Preparation and properties of nanosized PdS dispersions for electrolytic plating

Aqueous dispersions of PdS particles were prepared by the controlled double-jet precipitation technique using PdCl2 or Na-2[PdCl4] and Na2S solutions. Uniform spherical particles 20-30 nm in diameter were obtained in acidic media in the absence and in the presence of surfactants, whereas the reaction in alkaline media yielded particles with a diameter of 2-5 nm. Surfactants of the AVANEL S series enhanced the deposition of PdS particles on the epoxy circuit boards, resulting in a conductive layer, which also facilitated the electroplating by copper in holes. The electrokinetic mobilities of the chloride-containing dispersions reveal negative charges over the entire pH range, whereas chloride-free samples display isoelectric points at pH 3.0+/-0.2 or between pH 5 and 6, depending on the preparation conditions. (C) 1998 Elsevier Science B.V.