Large Capacitance Multilayer Ceramic Capacitor

Large capacitance multilayer ceramic capacitors were made using a ceramic dieletric in the binary system Pb(Fe2/3Wl/3)O3-Pb(Fel/2Nbl/2)O3. The new capacitors used silver alloy as an internal electrode, reducing the capacitor cost significantly. It was then possible to make economical 10 µF ~ 400 µF muitilayer ceramic capacitors. Typical electrical properties of the new capacitors are listed below: Size 4.5 cm³Capacitance at 20° C, 1 kHz 400 µF Dissipation factor at 1 V rms, 1 kHz 0.6 percent Insulation resistance 5000 -F Capacitance change with temperature change (-30° C ~ +85° C) -83 to 0 percent Impedance at 100 kHz 2m 2 Equivalent series resistance at 100 kHz 0.8 m Maximum permissible ripple current 20 A. The new multilayer ceramic capacitors exhibit the following benefits in comparison with conventional multilayer ceramic capacitors, tantalum electrolytic capacitors, and aluminum electrolytic capacitors. a) Dimensions are small and capacitance is large; b) impedance at high frequency band is small; c) equivalent series resistance is small; d) maximum permissible ripple current is large. The new multilayer ceramic capacitors are useful in various electronic circuits, particularly in switching regulators, in place of tantalum electrolytic capacitors and aluminum electrolytic capacitors.