Embedded Components

“Failure Mechanisms in Embedded Planar Capacitors during High Temperature Operating Life (HTOL) Testing”

Authors: Mohammed A. Alam, Michael H. Azarian, Michael Osterman and Michael Pecht, Ph.D.; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: High temperature operating life (HTOL) testing was performed on embedded planar capacitors (with epoxy-BaTiO3 composite dielectric) by subjecting these devices to highly accelerated temperature and voltage aging conditions. During HTOL testing, failure modes observed were a gradual decrease in capacitance and a sharp decrease in the value of insulation resistance. The sharp decrease in the value of insulation resistance after some time was expected to be governed by the avalanche breakdown (ABD) of the dielectric. The ABD failures were modeled. The effect of the area of the capacitor and dielectric thickness on the time-to-failure as a result of ABD was also investigated. A novel failure analysis technique was developed that can be used to locate the failure site of avalanche breakdown and understand the failure mechanism in this material. This technique can also be applied to some other dielectric materials. It was also observed that before ABD failures, the dielectric material started to show signs of degradation. These degradations were detectable using AC measurements (measurement of dissipation factor) but were not observed in DC measurements (measurement of insulation resistance). (IPC Apex Expo, April 2011)
Solder Joint Reliability

“Pb-free Solder Joint Reliability in a Mildly Accelerated Test Condition”

Authors: Joe Smetana, et al.; This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Abstract: Two different temperature cycling profiles were used to compare thermal fatigue reliability of Pb-free and SnPb solder joints in 16 different, high strain SMT packages. In some applications, high strain SAC components are expected to fail earlier than the equivalent SnPb versions. In this program, test results were compared for a 0°-100°C thermal cycle used often for evaluating high reliability applications to those of a comparatively mild, accelerated thermal cycle condition of 20°-80°C. A total of 6957 cycles was completed in the 0°-100°C testing, and a total of 9792 cycles was completed in the 20°-80°C thermal cycling. The results indicate that the SAC components that create a high strain in thermal cycling tend to perform worse in 0°-100°C testing than identical SnPb-soldered components. However, when the strain is reduced by testing with the reduced ∆T in the 20°-80°C cycle, the SAC thermal fatigue performance is equal to or better than that of identical SnPb-soldered components. The encouraging SAC performance in the 20°-80°C cycle tends to mitigate Pb-free reliability concerns because the lower strain test conditions are closer to actual service conditions. (IPC Apex Expo, April 2011)

This column provides abstracts from recent industry conferences and company white papers. Our goal is to provide an added opportunity for readers to keep abreast of technology and business trends.