Method for electroplating gold and electroplating baths therefor

Claim 1

AN ELECTROPLATING BATH FOR PLATING GOLD, COMPRISING: AN AQUEOUS SOLUTION OF AN ALKALI-GOLD CYANIDE; SAID GOLD BEING PRESENT IN THE RANGE OF FROM ABOUT 2 TO 36 G/L, CALCULATED AS THE METAL; FROM 0.5 TO 60 G/L OF A CHELATING AGENT SELECTED FROM THE GROUP CONSISTING OF TRANS-1, 2-DIAMINOCYCLOHEXANE TETRA ACETIC ACID, ETHYLENEDIAMINE TETRA METHYLENEPHOSPHONIC ACID, AND THE BATH SOLUBLE SALTS OF SAID ACIDS; FROM 0.5 TO 15 ML/L OF HYDRAZINC OR A BATH SOLUBLE SALT THEREOF, CALCULATED AS 64 PERCENT HYDRAZINE; AS AN AGENT FOR IMPROVING THE DISTRIBUTION AND AESTHETIC QUALITIES OF THE DEPOSIT, BETWEEN FROM ABOUT 0.4 TO 12 ; AND AS ADDITIONAL CONDUCTIVITY AND BUFFERING COMPOUNDS, ONE OR MORE ALKALI PHOSHATES, SAID COMPOUNDS BEING PRESENT IN CONCENTRATIONS APPROPRIATE IN THE PRESENCE OF THE REMAINING BATH COMPONENTS TO ADJUST THE BATH SPECIFIC GRAVITY TO A DESIRED LEVEL OF FROM ABOUT 8* TO 20* BAUME. SAID LEVEL BEING ABOVE THAT WHICH WOULD BE ACHIEVED IN THE ABSENCE OF SAID COMPOUNDS.

Claim 10

A method for electroplating of complex parts with gold, comprising: barrel plating said complex parts in an aqueous solution of an alkali-gold metal cyanide, said gold being present from about 2 to 36 g/l calculated as the metal; said bath further including as a chelating agent from 0.5 to 60 g/l of one or more compounds selected from the group consisting of trans-1, 2-diaminocyclohexane tetra acetic acid, ethylenediamine tetra methylenephosphonic acid, and the bath soluble salts of said acids, between 0.5 and 15 ml/l of hydrazine or a bath soluble salt thereof, calculated as 64 percent hydrazine; from 0.4 to 12 mg/l of trivalent arsenic ion; and as additional conductivity and buffering compounds, one or more alkali phosphate compounds in concentrations appropriate in the presence of the remaining bath components to adjust the bath specific gravity to a desired level of between 8* to 20* Baume, said level being above that which would be achieved in the absence of said compounds; and the pH of said bath being maintained between about 3.0 and 8.0 during said barrel plating operation.

Claim 11

A method for electroplating of complex parts with gold, comprising: barrel plating said complex parts in an aqueous solution of an alkali-gold metal cyanide, said gold being present from about 2 to 36 g/l calculated as the metal; said bath further including as a chelating agent from 0.5 to 60 g/l of one or more compounds selected from the group consisting of trans-1, 2-diaminocyclohexane tetra acetic acid, ethylenediamine tetra methylenephosphonic acid, and the bath soluble salts of said acids, between 0.5 and 15 ml/l of hydrazine or a bath soluble salt thereof, calculated as 64 percent hydrazine; from 0.4 to 12 mg/l of trivalent arsenic ion; and as additional conductivity and buffering compounds, one or more alkali phosphate compounds in concentrations appropriate in the presence of the remaining bath components to adjust the bath specific gravity to a desired level of between 8* to 20* Baume, said level being above that which would be achieved in the absence of said compounds; and the pH of said bath being maintained between about 3.0 and 8.0 during said barrel plating operation.