RU2385366C1 - Electrolyte for copper coating steel pads - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: electrolyte consists of bluestone 105-115 g, ammonium sulphate 220-230 g, polyethylene-polyamine 3-6 g, water solution of ammonia 89-95 ml, bromine-benzo-thyazo 1-3 mmole/l, captax 1-3 mmole/l and water to 1 l.

EFFECT: cathode sediments have fine crystal structure, are smooth, plain, uniform, mirror-bright, well adherent to base and with maximal current output.

3 tbl, 3 ex

Description

The invention relates to the field of electroplating, in particular to the electrolytic deposition of a copper coating on steel without the use of an intermediate sublayer, and may find application in engineering industries where it is important to obtain plastic copper coatings with minimal hydrogenation of the steel base.

Known ammonia copper plating electrolytes [1-4] with polyethylene polyamine, allowing to obtain high-quality galvanic coatings.

Polyethylene polyamines are a mixture of the general formula H ₂ N (CH ₂ CH ₂ NH), where n = 1-5. Dark-colored liquid with a content of N 30-36% [5].

The closest in technical essence and composition of the components is an electrolyte [1], containing copper sulfate, ammonium sulfate, polyethylene polyamine, an aqueous solution of ammonia 25% and decamine. From this electrolyte, high-quality shiny sediments with a fine-crystalline structure are obtained, without pitting, overburden and whisker dendrites without the use of an intermediate sublayer. However, the sediments are porous and do not interfere with the diffusion of hydrogen into the steel base.

The objective of the invention is to obtain a mirror-shiny copper precipitation without the use of an intermediate sublayer, high current efficiency and minimal hydrogenation of the steel base.

The problem is achieved in that an electrolyte containing copper sulfate, ammonium sulfate, an aqueous solution of ammonia 25%, polyethylene polyamine, is additionally injected with a brightener - captax (2-mercaptobenzothiazole), yellow crystals, soluble in benzene, alcohol, ether. Obtained by condensation of aniline with CS ₂ and S in the presence of nitrobenzene [5]:

and hydrogenation inhibitor - bromobenzothiazo- (1- [6-bromobenzothiazol-2-yl) azo] 2-naphthol) dark red crystals are soluble in chloroform, o - xylene [5]:

in the following ratio of components:

Copper sulfate, g 105-115 Ammonium sulfate, g 220-230 Polyethylene polyamine, g 3-6 Aqueous solution of ammonia, ml 89-95 Bromobenzthiazo, mmol / L 1-3 Kaptax, mmol / l 1-3 Water, l up to 1 l

To obtain the inventive electrolyte, three component compositions were prepared:

Table 1 Name of components I maximum Maximum II Secondary III Copper sulfate, g 115 105 110 Ammonium sulfate, g 230 220 225 Polyethylene polyamine, g 6 3 four Aqueous solution of ammonia 25%, ml 95 85 90 Bromobenzthiazo, mmol / L 3 one 2 Kaptax, mmol / l 3 one 2 Water, l one one one

Electrolyte Preparation:

The electrolyte is prepared by dissolving separately at a temperature of 50-60 ° C copper sulfate, ammonium sulfate, polyethylene polyamine; mix solutions. To remove impurities, the electrolyte is worked out at Dk = 1 A / dm ² for 4-6 hours, filtered and 25% aqueous ammonia solution and organic additives are added. All reagents brand analytical grade and h.ch.

Electrolysis mode: temperature 18-25 ° C, current density 1-4 A / dm ² , pH 8.2-8.6.

Steel hydrogenation was determined by the change in ductility of steel wire samples of grade U-10A, with a diameter of 1 mm and a length of 100 mm. Plasticity (N) was determined by the formula:

N = (a / ao) * 100%

where, ao - the number of revolutions before the destruction of the bare wire;

and - the number of revolutions before the destruction of copper-plated wire.

Physicomechanical properties during electrodeposition of copper from ammonia electrolyte were carried out on steel plates 40 × 40 × 2 mm from steel 20, one side of which was insulated with BF glue. Sample preparation consisted of micron-skin polishing, degreasing with Vienna lime, and washing with distilled water.

The cathode potential was measured on a R-375 potentiometer relative to a silver chloride electrode, calculated on a hydrogen scale.

The gloss of copper coatings was measured on an FB-2 photoelectric gloss meter in relative units with respect to uviole glass, the gloss of which is 65 rel. units The range of values 1–10 corresponds to a matte surface, 10–50 corresponds to semi-brilliant, 50–90 to brilliant, 90–100 to a mirror. The current efficiency of copper was determined using a copper coulometer.

The porosity of the coatings was determined according to GOST 9.302-79. The scattering power of the electrolyte was investigated by the method of the far and near cathode.

The adhesion of a copper precipitate to the cathode surface was studied by applying a scratch method and bending wire samples by 180 °. Adhesion was considered good if peeling of the precipitate did not occur. The appearance of the coating and the structure of the precipitate were described using a microscope.

The results of the experimental analysis are presented in tables 2 and 3.

Example 1. Copper electrodeposition was carried out with composition 1 of Table 1 in the presence of a hydrogenation inhibitor, bromobenzthiazo, whose inhibitory effect is 88-100% (Table 2, No. 3).

The high inhibitory effect of this additive is related to its structure, it has five adsorbed centers — nitrogen, sulfur, oxygen atoms, an azo group, and two condensed aromatic rings, π — electrons of which can go to the d — sublevel of metal atoms, and this leads to a more durable chemisorption additives bond with the cathode metal surface.

The cathode potential varies from - 0.243 to - 0.803 V (Table 3, No. 3). Cathode deposits have a fine crystalline structure, a matte and semi-shiny surface. At DK 3 and 4 A / dm ^{2, the} precipitation is coarse-crystalline. Pitting and filamentous dendrites were found on the surface. Partially peeling coating from the base. The porosity of the copper deposit varies from 36 to 5 pores per 1 cm ² with a coating thickness of 1 to 10 μm. The current efficiency is 84-95%. The dissipation capacity of the electrolyte is 38-48%.

Example 2. Electrodeposition of copper was carried out from an electrolyte of composition 1 of table 1 in the presence of a brightener - captax. Indeed, the precipitation is better with a mirror surface, the gloss is 90-100 rel. units (table 3, No. 6). The surface is crystalline, dense, uniform, well adhered to the base. The effectiveness of the brightening and smoothing effect is associated with the presence of adsorption centers - two sulfur atoms, a nitrogen atom and a condensed aromatic ring, all of which determines a stronger bond between the additive and the cathode metal surface. The cathode potential shifts to the region of negative values from -0.334 to -0.862 V (Table 3, No. 6). The porosity of copper deposits varies from 28 to 5 pores per 1 cm ² . Such porous coatings are not a barrier to the diffusion of hydrogen into the steel substrate. The ductility of wire samples is 79-93%, and the current efficiency is 80-92%. The dissipating ability of the electrolyte is 47-57%.

Example 3. Only the joint presence in the studied ammonia electrolyte of the hydrogenation inhibitor bromobenzthiazo and the brightening agent - captax - enhances their effectiveness of the inhibitory and brightening action (Table 2, 3, No. 7). The cathode potential is greatly reduced -0.263-0.873 V. The cathode deposits have a fine-crystalline structure, even, smooth, uniform, mirror-shiny (gloss 72-100%), well adhered to the base. The ductility of steel cathodes is 87-100%, and the maximum current efficiency is 84-94%. The porosity is the smallest from 18 to 2 pores per 1 cm ² with a coating thickness of 1 to 10 microns. The dissipating ability of the electrolyte is 42-54%.

The analysis of examples shows the advantage of the inventive electrolyte in the joint presence of a hydrogenation inhibitor - bromobenzthiazo and a brightener - captax at C = 3 mmol / L.

INFORMATION SOURCES

1. A.S. 459531. C23B 5/18. Copper electrolyte. BI 1976, No. 5.

2. A.S. 427094. C23B 5/18. Copper electrolyte. BI 1974, No. 17.

3. A.S. 1315525. C25D 3/38. Electrolyte copper plating of steel substrates. BI 1987, No. 21.

4. Marienko N.A., Rayber Z.S., Cossack E.N. Application of copper coating from ammonia coating. L., 1961, 22 p.

5. Chemical encyclopedic dictionary. - M .: Owls. encyclopedia. 1983.- S. 410, 323, 83.

table 2 Properties of copper precipitation obtained from the inventive electrolyte No. Electrolyte composition Dk, A / dm ² Ductility,% Current output,% The structure and appearance of the coating The time of deposition, min 5.5 eleven 22 one 2 3 four 5 6 one Copper sulfate, g 105 one 95 93 90 92 Coatings with a matte and semi-shiny surface, fine-crystalline structure, with DK 3 and 4 A / dm ² - coarse-grained. Pitting and filamentous dendrites, partially peeling from the base, were found on the surface. Ammonium sulfate, g 220 2 93 90 88 88 Polyethylene polyamine, g 3 Aqueous solution of ammonia 25%, ml 85 3 90 88 86 85 Bromobenzthiazo, mmol / L one Water, l up to 1 four 86 84 82 80 2 Copper sulfate, g 110 one 99 96 95 94 Ammonium sulfate, g 225 2 97 95 93 90 Polyethylene polyamine, g four Aqueous solution of ammonia 25%, ml 90 3 93 91 88 86 Bromobenzthiazo, mmol / L 2 four 90 88 86 82 Water, l up to 1 3 Copper sulfate, g 115 one one hundred 98 97 95 Ammonium sulfate, g 230 2 98 96 95 91 Polyethylene polyamine, g 6 Aqueous solution of ammonia 25%, ml 95 3 94 93 92 88 Bromobenzthiazo, mmol / L 3 Water, l up to 1 four 92 90 88 84 four Copper sulfate, g 105 one 88 84 82 84 Coatings with a mirror-shiny surface, crystalline, well adhered to the base, dense, uniform. When DK = 4 A / DM ² - coarse-grained. Ammonium sulfate, g 220 2 84 81 80 80 Polyethylene polyamine, g 3 Aqueous solution of ammonia 25%, ml 85 Kaptax, mmol / l one Water, l up to 1 3 81 79 78 78 four 79 77 75 75 5 Copper sulfate, g 110 one 91 86 84 90 Ammonium sulfate, g 225 2 86 83 82 85 Polyethylene polyamine, g four Aqueous solution of ammonia 25%, ml 90 3 84 81 80 80 Kaptax, mmol / l 2 four 81 79 78 78 Water, l up to 1 6 Copper sulfate, g 115 one 93 90 86 92 Ammonium sulfate, g 230 2 90 88 84 88 Polyethylene polyamine, g 6 3 88 85 82 85 Aqueous solution of ammonia 25%, ml 95 Kaptax, mmol / l 3 four 85 82 79 80 Water, l up to 1 7 Copper sulfate, g 115 one one hundred 97 92 94 The coating is fine crystalline, even, uniform, smooth, mirror-shiny, adhesion is good. Ammonium sulfate, g 230 2 97 95 90 90 Polyethylene polyamine, g 6 Aqueous solution of ammonia 25%, ml 95 3 94 92 88 86 Bromobenzthiazo, mmol / L 3 Kaptax, mmol / l 3 four 91 90 87 84 Water, l up to 1

Table 3 Properties of copper precipitation obtained from the inventive electrolyte No. Electrolyte composition Dk, A / dm ² Cathode potential, -φ, V Shine, Rel. units Dissipation ability,% The number of pores per 1 cm ² and the thickness of the sediment, microns one 3 5 7 10 one 2 3 four 5 b 7 one. Copper sulfate, g 105 one 0.162 8 44 34 24 twenty fourteen 10 Ammonium sulfate, g 220 Polyethylene polyamine, g 3 2 0.431 24 40 Aqueous solution of ammonia 25%, ml 85 Bromobenzthiazo, mmol / L one 3 0.742 twenty 38 Water, l up to 1 four 0.783 fourteen 35 45 37 35 twenty 13 2. Copper sulfate, g 110 one 0.184 12 45 32 21 16 12 9 Ammonium sulfate, g 225 2 0.483 42 41 Polyethylene polyamine, g four 3 0.758 thirty 39 Aqueous solution of ammonia 25%, ml 90 Bromenzthiazo, mmol / l 2 four 0.791 eighteen 36 38 32 thirty 17 10 Water, l up to 1 3. Copper sulfate, g 115 one 0.243 35 48 thirty twenty eighteen 10 5 Ammonium sulfate, g 230 2 0.654 44 46 Polyethylene polyamine, g 6 Aqueous solution of ammonia 25%, ml 95 3 0.768 37 42 Bromobenzthiazo, mmol / L 3 four 0.801 21 38 36 28 22 16 9 Water, l up to 1 four. Copper sulfate, g 105 one 0.143 78 51 25 22 19 10 7 Ammonium sulfate, g 220 2 0.421 90 49 Polyethylene polyamine, g 3 Aqueous solution of ammonia 25%, ml 85 3 0.728 86 43 Kaptax, mmol / l one four 0.784 75 39 27 24 twenty 13 8 Water, l up to 1 5. Copper sulfate, g 110 one 0.168 83 56 23 twenty fifteen 8 5 Ammonium sulfate, g 225 2 0.453 one hundred 51 Polyethylene polyamine, g four 3 0.749 92 48 Aqueous solution of ammonia 25%, ml 90 Kaptax, mmol / l 2 four 0.805 90 40 thirty 25 16 eleven 6 Water, l up to 1 6. Copper sulfate, g 115 one 0.334 90 57 21 19 13 7 5 Ammonium sulfate, g 230 2 0.586 one hundred 52 Polyethylene polyamine, g 6 Aqueous solution of ammonia 25%, ml 95 3 0.762 one hundred 49 Kaptax, mmol / l 3 four 0.861 94 47 28 23 fourteen 10 Water, l up to 1 6 7. Copper sulfate, g 115 one 0.263 72 54 fifteen 10 6 four 2 Ammonium sulfate, g 230 Polyethylene polyamine, g 6 2 0.512 one hundred fifty Aqueous solution of ammonia 25%, ml 95 3 0.726 92 47 Bromobenzthiazo, mmol / L 3 Kaptax, mmol / l 3 four 0.873 85 42 eighteen fourteen 8 5 3 Water, l up to 1

Claims (1)

The copper plating electrolyte of steel substrates containing copper sulfate, ammonium sulfate, polyethylene polyamine, an aqueous solution of ammonia 25%, a hydrogen inhibitor and a brightener, characterized in that it contains bromobenzthiazo with a structure as a hydrogen inhibitor

and as a brightener, captax with a structure

in the following ratio of components:
Copper sulfate, g 105-115 Ammonium sulfate, g 220-230 Polyethylene polyamine, g 3-6 Aqueous solution of ammonia, ml 89-95 Bromobenzthiazo, mmol / L 1-3 Kaptax, mmol / l 1-3 Water, l up to 1