Characterization of Silver Interdiffusion into (Zn,Mg)TiO3+x:Bi:Sb Multilayer Ceramic Capacitor

Abstract

In this study, (Zn,Mg)TiO3+x+Bi2O3+Sb2O5 multilayer ceramic capacitors (MLCCs) with different proportions of a silver (Ag)–palladium (Pd) mixture acting as the inner electrode were sintered at 925°C for 2 h to evaluate the effect of the inner electrode on reliability. The main results reveal that the lifetime is inversely proportional to the Ag content in the Ag/Pd inner electrode. Ag diffusion into the (Zn,Mg)TiO3+x+Bi2O3+Sb2O5 MLCC during cofiring at 925°C for 2 h and Ag migration at 140°C against 200 V are both responsible for the short lifetime of the (Zn,Mg)TiO3+x+Bi2O3+Sb2O5 MLCC, particularly the latter factor. A Bi,Sb‐rich secondary phase was present at the triple junction and a small amount of Ag was detected from the second phase for a (Zn,Mg)TiO3+x+Bi2O3+Sb2O5 MLCC with a high Ag content in the inner electrode of Ag/Pd=99/01. However, this was not the case with a low Ag content in the inner electrode of Ag/Pd=90/10. This means that the Bi,Sb‐rich second phase plays an important role in determining the degradation of insulation resistance due to the excessive formation of oxygen vacancies from the reaction of Ag+ for Bi3+ or Sb5+ substitution to lower the activation energy of the (Zn,Mg)TiO3+Bi2O3+Sb2O5 dielectrics and to enhance markedly the effect of Ag migration.