JPH0639714B2 - Chemical copper plating solution - Google Patents

Description

The present invention relates to a chemical copper plating solution used for forming a conductive film on a wiring board or the like.

[Conventional technology]

The conventional chemical copper plating solution used to form a conductor film on a printed wiring board by electroless plating is
Copper salts such as copper sulfate and copper acetate, complexing agents such as ethylenediaminetetraacetate and triamine, reducing agents such as formaldehyde, pH regulators such as sodium hydroxide, stabilizers such as dipyridyl, polyoxy It consists of an aqueous solution containing a nonionic surfactant such as an ethylene derivative.

The plating film deposited from these chemical copper plating solutions has appropriate flexibility. Therefore, the conductive film formed on the wiring board or the like by the same plating film has a feature that it is not easily broken by thermal stress or the like received during flow soldering.

[Problems to be solved by the invention]

However, this type of chemical copper plating solution has a slow plating film deposition rate, and it takes more than ten hours to project a copper plating film having a thickness of 20 μm as a conductor of a printed wiring board, for example. was there. From these things,
There has been a demand for a chemical copper plating solution that can obtain a plating film with appropriate flexibility and at the same time has a high plating film extrusion rate. However, a chemical copper plating solution that has these two features at the same time has not yet been obtained. Has not been done.

The inventors of the present invention have studied the above-mentioned conventional problems, and as a result, by combining a certain special surfactant, a copper plating film having an appropriate flexibility can be formed earlier than the conventional one. We focused on obtaining a copper plating solution. The present invention is based on this,
An object of the present invention is to enable a copper plating film having a required thickness, which is not easily broken, to be deposited in a short time in a soldering process or the like.

[Means for solving problems]

The chemical copper plating solution according to the present invention comprises an aqueous solution containing a copper salt, a complexing agent, a reducing agent, a pH adjusting agent, a stabilizer, and a surfactant. On the other hand, 1 to 50 mg of nonionic surfactant and 10 to 100 mg of fluorine surfactant are contained.

〔Example〕

 Next, an embodiment of the present invention will be described.

(Example 1) First, a degreased and cleaned alumina substrate and a stainless steel substrate,
Pretreatment liquid 1 and pretreatment liquid 2 and a chemical copper plating liquid were prepared.

It should be noted that the pretreatment liquid 1 is 50 g of tin chloride with respect to water 1,
It consists of an aqueous solution containing 10 ml of hydrochloric acid. Pretreatment 2 liquid is water 1
On the other hand, it consists of an aqueous solution containing 0.25 g of palladium chloride and 10 ml of hydrochloric acid. In addition, the chemical copper plating solution was prepared by adding 7.49 g of copper sulfate as a copper salt, 31.6 g of sodium ethylenediaminetetraacetate as a complexing agent, 6 g of sodium hydroxide as a PH adjusting agent, and formaldehyde (37% as a reducing agent) to 1 part of water.
Liquid) 8 cc, 2 to 2 dipyridyl 30 mg as a stabilizer, 1 mg of polyoxyethylene alkylphenyl ether as a nonionic surfactant, and 30 mg of potassium perfluoroalkylsulfonate as a fluorine surfactant. The PH value of this chemical copper plating solution is 25 ℃.
At 12.5.

The alumina substrate and the stainless steel substrate were immersed in pretreatment liquid 1 at room temperature, taken out after 3 minutes, washed with water, immediately immersed in pretreatment liquid 2 at room temperature, taken out after 3 minutes and washed with water. Next, this substrate was immersed in a chemical copper plating solution kept at 70 ° C. Immediately, copper began to break out on the board surface. The substrate was left in the plating solution, and after 1 hour, it was taken out, washed with water and dried.

Then, the film thickness of the copper plating film projected on the alumina substrate was measured by a commercially available plating film thickness meter (SFT-156). The results are shown in the table as the deposition rate Cs of the copper plating film per unit time.

In addition, in order to examine the flexibility of the copper plating film, the copper plating film deposited on the surface of the stainless steel substrate was cut into a rectangle of 2 cm x 5 cm, and the copper foil was taken out. Then, this copper foil was completely folded in two, and a bending test of returning it to its original state was repeated until a crack was formed at the fold, and the number of cycles Bs when the crack was generated is shown in the table.

(Example 2) In Example 1, the concentration of polyoxyethylene alkylphenyl ether, which is a nonionic surfactant in the chemical copper plating solution, was changed from 1 mg / to 50 mg /, and a fluorine-based surfactant was used. A copper plating film was deposited on two kinds of substrates under the same method and conditions as in Example 1, except that potassium perfluoroalkyl sulfonate was changed from 30 mg / to potassium perfluoroalkylcarboxylate to 80 mg /.

Further, the thickness of the plated film and the bending test were conducted in the same manner as in Example 1 above, and the results are shown in the table.

(Example 3) In Example 1, the nonionic surfactant in the chemical copper plating solution was changed from 1 mg / of polyoxyethylene alkyl phenyl ether to 5 mg / of polyoxyethylene alkyl ether, and a fluorine-based interface. Concentration of activator potassium perfluoroalkylsulfonate 30 mg /
The copper plating film was deposited on two kinds of substrates by the same method and conditions as in Example 1 except that the amount was changed to 100 mg /.

Further, the thickness of the plated film and the bending test were conducted in the same manner as in Example 1 above, and the results are shown in the table.

(Example 4) In Example 1, the nonionic surfactant in the chemical copper plating solution was changed from polyoxyethylene alkylphenyl ether 1 mg / to polyoxyethylene alkyl ether.
The same method and conditions as in Example 1 were used except that the amount of the fluorosurfactant was changed to 40 mg /, and the fluorine-based surfactant was changed from potassium perfluoroalkylsulfonate of 30 mg / to ammonium perfluoroalkylsulfonate of 40 mg /. A copper plating film was deposited on the seed substrate.

Further, the thickness of the plated film and the bending test were conducted in the same manner as in Example 1 above, and the results are shown in the table.

(Comparative Example) In Example 1, the nonionic surfactant in the chemical copper plating solution was changed from polyoxyethylene alkylphenyl ether 1 mg / to polyoxyethylene alkylphenyl ether 100 mg, and fluorine-based surfactant was used. A copper plating film was deposited on an alumina substrate and a stainless steel substrate by the same method and conditions as in Example 1 except that the plating solution was not included.

Further, the thickness of the plated film and the bending test were conducted in the same manner as in Example 1 above, and the results are shown in the table.

As is clear from the results summarized in the table, in the copper plating solutions of Examples 1 to 4, the nonionic surfactant and the fluorine-based anionic surfactant were both dissolved in the chemical copper plating solution. The deposition rate of the plated film is faster than that of the comparative example using only the nonionic surfactant. Also, in the bending test, the plated films obtained in the above-mentioned examples were able to withstand more bending than those obtained in the comparative examples.

As shown in the above Examples, the nonionic surfactant is a polyoxyethylene derivative, and the fluorine surfactant is a perfluoroalkyl sulfonate or a perfluoroalkyl carboxylate. Is desirable. If these nonionic surfactants and fluorine-based surfactants are both contained in the plating solution within the above range,
The plating film deposition rate is fast and the deposited plating film is highly flexible.

The reason for limiting the ratio of the surfactant to be melted in the chemical copper plating solution as described above is as follows.

When the ratio of the nonionic surfactant contained in the plating solution together with the fluorine-based surfactant is less than 1 mg relative to 1 part of water, the deposited copper plating film becomes brittle and cracks are likely to occur in the soldering process or the like. On the contrary, a chemical copper plating solution having a concentration of more than 50 mg / s is not preferable because the deposition rate of the copper plating film becomes slow.

On the other hand, when the concentration of the fluorine-based surfactant contained in the plating solution together with the nonionic surfactant is less than 10 mg with respect to 1 part of water, the copper plating film that has been extruded becomes brittle, and it may become It is not preferable because it easily cracks. On the other hand, if it exceeds 100 mg /, the protruding speed of the copper-plated film will be drastically reduced.

〔The invention's effect〕

As described above, according to the chemical copper plating solution of the present invention,
Similar to the case of using the conventional chemical copper plating solution, a flexible copper plating film can be projected in about 5 to 1/6 the time of the conventional case. Therefore, by the electroless plating method,
The effect that the conductor can be formed on the printed wiring board or the like in a short time is obtained.

Claims (4)

[Claims] 1. A copper salt, a complexing agent, a reducing agent, and a pH adjusting agent,
In a chemical copper plating solution composed of an aqueous solution containing a stabilizer and a surfactant, 1 to 50 mg of a nonionic surfactant and 1 to 50 mg of a fluorine-based surfactant are used as surfactants in water.
A chemical copper plating solution containing 10 to 100 mg. 2. The chemical copper plating solution according to claim 1, wherein the nonionic surfactant is a derivative of polyoxyethylene. 3. The chemical copper plating solution according to claim 1 or 2, wherein the fluorine-based surfactant is a perfluoroalkyl sulfonate. 4. The chemical copper plating solution according to claim 1 or 2, wherein the fluorine-based surfactant is a perfluoroalkylcarboxylic acid salt.