KR20190068046A - Immersion Tin Plating Solution Using Ionic Liquid Electrolyte materials - Google Patents

Abstract

The present invention relates to an electroless tin plating solution and, more specifically, relates to an electric component as an electroless tin plating solution containing an ionic liquid electrolyte or an ionic liquid material and a composition of an electroless tin plating solution for high speed plating. More specifically, the present invention relates to an electroless tin plating solution composition, wherein using reaction of DES containing choline chloride and urea series or a carboxylic acid in choline chloride, a chelating agent and a tin salt are dissolved in an electrolyte to dissolve a metal salt for tin to be plated in copper and a copper alloy.

Description

{Immersion Tin Plating Solution Using Ionic Liquid Electrolyte Materials Using Ionic Liquid Electrolyte}

The present invention relates to an electroless tin plating solution, and more particularly, to an electroless tin plating solution containing an ionic liquid electrolyte or an ionic liquid material.

The electroless tin plating solution applied to the PCB or electrical parts is prepared by dissolving tin salt in organic acid or inorganic acid to make an electroless tin solution and commercialized in the market. In particular, in the case of methane sulfonic acid (MSA), which is a substance used in electroless tin plating, a methane sulfonic acid bath has been used in the past as being environmentally friendly. (Metal Finishing, January, AESF, p. 17 (1990)).

However, the inorganic impurities contained in the methane sulfonic acid remove the hydrochloric acid through the purification process. However, hydrochloric acid is not completely removed from commercially available methane sulfonic acid and remains at a level of several to several tens ppm. The hydrochloric acid thus left deteriorates the plating efficiency in the plating process of the actual production site and adversely affects the plating film, thereby increasing the defect rate. In addition, the sulfur compounds that are generated incidentally in the synthesis of methanesulfonic acid also affect the plating characteristics and adversely affect the quality of wastewater treatment and tin plating due to residual hydrochloric acid and sulfur compounds.

Alkanesulfonic acids such as methanesulfonic acid, ethanesulfonic acid and propanesulfonic acid; Alkanol sulfonic acids such as 2-hydroxyethanesulfonic acid and 2-hydroxypropanesulfonic acid; a tin plating bath containing an organic sulfonic acid such as an aromatic sulfonic acid such as p-phenol sulfonic acid as a base acid has a high stability of a plating solution and is excellent in a coating film of a plated tin plating and is widely used conventionally. (Korean Patent No. 10-1574229, and Korean Patent No. 10-1608073).

In such tin plating baths and tin alloy plating baths using an organic sulfonic acid, especially a commonly used aliphatic sulfonic acid such as an alkane sulfonic acid as a base acid, there is a certain correlation between the purity of the aliphatic sulfonic acid and the characteristics of the resulting plating film. Recently, And the like. In particular, if the purity of the aliphatic sulfonic acid is low and even a small amount of impurities are included, there is a problem that the characteristics of the plated film adversely affect the properties.

The general characteristic of ionic liquids is that they consist of organic cations and organic / inorganic anions. Due to the asymmetry of size, they can not form crystals, and the lattice energy of the crystal structure decreases, And the like. Ionic liquid has low vapor pressure, is non-flammable, has high ionic conductivity due to high density of ion movement, has electrochemically stable characteristics and stable characteristics at high temperature, and has many advantages in high temperature tin plating It is the material that we have.

In addition, ionic liquids are called clean organic solvents and electrolytes in the future. In recent years, ionic liquids have been used in various fields such as electrolyte, electrochemical and separation processes of fuel cells and solar cells, (Korean Patent No. 10-1630210, Korean Patent No. 10-1473039, and Korean Patent No. 10-1488781).

As for electronic parts and automobile electric parts, replacement of environmentally friendly substances due to environmental hazards of Pb is essential, and tin is the most interested substance. Immersion Tin plating, which is the most used surface treatment in the industry, is applied to many industrial fields such as plating of printed circuit boards and various electronic parts.

As a result, the inventors of the present invention have made efforts to improve the problem of the electrolytic solution for electroless tin plating as described above. As a result, the present inventors have found that by using a reaction of carboxylic acid with choline chloride and DES or choline chloride containing urea, Dissolving thiourea in an electrolyte to dissolve thiourea in the solution to make tin plating on the copper. The present invention also provides an electroless tin plating solution that is environmentally friendly and stable at an optimum blending ratio and can be stably electrolessly tinned at a high temperature And the thickness of the tin plating rapidly precipitated, thereby completing the present invention.

Korean Patent No. 10-1574229 and Korean Patent No. 10-1608073

An object of the present invention is to provide an electroless tin plating solution containing an ionic liquid electrolyte or an ionic liquid material, which is environmentally friendly and can be stably electrolessly tinned at a high temperature, and a preparation method thereof .

It is still another object of the present invention to provide an electroless tin plating solution containing the ionic liquid electrolyte or the ionic liquid material according to the present invention and a electroless tin plating solution for forming a tin coating on copper or a copper alloy using the electroless tin plating solution. The present invention provides an electroless tin plating composition and an electroless tin plating method capable of inhibiting the oxidation of tin salts as tin-plated copper.

In order to achieve the above object, the present invention provides a composition of a plating solution for electroless tin plating comprising an ionic liquid mixed with choline chloride and urea, and choline chloride and citric acid.

The present invention also provides an electroless tin plating solution composition comprising an ionic liquid mixed with choline chloride and urea, and choline chloride and citric acid, wherein the plating solution composition is capable of tin plating at a high temperature.

The present invention also provides a plating solution composition capable of tin plating while preventing the oxidation of tin salts as an electroless tin plating solution composition containing an ionic liquid and choline chloride and citric acid mixed with chloride chloride and urea do.

In addition, the present invention provides an electroless tin plating method using the electroless tin plating solution according to the present invention.

The present invention also provides an electroless tin plating solution composition comprising an ionic liquid mixed with choline chloride and urea, and choline chloride and citric acid, which is environmentally friendly and has high ionic conductivity, tin salts And has oxidation stability. In addition, the electroless tin plating composition comprising choline chloride and urea mixed ionic liquid and choline chloride and citric acid according to the present invention enables rapid and stable precipitation of metal, And can be used as an electroless tin plating solution for rapidly and thickly growing tin coatings on copper or copper alloys in electronic parts.

Figure 1 shows the thickness of the electroless tin plating film with plating time in the plating solution containing DES and the ionic liquid material.
FIG. 2 is a graph showing the relationship between electroless tin plating film texture

Hereinafter, the present invention will be described in detail.

The present invention relates to an electroless tin salt composition comprising an ionic liquid in which choline chloride and urea are mixed, wherein the ionic liquid is prepared by mixing choline chloride and urea in a molar ratio of 5: 5 to 6: 4, (Deep Eutectic Solvent).

The DES electrolyte composition may further include one or more additives.

The additive may be selected from the group consisting of ethylene glycol, ethylene alcohol, propylene glycol, propyl alcohol, malonic acid, succinic acid, and oxalic acid. , And more preferably ethylene glycol, malonic acid, or oxalic acid. [0029] The term " anionic surfactant "

The additive is preferably mixed at 1: 0.1 to 0.5 molar ratio with respect to either choline chloride or urea, more preferably mixed at a molar ratio of 1: 0.5.

The temperature of the electrolyte is preferably in the range of 30 to 90 占 폚. Here, when the temperature of the electrolyte is low in the range of 30 to 90 占 폚, the electrolyte has a high viscosity, and the plating solution on the plated substrate can not be satisfactorily separated. Therefore, the temperature of the electrolyte should preferably be at least 30 캜 or higher. As the temperature of the electrolyte increases, the viscosity decreases and the separation of the tin plating solution improves. However, when the temperature of the electrolyte becomes higher than 90 ° C, bubbles and smoke are generated violently during plating, thereby causing contamination of the working environment, or disassembling the electroless tin alloy.

The electrolyte is preferably used for electroless tin plating.

The present invention also provides a method for preparing an ionic liquid electrolyte composition for electroless tin plating, comprising mixing an ionic liquid by mixing choline chloride and urea.

The present invention also relates to a process for the production of an ionic liquid by mixing choline chloride and urea to produce an ionic liquid; And mixing the ionic liquid with an additive. The present invention also provides a method for preparing an ionic liquid electrolyte composition for electroless tin plating.

The choline chloride and urea are preferably mixed in a molar ratio of 5: 5 to 6: 4, more preferably 1: 1.

The additive is preferably mixed at 1: 0.1 to 0.5 molar ratio with respect to either choline chloride or urea, more preferably mixed at a molar ratio of 1: 0.5.

The kind of the additive is as described above.

The present invention also provides an electroless tin plating solution containing the ionic liquid electrolyte composition according to the present invention.

The electroless tin plating solution may further comprise at least one of a tin salt, a complexing agent, a surfactant or an antioxidant in addition to the tin compound and the ionic liquid electrolyte composition according to the present invention.

The tin salt serves to supply an ionic ion for forming a plating film in the electroless tin plating and contributes to the quality of the plating film such as appearance, denseness, smoothness, and adhesion of the plating film. The tin salt generally contains tin methane sulfonate, Tin sulfate, tin chloride, and the like may be used. The concentration of the tin salt in the electroless tin plating solution is not particularly limited, but is preferably about 5 g / L to 100 g / L.

The surfactant contributes to the improvement of appearance, compactness, smoothness and adhesiveness of the plated film, and various surfactants such as usual nonionic, anionic, cationic or amphoteric surfactants can be used. The surfactants may be used alone or in combination of two or more. The concentration of the surfactant in the electroless plating solution is not particularly limited, but it is preferably about 0.01 g / L to 50 g / L.

The complexing agent is capable of tin plating as a material for forming a plating on a copper or copper alloy material and contributes to the improvement of the appearance, compactness, smoothness, adhesion, etc. of the plating film, and a conventional thiourea . Although the concentration of the complexing agent in the electroless tin plating solution is not particularly limited, it is preferably about 60 g / L to 200 g / L.

The antioxidant is for the purpose of preventing the oxidation of tin and the like in the electroless plating solution and may be a hydroquinone such as hydroquinone, catechol, resorcin, proglycine, hydrazine, hypophosphorous acid, ascorbic acid, cresol sulfonic acid, phenol sulfonic acid, Hydroquinone sulfonic acid, salts thereof and the like. The antioxidant may be used alone or in combination of two or more. The concentration of the antioxidant in the electroless plating solution is not particularly limited, but is preferably about 0.01 g / L to 100 g / L.

In addition, the present invention provides an electroless plating method using the electroless tin plating solution according to the present invention.

The electroless tin plating method may include treating an electroless tin plating solution containing a water soluble tin salt and the ionic liquid electrolyte composition according to the present invention to copper or a copper alloy.

In the electroless plating method, the temperature of the electrolyte is preferably in the range of 30 to 90 ° C.

Hereinafter, embodiments of the present invention will be described in detail.

The present invention may be better understood by the following examples, which are for the purpose of illustrating the invention and are not intended to limit the scope of protection defined by the appended claims.

As an example, 1 mol of choline chloride and 1 mol of urea were added to a beaker in a magnetic bar, the temperature was raised to 120 ° C and the mixture was stirred at 200 RPM to completely dissolve the powder to prepare an ionic liquid, a DES solution, Tin Methanesulfonate) was added in an amount of 10 g / L, and a tin amount was prepared by dissolving 100 g / L of thiourea, which is a complexing agent, and 200 g / L of citric acid.

The prepared electroless tin plating solution was subjected to tin plating on the copper surface by plating by temperature or plating time.

The results are shown in Fig. 1 and Fig. 2 by plating time by temperature.

Claims (4)

An ionic liquid electrolyte composition for electroless tin plating comprising an ionic liquid mixed with choline chloride and urea and an electroless tin amount prepared therefrom.
The electroless tin plating liquid according to claim 1, which comprises an additive composed of ethylene glycol and citric acid.
The electroless tin plating solution according to any one of claims 1 to 2, wherein the temperature of the electrolyte is 30 to 90 占 폚.
The electroless tin plating liquid according to claim 1, wherein the electrolyte contains a tin salt, a complexing agent, a stabilizer, and a surfactant.

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