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 acid baths for producing brilliant copper levelling coatings.
• the present invention relates to a class of substances which produce in acid copper-plating baths capable of imparting to articles treated therein a brilliant finish but no levelling or smoothing effect, a surprising smoothing or levelling action Without affecting the originally obtained, uniform brilliant finish and without unfavorably influencing penetration in depth of the bath.
• the smoothing effect is so pronounced that grinding marks com pletely disappear after deposition of a copper coating of a thicknses of 26 1. only.
• Such an effect is not attained in any of the known sulfuric acid bright copper-plating baths. They require a thickness of the copper coating of at least 42a in order to completely cover and eliminate, i.e. to level the microscopic cracks obtained on grinding the surface to be copper plated.
• an acid bath for the preparation of highly brilliant, smoothing or levelling copper coatings is provided which bath is characterized by the feature that it combines the use of basic brightening agents having in their molecule at least one group of the formula wherein X represents a member selected .firom the group consisting of the hydroxyl group, the carboxyl group, the sulfonic acid group, and a canboxylic acid ester group, While 11 is an integer between 1 and 10,
• the present invention consists in using primary condensation products of thiourea with aliphatic aldehydes, tor instance, with formaldehyde.
• Such derivatives of thiourea have a considerably greater smo oth-ing or levelling effect than the known thiourea compound heretofore used for this purpose.
• the temperature at which they are prepared should not be too high since there is otherwise the danger that insoluble resins will be produced.
• the optimum temperature conditions for the preparation of the thiourea condensation products are between about C. and about C. Depending on the exact temperainure, reaction time, and catalysts employed, the following addition pnoducts can be obtained:
• Such primary brighteners may be any of the above mentioned compounds containing one or more groups of the formula NS-(CH2)DX 1 'wherein X indicates a member selected from the group consisting of the hydroxyl group, the carboxyl group, the sulfonic acid group, and :a carboxylic acid ester group, while n is an integer from 1 to 10.
• Preferred brightening agents of this type are dithiocarbarnic acid derivatives of the formula R and R indicate hydrogen, aliphatic, or aromatic residues,
• n indicates an integer from 1 to 10
• X indicates a member selected from the group consisting of the hydroxyl group, the carboxyl group, the sulionic acid group, and a carboxylic acid ester group.
• Especially suitable brighteners of this type are, furthermore, heterocyclic nitrogen compounds such as compounds of the pyridine, pyrimidine, triazine, tetrazine, pyrazole, imidazole, triazole, pyIr-o-le, quinoline, cinnoline (5,6- benzopyridazine) series and the like in which one or more hydrogen atoms linked to carbon atoms are substituted by the radical wherein X represents the hydroxyl group, the carboxyl group, or another water soluble group of a different anionic character.
• a group S-(CH ),,X need not necessarily occupy an end position in an aliphatic side chain.
• Compounds of the following formulas are especially suitable examples of this group of primary brighteners:
• Example 1 (a) A sheet of iron or steel is ground to a zero polish and is then copper plated in a bath of the following oompos-ition (in g. per liter):
• Example 2 (a) A brass sheet previously polished on :a. zero number grinding wheel is treated at 4 amp/sq. dm. and at 20 C. for 30 minutes in a bath containing per liter:
• the resulting coating is :bright, but no level-ling or smoothing eifect is observed.
• condensation products are characterized by containing not only thiourea moieties bridged by methylene moieties but also diamine moieties bridged by methylene moieties. Thereby, chain structures or two to three dimensionally cross-linked structures are obtained.
• the simplest condensation products of this type correspond approximately to the following formula C Hzwherein To prepare these condensation products, the required amounts of thiourea, polyamine, and formaldehyde are condensed at a temperature of about 110-130" C.
• the molar ratio bet een the thiourea and the compound containing at least two amino groups, for instance, melamine has an optimum value of 1:1, but other ratios may be employed, for instance, a ratio of 1:2.
• the aggressive action of the thiourea by such a cocondensation with a polyamine is considerably mitigated and its inhibitory effect is favorably adjusted for the purpose in view.
• melamine other substances containing at least two amino groups can be used as reaction component in such co-condensation reaction, such as diamino azobenzene, diamino diphenylamine, diamino diphenylurea, diamino stilbene, urea, o dianisidine, o-toluidine, phenylene diamines, 2,4'-diamino diphenyl, parafuchsin, congo red, benzidine, guanidine, benzidine-2,2'-disulfonic acid, diarnino stilbene disulfonic acid, 1,5-diamin0 naphthalene-3,7-disulfonic acid, naphthalene diamines, homologues and derivatives thereof, and the like polyarnino compounds.
• diamino azobenzene diamino diphenylamine
• diamino diphenylurea diamino stilbene
• urea o dianis
• Example 3 A bath of the following composition in g. per liter is used for copper plating:
• Copper plating is effected with a current density of 1-6 amp/sq. dm. at 15-35 C.
• Bright copper coatings of a thickness of 26 of sufiicient brilliancy and good levelling properties are obtained wherein the marks of a No. 0 grinding wheel are completely eliminated.
• Example 4 A copperplating bath of the following composition in g. per liter is used:
• Copper plating is efiected at current densities between 1-6 amp/sq. dm. and at a temperature range between C. and 40 C. Brilliant, effectively levelling copper coatings are obtained thereby.
• the temperature must be kept at C. or, preferably, lower when operating at a current density range between 2.5 amp./ sq. dm. and 6.0 amp./ sq. dm. At higher temperatures, such as between 25 C. and 40 C. the copper coatings are dull and no smoothing effect is observed.
• heterocyclic compounds with nitrogen as hetero atom in their nucleus than pyrazine-3,6-dithi oglycolic acid, 3,6-dirnercapto-fi-hydroxy propyl pyrazine may also be used as brightening agents.
• Such brightening agents are known to the art and their use in copper plating processes are known to the art.
• the thiourea-formaldehyde condensation products used in Examples 1 and 2 as well as the thiourea-formaldehydepolyamine condensation products used in examples 3 and 4 may be replaced by other condensation products wherein other aldehydes are employed than formaldehyde.
• the conditions of preparation of such condensation products must be such that the products are sufficiently soluble in the copper plating bath.
• addition of thiourea-aldehyde condensation products or thiourea-aldehyde-polyamine condensation products to copper plating baths has a number of advantages and more particularly permits to produce perfectly smooth and levelled copper surfaces in a thickness of about 26a only. In addition thereto it was found that polishing of the precipitated thin copper coating is not required. As a result thereof it is possible to continuously subject suitable sheet material and the like articles to copper plating according to the present invention and immediately thereafter to nickel plate such copper plated sheets and the like articles without any intermediate treatment.
• the copper plating baths according to the present invention permit operation with a current density of 6 -amp./ sq. dm. or even more while heretofore current densities of 4 amp./ sq. dm. usually could not be exceeded.
• the amounts of the thiourea-aldehyde condensation products or of thiourea-aldehyde-polyamine condensation products to be added to the copper plating bath may, of course, vary depending upon the composition of the bath and the composition of the smoothing and levelingagent. Amounts between about 0.001 g./l. and about 0.5 g./ l. have proved satisfactory. The preferred amounts are between about 0.01 g./l. and about 0.04 g./l.
• the brightening agents i.e. the dith-i'ocarbamic acid compounds and similar heterocyclic compounds are added as is known, in amounts between about 0.01 g./l. and about 0.5 g./l. although they are not "limited to such amounts.
• wetting agents compatible with the copperpl-ating bath.
• wetting agents based on ethylene oxide i.e. polyglycol compounds and the like.
• Sulfonated wetting agents have proved of advantage due to their increased solubility in water.
• non-ionogenic wetting agents such as wetting agents with ether bridge bonds have proved to be useful additives.
• the electroprecipitation conditions such as current density, temperature, and duration, and the like may be made by those skilled in the ant in accordance with the principles set forth herein and in the claims annexed hereto.
• An acid copper plating bath for producing smooth and levelled copper coatings of high brilliancy said bath containing, as brightening agent, a basic brightening agent selected from the group consisting of dithiocarbamic acid compounds of the formula wherein R and R are members selected from the group consist ing of hydrogen, aliphatic, and aromatic residues,
• X is a member selected from the group consisting of the hydroxyl group, the carboxyl group, the sulfonic acid group, and the carboxylic acid ester group, and
• n is an integer between 1 and 10
• heterocyclic nitrogen-containing compounds at least one of the carbon-linked hydrogen atoms of said heterocyclic compounds being substituted by the group, X and n in said group representing the same members and numbers as indicated above, and between about 0.001 g./l. and about 0.5 g./l. of a levelling agent consisting of an acid-soluble condensation product of thiourea, an aliphatic aldehyde component consisting of formaldehyde, and a compound having at least two amino groups in its molecule.
• a levelling agent consisting of an acid-soluble condensation product of thiourea, an aliphatic aldehyde component consisting of formaldehyde, and a compound having at least two amino groups in its molecule.
• An acid copper plating bath for producing smooth and levelled copper coatings of high brilliancy said bath containing per liter about 2-10 g. of copper sulfate CuSO .5H O,
• An acid copper plating bath for producing smooth and levelled copper coatings of high brilliancy said bath containing per liter about 210 g. of copper sulfate CuSO .5H O,
• An acid copper plating bath for producing smooth and levelled copper coatings of high brilliancy said bath containing per liter 5.
• An acid copper plating bath for producing smooth and levelled copper coatings of high brilliancy said bath containing per liter about 200 g. pf copper sulfate CuSO .5H O,
• An acid copper plating bath for producing smooth and levelled copper coatings. of high brilliancy, said bath containing, as brightening agent, a basic brightening agent having at least one group of the formula in its molecule, X in said group indicating a member selected from the group consisting of the hydroxyl group, the carboxyl group, and a Water soluble group of different anionic character, and 12 indicating a whole number between 1 and 10, and "between about 0.001 g./l. and about 0.5 g./l. of a levelling agent consisting of an acidsoluble condensation product of thiourea and an aliphatic aldehyde component consisting of formaldehyde.
• a levelling agent consisting of an acidsoluble condensation product of thiourea and an aliphatic aldehyde component consisting of formaldehyde.

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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)
• Phenolic Resins Or Amino Resins (AREA)
• Manufacturing Of Printed Wiring (AREA)

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Cited By (14)

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• 1957
  • 1957-03-16 DE DER20796A patent/DE1152863B/de active Pending
  • 1957-08-28 FR FR1181721D patent/FR1181721A/fr not_active Expired
  • 1957-09-03 GB GB27741/57A patent/GB873753A/en not_active Expired
• 1958
  • 1958-03-12 US US720824A patent/US3101305A/en not_active Expired - Lifetime

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