Thank you Doug!  Does Bellcore TR-332 include a method of estimating the 
FIT/MTBF of inductive devices (transformers, inductors, etc.)?

Thank You, Mel

----------
From:   Doug McKean[SMTP:[email protected]]
Sent:   Thursday, May 01, 1997 9:33 AM
To:     [email protected]
Subject:        Re: Reliability

Mel Pedersen wrote:
> 
> Dear TREG'ers:
> 
> I have been doing some component reliability (failures per million power on 
> hours) estimates using the method outlined in MIL-HDBK-217E.  My questions 
> are:
> 
> a)  how accepted (or, for that matter, accurate) is this method?
> 
> b)  Are there any other methods that are more accepted?
> 
> c)  Is there any reference in any Bellcore documents about this or any other 
> method for estimating reliability of a component?  Or is testing the only 
> accepted method?
> 
> Thank You!
> 
> Mel Pedersen                    Midcom, Inc.
> Homologations Engineer          Phone:  (605) 882-8535
> [email protected]       Fax:    (605) 886-6752

Hi Mel, 

Yes, you might want to try 

     Bellcore TR-332, Issue 5, December 1995. 

Try - 

     Bellcore
     Customer Service
     60 New England Avenue
     DSC 1B-252
     Piscataway, NJ 08854-4196
     Tel: 1-800-521-2673

Or their website  

     http://www.bellcore.com/ 

As to FITs. 
A FIT = 1 is 1 failure in 1 billion hours. 
Obviously a higher FIT number means a less reliable part. 

MTBF and FITs are related by  MTBF = [1/FIT]*10^9 

Bellcore 322 gives a standard set of FITs for all sorts of 
components. The semiconductor stuff you'll have to try to 
dig out of the mfrs by way of gate count or the FIT itself. 

If you're using accelerated temp testing to confirm this, 
don't pick a particular activation energy for a semiconductor 
to use in the Arrenhius relation. You'll have to come up with 
that emprically. 

Regards, Doug

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