CN113138215B - Copper ion concentration monitoring method - Google Patents

Abstract

The monitoring method of the invention comprises the following steps: providing a solution to be tested containing copper ions; providing a monitoring device; in a specific potential interval, determining a cyclic voltammetry curve of the solution to be detected by the monitoring device, wherein the cyclic voltammetry curve has a peak current value; providing a plurality of groups of standard solutions with known concentrations of copper ions, measuring cyclic voltammograms of the plurality of groups of standard solutions in the specific potential interval by the monitoring device, wherein the cyclic voltammograms of the standard solutions with each concentration have a peak current value, and determining a linear equation by the copper ion concentration values of the plurality of groups of standard solutions and the peak current values of the corresponding cyclic voltammograms, wherein the linear equation is y=ax+b, wherein Y represents the peak current value, a represents the slope of the linear equation, X represents the copper ion concentration, and B represents the intercept of the linear equation; and determining the copper ion concentration of the solution to be detected by using the linear equation and the peak current value of the cyclic voltammetry curve of the solution to be detected.

Description

Copper ion concentration monitoring method

Technical field

The present invention relates to a monitoring method for quantitatively measuring copper ion concentration by cyclic voltammetry.

Background technique

In the process of preparing liquid crystal display panels and printed circuit boards, it is often necessary to use various etching solutions to etch metal materials. The metal ions generated during the etching process will continue to accumulate in the etching solution. When the concentration of metal ions in the etching solution increases to a certain level, the etching solution will become unusable and become etching waste liquid.

Currently, there are two etching liquids widely used in industry: acidic copper chloride etching liquid and alkaline copper chloride etching liquid. The acidic copper chloride etching solution uses copper chloride as the copper etching agent, and uses an acidic oxidation system to regenerate the copper etching agent. Alkaline copper chloride etching solution uses the divalent copper ammonia complex Cu(NH ₃ ) ₄ Cl ₂ generated by the complex reaction of copper chloride and ammonia water as the copper etching agent, and reacts with oxygen, NH ⁴⁺ and Cl ^- , to regenerate the copper etching agent. As the etching proceeds, the copper on the plate will be etched to form monovalent copper Cu(NH ₃ ) ₂ Cl. Since monovalent copper is insoluble in water, the concentration of divalent copper gradually decreases with the etching time. As a result, the etching speed is affected.

In this field, the etching solution formulas used and the tolerable metal ion concentrations vary among manufacturers and industries. Take the etching solution used by some domestic thin film transistor liquid crystal display (TFT LCD) manufacturers as an example. When the concentration of copper ions in the etching solution reaches about 1000ppm, the etching solution loses its etching ability. , and the etching solution must be replaced with a new one. In addition, in the etching solution for copper etching used by some printed circuit board (PCB) manufacturers, the tolerable copper ion concentration is about 130g/L.

The general method to control the concentration of alkaline etching solution is to measure pH, hydrometer and temperature, but there is no intuitive way to monitor and measure the concentration of monovalent copper in the solution; in addition, chelating agents (such as EDTA) are also used in the existing technology. A chemical reaction is used to chelate copper ions to control the concentration of copper ions (Cu ²⁺ ) in the solution. However, it cannot accurately and quantitatively control the copper concentration, and has side effects such as contamination of the bath solution and heat generation, resulting in copper control. Ineffective, costly and potentially dangerous. In addition, the existing technology CN201686754U proposes an automatic control device for copper extraction. However, the automatic control device measures the copper ion concentration in the waste liquid through a specific gravity method. This method is suitable for small volume solutions and low concentrations (ppm) of copper. The sensitivity of ions is not high and there is still room for improvement.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a monitoring system for quantitatively measuring copper ion concentration by cyclic voltammetry.

The technical means adopted in the present invention are as follows.

In order to achieve the above purpose, the monitoring method of the present invention includes the following steps: providing a solution to be tested containing copper ions; providing a monitoring device; and using the monitoring device to measure a cycle of the solution to be tested within a specific potential range. A voltammogram curve, the cyclic voltammogram curve has a peak current value; a plurality of sets of copper ion standard solutions with known concentrations are provided, and in the specific potential interval, the cyclic voltammogram curves of the plurality of sets of standard solutions are measured by the monitoring device, each time The cyclic voltammogram curve of a standard solution with a concentration has a peak current value. A linear equation is determined based on the copper ion concentration values of the complex set of standard solutions and the peak current value of the corresponding cyclic voltammogram curve. The linear equation is Y= AX+B, where Y represents the peak current value, A represents the slope of the linear equation, The peak current value determines the copper ion concentration of the solution to be tested.

In a preferred aspect, the monitoring device has a receiving tank, which is equipped with a first-flow inlet and a first-flow outlet, and a working electrode, an auxiliary electrode, a reference electrode, an ampere meter and a voltmeter are arranged in the In the accommodation tank, the voltmeter is connected between the working electrode and the reference electrode, and has a connected power supply unit and a control unit. The power supply unit is electrically connected to the working electrode and the auxiliary electrode, and the ampere meter is Connected between the auxiliary electrode and the power supply unit.

In a preferred aspect, the working electrode and the auxiliary electrode may be platinum ring electrodes.

In a preferred embodiment, the reference electrode may be a saturated calomel electrode.

In a preferred embodiment, the specific potential range is 0.1-0.9 volts.

In a preferred aspect, the monitoring device is configured in an etching tank to continuously monitor the solution to be measured in the etching tank.

In a more optimal version, the value of A in this linear equation is 54.019 and the value of B is -0.4159.

Description of the drawings

Figure 1 is a schematic structural diagram of the monitoring device in the present invention.

Figure 2 is a structural perspective view of the accommodation tank in the present invention.

Figure 3 is a linear graph of peak current values corresponding to different standard solutions in the present invention.

Figure number description:

Monitoring device 1

Accommodation tank 10

Inlet 11

Outlet 12

Partition 13

Working electrode 21

Auxiliary electrode 22

Reference electrode 23

Power supply unit 30

Control unit 40

Amperemeter 51

Voltmeter 52.

Detailed ways

Please refer to Figure 1, which is a schematic structural diagram of the monitoring device in the present invention. The monitoring device 1 of the present invention at least includes: a receiving tank 10 , a working electrode 21 , an auxiliary electrode 22 , a reference electrode 23 , a power supply unit 30 , a control unit 40 , an ammeter 51 and a voltmeter 52 .

The accommodating tank 10 is equipped with a first-flow inlet 11 and a first-flow outlet 12. Please refer to FIG. The inner wall of the groove 10 and the other end are spaced apart from the inner wall of the accommodating groove 10. In the embodiment shown in the figure, three partitions 13 are provided to divide the accommodating groove 10 into a meandering donor flow channel. .

The working electrode 21, the auxiliary electrode 22 and the reference electrode 23 are arranged in the accommodating tank 10. The working electrode 21 and the reference electrode 23 are connected to a voltmeter 52, and the working electrode 21 and the auxiliary electrode 22 are partially exposed. The accommodating tank 10 is electrically connected to the power supply unit 30 . An ammeter 51 is connected between the power supply unit 30 and the auxiliary electrode 22 . The power supply unit 30 is electrically connected to the control unit 40 . The control unit 40 Under a predetermined voltage, the potential value is monitored by the voltmeter 52, and the change of the current value is monitored by the ammeter 51; wherein, the working electrode 21 and the auxiliary electrode 22 can be platinum ring electrodes, and the reference electrode 23 can be saturated calomel. electrodes, and in the embodiment as shown in the figure, the working electrode 21 and the auxiliary electrode 22 may be two rings located on the same round rod, while the reference electrode 23 is independently located on another round rod.

The monitoring method of the preferred embodiment of the present invention is explained by taking the measurement of alkaline etching liquid in the etching tank as an example. It specifically includes the following steps: taking an appropriate amount of the solution to be tested containing copper ions in the etching tank and placing it in the holding tank 10 . Through the monitoring device 1, a cyclic voltammetry scan is performed on the solution to be measured in the accommodation tank 10. The specific steps are: placing the working electrode 21, the auxiliary electrode 22 and the reference electrode 23 in the accommodation tank 10, and Contact the solution to be measured, set the specific potential range of the power supply unit 30 to 0.1 volts to 0.9 volts, turn on the power supply unit 30, scan cyclically within the potential range, and record the potential value of the working electrode 21 and its corresponding current. value, the control unit 40 synchronously draws a cyclic voltammogram curve according to the recorded data. In this embodiment, when the potential value of the working electrode 21 is between 0.1 volts and 0.9 volts, a wave peak will appear, and the peak current value Ip corresponding to the wave peak will be recorded.

Configure a plurality of sets of copper ion standard solutions with known concentrations, wherein the plurality of sets of standard solutions have different copper ion concentrations. The monitoring device 1 repeats the above voltammetric scanning steps for the plurality of sets of standard solutions under the condition of a potential scanning interval of 0.1 volts to 0.9 volts, and records the peak current values corresponding to the plurality of sets of standard solutions.

According to the copper ion concentration values of the plurality of standard solutions and their corresponding peak current values, it can be found that the copper ion concentration values of the plurality of standard solutions have a linear relationship with the peak current values of their cyclic voltammetry curves. Therefore, a linear equation can be determined based on the complex set of standard solution concentration values and the peak current value of the corresponding cyclic voltammogram curve. The linear equation is Y=AX+B, where Y represents the peak current value, A represents the slope of the linear equation, X represents the copper ion concentration, and B represents the intercept of the linear equation.

The peak current value of the cyclic voltammetry curve corresponding to the solution to be tested is substituted into the linear equation to determine the copper ion concentration of the solution to be tested.

In a preferred embodiment of the present invention, the standard solution is configured in the following manner: 100 ml of monovalent copper-free etching solution is added to five sealable plastic bottles, and 0.01, 0.05, 0.10, 0.15, and 0.20 grams of copper powder are added respectively. to the plastic bottle, and then seal the plastic bottle for 30 minutes to complete five sets of copper ion standard solutions with known concentrations. Repeat the above voltammetric scanning steps for the five sets of standard solutions, and record the corresponding values of the five sets of standard solutions. The peak current value is shown in Figure 3. (Note: The abscissa represents the five sets of standard solutions, and the ordinate represents the peak current value.)

From Figure 3, a linear equation can be obtained as Y=54.019X-0.4159. Then the peak current value of the cyclic voltammetry curve corresponding to the solution to be tested is substituted into the Y value in the linear equation to determine the copper content of the solution to be tested. The ion concentration, that is, the copper ion concentration of the alkaline etching solution in the etching tank can be known.

In addition, the monitoring device of the present invention can be directly configured and installed in the flow tank of an etching tank, using the inlet and outlet to form a flow with the flow tank, and continuously monitor the solution to be measured in the etching tank in real time, and further With a photoelectric sensor to count the number of boards passing through the etching tank, the monitoring method of the present invention can not only monitor the concentration of monovalent copper ions in the etching solution, but also use the photoelectric sensor to know the corresponding number of boards, thereby Controlling the production volume of panels can also control the addition and regeneration of alkaline etching solution, maintaining a stable etching speed to stabilize production quality.

Claims (5)

1. A copper ion concentration monitoring method, characterized in that it includes the following steps: Provide a solution to be tested containing copper ions; Provide a monitoring device, configured in an etching tank, to continuously monitor the solution to be measured in the etching tank. The monitoring device has a receiving tank, the receiving tank is equipped with a first-flow inlet and a first-flow outlet, and has a working An electrode, an auxiliary electrode, a reference electrode, an ammeter, and a voltmeter are arranged in the accommodation tank. The voltmeter is connected between the working electrode and the reference electrode, and has a connected power supply unit and a control unit. The power supply unit is electrically connected to the working electrode and the auxiliary electrode. The amperemeter is connected between the auxiliary electrode and the power supply unit. The working electrode and the auxiliary electrode can be two rings located on the same round rod. , and the reference electrode is independently located on another round rod; At least one partition is provided in the holding tank to divide the holding tank into a meandering liquid flow channel; Within a specific potential interval, a cyclic voltammogram curve of the solution to be measured is measured by the monitoring device, and the cyclic voltammogram curve has a peak current value; A plurality of sets of copper ion standard solutions with known concentrations are provided. In the specific potential interval, the cyclic voltammetry curves of the plurality of sets of standard solutions are measured by a monitoring device. The cyclic voltammetry curve of the standard solution of each concentration has a peak current value, so as to The copper ion concentration value of the complex set of standard solutions and the peak current value of the corresponding cyclic voltammetry curve determine a linear equation. The linear equation is Y=AX+B, where Y represents the peak current value and A represents the linear equation. The slope of the equation, where X represents the copper ion concentration and B represents the intercept of the linear equation; and The copper ion concentration of the solution to be tested is determined based on the linear equation and the peak current value of the cyclic voltammetry curve of the solution to be tested. 2. The copper ion concentration monitoring method according to claim 1, wherein the working electrode and the auxiliary electrode are platinum ring electrodes. 3. The copper ion concentration monitoring method according to claim 1, wherein the reference electrode is a saturated calomel electrode. 4. The copper ion concentration monitoring method according to any one of claims 1 to 3, characterized in that the specific potential range is 0.1 volts to 0.9 volts. 5. The copper ion concentration monitoring method according to any one of claims 1 to 3, characterized in that the A value in the linear equation is 54.019 and the B value is -0.4159.