Do you need requirements for a Design FMEA

[david316]

Hi all,

An example of a template for a design FMEA is given in

FMEA 4th Edition Blank P and D FMEA sheets in Excel .xls spreadsheets

One part I am struggling with is when you do a design FMEA at the component level, do you need to define the requirements for a component. At the company I work for, we very rarely define requirements down to a level that you have precise requirements for a specific part. In reality we have a high level requirement that drives a lot of design and is an input into a lot of components. When we are doing an FMEA at a component level we can still identify the function a part it supposed to do (e.g. fail of a capacitor on a power supply stops for device from functioning) without having a specific requirement for a part.

So what is the intent of the "requirement" column in an Design FMEA. Should we ideally have a formal requirement for every specific part (that would need to be formally verified or validated) to feed into the DFMEA or is it ok to just define the parts function and how it can fail?

Thanks

 

[sagai]

Doing DFMEA on component level sounds an endless work for me.
I am not saying that it does not make sense, solely sounds a way to long journey.
DFMEA I have come across with is on system level, whereas measure goes down to functional blocks of the schematic design.

Requirements for the components are usually coming from the target reliability of the electronic board based on the experience that I have.
With other words, the FIT rate of the component should not exceed the remaining budget of the reliablity target (MTBf) of the electronic board.
It is usually not possible to identify upfront the exact remaning budget, regular reviews and calculations of the estimated FIT rate of the electronic board based on the schematic design enables that however. (it still not will be accurate due to PCB design will introduce further FIT budget consumption later)

There are standards setting the bare minimum set of failure types for components, those are more for FTAs I think.

Hope this helps
Cheers