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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: Glen Hanington (ghanington@littlefeet-inc.com )
Organization:Littlefeet, Inc.
Date posted: Tue Jan 23 11:51:42 US/Eastern 2001
Subject: Solder Connection Reliability
Message:
Does anyone have information regarding the reliability of component to board solder connections in the following application? We are using ceramic cavity filters in our product, some of which may be up to 2.5" long. As these are soldered into a G-10 printed circuit board there is some concern regarding the expected reliability of the solder connections. Our product will be mounted in an outside, non-weatherprotected environment, in a variety of locations around the world, and possibly experience a range of temperature extremes between -30degC to +50degC in normal use.


Reply:

Subject: Reliabiity Solder Connection
Reply Posted by: Bruce Dudley (bdudley@alionscience.com )
Organization: Reliability Analysis Center
Date Posted: Thu Jan 25 10:24:26 US/Eastern 2001
Message:
With all material connections, the Coefficient of Thermal Expansion (CTE)is a significant factor for mechanical fatigue failure. The proposed materials, G-10 and ceramic, have significantly different CTE factors. G-10 has an average CTE of 16 ppm/degree C and ceramic has an average CTE of 6 ppm/degree C. With this mismatch and a large delta temperature cycle of 80 degrees C, the life expectancy due to thermal fatigue cycling would be reduced by at least ten to one over a good match. Equations for determining fatigue life cycles for solder connections are included in RL-TR-92-197 "Reliability Assessment of Critical Electronic Components" and RL-TR-93-6 "Reliabiity Analysis of Surface Mount Technology".


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