JPH0931699A - Electro tin plating method using insoluble anode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a tin dissolving rate, to control the Sn<2+> ion concn. in a tin plating soln. and to reduce the generation of tin sludge at the time of electrotinning a steel and other metals with the acidic tin plating soln. by the use of an insoluble anode. SOLUTION: Metallic tin is held in a tin dissolving tank, and the plating soln. in the tank is controlled to 30 to 45 deg.C. Metallic tin is dissolved in the tank, and electro tin plating is conducted by the use of the obtained plating soln. Otherwise, metallic tin is dissolved in the plating soln. with the dissolved oxygen concn. C in ppm specified, and electro tin plating is performed with the use of the obtained plating soln.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrotin plating method using an insoluble anode for the production of tin-plated steel sheets and the like. The present invention relates to a method of rapidly supplying Sn ²⁺ ions to a plating solution during plating to control the Sn ²⁺ ion concentration in the tin plating solution within an appropriate range.

[0002]

2. Description of the Related Art Conventionally, a soluble anode, that is, a tin cast product, has been used in electroplating tin, but in the actual operation, replacement of the anode requires a lot of labor, which is one of the causes of productivity drop. It was. Therefore, it is widely recognized that the insolubilization of the anode is effective as a means for improving the productivity of the electric tin plating line, and Examples are also reported.

In making a tin (tin plating) line into an insoluble anode, how to supply Sn ²⁺ ions is important. Regarding this point, some techniques have already been developed, but as a method applied to an actual tin plating line, for example, there are JP-B-53-17979 and JP-B-56-54079. In these methods, an oxygen-containing gas is blown into the plating solution to increase the concentration of dissolved oxygen in the plating solution, thereby promoting the chemical dissolution of metal tin and enabling Sn ²⁺ ion replenishment. In this method, it is considered that the dissolution of metallic tin proceeds by the electrochemical reaction of the following formulas (2) and (3).

[0004] anode ^{reaction: Sn → Sn 2+ + 2e -} ···· (2) cathode ^{_{reaction: O 2 + 4H + + 4e}} - → 2H 2 O ···· (3) However, conventionally, the dissolved oxygen in the plating solution However, there is a problem that Sn ²⁺ ions are further oxidized and tin sludge is generated. Therefore, a method for reducing tin loss due to sludge formation of Sn ²⁺ ions is disclosed.

For example, in Japanese Patent Publication No. 57-1600,
Connects tin dissolving device and tin plating solution through ion exchange membrane
However, the solution with high dissolved oxygen concentration directly contacts the plating solution and Sn
²⁺A technique for preventing sludge formation of ions is disclosed.
ing. Further, in Japanese Patent Laid-Open No. 3-180493, tin dissolution
By mechanically stirring the metallic tin layer in the device, Sn
²⁺A technique for suppressing sludge formation of ions has been disclosed.
You.

However, according to these methods, in the plating solution
The sludge formation of Sn ²⁺ ions could not be sufficiently suppressed. Sludge causes problems such as an increase in tin consumption rate, equipment malfunction and maintenance due to adhesion to plating equipment, and surface defects of plated products due to floating in the plating solution. There is a demand for development of a method capable of stably supplying Sn ²⁺ ions therein.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to increase the tin dissolution rate when electroplating steel or other metal with an acidic tin plating solution using an insoluble anode to increase the tin dissolution rate in the tin plating solution. The present invention provides a method for controlling the Sn ²⁺ ion concentration in a suitable range and further reducing the generation of tin sludge.

[0008]

A first aspect of the present invention is an electrotin plating method using an insoluble anode, which holds metal tin and adjusts the plating solution temperature in the bath to 30 ° C or higher and lower than 45 ° C. An electrolytic tin plating method using an insoluble anode, characterized in that metallic tin is melted in the tin dissolution bath thus prepared, and electrolytic tin plating is performed using the obtained plating solution.

A second aspect of the present invention is an electrotin plating method using an insoluble anode, in which the dissolved oxygen concentration C (ppm) is adjusted to fall within the range of the following formula (1), and a metal tin is added to the plating solution. And an electrolytic tin plating using the obtained plating solution. An electrolytic tin plating method using an insoluble anode. C _sat −10 ≦ C ≦ C _sat ··· (1) In the formula (1), C _sat is plating under the condition that the temperature of the plating solution and the oxygen partial pressure are 1.01 × 10 ⁵ Pa when the metal tin is dissolved. Indicates the saturated solubility (ppm) of oxygen in liquid.

In the second aspect of the present invention, in the dissolution of metallic tin, it is preferable that the pressure of the vapor phase on the surface of the plating solution in the tin dissolution tank is atmospheric pressure. In the second aspect of the invention, the dissolved oxygen concentration C (ppm) of the plating solution when the metal tin is dissolved,
It is preferable to adjust the dissolved oxygen concentration C (ppm) of the plating solution at the inlet of the metal tin dissolution tank to be within the range of the above formula (1).

Further, the first invention and the second invention are
It is preferably applied to an electrotin plating method using an alkane sulfonic acid and / or an alkanol sulfonic acid as a conduction aid of a plating solution, and more preferably, methane sulfonic acid and / or 2-hydroxy as a conduction aid of a plating solution. It is preferably applied to an electrotin plating method using an insoluble anode using propane-1-sulfonic acid.

[0012]

[Operation] The present invention will be described in more detail below. The present invention is preferably applied to an electrotin plating method having at least an electroplating bath and a tin dissolving bath. That is, in the present invention, the plating solution whose Sn ²⁺ ion concentration has been reduced by electroplating is appropriately circulated between the electroplating bath and the tin dissolution bath, and after the Sn ²⁺ ion concentration has increased,
Return to the electroplating tank.

The method of circulating the plating solution in the method of the present invention is not limited, but, as will be described later, in the flow path of the plating solution between the electroplating bath and the tin dissolving bath, oxygen enrichment in the plating liquid is achieved. It is also preferably applied to a three-tank system electrotin plating method in which an oxygen enrichment tank is installed. In the method of the present invention, the plating solution is circulated between the tin dissolution tank and the oxygen enrichment tank, and the plating solution is circulated between the tin dissolution tank and the electroplating tank with or without an oxygen enrichment tank. It is also preferably applied to a bath-type electrotin plating method.

The circulation system of the plating solution between the electroplating bath, the oxygen enrichment bath and the tin dissolution bath may be continuous or intermittent, and when intermittently performed, there are no particular restrictions on the time interval or the like. Absent. As the insoluble anode in the electroplating bath, for example, a platinum-coated electrode, an iridium oxide-coated electrode, or the like can be preferably used, but it is not particularly limited.

In a preferred embodiment of the tin dissolving tank of the present invention, the oxygen-enriched plating solution is supplied at a high flow rate from the lower portion of the tin dissolving tank provided with a stirring blade or the tank filled with tin particles. An example is a fluidized bed reactor that mixes tin with a plating solution while floating and flowing tin, but is not limited thereto. First, the electrotin plating method of the first invention will be described.

In the electrotin plating method, the method of melting Sn and supplying Sn ²⁺ ions has hitherto been carried out under the flow rate of the oxygen-containing gas to be blown and the pressure in the metal tin dissolution tank, especially under high pressure. Although the research on the dissolved oxygen concentration of the plating solution was carried out, there was no example paying attention to the temperature of the plating solution when tin was dissolved. Regarding the temperature of the plating solution when tin is dissolved in the prior art, it is described as 45 ° C. in JP-B-53-17979 and JP-B-53-18168, and JP-B-56-54079. Although there is no particular description in Japanese Patent Publication No. 56-54080, the temperature of the plating solution is described as 50 ° C. in all cases, and the temperature of the plating solution when tin is dissolved is considered to be 50 ° C.

As a result of intensive studies on the method of supplying Sn ²⁺ ions to the tin plating bath, the present inventors have found that the temperature of the plating solution is extremely important when metallic tin is dissolved, Came to. That is, as a result of investigating the change with temperature of the reaction in which metallic tin dissolves as Sn ²⁺ ions, it was found that there is a maximum value of the tin dissolution rate at the temperature of the plating solution of 45 ° C. as shown in FIG. did. The cause of this is unknown, but it is thought that it occurs as the sum of several different reaction mechanisms.

On the other hand, as shown in FIG. 3, the reaction rate at which metallic tin or Sn ²⁺ ions are further oxidized to form tin sludge monotonically increases with the temperature of the plating solution, but the rate of increase is tin. It is smaller than the temperature dependence of the dissolution rate.
Based on the results obtained above, the relationship between the ratio of the sludge generation rate to the tin dissolution rate (sludge generation rate) and the temperature of the plating solution was obtained. As a result, as shown in FIG. It was found that the temperature had a minimum value within the range of 30 to 45 ° C.

In the actual operation of electroplating tin, the ratio of the sludge generation rate to the tin dissolution rate, that is, the sludge generation rate is important. If the sludge generation rate is high even if the tin dissolution rate is high, the tin dissolution equipment Will be compact, but on the other hand, a large amount of sludge is generated, which is a problem. Therefore, in the present invention, the temperature of the plating solution is 30 ° C. or higher,
Less than 45 ° C, more preferably 30 ° C or more and 42 ° C or less,
It is more preferable to keep the temperature at 30 ° C. or higher and 40 ° C. or lower to reduce the sludge generation rate.

Next, a method for adjusting the temperature of the plating solution will be described. The temperature of the plating solution in the electroplating bath during tin plating is maintained at 45 ° C. or higher, and in some cases about 60 ° C. in order to increase the conductivity and improve the limiting current density. For this reason, when the plating solution in the electroplating tank is directly sent to the tin dissolving tank as in the conventional method, the sludge generation rate increases.

Therefore, in the present invention, a temperature adjusting device is provided in the tin dissolving bath itself or in the plating bath between the electroplating bath and the tin dissolving bath so that the temperature of the plating bath in the tin dissolving bath can be adjusted according to the present invention. Adjust so that it is within the temperature range. The temperature adjusting device detects the temperature in the tin melting tank, and if the temperature can be controlled within the temperature range of the present invention, its installation location is not particularly limited.

If the temperature of the plating solution can be controlled so that the temperature of the plating solution in the tin dissolving bath is within the range of the present invention, the mounting location of the terminal is not particularly limited. It may be attached to the plating solution inlet pipe of the dissolution tank.
In the present invention, in order to improve tin solubility, when an oxygen enrichment tank for enriching oxygen in the plating solution and a tin dissolution tank are installed separately, in view of equipment maintenance and management, It is desirable to control the temperature using a temperature control device installed in the enrichment tank.

As a temperature adjusting method, an ordinary cooling device,
A heating device and a cooling / heating device can be used and are not particularly limited. When the temperature of the plating solution during tin dissolution is out of the above temperature range, the sludge generation rate increases significantly,
This causes malfunction of the equipment due to adhesion of sludge and increase of stains on the plating surface, and a great deal of work is required to remove sludge.

The first aspect of the present invention is not limited to the three-electron plating method including the oxygen enrichment tank, the tin dissolving tank and the electroplating tank, and the electroplating tank and the tin dissolving tank are not limited thereto. It is also preferably applied to the two-tank method of electrotin plating. Next, the electric tin plating method of the second invention will be described. In the metal tin dissolution method, Japanese Patent Application Laid-Open No. 4-131399 is mentioned as a conventional technique focusing on the dissolved oxygen concentration in the plating solution. In this publication, the dissolution reaction is carried out under the condition that the dissolved oxygen concentration is 200 ppm, that is, under pressure (estimated value of oxygen partial pressure: 6.7 atm) in the examples, and it is usual from the viewpoint of simplification of dissolution equipment. A technique capable of achieving sufficient dissolution of tin under pressure is desired.

As a result of earnest studies on the method of supplying Sn ²⁺ ions to the tin plating bath, the inventors of the present invention have found that it is extremely important to control the concentration of dissolved oxygen in the plating solution when dissolving metallic tin under normal pressure. The inventors have found that there is one, and have reached the present invention. The rate of reaction in which metallic tin dissolves as Sn ²⁺ ions is proportional to the dissolved oxygen concentration, as shown in FIG.

On the other hand, as shown in FIG. 7, the reaction rate at which metal tin or Sn ²⁺ ions are further oxidized to form tin sludge rather decreases as the dissolved oxygen concentration increases, and increases in the vicinity of the saturated dissolved oxygen concentration. I understood. Although the cause of this is unknown, it is considered that the reaction mechanism in the insufficient oxygen supply region is different from that in the sufficient oxygen region.

Furthermore, the sludge formation rate and the tin dissolution rate
As shown in Fig. 5, the ratio of
Oxygen concentration: C (ppm), C_sat−10 ≦ C ≦ C
_satIt was found to be the lowest in the range. Where C
_satIs the temperature of the plating solution and the oxygen partial pressure when the metal tin is dissolved.
Is 1.01 x 10 ^FiveSaturation of oxygen to the plating solution under Pa condition
Shows total solubility (ppm), dissolved oxygen concentration, oxygen saturation
Solubility unit ppm is per volume of plating solution (1L)
It is defined as the mass (mg) of oxygen dissolved in.

C _sat in FIGS. 5 and 6 is
Plating solution temperature at melting metal tin is 40 ℃, oxygen partial pressure is 1.01 ×
The saturated solubility of oxygen in the plating solution under the condition of 10 ⁵ Pa is shown. In the actual operation of electro-tinning, the sludge generation rate is important.If the sludge generation rate is high even if the tin dissolution rate is high, the tin dissolution equipment will be compact, but a large amount of sludge will be generated. It becomes a problem.

[0029] Thus, in the present invention, and manage the dissolved oxygen concentration C a (ppm) to be within a range of _{C sat -10 ≦ C ≦ C sa} t, it is desirable to reduce the sludge generation rate. Further, more preferably, the dissolved oxygen concentration C (ppm) is C
_It is preferable to manage it so that it is within the range of _sat −5 ≦ C ≦ C _sat −1. The saturated solubility (ppm) is preferably defined by the actual measurement value of the saturated solubility in the plating solution during the construction bath.

As a method for controlling the dissolved oxygen concentration to fall within the above range, the method of adjusting the flow rate of the oxygen-containing gas blown into the plating solution, the shape of the oxygen-containing gas blow-in port and the bubble diameter of the gas are controlled. Examples of the method of adjusting, the method of adjusting the oxygen concentration in the oxygen-containing gas, the method of blowing an inert gas, the method of blowing air, etc., if the dissolved oxygen concentration can be controlled within the above range, The method is not particularly limited.

When the oxygen enrichment tank and the tin dissolution tank are installed separately, the dissolved oxygen can be easily dissolved by changing the area of the oxygen blowing port of the oxygen enrichment tank and / or the gas bubble diameter. The concentration can be controlled. Alternatively, the dissolved oxygen concentration of the plating solution may be constantly measured with an oxygen concentration meter, and the valve opening degree of the oxygen blowing pipe may be adjusted according to the value.

If the concentration of dissolved oxygen in the plating solution during dissolution of tin is out of the control range, the sludge generation rate increases significantly,
This causes malfunction of the equipment due to adhesion of sludge and increase of stains on the plating surface, and a great deal of work is required to remove sludge. The second invention comprises the oxygen enrichment bath, the tin dissolution bath and the electroplating bath.
The electrotin plating method is not limited to the bath type electrotin plating method, and is preferably applied to a two bath type electrotin plating method including an electroplating bath and a tin dissolving bath.

In this case, the dissolved oxygen concentration of the plating solution at the inlet of the tin dissolution tank may be adjusted by the same method as described above such as adjusting the flow rate of the oxygen-containing gas blown into the plating solution so that the dissolved oxygen concentration is within the control range. . The first invention and the second invention have been described above. However, as described above, the present invention is not particularly limited as a conductive auxiliary agent of the acidic tin plating solution, but it is not limited to the electric conductivity using alkanesulfonic acid and / or alkanolsulfonic acid. It is preferably applied by the tin plating method.

As the alkane sulfonic acid, methane sulfonic acid, ethane sulfonic acid, propane sulfonic acid, 2-
Propane sulfonic acid, butane sulfonic acid, etc. are exemplified,
As alkanol sulfonic acids, 2-hydroxyethane-1-sulfonic acid, 2-hydroxypropane-1-sulfonic acid, 1-hydroxypropane-2-sulfonic acid, 2
-Hydroxybutane-1-sulfonic acid and the like are exemplified.

Further, in the present invention, more preferably, it is preferably applied to an electric tin plating method using methanesulfonic acid and / or 2-hydroxypropane-1-sulfonic acid as a conduction aid of an acidic tin plating solution. .
This is because the conductive aid improves the plating performance in electroplating and contributes to the expansion of the operating current density range, while the problem of tin sludge formation is more serious than in the case of using the conventional conductive aid phenolsulfonic acid. This is because it becomes remarkable and the present invention is more suitably applied.

[0036]

[First invention]

(Embodiment 1) FIG. 4 shows a configuration diagram of an electric tin plating apparatus in this embodiment.

In FIG. 4, 1 is an electroplating tank, 2 is an oxygen enrichment tank, 3 is a tin dissolution tank (stirring device), 4 is an oxygen-containing gas blowing pipe, 5 is a filter, 6 is a bubble (oxygen-containing gas). ), 7 is an oxygen enrichment stirrer, 8 is a metal tin particle, 9 is a stirring blade, 10 is a metal tin replenishing hopper, 11 and 12 are plating solution temperature control devices, 13 is a thermocouple, 14 is a temperature indicating controller, 15 is a valve,
16 is a pump, 17 is a strip, 20 is the moving direction of the plating solution,
21 indicates an insoluble anode.

The equipment specifications and operating conditions of the oxygen enrichment tank 2 and the tin dissolution tank 3 are as described later. In this example, 2 m ³ of a tin plating solution having the following composition containing methanesulfonic acid as a conduction aid and an additive was added, and the space between the oxygen enrichment tank 2 and the tin dissolution tank 3 is shown in FIG. ^So that Sn ²⁺
The temporal changes in ion concentration and tin sludge generation were investigated.

The temperature of the plating solution in the tin dissolving tank is controlled by a refrigerant indirect heat exchanger 11 and a steam indirect heating heat exchanger 12, which are installed between the electroplating tank 1 and the oxygen enrichment tank 2.
And the temperature indicating controller 14 installed at the inlet of the tin melting tank connected to them. [Tin plating solution composition] Sn ²⁺ ion concentration: 20 g / L Methanesulfonic acid: 0.5 mol / L Surfactant: 10 g / L Antioxidant: 1 g / L Electroplating bath plating solution temperature: 50 ° C [Oxygen rich Chemical tank] Effective volume: 3.0m ³ Filter surface area: 0.5m ² Stirrer rotation speed: 1500 rotations / minute Blow gas: Oxygen [Tin dissolution tank] Volume: 1.0m ³ Metal tin amount: 1000kg (minor diameter 3mm -Large diameter 7 mm teardrop) Stirring blade: Double helical ribbon blade Stirring blade rotation speed: 200 revolutions / minute Sn ²⁺ ion concentration in the plating solution was measured by titration every 10 minutes to dissolve tin per unit weight of plating solution. Speed (g / hr ・ kg)
I asked. Further, a small amount of the plating solution was sampled, and the sludge contained therein was filtered and weighed to obtain the sludge generation rate (g / hr · kg) per unit weight of the plating solution.

After adjusting the temperature of the plating solution in the tin dissolution tank to 30 ° C., oxygen is blown into the plating solution while stirring the solution in the oxygen enrichment tank to dissolve the oxygen in the plating solution, and the plating solution is filled with metallic tin. As a result of introducing the metal tin and the plating solution into the dissolution tank, the tin dissolution rate was 100 (g / hr · kg) and the sludge generation rate was 0.07%. (Examples 2, 3, 4, 5) Except that the temperature of the plating solution in the tin dissolution bath was adjusted to 35 ° C, 40 ° C, 42 ° C and 44 ° C, and the conduction aid of the plating solution was changed as shown in Table 1. Is Example 1
As a result of mixing the plating solution and the metal tin in the same manner as in, the tin dissolution rates were 150, 180, 190 and 198, respectively.
(g / hr ・ kg), sludge generation rate was less than 0.12%.

Comparative Example 1 A plating solution and metallic tin were mixed in the same manner as in Example 1 except that the temperature of the plating solution in the tin dissolution tank was adjusted to 20 ° C. As a result, the tin dissolution rate was 20 ( g /
hr · kg) and the sludge generation rate increased to 0.20%. (Comparative Examples 2, 3, 4) The temperature of the plating solution in the tin dissolution bath was set to 4
The plating solution and metallic tin were mixed in the same manner as in Example 1 except that the temperature was adjusted to 5 ° C, 50 ° C, and 60 ° C. As a result, the tin dissolution rates were 200, 170, and 90 (g / hr · kg), respectively. As a result of the increased sludge generation rate, the sludge generation rates increased to 0.13%, 0.20% and 0.40%, respectively.

The test results of Examples 1 to 5 and Comparative Examples 1 to 4 are summarized in Table 1.

[0043]

[Table 1]

From the results of Examples 1 to 5 and Comparative Examples 1 to 4 described above, by controlling the temperature of the plating solution in the tin dissolving tank within the range of the present invention, sludge generation which is important for the electrotin plating method is generated. It is shown that the rate can be reduced. [Second Invention] (Embodiment 6) FIG. 8 shows a configuration diagram of an electric tin plating apparatus in the present embodiment.

In FIG. 8, the same members as those in FIG. 4 are designated by the same reference numerals. In addition, 18 is an oxygen concentration meter, and 19 is a valve for adjusting the flow rate of oxygen-containing gas. The equipment specifications and operating conditions of the oxygen enrichment tank 2 and the tin dissolution tank 3 are as described below. In the present example, 2-hydroxypropane-1-sulfonic acid was used as a conduction aid, and a tin plating solution having the following composition with an additive was added in an amount of 2 m ^{3 to} prepare an oxygen enrichment tank 2 and a tin dissolution tank 3. The spaces were circulated as shown in FIG. 8, and changes over time in the Sn ²⁺ ion concentration and the amount of tin sludge generated were investigated.

The dissolved oxygen concentration in the plating solution at the inlet of the tin dissolving tank is controlled by measuring the value measured by the oxygen concentration meter 18 and the valve 19
It was carried out by adjusting the flow rate of oxygen blown into the oxygen enrichment tank by adjusting the opening degree of. In Example 6 and Examples 7 to 9 described later, and Comparative Example 5, the dissolved oxygen concentration in the plating solution in the tin dissolution tank inlet pipe was measured separately, and the same as the oxygen concentration meter 18 in the oxygen enrichment tank. It was confirmed that the value was shown.

[Composition of tin plating solution] Sn ²⁺ ion concentration: 20 g / L 2-hydroxypropane-1-sulfonic acid: 70 g / L surfactant: 10 g / L antioxidant: 1 g / L electroplating bath plating solution Temperature: 40 ° C. [Oxygen enrichment tank] Effective volume: 3.0 m ³ Filter surface area: 0.5 m ² Stirrer rotation speed: 1500 revolutions / minute Blow gas: Oxygen Oxygen enrichment tank Plating solution temperature: 40 ° C. [Tin dissolution] Tank] Volume: 1.0 m ³ Metal tin amount: 1000 kg (teardrop shape with a short diameter of 3 mm and a long diameter of 7 mm) Stirring blade: Double helical ribbon blade Stirring blade rotation speed: 200 rotations / minute Tin dissolution bath plating solution temperature: 40 ° C. Sn ²⁺ ion concentration in plating solution is measured by titration every 10 minutes, tin dissolution rate per unit weight of plating solution (g / hr ・ kg)
I asked. Further, a small amount of the plating solution was sampled, and the sludge contained therein was filtered and weighed to determine the sludge generation rate (g / hr · kg) per unit weight of the plating solution.

The measured value of the saturated dissolved oxygen concentration (C _sat ) at a temperature of 40 ° C., which was separately measured for the plating solution, was 30.5 ppm. By blowing oxygen while stirring the plating solution in the oxygen enrichment tank 2, the dissolved oxygen concentration in the plating solution in the oxygen enrichment tank is adjusted to 20.5 ppm (: C
While adjusting to _sat- 10), the plating solution was introduced into the tin dissolution tank 3 filled with the metal tin particles 8 to mix the metal tin and the plating solution, and as a result, the tin dissolution rate was 130 (g / hr · kg). ), And the sludge generation rate was 0.20%.

(Examples 7, 8 and 9) The dissolved oxygen concentration in the plating solution in the oxygen enrichment tank was 25.5 ppm, respectively.
(: C _sat -5), 29.5 ppm (: C _sat -1),
Example 6 except that the amount was adjusted to 30.5 ppm (: C _sat ).
In the same manner as described above, the tin dissolution rate was 150 and 17 respectively as a result of mixing the plating solution and metallic tin in the tin dissolution tank 3.
5, 180 (g / hr · kg), and the sludge generation rates were 0.06, 0.10, and 0.20%, respectively.

Comparative Example 5 The dissolved oxygen concentration in the plating solution in the oxygen enrichment tank was 15.5 ppm (: C _sat -15).
In the same manner as in Example 6 except that the plating solution and metallic tin were mixed in the same manner as in Example 6, the tin dissolution rate was reduced to 90 (g / hr · kg), and the sludge generation rate was decreased. 1.
It rose to 0%.

The test results of Examples 6 to 9 and Comparative Example 5 are summarized in Table 2.

[0052]

[Table 2]

From the results of Examples 6 to 9 and Comparative Example 5 described above, by controlling the dissolved oxygen concentration in the plating solution at the inlet of the tin dissolution tank within the range of the present invention, sludge important for the electrotin plating method is obtained. It is shown that the incidence can be reduced.

[0054]

INDUSTRIAL APPLICABILITY The present invention uses an insoluble anode to produce steel and other materials.
When electroplating tin metal with acidic tin plating solution
Sn in the plating solution²⁺Quickly supplying ions, tin plating
Sn in liquid ²⁺Ion concentration is controlled within an appropriate range, and tin
It also provides an efficient way to reduce sludge volume
Of. The present invention is resource saving, labor saving, production efficiency, product
It greatly contributes to the improvement of quality, and it also produces sludge.
The effect of reducing deterioration of the plating solution is extremely high.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a plating solution temperature and a sludge generation rate.

FIG. 2 is a graph showing the relationship between the plating solution temperature and the tin dissolution rate.

FIG. 3 is a graph showing the relationship between the plating solution temperature and the sludge generation rate.

FIG. 4 is a configuration diagram of an electric tin plating apparatus in an example.

FIG. 5 is a graph showing the relationship between the concentration of dissolved oxygen in the plating solution at a plating solution temperature of 40 ° C. and the sludge generation rate.

FIG. 6 is a graph showing the relationship between the dissolved oxygen concentration in the plating solution at a plating solution temperature of 40 ° C. and the tin dissolution rate.

FIG. 7 is a graph showing the relationship between the concentration of dissolved oxygen in the plating solution at a plating solution temperature of 40 ° C. and the sludge generation rate.

FIG. 8 is a configuration diagram of an electric tin plating apparatus in an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electroplating tank 2 Oxygen enrichment tank 3 Tin dissolution tank (stirring device) 4 Oxygen-containing gas blowing pipe 5 Filter 6 Bubbles (oxygen-containing gas) 7 Oxygen-enriching stirrer 8 Metal tin particles 9 Stirring blade 10 Metal tin Replenishing hopper 11, 12 Plating solution temperature control device 13 Thermocouple 14 Temperature indicating controller 15 Valve 16 Pump 17 Strip 18 Oxygen concentration meter 19 Oxygen-containing gas flow rate control valve 20 Plating solution moving direction 21 Insoluble anode

Claims (4)

[Claims] 1. A method for electroplating tin using an insoluble anode, wherein metal tin is held and a plating solution temperature in the bath is adjusted to 30 ° C. or higher and lower than 45 ° C. A method for electroplating tin using an insoluble anode, characterized in that the electroplating is performed using the obtained plating solution. 2. An electrotin plating method using an insoluble anode, which is obtained by dissolving metallic tin in a plating solution having a dissolved oxygen concentration C (ppm) adjusted to fall within the range of the following formula (1). An electrotin plating method using an insoluble anode, characterized in that electrotin plating is performed using the above plating solution. Note C _sat -10 ≤ C ≤ C _sat ··· (1) In the formula (1), C _sat is the temperature of the plating solution when the metal tin is dissolved and the oxygen partial pressure is 1.01 × 10 ⁵ Pa. Indicates the saturated solubility (ppm) of oxygen in the plating solution. 3. The electrotin plating method using an insoluble anode according to claim 1, wherein an alkane sulfonic acid and / or an alkanol sulfonic acid is used as a conduction aid of the plating solution. 4. The method of electroplating tin using an insoluble anode according to claim 1, wherein methanesulfonic acid and / or 2-hydroxypropane-1-sulfonic acid is used as a conduction aid of the plating solution.