What is the function and activation mechanism of electroless nickel plating additives?

The temperature of electroless nickel plating is high. Reducing the temperature of the plating solution can not only improve the stability of the plating solution, reduce the production cost, but also reduce the volatilization of the plating solution, so as to save energy and protect the environment. , the most promising solution is to choose appropriate complexing agents and additives. The amount of additives is small, which has a significant impact on the deposition rate and coating performance, but the research on the mechanism of the additives is not deep enough. At the same time, because the activation step is related to the chemical Whether the plating occurs or not, the speed of deposition, the quality of the coating, etc., exploring the mechanism of the activation process, and developing new activation methods have also become the key to the innovation of electroless plating technology.

The effect of additives on the electroless deposition rate and morphology was explored. The composition of the bath and the effect of additives in the electroless Ni-P and Ni-WP systems were explored. The increase of pH value can accelerate the chemical deposition rate, and the increase of Ni2 concentration and pH value is beneficial to the increase of Ni deposition amount, while NaH2PO2 obviously promotes the increase of P deposition amount.

Additives mainly work through surface effects. For example, propionic acid promotes chemical deposition by forming surface complexes with Ni2 and NaH2PO2. Propionic acid and NaH2PO2 form intermolecular hydrogen bonds, which promote the breaking of PH bonds and generate ?PHO2-intermediate Propionic acid added with "-OCO-" functional group to Ni2 to form a bridge complex, thereby accelerating the deposition of Ni.