TESTING PASSIVE COMPONENTS FOR FLEXURE CRACK PERFORMANCE
Authors: Daniel Skamser, Cory Riedl, Bill Sloka, John Evans, Ph.D., and Zhaozhi Li Company: KEMET Electronics Corporation and Center for Advanced Vehicle Electronics (CAVE) Auburn University Date Published: 10/11/2007
Abstract: Surface mount capacitors are used extensively in harsh automotive applications. In addition, the assembly processes for manufacturing the electronic systems can often lead to high stress on the crack-sensitive passive components. The typical mode of failure is a flex crack, which can often leads to a “short” failure. Other than a few standard tests, it can be difficult to fully mimic the same conditions seen in both the automotive application and the manufacturing process. This study describes both standard and new tests used to create stress on multilayer ceramic capacitors (MLCCs). Standard tests include modulus of rupture (MOR), flexure test, drop test, and thermal shock. Customized tests include screw torque, air thermal cycle with flex, break tab, and a connector test. Both electrical and strength performance were measured to rate performance. Failure analysis was conducted to verify crack mode behavior. Finally, some new MLCC designs were tested showing crack insensitivity to flex crack issues. The floating electrode design proved to be robust for high stress environments.