| abstract |
(57) [Abstract] [Purpose] To provide a stable plating bath for forming a solder film of tin or a tin-lead alloy by an electroless plating method. [Structure] Add an antioxidant such as hydroquinone to an electroless plating bath containing divalent tin ions or divalent tin ions and lead ions, a complexing agent, a reducing agent, and a pH adjusting agent, and add nitrogen gas or the like. Ventilation with an inert gas made it possible to prevent oxidation of the plating bath. As a result, it has become possible to stably form a solder film made of tin or a tin-lead alloy by the electroless plating method and prevent deterioration of the plating bath. |