JPH0499285A - Surface treatment of copper and copper alloy - Google Patents

Abstract

PURPOSE:To improve the solderability of copper by forming a heat resistant chemical coating film based on alkylbenzimidazole compds. on the surface of the copper. CONSTITUTION:An aq. soln. contg. an org. acid, 2-alkyl-4-methylbenzimidazole and 2-alkyl-5-methylbenzimidazole compds. represented by general formulae I, II (where R1 is >=23C alkyl) is brought into contact with the surface of copper to carry out surface treatment. By this treatment, a chemical coating film having superior heat resistance can be formed on the surface of the copper. This treatment is especially suitable for use as the prefluxing treatment of the circuit parts of hard and flexible printed circuit boards.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for forming a chemical conversion film with excellent heat resistance on the surface of copper and copper alloys, and particularly relates to a method for forming a chemical conversion film with excellent heat resistance on the surface of copper and copper alloys, and in particular for forming circuits on rigid printed wiring boards and flexible printed wiring boards. The present invention provides a method suitable for preflux treatment of parts.

Conventional technology A surface treatment method for forming a film of a 2-position long-chain alkylimidazole compound on the surface of copper or copper alloy was developed in the Japanese Patent Publication Publication No. 4
No. 6-17046, No. 48-11454, No. 48-2
No. 5621, No. 49-1983, No. 49-26183
No. 58-22545, No. 61-41988, and Japanese Unexamined Patent Publication No. 61-90492.

In addition, as a method for forming a chemical conversion film of a henzimidazur compound on the surface of copper or copper alloy, JP-A-58-5
No. 01281 discloses a treatment using 5-methylbenzimidazole.

Problems to be Solved by the Invention In recent years, surface mounting methods have been increasingly adopted as a method for bonding electronic components to printed wiring boards. Due to mixed mounting, printed wiring boards are now exposed to high temperatures.

However, conventionally known chemical conversion coatings of 2-position long-chain alkylimidazole formed on copper circuits are stable at around room temperature, but discolor at high temperatures, and there is a risk that they may interfere with soldering. was there.

Furthermore, in the surface treatment method described in JP-A-58-501281, since 5-methylbenzimidazole is relatively easily soluble in water, it is possible to form a chemical conversion film with a thickness of 0.08 μm or more, which is considered to be a preferable film thickness. Therefore, it was difficult to fulfill the role of protecting the base during heating.

Thus, in response to the surface mounting method of printed wiring boards, it has been desired to form a preflux coating with better heat resistance on the surface of copper metal.

Means for Solving the Problems In view of the above circumstances, the inventors of the present invention have conducted intensive tests and found that 2-alkyl-4-methylbenz represented by the following general formula I is added to the surface of copper or copper alloy. Both an imidazole compound and a 2-alkyl-5-methylbenzimidazole compound represented by the following general formula (hereinafter referred to as a 2-alkyl-methylbenzimidazole mixture) (hereinafter referred to as a margin) (However, in the formula, R1 has 3 or more carbon atoms. (indicates an alkyl group)
The present inventors have discovered that a chemical conversion film with excellent heat resistance can be obtained by contacting an aqueous solution containing an organic acid and an organic acid, and have completed the present invention.

Representative 2-alkyl-methylbenzimidazole mixtures used in the practice of the invention include 2-propyl-4-methylbenzimidazole 72-
mixture of propyl-5-methylbenzimidazole, 2
-Mixture of butyl-4-methylbenzimidazole and 2-butyl-5-methylbenzimidazole, 2-benziru-4-methylbenzimidazole and 2-benziru-5
-Mixture of methylbenzimidazole, 2-hexyl-
Mixture of 4-methylbenzimidazole and 2-hexyl-5-methylbenzimidazole, 2-hebutyl-4-
Mixture of methylbenzimidazole and 2-7'thyl-5-methylbenzimidazole, Mixture of 2-octyl-4-methylbenzimidazole and 2-octyl-5-methylbenzimidazole L 2-nonyl-4-methylbenzimidazole and 2-nonyl-5-methylbenzimidazole; a mixture of 2-undecyl-4-methylbenzimidazole and 2-undecyl-5-methylbenzimidazole; - mixtures of methylbenzimidazole and their salts.

2-alkyl-4-methylbenzimidazole compounds can be easily obtained by heating and condensing 2,3-diaminotoluene with the corresponding carboxylic acid. It can be easily obtained by heating and condensing diaminotoluene and the corresponding carboxylic acid. By mixing the 2-alkyl-4-methylbenzimidazole compound and the 2-alkyl-5-methylbenzimidazole compound obtained individually by the above method in a ratio of 2:8 to 8:2,
The 2-alkyl-methylbenzimidazole mixture used in the process of the invention is obtained.

Also, by reacting a mixture of 2,3-diaminotoluene and 3,4-diaminotoluene with a carboxylic acid,
The 2-alkyl-methylbenzimidazole mixture used in the process of the invention can be easily obtained.

However, when using a 2-alkyl-methylbenzimidazole mixture having an alkyl group with fewer than 3 carbon atoms, a part of the chemical conversion film formed on the surface of copper metal tends to be eluted; 2- with an alkyl group
When an alkyl-methylbenzimidazole mixture is used, a large amount of organic acid is required when dissolving the 2-alkyl-methylbenzimidazole mixture to prepare a treatment solution. A mixture of imidazole and 2-pentyl-5-methylbenzimidazole, a mixture of 2-1-xyl-4-methylhenzimidazole and 2-hexyl-5-methylbenzimidazole, a mixture of 2-hebutyl-4-methylbenzimidazole and 2- A mixture of heptyl-5-methylbenzimidazole, a mixture of 2-octyl-4-methylbenzimidazole and 2-octyl-5-methylbenzimidazole, a mixture of 2-nonyl-4-methylbenzimidazole and 2-
Particularly preferred are mixtures of nonyl-5-methylbenzimidazole, mixtures of 2-undecyl-4-methylbenzimidazole and 2-undecyl-5-methylbenzimidazole, and salts thereof.

The mixing ratio of 2-alkyl-4-methylbenzimidazole and 2-alkyl-5-methylbenzimidazole was 2.
The chemical conversion coating on the metal surface when treated in the range of :8 to 8:2 has excellent solder wettability.

In carrying out the method of the present invention, a 2-alkyl-methylbenzimidazole mixture is added to water in a proportion of 0.01 to 5%, preferably 0.1 to 2%. For dissolution, an organic acid may be added to render the 2-alkyl-methylbenzimidazole mixture into a water-soluble salt.

The organic acids used in carrying out the method of the present invention include:
Formic acid, acetic acid, lactic acid, propionic acid, capric acid, glycolic acid, acrylic acid, benzoic acid, paranitrobenzoic acid,
Parabutylbenzoic acid, paratoluenesulfonic acid, picric acid, salicylic acid, -monotoluic acid, oxalic acid, succinic acid,
Maleic acid, fumaric acid, tartaric acid, adipic acid, etc. are included in the range of 0.01 to 15%, preferably 0.01% to 15% based on water.
It may be added at a rate of 2 to 5%.

To carry out the method of the present invention, the surface of copper or copper alloy is subjected to treatments such as polishing, degreasing, soft etching, and acid cleaning, and then the metal surface is immersed in a treatment solution or the metal surface is coated with a treatment solution. It can be applied or sprayed.

In the method of the present invention, the step of bringing an aqueous solution containing a 2-alkyl-methylbenzimidazole mixture and an organic acid into contact with the surface of copper or a copper alloy involves controlling the temperature of the aqueous solution to about 20°C.
C to 60'C and the contact time is from 1 second to several minutes.

The present inventors conducted an attempt to impart further heat resistance to the chemical conversion film of the 2-alkyl-methylbenzimidazole mixture formed on the metal surface in the method of the specific invention, and found that the 2-alkyl-methylbenzimidazole mixture and Achieving the desired purpose by a method in which an aqueous solution containing an organic acid and at least one of a zinc compound or a copper compound is brought into contact with the surface of copper or copper alloy (hereinafter referred to as "-step treatment method"). I can do it.

Furthermore, the heat resistance of similar chemical conversion coatings can be further improved by contacting the surface of copper or copper alloy with an aqueous solution containing a 2-alkyl-methylbenzimidazole mixture and an organic acid, and then applying at least It can also be obtained by a method of contacting an aqueous solution containing either a zinc compound or a copper compound (hereinafter referred to as "two-stage treatment method").

Typical zinc compounds that can be used in these methods include zinc oxide, zinc formate, zinc acetate, zinc oxalate, zinc lactate, zinc citrate, zinc benzoate, zinc salicylate, zinc sulfate, and zinc nitrate. , zinc phosphate, etc. Typical copper compounds include cuprous chloride,
These include dichloride, copper hydroxide, copper phosphate, copper acetate, copper sulfate, copper nitrate, copper bromide, etc., all of which have a concentration of 0.02 to 0.02 to water.
It may be added at a rate of 10%, preferably 0.1 to 5%.

Further, in this case, it is preferable to stabilize the pH of the solution by adding an organic acid, an inorganic acid, and a buffering substance such as aqueous ammonia or amines to the aqueous solution containing the zinc compound or copper compound.

The one-stage treatment method of the present invention is carried out in exactly the same manner as in the specified invention, except that at least one of a zinc compound or a copper compound is added to an aqueous solution containing a 2-alkyl-methylbenzimidazole mixture and an organic acid. It can be carried out.

Furthermore, in the two-stage treatment method of the present invention, after an aqueous solution containing a 2-alkyl-methylbenzimidazole mixture and m6 is brought into contact with the surface of copper or a copper alloy, the metal surface on which a chemical conversion film has been formed is coated with at least a zinc compound or copper. About 20°C to 60°C to an aqueous solution containing any one of the compounds.
It may be immersed at a temperature of 5 seconds to several minutes.

The method of the present invention can also be carried out by adding two or more kinds of zinc compounds, copper compounds, nickel compounds, and cobalt compounds to the specified invention.

Furthermore, in carrying out the method of the present invention, it is also possible to form a two-layer structure of thermoplastic resin on the chemical conversion film to improve heat resistance.

That is, after forming a chemical conversion film of a 2-alkylmethylbenzimidazole mixture on the surface of copper or copper alloy, rosin, rosin derivatives such as rosin ester, terpene resin,
Thermoplastic resins with excellent heat resistance consisting of terpene resin derivatives such as terpene phenol resins and hydrocarbon resins such as aromatic hydrocarbon resins, aliphatic hydrocarbon resins, and alicyclic hydrocarbon resins are mixed with toluene, ethyl acetate, and IPA. etc.) and apply it uniformly and evenly onto the chemical conversion coating using a roll coater method or the like to a thickness of 1 to 30μ, preferably 2 to 20μ, to separate the chemical conversion coating and thermoplastic resin. A two-layer structure may be formed.

Effect: Water containing 2-alkyl-methylbenzimidazole mixture and organic acid on the surface of copper or copper alloy? g't&
When brought into contact with each other, a copper complex is locally formed due to the complex formation reaction between the 2-alkyl-methylbenzimidazole mixture and copper and the effects of hydrogen bonding and van der Waals forces between the 2-alkyl-methylbenzimidazole mixture. A conversion coating of a 2-alkylmethylbenzimidazole mixture is formed on the copper surface.

When the chemical conversion film formed in this way is left or heated, copper migrates from the copper surface, and most of the 2-alkyl-methylbenzimidazole mixture becomes a 2-alkyl-methylhenzimidazole copper complex. , 2-alkyl-methylbenzimidazole contains a conjugated Hensen ring, and is therefore considered to be thermally stable.

When a chemical conversion film made of a mixture of 2-alkyl-4-methylbenzimidazole and 2-alkyl-5-methylbenzimidazole is formed on the surface of copper metal, the solder A chemical conversion film with excellent wettability can be obtained, but the reason for this is not clear.

When the surface of copper or copper alloy is brought into contact with an aqueous solution containing a 2-alkyl-methylbenzimidazole mixture and an organic acid, and then the treated metal surface is brought into contact with an aqueous solution containing a zinc compound, an aqueous solution containing a zinc compound is formed. Zinc is incorporated into the conversion coating, and although some 2-alkyl-methylbenzimidazur copper complexes are included, the majority is 2-alkyl-methylbenzimidazole, which is much more thermally stable than copper complexes.
It is thought that heat resistance is improved because a chemical conversion film consisting of a methyl-dzimidazur zinc complex is further formed.

When the surface of copper or copper alloy is brought into contact with an aqueous solution containing a 2-alkyl-methylbenzimidazole mixture, an organic acid, and a zinc compound, in the process of forming a conversion film of 2-alkyl-methylbenzimidazole on the metal surface. , since zinc is incorporated into the conversion coating to form a 2-alkyl-methylbenzimidazole zinc complex;
It is thought that the heat resistance of the chemical conversion coating is improved.

In addition, when the surface of copper or copper alloy is brought into contact with an aqueous solution containing a 2-alkylmethylbenzimidazole mixture, an organic acid, and a copper compound, a chemical conversion film of 2-alkylmethylbenzimidazole is formed on the metal surface. In this method, copper ions in the aqueous solution promote the formation of a 2-alkyl-methylbenzimidazole copper complex, increasing the rate of formation of the chemical conversion film.

Supplying copper ions from an aqueous solution to the conversion coating produces a homogeneous conversion coating of 2-alkyl-methylbenzimidazole copper complexes and reduces the proportion of uncomplexed 2-alkyl-methylbenzimidazole in the conversion coating. It is thought that the heat resistance of the chemical conversion coating is improved due to the Q factor.

EXAMPLES The following examples and comparative examples demonstrate the method of the present invention in detail.
2.Explain.

In addition, in these tests, the thickness of the chemical conversion coating on the metal surface was determined by immersing a test piece of a predetermined size in a 0.5% hydrochloric acid aqueous solution, extracting the penzimidadur compound, and measuring it with an ultraviolet spectrophotometer. The concentration of imidazoles contained in this extract was measured using the method, and was converted into the thickness of the chemical conversion film.

The solder wetting time is measured using a test piece (5mm x 50
After degreasing a copper plate (mm x 0.3 mm) and then soft etching, it was treated with each treatment solution and heat treated, and immediately before measurement, it was coated with PostFranks [trade name rJS-64].
solder wettability tester (SAT).
The measurement conditions were a solder temperature of 240'C, an immersion depth of 2 mm, and an immersion speed of 16 mm/sec.

Example 1 A copper plate test piece that had been degreased and soft-etched was treated with 0.2-pentyl-4-methylbenzimidazole.
5%, 2-pentyl-5-methylbenzimidazole 0
．． It was immersed in an aqueous solution containing 5% zinc acetate, 2.5% acetic acid, and 0.5% zinc acetate at a temperature of 50°C for 45 seconds, and was then taken out and washed with water.

The thickness of the chemical conversion coating on the surface of the test piece thus obtained was 0.15 μm.

Immediately after treatment of the test piece subjected to the above treatment and 9
Items left at room temperature for 6 hours and temperature 60°C 1 humidity 9
For each of those heated for 96 hours in a constant temperature and humidity chamber at 5% RH, 10
The solder wettability was measured when heated for 1 minute, and the solder wetting time was as shown in Table 1.Example 2 A copper plate test piece that had been degreased and soft etched was
．． 2%, 2-hebutyl-5-methylbenzimidazole 0.8%, formic acid 6.0% and zinc acetate 1.5% for 12 seconds at a temperature of 40°C, taken out and washed with water.

The thickness of the chemical conversion coating on the surface of the test piece thus obtained was 0.16 μm, and the results of the solder wettability test are shown in Table 2.
It was as shown in

Example 3 A copper plate test piece that had been degreased and soft etched was treated with 2-nonyl-4-methylbenzimidazole 0.3
%, 2-nonyl-5-methylbenzimidazole 0.2
%, formic acid 5.0% and zinc acetate 0.8% for 10 seconds at a liquid temperature of 40°C, taken out and washed with water.

The thickness of the chemical conversion coating on the surface of the test piece thus obtained was 0.20 μm. 0.
35%, 2-octyl-5-methylbenzimidazole 0.15%, formic acid 4.0% and zinc acetate 0.8% for 13 seconds at a liquid temperature of 40''C, taken out and washed with water.

The thickness of the chemical conversion coating on the surface of the test piece thus obtained was 0.20 μm, and the results of the solder wettability test are shown in Table 4.
It was as shown in

Example 5 A disk test piece that had been degreased and soft etched was treated with 2-undecyl-4-methylbenzimidazole 0.
．． The sample was immersed in an aqueous solution containing 0.03%, 2-undecyl-5-methylbenzimidazole, 0.07%, acetic acid, 9.2%, and zinc chloride at a temperature of 40° C. for 60 seconds, and was taken out and washed with water.

The thickness of the chemical conversion coating on the surface of the test piece thus obtained was 0.18 μm, and the results of the solder wettability test are shown in Table 5.
It was as shown in

Table 5 Solder wettability (unit: seconds) Table 6 Solder wettability (unit: seconds) Example 6 A plate test piece that had been degreased and soft-etched was coated with 2-benzene-4-methylbenzimidazole 0.
2%, 2-benziru-5-methylbenzimidazole 0
．． The sample was immersed in an aqueous solution containing 8% acetic acid, 2.5% acetic acid, and 0.5% fI chloride at a temperature of 50°C for 18 seconds, then taken out and washed with water.

The thickness of the chemical conversion coating on the surface of the test piece thus obtained was 0.18 μm, and the results of the solder wettability test are shown in Table 6.
It was as shown in

Example 7 A copper plate test piece that had been degreased and soft-etched was treated with 0.2-heptyl-4-methylbenzimidazole.
64%, 2-hebutyl-5-methyl-nzimidazole 0.16%, formic acid 6.0% and copper acetate 0.2%, immersed in an aqueous solution containing 64%, 2-hebutyl-5-methyl-nzimidazole 0.16%, formic acid 6.0% and copper acetate 0.2% for 8 seconds at a temperature of 50"C, taken out and washed with water. did.

The thickness of the chemical conversion coating on the surface of the test piece thus obtained was 0.26 μm, and the results of the solder wettability test are shown in Table 7.
It was as shown in

Table 7 Solder wettability (unit: seconds) Table 8 Solder wettability (unit: 5 seconds) Example 8 A copper plate test piece that had been degreased and soft etched was treated with 2-nonyl-4-methylbenzimidazole 0.1
2%, 2-nonyl-5-methylbenzimidazole 0.
The sample was immersed in an aqueous solution containing 0.8% acetic acid, 5.0% acetic acid, and 0.1% cupric chloride at a temperature of 50°C for 7 seconds, then taken out and washed with water.

The thickness of the chemical conversion coating on the surface of the test piece thus obtained was 0.28 μm, and the results of the solder wettability test are shown in Table 8.
It was as shown in

Example 9 A copper plate test piece that had been degreased and soft-etched was treated with 0.07% of 2-undecyl-4-methyl-nzimidazole, 0.03% of 2-undecyl-5-methylbenzimidazole, and 9.2% of acetic acid. % and fernic chloride w40.
It was immersed in an aqueous solution containing 2% for 30 seconds at a temperature of 40°C, taken out, and washed with water.

The thickness of the chemical conversion coating on the surface of the test piece thus obtained was 0.18 μm, and the results of the solder wettability test are shown in Table 9.
It was as shown in

Example Work 0 A copper plate test piece that had been degreased and soft etched was treated with 2-heptadecyl-4-methylbenzimidazole 0.06%, 2-heptadecyl-5-methylbenzimidazole 0.04%, acetic acid is, s%, and acetic acid. Copper 0.3%
The sample was immersed in an aqueous solution containing the following for 50 seconds at a temperature of 40'C, taken out and washed with water.

The thickness of the chemical conversion coating on the surface of the test piece thus obtained was 0.20 μm. 0.
6%, 2-pentyl-5-methyl-nzimidazole 0.4% and eF, an aqueous solution containing 2.5% acid at a temperature of 5%.
It was immersed at 0°C for 40 seconds, taken out and washed with water. followed by 2.0% zinc acetate, 0.09% acetic acid and 0.0 ammonia.
The test piece was placed in an aqueous solution containing 4% at a temperature of 50°C.
It was immersed in water for 30 seconds, then taken out and washed with water.

The thickness of the chemical conversion coating on the surface of the test piece thus obtained was 0.12 μm, and the results of the solder wettability test are shown in Table 1.
It was as shown in 1.

(The following is a blank space) Example 12 When the same treatment as in the above Example was performed except that the treatment with the aqueous solution containing zinc acetate, acetic acid, and ammonia was not performed, the chemical conversion coating on the surface of the test piece was 0.16 μm. The results of the solder wettability test were as shown in Table 12.

Example 13 A 1'1 test piece that had been degreased and soft-etched was treated with 0.3% of 2-heptyl-1-methylhenzimidazur, 0.2% of 2-heptyl-5-methylhenzimidazur, and 0.2% of 2-heptyl-5-methylhenzimidazur. In an aqueous solution containing 0.7% formic acid, the liquid temperature was 4.
It was immersed at 0°C for 25 seconds, taken out and washed with water. followed by 2.0% copper acetate, 0.09% acetic acid and 0.04% ammonia.
% of the aqueous solution, the test piece was heated to a liquid temperature of 50°C.
It was immersed in water for 30 seconds, then taken out and washed with water.

The thickness of the chemical conversion coating on the surface of the test piece thus obtained was 0.15 μm, and the results of the solder wettability test are shown in Table 1.
It was as shown in 3.

Example 14 The same treatment as in Example 13 was repeated except that the treatment with the aqueous solution containing copper acetate, acetic acid, and ammonia was not performed, and the chemical conversion coating on the surface of the test piece was 0.17 μm, and the solder The results of the wettability test are shown in Table 14.

The test piece was immersed in an aqueous solution containing 0.04% Monia for 30 seconds at a temperature of 50° C., then taken out and washed with water.

The thickness of the chemical conversion coating on the surface of the TESJ piece thus obtained was 0.19 μm, and the results of the solder wettability test were as shown in Table 15.

Table 15 Solder wettability (unit: 5 seconds) Example 15 A copper plate test heath that had been degreased and soft etched was treated with a 2-nonyl-4-methylbenzimiter tool of 0.4
%, 2-nonyl-5-methylbenzimidazole 0.1
% and formic acid at a temperature of 50°C.
It was immersed for 0 seconds, then taken out and washed with water.

Next, cupric chloride 2.0%, acetic acid 0.09% and ammonium Example 16. When the same treatment as in Example 15 was performed, the chemical conversion coating on the surface of the test piece was 0.20 μm, and the results of the solder wettability test were as shown in Table 16.

(Left below) 216 Solder wettability (Unit: seconds) Comparative Example 1 A copper plate test (heather) that had been degreased and soft-etched was soaked in an aqueous solution containing 1.0% of 2-undecylimidazole and 1.6% of acetic acid. When the test piece was immersed in the liquid for 20 seconds at a temperature of 50°C and then taken out and washed with water, the thickness of the chemical conversion coating on the surface of the test piece was 0.23 μm.The results of examining the solder wettability in the same manner as in the previous examples are shown in Table 17. It was as shown.

Comparative Example 2 A copper plate test piece that had been degreased and soft etched was placed in an aqueous solution containing 1.0% of 2-pentylbenzimidazole, 2.5% of acetic acid, and 0.5% of cupric chloride at a temperature of 50°C. When the test piece was immersed for 15 seconds at °C and then taken out and washed with water, the thickness of the chemical conversion coating on the surface of the test piece was 0.17 μm.The results of examining the solder wettability in the same manner as in the previous examples are shown in Table 18. there were.

Table 18 Solder wettability (unit: 5 seconds) Comparative Example 3 A test piece of a copper plate that had been degreased and soft etched was treated with 2-nonyl-4-methylbenzimidazole 0.5%.
When the test piece was immersed in an aqueous solution containing 5% formic acid, 1.6% formic acid, and 0.8% zinc acetate at a temperature of 40°C for 7 seconds and then taken out and washed with water, the thickness of the chemical conversion coating on the surface of the test piece was 0.20 μm. The solder wettability was investigated in the same manner as in each of the above Examples, and the results are shown in Table 19.

Table 19 Solder wettability (unit: 5 seconds) Effects of the invention According to the method of the present invention, it is possible to form a chemical conversion film with excellent heat resistance, which is mainly composed of an alkylhenzimidazole compound, on the surface of copper or copper alloy. In particular, soldering properties in the surface mounting method of printed wiring boards can be improved.

Patent applicant: Shikoku Kasei Kogyo Co., Ltd.

Claims (4)

[Claims] (1) A 2-alkyl-4-methylbenzimidazole compound represented by the following general formula I, a 2-alkyl-5-methylbenzimidazole compound represented by the following general formula II on the surface of copper or copper alloy.
A method for surface treatment of copper and copper alloys, which comprises contacting an aqueous solution containing a methylbenzimidazole compound and an organic acid. General formula I ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ General formula II ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ (However, R_1 in the formula represents an alkyl group with 3 or more carbon atoms) (2) A 2-alkyl-4-methylbenzimidazole compound represented by the following general formula I or a 2-alkyl-5-methylbenzimidazole compound represented by the following general formula II on the surface of copper or copper alloy.
A method for surface treatment of copper and copper alloys, which comprises contacting an aqueous solution containing a methylbenzimidazole compound, an organic acid, and a zinc compound or a copper compound. General formula I ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ General formula II ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ (However, R_1 in the formula represents an alkyl group with 3 or more carbon atoms) (3) A 2-alkyl-4-methylbenzimidazole compound represented by the following general formula I or a 2-alkyl-5-methylbenzimidazole compound represented by the following general formula II on the surface of copper or copper alloy.
A method for surface treatment of copper and copper alloys, which comprises contacting an aqueous solution containing a methylbenzimidazole compound and an organic acid, and then contacting the treated metal surface with an aqueous solution containing a copper compound or a zinc compound. General formula I ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ General formula II ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ (However, R_1 in the formula represents an alkyl group with 3 or more carbon atoms) (4) Claim (1) characterized in that the mixing ratio of the 2-alkyl-4-methylbenzimidazole compound and the 2-alkyl-5-methylbenzimidazole compound is in the range of 2:8 to 8:2; Claim (2), and claim (
The method described in 3).