Hi Everyone!

I would like to find MTTF of PCB.
For that I have collected the FIT rates of major components(ICs, Mosfets, etc.) present on PCB by contacting manufactureres.
Now I have all the FIT values.
So MTTF would be just summing the FIT rates of all components and taking its inverse right?

By appplying this formula will I get the MTTF of complete PCB? or I am missing something?
Please help if anyone has done this before.

I also wanted to know if there is any software which directly calculates MTTF of PCB.
Kindly suggest if anyone is using it.

Thanks in advance!

Best Regards
Vishakha

 

How you combine things depends on a number of factors. Just summing up the FIT values relies on the assumption that any one failure equates to a failure of the entire assembly. Is that the case here, or have you designed in redundancy for some of the components?

What about the failure rate of the board itself? Is it sufficiently low that it can be discounted?

What about the non-major components? They may individually have low rates, but if you have a lot of them, you should take them into account to.

 

Hey WBahn!
Thanks for your reply. I have also collected FIT rates of Capacitors and resistors but I wasn't sure if I should take them into consideration. This is new topic for me. 'have you designed in redundancy for some of the components? ' What is designing redundancy for some components? what does it mean? Please guide thanks!

 

Hey WBahn!
Thanks for your reply. I have also collected FIT rates of Capacitors and resistors but I wasn't sure if I should take them into consideration. This is new topic for me. 'have you designed in redundancy for some of the components? ' What is designing redundancy for some components? what does it mean? Please guide thanks!

It means is your design such that if a particular component fails that the circuit will still work. Unless you have deliberately design the circuit to be fault tolerant, this probably doesn't apply