A method for the production of cover layers for the partially electroplating of electrically conductive, if nsta ends or for cathodes in the case of electrochemical polishing - and treatment processes

摘要

A method of electrodepositing a metal on a selected part of a conductive surface, comprises cathodically depositing on the surface a resist of an amphoteric metal oxide (such as an oxide of V, Mo, W, U, Re, Ru, Mn, or Nb), and thereafter electrodepositing the metal on a part of the surface not bearing the resist. The oxide, e.g. less than 0.01 micron thick, is deposited from solutions containing salts of metals (having amphoteric oxides) with acid or from solutions containing salts of the acid oxides of metals (having amphoteric oxides) with alkali metals, alkaline earth metals or ammonium. The electrolyte may contain additions to improve its conductivity and stability. The surface may be coated with oxide only on defined portions, e.g. by using a resist layer of a substance which is dissolved after electrodepositing the oxide and prior to electrodepositing the metal. Alternatively, the surface may be wholly coated with oxide and the oxide then removed from certain portions, e.g. mechanically, chemically or electrolytically. After electrodeposition of the metal, the oxide resist may be removed. A further electrolytic metal deposit may be applied to the whole surface, the result being a grooved surface with the grooves in the location of the original oxide pattern. According to another possibility, the electrodeposited metal may be etch resistant and after removal of the oxide resist, the uncoated parts of the surface may be etched. The oxide coating resists may be used in making printed circuits or half-tone printing blocks. Examples of electrolytes, current conditions and times for coating with oxide are as follows: Example I: hydrated MnSO4, (NH4)2SO4, citric acid, sodium perborate 6-8 volts, 30-60 A/dm.2, 20-30 secs. The oxide layer prevents deposition of Cr. Example II: uranyl acetate, K2CO3, 5-7 volts, 20-50 A/dm.2, 15-20 secs. The layer prevents deposition of Ni and Cr from acid baths. Example III: sodium molybdate, sodium tungstate, formic acid to make pH of 6, 5-7 volts, 20-50 A/dm.2, 15-20 secs. The layer prevents deposition of Au or Rh.