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US 4,053,372 AGranted
Tin-lead acidic plating bath
AssigneeAMP Incorporated
InventorThomas Francis Davis
Life of this patent
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Abstract
A method for electroplating tin-lead compositions, a bath for electroplating of tin-lead alloys and stable, solid salt compositions for make up of a bath for plating the tin-lead alloys, said bath contains, besides the two metals, thiourea, potassium, hypophosphite and hydrochloric acid with the pH of the bath being from 0.5 to 1.5.
Claims7
A method for depositing tin-lead alloys from an aqueous electrolyte solution comprising electrolyzing a solution comprising from
- ______________________________________ Sn metal (as stannous chloride) 7.5-75 g/l Pb metal (as lead chloride) 1-99% of total Sn and Pb concentration A thiourea 10-200 g/l NH.sub.4 Cl 00-300 g/l Na.sup.+, or K.sup.+ 10-200 g/l.- H.sub.2 PO.sub.2 . H.sub.2 O HCl, 36% concentrated 20-500 ml/l ______________________________________
- said solution being at a pH from 0.5 to 1.5, said bath being at a temperature from 130.degree. to 200.degree. F. and depositing said lead alloy on a cathodic work piece and recovering said work piece.
An aqueous electrolyte suitable for deposition of tin-lead alloys from said electrolyte, said aqueous electrolyte comprising
- ______________________________________ Sn metal (as stannous chloride) 7.5 - 75 g/l Pb metal (as lead chloride) 1 - 99 % of total Sn and Pb concentration A thiourea 10 - 200 g/l NH.sub.4 Cl 0 - 300 g/l Na.sup.+, NH.sub.4.sup.+ or K.sup.+ with .sup.- H.sub.2 PO.sub.2 . H.sub.2 O 10 - 200 g/l HCl (conc.) 20 - 500 ml/l ______________________________________
- wherein the pH of said solution is from 0.5 to 1.5.
Dependencies are inferred from the claim text.