An electrically excited acoustic emission test technique for screening multilayer ceramic capacitors

An AC-voltage-induced acoustic emission test technique for screening physical flaws, particularly delaminations, in various Z5U and X7R/BX ceramic capacitors was extensively evaluated. The test results showed that the severity of delaminations strongly coincided with the corresponding degree of severity in the acoustic signal. This had led to a more-than-ten-times higher rejection rate against the ceramic capacitors with delaminations in most of the screening tests. The source of the acoustic wave was attributed to the partial discharge in delaminations, cracks, and pores due to the field intensification by the high-K dielectric materials. Almost identical patterns of behavior were found between acoustic emission and partial discharge with respect to the application of voltage and the change of dielectric material.<>