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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: Cathy
Date posted: Thu Mar 29 17:21:13 US/Eastern 2001
Subject: Passive Component "Uprating"
Message:
Is there any standard or guideline for passive component uprating? Actually I need the justification for PiT used in MIL-HDBK-217 prediction. For example, what's the PiT of a resistor (rated at 150C) at 240C? Thanks.


Reply:

Subject: Passive Component "Uprating"
Reply Posted by: David Dylis (ddylis@alionscience.com )
Organization: Reliability Analysis Center (RAC)
Date Posted: Mon Apr 9 9:03:33 US/Eastern 2001
Message:
I spoke with a number of individuals regarding your situation and question. The result was that 240*C is, as you are probably aware, a very stressful/not recommended application. I was not able to specifically identify any uprating conditions for your application, however, did receive the following guidance: The 240*C operating temperature is going to require welded part and electronic assembly construction and special materials. Most of the Tin/Lead solders have a melting temperature of 183*C. Exposure to a temperature of +240*C is going to cause failure of most soldered electronic assemblies within minutes due to separation of solder joints. It would be extremely difficult to recommend a value for PiT as the part is being used outside of its temperature range. I would recommend that life testing be performed to assess the life of this part at these extreme conditions. If you have any further questions feel free to contact me. David Dylis Data and Information Manager Reliability Analysis Center (RAC) 201 Mill St. Rome, NY 13440-6916 Phone: (315) 339-7055 Fax: (315) 337-9932 Email: ddylis@alionscience.com


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