SN-NI ALLOY OR SN-CO ALLOY PLATING METHOD

摘要

PURPOSE:To prevent the reduction of plating efficiency due to the oxidation of bivalent Sn in an Sn-Ni alloy or Sn-Co alloy plating bath, by adding a specified reducing agent to the plating bath. CONSTITUTION:When Cu, a Cu alloy, Fe or an Fe alloy such as stainless steel is plated with an Sn-Ni alloy or an Sn-Co alloy having superior decorativeness and corrosion resistance by electroplating or chemical plating, the plating capacity of an acidic plating bath such as a fluoride bath, a borofluoride bath or a pyrophosphate bath as an Sn-Ni alloy or Sn-Co alloy plating bath is reduced because bivalent Sn in the plating bath is oxidized to quatervalent Sn which does not deposit Sn during plating. In order to inhibit the oxidation, 0.01-1g/l in total of at least one kind of reducing agent such as L-ascorbic acid, hydroquinone, pyrocatechol or hydrazine salt is added to the plating bath. The oxidation of bivalent Sn to quatervalent Sn in inhibited and the service life of the Sn alloy plating bath is prolonged.