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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: Ali Ashraf (ali.ashraf@appl.ge.com )
Organization:General Electric
Date posted: Fri Oct 20 9:31:01 US/Eastern 2000
Subject: Arrhenius equation. What is the value for Humidity acceleration Factor
Message:
What is the value for Humidity Acceleration Factor in Arrhenius equation to calculate the Duration of Test time(hours).


Reply:

Subject: Humidity Acceleration Factor
Reply Posted by: Bruce Dudley (bdudley@alionscience.com )
Organization: Reliability Analysis Center
Date Posted: Mon Oct 30 13:45:32 US/Eastern 2000
Message:
The acceleration constant "n" in the Peck temperature and humidity model has a general range of 2 to 5 depending on the material being tested. In the Peck paper, "A Comprehensive Model for Humidity Testing correlation", 1986 International Reliability Physics Symposium Proceedings, a value of 2.66 to 4.64 has been reported based on testing. For plastic microcircuits, the RAC has used a value of 3.0 in evaluating HAST (highly accelertated stress testing) test data for the "Reliable Application of Plastic Encapsulated Microcircuit" report. If the stress testing is only for solder joints, then the lower level of 2 is recommended. The only truely accurate method of determining the value of the constant is to perform multiple tests and evaluate the results.


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