CHARACTERIZATION OF SILVER-PALLADIUM SUBMICRONIC POWDERS .1. MORPHOLOGY AND THERMAL-PROPERTIES

Various properties of submicronic silver-palladium powders (70/30 and 75/25 Ag/Pd % wt/wt), recently obtained by a new process of precipitation in aqueous solution, are described. These powders are intended to be used in the multilayer ceramic capacitor industry. The morphology of the particles has been analysed through various measurements, such as SEM images, tap density, BET surface area, and the size distribution by a sedimentation technique. The powders were found to be made of spherical shaped particles of mean diameter close to 0.3 mu m with a narrow size distribution. The individual grains were agglomerated only to a small extent. After being conditioned as a paste by blending with an organic binder, screen-printed and fired, the particles sintered into a conductive layer of low resistivity (15-30 mu W cm for 2 mu m thickness) with only a few remaining voids, as observed by SEM. Thermal measurements indicated no melting of a pure silver phase at 960 degrees C, thus indicating that alloying was achieved before this temperature.