Early Failure Processes Identified for Capacitors in Medical Devices

MML presented technical results culminating a 3.5 year effort as part of the International Electronics Manufacturing Initiative (iNEMI) Medical Reliability for Multilayer Chip Type Ceramic Capacitors (MLCC) working group assessing the relative importance of a variety of parameters for driving MLCCs to early failure. The presentations were given in a closed webinar accessible to the entire iNEMI membership March 22, 2010 and, subsequently, to the public in a presentation at the IPC APEX EXPO™ 2010 Conference and Exhibition. Analysis of the data resulted in five capacitor degradation processes being observed, two of which would result in capacitor failure; the remaining three behaviors appeared to be related to dipole motion in the ferroelectric-based dielectric. One of the two processes that lead to capacitor failure was identified as the very early failure processes that result in increased leakage current and eventual capacitor shorting. Temperature was identified as the dominant parameter that led to this degradation process. The final observation was that a small fraction of the capacitors experienced catastrophic degradation independent of any of the test parameters. In these cases, the capacitor exhibited extensive degradation early in the test process: between t = 0 h and t = 50 h. The source of these failures is currently thought to be capacitor damage resulting from a combination of capacitor and package processing treatments.