JP2002068743A - Method for manufacturing highly soluble copper oxide, highly soluble copper oxide, raw material for copper plating and method of copper plating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly soluble copper oxide with less impurities, capable of suppressing the generation of insoluble residue, and suitable for, for example, a raw material for copper plating. SOLUTION: The high purity highly soluble copper oxide is obtained by thermal decomposition of basic copper carbonate under a non-reducing atmosphere, for example, in an electric heating furnace, at 250 deg.C-800 deg.C, preferably 350-600 deg.C, and then washing this highly soluble copper oxide in a wash tank and removing moisture by a centrifuge followed by drying.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a soluble copper oxide from basic copper carbonate, a soluble copper oxide, a copper plating material comprising the soluble copper oxide, and a soluble oxide. The present invention relates to a copper plating method using copper.

[0002]

2. Description of the Related Art As one of the techniques for performing a copper plating process on a plating target, a copper plating material is supplied into sulfuric acid which is an electrolytic solution, and a current is passed between an insoluble anode and a plating target forming a cathode. There is a plating method, and it is known that copper oxide obtained by thermally decomposing basic copper carbonate is used as a copper plating material used in this method (Japanese Patent No. 2753855).

[0003] Copper oxide is widely used as a raw material for ferrite materials, and is also used as a copper ion replenishing material in electroless copper plating baths, as described in JP-A-3-80116. Generally, copper mill scale, cuprous oxide or copper hydroxide is produced by heat treatment. However, copper mill scale is difficult to dissolve and cannot be used as a copper plating material. Since there are many ions (chlorine ions), plating is poor and cannot be used. In the above publication (Japanese Unexamined Patent Publication No. 3-80116), copper hydroxide is used in the amount of 6%.
It is described that copper oxide is obtained by heating at 0 to 100 ° C., but cupric hydroxide system has a large amount of Cl ions and S 4 SO 4, so that when it is used for electrolytic plating, plating failure occurs. On the other hand, copper oxide obtained by thermally decomposing basic copper carbonate can be used as a copper plating material because it has a small amount of Cl ions and S of SO4.

[0004]

However, using copper oxide obtained by thermally decomposing basic copper carbonate as a copper plating material has the following problems.

A. Since copper oxide is usually used as a raw material for ferrite, it is required that the weight reduction is small in the ferrite production, particularly in the sintering step, and therefore, the heating temperature when the raw material is thermally decomposed or heat-treated is generally 900 ° C.
As described above, although the obtained copper oxide is more soluble than general copper oxide, the degree of solubility is not so large. Therefore, when the copper plating material is supplied to the copper plating bath (a solution in which the copper plating material is supplied to the electrolytic solution), it takes a long time until the copper plating material is completely dissolved in the electrolytic solution. This causes a variation in quality and also causes a reduction in processing efficiency.

B. Rotary kilns of direct heating with a frame that emphasizes thermal efficiency are commonly used as ordinary cracking furnaces, but when the reducing flame of the frame touches copper carbonate or copper oxide, copper suboxide or metallic copper is reduced. Will be generated in the section. When dissolved in sulfuric acid, which is an electrolytic solution, these cuprous oxides and metallic copper lead to an increase in insoluble residues, which are impurities, and the copper concentration in the electrolytic solution becomes unstable. The quality is impaired and the quality of the plated product becomes unstable.

C. Impurities contained in the basic copper carbonate itself brought from the raw material of the basic copper carbonate, for example, a small amount of an alkali metal (Na or K) or an alkaline earth metal (Mg or C
a), Cl ions, S of SO4, etc. are concentrated, for example, about 1.4 to 1.5 times in copper oxide obtained by thermal decomposition. When Cl ions are accumulated in the plating bath, the surface of the object to be plated becomes rough, or a knob-like or needle-like precipitate occurs,
Product failure. In addition, when S in the SO4 body accumulates, it not only adversely affects the plating state, but also makes it difficult to control the SO4 concentration in the plating bath, and the quality of the plated product becomes unstable. Furthermore, when an alkali metal or an alkaline earth metal accumulates, there is a concern that the sulfates are deposited on the plating surface, which may increase the frequency of the bath.

Therefore, when a continuous operation using copper oxide as a direct plating material is performed, these impurities are accumulated in the plating bath. When the accumulated amount reaches the upper limit of management, plating failure occurs, so plating bath must be built earlier than planned, but since bathing of plating bath is very expensive, cost is low for system operation. It leads to up.

The present invention has been made under such a background. An object of the present invention is to provide an easily soluble copper oxide having high solubility and capable of suppressing generation of an insoluble residue. An object of the present invention is to provide an easily soluble copper oxide containing few impurities. Another object is to provide a copper plating material having high solubility and capable of suppressing generation of insoluble residues. Still another object is to provide a copper plating method using high-purity easily soluble copper oxide.

[0010]

SUMMARY OF THE INVENTION According to the present invention, a basic copper carbonate is heated at a temperature of 250 DEG C. to 800.degree.
This is a method for producing a readily soluble copper oxide, which is characterized in that a readily soluble copper oxide is obtained by heating to a temperature of ° C. and thermally decomposing.
Heating in an atmosphere that does not become a reducing atmosphere means, for example, heating not using a burner directly but using an electric furnace or the like.

Commercially available basic copper carbonate may be used, but an aqueous solution of copper chloride, copper sulfate or copper nitrate is mixed with an aqueous solution of, for example, an alkali metal, an alkaline earth metal or a carbonate of NH 4. The reaction may be carried out while heating, and the reaction product thus precipitated may be obtained by filtration and separation. In this case, mixing the aqueous solution of the carbonate with the aqueous solution of copper chloride, copper sulfate or copper nitrate means that the carbonate is poured into an aqueous solution of copper chloride, copper sulfate or copper nitrate in a solid state, and the carbonate is converted into the aqueous solution. Conversely, it also includes the case where a solid of copper chloride, copper sulfate or copper nitrate is charged into an aqueous solution of carbonate to form an aqueous solution. Since the easily soluble copper oxide according to the present invention has high solubility, it is preferably used as a copper plating material supplied to an electrolytic solution provided with, for example, an insoluble anode and a plated object forming a cathode. Can be. In this case, if the copper plating material contains a large amount of the above-described impurities, the quality of the plated product is deteriorated. Therefore, the basic copper carbonate contains alkali metal (Na or K) or alkaline earth metal (Mg or C).
In the case of containing a lot of impurities such as a) and anions (Cl ions and SO4 ions), it is preferable to wash easily soluble copper oxide obtained by thermal decomposition.

The present invention is also realized as a copper plating method which is a method of using easily soluble copper oxide, and the method comprises the step of forming the above-mentioned easily soluble copper oxide into an insoluble anode and a cathode to form a cathode. Is supplied as a copper plating material to the electrolytic solution provided with (a) and (b), and the object to be plated is subjected to copper plating.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a commercially available basic copper carbonate may be purchased as a raw material of easily soluble copper oxide, but in this embodiment, basic copper carbonate is not purchased. It will be manufactured at the factory side. FIG. 1 is an explanatory view showing a production flow in this case. For example, an aqueous solution of cupric chloride (CuCl2) having a copper concentration of 10% by weight and a carbonate of an alkali metal such as a carbonate having a carbonic acid concentration of 7% by weight. An aqueous solution of sodium (Na2 CO3) is charged into the reaction tank 1 so that the pH of the mixture becomes, for example, 7 to 9, and the stirring means 11 is heated while the mixture is heated to, for example, 70 ° C.
For 30 minutes, for example. The heating of the mixed solution is performed, for example, by providing a bubbling unit (not shown) such as a diffuser tube in the reaction tank 1 and bubbling vapor from the bubbling unit to the mixed solution.

The above reaction proceeds as follows. First, copper carbonate is generated as shown in equation (1), and Na2 CO3 + CuCl2 → CuCO3 + 2NaCl (1) Subsequently, as shown in equation (2), copper carbonate is hydrated to form a dihydrate of basic copper carbonate. CuCO 3 + 3 / 2H 2 O → 1/2 {CuCO 3 .Cu (OH) 2 .2H 2 O} +1/2 CO 2 (2) Further, as shown in the formula (3), water is removed from the above dihydrate to form an anhydrous base. Copper carbonate is produced.

CuCO 3 .Cu (OH) 2 .2H 2 O → CuCO 3 .Cu (OH) 2 + 2H 2 O (3) Thus, basic copper carbonate is precipitated and formed into a powder and precipitates. Then, the valve 12 is opened to extract the slurry as a precipitate and send it to the centrifugal separator 2, where the solid content is separated from the mother liquor by centrifugation, and the solid content is put into the dryer 3 to be dried. Obtain copper carbonate powder.

As a source of copper ions which is a raw material of the basic copper carbonate, an aqueous solution of a copper salt such as copper sulfate or copper nitrate can be used in addition to copper chloride. As a carbonate ion source, in addition to sodium carbonate, carbonates of alkali metals such as sodium hydrogen carbonate and potassium carbonate, carbonates of alkaline earth metals such as calcium carbonate, magnesium carbonate and barium carbonate or ammonium carbonate ((NH4) 2
CO3) can be used.

Next, the basic copper carbonate, which is a powder, is supplied to a heating furnace, for example, a rotary kiln 4 where, for example,
It is thermally decomposed by heating to a temperature of not less than 50 ° C and not more than 800 ° C. In this example, as a heating furnace, a rotating tube 41 made of, for example, stainless steel, which rotates around a tube axis as a rotating shaft, is provided at a slight angle, and the periphery of the rotating tube 41 is surrounded by a heater 42.
A rotary kiln that transfers the basic copper carbonate powder by rotating the rotary tube 41 is used. If the basic copper carbonate is heated in this way, the heating atmosphere does not become a reducing atmosphere. The reason that the basic copper carbonate is not directly heated by a burner is that, when a reducing atmosphere is used, the copper carbonate itself or the copper carbonate is decomposed into copper oxide, and then a part thereof is reduced to form a cuprous oxide (Cu
This is to avoid 2 O) and metallic copper (Cu).

When copper oxide is used as a copper plating material, metallic copper does not dissolve or is hardly dissolved in sulfuric acid which is an electrolytic solution, becomes an insoluble residue, and requires new filtration equipment. If metallic copper or cuprous oxide is produced, the amount of replenished copper in the plating bath will not be constant, and the quality of the plated product will vary. Therefore, it is necessary not to use a reducing atmosphere when heating the basic copper carbonate.

As for the heating temperature, copper oxide can be obtained by heating for about 2 hours at 250 ° C., for example, but not thermally decomposed at 200 ° C. At 220 ° C, it is necessary to heat at 250 ° C or higher because it is understood that thermal decomposition has not been completed even by differential thermal analysis. Is preferably 350 ° C. or higher. If the temperature exceeds 800 ° C., the solubility of the obtained copper oxide becomes small, so the temperature must be 800 ° C. or less. In order to obtain copper oxide having higher solubility, the temperature is preferably set to 600 ° C. or lower.

After the copper oxide is thus obtained, the copper oxide is put into a cleaning tank 5 containing pure water as a cleaning liquid, and the copper oxide is stirred by a stirring means 51 and washed with water. And the valve 52
Is opened, a mixed slurry of water and copper oxide is extracted from the washing tank 5, and water is removed by a centrifugal separator 6 or a filter, followed by drying by a dryer 7, thereby obtaining copper oxide as powder.
Pure water such as distilled water or ion-exchanged water can be used as the washing liquid, but water with less impurities than that,
For example, ultrapure water can be used.

FIG. 2 shows an example of an apparatus for performing a copper plating method using copper oxide as a replenishing material for a copper plating material. In FIG. 2, reference numeral 8 denotes a plating bath, which is filled with a plating bath obtained by dissolving copper oxide in sulfuric acid as an electrolytic solution, and is provided with an insoluble anode 81 such as a titanium plate connected to the positive electrode of the DC power source E. White metal platinum iridium 7:
3 is immersed in a material to be plated 82 such as a metal plate to be plated, which is a cathode connected to the negative electrode side of the DC power supply E. 83 is a dissolution tank,
When the amount of copper ions in the plating bath 8 decreases,
A copper oxide powder is supplied from a hopper 84 serving as a replenishing source to a melting tank 83.
After a predetermined amount is supplied to the inside, the mixture is stirred by the stirring means 85 and dissolved in sulfuric acid, and then the pumps P1 and P2 are operated to circulate the plating bath, and then the next copper plating treatment is performed. F is a filter.

According to the above example, the basic copper carbonate is
As can be seen from the examples described later, the obtained copper oxide has high solubility and is thermally decomposed at 50 to 800 ° C., and is not thermally decomposed in a reducing atmosphere. The generation of components that become insoluble residues is suppressed, and when copper oxide is used as a copper plating material, a load is hardly applied to the filter, and the concentration of copper ions in the copper plating bath is stabilized.

The basic copper carbonate contains anions and cations according to the raw materials. For example, an aqueous solution of cupric chloride (CuCl2) and sodium carbonate (Na2 CO3)
3) When using the aqueous solution as the raw material, Cl ion and Na
When ions are contained in the basic copper carbonate, for example, when cupric sulfate (CuSO4) is used instead of cupric chloride, Na
The ion and S of the SO4 ion body are included. S, Na, K of these Cl ions or SO4 ions
Although it can hardly be reduced and purified even if the basic copper carbonate is washed, as described in the examples below, when the basic copper carbonate is thermally decomposed into copper oxide and then washed, , These impurities can be reduced. Therefore, when used as a copper plating material, the time required for the impurity concentration to reach the upper limit in management becomes longer, so that the time required for building the bath becomes longer, and an increase in cost can be suppressed.

[0024]

EXAMPLES (Example 1-1) In the above embodiment, the basic copper carbonate was heated at 400 ° C. for about 60 minutes and thermally decomposed to obtain copper oxide.

(Example 1-2) In the above embodiment, the basic copper carbonate was heated at 600 ° C for about 60 minutes and thermally decomposed to obtain copper oxide.

(Example 1-3) In the above embodiment, the basic copper carbonate was heated at 700 ° C for about 60 minutes and thermally decomposed to obtain copper oxide.

(Example 1-4) In the above embodiment, the basic copper carbonate was heated at 750 ° C for about 60 minutes and thermally decomposed to obtain copper oxide.

(Example 1-5) In the above embodiment, the basic copper carbonate was heated at 800 ° C. for about 60 minutes and thermally decomposed to obtain copper oxide.

Comparative Example 1 In the above embodiment, the basic copper carbonate was heated at 900 ° C. for about 60 minutes and thermally decomposed to obtain copper oxide.

In order to determine the solubility when copper oxide was supplied to the copper plating bath as copper plating material, Example 1-1 was used.
1-5 and the copper oxide of Comparative Example 1 were added to 10 liters of a sulfuric acid aqueous solution having an H2 S04 concentration of 245 g / liter.
50 g was charged and dissolved. When the conductivity of the liquid in the dissolving process of each sample was measured, the results shown in FIG. 3 were obtained. FIG. 4 and FIG. 5 are graphs showing the results as a change with time of the conductivity. When the time when the value of the electrical conductivity becomes constant is defined as the end of dissolution, and the time from the introduction of the copper oxide powder to the end of the dissolution is measured and defined as the dissolution time, the dissolution time in each sample is as shown in FIG. is there. From these results, it can be seen that the solubility is high up to a temperature of 800 ° C. at the time of thermal decomposition of the basic copper carbonate, but the solubility becomes low at a temperature of 900 ° C. In addition, since the dissolving time becomes shorter as the temperature at the time of thermal decomposition decreases from 800 ° C. to 600 ° C. (the solubility becomes larger), the temperature may be lower than 800 ° C., for example, 600 ° C. or less. More preferred. It is considered that the reason that the higher the temperature is, the lower the solubility becomes, is that the solid phase sintering of copper oxide formed by decomposition proceeds. (Example 2) In the above embodiment, the basic copper carbonate was replaced with 4
It was heated at 00 ° C. for about 60 minutes and thermally decomposed to obtain copper oxide.

Comparative Example 2-1 Copper oxide was obtained in the same manner as in Example 2 except that a rotary kiln having a reducing atmosphere capable of directly heating with a burner was used.

(Comparative Example 2-2) Copper oxide was obtained in the same manner as in Example 2 except that the temperature of the thermal decomposition of basic copper carbonate was changed to 900 ° C.

550 g of the copper oxide of Example 2, Comparative Example 2-1 and Comparative Example 2-2 was added to and dissolved in 10 liters of a sulfuric acid aqueous solution having an H2S04 concentration of 245 g / liter. After the dissolution was completed, the solution was filtered and the amount of the undissolved residue remaining on the filter paper was measured. The result shown in FIG. 5 was obtained. From this result, when the basic copper carbonate is thermally decomposed in a reducing atmosphere, the amount of the insoluble residue is large, and when the basic copper carbonate is thermally decomposed at a high temperature of 900 ° C. without the reducing atmosphere, the amount of the insoluble residue is considerably smaller than that in the reducing atmosphere. This shows a high value, which indicates that according to the present invention, the amount of insoluble residue can be extremely reduced.

Example 3 In the above embodiment, the basic copper carbonate was heated at 400 ° C. for about 60 minutes and thermally decomposed to obtain copper oxide, which was washed under the following washing conditions, and before and after washing. The concentration of Na and Cl contained in ICP-AES
(Induction Plasma Emission Spectrometer) and a titrator gave the results shown in FIG. Washing conditions:
500 g of copper oxide powder is added to 4500 g of water, stirred for 10 minutes, and then filtered and washed with water. Washing with copper oxide powder 500g
5000 g of water was used. In the case of basic copper carbonate, the concentration of Na and Cl cannot be reduced by washing with water, but it can be seen that washing with copper oxide is very effective in reducing the concentration of impurities.

(Example 4) The chlorine concentration (Cl concentration) is about 2
Electroplating was carried out under the following conditions using 0 ppm of copper oxide as a copper supplement.

Electroplating conditions Anode: titanium coated with platinum group (Pt: Ir = 7: 3) Cathode: copper plate Electrode area: 10 cm × 10 cm Current density, current, voltage: 1 A / dm 2, 1A, 2,2 V Copper concentration 18 g / l as Cu Cu sulfuric acid concentration 180 g / l as H2 S04 The chlorine concentration in the plating bath at the start was adjusted to about 20 ppm. When copper oxide was supplied so as to keep the copper concentration constant, the chlorine concentration in the bath did not increase but instead decreased. Therefore, in order to keep the chlorine concentration in the bath constant, the chlorine content should be 5 to 5.
20 ppm / day is added. From this result, it is considered that the amount of chlorine generated from the anode is larger than the amount of chlorine contained in the supplied copper oxide. The surface of the finally obtained cathode was very flat and smooth.

(Comparative Example 4) Electroplating was carried out under the same conditions as in Example 4 above, using copper oxide having a chlorine concentration of about 140 ppm as a copper supplement.

The chlorine concentration in the plating bath at the start is about 20 p.
pm. When copper oxide was supplied to keep the copper concentration constant, an increase in chlorine concentration of 2-4 ppm / day occurred in the plating bath. This is considered to be because the amount of chlorine contained in the supplied copper oxide is larger than the amount of chlorine generated from the anode. After 40 days, the chlorine concentration in the plating bath was about 150 ppm. The surface of the finally obtained cathode was rougher than that of Example 4.

[0039]

As described above, according to the present invention, an easily soluble copper oxide having high solubility and capable of suppressing generation of an insoluble residue can be obtained. In addition, high-purity copper oxide can be obtained by washing the easily soluble copper oxide, and can be suitably used, for example, as a copper plating material in electrolytic plating. When electroplating is performed using this easily soluble copper oxide as a copper plating material, favorable plating treatment can be performed, and the time required to reach a building bath can be increased, thereby suppressing an increase in cost.

[Brief description of the drawings]

FIG. 1 is a process chart showing an embodiment of a method for producing a readily soluble copper oxide according to the present invention.

FIG. 2 is a configuration diagram showing an example of a plating apparatus used in the plating method of the present invention.

FIG. 3 shows the thermal decomposition temperature of basic copper carbonate as a parameter,
FIG. 3 is an explanatory diagram showing a change over time in conductivity when copper oxide is introduced into sulfuric acid as a table.

FIG. 4 is an explanatory diagram showing a change with time of the conductivity shown in FIG. 3 as a graph.

FIG. 5 is an explanatory diagram showing a change over time in the conductivity shown in FIG. 3 as a graph.

FIG. 6 is an explanatory diagram showing the dissolution time of copper oxide obtained at each pyrolysis temperature based on the results of FIG.

FIG. 7 is an explanatory diagram showing the relationship between the conditions for thermal decomposition of basic copper carbonate and the amount of insoluble residue.

FIG. 8 is an explanatory diagram showing a relationship between the presence / absence of water washing of copper oxide and an impurity amount.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Centrifuge 3 Dryer 4 Heating furnace 5 Cleaning tank 6 Centrifuge 7 Dryer 8 Electrolytic tank 81 Insoluble anode 82 Cathode to be plated 83 Melting tank 84 Hopper

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[Procedure amendment]

[Submission date] September 14, 2000
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Claims (8)

[Claims] 1. An easily soluble copper oxide, which is obtained by heating a basic copper carbonate to 250 ° C. to 800 ° C. in an atmosphere which does not become a reducing atmosphere and thermally decomposing the same to obtain easily soluble copper oxide. Production method. 2. A step of heating a basic copper carbonate to 250 ° C. to 800 ° C. in an atmosphere which does not become a reducing atmosphere to thermally decompose the same, thereby obtaining a readily soluble copper oxide. A method of producing easily soluble copper oxide, which comprises a step of washing with water. 3. The basic copper carbonate is mixed with an aqueous solution of copper chloride, copper sulfate or copper nitrate and an aqueous solution of an alkali metal, an alkaline earth metal or a carbonate of NH4 and reacted while heating. 3. The method for producing easily soluble copper oxide according to claim 1, wherein the obtained reaction product is obtained by filtration. 4. An easily soluble copper oxide produced by heating basic pyrocarbonate to 250 ° C. to 800 ° C. in an atmosphere which does not become a reducing atmosphere and thermally decomposing it. 5. An easily soluble copper oxide obtained by thermally decomposing basic copper carbonate by heating it to 250 ° C. to 800 ° C. in an atmosphere which does not become a reducing atmosphere, and then washing it with water. . 6. The basic copper carbonate is mixed with an aqueous solution of an alkali metal, an alkaline earth metal or a carbonate of NH4 and an aqueous solution of copper chloride, copper sulfate or copper nitrate and reacted while heating. The reaction product obtained by filtration and separation is obtained.
The easily soluble copper oxide as described. 7. A copper plating material supplied to an electrolytic solution provided with an insoluble anode and an object to be plated serving as a cathode, comprising a readily soluble copper oxide according to claim 4, 5 or 6. Copper plating material. 8. An easily soluble copper oxide according to claim 4, 5 or 6, which is supplied as a copper plating material to an electrolytic solution provided with an insoluble anode and an object to be plated serving as a cathode, and copper is added to the object to be plated. A copper plating method characterized by plating.