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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: S. White (simon.white@zelana.com )
Organization:Zellweger Analytics Ltd
Date posted: Thu Jul 27 7:30:35 US/Eastern 2000
Subject: Ceramic chip capacitors generic failure rate
Message:
How come ceramic chip capacitors have a generic failure rate that has become worse in the Notice 2 re-edition of MIL-HDBK-217? Data from MIL-HDBK-217 Appendix A-8 shows that in a Gf environment failure rate = 0.0022 for the first edition and Notice 1 but Notice 2 shows a rise to 0.053. Aluminium Oxide capacitors have also changed 0.061 fpmh in the first and Notice 1 editions but a radical improvement to 0.019 in Notice 2. Is this a mistake in Notice 2? I would have expected Ceramic Chip capacitors to be far more reliable than more complicated to make Aluminium Oxides.


Reply:

Subject: Ceramic Chip Capacitor
Reply Posted by: Bruce Dudley (bdudley@alionscience.com )
Organization: Reliability Analysis Center
Date Posted: Thu Jul 27 9:33:38 US/Eastern 2000
Message:
The reliability failure rates for ceramic chip and Al electrolytic capacitors that you quoted are the latest values from Mil-Hdbk-217 Notice #2 and the supporting data are detailed in the technical report RL-TR-92-197 "Reliability Assessment of Critical Electronic Components". The changes that were incorperated into the Notice #2 were from this technical report. Base falure rates for the ceraminc capacitor changed from the previous Mil-Hdbk-217 as more data were accumulated in the technical report study. If you do not like these failure rates, you should investigate our new models in the RAC PRISM program. The capacitor models from the PRISM represent the latest failure data and models for capacitors. Using default conditions for a ground environment, the failure rate for a ceramic chip capacitor is approximately 0.00093 failures per million hours and the AL electrolytic capacitor is 0.0011 failures per million hours. These ae roughly the same but less than the out of data Mil-Hdbk-217.


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