PL152931B2 - Electrolytic copper bath with sheen - Google Patents

Description

PATENT DESCRIPTION

THE REPUBLIC OF POLAND

PATENT OFFICE OF THE RP

Additional patent to patent no. ----- Pending: 89 02 09 (P. 277650)

Priority ---- Application announced: 89 11 13

Patent description published: 1991 12 31

152 931

Int. Cl. C2SD 3/38

HlTtllll ntdlH

Inventor of the invention: Stanisław Szczepaniak

The holder of the patent: Szczepaniak Stanisław, Kielce (Poland)

BATH 00 ELECTROLYTIC COPPER GLOSSY

The present invention relates to an alkaline electrolytic copper plating bath with a gloss. The bath is designed to apply shiny and plastic copper coatings directly on steel and cast iron details without the need to use toxic cyanides or nickel sublayers.

The electrolytic application of copper coatings in a one-step process directly on steel or cast iron workpieces is so far known from several types of baths, mainly cyanide, pyrophosphate, phosphonium and edetate.

In electroplating, cyanide baths containing cuprous cyanide, alkali metal cyanide, alkali metal hydroxide and brighteners are the most commonly used. Due to the large amount of highly toxic cyanides contained in these baths, their washings or used baths cannot be poured into sewage, as this may contaminate the natural environment and biological destruction of living organisms.

The pyrophosphate baths, known from US patent No. 3,704,454 and Polish patent No. 120,200, which are used to obtain shiny copper coatings with a high gloss, have little adhesion to steel.

The following patents: Great Britain No. 1,370,307 and No. 1,419,613, France No. 2,276,395, United States No. 3,475,293 and Polish No. 122,017, 133 515, 117,002 describe copper plating baths containing phosphonium acid salts and edetate compounds known as highly complexing compounds for copper and other metals. The copper coatings obtained from them are smooth and adhere well to the steel substrate. However, the baths themselves are very expensive and troublesome in the treatment of sewage, the neutralization of which requires appropriate technologies and specialized installations as well as expensive reagents.

152 931

152 931

In U.S. Patent No. 4,389,286, glucoheptonates are used to complex copper, tin, and lead. Organic sulfur compounds and trace amounts of zinc, tellurium, bismuth, antimony, indium, gold, silver and other ions were used as leveling and polishing agents. The copper-tin and / or lead alloy coatings deposited from this bath were shiny and well adhered to the steel substrate. The maximum cathodic current density did not exceed 1 A / dm, which in practice excludes its industrial application.

The object of the invention is to provide an alkaline gloss copper bath that would allow copper coatings to be applied to details of complex shape, and the deposited coatings would be shiny, non-porous and well adherent to iron and steel. Readily neutralizable or biodegradable complexing compounds would be cheap and available. This goal was achieved by developing an alkaline bright copper plating bath that contains soluble divalent copper compounds, complexing compounds such as sodium and / or potassium salts of aliphatic hydroxycarboxylic acids, buffering, weak reductive and brightening compounds.

As complexing compounds, sodium and / or potassium salts of aliphatic hydroxycarboxylic acids such as citric, gluconic, glucoheptonic, malic, tartronic and tartaric acids can be used individually or in combination. The buffering compounds can be borates, phosphates, pyrophosphates, aliphatic and / or aromatic alkanolamines, and others.

The essence of the invention consists in the fact that the bath contains: 0.5-60 g / dm3 of inorganic compounds of tetravalent sulfur, 0.001-10 g / dm3 of heterocyclic compounds having at least one nitrogen atom and / or their oligomers obtained by reaction with epihalohydrin in the ratio molar 2: 1 to 1: 2 and 0.001 - 5 g / dm3 of soluble divalent metal compounds such as zinc and / or tin and / or nickel and / or cobalt and / or cadmium and / or lead.

As inorganic tetravalent sulfur compounds, soluble alkali metal salts of sulfurous and / or metabisulfuric acid can be used. It is preferable to add sodium salts such as sodium sulfite, sodium bisulfite, sodium metabisulfite, sodium bisulfite. Sulfites and / or metabisulfites are added to the bath to facilitate the cathodic reduction of divalent copper ions to metallic. Moreover, the sulphites and / or metabisulphites have a positive effect on the grain refinement of the deposited copper, lightening the coating, especially in the low current densities range.

The heterocyclic compounds used according to the invention that have a beneficial effect on the operation of the copper bath include: pyrrole, pyrrolidine, pyridine, piperidine, piperazine, pyrazine, pyridazine, pyrimidine, quinoline, isoquinoline, indole, imidazole, triazine, oxazole, isoxazole, 1, morpholino 2,4-triazole and their derivatives.

As epihalohydrin it is preferred to use: 1-chloro-2,3-epoxypropane, 1-fluoro-2,3-epoxypropane, 1-bromo-2,3-epoxypropane, 1-iodo-2,3-epoxypropane, 1-chloro- 2,3-epoxybutane, 1-chloro-2,3-epoxypentane, 1-chloro-3,4-epoxypentane.

The bath according to the invention can be operated in rotary and stationary devices in the temperature range from 290 to 350 K, preferably 320 to 340 K, with or without agitation, continuous or batch filtration. The amount of copper in the bath is not decisive and may vary from 5-30 g / dm \ preferably for rotary devices 8-12 g / dm \ and for stationary devices from 12 - 20 g / dm \ Concentrations of hydroxyl acids can be from 50-200 g / dm \ preferably 80 - 120 g / dm \ The anodes should be suspended in anode bags, and their ratio to the cathode must be at least 2: 1, the pH of the bath is greater than 7, preferably 8.8 - 9.5. Bath neutralization is cheap, simple and effective, and it is carried out with inorganic calcium and iron compounds.

The subject matter of the invention is elucidated in the following examples.

Example I.

Copper sulphate CuSO * 5 H ₂ o ....................................... 45g / dm ^

Citric acid ^ ΗθΟ? HjO ............................................ 110g / dm ^

Sodium hydroxide NaOH ............................................... 75q / dm ^

152 931

Sodium tetraborate Na ^^ O? - 10 H? 0 .................................. 30g / dm

Sodium sulphite Na ₂ S0 ^ · 7 Η? 0 ....................................... 40g / dm

Product of the reaction of pyrrole with 1-chloro-2,3-epoxypropane in a molar ratio of 1: 1 ............................... .............. 0.3 g / dm

Imidazole ........... 1.2 g / dm

Lead acetate ................ 0.02 g / dm

The bath was tested in a Hull cell using an M1-E grade electrolytic copper anode and a degreased and etched steel plate. During the electrolysis, a current of 0.5 A flowed for 1500 seconds, and the bath was stirred with a magnetic stirrer. Bath temperature 320 K and pH = 9.0. As a result of electrolysis, a coating was obtained which adhered well to the steel substrate, shiny in the range of 0 - 2.5 A / dm, while above this density the coating was burnt and not very adhesive.

Example II.

Copper sulphate CuSO * 5 HjO ..................................... 35g / dm

Sodium Gluconate CjH ^^ O ^ COONa ................ 60g / dm

Potassium citrate .......................................... 60 g / dm ³

Sodium tetraborate NajB ^ O? 10 Η? 0 ....... 35g / dm

Sodium metabisulfite Na ₂ S ₂ 0 ^ .......................................... 30g / dm

Sodium carbonate Na ₂ C0 _} · 10 Η? 0 ....................................... .15g / dm

Product of the reaction of piperazine with l-chloro-2,3-epoxypropane in a molar ratio of 1: 1 ............................... ........... 0.2 g / dm

Cobalt sulphate CoSO * 7 Η? 0 ..................................... 0.1g / dm

The bath was tested in a Hull cell under the same conditions as in Example I.

As a result of electrolysis, a plastic and well-adherent copper coating 2 was obtained, which was shiny in the range of 0 - 1.5 A / dm 2 and semi-glossy in the range of 1.5-2.5 A / dm ² .

Example III.

Basic cupric carbonate CuCOj · Cu (0H) ₂ ............................ 30 g / dm ³

Citric acid C ^ HgO? HjO .......................................... 00 g / dm ³

Potassium tartrate C ^ H ^ O ^ Kj · 1/2 H ₂ 0 .................................. .25 g / dm ³

Potassium hydroxide KOH ............................................ 55 g / dm ³

Sodium metabisulfite Na ^ jO ^ .......................................... 25 g / dm ³

Sodium tetraborate Na ^^ O? 10 H ₂ 0 .................................. 35 g / dm ³

Reaction product of imidazole with 1-chloro-2,3-epoxypropane in a molar ratio of 2: 3 ............................... .............. 0.5 g / dm ³

3-Benzolyl-1,2,4-triazole ....................................... ..... 0.1 g / dm ³

Lead carbonate ................................................ ........ 0.01 g / dm ³

Stannous sulfate ................................................ ...... 0.05 g / dm ³

The bath was tested in a Hull cell where the anode was an electrolytic copper plate and the cathode was a steel plate. A current of 1 A was passed through the cell for 900 s while agitating with compressed air. Bath temperature 330 K, pH - 9.2. As a result of electrolysis, a plastic, non-porous and well-adherent coating was obtained. The obtained copper coatings were shiny in the range of 0.1 - 1.8 A / dm 2 and semi-glossy in the range of 1.8 - 2.6 A / dm ² .

The electrolytic copper plating bath according to the invention can be operated industrially in rotary and stationary devices. Bath components must be replenished based on periodic laboratory analyzes and tests. The basic and polishing ingredients can be added individually or in a set.

152 931

Claims (1)

Patent claim Electrolytic copper plating bath consisting of soluble divalent copper compounds, sodium and / or potassium salts of aliphatic hydroxycarboxylic acids and buffering compounds, characterized in that it contains 0.5 - 60 g / dm3 of inorganic compounds of tetravalent sulfur, 0.001 - 10 g / dm 'of heterocyclic compounds having at least one nitrogen atom and / or their oligomers obtained by reaction with epihalohydrin in a molar ratio of 2: 1 to 1: 2 and 0.001 - 5 g / dm3 of soluble divalent metal compounds such as zinc and / or tin and / or nickel and / or cobalt and / or cadmium and / or lead. UF RP Publishing House. Mintage 100 Price: PLN 3,000