PRISM Forum - Message Replies


Topic: PRISM Questions and Answers
Topic Posted by: SRC (src_forum@alionscience.com )
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: S.Arun Kumar
Date posted: Wed Feb 9 12:48:39 US/Eastern 2005
Subject: PRISM Model for PCBs
Message:
When we want to compute the FR for PCB, we were not able to find a model for it in PRISM. We are Currently using MIL 217FN2 for PCBs.

Now the Questions we have are

Q1. How do I compute the Failure Rate for the PCBs using PRISM.
Q2. In MIL 217FN2 we have Model for PTH and SMT Version of the PCB. My Query is that since we take the solder joint factor, Cycling Rate Factor for most of the components we are using in PRISM, do we need to separately calculate the FR of the PCB (SMT Technology).


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Reply:

Subject: PRISM Model for PCBs
Reply Posted by: Rajeshkumar
Date Posted: Wed Nov 23 6:05:26 US/Eastern 2005
Message:
While dividing the PRISM failure rate by duty cycle, for small duty cycles ie less than 10%, failure rate is increased by 10 times,which is very high for certain applications. How can we consider this dutycycle factor in converting the calender hours to operational hours?


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