Development of an electroless nickel immersion gold process for PCB final finishes

A new generation of electroless nickel immersion gold process has been developed that is targeted to solve the “Black Nickel issue”. The development involved the understanding of the details of the nanostructure of electroless nickel, the interface between Ni and Au, Ni and solder, and the control of the porosity of the Au surface. A suitable increase in phosphorous content in the nickel deposit reduces the hyperactive corrosion during immersion gold process. In addition, a stabilizer system that gives consistent performance across the entire bath life was used to improve the simplicity of bath control. This combination gives many advantages for the applications in printed wiring boards.