Dear Doug:

Thank you very much for your reply. Where can I get a copy of Bellcore 332?
Is it for free?

Best regards

Kang


>From: Doug <[log in to unmask]>
>Reply-To: "TechNet E-Mail Forum." <[log in to unmask]>, Doug <[log in to unmask]>
>To: [log in to unmask]
>Subject: Re: [TN] Reliability Prediction Methods
>Date: Mon, 12 Jun 2000 23:32:10 -0700
>
>Kang Zhang wrote:
> >
> > Hello all
> >
> > Two questions:
> >
> > 1. Is there any big difference in reliability prediction results between
> > using MIL-HDBK-217F notice2 and using Bellcore? I just try MIL. Using
> > Bellcore can get "better" MTBF or "worse"?
> >
> > 2. Except the above two, are there any other methods to predict the
> > reliability of electronic components, such as FET, Bipolar?
> >
> > Any inputs are very welcome. Thanks in advance!
> >
> > Kang
>
>For #1 ...
>My opinion only, I've no experience with the MIL-217
>(what I'm comparing Bellcore with MIL-217 is what a
>  colleague I saw go through with 217), but I've been
>working with Bellcore 332 for a couple of years now.
>
>Bellcore will give you better "numbers".  The assumption
>with Bellcore 332 is 50% electrical stress and uniform
>temp stress on the part (usually 40 degrees C).  That's
>a global assumption, i.e. all parts throughout the entire
>system.  The guy I knew who worked extensively with 217
>made individual electrical and temp stress measurements
>for the MIL contracts he worked on.  Very tedious work.
>I'm not sure if that's really necessary for 217, but
>that's what the guy I knew did.
>
>For #2 ...
>Yes.  The reliability numbers the semiconductor
>industry produces comes from using the Arrhenius
>equation in conjunction with accelerated temp
>testing of the chip. Emailed back and forth with
>one of the reliability engineers over at Intel
>about it a couple of years ago.  Since, they use
>so many different types of material in the making
>of a chip, the activation energy (which is needed
>for the Arrhenius equation) is guessed at.  But
>this is all used for the accelerated temp testing
>they do for chips.  But the bottom line is that
>they develop a lot of empirical data over time.
>So they're pretty accurate.
>
>Just an aside.  I was corrected by a vendor once rather
>sternly for using MTBF for a part.  They were adamant
>that "MTBF" was to be used for something that was to
>be repaired such as a printed circuit board.  The correct
>acronym for a part is MTTF or Mean Time To Failure. The
>key words being "Between" versus "To".  You don't
>"repair" a chip or a fuse.  It's from this type of
>database and field repair reports the come into Bellcore
>that the FITs (Failure In Time) data tables in the back
>of 332 are generated.  I believe 332 edition 4 had
>some corrections to some FITs values in edition 5
>to make them more realistic.
>
>Regards, Doug McKean
>
>##############################################################
>TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
>##############################################################
>To subscribe/unsubscribe, send a message to [log in to unmask] with following
>text in
>the body:
>To subscribe:   SUBSCRIBE TECHNET <your full name>
>To unsubscribe:   SIGNOFF TECHNET
>##############################################################
>Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
>additional
>information.
>If you need assistance - contact Keach Sasamori at [log in to unmask] or
>847-509-9700 ext.5315
>##############################################################

________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
##############################################################