FEDEVEL
Platform forum

joselopezBarcelona , 08-10-2023, 10:53 AM

Hi, I would like to learn how to calculate the MTBF of a board.
Does anyone could help me or give me some links to learn it please
The best

Selvaprasad , 08-11-2023, 09:57 AM

I hope there is some kind of software like ram commander, item toolkit.

QDrives , 08-11-2023, 07:48 PM

I assume an assembled board with all components?
Then the question is MTBF (Mean Time Before Failure) or MTTF(d) (Mean Time To Dangerous Failure)?
The easiest way is to use the FIT (Failure In Time) value that is often given by the manufacturer. FIT is 1billion hours/MTTFd, and MTTFd is half of MTBF.
Both FIT and MTTFd are used for safety (ie. IEC 61508 and ISO 13849)
1) Get the FIT value of each component.
2) Add them all up.
3) 2 billion hours divided by FIT sum => MTBF of board.

Selvaprasad , 08-12-2023, 04:11 AM

Any documents for reference

joselopezBarcelona , 08-12-2023, 07:27 AM

Thank you QDrives. Yes is for all components. I guess is quite difficult to get all IFT of R, C, diodes,...
Anyway any doc, link or reference to read more please

QDrives , 08-12-2023, 03:48 PM

"...I guess is quite difficult to get all FIT of R, C, diodes,..." -- There are three things:
1) Most semiconductor manufacturers have, or can provide, the FIT/MTTFd values. It may be a bit more work to find that data, but it is often on the sites.
2) For resistors, capacitors, inductors, etc. I used a table that was in ISO 13849(-1?).
3) It is possible to calculate it, but yes, this is quite difficult.
If you want more details, google something like MTTFd

joselopezBarcelona , 08-12-2023, 06:31 PM

Thank you very much QDrives,

QDrives , 08-12-2023, 06:59 PM

And one other advise it to put those values into your schematic library. Have a (special) BoM that lists these number and for any future design it will become easier (faster) to calculate it as most components are already known (for there MTTFd/FIT).

joselopezBarcelona , 08-15-2023, 11:09 AM

Yes, good point, thanks so much