METHOD FOR PRODUCING SN-AG ALLOY PLATING SOLUTION

摘要

The present invention relates to a method for producing an Sn-Ag alloy plating solution comprising methanesulphonic tin, methanesulphonic silver, methanesulphonic, nonionic surfactant and additive. The producing method comprises the following steps: a first step of removing and refining positive ion metal impurities in methanesulphonic and nonionic surfactant using at least one refining method among the refining methods through diatomite filtering method, activated carbon method, and positive ion exchange processing method, while removing positive ion metal impurities released to equal to or below 100 ppm of Pb, Fe, Cu, Ni, Bi, P, K ion; a second step of producing methanesulphonic tin and methanesulphonic silver by melting tin and silver into methanesulphonic in which the impurities are removed through an electrolyic method; a third step of producing a composing solution by adding additives comprising methanesulphonic tin, methanesulphonic silver, methanesulphonic, nonionic surfactant, an antioxidant, and complexing agent; and a forth step of filtering the composing solution. Through these steps, the present invention can produce a plating solution of which the silver extraction content is constant and of which the plated film is even by producing the plating solution with filtered materials while removing the positive metal impurities from them. [Reference numerals] (AA) Remove cation metal impurities in methanesulphonic/nonionic surfactant;(BB) Generate methanesulphonic tin/methanesulphonic silver;(CC) Genarate a mixture by adding methanesulphonic, methanesulphonic tin, methanesulphonic silver, nonionic surfactant, and an additive;(DD) Filter a mixed liquid