Electroless plating of nickel-tungsten-phosphorus alloy for hybrid circuit packaging

摘要

The electroless plating process of nickel-tungsten-jphosphorus (Ni-W-P) alloy applied in thin film resistor making is described in the paper. Some factors, such as the bath composition, operating conditions(e.g., temperature, plating time and pH value), especially the effects of additives on the Ni-W-P thin film resistor are also discussed. It has been proved that adding a small amount of earth elements to the bath not only increased corrosion resistance of the deposit, but also improved the stability of thin film resistor. The results of heat-treatment and aging test showed that the atmosphere has obvious influences on the thin film resistor; after annealing in elevated temperature (above 250 deg C) in the air, the resistance increases rapidly, which mainly attributed to the oxidation of Ni-W-P film; and after annealing in 400 deg C under technical pure N_2 or H_2 atmosphere for 15 mins, there are no obvious changes for the resistance. The data of the aging test in 150 deg C in the air demonstrated the good resistance stability of the Ni-W-P film.