JP2001107270A - Copper chloride etchant electrolytic regeneration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved electrolytic regeneration treatment in which the precipitation state of copper powder is constant and the copper powder can be scraped off from the cathode plate and discharged from the cathode chamber stably. Provide system. SOLUTION: A return liquid tank 4 is provided in a liquid return path from an electrolytic tank 2 to an etching tank 1, and a liquid discharged from an anode chamber is temporarily retained in the return liquid tank.
A liquid level detector 16 is attached to 3 and a part of the liquid retained in the return liquid tank is returned to the cathode chamber based on the detection result of the liquid level detector, and the liquid level of the cathode chamber is adjusted. Control within a certain range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a printed wiring board,
The present invention relates to a system for regenerating an etching solution degraded in a manufacturing process of an electronic component such as a lead frame using a so-called diaphragm electrolysis method.

[0002]

2. Description of the Related Art Conventionally, in a process of manufacturing an electronic component as described above, it has been industrially performed to form a desired pattern by corroding a copper foil with an etching solution containing copper chloride as a main component. . For an etching solution that deteriorates by corroding copper foil, an oxidizing agent such as aqueous hydrogen peroxide is generally injected to oxidize and regenerate monovalent copper ions generated as the material is dissolved. At the same time, the specific gravity (copper concentration), which increases with the dissolution of the material, is diluted with water to replenish the decreasing chlorine ions.

However, such a method can recover the oxidizing power of copper ions, but requires the addition of hydrochloric acid for supplementing chloride ions, and cannot dilute dissolved copper components. Therefore, it is necessary to dispose excess etching liquid as waste liquid.

In order to solve the above problems, the inventors of the present invention disclosed in Japanese Patent Laid-Open Nos. 5-125564 and 5-125564.
Japanese Patent Application Laid-Open No. Hei 6-158359 proposes a regeneration method using a diaphragm electrolysis method in Japanese Patent Application Laid-Open No. Hei 6-158359, and has put it to practical use.

In order to maintain the composition of the etching solution under optimum conditions by electrolytic regeneration, it is necessary to match the dissolution rate of copper in the etching step with the rate of electrolytic regeneration.
Under the condition of constant current, the rate of electrolytic regeneration can be kept almost constant, whereas the rate of copper dissolution in the etching process varies with the thickness of copper foil, differences in patterns and production conditions. However, there is a problem that it is difficult to make the dissolution speed of the steel equal to the speed of the electrolytic regeneration.

The monovalent copper ions regenerated with chlorine gas are easily oxidized by oxygen in the air. When oxidation by oxygen occurs, chlorine gas generated by electrolysis is released in surplus, resulting in a loss of chlorine ions, an increase in the replenishment of hydrochloric acid and a treatment of the released chlorine gas.

To solve this problem, the present inventors have proposed and put to practical use a method for controlling the composition of an etching solution incorporating an electrolytic regeneration method in Japanese Patent Application Laid-Open No. H11-14067.

[Problems to be solved by the invention]

However, in order to actually perform the electrolytic regeneration of the etching solution industrially, there is a problem in terms of the stability of the discharge of the copper powder from the electrolytic bath. It has been found that it is important to maintain the deposition state constant and to control the liquid composition and voltage in the electrolytic cell for this purpose.

Accordingly, the present invention provides an improved electrolytic regeneration system capable of stably removing the copper powder from the cathode plate and discharging the copper powder from the cathode chamber with a constant copper powder deposition state. The task is to provide

[0010]

In order to solve the above-mentioned problems, it is known that factors affecting the precipitation state of copper powder include current density and temperature in electrolysis and copper concentration in catholyte. ing. It is also known that the temperature of the liquid in the electrolytic cell rises due to heat loss due to electric resistance. The present inventors, in order to prevent the current density from fluctuating due to fluctuations in the liquid level in the electrolytic cell, a part of the liquid discharged from the electrolytic cell, from the liquid level detecting mechanism installed in the cathode chamber The method of controlling and returning with the signal of the above is effective. At that time, a catholyte circulation mechanism is attached to uniformly stir the liquid in the cathode chamber, and furthermore, a temperature detector and a cooler are provided in the catholyte circulation path. It has been found that a method of adjusting the temperature by providing a liquid is preferable.

On the other hand, the concentration of hydrochloric acid in the catholyte and the anolyte is determined by the concentration of hydrochloric acid in the continuously supplied etching solution, but gradually decreases depending on the operating conditions. In particular, the concentration of hydrochloric acid in the catholyte is 30 g / liter. It was found that when the voltage was lowered below, it became impossible to perform electrolysis at a practical current density due to the increase in voltage, and the state of deposition on the cathode plate also changed, which hindered peeling. Therefore, the precipitation of copper was stabilized by replenishing hydrochloric acid so that the concentration of hydrochloric acid in the catholyte was not less than the above concentration.

The copper powder that precipitates on the cathode plate has a current of less than 20 g / liter, preferably within the range of 5 to 20 g / liter, in the solution (catholyte) in the cathode chamber of the electrolytic cell. The present inventors have already found that copper powder having the highest efficiency and easy to peel off from the cathode plate is obtained,
As a method for controlling the copper concentration in the catholyte within this range, a liquid specific gravity detection mechanism is attached to the electrolytic cell, and the supply amount of the etching liquid supplied to the electrolytic cell is controlled according to the specific gravity of the catholyte to be detected. Is effective. The supply of the etching solution may be performed directly to the electrolytic bath or indirectly to the return bath.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a copper chloride etching solution electrolytic regeneration circulation system according to the present invention. The system basically includes an etching tank 1, an electrolytic tank 2, a regenerating liquid tank 3, a returning liquid tank 4, an exhaust gas washing tower 5, and a pump for transferring liquid between these.

The etching solution in which the material has been dissolved and degraded in the etching bath 1 is supplied to the electrolytic bath 2 by the etching solution supply pump 8 and to the regeneration bath 3 by the regeneration bath feed pump 9. .

The anode chamber 21 is separated from the cathode chamber 23 through a diaphragm 22.
The etchant supplied to the electrolytic cell 2 surrounded by the above-described method reduces the copper concentration by depositing copper in the cathode chamber 23, passes through the diaphragm 22, and flows into the anode chamber 21. The etching solution that has flowed into the anode chamber 21 becomes an anolyte having a reduced chlorine concentration due to the generation of chlorine gas on the surface of an anode plate (not shown).
It is discharged from 4. On the other hand, the deposited copper is discharged as a copper powder slurry from the bottom of the cathode chamber through the copper powder discharge pipe 25 by opening and closing the butterfly valve.

The discharged copper powder slurry is collected in a collecting copper receiving tank 10.
to go into. The adhering liquid discharged together with the copper powder is separated and collected by the copper powder filter 11 and the adhering liquid pump 12, and is returned to the return liquid tank 4.
Liquid. The copper powder after the separation of the adhering liquid is collected in a collecting copper receiving tank 10.
Everything is regularly carried out and collected.

The cathode chamber 23 of the electrolytic cell 2 is provided with a catholyte outlet 26 and an inlet 27 for circulating the catholyte. The catholyte is drawn out from the outlet 26 using the circulation pump 13 and pumped up. It is returned and circulated through the cooler 14 to the inflow port 27. The cooler 14 is for cooling the heat generated by the electric resistance during the electrolysis, and measures the temperature of the catholyte using the liquid temperature detecting means 15 attached to the circulation path. At this time, a coolant (for example, cooling water) is supplied to the cooler 14 to control the temperature of the catholyte within a certain range. The set temperature depends on the liquid composition, but is set, for example, in the range of 50 ° C. ± 5 ° C. to 70 ° C. ± 5 ° C. At a high temperature, the electric resistance of the liquid decreases, which is preferable in that range. However, the durability of the electrode also decreases, so that an appropriate set value must be determined for each liquid composition.

The electrolytic cell 2 is provided with a liquid level detecting means 16 for detecting upper and lower limits of the liquid level of the catholyte.
The return liquid pump 41 is returned from the return liquid tank 4 according to the detection result.
The liquid is replenished via the, and the liquid level of the cathode chamber 23 is kept within a certain range. Regarding this liquid level, the electrolytic cell is designed so that the effective part of the electrode surface, that is, all the parts that undergo an electrolytic reaction in contact with the liquid are always in the liquid. ± 50mm to position of liquid outlet pipe
The degree is defined as the liquid level control range.

In addition, by circulating the catholyte, the liquid composition is made uniform, and the downstream side of the circulating pump 13 is branched so that the flow rate can be appropriately changed by opening and closing the valve. A liquid specific gravity detecting means 17 is provided in a separate circulation path, and when the measured liquid specific gravity falls below the set lower limit, the etching liquid supply pump 8 is started (or the supply liquid amount is increased), and is set to a value equal to or higher than the set upper limit. (The supply lowering amount may be reduced, the set lower limit value and the set upper limit value may be the same value). Further, a means 18 for detecting the concentration of hydrochloric acid of the catholyte is provided in the circulation path, and when the measured concentration of hydrochloric acid falls below a set value, that is, 30 g / liter, the hydrochloric acid is metered and replenished into the circulation path of the catholyte. The hydrochloric acid concentration should be adjusted above the set value and up to about 120 g / l.

The gas-liquid mixed flow discharged from the gas / anolyte outlet pipe 24 flows into the gas-liquid separator 28, and the chlorine gas is separated from the upper part of the gas-liquid separator and the anolyte is separated and discharged from the lower part. The chlorine gas is sucked by the negative pressure generated in the ejector 31 attached to the regenerating liquid tank 3, and is automatically circulated from the regenerating liquid tank 3 to the regenerating liquid tank 3 via the ejector 31 by the ejector pump 32 as an ejector driving liquid. Is contacted and absorbed. The anolyte is returned to the return liquid tank 4 by overflow so that the liquid level of the gas-liquid separator 28 becomes constant.
Flows into

The return liquid tank 4 is provided with a liquid surface level detecting means 42. The return liquid increase amount obtained by subtracting the amount of liquid to be replenished and returned to the electrolytic tank 2 from the amount of liquid to be received in the return liquid tank 4 is:
So that the liquid level of the return liquid tank 4 falls within a certain range,
On the basis of the detection result of the liquid level detecting means 42, the liquid is drawn from the return liquid tank 4 to the regenerating liquid tank 3 via the return liquid pump 41. The regenerating liquid tank 3 is also provided with a liquid level detecting means 33 and a return pump 34 so that the regenerating liquid can be returned to the etching tank 1.

Exhaust pipes 29, 39 and 49 are provided above the cathode chamber 23, the regenerating liquid tank 3 and the returning liquid tank 4 of the electrolytic cell 2, respectively. Then, if there is any chlorine gas that comes into contact with the etching liquid to be received from the etching tank 1 to the regenerating liquid tank 3 and is not absorbed by the ejector 31, it is absorbed in the etching liquid. The reception of the etching liquid from the etching tank 1 to the regenerating liquid tank 3 can be performed not only by the direct route to the regenerating liquid tank 3 but also by the cleaning tower route to the regenerating liquid tank 3 via the cleaning tower 5 as described above. A self-circulation route through the ejector 31 is also possible.

The exhaust pipe 51 from the top of the washing tower 5 is connected to the secondary washing tower 6, and the exhaust gas from the exhaust pipe 51 may be chlorine gas which is not absorbed by the ejector 31 and the exhaust gas washing tower 5 in some cases. The chlorine gas is also discharged together with the copper powder in the above-mentioned recovered copper receiving tank 10, washed and absorbed by a part of the adhesive liquid separated and collected by the adhesive liquid pump 12 and returned to the return liquid tank 4. Since the amount of the adhered liquid is originally small in amount, in order to adjust the liquid / gas ratio, the return liquid is branched from the return path from the return liquid tank 4 to the electrolytic tank 2 via the return liquid pump 41, and the returned liquid is secondarily washed. Sometimes used. After exhaust gas cleaning, the liquid discharged from the secondary cleaning tower 6 is returned to the return liquid tank 4.
, But a part thereof is returned to the recovered copper receiving tank 10. The refluxed liquid comes into contact with the recovered copper and becomes a cuprous chloride-containing liquid for absorbing chlorine gas by dissolving a part of it. If there is a large excess of chlorine gas, use it again for absorption. Is possible. It is also possible to omit the exhaust gas washing tower 5 and directly wash the exhaust gas from the cathode chamber, the regenerating liquid tank and the returning liquid tank in the secondary washing tower 6.

[0024]

According to the present invention, the return liquid tank is provided in the liquid return path from the electrolytic tank to the etching tank, and the liquid discharged from the anode chamber is temporarily retained in the return liquid tank, A liquid level detecting means is attached to the cathode chamber, and based on the detection result of the liquid level detecting means, a part of the liquid staying in the return liquid tank is returned to the cathode chamber to adjust the liquid level of the cathode chamber. Since the control is performed within a certain range, it is possible to suppress a change in current density due to a change in liquid level, and to keep the copper powder deposition state constant.

A circulation path for circulating the liquid in the cathode chamber, a liquid temperature detecting means and a cooler are provided in the circulating path. By controlling the temperature within a certain range, the temperature and liquid composition can be made constant and uniform, and it is ensured that the copper powder deposition state is kept constant.

A circulation path for circulating the liquid in the cathode chamber, a means for detecting the concentration of hydrochloric acid in the circulating liquid, and a means for replenishing hydrochloric acid in the circulation path are provided. By replenishing the circulating fluid with hydrochloric acid based on the concentration detection result and controlling the hydrochloric acid concentration within a certain range, the hydrochloric acid concentration can be kept constant, and the precipitation state of copper powder can be kept constant. Of the copper powder and discharge of the copper powder from the cathode chamber can be stably performed.

[Brief description of the drawings]

FIG. 1 is an overall conceptual diagram of a copper chloride etching solution electrolytic regeneration circulation system according to the present invention.

[Explanation of symbols]

1: etching tank, 2: electrolytic tank, 3: regenerating liquid tank, 4: return liquid tank, 5: exhaust gas washing tower, 6: exhaust gas secondary washing tower, 10: recovered copper receiving tank, 11: copper powder filter, 14: Cooler, 28: gas-liquid separator,
31: Ejector

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Susumu Takayama 8-1 Hirai Hiraicho, Nishitama-gun, Tokyo Nippon Steel Mining Co., Ltd. F-term (reference) 4K057 WA18 WA19 WB04 WE08 WH01 WH02 WH05 WH07 WM19 WN01 WN02

Claims (4)

[Claims] An etching bath having a copper chloride etching solution, and an electrolytic bath for sending and receiving the etching solution to and from the etching bath, wherein the electrolytic bath is connected to a cathode chamber and an anode chamber via a diaphragm. In an etchant electrolysis regeneration system which separates and receives an etchant from a cathode chamber to an anode chamber through a diaphragm continuously to be electrolyzed and then returns to an etching tank, from the electrolytic tank to the etching tank A return liquid tank is disposed in the liquid return path, and the liquid discharged from the anode chamber is temporarily retained in the return liquid tank. At the same time, a liquid level detection means is provided in the cathode chamber of the electrolytic cell to detect the liquid level. A part of the liquid retained in the return liquid tank is returned to the cathode chamber based on the detection result of the means to control the liquid level of the cathode chamber within a certain range. Beam. 2. A circulating path for circulating the liquid in the cathode chamber, a liquid temperature detecting means and a cooler provided in the circulating path, and cooling is performed based on a result of detecting the temperature of the circulating liquid by the liquid temperature detecting means. The electrolytic solution regeneration system according to claim 1, wherein the solution temperature is controlled within a certain range by a vessel. 3. An etching bath having a copper chloride etching solution, and an electrolytic bath for sending and receiving the etching solution between the etching bath and the electrolytic bath, wherein the electrolytic bath is connected to a cathode chamber and an anode chamber via a diaphragm. In an etchant electrolytic regeneration system that separates and receives an etchant from a cathode chamber to an anode chamber through a diaphragm, and then electrolyzes the electrolytic solution and returns it to an etching tank, the solution in the cathode chamber is circulated. And a means for detecting the concentration of hydrochloric acid in the circulating fluid, and a means for replenishing hydrochloric acid in the circulating fluid. An electrolytic regenerating system for an etching solution, characterized by controlling hydrochloric acid concentration within a certain range by replenishing hydrochloric acid. 4. The electrolytic regenerating system according to claim 3, wherein when the detected value of the hydrochloric acid concentration of the circulating liquid falls below 30 g / liter, the circulating liquid is replenished with hydrochloric acid.