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Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum (src_forum@alionscience.com )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

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Original Message:

Posted by: Sadat Hussain (sadath@nortelnetworks.com )
Organization:Nortel Networks
Date posted: Mon Jan 28 16:32:48 US/Eastern 2002
Subject: ASIC Reliability
Message:
Are there any generic guidelines for ASIC reliability? -Useful Life? -Average failure rate Things I don't know but want to find out: - Number of machine on/off cycles = ??? - Number of Machine Mini-cycles = ??? - Mini cycle duration = ??? * A mini-cycle is defined as a significant deviation from normal power on operation. From what a vendor tells me, this is the number of "unusual" power up cycles and the info is used for second level attach reliability analysis Can someone please provide me some typical values for the above parameters??


Reply:

Subject: ASIC Reliability
Reply Posted by: B. W. Dudley (bdudley@alionscience.com )
Organization: Reliability Analysis Center
Date Posted: Wed Feb 6 12:10:59 US/Eastern 2002
Message:
From a search of the current data, I was able to find some information that could be useful as a generic guide for ASIC (application specific integrated circuits)reliability: The average life estimate for a PEM (plastic encapsulated microcircuit) is about 20 years or more depending on operation and conditions. Hermetic devices could have a longer life as the corrosion failure mechanism will be eliminated. The average failure rate varies from a low of 0.14 failures per billion hours to a high of 65.6 failures per billion hours. The expected value is 5.7 failures per billion hours for controlled conditions. This information is from six manufacturers of PEMs. Machine on-off cycles vary by application and type. Some cycling rates as are shown in the Reliability Toolkit are as follows: Computer Systems -- 1500 cycles per year Telecommunication Systems -- 37 cycles per year Aircraft Electronic Systems -- 1000 cycles per year Automotive Electronic Systems -- 8700 cycles per year Information on “mini-cycles “ is not readily available as there seems to be some confusion in the industrial world about this parameter. If the mini-cycle is truly a power on-off by another name then reliability will be impacted and cycle rate as shown above would apply. If this is a term for reduced power i.e. quiescent time, the reliability should not be impacted. Power cycling is a concern for most electronic components as the rate of failure can increase and the useful life decrease. When a power supply is turned on, there is a delay while the power supply control circuits establish correct conditions. During this short interval, it is possible for the output voltage to exceed normal value resulting in a “turn-on voltage overshoot”. Integrated circuits commonly have some tolerance level that could be exceeded in this overshoot condition. If this occurs frequently, damage could be introduced.


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