JP2013053338A - Concentration measuring method for dye-based additive in copper sulfate plating solution, plating method, and plating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a concentration measuring method by which the concentration of a dye-based additive in a copper sulfate plating solution is quantitatively analyzed by a simple operation, and to provide a plating method and a plating device using the method.SOLUTION: The concentration measuring method for the dye-based additive in the copper sulfate plating solution includes: measuring absorbance of the copper sulfate plating solution by using light having a wavelength selected from the range of 360-510 nm and calculating the concentration of the dye-based additive in the copper sulfate plating solution from the absorbance. Further, there are also provided the plating method and plating device using the measuring method.

Description

  The present invention relates to a method for measuring the concentration of a dye-based additive in a copper sulfate plating solution, a plating method, and a plating apparatus.

  As a copper sulfate plating solution, a solution obtained by adding a brightener component (accelerator), a leveler component, and a carrier component as additive components to a plating solution composed of copper sulfate, sulfuric acid, and chlorine is generally used. As the leveler component additive, a dye-based additive represented by Janus Green B is often used.

  In the copper sulfate plating solution, the concentration of sulfuric acid and chloride ions decreases and the concentration of copper ions increases due to the plating reaction. Also, the additive component is gradually consumed by the plating reaction.

  Excess or deficiency of each component constituting the plating solution greatly affects the uniformity and finish of the plating. Therefore, in order to maintain the plating quality, it is necessary to manage each component at a constant concentration.

  As a conventional method for managing a copper sulfate plating solution, for example, as described in Patent Document 1, sulfuric acid is automatically analyzed and managed by neutralization titration method, and chlorine ions and copper ions are colorimetrically analyzed. The excess or deficiency of the components was adjusted based on this.

  As for the dye-based additive, as a laboratory analysis method, a quantitative analysis method using electrochemical analysis as in Non-Patent Document 1 is known, but in the manufacturing process, it was obtained by a Hull cell test. A method of qualitatively controlling the degree of additive consumption by the color of the plated surface has been taken.

Japanese Patent Laid-Open No. 4-187800

Electrochemical Analysis of Via Filling Acid Copper Plating Additives Tomoko Nishitani et al. (Abstracts of Lecture Meetings of the Surface Technology Society of Japan, Issued on March 2, 2009, No. 119, p. 191)

  The above-described electrochemical analysis method as described in Non-Patent Document 1 requires analysis expertise and expensive analysis equipment, so it is limited to use at the laboratory level and should be used in the actual plating product manufacturing process. Was difficult. Moreover, although the Hull cell test can be performed simply, there is a problem that quantitative management is difficult because it is only a qualitative analysis by color.

  An object of the present invention is to provide a concentration measuring method capable of quantitatively analyzing the concentration of a dye-based additive in a copper sulfate plating solution by a simple operation in view of the above-described problems of the prior art.

  In order to solve the above-mentioned problems, the present invention measures the absorbance of a copper sulfate plating solution using light having a wavelength selected from a range of 360 nm or more and 510 nm or less. From the absorbance, the dye-based additive in the copper sulfate plating solution is measured. Provided is a method for measuring the concentration of a dye-based additive in a copper sulfate plating solution, wherein the concentration is calculated.

  According to the present invention, in a copper sulfate plating solution (acidic copper plating solution) used in the production of a flexible wiring board (FPC), the concentration of the dye-based additive in the plating solution is quantitatively analyzed with a simple operation. Can do.

Wavelength dependence of absorbance of aqueous copper sulfate solution and aqueous copper sulfate solution with Janus Green B added Calibration curve for light having a wavelength of 510 nm to 585 nm, prepared from the results of FIG. Wavelength dependence of absorbance of copper sulfate aqueous solution with Brightener component and carrier component added Explanatory drawing of the plating apparatus in 3rd Embodiment which concerns on this invention Wavelength dependence of absorbance of basic composition plating solution in examples according to the present invention Calibration curve for dye-based additives in the examples according to the invention Concentration change of dye-based additive in copper sulfate plating solution measured in Examples according to the present invention

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments, and the following embodiments are not departed from the scope of the present invention. Various modifications and substitutions can be made.
[First Embodiment]
The inventors of the present invention, as a result of intensive studies on the means for quantifying the dye-based additive in the copper sulfate plating solution, have used light in a wavelength region in which components contained in the basic solution such as copper sulfate do not absorb light. The present inventors have found that the content of the dye-based additive can be calculated from the absorbance measured in this manner. Specifically, in the present invention, the concentration of the dye-based additive in the copper sulfate plating solution is calculated from the absorbance measured by irradiating the copper sulfate plating solution with light having a wavelength selected from a range of 360 nm to 510 nm. To do.

  In the present embodiment, a method for measuring the concentration of the dye-based additive in the copper sulfate plating solution will be described below.

  First, various components in the copper sulfate plating solution will be described. A plating solution composed of copper sulfate, sulfuric acid and chlorine is used as a basic solution (basic composition solution). Further, a leveler component that is a precipitation inhibitor, a brightener component that is a precipitation accelerator, a carrier component, and the like can be further added to the basic solution as additional components.

  Examples of the leveler component include dye-based additives to be analyzed in the present invention, and any dye-based additive can be used without particular limitation because it exhibits the same or similar light absorption characteristics. Examples of the dye-based additive include Janus Green B containing nitrogen in its structure, phenosafranine, safranine, crystal violet, methyl violet, and the like.

  The brightener component and the carrier component are not particularly limited, and various known components can be used. Specifically, as the brightener component, sulfur-based additive bis- (3-sulfopropyl) -disulfide (hereinafter simply referred to as SPS), 3 mercapto-1-propanesulfonic acid (MPS), 3-amidinothio Examples include -1-propanesulfonic acid (UPS).

  Furthermore, examples of the carrier component include polyethylene glycol (hereinafter simply referred to as PEG), polypropylene glycol (PPG), and a copolymer of PEG and PPG.

  In order to obtain a plating film with a flat surface, it is preferable that the copper sulfate plating solution contains the above-described additive component in addition to the dye-based additive, a sulfur-based additive that is a brightener component, It is preferable to contain a carrier component.

  And in this Embodiment, the light absorbency of the copper sulfate plating solution which has the above components is measured, and the density | concentration of dye type additive is computed from the measured value. When measuring the absorbance, a spectrophotometer is used. However, the spectrophotometer can be used without particular limitation as long as it can measure the absorbance in a predetermined wavelength region.

  Here, in the aqueous solution of copper sulfate (copper 30 g / L, sulfuric acid 200 g / L, hydrochloric acid 50 mg / L), a dye-based additive (Janus Green B, in the figure) so as to have a predetermined concentration between 5 and 20 mg / L. FIG. 1 shows the wavelength dependence of the light absorption characteristics of an aqueous copper sulfate solution added with JGB). For comparison, a sample containing only an aqueous copper sulfate solution is also shown.

  The measurement was performed by filling each sample in a quartz glass cell having an optical path length of 1 cm and using an ultraviolet-visible spectrophotometer. Hereinafter, the absorbance is measured under the same conditions.

  According to FIG. 1, in the wavelength region of 335 nm or more and 510 nm or less, the absorbance of the copper sulfate aqueous solution is almost 0, and it can be seen that no light absorption occurs. On the other hand, the sample added with Janus Green B has a greater absorbance in proportion to the amount added in the wavelength region. In particular, in the wavelength region of 360 nm or more and 510 nm or less, the absorbance changes greatly in proportion to the added amount.

  Here, FIG. 2 shows a calibration curve of Janus Green B, which is created from the measurement results of FIG. 1 and uses light of each wavelength of 510 to 585 nm.

  According to the result of FIG. 2, when light having a wavelength of 510 nm is used, the intercept of the calibration curve is 0, and furthermore, there is almost no difference between the measured value and the calibration curve.

  On the other hand, the intercept is larger than 0 in the calibration curve of 535 nm or more. For this reason, as shown in FIG. 2, when the calibration curve was drawn so that the intercept was 0, the difference from the measured value became large. As can be seen from FIG. 1, this is because the aqueous solution of copper sulfate causes light absorption in the wavelength region of 535 nm or more, and the value of the intercept varies depending on the concentration of copper sulfate. For this reason, it is considered difficult to accurately determine the concentration of the dye-based additive in the wavelength region of 535 nm or more.

  Next, FIG. 3 shows the wavelength dependence of the light absorption characteristics of other additive components in the wavelength region of 360 nm to 510 nm. Here, SPS that is a sulfur-based additive (Brightener component) and PEG that is a carrier component were measured using a copper sulfate aqueous solution added so that each component had a concentration of 1000 mg / L. This is a much higher concentration than that usually added to the plating solution. According to this, it is understood that these additive components do not absorb light in a wavelength region of 360 nm or more and 510 nm or less.

  From the above results, when measured in the wavelength region of 360 nm or more and 510 nm or less, components other than the dye-based additive contained in the plating solution such as an aqueous copper sulfate solution do not exhibit light absorption, and only the dye-based additive to be measured It can be seen that shows light absorption. For this reason, it is possible to accurately calculate the concentration of the dye-based additive in the copper sulfate plating solution from the absorbance measured using the light in the wavelength region.

  Here, a specific procedure of the method for measuring the concentration of the dye-based additive in the copper sulfate plating solution will be described. First, the wavelength of light used for measurement is selected from the wavelength region of 360 nm or more and 510 nm or less, and a calibration curve is created for light of that wavelength, for example, as in the case of using light with a wavelength of 510 nm shown in FIG. . Next, the absorbance of the copper sulfate plating solution containing the dye-based additive to be measured is measured with light having the same wavelength as the light used in the calibration curve, and the concentration can be calculated from the measured value and the calibration curve prepared in advance. .

  The wavelength of the light used is not limited as long as it is selected from the range of 360 nm or more and 510 nm or less, but as can be seen from FIG. 1, in the wavelength region of 460 nm or more and 510 nm or less, the dye-based additive is used. The difference in absorbance due to concentration increases. For this reason, since it is possible to calculate the concentration with higher accuracy, it is more preferable to perform measurement using light in a wavelength region of 460 nm or more and 510 nm or less.

As explained so far, according to the measurement method of the present invention, conventionally, quantitative analysis of dye-based additives in a plating solution, which has been difficult to perform quantitative analysis, is easily performed without requiring any special operation. It becomes possible. For this reason, the component management of a plating solution can be easily performed now by applying to a plating product manufacturing process etc.
[Second Embodiment]
In the present embodiment, a plating method will be described.

Specifically, it is a plating method using a copper sulfate plating solution containing a dye-based additive, and includes the following steps (A) to (C).
(A) The step of measuring the absorbance of the copper sulfate plating solution with light having a wavelength selected from the range of 360 nm or more and 510 nm or less (B) The dye contained in the copper sulfate plating solution from the measured absorbance A step of calculating the concentration of the system additive (C) a step of supplying a dye-based additive to the copper sulfate plating solution based on the calculated concentration.

  First, the apparatus and material used for the said plating method are demonstrated.

  The composition of the plating solution to be used is not particularly limited, and any copper sulfate plating solution containing a dye-based additive can be used. For example, as described in the first embodiment, a dye-based additive, a brightener component (sulfur-based additive), and a carrier component additive are added to a plating solution composed of copper sulfate, sulfuric acid, and chlorine. A copper sulfate plating solution can be preferably used.

Further, the structure of the electroplating tank to be used is not particularly limited. For example, the plating tank contains a copper sulfate plating solution containing a dye-based additive, and has a structure in which an anode immersed in the plating solution, a cathode, and a power supply unit that connects the both and supplies a direct current Is mentioned. Furthermore, a stirring device or the like for stirring the inside of the plating tank can be provided. And, in the above-described step (A), the present invention measures the absorbance of the plating solution, and is used when measuring the absorbance. As the spectrophotometer, any spectrophotometer can be used without particular limitation as long as it can measure in a predetermined wavelength region. For example, an ultraviolet-visible spectrophotometer can be used.

  The installation mode of the spectroscopic device is not particularly limited, and can be selected depending on the frequency of analysis, the size of the plating tank, and the like. For example, the plating solution is appropriately sampled manually or automatically, and supplied to a cell of a spectrophotometer so that the measurement can be performed. Moreover, the form etc. which arrange | position and fix the measuring part of the optical fiber probe connected to the light source part of a spectrophotometer, and a light-receiving part in a plating solution, and measure directly in a plating solution are also mentioned. Here, the optical fiber probe is configured such that light from the light source part passes through the plating solution in the measurement part via the optical fiber and enters the light receiving part again via the optical fiber.

  The present invention includes the steps (A) to (C) described above, but the timing for performing these steps is not particularly limited. For example, when preparing and adjusting a plating solution, This can be done to manage the plating solution in the process.

  Below, the procedure of a plating method is demonstrated using the example which performed the said (A)-(C) process during the plating process.

  Similar to a normal plating method, plating is started by passing a direct current between electrodes immersed in a copper sulfate plating solution. The plating conditions such as current density at this time are appropriately selected depending on the target plating thickness, the type of substrate, and the like.

  In the present embodiment, a step of measuring the absorbance by irradiating the copper sulfate plating solution with light having a wavelength selected from a range of 360 nm or more and 510 nm or less at a predetermined time interval during the plating step. Do. Next, a step of calculating the concentration of the dye-based additive from the measured absorbance based on a calibration curve prepared in advance is performed.

  Here, the interval for measuring the absorbance and calculating the concentration of the dye-based additive, the measurement conditions, etc. are not particularly limited, but the size of the substrate used, the composition of the plating bath, the required plating film surface It is selected according to flatness or the like.

  Next, a step of supplying a dye-based additive to the copper sulfate plating solution based on the concentration calculated in the previous step is performed.

  Here, the supply amount of the dye-based additive, the control of the timing, etc., the judgment criteria are selected according to the size of the plating tank, the composition of the plating solution, the required flatness of the plating film, etc. It is not limited. An example of a specific control method is to supply a predetermined amount of dye-based additive to the plating tank when the calculated concentration of the dye-based additive falls below this with reference to a predefined concentration. In the case of exceeding, there is a method of continuing the plating process without supplying.

  In addition, the lower limit concentration and the upper limit concentration of the dye-based additive are respectively defined. When the calculated dye-based additive concentration is less than the lower limit concentration, the supply of the dye-based additive is started, and the upper limit concentration is exceeded. In such a case, there is a method of stopping supply or not supplying.

  In addition, a method of controlling the opening degree of a valve provided on the pipe based on the calculated concentration by connecting the tank containing the dye-based additive and the plating tank with the pipe. Can be mentioned.

  According to the plating method described above, the concentration of the dye-based additive in the copper sulfate plating solution can be easily maintained and adjusted within a certain range. For this reason, the number of irregularities generated on the surface of the obtained plating film can be reduced, and a high-quality plating film can be formed.

  In addition, although demonstrated using the example which implemented the said (A)-(C) process during the plating process here, the timing which performs these processes is not limited during a plating process. For example, it is also possible to calculate the concentration of the dye-based additive before adjusting the plating solution before starting the plating process and adjust the concentration.

In this embodiment, plating is performed while measuring and controlling the concentration of the dye-based additive. The concentration of other components in the plating solution is also measured by various analysis methods, and is within a certain range. It is preferable to control to be within.
[Third Embodiment]
In the present embodiment, a plating apparatus capable of performing electroplating while measuring the concentration of a dye-based additive will be described.

  The configuration is a plating apparatus using a copper sulfate plating solution containing a dye-based additive, and the absorbance of the copper sulfate plating solution in the plating tank is measured by light having a wavelength selected from a range of 360 nm to 510 nm. Calculate the concentration of the dye-based additive contained in the copper sulfate plating solution from the absorbance, and supply signal to the dye-based additive tank based on the calculated concentration And a dye-based additive tank for supplying the dye-based additive to the plating tank based on a replenishment signal from the dye-based additive concentration controller. It is the plating equipment to do.

  The configuration of the above apparatus will be described with reference to FIG.

  As shown in FIG. 4, the plating apparatus according to the present embodiment includes a plating tank 10, a dye-based additive concentration measuring unit 11, a dye-based additive concentration control unit 12, and a dye-based additive tank 13. .

  Here, each member which comprises a plating apparatus is demonstrated.

  First, the configuration of the plating tank 10 is not particularly limited, and various known plating tanks can be employed. For example, the plating tank contains a copper sulfate plating solution containing a dye-based additive, and has a configuration in which an anode and a cathode immersed in the plating solution are connected to each other, and a power supply unit that supplies a direct current is connected. Is mentioned. Furthermore, a stirring device or the like for stirring the inside of the plating tank can be provided.

  Next, it is sufficient if the dye-based additive concentration measuring unit 11 is configured to be able to measure the absorbance of the plating solution with light having a predetermined wavelength.

  Examples of the configuration of the dye-based additive concentration measuring unit include a configuration including a spectrophotometer and a measurement cell provided in the spectrophotometer. And it is preferable that the measurement cell and the plating tank are connected by piping so that the plating solution in the plating tank can be circulated in the measurement cell. In this case, since the plating solution in the plating tank is circulated through the measurement cell by, for example, a pump provided on the pipe, the plating solution can be easily sampled and the absorbance can be measured.

  Another example of the configuration of the dye-based additive concentration measuring unit is a configuration in which the measuring unit of the optical fiber probe connected to the light source unit and the light receiving unit of the spectrophotometer is installed and fixed in the plating solution.

  Next, the dye-based additive concentration control unit 12 first calculates the dye-based additive concentration from the absorbance measured by the dye-based additive concentration measuring unit 11 using a calibration curve prepared in advance. The replenishment signal is transmitted to the dye-based additive tank 13 based on the calculated dye-based additive concentration.

  Here, the replenishment signal is a signal for instructing the dye-based additive tank 13 to supply the dye-based additive to the dye-based additive tank 13 based on the calculated dye-based additive concentration. The contents are not limited and are selected according to the configuration of the apparatus.

  As the contents of the replenishment signal command, for example, when the calculated dye-based additive concentration is lower than the standard concentration specified in advance, a predetermined amount of dye-based additive is supplied to the plating tank. In the case of exceeding, there is a command to continue the plating process without supplying.

  In addition, the lower limit concentration and the upper limit concentration of the dye-based additive are respectively defined. When the calculated dye-based additive concentration is less than the lower limit concentration, the supply of the dye-based additive is started, and the upper limit concentration is exceeded. If so, a command to stop the supply is given.

  Furthermore, a command for changing the opening degree of a valve provided on a pipe connecting the dye-based additive tank and the plating tank according to the calculated dye-based additive concentration is also included.

  The dye-based additive tank 13 is a tank that is connected to the plating tank 10 and stores the dye-based additive therein, and based on the command from the dye-based additive concentration control unit 12 as described above. The dye-based additive is supplied to the plating tank.

  According to the plating apparatus explained above, the concentration of the dye-based additive in the plating tank can be easily quantitatively measured, and the concentration of the dye-based additive in the plating tank can be accurately controlled based on the measured value. can do.

  In the present embodiment, the measurement and control device of the dye-based additive has been described, but various components in the plating solution, for example, various analysis and control devices for the brightener component, etc. are also added. Also, it is preferable to control so as to be within a certain range.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to the Example which concerns.

  First, a copper sulfate plating solution having a liquid composition shown in Table 1 is prepared for wet copper plating.

  Next, a calibration curve showing the relationship between absorbance (ABS) and Janus Green B concentration was prepared. As a procedure, first, a basic composition liquid to which Janus Green B is not added and a basic composition liquid to which Janus Green B is added to a predetermined concentration between 5 mg / L and 30 mg / L are prepared. The absorbance of each sample was measured in the wavelength range of 360 nm to 510 nm. A calibration curve was created based on the measured values. Here, the basic composition liquid means a liquid composition having the liquid composition shown in Table 1 and without adding Janus Green B. The measured absorbance is shown in FIG. In the figure, Janus Green B is written as JGB.

  From the results shown in FIG. 5, light having a wavelength of 510 nm, in which the light absorbency (ABS) of the basic composition solution to which no additive is added is 0 and the displacement width of the light absorbency (ABS) is large with respect to the change in the amount of Janus Green B added. It was decided to measure by. A calibration curve at 510 nm is shown in FIG.

  In the actual plating process, plating was performed while appropriately sampling the plating solution, measuring the absorbance, and calculating the concentration of Janus Green B using the calibration curve.

  Here, as the copper sulfate plating solution for wet copper plating used, the copper sulfate plating solution having the liquid composition shown in Table 1 is used, and Janus Green B is 18.0 mg in the initially prepared copper sulfate plating solution. / L contained. And when a plating process is performed and the measured concentration of Janus Green B is reduced to about 12.0 mg / L, Janus Green B is continuously added so that the concentration becomes 15.0 to 16.0 mg / L. The plating process was performed. Changes in the concentration of Janus Green B during this plating process are shown in FIG.

  According to FIG. 7, it can confirm that the density | concentration of Janus green B is falling by implementing a plating process. It was also confirmed that when Janus Green B concentration was reduced to about 12.0 mg / L, adding Janus Green B increased the concentration. That is, it can be seen that the measurement is performed accurately.

  And when the surface of the plating film obtained as a result of the plating process was examined, it was confirmed that a plating film with few irregularities and high flatness was stably obtained throughout the plating process.

DESCRIPTION OF SYMBOLS 10 Plating tank 11 Dye-type additive density | concentration measurement part 12 Dye-type additive density | concentration control part 13 Dye-type additive tank

Claims (5)

  Sulfuric acid characterized in that the absorbance of a copper sulfate plating solution is measured using light having a wavelength selected from a range of 360 nm or more and 510 nm or less, and the concentration of the dye-based additive in the copper sulfate plating solution is calculated from the absorbance. A method for measuring the concentration of a dye-based additive in a copper plating solution.   2. The dye-based addition in a copper sulfate plating solution according to claim 1, wherein the copper sulfate plating solution contains a sulfur-based additive and a carrier component in addition to the dye-based additive as an additive. Concentration measurement method.   The method for measuring a concentration of a dye-based additive according to claim 1 or 2, wherein the dye-based additive contains nitrogen in its structure. A plating method using a copper sulfate plating solution containing a dye-based additive, comprising the following steps (A) to (C).
(A) The step of measuring the absorbance of the copper sulfate plating solution with light having a wavelength selected from the range of 360 nm or more and 510 nm or less (B) The dye contained in the copper sulfate plating solution from the measured absorbance A step of calculating the concentration of the system additive (C) a step of supplying a dye-based additive to the copper sulfate plating solution based on the calculated concentration. A plating apparatus using a copper sulfate plating solution containing a dye-based additive,
A dye-based additive concentration measurement unit that measures the absorbance of the copper sulfate plating solution in the plating tank with light having a wavelength selected from a range of 360 nm or more and 510 nm or less;
A dye-based additive concentration control unit that calculates the concentration of the dye-based additive contained in the copper sulfate plating solution from the absorbance and transmits a replenishment signal to the dye-based additive tank based on the calculated concentration When,
A plating apparatus comprising: a dye-based additive tank that supplies a dye-based additive to a plating tank based on a replenishment signal from the dye-based additive concentration control unit.

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