Palladium catalyst synthesis through sol-gel processing for electroless nickel deposition on glass

The method of palladium catalyst synthesis by spin-coating of silicate glass with stable isopropanol sol containing the products of controllable SnCl2 hydrolysis with subsequent treatment in PdCl2 solution has been developed. It has been shown that nanostructured Sn(II) hydroxycompounds film containing trace quantity of isopropanol was formed by sol-gel process. This film had an improved continuity and enlarged thickness, smoothed down the surface of the substrate and imparted to it high reductive ability resulting in the generation of palladium nanoparticles in the increased concentration. Mean size of palladium nuclei appeared to be about 4.9 nm against 6.4 nm and concentration gained 4500-5000 μm− 2 contrary to 1700-2300 μm− 2 as compared with the particles formed at the use of common aqueous SnCl2 solutions in the processes of palladium activation of dielectrics for electroless nickel deposition. The increase in palladium nanoparticles concentration, improvement of their arrangement and diminution of their sizes provided the rise in palladium catalyst activity. That was revealed in the growth of the rate of nickel films electroless deposition by a factor of 4-6, the improvement of these films microstructure and adhesion to the glass, the enlargement of their thickness from 0.3 to 2.5 μm. Nickel films had good adhesion to the glass and were characterized by uniform, compact and fine-grained microstructure with a majority of grains smaller than 40 nm. The developed method of palladium catalyst synthesis was applied also for electroless nickel deposition on alumina ceramics and quartz.