Calculating MTBF with Polimore for Confused Users

[lcr2139]

I am confused as to how to calculate MTBF. I am using a website called Polimore, http://www.polimore.com/index.php?P=1000110&F=home.html I input all of the subcomponents of my system and their MTBFs and then I get the MTBF for the system. The thing I am confused of is what to do if I am using more than one of the subcomponents. For example, I am using 5 of the same capacitor. Do I input this capacitor 5 times? Will this change the MTBF at all?

 

[tasp77]

I would think any of the caps could fail, so wouldn't the MTBF decrease?

If there were a million caps, you'd have a million more ways it could fail, after all.

I would ask, however, are the caps in series? Perhaps you want to achieve a certain capacitance value otherwise unavailable?

If so, you might treat the stack as one cap (I am assuming the voltage rating of an individual cap is sufficient by itself, so a stack of 5 would see far less than supply voltage).