Abstract
This study investigates the effect of dielectric layer thickness on the electrical and reliability characteristics of BaTiO₃- based X8R multilayer ceramic capacitors (MLCCs) for automotive applications. MLCCs with 30 dielectric layers and thicknesses ranging from 5 to 30 μm were fabricated, and key parameters―including capacitance, equivalent series resistance (ESR), insulation resistance (IR), breakdown voltage (BDV), DC-bias characteristics, temperature coefficient of capacitance (TCC), and ripple current-induced heating―were evaluated. The dielectric constant (~2,000) and sintering shrinkage (~-25%) were nearly independent of thickness, confirming stable microstructure formation. ESR increased with thickness, while normalized BDV (V/μm) decreased due to defect accumulation. IR improved with increasing thickness but dropped sharply above 125℃. Dielectrics thinner than 10 μm exhibited significant capacitance degradation under DC-bias and temperature variation, reflecting strong internal field effects. Ripple-induced heating correlated directly with ESR. These results indicate that, although thinner layers enhance capacitance density, reducing the thickness below 10 μm compromises bias stability and thermal reliability. A minimum dielectric thickness of 10 μm is therefore recommended to achieve an optimal balance between electrical performance and durability in high-reliability X8R MLCCs.
