Study On Preparation Of Silver Plating Copper Powder By Electronic Paste

The Cu-Ag-Flake is a kind of copper powder coated by a complete and uniform silver layer. This kind of compound powder can maintain the advantage of silver powder with its excellent electric conductivity and oxidation resistance, while on the other hand overcome the drawbacks of silver ion such as high migration rate and high cost. The Cu-Ag-Flake prepared by chemical deposition has such merits as its simple production procedure and convenient operation. Moreover, coatings by this method have impressive uniformity and integrity in addition to their chemical and mechanical properties and fine appearance.This paper briefly introduces conductive paste and conductive paste packing, and then elaborates the techniques in the Cu-Ag-Flake production and the current status of related research. In this research, copper flakes are used as raw material. The Cu-Ag-Flake produced with ammonia and complexing agent A based complexing agent can achieve fine appearance and excellent electric conductivity comparable to pure silver powder.The research starts from an investigation of different complexing agents. The appearance, granularity (D50) and surface electric conductivity are major criterion for the resulting copper powder. Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) are also used to determine the effects of different complexing agents. The optimal complexing agent is found to be a mixture of ammonia and complexing agent A. The proper dosage and application procedure are determined afterwards. In the conclusion, a hypothesis is proposed according to the spatial structures and stability constants of copper ammonium ion and copper complexing agent A ion, that the formation of copper ammonium ion is suppressed by the complexing between copper ion and complexing agent A. This theory is supported by proceeding/further experiments.In the summary, further analysis and studies are discussed in the choice and dosage of reducing agent, dosage of AgNO3, choice and dosage of surfactant, reaction temperature, mixing of solution A and solution B, mixing time, stirring intensity and curing process of conductive coating. The appearance, granularity (D50) and surface electric conductivity are evaluated with regard to the above factors. The final and optimum recipe of the coating solution and the operation procedure are given at the end.