Ultra-low fire palladium-silver electrode powders for COG dielectric

Cost savings, higher performance, and miniaturization continue to be the major drivers in the manufacturing of multilayer ceramic capacitors (MLCCs). These trends impose higher demands on the metal powders used in the electrode compositions, the electrode ink compositions, and the dielectrics. Miniaturization and performance improvements require building MLCCs with more, thinner layers. Consequently, non-agglomerated, monodispersed metal powders are required. Due to recently high palladium prices, manufacturers have been investigating ways to reduce the cost of the electrode systems. On X7R based MLCCs, many have already switched from precious metal air fired parts to nitrogen fired base metal systems. Here, the high cost of the required equipment forces a major commitment of capital, increasing the risk of a base metal strategy. As an alternative, increasing the percent silver in silver-palladium electrode compositions allows for the possibility to reduce the cost of an air-fireable MLCC to the same level as a base metal system. The ability to use lower Pd concentrations approaching 100% Ag especially makes an impact on Class I (COG) parts, where precious metals are still predominantly used. As silver is the most conductive element, electrodes approaching 100% silver would be advantageous for lower ESR and for higher frequency requirements. In order to meet these new demands, this paper presents in detail a new line of AgPd alloy powders ranging from zero to 15% palladium and fully characterizes their potential in state-of-the-art electrode inks