Insulation resistance degradation mechanisms of multilayer ceramic capacitors during highly accelerated temperature and humidity stress tests

Abstract

The failure mechanisms of multilayer ceramic capacitors (MLCCs) with Ni internal electrodes under high temperature and high voltage conditions have been investigated through highly accelerated life tests (HALTs) in recent years. Generally, insulation resistance degradation during HALTs is presumed to be because of the electromigration of oxygen vacancies. Reliability in high-temperature, high-humidity, and rated-voltage environments is important for MLCCs. However, only a few studies have investigated the causes of insulation resistance degradation in MLCCs in these environments. We investigated the failure mechanisms of MLCCs through a highly accelerated temperature and humidity stress test. On the basis of presence of a degraded area on the anode side, we presumed that hydrogen ions were produced by H 2 O electrolysis at the interface between the ceramics and internal electrodes on the anode side, and that these hydrogen ions caused insulation resistance degradation.

Hydrogen migration in BaTiO3-based dielectrics under high humidity and electric field bias

“…Consequently, the leakage current increases as the protons diffuse into the dielectric. 23) It was verified that water vapor infiltrates the MLCC 24) using deuterium, as a tracer. It was observed, that deuterium was biased toward the cathode-side inner electrode in the BaTiO 3 -based dielectric exhibiting increased leakage current.…”

“…In previous studies, it was presumed that when water vapor infiltrated the interface between the anode-side inner electrode and the dielectric, electrolysis occurred at the interface, as shown in the equation below, and D + was attracted to the cathode-side inner electrode by migration through the dielectric. [23][24][25] Considering the results of Fig. 3(a) and the aforementioned presumption, the deuterium in the dielectric is presumed to exist as D +…”

“…From the results of previous studies, [23][24][25] it was presumed that protons migrate because they are attracted from the anode side to the cathode side. In this study, secondary ion mass spectrometry (SIMS), which can analyze deuterium with a high degree of sensitivity, was used to understand deuterium migration due to the electric field and temperature.…”

Infiltration of water vapor into multi-layer ceramic capacitors under highly accelerated temperature and humidity stress tests

“…[22][23][24][25][26][27][28] Recently, Saito et al reported the failure mechanisms of MLCCs during HASTs. 29) It is presumed that infiltration of water vapor into MLCCs generates hydrogen ions via electrolysis of H 2 O at the interface of the ceramics and the internal electrodes on the anode side; thereafter, these hydrogen ions, which diffuse to the dielectrics, cause an increase in the leakage current. 29) However, this does not show that the increase in the leakage current of MLCCs is directly linked to water vapor infiltration; thus, in this study, to verify this idea, we investigated whether the water vapor that infiltrated the MLCCs caused an increase in the leakage current.…”

“…These MLCCs had a chip size of 3.2 mm × 1.6 mm × 1.6 mm, a capacitance of 10 μF, a rated voltage of 16 V, a dielectric layer thickness of 3 μm, a Ni internal electrode layer with a thickness of 1 μm and 340 dielectric layers. Based on previous studies, 29) the thickness of the external electrode of these MLCCs was one-quarter of the conventional MLCC thickness; this facilitates the infiltration of water vapor into the MLCCs. The MLCCs were used as test chips.…”