GB1135099A - Electroplating - Google Patents

Abstract

1,135,099. Electro-plating using an ultrasonically agitated bath. LITTON INDUSTRIES Inc. July 21, 1966 [July 21, 1965], No.32933/66. Heading C7B. A deposit of metal (e.g. Au) is electro-plated from an aqueous solution of at least one soluble salt of the metal (e.g. an alkali gold double cyanide) and with an ultrasonic field applied to the solution, the concentration of the metal salt, or salts, in the presence of the field exceeding the saturation concentration level of the solution with no applied ultrasonic field. The solution temperature may be elevated above room temperature and may be increased to boiling. Current densities up to 1,000 amps/sq.ft. may be used. Bright Au plate in excess of 0À01 inches may be obtained. Fig. 1 shows anultrasonic transducer 12 which agitates a plating solution 18 by first exciting another liquid 183, e.g. water. The ultrasonic frequency may be 20 kc/sec. and the intensity be 2À5 to 10 watts/sq.in. The cathode 20 may be moved slightly during plating by an agitator 26. The plating solution may contain 5 to 9 troy ounces of Au as KAu (CN) 2 per U. S. gallon. It may be at 150‹ F. and have a pH between 8À0 and 14À0. Possible additives to the solution are KCN or NaCN, K 2 CO 3 , potassium sodium tartrate and a wetting agent such as pentadecafluoro-octanoic acid or sodium lauryl sulphonate. Examples of electro-forming Au are: - A) Electro-plating Au on to Cu or Al then physically withdrawing the Cu or Al. B) Depositing Cu over plaster, electroplating Au on to the Cu, dissolving out the plaster with water and the Cu with acid. C) Electroplating Au on to a basis metal then machining off the Au where it is not desired. Cu, Ni or Ag and other conventional strike coatings may be used as a basis metal for the Au, e.g. zincated Al may be covered with a Cu strike before the Au is electro-plated.