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
  • C25D3/38—Electroplating: Baths therefor from solutions of copper

Definitions

• This invention relates to the electrodeposition of copper from aqueous acidic baths, especially from acidic copper sulfate and fl-uoborate baths. More particularly it relates to the use of certain organic compounds in the baths in new relationships which make possible bright, highly ductible, low stress, good leveling copper deposits.
• 1,3-dioxolane polymers when used together in the acidic copper baths with very low concentrations of certain organic sulfide (thiols, thioethers, etc.) compounds carrying sulfonic groups such as those of Table I, enable the electrode'position of smooth bright copper plate without decreasing appreciably the ductility of the copper deposits.
• organic sulfide thiols, thioethers, etc.
• the sulfonated organic sulfides first described for use in acidic copper baths by Henricks US.
• Patent 2,424,- 887, July 29, 1947 such as th-ianthrene sulfonic acids, Example 4, Table I, and the phenyl disulfide sulfonic acids, Example 5, Table I, used in as low concentrations as 0.0005 to 0.01 gram/liter with about 0.05 to 0.2 gram/liter of the high molecular weight 1,3-dioxolane polymers cooperate to give bright ductile copper deposits.
• sulfonated thianthrene for example, is used alone, or with a similar sul-fonated organic sulfide, in an acidic copper bath as shown in Example 8 of US. 2,424,887, it is necessary to use 1 to 2 grams/liter for brightness.
• the 1,3-dioxolane though a 5-membered ring, can be converted into high molecular weight polymers in accordance with well-known polymerization procedures, namely by heating the dioxolane in the presence of an acidic catalyst until a polymer of the desired molecular weight has been obtained, which for this application is about 5,000.
• the best acidic catalyst for the polymerization of the dioxolane is the boron tri-fluoride type.
• the polymers of 1,3-dioxolane are polyethers consisting of alternating methylene and ethylene groups interrupted by oxygen atoms.
• the polymers of 1,3-dioxolane can be fiurther reacted with many organic compounds having a reactive hydrogen atom, such as alcohols, iglycols, sugars, aryl amines, chlorohydrins, amides, thiol compounds, .alkanol SllllfOHiC acids, nitriles, thio-aryl, and thioand thiol-alkane sulfonic acids, alkanolamines, etc., and such bath soluble polymers which can be formed in which the portion of poly-1,3-dioxolane predominates, that is, constitutes over 50% of the molecular weight of the polymer, usually produce beneficial efiects on the copper plate, and often improved results are obtained.
• organic compounds having a reactive hydrogen atom such as alcohols, iglycols, sugars, aryl amines, chlorohydrins, amides, thiol compounds, .alkan
• the sulfonated organic sulfide compounds that is the compounds of Table I, in the very low concentrations of 0.0005 to 0.01 gram/liter, below the concentration where brightness is discernible from these compounds, prevent the harmful striations and ribbing effects that polyethers such as the high molecular weight polyethylene ethanols and glycols (average molecular weight of 220 to at least 30,000) cause in the absence of at least 0.02 to 0.1 gram/liter of chloride or bromide ion. Not only are the striations and ribbing effects eliminated without the need of chloride or bromide ions, but just as had occurred with the poly-dioxolanes, a very bright deposit was also obtained.
• polyethers such as the high molecular weight polyethylene ethanols and glycols (average molecular weight of 220 to at least 30,000) cause in the absence of at least 0.02 to 0.1 gram/liter of chloride or bromide ion.
• polyethers such as polypropylene propanols and especially glycols of average molecular weight of about 290 to 1,000 which cause very severe striations especially with the higher molecular weight species, when used in concentrations of about 0.1 to 0.5 gram/liter were found to give no striations and even brighter plate than the high molecular weight polyethylene ethanols and glycols, when used similarly with the very low concentrations of the compounds of Table I.
• a large class of bathsoluble derivatives of polyethylene oxide or polypropylene oxide, or mixtures can be used.
• Terminal groups other than the hydroXy group may be present on the polyether polymers of this invention, such as amino, chloride, bromide, sulfonic, mercapto, methoxy to heptoxy, naphthoxy, phenoxy, and chloro, bromo, nitro, methoxy and ethoxy substituted phenoxy groups, as well as small chain alkyl phenoxy groups where the alkyl group is less than 6 carbon atoms.
• the class of polymers which are useful for the purposes of this invention includes the polyether compounds containing at least six ether oxygen atoms and which are free from alkyl chains having more than 6 carbon atoms. It has been found that compounds containing alkyl chains of more than 6 carbon atoms tend to overfoam with air agitation but more importantly de crease the luster of the deposit, especially in the low current density areas.
• Table II representative examples of the bath soluble polyether derivatives which can be used with the low concentrations of the compounds of Table I to give bright, ductile copper plate.
• the preferred compounds of Table II, besides the poly-dioxolane, from the standpoint of best cooperation with the compounds of Table I, to give smooth, striation-free, bright, ductile copper are the polypropylene propanols and glycols of average molecular weight of about 360 to about 1,000.
• the dyes of the phenaziine class (the Safranine type) and more especially the phenazine azo dyes (the Janus Green B type) which make possible the greatly improved leveling and extended b-right plating range can be represented by the following formula.
• the preferred phenazine 'dyes are the Janus Green B type (Diethyl Safranine Azo Dimethyl Aniline or Dimethyl Safranine Azo Dimethyl Aniline, C. I. Nos. 11045, 11050), or the Janus Black R type, also C. I. 11975 (Colour Index, Second Edition, vol. 3, 1956-57), as these compounds make possible the highest leveling and the widest bright plate range.
• the anions of these cat-ionic dyes are in general not important for its maximum activity, though there is evidence for ion pairing and small anions that are not surface-active in wetting are desirable, but surface-active anions such as dodecyl sulfonic are not desirable and tend to precipitate the phenazine dyes.
• a preliminary copper or brass strike from a cyanide bath or a nickel strike from an acidic, pH of about 0.5 to 5, nickel plating bath is first used to avoid poorly adherent immersion deposits.
• the acidic nickel strike (low chloride, high sulfate type to minimize drag-in of chloride ions into the copper bath) is often preferred because it is easier to control and easier to rinse and easier for waste disposal.
• the inorganic composition of the acid copper plating baths such as the acidic sulfate or acidic fluoborate may vary over rather wide limits, an actually much lower acid content may be used with the unique combination of additives of this invention than is present in the usual standard compositions. However, when very low acid contents are used, higher tank voltages are needed.
• the standard types of acidic copper sulfate and fluoborate baths are used for the inorganic compositions.
• inorganic cations which do not plate out from the normal acidic copper plating baths, may be present in concentrations as high .as at least 25 grams/liter with out detrimental eifects, for example, ferrous, nickel, cobalt, zinc and cadmium cations.
• Chloride and/or bromide anions should in general be kept below about 0.1 gram/liter, and preferably below about 0.02 gram/liter.
• Air agitation or cathode-rod agitation, or solution agitation and cathode-rod agitation is desirable for highest speed plating and optimum results.
• the best bath temperatures are 25-30 C., though lower or higher (even up to 50 C. in some cases) temperatures can be used.
• the various organic sulfide sulfon-ic compounds may have various substituting groups such as methyl, chloro, bromo, methoxy, ethoxy, car-boxy and hyd oxy on the molecules especially on the aromatic and heterocyclic sulfide sulfonic acids without iundamental changes in brightness.
• the organic sulfide sulfonic acids of Table I can be added to the baths as the free acids, or the alkali metal salts, or the organic amine salts such as the triethanolamine, guanidine, aminoguanidine, phenylguanidine, ethylene diamine and pyridine salts. In most cases it is preferred to use the free acids.
• Baths A and B do not give as bright plate as the rest of the baths which employ combinations of addition agents.
• the highest brilliance, widest bright plate range, and best leveling is obtained with the baths using Janus Green as one of the brighteners.
• cathode current density amp3/ q 1 H 50 30-75 1,3-dioxolane polymer, av. mol. wt. 5,000 0.03-0.15 30
• ExampleF Temp. -35 C. glrlgrergt/rfigon, Average cathode Cu n y, 5 P CuSO 5H O ISO-250
• Example B 2 4 -75 Concentration, Polypropylene glycol, av. mol. Wt. 350-750 0.05-0.2 rams/liter Thianthrene sulfonic acid 0.001-0.02 Cu(BF I O-42 Dim hyl safranine azo dimethyl aniline 0 0 1 0 1 6 8'38 Tem 20-35 0.
• Example 3 Table I 0.0010.02 cuso,.sH o 2 Temp. 25-30 0. H25 A p p 1,3-dioxolane polymer, av. mol. Wt. 5,000 0.05-0.15 cathode current 1611810, 5 P q- Thianthrene sulfonic acid (Example 4, Example 1 Table 5 Concentration, Temp. 20-35 C. grams/liter Av, cathode current density, 5 amps/sq. dm. E; 150-425 HBF 10-30
• Example 12 Table II 0.02-0.3 grams/liter 50425 Example T ble I (1001-01)]. CHEF; Janus Black R 0 001-4) 01 10-30 H BO 0-30 Temp. 25-30 C.
• 1,3-dioxolane polymer av. mol. wt. 5,000 0.1-0.3
• Av. cathode current density 5-10 amps/sq. dm.
• Example I Concentration, grams/liter CUSO4-SH2O H 80 3060 Polypropylene glycol, av. mol. wt. 300-750 0.01-0.2 Janus Green B 0.001-0.02
• the addition agents of Tables I and II can be combined in the same molecule or combined with one of the phenazine dyes, or they may be used as individual molecules as listed in Tables I and II mixed together in the sa ine solution with or without the phenazine dyes because they all deplete from the solution at very nearly the same rate.
• the compounds of Table I used in the very low concentrations of 0.0005 to about 0.025 gram/liter deplete practically exactly at the same rate as the phenazine dyes used in the concentration range of 0.001 to 0.05 gram/liter.
• the rate of depletion of the unique combiantion of additives of this invention is very closely the same in the acidic copper sulfate, copper fluoborate and copper methane sulfonate baths which are the preferred baths.
• the solubility of the cop-per salts of these compounds are much smaller than, for example, the copper methane, ethane or propane monosulfonates, and it is therefore necessary to use the d-isulfonates in much lower concentrations than the monosulfonates.
• phosp-horized copper anodes especially when the additives in the acidic baths consist of combination of compounds selected from Tables I and II.
• pure copper anodes such as electrolytic copper or oxygen-free copper anodes
• the anode corrosion is less smooth and also the brightness of the plate is less. Just why the plate is less bright is not clear.
• the phosphorized anodes contain from about 0.02 to about 0.2% phosphorous and the cathode copper plate obtained with the use of these phosphorized anodes also contains a very similar percent phosphorous, and it is the inclusion of this phosphorous in the plate that may aid in the brightening.
• the phosphorized copper anodes usually contain about 0.01 to 0.05% silver and smaller traces of nickel, iron, sulfur, arsenic, antimony, and bismuth.
• the cathode plate contains even less of these impurities. The silver seems to be precipitated out as the chloride, which probably explains its very much smaller concentration in the cathode plate.
• the copper plate is about equally brilliant, independent of the type of the above-mentioned copper anodes used in the plating.
• a bath for electrodepositing ductile, lustrous copper comprising an aqueous acidic copper plating bath containing dissolved therein about 0.0005 to about 0.04 gram per liter of an organic sulfide compound carrying at least one sulfonic group, together with 0.01 to 5 grams/liter of a bath-soluble polyether compound containing at least 6 ether oxygen atoms and being free from alkyl chains having more than 6 carbon atoms.
• a bath as claimed in claim 1 wherein said polyether is a polymer of 1,3-dioxolane having a molecular weight in the range of 296 to at least 30,000.
• a bath as claimed in claim 5 wherein said phenazine dye is diethyl safranine azo dimethyl aniline.
• said acid copper plating bath contains at least one copper salt selected from the group consisting of copper sulfate, copper fluoborate, copper methane sulfonates, copper methane disulfonates, copper ethane sulfonates, copper ethane disulfonates, copper propane sulfonates and copper propane d-isulfonates.
• a method for electrodepositing ductile lustrous copper comprising the step of electrodepositing copper from an aqueous acidic copper plating bath containing dissolved therein about 0.0005 to about 0.04 gram/liter of an organic sulfide compound carrying at least one sulfonic group, together with 0.01 to 5 grams per liter of a bath-soluble polyether compound containing at least 6 ether oxygen atoms and being free from alkyl chains having more than 6 carbon atoms.
• said polyether in the said acidic copper baths is a polymer of 1,3-dioxolane having a molecular weight in the range of 296 to at least 30,000.
• said polyether in the said acidic copper baths contains the group (C H.;OC H O--) where x is an integer of magnitude of at least 3.
• a method as claimed in claim 14 wherein said phenazine dye is diethyl safranine azo dimethyl aniline.
• a method as claimed in claim 14 wherein said phenazine dye is dimethyl safranine azo dimethyl aniline.
• said acid copper plating bath contains at least one copper salt selected from the class consisting of copper sulfate, copper fluoborate, copper methane sulfonates, copper methane disulfonates, copper ethane sulfonates, copper ethane disulfonates, copper propane sulfonates and copper propane disulfonates.

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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)
• Polymers With Sulfur, Phosphorus Or Metals In The Main Chain (AREA)

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• 0
  • NL NL291575D patent/NL291575A/xx unknown
• 1962
  • 1962-04-16 US US187926A patent/US3267010A/en not_active Expired - Lifetime
• 1963
  • 1963-04-09 SE SE3974/63A patent/SE301576B/xx unknown
  • 1963-04-11 GB GB14632/63A patent/GB1034484A/en not_active Expired
  • 1963-04-16 FR FR931603A patent/FR1361558A/fr not_active Expired
  • 1963-04-16 DE DE19631521062 patent/DE1521062B2/de not_active Ceased

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