KR20070031442A - Tin-zinc alloy electroplating method - Google Patents

Abstract

It is an object of the present invention to provide an electroplating method which enables the treatment in a short time which was difficult in conventional tin-zinc alloy electroplating. The present invention provides a method of electroplating tin-zinc alloy under the conditions of plating solution temperature: 30 to 90 ° C, stirring rate of plating solution: 5 to 300 m / min, and cathode current density: 5 to 200 A / dm ² . Preferably, the divalent tin ion concentration in the tin-zinc alloy plating bath is 1 to 100 g / L, and the zinc ion concentration is 0.2 to 80 g / L.

Tin, zinc, alloy, electroplating, temperature, stirring speed

Description

Tin-Zinc Alloy Electroplating Method {TIN-ZINC ALLOY ELECTROPLATING METHOD}

The present invention relates to a tin-zinc alloy electroplating method.

Since tin-zinc alloy electroplating is excellent in corrosion resistance, workability, and solderability, it has been attracting attention and has been widely used as industrial plating for automobile parts and electronic parts. Alkali cyanide baths, pyrroline baths, boron fluoride baths, sulfonic acid baths, carboxylic acid baths and the like are used for the tin-zinc alloy electroplating. It has been proposed and brought to practical use.

In the conventional method using such an electroplating bath, when treated at a high current density in order to shorten the treatment time, plating deposition, burning, pressing, etc. occur, and the characteristics of the tin-zinc alloy plating are impaired. The practical use of the plating was difficult. In practice, the lock method (mounting current to be processed at the maximum current density of 3A / dm ² ) by mounting the plated object on the jig and the barrel method (maximum current density 1A / dm ² ) to process the plated material in the barrel are put to practical use. I stay. Moreover, when tin-zinc alloy plating is performed for a short time, the method of electroplating and alloying tin and zinc separately, respectively, or the hot-dip plating method by the molten salt of a tin-zinc alloy has been used.

Problems to be Solved by the Invention

An object of the present invention is to provide an electroplating method which enables a treatment in a short time which is difficult in conventional tin-zinc alloy electroplating.

Means for solving the problem

The present invention has been made based on the knowledge that the tin-zinc alloy electroplating can be performed in a short time by setting the plating bath temperature and the stirring speed of the plating liquid to a predetermined value or more and using a specific tin-zinc alloy plating bath.

That is, the present invention provides a method of electroplating tin-zinc alloy under the conditions of the plating bath temperature: 30 to 90 ° C, the stirring speed of the plating solution: 5 to 300 m / min, and the cathode current density: 5 to 200 A / dm ² .

Effect of the Invention

According to the present invention, electroplating of a tin-zinc alloy can be made possible in a short time by setting the plating bath temperature and the stirring speed of the plating liquid to a predetermined value or more and using a specific tin-zinc alloy plating bath.

The plating bath temperature in the electroplating method of this invention is 30-90 degreeC, Preferably it is 40-60 degreeC, The stirring speed of a plating liquid is 5-300 m / min, Preferably it is 10-100 m / min. Specifically, the stirring of the plating liquid can be carried out by applying a jet plating apparatus or a plating apparatus of a steel sheet to circulate liquid by a pump. The plating apparatus may be any material of heat and chemical resistance, and may be made of metal such as stainless steel or titanium, vinyl chloride, Teflon, or ABS (acrylonitrile butadiene styrene) resin. Etc. can be used. Moreover, in order to improve the uniformity of plating film thickness and plating alloy composition, the apparatus by which the stirring speed of the plating liquid uniform with respect to the whole to-be-plated object is obtained is preferable.

As the tin-zinc alloy electroplating bath used in the electroplating method of the present invention, any plating bath known to those skilled in the art can be used, but is preferably a plating bath containing hydroxycarboxylic acid or a salt thereof. .

As the hydroxycarboxylic acid, a compound having one or two or more hydroxy groups and one or two or more carboxyl groups in one molecule is preferable. Examples of specific hydroxycarboxylic acids include citric acid, tartaric acid, malic acid, glycolic acid, glycerin acid, lactic acid, β-hydroxypropionic acid and gluconic acid. Can be mentioned. Preferably, citric acid, tartaric acid, malic acid and gluconic acid. Moreover, as a specific example of hydroxycarboxylic acid salt, the alkali metal salt (sodium, potassium, lithium salt) of the said hydroxycarboxylic acid, alkaline earth metal salt (magnesium, calcium, barium salt, etc.), divalent tin salt, zinc salt, Ammonium salts and organic amine salts (monomethylamine, dimethylamine, trimethylamine, ethylamine, isopropylamine, ethylenediamine, diethylenetrimaine and the like). Preferred are sodium, potassium, lithium salts, divalent tin and zinc salts of citric acid, tartaric acid, malic acid or gluconic acid. These hydroxycarboxylic acid and its salt may be used individually or in mixture of 2 or more types, The density | concentration in a plating bath is 0.25-3 mol / L, Preferably it is 0.3-1.5 mol / L. In addition, when hydroxycarboxylate is used as a divalent tin salt and / or zinc salt, the hydroxycarboxylic acid which is a counter ion of a metal ion also comprises a part of said concentration.

The pH of the plating bath containing hydroxycarboxylic acid or its salt is preferably 2-10, more preferably 3-9. The pH of the plating bath can be adjusted using alkaline compounds such as hydroxides and carbonates, acidic compounds such as inorganic acids and organic acids, and the like. Specifically, alkaline compounds such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, ammonia water, sulfuric acid, hydrochloric acid, sulfamic acid, methanesulfonic acid, and phenol sulfonic acid Acid compounds, such as), are mentioned.

Moreover, the tin-zinc alloy electroplating bath used for the electroplating method of this invention is a 1 or more types chosen from the group which consists of a water-soluble compound in which aliphatic amine, organic acid ester, and phthalic anhydride reacted, and an amphoteric surfactant. It is also possible to use a plating bath containing. Specifically, for example, 0.2 to 3 moles of an organic acid ester per mole of aliphatic amine is reacted at a temperature of 50 to 99 ° C. for 10 to 60 minutes, and 0.1 to 1 phthalic anhydride is used at a temperature of 60 to 130 ° C. for the reactive product 1 obtained in a weight ratio. And a water-soluble compound reacted for 30 to 180 minutes. Examples of the amphoteric surfactant include imidazoline type, betaine type, alanine type, glycine type, amide type and the like. Examples of the aliphatic amine used for the reaction of the water-soluble compound include ethylenediamine, triethylenetetramine, isobutylamine, 3-methoxypropylamine, iminobispropylamine, diethylamine, hexamethylenetetramine, and dimethylamino. And propylamine (dimethylaminopropylamine). Examples of the organic acid ester include dimethyl malonate, diethyl succinate, diethyl maleate, dimethyl fumarate, diethyl stannate, dimethyl malate, and tartaric acid. Ethyl (diethyl tartronate) etc. are mentioned. These water-soluble compounds and an amphoteric surfactant may be used individually or in mixture of 2 or more types, and content in a plating bath is 0.001-50 g / L, Preferably it is 0.01-30 g / L.

The pH of the plating bath containing at least one selected from the group consisting of a water-soluble compound in which an aliphatic amine, an organic acid ester and a phthalic anhydride are reacted, and an amphoteric surfactant is preferably 2-10, more preferably 3-9. . The pH of the plating bath can be adjusted using alkaline compounds such as hydroxides and carbonates, acidic compounds such as inorganic acids and organic acids, and the like. Specifically, alkaline compounds, such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, and ammonia water, and acidic compounds, such as sulfuric acid, hydrochloric acid, sulfamic acid, methanesulfonic acid, and phenolsulfonic acid, are mentioned.

Moreover, the plating bath containing 1 or more types chosen from the group which consists of a tertiary amine compound and a quaternary amine compound can also be used as a tin-zinc alloy electroplating bath used for the electroplating method of this invention. Examples of the tertiary amine compound include imidazole compounds and aliphatic amine compounds. Examples of the quaternary amine compounds include reaction products of tertiary amine compounds and alkyl halides. Specific tertiary amine compounds are, for example, imidazole, 1-methylimidazole, 1-ethylimidazole, 2-methylimidazole, 1-ethyl-2-methyl as imidazole compounds. Imidazole, 1-oxymethylimidazole, 1-vinylimidazole, and 1,5-dimethylimidazole. Examples of the aliphatic amines include monoethanolamine, diethanolamine, triethanolamine, and dimethyl. Amine, ethylenediamine, diethylenetriamine, iminobispropylamine, triethylenetetramine, tetraethylenepentamine, N, N-bis- (3-aminopropyl) ethylenediamine, etc. are mentioned. As the halogenated alkyl reacted with the tertiary amine compound, for example, monochloroacetic acid, benzyl chloride, chloroacetamide, 3-aminobenzyl chloride, aryl chloride, dichloroethane, monochloropropane, dichloroglycerine, ethylene Chlorohydrin and epichlorohydrine. These tertiary amine compounds and quaternary amine compounds may be used alone or in combination of two or more thereof, and the content is 0.1 to 30 g / L, preferably 0.2 to 20 g / L in the plating bath.

The pH of the plating bath containing at least one type selected from the group consisting of tertiary amine compounds and quaternary amine compounds is preferably 10 to 14, more preferably 12 to 14. The pH of the plating bath can be adjusted using alkaline compounds such as hydroxides and carbonates. Specifically, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, ammonia water, etc. are mentioned.

The plating bath used in the electroplating method of the present invention may further contain at least one surfactant selected from the group consisting of nonionic surfactants, anionic surfactants and cationic surfactants. By containing these surfactant, precipitation at high current density can be made compact, and the electroplating method of this invention can be performed smoothly.

The tin ion concentration of the plating bath used in the plating method of the present invention is 1 to 100 g / L of divalent ions, preferably 5 to 80 g / L, and a zinc ion concentration of 0.2 to 80 g / L, preferably 1 to 1. 50 g / L. Examples of these metal ion sources include hydroxides, oxides, sulfates, hydrochlorides, sulfamates, pyrrolates, hydroxycarboxylates, sulfonates and amino acid salts of the respective metals. Preferred are oxides, sulfates, hydrochlorides, hydroxides of the respective metals. Specific examples of the hydroxycarboxylates include those exemplified above. Specific examples of the sulfonate include alkanesulfonate, alkanol sulfonate, and phenol sulfonate. Of these, specific examples of alkanesulfonic acid include methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, isopropanesulfonic acid, isopropanesulfonic acid, butanesulfonic acid, pentansulfonic acid and hexanesulfonic acid, and specific examples of alkanolsulfonic acid include 2-hydroxyethanesulfonic acid 2-hydroxyethanesulfonic acid), 3-hydroxypropanesulfonic acid, and 2-hydroxybutanesulfonic acid. Specific examples of the phenol sulfonic acid include phenol sulfonic acid, cresol sulfonic acid and dimethyl phenol sulfonic acid. Specific examples of amino acids include glycine, glutamic acid and alanine.

In the plating bath used in the electroplating method of the present invention, alkali metal salts (sodium, potassium, lithium salts) of sulfuric acid, hydrochloric acid, sulfamic acid, pyrroline acid, sulfonic acid, hydroxide, and carbonate are used in order to improve the electrical conductivity during plating. ), Alkaline earth metal salts (magnesium, calcium, barium salts), ammonium salts, organic amine salts (monomethylamine, dimethylamine, trimethylamine, ethylamine, isopropylamine, ethylenediamine, diethylenetriamine, etc.) It can be contained. Specific examples include ammonium sulfate, ammonium chloride, sodium pyrrolate, monomethyl sulfamate, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and the like. Ammonium sulfate, ammonium chloride, potassium hydroxide, potassium carbonate Particularly preferred. The content of these salts is 10 to 300 g / L, preferably 50 to 200 g / L.

Although the plating bath used for the electroplating method of this invention can be called water other than the said containing component, it can also contain the additive used as a gloss agent of tin and zinc. For example, synthetic polymers (polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, etc.), ketones (benzaacetone, acetophenone, etc.), aliphatic aldehydes (formalin) (formaline), acetaldehyde, crotonaldehyde, etc.), aromatic aldehydes (vanillin, salicylaldehyde, orthochlorobenzaldehyde, etc.), reaction products by unsaturated aliphatic aldehydes and amine compounds, sulfur compounds (thio) Urea (thiourea), mercaptobenzimidazole, etc.), Cu, Ni, Mn, Bi, In, etc. are mentioned. Such additives preferably contain 0.001 to 50 g / L, preferably 0.005 to 30 g / L. Moreover, hydroxyphenyl compounds, such as catechol, pyrogallol, hydroquinone, sulfosalicylic acid, and potassium dihydroxybenzenesulfonate, as tin antioxidants And salts thereof, L-ascorbic acid, sorbitol, or the like.

The to-be-plated material in the plating method of this invention is a metal material of Fe, Ni, Cu, or these alloys, and it plating by using this as a cathode. As the counter electrode, an insoluble electrode, a carbon electrode, or the like in which Pt plating is performed on a tin-zinc alloy or a Ti material can be used. In the case of using an insoluble anode, the metal concentration of the plating bath can be maintained by directly dissolving the metal salts of tin and zinc in the plating solution or by supplying an aqueous solution in which the metal salts of tin and zinc are dissolved in high concentration. The high concentration aqueous solution of this metal may contain said hydroxycarboxylic acid or its salt, and an alkali hydroxide compound.

The cathode current density is 5 to 200 A / dm ² , preferably 10 to 120 A / dm ² , and the film thickness is possible in a wide range, but is generally 0.5 to 500 μm, preferably 2 to 20 μm.

By varying the ratio of tin ions and zinc ions in the plating bath to be used, tin-zinc alloy plating of a wide composition can be performed. For example, an electronic component can be tin-zinc alloy plated with a zinc content of 3 to 15%, and tin-zinc alloy plated with a zinc content of 15 to 45% can be applied when the salt water resistance or corrosion resistance is particularly enhanced. . In addition, in order to obtain a high corrosion-resistant film in consideration of atmospheric exposure, tin-zinc alloy plating having a zinc content of 50 to 90% can be performed.

In the plating method of this invention, a to-be-plated object is referred to a plating process after pre-processing by a conventional method. In the pretreatment step, at least one operation of dipping degreasing, pickling, electrolytic cleaning and activation is performed. After plating, the obtained film may be washed with water and dried, and chromate treatment and chemical conversion treatment by conventional methods or coating treatment with inorganic and organic substances may be performed.

Next, although an Example demonstrates this invention, this invention is not limited to this, The plating liquid temperature, the flow rate of a plating liquid, and the composition of the plating bath to be used can be arbitrarily changed according to the objective.

(Example 1)

After the steel plate was pretreated, the following plating bath was used to perform electroplating treatment under the conditions of a plating bath temperature of 60 ° C. and a stirring speed of a plating solution of 50 m / min.

First tin sulfate 으로서 (as tin) 30 g / L

Zinc sulfate (as zinc) 25 g / L

Citric Acid 150g / L (0.71mol / L)

Ammonium Sulfate 100g / L

10 ml / L of 1 mol of ethylenediamine and 1 mol of dimethyl malonate

For product 1 reacted at 85 ° C. for 60 minutes

90 minutes of 95% phthalic anhydride by weight ratio by 95 degreeC

Reacted product

pH4 (adjusted with ammonia water)

(Example 2)

After pretreatment of the steel sheet, 5 g / L of Niamine NAG-1001 manufactured by Nippon Oil and Fats Co., Ltd. was added to the plating bath of Example 1 as a nonionic surfactant, and the plating bath temperature was 60 ° C. and the stirring rate of the plating solution was 30 m / min. The electroplating process was performed under the conditions of.

(Example 3)

After the steel plate was pretreated, the following plating bath was used to perform electroplating treatment under the conditions of a plating bath temperature of 60 ° C. and a stirring speed of a plating solution of 30 m / min.

Potassium Tartrate (as Tin) 55g / L

Zinc Oxide (as Zinc) 5g / L

Potassium hydroxide 80g / L

Potassium Carbonate 100g / L

1 mol of 1-methylimidazole and 1 g / L of benzyl chloride

Product which reacted 1 mol 180 minutes at 85 degreeC

1 mole of diethylenetriamine and 1 g / L of ethylenechlorohydrin

Product which reacted 1 mol at 90 degreeC for 90 minutes

pH14

(Example 4)

After the phosphor bronze plate was pretreated, the plating bath was subjected to electroplating under the conditions of a plating bath temperature of 50 ° C. and a stirring speed of a plating solution of 60 m / min.

First tin sulfate 으로서 (as tin) 20 g / L

Zinc sulfate 으로서 (as zinc) g 7 g / L

Citric Acid 120g / L (0.57mol / L)

Ammonium Sulfate 80g / L

1 mol of triethylenetetramine and diethyl succinate 10ml / L

Product 1 reacted with 1.2 moles at 80 ° C. for 40 minutes

Phthalic anhydride of 0.7 by weight ratio

Product reacted at 90 ° C. for 120 minutes

Palm oil alkyl-N-carboxyethyl-N-5 g / L

Sodium Hydroxyethylimidazolium Betaine

pH5.5 (adjust with sodium hydroxide)

(Example 5)

After the phosphor bronze plate was pretreated, an electroplating treatment was carried out using a plating bath described below under the conditions of a plating bath temperature of 60 ° C. and a stirring speed of a plating solution of 60 m / min.

Methanesulfonic acid tin 으로서 (as tin) 30 g / L

Zinc methane sulfonate (as zinc) 15 g / L

Sodium Gluconate 150g / L (0.69mol / L)

Methanesulfonic Acid 100g / L

8 ml / L of 1 mol of ethylenediamine and 1 mol of dimethyl maleate

For product 1 reacted at 90 ° C. for 60 minutes,

Phthalic anhydride of 0.5 by weight ratio at 110 ℃

Product reacted for 150 minutes

Salicylate 0.05g / L

pH6.2 (adjusted with sodium hydroxide)

(Comparative Example 1)

After the steel plate was pretreated, the plating bath of Example 1 was used to perform electroplating under the conditions of a plating bath temperature of 23 ° C. and a stirring speed of a plating solution of 50 m / min.

(Comparative Example 2)

After the steel plate was pretreated, the plating bath of Example 1 was subjected to electroplating under the conditions of a plating bath temperature of 60 ° C. and a stirring speed of a plating solution of 2 m / min.

(Comparative Example 3)

After the steel plate was pretreated, the plating bath of Example 3 was used to perform electroplating under the conditions of a plating bath temperature of 60 ° C. and a stirring speed of 3 m / min.

The plating precipitation state, alloy composition (weight%) of a precipitation film, processing time, and film thickness of Examples 1-5 and Comparative Examples 1-3 are shown in Tables 1-2.

Units of processing time are all seconds.

○: dense and smooth precipitation

△: occurrence of flaw deposition

× ： powdery coarse precipitation

Units of processing time are all seconds.

○: dense and smooth precipitation

△: occurrence of flaw deposition

× ： powdery coarse precipitation

Units of processing time are all seconds.

○: dense and smooth precipitation

△: occurrence of flaw deposition

× ： powdery coarse precipitation

Claims (6)

The tin-zinc alloy electroplating method performed on condition of the following. Plating bath temperature: 30 to 90 ° C Stirring Speed of Plating Solution: 5 to 300 m / min, and Cathode current density: 5 to 200 A / dm ² . The method of claim 1, Tin-zinc alloy plating bath, A hydroxycarboxylic acid or a salt thereof, and the tin-zinc alloy plating bath has a pH of 2 to 10. The method of claim 1, Tin-zinc alloy plating bath, A method containing at least one member selected from the group consisting of a water-soluble compound in which an aliphatic amine, an organic acid ester and a phthalic anhydride are reacted, and an amphoteric surfactant, and the pH of the tin-zinc alloy plating bath is 2 to 10. The method of claim 1, Tin-zinc alloy plating bath, A method containing at least one member selected from the group consisting of a tertiary amine compound and a quaternary amine compound, wherein the tin-zinc alloy plating bath has a pH of 10 to 14. The method according to any one of claims 1 to 4, Tin-zinc alloy plating bath, A method comprising at least one member selected from the group consisting of nonionic surfactants, anionic surfactants and cationic surfactants. The method according to any one of claims 1 to 5, The divalent tin ion concentration in the tin-zinc alloy plating bath, 1 to 100 g / L, and zinc ion concentration is 0.2 to 80 g / L.