JPH06240474A - Method and device for etching copper or copper alloy - Google Patents

Abstract

PURPOSE:To provide a method and device for etching copper or copper alloy capable of preventing the lowering of etching speed by detecting the fluctuation of etching speed of copper due to the lowering of the conc. of hydrogen peroxide or the contamination of the ion of a halogenated compound. CONSTITUTION:This device for etching copper or copper alloy by using an etchant containing sulfuric acid and hydrogen peroxide and applying a dipping potential detecting hydrogen peroxide replenishing system is constituted of an etching vessel 1 for storing the etchant, a dipping potential measuring instrument 2 for a material 5 to be etched in the etchant and a hydrogen peroxide replenishing device 3. And the dipping potential of a copper laminated plate 5 dipped in the etching vessel 1 is measured by an electrometer 7 based on a reference electrode 6 as a reference, a replenishing pump 9 is operated by a control device 8 based on the detected dipping potential value as controlling index and the hydrogen peroxide 12 is replenished into the etching vessel 1 from a hydrogen peroxide replenishing tank 10 through a supply pipe 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for etching copper or a copper alloy in an aqueous solution containing sulfuric acid and hydrogen peroxide as main components. TECHNICAL FIELD The present invention relates to a technique effective when applied to a copper or copper alloy etching method and apparatus capable of being etched by.

[0002]

2. Description of the Related Art Generally, in the process of manufacturing a printed wiring board, a method is used in which an etching resist corresponding to a circuit forming pattern is provided on a copper surface laminated on a substrate and copper other than the circuit is removed by etching. ing.

For example, for wet etching of copper,
Copper is etched by using a solution having a high solubility for copper and immersing the material to be treated in the solution or spraying the solution onto the material to be treated. Various aqueous solutions containing chloride or peroxide are used as the etching solution.

Among them, the sulfuric acid-hydrogen peroxide system solution makes it easy to recover copper from the etching solution and control the copper concentration in the solution by forming a closed cycle, and to appropriately consume the sulfuric acid and hydrogen peroxide solution. It has been widely used as an etching liquid for printed wiring boards because it has a feature that it does not require waste liquid treatment if it is replenished.

However, the sulfuric acid-hydrogen peroxide type etching solution also has a problem in controlling the liquid composition. One of them is that hydrogen peroxide, which is a liquid component, not only undergoes reductive decomposition due to oxidative dissolution of copper, but also self-decomposes due to catalytic action of copper ions, etc. There is a problem that the etching rate is significantly reduced.

As a method for solving this problem, a method of periodically analyzing the concentration of hydrogen peroxide in the etching solution and replenishing the hydrogen peroxide solution by determining the amount of consumption, and a phosphate for suppressing self-decomposition A method of adding a stabilizer such as the above to the etching solution, or a method of adding a catalyst such as palladium ion or platinum ion that promotes the etching reaction is adopted.

Further, in the sulfuric acid-hydrogen peroxide type etching solution, halide ion is another important factor for reducing the etching rate of copper. In particular, chloride ions are liable to be contained in industrial water or easily mixed into the etching solution as contaminant impurities, which may significantly reduce the etching rate.

As a method for solving this problem, conventionally, a method of using ion-exchanged water as water for constructing an etching solution or a method of adding silver ions into the solution and removing chloride ions by precipitation is adopted. Has been.

[0009]

However, the above-mentioned conventionally adopted liquid management methods also have various problems as described below.

For example, in the method of adding a catalyst for promoting the etching reaction, it is difficult to control the concentration of the catalyst, and the noble metal ions as the promoter are reduced and deposited on the etching surface, so that a uniform etching surface cannot be obtained. There is. Further, in the method of controlling and controlling chloride ions, a large amount of ion-exchanged water is required as water for use and washing water, and it is necessary to add expensive silver ions. As described above, in the conventional method, many problems may occur when the third component other than the main component of the etching solution such as sulfuric acid and hydrogen peroxide is added.

On the other hand, in the method of controlling the hydrogen peroxide concentration, when chloride ions are mixed in the etching solution, the reduction of the etching rate can be suppressed only by controlling the hydrogen peroxide concentration to a predetermined control value. It is difficult. From the above, it is desirable to detect the decrease in the etching rate of copper due to the mixture of chloride ions and the decrease in hydrogen peroxide concentration, and to prevent it without adding the third component.

Therefore, an object of the present invention is to detect fluctuations in the etching rate of copper due to a decrease in hydrogen peroxide concentration and the inclusion of halide ions such as chloride ions.
An object of the present invention is to provide a copper or copper alloy etching method and apparatus capable of preventing a decrease in etching rate.

Another object of the present invention is to provide a copper or copper alloy etching method and apparatus capable of removing halide ions without adding a halide ion removing agent such as silver ions to an etching solution. Is to provide.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0015]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows.

That is, the first copper or copper alloy etching method and apparatus of the present invention is a copper or copper alloy etching method using an aqueous solution containing at least sulfuric acid and hydrogen peroxide as an etching solution. Material or a material having the same composition as the material to be etched and a device for measuring the immersion potential, and a device for supplying hydrogen peroxide solution, and measuring the immersion potential of the material to be etched in the etching solution or the material having the same composition as the material to be etched The value is used as a control index to control the supply amount of hydrogen peroxide solution.

A second copper or copper alloy etching method and apparatus of the present invention is provided with a halide ion concentration measuring device and a hydrogen peroxide solution replenishing device, and the halide ion concentration in the etching liquid is Is measured, and a hydrogen peroxide solution having a concentration corresponding to the halide ion concentration is replenished.

Further, a third copper or copper alloy etching method and apparatus of the present invention is a device for measuring an immersion potential of a material to be etched or a material having the same composition as the material to be etched, and a function for fixing and removing halide ions. And a halide ion removing device having the above-mentioned. The halide ion is removed from the etching solution by using the immersion potential of the material to be etched or the material having the same composition as the material to be etched in the etching solution as a control index.

Further, a fourth copper or copper alloy etching method and device of the present invention comprises a halide ion concentration measuring device and a halide ion removing device having a function of fixing and removing halide ions. The halide ion is removed from the etching solution by using the measured value of the halide ion concentration in the etching solution as a control index.

[0020]

According to the above-described first copper or copper alloy etching method and apparatus, the fluctuation of the etching rate is detected by measuring the immersion potential of copper in the etching solution,
Since this immersion potential can be used as a control index to replenish the hydrogen peroxide solution that causes the fluctuation of the etching rate, it is necessary to prevent the etching rate from decreasing and perform etching of copper or copper alloy at a constant high etching rate. You can As a result, fluctuations in hydrogen peroxide concentration can be suppressed, the efficiency of the etching process can be improved, the dimensional accuracy of the material to be etched can be reduced, and the life of the etching solution can be extended.

Further, according to the second copper or copper alloy etching method and apparatus described above, a decrease in etching rate is predicted by measuring the halide ion concentration in the etching solution, and this halide ion concentration is a control index. Since it is possible to replenish the hydrogen peroxide solution that causes a decrease in the etching rate, it is possible to obtain a high level of etching without adding a halide ion remover such as silver ions to the etching solution as in the conventional case. It allows etching of copper or copper alloys at a rate.

Further, according to the above-described third copper or copper alloy etching method and apparatus, halide ions can be removed by using the immersion potential of copper in the etching solution as a control index, and therefore the same as above. It is possible to etch copper or a copper alloy at a constant high etching rate by suppressing fluctuations in the etching rate.

Further, according to the above-described fourth copper or copper alloy etching method and apparatus, the halide ion can be removed by using the halide ion concentration in the etching solution as a control index, and thus the same as above. It is possible to etch copper or a copper alloy at a constant high etching rate while suppressing a decrease in etching rate.

That is, in the sulfuric acid-hydrogen peroxide type etching solution, copper is dissolved by the reaction formula (1). The sulfuric acid and hydrogen peroxide are consumed as the etching progresses, and the concentration decreases.

Cu + H ₂ SO ₄ + H ₂ O ₂ → CuSO ₄ + 2H ₂ O (1) In addition to the formula (1), hydrogen peroxide is self-decomposed as in the formula (2) due to the catalytic action of copper ions and the like. To do. The copper etching rate decreases as the hydrogen peroxide concentration decreases, as shown in the characteristic diagram of the relationship between the etching rate and the hydrogen peroxide concentration shown in FIG.

2H ₂ O ₂ → 2H ₂ O + O ₂ (2) Therefore, a normal etching apparatus is provided with a mechanism for measuring and replenishing the concentrations of sulfuric acid and hydrogen peroxide in order to keep the etching rate constant. In addition, a stabilizer such as phosphoric acid is added in advance to the usual etching solution in order to prevent self-decomposition of hydrogen peroxide. Furthermore, in order to remove copper ions that accelerate the self-decomposition reaction of hydrogen peroxide, there is also an etching apparatus provided with a mechanism for cooling and removing the etching solution to recover and remove copper ions as copper sulfate crystals.

By using the etching solution and the etching apparatus having the above characteristics, the etching rate of copper can be kept constant, and only the hydrogen peroxide solution and the sulfuric acid are replenished, and the waste liquid treatment is unnecessary. Therefore, the operating cost can be kept low.

However, as can be seen from the relational characteristic diagram between the etching rate and the chloride ion concentration in FIG. 6, even if a small amount of chloride ions are mixed in the etching solution, the etching rate of copper is remarkably reduced.

This is because a cuprous chloride film is formed on the copper surface as in the formula (3), and this film suppresses the catalytic decomposition reaction of hydrogen peroxide that occurs on the copper surface. Therefore, it is not possible to prevent a decrease in the etching rate due to chloride ion mixing, simply by measuring the concentration of hydrogen peroxide or sulfuric acid and controlling the supply to a predetermined value.

2Cu + 2Cl ⁻ + H ₂ O ₂ + 2H ⁺ → 2CuCl + 2H ₂ O (3) Further, in order to prevent chloride ions from being mixed, deionized water is used as water for forming the etching solution, and before etching. As a treatment, it is necessary to wash the material to be treated with deionized water.

However, it is practically difficult to prevent chloride ions from being mixed into the etching solution from equipment components such as hydrochloric acid mist and polyvinyl chloride in the working environment. Therefore, even if chloride ions are mixed in the etching solution, it is necessary to take measures to prevent the etching rate from decreasing.

Therefore, as a method for preventing the decrease of the etching rate due to the mixing of chloride ions, a method of promoting the etching reaction by adding a catalyst such as platinum ion or increasing the hydrogen peroxide concentration, and a mixed chloride A possible method is to remove ions directly to prevent the etching rate from decreasing.

For example, the method of adding an etching reaction catalyst has problems that it is difficult to control the concentration of the catalyst, and noble metal ions, which are the catalyst, are reduced and deposited on the etching surface, so that a uniform etching surface cannot be obtained.

The method for increasing the hydrogen peroxide concentration is to increase the hydrogen peroxide concentration by an amount commensurate with the decrease in the etching rate which is decreased by the chloride ion as shown in FIG. It is excellent in that the speed can be controlled relatively easily.

As a method of efficiently adjusting the hydrogen peroxide concentration while suppressing the fluctuation of the etching rate, a method of detecting the etching rate of copper and using this detection signal as a control index to replenish the hydrogen peroxide solution, chloride Measure the product ion concentration,
There is a method of replenishing by obtaining the required amount of hydrogen peroxide using a characteristic diagram as shown in FIG.

The former method requires a change in the etching rate of copper to be directly or indirectly detected and converted into a control signal, and the latter method is conventionally used as a liquid control method. It is necessary to measure the chloride ion concentration in parallel with the measurement of the hydrogen peroxide concentration.

Further, the method of determining the etching rate of copper includes a method of directly determining the etching amount by measuring the weight reduction amount of the copper material by etching or the amount of copper ions dissolved in the etching solution, and the polarization of the copper material in the etching solution. There is a method of indirectly measuring the etching rate by measuring an electrochemical signal such as resistance or immersion potential.

Of these methods, the method of measuring the weight reduction amount is not suitable for automatic control because it requires manual work. Also,
As for the method of analyzing the copper ion concentration, continuous measurement and automatic control are possible if a copper ion sensor or spectroscopic analyzer is used.
It cannot be applied when copper ion is constantly collected and removed.

On the other hand, the method of detecting an electrochemical signal is as follows:
When the material to be treated is an electrode, the etching state can be continuously monitored, which is advantageous over other methods in that the liquid management with excellent responsiveness can be performed. The method of electrochemically monitoring the etching state includes a polarization resistance method and an immersion potential measuring method.

For example, the polarization resistance method is a method of obtaining polarization resistance by using two materials to be treated as electrodes and applying a minute voltage or current between the electrodes to measure the current or potential change flowing through the electrodes. . Since this polarization resistance has a value that is inversely proportional to the etching rate, it is possible to detect fluctuations in the etching rate from changes in the polarization resistance.

However, since the polarization resistance of the material to be etched in the etching solution is extremely small, if a minute voltage or current is applied for measurement, an excessive current will flow or the potential will fluctuate significantly and the etching state before and after the measurement. May change significantly.

On the other hand, the immersion potential method utilizes the fact that the potential of the material to be etched fluctuates depending on the change in the concentration of reactive chemical species such as hydrogen peroxide involved in the etching reaction or the surface condition of the etching surface. It is a method of monitoring.

For example, in the immersion potential method, a reference electrode such as a sweet potato electrode or a silver-silver chloride electrode is immersed in an etching solution in the vicinity of a material to be etched, and a potential difference between the reference electrode and the material to be etched is obtained. Is a measuring method for obtaining the potential of the material to be etched by measuring

In this potential difference measurement, if an electrometer having an extremely large input impedance is used, a current does not practically flow between the electrodes, so that the etching state does not change during measurement, and the polarization resistance is used as a monitoring method of the etching state. It is superior to the law.

When it is difficult to directly measure the immersion potential of the material to be etched at the time of etching, such as spray etching, a measuring cell filled with an etching solution is provided in the etching apparatus and the same composition as that of the material to be etched is provided. The state of the etching solution may be monitored by using an electrode and measuring the immersion potential of this electrode.

In this case, as shown in FIGS. 7 and 8, the immersion potential of copper decreases in the base direction due to the decrease in hydrogen peroxide concentration and the increase in chloride ion concentration. Further, when analyzed together with the relationship characteristic diagram between the etching rate of FIGS. 5 and 6 and the hydrogen peroxide or chloride ion concentration, there is a relationship that the immersion potential decreases as the etching rate decreases as shown in FIG. .

This is because the decrease in hydrogen peroxide concentration and the increase in chloride ion concentration both reduce the reaction rate of the decomposition reaction of hydrogen peroxide, which is a cathode reaction, so that the immersion potential is in the cathode direction, that is, the base potential. This is for shifting in the direction.

Therefore, if a characteristic relationship diagram as shown in FIG. 9 is obtained in advance, the etching rate can be obtained from the immersion potential of copper, and the immersion potential is used as a control index to replenish hydrogen peroxide solution and remove chloride ions. Liquid management such as operation can be automatically controlled.

That is, when the immersion potential decreases with a decrease in the concentration of hydrogen peroxide or a decrease in the etching rate of copper due to the mixing of chloride ions, the hydrogen peroxide solution is kept until the immersion potential returns to the normal value. If the mechanism for replenishing or removing chloride ions is activated, the etching rate of copper can be controlled to be constant without lowering.

When the immersion potential is controlled, it may be controlled to a potential corresponding to the etching rate set from the characteristic diagram of FIG. 9, but an etching rate of 0.5 Vm / min or more can be obtained at 0.3 V. (Standard hydrogen electrode control) It is preferable in terms of productivity to control the above.

Further, in addition to the method of controlling the etching rate by using the above-mentioned immersion potential as a control index, the concentration of chloride ion is directly measured, and an amount of hydrogen peroxide solution corresponding to the decrease in etching rate due to the incorporation of chloride ion is used. The method of replenishing is also excellent as a method of controlling the etching rate. Although there are various methods for measuring the chloride ion concentration, an ion selective electrode or an ion chromatography method is suitable for continuous automatic monitoring of the concentration.

If the mechanism for removing chloride ions is operated by using the measured chloride ion concentration as a control index, the etching rate of copper can be controlled to be constant without increasing the hydrogen peroxide concentration. You can in this case,
The chloride ion concentration has a small reduction in the etching rate.
It is preferably set to 01 mmol / l or less.

In order to remove the chloride ions, silver ions have conventionally been added to the etching solution for precipitation separation. However, this method has a problem in that expensive silver is consumed and unreacted silver ions are reduced and deposited on the copper surface to make the etching surface non-uniform.

As a chloride ion removing method other than the precipitation method, a selective ion separation method by an ion chromatography method using an ion exchange resin column, a chloride on a metal which forms a sparingly soluble chloride such as silver or lead, etc. A method of precipitating and fixing ions can be considered.

The former method is a method in which an etching solution is introduced into a column filled with an anion-selective ion-exchange resin, and a chloride ion concentrated solution that separates and flows out is separated and removed. However, this method is not suitable for processing a large amount of liquid. On the other hand, the latter method of fixing and recovering as hardly soluble chloride is similar to the precipitation method in principle, but it is possible to process a large amount of solution without leaving unreacted ions in the etching solution It is more advantageous than the law.

In this case, when the etching solution mixed with chloride ions is brought into contact with a metal such as silver which produces a sparingly soluble chloride, the silver surface is ionized by the oxidizing action of hydrogen peroxide as shown in formula (4). At the same time, the refractory chloride film is deposited by reacting with chloride ions.

2Ag + 2Cl ⁻ + H ₂ O ₂ + 2H ⁺ → 2AgCl + 2H ₂ O (4) Metals that produce this sparingly soluble chloride include silver, lead, and mercury.
There is copper, but silver is the most suitable in consideration of corrosion resistance and safety against etching solutions. However, if the film thickness of the poorly soluble chloride film is increased, the recovery efficiency is lowered, and there is a problem that the chloride film having low adhesion is peeled off.

Therefore, as a means for improving the recovery efficiency and the adhesion of the deposited film, an electrolytic current is caused to flow by using silver as the positive electrode in the etching solution, and a chloride film is formed on the surface of the positive electrode by the electrolytic reaction of formula (5). There is a method of analysis.

Ag + Cl ⁻ → AgCl + e ⁻ (5) The film formed by this electrodeposition has high adhesiveness, and since the electrolytic current is applied from the outside, the recovery efficiency does not decrease even if the deposited film becomes thick. . However, at the time of electrolysis, hydrogen peroxide is decomposed and consumed at the cathode as shown in formula (6).

H ₂ O ₂ + 2H ⁺ + 2e ⁻ → 2H ₂ O (6) Therefore, in order to suppress the decrease in the hydrogen peroxide concentration due to electrolysis, the chloride ion concentration is increased by mixing chloride into the etching solution. Alternatively, it is necessary to start the application of the electrolytic current when the etching rate is lowered, and stop the application when the normal value is restored.

That is, it is desirable to measure the immersion potential or the chloride ion concentration and automatically control the electrolysis operation using this value as a control index. Note that silver is suitable for the cathode material that is the counter electrode during electrolysis, considering the removal action during non-electrolysis.

As described above, if the hydrogen peroxide is replenished or the chloride ion is removed by using the immersion potential or chloride ion as a control index, the third component is not added to the etching solution at a constant rate. Copper can be etched quickly.

[0063]

Embodiment 1 FIG. 1 is a block diagram showing a copper or copper alloy etching apparatus which is an embodiment of the present invention, and FIG. 2 is a construction diagram showing a modification of the etching apparatus of this embodiment.

First, the structure of the etching apparatus of this embodiment will be described with reference to FIG.

The etching apparatus of the present embodiment is an etching apparatus for copper or copper alloy by the immersion potential detection hydrogen peroxide replenishment system using an etching solution containing at least sulfuric acid and hydrogen peroxide, and stores the etching solution. It is composed of an etching tank 1, an immersion potential measuring device 2 for the material to be etched in an etching solution, and a hydrogen peroxide solution replenishing device 3.

The etching bath 1 is filled with an aqueous solution of, for example, a mixture of sulfuric acid and hydrogen peroxide as an etching solution 4, and a copper-clad laminate 5 (material to be etched) provided with an etching resist pattern is immersed in the etching bath 1. The copper foil portion of the laminated plate 5 which is not covered with the etching resist is etched.

In the immersion potential measuring device 2, the etching bath 1 is used.
The immersion potential of the copper-clad laminate 5 dipped in is measured by the electrometer 7 with reference to the reference electrode 6 formed of, for example, a silver-silver chloride electrode or a sweet potato electrode.

The hydrogen peroxide solution replenishing device 3 operates the replenishing pump 9 by the control device 8 by using the potential value detected by the immersion potential measuring device 2 as a control index, and the hydrogen peroxide solution replenishing tank 10 to the supply pipe 11 are supplied. Through hydrogen peroxide 1
2 is replenished to the etching tank 1, and the liquid is managed so that the etching rate does not decrease.

Next, the operation of this embodiment will be described with reference to Table 1.

[0070]

[Table 1]

Table 1 shows an etching solution 4 (solution temperature 40 ° C.) prepared by mixing sulfuric acid and hydrogen peroxide, which is controlled by each method.
The results are obtained by immersing a copper-clad laminate 5 having a copper film thickness of 35 μm in an aluminum plate and performing an etching test.

For example, as in Conventional Examples 1 and 3 corresponding to a conventional etching apparatus, chloride ion was added to a sulfuric acid concentration of 1.5 mol / l and a hydrogen peroxide concentration of 1.0 or 0.5 mol / l. Liquid not containing (chloride ion concentration = 0 mmol
/ L) is 3.7 to 4.2 or 2.0 to 2.6 μm, respectively.
The result showing a high etching rate of / min was obtained.

However, when the liquid is managed by the conventional method of measuring the hydrogen peroxide concentration and replenishing it (conventional examples 2 and 4), it is 0 for the hydrogen peroxide concentration of 1.0 or 0.5 mol / l, respectively. In the case of a solution containing chloride ions with a concentration of 0.01 or 0.1 mmol / l, the etching rate is 1.8 to 2.
2. Remarkably decreased to 0.17 to 0.25 μm / min.

On the other hand, in the method of detecting the immersion potential of the copper-clad laminate 5 of the present invention and replenishing the hydrogen peroxide solution 12, the immersion potential lowered by the mixing of chloride ions is
In Inventive Example 1, the hydrogen peroxide concentration was changed from 1.0 mol / l to 3.0 m so that the electric potential became 0.35 V (standard hydrogen electrode control).
When it is increased to ol / l, it is possible to maintain an etching rate of 3.5 to 4.3 μm / min, which is similar to that when chloride ions are not mixed.

Therefore, according to the etching apparatus of this embodiment, the immersion potential measuring device 2 using the reference electrode 6 and the electrometer 7, the hydrogen peroxide using the control device 8, the replenishing pump 9, the hydrogen peroxide solution replenishing tank 10 and the like. With the water replenishing device 3 and the like, the immersion potential of the copper-clad laminate 5 in the etching solution 4 is measured by the electrometer 7, and the hydrogen peroxide solution 12 is adjusted so that the immersion potential becomes 0.3 V or more. By controlling the amount of replenishment of the gas through the control device 8, it is possible to suppress a decrease in the etching rate and perform etching while maintaining a constant high etching rate.

As shown in FIG. 2, the copper-clad laminate 5
Even when the immersion potential of the copper electrode 13 is measured with reference to the reference electrode 6 instead of, the immersion potential lowered by the incorporation of chloride ions becomes 0.3 V or more as in the invention example 2 of Table 1. By increasing the hydrogen peroxide concentration in this way, it is possible to maintain the same etching rate as that when chloride ions are not mixed.

[0077]

[Embodiment 2] FIG. 3 is a block diagram showing an etching apparatus for copper or copper alloy according to another embodiment of the present invention.

The etching apparatus of the present embodiment is, for example, an etching apparatus for copper or copper alloy by a chloride ion detection hydrogen peroxide replenishment system, and the etching solution 4 in which the copper-clad laminate 5 (material to be etched) is dipped is used. An etching tank 1 for storing, a halide ion concentration measuring device 14 in an etching solution 4, a control device 8, a replenishing pump 9, a hydrogen peroxide water replenishing tank 10, a hydrogen peroxide water replenishing device 3 by a supply pipe 11, and the like. The first embodiment is different from the first embodiment in that the hydrogen peroxide solution 12 is replenished by chloride ion detection instead of immersion potential detection.

That is, as shown in FIG. 3, the halide ion concentration measuring device 14 comprises a chloride ion selective electrode 1.
5 and an ion meter 16, a chloride ion selective electrode 15 is used to measure the chloride ion concentration in the etching solution 4 by the ion meter 16, and the hydrogen peroxide solution 12 is commensurate with the decrease in the chloride ion concentration. Is configured to be replenished.

Therefore, according to the etching apparatus of this embodiment, the chloride ion selective electrode 15 and the ion meter 1 are used.
The halide ion concentration measuring device 14 according to No. 6 is provided to measure the chloride ion concentration, and the hydrogen peroxide concentration corresponding to the decrease in the etching rate is shown in Table 1 (Example 3 of the present invention) of Example 1. From 0.5 mol / l to 8.0 m
By increasing to ol / l, it is possible to prevent the etching rate from decreasing and maintain a constant high etching rate as in the first embodiment.

[0081]

[Embodiment 3] FIG. 4 is a block diagram showing a copper or copper alloy etching apparatus which is still another embodiment of the present invention.

The etching apparatus of the present embodiment is, for example, an etching apparatus for copper or copper alloy by a chloride ion removal method for detecting immersion potential, and stores the etching solution 4 in which the copper clad laminate 5 (material to be etched) is immersed. Etching bath 1, a reference electrode 6 and an immersion potential measuring device 2 for a copper electrode 13 in an etching liquid 4 by an electrometer 7, and a halide ion removing device having a function of fixedly removing halide ions from the etching liquid 4. 17
And is different from Examples 1 and 2 in that chloride ions are removed using the immersion potential as a control index without replenishing the hydrogen peroxide solution 12.

That is, the halide ion removing device 1
7 has a function of applying an electrolytic current between the two electrode plates immersed in the etching solution 4 to deposit and remove halide ions as a sparingly soluble halide on the anode plate, as shown in FIG. Circulation pump 18, removal tank 19, electrolysis device 2
0, a silver electrode plate 21, and a circulation pipe 22.

Then, the etching solution 4 is supplied to the circulation pump 18
Is introduced into the removal tank 19 by using the measured immersion potential as a control index, the electrolysis apparatus 20 is operated, and after the chloride ions in the liquid are fixed and removed as silver chloride on the surface of the silver electrode plate 21, It is adapted to be returned to the etching tank 1 through the circulation pipe 22.

Therefore, according to the etching apparatus of the present embodiment, the halide ion removing apparatus 1 using the circulation pump 18, the removing tank 19, the electrolyzing apparatus 20, the silver electrode plate 21, and the like.
7 is provided, the immersion potential is detected, and chloride ions are electrodeposited on the silver electrode plate 21 without increasing the hydrogen peroxide concentration, as shown in Table 1 (Example 4 of the present invention) of Example 1. Chloride ion concentration from 0.01 mmol / l to 0.001 mm
By reducing it to ol / l, it is possible to prevent the etching rate from decreasing and maintain a constant high etching rate as in the case of Examples 1 and 2.

Although the invention made by the present inventor has been specifically described based on the first to third embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

For example, with respect to the etching apparatus of the above embodiment, the case of etching the copper foil portion of the copper clad laminate 5 provided with the etching resist pattern has been described, but the present invention is not limited to the above embodiment. Without
The present invention is also widely applicable to a laminated plate to which a copper alloy or the like is adhered or other materials to be etched made of the same composition material.

Further, in the second embodiment, the case of supplying the hydrogen peroxide solution 12 which corresponds to the decrease of the chloride ion concentration in the etching solution 4 has been described, but the same applies to other halide ions. It goes without saying that it is possible.

Further, in the third embodiment, the immersion potential measuring device 2 is replaced with a halide ion detecting halide ion removing system equipped with the same halide ion concentration measuring device 14 as in the second embodiment. By using the concentration as a control index and removing halide ions so that the concentration becomes, for example, 0.01 mmol / l or less,
Similarly, a decrease in etching rate can be suppressed.

Further, as a method of removing halide ions, it is also possible to bring a metal such as silver forming a sparingly soluble halide into contact with an etching solution and fix the halide ions on the metal surface for removal. Is.

In the above description, the invention mainly made by the present inventor is applied to the etching apparatus used in the manufacturing process of the printed wiring board, which is the field of use of the invention. However, the invention is not limited to this. The present invention is also widely applicable to etching devices for etching other materials made of copper or copper alloy.

[0092]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

(1). Detecting a change in etching rate by measuring the immersion potential of copper in the etching solution, or measuring the halide ion concentration in the etching solution to predict a decrease in etching rate, By replenishing the hydrogen peroxide solution with the immersion potential or the halide ion concentration as a control index, or by removing the halide ions, copper or copper alloy can be etched at a constant high etching rate. It is possible to improve the etching processing efficiency and reduce the variation in the dimensional accuracy of the material to be etched.

(2) By the above (1), it is possible to detect the fluctuation of the etching rate due to the decrease of the hydrogen peroxide concentration and the mixing of halide ions, so that the life of the etching solution can be extended. Alternatively, a copper alloy etching method and apparatus can be obtained.

(3) According to the above (1), a method or apparatus for etching copper or a copper alloy capable of removing halide ions without adding a halide ion remover to the etching solution as in the conventional case. Can be obtained.

(4) Due to the above (1) to (3), especially in the manufacturing process of the printed wiring board, the fluctuation of the etching rate is detected, and the quality and cost are excellent, and the copper is etched at a uniform rate. It is possible to obtain a copper or copper alloy etching method and apparatus capable of etching.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a copper or copper alloy etching apparatus that is Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram showing a modification of the etching apparatus of the first embodiment.

FIG. 3 is a configuration diagram showing a copper or copper alloy etching apparatus that is Embodiment 2 of the present invention.

FIG. 4 is a configuration diagram showing a copper or copper alloy etching apparatus that is Embodiment 3 of the present invention.

FIG. 5 is an explanatory diagram showing the effect of hydrogen peroxide concentration on the etching rate of copper.

FIG. 6 is an explanatory diagram showing the influence of chloride ion concentration on the etching rate of copper.

FIG. 7 is an explanatory diagram showing the effect of hydrogen peroxide concentration on the immersion potential of copper.

FIG. 8 is an explanatory diagram showing the influence of chloride ion concentration on the immersion potential of copper.

FIG. 9 is an explanatory diagram showing the relationship between the etching rate of copper and the immersion potential.

[Explanation of symbols]

 1 Etching Tank 2 Immersion Potential Measuring Device 3 Hydrogen Peroxide Replenishing Device 4 Etching Liquid 5 Copper Laminated Plate (Material to be Etched) 6 Reference Electrode 7 Electrometer 8 Controller 9 Replenishing Pump 10 Hydrogen Peroxide Replenishing Tank 11 Supply Pipe 12 Hydrogen Peroxide Water 13 Copper Electrode 14 Halide Ion Concentration Measurement Device 15 Chloride Ion Selective Electrode 16 Ion Meter 17 Halide Ion Removal Device 18 Circulation Pump 19 Removal Tank 20 Electrolysis Device 21 Silver Electrode Plate 22 Circulation Piping

Claims (17)

[Claims] 1. A method for etching copper or a copper alloy, which uses an aqueous solution containing at least sulfuric acid and hydrogen peroxide as an etching solution, the variation in the etching rate of the copper or copper alloy is detected, and the etching rate is kept constant. A method for etching copper or a copper alloy, which is characterized by controlling the etching speed. 2. The copper or copper alloy etching method according to claim 1, wherein when the etching rate is controlled to be constant, an immersion potential of the material to be etched or a material having the same composition as the material to be etched in the etching solution. A method for etching copper or a copper alloy, wherein the amount of replenishment of hydrogen peroxide solution is controlled using the measured value of 1. as a control index. 3. The copper or copper alloy etching method according to claim 1, wherein when the etching rate is controlled to be constant, the measured halide ion concentration in the etching solution is used as a control index. A method for etching copper or a copper alloy, which comprises supplying a hydrogen peroxide solution having a concentration corresponding to an ion concentration. 4. The copper or copper alloy etching method according to claim 1, wherein when the etching rate is controlled to be constant, the immersion potential of the material to be etched or the material having the same composition as the material to be etched in the etching solution. A method for etching copper or copper alloy, characterized in that halide ions are removed by using as a control index. 5. The copper or copper alloy etching method according to claim 1, wherein when the etching rate is controlled to be constant, the halide ion concentration in the etching solution is used as a control index to control the halide. A method for etching copper or a copper alloy, which comprises removing halide ions corresponding to an ion concentration. 6. The copper or copper alloy etching method according to claim 2 or 4, wherein the immersion potential as the control index is set to about 0.3 V or more in comparison with a standard hydrogen electrode. Etching method. 7. The copper or copper alloy etching method according to claim 3, wherein the halide ion concentration as the control index is about 0.01 mmol / l or less. Etching method. 8. A copper or copper alloy etching apparatus which uses an aqueous solution containing at least sulfuric acid and hydrogen peroxide as an etching solution, and detects fluctuations in the etching rate of at least the copper or copper alloy to detect the etching rate. An etching device for copper or copper alloy, comprising a detection / control device for controlling at a constant speed. 9. The copper or copper alloy etching device according to claim 8, wherein the detection / control device is a device for measuring an immersion potential of at least the material to be etched in the etching liquid or a material having the same composition as the material to be etched. And an etching device for copper or copper alloy, comprising: a hydrogen peroxide solution replenishing device. 10. The copper or copper alloy etching apparatus according to claim 8, wherein as the detection / control apparatus, at least a halide ion concentration measuring apparatus in the etching solution and a hydrogen peroxide solution replenishing apparatus are provided. An etching device for copper or copper alloy, comprising: 11. The copper or copper alloy etching apparatus according to claim 8, further comprising, as the detection / control apparatus, a halide ion removing apparatus having a function of fixing and removing halide ions from at least the etching solution. Characteristic copper or copper alloy etching equipment. 12. The copper or copper alloy etching apparatus according to claim 8, wherein the detection / control apparatus is an apparatus for measuring an immersion potential of at least the material to be etched in the etching solution or a material having the same composition as the material to be etched. And a halide ion removing device for removing halide ions from the etching solution. 13. The copper or copper alloy etching apparatus according to claim 8, wherein as the detection / control apparatus, at least a halide ion concentration measuring apparatus in the etching solution, and halide ions are removed from the etching solution. And an etching device for copper or copper alloys. 14. The copper or copper alloy etching apparatus according to claim 11, 12 or 13, wherein the halide ion removing device is a halide ion removing device in which a metal forming a sparingly soluble halide is brought into contact with an etching solution. An etching device for copper or copper alloy, characterized in that it uses a halide ion removing device having a function of fixing and removing metal on the metal surface. 15. The copper or copper alloy etching apparatus according to claim 14, wherein silver or a silver alloy is used as the metal for fixing the halide ions. 16. The copper or copper alloy etching apparatus according to claim 11, 12 or 13, wherein as the halide ion removing apparatus, an electrolytic current is applied between two electrode plates immersed in the etching solution. An etching device for copper or copper alloys, characterized in that a halide ion removing device having a function of electrodepositing and removing halide ions as a sparingly soluble halide is used for the anode plate. 17. The copper or copper alloy etching apparatus according to claim 16, wherein silver or a silver alloy is used as a material of an electrode plate constituting the halide ion removing apparatus. apparatus.