I'll give you my favorite engineering answer - It depends.

If you are trying to determine if a fabrication or assembly process is
Bellcore-compliant, the answer is no.  Bellcore compliancy is only obtained
through the SIR and Electromigration testing in Chapter 13 of TR-78.

If you are trying to determine if a vendor has acceptable product, and you
don't really care about Bellcore compliance, then I would say the answer is
yes.  The seven day SIR test, IPC-TM-650, method 2.6.3.3 rev A, is an
alternative.

The Bellcore electromigration test is 85C/85% RH, so is the SIR method.
The Bellcore test goes 96 hours before the first measurement in an unbiased
state, then a bias of 10 volts is applied.
The SIR test is biased from the start with a 50 volt bias.
The Bellcore test is not tied to an absolute resistance value.
The SIR test has a minimum of 100 megohms.

I'm not really trying to bash the Bellcore electromigration test, but I
understand the time constraint.  In my opinion (that and 50 cents gets you a
Diet Coke), you are best to do both methods concurrently.  The SIR test
should be able to allow you to make the decision in 7 days vs. 25 days.
 Alternatively, you could interrupt the electromigration test after 7-10 days
and see if you have any signs of corrosion or metal migration.  It has been
my experience that if you have not seen electromigration and corrosion after
7 days at 85/85 and a 50 volt bias, you would not see it in 500 hours.
 Again, my opinion.

Hope this was helpful.  If you want to discuss it in greater depth, give me a
call at (317) 457-8095.

Doug Pauls
CSL, Inc.
[log in to unmask]

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