I am conducting a risk assessment study of a system. To do so, I need to know the failure probabilities of its components. Some manufacturers do include this piece of information in their datasheets, other manufacturers don't and in the worst case some manufacturers don't even have a datasheet.
For example, I have been able to find the failure rate for the ATmega128 on page 8 of the datasheet:
Data Retention
Reliability Qualification results show that the projected data
retention failure rate is much less than 1 PPM over 20 years at 85°C
or 100 years at 25°C
On the other hand I have been unable to find any useful information for the CYRF6936 in the datasheet.
Finally, I can't find any datasheet for a linear B5K potentiometer.
- Where/How can I find/estimate failure rates and probabilities when there is no
information available? - Are there any known generic failure rates/probabilities for
electronic components such as sensors or potentiometers?
Best Answer
Your best choice is to ask the manufacturer, and ask them to give you a document, not just a mail.
If for some reason the manufacturer can't give you any information, you have to guesstimate how reliable a part is.
There are several standards which can be used to estimate a MTBF for a part.
I can't really comment on how useful each and everyone of them is, I think in our safety assessments we use different standards.
Siemens and IEC are the ones I already stumbled upon. But in some cases things tend to get very odd. Like failure rates for RAM, where you can get values from almost 0 to so large it dominates the whole system and with a RAM-test you just removed 90 % of the failures and are "done".
On this website I found a few comments on those standards, which suggest that the Mil-HDBK-217 is the most pessimistic guess and if you apply that you'll probably end up on the safe side.
Another source for information is usually the certification authority which is usually involved in the process of getting a SIL certified product for example. But in most cases, they hint you to the same standards, but you get an idea which one they prefer and using that reduces the amount of time spent arguing with them.