PL151258B1 - Nickel electroplating bath - Google Patents

Description

REPUBLIC POLAND PATENT DESCRIPTION 151 258 Additional patent READING OFFICE to patent no. Reported: 87 10 21 /P.268339/ Priority - GENERAL Int. Cl. ⁵ C25D 3/12 PATENT Application announced: 89 06 12 RP Patent description published: 1991 02 28

Creators of the invention: Benigna Szeptycka, Maciej Żubr,

Grażyna Chojnacka-Kalinowska, Magdalena Grzelak

Authorized by the patent: Institute of Precision Mechanics, Warsaw / Poland /

BATH FOR GALVANIC NICKEL PLATING

The subject of the invention is a bath for electroplating nickel plating. The base of the bath is an aqueous solution of nickel salts, especially those with a low concentration. The bath is used to obtain shiny or semi-shiny nickel coatings.

Known baths for electroplating nickel plating contain as basic ingredients nickel salts, conductive salts, buffer compounds and one or more brightening, anti-stress and wetting compounds, in particular, such as 1 ml of o-sulfobenzoic acid or the sodium salt of this imide, allylsulfonic acid, and naphthalene 1,3,6-trisulfonic acid, sodium salts of these acids or formalin, chloral, chloral hydrate, laurylsulfonic acid, laurylsulfuric acid, sodium salts of these acids as well as other sulfonamides, sulfonimides and salts of these sulfo compounds. Known baths also contain class II additives such as coumarin and its derivatives, alkynyl alcohols, alkynyl sulfates, alkynyl sulfonates, ring nitrogen compounds such as pyridine, picoline, quinoline.

A nickel electroplating bath based on nickel salts and carrier, anti-pitting and buffering additives is known from US Patent No. 3,898,138. This bath contains butindiol or hexindiol in the presence of butendiol or butenol as brightening and smoothing substances, and m-sulfobenzoic acid or its salts as the carrier compound. The known bath allows the deposition of semi-gloss, plastic and smooth nickel coatings characterized by low inherent stress and sulfur content lower than 0.005%

A bath for electroplating nickel plating based on nickel salts is known from German patent description No. 1173762 and contains two-ring quaternary salts as brightening compounds, the heterocyclic ring being pyrimidine, pyridazine,

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151 258 pyrazine, pyridine, quinoline, isoquinoline, quinazoline or quinoxaline and the substituent joining both rings is an alkylene substituent ^c n ^H 2n · E ^ n is from 1 to 5, terminated with an acid residue COO "or and the quaternary anion is a halogen anion or OH? The known bath allows the deposition of coatings with the highest gloss and good leveling.

There is known from US Patent No. 3,111,466 a bath for electroplating nickel containing as brightening and smoothing additives coumarin or its derivatives together with alkynylene compounds. The coatings produced from this known bath have a high corrosion resistance and a smoothness greater than that of the base metal.

There is known from British patent specification No. 970268 a bath for electroplating nickel containing as brightening components unsaturated glycol steroids and hydrate of chloral or bromal. The coatings applied from this known bath exhibit excellent corrosion resistance, columnar structure and are sulfur-free.

Baths containing known polishing and smoothing compounds are characterized by a good micro-smoothing ability of up to 81Ϊ, good corrosion resistance, low sulfur content, but at the same time a relatively high content of non-metallic inclusions.

The aim of the invention is to develop the composition of a nickel plating bath that will allow the deposition of nickel coatings characterized by a minimal content of non-metallic inclusions and increased corrosion resistance.

The aim of the invention is to provide a brightening and smoothing additive _, which _, when added to a bath with known basic ingredients, reduces the content of non-metallic inclusions in the nickel coating, while at the same time having high corrosion resistance of this coating. It is also an object of the invention to determine the amount of the brightening additive in which it is to be added to a bath of known essential ingredients.

The invention relates to a nickel plating bath consisting of an aqueous solution of nickel salts, in particular low concentration, conductive salts, buffering compounds and one or more carrier, anti-stress, anti-puncture and wetting compounds, especially o-sulfobenzoic imide, acid imide -phthalic acid or salts of these compounds, formaldehyde, chloral, bromal or hydrates of these compounds, laurylsulfonic acid, laurylsulfuric acid or salts of these acids and containing a brightening-smoothing compound, while the essence of the solution according to the invention consists in that the brightening-smoothing compound of the bath is a quaternary salt of formula I or a quaternary inner salt of common name betaine of formula II in which formulas H is 1,2-, 1,3- or 1,4-diazine, pyridine, α, β, or -picoline, quinoline , isoquinoline, 1,2-, 1 * 3- or 1,4-benzodiazine, 1,2,3-, 1,2,4- or 1,3,5-triazine, n is a natural number from 1 to 5, K, is C00 ~ or SO2 and X is a halogen, hydroxide, perchlorate or other hydrophilic anion wherein the quaternary salt or betaine is present in the bath in an amount of 0.1 to 20 mol per liter.

It is preferable to use a bath with a quaternary salt or betaine content of 0.1 to 5 mmoles per liter of bath.

The nickel coatings produced then are semi-gloss and contain a minimum number of non-metallic inclusions. Coatings from such a bath are characterized by increased corrosion resistance.

It is advisable to use a bath with a quaternary salt or betaine content of 2 to 20 millimoles per liter of bath. It has also turned out that in such a bath, shiny nickel coatings are produced with a smoothness greater than that of the substrate

The bath according to the invention is shown in the examples.

Example I. The composition of the bath is as follows: Ni ^ SO ^ · 7 ^ 0 - 130 g / dm \

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NICL ·,. 6iL, 0 - 60 g / dm, h ^ BO ^ - 45 g / dm, salt of ophthalic acid imide - 15 moles / dm, carboxyethylene pyrazinium bromide - 5 mmoles / dm \ Operation parameters of the nickel plating bath; temp. 4O-45 ° G, pH. - 3.8-4.0, current density 0.1-18 A / dm3, mixing with compressed air.

The content of non-metallic inclusions in the nickel coatings was measured with Leco apparatus manufactured in the USA. Nickel coatings applied to low-carbon steel samples with dimensions of 47 x 34 x 0.8 mm. Before applying the nickel coating, the samples were degreased and electrolytically activated, and then passivated with a 10% aqueous solution of sodium dichromate, which allowed to remove the nickel foil after it was applied to the prepared substrate. Results of measurements of the content of non-metallic inclusions. being the mean value of the three trials are as follows;

C-0.046%, S 0.001%, N ₂ O, O12%, 1 ^ -0.0014% 0 ₂ -0.018%. Sum of non-metallic inclusions 0.7θ%

The corrosion resistance was measured using accelerated test methods; GASS method and Corrodkote method. From the specified bath, a 15 µm thick nickel coating was deposited on low carbon steel specimens with dimensions of 65 x 47 * 1 mm, followed by a 5 µm glossy nickel coating and 0.3 µm thick chrome plating.

After the 24-hour test cycle, the samples tested with the GASS method had a corrosion resistance degree of 9, and the samples tested with the Corrodkote method had a corrosion resistance degree of 10.

Example II. The bath composition is as follows: NiSO · 7 ^ 0-150 g / dm ^, NiCl ^. óHgO- 40 g / dm \ Ug01 ₂ · 6 ŁL, 0 - 40 g / dm ^, H ^ EO ^ - 50 g / dm \ sodium salt of o-sulfobenzoic acid imide - 15 mmol / dm ^, chloral hydrate - 0, 5 mmol / dm 3, N-Carboxypropylene-4-methylpyridine - 20 mmol / dm. Operation parameters of the nickel plating bath: temperature 45-5O ° C, pH ^Ł 4.0-4.2, current density 0.1-18 A / dm3 while stirring.

The gloss of the nickel coating was measured with the Swedish 8510-1 glossmeter from C.S. Johansson was 100%. Using 15 min application time and current density

A / dm, nickel coatings were applied to the micro-groove plate matrices and a micro-smoothing was obtained for a 10 µm groove equal to 95% and for a 20 _with µm groove equal to 82%.

Claims (3)

Patent claims 1. Electroplating nickel plating bath consisting of an aqueous solution of nickel salts, especially low concentration, conductive salts, buffer compounds as well as one or more carrier, anti-stress, anti-pitting and wetting compounds, especially such as o-sulfobenzoic acid imide, o-phthalic acid imide or salts of these compounds, formaldehyde, chloral, bromal or hydrates of these compounds, laurylsulfonic acid, laurylsulfuric acid or salts of these compounds, and containing a brightening / smoothing compound, characterized in that the brightening / smoothing compound is a quaternary salt of formula I or a quaternary inner salt with the common name betaine of formula II, in which R is 1,2-, 1,3- or 1,4-diazine, pyridine, oc, β or -picoline, quinoline, isoquinoline, 1,2- , 1,3- or 1,4-benzodiazine, 1,2,3-, 1,2,4- or 1,3,5-triazine, n is a natural number from 1 to 5, means GOO "or Soj and X is halogen, hydroxide anion, n an chlorate or other hydrophilic anion, the quaternary salt or the betaine contained in the bath in an amount of 0.1 to 20 millimoles per liter. 2. Bath according to claim The composition of claim 1, wherein the quaternary salt or betaine content is 0.1 to 5 millimoles per liter of bath. Bath according to claim 1, characterized in that the content of the fourth order salt or betaine is from 2 to 20 millimoles per 1 liter of bath. 151 * 58 N- _{(CH2) n} - _Rl --HX Formula 1 Jsl- (CH ₂ ^} n " ^R i Formula 2 Department of Publishing of the UP RP. Circulation 100 copies. Price PLN 3,000