-217F typically provide PI T values for temperatures down to 0°C to 25°C, dependent upon component type.  As a result, dependent upon the component composition of your assembly, the use of these models at temperatures below 0°C to 25°C would not be recommended.