JP2017527700A - Composition for electrodeposition of gold-containing layer, use and method thereof - Google Patents

Abstract

The present invention relates to a composition for electrodeposition of a gold-containing layer, a method for electrodeposition of a gold-containing layer using the composition, and the use of a mercaptotriazole compound as an immersion inhibitor. The composition contains a mercaptotriazole compound that acts as an immersion inhibitor. The compositions and methods are suitable for functional or hard gold or gold alloy deposition that can be applied in the industry as contact materials for electrical connectors for high reliability applications.

Description

TECHNICAL FIELD The present invention relates to a composition for electrodepositing a gold-containing layer and a method for electrodeposition of a gold-containing layer using the composition of the present invention. The composition of the present invention contains a mercaptotriazole compound that acts as an anti-immersion additive. The compositions and methods of the present invention are suitable for functional or hard gold or gold alloy deposition that can be applied in the industry as contact materials for electrical connectors for high reliability applications.

BACKGROUND OF THE INVENTION Hard gold or gold alloys of cobalt and nickel are widely used as contact materials for electrical connectors for high reliability applications. A connector having a hard gold end layer is therefore electroplated on a conductive metal layer, for example on a nickel substrate such as nickel plated on copper. Usually, the connector is part of a large electrical device or wire. Selective electroplating techniques are used to deposit a gold or gold alloy layer only at the connector contacts without plating the rest of the electrical circuit. Such selective plating technology significantly reduces the material cost of the connector by limiting the plating area of gold and other noble metals such as palladium and palladium-nickel alloys.

Gold is a precious metal that is usually to be plated on a connector made of a base metal, thus creating a gold replacement problem. Gold substitution is the deposition of gold by an exchange reaction. If the surface to be gold plated is, for example, a nickel surface, the substitution reaction is thought to occur as follows:
2Au ⁺ + Ni ⁰ → 2Au ⁰ + Ni ²⁺
Here, the noble metal gold replaces the base metal nickel. Such metal deposition by exchange or substitution reaction is also called immersion reaction or immersion plating.

  On the other hand, this problem occurs on the functional surface of the electronic component, i.e., the surface of the portion or region of the substrate that should not be plated while the connector is being electroplated and thus not electrically connected. Further, if the electroplating is stopped, for example, at idle, an immersion reaction can occur. The connector surface then remains in the gold deposition bath for some time without being electrically connected.

  In either case, the gold layer is deposited on the non-connection surface by the immersion reaction. Thus, the gold layer is deposited in areas of the substrate that are not desired by the immersion reaction. This immersion gold deposition is undesirable because it consumes more gold than necessary to coat connectors and other electronic components, and causes excessive gold consumption leading to higher manufacturing costs.

  Gold layers deposited on printed wiring, connectors or other electronic device components that are not desired to be plated can also cause defects in the substrate, resulting in a poor final product. Thus, the gold layer must be removed later, which is cumbersome, time consuming and expensive.

  Moreover, the gold layer formed by the immersion reaction has low adhesion to the lower surface. If the part of the soaked gold layer is peeled off from the base, there is a risk that a shortcut will occur when another wiring or other contact metal is accidentally connected.

  Furthermore, the problem of gold immersion increases with the aging of the gold electrolyte.

  Gold soaking can be reduced by improving the design of the plating equipment. However, this requires significant expenditure to redesign and manufacture new equipment parts.

  EP 2309036 (EP2309036B1) discloses a hard gold plating bath that reduces the gold displacement reaction. The effect is due to the mercaptotetrazole compound contained in the plating bath. However, the reduction of the gold substitution reaction is still insufficient. Also, European Patent No. 2309036 (EP2309036B1) does not mention that gold replacement increases as aging of the gold deposition bath proceeds.

  Therefore, it is necessary to inhibit the gold immersion reaction in the electrodeposition bath of the functional pure gold layer and gold alloy layer.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a composition and method for electrodepositing a gold-containing layer with further reduced gold immersion reaction.

  It is a further object of the present invention to provide a method for reducing the gold soaking reaction that increases during the life of the gold electrodeposition composition.

SUMMARY OF THE INVENTION These objects are achieved by the following compositions and methods.

（式中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５及びＲ^６は、以下に定義される通りである）
を有する、前記電気めっき組成物。 An electroplating composition comprising:
(I) at least one source of gold ions, and (ii) at least one mercaptotriazole or a salt thereof, wherein the at least one mercaptotriazole is represented by the following general formula (I) or (II):

(Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are as defined below)
The electroplating composition comprising:

  The mercaptotriazole or salt thereof according to (ii) greatly reduces or substantially inhibits the gold soaking reaction when electrodepositing the gold-containing layer.

A method comprising the following steps,
(I) providing an electroplating composition as defined above;
(Ii) contacting a substrate with the composition; and (iii) applying a current between the substrate and at least one anode, thereby depositing gold or a gold alloy on the substrate. Said method.

  The method is suitable for electrodepositing a gold-containing layer on a substrate. The method greatly reduces or substantially inhibits the gold soaking reaction.

(I) providing a used gold or gold alloy electroplating composition;
(Ii) adding a mercaptotriazole as defined above to the spent gold or gold alloy electroplating composition; and (iii) contacting the substrate with the composition; and (iv) at least one of the substrate and Applying a current to and from the anode, thereby depositing gold or a gold alloy on the substrate.

  The method is suitable for reclaiming spent gold or gold alloy electroplating compositions that have reached an extent that the gold immersion reaction prevents effective use and deposition of the appropriate gold or gold alloy layer. The method greatly reduces or substantially inhibits the gold soaking reaction.

FIG. 1 shows the thickness of a gold alloy layer deposited by an immersion reaction from an electroplating bath containing various mercaptoazole compounds. FIG. 2 shows the thickness of the gold alloy layer deposited by an immersion reaction from an electroplating bath containing various mercaptotriazole compounds.

（式中、Ｒ^１、Ｒ^４は、相互に独立して水素、直鎖状又は分枝鎖状の、飽和又は不飽和（Ｃ_１〜Ｃ_２０）炭化水素鎖、（Ｃ_８〜Ｃ_２０）アラルキル基；置換又は非置換のフェニル基、ナフチル基又はカルボキシル基であり；且つ
Ｒ^２、Ｒ^３、Ｒ^５、Ｒ^６は、相互に独立して−Ｓ−Ｘ、水素、直鎖状又は分枝鎖状の、飽和又は不飽和（Ｃ_１〜Ｃ_２０）炭化水素鎖、（Ｃ_８〜Ｃ_２０）アラルキル基；置換又は非置換のフェニル基、ナフチル基又はカルボキシル基であり；且つ
Ｘは水素、（Ｃ_１〜Ｃ_４）アルキル基又はアルカリ金属イオン、カルシウムイオン、アンモニウムイオン及び第４級アミンから選択される対イオンであり、且つ
Ｒ^２及びＲ^３のうち少なくとも１つは−Ｓ−Ｘであり、Ｒ^５及びＲ^６のうち少なくとも１つは−Ｓ−Ｘである）
を有する、電気めっき組成物に関する。 Detailed Description of the Invention
(I) at least one gold ion source, and (ii) at least one mercaptotriazole or a salt thereof, wherein the at least one mercaptotriazole has the following general formula (I) or (II):

(Wherein R ¹ and R ⁴ are independently of each other hydrogen, linear or branched, saturated or unsaturated (C _{1 to} C ₂₀ ) hydrocarbon chain, (C _{8 to} C ₂₀ ). An aralkyl group; a substituted or unsubstituted phenyl group, naphthyl group, or carboxyl group; and R ² , R ³ , R ⁵ , and R ⁶ are independently of each other —S—X, hydrogen, linear, or A branched, saturated or unsaturated (C ₁ -C ₂₀ ) hydrocarbon chain, (C ₈ -C ₂₀ ) aralkyl group; a substituted or unsubstituted phenyl group, naphthyl group or carboxyl group; and X is hydrogen , A (C ₁ -C ₄ ) alkyl group or an alkali metal ion, a calcium ion, an ammonium ion and a counter ion selected from a quaternary amine, and at least one of R ² and R ³ is —S—X And at least of R ⁵ and R ⁶ One is -S-X)
The present invention relates to an electroplating composition.

  The electroplating composition is suitable for electrodepositing a gold-containing layer on a substrate. The gold-containing layer may be a pure gold layer or a gold alloy layer. Preferably, the gold-containing layer is a gold alloy layer. More preferably, the gold-containing layer is a gold alloy layer used as a so-called functional or hard gold layer. Functional or hard gold layers are particularly resistant to mechanical wear due to their high mechanical stability. Accordingly, gold layers, particularly gold alloy layers, are suitable for use in electrical connectors.

  The mercaptotriazole or salt thereof according to (ii) greatly reduces or substantially inhibits the gold soaking reaction when electrodepositing the gold-containing layer.

  In one embodiment, X is preferably a counter ion selected from alkali metal ions, wherein the alkali metal ions are selected from sodium ions, potassium ions and lithium ions.

In another embodiment, the substituent of the substituted phenyl or naphthyl group of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ is a branched or unbranched (C ₁ -C ₁₂ ) an alkyl group, a branched or unbranched (C ₂ -C ₂₀ ) alkylene group, a branched or unbranched (C ₁ -C ₁₂ ) alkoxy group; a hydroxyl group, And independently selected from halogen. In another embodiment, the halogen is selected from chlorine and bromine.

In solution, mercaptotriazoles of formula (I) can exist in two tautomeric forms:

Formula (I) thus includes both tautomers. Tautomers are particularly relevant when R ¹ is an H atom.

In a preferred embodiment, the at least one mercaptotriazole has the general formula (I) or (II), wherein R ¹ and R ⁴ are independently of each other hydrogen or linear (C ₁ -C ₄ ) an alkyl group, and R ² , R ³ , R ⁵ , R ⁶ are independently of each other —S—X, hydrogen or a linear (C ₁ -C ₄ ) alkyl group; and X is Hydrogen, a methyl group, an ethyl group, or a counter ion selected from sodium ion and potassium ion; and at least one of R ² and R ³ is —S—X, and at least one of R ⁵ and R ⁶ . One is -S-X.

In another preferred embodiment, the at least one mercaptotriazole has the general formula (I) or (II), wherein R ¹ and R ⁴ are independently of one another hydrogen, methyl or ethyl. And R ² , R ³ , R ⁵ , R ⁶ are independently of each other —S—X, hydrogen, methyl group or ethyl group, and X is hydrogen, sodium ion or potassium ion, and R ^At least one of ² and R ³ is —S—X, and at least one of R ⁵ and R ⁶ is —S—X.

In another preferred embodiment, the at least one mercaptotriazole has the general formula (I) or (II), wherein R ¹ , R ⁴ are independently of each other hydrogen or a methyl group, and R ² , R ³ , R ⁵ , R ⁶ are each independently —S—X, hydrogen or a methyl group, and X is hydrogen, sodium ion or potassium ion, and at least of R ² and R ³ one is a -S-X, at least one of ^{R 5} and ^{R 6} are -S-X.

In a further preferred embodiment, the at least one mercaptotriazole has the general formula (I), wherein R ¹ , R ² , R ³ and X have the meanings defined above.

  In an even more preferred embodiment, the at least one mercaptotriazole is 5-mercapto-1,2,3-triazole; 4,5-dimercapto-1,2,3-triazole; 5-mercapto-1,2,4. -Triazole; 3-mercapto-1,2,4-triazole; 3,5-dimercapto-1,2,4-triazole; 3-mercapto-4-methyl-1,2,4-triazole; 5-phenyl-1H Selected from the group comprising -1,2,4-triazole-3-thiol and its salts.

  In an even more preferred embodiment, the at least one mercaptotriazole is 5-mercapto-1,2,3-triazole; 4,5-dimercapto-1,2,3-triazole; 5-mercapto-1,2,4. -Triazole; selected from the group comprising 3-mercapto-1,2,4-triazole; 3,5-dimercapto-1,2,4-triazole and salts thereof.

  In an even more preferred embodiment, the at least one mercaptotriazole is 5-mercapto-1,2,3-triazole; 3-mercapto-4-methyl-1,2,4-triazole; 5-phenyl-1H-1 , 2,4-triazole-3-thiol; selected from 3-mercapto-1,2,4-triazole and salts thereof.

  In an even more preferred embodiment, the at least one mercaptotriazole is selected from 5-mercapto-1,2,3-triazole and salts thereof. Mercaptotriazole compounds are commercially available or can be prepared by methods well known in the art.

  In one embodiment, the at least one mercaptotriazole has a concentration in the electroplating composition ranging from 1 mg / l to 1 g / l. Preferably the concentration is below 1 g / l. More preferably, the concentration is between 1 mg / l and 900 mg / l, even more preferably between 1 mg / l and 500 mg / l, even more preferably between 5 mg / l and 100 mg / l, even more preferably between 20 mg / l and 100 mg / l. It is a range. If the concentration of at least one mercaptotriazole is too high, electrodeposition of the gold-containing layer is completely prevented or the electrodeposited gold or gold alloy layer does not adhere well to the surface of the substrate.

  When one or more mercaptotriazoles are added to the gold or gold alloy electroplating composition, the gold immersion reaction is inhibited, but the appearance of the gold alloy is not impaired. Further, the functional characteristics of the gold or hard gold layer such as contact resistance and hardness are not impaired. Contact resistance is maintained at the desired low level, and the gold layer is sufficiently hard for commercial electrical contacts for electronic devices. Furthermore, by adding one or more mercaptotriazoles according to the invention to the gold or gold alloy electroplating composition, the advantageous functional properties of the high wear resistance of the gold or hard gold layer, in particular the hard gold layer, are not impaired. .

  The electroplating composition further comprises (i) at least one gold ion source. The gold ion source can be selected from a gold (I) ion source and a gold (III) ion source. The gold (I) ion source can be selected from the group of gold (I) salts including gold cyanide compounds, gold thiosulfate compounds, gold sulfite compounds, and gold (I) halides. The gold cyanide compound may be selected from an alkali metal cyanide such as potassium gold cyanide or sodium gold cyanide; and ammonium gold cyanide. The gold thiosulfate compound may be selected from an alkali metal gold thiosulfate such as trisodium gold thiosulfate or tripotassium gold trithiosulfate. The gold sulfite compound may be selected from an alkali metal gold sulfite such as sodium gold sulfite or potassium gold sulfite; and gold ammonium sulfite. The gold (I) halide can be gold (I) chloride. The gold (III) ion source can be a gold (III) halide, such as gold (III) trichloride. Preferably, the gold ion source is an alkali metal cyanide compound, such as potassium gold cyanide or sodium gold cyanide. More preferably, the source of gold ions is potassium gold cyanide such as potassium dicyanogold (I) or potassium tetracyanogold (III); or sodium gold cyanide such as sodium dicyanogold (I) or tetracyanogold (III ) Sodium acid. Even more preferably, the gold ion source is potassium dicyanoaurate (I) or potassium tetracyanoaurate (III). Potassium cyanide cyanide has better solubility than other gold compounds.

  In one embodiment where the gold alloy layer deposited from the electroplating composition of the present invention is a hard gold layer, the gold ion source is preferably a gold cyanide compound, more preferably an alkali metal cyanide, such as potassium gold cyanide. Or sodium gold cyanide; or ammonium gold cyanide. When the gold ion source is a gold cyanide compound, a functional or hard gold alloy layer with a high gold content can be best electrodeposited. In this case, the gold ion is contained in the electroplating composition in the form of a gold-cyanide complex, preferably as an alkali metal ion-gold-cyanide complex, more preferably as a potassium ion-gold-cyanide complex. These complexes are particularly suitable for electrodepositing hard gold alloy layers with a high gold content. The same is true for electrodeposition of gold-containing layers from electrolytes used at high current densities. This is because gold compounds other than gold cyanide complex, alkali metal ion-gold-cyanide complex, or potassium ion-gold-cyanide complex have low stability at high current density.

  In one embodiment, the at least one gold ion source is in the electroplating composition in the range of 1 g / l to 50 g / l, preferably in the range of 5 g / l to 50 g / l, more preferably 10 g / l to 50 g / l. And even more preferably in the range of 5 g / l to 30 g / l, even more preferably in the range of 5 g / l to 20 g / l, still more preferably in the range of 10 g / l to 20 g / l. The tendency to deposit gold by the immersion reaction of the electroplating composition increases with the gold concentration contained in the composition.

  In one embodiment, the electroplating composition may further comprise a complexing agent for gold ions. Complexing agents for gold ions include alkali metal cyanides such as potassium cyanide, sodium cyanide, ammonium cyanide; thiosulfuric acid and its salts such as sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate; sulfurous acid and its salts such as Potassium sulfite, ammonium sulfite, carboxylic acids such as sorbic acid; hydroxycarboxylic acids such as citric acid and malonic acid; aminocarboxylic acids such as ethylenediaminetetraacetic acid, iminodiacetic acid, nitrilotriacetic acid, 1,2-diaminocyclohexanetetraacetic acid, Bis-2-aminoethyl ether tetraacetic acid, diethylenetriaminepentaacetic acid; mineral acids such as phosphoric acid, sulfuric acid, boric acid; phosphonic acids such as 1-hydroxyethane-1,1-diphosphonic acid, 1-hydroxyethane-1,2 -Diphosphonic acid, aminoto Limethylenephosphonic acid, ethylenediaminetetramethylphosphonic acid, hexamethylenediaminotetramethylphosphonic acid; salts of said acids, such as alkali metal salts, alkaline earth metal salts; preferably sodium salts and potassium salts; amines such as tetraethylenepentamine, trimethylamine Selected from ethylenetetraamine, triethylamine, diethylenetriamine and ethylenediamine. The complexing agent can also function as a conductive salt.

  In one embodiment where the gold ion source is an alkali metal cyanide compound, the complexing agent is preferably not a cyanide compound, more preferably not an alkali metal cyanide.

  In one embodiment, the complexing agent is in the electroplating composition in the range of 1 g / l to 200 g / l, preferably in the range of 1 g / l to 100 g / l, more preferably in the range of 10 g / l to 50 g / l. Has a concentration.

  In one embodiment, the electroplating composition may further include at least one alloyed metal ion source. The metal of the alloying metal ion is selected from cobalt, nickel and iron. Gold-cobalt alloys, gold-nickel alloys and gold-iron alloys belong to hard gold alloys.

  The precipitate of hard gold alloy has a gold content in the range of 99.00 mass% to less than 99.99 mass%. The content of alloying metals cobalt, nickel and / or iron can range from less than 0.03% to more than 0.3% by weight for hard gold alloys (ASTM B488-11, section 7). Alloying metals impart the highest hardness and highest wear resistance to gold alloys required for industrial applications such as contact materials for electrical connectors for high reliability applications (ASTM B488-11, Appendix X1). At the same time, hard gold alloys maintain high electrical conductivity, which is even more important for their use in electrical connectors. In contrast, gold deposits with a gold content greater than 99.90% by weight are low in hardness (ASTM B488-11, sections 4 and 7) and have low wear resistance and are therefore suitable for electrical connector applications. Not suitable.

  The alloying metal ions are selected from cobalt (II) ions, nickel (II) ions, iron (II) ions, and iron (III) ions. Alloying metal ion sources include cobalt carbonate, cobalt sulfate, cobalt gluconate, potassium cobalt cyanide, cobalt bromide, cobalt chloride, nickel chloride, nickel bromide, nickel sulfate, nickel tartrate, nickel phosphate, nickel nitrate, sulfamine Selected from nickel acid, iron chloride, iron bromide, iron citrate, iron fluoride, iron iodide, iron nitrate, iron oxalate, iron phosphate, iron pyrophosphate, iron sulfate, and iron acetate.

  In one embodiment, the at least one alloying metal ion source is in the electroplating composition in the range of 0.001 g / l to 5 g / l, preferably in the range of 0.05 g / l to 2 g / l, more preferably 0. Having a concentration in the range of .05 g / l to 1 g / l.

  In one embodiment, the electroplating composition may further include a complexing agent for alloying metal ions. Complexing agents for alloying metal ions include sulfurous acid and its salts, such as potassium sulfite, ammonium sulfite, carboxylic acids such as sorbic acid; hydroxycarboxylic acids such as citric acid and malonic acid; aminocarboxylic acids such as ethylenediamine Tetraacetic acid, iminodiacetic acid, nitrilotriacetic acid, 1,2-diaminocyclohexanetetraacetic acid, bis-2-aminoethyl ether tetraacetic acid, diethylenetriaminepentaacetic acid; mineral acids such as phosphoric acid, sulfuric acid, boric acid, thiosulfuric acid; phosphones Acids such as 1-hydroxyethane-1,1-diphosphonic acid, 1-hydroxyethane-1,2-diphosphonic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylphosphonic acid, hexamethylenediaminotetramethylphosphonic acid; Salts, such as alkali metal salts Slightly alkaline earth metal salts; preferably sodium and potassium salts; amine, e.g. tetraethylene pentamine, triethylene tetramine, triethylamine, may be selected from diethylenetriamine and ethylenediamine. The complexing agent can also function as a conductive salt.

  The complexing agent for alloying the metal ions may have a concentration in the electroplating composition in the range of 1 to 200 g / l, preferably in the range of 20 to 150 g / l. When the same complexing agent is used for gold ions and alloying metal ions, the concentration of complexing agent is the sum of the concentrations required for gold ions and alloying metal ions.

  In one embodiment, the electroplating composition may further comprise at least one brightener. The at least one brightener is selected from pyridine and quinoline compounds. The pyridine and quinoline compounds are selected from substituted pyridines and substituted quinoline compounds. Preferably, the substituted pyridine and substituted quinoline compounds are selected from monocarboxylic acids or dicarboxylic acids, monosulfonic acids or disulfonic acids, monothiol or dithiol substituted pyridines, quinolines, pyridine derivatives or quinoline derivatives. The pyridine or quinoline derivative can be substituted with the same or different substituents at one or more positions. More preferably, the pyridine derivative or quinoline derivative is selected from derivatives substituted at the 3-position of the pyridine ring. Even more preferably, the pyridine derivative or quinoline derivative is selected from pyridine or quinoline carboxylic acid, pyridine or quinoline sulfonic acid, and pyridine or quinoline thiol. Even more preferably, the pyridine or quinolinecarboxylic acid is selected from the respective ester and its amide. Even more preferably, the pyridine or quinolinecarboxylic acid is pyridine-3-carboxylic acid (nicotinic acid), quinoline-3-carboxylic acid, 4-pyridinecarboxylic acid, nicotinic acid methyl ester, nicotinamide, nicotinic acid diethylamide, pyridine- Selected from 2,3-dicarboxylic acid, pyridine-3,4-dicarboxylic acid and pyridine-4-thioacetic acid. Even more preferably, the pyridine or quinoline sulfonic acid is selected from 3-pyridine sulfonic acid, 4-pyridine sulfonic acid and 2-pyridine sulfonic acid. Most preferably, the at least one brightener is selected from pyridine-3-carboxylic acid (nicotinic acid), nicotinamide, and 3-pyridinesulfonic acid.

  The at least one brightener may have a concentration in the electroplating composition in the range of 0.5 g / l to 10 g / l, preferably in the range of 1 g / l to 10 g / l.

Brighteners advantageously cause the deposition of a brilliant gold layer over a wide current density range of ² A / dm ^{2 to} 100 A / dm ² .

  In one embodiment, the electroplating composition may further comprise at least one acid. Preferably, the at least one acid is an organic acid or an inorganic acid. More preferably, the at least one acid is selected from phosphoric acid, citric acid, malic acid, oxalic acid, formic acid and polyethyleneaminoacetic acid. At least one acid is used to adjust the pH value of the electroplating composition. At least one acid may function as a complexing agent and / or as a conductive salt.

  The at least one acid may have a concentration in the electroplating composition ranging from 1 g / l to 200 g / l.

In one embodiment, the electroplating composition may further comprise at least one alkaline compound. At least one alkaline compound is used to adjust the pH value of the electroplating composition. The at least one alkaline compound is selected from sodium, potassium and magnesium hydroxides, sulfates, carbonates, phosphates, hydrogen phosphates, and other salts. Preferably, the at least one alkaline compound is selected from KOH, NaOH, K ₂ CO ₃ , Na ₂ CO ₃ , K ₂ HPO ₄ , Na ₂ HPO ₄ , NaH ₂ PO ₄ and mixtures thereof.

  In one embodiment, the electroplating composition is an acidic electroplating composition. The electroplating composition has a pH value of less than 7, more preferably less than 5, still more preferably 1 to 6, still more preferably 3 to 6, still more preferably 3.5 to 5.5, still more preferably 3. .5 to 4.5.

  In one embodiment where the gold alloy layer deposited from the electroplating composition of the present invention is a hard gold layer, the electroplating composition is preferably an acidic electroplating composition. When the electrodeposition composition is acidic, it can best electrodeposit a functional or hard gold alloy layer with a high gold content.

  In one embodiment, the electroplating composition may include additional additives such as surfactants and / or grain refiners.

The present invention further comprises the following steps:
(I) providing an electroplating composition as defined above;
(Ii) contacting a substrate with the composition; and (iii) applying a current between the substrate and at least one anode, thereby depositing a gold-containing layer on the substrate. .

  The method is suitable for electrodepositing a gold-containing layer on a substrate. The method uses the electroplating composition of the present invention containing at least one mercaptotriazole or salt thereof as an immersion inhibitor. The method greatly reduces or substantially inhibits the gold soaking reaction. Thus, the method of the present invention significantly reduces gold consumption and increases the life of the gold or gold alloy electroplating composition. The gold-containing layer can be a pure gold layer or a gold alloy layer, preferably a gold alloy layer, more preferably a hard gold layer.

  The gold-containing layer can be deposited on the entire surface of the substrate or on a portion of the surface of the substrate. Depositing a metal layer on part of the surface of the substrate is also referred to as selective deposition or plating of the metal layer. In this way, the gold-containing layer can be selectively electroplated on the substrate.

  The selective plating can be performed by a known method such as a masking method, a spot plating method, or a brush plating method. The masking method involves the use of a mask that covers portions of the substrate surface that are not to be plated. In spot plating, only the portion of the substrate that is to be metallized is electrically connected and plated. The brush plating method applies an anode covered with a brush locally to the area of the substrate to be plated, where the brush contains a metal plating solution.

  In either case of metal deposition or selective metal deposition on the entire surface of the substrate, the conductive surface of the substrate or a portion of the substrate surface is in contact with the electroplating composition of the present invention. The surface of the substrate or a part of the substrate surface is electrically connected as a cathode. A voltage is applied between the cathode and at least one anode, and current is supplied to the substrate surface or a portion of the substrate surface.

The current density of the current ^{is, 0.05A / dm 2 ~100A / dm} 2, preferably ^{1A / dm 2 ~50A / dm 2} , more preferably ^{1A / dm 2 ~40A / dm 2} , more preferably 5A / dm ² It may be in the range of ˜40 A / dm ² , even more preferably in the range of 5 A / dm ^{2 to} 20 A / dm ² . Applying a higher current density during electrodeposition of the gold-containing layer advantageously increases the electrodeposition rate and the productivity of the electrodeposition method.

  The plating time can vary. The time depends on the desired thickness of the gold-containing layer on the substrate. The thickness of the gold-containing layer is in the range of 0.01 μm to 5 μm, preferably 0.05 μm to 3 μm, more preferably 0.05 μm to 1.5 μm.

  During plating, the electroplating composition of the present invention can be maintained at a temperature in the range of 40 ° C to 70 ° C.

  During plating, the electroplating composition of the present invention can be allowed to stand or be agitated. Agitation is, for example, mechanical movement of the aqueous plating bath, for example by shaking the liquid, stirring or continuous pumping or substantially by sonication or by high temperature or gas supply, for example inerting the aqueous plating bath This can be done by purging with gas or simply with air.

  The method of electrodepositing the gold-containing layer onto the substrate can further include a pretreatment step prior to contacting the substrate with the electroplating composition of the present invention. The pretreatment step is typically activation of the substrate surface using an acid or an acid containing fluoride.

  The method of electrodepositing the gold-containing layer onto the substrate can include an additional plating step prior to contacting the substrate with the electroplating composition of the present invention. Before the gold or gold alloy layer is electrodeposited on the substrate, a further metal layer is deposited on the substrate by a further plating step. The metal of the further metal layer may be selected from iron, nickel, nickel-phosphorous alloy, copper, palladium, silver, cobalt and their alloys, preferably nickel, nickel-phosphorous alloy, and copper. The above metal plating methods are known in the art.

  In one embodiment, the substrate to be plated with the gold-containing layer, i.e. the gold or gold alloy layer, is a conductive material. The conductive material may be a metal. The metal may be any metal that can undergo a gold immersion reaction. The metal may be selected from iron, nickel, nickel-phosphorous alloy, copper, palladium, silver, cobalt, and alloys thereof. Preferably, the substrate is made from iron or copper and covered with a nickel layer.

  In one embodiment, the substrate to be plated having a gold-containing layer is an electrical connector. Preferably, the substrate is an electrical connector contact interface. More preferably, the substrate is a plug connector. The substrate can be part of a printed circuit board, electrical wire or electrical equipment.

The present invention further comprises the following steps:
(I) providing a used gold or gold alloy electroplating composition;
(Ii) adding a mercaptotriazole as defined above to the spent gold or gold alloy electroplating composition; and (iii) contacting the substrate with the composition; and (iv) at least one with the substrate. It relates to a method comprising applying a current between two anodes, thereby depositing gold or a gold alloy on the substrate.

  The method is suitable for reclaiming used gold or gold alloy electroplating compositions. On the other hand, the used electroplating composition may be an aged gold or gold alloy electroplating composition. Aged electroplating composition means herein a composition that has already been used for electroplating to which the gold immersion reaction has reached a level that prevents effective use and deposition of the appropriate gold or gold alloy layer. . The criterion for evaluating the degree of aging is the deposition rate due to the immersion reaction. In newly made gold or gold alloy electroplating baths, the deposition rate is about 5 nm / 5 min at 60 ° C. The deposition rate increases with the life of the electroplating bath. When the deposition rate reaches 80-100 nm / 5 minutes at 60 ° C., it is usually necessary to replace the gold or gold alloy electroplating bath. Even when the deposition rate reaches 20-40 nm / 5 min at 60 ° C., the gold or gold alloy electroplating bath is no longer suitable for industrial plating applications because the immersion reaction has already caused a large loss of gold. In contrast, the method of the present invention greatly reduces or substantially inhibits the gold immersion reaction in aged gold or gold alloy electroplating compositions. Thus, the method of the present invention regenerates an aged gold or gold alloy electroplating composition and greatly increases the life of the gold or gold alloy electroplating composition.

The present invention further comprises the following steps:
(I) preparing an aging gold or gold alloy electroplating composition;
(Ii) adding a mercaptotriazole as defined above to the aged gold or gold alloy electroplating composition; and (iii) contacting the substrate with the composition; and (iv) the substrate and at least one anode. And applying a current therebetween to thereby deposit gold or a gold alloy on the substrate.

  The thickness of the gold layer can be measured with X-ray fluorescence (XRF) as known in the art. XRF thickness measurement utilizes characteristic fluorescent radiation emitted from a sample (substrate, precipitate) that is excited with X-rays. By evaluating the strength and assuming the layer structure of the sample layer, the thickness can be calculated.

  On the other hand, the used electroplating composition may be a gold or gold alloy electroplating composition that has not been used for a while in the electroplating process. Not being used means that the gold or gold alloy electroplating composition is not electrically connected and the gold or gold alloy is not electrodeposited from the composition. It has been observed that gold immersion plating problems also increase while gold or gold alloy electrodeposition compositions are not used in the electroplating process. When the mercaptotriazole of the present invention is added to a gold or gold alloy electrodeposition composition that has not been used temporarily, the gold soaking reaction is greatly reduced or substantially inhibited when the composition is used again.

The present invention further comprises the following steps:
(I) preparing a gold or gold alloy electroplating composition that has not been temporarily used;
(Ii) adding a mercaptotriazole as defined above to the temporarily unused gold or gold alloy electroplating composition; and (iii) contacting a substrate with the composition; and (iv) It relates to a method comprising applying a current between the substrate and at least one anode, thereby depositing gold or a gold alloy on the substrate.

  The invention further relates to a substrate electroplated with a gold-containing layer obtained by one of the methods of the invention.

  The invention further relates to the use of the mercaptotriazole of the invention as an immersion inhibitor in an electrodeposition composition, preferably in an electrodeposition composition for a gold-containing layer.

  The electroplating composition and method of the present invention greatly reduces or substantially inhibits the gold immersion reaction. Thus, gold does not deposit on unnecessary portions of the substrate surface. This saves money because gold loss and production of defective products are minimized. Furthermore, the life of the gold or gold alloy electroplating composition is greatly increased.

  In contrast to the triazole compounds of the present invention, tetrazole compounds are significantly less effective at reducing gold soaking reactions. Also, tetrazole compounds are less stable in gold or gold alloy electroplating compositions, which leads to high consumption of tetrazole compounds and does not work well due to increased concentrations of degradation products during processing, and The life of the gold electrolyte is reduced.

Examples Example 1
A copper plate electroplated with nickel was used as the substrate. The substrate was rinsed with water and pretreated by oxidative activation (UniClean 675, a product of Atotech Deutschland GmbH) for 15 seconds at room temperature (about 20 ° C.), rinsed again with water and then rinsed with deionized water.

A newly made gold-cobalt alloy plating bath (Aurocor HSC, gold 15 g / l, pH 4.5, Atotech Deutschland) further containing 500 mg / l sodium salt of 5-mercapto-1,2,3-triazole as an immersion inhibitor. The copper panel A was electroplated using a product from GmbH. Electroplating was carried out at a current density of 10 A / dm ² and a temperature of 60 ° C. for 150 seconds with stirring.

  After plating, the substrate was completely covered with a glossy, uniform, well-adhered gold-cobalt alloy layer having a thickness of 5 μm.

Example 2
A copper panel electroplated with nickel and pretreated as described in Example 1 was used as the substrate. In order to mask the portion that should not be plated, half the area of the substrate was covered with tethered tape.

  Copper panel B was contacted with an aged gold cobalt alloy plating bath (Aurocor HSC, gold 15 g / l, pH 4.5, product of Atotech Deutschland GmbH) containing no mercaptotriazole compound.

  As outlined in Table 1, copper panels C-F were separated into separate newly made gold-cobalt alloy plating baths (Aurocor HSC, 15 g / gold) containing 500 mg / l each of mercaptotriazole or mercaptotetrazole compounds. 1, pH 4.5, product of Atotech Deutschland GmbH).

  While in contact with the gold cobalt alloy plating bath, the copper panels BF were not electrically connected. Therefore, metal deposition by electroplating was impossible. 50 ml of a gold-cobalt alloy plating bath containing each mercaptoazole compound was used for each panel. The gold-cobalt alloy plating bath was kept at a temperature of 60 ° C. and constantly stirred at 400 rpm (number of rotations per minute). Contact with each panel was made for 5 minutes.

After the panel was brought into contact with each gold cobalt alloy plating bath, the thickness of the gold alloy layer deposited by the immersion reaction was measured by XRF. The results are summarized in Table 1 and shown in FIG.

  In general, the gold alloy layer was deposited on the portion of the substrate panel not covered with tape, and the gold alloy was not deposited on the portion of the substrate panel covered with tape. A gold alloy layer of minimal thickness was deposited by immersion reaction from a gold alloy bath containing mercaptotriazole according to the present invention. In contrast, from a gold alloy bath containing no mercaptoazole compound or a gold alloy bath containing a comparative mercaptotetrazole compound, a gold alloy layer having a significantly higher thickness was deposited by immersion reaction. Further, Comparative Compound D caused undesirable precipitates in the gold alloy bath. In contrast to the triazole compounds of the present invention, tetrazole compounds exhibit low stability in gold alloy electrolytes, which leads to higher consumption of tetrazole compounds and dysfunction due to increased concentrations of degradation products during processing. Leads to a reduction in the life of the gold electrolyte. Thus, the mercaptotriazole compounds of the present invention greatly reduce or substantially inhibit the gold soak reaction.

Example 3
A copper panel electroplated with nickel and pretreated as described in Example 1 was used as the substrate.

  An aged gold cobalt alloy electroplating bath (Aurocor HSC, product of Atotech Deutschland GmbH) was first treated with activated carbon at 60 ° C. for 30 minutes.

  In step 1, the gold plating bath was kept at 60 ° C. while being immersed in the gold plating bath for various times without being electrically connected. After 30 seconds in the bath, no gold was deposited on the substrate. However, after 2 minutes and 3 minutes, the gold layer was deposited on the substrate by an immersion reaction.

  In subsequent step 2, sodium salt of 5-mercapto-1,2,3-triazole, 25 mg / l, was added to the gold plating bath, and the substrate was again placed in the gold plating bath for various times without being electrically connected. Soaked. Even after 30 seconds, 2 minutes, 3 minutes, and even 5 minutes after contact with the gold plating bath, gold was not deposited on the substrate by the immersion reaction.

  Thus, the mercaptotriazole compounds of the present invention significantly reduce or substantially inhibit the gold immersion reaction in aged gold or gold alloy electroplating compositions. Accordingly, the mercaptotriazole compound of the present invention regenerates an aged gold or gold alloy electroplating composition and greatly increases the life of the gold or gold alloy electroplating composition.

Example 4
On the first day, Example 3 was repeated with the same results. After step 2, the bath was left unused for 1 day without being used in the plating.

  On the second day, the substrate was again brought into contact with the gold plating bath according to Step 1 of Example 3. After 3 minutes in the bath, no gold was deposited on the substrate. However, after 5 minutes, a gold layer was deposited on the substrate by an immersion reaction.

  Thereafter, Step 2 of Example 3 was performed. Even after 5 minutes of contact with the gold plating bath, no gold was deposited on the substrate by the immersion reaction.

  Thus, adding the mercaptotriazole compound of the present invention to a gold or gold alloy electrodeposition composition that has not been used temporarily can also significantly reduce the gold immersion reaction when the composition is used again. Or almost inhibit.

Example 5
A copper panel electroplated with nickel was used as the substrate. The copper panels were electroplated with nickel and pretreated as summarized in Table 2 below. After each process step listed in Table 2, the copper panel was rinsed with water. In order to mask the portion that should not be plated, half the area of the substrate was covered with tethered tape.

  Copper panel G was contacted with an aged gold cobalt alloy plating bath (Aurocor SC, gold 4 g / l, pH 4.5, product of Atotech Deutschland GmbH) not containing a mercaptotriazole compound.

  As outlined in Table 3, the copper panels H to M were separated from a separate aged gold-cobalt alloy plating bath (Aurocor SC, gold 4 g / l, pH 4.5, Atotech Deutschland) each containing 50 mg / l of a mercaptotriazole compound. Contact with a product of GmbH).

  While in contact with the gold cobalt alloy plating bath, the nickel coated and pretreated copper panels GM were not electrically connected. Therefore, metal deposition by electroplating was impossible. 50 ml of a gold-cobalt alloy plating bath containing each mercaptotriazole compound was used for each panel. The gold-cobalt alloy plating bath was kept at a temperature of 60 ° C., and constantly stirred at 400 rpm (the number of rotations per minute). Contact with each panel was made for 5 minutes.

After the panel was brought into contact with each gold cobalt alloy plating bath, the thickness of the gold alloy layer deposited by the immersion reaction was measured by XRF. The results are summarized in Table 3 and shown in FIG.

  Since the gold concentration of the plating bath of Example 5 was significantly lower than that of Example 2, the thickness of the gold cobalt layer (panel G) deposited from the plating bath containing no mercaptotriazole compound was lower than that of Example 2 (panel B). . Since the concentration of 5-mercapto-1,2,3-triazole in the plating bath of Example 5 was significantly lower than in Example 2, the gold deposited from the plating bath containing 5-mercapto-1,2,3-triazole The cobalt layer thickness (panel H) was higher than Example 2 (panel C).

  In general, the gold alloy layer was deposited on the portion of the substrate panel not covered with the tape, and the gold alloy was not deposited on the portion of the substrate panel covered with the tape. A thin gold alloy layer was deposited by immersion reaction from a gold alloy bath containing mercaptotriazole according to the present invention. In contrast, a significantly higher gold alloy layer was deposited by immersion reaction from a gold alloy bath containing no mercaptotriazole compound or a comparative amino-modified mercaptotriazole compound. Thus, the mercaptotriazole compounds of the present invention greatly reduce the gold soaking reaction.

Example 6
Effect of Mercaptotriazole Compound on Deposition Rate, Hardness and Adhesion of Deposited Gold Layer A copper panel electroplated with nickel and pretreated as described in Example 1 was used as the substrate.

  First, as described in Example 5, the immersion reaction of an aged gold cobalt alloy plating bath (Aurocor HSC, gold 15 g / l, pH 4.5, product of Atotech Deutschland GmbH) was measured.

  Copper panel N was plated by a dipping reaction from a portion of the plating bath containing no mercaptotriazole compound. Copper panel P was plated by a dipping reaction from a portion of the plating bath containing 25 mg / l sodium salt of 5-mercapto-1,2,3-triazole. The thickness of the gold-cobalt alloy layer deposited by the immersion reaction at the panel N was 82 ± 6 nm, and the thickness at the panel P was 10 ± 4 nm.

  Thereafter, the same aged gold-cobalt alloy plating bath was used to electrodeposit the gold-cobalt alloy layer on the panel unless otherwise noted in the later paragraphs. The deposition rate, hardness and adhesion of the deposited alloy layer were measured. Electrodeposition was performed as described in Example 1.

Deposition rate:
Copper panels Q1-Q4 were plated from a separate aging plating bath containing no mercaptotriazole compound. Copper panels R1-R4 were plated from a separate aging plating bath containing 25 mg / l of the sodium salt of 5-mercapto-1,2,3-triazole. The current density varied from 5 A / dm ² to 20 A / dm ² as outlined in Table 4. The thickness of the electrodeposited gold-cobalt alloy layer was measured by XRF. The results are summarized in Table 4.

  The deposition rate of the gold-cobalt alloy from the aging plating bath in the absence or presence of mercaptotriazole was approximately the same. Therefore, the presence of the mercaptotriazole according to the present invention in the gold electrodeposition bath did not affect the deposition rate.

Hardness:
Copper panel S was plated from a portion of an aging plating bath that did not contain a mercaptotriazole compound. Copper panel T was plated from a portion of an aging plating bath containing 25 mg / l of the sodium salt of 5-mercapto-1,2,3-triazole. Electroplating was performed at a current density of 15 A / dm ² for 150 seconds to obtain a gold-cobalt alloy layer having a thickness of about 5 μm. The hardness of the gold-cobalt alloy layer was measured by a Vickers hardness test using an XRF-SDD (X-ray fluorescence-silicon drift detector) instrument, Fischerscope X-RAY XDRL, manufactured by Fischer Technology, Inc. The hardness of the gold-cobalt alloy layer electrodeposited on the panel S was 180 ± 10 HV0.001, and the hardness of the panel Ta was 178 ± 10 HV0.001.

  The hardness of the gold-cobalt alloy layer deposited from the aging plating bath in the absence or presence of mercaptotriazole was approximately the same. Therefore, the presence of the mercaptotriazole according to the present invention in the gold electrodeposition bath did not affect the hardness of the deposited gold-containing layer.

Adhesion:
A newly made gold-cobalt alloy plating bath (Aurocor HSC, gold 15 g / l, pH 4.5, product of Atotech Deutschland GmbH) was used for adhesion measurements. The adverse effects on the deposition of the electrodeposited gold-containing layer can best be detected when performing deposition using a newly made gold or gold alloy plating bath. This is because these plating baths have little immersion reaction and the deposits usually have good adhesion.

  Copper panels U1-U2 were plated from a separate newly made plating bath containing no mercaptotriazole compound. Copper panels V1-V2 were plated from a separate freshly made plating bath containing 50 mg / l of the sodium salt of 5-mercapto-1,2,3-triazole.

First, the copper panels U1 and V1 were brought into contact with each plating bath for 5 minutes without being electrically connected. Thus, in panel V1, mercaptotriazole was adhered to the nickel surface of the panel. Thereafter, copper panels U1 and V1 were electroplated from each plating bath at 5 A / dm ² for 72 seconds, thereby electrodepositing a gold-cobalt alloy layer onto the panel. The adhesion of the gold-cobalt alloy layer to the panel surface was measured by a bending test and a tape test. The bending test was performed as follows: a portion of the panel to be tested was bent once at 90 °. The adhesion was considered good when no bubbles were generated in the deposited gold layer or when the flakes of the deposited gold layer were not peeled off from the bent portion. In the tape test, tessa tape 4102 having an adhesive force of about 6 N / cm was attached to a gold-cobalt plated panel and then peeled off from the panel surface. When the tape did not peel part or all of the gold-cobalt layer, the adhesion was at least 6 N / cm, which was considered to be good adhesion. On the other hand, when the tape peeled off part or all of the gold-cobalt layer, the adhesion was insufficient.

Bending and tape tests revealed that the adhesion of the gold-cobalt alloy layer to the nickel surfaces of panels U1 and V1 was nearly identical and good. First, the copper panels U2 and V2 were brought into contact with the respective plating baths, and a thin gold-cobalt layer (first gold-cobalt layer) having a thickness of 0.1 to 0.2 μm was electrodeposited. Thereafter, the plated copper panel was brought into contact with each plating bath for 10 seconds without being electrically connected. Thus, for panel V2, mercaptotriazole was deposited on the surface of the deposited gold-cobalt layer. Thereafter, copper panels U2 and V2 were electroplated from each plating bath at 5 A / dm ² for 72 seconds, thereby electrodepositing a second gold-cobalt alloy layer on the panel. The adhesion of the second gold-cobalt alloy layer to the surface of the first gold-cobalt layer was measured by a bending test and a tape test as described above.

  Bending and tape tests revealed that the adhesion of the second gold-cobalt alloy layer to the surface of the first gold-cobalt layer of panels U2 and V2 was nearly identical and good.

  The adhesion of the gold-cobalt alloy layer deposited from the newly created plating bath in the absence or presence of mercaptotriazole was nearly identical. Therefore, the presence of the mercaptotriazole according to the present invention in the gold electrodeposition bath did not affect the adhesion of the deposited gold-containing layer.

Claims (12)

An electroplating composition comprising:
(I) at least one gold ion source, and (ii) at least one mercaptotriazole or a salt thereof, wherein the at least one mercaptotriazole has the following general formula (I) or (II):

(Wherein R ¹ and R ⁴ are independently of each other hydrogen, linear or branched, saturated or unsaturated (C _{1 to} C ₂₀ ) hydrocarbon chain, (C _{8 to} C ₂₀ ). An aralkyl group; a substituted or unsubstituted phenyl group, naphthyl group, or carboxyl group; and R ² , R ³ , R ⁵ , and R ⁶ are independently of each other —S—X, hydrogen, linear, or A branched, saturated or unsaturated (C ₁ -C ₂₀ ) hydrocarbon chain, (C ₈ -C ₂₀ ) aralkyl group; a substituted or unsubstituted phenyl group, naphthyl group or carboxyl group; and X is hydrogen , A (C ₁ -C ₄ ) alkyl group or an alkali metal ion, a calcium ion, an ammonium ion and a counter ion selected from a quaternary amine, and at least one of R ² and R ³ is —S—X And less than R ⁵ and R ⁶ Both are -S-X)
The electroplating composition comprising: The at least one mercaptotriazole has the general formula (I) or (II);
In that case, R ¹ and R ⁴ are each independently hydrogen or a linear (C ₁ -C ₄ ) alkyl group, and R ² , R ³ , R ⁵ , R ⁶ are independently- S—X, hydrogen or a linear (C ₁ -C ₄ ) alkyl group, and X is hydrogen, a methyl group, an ethyl group, or a counter ion selected from sodium and potassium ions; and R ² And at least one of R ³ is —S—X, and at least one of R ⁵ and R ⁶ is —S—X.   The composition according to claim 1 or 2, wherein the at least one mercaptotriazole has a concentration in the range of 1 mg / l to 1 g / l.   4. A composition according to any one of claims 1 to 3, further comprising at least one source of alloying metal ions, wherein the metal of the alloying metal ions is selected from cobalt, nickel and iron.   5. A composition according to any one of claims 1 to 4, further comprising a complexing agent for gold ions.   The composition according to any one of claims 1 to 5, further comprising at least one brightener selected from pyridine and quinoline compounds.   The composition according to any one of claims 1 to 6, having a pH value of 1 to 6. (I) preparing the electroplating composition according to any one of claims 1 to 7;
(Ii) contacting the substrate with the composition; and (iii) applying a current between the substrate and at least one anode, thereby depositing gold or a gold alloy on the substrate. .   The method of claim 8, wherein the substrate is iron, nickel, copper, or an alloy thereof.   The method according to claim 8 or 9, wherein the substrate is an electrical connector. (I) providing a used gold or gold alloy electroplating composition;
(Ii) adding a mercaptotriazole as defined in claim 1 or 2 to said spent gold or gold alloy electroplating composition; and (iii) contacting a substrate with said composition; and (iv) said Applying a current between the substrate and at least one anode, thereby depositing gold or a gold alloy on the substrate.   Use of a mercaptotriazole as defined in claim 1 or 2 as an immersion inhibitor in an electrodeposition bath.

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