Ceramic Capacitor - Construction and Styles - Multi-layer Ceramic Capacitors (MLCC Chips) - NME and BME Metallization

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NME and BME Metallization

  • Influence of the metallization on the voltage dependence of X7R ceramic multilayer chip capacitors
  • Structure of the electrodes and the NME respectively BME metallization of the terminals of MLCC cchips

  • Influence of the NME respectively BME metallization for class 2 X7R MLCC chips on the voltage dependence of capacitance.

A particular problem in the production of multilayer ceramic chip capacitors at the end of the 1990s was a strong price increase of the metals used for the metallization of the electrodes and the terminals. Initially used, with regard to the high sintering temperatures of 1200 to 1400 °C, were the non-oxidizable noble metals silver and palladium. Both metals are expensive and greatly affect the price of the ceramic capacitors. This material composition is called "NME" (Noble Metal Electrode) metallization and lends very good electrical properties to ceramic capacitors, class 2 ones, too. But it drives, however, the cost per component upwards. These cost pressures led to the development of BME (Base Metal Electrode) metallization for the electrodes and the terminals using the much cheaper materials nickel and copper.

But with BME metallization, the electrical properties of ceramic capacitors were changed; for example, the voltage dependence of the class 2 ceramic capacitors X7R increased significantly (see picture). Even the loss factor and the impedance behavior of class 2 ceramic capacitors have been deteriorated by the BME metallization.

In class 2 ceramic capacitors, because of their use in applications where it is usually not very important for the stability of the electrical properties, these negative changes, for cost reasons, were finally accepted by the market, while the NME metallization was maintained in the class 1 ceramic capacitors.

Read more about this topic:  Ceramic Capacitor, Construction and Styles, Multi-layer Ceramic Capacitors (MLCC Chips)