DE1804970B2 - GALVANIC CYANIDIC ORGANIC SELENIUM COMPOUND, SHINY COPPER BATH - Google Patents

Description

The present invention relates to a galvanic, cyanidic, organic selenium compound containing Bright copper bath for depositing shiny copper coatings.

Numerous attempts have been made to obtain such glossy coatings. For example is the use of alkali metal selenite as an additive to an electrolyte bath in relatively large Quantities have been suggested. Such baths are disadvantageous insofar as the selenite has the tendency have to decompose, adversely affecting the bright plating area. During electrolysis the anodes are blackened by decomposed selenite. The insoluble compounds formed are detached from the anodes and deposited together with the electrodeposited metal, which leads to rough deposits. In technical operation, this also results from the very narrow bright electroplating area an uneven appearance of the precipitations, and the precipitations are in many Cases not shiny enough that they need to be buffed.

U.S. Patent 2,770,567 discloses various selenium compounds with a valence of -2 described as a gloss-producing agent in alkaline copper electroplating. The shine of the precipitation is thereby improved over a wider current density range.

US Pat. No. 2,770,587 discloses the addition of various organic selenium compounds with only one nitrogen atom per molecule known as a brightener for cyanidic copper baths. the The effect of these known brighteners leaves something to be desired because they are in proportion have to be used in large quantities and because the gloss is not yet satisfactory.

The present invention is now intended to overcome the difficulties and disadvantages associated with the known Adhere to baths. The aim of the present invention is to create a bright copper bath in which relatively small amounts of additives are introduced and that significantly increases the gloss of the electroplated surface and a further, more uniform electroplating area results.

The coatings obtained with this bath should not only have a gloss, but should also be soft and ductile and, if desired, can be slightly polished or buffed to prevent the coating from sliding, for example on steel. Another object of the present invention is to provide a Bright copper bath that does not decompose even after long use.

The invention relates to a galvanic, cyanidic, organic selenium compound containing Bright copper bath for the deposition of shiny copper coatings, which is characterized by that the bath as a brightener organic selenium compounds of the general formula

Se

R —R '

-C ^/

contains, in which R is part of a ring structure which, in connection with the two carbon atoms to which R is bound, a benzene, naphthylene, pyridine, quinoline, pyrimidine, pyridazine, pyrazine, thiophene or pyrene ring and R 'is a substituent of bromine, chlorine or an alkyl, amino, acetyl, Hydroxyl, nitro group or a residue of the following formulas

Se

\ 1s1_r /

R -

and Se

RO -

NC ⁷

represents.

In the above formulas, selenium is shown with a valency of 4. It should be noted, however, that the compounds used according to the invention retain their aromatic character and also can be represented by the following resonance formulas:

The selenium compounds used according to the invention can be prepared by reacting the corresponding o-diamino ring compound with selenous acid.

The brightening agents according to the present invention act in an alkaline bright copper bath in concentrations of about 0.001 to 0.5 g / l. The preferred concentration range is between 0.001 and 0.02 g / l. There is very little visible difference in appearance in this preferred area of precipitation over the area, which is advantageous in that the precise concentration is not highly critical.

The use of the additive according to the invention produces a gloss-producing effect in all known alkaline bright copper baths. The use of the additives according to the invention influences the gloss formation of the copper deposits in a current density range from 5 to 100 A / 0.09 m ² . The electroplating baths given in the following examples are typical of such alkaline bright copper baths. These alkaline copper baths operate at temperatures in the range of about 54 to about 85 ° C and the current density can vary widely, as discussed in detail below. In the following examples, all quantities are given in grams per liter.

example 1

It becomes a base solution having the following composition and properties manufactured:

CuCN 75 g / l

Free KCN 18 g / l

KOH 25 g / l

K ₂ CO ₃ 40 g / l

pH 12.5 to 13.5

Temperature 68.5 ° C

This solution is used in a Hull cell with a cathode that is approximately 9.84 cm long and 5.08 cm is high. A current of 3 amps is used with an intermittent cycle, taking 8 seconds switched on and switched off for 2 seconds. It becomes a reciprocating mover used at about 60 rotations per minute. The electroplating time is 10 minutes. Using the normal length-current density scale for the Hull cell, the shine of the precipitation can be described as follows:

A / 0.09 m ²

0 to 10 dull / semi-glossy

10 to 60 semi-gloss

60 to 90 dull / semi-glossy

over 90 matt

To this solution 0.005 g / l dithioammelide are added, with the following results:

A / 0.09 m ²

0 to 30 very shiny

30 to 40 very lackluster /

semi-glossy

40 to 90 glossy / semi-glossy

over 90 matt

If the amount of dithioammelide is increased to 0.15 g / l, the following results are obtained:

A / 0.09 m ²

0 to 37 very shiny

37 to 60 lackluster

60 to 1000 semi-gloss

over 100 matt

It should be noted that the lack of luster, which occurs at medium current density in the case of thin cell plates shows is not as apparent when the plates are at or near this current density in beaker vessels or when parts are electroplated in production containers.

Example 2

0.005 g / l 1,2-selenodiazolebenzene with the formula are added to the same basic solution as in Example 1

are set, the low current density range of 0 to 3 A / 0.09 m ² becomes shiny.

Example 3

To the same basic solution as in Example 1, 0.015 g / l 1,2-selenodiazole naphthylene with the formula

N = Se

given, and a hull cell plate is electroplated as above:

A / 0.09 m ²

0 to 3 semi-gloss

3 to 150 glossy

over 150 lackluster

If 0.005 g / l dithioammelide is added to this solution

given. In this case the current density ranges are: A / 0.09 m ²

0 to 15 dull / semi-glossy

15 to 80 glossy

over 80 matt

If 0.01 g / l thioammelide is added, the following results for the current density ranges:

A / 0.09 m ²

0 to 90 glossy

over 90 matt

Example 4

A solution equivalent to the solution from Example 1 is used, but as a sodium formulation, ie NaCN, NaOH and Na ₂ CO ₃ are used instead of the potassium salts. If 0.006 g / l 1,2-selenodiazolebenzene are added, the precipitate on the Hull cell plate has the following appearance:

A / 0.09 m ²

0 to 5 semi-gloss

5 to 25 glossy

25 to 30 semi-gloss

30 to 60 glossy

60 to 75 semi-gloss

over 75 matte

It should be noted that this precipitate is not as shiny as the corresponding precipitate in Example 1 and that the upper limited current density is lower. This is generally the case for Sodium formulations versus potassium formulations. Become the above solution 0.005 g / L dithioammelide given with the following results:

A / 0.09 m ²

0 to 50 shine

50 to 80 semi-gloss

over 80 matt

When the amount of dithioammelide is increased to 0.05 g / l, a very lackluster current density band at 40 to 70 A / 0.09 m ^{2 is} obtained.

Example 5

The basic solution used in Example 1 is 0.002 g / l of l, 2-selenodiazole-3-aminobenzene

formula

NH

4. 1,2-Selenodiazole-4,6-dimethylbenzene CH ₃

given with the following results: A / 0.09 m ²

0 to 100 glossy

100 to 140 dull / semi-glossy

over 140 matt

If the amount of the selenium compound is increased to 0.01 g / l, the glossy surface loses some of its gloss, although it can still be called glossy, and the upper limiting current density is increased to about 150 A / 0.09 m ² .

20 Example 6

The procedure is as in Example 5, except that 0.002 g / l 2,3-selenodiazole pyridine with the formula

5. 2,3-selenodiazole phenol OH

6. 1 ^ -Selenodiazole-S-chlorobenzene

ei Wn.

Se

7. 1 ^ -Selenodiazole-S-nitrobenzene

NO-

be used. The following results are obtained:

A / 0.09 m ²

0 to 5 semi-gloss

5 to 100 glossy

100 to 120 semi-gloss

over 120 matt

By adding more 2,3-selenodiazole pyridine or by adding a small concentration (0.002 to 0.01 g / l) dithioammelide a glossy appearance is achieved even in the range from 0 to 5.

Other typical compounds of the invention include:

2,3-selenodiazole-5-aminopyridine

NH ₂ YVn ^ Se

2-methyl-4,5-selenodiazole pyridine

N = Se

1. 1 ^ -Selenodiazol ^ -carboxybenzene

45

COOH

2.1 ^ -Selenodiazol ^ o-dibromobenzene Br

10. 3,4-Selenodiazole pyridine

N = Se

55

60

11. 3,4-Selenodiazole-6-bromopyridazine

• N \ N

3. 1,2-selenodiazole-4-ethylbenzene

C ₂ H ₅

12. 4,5-Selenodiazole-3-aminopyridazine

NH ₂

Se = N

13. 4,5-Selenodiazole-2-methylpyrimidine

14. 5,6-selenodiazole pyrimidine

/ Ns

15. 2,3-Selendiazole-5-aminopyrazine

NH ₉

16. 2,3-Selenodiazole-6-bromopyrazine

/ Ns

17. 1 ^ -Selenodiazole-S-aminonaphthalene

N = Se

NH ₂ 18. 2,3-selenodiazole-1-benzazine

19. 2,3-Selenodiazolthiophene

20. 3,4-selenodiazole pyrrole

/ N _x

N N

21. Di (3,4-selenodiazolbenzene) ether

Se = N N = Se

22. 3,4,3 ', 4'-di (selenodiazole) diphenyl

N = Se

Se = N

From the preceding examples it can be seen that the addition of a small amount of dithioammelide Gloss in the extremely low current density areas improved. The use of dithioammelide and the equivalents thereof in cyanide copper baths is disclosed in U.S. Patent 2,862,861 im individually described.

Typical examples mentioned there are 2,4,6-trimercaptotriazine, dithioammelide, thioammelin, 4,6 - diamino - 2 - mercaptopyrimidine, 4,6 - diamino-2 - methylmercaptopyrimidine, 2,4 - dimercaptopyrimidine, 4-amino-6-hydroxy-2-mercaptopyrimidine, 6-amino-4-hydroxy-2-methyl-mercaptopyrimidine, 4 - hydroxy - 2 - mercapto - 6 - methylpyrimidine and 2-mercaptopyrimidine. All of these connections are in connection with the brightener used according to the invention to improve the gloss of galvanic copper deposition can be used in areas of extremely low current density. However, must it must be ensured that the concentration of these heterocyclic compounds is kept below 0.05 g / l is avoided if a dull galvanic deposit in the middle current density ranges is avoided shall be. However, if all of the electroplating is in the low current density range is carried out, up to 10 g / l of these compounds can be used to create a full gloss to cause galvanic precipitation in the areas of extremely low current density. Preferably however, the concentration of the dithioammelide is kept between 0.001 and 0.05 g / l.

A broad copper cyanide concentration range can be achieved with the gloss-producing agents according to the invention can be used and the copper cyanide concentration can range from about 45 to about 120 g / l. When no movement is applied, the best results are obtained when the concentration is about 75 to about 120 g / l. If the concentration decreases below about 75 g / l, it has been found that gloss is adversely affected without agitation. In general an increase in the copper cyanide concentration above about 120 g / l does not affect the gloss of the in agitated solutions not noticeably precipitate obtained. On the other hand, when the plating solution is moved, it has been found that the preferred concentration of copper cyanide for achieving is to be reduced considerably for optimal results. When strong movement is used, there is one Copper cyanide concentration, which is generally in

109 545/350

Range of about 55 to about 85 g / L has been found to be best. When the solution is stirred is, therefore, it is found that the gloss attributable to the compounds of the present invention deteriorates becomes, unless the copper cyanide concentration is adjusted to increase the degree of agitation compensate, or vice versa.

It has been found that generally larger amounts of free cyanide must be present when the solution is agitated compared with when the solution is not agitated. For example, if the solution is not agitated, it has been determined that if the concentration of free cyanide falls below about 4.0 g of free potassium cyanide per liter, a lackluster one Precipitation results. A similar lack of gloss appears above a concentration of free cyanide of about 30 g / l was found. The best results in stationary solutions are obtained when the The concentration of free cyanide is in the range from about 10 to about 20 g / l. If on the other hand, as above described above, when a strong movement is applied, it has been found to give the best results can be obtained when the concentration of free cyanide is generally in the range of about 14 to is about 25 g / l. When the concentration of free cyanide exceeds about 25 g / l, the cathode efficiency decreases noticeably off. Because of the need for "free cyanide" to be present, it can be seen that the limiting maximum amount of potassium cyanide is around 171 g / l when the copper cyanide concentration is around 100 g / l. The 171 g / l potassium cyanide are the sum of the potassium cyanide associated with the copper cyanide and of free cyanide.

In general, a wider pH range can be tolerated in the solution with optimal results in the pH range between about 11.5 and 13.5, when there is no agitation, and in a pH range between about 12.5 and 13.5 with vigorous agitation can be obtained. However, good results can in any case at pH values in the range of about 9-14 can be obtained.

For buffering the solution against pH changes and as a complexing agent for divalent copper ions and impurity ions, potassium citrate has been found useful in amounts that are generally range from about 35 to about 75 g / l. Best results have been obtained when the potassium citrate is used in amounts ranging from about 45 to about 65 grams per liter. Other buffering agents, such as Rochelle salts, ethylenediaminetetraacetic acid and the like can also be used, and the Rochelle salts can generally be used in amounts ranging from about 5 to about 55 grams per liter will. Usually the Rochelle salts are more effective in the agitated solutions than in the not moving solutions have been found.

The sodium or potassium carbonate can vary from 0 to 160 g / l, but 30 g / l is preferred are.

With regard to the temperature of the electroplating solution during the electroplating process, optimal results can be obtained in non-moving solutions over a somewhat wider temperature range than when using strong movement. For example, can without agitation of the solution temperatures in the range of about 60 to about 82 ° C, while preferably a temperature is employed from about 66 to about 71 ⁰ C when the solution is greatly moved. Again it can be seen that the ranges given above with respect to a moving and a non-moving solution mainly illustrate the invention and that the working conditions vary with regard to their optimum. Between the illustrated extreme case of agitation and the other extreme where there is relatively no agitation, solution temperatures of about 60 to about 85 ° C can be employed. Temperatures as low as 54 ° C have been indeed used successfully, but they are not highly recommended as the tendency to reduce the gloss of the resulting galvanized coating is, when the temperature of the plating solution drops below about 6O ⁰ C, for the case that no Movement is applied. On the other hand, if temperatures above about 71 ° C are used without agitation, somewhat higher current densities should be used. The current density range for bright electroplating tends to increase somewhat as higher temperatures are used. It should be noted, however, that temperatures of about 85 ° C. have been successfully applied using the gloss-producing agents of the invention.

In general, current densities of up to about 150 A / 0.09 m ² cathode surface can be used according to the invention. Interrupted current appears to allow a wider and slightly higher range of current densities and is usually preferred because it helps eliminate polarization and also minimizes film build-up on the anode.

Suitable cycles for the application of an interrupted current can be "switched on" for up to about 90 seconds and "switched off" for about 5 to about 50% of the "switched on" period of time. A suitable cycle is on for 7 seconds and off for 2 seconds. Periodic countercurrent can also be used, but in most cases will not have a beneficial effect. With a continuous current, optimal results in the form of maximum gloss in stationary solutions have been obtained when the current density is in the range from about 10 to about 35 A / 0.09 m ² cathode surface. Using high agitation and continuous current, it has been found that a preferred range of current densities of about 5 to 50 amps / 0.09 m ^{2 is} best, while with interrupted current the range is widened to about 5 to 60 A / 0.09 m ² can be increased.

Comparative example

The effect of the compounds according to the invention 1,2-selenodiazole-3-aminobenzene (compound 1, example 5), 2,3-selenodiazole pyridine (compound 2, example 6) and 1,2-selenodiazole benzene (compound 3, Example 2) as brightener in cyanidic bright copper baths was achieved with the effect of 2-Methylbenzselenozol compounds belonging to the art

C-CH ₃

(Compound 4), benzoselenazole

(Compound 5; U.S. Patent 2,770,587), selenourea

Se

H ₂ N - C - NH ₂
(Compound 6) and selenophenol

See

(Compound 7) compared.

All tests were carried out under the following conditions: A copper cyanide galvanizing bath with a pH value of 13 was used as the standard bath. In the tests, the baths were in a 500 ecm plastic cell according to Hull. Normal, buffed shell cell plates made of brass (6.35 10.2 cm; "27 ₂ x 4") were used as substrates. The electroplating bath was stirred and the experiments were carried out at a current of 3 amps for 5 minutes and at a bath temperature of 65.6 to 68.3 ° C.

Without the addition of a brightener, the precipitate from the stock solution was uneven in every attempt and lackluster.

When 0.005 g / l of Compound 1 was added to the stock solution, ^{a shiny or very shiny precipitate resulted at a current density between 0.54 and 13.45 amps / dm 2} (5 and 125 asf). When the amount of brightener was increased to 0.01 g / l, a very glossy precipitate ^{formed between 0.86 and 12.9 amps / dm 2.}

The addition of 0.005 g / l of compound 2 produced ^{a glossy precipitate in the entire range from 0 to 14.0 amps / dm 2} , while an addition of 0.01 g / l of the same compound produced a very glossy precipitate in the range of 0, 54 to 12.9 amps / dm ² resulted.

An addition of 0.005 g / l of compound 3 gave ^{a glossy coating in the range from 0.323 to 13.45 amperes / dm 2} , which, however, was covered by a slight haze. If the concentration was increased to 0.01 g / l, then in the range from 0.86 to 13.45 amperes / dm ^{2 there was} a shiny galvanic deposit, which also had a slight haze.

Now the monoazoles, namely the compounds 4 and 5, which belong to the state of the art, examined.

When 0.005 g / l of compound 4 was used as brightening agent in the standard bright copper bath, a non-uniform, semi-glossy coating in the range from 0 to 10.8 amps / dm ² resulted. If the amount of brightener was increased to 0.01 g / l, the result was ^{a semi-glossy coating in the range from about 0.54 to 8.07 amperes / dm 2} and a non-uniform, semi-glossy coating in the range from 8.07 to 11.8 amperes / dm ² . Subsequent tests at concentrations of 0.05, 0.1 and 0.25 g / l gave the same results as the concentration 0.01 g / l. Thus, even at relatively high concentrations, the brightener was not as effective as compounds 1 to 3 according to the invention.
When compound 5 was used, a non-uniform, lusterless precipitate was obtained at a concentration of 0.005 g / l. At a concentration of 0.01 g / l, a matt, semi-glossy coating in the range from 0 to 3.23 amperes / dm ² and

ίο a glossy coating in the range of 3.23 to 9.15 amps / dm ² . When the concentration was increased to 0.03 and 0.05 g / l, really glossy coatings between 1.29 and 9.15 amperes / dm ² or 0.646 and 9.15 amperes / dm ^{2 were obtained} . This means that although glossy coatings could be obtained, this generally required higher concentrations of glossing agents.

Compound 6 gave very good results even at low concentrations of 0.005 g / l.

A really glossy coating in the range from 0.969 to 12.9 amps / dm ^{2 was} thus obtained. However, this compound decomposed very quickly in the electroplating bath and was therefore unsuitable for the intended purpose.

Compound 7 gave uneven, lackluster precipitates at concentrations between 0.005 g / l and 0.02 g / l; so it was unsatisfactory at these low concentrations. However, a really glossy coating in the range of 1.29 to 4.84 amps / dm ² at a concentration of 0.04 g / l could be achieved with it. However, this concentration is considerably above the concentrations required for compounds 1 to 3 according to the invention, and the applicable current density range is also relatively small.

It thus follows that the diazoles according to the invention (compounds 1 to 3) at lower concentrations of gloss agent can achieve significantly better results than the rest of the tested, at the status of Technology belonging to selenium compounds, all of which had various disadvantages.

Claims (2)

Patent claims: 1. Galvanic, cyanidic, organic selenium compounds containing bright copper bath for the deposition of bright copper coatings, thereby characterized in that the bath uses organic selenium compounds of the general formula as brighteners Se M— 'N-C ⁷ R ' contains, in which R is part of a ring structure which, in connection with the two C atoms, is attached to the R is bonded, a benzene, napathylene, pyridine, quinoline, pyrimidine, pyridazine, pyrazine, Thiophene or pyrene ring forms and R 'is a substituent of bromine, chlorine or a Alkyl, amino, acetyl, hydroxyl, nitro group or a radical of the following formulas Se 13 14 and 3. bath according to claim 1, characterized / N — C \ net that it contains 1,2-selenodiazolebenzene. "" RO ^ ' ^ ^{a <} ^ ^nac ' ¹ claim 1 'marked thereby- ⁶ ^ / net that it contains 3,4-selenodiazole pyridine. N — C / 5 5. Bath according to claim 1, characterized in that that it depreciates 1,2-selenodiazole-5-aminobenzene. 2. bath according to claim 1, characterized marked- 6. bath according to claim 1 to 5, characterized marked- net that it distinguishes the organic selenium compounds in that it also contains 0.001 to 0.05 g / l a concentration of 0.001 to 0.02 g / l, io contains dithioammelide.