Power supply failure survey--Part II

Focus:

This article series reporting on the results of the author's LinkedIn survey of why power supplies fail continues with a focus on failures attributed to capacitors, which were found to be the second most popular cause of power supply failure. After some brief comments on the greater number of failure mechanisms for capacitors versus semiconductors, the article discusses (and ranks in terms of importance) thermal stress, long-term aging, voltage stress, mechanical stress, and counterfeiting and other sources of capacitor failures. Then, capacitor failures are ranked by capacitor type (electrolytic, tantalum, multilayer ceramic (MLC), and others) with discussion of the failure mechanisms for each type. There is also some discussion on how to derate tantalums and cautions about the need to obtain rugged tantalum components and about datasheet limitations. Similarly there are cautions about staying within ratings for MLCs and the need to limit mechanical stress on their larger packages.

What you’ll learn:

• How to understand the causes of capacitor failures in power supplies
• How to prevent capacitor failures in power supplies

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Author & Publication:

Dr. Ray Ridley, President, Ridley Engineering, Power Systems Design, Apr 30 2014

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