JP2021095396A - DITHIAPOLYETHER DIOL, METHOD FOR PRODUCING THE SAME, SnAg PLATING SOLUTION CONTAINING THAT DITHIAPOLYETHER DIOL, AND METHOD FOR FORMING PLATING FILM USING THAT SnAg PLATING SOLUTION - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-purity dithiapolyetherdiol having a low halogen content and a method for producing the same. When used in a SnAg plating solution, dithiapolyetherdiol improves the stability of the plating solution, the appearance of the plating film, and the uniformity of the film thickness. A dithiapolyetherdiol having a halogen content of less than 10 ppm, a purity of 80% or more, and represented by the following general formula (1) or (2). However, in the general formula (1) or (2), x and y are arbitrary natural numbers. [Selection diagram] None

Description

The present invention relates to dithiapolyetherdiol, which is a kind of sulfide compound preferably used for SnAg plating solution, and a method for producing the same. More specifically, the present invention relates to a SnAg alloy plating solution for forming a SnAg plating film by an electroplating method. More specifically, the present invention relates to a method for forming a plating film for a semiconductor wafer or a printed circuit board using a SnAg plating solution.

The present inventor has proposed a sulfide compound represented by the following general formula (21) as a sulfide compound used in a tin alloy plating solution (see Patent Document 1 (Claim 1, paragraph [0033])). In formula (21), n is 1-3.

This sulfide compound is obtained by dehydrating and condensing thiodiethanol (n = 0) in a strong acid having a dehydrating action such as concentrated sulfuric acid and alkyl sulfonic acid. By changing the reaction temperature, reaction time, and purification conditions at this time, the value of n in the general formula (21) can be controlled.

On the other hand, conventionally, as a sulfide compound used for developing a silver halide photographic photosensitive material, 3,9-dithia-6-oxa-1,11-undecanediol (HOCH ₂ CH ₂ SCH ₂ CH ₂ OCH ₂ CH ₂₎ SCH ₂ CH ₂ OH) is disclosed (see, for example, Patent Document 2 (column 14, lines 18-28)). This compound is synthesized by the following method. Dissolve 15.6 g of 2-mercaptoethanol, 14.3 g of bis- (2-chloroethyl) ether and 10.6 g of sodium carbonate in 50% ethanol. Then, the solution is refluxed for 20 hours, and the solvent is distilled off under reduced pressure. Then, the above compound is extracted with hot absolute ethanol and ethyl acetate. As described above, the above compound is synthesized. The target product (the above compound) is obtained by distillation.

Japanese Patent No. 6432667 Tokusei No. 4-28096

However, since the sulfide compound shown in Patent Document 1 is synthesized by dehydrating and condensing thiodiethanol (n = 0) in a strong acid, "HOCH ₂ CH ₂ SCH ₂ CH ₂ OH" and "HOCH ₂ CH _2" Not only a dimer in which two molecules of "SCH ₂ CH ₂ OH" are dehydrated and condensed, but also a trimer in which the single above-mentioned molecule is further condensed on this dimer, or a multimer such as a tetramer is produced. It ends up. Therefore, it is difficult to produce a highly pure sulfide compound suitable for a tin alloy plating solution. Due to this, when this sulfide compound is used in the SnAg plating solution, the Ag composition precipitated at the time of plating may not be stable, and the appearance and uniformity of the film thickness of the plating film may be impaired.

In this regard, the reaction of 2-mercaptoethanol as described in Patent Document 2 with bis- (2-chloroethyl) ether does not produce the above-mentioned multimer. However, in the reaction between 2-mercaptoethanol and bis- (2-chloroethyl) ether as described in Patent Document 2, in addition to the sulfide compound as the main reaction product, sodium chloride (NaCl) as a by-product Is generated. Furthermore, unreacted raw materials and organic impurities due to side reactions also remain.
Due to these residues, the sulfide compound shown in Patent Document 2 has a high chlorine content and low purity. As described above, when a sulfide compound having a high halogen content such as chlorine is used in the SnAg plating solution, silver halide such as silver chloride is generated, and the stability of the SnAg plating solution deteriorates due to this. There was an easy task. Further, when a sulfide compound having low purity is used in the SnAg plating solution, there is a problem that the plating performance, particularly the appearance of the plating film, tends to deteriorate, and the uniformity of the film thickness of the plating film tends to deteriorate.

An object of the present invention is to provide a high-purity dithiapolyetherdiol having a low halogen content and a method for producing the same. Another object of the present invention is to provide a dithiapolyetherdiol and a method for producing the same, which, when used in a SnAg plating solution, improve the stability of the plating solution, the appearance of the plating film, and the uniformity of the film thickness. .. That is, another object of the present invention is to provide a SnAg plating solution containing dithiapolyetherdiol having good stability of the plating solution, and a method for forming a plating film having good appearance and film thickness uniformity. It is in.

The first aspect of the present invention is a dithiapolyether having a halogen content of 10 ppm or less, a purity of 80% or more, and represented by the following general formula (1) or (2). It is a diol. However, in the general formula (1) or (2), x and y are arbitrary natural numbers.

Purity is measured by the following method. In a high performance liquid chromatography column (Prominence UFLC manufactured by Shimadzu Corporation) filled with octadecyl silica (ODS) as a stationary phase, the methanol concentration is gradually changed from 10% to 100% using pure water as a mobile phase. Perform a gradient analysis. The area ratio of the peak area of the dithiapolyetherdiol is calculated, assuming that the peak area of all the detected components is 100%. The calculated area ratio is taken as the purity of the dithiapolyether diol. When two or more kinds of dithiapolyetherdiols are contained, the area ratio of the peak area of the component having the largest peak area is defined as the purity.
In addition, in this specification, a general formula and a formula are structural formulas.

The second aspect of the present invention is the invention according to the first aspect, and the Hazen unit color number (APHA) measured according to JIS K0071-1 (1998) is 100 or less. It is an ether diol.

A third aspect of the present invention is a SnAg plating solution containing the dithiapolyetherdiol of the first or second aspect.

A fourth aspect of the present invention is a method for forming a plating film, which comprises a step of forming a plating film using the SnAg plating solution of the third aspect.

The fifth aspect of the present invention is (a-1) to mix and heat an alcohol compound (raw material A) having a mercapto group at one end, an ether compound (raw material B) having a halogen group at both ends, and an alkaline aqueous solution. A step of obtaining a reaction product solution containing an alkali metal salt, or (a-2) an ether compound having a mercapto group at both ends (raw material A) and an alcohol compound having a halogen group at one end (raw material B). A step of obtaining a reaction product solution containing an alkali metal salt by mixing and heating with an alkaline aqueous solution, and (b) an organic phase contained in the reaction product solution of the step (a-1) or the step (a-2). The step of separating the aqueous phase from the aqueous phase, (c) the step of bringing the organic phase into contact with an ion exchange resin to remove the halide ion and the metal ion, and (d) the step of removing the halide ion and the metal ion. A method for producing a dithia polyether diol, which comprises a step of evaporating and removing impurities in the organic phase by heating the phase.

The sixth aspect of the present invention is the invention according to the fifth aspect, in which the alkali metal salt does not dissolve (b-1) the organic phase between the step (b) and the step (c). A method for producing a dithiapolyetherdiol, further comprising a step of diluting with an organic solvent to separate the alkali metal salt from the organic phase.

The seventh aspect of the present invention is the invention according to the fifth or sixth aspect, which is between the step (b) and the step (c), or the step (b-1) and the step ( A method for producing a dithiapolyetherdiol, further comprising (b-2) a step of bringing the organic phase into contact with activated carbon during c).

The eighth aspect of the present invention is the invention according to any one of the fifth to seventh aspects, in which the impurities in the organic phase in the step (d) are evaporated under reduced pressure. This is a method for producing a diol.

When used in a SnAg plating solution, the dithiapolyetherdiol of the first aspect of the present invention contains an oxygen atom "-O-" in the molecule in the above-mentioned general formula (1) or (2). Therefore, it has the effect of improving water solubility by hydrogen bonding with water. Further, since it contains a hydroxyl group "-OH", it acts as a hydrophilic group and has an effect of further improving water solubility by hydrogen bonding with water. Further, since the ether bond "C-OC" is present between the S atoms, the stability of the dithiapolyetherdiol itself is excellent and at least two S atoms are contained, so that these S atoms are in the plating bath. Sufficiently complex silver ions, which are noble than tin. Moreover, since the halogen content is as low as 10 ppm or less, silver halide is hardly generated in the plating solution. As a result, this SnAg plating solution is excellent in electrolytic stability and aging stability for a long period of time during use and storage. Further, since the purity is 80% or more, there are few by-products, and the dithiapolyetherdiol is appropriately adsorbed on the surface of the plating electrode. This improves the appearance of the plating film and the uniformity of the film thickness.

Since the dithiapolyetherdiol of the second aspect of the present invention has a Hazen unit color number (APHA) of 100 or less, the plating solution becomes transparent when used in the SnAg plating solution.

Since the SnAg plating solution according to the third aspect of the present invention contains dithiapolyetherdiol, it is excellent in electrolytic stability and stability over time as described above. It also improves the appearance of the plating film and the uniformity of the film thickness.

According to the method for forming the fourth aspect of the present invention, since the SnAg plating solution of the third aspect is used, a plating film having a good appearance and a uniform film thickness can be produced.

According to the production method of the fifth aspect of the present invention, the raw material (A), the raw material (B), and the alkaline aqueous solution are mixed to obtain a reaction aqueous solution containing an alkali metal salt. The reaction aqueous solution is separated into an organic phase and an aqueous phase, and halogens and metal ions are removed from the separated organic phase. Then, the organic phase is heated to remove impurities to obtain the desired product. Therefore, a high-purity dithiapolyetherdiol having a low halogen content can be produced.

According to the production method of the sixth aspect of the present invention, before treating the separated organic phase with an ion exchange resin, the organic phase is diluted with an organic solvent in which an alkali metal salt is not dissolved. Therefore, the contents of the halide ion and the metal ion can be significantly reduced, and the purification efficiency of the ion exchange resin can be improved.

According to the production method of the seventh aspect of the present invention, after the reaction product containing the alkali metal salt is separated into an organic phase and an aqueous phase, and before removing the halide ion from the separated organic phase. The organic phase is brought into contact with activated carbon. As a result, the colored impurity component of the organic phase is adsorbed and removed by the activated carbon, and the dithiapolyetherdiol can be made transparent.

According to the production method of the eighth aspect of the present invention, by removing impurities in the organic phase under reduced pressure, impurities are easily evaporated from the organic phase, and a higher purity dithiapolyetherdiol can be obtained. Be done.

Hereinafter, a method for producing the dithiapolyetherdiol according to the first and second embodiments of the present invention will be described.

<First Embodiment>
[Manufacturing method of dithiapolyetherdiol]
(A-1) Mixing and Heating Step of Raw Material (A), Raw Material (B) and Alkaline Aqueous Solution The production method of the first embodiment includes the step (a-1). In the step (a-1), an alcohol compound having a mercapto group at one end (raw material A), an ether compound having a halogen group at both ends (raw material B), and an alkaline aqueous solution are mixed and heated to make an alkali. A reaction product containing a metal salt is obtained. That is, the raw material (A) is an alcohol compound having a mercapto group at one end (hereinafter, also referred to as a raw material (A1)). For example, 2-mercaptoethanol represented by the following formula (3) can be mentioned.

The raw material (B) is an ether compound having halogen groups at both ends (hereinafter, also referred to as a raw material (B1)). For example, the compounds represented by the following formulas (4) to (8) can be mentioned. Table 1 below shows the ether compounds represented by the formulas (4) to (8) of the raw material (B) together with the raw material (A) of the formula (3).

Examples of the alkaline aqueous solution of the production method of the first embodiment include aqueous solutions of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium hydrogencarbonate and the like. Regarding the mixing of the raw material (A), the raw material (B), and the alkaline aqueous solution, for example, it is preferable to first uniformly mix the raw material (A) with the alkaline aqueous solution. As a result, the deprotonation of the raw material (A) can be reliably performed. For the reason of suppressing heat generation during mixing, it is preferable to cool the alkaline aqueous solution to a temperature of 0 ° C. to 10 ° C. before mixing. Next, it is preferable to uniformly mix the raw material (B) with this mixed solution and heat it. This heating is preferably performed by heating the mixed solution to a temperature of 40 ° C. to 100 ° C. in an air atmosphere and holding it for 3 hours to 24 hours. As a result, a dehalogenation reaction occurs, and the main reaction product, dithiapolyetherdiol, the by-product, alkali metal halide, the unreacted raw material, and the organic impurities produced by the side reaction are formed. The contained reaction product is obtained.

(B) Step of separating the reaction product solution into an organic phase and an aqueous phase Since the obtained reaction product solution contains an organic phase and an aqueous phase, it is separated into an organic phase and an aqueous phase. If the amount of the reaction product is small, it is separated into an organic phase and an aqueous phase by a separating funnel, and if the amount of the reaction product is large, it is separated into an organic phase and an aqueous phase by centrifugation or the like. The reaction product may be concentrated in order to facilitate separation into the organic phase and the aqueous phase.

(b-1) Step of diluting the organic phase with an organic solvent in which the alkali metal salt does not dissolve. The separated organic phase is collected, an organic solvent in which the alkali metal salt does not dissolve is added to this organic phase, and the organic phase is divided into 2 by volume. It is preferable to dilute it 10 to 10 times. That is, it is preferable to add the organic solvent so that the volume after dilution is 2 to 10 times the volume before dilution. As the organic solvent, isopropanol, toluene and the like can be used. As a result, the alkali metal salt is easily precipitated or precipitated. Therefore, when the alkali metal salt is solid-liquid separated, an organic phase having a low alkali metal salt content can be obtained.

(B-2) Step of bringing the organic phase into contact with activated carbon The organic phase of step (b) above or the organic phase that has undergone step (b-1) is brought into contact with activated carbon to make the colored and offensive odorous organic phase transparent. It is preferable to deodorize at the same time. If the organic phase is small, granular activated carbon is mixed with the organic phase to bring the organic phase into contact with the activated carbon. If the amount of the organic phase is large, the organic phase is passed through a column filled with activated carbon to bring the organic phase into contact with the activated carbon. As the activated carbon, for example, activated carbon such as "Taiko K type" manufactured by Futamura Chemical Co., Ltd., "Kuraraycol" manufactured by Kuraray Co., Ltd., and "Refined Shirasagi" manufactured by Osaka Gas Chemical Co., Ltd. can be used. The step (b-2) may be performed a plurality of times as needed.
When the activated carbon is mixed with the organic phase, the amount (g) of the activated carbon with respect to the amount (L) of the organic phase is preferably 1 g / L to 200 g / L. When the organic phase is passed through the column filled with activated carbon, it is preferable to pass the organic phase through the column at a flow velocity having a linear velocity LV (Linear Velocity) of 0.1 to 5.

(C) Step of bringing the organic phase into contact with the ion exchange resin The organic phase of the above step (b), the organic phase of the step (b-1) or the organic phase of the step (b-2) is brought into contact with the ion exchange resin. The remaining halide ion and metal ion are removed. If the amount of the organic phase is small, the granular ion exchange resin is mixed with the organic phase and the organic phase is brought into contact with the ion exchange resin. If the amount of the organic phase is large, the organic phase is passed through a column packed with an ion exchange resin. Examples of the ion exchange resin include "A series" and "C series" manufactured by Purolite, "Duolite" manufactured by Sumika Chemtex, "SK series", "SA series" and "SM series" manufactured by Mitsubishi Chemical Corporation. Ion exchange resins such as "SMUPB" can be used. The step (c) may be performed a plurality of times as needed.
When the ion exchange resin is mixed with the organic phase, the amount (g) of the ion exchange resin with respect to the amount (L) of the organic phase is preferably 1 g / L to 200 g / L. When the organic phase is passed through the column packed with the ion exchange resin, it is preferable to pass the organic phase through the column at a flow velocity having a linear velocity LV (Linear Velocity) of 0.1 to 5.

(D) Step of removing impurities in the organic phase By heating the organic phase that has undergone the above step (c), the impurities in the organic phase are evaporated and the impurities are removed. As a result, the organic phase in which the offensive odor remains is deodorized, and the purity of the obtained dithiapolyetherdiol is increased. The evaporation of the impurities is preferably carried out under a reduced pressure of 0.001 MPa to 0.01 MPa and a temperature of 40 ° C. to 100 ° C. for 1 hour to 24 hours. This facilitates the evaporation of impurities from the organic phase.

In the above embodiment, in the step (b-1), the organic phase is diluted with an organic solvent in which the alkali metal salt is not dissolved, and the alkali metal salt is precipitated and / or precipitated to remove the alkali metal salt from the organic phase. It is being removed. However, it is also possible to remove the alkali metal salt from the organic phase by cleaning the organic phase with pure water.

[Dithiapolyetherdiol]
The dithiapolyetherdiol produced by the method of the first embodiment has a halogen content of 10 ppm or less and a purity of 80% or more, and is represented by the above-mentioned general formula (1). The preferred halogen content is 5 ppm or less and the preferred purity is 90% or more.

Examples of the dithiapolyetherdiol of the first embodiment include the following formulas (9) to (13). The number of x in the general formula (1) is also shown. It is preferable that x is in the range of 1 to 5 because the raw material is easily available.

<Second embodiment>
[Manufacturing method of dithiapolyetherdiol]
Next, a second embodiment of the present invention will be described. The manufacturing method of the second embodiment includes the step (a-2). In step (a-2), an ether compound having a mercapto group at both ends (raw material A), an alcohol compound having a halogen group at one end (raw material B), and an alkaline aqueous solution are mixed and heated to make an alkali. A reaction product containing a metal salt is obtained. In the production method of the second embodiment, the raw material (A) and the raw material (B) are different from those of the first embodiment. Other than that, the production method of the second embodiment is different from that of the first embodiment. The same is true.

In the production method of the second embodiment, the raw material (A) is an ether compound having a mercapto group at both ends (hereinafter, also referred to as a raw material (A2)). For example, bis (2-mercaptoethyl) ether represented by the following formula (14) can be mentioned.

The raw material (B) is an alcohol compound having a halogen group at one end (hereinafter, also referred to as a raw material (B2)). For example, compounds represented by the following formulas (15) to (17) can be mentioned. Table 2 below shows the alcohol compounds represented by the formulas (15) to (17) of the raw material (B) together with the raw material (A) of the formula (14).

[Dithiapolyetherdiol]
The dithiapolyetherdiol produced by the method of the second embodiment has the same characteristic values as the dithiapolyetherdiol produced by the method of the first embodiment. That is, this dithiapolyetherdiol has a halogen content of 10 ppm or less and a purity of 80% or more, and is represented by the above-mentioned general formula (2). The preferred halogen content is 5 ppm or less and the preferred purity is 90% or more. Examples of the dithiapolyetherdiol of the second embodiment include the following formulas (18) to (20). The number of y in the general formula (2) is also described. It is preferable that y is in the range of 1 to 3 because the raw material is easily available.

[SnAg plating solution and a method for forming a plating film using this plating solution]
The SnAg plating solution of the present embodiment contains the dithiapolyetherdiol produced in the first and second embodiments, and is also a soluble Sn salt that dissolves in water to generate divalent tin ions. , Soluble Ag salt and additives. The dithiapolyetherdiol acts as a complexing agent for Ag ions. Examples of the additive include an acid electrolyte (free acid), a surfactant, an antioxidant, a complexing agent for Sn, a pH adjusting agent, a brightening agent and the like. This SnAg plating solution can be prepared, for example, by mixing a soluble tin salt, the above-mentioned dithiapolyetherdiol and additives, and water.

As a method of forming a plating film using the SnAg plating solution of the present embodiment, an electroplating method is used. Examples of the plating film include plating films for semiconductor wafers and printed circuit boards. The liquid temperature of this SnAg plating liquid at the time of plating is generally 70 ° C. or lower, preferably 10 ° C. to 40 ° C. The current density at the time of forming a plating film by electroplating is in ^{the range of 0.1 A / dm 2} or more and 100 A / dm ² or less, preferably 0.5 A / dm ² or more and 20 A / dm ² or less.

The SnAg plating solution containing dithiapolyetherdiol produced in the first and second embodiments can be applied to an electronic component to be plated to form a plating film on the electronic component. Examples of electronic components include printed boards, flexible printed boards, film carriers, semiconductor integrated circuits, resistors, capacitors, filters, inductors, thermistors, crystal oscillators, switches, lead wires, and the like.

Next, examples of the present invention will be described in detail together with comparative examples.

<Example 1>
40 g (1 mol) of sodium hydroxide was dissolved in 200 mL of pure water and the solution was cooled to 5 ° C. 78.1 g (1 mol) of 2-mercaptoethanol represented by the formula (3) was mixed with this aqueous sodium hydroxide solution as a raw material (A), and the mixture was stirred with a stirrer to prepare a first mixed solution. Subsequently, 71.5 g (0.5 mol) of bis (2-chloroethyl) ether represented by the formula (4) as a raw material (B) is mixed with this first mixed solution, and the mixture is stirred with a stirrer to give the first mixture. Two mixed solutions were prepared. The second mixed solution was heated to 80 ° C. in an air atmosphere and refluxed at 80 ° C. for 12 hours. As a result, the raw material (A) and the raw material (B) reacted to obtain a reaction product.

The reaction product was transferred to a separating funnel and allowed to stand, and separated into two phases, an organic phase and an aqueous phase. 2-Isopropanol was mixed with the separated organic phase, and the organic phase was diluted 5-fold by volume. That is, 2-isopropanol was added so that the volume after dilution was 5 times the volume before dilution. The solids were removed from the organic phase by filtering the solids precipitated or precipitated by dilution. Next, granular activated carbon (“purified egret” manufactured by Osaka Gas Chemical Co., Ltd.) was mixed with the organic phase at a ratio of 10 g / L, and the mixture was stirred for 1 hour. After stirring, the mixed liquid was filtered to remove activated carbon.

Granular ion exchange resin (“SMUPB” manufactured by Mitsubishi Chemical Corporation) was mixed with the organic phase from which activated carbon had been removed at a ratio of 200 g / L, and the mixture was stirred for 1 hour. After stirring, the mixed liquid was filtered to remove the ion exchange resin. Subsequently, the organic phase from which the ion exchange resin had been removed was transferred to an eggplant-shaped flask, the pressure was reduced to 0.005 MPa, and the mixture was heated at 80 ° C. for 12 hours to evaporate impurities in the organic phase to obtain a liquid final product. ..

Table 3 below shows the production conditions (No. 1) of the dithiapolyetherdiol in Example 1 and Examples 2 to 8 and Comparative Examples 1 and 2 described below. That is, each type of the raw material (A) and the raw material (B) used in Example 1 and the following Examples 2 to 8 and Comparative Examples 1 and 2 is shown. In Table 3, the formula numbers correspond to the formula numbers shown in the embodiments.

Further, Table 4 below shows the production conditions (No. 2) of the dithiapolyetherdiol in Example 1 and Examples 2 to 8 and Comparative Examples 1 and 2 described below. That is, the presence or absence of the manufacturing process in Example 1 and the following Examples 2 to 8 and Comparative Examples 1 and 2 is shown. In Table 4, the process code corresponds to the process code shown in the embodiment.

<Examples 2 to 8 and Comparative Examples 1 to 2>
In Examples 2 to 8 and Comparative Examples 1 and 2, as shown in Table 3, the type of the raw material (A) and the type of the raw material (B) were the same as or changed from those of Example 1, respectively. Further, as shown in Table 4, step (a-1), step (b), step (b-1), step (b-2), step (c), and step (d) were performed or not performed. ..
In Example 6, impurities in step (d) were removed under "normal pressure". In Example 7, contact with the activated carbon in step (b-2) was not performed. In Example 8, instead of diluting with the organic solvent in step (b-1), it was diluted 5 times by volume with pure water, and contact with the ion exchange resin in step (c) was performed. It was repeated 10 times. In Comparative Example 1, contact with the ion exchange resin in step (c) and removal of impurities in step (d) were not performed. In Comparative Example 2, the impurities in step (d) were not removed. Other than that, in Examples 2 to 8 and Comparative Examples 1 and 2, the final product was produced in the same manner as in Example 1.

<Example 9>
40 g (1 mol) of sodium hydroxide was dissolved in 200 mL of pure water and the solution was cooled to 5 ° C. 69.1 g (0.5 mol) of bis (2-mercaptoethyl) ether represented by the formula (14) as a raw material (A) is mixed with this aqueous sodium hydroxide solution, and the mixture is stirred with a stirrer for the third mixing. The liquid was prepared. Subsequently, 124.9 g (1 mol) of 2-bromoethanol represented by the formula (15) is mixed with this third mixed solution as a raw material (B) and stirred with a stirrer to prepare a fourth mixed solution. did. From this point onward, the final product was obtained in the same manner as in Example 1.

Further, Table 5 below shows the production conditions (No. 1) of the dithiapolyetherdiol in Example 9 and Examples 10 to 11 described below. That is, each type of the raw material (A) and the raw material (B) used in Example 9 and Examples 10 to 11 described below is shown. In Table 5, the formula numbers correspond to the formula numbers shown in the embodiments.

Further, Table 6 below shows the production conditions (No. 2) of the dithiapolyetherdiol in Example 9 and Examples 10 to 11 described below. That is, the presence or absence of the manufacturing process in Example 9 and Examples 10 to 11 described below is shown. In Table 6, the process code corresponds to the process code shown in the embodiment.

<Examples 10 to 11>
In Examples 10 to 11, as shown in Table 5, the type of the raw material (A) and the type of the raw material (B) were the same as or changed from those of Example 9, respectively. Further, as shown in Table 6, steps (a-2), step (b), step (b-1), step (b-2), step (c), and step (d) were performed. In Examples 10-11, the final product was produced in the same manner as in Example 9.

<Comparative tests and evaluations>
Using dithiapolyetherdiol, which is the final product of 13 kinds obtained in Examples 1 to 11 and Comparative Examples 1 and 2, as samples, the halogen content, purity and color taste (Hazen unit color number) of these samples were taken. ) Was measured and evaluated by the following method. Further, a SnAg plating solution was prepared using these dithiapolyetherdiols, and a plating test was performed to evaluate the stability of the plating solution, the appearance of the plating film, and the uniformity of the film thickness. These results are shown in Table 7.

(A) Halogen content The halogen content was calculated by quantifying the ion concentration of halogen (F, Cl, Br, I) in the sample by ion chromatography (Prominence HIC-SP, manufactured by Shimadzu Corporation).

(B) Purity A sample (dithiapolyetherdiol) was introduced into a high performance liquid chromatography column (Prominence UFLC, manufactured by Shimadzu Corporation) packed with octadecyl silica (OSD) as a stationary phase. Using pure water as the mobile phase, gradient analysis was performed in which the concentration of methanol was changed stepwise from 10% to 100%. The peak area of all the detected components was taken as 100%, and the peak area of the sample was calculated by the area ratio ((peak area of sample / peak area of all components) × 100 (%)). The calculated area ratio was used as the purity of the sample.

(C) Color (number of colors per Hazen)
A sample (dithiapolyetherdiol) was separated into a glass cell, and the color was measured using a color / turbidity simultaneous measuring device (model number: TZ6000) manufactured by Nippon Denshoku Kogyo Co., Ltd. while keeping the temperature at 40 ° C. , The number of Hazen unit colors (APHA) as a tint was obtained from the value.

(D) Plating test In an aqueous solution of tin methanesulfonate, methanesulfonic acid as a free acid, a sample (dithiapolyetherdiol), and a nonionic surfactant (polyoxyethylene and polyoxypropylene in ethylenediamine 50:50) ) And benzylidene acetone as a brightener were mixed and dissolved. Then, an aqueous silver methanesulfonate solution was further added to the mixed solution and mixed. Finally, ion-exchanged water was added to bathe the SnAg plating solution having the following composition. The molar ratio of the dithiapolyetherdiol to the amount of Ag in the SnAg plating solution having the following composition was 1: 1. The tin methanesulfonic acid aqueous solution was prepared by electrolyzing a metal tin plate in the methanesulfonic acid aqueous solution. The silver methanesulfonic acid aqueous solution was prepared by electrolyzing each metal silver plate in the methanesulfonic acid aqueous solution.

(Composition of SnAg plating solution)
Tin methanesulfonate (as Sn2 +): 50 g / L
Silver methanesulfonate (as Ag +): 0.005 mol / L
Methanesulfonic acid (as free acid): 200 g / L
Dithia polyether diol: 0.005 mol / L
Nonionic surfactant: 10g / L
Brightener: 10 mg / L
Ion-exchanged water: balance

(D-1) Stability of Plating Solution 13 types of SnAg alloy plating solutions that had been bathed were separately placed in a sealed glass bottle and stored at 25 ° C. for 1 month. After one month had passed, the appearance of the liquid was visually observed, and the one that maintained transparency was regarded as "good", and the one in which turbidity or precipitate was observed was regarded as "poor".

(D-2) Appearance of plating film 13 types of SnAg alloy plating solutions that have been bathed are placed separately in a plating tank, a wafer with a pattern formed as a cathode is placed in the solution, and a Pt / Ti mesh plate is used as an anode. It was placed and a plating test was performed. As the plating conditions, the liquid temperature was 25 ° C., the energizing current was 4 A / dm ² , and the plating treatment time was 25 minutes. During the plating process, the plating solution was stirred with a cathode rocker. The appearance of the plating film formed in the pattern was observed with a laser microscope. A film having a surface roughness Ra of less than 2 μm is regarded as “good”, a film having a surface roughness Ra of 2 μm or more and less than 5 μm is regarded as “possible”, and a film having a surface roughness Ra of 5 μm or more is regarded as “poor”. did. The appearance of the plating film was evaluated based on these three criteria.

(D-3) Uniformity of plating film thickness Plating test The uniformity of the film thickness of the plating film formed in the above pattern was investigated. Obtain the maximum value (Tmax), minimum value (Tmin), and average value (Tave) of the film thickness of the plating film in 10 dies, calculate the film thickness uniformity by the following formula, and perform uniform plating. I evaluated it.
Uniformity of plating film thickness = {(Tmax-Tmin) / (2 x Tave)} x 100 (%)
When the uniformity of the film thickness of the plating film was less than 5%, it was regarded as "good", when it was 5% or more and less than 10%, it was regarded as "OK", and when it was 10% or more, it was regarded as "bad". The uniformity of the film thickness of the plating film was evaluated based on these three criteria.

As is clear from Tables 4, 6 and 7, in Comparative Example 1, contact with the ion exchange resin in step (c) and removal of impurities in step (d) were not performed. In Comparative Example 1, the halogen content was as high as "700 ppm", the purity was as low as "46%", and the number of Hazen unit colors of color was as high as "120". The stability of the plating solution, the appearance of the plating film, and the uniformity of the film thickness were all "poor".

Further, in Comparative Example 2, the impurities in the step (d) were not removed. In Comparative Example 2, the purity was as low as "50%". The stability of the plating solution, the appearance of the plating film, and the uniformity of the film thickness were all "poor".

On the other hand, in Examples 1 to 5 and Examples 9 to 11, the step (a-1) or the step (a-2), the step (b), the step (c) and the step (c) of the fifth aspect of the present invention Step (d) was performed. In Examples 1-5 and 9-11, the obtained final products have a halogen content and purity within the range shown in the first aspect of the present invention, and SnAg containing these final products. The stability of the plating solution, the appearance of the plating film, and the uniformity of the film thickness, which were the results of the plating test using the plating solution, were all "good".
In Example 6, impurities in step (d) were removed under normal pressure. In Example 6, the purity was slightly low at "80%", the color was high at "80", and the appearance of the plating film and the uniformity of the film thickness were "possible", respectively.
In Example 7, contact with the activated carbon in step (b-2) was not performed. In this Example 7, the halogen content was slightly high at "10 ppm" and the number of Hazen unit colors of the tint was very high at "240", but the stability of the plating solution, the appearance of the plating film and the film thickness were high. The uniformity was all "good".
In Example 8, in step (b-1), the mixture was diluted with pure water without being diluted with an organic solvent. In Example 8, although the color was slightly high at "60", the stability of the plating solution, the appearance of the plating film, and the uniformity of the film thickness were all "good".

The dithiapolyetherdiol of the present invention can be used as a SnAg plating solution for forming a part of an electronic component such as a solder plating film for a semiconductor wafer or a printed circuit board.

Claims (8)

A dithiapolyetherdiol having a halogen content of 10 ppm or less, a purity of 80% or more, and represented by the following general formula (1) or (2). However, in the general formula (1) or (2), x and y are arbitrary natural numbers.

The dithiapolyetherdiol according to claim 1, wherein the Hazen unit color number (APHA) measured according to JIS K0071-1 (1998) is 100 or less. A SnAg plating solution containing the dithiapolyether diol according to claim 1 or 2. A method for forming a plating film, which comprises a step of forming a plating film using the SnAg plating solution according to claim 3. (a-1) A reaction containing an alkali metal salt by mixing and heating an alcohol compound (raw material A) having a mercapto group at one end, an ether compound (raw material B) having a halogen group at both ends, and an alkaline aqueous solution. The process of obtaining the product solution, or
(a-2) Reaction containing an alkali metal salt by mixing and heating an ether compound (raw material A) having a mercapto group at both ends, an alcohol compound (raw material B) having a halogen group at one end, and an alkaline aqueous solution. The process of obtaining the product liquid and
(b) A step of separating the organic phase and the aqueous phase contained in the reaction product solution of the step (a-1) or the step (a-2), and
(c) A step of bringing the organic phase into contact with an ion exchange resin to remove halide ions and metal ions.
(d) A method for producing a dithiapolyetherdiol, which comprises a step of evaporating and removing impurities in the organic phase by heating the organic phase from which the halide ion and the metal ion have been removed. Between the step (b) and the step (c),
(b-1) The method for producing a dithiapolyetherdiol according to claim 5, further comprising a step of diluting the organic phase with an organic solvent in which the alkali metal salt does not dissolve and separating the alkali metal salt from the organic phase. .. Between the step (b) and the step (c), or between the step (b-1) and the step (c),
(b-2) The method for producing a dithiapolyetherdiol according to claim 5 or 6, further comprising a step of bringing the organic phase into contact with activated carbon. The method for producing a dithiapolyetherdiol according to any one of claims 5 to 7, wherein the impurities in the organic phase are evaporated under reduced pressure in the step (d).