Forum Questions and Answers
Topic: PRISM Questions and Answers
Topic Posted by: SRC ( )
Organization: SRC
Date Posted: Wed Jan 12 8:33:33 US/Eastern 2000
Topic Description: Welcome to the PRISM forum! Please feel free to post your questions and comments about the PRISM assessment software here.

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Original Message:
Posted by: Chris Wright ( )
Organization:BAE SYSTEMS
Date posted: Wed Mar 6 15:32:13 US/Eastern 2002
Subject: RACRates IC Model Questions
I have been evaluating the PRISM IC RACRates model for my company and have a few questions. First, how is it that the pi-factors tend to go down for non-hermetic devices versus hermetic? This seems counter intuitive, especially for pi-RHT. The overall device failure rate ends up being lower for a non-hermetic part. Is this true? Second, it appears that pi-TO, pi-RHT, pi-DT and Lambda-SJ all vary with device temperature, but there is nothing in the manual which describes these relationships. I am also puzzled as to why pi-RHT would change when I add a junction temperature rise, since this is supposed to be a non-operating factor. The junction temperature rise should only apply to operating factors. When non-operating the device should be at its non-operating ambient temperature with no junction temperature rise since it wouldn't be dissipating power at that point.
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