Practice of copper plating process for zinc alloy Die casting

Zinc Alloy SF-628 Cyanide-free alkaline copper plating has excellent dispersion and deep plating capabilities. It can be easily pre-plated and thick plated on a variety of substrates. The coating is beautiful and semi-bright. It is an ideal replacement process for traditional cyanide copper plating. It has been industrialized in Europe and the United States for several years and has been recognized by leading companies such as Boeing.
In China, for administrative reasons, the cyanide-free alkaline copper plating process is used to focus on the development of single electroplating, but the related process support around its large-scale production and application is limited, which limits its promotion and application. In particular, the problem of adhesion of zinc die-casting parts after cyanide-free alkaline copper plating has not been effectively solved. Through experiments and production applications, we have adopted SF-628 non-cyanide alkaline copper plating process and our company's pre-plating process for zinc alloy die-casting parts, and obtained good adhesion and accumulated beneficial effects. There is further experience in promoting the copper plating process without cyanide.
Ways to improve the binding ability of cyanide-free alkaline copper plating on zinc alloy SF-628
We know that cyanide in cyanide copper plating bath is a very strong complexing agent and a very effective descaling activator. It can largely compensate for the poor implementation of zinc alloy Die casting pretreatment. During the electroplating process, the cyanide plating solution can even penetrate very fine shrinkage holes and interparticle gaps on the substrate surface. In contrast, sf628 non-cyanide alkali copper does not contain a strong chelating agent. Therefore, the adhesion of the zinc Die casting is poor. In order to improve its cohesiveness, we believe that we should start from China's successful experience:
Improve the applicability of zinc die-casting substrate plating: including the selection of zinc-aluminum castings with qualified high-quality alloy composition, advanced die-casting process, reliable grinding and polishing technology and other workpieces with high surface compactness and smoothness, which can effectively improve zinc The bonding force of the surface coating of aluminum castings.
Efficient pre-plating activation process: Zinc alloy castings use a gentle and efficient chemical electrolytic degreasing and descaling process. Proper introduction of anodic electrolytic oil removal can greatly improve the adhesion. The anodic electrolytic oil removal method can effectively eliminate the foaming of the zinc die-cast coating caused by the hydrogen evolution of the cathodic electrolytic oil in the past. Secondly, proper anodic electrolysis oil removal has good removal ability on the surface scale and ash suspension of the part, which can greatly improve the adhesion of the copper coating on the surface of the zinc casting.

Strict process management and process control are subject to rigorous process management: SF-628 Cyanide-free alkaline copper plating bath is sensitive to impurities, and excessive accumulation of inorganic and organic impurities can easily lead to poor adhesion of the coating. Therefore, it is not negligible to reduce the amount of impurities in the operation and periodically remove impurities. In addition, the plating process parameters should be analyzed periodically and adjusted according to the optimum range.

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