Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/56—Electroplating: Baths therefor from solutions of alloys
  • C25D3/60—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of tin
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/56—Electroplating: Baths therefor from solutions of alloys
  • C25D3/58—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of copper

Definitions

• the invention relates to alkaline cyanide baths for the electrodeposition of bright to shiny, leveled copper-tin alloy coatings, the 1 to 60 g / l copper in the form of copper (I) cyanide, 1 to 50 g / l tin in the form of alkali tannate , 0 to 10 g / l zinc in the form of zinc cyanide, 0.1 to 200 g / l of one or more complexing agents, 1 to 100 g / l free alkali metal cyanide, 1 to 50 g / l free alkali metal hydroxide, 0 to 50 g / l Contain alkali carbonate, 0.01 to 5 g / l brightener and 0 to 100 mg / l lead as lead (II) acetate or lead (II) sulfonate.
• the former are therefore used in decorative electroplating to replace, for example, silver, nickel, chromium or aluminum. Because of their very good soldering properties, their abrasion resistance, their corrosion resistance and their low electrical contact resistance, copper-tin coatings are also used increasingly in technical fields.
• the latter are mainly used in decorative electroplating as a replacement for brass and as an underlayer before electroplating. Copper-tin alloy layers do not cause any known allergies on human skin.
• Copper-tin alloys are mainly deposited from alkaline, cyanide-containing electrolytes that contain copper as copper (I) cyanide and tin as sodium stannate.
• Other electrolytes contain phosphate and / or polyphosphate as complexing agents and also colloids, such as polypeptides as gloss additives (DE-PS 860 300).
• These well-known baths must be operated at high, constant temperatures (65 o C and higher) in order to obtain uniform layers of constant composition. Working with these baths is therefore difficult and cumbersome.
• the copper-tin baths can also contain zinc salts, which means that a few percent of zinc is also separated.
• Copper-tin alloy baths have recently become known (DE-PS 33 39 541) which, in addition to copper cyanide, alkali tannate, phosphates, free alkali metal cyanide and free alkali metal hydroxide as complexing agents, also include organic substances in the form of fatty acid-imido-alkyl-dialkylamine oxides, fatty acid -amido-alkyl-dialkylamine-betaine and / or ethoxylated naphthols and as brighteners contain polyethylenediamines, benzaldehydes, ethynols and / or benzylpyridine carboxylates. These baths also require monitoring of the free cyanide and hydroxide content.
• Oligosaccharides based on pentose and hexose have proven particularly useful.
• the baths preferably contain 50 to 150 g / l of these oligosaccharides.
• Baths of this composition are not very sensitive to fluctuations in the hydroxide and cyanide content.
• the coatings deposited from such baths are shiny and shiny.
• the current density range of 1 to 3 A / dm2 that can be used to achieve uniform layers is relatively small.
• the baths preferably contain 0.5 to 1.5 g / l of this gloss agent.
• group a) e.g. Allylsufonate, vinyl sulfonate, from group b) propyne sulfonate and butyne sulfonate, from group c) 1- (3-sulfopropyl) -2-vinyl-pyridinium betaine, 4-methyl-1- (3-sulfopropyl) pyridinium betaine, 4-Benzyl-1- (3-sulfopropyl) pyridinium betaine, and from group d) S-isothiuronium-3-propanesulfonate, o-ethyl-dithiocarbonic acid (3-sulfopropyl) -ester potassium salt.
• the baths are less dependent on fluctuations in the bath components.
• the coatings do not trigger any known allergies and can therefore also replace nickel coatings.
• the baths according to the invention can be operated with insoluble anodes, e.g. with graphite anodes.
• the operating temperatures are 40 to 62 o C, the current densities between 0.1 and 5.0 A / dm2 and the pH values between 11 and 13.
• Baths containing 5 to 25 g / l copper in the form of copper (I) cyanide have proven successful. 5 to 40 g / l tin in the form of sodium stannate, 50-150 g / l complexing agent, 20 to 60 g / l free alkali metal cyanide, 2 to 40 g / l free alkali metal hydroxide, 0.2 to 1.5 g / l brightener and possibly contain 1 to 100 mg / l lead as lead (II) acetate.
• the copper-tin baths can additionally contain known complexing agents, such as phosphates, hydroxycarboxylic acids, aminocarboxylic acids or polyoxycarboxylic acids.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electroplating And Plating Baths Therefor (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=6493699

Family Applications (1)

Country Status (5)

Cited By (8)

Families Citing this family (7)

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• 1993
  • 1993-07-26 DE DE4324995A patent/DE4324995C2/de not_active Expired - Fee Related
• 1994
  • 1994-06-17 EP EP94109336A patent/EP0636713A3/fr not_active Withdrawn
  • 1994-07-20 US US08/277,631 patent/US5534129A/en not_active Expired - Lifetime
  • 1994-07-25 BR BR9402931A patent/BR9402931A/pt not_active IP Right Cessation
  • 1994-07-26 JP JP17424894A patent/JP3305504B2/ja not_active Expired - Fee Related

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