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Date: | Wed, 10 Jul 1996 17:12:07 -0400 |
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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.
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