JP2006052431A - Tin-zinc alloy electroplating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroplating method capable of performing treatment in a short time which has been difficult by the conventional tin-zinc alloy electroplating. <P>SOLUTION: In the method, tin-zinc alloy electroplating is performed under the conditions where the temperature of a plating liquid is 30 to 90°C, the stirring rate of the plating liquid is 5 to 300 m/min, and cathode current density is 5 to 200 A/dm<SP>2</SP>. Preferably, the concentration of bivalent tin ions is 1 to 100 g/L and the concentration of zinc ions is 0.2 to 80 g/L in a tin-zinc alloy plating bath. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  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 widely used as industrial plating for automobile parts and electronic parts. As a plating bath used for this tin-zinc alloy electroplating, an alkali cyanide bath, pyrophosphoric acid bath, borofluoride bath, sulfonic acid bath, carboxylic acid bath, and the like have been proposed and partially put into practical use.
In the conventional methods using these electroplating baths, when processing at a high current density in order to shorten the processing time, rough plating, burns, burns, etc. occur and the characteristics of the tin-zinc alloy plating are impaired. Therefore, practical application of high-speed electroplating has been difficult. Actually, the rack method (maximum current density of about 3 A / dm ² ) for mounting the object to be plated on the jig and the barrel method (maximum current density of 1 A / dm ² ) for processing the object to be plated in the barrel are put into practical use. It remains to be done. In addition, when tin-zinc alloy plating is performed in a short time, a method in which tin and zinc are separately electroplated and alloyed, or a hot dipping method using a molten salt of tin-zinc alloy has been used.

  An object of this invention is to provide the electroplating method which enables the process in the short time which was difficult with the conventional tin-zinc alloy electroplating.

The present invention is based on the knowledge that tin-zinc alloy electroplating can be performed in a short time by using a specific tin-zinc alloy plating bath with the plating bath temperature and the stirring rate of the plating solution being a predetermined level or more. It was made.
That is, the present invention is a method for performing tin-zinc alloy electroplating under the conditions of plating bath temperature: 30 to 90 ° C., plating solution stirring speed: 5 to 300 m / min, and cathode current density: 5 to 200 A / dm ^2. I will provide a.

  According to the present invention, it is possible to perform electroplating of a tin-zinc alloy in a short time by using a specific tin-zinc alloy plating bath by setting the plating bath temperature and the stirring speed of the plating solution to a predetermined level or more. it can.

  The plating bath temperature in the electroplating method of the present invention is 30 to 90 ° C., preferably 40 to 60 ° C., and the stirring speed of the plating solution is 5 to 300 m / min, preferably 10 to 100 m / min. Specifically, stirring of the plating solution may be performed by a jet type plating device or a steel plate plating device in which the solution is circulated by a pump. The plating apparatus may be any heat-resistant and chemical-resistant material, and metals such as stainless steel and titanium, vinyl chloride, Teflon (registered trademark), ABS resin, and the like can be used. Moreover, in order to improve the uniformity of the plating film thickness and the plating alloy composition, an apparatus capable of obtaining a uniform plating solution stirring speed over the entire object to be plated is desirable.

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. is there.
As the hydroxycarboxylic acid, a compound having 1 or 2 or more hydroxy groups and 1 or 2 or more carboxyl groups in one molecule is preferable. Specific examples of hydroxycarboxylic acids include citric acid, tartaric acid, malic acid, glycolic acid, glyceric acid, lactic acid, β-hydroxypropionic acid, and gluconic acid. Preferred are citric acid, tartaric acid, malic acid and gluconic acid. Specific examples of the hydroxycarboxylate include alkali metal salts of the above hydroxycarboxylic acid (sodium, potassium, lithium salts), alkaline earth metal salts (magnesium, calcium, barium salts, etc.), divalent tin salts, Zinc salts, ammonium salts and organic amine salts (monomethylamine, dimethylamine, trimethylamine, ethylamine, isopropylamine, ethylenediamine, diethylenetriamine, etc.) can be mentioned. Preferred are sodium, potassium, lithium salts, divalent tin and zinc salts of citric acid, tartaric acid, malic acid or gluconic acid. These hydroxycarboxylic acids and salts thereof may be used alone or in admixture of two or more. The concentration in the plating bath is 0.25 to 3 mol / L, preferably 0.3 to 1.5 mol / L. L. When a hydroxycarboxylate is used as the divalent tin salt and / or zinc salt, the hydroxycarboxylic acid which is a counter ion of the metal ion also constitutes a part of the above concentration.
The pH of the plating bath containing hydroxycarboxylic acid or a salt thereof is preferably 2 to 10, more preferably 3 to 9. The pH of the plating bath can be adjusted using alkaline compounds such as hydroxides and carbonates, and acidic compounds such as inorganic acids and organic acids. Specifically, alkaline compounds such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, and aqueous ammonia, and acidic acids such as sulfuric acid, hydrochloric acid, sulfamic acid, methanesulfonic acid, and phenolsulfonic acid. Compounds.

In addition, the tin-zinc alloy electroplating bath used in the electroplating method of the present invention is selected from the group consisting of a water-soluble compound obtained by reacting an aliphatic amine, an organic acid ester and phthalic anhydride, and an amphoteric surfactant. Plating baths containing more than one type can also be used. Specifically, for example, 0.2 to 3 mol of an organic acid ester is reacted at a temperature of 50 to 99 ° C. for 10 to 60 minutes per 1 mol of an aliphatic amine, and the reactive product 1 obtained in a weight ratio is anhydrous. Examples thereof include water-soluble compounds obtained by reacting phthalic acid 0.1 to 1 at a temperature of 60 to 130 ° C. for 30 to 180 minutes. Examples of amphoteric surfactants include imidazoline type, betaine type, alanine type, glycine type, and amide type. Examples of the aliphatic amine used for the reaction of the water-soluble compound include ethylenediamine, triethylenetetramine, isobutylamine, 3-methoxypropylamine, iminobispropylamine, diethylamine, hexamethylenetetramine, dimethylaminopropylamine, and the like. Examples of the acid ester include dimethyl malonate, diethyl succinate, diethyl maleate, dimethyl fumarate, diethyl tartrate, dimethyl malate, and diethyl tartrate. These water-soluble compounds and amphoteric surfactants may be used alone or in admixture of two or more. The content in the plating bath is 0.001 to 50 g / L, preferably 0.01 to 30 g / L. L.
The pH of the plating bath containing one or more selected from the group consisting of a water-soluble compound obtained by reacting an aliphatic amine, an organic acid ester and phthalic anhydride and an amphoteric surfactant is preferably 2 to 10, more Preferably it is 3-9. The pH of the plating bath can be adjusted using alkaline compounds such as hydroxides and carbonates, and acidic compounds such as inorganic acids and organic acids. Specifically, alkaline compounds such as sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, and aqueous ammonia, and acidic acids such as sulfuric acid, hydrochloric acid, sulfamic acid, methanesulfonic acid, and phenolsulfonic acid. Compounds.

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 an imidazole compound and an aliphatic amine compound, and examples of the quaternary amine compound include a reaction product of a tertiary amine compound and an alkyl halide. Specific examples of the tertiary amine compound include imidazole compounds such as imidazole, 1-methylimidazole, 1-ethylimidazole, 2-methylimidazole, and 1-ethyl-2-methyl. Examples include imidazole, 1-oxymethyl imidazole, 1-vinyl imidazole and 1,5-dimethyl imidazole, and aliphatic amines include monoethanolamine, diethanolamine, triethanolamine, dimethylamine. , Ethylenediamine, diethylenetriamine, iminobispropylamine, triethylenetetramine, tetraethylenepentamine, N, N-bis- (3aminopropyl) ethylenediamine, and the like. Examples of the alkyl halide to be reacted with the tertiary amine compound include monochloroacetic acid, benzyl chloride, chloroacetamide, 3-aminobenzyl chloride, allyl chloride, dichloroethane, monochloropropane, dichloroglycerin, ethylene chlorohydrin and epichlorohydrin. It is done. These tertiary amine compounds and quaternary amine compounds may be used alone or in admixture of two or more, and the content in the plating bath is 0.1-30 g / L, preferably 0.2-20 g. / L.
The pH of the plating bath containing at least one selected from the group consisting of a tertiary amine compound and a quaternary amine compound is preferably 10-14, more preferably 12-14. The pH of the plating bath can be adjusted using an alkaline compound such as hydroxide and carbonate. Specific examples include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, and aqueous ammonia.

  The plating bath used in the electroplating method of the present invention may further contain one or more surfactants selected from the group consisting of nonionic surfactants, anionic surfactants and cationic surfactants. . By containing these surfactants, precipitation at a high current density can be made dense, so that the electroplating method of the present invention can be carried out smoothly.

  The tin ion concentration of the plating bath used in the plating method of the present invention is 1-100 g / L of divalent ions, preferably 5-80 g / L, and the zinc ion concentration is 0.2-80 g / L, preferably Is 1 to 50 g / L. Examples of these metal ion sources include hydroxide, oxide, sulfate, hydrochloride, sulfamate, pyrophosphate, hydroxycarboxylate, sulfonate, and amino acid salt of each metal. Preferred are oxides, sulfates, hydrochlorides and hydroxides of each metal. Specific examples of the hydroxycarboxylate include those exemplified above. Specific examples of the sulfonate include alkane sulfonate, alkanol sulfonate, and phenol sulfonate. Among these, specific examples of alkanesulfonic acid include methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, isopropanesulfonic acid, butanesulfonic acid, pentanesulfonic acid and hexanesulfonic acid. Specific examples include 2-hydroxyethanesulfonic acid, 3-hydroxypropanesulfonic acid, and 2-hydroxybutanesulfonic acid. Specific examples of 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.

  The plating bath used in the electroplating method of the present invention further includes an alkali metal salt of sulfuric acid, hydrochloric acid, sulfamic acid, pyrophosphoric acid, sulfonic acid, hydroxide, carbonate in order to improve the electrical conductivity during plating. (Sodium, potassium, lithium salts), alkaline earth metal salts (magnesium, calcium, barium salts), ammonium salts, organic amine salts (monomethylamine, dimethylamine, trimethylamine, ethylamine, isopropylamine, ethylenediamine, diethylenetriamine, etc.) Can be made. Specific examples include ammonium sulfate, ammonium chloride, sodium pyrophosphate, monomethyl sulfamate, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like, with ammonium sulfate, ammonium chloride, potassium hydroxide, and potassium carbonate being particularly desirable. The content of these salts is 10 to 300 g / L, preferably 50 to 200 g / L.

  The plating bath used in the electroplating method of the present invention can contain water other than the above-mentioned components, but can also contain additives used as tin and zinc brighteners. For example, synthetic polymers (polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, etc.), ketones (benzal acetone, acetophenone, etc.), aliphatic aldehydes (formalin, acetaldehyde, crotonaldehyde, etc.), aromatic aldehydes (vanillin) , Salicylaldehyde, ortho-chlorbenzaldehyde, etc.), reaction products of unsaturated aliphatic aldehydes and amine compounds, sulfur compounds (thiourea, mercaptobenzimidazole, etc.), Cu, Ni, Mn, Bi, In Etc. These additives are contained in an amount of 0.001 to 50 g / L, preferably 0.005 to 30 g / L. In addition, hydroxyphenyl compounds such as catechol, pyrogallol, hydroquinone, sulfosalicylic acid, potassium dihydroxybenzenesulfonate, and salts thereof, L-ascorbic acid, sorbitol, and the like can also be used as tin antioxidants. .

  An object to be plated in the plating method of the present invention is a metal material of Fe, Ni, Cu or an alloy based on these, and plating is performed using this as a cathode. For this counter electrode, a tin-zinc alloy or an insoluble electrode obtained by applying Pt plating to a Ti material, a carbon electrode, or the like can be used. When an insoluble anode is used, the metal concentration of the plating bath used by dissolving the above-mentioned tin and zinc metal salts directly in the plating solution or by replenishing an aqueous solution in which tin and zinc metal salts are dissolved at high concentrations. Can be maintained. The high concentration aqueous solution of the metal may contain the above hydroxycarboxylic acid or a salt thereof 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 can be 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 with a wide composition can be performed. For example, a tin-zinc alloy plating with a zinc content of 3 to 15% can be applied to an electronic component, and a tin-zinc alloy plating with a zinc content of 15 to 45% is particularly required to enhance salt water resistance and corrosion resistance. Can be applied. Furthermore, when it is going to obtain the high corrosion-resistant film | membrane which considered air | atmosphere exposure property, tin-zinc alloy plating with a zinc content rate of 50 to 90% can be given.
In the plating method of the present invention, the object to be plated is subjected to a plating process after pretreatment by a conventional method. In the pretreatment step, at least one operation of immersion degreasing, pickling, electrolytic cleaning and activation is performed. After plating, the obtained film may be washed with water and dried, and may be subjected to conventional chromate treatment and chemical conversion treatment, or inorganic and organic coating treatment.
Next, the present invention will be described by way of examples. However, the present invention is not limited thereto, and the plating solution temperature, the flow rate of the plating solution, and the composition of the plating bath to be used can be arbitrarily changed according to the purpose. Can do.

Example 1
After the steel plate was pretreated, the following plating bath was used, and electroplating was performed under the conditions of plating bath temperature: 60 ° C. and plating solution stirring speed: 50 m / min.

(Example 2)
After pre-treating the steel plate, 5 g / L of Niimen NAG-1001 manufactured by Nippon Oil & Fats Co., Ltd. as a nonionic surfactant was added to the plating bath of Example 1, plating bath temperature: 60 ° C., plating solution stirring speed: The electroplating process was performed under the condition of 30 m / min.

(Example 3)
After the steel plate was pretreated, the following plating bath was used, and electroplating was performed under the conditions of plating bath temperature: 60 ° C. and plating solution stirring speed: 30 m / min.

Example 4
After pretreatment of the phosphor bronze plate, electroplating was performed using the following plating bath under conditions of plating bath temperature: 50 ° C. and plating solution stirring speed: 60 m / min.

(Example 5)
After pretreatment of the phosphor bronze plate, electroplating was performed using the following plating bath under the conditions of plating bath temperature: 60 ° C. and plating solution stirring speed: 60 m / min.

(Comparative Example 1)
After pre-treating the steel sheet, the plating bath of Example 1 was used, and electroplating was performed under the conditions of plating bath temperature: 23 ° C. and plating solution stirring speed: 50 m / min.

(Comparative Example 2)
After pre-treating the steel sheet, the plating bath of Example 1 was used, and electroplating was performed under the conditions of plating bath temperature: 60 ° C. and plating solution stirring speed: 2 m / min.

(Comparative Example 3)
After pre-treating the steel sheet, the plating bath of Example 3 was used, and electroplating was performed under the conditions of plating bath temperature: 60 ° C. and plating solution stirring speed: 3 m / min.

Tables 1 to 2 show the plating deposition state, the alloy composition (% by weight) of the deposited film, the treatment time, and the film thickness of Examples 1 to 5 and Comparative Examples 1 to 3.

処理時間の単位はすべてsec.である。
○：緻密で平滑な析出
△：部分的に粗析出の発生
×：粉末状の粗い析出 Table 1

The unit of processing time is all sec.
○: Precise and smooth precipitation Δ: Occurrence of partially rough precipitation ×: Powdery rough precipitation

処理時間の単位はすべてsec.である。
○：緻密で平滑な析出
△：部分的に粗析出の発生
×：粉末状の粗い析出





Table 2

The unit of processing time is all sec.
○: Precise and smooth precipitation Δ: Occurrence of partially rough precipitation ×: Powdery rough precipitation

処理時間の単位はすべてsec.である。
○：緻密で平滑な析出
△：部分的に粗析出の発生
×：粉末状の粗い析出 Table 3

The unit of processing time is all sec.
○: Precise and smooth precipitation Δ: Occurrence of partially rough precipitation ×: Powdery rough precipitation

Claims (6)

A tin-zinc alloy electroplating method performed under the following conditions.
Plating bath temperature: 30 to 90 ° C.
Stirring speed of plating solution: 5-300 m / min, and cathode current density: 5-200 A / dm ² .   The method according to claim 1, wherein the tin-zinc alloy plating bath contains hydroxycarboxylic acid or a salt thereof, and the pH of the tin-zinc alloy plating bath is 2-10.   The tin-zinc alloy plating bath contains at least one selected from the group consisting of a water-soluble compound obtained by reacting an aliphatic amine, an organic acid ester, and phthalic anhydride, and an amphoteric surfactant, and a tin-zinc alloy plating bath The method according to claim 1, wherein the pH of the is 2-10.   The tin-zinc alloy plating bath contains at least one selected from the group consisting of a tertiary amine compound and a quaternary amine compound, and the pH of the tin-zinc alloy plating bath is 10 to 14. Method.   The method of any one of Claims 1-4 in which a tin-zinc alloy plating bath contains 1 or more types chosen from the group which consists of a nonionic surfactant, an anionic surfactant, and a cationic surfactant.   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. Method.