Prognostics of Embedded Planar Capacitors Under Temperature and Voltage Aging

Abstract

This paper presents the application of model-based and data-driven approaches for prognostics and health management (PHM) of embedded planar capacitors under elevated temperature and voltage conditions. An embedded planar capacitor is a thin laminate that serves both as a power/ground plane and as a parallel plate capacitor in a multilayered printed wiring board (PWB). These capacitors are typically used for decoupling applications and are found to reduce the required number of surface mount capacitors. The capacitor laminate used in this study consisted of an epoxy-barium titanate (BaTiO3) composite dielectric sandwiched between Cu layers. Three electrical parameters, capacitance, dissipation factor, and insulation resistance, were monitored in-situ once every hour during testing under elevated temperature and voltage aging conditions. The failure modes observed were a sharp drop in insulation resistance and a gradual decrease in capacitance. An approach to model the time-to-failure associated with these failure modes as a function of the stress level is presented in this paper. Model-based PHM can be used to predict the time-to-failure associated with a single failure mode, consisting of a drop in either insulation resistance or capacitance. However, failure of an embedded capacitor could occur due to either of these two failure modes and was not captured using a single model. A combined model for both these failure modes can be developed but there was a large variance in the time-to-failure data of failures as a result of a sharp drop in insulation resistance. Therefore a data-driven approach, which utilizes the trend and correlation between the parameters to predict remaining life, was investigated to perform PHM. The data-driven approach used in this paper is the Mahalanobis distance (MD) method that reduces a multivariate data set to a single parameter by considering correlations among the parameters. The Mahalanobis distance method was successful in predicting the failures as a result of a gradual decrease in capacitance. However, prediction of failures as a result of a drop in insulation resistance was generally challenging due to their sudden onset. An experimental approach to address such sudden failures is discussed to facilitate identifying any trends in the parameters prior to failure.

Reliability of Embedded Planar Capacitors With Epoxy–$\hbox{BaTiO}_{3}$ Composite Dielectric During Temperature–Humidity–Bias Tests

“…An increase in insulation resistance under these conditions is not expected, which means that factors other than moisture absorption are also playing a role in this behavior. The insulation resistance of this dielectric material was also found to increase during temperature and voltage aging at 125 • C and 200 V [30]. The increase in insulation resistance under high-temperature and high-humidity conditions is not investigated in this work and will be reported in a future publication.…”

Reliability and failure analysis of capacitive substrate

“…[2]. There are two possible mechanisms can be explained that the degradation in insulation resistance in BaTiO 3 dielectric materials, the one is oxygen vacancy generation and reduction in the grain boundary barrier height, the other an increase in the leakage current is due to a decrease in grain boundary barrier height as previously reported [4].…”

“…The accelerated life testing of the SMD components in reduction of insulation resistance under different temperature and voltage stress have been studied in high dielectric constant multiplayer ceramic capacitors (MLCC) [1][2] and other ceramic thin film capacitors [3], but very few investigation is done to evaluate the reliability and failure analysis of the embedded capacitors of HK capacitive substrate [4]. In this paper, we used the capacitors of the HK capacitive substrate as a discrete component, and its electrical characteristic degradation, MTTF characteristics and failure mechanisms under temperature and voltage stress have been studied and discussed systematically.…”

Temperature and voltage aging effects on electrical conduction mechanism in epoxy-BaTiO3 composite dielectric used in embedded capacitors

“…For the selection of the aging voltage, the breakdown voltage of the capacitor dielectric was measured at 125°C. The breakdown voltage was measured on 10 samples and was found to be 355.7 ± 40.1 V [26]. A voltage of 100 V was selected for aging that was well below the breakdown voltage of the dielectric.…”