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: Jim Ramsden ( )
Date posted: Mon Jun 12 15:12:12 US/Eastern 2000
Subject: Hermetic vs Nonhermetic ICs
In trying out the demo I stumbled upon something that puzzles me. I took a linear IC and changed it from hermetic to nonhermetic. Its failure rate increased as expected. But I also noted that the default thermal rise increased from 13C to 25C. So I played a what-if, and left the part as non-hermetic but forced the thermal rise to be 13C. When I did, the failure rate of the IC decreased from 0.04261 to 0.02897 in going from hermetic to non-hermetic. I was wondering if I am misunderstanding something about the RACRate model? And this leads to a more general question, are the details behind the RACRate models (what the lambda and pi factors are and what impacts them) documented in detail somewhere ? The on-line help refers to Appendices A-G, but I can't seem to find them anywhere with the demo. Is there a way I can get a copy ? Thanks...jrr
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