SRC Forum - Message Replies
Forum: Reliability & Maintainability Questions and Answers
Topic: Reliability & Maintainability Questions and Answers
Topic Posted by: Reliability & Maintainability Forum
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998
Posted by: asphil
Date posted: Fri Apr 16 1:51:19 US/Eastern 2004
Subject: Thermal factor estimation
When using MIL-217, we have to enter thermal parameter.
Although I calculate temperature rising for IC, I can't calculate it for passive components.
How should I do for this?
Subject: Thermal Analysis
Reply Posted by: BWD
Date Posted: Thu May 6 15:09:47 US/Eastern 2004
The failure rate models in MIL-HDBK-217 are based on ambient surrounding temperature except for microcircuits and hybrid devices. Therefore, you only need to estimate the temperature rise near each device. A measurement is the best way, but engineering judgement is usually sufficient. A 5 or 10 degree C rise is often more than sufficient for an analysis. If you cannot measure and the estimate is not sufficient, then one needs to perform a detail thermal analysis.