JPH09137298A - Production of replenishing liquid for copper electroplating and copper electroplating method by using this replenishing liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of nodule, gritty texture, etc., by adding a part of a plating liquid to a liquid mixture composed of superfine powder of copper oxide and medium, dissolving the copper oxide to prepare a plating replenishing liquid, subjecting this liquid to circulation filtration with an ultrafilter device at the time of use and supplying the liquid to a plating cell at the time of using the copper oxide as a plating source in order to attain a precise plating and decrease a plating cost. SOLUTION: The fine powder of copper oxide sized 5 to 50μm is first mixed with water, acid, alkali or org. solvent, etc., in order to improve the solubility of the copper oxide as the means for adjusting the plating replenishing liquid. The mixture is then subjected to ultrafine grinding by using a wet type ultrafine grinding machine until <=5μm grain size is attained. The copper oxide in the form of the ultrafinely ground liquid state is mixed with the plating liquid withdrawn from the plating cell and is dissolved under stirring. The liquid is then subjected to circulation filtration with a filter device having an ultrafilter membrane, by which a slight amt. of the remaining undissolved particles are removed. Only the copper-component is supplied to the plating cell. The pore diameter of the ultrafilter membrane is preferably specified to <=0.01μm.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a replenisher for electrolytic copper plating and a method for electrolytic copper plating using the replenisher.

[0002]

2. Description of the Related Art Conventionally, copper sulfate solution or metallic copper has been used as a copper source for electroless copper plating or electrolytic copper plating, but in recent years, particularly in electroless copper plating, sulfate ion and sodium Depending on the reaction, sodium sulfate (Na ₂ SO ₄ )
As the elongation rate and tensile strength of the deposited copper foil decrease due to the formation and accumulation of the above, as a method of not producing such a side reaction product, as disclosed in JP-B-59-32542, there is no hydroxylation. It has been proposed to use copper, copper oxide, copper carbonate, copper oxychloride and the like as a copper source.

On the other hand, in electroplating, electroplating using a horizontal insoluble electrode is desired in accordance with recent demands for precise plating and cost reduction. As the copper source, carbon dioxide is used instead of the electrolytic copper melting method. Copper sources such as copper and copper oxide have been proposed. However, since copper oxide is generally difficult to dissolve,
It is necessary to make fine powder, and also in the melting method, since undissolved copper oxide fine particles flow into the plating tank to cause product defects such as generation of nodules and roughness, JP-A-6-25863 and JP-A-6-25863. As disclosed in Japanese Patent Laid-Open No. 4-225826, a supply system has been proposed in which a powder of copper oxide is directly added to a dissolution tank, strongly stirred, and then filtered.

[0004]

When copper oxide is used as a copper source for plating, common problems are a method of improving the solubility of copper oxide and prevention of inflow of ultrafine powder that cannot be dissolved instantly into a plating tank. There is a method, moreover finely powdered copper oxide,
There are problems such as contamination of the work environment due to scattering from the container during transfer or dissolution, and blockage due to blocking in the container or transfer pipe, and improvement in handleability and usability has been desired.

[0005]

The method for producing a replenisher for electrolytic copper plating according to the present invention comprises mixing 5 to 50 .mu.m of copper oxide powder with water, an acid, an alkaline solution or an organic solvent, and adding the solution in the mixed solution. The copper oxide powder is pulverized by a wet pulverizer into fine powder having a particle size of 5 μm or less, and a part of the plating solution is added to the fine powder mixed solution to dissolve the copper oxide.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as means for improving the solubility of copper oxide, fine powder of copper oxide of 5 to 50 μm is used, and water or alcohols such as methanol and ethanol, fatty acids and esters thereof are used. Stir-mix with other suitable alkali, acid solution, solvent, etc., and then use a wet type super pulverizer capable of high speed rotation to obtain a particle size of 5
It is to carry out ultra-fine pulverization so that it becomes less than or equal to μm.

Next, this ultrafine powdered liquid copper oxide is supplied to a mixing and dissolving tank by a pump or the like, mixed with a part of the plating solution extracted by the plating tank, and dissolved in the plating solution while stirring. . Furthermore, it is preferable that the solution is circulated and filtered by an ultrafiltration device equipped with an ultrafiltration membrane, the membrane containing only the dissolved copper component is permeated, and the solution is supplied to the plating tank.

In general, the dissolution rate of a substance is a condition in which the particle size and the specific surface area of the substance to be dissolved are particularly important in addition to the physical properties peculiar to the substance, the temperature and the concentration, the mixing stirring strength and the like. Therefore, pulverization is the best method for improving the dissolution rate. In the present invention, 5 to 50 μm of copper oxide is mixed with pure water, and then finely pulverized to 5 μm or less, preferably 1 μm or less with a flow tube type wet ultrafine pulverizer. This method also
The finer the powder, the easier it is to scatter, and the growth of pseudo-particles due to aggregation is prevented, and by being a liquid fine powder, it is compared with the addition of fine powder as it is to the plating solution. The dispersibility in the plating solution is much better and the dissolution rate is increased. However, even if it is pulverized, it is difficult to instantaneously dissolve the crystal particles in the plating solution. Therefore, the slightly present fine particles are filtered by an ultrafiltration membrane to allow only dissolved copper ions to pass through. Here, the filtration method using the ultrafiltration membrane is such that the solid matter in the solution to be filtered is slid on the membrane surface as compared with the hollow fiber type, the tubular type, the flat membrane type, etc. It is important to use a so-called cross-flow method that flows in the vertical direction, and the problem of blockage that occurs in a general membrane filter can be largely avoided. In particular, the blockage in the filtration of the electroless plating solution can avoid the situation where the copper oxide powder is reduced and the plating becomes impossible. Further, the pore size of the ultrafiltration membrane is usually said to be 0.005 to 1 μm, but preferably the pore size is 0.01 μm or less, and undissolved copper oxide fine particles in the course of dissolution are not permeated, so that they are not mixed in the mixing and dissolution tank. It is returned and repeatedly circulated through the ultrafiltration membrane to gradually dissolve.

[0009]

EXAMPLES Examples will be described below with reference to FIG. First,
20 parts of granular copper oxide powder 1 having an average particle diameter of 5 μm and 80 parts of pure water 2 are mixed by stirring, and this mixed solution 3 is metered by a metering pump 4
At 1500 rpm using zirconia beads
The liquid was pulverized while being circulated by the wet type ultrafine pulverizer 5 of the distribution tube type. As a result, the copper oxide powder has an average particle diameter of 0.2 μm.
And became a fine powder, and the mixed solution became a highly viscous solution 6.
In order to use this liquid copper oxide 6 as a copper source for electroless plating for manufacturing a printed wiring board, a part of the plating solution 8 in the electroless plating tank 7 is extracted by a pump 9 and mixed in a mixing and dissolving tank 10. This mixed plating solution 11 is used as an SLP-1 which is a hollow fiber type ultrafiltration membrane 13 by an ultrafiltration circulation pump 12.
The solution was passed through 053 (trade name, manufactured by Asahi Kasei Kogyo Co., Ltd.) at an average pressure of 2.5 kg / cm ² . As a result, the copper oxide fine powder that could not be dissolved slightly instantaneously was filtered off, and the dissolved copper oxide was able to pass through the filtration membrane as copper ions and be supplied to the plating tank as the plating solution 14. Undissolved copper oxide particles are returned to the mixing and dissolving tank with a part of the plating solution,
It was able to dissolve gradually. Further, regarding electroplating, only the composition of the plating solution and the plating method are different, and the fundamental dissolution and supply method can be the same method.

[0010]

EFFECT OF THE INVENTION Although the effect of using copper oxide for plating has been conventionally recognized, nodule and roughness are generated on a plated product due to poor solubility and insoluble fine powder flowing into the plating tank. There were problems, and there were problems such as poor storability, transportability, and handleability. As a result of the present invention,
By liquefying copper oxide and pulverizing it, and filtering this liquid copper oxide by an ultrafiltration method, these problems could be almost solved. In this method, since the whole amount of the plating solution is ultrafiltered, fine foreign substances that adversely affect the plating characteristics can be concentrated and removed in the mixing and dissolving tank.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention.

[Explanation of symbols]

 1 Copper oxide powder 2 Pure water 3 Mixed solution 4 Metering pump 5 Wet ultrafine pulverizer 6 Liquid ultrafine copper oxide 7 Electroless plating tank 8 Electroless plating solution 9 Electroless plating solution drawing pump 10 Mixing dissolution tank 11 Mixed plating Liquid 12 Ultrafiltration circulation pump 13 Ultrafiltration membrane 14 Permeation plating liquid 15 Printed wiring board

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Suemitsu 3-1-2 Kanda Surugadai, Chiyoda-ku, Tokyo Hitsukasei Techno Plant Co., Ltd.

Claims (2)

[Claims] 1. A copper oxide powder of 5 to 50 μm is mixed with water, an acid, an alkaline solution or an organic solvent, and the copper oxide powder in this mixed solution is pulverized by a wet pulverizer into fine powder having a particle diameter of 5 μm or less. A method for producing a replenisher for electrolytic copper plating, which comprises adding a part of a plating solution to the fine powder mixed solution to dissolve copper oxide. 2. Water, an acid, an alkaline solution or an organic solvent is mixed with 5 to 50 μm of copper oxide powder, and the copper oxide powder in this mixed solution is pulverized by a wet pulverizer into fine powder having a particle size of 5 μm or less. A method of electrolytic copper plating, which comprises adding a part of a plating solution to the mixed solution of fine powder, dissolving copper oxide, and supplying the dissolved copper component to a plating tank using an ultrafiltration membrane.