| 摘要 |
PURPOSE:To form a plating layer having excellent adhesion and uniformity in the stage of performing a plating treatment in an electroless solder plating liquid consisting of tin borofluoride, lead borofluoride, thiourea and a reducing agent by dividing the operation to >=2 stages and increasing successively the concn. of the metallic components in the plating liquid to be used. CONSTITUTION:A plating operation for solder plating on the surface of a material to be treated by using an electroless solder plating liquid is accomplished by dividing the operation to at least two stages. More specifically, the electroless solder plating liquid contg. tin borofluoride, lead borofluoride, thiourea and a reducing agent of metallic salt ion and a surface active agent according to need is used as the electroless solder plating liquid and the concn. of the metallic components of said Sn and Pb is made 1/2-1/10 of the concn. of the metallic components in the liquid to be used in the final plating. The grain of the deposited solder plating layer is fine and the Sn-Pb solder plating layer having adhesion and uniformity over the entire part of the material to be treated is obtd. |
