Nondestructive Screening for Low Voltage Failure in Multilayer Ceramic Capacitors

Low voltage failure in multilayer ceramic capacitors is now generally accepted to be associated with an electrochemical dissolution of electrode materials in a humid environment and subsequent migration and deposition of material between electrodes of opposite polarity. This migration is particularly related to surface cracks or linked porosity. A novel screening technique for chip capacitors has been developed at Standard Telecommunication Laboratories (STL) that can detect the structural defects that are likely to give rise to low voltage failure. The technique is rapid and nondestructive, and is particularly suited to on-line production testing of chips as well as being suitable for goods inward inspection by the customer. Encapsulated capacitors can also be screened and information is then obtained concerning the quality of the encapsulation