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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: Kenny
Date posted: Sun Oct 20 7:30:27 US/Eastern 2002
Subject: ESS
Message:
I would like to clarify what is the recommended number of cycles for ESS? I know that by overspecifying the number of cycles will go into the useful life of the equipment so is there a guideline to tell us what's the limit? And for temperature ESS what is the acceptable rate of change of temperature?


Reply:

Subject: ESS Testing
Reply Posted by: bwd (bdudley@alionscience.com )
Organization: RAC
Date Posted: Tue Oct 22 8:24:24 US/Eastern 2002
Message:
I would suggest that you consider the stress screening cycling factors that are listed in the Reliability Toolkit; Commercial Practices Edition, which is available from our product catalog. The basic factors for circuit boards include temperature cycling -50 to 75 degrees C for 20 cycles. If it is at the unit level then -40 to +70 degrees C for 12 cycles should be considered. System level factors are -40 to 60 degrees C for 12 cycles. Rapid change in temperature works the best in eliminating failure defects. The impact of testing on the life of the product can be calculated from the information presented in MIL-HDBK-344, Environmental Stress Screening of Electronic Equipment.


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