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
  • C25D3/30—Electroplating: Baths therefor from solutions of tin
  • C25D3/32—Electroplating: Baths therefor from solutions of tin characterised by the organic bath constituents used

Definitions

• Electroplating bath for providing a bright tin deposit containing an anion, a non-ionic surfactant, tin ions and as a brightening agent, a carbonyl compound such as a heterocyclic or aromatic carbonyl compound with the carbonyl group directly attached to the ring.
• This invention relates to improvements in electroplating baths for obtaining bright tin deposits.
• Electroplating baths for the deposition of tin are well known. However, most of these baths suffer from the fact that the resultant tin deposits have a dull appearance which is unsuitable for many purposes. To brighten the tin deposits it was necessary to heat the deposit for a critical period of time and temperature.
• a principal object then of our invention is to provide an improved electroplating bath for the deposition of bright tin deposits. This and other objects of our invention will be apparent from the description that follows.
• an acid electroplating bath containing bivalent tin ions, at least one anion selected from the group consisting of sulfate, benzenesulfonate and fluoborate ions, a reducing agent, a non-ionic surfactant and as a brightening agent a carbonyl compound selected from the group consisting of aromatic andv heterocyclic ring containing aldehydes wherein the carbonyl group is directly attached to an aromatic or aromatic ring and a, ,8 olefinically unsaturated carbonyl compounds.
• the electroplating baths of our invention have the advantages of readily providing bright tin deposits even on work pieces having sharp edges or small apertures, allowing the electroplating to be carried out in a drum and permitting current densities of a factor of up to 1000.
• baths of our invention have'the decided-- advantage of being particularly stable.
• the bright tin deposits are immediately obtained.
• the tin-plated objects when removed from the bath, are coated with a thin brown-black layer which is readily removed by rinsing in a dilute alkali solution.
• the surfactant be a non-ionic surfactant as we have found that ionic surfactants do not 3,471,379 Patented Oct. 7, 1969 form a bright tin deposit over a wide range of current densities.
• both the carbonyl compound and the surfactant be employed as the surfactant alone does not provide bright tin deposits and the carbonyl compounds alone provide bright tin deposits only in a very restricted range of current densities (about 5 to 20 A./cm.
• the carbonyl compounds alone are not satisfactory for work pieces having sharp edges or plating carried out in a drum where the current density varies by a factor of or more.
• the carbonyl compounds employed must be free of ionizable substituents and substituents reducible in the bath.
• undesirable substituents are nitro, sulfonic acid, carboxylic acid, amino groups and substituted amino groups.
• the at, 3 olefinically unsaturated carbonyl compound is a compound of the formula:
• R2 R3 R4 wherein each of the symbols R R and R is a hydrogen atom, an aromatic, heterocyclic or aliphatic group or such a group wholly or partly hydrogenated, having, as the case may be, non-ionizable substituents or substituents not reducible in this medium, R is hydrogen, an alkyl group or an esterified carboxylic group or wherein the combination v I ll R13 is,.for example not in tautomeric relationship to form it. t,
• the carbonyl compounds themselves or derivatives of the carbonyl compounds which are converted by hydrolysis in the bath into the carbonyl compounds may be employed.
• brightening compounds Only small quantities of the carbonyl compounds (hereinafter called brightening compounds) are required. Thus quantities as small as about 25 mgs. per litre of bath liquid or even less are frequently sufficient. The upper limit is determined only by economic reasons and the solubility of the brightening agent.
• concentration of the non-ionic surfactant may vary considerably usually from about 0.1 g. to 10 g. per litre of bath liquid.
• non-ionic surfactants examples include Detergents and Emulsifiers 1963 Annual. John W. McCutcheon, -Inc., Morristown, New
• Example 1 An aqueous tin-plating bath of the following composition was prepared:
• An acid electroplating bath for depositing bright deposits of tin, said bath comprising an aqueous solution containing tin ions, at least one anion selected from the group consisting of sulfate, benzenesulfonate and fluoroborate ions, a reducing agent, a non-ionic surfactant and as the sole brightening agent at least about 25 mg. per liter of a carbonyl compound selected from the group consisting of A -dihydro-o-tolylaldehyde, A -dihydrobenzaldehyde, 3-formyl, 5,6-dihydro-2,6-dimethylpyrane and 2-benzalcyclohexanone.

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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 (1)

Publications (1)

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ID=19792365

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Cited By (9)

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Citations (4)

• 1965
  • 1965-02-13 NL NL6501841A patent/NL128321C/xx active
• 1966
  • 1966-01-20 US US521803A patent/US3471379A/en not_active Expired - Lifetime
  • 1966-02-10 DE DE19661496940 patent/DE1496940B2/de active Pending
  • 1966-02-10 SE SE1713/66A patent/SE309141B/xx unknown
  • 1966-02-10 GB GB5877/66A patent/GB1141283A/en not_active Expired
  • 1966-02-10 AT AT120266A patent/AT259965B/de active
  • 1966-02-11 FR FR49314A patent/FR1468083A/fr not_active Expired
  • 1966-02-11 BE BE676396D patent/BE676396A/xx unknown
  • 1966-02-11 ES ES0322902A patent/ES322902A1/es not_active Expired

Patent Citations (4)

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