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
• • 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

Definitions

• the present invention relates to an aqueous solution for the deposition of tin-zinc alloys and in particular to an electroplating bath which enables the deposition of tin-zinc alloys from a cyanide-free tin (II) -zinc (II) solution with a simple bath control.
• Products that are electroplated with a tin-zinc alloy are characterized by excellent corrosion resistance.
• the resistance to hydraulic fluid and aqueous salt solutions make products coated in this way appear interesting for the automotive industry.
• Products coated with tin-zinc alloys are also used in the broadcasting, electrical and construction industries due to their corrosion resistance and excellent solderability.
• electroplating baths have the disadvantage that a higher energy expenditure is required for the deposition of tin (IV) ions than for the deposition of tin (II) ions.
• the bath management involves the difficulty that when the anode is dissolved, which advantageously also consists of a tin-zinc alloy, the formation of tin (IV) ions must be promoted by forming a film by means of polarization.
• the thickness and composition of the deposited tin-zinc alloy depend on the current density and thus dependent on the geometry of the substrate. The toxicity of the cyanide ions also complicates industrial use.
• an electroplating bath which allows the deposition of tin from the stage of the divalent tin, so that the required energy expenditure is reduced.
• the dependence of the speed and composition of the tin-zinc deposition on the current density was also reduced.
• the amphoteric surface-active surfactants proposed in this publication mean that the bath guidance remains critical and must be set and monitored very precisely in order to prevent dark and disturbed deposits.
• aqueous solution which, in addition to tin (II) and zinc (II) ions, contains aliphatic carboxylic acids and / or their alkali metal salts as complexing agents, and also a mixture of anionic and nonionic surfactants as grain refiners.
• the aqueous solution according to the invention further contains aromatic aldehydes and / or aromatic ketones as brighteners. Aldehydes or ketones of the following formulas (I) or (II) are preferably used:
• a special, advantageous compound of formula (II) is o-Cl-benzaldehyde.
• the pH of the solution is preferably 2-8, particularly preferably 3-5.
• tin (II) and zinc (II) ions are preferably used in the form of chlorides, sulfates or alkyl sulfonates.
• one or more conductive salts of the corresponding anions are additionally used. NH 4 C1 and / or NH (CH 3 S0 3 ) are preferred.
• Preferred aliphatic carboxylic acids in the aqueous solution according to the invention are hydrocarboxylic acids and aminocarboxylic acids and particularly preferred is citric acid or its alkali salts.
• the nonionic surfactants of the present invention preferably have the formula (III):
• Aliphatic or aromatic sulfonates are preferably used as anionic surfactants.
• one or more compounds of the formulas (VI) to (IX) are selected:
• R C 3 _ 12 alkyl
• X H, -S0 3 M
• M Na, K, NH 4 b ') R'-O- (C 2 H 4 O) ⁇ r -R'iSO 3 M (VII)
• R ' C 3 _ 12 alkyl
• R » C 2 _ 5 alkyl
• M Na, K, NH 4
• R "' H, C-L_5-alkyl. 0- (C 2 H 4 0) n -X;
• R " 1 H, C 1 _ 5 alkyl, 0- (C 2 H 4 0) n -X;
• anionic surfactants according to the following formulas (X) to (XIII)
• the electroplating bath for the deposition of zinc-tin alloys can also contain aromatic and / or heterocyclic carboxylic acids or their alkali salts according to formula (XIV)
• carboxylic acids are nicotinic acid and / or Na benzoate.
• V orteilhaft stock be selected, the concentrations of the individual components within the following ranges:
• the present invention also includes the use of the aqueous solution described above for the deposition of tin Zinc coatings, in particular tin-zinc coatings with a zinc content of 10 to 50% by weight.
• An aqueous solution was prepared from the following components:
• Nicotinic acid 0.1 g / 1 o-Cl-benzaldehyde 0.05 g / 1
• Substrate surface with a thickness of 10 microns and deposited with a light gray color.
• aqueous solution according to the invention can be used to deposit tin-zinc alloys of uniform thickness and composition with a uniform light color without the use of cyanide ions with low energy consumption.

Landscapes

• 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)
• Electrolytic Production Of Metals (AREA)
• Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)

Priority Applications (8)

Applications Claiming Priority (2)

Related Child Applications (1)

Publications (2)

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Family Applications (1)

Country Status (11)

Families Citing this family (7)

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• 1998
  • 1998-11-12 DE DE19852219A patent/DE19852219C1/de not_active Expired - Fee Related
• 1999
  • 1999-11-12 CN CNB998097950A patent/CN1195904C/zh not_active Expired - Fee Related
  • 1999-11-12 WO PCT/EP1999/008724 patent/WO2000029645A2/de not_active Ceased
  • 1999-11-12 DE DE59902696T patent/DE59902696D1/de not_active Expired - Lifetime
  • 1999-11-12 AT AT99960973T patent/ATE223979T1/de not_active IP Right Cessation
  • 1999-11-12 CZ CZ20011633A patent/CZ296310B6/cs not_active IP Right Cessation
  • 1999-11-12 PL PL99348755A patent/PL194304B1/pl not_active IP Right Cessation
  • 1999-11-12 KR KR1020017005925A patent/KR20010086017A/ko not_active Withdrawn
  • 1999-11-12 JP JP2000582620A patent/JP4355987B2/ja not_active Expired - Fee Related
  • 1999-11-12 EP EP99960973A patent/EP1137825B1/de not_active Expired - Lifetime
  • 1999-11-12 AU AU17752/00A patent/AU1775200A/en not_active Abandoned
• 2001
  • 2001-05-11 US US09/854,131 patent/US6770185B2/en not_active Expired - Fee Related

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