JPH0763602B2 - Vertical multi-stage stirring tank and method for supplying copper to chemical copper plating solution using the stirring tank - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical multi-stage stirring tank and a method for supplying copper to a chemical copper plating solution using the stirring tank.

[0002]

2. Description of the Related Art In recent years, with the progress of the electronic industry, the chemical copper plating technology used for manufacturing printed circuit boards and the like has become very important. The chemical copper plating solution used in the chemical copper plating process is currently a divalent copper ion, a divalent copper ion complexing agent, a divalent copper ion reducing agent, p
Those consisting of H modifiers and organic additives are mainly used. For example, a typical chemical copper plating solution called an EDTA bath has the following composition (operating temperature 70
± 3 ° C).

Component concentration CuSO ₄ .5H ₂ O 5 to 15 g / l EDTA (complexing agent) 5 to 65 g / l HCHO (concentration: 37%) (reducing agent) 1 to 10 ml / l NaOH (pH adjusting agent ) Amount required to reach pH 12 to 12.8 (room temperature) Organic additive Small amount

In such a chemical copper plating solution, the consumed copper ions are replenished as well as the plating performance.
Prolonging the life of the plating solution is also a heavy task.

Conventionally, when replenishing copper ions to a chemical copper plating solution, a solution containing copper sulfate as a main component (copper sulfate + reducing agent + pH adjusting solution) is added to and mixed with the plating solution partially withdrawn from the plating bath, It was returned to the plating tank. However, when the plating treatment amount increases, the reaction products sodium sulfate and sodium formate accumulate in the plating liquid, which shortens the life of the plating liquid and necessitates a construction bath for each constant plating treatment amount. there were. This causes a large increase in the cost burden of the chemical copper plating solution.

In order to solve these problems, copper hydroxide, copper oxide, copper oxychloride, and basic copper carbonate, basic chloride or basic sulfate of copper have recently been used as a copper supplement source. Is proposed. (Japanese Patent Publication No. 59-325
42).

By the way, among these copper replenishment sources, sodium sulfate is not generated by the reaction when copper is replenished to the chemical copper plating solution using copper oxide or copper hydroxide, so that it is replaced with conventional copper sulfate. It is said that if copper oxide is used for copper replenishment, chemical copper plating with good quality can be performed. However, copper oxide is much slower to dissolve in the copper replenishment reaction to the chemical copper plating solution than copper sulfate, and therefore i) requires a large facility for dissolution. Ii) Copper concentration in the chemical copper plating solution Is difficult to control, iii) there is a problem that undissolved copper oxide is mixed in the chemical copper plating solution, so precise filtration equipment is required, and therefore it is not industrially put into practical use. Is.

Incidentally, the vertical multi-stage stirring tank used as one of the methods for supplying copper to the chemical copper plating solution is provided with a plurality of stirring paddles on the stirring shaft as illustrated in FIG. Since a partition plate is placed between each stirring paddle, in the case of a liquid-liquid reaction, the reaction can be efficiently performed by stirring, but the chemical copper plating solution is powdered. It is difficult to perform efficient stirring in the solid-liquid reaction performed by replenishing the solid copper oxide, and even when a gas such as air is blown, the gas short-passes and the solid-liquid-gas is uniformly mixed. It had a drawback that it was not performed sufficiently.

[0009]

SUMMARY OF THE INVENTION The present invention has been made as a result of studying a stirring tank capable of performing efficient stirring and mixing in solid-liquid reaction and solid-liquid-gas reaction in view of the situation as described above. In addition, in the copper replenishment to the chemical copper plating solution, it is effectively applied to stably and replenish copper to the chemical copper plating solution by continuously and completely dissolving copper oxide, which is suitable as a copper replenishment source. It is an object of the present invention to provide a vertical multi-stage stirring tank that can be used, and a method of supplying copper to a chemical copper plating solution using the stirring tank.

[0010]

A vertical multi-stage stirring tank according to the present invention is provided with a plurality of partition plates inside a vertically installed stirring tank so as to divide the inside into a plurality of chambers. An agitation shaft is hung down by penetrating an opening provided in each central part of the partition plate, and an agitation paddle is provided on the agitation shaft corresponding to each of the partitioned chambers, and a liquid supply pipe is provided in the lowermost chamber. In a multi-stage stirring tank in which discharge pipes are provided in the uppermost chambers, a) a partition disk is arranged on the stirring shaft above the stirring paddle so as to rotate together with the stirring paddle, and b) A multi-stage stirring tank and a gas injection pipe communicating with each bottom of the liquid supply pipe are provided.

Further, the method of replenishing copper to the chemical copper plating solution of the present invention uses the above-mentioned vertical multi-stage stirring tank and contains copper oxide and a reducing agent, and at least chemical copper plating containing a copper salt and a complexing agent. The solution is supplied into the stirring tank through the liquid supply pipe provided in the stirring tank, and the stirring shaft in the stirring tank is rotated to dissolve the copper oxide in the chemical copper plating solution. And

Next, the constitution of the vertical multi-stage stirring tank of the present invention will be described.
A specific description will be given based on FIG. 1 exemplifying the stirring tank.

[0013] Figure 1 is a schematic view showing an outline of a longitudinal section of the stirring vessel, reference numeral 1 denotes a stirring tank the body that is installed vertically. Inside the stirring tank 1, a plurality of partition plates 21 to 24 are arranged so as to divide the inside into a plurality of chambers, and an opening 9 provided at each central portion of the partition plates 21 to 24.
The stirring shaft 3 is hung down so as to penetrate 1 to 94. In the figure, reference numerals 41 to 44 denote stirring paddles, which are arranged on the stirring shaft corresponding to each of the partitioned chambers. In addition, reference numerals 71 to 74 in the figure indicate the stirring paddle 4 as the stirring shaft 3 rotates.
The partition disk arrange | positioned at the stirring shaft 3 so that it may rotate with 1-44 is shown. The disks 71 to 74 are agitating paddles 41.
Having a diameter greater than ~ 44 means that the
It is preferable for efficiently stirring the liquid mixture.

In the figure, 5 is a liquid supply pipe provided in the lowermost chamber of the stirring tank, and its opening 51 is installed at a position higher than that of the multi-stage stirring tank 1. Reference numeral 8 denotes a gas injection pipe communicating with each bottom of the stirring tank and the liquid supply pipe 5.

In the vertical multi-stage stirring tank of the present invention, the larger the number of stages of the chambers partitioned by the partition plates disposed in the tank, the higher the efficiency of stirring and mixing, but the increase in equipment. In consideration of the above, it is usually sufficient to have 3 to 6 stages, and it may be appropriately selected according to the purpose.

The smaller the size of the openings 91 to 94 provided in the central portions of the partition plates 21 to 24 for suspending the stirring shaft 3 in the vertical multi-stage stirring tank of the present invention, the smaller the supply to the tank. Although the contact efficiency with the liquid increases, on the other hand, if the amount is too small, the amount of the processing liquid decreases, so it is preferable to select it in consideration of the required amount of the processing liquid and the amount of gas to be blown.

The diameter of the stirring paddles 41 to 44 provided on the stirring shaft 3 is normally 1/3 to 2/3 of the diameter of the stirring tank 1,
Moreover, the shape of the paddle is a disc type, a propeller type,
Any of turbine type may be used. The stirring paddles 41 to 41
44 is preferably provided so as to be located substantially at the center of the chamber partitioned by the partition plates 21 to 24.

Next, the partition disks 71 to 74, which are one of the features of the vertical multi-stage stirring tank of the present invention, will be described.

The diameter of the partition disks 71 to 74 is preferably larger than the diameter of the stirring paddles 41 to 44,
Although it must be selected according to the paddle diameter and shape,
It is usually about 1.2 to 1.5 times the diameter of the stirring paddle. The distance between the agitating paddle 41 to 44 and the partition disk 71 to 74, blow gas amount, the different also by the height of the stirring speed and stirring paddle, 0.2 normal height of the stirring paddle
About 1.0 times is appropriate.

In the vertical multi-stage stirring tank of the present invention, the action due to the rotation of the partition disks 71 to 74 prevents a short path of the blown gas, and the action in cooperation with the stirring paddles 41 to 44 removes the liquid in the tank. A turbulent state is created, and the injected gas is fragmented to enable complete solid-liquid-gas mixing.
Therefore, the use of the stirring tank of the present invention has a characteristic effect that even a solid that cannot be completely dissolved in a liquid by an ordinary multistage stirring tank can be completely and efficiently dissolved in a short residence time. In addition, by mounting a baffle plate at an appropriate position in the stirring tank 1, the above dissolution efficiency can be further improved.

Next, the gas injection pipe 8 for injecting the reactive gas, which is another characteristic feature of the multistage stirring tank of the present invention and is provided at the bottom of the stirring tank 1 and the liquid supply pipe 5, will be described.

According to the present invention, oxygen, air or the like is blown through the gas blowing pipe 8 according to the purpose, so that solid-liquid-
The reaction efficiency can be improved by promoting gas mixing and contact. In addition, it is more effective to blow fine bubbles by using a bubbler tube or the like when blowing the gas.

The rotation speed of the stirring shaft 3 of the multi-stage stirring tank of the present invention must be appropriately selected depending on the specific gravity and viscosity of the treatment liquid, the type of stirring paddle, the design conditions of equipment, etc. It is usually 14
It may be 0 to 500 rpm, and the peripheral speed is usually 15 m / s or less, but if necessary, 15 to 30 m / s may be adopted.

An opening 51 is formed in the upper part of the liquid supply pipe 5 provided at the lowermost stage of the stirring tank 1 according to the present invention, and the liquid, solid or the like to be reacted from the opening 51 is inside the stirring tank 1. Is supplied to. In addition, after the liquid and the solid are stirred and mixed in a preliminary stirring tank, a liquid supply pipe 5 is used by using a pump or a head difference.
The liquid may be directly supplied to.

Further, the discharge pipe 6 provided at the uppermost stage of the stirring tank 1 is usually attached so as to overflow depending on the liquid level of the liquid supply pipe 5, but instead of the overflow system, the liquid of the stirring tank 1 may be replaced. A method of detecting the level and discharging with a pump may be adopted.

As described above, the vertical multi-stage stirring tank of the present invention can be used for ordinary stirring, mixing, reaction by stirring and mixing, etc., but it is particularly uniform mixing of poorly soluble solids with liquids and gases. Alternatively, it can be preferably used when a complete reaction in a short time is desired.

Next, the method of supplying copper to the chemical copper plating solution using the vertical multi-stage stirring tank of the present invention will be specifically described.

The chemical copper plating solution targeted by the present invention contains a reducing agent and at least a copper salt and a complexing agent. Specifically, it is a complex of divalent copper ion and divalent copper ion. The composition is composed of an agent, a divalent copper ion reducing agent, a pH adjuster and an organic additive, and also includes those to which a trace amount of metal ion is added as necessary. A typical example of this is the above-mentioned EDTA bath, and in addition to this, Rochelle salt bath, amines bath, gluconate bath, glucopeptoneate bath, etc. are known.

In the plating film deposition reaction, the complexing agent is EDT.
When A, the reducing agent is formaldehyde (HCHO), and the pH adjusting agent is NaOH, they are represented by the following formula (I). EDTA-Na ₂ Cu + 2HCHO + 4NaOH = EDTA-Na ₄ + Cu + H
₂ + 2HCOONa + 2H ₂ O (I) According to this reaction formula (I), for example, a material to be plated such as a printed circuit board is immersed in a chemical copper plating solution to form a copper film at a desired portion.

In the method of the present invention, in order to replenish the consumed copper ions in the chemical copper plating solution by the above reaction, the chemical copper plating solution in which the copper ions are consumed from the chemical copper plating tank is preferably a fixed amount. It is continuously withdrawn and sent to the upper opening of the feed pipe of the vertical multi-stage stirring tank of the present invention, and a predetermined amount of finely powdered copper oxide (CuO) is added to the upper opening using a quantitative feeder or the like. Then, a mixture of the copper oxide and the chemical copper plating solution in which the copper ions are consumed is supplied to a vertical multi-stage stirring tank through a liquid supply pipe. At this time, it is preferable that the copper oxide and the chemical copper plating solution are previously stirred by a stirrer provided on the upper part of the liquid supply pipe and then supplied to the multi-stage stirring tank.

Further, the liquid extracted from the plating tank in the preliminary stirring tank and copper oxide (CuO) may be stirred and mixed in advance and then directly supplied to the liquid supply pipe by utilizing a pump or a head difference.

The mixture supplied to the multi-stage stirring tank of the present invention is the same as the composition used for the chemical copper plating filled in the stirring tank and oxygen blown from a gas blowing pipe or oxygen such as air. It is agitated and mixed with the contained gas, and due to the excellent agitation function of the multi-stage agitation tank, solid-liquid-gas contact is sufficiently performed to dissolve copper oxide in the liquid, and copper ions are supplied to the chemical copper plating solution. Will be done.

The chemical copper plating solution thus replenished with copper ions is withdrawn from the vertical multi-stage stirring tank by a pump or the like by overflow or liquid level control, and then is consumed in the copper deposition reaction. A predetermined amount of (NaOH) and a reducing agent (HCHO) for divalent copper ions are added and mixed, sent to a chemical copper plating facility, and used again as a chemical copper plating solution.

The above-described blowing of oxygen or air into the stirring tank is not always necessary in terms of reaction because the copper replenishment reaction is performed according to the following reaction formula (II) when copper oxide is used as the copper replenishment source. Not necessary. EDTA-Na ₄ + CuO + H ₂ O = EDTA-Na ₂ Cu + 2NaOH (II)

However, unless the chemical copper plating solution is kept in an oxidizing atmosphere by blowing an oxygen-containing gas, the reducing agent contained in the plating solution causes a reduction reaction to precipitate copper, Alternatively, since a problem that the dissolution rate of copper oxide becomes slow may occur, it is preferable to blow an oxygen-containing gas in the present invention. Gas blowing amount is not uniquely determined for varying the processing solution or the like, 0.0 3 to 0.3-fold per unit volume of the multi-stage stirred tank, ie,
0.03 to 0.31 / min with respect to volume 11 , preferably
About 0.1 to 0.21 / minute is sufficient.

The copper oxide is supplied via the upper opening of the liquid supply pipe to the multistage stirring tank, a copper powder or heated in air, copper hydroxide, copper carbonate, by thermal decomposition of copper nitrate and the like ,
Further, it can be industrially produced by electrolyzing electrolytic copper in a sodium sulfate bath. Replenishment source copper oxide is required to be inexpensive, highly pure and easily soluble, and as a new copper oxide production method satisfying these requirements,
A method of catalytically reacting an aqueous ammonia solution or an aqueous ammonia solution and an aqueous solution of sodium hydroxide with metallic copper using an autoclave has been proposed, and copper oxide extremely suitable for the purpose of the present invention can be obtained.

The temperature of the plating solution in the vertical multi-stage stirring tank is preferably equal to or lower than the temperature during plating. For example, in the case of an EDTA bath, Cu ²⁺ , HCHO and NaOH are present in the plating solution to be supplemented with copper oxide. Therefore, if the plating solution temperature exceeds the plating temperature, copper ion is supplemented at the same time. The film deposition reaction is likely to occur in the melting tank. The temperature during plating is maintained at a high temperature, for example, around 70 ° C. in an EDTA bath in order to produce an optimum plating reaction. As the temperature of the plating solution is lowered, the reaction becomes less likely to occur, and such accidental copper deposition can be prevented. On the other hand, the lower the temperature, the lower the solubility of copper oxide. In the chemical copper plating bath represented by EDTA bath,
By controlling the temperature of the plating solution at 40 to 60 ° C., a sufficient copper oxide dissolution rate is guaranteed while preventing the copper precipitation reaction.

The copper ion to be replenished must be up to an equimolar amount to the free complexing agent, and if it exceeds this, the replenished copper oxide will not dissolve and will either settle or be physically suspended in the liquid by stirring. It becomes a state. This undissolved copper oxide adversely affects the equipment such as the wear of the tank and the stirrer, and may cause abnormal deposition of copper or adversely affect the plating film, so it is used as a replenisher for the plating tank. Creates a need for solid-liquid separation. Even if a separator is provided, it causes clogging of the separator. Therefore, the amount of copper ions to be supplemented in order to reduce undissolved copper oxide as much as possible is up to equimolar to the free complexing agent. On the other hand, if the amount of supplemental copper ions is small, the original plating reaction in the plating tank will be hindered, so the amount of copper ions added is 20% of the complexing agent molar amount.
The above is desirable.

That is, from the viewpoint of copper ion replenishing efficiency and solubility, copper ions corresponding to 20 to 80%, more preferably 40 to 60% of the molar amount of the free complexing agent are replenished in the form of copper oxide. Preferably. The entire amount of copper oxide added in this way forms a chelate with a free complexing agent, becomes copper ions for depositing a plating film, and guarantees the supply of consumed copper ions.

Since there may be undissolved components due to impurities contained in the copper oxide used, a filtration facility for removing these is installed between the vertical multi-stage stirring tank and the plating facility, just in case. It is desirable to keep it.

The method for supplying copper to the chemical copper plating solution using the vertical multi-stage stirring tank according to the present invention will be specifically described below with reference to examples.

[0041]

EXAMPLE A dissolution test of copper oxide in a chemical copper plating solution was carried out under the following conditions in the vertical multistage stirring tank shown in FIG. 1 using a test stirring tank having the following specifications.

Test stirring tank device (a) Tank diameter: 300 mm (b) Stirring paddle: Length from stirring shaft 80 mm, width 15
mm, number 4 sheets / step (total 4 steps) (c) step interval: 125 mm (d) partition disk: diameter 200 mm, thickness 1.6 mm (e) partition plate central opening: 20 mm (f) stirring shaft diameter : 8 mm (g) Liquid supply pipe diameter: 50 mm (h) Stirrer paddle is at the center of each chamber (i) Partition disk position: 10 mm from the top of stirrer paddle (center part)

Test conditions (a) Chemical copper plating solution: First, about 2.0 g of copper ions
/ L containing KC solution (trade name, manufactured by Nippon Mining Co., Ltd.) was filled in a stirring tank, and then a chemical copper plating tank (liquid volume: 2400 l)
As a result, about 0.27% (copper consumption = 13.2g / min) of the copper ions contained in the KC solution was continuously extracted as a copper solution by chemical copper plating, and this was supplied to a stirring tank. Liquor Amount supplied: 4 l / min, temperature: 60 ° C, and
After replenishing copper ions in the stirring tank, it was extracted at a rate of 4 l / min. Next, a predetermined amount of pH adjusting agent (NaO
H) and a reducing agent (HCHO) were replenished and then returned to the chemical copper plating tank. (B) Copper oxide: produced by electrolyzing electrolytic copper in a sodium sulfate bath. Supply amount 16.5 g / min (c) Air blowing amount: 7.5 l / min (stirring tank: liquid supply pipe =
4: 1) (D) Stirrer speed: 200 rpm

Using the above apparatus, a test was conducted under the above conditions, and 1 hour later, sampling was performed from each stage, and the dissolution rate of copper oxide was determined by analysis. Also, as a comparative example, except that the partition disk shown in (d) of the above apparatus is removed,
The test was conducted in the same manner as in the example to determine the dissolution rate of copper oxide.

The results are shown in Table 1.

[Table 1]

As is clear from Table 1, in the comparative example, the dissolution rate of copper oxide was as low as 80% even in the fourth stage, and undissolved copper oxide was clearly observed, whereas the vertical multistage stirring of the present invention was conducted. When a tank is used (Example), the dissolution rate of copper oxide is 1
It can be seen that there is a significant difference in that the chemical copper plating solution can be reliably replenished with copper, as it can be completely dissolved at 85% in the second step and 100% in the fourth step.

[0047]

As described above, the vertical multi-stage stirring tank of the present invention has a function of sufficiently mixing and contacting a liquid and a gas with a solid having a slow dissolution rate, so that the solid can be completely completed in a short time. Can be dissolved in.

Therefore, according to the present invention, by using the vertical multi-stage stirring tank, it becomes possible to easily replenish copper to the chemical copper plating solution with copper oxide, which has not been industrially carried out conventionally. Since it is possible to significantly reduce the cost in the chemical copper plating process and improve the quality of the plated film, it has a remarkable effect that it can greatly contribute to the development of the printed circuit board manufacturing industry.

[0049]

[Brief description of drawings]

FIG. 1 is a schematic view showing an outline of a vertical cross section of a vertical multistage stirring tank of the present invention.

[Explanation of symbols]

1 Vertical multi-stage stirring tank 21-24 Partition plate 3 Stirring shaft 41-44 Stirring paddle 5 Liquid supply pipe 51 Upper opening of liquid supply pipe 5 Discharge pipe 71-74 Partition disk 8 Gas blowing pipe 91-94 Partition plate 21 Opening provided at the center of 24

FIG. 2 schematically shows a vertical cross section of a conventional vertical multi-stage stirring tank.

[Explanation of symbols]

 11 Vertical multi-stage stirring tank 33 Stirring shaft 211-244 Partition plate 411-455 Stirring paddle 55 Liquid supply pipe 66 Discharge pipe

Claims (5)

[Claims] 1. A vertically arranged stirring tank is provided with a plurality of partition plates so as to divide the interior into a plurality of chambers, and an opening provided at each central portion of the partition plates is penetrated. And the stirring shaft is hung down, and the stirring shaft is provided with a stirring paddle corresponding to each of the partitioned chambers, a liquid supply pipe is provided in the lowermost chamber, and a discharge pipe is provided in the uppermost chamber. In the multistage stirring tank provided, (a) a partition disk is arranged on the stirring shaft above the stirring paddle so as to rotate together with the stirring paddle, and (b) each of the multistage stirring tank and the liquid supply pipe. A vertical multi-stage stirring tank characterized by having a gas injection pipe communicating with the bottom. 2. A vertically arranged stirring tank is provided with a plurality of partition plates so as to divide the interior into a plurality of chambers, and an opening provided at each central portion of the partition plates is penetrated. The stirring shaft is hung down, and the stirring shaft is provided with a stirring paddle corresponding to each of the partitioned chambers, a liquid supply pipe is provided in the lowermost chamber, and a discharge pipe is provided in the uppermost chamber. Further, a vertical multi-stage comprising a partition disk arranged on the stirring shaft above the stirring paddle so as to rotate together with the stirring paddle, and a gas blowing pipe provided at each bottom of the stirring tank and the liquid supply pipe. Using a stirring tank, a chemical copper plating solution containing copper oxide and a reducing agent and containing at least a copper salt and a complexing agent is supplied into the above stirring tank through the liquid supply pipe, and the stirring tank is stirred. By rotating the shaft, the copper oxide in the chemical copper plating solution is dissolved. How to replenish copper to copper plating solution. 3. The method of supplying copper to a chemical copper plating solution according to claim 2, wherein oxygen or an oxygen-containing gas is introduced into the stirring tank through the gas blowing pipe while rotating the stirring shaft . 4. The chemical copper plating solution supplied into the stirring tank via the liquid supply pipe is consumed after being discharged from the stirring tank.
The method for replenishing copper to a chemical copper plating solution according to claim 2, which is a solution to which an amount of powdered copper oxide corresponding to copper ions is added. 5. The method of supplying copper to a chemical copper plating solution according to claim 4, wherein the solution is preliminarily stirred and then supplied to a stirring tank.