JPS591679A - Controlling and administering method of etching solution - Google Patents

Abstract

PURPOSE:To administer and control the concn. of the compsn. of a copper chloride etching soln. so as to stabilize the rate of etching, by detecting directly the concn. of the hydrochloric acid in said etching soln. and replenishing the hydrochloric acid in said etching soln. in accordance with the preset concn. of the hydrochloric acid. CONSTITUTION:Part of the above-described etching soln. is removed to the outside of the system from an etching device provided with an etching bath, a detection bath, a regeneration bath, etc. in the stage of regenerating the etching soln. by adding hydrochloric acid and H2O2. The soln. is diluted by using a soln. of a specified concn. prepd. from an aq. soln. of 0.01-100g/gl alkali of NaOH or the like or water, and the concn. of the hydrochloric acid is detected continuously or intermittently. A soln. of a specified concn. prepd. from an aq. soln. of 10-200g/l alkali is used as the alkali to be used in titration for the purpose of said detection. Water or hydrochloric acid is replenished to a part of said etching device in accordance with the preset range of the concn. of the hydrochloric acid to control the concn. of the hydrochloric acid in the etching soln. As a result, the variance in the concn. of the hydrochloric acid in the soln. is reduced, the balance between H2O2 and the hydrochloric acid is maintained to be constant and the stable etching is accomplished for a long period of time.

Description

[Detailed Description of the Invention] The present invention relates to a method for controlling and managing a copper chloride etching solution, and a method for effectively controlling and managing an etching solution so that copper-clad laminates and the like can be etched efficiently and with high precision. Pertains to.

Conventionally, when etching copper and copper alloys, a cupric chloride solution is often used as an etching solution. It is important to keep the composition and concentration of the etching solution constant to avoid sudden changes in the etching rate. These are copper concentration, cupric chloride concentration, hydrochloric acid concentration, and hydrogen peroxide concentration.

Conventionally, as a method to control these concentrations, the concentration of cuprous chloride was detected using an OF2 meter, a potentiostatic electrometer, or a colorimeter.
Hydrogen peroxide and regeneration theoretical amount of hydrochloric acid are directly added to the etching tank or regeneration tank in proportion to the hydrogen peroxide replenishment amount +71f.
ic supplementation L, and the concentration of cupric chloride was detected with a hydrometer and generally controlled by supplementing with water or hydrochloric acid. In this way, conventionally, control and management has been carried out by detecting only the concentrations of cupric chloride and cupric chloride in the liquid.

However, with such control and management methods, the concentration of hydrochloric acid in the etching solution cannot be directly detected, and the balance between the hydrogen peroxide and hydrochloric acid that is replenished is likely to be lost, making it difficult to obtain a constant concentration of hydrochloric acid. It had the disadvantage that it could not be easily maintained and etched. Particularly in recent years, the concentration of free hydrochloric acid has been reduced from 2 to 2 to increase the etching rate and productivity.
#L is often used as a high hydrochloric acid concentration of about 6 mol/1. For example, if the amount of processed printed circuit boards or the density of circuit patterns changes, the rate of consumption of hydrochloric acid due to air oxidation as a side reaction will change, and the concentration of hydrochloric acid in the bath will change. When the etching rate varies from 2.5 mol/min to 4.5 mol/min, the etching rate increases to 28 mol/min.
It varies from μm/min to 50 μm/min. As described above, the etching rate varies greatly due to changes in the hydrochloric acid concentration, which has become a major problem.

In order to eliminate the above-mentioned variations in etching speed and to perform etching with high precision, the inventors of the present invention have conducted various studies on methods for controlling the composition and concentration of the etching solution, and have directly detected the concentration of hydrochloric acid in the etching solution. Through this, we discovered a method to manage and control the concentration of liquid composition.

That is, the present invention involves adding hydrochloric acid and hydrogen peroxide to a copper chloride etching solution to regenerate it.
A portion of the etching solution is extracted from the etching device equipped with a detection tank, a ladle tank, etc., the solution is diluted with water or alkaline water, and the hydrochloric acid concentration of the solution is detected continuously or intermittently. This method of controlling and managing an etching solution is characterized in that the concentration of hydrochloric acid in the etching solution is controlled by replenishing a part of the etching apparatus with water or hydrochloric acid in accordance with a set hydrochloric acid concentration range.

According to the method of the present invention, variations in the concentration of hydrochloric acid in the etching solution are reduced, the balance between hydrogen peroxide and hydrochloric acid can be maintained constant, and stable etching can be performed over a long period of time.

In the method of the present invention, when responding and controlling according to the instructions from the DH meter, the dilution magnification should be 2 to 2, taking into account that the HCp concentration in the hunting etching solution is 1 to 6 mol/4 and the characteristic f1 of the pH meter. 200 times, preferably 5 to 100 times. This ensures that the pH during measurement is within ±0.03.
In addition, the sampling error can be kept within ±5%, and the HC-eI 11 degrees in the etching solution can be kept within ±5% of the set value.
It is possible to manage within

On the other hand, if the titration method is not suitable, the HC-g concentration in the etching solution can be adjusted to ±5 of the set value by controlling the sum of alkali sampling errors and titration errors due to batch operations to ±596#.
% and can be applied even if the temperature is set, but in order to reduce errors due to temperature changes in the detection liquid, it is necessary to maintain constant temperature conditions by using a temperature compensation electrode or a constant temperature bath. It is preferable to measure as . For example, potentiometric titration using a pH meter or temperature titration using a thermistor can be applied to the titration method.

Water or alkaline water is used as the diluent. Alkaline water is from 0.01 to caustic soda, caustic potash, carbonated soda, etc.
A constant concentration aqueous solution of i o o f/43 is used.

When using an alkaline aqueous solution, equipment such as dilution measuring tanks and pumps can be made smaller, and the dilution ratio can be as low as 2 to 50 times, reducing sampling errors and measurement errors. The alkali used is caustic soda, caustic potash,
A constant concentration solution of 10 to 200 fl/-8 of an aqueous solution such as soda carbonate is used.

The hydrochloric acid concentration of the etching solution may be detected at any location from the time it is discharged from the etching tank until it enters the regeneration tank, or from the regeneration tank until it enters the etching tank. In order to properly detect the aging state of the etching solution, it is preferable to detect the solution discharged from the etching tank.
When finely adjusting the hydrochloric acid concentration suitable for etching, it is preferable to detect it during the process from the regeneration tank to the etching tank. When detecting the concentration of the liquid from the etching tank until it enters the regeneration tank, it can be carried out continuously, but when detecting it during the process from the regeneration tank to the etching tank, it is possible to detect the concentration of the liquid in the liquid to be detected. Since a considerable amount of hydrogen oxide is contained, air bubbles are generated and sampling errors are likely to occur. Therefore, if hydrogen peroxide in excess of 30 ppm is present, it is preferable to perform one scrubbing so as to detect it intermittently.

In addition, when performing temperature titration, the liquid discharged from the etching tank located between the moss etching tank and the regeneration tank is detected. Hydrochloric acid for replenishment may be added to any part of the etching apparatus, but it is generally added to the regeneration tank or the etching tank.

When carrying out the method of the present invention, specifically, a solenoid valve is installed in a shuttle in which hydrochloric acid is automatically added at a predetermined sound from a hydrochloric acid bath to an etching solution in response to an indication of a pH value or a potential value or a titration value.
The automatic method of the present invention, which operates a chamber pump, a timer, etc., detects the cuprous chloride concentration using a conventional ORP meter, potentiostatic electrometer, or colorimeter, and detects peroxide. When replenishing hydrogen, in addition to the method of replenishing a fixed amount of hydrochloric acid in proportion to the amount of hydrogen peroxide replenishment, the method of the present invention allows replenishment of finely controlled amounts of hydrochloric acid and water. It is also possible to replenish hydrogen peroxide using an ORP meter, potentiostatic electrometer, or colorimeter, and to replenish hydrochloric acid separately using the method of the present invention.

As described above, according to the uninvented method, only the concentration of hydrochloric acid can be directly and accurately detected without being affected by the concentrations of cupric chloride, cuprous chloride, and hydrogen peroxide in the copper chloride etching solution.
Controlled and uniform etching can be achieved.

Next, the method of the present invention will be explained using examples.

Example 1 CuC-g22mol/4, CuC,80,01(-ru/
13, H (a spray-type etching machine that circulates and uses an etching solution with a composition of 13 mol/13 and is equipped with a regeneration tank (equipped with etching solution t36o4. Circulation port 11400A)
/min) with a pH electrode (including control and compensation), a stirring device, and a diluent and stock solution inlet at a pH of 10 Oat.
The etching solution was continuously drawn out at a flow rate of 2*//min from a bypass provided in a part of the etching solution circulation path in the measuring tank, and at the same time, tap water for dilution was continuously drawn out at a flow rate of 30 mt/min. Then, supply it to the pH measuring tank.

(Before operation, the electrodes were calibrated and the pH meter was calibrated by flowing an etching solution with a known concentration.)

A single-sided phenolic resin copper-clad laminate (Cu foil) was prepared using a device that was constructed so that the pH meter and the replenisher insertion solenoid valve were linked so that the pH of the liquid was controlled at 1.30±0.02 using the output of the pH meter. 35μm11) (Total 800m2
) etching at 50℃±1℃, spray pressure 1.3k
F! The test was carried out at a speed of 4 m/min for 8 hours.

As a result, the pH fluctuation was small and the etching rate was uniform ((!), and no etching defects occurred at all.

Figure 1 shows the changes over time in the hydrochloric acid concentration and pH in the solution in this case.

For comparison, changes in the concentration of hydrochloric acid in the conventional detection method are also shown.

Example 2 A part of the etching solution circulating in an etching machine using an etching solution having the same composition as in Example 1 was intermittently extracted 4 times, mixed and diluted with 150 mg of water, and the pH was measured. Similar to Example 1, a solenoid valve for supplying hydrochloric acid or water was operated based on the detected pH indication value to replenish hydrochloric acid or water. Intermittent extraction is 1 cycle 5
I did it in minutes. According to this control method 1, copper-clad laminates (8021112 in total) were etched for 8 hours under the same conditions as in Example 1, but the variation in hydrochloric acid concentration was within ± of the set value.
496, and a consistent etching finish was achieved.

Example 3 Using an etching solution having the same composition as in Example 1, in an etching machine equipped with an etching tank and a regeneration tank and in which the etching solution circulates, the circulating etching solution was intermittently 4#j/
The solution was extracted twice, mixed with 1 somtrr NaOH water, diluted, and the pH was measured. Set the pll setting value to 4,
-0 (neutralization point of HC-g), and when it is higher than that, the solenoid valve installed in the replenishment water tank is opened, and conversely, when it is 4.0 or less, the solenoid valve of the replenishment hydrochloric acid tank is opened. . Using this control method, a copper-clad laminate (t1801m2) was etched for 8 hours, and the variation in hydrochloric acid concentration was within ±396 of the set value, making it possible to perform consistent etching.

Example 4 Consisting of an etching solution with the same composition as Example 1,
5 tnl of the etching solution was intermittently extracted from an etching machine similar to that used in , and titrated with a KOH aqueous solution of % standard using a temperature titration device using a thermistor. Just as the solenoid valve for the water tank that is refilled opens when the measured value exceeds the set value, the solenoid valve for the hydrochloric acid tank that refills opens when the measured value falls below the set value. Using this control method, a copper-clad T# layer board (802 m2 in total) was etched for 8 hours, and the one-degree variation was within ±5% of the set value, and consistent etching was achieved.

Comparative Example 1 A conventional etching machine (ORP meter and hydrometer control system) that circulated an etching solution having the same composition as in Example 1 was used under the same conditions as in Example 1.
795 m2) was etched for 8 hours.

After 3 hours had passed, the hydrochloric acid concentration reached 2.6 mol/blade, and etching began to become insufficient. When etching was carried out by changing the f ratio of hydrogen peroxide to hydrochloric acid in the replenisher from 1:2.4 to 1:2.8 based on H2O2 concentration detection, over-etching began to occur after 7 hours had passed. When the hydrochloric acid concentration was measured after 8 hours of operation, it was found to be 4.1 mol/min.

[Brief explanation of the drawing]

FIG. 1 shows changes over time in the hydrochloric acid concentration and pH in the etching solution. 1 shows the change in the concentration of hydrochloric acid when controlled by the method of the present invention, and t12 shows the change in the concentration of hydrochloric acid when controlled by the conventional method. Special ￥ [Applicant Mitsubishi Gas Chemical Co., Ltd. Representative Nagano Washo @ To + Takeshuyu C Semizuke ◆ 1 2 Kasui

Claims (1)

[Claims] When regenerating a copper chloride etching solution by adding hydrochloric acid and hydrogen peroxide, a part of the etching solution is extracted from the etching system, which is equipped with an etching tank, a detection tank, a regeneration tank, etc., and the solution is mixed with water or water. The etching solution is diluted with alkaline water, the hydrochloric acid concentration of the solution is detected continuously or intermittently, and a part of the etching apparatus is replenished with water or hydrochloric acid according to the preset hydrochloric acid concentration range. A method for controlling and managing an etching solution, characterized by controlling the concentration.