TW201615628A - Composition and method for electrodepositing gold containing layers - Google Patents

Abstract

The present invention relates to a composition and method for electrodepositing gold containing layers using the composition and the use of mercapto-triazole com-pounds as anti-immersion additives. The composition contains a mercapto-triazole compound which acts as an anti-immersion additive. The composition and method are suited for depositing functional or hard gold or gold alloys that can be applied in the industry as contact material of electrical connectors for high reliability applications.

Description

Composition and method for electrodepositing gold-containing layers

This invention relates to a composition and a method of using the composition of the invention for electrodepositing a gold-containing layer. The composition of the invention contains a mercaptotriazole compound that acts as an anti-dip coating additive. The compositions and methods are suitable for depositing functional or hard gold or gold alloys that can be used in the industry as contact materials for electrical connectors for high reliability applications.

Hard gold or gold alloys of cobalt and nickel have been widely used as contact materials for electrical connectors for high reliability applications. The connector with the hard gold end layer is thus plated on a conductive metal layer, such as a nickel substrate, such as nickel plated on copper. Typically, the connector is part of a larger electronic device or wire. A selective plating technique is used to deposit only a gold or gold alloy layer on the contact area of the connector without plating the remainder of the circuit. These selective plating techniques significantly reduce the material cost of the connector by limiting the plating area of gold and other precious metals such as palladium and palladium nickel alloys.

The problem of gold replacement occurs when gold is a precious metal to be plated on a connector that is typically made of a less expensive metal. Gold replacement is the deposition of gold by an exchange reaction. If the surface of the gold to be plated is, for example, a nickel surface, the salt displacement reaction occurs as follows: 2 Au ⁺ + Ni ⁰ → 2 Au ⁰ + Ni ²⁺

Among them, precious gold metal replaces the less expensive nickel. Metal deposition by the exchange reaction or displacement reaction is also referred to as immersion plating or immersion plating.

On the one hand, this problem occurs on the surface of the portion or region of the substrate that is not plated and therefore not electrically connected, while the functional surface (i.e., the connector) of the electronic portion is electroplated. In addition, the immersion plating reaction may occur when plating is stopped, for example, during idle time. Next, the connector surface is held in the gold deposition bath for a period of time without electrical connection.

In both cases, the gold layer is deposited on the non-attached surface by a dip plating reaction. Therefore, the gold layer is deposited in the unnecessary substrate region by the immersion plating reaction. This immersion gold plating is not forgotten because it consumes more gold than is required to coat the connectors and other electronic parts and thus results in additional consumption of gold that results in higher manufacturing costs.

A gold layer deposited on portions of printed circuit lines, connectors, or other electronic devices that are not intended to be plated can also cause defects in the substrate, resulting in defective end products. Therefore, the gold layer must then be removed, which is laborious, time consuming and costly.

In addition, the gold layer formed by the immersion plating has a low adhesion to its underlying surface. The portion of the immersion gold layer is detached from the underlying surface, with the risk of shorting when accidentally connecting individual circuit lines or other contact metals.

In addition, the problem of gold immersion plating increases with the age of gold electrolyte.

Gold immersion plating can be reduced by improving the design of the plating equipment. However, this requires expensive expense to redesign and then manufacture new equipment components.

The European patent EP 2 309 036 B1 discloses a hard gold plating bath which reduces the gold displacement reaction. The effect is attributed to the mercaptotetrazole compound contained in the plating bath. However, the reduction in the gold displacement reaction is still insufficient. In addition, EP 2 309 036 B1 does not describe that the gold substitution increases with the length of the gold deposition bath.

Therefore, for the functional pure gold layer and the gold alloy layer, it is still necessary to suppress the gold immersion plating reaction in the electrodeposition bath.

[Object of the present invention]

Accordingly, it is an object of the present invention to provide compositions and methods for electrodepositing gold-containing layers with further reduced gold immersion plating reactions.

Another object of the present invention is to provide a method for reducing the increased gold immersion plating reaction during the life of a composition for gold electroplating.

These objectives are achieved by the following compositions and methods.

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

Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are as defined below.

When the gold-containing layer is electrodeposited, the mercaptotriazole or its salt according to (ii) significantly reduces or almost inhibits the gold immersion plating reaction.

A method comprising the steps of: (i) providing an electroplating composition as defined above; (ii) contacting a substrate with a composition; and (iii) applying a current between the substrate and the at least one anode and thereby gold Or a gold alloy is deposited on the substrate.

The method is suitable for electrodepositing a gold-containing layer onto a substrate. This method significantly reduces or almost inhibits the gold immersion plating reaction.

A method comprising: (i) providing a gold or gold alloy plating composition for use; (ii) adding a mercaptotriazole as defined above to the gold or gold alloy plating composition used, and (iii) contacting the substrate with the composition; and (iv) applying between the substrate and the at least one anode Current and thereby deposit gold or gold alloy on the substrate.

The method is suitable for regenerating a gold or gold alloy plating composition that is used, wherein the gold immersion plating reaction achieves an extent that prevents proper operation of the appropriate gold or gold alloy layer and deposition. This method significantly reduces or almost inhibits the gold immersion plating reaction.

Figure 1 shows the thickness of a gold alloy layer deposited from a plating bath containing different hydrazol compounds by a immersion plating reaction.

Figure 2 shows the thickness of a gold alloy layer deposited from a plating bath containing different mercaptotriazole compounds by a immersion plating reaction.

The present invention relates to an electroplating composition comprising (i) at least one source of gold ions, and (ii) at least one mercaptotriazole or a salt thereof, wherein at least one mercaptotriazole has the following formula (I) or formula ( II):

Wherein R ¹ and R ⁴ are, independently of each other, hydrogen, straight or branched chain, saturated or unsaturated (C ₁ -C ₂₀ ) hydrocarbon chain, (C ₈ -C ₂₀ ) aralkyl; substituted or unsubstituted Phenyl, naphthyl or carboxy; and R ² , R ³ , R ⁵ , R ⁶ are each independently -SX, hydrogen, straight or branched, saturated or unsaturated (C ₁ -C ₂₀ ) hydrocarbon chain, ( C ₈ -C ₂₀ )Aralkyl; substituted or unsubstituted phenyl, naphthyl or carboxyl; and X is hydrogen, (C ₁ -C ₄ )alkyl or selected from alkali metal ions, calcium ions, ammonium a counter ion of an ion and a quaternary amine, and at least one of R ² and R ³ is -SX, and at least one of R ⁵ and R ⁶ is -SX.

The electroplating composition is suitable for electrodepositing a gold-containing layer onto 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. The functional or hard gold layer has a high mechanical stability and is therefore particularly resistant to mechanical wear. Gold layers and especially gold alloy layers are therefore suitable for use in electrical connectors.

When the gold-containing layer is electrodeposited, the mercaptotriazole or its salt according to (ii) significantly reduces or almost inhibits the gold immersion plating reaction.

In one embodiment, X is preferably a counterion selected from the group consisting of alkali metal ions selected from the group consisting of sodium ions, potassium ions, and lithium ions.

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

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

Formula (I) thus contains two tautomeric forms. The tautomeric form is especially relevant when R ¹ is a H atom.

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

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

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

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

In an even more preferred embodiment, the at least one mercaptotriazole is selected from the group consisting of: 5-mercapto-1,2,3-triazole; 4,5-dimercapto-1,2,3-tri Azole; 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-1,2,4-triazole-3-thiol and salts thereof.

In an even more preferred embodiment, the at least one mercaptotriazole is selected from the group consisting of: 5-mercapto-1,2,3-triazole; 4,5-dimercapto-1,2,3-tri Azole; 5-mercapto-1,2,4-triazole; 3-mercapto-1,2,4-triazole; 3,5-dimercapto-1,2,4-triazole and its salts.

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

In an even more preferred embodiment, the at least one mercaptotriazole is selected from the group consisting of 5-mercapto-1,2,3- Triazole and its salts. The mercaptotriazole compounds are either commercially available or can be prepared by methods well known in the art.

In one embodiment, at least one mercaptotriazole has a concentration in the electroplating composition ranging from 1 mg/l to 1 g/l. Preferably, the concentration is less than 1 g/l. More preferably, the concentration is in the range of from 1 mg/l to 900 mg/l, even more preferably from 1 mg/l to 500 mg/l, even more preferably from 5 mg/l to 100 mg/l, even more preferably from 20 mg/l to 100 mg/l. 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 is not sufficiently adhered to the surface of the substrate.

The addition of one or more mercaptotriazoles to the gold or gold alloy plating composition inhibits the gold immersion plating reaction without impairing the appearance of the gold alloy. In addition, the functional properties of the gold or hard gold layer, such as contact resistance and hardness, are not impaired. The contact resistance is maintained at the desired low level and the gold layer is sufficiently hard for commercial electrical contacts for electronic devices. In addition, by adding one or more mercaptotriazoles according to the invention to a gold or gold alloy electroplating composition, the advantageous functional properties of the high wear resistance of the gold or hard gold layer, especially the hard gold layer, are not impaired. .

The electroplating composition further comprises (i) at least one source of gold ions. The gold ion source can be selected from the group consisting of a gold (I) ion source and a gold (III) ion source. The gold (I) ion source may be selected from the group consisting of gold cyanide compounds, gold thiosulfate compounds, gold sulfite compounds, and gold (I) salts of gold (I) halides. The gold cyanide compound may be selected from alkali metal gold cyanide such as gold potassium cyanide or gold sodium cyanide; and gold ammonium cyanide. The gold thiosulfate compound may be selected from a thiosulfate gold alkali metal such as trisodium gold thiosulfate or tripotassium gold thiosulfate. The gold sulfite compound may be selected from gold alkali metal sulfites such as gold sodium sulfite or gold potassium sulfite; and gold ammonium sulfite. The gold (I) halide may be gold (I) chloride. The gold (III) ion source can be a gold (III) halide such as gold (III) trichloride. Preferably, the source of gold ions is an alkali metal gold cyanide compound such as gold potassium cyanide or gold sodium cyanide. More preferably, the gold ion source is potassium gold cyanide, such as potassium diiodide (I) or potassium tetracyanate (III); or sodium gold cyanide, such as sodium dicyanohydride (I) or tetracyanate Fund (III) sodium. Even better, the gold ion source is dicyanoic acid (I) potassium or tetracyano fund (III) Potassium acid. Gold potassium cyanide has better solubility than other gold compounds.

In one embodiment, wherein 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 a base such as gold potassium cyanide or gold sodium cyanide. Metal gold cyanide; or gold ammonium cyanide. If the gold ion source is a gold cyanide compound, electrodeposition with a high gold content or hard gold alloy layer is most likely. In this case, the gold ion is contained in the electroplating composition in the form of a gold cyanide complex, preferably as a complex of a gold cyanide alkali metal ion, and more preferably as a complex of gold potassium cyanide. It is especially suitable for electrodepositing hard gold alloy layers with a high gold content. The same applies to electrolyte-deposited gold-containing layers used with high current densities because of gold compounds other than gold cyanide complexes, alkali metal gold cyanide ion complexes or gold cyanide ion complexes. It is less stable at high current densities.

In one embodiment, the at least one source of gold ions has a range of from 1 g/l to 50 g/l, preferably from 5 g/l to 50 g/l, more preferably from 10 g/l to 50 g/in the electroplating composition. A concentration 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, even more preferably in the range of 10 g/l to 20 g/l. The tendency of the electroplating composition to deposit gold by the immersion plating reaction increases as the concentration of gold contained in the composition increases.

In one embodiment, the electroplating composition may further comprise a binder for gold ions. The complexing agent for gold ions is selected from the group consisting of alkali metal cyanides such as potassium cyanide, sodium cyanide and ammonium cyanide; thiosulfuric acid and salts thereof, such as sodium thiosulfate, potassium thiosulfate and ammonium thiosulfate Sulfuric 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, imine Acetic acid, nitrogen triacetic acid, 1,2-diaminocyclohexanetetraacetic acid, bis-2-aminoethyl ether tetraacetic acid, diethylenetriamine pentaacetic acid; inorganic acids such as phosphoric acid, sulfuric acid, boric acid; , such as 1-hydroxyethane-1,1-diphosphonic acid, 1-hydroxyethane-1,2-diphosphonic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylphosphonic acid, hexamethylene a diaminotetramethylphosphonic acid; and a salt of the foregoing, such as an alkali metal salt and an alkaline earth metal salt; preferably a sodium salt and a potassium salt; an amine such as Tetraethylamine, tri-ethyltetramine, triethylamine, diethyltriamine and ethylenediamine. The wrong agent can also act as a conductive salt.

In one embodiment where the gold ion source is an alkali metal gold cyanide compound, the complexing agent is preferably a cyanide-free compound, more preferably an alkali metal-free cyanide.

In one embodiment, the binder is present in the electroplating composition in the range of from 1 g/l to 200 g/l, preferably in the range of from 1 g/l to 100 g/l, more preferably in the range of from 10 g/l to 50 g/l. Concentration.

In one embodiment, the electroplating composition can further comprise at least one source of alloyed metal ions. The metal of the alloyed metal ion is selected from the group consisting of cobalt, nickel and iron. Gold-cobalt, gold-nickel and gold-iron alloys are hard gold alloys.

The hard gold alloy deposit has a gold content ranging from 99.00% by mass to less than 99.90% by mass. For hard gold alloys, the alloy metal cobalt, nickel and/or iron may be present in an amount ranging from less than 0.03 mass% to more than 0.3 mass% (ASTM B488-11, part 7). Alloy metal imparts 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 otherwise important for their use in electrical connectors. In contrast, gold deposits having a gold content of equal to or greater than 99.90 mass% have lower hardness (ASTM B488-11, parts 4 and 7), lower wear resistance and are therefore unsuitable for use in electrical connectors.

The alloying metal ions are selected from the group consisting of cobalt (II) ions, nickel (II) ions, iron (II) ions, and iron (III) ions. The alloying metal ion source is selected from the group consisting of cobalt carbonate, cobalt sulfate, cobalt gluconate, potassium cobalt cyanide, cobalt bromide, cobalt chloride, nickel chloride, nickel bromide, nickel sulfate, nickel tartrate, nickel phosphate, nitric acid. Nickel, nickel sulfonate, 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 has a range of from 0.001 g/l to 5 g/l, preferably from 0.05 g/l to 2 g/l, more preferably in the electroplating composition. Concentrations ranging from 0.05 g/l to 1 g/l.

In one embodiment, the electroplating composition may further comprise a binder for alloying metal ions. The complexing agent for alloying metal ions may be selected from the group consisting of sulfurous acid and salts thereof, such as potassium sulfite, ammonium sulfite; carboxylic acids such as sorbic acid; hydroxycarboxylic acids such as citric acid and malonic acid; , such as ethylenediaminetetraacetic acid, imine diacetic acid, nitrogen triacetic acid, 1,2-diaminocyclohexanetetraacetic acid, bis-2-aminoethyl ether tetraacetic acid, diethylenetriamine pentaacetic acid; inorganic Acids such as phosphoric acid, sulfuric acid, boric acid, thiosulfuric acid; phosphonic acids such as 1-hydroxyethane-1,1-diphosphonic acid, 1-hydroxyethane-1,2-diphosphonic acid, aminotrimethylene a phosphonic acid, ethylenediaminetetramethylphosphonic acid, hexamethylenediaminetetramethylphosphonic acid; and a salt of the foregoing, such as an alkali metal salt and an alkaline earth metal salt; preferably a sodium salt and a potassium salt; an amine, Such as tetraethylamine, triethylamine, triethylamine, diethylamine and ethylenediamine. The wrong agent can also act as a conductive salt.

The binder for alloying metal ions may have a concentration in the electroplating composition in the range of from 1 g/l to 200 g/l, preferably from 20 g/l to 150 g/l. If the above-mentioned binder is used for gold ions and alloying metal ions, the concentration of the binder is the sum of the concentrations required for the gold ions and the alloyed metal ions.

In one embodiment, the electroplating composition can further comprise at least one whitening agent. The at least one whitening agent is selected from the group consisting of pyridine and quinoline compounds. The pyridine and quinoline compounds are selected from the group consisting of substituted pyridines and substituted quinoline compounds. Preferably, the substituted pyridine and the substituted quinoline compound are selected from the group consisting of a monocarboxylic acid or a dicarboxylic acid, a monosulfonic acid or a disulfonic acid, a monothiol or a dithiol substituted pyridine, a quinoline, a pyridine derivative or Quinoline derivative. The pyridine derivative or quinoline derivative may be substituted at one or more positions by the same or different substituents. More preferably, the pyridine derivative or the quinoline derivative is selected from the group consisting of a derivative substituted at the 3-position of the pyridine ring. Even more preferably, the pyridine derivative or the quinoline derivative is selected from the group consisting of pyridine carboxylic acid or quinoline carboxylic acid, pyridine sulfonic acid or quinoline sulfonic acid, and pyridine thiol or quinoline thiol. Even more preferably, the pyridine carboxylic acid or the quinoline carboxylic acid is selected from the group consisting of its respective esters and guanamines. Even more preferably, pyridine carboxylic acid or quinoline carboxylic acid Is selected from the group consisting of pyridine-3-carboxylic acid (nicotinic acid), quinoline-3-carboxylic acid, 4-picolinic acid, methyl nicotinic acid, nicotinamide, nicotinic acid diethylguanamine, pyridine-2, 3-dicarboxylic acid, pyridine-3,4-dicarboxylic acid and pyridine-4-thioacetic acid. Even more preferably, the pyridinesulfonic acid or quinoline sulfonic acid is selected from the group consisting of 3-pyridinesulfonic acid, 4-pyridinesulfonic acid and 2-pyridinesulfonic acid. Most preferably, the at least one whitening agent is selected from the group consisting of pyridine-3-carboxylic acid (nicotinic acid), nicotinamide, and 3-pyridine sulfonic acid.

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

The brightener advantageously causes deposition of a bright gold layer over a wide current density range between ² A/dm ² and 100 A/dm ² .

In one embodiment, the electroplating composition can further comprise at least one acid. Preferably, the at least one acid is an organic or inorganic acid. More preferably, the at least one acid is selected from the group consisting of phosphoric acid, citric acid, malic acid, oxalic acid, formic acid, and polyvinylaminoacetic acid. At least one acid is used to adjust the pH of the plating composition. The at least one acid can also act as a blocking agent and/or act 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 basic compound. At least one basic compound is used to adjust the pH of the plating composition. The at least one basic compound is selected from the group consisting of hydroxides, sulfates, carbonates, phosphates, hydrogen phosphates, and other salts of sodium, potassium, and magnesium. Preferably, the at least one basic compound is selected from the group consisting of 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 may have a ratio of less than 7, more preferably less than 5, even more preferably between 1 and 6, even more preferably between 3 and 6, even more preferably between 3.5 and 5.5, and even more Good pH between 3.5 and 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. If the electrodeposition composition is acidic, it is most likely to electrodeposit a functional or hard gold alloy layer having a high gold content.

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

The invention further relates to a method comprising the steps of: (i) providing an electroplating composition as defined above; (ii) contacting the substrate with the composition; and (iii) applying a current between the substrate and the at least one anode and Thereby, a gold-containing layer is deposited on the substrate.

The method is suitable for electrodepositing a gold-containing layer onto a substrate. The method utilizes an electroplating composition of the present invention containing at least one mercaptotriazole or a salt thereof as an anti-dip coating additive. This method significantly reduces or almost inhibits the gold immersion plating reaction. The process of the invention therefore significantly reduces gold consumption and increases the lifetime of the gold or gold alloy electroplating composition. The gold-containing layer may 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 a portion of the surface of the substrate is also referred to as selectively depositing or plating a metal layer. Therefore, the gold-containing layer can be selectively plated on the substrate.

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 covering portions of the surface of the substrate that are not to be plated. In the spot plating method, only a portion of the substrate to be metallized is electrically connected and thus plated. The brush plating method locally applies the anode covered by the brush to the substrate area of the brush to be plated with the metal plating solution.

In the case where the metal is deposited on the entire surface of the substrate or in selective metal deposition, the surface of the conductive substrate or a portion of the surface of the substrate is in contact with the electroplating composition of the present invention. A portion of the substrate surface or the surface of the substrate is electrically connected as a cathode. In this cathode with at least one A voltage is applied between the anodes such that current is supplied to the surface of the substrate or a portion of the surface of the substrate.

The current density of the current may be from 0.05 A/dm ² to 100 A/dm ² , preferably from 1 A/dm ² to 50 A/dm ² , more preferably from 1 A/dm ² to 40 A/dm ² , even more preferably from 5 A/dm ² to 40 A. /dm ² , and even better 5A/dm ² to 20A/dm ² . Applying a higher current density during electrodeposition of the gold-containing layer advantageously increases the deposition rate and thus the productivity of the electrodeposition process.

The plating time can be changed. The amount of 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.

The electroplating composition of the present invention can be maintained at a temperature ranging from 40 ° C to 70 ° C during plating.

The electroplating composition of the present invention may not be moved during plating or the electroplating composition of the present invention may be agitated. For example, by mechanical movement of the water bath (such as vibration, stirring of liquid or continuous pumping) or inherently by ultrasonic treatment or by high temperature or by gas feeding (such as with inert gas or simply Air purifying water plating tank) to perform agitation.

The method for electrodepositing a gold-containing layer on a substrate may further comprise a pre-treatment step prior to contacting the substrate with the electroplating composition of the present invention. The pretreatment step is to activate the surface of the substrate, typically with an acid or a fluorine-containing acid.

The method for electrodepositing a gold-containing layer onto a substrate can include other plating steps prior to contacting the substrate with the electroplating composition of the present invention. Other plating steps deposit other metal layers on the substrate prior to electrodepositing the gold or gold alloy layer onto the substrate. The metal of the other metal layer may be selected from the group consisting of iron, nickel, nickel-phosphorus alloy, copper, palladium, silver, cobalt, and alloys thereof, preferably nickel, nickel-phosphorus alloy, and copper. Plating methods for the metals mentioned above are known in the art.

In one embodiment, the substrate to be plated with a gold-containing layer (ie, a gold layer or a gold alloy layer) is a conductive material. The electrically conductive material can be a metal. The metal can be any metal that can undergo a gold immersion plating reaction. The metal may be selected from the group consisting of iron, nickel, nickel-phosphorus alloys, copper, palladium, silver, cobalt, and combinations thereof. gold. Preferably, the substrate is made of iron or copper and covered with a layer of nickel.

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

The invention further relates to a method comprising the steps of: (i) providing a gold or gold alloy plating composition for use; (ii) adding a mercaptotriazole as defined above to a gold or gold alloy plating combination used And (iii) contacting the substrate with the composition; and (iv) applying a current between the substrate and the at least one anode and thereby depositing gold or a gold alloy on the substrate.

The method is suitable for regenerating gold or gold alloy plating compositions that have been used. In one aspect, the electroplating composition used can be an aged gold or gold alloy electroplating composition. An aged electroplating composition is herein meant to be a composition that has been used in electroplating where the gold immersion plating reaction has achieved an extent to prevent efficient operation and deposition of a suitable gold or gold alloy layer. The criterion used to evaluate the degree of aging is the deposition rate by the immersion plating reaction. In a newly fabricated gold or gold alloy plating bath, the deposition rate is about 5 nm/5 min metal at 60 °C. The deposition rate increases as the life of the plating bath increases. When the deposition rate reaches 80 to 100 nm/5 min metal at 60 ° C, it is usually necessary to replace the gold or gold alloy plating bath. Even when the deposition rate reaches 20 to 40 nm/5 min of metal at 60 ° C, the gold or gold alloy plating bath may no longer be suitable for industrial plating applications because the immersion plating reaction at the time has caused a high loss of gold. In contrast, the process of the present invention significantly reduces or nearly inhibits the gold immersion plating reaction of aged gold or gold alloy plating compositions. Thus, the process of the invention regenerates aged gold or gold alloy plating compositions and significantly increases the life of the gold or gold alloy plating composition.

The invention further relates to a method comprising the steps of: (i) providing an aged 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) applying a current between the substrate and the at least one anode Thereby, gold or a gold alloy is deposited on the substrate.

The thickness of the gold layer can be measured by x-ray fluorescence (XRF) as known in the art. XRF thickness measurements utilize characteristic fluorescent radiation emitted from x-ray excited samples (substrates, deposits). The layer thickness can be calculated by evaluating the intensity and assuming a layered structure of the sample.

Alternatively, the electroplating composition used may be a gold or gold alloy electroplating composition that has not been used for a period of time in the electroplating process. Unused means that the gold or gold alloy plating composition is not electrically connected and no gold or gold alloy is electrodeposited from the composition. It has been observed that although gold or gold alloy electrodeposition compositions are not used in the electroplating process, the problem of gold immersion plating is also increased. The addition of the mercaptotriazole of the present invention to the gold or gold alloy electrodeposition composition temporarily removed from operation also significantly reduces or nearly inhibits the gold immersion plating reaction when the composition is operated again.

The invention further relates to a method comprising the steps of: (i) providing a gold or gold alloy plating composition for temporary leaving operation; (ii) adding a mercaptotriazole as defined above to a gold or gold alloy temporarily leaving operation An electroplating composition, and (iii) contacting the substrate with the composition; and (iv) applying a current between the substrate and the at least one anode and thereby depositing gold or a gold alloy on the substrate. The invention further relates to a substrate electroplated with a gold-containing layer obtainable by a method of the invention.

The invention further relates to the use of the mercaptotriazole of the invention as an anti-dip coating additive in an electrodeposition composition, preferably in an electrodeposition composition of a gold-containing layer.

The electroplating compositions and methods of the present invention significantly reduce or nearly inhibit the gold immersion plating reaction. Therefore, gold is not deposited on the undesired areas of the substrate surface. This saves money because of the gold The loss and defective end product preparation is minimized. In addition, the life of gold or gold alloy plating compositions is significantly improved.

The tetrazole compound is less effective in reducing the gold immersion plating reaction than the triazole compound of the present invention. In addition, the tetrazole compound exhibits less stability in the gold or gold alloy electroplating composition, resulting in higher consumption of the tetrazole compound, due to the increased concentration of decomposition products during processing, and thus the reduced life of the gold electrolyte. normal work.

Instance Example 1

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

A gold-cobalt alloy plating bath (Aurocor HSC, 15 g/l gold, pH 4.5, additionally prepared with a sodium salt of 500 mg/l 5-mercapto-1,2,3-triazole as an anti-dip coating additive) Copper plate A is electroplated by Atotech Deutschland GmbH. Electroplating was carried out under stirring at a current density of 10 A/dm ² at a temperature of 60 ° C for a period of 150 seconds.

After plating, the substrate was completely covered with a bright, uniform, good adhesion gold-cobalt alloy layer having a high hardness of 5 μm.

Example 2

A nickel plated with nickel and a pretreated copper plate as described in Example 1 was used as the substrate. One half of the substrate is covered with tesa tapes to shield areas that are not to be plated.

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

Copper plate C to copper plate F with a newly prepared gold-cobalt alloy plating bath containing 500 mg/l of each mercaptotriazole compound or mercaptotetrazole compound as outlined in Table 1 (Aurocor HSC, 15 g/l gold, pH 4.5, contact with individual parts of the product of Atotech Deutschland GmbH).

The copper plate B is not electrically connected to the copper plate F while being in contact with the gold-cobalt alloy plating bath. Therefore, it is possible to perform metal-free deposition by electroplating. 50 ml of a gold-cobalt alloy plating bath containing each hydrazolazole compound was used for each panel. The gold-cobalt alloy plating bath was maintained at a temperature of 60 ° C and continuously agitated at 400 rpm (revolutions per minute). Touch each panel for 5 minutes.

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

In general, a gold alloy layer is deposited on portions of the substrate panel that are not covered by the tape, and no gold alloy is deposited onto portions of the substrate panel covered with tape. From the gold alloy bath containing the mercaptotriazole according to the present invention, the gold alloy layer having the smallest thickness is deposited only by the immersion plating reaction. In contrast, a gold alloy layer having a significantly higher layer thickness was deposited by a immersion plating reaction from a gold alloy bath containing no hydrazol compound or a decyltetrazole compound. In addition, Comparative Compound D caused unwanted deposits in the gold alloy bath. The tetrazole compound exhibits less instability in the gold alloy electrolyte than the triazole compound of the present invention, resulting in higher consumption of the tetrazole compound, due to increased concentration of decomposition products during processing, and thus gold electrolyte Not working properly to reduce life. Therefore, the mercaptotriazole compound of the present invention significantly reduces or almost inhibits the gold immersion plating reaction.

Example 3

A nickel plated with nickel and a pretreated copper plate as described in Example 1 was used as the substrate.

First aging gold-cobalt alloy plating bath at 60 ° C (Aurocor HSC, Atotech Deutschland GmbH product) treated with activated carbon for 30 min.

In step 1, the gold plating bath is maintained at 60 ° C, and the substrate is immersed in the gold plating bath without electrical connection for different periods of time. After 30 seconds in the bath, no gold was deposited on the substrate. However, after 2 minutes and 3 minutes later, the gold layer was deposited on the substrate by a dip plating reaction.

In the subsequent step 2, 25 mg/l sodium salt of 5-mercapto-1,2,3-triazole was added to the gold plating bath, and the substrate was again immersed in gold without electrical connection. The plating bath continues for different time periods. After no contact with the gold plating bath for 30 seconds, 2 minutes, 3 minutes, and even 5 minutes, no gold was deposited on the substrate by the immersion plating reaction.

Thus, the mercaptotriazole compounds of the present invention significantly reduce or nearly inhibit the gold immersion plating reaction of aged gold or gold alloy electroplating compositions. Thus, the mercaptotriazole compounds of the present invention regenerate aged gold or gold alloy electroplating compositions and significantly increase the lifetime of gold or gold alloy electroplating compositions.

Example 4

On day 1, Example 3 was repeated and the same results were obtained. After step 2, let the tank stand for one day without being used for 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, the gold layer was deposited on the substrate by a dip plating reaction.

Then perform step 2 of example 3. Even after 5 minutes of contact with the gold plating bath, no gold was deposited on the substrate by the immersion plating reaction.

Thus, the addition of the mercaptotriazole compound of the present invention to a gold or gold alloy electrodeposition composition that is temporarily removed from operation also significantly reduces or nearly inhibits the gold immersion plating reaction when the composition is operated again.

Example 5

A copper plate plated with nickel was used as the substrate. As summarized in Table 2 below, copper plates are made of nickel. Plated and pretreated. After each of the process steps listed in Table 2, the copper plate was rinsed with water. Cover one half of the substrate with Tessa tape to shield the areas that are not to be plated.

The copper plate G was brought into contact with an aged gold-cobalt alloy plating tank (Aurocor SC, 4 g/l gold, pH 4.5, product of Atotech Deutschland GmbH) containing no mercaptotriazole compound.

Copper plate H to copper plate M and aged gold-cobalt alloy plating bath containing 50 mg/l of each mercaptotriazole compound as outlined in Table 3 (Aurocor SC, 4 g/l gold, pH 4.5, product of Atotech Deutschland GmbH) ) Contact with individual parts.

While being in contact with the gold-cobalt alloy plating bath, the nickel-coated and pretreated copper plate G to the copper plate M are not electrically connected. Therefore, it is possible to perform metal-free deposition by electroplating. 50 ml of a gold-cobalt alloy plating bath containing the respective mercaptotriazole compounds was used for each panel. The gold-cobalt alloy plating bath was maintained at a temperature of 60 ° C and continuously agitated at 400 rpm (revolutions per minute). Touch each panel for 5 minutes.

After the panel was brought into contact with the respective gold-cobalt alloy plating baths, the thickness of the gold alloy layer deposited by the immersion plating reaction was measured by XRF. The results are summarized in Table 3 and shown in Figure 2.

^* Product of Atotech Deutschland GmbH; RT = room temperature (about 20 ° C); MA = mechanical agitation; "---" = no application conditions

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

In general, a gold alloy layer is deposited on portions of the substrate panel that are not covered by the tape, and no gold alloy is deposited onto portions of the substrate panel covered with tape. From the gold alloy bath containing the mercaptotriazole according to the present invention, the gold alloy layer having a small thickness is deposited by the immersion plating reaction. In contrast, a gold alloy layer having a significantly higher layer thickness was deposited by a immersion plating reaction from a gold alloy bath containing no mercaptotriazole compound or a comparative amine-modified mercaptotriazole compound. Therefore, the mercaptotriazole compound of the present invention significantly reduces the gold immersion plating reaction.

Example 6

Effect of Mercaptotriazole Compounds on Deposition Rate, Hardness and Adhesion of Deposited Gold Layer

A nickel plated with nickel and a pretreated copper plate as described in Example 1 was used as the substrate.

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

The copper plate N is partially plated from one of the plating tanks containing no mercaptotriazole compound by a dip plating reaction. The copper plate P was partially plated by a immersion plating reaction from one of the plating tanks containing the sodium salt of 25 mg/l of 5-mercapto-1,2,3-triazole. The gold-cobalt alloy layer deposited on the face plate N by the immersion plating reaction has a thickness of 82 ± 6 nm, and the gold-cobalt alloy layer deposited on the face plate P has a thickness of 10 ± 4 nm.

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

Deposition rate:

The copper plate Q1 to the copper plate Q4 are plated from individual portions of the aged plating bath containing no mercaptotriazole compound. The copper plate R1 to the copper plate R4 were plated from individual portions of the aged plating bath containing the sodium salt of 25 mg/l 5-mercapto-1,2,3-triazole. As outlined in Table 4, the current density varied from 5 A/dm ² to 20 A/dm ² . The thickness of the electrodeposited gold-cobalt alloy layer was measured by XRF. The results are summarized in Table 4.

In the absence or presence of mercaptotriazole, the deposition rate of the gold-cobalt alloy from the aged plating bath is almost the same. Therefore, the mercaptotriazole according to the present invention does not affect the deposition rate in the gold electrodeposition tank.

hardness:

A copper plate S is partially plated from one of the aged plating tanks containing no mercaptotriazole compound. A copper plate T was partially plated from one of the aged plating baths containing sodium salt of 25 mg/l 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 determined by Vickers hardness test using an XRF-SDD (X-ray fluorescence-twist detector), Fischerscope X-RAY XDRL from Fischer Technology, Inc. . The gold-cobalt alloy layer electrodeposited on the face plate S has a hardness of 180 ± 10 HV 0.001, and the gold-cobalt alloy layer electrodeposited on the face plate T has a hardness of 178 ± 10 HV 0.001.

In the absence or presence of mercaptotriazole, the hardness of the gold-cobalt alloy layer deposited from the aged plating bath is almost the same. Therefore, there is a ruthenium base according to the present invention in the gold electrodeposition tank The triazole does not affect the hardness of the deposited gold-containing layer.

Adhesion:

A newly prepared gold-cobalt alloy plating tank (Aurocor HSC, 15 g/l gold, pH 4.5, product of Atotech Deutschland GmbH) was used to determine the adhesion. When depositing using a newly formed gold or gold alloy plating bath, the negative effect on the adhesion of the electrodeposited gold-containing layer is best detected because these plating baths only have a low immersion plating reaction. And the deposits usually have good adhesion.

The copper plate U1 to the copper plate U2 are plated from the individual portions of the newly formed plating tank containing no mercaptotriazole compound. The copper plate V1 to the copper plate V2 were plated from the individual portions of the newly formed plating bath containing the sodium salt of 50 mg/l 5-mercapto-1,2,3-triazole.

In the case of no electrical connection, the copper plate U1 and the copper plate V1 are first brought into contact with the respective plating grooves for 5 minutes. Thus, for panel V1, mercaptotriazole is allowed to adhere to the nickel surface of the panel. Then, the copper plate U1 and the copper plate V1 were plated from the respective plating tanks at 5 A/dm ² for 72 seconds, whereby the gold-cobalt alloy layer was electrodeposited on the panel. The adhesion of the gold-cobalt alloy layer to the panel surface was determined by a bend test and by a tape test. Perform the bending test as follows: bend the portion of the panel to be tested to a 90° angle once. When the bubbles are formed in the deposited gold layer or the undeposited gold layer is released from the curved region, the adhesion is considered to be good. For the tape test, a Tessa tape 4102 having an adhesion strength of about 6 N/cm was adhered to the gold-cobalt plated panel and then removed from the panel surface. If the tape does not remove part or all of the gold-cobalt layer, the adhesion is at least as good as 6 N/cm which is considered to be good adhesion. In contrast, if the tape removes a part or the whole of the gold-cobalt layer, the adhesion is insufficient.

The bending test and the tape test revealed that the adhesion of the gold-cobalt alloy layer to the nickel surface of the panel U1 and the panel V1 was almost the same and good.

First, the copper plate U2 and the copper plate V2 are brought into contact with the respective plating grooves and a thin gold-cobalt layer (first gold-cobalt layer) having a thickness of between 0.1 μm and 0.2 μm is electrodeposited. Then, the plated copper plate was brought into contact with the respective plating grooves for 10 seconds without being electrically connected. Thus, for panel V2, mercaptotriazole is allowed to adhere to the surface of the deposited gold-cobalt layer. Next, the copper plate U2 and the copper plate V2 were plated from the respective plating tanks at 5 A/dm ² for 72 seconds, whereby the second gold-cobalt alloy layer was electrodeposited on the panel. The adhesion of the second gold-cobalt alloy layer to the surface of the first gold cobalt layer was determined by a bending test and by a tape test as described above.

The bending test and the tape test revealed that the adhesion of the second gold-cobalt alloy layer to the surface of the first gold-cobalt layer of the panel U2 and the panel V2 was almost the same and good.

In the absence or presence of mercaptotriazole, the adhesion of the gold-cobalt alloy layer deposited from the newly formed plating bath is almost the same. Therefore, the presence of the mercaptotriazole according to the present invention in the gold electrodeposition tank does not affect the adhesion of the deposited gold-containing layer.

Claims (12)

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 has the following general formula (I) or formula (II): Wherein R ^1, R ⁴ independently of one another hydrogen, straight-chain or branched, saturated or unsaturated (C ₁ -C ₂₀₎ hydrocarbon chain, (C ₈ -C ₂₀₎ arylalkyl; substituted or non-substituted Phenyl, naphthyl or carboxy; and R ² , R ³ , R ⁵ , R ⁶ are, independently of each other, -SX, hydrogen, straight or branched, saturated or unsaturated (C ₁ -C ₂₀ ) hydrocarbon chain, ( C ₈ -C ₂₀ )Aralkyl; substituted or unsubstituted phenyl, naphthyl or carboxyl; and X is hydrogen, (C ₁ -C ₄ )alkyl or selected from alkali metal ions, calcium ions, ammonium a counter ion of an ion and a quaternary amine, and at least one of R ² and R ³ is -SX, and at least one of R ⁵ and R ⁶ is -SX. The composition of claim 1, wherein the at least one mercaptotriazole has the formula (I) or the formula (II), wherein R ¹ and R ⁴ are independently of each other hydrogen or a straight chain (C ₁ -C ₄ An alkyl group, and R ² , R ³ , R ⁵ , R ⁶ are each independently -SX, hydrogen or a linear (C ₁ -C ₄ ) alkyl group; and X is hydrogen, methyl, ethyl or selected from a counter ion of sodium ion and potassium ion; and at least one of R ² and R ³ is -SX, and at least one of R ⁵ and R ⁶ is -SX. The composition of claim 1 or 2, wherein the at least one mercaptotriazole has a concentration ranging from 1 mg/l to 1 g/l. The composition of claim 1 or 2, further comprising at least one source of alloying metal ions, wherein the metal of the alloying metal ions is selected from the group consisting of cobalt, nickel, and iron. The composition of claim 1 or 2, further comprising a complexing agent for gold ions. The composition of claim 1 or 2, further comprising at least one whitening agent selected from the group consisting of pyridine and quinoline compounds. A composition according to claim 1 or 2 which has a pH between 1 and 6. A method comprising: (i) providing an electroplating composition according to any one of claims 1 to 7; (ii) contacting a substrate with the composition; and (iii) applying between the substrate and the at least one anode Current and 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 of claim 8 or 9, wherein the substrate is an electrical connector. A method comprising: (i) providing a gold or gold alloy plating composition for use; (ii) adding mercaptotriazole to the used gold or gold alloy electroplating composition, wherein the mercaptotriazole is And (iii) contacting the substrate with the composition; and (iv) applying a current between the substrate and the at least one anode and thereby depositing gold or a gold alloy on the substrate. Use of a mercaptotriazole, as defined in claim 1 or 2, as an anti-dip coating additive in an electrodeposition bath.