Preparation of salt-based colloid palladium of high concentration

A kind of salt-based colloid palladium of high concentration was prepared, with concentration up to 3.6 g/L on amount of PdCl2. The optimal preparation conditions of the salt-based colloid palladium were that the PdCl2 and NaCl concentrations were respectively 3.6 g/L and 175 g/L, mole ratio of Sn to Pd was 50∶1, reaction temperature was 2035 ℃, with urea, ascorbic acid and vanillin added in a proper amount. The test results of optimal condition show that the time of starting hydrogen-deposition is 9 s, the time of completely coating copper on a test substrate is 2 min, the stability time of colloid palladium is 98 h after it is diluted into 0.1 g/L（on amount of PdCl2） when the solution temperature is 20 ℃, the backlight lever of electroless copper plating layer is 10th grade of 10-grade system, the adhesion force of the copper layer is up to GB5270—85 of China, and the average particle size of the colloid palladium is 81 nm measured by Master Sizer.