CS271682B1 - Admixture for currentless copper plating bath - Google Patents

Abstract

The additive is formed by the compounds according to the general formula<IMAGE>,where R1 = aliphatic alkyl with 1 to 12 carbons, R2 = H -, Na -, K -, x and y = integral number 1 to 10, which it contains separately or in mixtures. It is applied in the amount of 0.01 to 0.50 grams per 1,000 millilitres of the solution for the electroless elimination of the copper plates on the steel base material. The solution is based on cupric sulphide, sulphur acid, derivates of diaminodiphenylmethane, polyethylene glycols, and anionic tensides, which are prepared by sulphonation of aliphatic alcohols. The efficiency of the additive is further increased by the addition of chloride ions in the form of chlorides of the alkali metals in the amount of 3.0 to 10.0 grams per 1,000 millilitres. It has the ability to refine the microstructure of the eliminated copper and increase its adhesion so that it enables the four-fold to five-fold copper-plated steel wire drawing that is required.

Description

(57) The additive © consists of compounds of the general formula

- ch - (ch ₂ ) _x - CH - CH - (сн ₂ ) _у - coor ₂ 0 - SO OH where ε means aliphatic alkyl of 1 to 12 carbons, R ₂ H -, Na -, К -, x а у »An integer of 1 to * 10, which it contains alone or in mixtures. It is applied in an amount of 0.01 to 0.50 g per 1000 ml bath for electroless deposition of copper layers on a steel base material based on copper sulfate, sulfuric acid, diaminodiphenylmethene derivatives, polyethylene glycols and anionic surfactants prepared by sulfonation of aliphatic alcohols.

The efficacy of the additive is further enhanced by the addition of chloride ions in the form of alkali metal chlorides in an amount of 3.0 to 10.0 g per 1000 ml. It has the ability to soften the microstructure of the deposited copper and to increase its adhesion so that it allows in practice the required four to five times the drawing of the copper-coated steel wire.

271 682 Italy (11) (13) B1 (51) Int. Cl. ⁵ C 23 C 18/38

CS 271682 Bl

The invention relates to the addition of a current-free bath based on cupric eiran, sulfuric acid, diaminodephenylmethane derivatives, polyethylene glycols and aminoactive surfactants.

Current-free copper layers and and most of all use dies for drawing steel wires. There are considerable demands on the adhesion and physical vlaatnoati of these gates, since the failure of the coherence of the coating to cover the surface of the wire during multiple drawing is required. The gates must be very firmly anchored to the crystal lattice of the base material, and must have a suitable microstructure that decisively affects the physical properties in terms of drawing.

The adhesion of the copper gates obtained by cementing from solutions of cupric sulphate and sulfuric acid is low. Coatings are formed by relatively large crystallites, which is caused by too high a rate of copper deposition due to the considerable difference between the electrochemical potentials of iron and copper. Therefore, divalent copper ions bind to strong complexes with organic compounds such as diaminodiphenylmethane derivatives, which significantly reduce the rate of excretion. This is accompanied by an increase in adhesion and a fine crystalline structure. The addition of surfactants to solutions such as polyethylene glycols with anionic surfactants prepared by sulfonation of aliphatic alcohols also improves.

The above-mentioned drawbacks are overcome by the additive according to the invention, which consists of the compounds of the general formula

R _R - CH - _(CH2 ^ - CH - CH - _(CH2) - C00R ₂ '

O - SO ₂ 0H where

R 1 is an aliphatic alkyl of 1 to 12 carbons, R ₂ is H-, Na-, K, x, y is an integer of 1 to 10, which it contains alone or in mixtures.

It has been found that this additive has the ability to adsorb to active centers of the crystal lattice of the parent metal to effectively inhibit the immediate access of complex copper ions in solutions containing cupric sulfate, sulfuric acid, diaminodiphenylmethane derivatives, polyethylene glycols and anionic surfactants prepared by eulfonation of aliphatic alcohols. The result is a reduction in the chemical reaction rate. The efficiency of the additive is further enhanced by the addition of alkali metal chloride, which together with the sulfuric acid and the additive according to the invention cause an increase in the number of active centers and thus a marked refinement of the microstructure of the deposited copper. The copper coatings then exhibit adhesion and physical properties sufficient to achieve in practice the required four- to five-fold drawing with the steel wires thus treated. It is suitable to add 0.01 to 0.5 g of chloride ions to the solutions in amounts of 3.0 to 10.0 g per 1000 ml. A detailed explanation is given in the following examples.

Example 1

Rolled steel wire of diameter 5.6 mm was copper plated in a bath for electroless copper coatings secretion of 25 g of copper sulfate, 70 g of sulfuric acid, 1.2 g tetrámethyldiaminodifenylmethaqu ^l 0.25 g of polyethylene glycol of MW 400, 1.5 g of polyethylene glycol of 4000, 0.15 g of anionic surfactant prepared by sulfonation of an aliphatic alcohol of 13 to 15 carbons per 1000 ml of an aqueous solution at 50 ° C and an exposure time of 5 minutes. The wire prepared in this way was pulled four times with dies of 4.00, 4.17, 3.55 and 3.08 mm in diameter. Already in the second stroke, the copper layer proved to be unstable and poorly adhering and there was a local peeling. 0/5 g of the additive according to the invention were added to the bath, kd R R - CH ₃ (CH ₂ ) ₅ -, R ₂ Na x - 1, у - 7 and 10 g of sodium chloride. The rolled steel wire was copper-plated and drawn under the same conditions as in the previous case. Even after the fourth stroke, the wire surface was covered with a continuous, firmly adhering layer of copper.

Example 2

Rolled steel wire has been copper plated in the bath as in Example 1 and 0.05 g of additive, wherein R ^ - ^{сн з (сн} 2) 5 2 * ^R ** ^{Na x} У ^{7 e # 0 01 9} P-series, wherein R-2-ethylhexyl, Rg-, K-, x-4, у-7 and 10 g of sodium chloride · bath temperature was 50 ° C, exposure time 5 minutes · drawn under the same conditions as in example 1 · after on the fourth stroke, the wire surface was covered with an eouviel, well adhering copper layer ·

Example 3

The rolled steel wire was copper-plated in the bath as in Example 1e by the addition of 0.05 g of the additive, where R ^ - CH ₃ (CHg) ₅ Rj * ^{Na x} * У * ^{7 and} ° · ⁰³ 9 additive, who R ^ - isobutyl, Rg -, Na -, x - 2, у - 2 and 10 g of sodium chloride · The bath temperature was 50 ° C, the exposure time was 5 minutes · It was pulled under the same conditions as in example 1 · , firmly adhering by copper layer ·

The invention can be used in metallurgical and mechanical engineering plants, where it performs wire drawing or other applications in which electrolessly deposited copper coatings are applied.

Claims (1)

P R E D M E T Addition to the electroless copper bath based on cupric sulphate, sulfuric acid, diaminodiphenylmethane derivatives, polyethylene glycols and anionic surfactants prepared by sulphonates of aliphatic alcohols and by the addition of chloride ions in the form of alkali metal chlorides, characterized in that it consists of compounds of the general formula R _x - CH - (CH g) _x - CH n CH - (CH _g ) _y - COOR g 0 - SOgOH where R 1 is an aliphatic alkyl of 1 to 12 carbons, R g is H Na K x, y is an integer of 1 to 10, containing eamotic or in mixtures ·