[075] Power Supply Failure Survey – Part II Capacitors

Survey results on the causes of power supply failures due to capacitors.

Introduction

In this second article about power supply failures, the capacitors are examined for their contribution to the failure rate. The causes of failure for different types of capacitors are discussed.

Power Supply Failure Survey

The LinkedIn site “POWER SUPPLY DESIGN CENTER” [1] is a valuable source of design information with over 3000 members contibuting to discussions. In the last part of this article, the question was asked of group members “Why do power supplies fail?”, and the results of the survey are repeated in Figure 1 below.

Figure 1: Survey Results for the Cause of Power Supply Failures

(Please note that in the last part of this article the data was not reported correctly. The statistics for capacitor and magnetics failure were inadvertently interchanged.)

From Figure 1, the semiconductors were seen by the survey group as the main cause of failures, and this was discussed in the last article of this series. Second on the list is capacitors. In this article, we will look at the issues that cause capacitor failures.