DE1796337A1 - GALVANIC COPPER PYROPHOSPHATE BAEDER - Google Patents

Description

Excretion from

P 17 71 228.6-45 (Oase 351 / W)

Albright & Wilson Uifg.) Limited, Oldbury near Birmingham, Warwickshire (Great Britain)

Galvanic copper ^ pyrophosphate baths

5üs is known to electrolytically convert copper from alkaline Separate baths that contain an alkali-copper pyrophosphate complex the formula

X ₆ Cu (P ₂ O ₇ ) ₂ ,
in which X is an alkali metal.

Din characteristic ^., Feature of this galvanic Bä.der this is that they are in 3-emgemeinschaft with suitable Balancing agent additives for the formation of copper coatings of the best possible mirror finish that no longer require mechanical repolishing. In this They differ from the known acidic galvanic copper plating systems and from the Copper cyanide systems that provide matt gloss coatings. The gloss agents used in earlier bathrooms are intended to improve the glossy shine of the gloss coatings, while the Mi etel used in the latter systems are intended to serve the purpose of the matt gloss coatings to make it more suitable for mechanical polishing.

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As brightener additives to galvanic alkali pyrophosphate baths various heterocyclic compounds have been proposed, and some of these have proven to be particularly advantageous in electroplating. For a group of these heterocyclic compounds is that in a 5- or 6-membered heterocyclic ring system grouping present cfer formula

-Ή

C - SH ^

-Q

characteristic, in which Q denotes a nitrogen atom (which can be in a = Ή or -N bond) or a sulfur atom. Suitable representatives of these mercapbo-heterocyclic compounds are described in British patents 939,997, 940,282 and 1,051,150.

British patent specification 1 051 150 already mentions that in the galvanic baths, other organic compounds, such as simple aliphatic ^ or hydroxy-aliphatic carboxylic acids, can also be used can. These acids are oxalic acid, Tartaric acid and citric acid. These should be the grain fineness of the electrodeposited coating improve and reduce the anodic polarization.

The heterocyclic brighteners have copper pyrophosphate baths a strong gloss effect, but the technical use was hindered because, especially with Complex shaped objects did not produce a uniform plating; sharply demarcated objects were obtained

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matt surfaces, the so-called skip-plating. When trying to find suitable auxiliary brighteners or stasis agents is the effect of adding a variety of organic compounds to copper pyrophosphate electrolytes, which already contain an addition of the above-mentioned heterocyclic brighteners, been investigated. Even though the majority of the compounds examined turned out to be either ineffective or proved to be harmful, some have been found that improve the electrolyte, because they make it possible to prevent the risk of uneven coating formation. on in this way the optimum concentration range of the heterocyclic brightener is markedly widened. This is an effect that is completely different from that achieved by the

low molecular weight aliphatic and hydroxy-aliphatic Carboxylic acids in the British patent 1,051,150 is reported, and generally wise also the auxiliary brighteners found to be effective were made to have a higher molecular weight than those compounds that were previously used as additives Copper pyrophosphate electrolytes - albeit for completely different purposes - have been specifically described.

The present invention therefore relates to galvanic Copper pyrophosphate baths with a content of water-soluble heterocyclic brightener, the one Grouping the formula

C-SM (II)

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.As part of a 5- or β-membered ring Type in which Q- is a nitrogen or sulfur atom and M is a hydrogen atom or represents a cation (such as mercaptothiazoles, benzothiazoles, thiadiazoles or pyrimidines) or a preliminary stage of such, possibly in association with other additives like them for usually in galvanic copper pyrophosphate baths are used, characterized in that it also contains an alkarylsulfonic acid waiigsböns 7 carbon atoms and less than 5 carbon atoms contains in the alkyl chain or an arylsulfonic acid with more than 7 carbons. The additional Substances are in the galvanic copper pyrophosphate baths in an amount of 2 - 100 mg / l, preferably 3 - δ mg / l.

Comparative tests that have been carried out show that the aliphatic acids mentioned in British patent specification 1,051,150 do not have the effect how the inventive auxiliary brighteners have, i.e. that they have the step-shaped errors or the Do not prevent skip-plating.

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BAD ORIGfNAL

Tabel Brightener additive / l

Mirror finish skxp-plating Well moderate very good strong very good strong very good strong very good strong very good no

.2 mg 2

4 mg 2 MBT *)

4 mg DMTD '

4 mg DMTD ** '+ 10 mg Benzenesulfonic acid

4 mg DMTD '+ 100 mg Benzenesulfonic acid

A / J / \

4 ig DMTD ^j + 10 mg methylene-bis-naphthalenesulfonate

2 MBT = 2-mercaptoT3enzthiazole

DMTD = 2,5-dimercapto-1,3,4-thiadiazole

The heterocyclic brighteners useful for the purposes of the present invention can be obtained by those described in British Patent specification 940 282 described mercaptothiazole compounds are exemplified, including 2 ~ mercapto-1,3-thiazole and 2-mercapto-benzthiaaol include;

-G-

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also the 2-Iviercapto-1, 3,4-thiadiazole compounds, the are described in British patent specification 939 997, including, for example, 2,5-Dimercapuo-i, 3,4-thiädiazole, 2-iviercapto-5-inethi / linercapt, o-1,5,4-thiadiaZol and 2-Hercapto-5-n-butylmercap co-1, 3,4-thiadiasoi include; and also by the 2-mercaptoimirlazoles and 2-mercaptopyrimidines, that in British Patent 1,051 are described, including, for example, the 2-r; iercapto-1-methylimidazole, the 2-Iviercaptopyrimidin, the 6-Hydroxy-2-mercaptopyriniidin and the 6-hydroxy-2-niercaptq-4-me.thylpyrimidine belong. The precursors of the above-mentioned compounds also belong to this class of brighteners. The term “precursor” is to be understood here as meaning a compound which is dissolved in the Zupferpyrophosphat-lead electrolyte provides a compound in the solution which has the structure (II). For example, can heterocyclic disulfides comprising the grouping of the formula below

Il Il. .

G-S-S-O (III)

Q-

have to be used.

The auxiliary brighteners or scattering agents which can be used for the purposes of the present invention are acids which are normally used as sodium, potassium or ammonium salts. Particular mention may be here, the alkaryl sulfonates in which _(daa salt less than 5 carbon atoms in each alkyl chain, and preferably less than 5 aliphatic Kohlenetoffa.tome pro 'SuIfonatgruppe having. Alkylarylsulfonates

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"""'''** ^{:? u} - BAD ORIGINAL

with longer alkyl groups are generally unsatisfactory effective so that they are for the purposes of the present Invention are hardly of technical importance. Suitable salts include sodium xylene sulfonate, the salts of sulfonated uaphthalene-formaldehyde condensation products, e.g. the Methylenbis-Cnaphb-halinsulfonate), _ the salts of sulfonated polystyrenes and "potassium toluene sulfonate".

Ι ·; οrmalerweiß is the heterocyclic gloss agent in an amount of at least 0.001 g per liter of the total amount of the electrolyte is used, preferably in an amount of 1 to 10 mg per liter. The optimal one The concentration can vary between 2 and 4 mg per liter, depending on the type of auxiliary agent present. The FiIfs polish usually comes in one. Approximately 1 mg / l electrolyte to saturation, preferably in a tienge from 2 to 100 mg / l, e.g. from 3 to 6 mg / l electrolyte for use.

3s it is recommended that the inventive Electrolysis for galvanic copper deposition about the same composition in terms of the concentration of the copper salt and the pyrophosphate have, as the well-known elec- -crolyte, such as those mentioned above British patents are described. These ■ 'Slectrolyte can in addition to the heterocycliechen Gloss agents contain other additives, such as They are known to be used with this type of electrolyte. The electrolyte can be used for deposition von coatings on metal objects according to known Working methods are applied.

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The invention is illustrated by the following examples, in which electrolytes of the following Composition were used.

Copper pyrophosphate 94 g per liter, potassium pyrophosphate 300 g per liter, ammonia 1 g per liter, main brightener as specified below, in an amount of 2 mg / 1 electrolyte. Standard baths were made, the 3 heterocyclic brighteners contained, namely 2,5-dimercapto-l, 3,4-thiadiazole, 2-mercaptobenzimidazole and 2-mercaptobenzothiazole. The solutions were obtained with a pH of 8.8 at a temperature of 55.degree. The copper coatings were deposited on brass panels at a current density of 3.23 amperes per dm below Stirring by passing air through.

The tests were repeated with the three standard baths, but using the following auxiliary brighteners contained in a concentration of 10 mg / 1 electrolyte: 1. Itfodium-Toluolsulfonat,

2. sodium xylene sulfonate,

3..naph-feal intrisulfonate (Na),

4. vinyl benzene sulfonate (K),

5 polystyrene sulfonate (Na),

6. Methylene-bis-naphthalenesulfonate (Na)

In each example, the auxiliary brightener practiced an improved one Gloss and leveling effect without step-like defects (skipplating) occurring.

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BATH

Claims (2)

Claims 1 «Galvanic copper pyrophosphate baths with a content of water-soluble heterocyclic brightener, which is a grouping of the formula - SM 2. as part of a 5- or 6-membered ring having type in which Q is a nitrogen or sulfur atom and M is a hydrogen atom or a cation (such as mercaptothiazoles, benzthiazoles, thiadiazoles or pyrimidines) or a precursor of such, optionally in Community with other additives, as they are usually used in galvanic copper pyrophosphate baths, characterized in that it additionally contains an alkarylsulphonic acid with at least 7 carbon atoms and less than 5 carbon atoms in the alkyl chain or an arylsulphonic acid with more than 7 carbons. Bath according to claim 1, characterized in that it is the contains additional substances in an amount of 2-100 mg / l, preferably 3-6 mg / l ". 409809/1022