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US20130334056A1 - Coating technology - Google Patents

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Publication number
US20130334056A1
US20130334056A1 US13/979,448 US201213979448A US2013334056A1 US 20130334056 A1 US20130334056 A1 US 20130334056A1 US 201213979448 A US201213979448 A US 201213979448A US 2013334056 A1 US2013334056 A1 US 2013334056A1
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Prior art keywords
unsubstituted
group
alkyl
platinum
substituted
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English (en)
Inventor
Laura Ashfield
Allan Rein Berzins
Alan Boardman
Stephen Geoffrey Warren
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Johnson Matthey PLC
JOHNSON NATTHEY PLC
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JOHNSON NATTHEY PLC
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Priority to US13/979,448 priority Critical patent/US20130334056A1/en
Assigned to JOHNSON MATTHEY PUBLIC LIMITED COMPANY reassignment JOHNSON MATTHEY PUBLIC LIMITED COMPANY ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BERZINS, Allan Rein, ASHFIELD, Laura, BOARDMAN, ALAN, WARREN, STEPHEN GEOFFREY
Publication of US20130334056A1 publication Critical patent/US20130334056A1/en
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    • 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
    • C25D3/50—Electroplating: Baths therefor from solutions of platinum group metals
    • 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
    • C25D3/50—Electroplating: Baths therefor from solutions of platinum group metals
    • C25D3/52—Electroplating: Baths therefor from solutions of platinum group metals characterised by the organic bath constituents used
    • 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
    • C25D3/567—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of platinum group metals

Definitions

  • the present invention concerns improvements in coating technology, more particularly it concerns improvements in the deposition of coatings of platinum by electroplating. Even more particularly, the present invention concerns improvements in the deposition of coatings of platinum by electroplating in a commercial or industrial process.
  • Electroplating is a well-known technique for applying coatings of platinum and other platinum group metals onto conductive substrates.
  • substrates for plating according to the present invention are conductive metals or graphite, composites incorporating conductive fibres or particles may be considered as well as plastics which have a keying metal deposit or flash coating.
  • the coatings may be a thin “flash” coating used for jewellery, or several microns in thickness, generally up to about 20 ⁇ m, depending upon the intended use of the coated product; the coating may be thicker for certain applications.
  • P salt is an ammoniacal solution of diammine dinitroplatinum(II), i.e. (NH 3 ) 2 Pt(NO 2 ) 2 .
  • Q Salt® is an ammoniacal solution of tetraammineplatinum(II) hydrogen orthophosphate.
  • EP0358375A has been very successfully used in industry. Plating is carried out at temperatures of 90° C. or above. At such temperatures, water vapour and ammonia are driven off, with the consequential need to regularly replenish these components during plating in order to maintain plating rate. Additionally, the platinum salt needs to be replenished with use of the bath. There have been attempts to find alternatives to ammonia but there remains a need to find plating baths which are more environmentally friendly in reducing or eliminating the loss of toxic ammonia, and desirably which are less energy intensive and/or which offer other advantages, such as having a good plating rate, good coating properties and compatible with plating additives that improve coating properties.
  • the present invention relates to a platinum plating bath.
  • the bath may be used successfully over extended periods and the platinum component may be replenished easily.
  • the bath provides a safe, neutral, non-corrosive bath.
  • the baths yield a bright and shiny plate.
  • the baths may be used under relatively energy-efficient conditions.
  • the baths have a good plating rate providing a good deposition of platinum in a reasonable period of time.
  • the baths may be used without the emission of ammonia or with only low emissions.
  • the present invention provides an aqueous platinum electroplating bath comprising:
  • the invention provides the use of the aqueous platinum electroplating bath of the present invention for plating platinum or a platinum alloy onto a substrate.
  • the invention provides a platinum salt which is tetraammineplatinum(II) dihydrogen pyrophosphate, di[tetraammineplatinum(II)]pyrophosphate or Na 2 [Pt(NH 3 ) 4 ][H 2 P 2 O 7 ].
  • —OH is attached through the oxygen atom.
  • Alkyl refers to a straight-chain or branched saturated hydrocarbon group.
  • the alkyl group may have from 1 to 10 carbon atoms, in certain embodiments from 1 to 8 carbon atoms, in certain embodiments from 1 to 6 carbon atoms.
  • the alkyl group may be substituted or unsubstituted. Unless otherwise specified, the alkyl group may be attached at any suitable carbon atom and, if substituted, may be substituted at any suitable carbon atom.
  • Typical alkyl groups include but are not limited to methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, and the like.
  • Alkenyl refers to a straight-chain or branched unsaturated hydrocarbon group having at least one carbon-carbon double bond. The group may be in either the cis- or trans-configuration around each double bond. In certain embodiments, the alkenyl group can have from 2 to 10 carbon atoms, in certain embodiments from 2 to 8 carbon atoms, in certain embodiments, 2 to 6 carbon atoms. The alkenyl group may be unsubstituted or substituted. Unless otherwise specified, the alkenyl group may be attached at any suitable carbon atom and, if substituted, may be substituted at any suitable carbon atom. Examples of alkenyl groups include but are not limited to ethenyl (vinyl), 2-propenyl (allyl), 1-methylethenyl, 2-butenyl, 3-butenyl and the like.
  • Alkynyl refers to a straight-chain or branched unsaturated hydrocarbon group having at least one carbon-carbon triple bond.
  • the alkynyl group can have from 2-10 carbon atoms, in certain embodiments from 2-8 carbon atoms, in certain embodiments, 2-6 carbon atoms.
  • the alkynyl group may be unsubstituted or substituted. Unless otherwise specified, the alkynyl group may be attached at any suitable carbon atom and, if substituted, may be substituted at any suitable atom.
  • alkynyl groups include but are not limited to ethynyl, prop-1-ynyl, prop-2-ynyl, 1-methylprop-2-ynyl, but-1-ynyl, but-2-ynyl, but-3-ynyl and the like.
  • Aryl refers to an aromatic carbocyclic group.
  • the aryl group may have a single ring or multiple condensed rings.
  • the aryl group can have from 6 to 20 carbon atoms, in certain embodiments from 6 to 15 carbon atoms, in certain embodiments, 6 to 12 carbon atoms.
  • the aryl group may be unsubstituted or substituted. Unless otherwise specified, the aryl group may be attached at any suitable carbon atom and, if substituted, may be substituted at any suitable carbon atom. Examples of aryl groups include, but are not limited to, phenyl, naphthyl, anthracenyl and the like.
  • bath includes a concentrate for ease of storage and transport.
  • Cycloalkyl refers to a cyclic saturated hydrocarbon group.
  • the cycloalkyl group may have from 3-10 carbon atoms, in certain embodiments from 3-10 carbon atoms, in certain embodiments, 3-8 carbon atoms, in certain embodiments, 3-6 carbon atoms.
  • the cycloalkyl group may be unsubstituted or substituted. Unless otherwise specified, the cycloalkyl group may be attached at any suitable carbon atom and, if substituted, may be substituted at any suitable atom.
  • Typical cycloalkyl groups include but are not limited to cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like.
  • Heterocycloalkyl refers to a saturated cyclic hydrocarbon group wherein one or more carbon atoms are independently replaced with one or more heteroatoms (e.g. nitrogen, oxygen, phosphorus and/or sulfur atoms).
  • the heterocycloalkyl group may have from 2-10 carbon atoms, in certain embodiments from 2-10 carbon atoms, in certain embodiments, 2-8 carbon atoms in certain embodiment, 2-6 carbon atoms.
  • the heterocycloalkyl group may be unsubstituted or substituted. Unless otherwise specified, the heterocycloalkyl group may be attached at any suitable atom and, if substituted, may be substituted at any suitable atom. Examples of heterocycloalkyl group include but are not limited to epoxide, morpholinyl, piperadinyl, piperazinyl, thirranyl and the like.
  • Heteroalkyl refers to a straight-chain or branched saturated hydrocarbon group wherein one or more carbon atoms are independently replaced with one or more heteroatoms (e.g. nitrogen, oxygen, phosphorus and/or sulfur atoms).
  • the heteroalkyl group may have from 1 to 10 carbon atoms, in certain embodiments from 1 to 8 carbon atoms, in certain embodiments from 1 to 6 carbon atoms.
  • the heteroalkyl group may be unsubstituted or substituted. Unless otherwise specified, the heteroalkyl group may be attached at any suitable atom and, if substituted, may be substituted at any suitable atom.
  • Heteroaryl refers to an aromatic carbocyclic group wherein one or more carbon atoms are independently replaced with one or more heteroatoms (e.g. nitrogen, oxygen, phosphorus and/or sulfur atoms).
  • the heteroaryl group can have from 5 to 20 carbon atoms, in certain embodiments from 5 to 15 carbon atoms, in certain embodiments, 5 to 12 carbon atoms.
  • the heteroaryl group may be attached at any suitable atom and, if substituted, may be substituted at any suitable atom. Examples of heteroaryl groups include but are not limited to furanyl, indolyl, oxazolyl, pyridinyl, pyrimidinyl, thiazolyl, thiphenyl and the like.
  • Heteroatom refers to nitrogen, oxygen or sulfur, preferably nitrogen or oxygen and most preferably nitrogen.
  • Polyphosphate refers to a group comprising two or more (e.g. 3, 4, 5 or 6) phosphate (PO 4 ) groups linked together via shared oxygen atoms.
  • the polyphosphate may be linear or cyclic.
  • Root temperature means from about 20° C. to about 35° C.
  • “Substituted” refers to a group in which one or more (e.g. 1, 2, 3, 4 or 5) hydrogen atoms are each independently replaced with substituents which may be the same or different.
  • substituents include but are not limited to -halo, —C(halo) 3 , —R a , ⁇ O, ⁇ S, —O—R a , —S—R a , —NR a R b , ⁇ NR a , ⁇ N—OR a , —CN, —SCN, —NCS, —NO 2 , —C(O)—R a , —COOR a , —C(S)—R a , —C(S)OR a , —S(O) 2 OH, —S(O) 2 —R a , —S(O) 2 NR a R b , —O—S(O)—R a and —CON
  • the present invention provides an aqueous platinum electroplating bath comprising:
  • the source of platinum ions may be at least one (e.g. 1, 2, 3, 4 or 5 preferably 1) platinum plating salt or complex.
  • the platinum plating salts useful in the invention include a large number of salts or dissolved complexes, for example, diammine dinitroplatinum(II) (i.e. “P Salt”), tetraammineplatinum(II) hydrogen orthophosphate (i.e. “Q Sale”), tetraammineplatinum(II) sulphate, alkali metal hexahydroxyplatinates(IV) (such as sodium hexahydroxyplatinate(IV) or potassium hexahydroxyplatinate(IV)), alkali metal tetranitroplatinates(II) (e.g.
  • the platinum ions may be cationic or anionic.
  • the platinum ions may be may be at an oxidation state of (II) or (IV).
  • the bath of the present invention comprises a source of polyphosphate anions.
  • the polyphosphate anion source may be an alkali metal salt, alkaline earth metal salt or ammonium salt of a polyphosphoric acid, or a mixture thereof. Hydrates or anhydrous salts may be used, although the use of anhydrous salts is not essential as the plating bath is aqueous.
  • the salt is an alkali metal salt
  • the salt is preferably a lithium, sodium or potassium salt.
  • the salt may be a magnesium or calcium salt.
  • suitable polyphosphate salts include but are not limited to disodium pyrophosphate dibasic, dipotassium dibasic pyrophosphate, tetrasodium pyrophosphate, tetrasodium pyrophosphate decahydrate, tetrapotassium pyrophosphate, potassium tripolyphosphate, sodium hexametaphosphate, potassium hexametaphosphate, lithium hexametaphosphate, lithium hexametaphosphate.6H 2 O, potassium pyrophosphate, sodium pyrophosphate or a mixture thereof.
  • the polyphosphate ion source may be a polyphosphoric acid, such as pyrophosphoric acid.
  • the plating baths when made up to be ready for use suitably have a polyphosphate ion concentration of about 0.1 to about 90 g/litre e.g. about 5 to about 80 g/litre. While it possible for the polyphosphate ion concentration to be greater than about 90 g/litre, this is usually undesirable as the polyphosphate may begin to crystallise out of the plating bath at lower temperatures, e.g. room temperature. This may then create handling or processing difficulties with regard to the plating bath.
  • the polyphosphate ion concentration is about ⁇ 0.1 g/litre. In some embodiments, the polyphosphate ion concentration is about ⁇ 1 g/litre.
  • the polyphosphate ion concentration is about ⁇ 2.5 g/litre. In some embodiments, the polyphosphate ion concentration is about ⁇ 5 g/litre. In some embodiments, the polyphosphate ion concentration is about ⁇ 10 g/litre. In some embodiments, the polyphosphate ion concentration is about ⁇ 15 g/litre.
  • the polyphosphate ion concentration is about ⁇ 85 g/litre, in some embodiments about ⁇ 85 g/litre, in some embodiments about ⁇ 80 g/litre, in some embodiments about ⁇ 75 g/litre, in some embodiments about ⁇ 70 g/litre, in some embodiments about ⁇ 65 g/litre, in some embodiments about ⁇ 60 g/litre, in some embodiments about ⁇ 55 g/litre, in some embodiments about ⁇ 50 g/litre, in some embodiments about ⁇ 45 g/litre, in some embodiments about ⁇ 40 g/litre, in some embodiments about ⁇ 35 g/litre, in some embodiments about ⁇ 30 g/litre, in some embodiments about ⁇ 25 g/litre, in some embodiments about ⁇ 20 g/litre.
  • the polyphosphate ion concentration is about 10 to about 20 g/litre.
  • the polyphosphate ion concentration may be determined from the mass of the components used to make up the bath. However, when the bath is in use, the polyphosphate ion concentration may be assessed using analytical techniques such as titration, gravimetric methods or ion-chromatography.
  • the platinum plating bath ready for use or in use has a pH in the range from about 2 to about 9. If the pH of the bath is ⁇ 2, the bath may be very corrosive which may present equipment problems with its use and containment. For example, the equipment needed to analyse the bath (e.g. HPLC internals and column) may be severely affected, or levellers (if used) or other organic additives (if used), such as wetting agents may be destroyed. Moreover, the range of substrates which may be plated would be limited, as well as the materials used in supporting the workpiece. In addition, the present inventors have found that a bath at a pH of ⁇ 2 is generally inefficient, plates poorly and may have extensive gas formation on the substrate.
  • the pH is >2, in certain embodiments ⁇ 2.5, in certain embodiments ⁇ 3, in certain embodiments ⁇ 3.5, in certain embodiments ⁇ 4, in certain embodiments ⁇ 4.5, in certain embodiments ⁇ 5, in certain embodiments ⁇ 5.5, in certain embodiments ⁇ 6, in certain embodiments ⁇ 6.5.
  • the pH is ⁇ 8.5, preferably ⁇ 8.5, for example, ⁇ 8, such as about 7. In one preferred embodiment, the pH is from about 7 to less than about 8.5.
  • a bath having a pH of from about 7 to less than about 8.5 may be termed a “neutral” bath and is an example of a non-corrosive plating bath.
  • a neutral bath is advantageous as there is little bubbling at the cathode as most energy is used in plating.
  • the pH of the plating bath may be adjusted by the addition of suitable acids, bases or a mixture thereof.
  • suitable acids bases or a mixture thereof.
  • “Q Salt®” solution is normally supplied for use at about pH 10 to 11 and the addition of acid is required to lower the pH of the solution.
  • Any suitable inorganic acid, organic acid or mixture thereof may be utilised.
  • suitable organic acids include but are not limited to formic acid, acetic acid and oxalic acid.
  • suitable inorganic acids include but are not limited to hydrohalic acids (e.g. HCl, HBr or HI), sulfur-containing acids (e.g. sulphuric acid) and phosphorus-containing acids.
  • Phosphorus-containing acids are particularly preferred, such as hypophosphoric acid (H 3 PO 2 ), phosphorous acid (H 3 PO 3 ), ortho-phosphoric acid (H 3 PO 4 ) or pyrophosphoric acid [(HO) 2 P(O)OP(O)(OH) 2 ].
  • Pyrophosphoric acid is itself a source of polyphosphate anions.
  • the use of phosphorus-containing acids in combination with polyphosphate salts as the polyphosphate ion source is advantageous as a buffered plating bath may be prepared.
  • any suitable inorganic base, organic base or mixture may be utilised to increase the pH of the plating bath, if this is required.
  • suitable inorganic bases include but are not limited to alkali metal polyphosphates, alkaline earth metal polyphosphates, ammonium polyphosphates, alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, alkali metal phosphates and alkali metal silicates, such as potassium hydroxide, sodium hydroxide, calcium hydroxide, magnesium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, potassium phosphate, sodium silicate, potassium silicate.
  • suitable organic bases include but are not limited to amines and tetraalkyl ammonium hydroxides, such as ethanolamine or choline hydroxide.
  • the polyphosphate anion source is selected from an alkali metal salt, alkaline earth metal salt or ammonium salt of a polyphosphoric acid such as those described above, the polyphosphate ion source itself may act as a base.
  • the pH will change slowly as the platinum is plated from the bath.
  • the concentration of the platinum can be maintained in the bath by adding fresh plating solution that comprises the platinum ions, polyphosphate anions, acid (if used) and base (if used).
  • each component may be added individually.
  • the plating bath is analysed regularly and replenished as necessary in order to maintain the desired concentration of each component. Suitable concentrations for e.g. the platinum ions and/or polyphosphate anions when the bath is in use are generally those provided above and below in respect of when the bath is ready for use.
  • the platinum ions and the polyphosphate anions may be obtained from different sources.
  • the platinum ions may be derived from the platinum plating salts and complexes
  • the polyphosphate anions may be derived from the salts of polyphosphoric acid.
  • the source of platinum ions and the source of polyphosphate anions may be obtained from the same source.
  • the source for both may be a platinum polyphosphate salt, such as tetraammineplatinum(II) dihydrogen pyrophosphate, di[tetraammineplatinum(II)]pyrophosphate or Na 2 [Pt(NH 3 ) 4 ][H 2 P 2 O 7 ].
  • Aqueous solutions of these salts may be acidic (in the range of pH 3-4), neutral (e.g. about 7) or alkaline (e.g. about 7-8).
  • polyphosphate anions may be added to the bath in order to raise the pH before plating, if necessary (the additional polyphosphate anions, therefore, acting as a secondary source of polyphosphate anions).
  • a neutral or alkaline solution may be used directly in plated if desired without further addition of polyphosphate anions.
  • the use of sulfur-containing materials may not be desirable.
  • An example where sulfur-containing materials may not be desirable is the platinum plating of materials for aerospace applications, especially turbine blades. Accordingly, plating baths containing materials such as sulfur-containing platinum plating salts or complexes, or sulfur-containing acids may not be optimal for such applications.
  • the aqueous platinum plating bath does not comprise a sulfur-containing platinum plating salt or complex. In another embodiment, the aqueous platinum plating bath does not comprise a sulfur-containing acid.
  • sulfur-containing materials may be suitable for the platinum plating of materials other than for aerospace applications.
  • halogen-containing materials particularly chlorine-containing materials
  • the plating baths when made up to be ready for use suitably have a platinum ion concentration of about 1 to about 40 g/litre e.g. about 1 to about 30 g/litre.
  • Preferred platinum concentrations depend upon the product to be coated and the coating apparatus but are typically about 5 g/litre to about 20 g/litre for most normal operations.
  • the platinum ion concentration is ⁇ 5 g/litre, for example, ⁇ 7 g/litre.
  • the platinum ion concentration is ⁇ 10 g/litre, for example, ⁇ 15 g/litre.
  • the platinum ion concentration is ⁇ 20 g/litre, for example, ⁇ 15 g/litre.
  • the plating bath of the present invention may be used at temperatures from about room temperature to about 100° C.
  • the temperature may be from about 60° C. to about 100° C., in certain embodiments from about 60° C. to about 95° C., in certain embodiments from about 70° C. to about 95° C., in certain embodiments from about 75° C. to about 95° C., in certain embodiments from about 75° C. to about 90° C., in certain embodiments from about 70° C. to about 90° C.
  • the higher the plating temperature the greater the plating rate. Greater loss of water by evaporation at higher temperatures may occur, however, this may be monitored and adjusted as appropriate through the addition of water to the bath.
  • the bath of the invention may be used successfully under broadly conventional conditions and current densities.
  • the current density may be from about 2 to about 10 mA/cm 2 , for example, from about 2 to about 6 mA/cm 2 , such as about 4 mA/cm 2
  • the bath can be used to plate using complex methods such as pulse plating or impressed AC ripple or other interrupted plating techniques, but direct current electroplating is preferred.
  • the aqueous platinum electroplating bath is suitable for use in an industrial or commercial electroplating process.
  • the bath of the present invention may be used to rapidly coat large substrates in an industrial sized tank in a continual process rather than being restricted to a research tool explored by cyclic voltammetry, or by other electrochemical probing techniques in a small cell, whilst confined to a small cell.
  • the rate at which the platinum is plated out of solution should be such that the process is commercially viable. In one embodiment, therefore, the rate of plating is about ⁇ 0.5 microns thickness of platinum per hour. In yet another embodiment, the rate of plating is about ⁇ 1 micron thickness of platinum per hour. In another embodiment, the rate of plating is about ⁇ 1.5 microns thickness of platinum per hour.
  • the rate of plating is about ⁇ 2 microns thickness of platinum per hour. In another embodiment, the rate of plating is about ⁇ 2.5 microns thickness of platinum per hour. In yet another embodiment, the rate of plating is about ⁇ 3 microns thickness of platinum per hour. In another embodiment, the rate of plating is about ⁇ 3.5 microns thickness of platinum per hour. In yet another embodiment, the rate of plating is about ⁇ 4 microns thickness of platinum per hour. In another embodiment, the rate of plating is about ⁇ 4.5 microns thickness of platinum per hour. In yet another embodiment, the rate of plating is about ⁇ 5 microns thickness of platinum per hour. In another embodiment, the rate of plating is about ⁇ 5.5 microns thickness of platinum per hour.
  • the rate of plating is about ⁇ 6 microns thickness of platinum per hour. In another embodiment, the rate of plating is about ⁇ 6.5 microns thickness of platinum per hour. In yet another embodiment, the rate of plating is about ⁇ 7 microns thickness of platinum per hour. In another embodiment, the rate of plating is about ⁇ 7.5 microns thickness of platinum per hour. In yet another embodiment, the rate of plating is about ⁇ 8 microns thickness of platinum per hour. In another embodiment, the rate of plating is about ⁇ 8.5 microns thickness of platinum per hour. In yet another embodiment, the rate of plating is about ⁇ 9 microns thickness of platinum per hour. In another embodiment, the rate of plating is about ⁇ 9.5 microns thickness of platinum per hour.
  • the rate of plating is about ⁇ 10 microns thickness of platinum per hour. In one preferred embodiment, the rate of plating is from about 5 microns thickness of platinum per hour to about 10 microns thickness per hour.
  • the plating bath comprises one or more other plating salts or complexes (which are not platinum plating salts or complexes)
  • the above embodiments relate to the plating rate and thickness of platinum alloy per hour.
  • the platinum electroplating bath of the present invention therefore may further comprise at least one leveller.
  • the leveller may contribute to the production of a bright or shiny plate.
  • the leveller may contribute to the lustre of the produced plate.
  • the leveller may help to generate a plate with increased hardness.
  • the leveller comprises at least one unsaturated carbon-carbon or unsaturated carbon-heteroatom bond.
  • the leveller is selected from the group consisting of at least one:
  • the leveller may be a substituted or unsubstituted saccharine or salt thereof.
  • the leveller is a compound of formula (1) or salts thereof:
  • each R 1 is independently an unsubstituted C 1 -C 10 alkyl group
  • R 2 is selected from the group consisting of H, unsubstituted C 1 -C 10 alkyl, an alkali metal ion and an alkaline earth metal ion.
  • m is 0 i.e. the aryl group is unsubstituted.
  • R 2 is H.
  • the compound of formula (1) is a salt wherein R 2 is an alkali metal cation or an alkaline earth metal cation e.g. Na + , K + or Ca 2+ .
  • Examples of compounds of formula (1) include but are not limited to saccharine, sodium saccharine, potassium saccharine and calcium saccharine.
  • the anionic sulfobenzimide group may be present as an amido tautomer (for example see the structure of calcium saccharine above) and/or as the iminyl tautomer (for example see the structure of sodium and potassium saccharine above).
  • the amido and iminyl tautomers are included within the definition of the compound of formula (1).
  • the benzopyranone may be a substituted or unsubstituted 1-benzopyran-2-one, 2-benzopyran-1-one or 1-benzopyran-4-one.
  • the leveller is a compound of formula (2a), (2b) or (2c):
  • the leveller is a compound of formula (2a). In another embodiment, the leveller is a compound of formula (2b). In yet another embodiment, the leveller is a compound of formula (2c).
  • n is 0 i.e. the aryl group is unsubstituted.
  • p is 0.
  • An example of a compound of formula (2a) includes but is not limited to coumarin.
  • the leveller may be a substituted or unsubstituted benzaldehyde or derivative thereof.
  • the leveller is a compound of formula (3a) or (3b):
  • R 20 is selected from the group consisting of H and —OR 23 ; and R 21 and R 22 are independently selected from the group consisting of H, —C(O)R 24 and unsubstituted C 1 -C 10 -alkyl; and R 23 and R 24 are independently selected from the group consisting of H and unsubstituted C 1 -C 10 -alkyl.
  • the leveller is a compound of formula (3a). In another embodiment, the leveller is a compound of formula (3b).
  • R 20 is selected from the group consisting of H, —OH, —OMe, —OEt, —OPr (n- or i-) and —OBu (n-, i- or t-) and more preferably, H, —OH and —OMe.
  • R 23 is preferably —H, -Me, -Et, -Pr (n- or i-), -Bu (n-, i- or t-) and more preferably —H or —OMe.
  • each R 21 and R 22 is independently selected from the group consisting of H, methyl, ethyl, propyl (n- or i-), butyl (n-, i- or t-), —C(O)H, —COMe, —COEt, —COPr (n- or i-) and —COBu (n-, i- or t-). More preferably, each R 21 and R 22 is independently selected from the group consisting of H, methyl, ethyl and —COMe. In these cases, R 24 is preferably H, methyl, ethyl, propyl (n- or i-), butyl (n-, i- or t-) and more preferably Me.
  • Examples of compounds of formula (3a) include but are not limited to vanillin, ethyl vanillin, vanillin acetate, vanillic acid and methyl vallinate.
  • Examples of compounds of formula (3b) include but are not limited to ortho-vanillin and 3-methoxysalicylic acid.
  • the leveller may be a substituted or unsubstituted alkene. In this instance, it is preferred that the leveller is not ethylene. In one preferred embodiment, the leveller is a compound of formula (4):
  • each R 30 , R 31 , R 32 and R 33 is independently selected from the group consisting of H, unsubstituted C 1 -C 10 -alkyl, substituted C 1 -C 10 -alkyl, —CO 2 R 34 , —NR 34 R 35 , —CONR 34 R 35 and —CN, provided that R 30 , R 31 , R 32 and R 33 are not all H, wherein the substituents are selected from the group consisting of at least one (e.g.
  • R 34 and R 35 are independently selected from the group consisting of H and unsubstituted C 1 -C 10 -alkyl; and R 36 and R 37 are independently selected from the group consisting of H and unsubstituted C 1 -C 10 -alkyl.
  • the compounds of formula (4) may be cis-, trans- or geminal-alkenyl compounds.
  • R 30 and R 32 or R 31 and R 33 are H.
  • R 30 and R 33 or R 31 and R 32 are H.
  • R 30 and R 31 or R 32 and R 33 are H.
  • R 30 , R 31 , R 32 and R 33 may each be substituted with a group other than H.
  • each R 30 , R 31 , R 32 and R 33 is independently selected from the group consisting of H, unsubstituted C 1 -C 10 -alkyl, substituted C 1 -C 10 -alkyl, —NH 2 and —CN.
  • the substituents are selected from the group consisting of at least one (e.g. 1, 2, 3, 4 or 5) —OH, —OC(O)Me, —NH 2 , —CN and —SO 3 ⁇ Na + and —SO 3 ⁇ K + .
  • each R 30 , R 31 , R 32 and R 33 is independently selected from the group consisting of H, —CH 2 —OH, —CH(OH)CH 2 —OH, —NH 2 and —CN.
  • Examples of compounds of formula (4) include but are not limited to butenediol (e.g. trans-1,4-butenediol, cis-2-butene-1,4-diol, or 3-butene-1,2-diol) and diaminomaleonitrile.
  • the leveller may be a water-soluble substituted or unsubstituted C 2 -C 10 -alkyne provided the alkyne is not acetylene.
  • the leveller is a compound of formula (5):
  • R 40 and R 41 are independently selected from the group consisting of H, unsubstituted C 1 -C 10 -alkyl and substituted C 1 -C 10 -alkyl, provided that R 40 and R 41 are not both H, wherein the substituents are selected from the group consisting of at least one (e.g. 1, 2, 3, 4 or 5) of —OH, —CO 2 R 42 , —OC(O)R 42 , —NR 42 R 43 , —CONR 42 R 43 , —CN, —SO 3 ⁇ Na + and ⁇ SO 3 ⁇ K + ; R 42 and R 43 are independently selected from the group consisting of H and unsubstituted C 1 -C 10 -alkyl.
  • R 40 and R 41 are independently selected from the group consisting of H, unsubstituted C 1 -C 10 -alkyl and substituted C 1 -C 10 -alkyl, wherein the substituents are selected from the group consisting of at least one (e.g. 1, 2, 3, 4 or 5) of —OH, OC(O)Me, —NH 2 , —CN, —SO 3 ⁇ Na + and —SO 3 ⁇ K + . More preferably, R 40 and R 41 are independently selected from the group consisting of H, —CH 2 —OH, —CH(OH)CH 2 —OH and —CH 2 OC(O)Me. Examples of compounds of formula (5) include but are not limited to 1,4-butynediol, 1,4-butynediol diacetate and propargyl alcohol.
  • the leveller is a substituted or unsubstituted alkylnitrile, it is preferred that the leveller is a compound of formula (6):
  • R 50 is a substituted or unsubstituted C 1 -C 10 -alkyl, and the substituents are selected from the group consisting of at least one (e.g. 1, 2, 3, 4 or 5) of ⁇ OR 51 , —CO 2 R 51 , —OC(O)R 51 , —NR 51 R 52 and —CN; and wherein R 51 and R 52 are independently selected from the group consisting of H and unsubstituted C 1 -C 10 -alkyl.
  • R 50 is a substituted or unsubstituted C 1 -C 10 -alkyl, wherein the substituents are selected from the group consisting of at least one (e.g. 1, 2, 3, 4 or 5) of —OH, —OMe, —OPr (n- or i-), —OBu (n-, or t-), —CO 2 H, —NH 2 and —CN. More preferably, R 50 is selected from the group consisting of —CH 2 CH 2 —OH, —CH(OH)—CH 3 , —CH 2 CO 2 H and —CH 2 —CH 2 —CN. Examples of compounds of formula (6) include but are not limited to 3-hydroxypropionitrile, 2-hydroxypropionitrile, cyanoacetic acid and succinonitrile
  • the leveller may be a substituted or unsubstituted pyridine or an addition salt thereof.
  • the leveller is a compound of formula (7a), (7b) or (7c):
  • R 60 and R 61 are independently selected from the group consisting of —OH, —CN, —CONR 62 R 63 , —CO 2 R 62 , —COR 63 , N-(unsubstituted C 1 -C 10 -alkyl)-pyrrolidinyl, unsubstituted C 1 -C 10 -alkyl, substituted C 1 -C 10 -alkyl, unsubstituted C 2 -C 10 -alkenyl, substituted C 2 -C 10 -alkenyl, —SO 2 —R 63 , —N ⁇ N-(unsubstituted C 6 -C 10 -aryl), —N ⁇ N-(substituted C 6 -C 20 -aryl), unsubstituted pyridyl, substituted pyridyl, wherein the substituents are independently selected from the group consisting of at least one (e.g.
  • R 62 is selected from the group consisting of H, —OH and unsubstituted C 1 -C 10 -alkyl
  • R 63 is selected from the group consisting of H, —OH, unsubstituted C 1 -C 10 -alkyl, unsubstituted C 1 -C 10 -alkyl-CO 2 H, —NH 2 , —NH(unsubstituted C 1 -C 10 -alkyl), —N(unsubstituted C 1 -C 10 -alkyl) 2
  • R 64 is selected from the groups defined for R 62
  • R 65 is selected from the groups defined for R 63 ; each x is 0, 1, 2 or 3; and each y is 0, 1, 2, 3 or 4.
  • the leveller is a compound of formula (7a). In another embodiment, the leveller is a compound of (7b). In yet another embodiment, the leveller is a compound of (7c).
  • the compound of formula (7a) is unsubstituted i.e. x is 0.
  • x is 1 i.e. the compound (7a) is monosubstituted.
  • the substituent R 60 may be attached to any one of the carbons in the pyridine ring i.e. at C-2, C-3 or C-4.
  • x is 2 for the compound of (7a) i.e. the compound is disubstituted.
  • each substituent R 60 may be the same or different.
  • the substituents may be attached to any of the carbons in the pyridine ring i.e.
  • the compound (7a) may be 2,3-, 2,4-, 2,5-, 2,6-, 3,4-, 3,5- or 3,6-disubstituted.
  • compound (7a) is trisubstituted i.e x is 3.
  • each substituent R 60 may be the same or different.
  • the substituents may be attached to any of the carbons in the pyridine ring i.e. the compound (7a) may be 2,3,4-, 2,3,5-, 2,3,6-, 2,4,5-, 2,4,6-, 3,4,5- or 3,4,6-trisubstituted.
  • x may be 0, 1, 2 or 3 for the compound of formula (7b).
  • the pyridinyl ring is unsubstituted.
  • the R 60 substituent may be attached at any of the carbon atoms at C-2, C-3 or C-4.
  • each R 60 substituent may be the same or different.
  • the substituents may be attached to any of the carbons in the pyridine ring i.e. the compound (7b) may be 2,3-, 2,4- or 3,4-substituted.
  • x is 3 and each R 60 is attached at C-2, C-3 and C-4. In this instance, each substituent R 60 may be the same or different.
  • y may be 0, 1, 2, 3 or 4 for the compound (7b). In one embodiment, y is 0. In yet another embodiment, y is 1. In this instance, the substituent R 61 may be attached to any of the carbon atoms at C-5, C-6, C-7 or C-8. In yet another embodiment, when y is 2, each R 61 substituent may be the same or different. The substituents may be attached in any substitution pattern to any of the carbons at C-5, C-6, C-7 or C-8 i.e. the compound (7b) may be 5,6-, 5,7-, 5,8-, 6,7-, 6,8- or 7,8-substituted. In another embodiment, when y is 3, each R 61 substituent may be the same or different.
  • the substituents may be attached in any combination to the carbons at C-5, C-6, C-7 or C-8 i.e. the compound (7b) may be 5,6,7-, 5,6,8-, 5,7,8- or 6,7,8-substituted.
  • y is 4 and each R 61 is attached at C-5, C-6, C-7 and C-8. In this instance, each substituent R 61 may be the same or different.
  • x and y are 0 i.e. compound (7b) is quinoline.
  • x may be 0, 1, 2 or 3 for the compound of formula (7c).
  • the pyridinyl ring is unsubstituted.
  • the R 60 substituent may be attached at any of the carbon atoms at C-1, C-3 or C-4.
  • each R 60 substituent may be the same or different.
  • the substituents may be attached to any of the carbons in the pyridine ring i.e. the compound (7c) may be 1,3-, 1,4- or 3,4-substituted.
  • x is 3 and each R 60 is attached at C-1, C-3 and C-4. In this instance, each substituent R 60 may be the same or different.
  • y may be 0, 1, 2, 3 or 4 for the compound (7c). In one embodiment, y is 0. In yet another embodiment, y is 1. In this instance, the substituent R 61 may be attached to any of the carbon atoms at C-5, C-6, C-7 or C-8. In yet another embodiment, when y is 2, each R 61 substituent may be the same or different. The substituents may be attached in any combination to any of the carbons at C-5, C-6, C-7 or C-8 i.e. the compound (7c) may be 5,6-, 5,7-, 5,8-, 6,7-, 6,8- or 7,8-substituted. In another embodiment, when y is 3, each R 61 substituent may be the same or different.
  • the substituents may be attached in any combination to the carbons at C-5, C-6, C-7 or C-8 i.e. the compound (7c) may be 5,6,7-, 5,6,8-, 5,7,8- or 6,7,8-substituted.
  • y is 4 and each R 61 is attached at C-5, C-6, C-7 and C-8. In this instance, each substituent R 61 may be the same or different.
  • x and y is 0 i.e. compound (7c) is isoquinoline.
  • R 60 is selected from the group consisting of —OH, —CN, —CONR 62 R 63 , —CO 2 R 62 , —COR 63 , N-(unsubstituted C 1 -C 10 -alkyl)-pyrrolidinyl, unsubstituted C 1 -C 10 -alkyl, substituted C 2 -C 10 -alkenyl, —SO 2 —R 63 , —N ⁇ N-(substituted C 6 -C 20 -aryl) and unsubstituted pyridyl.
  • the substituents are selected from the group consisting of at least one (e.g.
  • R 62 and R 64 are preferably independently selected from the group consisting of H, —OH, methyl, ethyl, propyl (n- or i-) and butyl (n-, i- or t-).
  • R 63 and R 65 are preferably independently selected from the group consisting of H, —OH, methyl, ethyl, propyl (n- or i-), butyl (n-, i- or t-), —NH 2 , —NHMe, —NHEt, —NHPr (n- or i-), —NHBu (n-, i- or t-), —NMe 2 , —NEt 2 , —NPr 2 (wherein each Pr group is independently n- or i-), —NBu 2 (wherein each Bu group is independently n-, i- or t-) and —CH 2 —CO 2 H.
  • R 60 is selected from the group consisting of methyl, ethyl, propyl (n- or i-), butyl (n-, i- or t-), —CN, —CO 2 H, —COH, —CONH(OH), —CONH(NH 2 ), —CONH 2 , N-Me-pyrrolidinyl-2-yl, —CO 2 Me, —CONMe 2 , —CO 2 Et, —CONEt 2 , —CONMeEt, —C ⁇ C—CO 2 H, —SO 2 OH, —N ⁇ N-(2,4-dihydroxy-phenyl), -pyridyl, —C(NOH)(NH 2 ), —C(NOH)(NMe 2 ), —C(NOH)(NEt 2 ), —C(NOH)(NMeEt) and —CONH(CH 2 CO 2 H).
  • R 61 is selected from the group consisting of methyl, ethyl, propyl (n- or i-), butyl (n-, i- or t-), —CN, —CO 2 H, —COH, —CONH(OH), —CONH(NH 2 ), —CONH 2 , N-Me-pyrrolidinyl-2-yl, —CO 2 Me, —CONMe 2 , —CO 2 Et, —CONEt 2 , —CONMeEt, —C ⁇ C—CO 2 H, —SO 2 OH, —N ⁇ N-(2,4-dihydroxy-phenyl), -pyridyl, —C(NOH)(NH 2 ), —C(NOH)(NMe 2 ), —C(NOH)(NEt 2 ), —C(NOH)(NMeEt) and —CONH(CH 2 CO 2 H).
  • R 61 is selected from the group consisting of methyl, ethyl, propyl (n- or i-), butyl (n-, i- or t-), —CN, —CO 2 H, —COH, —CONH(OH), —CONH(NH 2 ), —CONH 2 , —CO 2 Me, —CONMe 2 , —CO 2 Et, —CONEt 2 , —CONMeEt, —C(NOH)(NH 2 ), —C(NOH)(NMe 2 ), —C(NOH)(NEt 2 ), and —C(NOH)(NMeEt).
  • Examples of compounds of formula (7a), (7b) and (7c) include but are not limited to 4-cyanopyridine, 2-cyanopyridine, nicotinic hydrazide, iso-nicotinamide, nicotinamide, iso-nicotinic acid, nicotinic acid, nicotine, methyl nicotinate, N,N-dimethylnicotinamide, trans-3-(3-pyridyl)acrylic acid, trans-3-(4-pyridyl)acrylic acid, pyridine-3-sulfonic acid, 4-(2-pyridylazo)resorcinol, iso-nicotinaldehyde, nicotinaldehyde, bipyridyl (2,2′- and 4,4′-), quinoline, isoquinoline or other compound of formula (7a), (7b) or (7c) illustrated below.
  • a compound of formula (7) can convert to another compound of formula (7) under the conditions used in the plating bath of the present invention, i.e such as one compound of formula (7a) to another compound of formula (7a), a compound (7b) to another compound (7b) or a compound (7c) to another compound (7c).
  • 4-cyanopyridine, iso-nicotinamide and iso-nicotinaldehyde may each convert to iso-nicotinic acid
  • 3-cyanopyridine, nicotinamide, nicotinaldehyde and nicotinic hydrazide may each convert to nicotinic acid.
  • the compound of formula (7) therefore includes within its scope the starting compound of formula (7), the converted compound of formula (7) and mixtures thereof. In this embodiment, it is not envisaged that e.g. a compound (7a) would convert to e.g. a compound (7c) or vice versa.
  • the salt may be an alkali metal salt, an alkaline earth metal salt or an ammonium salt.
  • the salt is a sodium, potassium, calcium or ammonium salt.
  • Examples of salts of compound of formula (7a), (7b) or (7c) include but are not limited to nicotinic acid sodium salt, nicotinic acid potassium salt, nicotinic acid calcium salt, nicotinic acid ammonium salt, iso-nicotinic acid sodium salt, iso-nicotinic acid potassium salt, iso-nicotinic acid calcium salt and iso-nicotinic acid ammonium salt.
  • the triazole may be a 1,2,3- or a 1,2,4-triazole.
  • the leveller is a compound of formula (8):
  • R 70 is selected from a group consisting of H, —CO 2 R 72 and —NR 72 R 73 ;
  • R 71 is selected from a group consisting of H and unsubstituted C 1 -C 10 -alkyl;
  • R 72 and R 73 are independently selected from the group consisting of H and unsubstituted C 1 -C 10 -alkyl;
  • one of X 1 and X 2 is C—R 74 and the other of X 1 and X 2 is N; and
  • R 74 is selected from a group as defined for R 70 .
  • X 1 is C—R 74 and X 2 is N. In another embodiment, X 2 is C—R 74 and X 1 is N.
  • R 70 is selected from a group consisting of H, —CO 2 H, —CO 2 Me, —CO 2 Et, —CO 2 Pr (n- or i-), —CO 2 Bu (n-, i- or t-), —NH 2 , —NHMe, —NHEt, —NHPr (n- or i-), —NHBu (n-, i- or t-), —NMe 2 , —NEt 2 , —NPr 2 (wherein each Pr group is independently n- or i-) and —NBu 2 (wherein each Bu group is independently n-, i- or t-).
  • R 72 and R 73 therefore are independently selected from the group consisting of H, methyl, ethyl, propyl (n- or i-) and butyl (n-, i- or t-).
  • R 71 is preferably selected from a group consisting of H, methyl, ethyl, propyl (n- or i-) and butyl (n-, i- or t-).
  • R 74 is preferably selected from the group consisting of H, —CO 2 H, —CO 2 Me, —CO 2 Et, —CO 2 Pr (n- or i-), —CO 2 Bu (n-, i- or t-), —NH 2 , —NHMe, —NHEt, —NHPr (n- or i-), —NHBu (n-, i- or t-), —NMe 2 , —NEt 2 , —NPr 2 (wherein each Pr group is independently n- or i-) and —NBu 2 (wherein each Bu group is independently n-, i- or t-).
  • Examples of compounds of formula (8) include but are not limited to 3-amino-1,2,4-triazole and 3-amino-1,2,4-triazole-5-carboxylic acid.
  • the leveller may be a substituted or unsubstituted pyridinium salt.
  • the leveller is a compound of formula (9a), (9b) or (9c):
  • R 60 and R 61 are independently selected from the group consisting of —OH, —CN, —CONR 62 R 63 , —CO 2 R 62 , —COR 63 , N-(unsubstituted C 1 -C 10 -alkyl)-pyrrolidinyl, unsubstituted C 1 -C 10 -alkyl, substituted C 1 -C 10 -alkyl, unsubstituted C 2 -C 10 -alkenyl, substituted C 2 -C 10 -alkenyl, —SO 2 —R 63 , —N ⁇ N-(unsubstituted C 6 -C 10 -aryl), —N ⁇ N-(substituted C 6 -C 20 -aryl), unsubstituted pyridyl, substituted pyridyl, wherein the substituents are independently selected from the group consisting of at least one (e.g.
  • R 62 is selected from the group consisting of H, —OH and unsubstituted C 1 -C 10 -alkyl
  • R 63 is selected from the group consisting of H, —OH, unsubstituted C 1 -C 10 -alkyl, unsubstituted C 1 -C 10 -alkyl-CO 2 H, —NH 2 , —NH(unsubstituted C 1 -C 10 -alkyl), —N(unsubstituted C 1 -C 10 -alkyl) 2
  • R 64 is selected from the groups defined for R 62
  • R 65 is selected from the groups defined for R 63
  • R 82 is selected from the group consisting of —O ⁇ and unsubstituted C 1 -C 10
  • the leveller is a compound of formula (9a). In another embodiment, the leveller is a compound of formula (9b). In yet another embodiment, the leveller is a compound of formula (9c).
  • R 60 , R 61 , R 62 , R 63 , R 64 , R 65 , x and y are as generally described above with regard to the compounds of formulae (7a), (7b) and (7c) and each of these embodiments can be considered recited herein with regard to the compounds of formulae (9a), (9b) and (9c).
  • R 82 is a substituent attached to the nitrogen atom.
  • R 82 may be —O ⁇ i.e. the compound of formula (9a), (9b) or (9c) is an N-oxide.
  • a counterion Z is generally not required in order to stabilise the pyridinyl N atom.
  • R 82 may be an unsubstituted C 1 -C 10 -alkyl, such as methyl, ethyl, propyl (n- or i-), butyl (n-, i- or t-).
  • a counterion Z is required and any suitable counterion may be utilised, for example, halide anions such as F, Cl ⁇ , Br or I ⁇ .
  • a compound of formula (9) it is possible for a compound of formula (9) to convert to another compound of formula (9) under the conditions used in the plating bath of the present invention, i.e such as one compound of formula (9a) to another compound of formula (9a), a compound (9b) to another compound (9b) or a compound (9c) to another compound (9c).
  • the compound of formula (9) therefore includes within its scope the starting compound of formula (9), the converted compound of formula (9) and mixtures thereof. In this embodiment, it is not envisaged that e.g. a compound (9a) would convert to e.g. a compound (9c) or vice versa.
  • Examples of compounds of formula (9a), (9b) and (9c) include but are not limited to those illustrated below:
  • the leveller may be a substituted or unsubstituted polyalkyleneimine.
  • the leveller is preferably unsubstituted polyethyleneimine or ethoxylated polyethyleneimine.
  • the leveller Before the bath is utilised in a plating process, the leveller may in insoluble, partially soluble or substantially completely soluble in the other bath components. However, when the bath is in use it is desirable that the leveller is substantially completely soluble at the desired plating temperature.
  • the leveller may be added in any suitable quantity, for example, from about 0.0001 g/litre to about 10 g/litre.
  • the concentration of leveller is about ⁇ 0.001 g/litre, in another embodiment about ⁇ 0.01 g/litre, in another embodiment about ⁇ 03.1 g/litre.
  • the concentration of leveller is about ⁇ 9 g/litre, in another embodiment about ⁇ 8 g/litre, in another embodiment about ⁇ 7 g/litre, in another embodiment about ⁇ 6 g/litre, in another embodiment about ⁇ 5 g/litre.
  • the concentration of the leveller is about 0.01 g/litre to about 5 g/litre.
  • the aqueous platinum electroplating bath may comprise more than one leveller e.g. 2, 3, 4, or 5 levellers.
  • each leveller may be independently selected from those as described above.
  • the plating bath of the present invention may comprise one or more other plating salts or complexes, such as platinum group metal (PGM) plating salts or complexes, or base metal plating salts or complexes.
  • PGM platinum group metal
  • the PGM salts or complexes may be rhodium, palladium, iridium, ruthenium or rhenium plating salts or complexes, such as HReO 4 .
  • Base metal plating salts include but are not limited to hexaamminenickel(II) chloride.
  • the bath may be prepared by adding the components in any suitable order, for example, in one method an acid (if used) may be added to an aqueous solution of the platinum ions, followed by the polyphosphate anion source, base (if used), leveller (if used) and other components (if used). In another method, a base may be added to an aqueous solution of a platinum polyphosphate salt, followed by a leveller (if used) and other components (if used).
  • the plating baths may further comprise one or more brighteners or other components, for example, surfactants or wetting agents to suppress bubble formation on the substrate.
  • Suitable wetting agents/surfactants include polyethyleneglycol 50% aqueous solution or long chain alkyl sarcosines.
  • the invention includes a method of plating a PGM onto a substrate, comprising electroplating using the bath of the invention.
  • the substrate is preferably a conductive substrate, such as a metal, conductive plastic or conductive ceramic.
  • the invention includes a platinum salt which is tetraammineplatinum(II) dihydrogen pyrophosphate, di[tetraammineplatinum(II)]pyrophosphate or Na 2 [Pt(NH 3 ) 4 ][H 2 P 2 O 7 ].
  • the platinum plating salt is tetraammineplatinum(II) dihydrogen pyrophosphate.
  • the platinum plating salt is di[tetraammineplatinum(II)]pyrophosphate.
  • the platinum plating salt is Na 2 [Pt(NH 3 ) 4 ][H 2 P 2 O 7 ].
  • the invention includes the use of an aqueous platinum plating bath as defined herein for plating platinum or platinum alloy onto a substrate.
  • platinum is plated onto a substrate.
  • a platinum alloy is plated onto a substrate.
  • the substrate may be a metal (e.g. a metal article or metal powder), conductive plastic or conductive ceramic (such as a zirconia oxygen sensor or ceramic ozone destructor for motor vehicles or aircraft).
  • the invention includes a method for the preparation of tetraammineplatinum(II) dihydrogen pyrophosphate comprising the step of reacting Pt(NH 3 ) 4 (OH) 2 or Pt(NH 3 ) 4 (HCO 3 ) 2 with pyrophosphoric acid in water, wherein the molar ratio of Pt(NH 3 ) 4 (OH) 2 or Pt(NH 3 ) 4 (HCO 3 ) 2 : pyrophosphoric acid is about 1: about 1.
  • the invention includes a method for the preparation of di[tetraammineplatinum(II)]pyrophosphate comprising the step of reacting Pt(NH 3 ) 4 (OH) 2 or Pt(NH 3 ) 4 (HCO 3 ) 2 with pyrophosphoric acid in water, wherein the molar ratio of Pt(NH 3 ) 4 (OH) 2 or Pt(NH 3 ) 4 (HCO 3 ) 2 : pyrophosphoric acid is about 1: about 0.5.
  • the invention includes a method for the preparation of Na 2 [Pt(NH 3 ) 4 ][H 2 P 2 O 7 ] comprising the step of reacting Pt(NH 3 ) 4 (OH) 2 or Pt(NH 3 ) 4 (HCO 3 ) 2 with Na 2 H 2 P 2 O 7 in water, wherein the molar ratio of Pt(NH 3 ) 4 (OH) 2 or Pt(NH 3 ) 4 (HCO 3 ) 2 : Na 2 H 2 P 2 O 7 is about 1:about 1.
  • tetraammineplatinum(II) dihydrogen pyrophosphate di[tetraammineplatinum(II)]pyrophosphate and Na 2 [Pt(NH 3 ) 4 ][H 2 P 2 O 7 ] may be used as aqueous solutions.
  • the platinum complexes may be isolated as solids using known methods.
  • FIG. 1 illustrates a shaped part of the given dimensions which is used to assess the deposition of platinum (or platinum alloys) onto shaped parts.
  • FIG. 2 is a distribution plot of platinum thickness at locations 1-8 identified in FIG. 1 .
  • 20Q “Q Salt®” material is commercially available from Johnson Matthey and is an ammoniacal solution of tetraammineplatinum(II) hydrogen phosphate at a pH of about 10 to 11 and 20 g/l Pt.
  • substrates were 9 ⁇ 2.5 cm panels, thickness 1 mm for 316 stainless steel and 2 mm for brass.
  • the brass panels were either manually polished using “Brasso®” or grit blasted using Type 150 and 180/220 brown aerospace grade grit; stainless steel panels were cleaned and degreased using 1M sodium hydroxide solution, followed by a dip in 6M hydrochloric acid.
  • the shaped substrates as shown in FIG. 1 were of Iconel or 316 stainless steel and were treated before use by grit blasting with 180/220 brown aerospace grit and alkali cleaning using 1M sodium hydroxide solution for 6 minutes at a temperature of at least 60° C., followed by a dip (1-2 minutes) in 6M hydrochloric acid at room temperature. The substrates were washed thoroughly between each treatment.
  • the panels were immersed in the plating baths to a depth of 5 cm, within 150, 400 or 600 ml glass beakers.
  • the anode and cathode were 4 cm apart if a 400 ml beaker was used and 2.5 cm apart if a 150 ml beaker was used.
  • the substrates were used as cathodes and the anode was a platinised titanium sheet (plated on both sides) placed directly opposite the cathode or a circular platinised titanium mesh surrounding the cathode.
  • the circular platinised titanium mesh was placed around the inner circumference wall of the glass beaker.
  • An attractive bright coating was obtained of weight 0.3016 g platinum.
  • a plating bath was formed from 5.3 g potassium tetranitroplatinate(II) (Alfa Aesar), 0.5 ml of 45% ortho-phosphoric acid, 2.5 g of tetrapotassium pyrophosphate and 250 ml of water.
  • the initial concentration of Pt as metal in the bath was 9 g/l.
  • Example 7a As for Example 7a except that 150 ml of 20Q solution was used with 150 ml of water.
  • Example 7a As for Example 7a except that 300 ml of 20Q solution used, no water and the masses of the phosphorus-containing components were doubled.
  • Tetraammineplatinum(II) dihydrogen pyrophosphate [Pt(NH 3 ) 4 ][H 2 P 2 O 7 ] was prepared by reacting 1 mole of Pt(NH 3 ) 4 (OH) 2 or Pt(NH 3 ) 4 (HCO 3 ) 2 with 1 mole of pyrophosphoric acid, H 4 P 2 O 7 in water.
  • Na 2 [Pt(NH 3 ) 4 ][H 2 P 2 O 7 ] was prepared by reacting 1 mole of Pt(NH 3 ) 4 (OH) 2 or Pt(NH 3 ) 4 (HCO 3 ) 2 with 1 mole of Na 2 H 2 P 2 O 7 in water.
  • Example 8a As for Example 8a except that 300 ml of tetraammineplatinum(II) dihydrogen pyrophosphate or di[tetraammineplatinum(II)]pyrophosphate solution at pH 3 and 10 g/l Pt as metal was used. Tetrapotassium pyrophosphate or sodium hydroxide was added to increase the pH to 7-8. A clear solution formed and a leveller was added if desired. The bath was heated to 90° C., whereupon the bath was ready for plating.
  • the shaped test part was plated with 0.03 g of levelled Pt in 60 minutes.
  • a plating bath was formed from 125 ml of 20Q solution (20 g/l of platinum as metal), 175 ml of water, 0.7 ml of 40% phosphoric acid, 2.5 g of potassium pyrophosphate and 0.04 g of nicotinic acid N-oxide.
  • the initial concentration of Pt as metal in the bath was 8.3 g/l.
  • Isonicotinamide, isonicotinic acid and nicotinic acid were tested as levellers in plating baths under the following conditions:
  • the plating bath was prepared from 125 ml of 20Q solution (20 g/l platinum as metal), 0.5-1 ml of 40% phosphoric acid, 2.5 g potassium pyrophosphate, 175 ml water and 0.04 g of leveller.
  • the plating conditions were 072 mA on a 12 sq. cm. shaped test part, pH 7.5-8.5 at 90° C.
  • a second sample of polished brass (dimensions 4 ⁇ 2.5 cm) was plated in the bath to give 0.1980 g of alloy coating in 60 mins at 1.87V, 069 mA, 90° C. and pH 8.
  • a third sample of polished stainless steel (dimensions 4 ⁇ 2.5 cm) was plated in the bath to give 0.1710 g of alloy coating in 60 mins at 1.87V, 069 mA, 90° C. and pH 8.
  • the effect of selected levellers on the platinum plating distribution was assessed using a shaped part as shown in FIG. 1 .
  • the part was plated, cut it in half and then after mounting and polishing the plated thickness at eight points around the part was measured (see FIG. 2 ).
  • the distribution plot for commercially available Q Salt shows an increased thickness at locations 2, 4, 6 and 8 together with a reduces thickness at locations 3 and 7. All the other plots show less variation due to the presence of the named levellers.
  • a stock solution was prepared from 300 ml of 20Q solution (pH 10-11 and 20 g/l of Pt as metal) and 50% phosphoric acid was added dropwise with stirring until the pH was lowered to 3.
  • a platinum plating bath was prepared from 50 ml of the stock solution, 3 g sodium tripolyphosphate (85% tech grade) and 120 ml water. The pH of the bath was 7.
  • a steel plaque (dimensions 6 ⁇ 2.5 cm) was plating using the conditions 1.66V, 076 mA, 80-85° C., pH 7 to give 0.2020 g of a bright platinum plate in 60 minutes.

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  • Electroplating And Plating Baths Therefor (AREA)
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US10612149B1 (en) * 2019-09-05 2020-04-07 Chow Sang Sang Jewellery Company Limited Platinum electrodeposition bath and uses thereof

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CN104152953A (zh) * 2014-08-29 2014-11-19 昆明贵金属研究所 磷酸槽电镀铂用的主盐及其合成方法
CN105132964A (zh) * 2015-09-21 2015-12-09 无锡清杨机械制造有限公司 一种磷酸盐体系的铂电镀液及其电镀方法
CN105386096A (zh) * 2015-09-21 2016-03-09 无锡清杨机械制造有限公司 一种碱性镀Pt的电镀液及其电镀方法
CN105154931A (zh) * 2015-09-21 2015-12-16 无锡清杨机械制造有限公司 一种二硝基硫酸二氢化铂的铂电镀液及其电镀方法
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GB202020071D0 (en) 2020-12-18 2021-02-03 Johnson Matthey Plc Electroplating solutions
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WO2016035645A1 (ja) * 2014-09-04 2016-03-10 日本高純度化学株式会社 パラジウムめっき液及びそれを用いて得られたパラジウム皮膜
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US10612149B1 (en) * 2019-09-05 2020-04-07 Chow Sang Sang Jewellery Company Limited Platinum electrodeposition bath and uses thereof
CN111304708A (zh) * 2019-09-05 2020-06-19 周生生珠宝金行有限公司 一种铂电沉积液及其用途

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SG10201510015PA (en) 2016-01-28

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