DE1246347B - Acid galvanic copper bath - Google Patents

Description

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FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl.

C23b

German class: 48 a -5/20

Number: 1 246 347

File number: Sch 38624 VI b / 48 a

Filing date: March 8, 1966

Opened on August 3, 1967

€ 25 D 3-38

The invention relates to an acidic electrolyte for the galvanic deposition of shiny copper coatings and has the task in particular of the electrolytic deposition of these precipitates from aqueous, to improve acidic solutions of copper salts.

It is known that acidic, in particular the most common sulfuric acid copper electrolyte Certain organic substances in small amounts can be added to instead of one crystalline-matt deposit to obtain shiny copper coatings. Are primarily suitable for this organic thio compounds. So was z. B. the use of thiourea, thiohydantoin, thiosemicarbazones Thiocarbamic acid esters, thiophosphoric acid esters and numerous derivatives suggested of these compounds. Since the quality of the copper precipitates with the sole addition of Thio compounds were unsatisfactory in most cases, and became a common use with nitrogenous substances, especially alkaloids and phenazine dyes, or with derivatives of the dioxolane.

However, it has been shown that these combinations also meet the increased requirements in practice not do justice. In particular, the following disadvantages are noticeable:

1. The copper deposit is shiny only in a limited current density range and falls particularly well matt in the range of low current densities. This means that you can work on profiled parts does not get a uniform coating, but that it is shiny on the outer surfaces, in But is dull.

2. The copper deposit is more or less obscured and thus does not have ³ ^ decorative appearance.

3. The leveling effect of the organic additives to the electrolyte is too small, so that polishing marks or defects in the base material _{can still be clearly seen after copper} plating and further mechanical processing is required. However, any additional polishing work results in high costs. In practice, therefore, there is increasing demand for highly leveling electrolytes with which the polishing costs can be reduced to a minimum.

It has now been found that the disadvantages mentioned can be overcome, and in particular the leveling one Effect can improve if one contains the acidic copper electrolyte Acid galvanic copper bath

Applicant:

Schering Aktiengesellschaft,

Berlin 65, Mullerstr. 170/172

Named as inventor:

Dr. Hans-Günther Todt, Berlin

Brighteners based on organic thio compounds, one or more straight-chain or branched ones Polyalkylenimines or their functional derivatives are added.

The salts of polyalkylenimines and their salts may be mentioned as examples of functional derivatives Reaction products with carbon dioxide, carbonic acid esters, alkyl halides or fatty acids.

The molecular weight of the compounds to be used according to the invention should be approximately between 180 and 50000 lie. The best results are obtained with substances that have a molecular weight between 1000 and 12000 own.

The quantities required to significantly improve copper deposition are extremely high low and are from 0.0005 to 0.1 g / l, in general from 0.0005 to 0.03 g / l, depending on the thio compounds and, if applicable, which other brighteners the copper bath contains. The thio compounds are used in the usual amounts of 0.001 to 0.1 g / l, preferably 0.005 to 0.05 g / l.

Sulfuric acid is generally used as the electrolyte Copper sulfate solution of the following composition is used:

CuSO ₄ · 5 H ₂ O 125 to 260 g / l

H ₂ SO ₄ 20 to 85 g / l

Instead of copper sulfate, other copper salts can also be used, at least in part. The sulfuric acid can be partially or completely replaced by fluoroboric acid, phosphoric acid or other acids. The electrolyte can be chloride-free or - which is usually beneficial for improving the gloss - Chlorides, e.g. B. contain alkali chlorides in amounts of 0.001 to 0.1 g / l. As further additives you can other conventional brighteners and / or wetting agents can be used.

In Table I, substances are compiled which, according to the invention, contain copper baths with organic thio compounds added to be haze-free

709 619/551

To obtain copper deposits with increased leveling effect.

Table I.

Preferred g / l substance concentration up to 0.01 up to 0.01 1. Polyethyleneimine 0.001 up to 0.005 2. polypropylene imine 0.001 up to 0.01 3. polybutylene imine 0.0005 up to 0.01 4. N-methyl polyethyleneimine .. 0.001 up to 0.01 5.N-butyl polyethyleneimine ... 0.001 up to 0.005 6.N-Amylpolyethyleneimine ... 0.001 up to 0.01 7. N-amyl polypropylene imine. . 0.0005 8.N-acetyl polyethyleneimine ... 0.001 9. Reaction product of Polyethyleneimine with up to 0.03 Ethylene carbonate (coals acid ethylene ester 0.005 10. Reaction product of Polyethyleneimine with up to 0.02 Propylene carbonate (carbon acid propylene ester) 0.005 11. Reaction product of up to 0.01 Polypropylene imine with carbon dioxide 0.002

² 5

The aforementioned substances are either known per se or can be prepared by methods known per se be produced, e.g. B. by polymerization of alkylene imines according to the procedures of the USA patent 2182 306 or by reacting the polyalkyleneimines with alkyl halides, fatty acids or fatty acid anhydrides, carbon dioxide or carbonic acid esters in suitable solvents at elevated levels Temperature (see e.g. W. K e r η and E. B r e η η iron, "Journal for practical chemistry" (2), 159, pp. 193 to 240 [1941]).

In the copper bath, the polyalkylenimines and the designated reaction products are present as salts, e.g. B. as sulfates in the usual sulfuric acid electrolytes. But you can also already in salt form be added, e.g. B. as hydrochloride, hydrobromide, methyl iodide, ethyl bromide etc.

Known copper electrolyte additives based on organic thio compounds are listed in Table II. that in the case of copper deposition when used alone is only an unsatisfactory one Make an impact.

Table II

substance

1. Thiourea

2. l-acetyl-2-thiourea

3. 1-Acetyltliiohydantoin

4. Carboxymethyl dithiocarbamic acid

5. Butyraldehyde thiosemicarbazone

6. Thiophosphoric acid tris (propyl ester tw-sodium sulfonate)

7. Thio malic acid

8. Butane-1,4-dithiol-2,3-disulfonic acid sodium

concentration

g / l

0.01

0.015

0.04

0.04 0.02

0.03 0.02

0.05

If, on the other hand, these compounds are used together with one or more substances from Table I, a clear and sudden improvement in the deposition is obtained, that is to say, the coating is free of haze and has excellent leveling. As further additives, the copper electrolyte can contain other known brighteners such as alkaloids, aliphatic carboxylic acids, gelatine, dextrin or polyethylene glycols.
ίο The following examples explain the invention:

example 1
In a copper bath of the composition

200.0 g / l copper sulfate (CuSO ₄ ■ 5 H ₂ O),
55.0 g / l sulfuric acid (conc.),
0.04 g / l sodium chloride

is obtained upon addition of 0.015 g / l acetylthiourea and at an electrolyte temperature of 2O ⁰ C and the cathode movement bright copper deposits, but in the current density range of 1.0 to 7.0 A / dm ² have irregular, milky haze. If an additional 0.0025 g / l polyethyleneimine or its reaction product with carbon dioxide is added to the electrolyte, the coatings are free of haze and have a significantly higher brilliance.

Example 2
The same electrolyte as in Example 1, but with

0.04 g / l acetylthiohydantoin and

0.1 g / l l-amino-2-methoxy-4-oxyanthraquinone,

provides even copper deposits which do not show any relief formation, but are veiled milky ^{in the current density range from 1.2 to 9.6 A / dm 2.} By adding 0.003 g / l N-ethyl polyethyleneimine, the precipitates turn out to be glossy and haze-free. The leveling effect of the electrolyte is about 45% with a layer thickness of 24 μ copper before the addition of N-ethylpolyethyleneimine, ie the roughness of the base material is reduced by 45% by the copper plating.

By adding the N-Ethylpolyäthylenimins the leveling increases to about 63%, i.e. it increases by 40%.

Example 3
The electrolyte according to Example 1 will be

0.03 g / l thiophosphoric acid tris (propyl ester

ω-sodium sulfonate) and
0.1 g / l polyethylene glycol

admitted. The leveling effect is around 48% with a layer thickness of 24 μ copper. To give Add an additional 0.003 g / l of polyethyleneimine to the bath, so the leveling increases under the same working conditions to 72%, which corresponds to an increase of 50%.

Similar good effects can be found in the tables when each of the others is used together I and II listed compounds achieve.

Claims (1)

Patent claims: 1. Acid galvanic copper bath with a content of organic brighteners Thio compounds in amounts of 0.001 to 0.1 g / l, preferably 0.005 to 0.05 g / l, thereby 5 6 characterized in that it contains one or more polyalkyleneimines their salts or reaction straight-chain or branched polyalkyleneimines or products with carbon dioxide, carbonic acid esters, their functional derivatives in amounts of 0.0005 alkyl halides or fatty acids,
to 0.1 g / l, preferably 0.0005 to 0.03 g / l. 3. Bath according to claim 1 or 2, characterized marked-2. Bath according to Claim 1, characterized in that it also has other customary glosses in that it contains the formers and / or wetting agents as functional derivatives. 709 619/551 7.67 ® Bundesdruckerei Berlin