JP2976319B2 - Etching waste liquid treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for removing copper from an etching waste solution obtained by etching a copper printed circuit board with, for example, a ferric chloride etching solution.

[0002]

2. Description of the Related Art Etching of a copper printed circuit board with a ferric chloride (FeCl ₃ ) etching solution is generally performed by a consumer,
It is widely used in a wide range of fields such as industrial equipment. As described above, the etching reaction when copper (Cu), which is the material to be etched, is etched using the ferric chloride etching solution proceeds according to the reaction formula shown in the following formula (1).

Cu + 2FeCl ₃ → CuCl ₂ + 2FeCl ₂ (1) Therefore, the etching waste liquid after the etching treatment includes cupric chloride (CuCl ₂ ) and ferrous chloride (FeCl ₂ ) which are products of the etching reaction. Unreacted ferric chloride or hydrochloric acid (HC) originally contained in the etching solution
l) is included.

As described above, since the etching waste liquid contains copper, which is relatively expensive, as cupric chloride, conventionally, this copper is effectively used and the ferric chloride etching liquid is regenerated. Therefore, iron (F
A method of reducing the etching waste liquid by adding a reducing agent such as e) is employed. In this method, cupric chloride contained in the etching waste liquid is generated and recovered as copper metal by a reduction reaction with iron, and the reaction between cupric chloride and iron, and the reaction between ferric chloride and iron. The reaction of hydrochloric acid with iron produces ferrous chloride, and this ferrous chloride is chlorinated together with ferrous chloride as an etching product to regenerate the etching solution as ferric chloride. Things.

[0005] Since these reactions proceed in the order of potential, the reaction between ferric chloride and iron, the reaction between cupric chloride and iron, and the reaction between hydrochloric acid and iron. In some cases, the reaction is carried out in separate reaction tanks, and the respective reaction tanks are connected in series, whereby the reduction reaction divided into each step is continuously performed. The management of this processing step is performed by measuring the oxidation-reduction potential, visually observing the color and state of the solution, and empirically judging.

[0006]

However, in the conventional process management, the method for measuring the oxidation-reduction potential is to detect the total potential irrespective of the type of the substance. Since it is difficult, and it is not possible to determine the measurement target even by a method of visually judging, the concentration of the etching waste liquid cannot be measured accurately in each of the reduction treatment steps divided into several stages, and Since the time is long, there is a problem that accurate control of the process control in real time cannot be performed. In addition, there is a problem that the quality varies in the final process, and there is a problem that complicated manual analysis is required to suppress the quality variation.

The present invention has been made under such circumstances, and an object of the present invention is to accurately and quickly measure the concentration of copper ions in an etching waste liquid, and based on the measurement results, to determine the etching waste liquid. To provide an etching waste liquid treatment apparatus for automatically and accurately controlling a reduction treatment step.

[0008]

According to the present invention, there is provided a reduction reaction tank for performing a reduction treatment by adding a reducing agent to an etching waste liquid obtained by etching copper using an etching solution; Sampling means for sampling the solution, copper ions contained in the solution sampled by the sampling means are reduced to monovalent copper ions, and the monochromatic light transmittance of the solution is measured.
Te, monovalent sampling solution based on the measurement result
A measuring means for detecting a copper ion concentration, and a coloring agent selectively reacting with monovalent copper ions are supplied to the sampling solution,
Even when the monovalent copper ion concentration in the solution is low, a sampling solution adjustment unit for performing accurate concentration detection, and when the copper ion concentration measured by the measuring means is higher than a predetermined value. Diluent supply means for diluting the sampling liquid, and control means for controlling a reduction treatment of the solution in the reduction reaction tank based on a detection value from the measurement means, I do.

[0009]

[Effect] For example, an etching waste liquid after an etching treatment of, for example, a copper printed board with a ferric chloride etching solution is supplied to a reduction reaction tank, and the reduction treatment is performed by adding a reducing agent such as iron in the reduction reaction tank. Done.
The cupric chloride contained in the etching waste liquid is recovered as copper metal, and the ferrous chloride solution is supplied to a regenerating means, where the ferric chloride solution is regenerated as a ferric chloride etching liquid by a chlorination reaction.

On the other hand, the solution in the reduction reaction tank is continuously sampled by sampling means, for example, and divalent copper ions (Cu ²⁺ ) contained in the solution are reduced to monovalent copper ions (Cu ⁺ ). After the addition of a reducing agent or a coloring agent, the concentration of monovalent copper ions in the solution is detected by an absorption spectrophotometer in a measuring means. The detected monovalent copper ion concentration is input to the control means, and a control signal is output from the control means by comparing this value with the set value of the monovalent copper ion concentration, for example, in the reduction reaction tank. By controlling the residence time of the solution and the amount of iron as a reducing agent, the process of reducing the etching waste liquid is controlled.

[0011]

FIG. 1 is a configuration diagram of an etching waste liquid processing apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a waste liquid storage tank for storing an etching waste liquid obtained by etching a material to be etched, for example, a copper printed board with a ferric chloride etching solution. The reduction reaction tank 2 is connected via a feed passage 11, and a valve 12 for adjusting the inflow amount is provided at an intermediate portion of the supply passage 11. The reduction reaction tank 2 is provided in the vicinity of the reduction reaction tank 2 for an etching waste liquid containing cupric chloride, ferrous chloride, and ferric chloride supplied from the waste liquid treatment tank 1 via the supply path 11. This is a reaction tank for adding iron scrap as a reducing agent from the reducing agent supply means 25 and reducing the etching waste liquid.

The regenerating means 6 is connected to the reduction reaction tank 2 via a supply path 21 and an outflow control valve 22 provided at an intermediate portion of the supply path 21. Reproduction means 6
Is a means for regenerating the ferric chloride etching solution by performing a chlorination reaction on the ferrous chloride solution supplied from the reduction reaction tank 2. The supply path 21 is branched to a circulation path 23 on the reduction reaction tank 2 side from the valve 22, and the circulation path 23 is connected to the reduction reaction tank 2 via a pump 24. Further, the circulation path 23 is connected to a sampling solution adjustment unit 31 via a sampling means 3 for sampling a solution in the reduction reaction tank 2 flowing in the circulation path 23. For example, the sampling means 3 includes a corrosion-resistant tubing pump, a corrosion-resistant filter (mesh diameter of about 1 .mu.) For preventing slurry from mixing solids in the sampling solution.

The sampling solution adjusting section 31 adds an appropriate amount of a reducing agent such as hydroxylamine hydrochloride or ascorbic acid to the solution containing cupric chloride sampled by the sampling means 3 to convert divalent copper ions. It is reduced to monovalent copper ions, and if necessary, an appropriate amount of, for example, sodium bathocuproine sulfonate as a color former, or, for example, sodium citrate as a pH adjuster, is added thereto, and the measuring means described later is used. 4 is a part for adjusting the solution measured by 4. When it is necessary to dilute the sampling solution, the diluting solution obtained by mixing the above-described reducing agent, coloring agent, pH adjusting agent, and the like, by the diluting liquid supply means 33 disposed near the sampling solution adjusting unit 31. The liquid is supplied and the sampling solution is adjusted. The measuring means 4 is connected to the sampling solution adjusting section 31 via a supply path 32.

The measuring means 4 is a means for measuring the absorbance (transmittance) of the sampling solution and detecting the concentration of monovalent copper ions. For example, as shown in FIG. A measuring cell 40 to which a sampling solution is supplied via a passage 32 and a measuring unit provided in the vicinity thereof and detecting the concentration of monovalent copper ions in the sampling solution supplied into the measuring cell 40 by an absorption spectrophotometric method. Be composed.

The measuring unit passes through a light emitting source 41 formed of, for example, a lamp, a diffraction grating 42 forming a light splitting unit for splitting light from the light emitting source 41, and an emission slit 43 from the diffraction grating 42. A filter 44 for extracting monochromatic light having a wavelength of, for example, 480 nm from monochromatic light, a detector 45 for detecting light transmitted through the measurement cell 40 from the filter 44 and converting the light into an electric signal, and amplifying the signal. An amplifier 46 and an output signal I of the amplifier 46
And an output signal I corresponding to the intensity of light from the filter 44
_0, and a calculating unit 47 for calculating the transmittance T (T = I / I ₀ ), and L connected to the output side of the calculating unit 47.
The log converter 48 includes a meter display unit 49 that is switched between an input terminal and an output terminal of the Log converter 48.

On the output side of the measuring means 4, a valve 12,
The control unit 5 that outputs control signals 51, 52, 53, and 54 is provided for the 22, the reducing agent supply unit 25, and the diluent supply unit 33, respectively.

Next, the operation of the above embodiment will be described.
The etching waste liquid in the waste liquid storage tank 1 is supplied into the reduction reaction tank 2 through the supply path 11. In the reduction reaction tank 2,
By the addition of iron as a reducing agent from the reducing agent supply means 25, as described above in the section of "Prior Art", a reduction treatment of the etching waste liquid is performed, and cupric chloride contained in the etching waste liquid is reduced. It is recovered as copper metal by a reduction reaction with iron. On the other hand, the ferrous chloride solution is supplied to the regenerating means 6 via the supply path 21 and the valve 22, and the chlorination reaction of ferrous chloride is performed in the regenerating means 6, whereby the ferric chloride etching solution is regenerated. Is done.

Here, when the concentration of copper ions contained in the ferrous chloride solution supplied from the reduction reaction tank 2 to the regenerating means 6 is high, the impurity contained in the regenerated ferric chloride etching solution is reduced. Therefore, it is necessary to control the reduction process based on the concentration of copper ions contained in the solution in the reduction reaction tank 2. The management is performed as follows.

That is, the solution in the reduction reaction tank 2 is constantly circulating in the circulation path 23 by the activation of the pump 24, and is sampled by the sampling means 3 on the way to be supplied to the sampling solution adjusting section 31. Then, the sampling solution adjusting section 31 adjusts the sampling solution for performing accurate concentration detection in the measuring means 4. For example, in the sampling solution, there are divalent copper ions that have not been reduced and monovalent copper ions that are being reduced, but the measuring means 4 detects monovalent copper ions in the solution. Because of the concentration, it is necessary to reduce all divalent copper ions contained in the sampling solution to monovalent copper ions. Therefore, the sampling solution adjusting unit 3
In 1, the adjustment is performed by adding a reducing agent such as hydroxylamine hydrochloride or ascorbic acid to the sampling solution to reduce divalent copper ions in the sampling solution to monovalent copper ions.

In addition, for example, bathocuproine sulfonic acid selectively reacting with monovalent copper ions so that accurate concentration detection can be performed even when the concentration of monovalent copper ions in the solution is low. A coloring agent such as sodium is added in an appropriate amount according to the monovalent copper ion concentration. Furthermore, the color development of this bathocuproine sodium sulfonate depends on the pH of the solution.
Since the value is preferably about 3 to 9, it is possible to add an appropriate pH adjuster such as a sodium citrate solution. The sodium citrate solution is used to prevent the coexisting ions from forming a precipitate.
It has an H buffer effect, and the pH value of the solution can be adjusted to an arbitrary value of 3 to 5 by changing its concentration. In addition, when the monovalent copper ion concentration in the solution is about 100 to 3000 ppm, the coloring agent or p
Accurate concentration detection is performed without adding an H adjuster.

Further, when the concentration of monovalent copper ions in the solution is 3
When the concentration is 000 ppm or more, the solution needs to be diluted, and the diluent is added from the diluent supply means 33 to perform adjustment. Here, when the diluent is oxidizing (for example, when dissolved oxygen is contained), monovalent copper ions contained in the solution may be oxidized to divalent copper ions. In order to suppress the measurement error, when the amount of the reducing agent such as hydroxylamine hydrochloride is small, it is preferable to add the reducing agent again to reduce divalent copper ions to monovalent copper ions.

In this way, the sampling solution adjusting unit 3
1 is supplied to the supply path 32
Is supplied into the measuring cell 40 via the measuring device, and the concentration of monovalent copper ions in the solution is detected in the measuring section by the absorption spectrophotometry. The detection of the monovalent copper ion concentration by the absorptiometry is performed, for example, as follows.

That is, the light emitted from the light emitting source 41 is
400 nm to 560 n via a diffraction grating 42, an exit slit 43, and an optical filter 44 provided in the optical path.
After being converted into monochromatic light having a specific wavelength of m, for example, 480 nm, the light passes through the measuring cell 40. The transmitted light that has passed through the measuring cell 40 is detected by a detector 45 and converted into an electric signal. The electric signal is input to an arithmetic unit 47 via an amplifier 46. The arithmetic result (transmittance T) is displayed on the meter display unit 4.
9 is directly input to the display unit 9 or converted into an absorbance A (A = −LogT) via a Log converter 48 and input to the meter display unit 49. In the meter display section 49, for example, FIG.
Are stored in advance, and the monovalent copper ion concentration corresponding to the detected transmittance T or the absorbance A is displayed.

The monovalent copper ion concentration in the solution thus measured by the measuring means 4 is
Is input to In the control means 5, an allowable range of the monovalent copper ion concentration in the solution is stored in advance as a set value, and the set value is compared with the input value of the monovalent copper ion concentration, and the valve is operated. 12, 22 and reducing agent supply means 25,
A control signal is output to the diluent supply means 33. For example, if the monovalent copper ion concentration is within the set range, the flow rate of the solution flowing from the reduction reaction tank 2 to the regenerating means 6 and the flow rate of the solution flowing from the waste liquid storage tank 1 to the reduction reaction tank 2 are increased. In this case, signals 51 and 52 are output to respective driving units (not shown) of the valve 12 and the valve 22.

When the monovalent copper ion concentration exceeds the set value, the amount of the solution flowing into the reduction reaction tank 2 and the amount Signals 51 and 52 are output to the respective drive units (not shown) of the valves 12 and 22 so as to suppress the outflow amount, and if necessary, the reducing agent is added so as to increase the amount of iron as a reducing agent. The signal 53 is output to the supply unit 25. Furthermore, when the monovalent copper ion concentration is high and measurement is difficult, a signal 54 is output to the diluting liquid supply means 33, and the sampling solution adjusting section 31 adjusts the dilution of the sampling solution.

That is, in the above-mentioned apparatus, the etching waste liquid during the reduction treatment in the reduction reaction tank 2 is continuously sampled, the monovalent copper ion concentration in the solution is detected, and based on the monovalent copper ion concentration. The amount of the etching waste liquid supplied from the waste liquid storage tank 1 to the reduction reaction tank 2 and the amount of the ferrous chloride solution supplied from the reduction reaction tank 2 to the regenerating means 6 are adjusted to reduce the waste liquid. In addition to controlling the residence time in the inside, the supply amount of iron as a reducing agent is controlled, thereby controlling the reduction process.

Therefore, according to the above embodiment, the copper ions in the etching waste liquid are reduced to monovalent copper ions, and the concentration of the monovalent copper ions is measured by an absorptiometric method. Since the total copper concentration in the inside is grasped, the concentration of residual copper ions in the etching waste liquid can be detected with high accuracy, quickly and continuously. In addition, even when the concentration of monovalent copper ions is low due to the addition of a coloring agent, the concentration can be accurately detected. As a result, the reduction process of the etching waste liquid is performed accurately and continuously.
This can be performed automatically and the concentration of copper ions in the processing solution can be made as low as possible, so that the quality variation in the final step is reduced and the copper recovery efficiency is improved.

In the above, in the present invention, the sampling means 3, the sampling solution adjusting unit 31, and the measuring means 4 are not limited to the configuration of the embodiment, and the adjustment of the sampling solution is performed in the sampling means 3 or the measuring cell 40. It is also possible to configure. Further, the measuring unit for measuring the absorbance is not limited to the configuration of the embodiment.

The present invention can be applied to, for example, a reduction treatment of an etching waste liquid of a cupric chloride etching liquid in addition to an etching waste liquid of a ferric chloride etching liquid.

[0030]

According to the present invention, the concentration of monovalent copper ions contained in the etching waste liquid after etching the copper with the etching liquid can be detected continuously, accurately and quickly. The control of the process of reducing the etching waste liquid based on the monovalent copper ion concentration is automatically and accurately performed, and the variation in product quality is reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an etching waste liquid processing apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a measuring unit according to the embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a relationship between absorbance A for monochromatic light having a wavelength of 480 nm and monovalent copper ion concentration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Waste liquid storage tank 12,22 valve 2 Reduction reaction tank 25 Reducing agent supply means 3 Sampling means 31 Sampling solution adjustment unit 33 Diluent supply means 4 Measurement means 5 Control means 6 Regeneration means

Continuation of the front page (56) References JP-A-53-103942 (JP, A) JP-A-59-1679 (JP, A) JP-A-4-66681 (JP, A) JP-A-4-157185 (JP) (A) JP-A-2-27663 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C23F 1/46 G01N 21/77 G01N 31/00 H05K 3/06

Claims (1)

(57) [Claims] 1. A reduction reaction tank for performing a reduction treatment by adding a reducing agent to an etching waste liquid obtained by etching a copper using an etching solution, and a sampling unit for sampling a solution in the reduction reaction tank. When the copper ions contained in the solution sampled by said sampling means, reduced to monovalent copper ions, the
Measuring means for measuring the transmittance of monochromatic light with respect to the solution and detecting the concentration of monovalent copper ions in the sampling solution based on the measurement result; and a coloring solution which selectively reacts with monovalent copper ions. And a sampling solution adjustment section for performing accurate concentration detection even when the monovalent copper ion concentration in the solution is low, and the copper ion concentration measured by the measuring means is higher than a predetermined value. A diluting liquid supply unit for diluting the sampling liquid when the temperature is high, and a control unit for controlling a reduction process of the solution in the reduction reaction tank based on a detection value from the measuring unit. An etching waste liquid treatment apparatus characterized by the above-mentioned.