Electrolysis gold plating solution and manufacturing method for electrolysis gold plating film

Abstract

To provide an electrolysis gold plating solution that can produce an electrolysis gold plating film with excellent mechanical, corrosion resistance, electrical, and other properties, and that maintains good gold selective deposition for a long time.SOLUTION: The above problems were solved by an electrolysis gold plating solution using gold cyanide salt as a gold source, which contains one or more quinone compounds selected from the group consisting of compounds having an anthraquinone skeleton and compounds having a naphthoquinone skeleton. Further, the above problems were solved by an electrolysis gold plating solution using gold cyanide salt as a gold source, characterized in that when the ultraviolet-visible absorption spectrum is measured at an optical path length of 1 cm, the absorbance at a wavelength of 258 nm is A1, and the absorbance at a wavelength of 327 nm is A2, A2 is 0.01 or greater and A1 / A2 is 6 or more and 12 or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrolytic gold plating solution, and more particularly to an electrolytic gold plating solution having excellent selective gold deposition properties. The present invention also relates to an agent for improving selective gold deposition for such an electrolytic gold plating solution, and a method for producing such an electrolytic gold plating solution. [Background technology]

[0002] Gold plating is widely used because of its excellent corrosion resistance, mechanical properties, electrical properties, etc. In particular, gold plating applied on nickel films is widely used in the field of electronic and electrical components, etc., because gold has excellent corrosion resistance, mechanical properties, electrical properties, etc., and nickel has excellent heat resistance as a base metal. Among them, gold plating films alloyed with metals such as cobalt, nickel, and iron are widely used as gold plating for contact junctions of plug-in members such as connectors, contact members such as switches, etc., taking advantage of their high hardness and excellent wear resistance. Plating using an electrolytic gold plating solution containing cobalt salts, nickel salts, iron salts, etc. is also called hard electrolytic gold plating.

[0003] In recent years, as electronic devices have become smaller, plug-in components such as connectors and contact components such as switches have also become smaller and more complex in shape, and the distance between the parts that need to be soldered and the parts that need to function as contacts has become significantly narrower, causing a problem of solder spreading to parts that do not need soldering. Therefore, we are trying to solve this problem by providing a non-gold-plated part between the contact part and the solder joint part, so that solder spreads only to the parts that need it.

[0004] This method is an electrolytic gold plating technology commonly known as nickel barrier plating, in which gold-plated and non-gold-plated areas are created within a single component by mechanically pressing down on the areas where gold plating is not required (nickel barrier areas) with a member such as silicone rubber to prevent contact between the gold plating solution and the component to be plated, thereby creating gold-plated and non-gold-plated areas (nickel barrier areas) within a single component.

[0005] However, because it is necessary to create areas within a single component that are gold plated and areas that are not, there is a problem in that it is extremely difficult from an equipment perspective to completely prevent the gold plating solution from leaking out of those areas, even if the areas that do not require gold plating are mechanically held down with a member such as silicone rubber.

[0006] Attempts have been made to solve this problem by adjusting the composition of the gold plating solution to a specific composition by adding additives, etc. In other words, various gold plating solutions have been proposed that have the property of depositing a large amount of gold on the parts of the surface of the object to be plated that require gold plating and reducing the amount of gold deposited on the parts that do not require gold plating (hereinafter, such a property may be referred to as "selective gold deposition").

[0007] Patent Document 1 discloses an acidic gold-cobalt alloy plating solution containing gold cyanide or a salt thereof, a soluble cobalt salt, an inorganic conductive salt component, a chelating agent, and hexamethylenetetramine.

[0008] Patent Document 2 discloses a hard gold plating solution for electrolytic plating, which contains specific amounts of a gold ion supply material, a conductive salt, a complexing agent, a metal salt containing an alloying element for gold, and a gold deposition inhibitor, and has a solution specific gravity and electrical conductivity.

[0009] Patent Document 3 discloses a substitution prevention agent for electrolytic hard gold plating solutions, which contains a gold salt, a soluble cobalt salt and / or a soluble nickel salt, an organic acid conductive salt, a chelating agent, and a compound having a mercapto group, and an electrolytic hard gold plating solution containing such a substitution prevention agent for electrolytic hard gold plating solutions.

[0010] Patent Document 4 discloses an electrolytic hard gold plating solution containing a gold cyanide salt, an organic acid conductive salt, a chelating agent, iron ions, and at least one of boric acid and a borate salt.

[0011] Patent Document 5 discloses an electrolytic gold plating solution containing a gold cyanide salt and a heterocyclic compound having one or more nitrogen atoms in a ring and in which one or more nitro groups are substituted on carbon atoms in the ring.

[0012] However, these known gold plating solutions sometimes have insufficient selective gold deposition properties, and sometimes fail to provide a good nickel barrier plating. Furthermore, in these known gold plating solutions, the additives in the gold plating solution are decomposed or consumed due to the effects of heating during plating operation, etc., so that the selective gold deposition is not sustained and it may become necessary to replenish the additives in order to maintain the selective gold deposition. This not only increases the material cost of the additives themselves, but also necessitates frequent analysis and replenishment of the additives in order to keep the additive concentration constant, which is uneconomical in terms of labor costs, etc.

[0013] In recent years, due to the miniaturization of electronic devices, it has become necessary to clearly distinguish between gold-plated and non-gold-plated parts, but this has not been achieved with conventional technology, and further improvements were necessary. In particular, from the viewpoint of cost, there is a strong demand for the development of a gold plating solution that can maintain selective gold deposition for a long period of time. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] JP 2008-045194 A [Patent Document 2] JP 2017-186627 A [Patent Document 3] International Publication No. 2016 / 208340 [Patent Document 4] JP 2013-177654 A [Patent Document 5] International Publication No. 2009 / 150915 Summary of the Invention [Problem to be solved by the invention]

[0015] The present invention has been made in view of the above-mentioned background art. An object of the present invention is to provide an electrolytic gold plating solution capable of producing an electrolytic gold plating film having excellent mechanical properties, corrosion resistance, electrical properties, etc., and capable of maintaining good selective gold deposition properties for a long period of time. [Means for solving the problem]

[0016] The present inventors have conducted extensive research to solve the above problems and have discovered the following facts, which have led to the completion of the present invention.

[0017] That is, an electrolytic gold plating film produced using an electrolytic gold plating solution containing an anthraquinone skeleton compound or a naphthoquinone skeleton compound has excellent mechanical properties, corrosion resistance, electrical properties, and the like. Moreover, such an electrolytic gold plating solution has good selective gold deposition properties. Furthermore, in such an electrolytic gold plating solution, the compounds having an anthraquinone skeleton and the compounds having a naphthoquinone skeleton, which are presumed to exert the selective gold deposition property, are not easily consumed during plating operations, and therefore, such an electrolytic gold plating solution maintains good selective gold deposition property for a long period of time without the addition (replenishment) of these compounds.

[0018] The present invention thus completed is as follows:

[0019] An electrolytic gold plating solution using a gold cyanide salt as a gold source, the electrolytic gold plating solution being characterized by containing one or more quinone compounds selected from the group consisting of compounds having an anthraquinone skeleton and compounds having a naphthoquinone skeleton.

[0020] The electrolytic gold plating solution uses gold cyanide salt as the gold source. The ultraviolet-visible absorption spectrum is measured with an optical path length of 1 cm, and the absorbance at a wavelength of 258 nm is A 1 , the absorbance at a wavelength of 327 nm is A 2 When this is done, A 2 is 0.01 or more, and A 1 / A 2 Electrolytic gold plating solution, characterized in that

[0021] A selective gold deposition improver for an electrolytic gold plating solution that uses a gold cyanide salt as a gold source, characterized in that the selective gold deposition improver contains, as its main component, one or more quinone compounds selected from the group consisting of compounds having an anthraquinone skeleton and compounds having a naphthoquinone skeleton.

[0022] A method for producing an electrolytic gold plating solution, comprising dissolving a gold cyanide salt and the above-mentioned gold selective deposition enhancer in water. Effect of the Invention

[0023] The electrolytic gold plating solution of the present invention exhibits good selective gold deposition properties, i.e., the electrolytic gold plating solution of the present invention can deposit a large amount of gold in areas that require gold plating and reduce the amount of gold deposited in areas that do not require gold plating.

[0024] The compound having an anthraquinone skeleton or a compound having a naphthoquinone skeleton, which is an additive (gold selective deposition improver) in the gold electrolytic plating solution of the present invention, is not easily consumed during plating operations. Therefore, in the production of an electrolytic gold plating film using the electrolytic gold plating solution of the present invention, good selective gold deposition properties are maintained for a long period of time without the need to replenish these additives. Therefore, according to the present invention, the material cost of the electrolytic gold plating solution can be reduced, and the labor required for analyzing the concentration of additives and replenishing additives can be saved, thereby reducing labor costs and the like.

[0025] The electrolytic gold plating film produced by the electrolytic gold plating of the present invention has excellent mechanical properties, corrosion resistance, electrical properties, etc. [Brief description of the drawings]

[0026] [Figure 1] 1 is an ultraviolet-visible absorption spectrum of the electrolytic gold plating solution of Example 1. [Diagram 2] 1 is an ultraviolet-visible absorption spectrum of the electrolytic gold plating solution of Example 2. [Diagram 3] 1 is an ultraviolet-visible absorption spectrum of the electrolytic gold plating solution of Example 3. [Figure 4] 1 is an ultraviolet-visible absorption spectrum of the electrolytic gold plating solution of Example 4. [Diagram 5] 1 is an ultraviolet-visible absorption spectrum of the electrolytic gold plating solution of Example 5. [Figure 6] 1 is an ultraviolet-visible absorption spectrum of the electrolytic gold plating solution of Example 6. [Figure 7] 1 is an ultraviolet-visible absorption spectrum of the electrolytic gold plating solution of Example 7. [Figure 8] 1 is an ultraviolet-visible absorption spectrum of the electrolytic gold plating solution of Comparative Example 1. [Figure 9] 1 is an ultraviolet-visible absorption spectrum of the electrolytic gold plating solution of Comparative Example 2. [Figure 10] 1 is an ultraviolet-visible absorption spectrum of the electrolytic gold plating solution of Comparative Example 3. [Figure 11] 1 is an ultraviolet-visible absorption spectrum of the electrolytic gold plating solution of Comparative Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The present invention will be described below, but the present invention is not limited to the following embodiments and can be practiced in any modified form.

[0028] In this specification, unless otherwise specified, "%" means "% by mass" and "ppm" means "ppm by mass".

[0029] [Electrolytic gold plating solution] The present invention relates to an electrolytic gold plating solution that uses a gold cyanide salt as a gold source, and that contains one or more quinone compounds selected from the group consisting of compounds having an anthraquinone skeleton and compounds having a naphthoquinone skeleton.

[0030] <Gold cyanide salt> The electrolytic gold plating solution of the present invention uses a gold cyanide salt as the gold source. That is, the gold cyanide salt in the electrolytic gold plating solution is reduced by a plating reaction and precipitates as gold on the object to be plated, thereby producing an electrolytic gold plating film.

[0031] The valence of gold in the gold cyanide salt may be 1 or 3. From the viewpoint of gold deposition efficiency, the valence is preferably 1.

[0032] The gold cyanide salt is preferably an alkali metal gold cyanide or ammonium gold cyanide.

[0033] More specifically, examples of gold cyanide salts include sodium gold cyanide(I), potassium gold cyanide(I), ammonium gold cyanide(I), sodium gold cyanide(III), potassium gold cyanide(III), and ammonium gold cyanide(III). Among these, for example, from the viewpoints of plating performance such as gold deposition efficiency, cost, and ease of availability, sodium gold cyanide(I), potassium gold cyanide(I), and ammonium gold cyanide(I) are preferable. Furthermore, from the same viewpoints, potassium gold cyanide(I) is particularly preferable.

[0034] In the electrolytic gold plating solution of the present invention, the gold cyanide salt may be used alone or in combination of two or more kinds.

[0035] There is no particular limitation on the concentration of the gold cyanide salt in the electrolytic gold plating solution (total concentration when two or more kinds of gold cyanide salts are used in combination). The concentration is preferably 0.05 g / L or more, more preferably 0.5 g / L or more, and particularly preferably 1 g / L or more, calculated as gold. The concentration is preferably 50 g / L or less, more preferably 30 g / L or less, and particularly preferably 20 g / L or less, calculated as gold.

[0036] When the concentration of the gold cyanide salt is equal to or higher than the lower limit, a normal lemon yellow electrolytic gold plating film is likely to be formed. During plating operation, the gold source, the gold cyanide salt, is consumed and the concentration of the gold cyanide salt in the electrolytic gold plating solution decreases. When the concentration falls below the above-mentioned lower limit, it is desirable to replenish the gold cyanide salt to the electrolytic gold plating solution.

[0037] On the other hand, it is advantageous from the viewpoint of cost if the concentration of the gold cyanide salt is equal to or less than the above upper limit, that is, even if the concentration of the gold cyanide salt exceeds the above upper limit, there is no particular problem in terms of the performance of the electrolytic gold plating solution, but since gold cyanide salt is very expensive, it may become uneconomical to contain it at a high concentration in the electrolytic gold plating solution.

[0038] The above description of the gold cyanide salt specifies the form in which it is present in the electrolytic gold plating solution of the present invention, but it is preferable to use the above gold cyanide salt as a raw material to be dissolved in the preparation of the electrolytic gold plating solution of the present invention.

[0039] <Specific quinone compounds> The electrolytic gold plating solution of the present invention contains one or more quinone compounds selected from the group consisting of compounds having an anthraquinone skeleton and compounds having a naphthoquinone skeleton.

[0040] The term "compound having an anthraquinone skeleton" refers to anthraquinone and a compound in which one or more hydrogen atoms of anthraquinone are substituted with a substituent. "Anthraquinone" is a general term for 1,2-anthraquinone, 1,4-anthraquinone, and 9,10-anthraquinone. From the standpoint of availability, compound stability, and the like, the compound having an anthraquinone skeleton contained in the electrolytic gold plating solution of the present invention is preferably a compound having a 9,10-anthraquinone skeleton.

[0041] The term "compound having a naphthoquinone skeleton" refers to naphthoquinone and a compound in which one or more hydrogen atoms of naphthoquinone are substituted with a substituent. "Naphthoquinone" is a general term for 1,2-naphthoquinone, 1,4-naphthoquinone, and 2,6-naphthoquinone. From the standpoint of availability, compound stability, and the like, the compound having a naphthoquinone skeleton contained in the electrolytic gold plating solution of the present invention is desirably a compound having a 1,2-naphthoquinone skeleton and / or a compound having a 1,4-naphthoquinone skeleton.

[0042] Hereinafter, "one or more quinone compounds selected from the group consisting of compounds having an anthraquinone skeleton and compounds having a naphthoquinone skeleton" may be referred to as "specific quinone compounds".

[0043] The electrolytic gold plating solution of the present invention is an electrolytic gold plating solution using a gold cyanide salt as a gold source and containing a specific quinone compound. Even if the specific quinone compound itself is not added when preparing the electrolytic gold plating solution of the present invention, so long as the specific quinone compound is generated in the plating solution and a gold cyanide salt is used as the gold source, the electrolytic gold plating solution is included in the scope of the present invention. However, from the viewpoint of adjusting the concentration in the electrolytic gold plating solution, it is desirable to add the specific quinone compound itself when preparing the electrolytic gold plating solution of the present invention.

[0044] The electrolytic gold plating solution of the present invention has good selective gold deposition properties. Specifically, the electrolytic gold plating solution of the present invention can reduce the thickness of the gold deposit film in a low current density region and can greatly increase the difference between the thickness of the gold deposit film in a low current density region and the thickness of the gold deposit film in a high current density region. Therefore, the electrolytic gold plating solution of the present invention can be said to be an electrolytic gold plating solution suitable for nickel barrier plating.

[0045] It is presumed that the electrolytic gold plating solution of the present invention has good selective gold deposition properties due to the inclusion of the specific quinone compound. Furthermore, the electrolytic gold plating film produced using the electrolytic gold plating solution of the present invention is excellent in mechanical properties, corrosion resistance, electrical properties, etc., and it is presumed that the specific quinone compound does not adversely affect the physical properties of the film.

[0046] When the specific quinone compound contained in the electrolytic gold plating solution of the present invention has a substituent, examples of such a substituent include a sulfo group, a sulfoalkyl group, a carboxy group, a hydroxy group, an alkyl group, a hydroxyalkyl group, an amino group, an alkylamino group, a dialkylamino group, a cyano group, a nitro group, and a halogen group.

[0047] The number of carbon atoms of the alkyl group or alkylene group contained in the sulfoalkyl group, the alkyl group, the hydroxyalkyl group, the alkylamino group, and the dialkylamino group is, for example, from 1 to 8. The alkyl group or the alkylene group may be linear or branched.

[0048] More specifically, examples of the halogen group include a fluoro group, a chloro group, a bromo group, and an iodo group.

[0049] The specific quinone compound contained in the electrolytic gold plating solution of the present invention may have a plurality of substituents, in which case the same substituent may be present at a plurality of positions, or different types of substituents may be present.

[0050] The specific quinone compound contained in the electrolytic gold plating solution of the present invention may be a salt, and specific types of salts include, for example, lithium salts, sodium salts, potassium salts, rubidium salts, cesium salts, beryllium salts, magnesium salts, calcium salts, strontium salts, barium salts, and ammonium salts.

[0051] Specific examples of the specific quinone compounds contained in the electrolytic gold plating solution of the present invention include anthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, dihydroxyanthraquinone, trihydroxyanthraquinone, 1,2,3,4-tetrahydroanthraquinone, 1,4,4a,9a-tetrahydroanthraquinone, hexahydroanthraquinone, 1-aminoanthraquinone, 2-aminoanthraquinone, 1-amino-4-hydroxyanthraquinone, 1-chloroanthraquinone, and 2-chloroanthraquinone. , 1,4-diaminoanthraquinone, 1,5-dichloroanthraquinone, 1,5-dihydroxyanthraquinone, 1,8-dihydroxyanthraquinone, 1,4-dihydroxyanthraquinone, 4,5-dihydroxyanthraquinone-2-carboxylic acid, 1,4-dimethylanthraquinone, 1,2,4-trihydroxyanthraquinone, 2-(hydroxymethyl)anthraquinone, 2-tert-butylanthraquinone, anthraquinone-2-carboxylic acid, anthraquinone-2,7-disulfonic acid, anthraquinone-2 ,6-disulfonic acid, anthraquinone-1,8-disulfonic acid, anthraquinone-1,5-disulfonic acid, anthraquinone-1-sulfonic acid, anthraquinone-2-sulfonic acid, anthraquinone-2,3-dimethanesulfonic acid, 1,8-dihydroxyanthraquinone-2,7-disulfonic acid, 1,5-dihydroxyanthraquinone-2,6-disulfonic acid, 1,4-dihydroxyanthraquinone-2-sulfonic acid, 1,3,4-trihydroxyanthraquinone-2-sulfonic acid, 1,2-naphthoquinone, 1,2-naphtho Examples of the sulfonic acid include quinone-4-sulfonic acid, 1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-methyl-1,4-naphthoquinone, 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, 1,4-naphthoquinone-2-sulfonic acid, 2-chloro-1,4-naphthoquinone-3-sulfonic acid, 2-bromo-1,4-naphthoquinone-3-sulfonic acid, and salts thereof. In the above specific compound names, "anthraquinone" means "9,10-anthraquinone."

[0052] From the viewpoints of high water solubility, easy availability, etc., the specific quinone compound contained in the electrolytic gold plating solution of the present invention is preferably a compound having a sulfo group, and particularly preferably a compound having two or more sulfo groups.

[0053] Among the compounds whose specific compound names are given above, anthraquinone-2-sulfonic acid and 1,2-naphthoquinone-4-sulfonic acid are specific quinone compounds having one sulfo group. In addition, anthraquinone-2,7-disulfonic acid, anthraquinone-2,6-disulfonic acid, anthraquinone-1,8-disulfonic acid, and anthraquinone-1,5-disulfonic acid are specific quinone compounds having two sulfo groups.

[0054] The specific quinone compound contained in the electrolytic gold plating solution of the present invention is particularly preferably a sodium salt of a compound having a sulfo group, from the viewpoints of high water solubility, easy availability, etc. Specific examples of such specific quinone compounds include disodium anthraquinone-2,7-disulfonate, disodium anthraquinone-2,6-disulfonate, disodium anthraquinone-1,8-disulfonate, disodium anthraquinone-1,5-disulfonate, sodium anthraquinone-2-sulfonate, and sodium 1,2-naphthoquinone-4-sulfonate.

[0055] In the electrolytic gold plating solution of the present invention, the specific quinone compound may be used alone or in combination of two or more kinds.

[0056] There is no particular limitation on the concentration of the specific quinone compound in the electrolytic gold plating solution (total concentration when two or more quinone compounds are used in combination). The concentration is preferably 20 ppm or more, more preferably 100 ppm or more, and particularly preferably 200 ppm or more. Also, it is preferably 100,000 ppm or less, more preferably 60,000 ppm or less, and particularly preferably 20,000 ppm or less.

[0057] When the concentration of the specific quinone compound is equal to or higher than the above lower limit, gold deposition during plating in a low current density range can be sufficiently suppressed, and an electrolytic gold plating film with good appearance can be easily obtained.

[0058] On the other hand, when the concentration of the specific quinone compound is equal to or lower than the upper limit, costs can be reduced (even if the specific quinone compound is added in an amount exceeding the upper limit, the effect of suppressing gold deposition in the low current density region is not improved).

[0059] The above description of the specific quinone compound specifies the form in which it is present in the electrolytic gold plating solution of the present invention, but it is preferable to use the above specific quinone compound as a raw material to be dissolved in the preparation of the electrolytic gold plating solution of the present invention.

[0060] <Alloy source metal salt> The "electrolytic gold plating film" of the present invention may contain a metal other than gold. "Containing a metal other than gold" includes not only the case where a metal other than gold is contained as an unavoidable impurity in the electrolytic gold plating film, but also the case where a metal other than gold is intentionally deposited (co-deposited). In other words, the "electrolytic gold alloy plating film" of the present invention in which a metal other than gold is intentionally deposited (co-deposited) is also included in the category of the "electrolytic gold plating film" of the present invention. In addition, "electrolytic gold alloy plating film" refers to an "electrolytic gold plating film" that contains 0.01 mass% or more of metals other than gold (gold content is less than 99.99%).

[0061] The gold content in the electrolytic gold plating film of the present invention is from 50% to 100%. The content is, for example, 80% or more, 90% or more, 95% or more, 97% or more, 99% or more, or 99.5% or more. Moreover, the content is, for example, 99.98% or less, 99.95% or less, 99.9% or less, 99.8% or less, 99.7% or less, or 99.6% or less.

[0062] In this specification, "electrolytic gold plating solution" refers to an electrolytic plating solution in which the gold content in the electrolytic plating film deposited during electrolytic plating is 50% or more and 100% or less. Electrolytic plating solutions for depositing "electrolytic gold alloy plating films" (electrolytic gold plating films containing 0.01% by mass or more of metals other than gold) are also included in the category of "electrolytic gold plating solutions."

[0063] Electrolytic gold alloy plating films, i.e., electrolytic gold plating films containing 0.01% by mass or more of metals other than gold, are known to be hard gold films suitable for applications requiring hardness and abrasion resistance, such as contact components for connectors. The electrolytic gold plating solution of the present invention may be one for depositing such a hard gold film.

[0064] The electrolytic gold plating solution of the present invention may contain one or more metal salts selected from the group consisting of cobalt salts, nickel salts, iron salts and silver salts. By adding these metal salts to the electrolytic gold plating solution of the present invention, cobalt, nickel, iron, and silver are co-deposited in the electrolytic gold plating film that is deposited, making it easier to produce an electrolytic gold alloy plating film that is suitable for applications requiring hardness.

[0065] In this specification, "one or more metal salts selected from the group consisting of cobalt salts, nickel salts, iron salts, and silver salts" may be referred to as "source metal salts for alloying". Although there is no particular limitation on the type of alloy source metal salt, it is desirable for the alloy source metal salt to be water-soluble.

[0066] Specific examples of cobalt salts include cobalt sulfate, cobalt chloride, cobalt nitrate, cobalt carbonate, cobalt phthalocyanine, cobalt stearate, cobalt disodium ethylenediaminetetraacetate, cobalt naphthenate, cobalt borate, cobalt thiocyanate, cobalt sulfamate, cobalt acetate, cobalt citrate, cobalt hydroxide, cobalt oxalate, and cobalt phosphate.

[0067] Specific examples of nickel salts include nickel sulfate, nickel acetate, nickel chloride, nickel borate, nickel benzoate, nickel oxalate, nickel naphthenate, nickel oxide, nickel phosphate, nickel stearate, nickel tartrate, nickel thiocyanate, nickel amidosulfate, nickel carbonate, nickel citrate, nickel formate, nickel cyanide, nickel hydroxide, nickel nitrate, and nickel octanoate.

[0068] Specific examples of iron salts include iron sulfate (II), iron sulfate (III), iron nitrate (II), iron nitrate (III), iron chloride (II), iron chloride (III), iron citrate (II), iron citrate (III), iron formate (II), iron formate (III), iron hypophosphite (II), iron hypophosphite (III), iron naphthenate (II), iron naphthenate (III), iron stearate (II), iron stearate (III), iron pyrophosphate (II), iron pyrophosphate (III), iron tartrate (II), iron tartrate (III), iron thiocyanate (II), iron thiocyanate (III), iron fumarate (II), iron fumarate (III), iron gluconate (II), iron gluconate (III), iron ethylenediaminetetraacetate (II), and iron ethylenediaminetetraacetate (III).

[0069] Specific examples of silver salts include silver nitrate, silver sulfate, silver carbonate, silver chloride, silver thiocyanate, silver acetate, silver citrate, silver hydroxide, silver oxalate, silver phosphate, silver borate, silver tartrate, silver cyanide, potassium silver cyanide, sodium silver cyanide, and ammonium silver cyanide.

[0070] From the above-mentioned alloy source metal salts (cobalt salt, nickel salt, iron salt and / or silver salt), an alloy source metal salt can be selected and added to the electrolytic gold plating solution of the present invention, taking into consideration plating performance, water solubility, co-deposition with the film, ease of availability, cost, and the like.

[0071] In the electrolytic gold plating solution of the present invention, the alloy source metal salt may be used alone or in combination of two or more kinds. Two or more alloy source metal salts of different metal species may be used in combination, in which case two or more metals other than gold are co-deposited in the electrolytic gold plating film.

[0072] There is no particular limitation on the concentration of the alloy source metal salt in the electrolytic gold plating solution (total concentration when two or more alloy source metal salts are used in combination). The concentration is preferably 1 ppm or more, more preferably 10 ppm or more, and particularly preferably 50 ppm or more, calculated as metal. The concentration is preferably 50,000 ppm or less, more preferably 30,000 ppm or less, and particularly preferably 10,000 ppm or less, calculated as metal.

[0073] When the concentration of the alloy source metal salt is at least the above lower limit, the co-deposition amount of cobalt, nickel, iron and / or silver becomes sufficient, making it easier to obtain an electrolytic gold plating film with high hardness. During plating operation, the alloy source metal salt is consumed and the concentration of the alloy source metal salt in the electrolytic gold plating solution decreases. When the concentration falls below the above-mentioned lower limit, it is desirable to replenish the alloy source metal salt to the electrolytic gold plating solution.

[0074] On the other hand, if the concentration of the alloy source metal salt is equal to or less than the upper limit, the amount of cobalt, nickel, iron and / or silver co-deposited is not too large, so that problems such as poor color tone and increased contact resistance of the electrolytic gold plating film are unlikely to occur. Also, even if the electrolytic gold plating solution contains an amount of the alloy source metal salt exceeding the upper limit, no further improvement in the hardness of the electrolytic gold plating film can be expected.

[0075] <Other ingredients> In addition to the above-mentioned components, other components may be added to the electrolytic gold plating solution of the present invention, if necessary. Specific examples of other components include a buffering agent for maintaining a constant pH of the electrolytic gold plating solution, a conductive salt for improving the conductivity of the electrolytic gold plating solution, a sequestering agent for removing the effects of impurity metals that may be present in the electrolytic gold plating solution, a brightener for smoothing the electrolytic gold plating film, and a surfactant for improving the defoaming properties of the electrolytic gold plating solution.

[0076] There are no particular limitations on the buffering agent added to the electrolytic gold plating solution of the present invention, and any known buffering agent can be used.

[0077] Specific examples of buffers include carboxylic acids such as adipic acid, benzoic acid, citric acid, malic acid, succinic acid, formic acid, acetic acid, lactic acid, malonic acid, phthalic acid, oxalic acid, tartaric acid, glycine, glutamic acid, glutaric acid, iminodiacetic acid, dehydroacetic acid, maleic acid, and fumaric acid, and their salts; inorganic acids such as boric acid, phosphoric acid, pyrophosphoric acid, phosphorous acid, thiosulfuric acid, sulfurous acid, nitric acid, sulfuric acid, hydrochloric acid, and thiocyanic acid, and their salts; ammonia; and amine compounds such as 1,2-ethylenediamine, hydroxyamine, ethanolamine, diethanolamine, and triethanolamine, and their salts.

[0078] More specific examples of the salts of the above-mentioned carboxylic acids and inorganic acids include lithium salts, sodium salts, potassium salts, rubidium salts, cesium salts, beryllium salts, magnesium salts, calcium salts, strontium salts, barium salts, and ammonium salts of the above-mentioned carboxylic acids and inorganic acids.

[0079] More specific examples of the salts of the above-mentioned amine compounds include the hydrochlorides, hydrobromides, hydroiodic acid salts, sulfates, nitrates, citrates and lactates of the above-mentioned amine compounds.

[0080] In the electrolytic gold plating solution of the present invention, the buffering agent may be used alone or in combination of two or more kinds.

[0081] There is no particular limitation on the concentration of the buffer in the electrolytic gold plating solution (total concentration when two or more types are used in combination). The concentration is preferably 1 g / L or more, more preferably 3 g / L or more, and particularly preferably 10 g / L or more. The concentration is preferably 500 g / L or less, more preferably 300 g / L or less, and particularly preferably 100 g / L or less. When the concentration of the buffering agent is equal to or higher than the lower limit, a sufficient buffering effect is easily exhibited, whereas when the concentration of the buffering agent is equal to or lower than the upper limit, costs can be suppressed (adding a buffering agent in an amount exceeding the upper limit does not improve the buffering effect).

[0082] The pH of the electrolytic gold plating solution of the present invention is preferably 2 or more, more preferably 3 or more, and particularly preferably 4 or more. It is also preferably 9 or less, more preferably 8 or less, and particularly preferably 7 or less. When the pH of the electrolytic gold plating solution is within the above range, the stability of the gold cyanide salt and the alloy source metal salts in the electrolytic gold plating solution can be appropriately maintained. By appropriately selecting the buffer, the pH of the electrolytic gold plating solution can be adjusted to fall within the above range.

[0083] The conductive salt to be added to the electrolytic gold plating solution of the present invention is not particularly limited, and any known conductive salt can be used. The conductive salt may be the same component as the buffer.

[0084] Specific examples of conductive salts include inorganic acids such as phosphoric acid, pyrophosphoric acid, sulfuric acid, thiosulfuric acid, nitric acid, nitrous acid, and boric acid, and their salts; carboxylic acids such as oxalic acid, succinic acid, glutaric acid, malonic acid, citric acid, tartaric acid, and malic acid, and their salts; ammonia; and amine compounds such as 1,2-ethylenediamine, hydroxyamine, ethanolamine, diethanolamine, and triethanolamine, and their salts.

[0085] More specific examples of the salts of the above-mentioned carboxylic acids and inorganic acids include lithium salts, sodium salts, potassium salts, rubidium salts, cesium salts, beryllium salts, magnesium salts, calcium salts, strontium salts, barium salts, and ammonium salts of the above-mentioned carboxylic acids and inorganic acids.

[0086] More specific examples of the salts of the above-mentioned amine compounds include the hydrochlorides, hydrobromides, hydroiodides, sulfates, nitrates, citrates and lactates of the above-mentioned amine compounds.

[0087] In the electrolytic gold plating solution of the present invention, the conductive salt may be used alone or in combination of two or more kinds.

[0088] There is no particular limitation on the concentration of the conductive salt in the electrolytic gold plating solution (total concentration when two or more kinds are used in combination). The concentration is preferably 1 g / L or more, more preferably 3 g / L or more, and particularly preferably 10 g / L or more. The concentration is preferably 500 g / L or less, more preferably 300 g / L or less, and particularly preferably 100 g / L or less. When the concentration of the conductive salt is equal to or higher than the lower limit, a sufficient conductive effect is easily exhibited, whereas when the concentration of the conductive salt is equal to or lower than the upper limit, costs can be suppressed (even if the conductive salt is added in an amount exceeding the upper limit, the conductive effect is not improved).

[0089] There are no particular limitations on the sequestering agent added to the electrolytic gold plating solution of the present invention, and any known sequestering agent can be used.

[0090] Specific examples of sequestering agents include aminocarboxylic acid chelating agents such as iminodiacetic acid, nitrilotriacetic acid, and ethylenediaminetetraacetic acid; and phosphonic acid chelating agents such as hydroxyethylidene diphosphonic acid, nitrilomethylene phosphonic acid, and ethylenediaminetetramethylene phosphonic acid.

[0091] In the electrolytic gold plating solution of the present invention, the sequestering agent may be used alone or in combination of two or more kinds.

[0092] There is no particular limitation on the concentration of the sequestering agent in the electrolytic gold plating solution (total concentration when two or more types are used in combination). The concentration is preferably 0.1 g / L or more, more preferably 0.3 g / L or more, and particularly preferably 0.5 g / L or more. It is also preferably 100 g / L or less, more preferably 70 g / L or less, and particularly preferably 50 g / L or less. When the concentration of the sequestering agent is equal to or higher than the lower limit, the effect of removing the influence of impurity metals is easily exerted sufficiently, while when the concentration of the sequestering agent is equal to or lower than the upper limit, the cost can be suppressed (even if the concentration of the sequestering agent exceeds the upper limit, the effect of removing the influence of impurity metals is not improved).

[0093] The brightener to be added to the electrolytic gold plating solution of the present invention is not particularly limited, and any known brightener can be used.

[0094] Specific examples of brighteners include thallium salts such as thallium sulfate, thallium nitrate, thallium formate, and thallium oxide; and amine compounds having a pyridine skeleton such as 2-aminopyridine, 3-aminopyridine, and 4-aminopyridine.

[0095] In the electrolytic gold plating solution of the present invention, the brightener may be used alone or in combination of two or more kinds.

[0096] There is no particular limitation on the concentration of the brightener in the electrolytic gold plating solution (total concentration when two or more types are used in combination). The concentration is preferably 0.01 g / L or more, more preferably 0.03 g / L or more, and particularly preferably 0.1 g / L or more. The concentration is preferably 20 g / L or less, more preferably 10 g / L or less, and particularly preferably 5 g / L or less.

[0097] The surfactant to be added to the electrolytic gold plating solution of the present invention is not particularly limited, and any known surfactant can be used. In addition, any of nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants can be used as the surfactant to be added to the electrolytic gold plating solution of the present invention.

[0098] Specific examples of nonionic surfactants include ester-type nonionic surfactants such as sorbitan fatty acid esters and sucrose fatty acid esters; ether-type nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers and polyoxyethylene polyoxypropylene glycols; ether-ester-type nonionic surfactants such as polyoxyethylene glycerin fatty acid esters, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters and polyoxyethylene hexitane fatty acid esters; and amide-type nonionic surfactants such as lauric acid diethanolamide, oleic acid diethanolamide and stearic acid diethanolamide.

[0099] Specific examples of anionic surfactants include sulfonate-type anionic surfactants such as sodium 1-hexanesulfonate, sodium 1-octane sulfonate, sodium 1-decanesulfonate, sodium 1-dodecanesulfonate, sodium toluenesulfonate, and sodium octylbenzenesulfonate; carboxylate-type anionic surfactants such as sodium laurate, sodium myristate, sodium palmitate, and sodium stearate; sulfate-type anionic surfactants such as sodium lauryl sulfate, sodium myristyl sulfate, sodium polyoxyethylene alkylphenol sulfonate, and ammonium lauryl sulfate; and phosphate-type anionic surfactants such as sodium lauryl phosphate and potassium lauryl phosphate.

[0100] Specific examples of cationic surfactants include amine salt-type cationic surfactants such as monomethylamine hydrochloride, dimethylamine hydrochloride, and trimethylamine hydrochloride; quaternary ammonium salt-type cationic surfactants such as tetramethylammonium chloride, tetrabutylammonium chloride, dodecyldimethylbenzylammonium chloride, alkyltrimethylammonium chloride, benzalkonium chloride, benzethonium chloride, dialkyldimethylammonium chloride, didecyldimethylammonium chloride, alkyltrimethylammonium bromide, benzyltrimethylammonium chloride, benzyltriethylammonium chloride, and benzalkonium bromide; and pyridinium salt-type cationic surfactants such as butylpyridinium chloride, dodecylpyridinium chloride, and cetylpyridinium chloride.

[0101] Specific examples of amphoteric surfactants include betaine-type amphoteric surfactants such as lauryl dimethylaminoacetate betaine, stearyl dimethylaminoacetate betaine, dodecyl aminomethyl dimethylsulfopropyl betaine, octadecyl aminomethyl dimethylsulfopropyl betaine, and 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine; amino acid-type amphoteric surfactants such as sodium lauroyl glutamate and potassium lauroyl glutamate; and amine oxide-type amphoteric surfactants such as lauryl dimethylamine N-oxide and oleyl dimethylamine N-oxide.

[0102] In the electrolytic gold plating solution of the present invention, the surfactant may be used alone or in combination of two or more kinds.

[0103] There is no particular limitation on the concentration of the brightener in the electrolytic gold plating solution (total concentration when two or more types are used in combination). The concentration is preferably 0.01 g / L or more, more preferably 0.03 g / L or more, and particularly preferably 0.1 g / L or more. The concentration is preferably 20 g / L or less, more preferably 10 g / L or less, and particularly preferably 5 g / L or less.

[0104] <Physical properties of electrolytic gold plating solution> The electrolytic gold plating solution of the present invention uses gold cyanide salt as the gold source. The ultraviolet-visible absorption spectrum is measured with an optical path length of 1 cm, and the absorbance at a wavelength of 258 nm is A 1 , the absorbance at a wavelength of 327 nm is A 2 When this is done, A 2 is 0.01 or more, and A 1 / A 2 is between 6 and 12 inclusive.

[0105] The electrolytic gold plating solution of the present invention contains one or more quinone compounds selected from the group consisting of compounds having an anthraquinone skeleton and compounds having a naphthoquinone skeleton. An aqueous solution containing a certain concentration of a compound having an anthraquinone skeleton or a naphthoquinone skeleton satisfies the above-mentioned conditions regarding absorbance.

[0106] The electrolytic gold plating solution of the present invention is applied to a nickel coating by a jet-type plating apparatus at a current density of 5 A / dm 2 Or 40A / dm 2 The gold plating film was produced by spot plating on a circle with a diameter of 1 cm at a flow rate of 18 L / min, a temperature of 50°C, and a current density of 5 A / dm 2 The film thickness at this time is T 1 , current density 40A / dm 2 The film thickness at this time is T 2 When this is done, T 1 is 0.1 μm or less, and T 2 / T 1 is 5 or more.

[0107] A "jet jet plating apparatus" is an apparatus used in a plating method (jet jet plating method) in which the plating solution is stirred by a jet using a pump. The jet jet plating method makes it easy to perform plating at a high current density.

[0108] When plating is performed using the electrolytic gold plating solution of the present invention using a jet-type plating apparatus, the electrolytic gold plating film is formed at a current of 5 A / dm 2 In the low current density region, the film thickness is small, and the 2In other words, the electrolytic gold plating solution of the present invention has good selective gold deposition properties.

[0109] When an electrolytic gold plating film is produced using a jet-type plating apparatus under the above-mentioned production conditions, the electrolytic gold plating solution of the present invention has a T 1 can be, for example, 0.08 μm or less, 0.06 μm or less, or 0.05 μm or less. In addition, when the electrolytic gold plating solution of the present invention is used to produce an electrolytic gold plating film under the above-mentioned production conditions using a jet flow plating apparatus, the electrolytic gold plating solution of the present invention has a T 2 / T 1 can also be, for example, 7 or more, 9 or more, or 10 or more.

[0110] <Conditions for electrolytic gold plating> There is no particular limitation on the thickness of the electrolytic gold plating film (the film thickness of the part intended for the formation of the electrolytic gold plating film) obtained by electrolytic plating using the electrolytic gold plating solution of the present invention. The film thickness is preferably 0.01 μm or more, more preferably 0.03 μm or more, and particularly preferably 0.1 μm or more. The film thickness is preferably 20 μm or less, more preferably 10 μm or less, and particularly preferably 5 μm or less.

[0111] There is no particular limitation on the temperature of the electrolytic gold plating solution when forming an electrolytic gold plating film using the electrolytic gold plating solution of the present invention. The temperature is preferably 15° C. or higher, more preferably 20° C. or higher, and particularly preferably 30° C. or higher. The temperature is preferably 90° C. or lower, more preferably 80° C. or lower, and particularly preferably 70° C. or lower.

[0112] There is no particular limitation on the time (plating time) required to form an electrolytic gold plating film using the electrolytic gold plating solution of the present invention. The time is preferably 1 second or more, more preferably 5 seconds or more, and particularly preferably 10 seconds or more. The time is preferably 60 minutes or less, more preferably 30 minutes or less, and particularly preferably 15 minutes or less.

[0113] When the temperature of the electrolytic gold plating solution and the plating time are within the above ranges, it is easy to achieve a film thickness within the above range.

[0114] When using electrolytic gold plating solutions, it is common to first apply a thin gold plating process, called flash gold plating, to a gold film thickness of about 0.01 μm to 0.05 μm in order to improve adhesion between the electrolytic gold plating film and the underlying metal, and then apply a thick gold plating process on top of that to the desired film thickness. The electrolytic gold plating solution of the present invention can be suitably used for the thick gold plating process. The electrolytic gold plating solution of the present invention can also be used for flash gold plating. For example, a commercially available flash gold plating solution may be used for flash gold plating, and the electrolytic gold plating solution of the present invention may be used for thick gold plating, or the electrolytic gold plating solution of the present invention may be used for both flash gold plating and thick gold plating.

[0115] The electrolytic gold plating solution of the present invention can be used for contact members such as connectors of electronic components, etc. Such applications make the most of the features of the electrolytic gold plating solution of the present invention. When the electrolytic gold plating solution of the present invention is used for such purposes, it is usually desirable to first form a nickel plating film on a base such as copper.

[0116] There is no particular limitation on the type of nickel plating solution used to form the nickel plating film, and any commonly used nickel plating solution can be used. Examples of such nickel plating solutions include a Watts bath, a sulfamine bath, and a nickel bromide bath.

[0117] The nickel plating solution used to form the nickel plating film may contain, as necessary, a pit prevention agent, a primary brightener, a secondary brightener, etc. The method of using the nickel plating solution is not particularly limited and can be used according to a conventional method.

[0118] There is no particular limitation on the thickness of the nickel plating film. The thickness is preferably 0.1 μm or more, more preferably 0.3 μm or more, and particularly preferably 0.5 μm or more. The thickness is preferably 20 μm or less, more preferably 10 μm or less, and particularly preferably 5 μm or less.

[0119] <Action / Principle> The mechanism by which the gold electrolytic plating solution of the present invention exhibits excellent selective gold deposition and maintains this property for a long period of time is not clear, but is believed to be as follows, although the present invention is not limited to the scope of the mechanism by which it operates.

[0120] The specific quinone compound contained in the electrolytic gold plating solution of the present invention is believed to play a role in suppressing the deposition of electrolytic gold plating films in the low current density region. After the specific quinone compound has played this role and is consumed, its electrolytic product is believed to be regenerated as the specific quinone compound in the electrolytic gold plating solution by electrical action again. For this reason, the electrolytic gold plating solution of the present invention is believed to have a long-lasting gold selective deposition property.

[0121] [Method of producing gold selective deposition enhancer and electrolytic gold plating solution] The present invention also relates to a selective gold deposition improver for use in an electrolytic gold plating solution that uses a gold cyanide salt as the gold source, the selective gold deposition improver being characterized in that it contains, as a main component, one or more quinone compounds selected from the group consisting of compounds having an anthraquinone skeleton and compounds having a naphthoquinone skeleton. The present invention also relates to a method for producing an electrolytic gold plating solution, which comprises dissolving a gold cyanide salt and the above-mentioned gold selective deposition enhancer in water.

[0122] The gold cyanide salt, which is the gold source of the electrolytic gold plating solution of the present invention, is very expensive, and it may be uneconomical to store it in a state where it is contained in the electrolytic gold plating solution. Furthermore, if the gold cyanide salt is stored in the form of an aqueous solution, various performance properties of the electrolytic gold plating solution may deteriorate.

[0123] For this reason, from the viewpoint of storage stability, it is desirable to prepare the electrolytic gold plating solution of the present invention by dissolving the gold cyanide salt in water immediately before use. The above "water" does not mean only pure water, but also includes an "aqueous solution" in which a solute is already dissolved.

[0124] The gold selective deposition improver of the present invention contains as its main component a specific quinone compound that is presumed to exert the gold selective deposition property in the electrolytic gold plating solution of the present invention. Furthermore, the gold selective deposition improver of the present invention does not contain a cyanide gold salt.

[0125] Specific examples of the specific quinone compound that is the main component of the gold selective deposition improver of the present invention are the same as those listed above in the section on [Electrolytic gold plating solution]. In the gold selective deposition improver of the present invention, the specific quinone compound may be used alone or in combination of two or more kinds.

[0126] The gold selective deposition improver of the present invention may contain components other than the specific quinone compound. Hereinafter, the components in the gold selective deposition improver of the present invention other than the specific quinone compound and the cyan gold salt may be referred to as "other components".

[0127] Specific examples of other components include the alloy source metal salts, buffers, conductive salts, sequestering agents, brighteners, and surfactants described above in the section on [Electrolytic gold plating solution].

[0128] By preparing the electrolytic gold plating solution by dissolving a gold cyanide salt or the like in water immediately before using the electrolytic gold plating solution, the storage stability of each component of the electrolytic gold plating solution is improved, and the electrolytic gold plating solution can fully exhibit its performance.

[0129] Since it is desirable for the gold selective deposition improver of the present invention to have good storage stability, it is desirable not to include, among other components, components that are incompatible with the specific quinone compound in the gold selective deposition improver of the present invention. Such components which need to be contained in the electrolytic gold plating solution may be dissolved in water in the same manner as gold cyanide salts when the electrolytic gold plating solution is produced.

[0130] There is no particular limitation on the form of the gold selective deposition enhancer of the present invention. For example, the gold selective deposition enhancer of the present invention may be in the form of a powder or liquid. The liquid gold selective deposition enhancer of the present invention may be an aqueous solution.

[0131] When the gold selective deposition improver of the present invention is in the form of an aqueous solution, the gold cyanide salt, etc. may be added directly to the gold selective deposition improver (aqueous solution) to produce the electrolytic gold plating solution of the present invention, or when the gold cyanide salt, etc. is added to the gold selective deposition improver (aqueous solution), water may be further added (diluted) to produce the electrolytic gold plating solution of the present invention. In the latter case, the concentration of the specific quinone compound in the gold selective deposition improver (aqueous solution) must be greater than the concentration of the specific quinone compound in the gold electroplating solution. EXAMPLES

[0132] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples as long as it does not depart from the gist of the present invention. Furthermore, when the concentration value in the composition of the electrolytic gold plating solution is a component that contains water of crystallization, the concentration value is the value calculated from the mass excluding the water of crystallization.

[0133] <Preparation of electrolytic gold plating solution> In the examples and comparative examples, the compounds shown below were used as specific quinone compounds and comparative compounds.

[0134] (Specific quinone compounds) Disodium anthraquinone-2,7-disulfonate Disodium anthraquinone-2,6-disulfonate Disodium anthraquinone-1,8-disulfonate Disodium anthraquinone-1,5-disulfonate Sodium anthraquinone-2-sulfonate Sodium 1,2-naphthoquinone-4-sulfonate

[0135] (Comparative Compound) 4-Nitropyrazole 3-Nitro-1,2,4-triazole Sodium 3-nitrobenzenesulfonate

[0136] Example 1 The following components were dissolved in water to the following concentrations, and the pH was adjusted to 4.3 to prepare an electrolytic gold plating solution.

[0137] (a) Potassium gold(I) cyanide: 9 g / L (gold equivalent) (b) Disodium anthraquinone-2,7-disulfonate: 8g / L (c) Cobalt sulfate: 200 ppm (metal (cobalt) equivalent) (d) Sequestering agent: 1g / L (e) Surfactant: 1g / L (f) Polishing agent: 1g / L (g) Citric acid: 100g / L

[0138] Incidentally, (g) citric acid was added to the electrolytic gold plating solution as a component that acts both as a conductive salt and a buffering agent.

[0139] Examples 2 to 10, Comparative Examples 1 to 4 An electrolytic gold plating solution was prepared in the same manner as in Example 1, except that the above component (b) and / or the above component (c) was changed to the substances shown in Table 1. In Example 7, the above component (c) was not added to the electrolytic gold plating solution, and in Comparative Example 1, the above component (b) was not added to the electrolytic gold plating solution.

[0140] <Measurement of UV-Visible Absorption Spectrum> The ultraviolet-visible absorption spectrum of the prepared electrolytic gold plating solution was measured using a double-beam spectrophotometer U-2910 (manufactured by Hitachi High-Tech Science Corp.) The optical path length was set to 1 cm, and the absorbance was measured from 200 to 400 nm. The obtained ultraviolet-visible absorption spectra are shown in Figs. 1 to 11. The absorbance at a wavelength of 258 nm is A 1 , the absorbance at a wavelength of 327 nm is A 2 When A is 1 / A 2 The values ​​are shown in Table 1.

[0141] [Table 1]

[0142] <Electrolytic gold plating> A copper plate measuring 20 mm x 25 mm was used as the substrate. Electrolytic nickel strike plating was applied to the copper plate so that the thickness of the electrolytic nickel strike plating film was 0.1 μm. Then, electrolytic gold plating was applied to the electrolytic nickel strike plating film using the electrolytic gold plating solution of each of the Examples and Comparative Examples. Details of the plating process are shown in Table 2.

[0143] [Table 2]

[0144] The "Electrolytic Nickel Plating A" used for the electrolytic nickel strike plating is an electrolytic nickel plating solution containing nickel chloride at a concentration of 240 g / L and hydrochloric acid at a concentration of 125 mL / L.

[0145] A jet plating apparatus was used for electrolytic gold plating. The jet nozzle was circular with a diameter of 10 mm, the flow rate of the electrolytic gold plating solution was 18 L / min, the temperature of the electrolytic gold plating solution was 50°C, and the plating time was 10 seconds.

[0146] The current density during electrolytic gold plating is 5A / dm 2 Or 40A / dm 2The study was carried out at two levels: In addition, the following two types of electrolytic gold plating solutions were used for electrolytic gold plating.

[0147] (Electrolytic gold plating solution X) Electrolytic gold plating solution immediately after preparation according to the above <Preparation of electrolytic gold plating solution>

[0148] (Electrolytic gold plating solution Y) An electrolytic gold plating solution in which the potassium cyanide gold (I) (gold source) in electrolytic gold plating solution X is consumed by a plating reaction at a rate of 9 g / L in terms of gold, and then potassium cyanide gold (I) equivalent to the amount consumed is added (replenished).

[0149] <Evaluation of electrolytic gold plating film> The thickness of the electrolytic gold plating film near the center of the circular portion of the plated object that had been electrolytically gold plated was measured using a fluorescent X-ray film thickness gauge FT150 (manufactured by Hitachi High-Tech Science Corporation). Current density 5A / dm 2 The film thickness at this time is T 1 , current density 40A / dm 2 The film thickness at this time is T 2 When this is done, T 1 is 0.1 μm or less, and T 2 / T 1 A score of 5 or more was judged as "good", and any other score was judged as "poor". The results are shown in Table 3.

[0150] [Table 3]

[0151] In Examples 1 to 10, good selective gold deposition was observed both when the electrolytic gold plating solution immediately after preparation (electrolytic gold plating solution X) was used and when the electrolytic gold plating solution in which the gold source had been consumed and then replenished with the gold source (electrolytic gold plating solution Y) was used. [Industrial Applicability]

[0152] The electrolytic gold plating solution of the present invention is capable of producing an electrolytic gold plating film having excellent mechanical properties, corrosion resistance, electrical properties, etc., and also has good selective gold deposition properties that are sustained for a long period of time, and therefore is widely used in the production of gold films in the electronics industry and the like. The electrolytic gold plating solution of the present invention is most suitable for nickel barrier plating, which is put to practical use in the manufacture of contact members for electronic devices, etc.

Claims

1. The electrolytic gold plating solution uses a gold cyanide salt as a gold source, and is characterized in that it contains one or more quinone compounds selected from the group consisting of compounds having an anthraquinone skeleton and compounds having a naphthoquinone skeleton.

2. 2. The electrolytic gold plating solution according to claim 1, wherein the quinone compound is a compound having a sulfo group.

3. 2. The electrolytic gold plating solution according to claim 1, wherein the quinone compound is a compound having two or more sulfo groups.

4. 2. The electrolytic gold plating solution according to claim 1, wherein the quinone compound is one or more compounds selected from the group consisting of disodium anthraquinone-2,7-disulfonate, disodium anthraquinone-2,6-disulfonate, disodium anthraquinone-1,8-disulfonate, disodium anthraquinone-1,5-disulfonate, sodium anthraquinone-2-sulfonate, and sodium 1,2-naphthoquinone-4-sulfonate.

5. The electrolytic gold plating solution contains gold cyanide as the gold source. The ultraviolet-visible absorption spectrum is measured with an optical path length of 1 cm, and the absorbance at a wavelength of 258 nm is expressed as A １ , and absorbance at a wavelength of 327 nm is A ２ When this is done, A ２ is 0.01 or more, and A １ / A ２ Electrolytic gold plating solution, characterized in that

6. 6. The electrolytic gold plating solution according to claim 1, further comprising at least one metal salt selected from the group consisting of cobalt salts, nickel salts, iron salts and silver salts.

7. Using a jet-type plating device, a current density of 5 A / dm was applied to the nickel coating. ２ or 40 A / dm ２ The electrolytic gold plating film was produced by spot plating in a circle having a diameter of 1 cm at a flow rate of 18 L / min, a temperature of 50° C. for 10 seconds, and a current density of 5 A / dm ２ The film thickness at this time is T １ , current density 40A / dm ２ The film thickness at this time is T ２ When this is done, T １ is 0.1 μm or less, and T ２ / T １ 6. The electrolytic gold plating solution according to claim 1, wherein the pH is 5 or more.

8. A selective gold deposition improver for an electrolytic gold plating solution that uses a gold cyanide salt as a gold source, the selective gold deposition improver being characterized by having as its main component at least one quinone compound selected from the group consisting of compounds having an anthraquinone skeleton and compounds having a naphthoquinone skeleton.

9. 9. The gold selective deposition improver according to claim 8, wherein the quinone compound is a compound having a sulfo group.

10. 9. The gold selective deposition improver according to claim 8, wherein the quinone compound is a compound having two or more sulfo groups.

11. The gold selective deposition improver according to claim 8, wherein the quinone compound is one or more compounds selected from the group consisting of disodium anthraquinone-2,7-disulfonate, disodium anthraquinone-2,6-disulfonate, disodium anthraquinone-1,8-disulfonate, disodium anthraquinone-1,5-disulfonate, sodium anthraquinone-2-sulfonate, and sodium 1,2-naphthoquinone-4-sulfonate.

12. 12. A method for producing an electrolytic gold plating solution, comprising dissolving a gold cyanide salt and the gold selective deposition improver according to claim 8 in water.

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