RU2239008C2 - Aqueous bright copper plating electrolyte - Google Patents

Abstract

FIELD: galvanostegy.

SUBSTANCE: electrolyte showing high diffusing capacity contains 150-170 g copper sulfate, 130-150 g sulfuric acid, 0.03-0.06 g S,S-(benzyloxy)propane-diisothiourea dihydrochloride, and water to 1 L and can be employed in mechanical and instrumentation engineering.

EFFECT: enabled formation of quality galvanic deposits well attached to support and characterized by minimum hydrogenation of steel.

3 tbl, 2 ex

Description

The invention relates to electroplating, in particular to the deposition of copper coatings on steel, and can be used in mechanical engineering and instrument making to obtain mirror copper coatings with minimal hydrogenation of the steel base.

Known electrolytes of brilliant copper plating [1-5] containing copper sulfate. sulfuric acid, sodium chloride and various organic additives. However, these electrolytes do not fully provide the possibility of obtaining high-quality galvanic coatings, well adhered to the base, with minimal hydrogenation of steel.

The objective of the invention is to obtain non-porous copper coatings with a mirror surface and a high dispersing ability of the electrolyte.

The technical result consists in obtaining high-quality galvanic precipitation, well adhered to the base, and with minimal hydrogenation.

This result is achieved in that the electrolyte, including copper sulfate, sulfuric acid, sodium chloride, contains, as a hydrogen inhibitor and a brightener, an additive - dihydrochloride-S-S- (benzyloxy) -propane-diisothiourea (M.M. 371) - having the structural formula:

in the following ratio of components, g:

Copper sulfate 150-170

Sulfuric acid 130-150

Sodium Chloride 0.03-0.06

Dihydrochloride-S-S- (benzyloxy) -

propanediisothiourea 3 · 10 ^-3 -5 · 10 ^-3

Water, l To 1

The synthesis of this compound is carried out by prolonged boiling in propyl alcohol of thiourea with 2-benzyloxy-1,3-dichloropropane, synthesized by heating epichlorohydrin and benzyl chloride in the presence of copper dichloride, and is a white crystalline substance, readily soluble in water.

To obtain the inventive electrolyte brilliant copper plating were prepared three composition of the components (see tab. 1).

The electrolyte is prepared as follows: dissolve the components in distilled water at a temperature of 18-25 ° C in separate volumes and introduce sulfuric acid and sodium chloride into a solution of copper sulfate with stirring. To remove impurities, the electrolyte is worked out for 4-6 hours at a current density of 1-4 A / dm ² , filtered and an organic additive is added. All reagents of the brand “analytical grade”.

Copper electrodeposition was performed on 20 × 50 × 2 mm plates of steel 20 with a copper deposition thickness of 20 μm.

Before coating, the samples were polished with a thin micron skin, degreased with Viennese lime, and washed with distilled water.

The appearance of the coatings was described using a microscope.

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

The gloss of copper coatings was measured on an FB-2 gloss meter (with a photocell) in relation to uviole glass, the gloss of which is 65 rel. units The range of values 10-50 corresponds to semi-brilliant, 50-90 to brilliant and 90-100 to a mirror surface.

The current efficiency was determined using a copper coulometer.

Steel hydrogenation was determined by the change in ductility of a spring wire made of U8A carbon steel with a diameter of 1 mm, a length of 100 mm, measured by the number of revolutions before failure when twisting on a K-5 machine (tensile load 1.5 kg). The ductility of steel samples (N) was determined by the formula N = (a / a ₀ ) · 100%, where a and a ₀ are the number of revolutions of the wire samples to failure of the respectively coated and uncoated copper layer.

The porosity of copper coatings was determined according to GOST 9.302-79.

The hardness of copper deposits was determined by the static indentation of the diamond pyramid on a PMT-3 instrument under a load of 20 g.

Adhesion was determined by scratching and bending wire samples by 180 °. Adhesion was considered good if peeling did not occur.

The scattering power of the electrolyte was determined by the Hering-Bloom method.

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

Example 1. Electrodeposition of copper was carried out from composition II (table 1) with the addition of dihydrochloride-8-5- (benzyloxy) propanediisothiourea with a concentration of 3 · 10 ^-3 mol / l at D _to = 2 A / dm ² (tables 2 and 3 ) The potential of the cathode is 0.29 V, which contributes to the production of high-quality galvanic precipitates with a fine crystalline structure, smooth, uniform, well adhered to the base, with a mirror surface (94 rel. Units). The ductility of steel samples is low and is 96-92%. The current efficiency is 955, the hardness of copper coatings is 182 kgf / mm ² , and the dissipation capacity of the electrolyte is 73%.

Example 2. Electrodeposition of copper was carried out from composition I (table 1) with the addition of dihydrochloride-8-8- (benzyloxy) propanediisothiourea with a concentration of 5 · 10 ^-3 mol / l at D _to = 1-4 A / dm ² (table 2 and 3). The cathode potential is greatly reduced and lies in the range from 0.18 to 0.29 V. The cathode deposits under these conditions form fine crystalline, even, uniform, smooth, well adhered to the base, have a mirror surface (0.95-100 rel. ) Precipitation is practically non-porous (at δ = 7-10 μm, the number of pores is 1-0). Diffusion of hydrogen through continuous coatings is difficult, therefore, hydrogenation is minimal (N = 10-90%). The current efficiency is 99-96%. The hardness of copper precipitation is 192-187 kgf / mm ² . The electrolyte has a high scattering power (71-80%), which allows to obtain samples uniform over the entire surface.

Thus, the above examples clearly show that the organic additive dihydrochloride-SS- (benzyloxy) -propanediisothiourea, introduced into the copper plating sulfate electrolyte, has an inhibitory and brightening effect and contributes to the production of high-quality galvanic precipitations, well adhered to the substrate, with a mirror surface and minimal hydrogenation of a steel base.

The high inhibitory and brightening effect of the organic additive - dihydrochloride-S-S- (benzyloxy) -propanediisothiourea - depends on the presence of its adsorption centers - nitrogen, oxygen and sulfur atoms, through which the additive is chemisorption bonded to the cathode metal surface.

Sources of information

1. A.S. 937537, USSR, 1982, BI No. 23.

2. A.S. 1010161, USSR, 1983, BI No. 13.

3. A.S. 1101478, USSR, 1984, BI No. 25.

4. A.S. 986969, USSR, 1983, BI No. 1.

5. A.S. 1274350, USSR, 1983.

Claims (1)

An aqueous electrolyte of brilliant copper plating, containing copper sulfate, sulfuric acid, sodium chloride, characterized in that it contains a dihydrochloride-SS- (benzyloxy) -propane-diisothiourea (MM 371) additive as a hydrogen inhibitor and a brightener, having the structural formula :

in the following ratio of components: Copper sulfate, g 150-170 Sulfuric acid, g 130-150 Sodium chloride, g 0.03-0.06 Dihydrochloride-S-S- (benzyloxy) - Propane-diisothiourea, mol / L 3 · 10 ^-3 -5 · 10 ^-3 Water, l to 1