Study On Brighteners And Process Of Silver Plating Used In Electronic Plating

Silver has excellent electrical conductivity,thermal conductivity and solderability,thus,silver plate is widely used in electronics industry.Cyanide silver plating,as a type of conventional silver plating method having a long history,has the advantage of stable bath,simple and reliable process,high quality plate and so on.At the present time,cyanide silver plating still plays a dominant role in the silver plating market.The achieving of ideal quality plate depends on the brighteners and the technological conditions.Thus,the study is focused on the research of additives and optimization of technological parameters.Silver-plating brighteners has been monopolized by well-known foreign company all the time.In this paper,based on the cyanide silver plating system,the brighteners and technological parameters were systematically researched,aiming to obtain a brighteners system and its technology specification replacing the silver-plating product from well-known foreign company.Brighteners were summarized and classified,many types of primary brighteners and carrier brighteners were chose.The chosen primary brighteners comprise metal brighteners,inorganic brighteners and organic brighteners,and the chosen auxiliary brighteners comprise anionic surfactant containing sulfonic group and nonionic surfactant containing hydroxyl group.The chosen S series compounds which contain tautomerism between-C = S and-C-SH were synthesized and purified,and then characterized by Fourier transform infrared spectroscopy(FTIR)and thin layer chromatography(TLC).The effect of chosen primary and carrier brighteners was tested through Hull Cell experiment,and the best appearance of the plate was obtained by achieving the optimum addition and the best combination of each kind of primary brighteners.The stability of silver-plating system was also studied via rack plating experiment with small tank.Combined Hull Cell experiment,rack plating experiment and study on cathodic polarization behavior,the technological parameters were regulated and standardized.Finally,the system of S-1 and S-3 were picked out,their process specifications were also formulated.The results showed that the S-1 system and S-3 system maintained good stability,which could meet the production requirements.Plate obtained from these two system under the current density of 0?5A/dm2 were uniform and bright.The plate obtained from S-1 system was shinning,while the plate obtained from S-3 system was pale and tender.Both of the plate exhibited low contact resistance and excellent solderability,achieving the properties level of silver plate product from well-known foreign company.Thus,it is suitable for the plating of electronic products.