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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: Ian Carmichael (ian.carmichael@kymata.com )
Organization:Kymata Ltd.
Date posted: Mon Jul 31 6:56:17 US/Eastern 2000
Subject: Reliability Sources
Message:
I would be grateful if somebody could provide me with information relating to generic failure rates of Epoxy resins and semiconductor wafer chips. Thanks in anticipation.


Reply:

Subject: Reliability of Epoxy and Wafer Chips
Reply Posted by: Bruce Dudley (bdudley@alionscience.com )
Organization: Reliability Analysis Center
Date Posted: Mon Jul 31 15:32:48 US/Eastern 2000
Message:
Failure rates for epoxy elements were not included in our data bases probably due to the nature of the use of the product. In curcuit board production use, the epoxy is often used as a temporary adhesive to hold the surface mount components until reflow or wave soldering is performed. Failure of the epoxy after this operation is not relevant as the solder connection will hold the device. Failure before will result in a missaligned component and is a significant manufacturing problem. Most vendors have produced epoxy test data that includes strength and cure/temperature times which should be evaluated before selecting a product. If the epoxy element is part of the circuit board itself, then failure rates for circuit boards should be obtained from the manufacturer's data. For the wafer chips one should use of a failure rate that does not include the effects of the package part of the device. We suggest that the RAC PRISM prediction program be considered for this need. In this program, device failure rates are broken down into chip failure causes and package or environment causes plus extraneous causes. This PRISM model will allow you to estimate the failure impact solely due to chip failure mechanisms. This product is avalable form the Reliability Analysis Center by calling 1-888-722-8737.


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