JPH01212774A - Method for maintaining and administrating power of alkaline etching liquid for copper or copper alloy - Google Patents

Abstract

PURPOSE:To maintain the total copper concn. in an etching liquid at a desired value by measuring the total copper concn. in the etching liquid by a concn. meter for which high frequencies are utilized and executing supply of a replenishing liquid and discharge of the etching liquid of the volume corresponding thereto. CONSTITUTION:The total copper concn. of the alkaline etching liquid for the copper or copper alloy in a sample vessel 3 is measured by a tuning circuit consisting of a high-frequency generator 1, a high-frequency coil 2 winding the outside circumference of the vessel 3 and a detecting meter 4 and by utilizing high frequencies. An additive circuit formed of a low-frequency AC current generator 5, an auxiliary coil 6 and a permanent magnet 7 is so provided that the synthetic magnetic field formed of a permanent magnet 7 and the auxiliary coil 6 intersects orthogonally with the magnetic field generated by the high-frequency coil 2 to increase the slight detection quantity (change quantity) generated in the tuning circuit. The change quantity of the measuring soln. detected by the detecting meter 4 is computed by an arithmetic circuit 8. The replenishing liquid is then supplied to the vessel 3 via an output circuit 9 and the etching liquid of the volume corresponding thereto is discharged.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a novel performance maintenance and management method for an alkaline etching solution containing cupric ions used for etching copper or copper alloys. Regarding.

More specifically, we accurately measured the increasing total copper concentration in an alkaline etching solution containing cupric ions in a non-contact and non-destructive manner using a densitometer that uses high frequency waves, and based on this measurement value. The present invention relates to a novel method for appropriately maintaining and managing etching solution capacity by controlling the total copper concentration to a desired value.

(Prior Art) At present, etching is one of the main processes in the manufacturing of printed wiring boards, in other words, the desired circuit parts of the copper foil laminated on the board are left and other unnecessary parts are removed. For etching, a so-called continuous etching method is employed in which the substrate is continuously fed into an etching processing apparatus.

Etching solutions (etchants) used in the above-described continuous etching method are broadly classified into acidic and alkaline ones. Compared to acidic etching solutions such as copper chloride, iron chloride, and ammonium persulfate, alkaline etching solutions have a smaller amount of side etching, less electrical corrosion caused by residual etching solution, and are suitable for use with solder (copper and tin) as etching resists. It is mainly used in the production of industrial wiring boards (for computers, communication equipment, high-end consumer equipment, etc.) because it can be used with aluminum alloys (alloys of

The alkaline etchant described above is generally an aqueous solution containing copper ions, an inorganic ammonium solution, and ammonium hydroxide as main components, and specifically, the copper ions are cupric tetraammine (Cu(NH3), +÷), Inorganic ammonium salts include ammonium chloride (Nl (4 cg), ammonium bicarbonate (llNH, c03), ammonium sulfate [
(NH, >, SO4) etc. are often used.

The etching mechanism and regeneration mechanism of the alkaline etching solution are as follows.

<Etching mechanism> Cu(NH,)4CQ□+Cu-+2Cu(NL)z(
Jt ++++++++++++++ [I] Regeneration mechanism> 2Cu(NH3)2(Q+2111H, CQ+2111
H, OH+2[0] (oxidation 亦D→2Cu(llIH,
), (4+2H, 0......(II) However.

[Oxidizing agent] is oxygen (02): NaClO2, Na
CQO2eNaCQO,,NH,C2O4,KCQO,
Chloric acid-based oxidizing agents such as Nal01. NaIO2,
Examples include iodic acid-based oxidizing agents such as KIO; percarbonate-based oxidizing agents; permanganic acid-based oxidizing agents.

That is, the tetraammine cupric ion acts on the surface of metallic copper (copper foil) to oxidize and solubilize it (ionize it to diammine cuprous ion) and elute it (reaction formula [I]).

In addition, since the etchant is always pressurized by a pump and sprayed from a nozzle in the etching equipment, cuprous ions are immediately oxidized by oxygen in the air or by the oxidizing agent added to the etchant in advance.
It restores and continues the solubilization and elution action of metallic copper repeatedly.

Therefore, in order to continue the cycle of solubilizing metallic copper and restoring cupric ions, the inorganic ammonium salt and ammonium hydroxide in the etchant are consumed (reaction formula [■]). In other words, the above reaction formula [11, (n)
As is clear from the above equation, in order to etch 1 mole of copper, theoretically 2 moles of ammonium chloride and 2 moles of ammonium hydroxide are required as etchants. disappears from within.

In addition, by spraying the etchant under pressure, ammonium hydroxide evaporates into the air independently of the etching reaction. Therefore, in order to maintain the performance of the etching system accurately and constant, it is necessary to adjust the state quantities of the etchant, namely copper ions, inorganic ammonium salts, and ammonium hydroxide.
), etc., and the concentration balance of each component must be detected and managed.

Note that the etching ability refers to the etching rate of copper, that is, the thickness of the copper foil on the substrate that is eluted and removed per unit time.

Focusing on the total copper concentration in the etching solution, we can see that metallic copper (C
u) is eluted as Cu+) and the total copper concentration ([Cu"+co+[Cu"l)] gradually increases in the etching solution due to the regeneration mechanism.

On the other hand, in the process control of etching treatment, as mentioned above, when the elution of copper or copper alloy into the etching solution progresses and the total copper concentration in the etching solution increases, the etching rate is reduced and production is reduced. Therefore, it is essential to control the total copper concentration to a desired value.

There are various methods for managing alkaline etching solutions containing cupric acid, as shown below, but none of them are fully satisfactory; (i) Management method using a float hydrometer and etching Indirect method of measuring liquid concentration.

A method of controlling the process using this float-type hydrometer is shown in, for example, Japanese Patent Publication No. 51-24988. However, there are problems with sensitivity speed, such as the need to use multiple float-type hydrometers to obtain the necessary data for process control.

Furthermore, when measuring the component concentration of the etching solution using a float type hydrometer, the measurement must be done indirectly, and the concentration components cannot be measured accurately and directly.

(ii) Electrochemical control method and concentration measurement method.

- When using a conductivity meter, the measurement range is narrow because the etching solution concentration is high, that is, the specific resistance (ρ) of the solution is small, and therefore the amount of change cannot be measured accurately. In addition, there are electrode corrosion, electrode contamination, etc., which cause errors and are not suitable for automatic management.

・When using an oxidation-reduction potential meter (ORP meter), the oxidation-reduction potential does not show the standard copper oxidation-reduction potential but shows an extremely small value because the copper alkaline etching solution produces a copper ammine complex. Management based on totals alone is insufficient.

- When using an ion-selective electrode meter, the copper amine complex is very stable and only a small amount dissociates into its constituent components, so accurate measurements cannot be expected.

(City) Management methods and concentration measurement methods using optical measurements.

- When using optical measurements, direct measurements cannot be performed because the alkaline etching solution has a unique dark blue hue. Even if the measurement solution is diluted or other coloring agents are applied, measurement is difficult using any method such as reflection, transmission, or colorimetry.

Particularly in recent years, performance requirements for printed wiring boards have become increasingly strict, and in particular, controlling the amount of side etch to a desired value has become important. As is well known, the amount of side etching increases as the etching process progresses, and as a result, the circuit width becomes narrower than the standard range, resulting in defective products. Therefore, the etching solution must be strictly controlled during continuous etching operations. There must be.

From the above, the management methods and means of the prior art described above have limitations, and an effective solution is awaited.

(Problems to be Solved by the Invention) The present inventors have made extensive studies to eliminate the drawbacks of the various conventional measuring meters described above. As a result, by interacting a tuned circuit containing a high-frequency oscillator with a permanent magnet wound with an auxiliary coil from a low-frequency alternating current generator, a non-contact, non-destructive and measurement accuracy is achieved. The present inventors have discovered that it is possible to obtain a densitometer that utilizes high frequency waves with excellent response speed, and that this densitometer is extremely effective in maintaining and managing the performance of alkaline etching solutions, leading to the completion of the present invention.

[Structure of the invention]

(Means for Solving the Problems) To summarize the present invention, the present invention provides a method for maintaining the ability of an alkaline etching solution containing cupric ions for etching copper or copper alloys. A concentration meter that uses high frequency to measure the total copper concentration in a liquid.
an additional circuit consisting of a permanent magnet wound around an auxiliary coil from a low-frequency alternating current generator, and a high-frequency coil from a high-frequency oscillator wound around a sample container for the measuring solution, which is produced by said permanent magnet. A tuned circuit including a high-frequency oscillator and a high-frequency coil installed in the magnetic field of the permanent magnet so that the magnetic field and the magnetic field created by the high-frequency coil are at right angles; - With a low-frequency alternating current applied to the auxiliary coil, A detector installed in the tuned circuit detects the amount of change occurring in the high frequency coil depending on the content of the measurement solution;
For use with copper or copper alloys, the etching solution is supplied with a replenisher based on the measurement results, and an amount of etching solution corresponding to the replenisher is discharged from the etching system to maintain the total copper concentration in the etching solution at a desired value. This paper concerns methods for maintaining and managing the capacity of alkaline etching solutions.

Hereinafter, the configuration of the present invention will be explained in detail.

First, a method for maintaining and managing the performance of an alkaline etching solution for copper or copper alloys according to the present invention will be outlined.

The performance maintenance and management of the alkaline etching solution of the present invention is carried out as follows.

1) Copper or a copper alloy is etched in a conventional spray etching machine with an alkaline etching solution containing cupric ions, inorganic ammonium salts, ammonium hydroxide, etc. as main ingredients.

2) Along with the etching reaction, the copper ion concentration in the etching solution increases and other components are consumed, causing a change in the balance of the etching solution components, that is, the state quantity. As a result, the etching ability fluctuates.

3) Among the changes in the state quantity of the etching solution, in the present invention, the total copper concentration is accurately detected by a densitometer using high frequency waves, and a replenisher for the etching solution is supplied via a pump that operates in conjunction with the densitometer. Replenish the etching solution to the standard state (
Return to target control value). On the other hand, the densitometer detects the point in time when the etching solution has returned to its normal state, and based on this, the pump for supplying the replenisher is stopped.

The present invention aims to constantly maintain and manage the etching ability of an alkaline etching solution by smoothly proceeding with the steps 1), 2), and 3).

Next, the configuration and features of a densitometer using high frequency, which is an important technical configuration in the performance maintenance and management method of an alkaline etching solution for copper or copper alloy of the present invention, will be explained.

The configuration of the densitometer using high frequency used in the present invention is as follows:
This is shown in the circuit diagram of FIG.

As shown in Fig. 1, the circuit system used in the present invention is the circuit system of the sample container
It consists of two circuits: a low-frequency alternating current generator ■ - an auxiliary coil 0 - a permanent magnet ■ (the magnet is wound by an auxiliary coil). Below, the above (i) and (ii)
) circuit system will be explained in detail.

A current is passed through the circuit system consisting of the output terminal (A) as shown in Fig. 2 to cause a voltage drop V.

On the other hand, the measurement terminals (A,
A variable capacitor C is connected in series to B) to form a series circuit. Now, tune the circuit by operating the variable capacitor C, and measure the terminal voltage Vc at this time with a voltmeter. If the value of the ratio of Vc/v is taken as the Q value, then if only the sample solution (alkaline etching solution) is changed while keeping other conditions constant, the amount of change in the Q value will be calculated according to the change in the components of the sample solution. can be detected. In FIG. 2, Le is the self-inductance of the coil, Re is the resistance, and Ce is the capacitor.

In other words, by inserting the sample container (■) filled with the solution sample to be measured into a part of the tuned circuit system (which may be a series circuit or a parallel circuit as an equivalent circuit) that includes the high-frequency oscillator (■), the measurement can be performed. When a change in properties (electrical conductivity, permeability constant, absorption of resonance energy, etc. of the solution) occurs in response to a change in the state of the solution (change in component compounds, change in ion concentration, etc.), an electric signal is generated from the electrical oscillator side. If you look at it, it appears as a change in Vc/v=Q value. The densitometer used in the present invention is based on the phenomenon that the Q value changes.

Next, what characteristics the tuned circuit system must have in measuring the Q value described above will be explained.

(b) When measuring by putting a sample solution, which is an alkaline etching liquid, into the sample container ■ wound around the high-frequency coil ■, the electrical circuit of the measurement system will consist of the equivalent circuit shown in Figure 3 ■. has been done. In FIG. 3, C2: Capacitance of the sample container C2: Capacitance of the sample solution R: Electrical resistance of the sample solution L: Inductance of the high frequency coil. For convenience of explanation, Figure 3 ■ shows the electrical characteristics of the sample solution by capacitance (
C2) and electrical resistance (R), the concept also includes characteristics due to resonance due to absorption of external energy. Therefore, this is considered to be sufficient as an explanation of the factor of variation in the Q value. In such a measurement system, L
Since and C1 are constant, the amount of electrical change corresponding to the change in C2 and R can be accurately captured. Furthermore, in the present invention, since a high frequency is used, C2 also hardly changes, so the amount of electrical change in this measurement system is R
will depend heavily on Therefore, let us assume that an electrolyte solution is used as a sample solution and its concentration is to be measured. In this case, when the heavy concentration is small, R is large, so the high-frequency current does not flow through R, but flows almost entirely through C2, so R can be ignored as shown in Figure 3. If R is ignored as in the following equation, the oscillation frequency f0 is expressed by the following equation.

(b) Next, as the electrolyte concentration increases, R becomes extremely small, so assuming that R=O, C2 can be considered to be short-circuited. In other words, as shown in FIG. 3, a circuit is created in which R and C2 are ignored, and the oscillation frequency f in this case is expressed by the following equation.

2πJLC This means that f does not depend on the concentration of the measurement solution and is determined only by L and C1.

In this case, in order to obtain the maximum value (maximum detected value) of the current flowing through the resonant circuit, the relationship between R and 01 must satisfy the following equation.

2πfC0R=1 That is, since C1 and R actually take small values in the above equation, it is understood that it is better to make f as high as possible.

Particularly, when measuring a highly concentrated electrolyte solution such as an etching solution, it is advantageous to use a high frequency because R takes an extremely small value, so that the measurement concentration range can be widened.

Through experiments by the present inventors, we have found that the higher the frequency, the more complete the electromagnetic shielding will be, otherwise the measurement values will vary, it will be uneconomical, and the handling will be subject to regulations such as the Radio Law. Considering several tens of MHz,
A frequency of 10 to 30 MHz is more preferable.

However, in the above-mentioned frequency band of 10 to 30 MHz, the amount of Q value detected in the tuned circuit system remains extremely weak.

The above-mentioned problems can be solved by a circuit (hereinafter referred to as an additional circuit) formed by the low-frequency alternating current generator 1, the auxiliary coil 0, and the permanent magnet 2 shown in FIG.

(ii) Regarding the circuit system including the low frequency alternating current generator■.

In order to improve the weakness of the Q value that occurs in the circuit system including the high-frequency oscillator (1) in (i), that is, the tuned circuit system, the present invention uses a strong magnetic field by the permanent magnet ■ and a weak magnetic field by the auxiliary coil 0 in the measurement system. A composite magnetic field with an alternating current magnetic field is applied.

That is, the sample container (circle), whose outer periphery is wound by the high-frequency coil (2) in the tuned circuit, is connected to the permanent magnet (2) and the auxiliary coil (3).
The high-frequency coil (2) is installed in the composite magnetic field so that the magnetic field produced by the high-frequency coil (2) is perpendicular to the composite magnetic field produced by the high-frequency coil (2).

This is as if it were an application of the principle of a speaker or receiver; the superposition of the magnetic field created by the permanent magnet (■) and the magnetic field created by the auxiliary coil (Q), through which a low-frequency alternating current flows, creates the tuned circuit of (i) above. This method utilizes the effect of increasing the weak detected amount (increasing the amplitude) generated by (using the mutual induction effect).

If we consider this at the level of chemical species in the measurement system, we get the following.

When the nuclear magnetic resonance of the nucleus of one chemical species placed in the measurement system is measured at a constant frequency, it is found that the magnetic field (magnetic field) that differs depending on the compound is equal to 1! Point B appears.

In atoms or ions, the electrons in their closed shells provide a magnetic field (diamagnetic field) that cancels out the outer magnetic tube (permanent magnet), but one demagnetizing field comes to be added to the magnetic field in the same direction as the external magnetic field. This is understood to be because the external magnetic field also polarizes the electron current distribution and induces a magnetic moment.

The present invention greatly increases the weak detection amount (change scene) that occurs in the tuned circuit including the high-frequency oscillator in response to changes in the measurement solution by setting an additional circuit including a low-frequency alternating current generator (c). This is based on the new knowledge that it is possible to perform densitometers with extremely high sensitivity and accuracy.

In the additional circuit including the low frequency alternating current generator 0, the low frequency alternating current generator is, for example, 10 to 100K.
Hz and an output voltage of 2 to 5 V are used. In addition, as a permanent magnet ■, for example, the magnetic flux (flux) is about 1,
000 Weber-1 magnetic flux density of approximately 4,000 terraces is used.

In the densitometer circuit diagram shown in Figure 1, the arithmetic circuit (■) connected after the detector converts the detected amount into linearity and logarithm, and converts the concentration of various components and electrical gradients and temperatures to indications. This is an electric circuit that compensates and corrects gradients, PH gradients, etc., and adjusts zero adjustment. Output circuit 0 indicates an electric circuit that obtains analog or digital measurement displays and control outputs. In addition, the detector (A) in Figure 1 uses the detection function to detect low-frequency signals from high-frequency signals, that is, in the tuned circuit system, and detects that the detected Q value changes according to changes in the state quantity of the measurement solution. The reason for this will be explained based on factors other than the capacitance (C2) and electrical resistance (R) of the measurement solution mentioned above. This will explain the measurement principle utilized by the present invention.

Every material has its own magnetic efficiency and angular motion.
When an external magnetic field is added to this, the direction of magnetic efficiency tends to match the direction of the external magnetic field. This is because potential energy is the smallest in this direction. The possible states of the magnetic efficiency of the nucleus of any material are determined by the spin inertia number (the magnitude of angular momentum), and the possible directions of the nuclear magnet are different. For example, protons have fixed directions such as 1/2, nitrogen 1, and chlorine 3/2. The magnetic energy between the core and the external magnetic field at these positions increases as the gradient with respect to the external magnetic field increases.

Therefore, in the atomic nuclei of a substance arranged as described above,
Furthermore, when a high-frequency magnetic field perpendicular to the external magnetic field is applied, the nuclear magnet is forced to vibrate by this high-frequency magnetic field.

Then, the nuclear magnet increases the frequency f such that the high-frequency magnetic field satisfies ΔE=hf, where ΔE is the difference in potential energy between any two allowed positions, and h is Boltzmann's constant. A phenomenon of transition between two states, that is, a resonance phenomenon occurs. In this case, the number of nuclei that transfer from a low energy position to a high energy position becomes greater than the number of nuclei that transfer from a high energy position to a low energy position. Therefore, if a large number of nuclei are considered, the average energy will be high, and the energy required for this will be supplied from the high frequency magnetic field.

In a tuned circuit system including the high-frequency oscillator (g) of the present invention, the frequency will shift due to the resonance phenomenon.

In other words, the energy of the electromagnetic waves between the high-frequency coils is consumed in the nuclear spin system (in other words, the energy level transition of the solution component that is the measurement sample), so the oscillation amplitude becomes slightly smaller (a type of amplitude modulation). As a result, as explained in FIG. 2, the Q value (=Vc/v value) decreases. The present invention attempts to determine the change in the state of the measurement sample by detecting this amount of change using a detector as a voltage value or a current value.

As described above, the present invention utilizes the resonance phenomenon of the nuclear spin system (transition of energy levels of solution components), so it accurately reflects the type of substance and changes in its components. This is because the energy difference ΔE between the states mentioned above is proportional to the strength H of the external magnetic field (ΔE=lif=aH), so f
This is natural considering that the relationship =kl+ can be obtained, and that the value of is a constant determined by the type of nucleus, and is determined by the magnetic efficiency and angular momentum of the nucleus.

To measure a measurement solution using the above-mentioned concentration meter using high frequency waves used in the present invention, it is sufficient to fill the sample container (2) with the measurement solution. The sample container (2) may be made of glass or plastic, but one with a constant dielectric constant may be selected and used, and it may be inserted into the high frequency coil (2) of the tuned circuit as shown in FIG.

Although FIG. 1 shows a mode in which the measurement solution is measured in a discontinuous manner, it goes without saying that the measurement can be carried out in a continuous manner.

To carry out continuous measurements, for example, the measurement solution is continuously extracted from a certain etching processing system, supplied into the sample container (■) from the lower inlet of the sample container (2), and then returned to the etching processing system through the upper outlet. You should do it. The measurement solution may be supplied to the sample container (2) at a desired supply rate, for example, from 1 to 5 Q/min, using a metering pump or a header tank.

In the present invention, the alkaline etching solution is continuously and non-destructively measured during the etching process using the above-mentioned concentration meter using high frequency, and based on the measurement results, the alkaline etching solution is measured. ability can be precisely controlled. As shown in the Examples below, the measured values correlate very well with the total copper concentration of the alkaline etchant. Therefore, for example, when the measured value of the concentration meter using the high frequency described above corresponds to a total copper concentration of 100 g#l, an electric signal is sent to start the replenisher supply pump to supply the replenisher into the etching machine.
When the measured value corresponds to a total copper concentration of 200 g/Q, the total copper concentration in the alkaline etching solution is controlled to the desired value by transmitting an electric signal to turn off the pump and stopping the supply of replenisher. can do. The control value for all 11VIa degrees is 100g# from the viewpoint of etching speed! ~20OgIQ, more preferably 10
0g/Q to 180g/12, more preferably 130g
/12 to 170g/Q should be set.

Incidentally, FIG. 4 shows an example of an apparatus suitable for continuously maintaining and managing the capacity of the alkaline etching solution described above. To carry out the present invention, the currently used continuous spray etching machine (10) may be equipped with the above-mentioned densitometer (12) that utilizes high frequency waves, as shown in FIG.

The alkaline etching solution (13) during the etching process is sucked up through the pipe (14a) by the operation of the pump (Pl) and is sprayed toward the plate to be processed (16) through the spray nozzle (15). At this time, a part of the etching liquid is sent to a concentration meter (12) that uses high frequency waves, and the etching liquid that has been detected by the same device is sent to an etching liquid tank (17) via a pipe (14b). be returned.

This concentration meter (12) continuously detects the total Cu concentration value of the etching solution, and when the total Cu concentration value exceeds the reference value, the electric signal from the concentration meter (12) activates the pump (P2). The pipe (14) runs from the replenisher tank (18).
c) The etching liquid tank (17) is replenished with a replenisher.

As a result, the concentration meter (12) shows that the total Cu concentration of the etching solution has decreased to the reference value by replenishing the replenisher.
When detected, the operation of the pump (P2) is stopped and replenishment of the replenisher is stopped.

In order to maintain a constant amount of etching liquid (13), an overflow port (19) is provided in the etching liquid tank (17).
), and when the etching liquid (13) exceeds a certain amount due to replenishment, it is automatically transferred to the etching liquid tank (13).
17) and stored in a drainage tank (20).

The etching liquid tank (17) is equipped with a temperature control mechanism (11) for controlling the temperature of the etching liquid, that is, a temperature sensor (lla).
, a heater (Ilb), and a cooling pipe (11c) are provided,
It is possible to maintain and manage the desired liquid temperature.

The concentration meter of the present invention is capable of measuring (or detecting) changes in state quantities in a non-contact manner without contacting the measurement solution of any component, and in a non-destructive manner without sampling. It is possible to measure (detect) the amount of change in state quantities in a process line, and there is no time lag or error, enabling rational process control management, high productivity, quality control, etc.

〔Example〕

The present invention will be explained in more detail below based on Examples, but the present invention is not limited to these Examples unless the gist of the present invention is exceeded.

(Example 1) First, an experiment was conducted to examine the effectiveness of the densitometer using high frequency according to the present invention. As a criterion for evaluating its effectiveness, we decided to evaluate it by looking at the correlation with the float type hydrometer.

■ Regarding the configuration of a concentration meter that uses high frequency (see Figure 1) (i) Measuring container - Made of Pyrex glass, 180 (Q) x 50 (
φ)×1(t) and a volume of approximately 3,501 liters was used.

- A measurement solution inlet was provided at the bottom of the measurement container and a measurement solution outlet at the top to enable continuous measurement, and a temperature sensor was also installed.

(ii) Liquid passing conditions The measurement solution was passed through at a rate of 3.9 fi/min using a metering pump.

(iti) Electrical conditions/High frequency coil: A 1 (φ) enamelled wire was loosely wound around the measurement container 10 times.

・High frequency oscillator...Oscillation frequency 27MHz ・Alternating current generator...20KHz, output 2V ・Detector...Detect using a voltmeter, output 0 to 5V to the output circuit, and output 0 to 10V. Made it correspond to the scale (meter indication).

(2) Measurement method and results The total steel (Cu) concentration of the alkali etchant during the manufacture of printed wiring boards was measured using the densitometer configured as described above. The alkaline etchant is N)1. OH/
This method oxidizes and elutes copper using a solution containing NH4CQ/Cu".
All C of (cupric) and Cu” (cuprous)
The u concentration gradually increases. In order to maintain an appropriate etching rate, the total Cu concentration ([Cu”) + (
Cu'') must be accurately maintained within a predetermined range, for example, 140 to 160 g/Q, while supplying a replenishing solution. occupies the majority.

Figure 5 shows the results of measurements taken at 20°C and 50°C at pH=10. The measurement results obtained by the densitometer using high frequency according to the present invention showed extremely high correlation with those obtained by the float type hydrometer, and were confirmed to be effective.

(Example 2) In connection with Example 1, an experiment was conducted to determine whether the concentration meter using high frequency according to the present invention is effective in controlling the total Cu concentration in the alkaline etchant when manufacturing pudding 1 to wiring boards continuously. .

The densitometer used in Example 1 was equipped with an etching liquid bath (liquid temperature 5.
0' ±10°C) to alkaline etchant (N11
4011/N114CN/Cu" child thread, etc.), and as a management target point for the total Cu concentration: Upper limit 160 g/Q, measurement device reading 7.75, lower limit 150 g/L measuring device reading. 4.5, the electric signal based on this actuated the replenisher supply pump to supply replenisher (Ni+4011 system) to the etching liquid tank, and the amount commensurate with this supplied amount was discharged from the etching liquid tank. In addition, in a normal alkali etching operation containing Cu++, the generated Cu+ is oxidized to Cu++ by oxygen or an appropriate oxidizing agent, so a replenisher that does not contain Cu''+ is used. Furthermore, when the indicated value reached 4.5, the replenisher supply pump was stopped to stop supplying the replenisher.

The results are shown in Figure 6. It can be seen from FIG. 6 that the concentration meter using high frequency according to the present invention is extremely effective in controlling the total Cu concentration in the alkaline etchant during continuous operation.

〔Effect of the invention〕

What is the concentration meter using high frequency, which is a new measurement means applied to the performance maintenance and management of the alkaline etching solution for copper or copper alloys of the present invention? 111 It is possible to perform non-contact measurements without coming into contact with the constant solution, and it is possible to measure the amount of state change in the process line non-destructively without sampling, and it is excellent because there is no time lag or error. It has characteristics. Therefore, by using the densitometer using high frequency, the alkali etching process of copper or copper alloy can be rationally controlled, and high productivity and quality can be achieved.

[Brief explanation of the drawing]

FIG. 1 shows a circuit diagram of a densitometer using high frequency according to the present invention. FIG. 2 is an explanatory diagram of the Q value of the tuning circuit that constitutes the concentration if of the present invention. FIGS. 3-3 are equivalent circuit diagrams of a part of the tuning circuit constituting the densitometer of the present invention. Fourth
The figure shows a schematic diagram of an example of a device suitable for carrying out the method of the invention. Figure 5 is a graph showing the results of measuring the total CufA in an alkaline etchant using the densitometer of the present invention, and Figure 6 shows the results of measuring the total CufA degree in an alkaline etchant using the densitometer of the present invention. - The graph shows the results when applied to the management of total Cu1 degree in etchant. 1...High frequency oscillator 2...High frequency coil 3.
... Sample container 4 ... Detector 5 ... Low frequency alternating current generator 6 ... Auxiliary coil 7 ... Permanent magnet patent applicant Yoshio Mizuno, agent, patent attorney, Yamatoya Shokai Co., Ltd. Figure 1 Figure 2 Figure 3 (PH=10.20'C, 50'C)

Claims (1)

[Claims] 1. A method for maintaining and managing the ability of an alkaline etching solution containing cupric ions for etching copper or a copper alloy, wherein the total copper concentration in the etching solution is determined by using radio frequency. The total copper concentration in the etching solution is maintained at a desired value by supplying a replenishing solution based on the measurement results and discharging an amount of etching solution corresponding to the replenishing solution from the etching system. How to maintain and manage the capacity of alkaline etching solutions for copper or copper alloys. 2. A densitometer that uses high-frequency waves: ●An additional circuit consisting of a permanent magnet wound around an auxiliary coil from a low-frequency alternating current generator; ●High-frequency waves from a high-frequency oscillator wound around a sample container for measuring solution. A tuning circuit including a high frequency oscillator and a high frequency coil installed in the magnetic field of the permanent magnet so that the magnetic field created by the permanent magnet and the magnetic field created by the high frequency coil are at right angles; A detector provided in the tuned circuit, which detects the amount of change that occurs in the high-frequency coil depending on the content of the measurement solution when an alternating current is applied. How to maintain and manage the capacity of alkaline etching liquid for copper alloys. 3. The method for maintaining and managing the capacity of an alkaline etching solution for copper or copper alloys according to claim 1, wherein the total copper concentration in the etching solution is continuously measured using a concentration meter using high frequency. 4. The method for maintaining and managing the capacity of an alkaline etching solution for copper or copper alloys according to claim 1, wherein the total copper concentration is maintained at 100 g/l to 200 g/l. 5. The method for maintaining and managing the capacity of an alkaline etching solution for copper or copper alloy according to claim 1, wherein the high frequency oscillator generates a high frequency of 10 to 30 MHz. 6. The method for maintaining and managing the capacity of an alkaline etching solution for copper or copper alloy according to claim 1, wherein the low frequency alternating current generator generates an alternating current of 10 to 100 KHz. 7. The method for maintaining and managing the capacity of an alkaline etching solution for copper or copper alloys according to claim 1, wherein the alkaline etching solution contains cupric ions, an inorganic ammonium salt, and ammonium hydroxide. 8. The method for maintaining and managing the capacity of an alkaline etching solution for copper or copper alloys according to claim 1, wherein the replenisher contains an inorganic ammonium salt and ammonium hydroxide.