JPH0762587A - Additive for copper electroplating and copper electroplating bath - Google Patents

Abstract

PURPOSE:To obtain an additive for copper electroplating not reacting with a copper anode and capable of being used at a low current density by preparing the additive from an organic thio compd. shown by a specified formula. CONSTITUTION:An org. thio compd. shown by the formula (R<1> and R<2> are hydrogen atom or the same or different 1-8C substituted or unsubstituted monovalent hydrocarbonic group, R<3> is a 1-3C substituted or unsubstituted bivalent hydrocarbonic group, R<4> is a 1-2C substituted or unsubstituted bivalent hydrocarbonic group, and M is hydrogen atom, alkali metal atom or amine base) is used as an additive (brightener) for copper electroplating Meanwhile, sodium S-(2-ethylamide)-thiopropanesulfonate, etc., are exemplified as the org. thio compd., and the concn. in an electroplating bath is controlled to about 0.1-1000mg/l. A copper plating film which is hardly consumed when not in electrolysis and excellent in brightness and smoothness is obtained by using this additive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic copper plating additive suitable as a brightening agent for an electrolytic copper plating bath, particularly a copper sulfate plating bath, and an electrolytic copper plating bath containing the additive.

[0002]

2. Description of the Related Art Conventionally, a brightening agent has been added to an electrolytic copper plating bath to give a bright copper plating film.

In this case, an organic thio compound, an oxygen-containing polymer organic compound or the like is known as a brightener, and NaO ₃ SC ₃ H ₆ S-SC ₃ H ₆ S is known as the organic thio compound.
Disulfide such as O ₃ Na is widely used, and as the oxygen-containing polymer organic compound, an oxyalkylene polymer, polyethylene glycol, polypropylene glycol, a copolymer of ethylene oxide and propylene oxide, or the like is used. Furthermore, thiourea and its derivatives, organic acid amides, and the like are used as additives other than the above, and among these, a disulfide-based organic thio compound is preferably used in terms of glossiness and the like. .

[0004]

However, although disulfide has a considerable effect, it has a narrow usable current density range, and there is a limit to a particularly usable low current density area. In addition, since the decomposition products are accumulated while the plating bath is not used or during the electrolysis, the usable low current region is further reduced, so that the brightener is added or the decomposition products are removed. There is a problem that the plating solution often needs to be filtered with activated carbon.

Further, the consumption of disulfide varies depending on the current density, and is more susceptible to the influence of the anode, and in particular, it is considered that it reacts with the copper anode (anode) as follows.

Cu + R-S-S-R → 2Cu (I) S-R That is, conventionally, metallic copper has been used as an anode for copper sulfate plating, and particularly phosphorous copper has been used. In this case, in the case of phosphorus-containing copper, when plating is normal, a so-called black skin is formed on the surface of the anode and is stably maintained, but when disulfide is used as a brightener, the black skin is formed in the low current density region. It may not be generated and the current distribution may be disturbed, resulting in defective plating.

Therefore, when the conventional organic thio compound (disulfide) is used as a brightening agent for copper plating, it is difficult to control the plating bath and it is consumed without using it. Is likely to occur.

Therefore, there has been a demand for a brightener for copper plating that is easy to manage and does not wear even when not in use.

The present invention has been made in view of the above circumstances.
Additive and electricity for electrolytic copper plating that can perform plating treatment in the low current density region without impairing gloss and prevent consumption of the plating solution when not in use without reacting with the copper anode (anode) The purpose is to provide a copper plating bath.

[0010]

Means and Actions for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the present inventor has found that HS-R ⁴ -can be used for amides such as acrylamide and N, N-dialkylamides. By reacting a compound represented by SO ₃ M, a novel organic thio compound represented by the following general formula (1) having an amide group and a sulfonic acid group and having a thioether bond can be obtained, and It was found that this organic thio compound is preferably used as an additive (brightening agent) for a copper sulfate plating bath.

[0011]

[Chemical 2] (However, in the formula, R ¹ and R ² are hydrogen atoms or the same or different, substituted or unsubstituted monovalent hydrocarbon groups having 1 to 8 carbon atoms, and R ³ is a substituted or unsubstituted 2 to ³ carbon atoms. Valent hydrocarbon group, R ⁴
Represents a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms. M represents a hydrogen atom, an alkali metal atom or an amine base. )

That is, as shown in the above formula (1), the sulfur atom is not present as a mercaptan, disulfide, dithiocarbamic acid, or xanthogenic acid, but as a sulfide (thioether) group. The reason for this is that it is not always clear that the amide group is present in the same molecule, and the presence of an amide group in the same molecule makes it possible to control the effect of sulfide (thioether). When it is present, it can be made water-soluble, and when this organic thio compound of formula (1) is used, it does not react with the copper anode and has a low degree of wear during non-electrolysis, and it has a conventional disulfide-based additive. The inventors have found that it is possible to provide a plating film having a gloss and smoothness equal to or higher than that of the present invention, and thus completed the present invention. It is intended.

The present invention will be described in more detail below. The additive for electrolytic copper plating of the present invention comprises an organic thio compound represented by the following general formula (1).

[0014]

[Chemical 3]

Here, R ¹ and R ² are hydrogen atoms or the same or different, substituted or unsubstituted monovalent hydrocarbon groups having 1 to 8 carbon atoms. As such monovalent hydrocarbon groups, Examples thereof include lower alkyl groups having 1 to 4 carbon atoms and aryl groups such as phenyl.

R ³ is a substituted or unsubstituted 2 having 1 to ³ carbon atoms.
The valence hydrocarbon group, _{specifically, - (CH 2) n -} (n
= 1 to 3) lower alkylene group.

R ⁴ is a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms, and examples of such a divalent hydrocarbon group include the following.

[0018]

[Chemical 4] (However, R ⁵ is a hydrogen atom, a group selected from —COOR and —OR (R is a hydrogen atom, an alkali metal or a lower alkyl group having 1 to 4 carbon atoms), and R ⁶ and R ⁷ each have 1 carbon atom. To 4 are lower alkylene groups, m is an integer of 1 to 4, and k is an integer of 1 to 2.)

M is a hydrogen atom, an alkali metal such as Na or K, or an amine base such as mono-, di- or triethanolamine.

Examples of such an organic thio compound include S-
(2-Ethylamido) -thiopropanesulfonic acid, S-
(3-Propylamide) -thiopropanesulfonic acid, S
-(4-Butylamido) -thiopropanesulfonic acid, S
-(3-Butylamido) -thiopropanesulfonic acid, S
-(3-propylamido) -thiopropyl-2-hydroxy-3-sulfonic acid, S- (3-propylamido)-
Thiophenylsulfonic acid, S- (N, N-dimethyl-3
-Propylamide) -thiopropanesulfonic acid, S-
(N-phenyl-3-propylamido) -thiopropanesulfonic acid, S- (3-propylamido) -thiobenzene-2-carboxy-4-sulfonic acid, S- (3-propylamido) -thiobenzene-4-sulfone Acid, S-
(3-Propylamido) -thio-2-naphthalene sulfonic acid, and their sodium salts, potassium salts, amine bases and the like.

The organic thio compound of the above formula (1) is, for example, a carbon-substituted chloroamide such as 2-chloroacetamide, an amide having an aliphatic unsaturated group such as acrylamide or N, N-dialkylamide, and HS-R. ^4- SO ₃
It can be obtained by reacting a compound represented by M (R ⁴ and M have the same meanings as described above).

In this case, the solvent used is not particularly limited as long as it dissolves the reaction starting material, but if H ₂ O, methanol, ethanol, 2-propanol, DMF or the like is used, good yield can be obtained. The target substance is obtained at a rate.
These solvents may be used alone or in combination of two or more.

The pH of the reaction solution is alkaline, but p
Rather than regulating H, the added hydroxide HS-R ⁴
The molar ratio to the compound represented by —SO ₃ M (R ⁴ and M have the same meanings as above) is 1.0 in the reaction with carbon-substituted chloroamides, and the amides having an aliphatic unsaturated group. In the reaction with, it is effective to set the molar ratio to about 0.1. Here, the hydroxide is preferably NaOH or KOH.

The amides are used in a molar ratio of 1 to 10 with respect to the compound represented by HS-R ⁴ -SO ₃ M (R ⁴ and M have the same meanings as described above). If it is less than 1, it takes time and effort to collect unreacted HS-R ⁴ —SO ₃ M.
If it is larger than 0, it is economically disadvantageous.

The reaction temperature is preferably 30 to 80 ° C. If the reaction temperature is higher than 80 ° C, hydrolysis of the amide group increases, and if it is lower than 30 ° C, the reaction rate becomes slow, which is economically disadvantageous.

The reaction time varies depending on the reaction temperature, but is 6
It is sufficient to react at 0 ° C. for 3 hours.

When the additive of the present invention is used in an electrolytic copper plating bath, the concentration at that time is 0.1 to 1,
It is preferably 000 mg / L, particularly preferably 0.3 to 500 mg / L. When the concentration is less than 0.1 mg / L, glossiness,
Leveling property may be insufficient, 1,000 mg /
If it exceeds L, the appropriate current density range is narrowed, and the appearance of the low current density region in particular may be deteriorated.

The electrolytic copper plating bath to which the above-mentioned additives are added is preferably a copper sulfate plating bath, and the composition of such a copper sulfate plating bath is a usual composition such as copper sulfate (C
_{uSO 4 · 5H 2 O) 30~250g} / L, concentrated sulfuric acid 50
A plating bath having a basic composition of 250 g / L is suitable.

When the additive of the present invention is used for electrolytic copper plating, it can give a satisfactory gloss effect by itself, but other known additives can be used to obtain the gloss effect and smoothness. Can be further improved.

For example, an oxygen-containing high molecular weight organic compound can be added to the plating bath of the present invention, specifically, polyvinyl alcohol, carboxymethyl cellulose, polyethylene glycol, polypropylene glycol, stearic acid-polyethylene glycol ester, stearyl. Alcohol-polyethylene glycol ether, nonylphenol-polyethylene glycol ether, octylphenol-polyethylene glycol ether,
Polyethylene-propylene glycol (copolymer or block copolymer), β-naphthol-polyethylene glycol ether and the like can be added. in this case,
It is preferably contained at a concentration of 0.1 to 10 g / L, particularly 0.2 to 5 g / L.

Further, a conventionally known organic thio compound can be added to the plating bath of the present invention. Specifically, bis (3-sulfopropyl) disulfide or its disodium salt, bis (2-sulfopropyl)
Disulfide or its disodium salt, bis (3-sulfo-2-hydroxypropyl) disulfide or its disodium salt, bis (4-sulfobutyl) disulfide or its disodium salt, bis (p-sulfophenyl) disulfide or its disodium salt Salt, 3-
(Benzothiazolyl-2-thio) propylsulfonic acid or its sodium salt, N, N-dimethyl-dithiocarbamic acid- (3-sulfopropyl) -ester or its sodium salt, O-ethyl-diethyl carbonic acid-S- (3-sulfo Propyl) -ester or its potassium salt, thiourea and its derivative, etc. can be added. The concentration in that case is preferably 0.0001 to 0.1 g / L, and particularly preferably 0.0003 to 0.05 g / L.

Furthermore, organic acid amides can be added to the plating bath of the present invention. Specifically, acetamide, propylamide, benzamide, acrylamide,
Methacrylamide, N, N-dimethylacrylamide, N, N-diethylmethacrylamide, N, N-diethylacrylamide, N, N-dimethylmethacrylamide, N- (hydroxymethyl) acrylamide, polyacrylic acid amide, polyacrylic acid amide A hydrolyzate or the like can be added. In this case, 0.001-1
It is preferably contained at a concentration of 0 g / L, particularly 0.005 to 5 g / L.

The plating bath of the present invention is particularly suitable for plating a printed circuit board having a through hole, but usual conditions can be adopted as the plating condition.
Plating temperature 20 to 30 ° C, cathode current density 1 to 8 A / dm
The conditions of ² can be adopted, and stirring such as air stirring, cathode locking, stirrer stirring and the like can be performed.

[0034]

The additive for electrolytic copper plating of the present invention is a copper which does not react with the copper anode and can be used at a low current density, has little wear during non-electrolysis, and has good gloss and smoothness. A plating film can be provided.

[0035]

EXAMPLES The present invention will be specifically described below with reference to Examples, Comparative Examples and Reference Examples, but the present invention is not limited to the following Examples. The plating bath was agitated by blowing air, and the air was hit on the object to be plated so that the vicinity of the cathode was well agitated.

[Example 1] S- (2-ethylamido) -thiopropanesulfone was added to a copper plating bath composed of the following composition: copper sulfate (CuSO ₄ .5H ₂ O) 80 g / L concentrated sulfuric acid 200 g / L NaCl 100 mg / L. Plating was performed using a Hull cell tester at a total current of 2 A for 10 minutes using a plating bath containing 5 mg / L of sodium acid salt and 3 g / L of polyethylene glycol (# 10,000). As a result, the deposit had good gloss under the following conditions. pH <1 temperature 25 ° C. cathode current density 0.15 to 4 A / dm ² Also, the Hull cell tester was left overnight with the copper plate still in place, and plating was performed in the same manner as above, but the same as the first plating. Giving good gloss.

Example 2 The following composition was added to a copper plating solution consisting of copper sulfate (CuSO ₄ .5H ₂ O) 60 g / L concentrated sulfuric acid 200 g / L NaCl 80 mg / L and S- (3-propylamide)-
Plating was performed using a Hull cell tester at a total current of 2 A for 10 minutes using a plating bath containing 3 mg / L of sodium thiopropanesulfonate and 3 g / L of polyethylene glycol (# 10,000). As a result, the deposit had good gloss under the following conditions. pH <1 temperature 25 ° C. cathode current density 0.15 to 4 A / dm ² Also, the Hull cell tester was left overnight with the copper plate still in place, and plating was performed in the same manner as above, but the same as the first plating. Giving good gloss.

Example 3 The following composition was added to a copper plating solution consisting of copper sulfate (CuSO ₄ .5H ₂ O) 50 g / L concentrated sulfuric acid 250 g / L NaCl 100 mg / L, and S- (4-butylamide) -thiopropanesulfone. Sodium acid 3 mg / L, polyacrylic acid amide (# 1,000) 2 g / L, polyethylene glycol (# 10,000) 0.2 g / L were added to the plating bath, total current 2A, time 10 minutes The plating was performed using a Hull cell tester at. As a result, the deposit had good gloss under the following conditions. pH <1 temperature 25 ° C. cathode current density 0.15 to 4 A / dm ² Also, the Hull cell tester was left overnight with the copper plate still in place, and plating was performed in the same manner as above, but the same as the first plating. Giving good gloss.

Example 4 The following composition was added to a copper plating solution consisting of copper sulfate (CuSO ₄ .5H ₂ O) 80 g / L concentrated sulfuric acid 180 g / L NaCl 100 mg / L, and S- (3-propylamide)-
Using a plating bath containing 5 mg / L of sodium thiopropyl-2-hydroxy-3-sulfonate, 1 g / L of acrylamide, and 0.3 g / L of polyethylene glycol (# 10,000), total current 2A, time 10 minutes The plating was performed using a Hull cell tester at. As a result, the deposit had good gloss under the following conditions. pH <1 temperature 25 ° C. cathode current density 0.15 to 4 A / dm ² Also, the Hull cell tester was left overnight with the copper plate still in place, and plating was performed in the same manner as above, but the same as the first plating. Giving good gloss.

Example 5 The following composition was added to a copper plating solution consisting of copper sulfate (CuSO ₄ .5H ₂ O) 80 g / L concentrated sulfuric acid 200 g / L NaCl 100 mg / L and S- (3-propylamide)-
Sodium thiobenzene-4-sulfonate 3 mg /
0.3 g of L, polyethylene glycol-polypropylene glycol block polymer (BASF L-35)
Plating was performed using a Hull cell tester with a total current of 2 A and a time of 10 minutes using the plating bath containing / L. As a result, the deposit had good gloss under the following conditions. pH <1 temperature 25 ° C. cathode current density 0.15 to 4 A / dm ² Also, the Hull cell tester was left overnight with the copper plate still in place, and plating was performed in the same manner as above, but the same as the first plating. Giving good gloss.

Example 6 The following composition was added to a copper plating solution consisting of copper sulfate (CuSO ₄ .5H ₂ O) 80 g / L concentrated sulfuric acid 200 g / L NaCl 100 mg / L and S- (N, N-dimethyl-3-).
Propylamide) -sodium thiopropanesulfonate 5 mg / L, polyethylene glycol (# 10,000)
0) in an amount of 3 g / L and propylene glycol (# 400) in an amount of 0.15 g / L were used to perform plating with a Hull cell tester at a total current of 2 A and a time of 10 minutes. As a result, the deposit had good gloss under the following conditions. pH <1 temperature 25 ° C. cathode current density 0.15 to 4 A / dm ² Also, the Hull cell tester was left overnight with the copper plate still in place, and plating was performed in the same manner as above, but the same as the first plating. Giving good gloss.

Next, as a reference example, a method for producing the organic thio compound of the formula (1) is shown below. [Reference Example 1] <S- (3-propylamido) -sodium thiopropanesulfonate> 10 equipped with a stirrer, thermometer and cooling tube
0.2 g of sodium hydroxide in a 00 ml four-necked flask
(0.005 mol) and 700 ml of methanol were added and dissolved. After that, 7.1 g of acrylamide (0.10
Mol) and sodium mercaptopropane sulfonate 8.
9 g (0.05 mol) was added and dissolved, and the mixture was stirred at 60 ° C. for 3 hours. After completion of the reaction, the pH was neutralized to 7 with 1N hydrochloric acid. Then, after concentrating to dryness and washing with chloroform,
By extracting the methanol-soluble component, 10.2 g of sodium S- (3-propylamido) -thiopropanesulfonate (white powder) was obtained (mp 255 ° C.).
In this case, the yield based on sodium mercaptopropane sulfonate was 81.7%. Obtained S- (3-
The IR spectrum of propylamido) -sodium thiopropanesulfonate is shown in FIG.

[Reference Example 2] <S- (N, N-dimethyl-3-propylamido) -sodium thiopropanesulfonate> A 1000 ml four-necked flask equipped with a stirrer, a thermometer and a condenser was used for hydroxylation. Sodium 0.2g (0.005mol) and methanol 7
00 ml was added and dissolved. Thereafter, 9.9 g (0.10 mol) of N, N-dimethylacrylamide and 8.9 g (0.05 mol) of sodium mercaptopropanesulfonate were added and dissolved, and the mixture was stirred at 60 ° C. for 3 hours. After completion of the reaction, the pH was neutralized to 7 with 1N hydrochloric acid. Then, the mixture was concentrated to dryness, washed with chloroform, and the methanol-soluble matter was extracted to give S- (3-N, N-dimethyl-
10.9 g of sodium 3-propylamido) -thiopropanesulfonate (white powder) was obtained (mp 250)
C). In this case, the yield based on sodium mercaptopropane sulfonate was 78.7%. The obtained S-
FIG. 2 shows an IR spectrum of (3-N, N-dimethyl-3-propylamido) -sodium thiopropanesulfonate.
Shown in.

Reference Example 3 <Sodium S- (3-propylamido) -thiobenzene-2-carboxy-4-sulfonate> A 1000 ml four-necked flask equipped with a stirrer, a thermometer and a cooling tube was hydroxylated. 0.2 g (0.005 mol) of sodium and 700 ml of methanol were added and dissolved. Thereafter, 7.1 g (0.10 mol) of acrylamide and 14.0 g (0.05 mol) of disodium 4-sulfothiosalicylate were added and dissolved, and the mixture was stirred at 60 ° C. for 3 hours. After completion of reaction, 1N
The pH was adjusted to ₂ with hydrochloric acid. Then, after concentrating to dryness and washing with chloroform, by extracting a methanol-soluble component, S- (3-propylamido) thiobenzene-2-
Sodium carboxy-4-sulfonate (white powder)
9.6 g was obtained. In this case, the yield based on disodium 4-sulfothiosalicylate was 54.9%. Obtained S- (3-propylamido) -thiobenzene-2-
The IR spectrum of sodium carboxy-4-sulfonate is shown in FIG.

Reference Example 4 <S- (3-Propylamido) -thiobenzene-4-sulfonate> 0.2 g of sodium hydroxide in a 1000 ml four-necked flask equipped with a stirrer, thermometer and cooling tube. (0.005 mol) and 700 ml of methanol were added and dissolved. After that, 7.1 g of acrylamide
(0.10 mol) and 10.6 g (0.05 mol) of sodium mercaptobenzene-4-sulfonate were added and dissolved, and the mixture was stirred at 60 ° C. for 3 hours. After completion of the reaction, the pH was neutralized to 7 with 1N hydrochloric acid. Then, the mixture was concentrated to dryness, washed with chloroform, and the methanol-soluble matter was extracted to give S- (3-propylamido) -thiobenzene-4.
-8.7 g of sodium sulfonate (white powder) was obtained (mp 140 ° C). In this case, the yield based on sodium mercaptobenzene-4-sulfonate is 61.5%.
Met. The IR spectrum of the obtained sodium S- (3-propylamido) -thiobenzene-4-sulfonate is shown in FIG.

Reference Example 5 <Sodium S- (3-propylamido) -thio-2-naphthalene sulfonate> Sodium hydroxide was added to a 1000 ml four-necked flask equipped with a stirrer, a thermometer and a condenser. 2 g (0.005 mol) and 700 ml of methanol were added and dissolved. After that, 7.1 g of acrylamide
(0.10 mol) and sodium 2-mercaptonaphthalenesulfonate (13.1 g, 0.05 mol) were added and dissolved, and the mixture was stirred at 60 ° C. for 3 hours. After completion of the reaction, the pH was neutralized to 7 with 1N hydrochloric acid. Then, the mixture was concentrated to dryness, washed with chloroform, and the methanol-soluble matter was extracted to obtain 11.5 g of sodium S- (3-propylamido) -thio-2-naphthalenesulfonate (white powder). (Mp 300 ° C.). In this case, the yield based on sodium 2-mercaptonaphthalene sulfonate was 69.1.
%Met. The IR spectrum of the obtained sodium S- (3-propylamido) -thio-2-naphthalenesulfonate is shown in FIG.

[Reference Example 6] <S- (2-ethylamido) -sodium thiopropanesulfonate> 100 equipped with a stirrer, thermometer and cooling tube
1.2 g of sodium hydroxide in a 0 ml four-necked flask
(0.03 mol) and 600 ml of methanol were added and dissolved. Then, 2-chloroacetamide 5.6 g
(0.06 mol) and 5.3 g (0.03 mol) of sodium mercaptopropane sulfonate were added and dissolved, 60
The mixture was stirred at ° C for 3 hours. After the reaction is completed, pH is adjusted with 1N hydrochloric acid.
Neutralized to 2. Then, after concentrating to dryness and washing with chloroform, the methanol-soluble matter is extracted to obtain S
5.8 g of sodium-(2-ethylamido) -thiopropanesulfonate (white powder) was obtained (mp 255).
C). In this case, the yield based on sodium mercaptopropane sulfonate was 90.7%. The obtained S-
The IR spectrum of (2-ethylamido) -sodium thiopropanesulfonate is shown in FIG.

[Brief description of drawings]

FIG. 1 shows an IR spectrum of an organic thio compound obtained in Reference Example 1 of the present invention.

FIG. 2 shows an IR spectrum of the organic thio compound obtained in Reference Example 2 of the present invention.

FIG. 3 shows an IR spectrum of the organic thio compound obtained in Reference Example 3 of the present invention.

FIG. 4 shows an IR spectrum of the organic thio compound obtained in Reference Example 4 of the present invention.

FIG. 5 shows an IR spectrum of the organic thio compound obtained in Reference Example 5 of the present invention.

FIG. 6 shows an IR spectrum of the organic thio compound obtained in Reference Example 6 of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Teruyuki Hotta 1-5-1, Exit Hirakata, Osaka Prefecture Central Research Institute, Uemura Industrial Co., Ltd. (72) Tohru Uetama 1-5 Exit, Hirakata, Osaka No. 1 Uemura Industrial Co., Ltd. Central Research Laboratory

Claims (2)

[Claims] 1. An additive for electrolytic copper plating comprising an organic thio compound represented by the following general formula (1). [Chemical 1] (However, in the formula, R ¹ and R ² are hydrogen atoms or the same or different, substituted or unsubstituted monovalent hydrocarbon groups having 1 to 8 carbon atoms, and R ³ is a substituted or unsubstituted 2 to ³ carbon atoms. Valent hydrocarbon group, R ⁴
Represents a substituted or unsubstituted divalent hydrocarbon group having 1 to 12 carbon atoms. M represents a hydrogen atom, an alkali metal atom or an amine base. ) 2. An electrolytic copper plating bath containing the additive according to claim 1.