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 an electroplating process and the bath for the process. It more particularly relates to a process for obtaining bright, smooth electroplates of copper involving the addition of alkyl and aryl derivatives of thiourea to the copperplating bath.
• a further object is to provide a new smoothing agent for electroplating baths.
• Another object is to provide a process for the electrodeposition of metals wherein the surface of the deposited metal is free from irregularities of the rough base metal on which the electrodeposit is made.
• a further object is to provide a process for obtaining smooth, bright copper electrodeposits by adding alkyl and aryl derivatives of thiourea to a bright copper plating bath.
• thiourea derivatives which contain one or more alkyl or aryl radicals in the molecule produce a particularly good smoothing effect, if they are used in copper-electroplating baths together with certain groups of high quality brightening agents and, if desired, together with additional bath additives, such as additives for increasing ductility, wetting agents, and other such additives.
• such thiourea derivatives are used in copper-electroplating baths together with those high quality brightening agents which are characterized by one or more carbon atoms linked only to heteroatoms, the carbon atoms in turn being linked through a sulfur atom to a short aliphatic radical which carries a sulfonic acid group or another water-solubilizing group.
• high quality brightening agents are the water-soluble salts of N,N-dimethyl-dithiocarbamic acid-n-propylester-w-sulfonic acid, N,N- diethyl-dithiocarbamic acidethylester-w-sulfonic acid, N,N pentamethylene dithiocarbamic acid n propylester-w-sulfonic acid, N,N-diethylamino-dithiocarbamic acid S propanediol-2,3,N butyl dithiocarbamic acid-N,S-bis-propane-w-su1fonic acid, dithiocarbamic acid-S-methylester-N-ethyl-N-butyl-w-sulfonic acid, 1,3,5- triazine 2,4,6 trimercapto 2 hydroxypropane sulfonic acid, 1,3,5-triazine2,4,-trimercaptoethane-sulfonic acid
• alkyl or aryl radicals in the thiourea derivatives may be attached to the nitrogen atom as Well as to the wherein R R R and R are selected from the group consisting of hydrogen, alkyl, aryl, aralkyl, cycloalkyl, hydroxyalkyl, hydroxyaryl, and hydroxy alkoxyalkyl radicals, at least one of the R through R, not being hydrogen.
• thiourea derivatives are the following: Naryl-N'-alkyl-thiourea, N-aralkyl-N'-a1kylthiourea, N-cycloalkyl-N'-alkyl-thiourea, Nalky1-N'- alkyl-thiourea, as well as S-alkyl-thiourea or their 7N- alkyl-substitution products.
• the alkyl radicals are primarily short-chain radicals with a maximum of about six carbon atoms.
• oxygen-containing alkylthiourea derivatives are the following: N-phenyl-N-oxethyl-thiourea, N-cyclohexyl-N'-oxethyl-thiourea, N-alkyl N-hydroXymethyl-thiourea, N-alkyl-N'-oxethyl-thiourea, N-phenyl -N- oxethyl-thiourea, N-phenyl -N'- hydroxypropyl-thiourea, N-phenyl-N-fl-(hydroxyethoxy)-ethylthiourea, N-benzyl-N'-hydroxyethyl-thiourea, N-4-hydroxyphenyl-N-hydroxyethyl-thiourea, and the like.
• the simultaneous use of the thiourea derivatives with the above-described high quality brightening agents may also be applied especially in the process for direct electroplating of non-precious metals, in accordance with French Patent No. 1,127,418.
• firmly adhering copper-electroplates may be applied to non-precious metals, such as iron, without a preliminary cyanide copperplate by pretreating the metal objects to be copper-plated in an acid pickling bath containing inhibitors having a high inhibiting effect, and thereafter immediately and without intermediate rinsing copper-plating the object in an acid copper-plating bath.
• Effective agents for increasing the ductility which meet these requirements are amino compounds, such as LB-propylenediamine, 1,3-bis-(diethylamino)-propanol-2, N,N,N,N- tetrabutyl 1,3 diaminopropanol 2, N,N,N,N' tetraethyl-l,3-diaminopropanol-2, or other sulfonic acid or sulfuric acid ester derivatives which contain one or more sulfonic acid groups or sulfuric acid ester groups.
• amino compounds such as LB-propylenediamine, 1,3-bis-(diethylamino)-propanol-2, N,N,N,N- tetrabutyl 1,3 diaminopropanol 2, N,N,N,N' tetraethyl-l,3-diaminopropanol-2, or other sulfonic acid or sulfuric acid ester derivatives which contain
• Additional agents for increasing the ductility include halogen-containing tertiary amino compounds free from carboxyl groups, such as 2-diethylarnino-ethylchlorided, 3 diethylamino 1 chloro propanol 2, 1 dioxethylamino-3-chloro-propanol-2, or the quaternary rearrangement products formed from these compounds which contain the halogen in ionogenic linkage.
• halogen-containing tertiary amino compounds free from carboxyl groups such as 2-diethylarnino-ethylchlorided, 3 diethylamino 1 chloro propanol 2, 1 dioxethylamino-3-chloro-propanol-2, or the quaternary rearrangement products formed from these compounds which contain the halogen in ionogenic linkage.
• Such compounds are described in German Patent No. 934,508 as well as in Belgian Patent No. 540,855.
• the combination according to the present invention is to be used primarily in acid copper-electroplating baths.
• the thiourea derivatives are used in quantities of about 0.005 to 2:0 gm./1iter of bath liquid. Otherwise, the baths are operated under the same concentration, temperature and current density conditions described in the above-mentioned patents.
• thiourea and certain thiourea derivatives have been proposed as brightening agents for electroplating baths, especially for copper-electroplating baths. These agents exhibit only moderate brightening effects in comparison with the brightening agents used in accordance with the invention, so that there Was no reason to use them as additional agents for improving the brightness.
• the claimed thiourea derivatives in combination with the claimed high quality brightening agents produce an entirely different efiect; namely, that they are especially effective smoothing agents. It produces a very substantial improvement of the baths which contain these high quality brightening agents.
• Example I An acid copper-plating bath which contained 180 gm./liter CUSO4.5H20, 60 gm./liter concentrated sulfuric acid and, as a brightening agent, 1 gm./liter N,N- diethyl dithiocarbamic acid ethylester w sodium sulfonate, as well as 0.8 gm./liter N,N,N,N-tetrabutyl- 1,3-diaminopropanol-2 was modified with 0:01 gm./liter N,N'-diethylthiourea. When unpolished brass strips were electroplated within a current density range from 1 to 6 amp./dm.
• Example 11 The acid copper bath of Example I was modified by dissolving therein 0.25 gm./ liter N,N-diethyl-dithiocarbamic acid propylester-w-sodium sulfonate as a brightening agent, and 2 gm./ liter of the quaternary rearrangement product of 3-diethyl-amino-1-ch1oro-propanol-2 and 0.005 to 0.01 gm./liter N-phenyl-N-oXethyl-thiourea as smoothing agents. Metal objects electroplated in this bath were provided with a full bright copper-electroplate which smoothed out the unevenness of the metal base.
• Example III The copper bath of Example I was modified by dissolving therein 1.2 gm./ liter 1,3,5-tIiazine 2,4,6-trimercapto- Z-hydroxypropane-sodium sulfonate, 0.8 gm./liter N,N, N,N' tetra n butyl 1,3 diaminopropanol 2, 0.02
• N,N-diethyl-dithiocarbamic acid-ethylester-wsodium sulfonate 2 gin/liter of an ethoxylated and partially sulfonated fatty alcohol as. wetting agents, and
• a process for producing a smooth, bright copper electroplate on a rough surface metal base from acidic copper plating baths containing a sulfonic acid brightening agent having a carbon atom linked exclusively to heteroatoms, said carbon atom being further linked through a sulfur atom to a lower aliphatic chain which carries the sulfonic radical which comprises adding to said bath a derivative of thiourea as a smoothing agent of the formula wherein R R R and R are selected from the group consisting of hydrogen, alkyl, aryl, aralkyl, cycloalkyl, hydroxyalkyl, hydroxyaryl, and hydroxyalkoxyalkyl radicals, at least one of R through R not being hydrogen, said smoothing agent being added in suflicient amount to efiect said smoothing of the copper plate.
• a process for producing a smooth bright copper electroplate on a rough surface metal base from acidic copperplating baths containing a brightening agent having a carbon atom linked exclustively to heteroatoms, said carbon atom being further linked through a sulfur atom to a lower aliphatic chain which carries a Water solubilizing radical which comprises adding to said bath a derivative of thiourea as a smoothing agent of the formula wherein R R R and R are selected from the group consisting of hydrogen, alkyl, aryl, aralkyl, cycloalkyl, hydroxy-alkyl, hydroxyaryl, and hydroxyalkoxyalkyl radicals, at least one of R through R, not being hydrogen, said smoothing agent being added in sufficient amount to effect said smoothing of the copper plate.
• An acidic copper electroplating bath for producing smooth, bright electrodeposits of copper on a rough surface metal base comprising an aqueous solution of an inorganic salt of copper, a sulfonic acid brightening agent having a carbon atom linked exclusively to heteroatoms, said carbon atom being further linked through a sulfur atom to a lower aliphatic chain which carries the s'ulfonic radical, and a derivative of thiourea as a smoothing agent of the formula.
• R R R and R are selected from the group consisting of hydrogen, alkyl, aryl, aralkyl, cycloalkyl, hydroxyalkyl, hydroxyaryl, and hydroxy alkoxyalkyl radicals, at least one of R through R, not being hydrogen, said smoothing agent being present in sufiicient amount to effect said smoothing of the electrodeposit.
• An acidic copper electroplating bath for producing smooth, bright electrodeposits of copper on a rough surface metal base comprising an aqueous solution of an inorganic salt of copper, a brightening agent having a carbon atom linked exclusively to heteroatoms, said carbon atom being further linked through a sulfur atom to a lower aliphatic chain which carries a water solubilizing radical, and a derivative of thiourea as a smoothing agent of the formula

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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)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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Cited By (16)

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Citations (4)

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• 0
  • BE BE565994D patent/BE565994A/xx unknown
• 1957
  • 1957-04-16 DE DED25419A patent/DE1214069B/de active Pending
• 1958
  • 1958-03-21 CH CH5734458A patent/CH368680A/de unknown
  • 1958-04-10 FR FR762787A patent/FR1248421A/fr not_active Expired
  • 1958-04-14 US US728033A patent/US3000800A/en not_active Expired - Lifetime
  • 1958-04-15 GB GB11888/58A patent/GB884036A/en not_active Expired

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