Loading patent…
AssigneePitt Metals and Chemicals, Inc.
InventorRichard E. Horn
Estimating the term…
In one specie a tin-plating bath contains an alkali metal stannate and generates an alkali metal hydroxide during the electrodeposition of tin. The tin-plating bath is circulated through the anode compartment of an electrodialytic cell that has a cation permselective membrane separating the anode compartment from the cathode compartment. The cathode compartment contains a suitable electrolyte and when a current is impressed across the electrodialytic cell, the alkali metal ions in the plating bath migrate through the permselective membrane into the cathode compartment and the stannate ions remain in the tin-plating bath in the anode compartment. The removal of the alkali metal ions from the tin-plating bath controls the alkali metal hydroxide content of the plating bath. The electrodialytic cell may be positioned in the tin plating bath and where feasible utilize the same power source as the plating bath. Where bath drag out is excessive and the amount of alkali metal hydroxide removed from the plating bath reduces the amount of treatment of the plating bath, the alkali metal stannate is recovered from the rinse water by passing the rinse water through a center compartment of a three compartment electrodialytic cell bounded by a cation and an anion or neutral permselective membrane. The stannate ions in the rinse water migrate to the anode compartment and are returned to the plating bath and the potassium ions pass to the cathode compartment. In an acid bath containing a tin fluoride complex with a fluostannite ion the excess alkali metal ions are removed from either the plating bath or the rinse water by passing the bath or rinse water through the center compartment of a three compartment electrodialytic cell that is bounded on both sides by a cationic permselective membrane. The cathode compartment contains an alkali metal hydroxide and the anode compartment contains an acid and an insoluble anode. The alkali metal ions are transferred from the center compartment to the cathode compartment thus removing the excess alkali metal ions from the bath and rinse water.
Apparatus for controlling the concentration of alkali metal ions in an electrochemical tin-plating bath while plating tin on a metallic member comprising,
Apparatus for continuously controlling the concentration of alkali metal ions in an electrochemical metal plating bath while plating a metal on a metallic member comprising,
Apparatus for continuously controlling the concentration of alkali metal ions in an electrochemical tin plating bath while plating tin on a metallic member comprising,
Dependencies are inferred from the claim text.