MLCC (Multilayer Ceramic Capacitor) is SMD (Surface Mounted Device) type capacitor that is used in wide ranges of capacitance. MLCC is paid more attentions than other capacitors due to the better frequency characteristics, higher reliability, higher withstanding voltage and so on.
MLCC is made of many layers of ceramic and inner electrodes like sandwich. Pd was used for inner electrodes. But the price of Pd was skyrocketed and Pd was replaced by the BME (Base Metal Electrode), which reduced the total cost of MLCC.
This inner electrode is connected to outer termination for surface mounting, which is composed of three layers, Cu or Ag layer, Ni plating layer, and SnPb or Sn plating layer. Most of MLCCs become Pb free by the environmental issue at present.
MLCC is divided into two classes. Class I (C0G, etc) is the temperature compensating type. It has a small TCC (Temperature Coefficient of Capacitance) and a better frequency performance.
Therefore, it is used in RF applications such as cellular phone, tuner, and so on. Class II (X7R, X5R, Y5V, etc) is the high dielectric constant type, which is used in general electronic circuit.
Especially high capacitance MLCC is replacing other capacitors (Tantalum and Aluminum capacitor) due to the low ESR (Equivalent Series Resistance) value.