Effect of 2,2′-dipyridyl on the plating rate, microstructure and performance of copper-coated tungsten composite powders prepared using electroless plating

Highly pure copper-coated tungsten powders were successfully prepared in fixed quantities using electroless plating, via the addition of an appropriate amount of 2,2′-dipyridyl to the plating bath. The effect of 2,2′-dipyridyl on the plating Cu rate, microstructure and performance of the coated Cu layer was studied systematically. Changing the concentration of 2,2′-dipyridyl had significant effects on the plating Cu rate, surface morphology, average grain size, purity and quantity of coated Cu. With a 2,2′-dipyridyl concentration of approximately 20-40 mg/L, the coated Cu was highly pure, with very little oxygen content (less than 0.1 wt.%). The complexation of the 2,2′-dipyridyl with cuprous ions and the absorption of the 2,2′-dipyridyl on the coated Cu surface can explain these findings. With increase in the concentration of 2,2′-dipyridyl in the plating bath, the plating Cu rate, microstructure and performance of the coated Cu layer changed steadily, indicating that the complexation and absorption of 2,2′-dipyridyl gradually approached a saturation level. High thermal performance W-Cu composite can be fabricated by using these composite powders.