2 - Plating

Abstract

Various physical properties of a plated film are derived from its microstructure. In Chapter 1, Heat generation during electrochemical reactions, the structure of the plated film was discussed electrochemically, assuming that it changes depending on the composition of the plating bath and various plating conditions. However, the author studied in detail the plating conditions of 15 types of pure metals, 51 types of binary alloys, 16 types of electroless plating, and the structure of the obtained plated film. As a result, I found that the microstructure of the plated film is almost uniquely determined by the film composition (ratio of types of elements and their amounts) formed regardless of the plating conditions. This means that the microstructure of the plated film is closely related to the metal phase diagram. However, as explained in Chapter 1, Heat generation during electrochemical reactions, the plating reaction is an exothermic reaction and the high-temperature film structure is rapidly cooled. For this reason, the plated film is often amorphous or has a metastable structure. Various plating conditions should be devised to change the composition of the resulting plated film. The adhesion of the plated film can be determined in the form of a phase diagram of the binary alloy. That is, it has been found that the adhesion of the plated film is determined by the combination of the substrate metal and the plated metal. That is, the adhesion of the plated film can be judged by a shape of a binary alloy phase diagram. Furthermore this chapter also describes the mechanism of hydrogen incorporation mechanism into the plated film and its behavior in the film.