Quality Levels in MILHDBK217

[George Azzopardi]

A common problem when trying to do reliability prediction using the models in MIL-HDBK-217 is how to assign quality levels to individual components. You could simply assign the lowest quality level specified in the model since it is difficult to find this kind of info on a daatsheet. But by doing so the values obtained are too conservative. How can i make a good judgement on this quality level? The system under study is used in the automotive industry. Specifically for surface mount resistors which qulaity level should be used?

[Daniel]

There are lots of problems with 217. That’s why it was discontinued. No matter what you assume the answer isn’t going to reflect reality. The idea of 217 was to compare not necessarily predict, so as long as you are consistent in what you assume it should be OK.