JP3220564B2 - Etching equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching apparatus for etching, for example, a copper printed circuit board with a cupric chloride etching solution.

[0002]

2. Description of the Related Art A copper printed circuit board etching method using a cupric chloride etching solution is generally widely used in a wide range of fields such as consumer use and industrial equipment. The reaction mechanism for etching copper (Cu), which is the material to be etched, using this etchant is shown by the following equation (1), and cupric chloride (CuCl ₂ ) is converted to cuprous chloride (Cu) by this reaction.
Cl). Cu + CuCl ₂ = 2CuCl (1) This cuprous chloride has low solubility in water and is hardly soluble, but forms a copper complex with hydrochloric acid (HCl) contained in about 7 to 8% of a cupric chloride etching solution. It is dissolved in the solution after the etching process. However, since cuprous chloride does not have the ability to dissolve copper, the presence of the cuprous chloride in the etching solution lowers the etching rate (dissolution amount of copper per unit time), thereby etching the material to be etched. The processing efficiency is significantly reduced.

Since the etching reaction using a cupric chloride etching solution is originally slower than the etching reaction using a ferric chloride etching solution, it is necessary to perform the etching treatment in a state as close as possible to a new solution. Conventionally, for example, when the concentration of cuprous chloride in an etching solution exceeds a predetermined value, a method of oxidizing cuprous chloride generated by the above-described etching reaction to quickly regenerate cupric chloride has been adopted. Have been. As a method of oxidizing cuprous chloride, aqueous hydrogen peroxide (H ₂ O ₂ ) is used as an oxidizing agent, and hydrochloric acid is added to supplement chlorine ions (Cl ⁻ ) consumed in the oxidation. Accordingly, a method of oxidizing and regenerating cuprous chloride in an etching solution to cupric chloride has been adopted. The reaction formula at this time is shown in the following formula (2). _{2CuCl + 2HCl + H 2 O 2} = 2CuCl 2 + H 2 O ... (2)

[0004]

However, in the above-mentioned oxidation regeneration method, both the aqueous hydrogen peroxide used as an oxidizing agent and the hydrochloric acid added for replenishing chloride ions are the largest of the commercially available solutions. The concentration is usually 3
Since the solution is a 5% solution, 65% moisture is always brought into the reaction system due to the use of the etchant after the treatment for regenerating the etching solution. Therefore, the amount of the etching solution increases in accordance with the amount of water by the regeneration process. Therefore, it is necessary to take out the increased amount to the outside of the system of the etching process and separately perform a waste liquid treatment.

[0005] In this waste liquid treatment, in order to recover useful copper, for example, metallic copper is removed from cupric chloride by reaction with iron scrap, or cupric oxide is reacted with an alkaline agent to recover copper. However, in any case, the increased amount of the etching solution must be taken out of the system of the etching process, and the large-scale waste liquid treatment facility as described above requires the etching process. Since it is difficult to install as an auxiliary facility in a factory where the processing is performed, for example, a factory for manufacturing a printed circuit board, the increased amount of the etching solution must be usually transported to a dedicated waste liquid processing facility, for example, a factory for manufacturing an etching solution. In the former case, the ferrous chloride solution, which is a product, is neutralized with an alkali agent, and the resulting precipitate is filtered.However, this precipitate has no use value, so it is dumped into the sea or land. It has to be dumped (landfilled), which is very costly. In the latter case, since the neutralization is performed directly, the cost of an alkali agent for the neutralization is required.

Therefore, conventionally, the more the etching process is performed, the more the etching solution is constantly increased due to the regenerating process accompanying the etching process. The increased etching solution is taken out of the system and transported, and the above-described waste liquid process is performed. However, there is a problem that it requires much labor and costs.

Further, due to the strong oxidizing effect of hydrogen peroxide water, there is a danger of causing a blister-like chemical wound when it adheres to skin such as hands and feet, and also as shown in the following formula (3). Due to the nature of self-decomposition, there is a problem that storage is restricted and management is troublesome. 2H ₂ O ₂ = 2H ₂ O + O ₂ (3) The present invention has been made under such circumstances.
It is an object of the present invention to provide an etching apparatus capable of easily and economically regenerating an etching solution after an etching process.

[0008]

An etching reaction portion for etching copper using an etching solution comprising a cupric chloride solution, and an etching solution flowing from the etching reaction portion is circulated to the etching reaction portion and supplied to the etching reaction portion. A circulating passage for supplying air or oxygen gas to the etching solution in the circulating passage, thereby oxidizing cuprous chloride in the etching solution to regenerate cupric chloride; A crystallization section connected to the circulation path, for adding hydrochloric acid to the etching solution in the circulation path, and depositing cupric chloride in the etching solution by a salting-out reaction , and connected to the crystallization section.
Is, anda solid-liquid separation means for separating from the etching solution was cupric chloride precipitated in the crystal analyzing unit, wherein
The cuprous chloride concentration in the etching solution in the circulation
The oxidizing gas supply means when the
Supply air or oxygen gas to the etching solution
Regenerate copper, cupric chloride of etching solution in the circulation path
When the concentration becomes higher than the predetermined range, the crystallization portion
Supplying the etching solution, wherein the salt in the etching solution is
Characterized in that cupric chloride is deposited.

[0009]

When copper is etched using a cupric chloride etching solution, the amount of cuprous chloride as an etching reaction product in the etching solution increases. Therefore, the cuprous chloride is oxidized with air or oxygen gas to regenerate cupric chloride, and the regenerated cupric chloride is further subjected to an etching process. When the etching treatment and the regeneration of cupric chloride are repeated in this way, the concentration of cupric chloride in the etching solution gradually increases. Therefore, for example, by adding hydrochloric acid to an etching solution in which cupric chloride is dissolved in a substantially saturated state, cupric chloride is precipitated using a salting-out reaction, solid-liquid separated, taken out as crystals, and the filtrate is further etched. Use as a liquid.

[0010]

Embodiments of the present invention will be described below. FIG.
FIG. 1 is a view showing an embodiment of an etching apparatus according to the present invention. In the figure, reference numeral 1 denotes an etching reaction tank for etching a material to be etched such as a copper printed board with a cupric chloride etching solution.

The etching reaction tank 1 has a transport path 11 for transporting the material to be etched, and spray means 12 attached to the upper and lower sides of the transport path 11 for spraying the etchant on the material to be etched from both upper and lower directions. The conveying path 11 and the spraying means 12 constitute an etching reaction section. The bottom of the etching reaction tank 1 is a liquid storage section 13 for storing the etching that has been sprayed onto the material to be etched by the spraying means 12 and has flowed down.

Further, in order to circulate the etching solution in the liquid reservoir 13 of the etching reaction tank 1, the first etching reaction tank 1 is provided with a first pump 21 and a valve 22.
A circulation path A is provided between the etching reaction tank 1 and the pump 21 in the first circulation path A. A regenerating liquid tank 2 for storing the etching liquid flowing out of the etching reaction tank 1 is provided. It is arranged. The regenerating solution tank 2 has, for example, a hydrometer 24 for detecting the concentration of cupric chloride contained in the etching solution in the regenerating solution tank 2 and a hydrochloric acid concentration meter 26 for detecting the hydrochloric acid concentration. Is provided.

On the downstream side of the pump 21 in the circulation path A,
The oxidizing gas supply means 3 is provided so as to supply air or oxygen gas to the etching solution flowing in the circulation path A, and the etching flowing in the circulation path A is provided between the oxidation gas supply means 3 and the valve 22. For example, an oxidation-reduction meter 23 is provided for detecting the concentration of cuprous chloride, which is a reaction product of copper as the material to be etched and cupric chloride, contained in the liquid. Further, the circulation path A is provided with a second circulation path B for circulating the etching liquid from the pump 21 and the oxidizing gas supply means 3 and circulating the etching liquid into the regenerating liquid tank 2. In the circulation path B, a valve 25, a crystallization tank 4 forming a crystallization part, a pump 43, and a solid-liquid separation means 5 are provided in this order. The crystallization tank 4 is provided with hydrochloric acid supply means 7 for adding hydrochloric acid.

The crystallization tank 4 cools the etching solution to, for example, about 15 to 20 ° C., and adds hydrochloric acid by a hydrochloric acid supply means 7 to crystallize the cupric chloride dissolved in the etching solution. This is a tank for forming and depositing, for example, a cooling pipe 42 through which a refrigerant, for example, cooling water flows, in a tank 41, for example. Further, the solid-liquid separation means 5 comprises: a cupric chloride crystal precipitated in the crystallization section 4;
It is for separating solid and liquid from a cupric chloride solution and comprises, for example, a centrifugal separator.
Is sent to the etching reaction tank 1 by the circulation path B.

In this embodiment, the supply and stop of the oxygen gas in the oxidizing gas supply means 3 are controlled based on the output signal of the redox meter 23, that is, the concentration of cuprous chloride.
The valve 25 according to the output signal of 4, ie, the concentration of cupric chloride.
Control the timing of a series of processes of cooling the etching solution, crystal deposition, and solid-liquid separation by controlling the opening and closing of the etching solution. Control means 6 for controlling the stop is provided. Further, for example, the temperature of the etching solution is set to about 50 in the circulation paths A and B near the supply port to the reaction tank 1.
A heating means (not shown) for heating to ° C is provided.

Next, the operation of the above embodiment will be described. In the etching reaction tank 1, a cupric chloride etching solution (CuCl ₂ = 21%, HCL = 8) is applied to the copper printed circuit board sent along the transport path 11 from both upper and lower surfaces.
%) Is heated to, for example, about 50 ° C. by the heating means and sprayed by the spray means 12 to perform the etching process, that is, the reaction represented by the above formula (1). The etching liquid after the etching process flows out of the liquid storage section 13 to the regenerating liquid tank 2 via the first circulation path A, is stored in the regenerating liquid tank 2, and is returned to the etching reaction tank 1.

Here, the etching liquid stored in the regenerating liquid tank 2 and returned to the etching reaction tank 1 through the circulation path A includes cuprous chloride as an etching reaction product and unreacted cupric chloride. And in the regenerating liquid tank 2,
The concentration of cupric chloride is monitored by measuring the liquid specific gravity with a hydrometer 24, and the saturated concentration of cupric chloride is monitored by measuring the hydrochloric acid concentration with a hydrochloric acid concentration meter 26.
The concentration of cuprous chloride is monitored by measuring the concentration ratio of cupric chloride to cuprous chloride by an oxidation-reduction meter 23 provided in the middle of the circulation path A, and the detected data is controlled. Output to means 6.

At this time, as the etching process proceeds, the concentration of cuprous chloride in the etching solution flowing through the first circulation path A increases, but the concentration of cuprous chloride in the etching solution is set to a predetermined upper limit. If it exceeds the value, redox meter 2
An operation command is output from the control means 6 to the oxidizing gas supply means 3 based on the detected value of the control signal 3. As a result, air or oxygen gas is supplied from the oxidizing gas supply means 3 to the etchant flowing in the first circulation path A, whereby cuprous chloride having no etching ability in the etchant is converted into the following (4) As shown in equation (2), cupric chloride having an etching ability is regenerated, and by this reaction, the etching solution has the ability to dissolve copper again, that is, the etching ability.
In addition, since the hydrochloric acid in the cupric chloride etching solution is partially consumed by the above-described reaction, the saturation concentration of cupric chloride increases, so that more copper can be dissolved.

4CuCl + O ₂ + 4HCl = 4CuCl ₂ + 2H ₂ O (4) When the concentration of cuprous chloride gradually decreases and becomes lower than a preset lower limit, a stop command is sent from the control means 6 to the oxidizing gas supply means 3. Is output and the supply of air or oxygen gas is stopped.

As described above, when the etching treatment in the etching reaction tank 1 and the regeneration treatment of cupric chloride by the oxidizing gas supply means 3 are repeatedly performed, the concentration of cupric chloride in the etching solution gradually increases, Hydrochloric acid in the etching solution is consumed by an amount oxidized by oxygen, and the dissolved amount of copper eventually approaches a saturated state. When the concentration of cupric chloride in the etching solution stored in the regenerating solution tank 2 rises above a preset value, the control means 6 controls the valve 25 based on the detection value of the hydrometer 24 to show the valve 25. An operation signal is output to the valve drive unit that does not perform the etching, and the etchant is sent to the crystallization tank 4 via the second circulation path B.

In the crystallization tank 4, a coolant or cooling water is passed through the cooling pipe 42 so that the etching solution is
While cooling to 0 ° C., an operation command is output from the control means 6 to the hydrochloric acid supply means 7 based on the detection value of the hydrochloric acid concentration meter 26 so that the hydrochloric acid concentration in the etching solution falls within a preset range. For example, hydrochloric acid with a high concentration of 35% is added. As a result, the salt concentration in the etching solution increases due to the addition of high-concentration hydrochloric acid, and the cupric chloride is crystallized and precipitated by the salting-out reaction. Dicopper is crystallized and precipitated. The cooling temperature can be set as appropriate. The etching solution containing the precipitated cupric chloride crystal is then sent to the solid-liquid separation means 5 to be separated into a solid and a liquid.
Cupric chloride crystals, which are solids, contain a large amount of valuable copper, so they are recovered and used after a separate purification step,
The etching solution, which is a filtrate, is sent to the second circulation path B,
It is used again as an etchant.

As described above, in the etching treatment apparatus of this embodiment, the regeneration treatment with air or oxygen gas is a reaction between a liquid and a gas. Does not occur, the concentration of cupric chloride increases without increasing the amount of the etching solution. Therefore, hydrochloric acid is added to the concentrated etching solution and cooled to precipitate and remove cupric chloride, and the filtrate is returned to the circulation path A, whereby the etching solution of the etching processing system is discharged.
Since the etching solution can be regenerated without changing the amount of tall, there is no need to treat the waste liquid for the increased amount of the cupric chloride solution as in the conventional method.

Therefore, if the etching solution is regenerated as in the above-described embodiment, the etching process and the regenerating process can be designed as one automated system. On the other hand, in the method of reacting the scrap iron with the etching waste liquid as in the prior art, the etching liquid having no etching ability must be taken out of the etching processing system as the etching waste liquid from the etching processing system. Not suitable for site creation.

Next, a description will be given of an experimental example conducted to confirm the effects of the above-described embodiment. (1) Experimental method Using a cupric chloride dihydrate reagent, this was dissolved in water and heated to 60 ° C. to make it saturated. At this time, the concentration of copper and the concentration of free hydrochloric acid in the supernatant were measured, and the solution was cooled to 20 ° C., and the concentration of copper and the concentration of free hydrochloric acid in the supernatant were measured in the same manner. Next, hydrochloric acid was appropriately added to the saturated solution to change the free hydrochloric acid concentration, and the copper concentration and the free hydrochloric acid concentration were measured as described above. (2) Experimental Results FIG. 2 shows the relationship between the solution temperature and the copper concentration when the free hydrochloric acid concentration was changed to 3.2%, 6.3%, and 9.9%. FIG. 3 shows the relationship between the free hydrochloric acid concentration and the saturated copper concentration at a solution temperature of 60 ° C. According to FIG. 2, for example, free hydrochloric acid is 0%
In the case of (2), the saturated concentration of the cupric chloride solution is cooled to about 20 ° C. by cooling the cupric chloride solution saturated at 60 ° C. to about 3.
It was confirmed that a supersaturated portion was obtained as crystals by cooling the solution to lower by 8%.

FIG. 3 shows that the free hydrochloric acid concentration was 2% and 8%.
% Are 23.6% and 16%, respectively.
When the concentration of hydrochloric acid is increased to 8% by adding 35% hydrochloric acid to a solution having a free hydrochloric acid concentration of 2%, the solution is diluted from the water contained in 35% hydrochloric acid. As shown by the dotted line, when the hydrochloric acid concentration is 8%, the copper concentration is about 20%. Therefore, it was confirmed that by adding 35% hydrochloric acid to increase the hydrochloric acid concentration to 8%, crystals of cupric chloride dihydrate which had become supersaturated by the salting-out reaction could be obtained in an amount of about 4.0% as a copper concentration. Was done.

When the solution is further cooled to precipitate cupric chloride crystals, since the change in the saturated concentration with respect to the temperature of copper is 0.12% / ° C., the solution is cooled from 60 ° C. to 20 ° C.
The crystals of cupric chloride that precipitates when cooled down are about 4.8% in copper concentration, but when hydrochloric acid is added to the solution and cooled to precipitate cupric chloride crystals, Since the copper (II) chloride crystals are precipitated at a concentration of about 4.0% by the above-mentioned salting-out reaction, 8.8% of the copper concentration is precipitated together with the precipitation of 4.8% by cooling. It was confirmed that cupric chloride crystals were obtained about 1.8 times more than when only cooling was performed.

As described above, in the present invention, air or oxygen gas may be used alone or as a mixture as the oxidizing gas, and cupric chloride crystals may be precipitated only by adding hydrochloric acid. Preferably, cooling is performed together with the addition of hydrochloric acid.
Further, the present invention is not limited to the above-described apparatus. For example, the etching process may be performed by immersing the material to be etched in the etching solution in the etching reaction tank 1. Alternatively, the valves provided in each circulation path may be manually controlled without using the control means 6. Furthermore, in the control of the cuprous chloride concentration and the cupric chloride concentration in the etching solution, not only the above-described detection means, but also management by time, empirical management by judging by the color and state of the solution, Is also good. Further, the crystallization section and the solid-liquid separation means are not limited to being provided in the second circulation path B as in the above-described embodiment, but may be provided in the first circulation path A, for example.

[0028]

According to the present invention, cuprous chloride generated during the etching process of, for example, a copper printed board with a cupric chloride etching solution is rapidly oxidized using air or oxygen gas to form a second chloride. The regeneration process of the etching solution is simplified by regenerating the copper and automatically concentrating the etching solution to precipitate cupric chloride as a crystal, thereby simplifying the regeneration process and improving the regeneration process. Since the total amount of the etchant does not increase, it is not necessary to perform a waste liquid treatment for the troublesome increase of the etchant, so that an efficient etching process can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an etching apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an experimental result of an example of the present invention.

FIG. 3 is an explanatory diagram showing an experimental result of the example of the present invention.

FIG. 4 is an explanatory diagram showing an experimental result of an example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Etching processing tank 2 Regeneration liquid tank 3 Chlorine gas supply means 4 Crystallization tank 5 Solid-liquid separation means 7 Hydrochloric acid supply means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C23F 1/18 C23F 1/08 101 C23F 1/46

Claims (1)

(57) [Claims] 1. An etching reaction section for etching copper using an etching solution comprising a cupric chloride solution, and a circulation for circulating and supplying an etching solution flowing out of the etching reaction section to the etching reaction section. An oxidizing gas supply means for supplying air or oxygen gas to the etching solution in the circulation path, thereby oxidizing cuprous chloride in the etching solution to regenerate cupric chloride; and connected, hydrochloric acid was added to the etchant of the circulation path, a crystal analyzing unit precipitating cupric chloride in the etching solution by salting out the reaction, connected to said crystal analyzing unit, precipitated in the crystal analyzing unit Solid-liquid separating means for separating the cupric chloride thus obtained from the etching solution, wherein the concentration of cuprous chloride in the etching solution in the circulation path is within a predetermined range.
When the oxidizing gas supply means becomes higher than
Supplying air or oxygen gas to the etching solution
The cupric is regenerated, and the concentration of cupric chloride in the etching solution in the circulation path is within a predetermined range.
When it is higher than the surrounding area,
And then deposit cupric chloride in the etchant.
An etching treatment apparatus characterized in that an etching process is performed.