Surface treatment agents for copper or copper alloys

Abstract

The objective of this invention is to provide a surface treatment agent that forms a heat-resistant coating on a copper surface, resulting in good weldability during welding. The copper or copper alloy surface treatment agent of this invention contains: an imidazole compound of formula (I) or a benzimidazole compound of formula (II); and a triazole compound of formula (III). The definitions of each substituent in formulas (I) to (III) are the same as those in the specification.

Description

[Technical Field]

[0001] This invention relates to a surface treatment agent used on copper or copper alloys for printed wiring boards. [Previous Technology]

[0002] As a recent method for mounting printed circuit boards (PCBs), surface mount technology (SMT) is widely used to increase mounting density. This SMT method is categorized into two-sided surface mount where chip components are joined using solder paste, and hybrid mount, which combines surface mount of chip components using solder paste with via mounting of distributed components. In any of these mounting methods, the PCB undergoes multiple soldering processes, thus being exposed to high temperatures and subjected to harsh thermal conditions. As a result, the surface of the copper or copper alloy (hereinafter sometimes simply referred to as copper) constituting the circuit section of the PCB is heated, promoting oxide film formation and compromising the solderability of the circuit section surface.

[0003] To protect the copper circuitry of such printed wiring boards from oxidation caused by air or heat, a surface treatment agent (pre-soldering flux) is widely used to form an oxidation film on the surface of the copper circuitry. The oxidation film formed by the surface treatment agent (OSP, Organic Solderability Preservative) is required to remain unchanged (degraded) even after the copper circuitry has undergone multiple heat treatments, thereby protecting the copper circuitry and maintaining good solderability.

[0004] On the other hand, tin-lead alloy eutectic solder has been widely used in bonding electronic components to printed circuit boards, etc. However, in recent years, considering the harmfulness of lead (Pb) contained in this solder alloy to the human body, there has been a demand for lead-free solder. Therefore, various lead-free solders have been studied, such as lead-free solders with tin (Sn) as the base metal and the addition of metals such as silver (Ag), zinc (Zn), bismuth (Bi), indium (In), antimony (Sb), cobalt (Co), manganese (Mn), nickel (Ni) or copper (Cu).

[0005] However, conventional Sn-Pb eutectic solders offer high reliability in the bonding between copper components due to their superior wettability to the base metals used in the bonding process, especially to copper surfaces, and their strong bonding to copper. In contrast, lead-free solders, due to their deteriorated wettability to copper surfaces, result in poor solderability, voids, and other poor bonding, as well as low bonding strength.

[0006] Therefore, when using lead-free solder, it is required to select a solder alloy with better solderability and a flux suitable for lead-free solder. However, for surface treatment agents used to prevent oxidation of copper surfaces, it is also required to improve the wettability of lead-free solder to make it a good soldering agent. In addition, most lead-free solders have a higher melting point, and their soldering temperature is about 20 to 50°C higher than that of conventional Sn-Pb eutectic solders. Therefore, it is also desirable for the surface treatment agent to form a chemically formed film with superior heat resistance.

[0007] Imidazole compounds are used as the active ingredient in this type of surface treatment agent, and various studies have been conducted. For example, Patent Documents 1 and 2 propose surface treatment agents for copper or copper alloys containing imidazole compounds with specific substituents. [Prior Art Documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2012-241251 [Patent Document 2] Japanese Patent Application Publication No. 2013-1977 [Summary of the Invention]

[0009] (The problem that the invention aims to solve)

[0010] To improve the performance of electronic devices, it is necessary to maintain good solderability of electronic components to printed circuit boards, especially when using lead-free solder. To prevent oxidation of the copper surface, further improvements in surface treatment agents are required. Therefore, the object of this invention is to provide a surface treatment agent that forms a coating on the copper surface with superior heat resistance, resulting in good solderability during soldering. (Technical means to solve the problem)

[0011] The inventors of this case have devoted themselves to research in order to solve the above-mentioned problems, and as a result, they have found that by using a surface treatment agent containing a specific imidazole compound or benzimidazole compound as an additive and further containing a specific triazole compound as an additive, the above-mentioned problems can be solved, and thus the present invention is completed.

[0012] That is, the present invention is as follows [1]~[6]. [1] A surface treatment agent for copper or copper alloy, comprising: an imidazole compound of the following chemical formula (I) or a benzimidazole compound of the following chemical formula (II); and a triazole compound of the following chemical formula (III);

[0013] [Chemical 1]

[0014] (In formula (I), R1 represents a hydrogen atom, a straight-chain or branched-chain alkyl or cycloalkyl group having 1 to 18 carbon atoms, a phenyl group that may have substituents, a naphthyl group that may have substituents, a benzyl group that may have substituents, a naphthylmethyl group, -CH-(Ph)2, -(CH2)k-Ph, a thiophene group, a thiophene methyl group, a furanyl group, or a pyridyl group; wherein, Ph represents a phenyl group that may have substituents, and k represents an integer from 2 to 5; R2 may be the same or different, representing a hydrogen atom, a straight-chain or branched-chain alkyl or cycloalkyl group having 1 to 18 carbon atoms, a phenyl group that may have substituents, a naphthyl group that may have substituents, a thiophene group, or a furanyl group; wherein, the case where R2 is also a hydrogen atom is excluded).

[0015] [Chemical 2]

[0016] (In formula (II), R3 represents a straight-chain or branched alkyl group with 1 to 18 carbon atoms, -(CH2)m-Ph, -(CH2)m-Np or the group shown in formula (1), Ph represents a phenyl group that may also have substituents, Np represents a naphthyl group that may also have substituents, and m represents an integer from 1 to 5;

[0017] [Chemical 3]

[0018] (In formula (1), m represents an integer from 1 to 5); R4 can be the same or different, representing hydrogen atoms, straight-chain or branched alkyl, nitro or halogen atoms with 1 to 18 carbon atoms);

[0019] [Chemical 4]

[0020] (In formula (III), R5 and R6 may be the same or different, representing hydrogen atoms, straight-chain or branched-chain alkyl or amino groups with 1 to 18 carbon atoms, phenyl groups with substituents, benzyl, naphthyl, pyridyl or groups shown in formula (2) below; wherein, the case where R5 and R6 are simultaneously groups shown in formula (2) below is excluded.

[0021] [Chemical 5]

[0022] (In formula (2), t represents an integer from 0 to 12); R7 represents a hydrogen atom, benzyl or -(CH2)n-COOH, where n represents an integer from 1 to 5).

[0023] [2] A surface treatment agent for copper or copper alloys as described in [1], wherein it further contains halide ions. [3] A surface treatment agent for copper or copper alloys as described in [2], wherein the halide ions are chloride ions. [4] A surface treatment agent for copper or copper alloys as described in any one of [1] to [3], wherein it further contains zinc ions. [5] A surface treatment agent for copper or copper alloys as described in any one of [1] to [4], wherein the triazole compound represented by chemical formula (III) is contained in a molar ratio of 0.005 to 3.0 relative to the imidazole compound represented by chemical formula (I) or the benzimidazole compound represented by chemical formula (II). [6] A surface treatment agent for copper or copper alloys as described in any one of [1] to [5], wherein the pH is 2 to 5. (Effects compared to prior art)

[0024] The copper or copper alloy surface treatment agent of the present invention is applied to the surface of the copper or copper alloy constituting the circuit part of the printed wiring board, etc., and can form a heat-resistant chemical film, while significantly improving the wettability of the solder on the surface, resulting in good solderability.

Implementation Method

[0025] The present invention will now be described in detail. However, the present invention is not limited to the embodiments described below.

[0026] The surface treatment agent for copper or copper alloys of the present invention contains an imidazole compound of formula (I) or a benzimidazole compound of formula (II) as an active ingredient, and a triazole compound of formula (III) as an additive. When the surface treatment agent of the present invention is applied to copper or copper alloys, copper ions dissolved from the copper surface react with the imidazole compound of formula (I) or the benzimidazole compound of formula (II) to form a copper-imidazolium complex. This copper-imidazolium complex is insoluble in the surface treatment agent and therefore precipitates on the copper or copper surface to form an OSP film. Although the function of the triazole compound of formula (III) in the surface treatment agent has not yet been elucidated, it can be inferred that the heat resistance of the OSP film is improved because the triazole compound is absorbed into the OSP film.

[0027] (Imidazole compound shown in formula (I)) The imidazole compound shown in formula (I) (hereinafter also referred to as imidazole compound (I)) has the following structure.

[0028] [Chemical 6]

[0029] (In formula (I), R1 represents a hydrogen atom, a straight-chain or branched-chain alkyl or cycloalkyl group having 1 to 18 carbon atoms, a phenyl group that may have substituents, a naphthyl group that may have substituents, a benzyl group that may have substituents, a naphthylmethyl group, -CH-(Ph)2, -(CH2)k-Ph, a thiophene group, a thiophenemethyl group, a furanyl group, or a pyridyl group; wherein, Ph represents a phenyl group that may have substituents, and k represents an integer from 2 to 5. R2 may be the same or different, representing a hydrogen atom, a straight-chain or branched-chain alkyl or cycloalkyl group having 1 to 18 carbon atoms, a phenyl group that may have substituents, a naphthyl group that may have substituents, a thiophene group, or a furanyl group; wherein, the case where R2 is also a hydrogen atom is excluded.)

[0030] In formula (I), R1 represents a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms, a cycloalkyl group, a phenyl group that may have substituents, a naphthyl group that may have substituents, a benzyl group that may have substituents, a naphthylmethyl group, -CH-(Ph)2 (Ph is a phenyl group that may have substituents), -(CH2)k-Ph (Ph is a phenyl group that may have substituents, k is an integer from 2 to 5), a thiophene group, a thiophene methyl group, a furanyl group, or a pyridyl group.

[0031] Specific examples of straight-chain alkyl groups having 1 to 18 carbon atoms include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecanyl, n-hexadecyl, n-heptadecyl, n-heptadecyl, n-octadecyl, etc. Specific examples of branched-chain alkyl groups having 1 to 18 carbon atoms include isopropyl, isobutyl, dibutyl, tributyl, isopentyl, dipentyl, tripentyl, isohexyl, dihexyl, trihexyl, isoheptyl, diheptyl, triheptyl, isooctyl, dioctyl, trioctyl, etc.

[0032] As a substituent replacing the hydrogen group of phenyl, naphthyl and benzyl, examples include straight-chain or branched-chain alkyl, phenyl, methoxy, ethoxy, halogen atoms, etc., having 1 to 18 carbon atoms.

[0033] Examples of halogen atoms substituted for the hydrogen groups of phenyl, naphthyl, and benzyl groups include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). Specific examples of halogen-substituted phenyl groups include 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 2-iodophenyl, 3-iodophenyl, 4-iodophenyl, 2,3-dichlorophenyl, 2,4-dichlorophenyl, 2,5-dichlorophenyl, 2,6-dichlorophenyl, 3,4-dichlorophenyl, 3,5-dichlorophenyl, 2,4,5-trichlorophenyl, and 3,4,5-trichlorophenyl. Examples of benzyl groups substituted with halogen atoms include 2-fluorobenzyl, 3-fluorobenzyl, 4-fluorobenzyl, 2-chlorobenzyl, 3-chlorobenzyl, 4-chlorobenzyl, 2-bromobenzyl, 3-bromobenzyl, 4-bromobenzyl, 2-iodobenzyl, 3-iodobenzyl, 4-iodobenzyl, 2,3-dichlorobenzyl, 2,4-dichlorobenzyl, 2,5-dichlorobenzyl, 2,6-dichlorobenzyl, 3,4-dichlorobenzyl, 3,5-dichlorobenzyl, 2,4,5-trichlorobenzyl, and 3,4,5-trichlorobenzyl.

[0034] As a thiophene group, examples include 2-thiophene and 3-thiophene; as a furanyl group, examples include 2-furanyl and 3-furanyl.

[0035] From the viewpoint of the heat resistance of the formed film, R1 is preferably a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms, or a phenyl group having a substituent, or a naphthyl group having a substituent, or a benzyl group having a substituent, naphthylmethyl group, or thiophene group having a substituent.

[0036] R2 represents a hydrogen atom, a straight-chain or branched-chain alkyl or cycloalkyl group having 1 to 18 carbon atoms, or a phenyl group that may have substituents, or a naphthyl, thiophene, or furanyl group that may have substituents. These substituents are the same as those described in R1 above. Two R2s may be the same or different, but R2s may not both be hydrogen atoms.

[0037] From the viewpoint of the heat resistance of the formed film, R2 is preferably a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms, or a phenyl group having a substituent, or a naphthyl, thiophene, or furanyl group having a substituent. The case where R2 is also a hydrogen atom is excluded.

[0038] The imidazole compound shown in formula (I) (imidazole compound (I)) is preferably an imidazole compound shown in formula (I-1) to (I-6).

[0039] [Chemical 7]

[0040] (In formula (I-1), R 112 represents a straight-chain or branched alkyl group having 1 to 18 carbon atoms; R 214 represents a straight-chain or branched alkyl group having 1 to 18 carbon atoms or a phenyl group that may also have substituents; R 215 represents a hydrogen atom or a straight-chain or branched alkyl group having 1 to 18 carbon atoms. In formula (I-2), R 224 represents a phenyl group that may also have substituents, or a naphthyl, thiophene, or furanyl group that may also have substituents; R 225 represents a hydrogen atom or a straight-chain or branched alkyl group having 1 to 18 carbon atoms; R 226 may be the same or different, representing a straight-chain or branched alkyl group, methoxy, ethoxy, or halogen atom having 1 to 18 carbon atoms; p represents an integer from 0 to 3. In formula (I-3), R 234 represents a phenyl group that may also have substituents; R 235 represents a hydrogen atom or a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms. In formula (I-4), R 224 represents a phenyl, naphthyl, or thiophene group that may also have substituents; R 245 represents a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms, or a phenyl group that may also have substituents; R 246 may be the same or different, representing a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms, or a halogen atom; p represents an integer from 0 to 3. In formula (I-5), R 254 represents a phenyl group that may also have substituents; R 255 represents a hydrogen atom or a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms. In formula (I-6), R 264 represents a phenyl or naphthyl group that may also have substituents; R 265 represents a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms, or a phenyl group that may also have substituents.

[0041] As a specific example of imidazole compound (I), the imidazole compound shown in formula (I-1) may include, for example, 2-ethyl-4-methylimidazolium, 2-undecaprol-4-methylimidazolium, 2,4,5-trimethylimidazolium, 4,5-dimethyl-2-octylimidazolium, 4-(3,4-dichlorophenyl)-5-methyl-2-nonylimidazolium, 4-(2,4-dichlorophenyl)-5-methyl-2-undecaprolimidazole, etc.

[0042] Examples of the imidazole compound shown in formula (I-2) include 2,4-diphenylimidazolium, 2,4-diphenyl-5-methylimidazolium, 2,4-diphenyl-5-hexylimidazolium, 2-phenyl-4-(2-chlorophenyl)imidazolium, 2-phenyl-4-(3-chlorophenyl)imidazolium, 2-phenyl-4-(4-chlorophenyl)imidazolium, 2-phenyl-4-(4-fluorophenyl)imidazolium, 2-phenyl-4-(4-bromophenyl)imidazolium, 2-phenyl-4-(4-iodophenyl)imidazolium, 2-phenyl-4-(2,3-dichlorophenyl)imidazolium, 2-phenyl-4-(2,4-dichlorophenyl)imidazolium, 2-phenyl-4-(2,5-dichlorophenyl)imidazolium, 2-phenyl-4-(2,6-dichlorophenyl)imidazolium, 2-Phenylacetyl-4-(3,4-dichlorophenyl)imidazole, 2-Phenylacetyl-4-(3,5-dichlorophenyl)imidazole, 2-Phenylacetyl-4-(2-propyl-3-chlorophenyl)imidazole, 2-Phenylacetyl-4-(2-chlorophenyl)-5-methylimidazole, 2-Phenylacetyl-4-(3-chlorophenyl)-5-methylimidazole, 2-Phenylacetyl-4-(4-chlorophenyl)-5-methylimidazole, 2-Phenylacetyl-4-(2,3-dichlorophenyl)-5-methylimidazole, 2-Phenylacetyl-4-(2,4-dichlorophenyl)-5-methylimidazole, 2-Phenylacetyl-4-(2,5-dichlorophenyl)-5-methylimidazole, 2-Phenylacetyl-4-(2,6-dichlorophenyl)-5-methylimidazole, 2-Phenylacetyl-4-(3,4-dichlorophenyl)-5-methylimidazole, 2-Phenylacetyl-4-(3,5-dichlorophenyl)-5-methylimidazole, 2-Phenylacetyl-4-(2,3-dichlorophenyl)-5-propylimidazole, 2-Phenylacetyl-4-(2,4-dichlorophenyl)-5-undecylimidazole, 2-Phenylacetyl-4-(1-naphthyl)imidazole, 2-Phenylacetyl-4-(2-naphthyl)imidazole, 2-Phenylacetyl-4-(2-naphthyl)-5-methylimidazole, 2-Phenylacetyl-4-(2-naphthyl)-5-methylimidazole, 2-Phenylacetyl-4-(2-thienyl)imidazole, 2-Phenylacetyl-4-(3-thienyl)imidazole, 5-methyl-2-phenyl-4-(2-thienyl)imidazole, 5-methyl-2-phenyl-4-(3-thienyl)imidazole, 4-(2-furanyl)-2-phenylimidazole, 2-(2-methylphenyl)-4-phenylimidazole, 2-(3-octylphenyl)-4-phenylimidazole, 2-(4-methylphenyl)-4-phenylimidazole, 2-(4-isopropylphenyl)-4-phenylimidazole, 2-(4-methylphenyl)-4-phenyl-5-methylimidazole, 2-(4-isopropylphenyl)-4-phenyl-5-methylimidazole, 2-(4-biphenyl)-4-phenyl-5-methylimidazole, 2-(2,4-Dimethylphenyl)-4-phenylimidazole, 2-(2-chlorophenyl)-4-phenylimidazole, 2-(3-chlorophenyl)-4-phenylimidazole, 2-(4-chlorophenyl)-4-phenylimidazole, 2-(4-fluorophenyl)-4-phenylimidazole, 2-(4-bromophenyl)-4-phenylimidazole, 2-(4-iodophenyl)-4-phenylimidazole, 2-(2,3-dichlorophenyl)-4-phenylimidazole, 2-(2,4-dichlorophenyl)-4-phenylimidazole, 2-(2,5-dichlorophenyl)-4-phenylimidazole, 2-(2,6-dichlorophenyl)-4-phenylimidazole, 2-(3,4-dichlorophenyl)-4-phenylimidazole, 2-(3,5-dichlorophenyl)-4-phenylimidazole, 2-(2,4-dibromophenyl)-4-phenylimidazole 2-(2-methyl-4-chlorophenyl)-4-phenylimidazole, 2-(4-chlorophenyl)-4-phenyl-5-methylimidazole, 4-(2,4-dichlorophenyl)-2-(4-methoxyphenyl)-5-methylimidazole, 2-(2,3-dichlorophenyl)-4-phenyl-5-methylimidazole, 2-(2,4-dichlorophenyl)-4-phenyl-5-methylimidazole, 2-(2,5-dichlorophenyl)-4-phenyl-5-methylimidazole, 2-(2,6-dichlorophenyl)-4-phenyl-5-methylimidazole, 2-(3,4-dichlorophenyl)-4-phenyl-5-methylimidazole, 2-(3,5-dichlorophenyl)-4-phenyl-5-methylimidazole, 2-(2,4-dichlorophenyl)-4-phenyl-5-ethylimidazole, 2-(2,3-Dichlorophenyl)-4-phenyl-5-decylimidazol, 2-(3,4-Dichlorophenyl)-4-phenyl-5-heptadecylimidazol, 2-(2-heptyl-4-chlorophenyl)-4-phenyl-5-isobutylimidazol, 2,4-bis(4-chlorophenyl)imidazol, 2-(2,4-dichlorophenyl)-4-(3,4-dichlorophenyl)-5-methylimidazol, 4-(2,4-dichlorophenyl)-2-(3,4-dimethoxyphenyl)-5-methylimidazol, 4-(3,4-dichlorophenyl)-2-(3,4-dimethoxyphenyl)-5-methylimidazol, 2-(4-methylphenyl)-4-(2-naphthyl)imidazol, 2-(4-isopropylphenyl)-4-(1-naphthyl)imidazol, 2-(3,4-Dimethoxyphenyl)-4-(1-naphthyl)imidazolium, 2-(4-methylphenyl)-4-(4-chloro-6-butyl-1-naphthyl)imidazolium, etc.

[0043] Imidazole compounds represented by formula (I-3) may include, for example, 2-(1-naphthyl)-4-phenylimidazolium, 2-(2-naphthyl)-4-phenylimidazolium, 2-(1-naphthyl)-4-phenyl-5-methylimidazolium, 2-(2-naphthyl)-4-phenyl-5-methylimidazolium, etc.

[0044] Imidazole compounds represented by formula (I-4) include, for example, 2-benzyl-4-phenylimidazolium, 2-benzyl-4-(4-hexylphenyl)imidazolium, 2-benzyl-4-(2-chlorophenyl)imidazolium, 2-benzyl-4-(3-chlorophenyl)imidazolium, 2-benzyl-4-(4-chlorophenyl)imidazolium, 2-benzyl-4-(4-bromophenyl)imidazolium, 2-benzyl-4-(2,3-dichlorophenyl)imidazolium, 2-benzyl-4-(2,4-dichlorophenyl)imidazolium, 2-benzyl-4-(2,5-dichlorophenyl)imidazolium, 2-benzyl-4-(2,6-dichlorophenyl)imidazolium, 2-benzyl-4-(3,4-dichlorophenyl)imidazolium, 2-benzyl-4-(3,5-dichlorophenyl)imidazolium, 2-Benzyl-4-(2,4,5-trichlorophenyl)imidazolium, 2-Benzyl-4-(3,4,5-trichlorophenyl)imidazolium, 2-Benzyl-5-methyl-4-phenylimidazolium, 2-Benzyl-5-butyl-4-phenylimidazolium, 2-Benzyl-5-heptyl-4-phenylimidazolium, 2-Benzyl-5-hexyl-4-phenylimidazolium, 2-Benzyl-5-octyl-4-phenylimidazolium, 2-Benzyl-4-(2-chlorophenyl)-5-methylimidazolium, 2-Benzyl-4-(3-chlorophenyl)-5-methylimidazolium, 2-Benzyl-4-(4-chlorophenyl)-5-methylimidazolium, 2-Benzyl-4-(2,4-dichlorophenyl)-5-methylimidazolium, 2-Benzyl-4-(3,4-dichlorophenyl)-5-methylimidazolium 2-Benzyl-5-methyl-4-(2,4,5-trichlorophenyl)imidazolium, 2-Benzyl-4,5-diphenylimidazolium, 2-Benzyl-4-(1-naphthyl)imidazolium, 2-Benzyl-4-(2-naphthyl)imidazolium, 2-(2-chlorobenzyl)-4-phenylimidazolium, 2-(3-chlorobenzyl)-4-phenylimidazolium, 2-(4-chlorobenzyl)-4-phenylimidazolium, 2-(4-bromobenzyl)-4-phenylimidazolium, 2-(4-chlorobenzyl)-4-(4-chlorophenyl)imidazolium, 4-(4-bromophenyl)-2-(4-chlorobenzyl)imidazolium, 2-(4-bromobenzyl)-4-(4-chlorophenyl)imidazolium, 2-(4-bromobenzyl)-4-(4-fluorophenyl)imidazolium, 2-(2-bromobenzyl)-4-(4-bromophenyl)imidazolium, 2-(4-bromobenzyl)-4-(3-bromophenyl)imidazolium, 4-(4-butylphenyl)-2-(2-chlorobenzyl)imidazolium, 2-(2-chlorobenzyl)-4-(4-hexylphenyl)imidazolium, 2-(2-chlorobenzyl)-4-(2,4-dichlorophenyl)imidazolium, 2-(2-chlorobenzyl)-4-(3,4-dichlorophenyl)imidazolium, 2-(3-chlorobenzyl)-4-(2,4-dichlorophenyl)imidazolium, 2-(3-chlorobenzyl)-4-(3,4-dichlorophenyl)imidazolium, 2-(4-chlorobenzyl)-4-(2,4-dichlorophenyl)imidazolium, 2-(4-chlorobenzyl)-4-(3,4-Dichlorophenyl)imidazolium, 2-(4-chlorobenzyl)-4-(2,4-dibromophenyl)imidazolium, 4-(2,4-dichlorophenyl)-2-(4-methylbenzyl)-5-methylimidazolium, 2-(2,3-dichlorobenzyl)-4-phenylimidazolium, 2-(2,4-dichlorobenzyl)-4-phenylimidazolium, 2-(2,5-dichlorobenzyl)-4-phenylimidazolium, 2-(2,6-dichlorobenzyl)-4-phenylimidazolium, 2-(3,4-dichlorobenzyl)-4-phenylimidazolium, 2-(3,5-dichlorobenzyl)-4-phenylimidazolium, 4-(2-chlorophenyl)-2-(2,4-dichlorobenzyl)imidazolium, 4-(2-chlorophenyl)-2-(3,4-dichlorobenzyl)imidazolium, 4-(3-chlorophenyl)-2-(2,4-dichlorobenzyl)imidazol, 4-(3-chlorophenyl)-2-(3,4-dichlorobenzyl)imidazol, 4-(4-chlorophenyl)-2-(2,4-dichlorobenzyl)imidazol, 4-(4-chlorophenyl)-2-(3,4-dichlorobenzyl)imidazol, 4-(4-bromophenyl)-2-(2,4-dichlorobenzyl)imidazol, 4-(4-biphenyl)-2-(2,4-dichlorobenzyl)imidazol, 4-(2,3-dichlorobenzyl)-4-(2,4-dichlorophenyl)imidazol, 4-(2,4-dichlorobenzyl)-4-(2,4-dichlorophenyl)imidazol, 4-(2,5-dichlorobenzyl)-4-(2,4-dichlorophenyl)imidazol, 4-(2,6-Dichlorobenzyl)-4-(2,4-dichlorophenyl)imidazolium, 4-(3,4-dichlorobenzyl)-4-(2,4-dichlorophenyl)imidazolium, 4-(3,5-dichlorobenzyl)-4-(2,4-dichlorophenyl)imidazolium, 4-(2,3-dichlorobenzyl)-4-(3,4-dichlorophenyl)imidazolium, 4-(2,4-dichlorobenzyl)-4-(3,4-dichlorophenyl)imidazolium, 4-(2,5-dichlorobenzyl)-4-(3,4-dichlorophenyl)imidazolium, 4-(2,6-dichlorobenzyl)-4-(3,4-dichlorophenyl)imidazolium, 4-(3,4-dichlorobenzyl)-4-(3,4-dichlorophenyl)imidazolium, 4-(3,5-Dichlorobenzyl)-4-(3,4-dichlorophenyl)imidazolium, 4-phenyl-2-(3,4,5-trichlorobenzyl)imidazolium, 2-(4-chlorobenzyl)-5-methyl-4-phenylimidazolium, 2-(4-chlorobenzyl)-4-(4-chlorophenyl)-5-methylimidazolium, 2-(4-bromobenzyl)-4-(4-bromophenyl)-5-methylimidazolium, 2-(2-chlorobenzyl)-4-(2,4-dichlorophenyl)-5-methylimidazolium, 2-(2-chlorobenzyl)-4-(3,4-dichlorophenyl)-5-methylimidazolium, 2-(3-chlorobenzyl)-4-(2,4-dichlorophenyl)-5-methylimidazolium, 2-(3-chlorobenzyl)-4-(3,4-dichlorophenyl)-5-methylimidazolium, 2-(4-chlorobenzyl)-4-(2,4-Dichlorophenyl)-5-methylimidazole, 2-(4-chlorobenzyl)-4-(3,4-dichlorophenyl)-5-methylimidazole, 2-(4-chlorobenzyl)-4-(2,4-dibromophenyl)-5-methylimidazole, 4-(2,4-dichlorophenyl)-2-(4-fluorobenzyl)-5-methylimidazole, 4-(3,4-dichlorophenyl)-2-(4-fluorobenzyl)-5-methylimidazole, 2-(4-bromobenzyl)-4-(2,4-dichlorobenzyl)-5-methylimidazole, 2-(4-bromobenzyl)-4-(3,4-dichlorobenzyl)-5-methylimidazole, 2-(2,4-dichlorophenyl)-5-methyl-4-phenylimidazole, 2-(3,4-dichlorobenzyl)-5-methyl-4-phenylimidazole, 4-(2-chlorophenyl)-2-(2,4-dichlorobenzyl)-5-methylimidazole, 4-(2-chlorophenyl)-2-(3,4-dichlorobenzyl)-5-methylimidazole, 4-(3-chlorophenyl)-2-(2,4-dichlorobenzyl)-5-methylimidazole, 4-(3-chlorophenyl)-2-(3,4-dichlorobenzyl)-5-methylimidazole, 4-(4-chlorophenyl)-2-(2,4-dichlorobenzyl)-5-methylimidazole, 4-(4-chlorophenyl)-2-(3,4-dichlorobenzyl)-5-methylimidazole, 2-(2,4-dichlorobenzyl)-5-methyl-4-(4-methylphenyl)imidazole, 2-(2,4-dichlorobenzyl)-4-(4-methoxyphenyl)-5-methylimidazole, 2-(2,3-Dichlorobenzyl)-4-(2,4-dichlorophenyl)-5-methylimidazole, 2-(2,4-dichlorobenzyl)-4-(2,4-dichlorophenyl)-5-methylimidazole, 2-(2,6-dichlorobenzyl)-4-(2,4-dichlorophenyl)-5-methylimidazole, 2-(3,4-dichlorobenzyl)-4-(2,4-dichlorophenyl)-5-methylimidazole, 2-(2,4-dichlorobenzyl)-4-(3,4-dichlorophenyl)-5-methylimidazole, 2-(3,4-dichlorobenzyl)-4-(3,4-dichlorophenyl)-5-methylimidazole, 2-(2,4-dibromobenzyl)-4-(3,4-dibromophenyl)-5-methylimidazole, 4-(2,4-dichlorophenyl)-2-(3,4-dimethoxybenzyl)-5-methylimidazole, 4-(3-chloro-4-methylphenyl)-2-(2,4-dichlorobenzyl)-5-methylimidazole, 2-(2-chlorobenzyl)-4,5-diphenylimidazole, 2-(3-chlorobenzyl)-4,5-diphenylimidazole, 2-(4-chlorobenzyl)-4,5-diphenylimidazole, 2-(2,4-dichlorobenzyl)-4,5-diphenylimidazole, 2-(2,4-Dichlorobenzyl)-5-hexyl-4-phenylimidazolium, 2-(2-chlorobenzyl)-4-(1-naphthyl)imidazolium, 2-(2-chlorobenzyl)-4-(2-naphthyl)imidazolium, 2-(3-chlorobenzyl)-4-(1-naphthyl)imidazolium, 2-(3-chlorobenzyl)-4-(2-naphthyl)imidazolium, 2-(4-chlorobenzyl)-4-(1-naphthyl)imidazolium, 2-(4-chlorobenzyl)-4-(2-naphthyl)imidazolium, 2-(2,3-dichlorobenzyl)-4-(1-naphthyl)imidazolium, 2-(2,3-dichlorobenzyl)-4-(2-naphthyl)imidazolium, 2-(2,4-dichlorobenzyl)-4-(1-naphthyl)imidazolium, 2-(2,4-Dichlorobenzyl)-4-(2-naphthyl)imidazol, 2-(2,5-Dichlorobenzyl)-4-(1-naphthyl)imidazol, 2-(2,5-Dichlorobenzyl)-4-(2-naphthyl)imidazol, 2-(2,6-Dichlorobenzyl)-4-(1-naphthyl)imidazol, 2-(2,6-Dichlorobenzyl)-4-(2-naphthyl)imidazol, 2-(3,4-Dichlorobenzyl)-4-(1-naphthyl)imidazol, 2-(3,4-Dichlorobenzyl)-4-(2-naphthyl)imidazol, 2-(3,5-Dichlorobenzyl)-4-(1-naphthyl)imidazol, 2-(3,5-Dichlorobenzyl)-4-(2-naphthyl)imidazol, etc.

[0045] Imidazole compounds represented by formula (I-5) include, for example, 2-(1-naphthylmethyl)-4-phenylimidazolium, 2-(2-naphthylmethyl)-4-phenylimidazolium, 4-(2-chlorophenyl)-2-(1-naphthylmethyl)imidazolium, 4-(2-chlorophenyl)-2-(2-naphthylmethyl)imidazolium, 4-(3-chlorophenyl)-2-(1-naphthylmethyl)imidazolium, 4-(3-chlorophenyl)-2-(2-naphthylmethyl)imidazolium, 4-(4-chlorophenyl)-2-(1-naphthylmethyl)imidazolium, 4-(4-chlorophenyl)-2-(2-naphthylmethyl)imidazolium, 4-(2,3-dichlorophenyl)-2-(1-naphthylmethyl)imidazolium, 4-(2,3-dichlorophenyl)-2-(2-naphthylmethyl)imidazolium, 4-(2,4-dichlorophenyl)-2-(1-naphthylmethyl)imidazole, 4-(2,4-dichlorophenyl)-2-(2-naphthylmethyl)imidazole, 4-(2,5-dichlorophenyl)-2-(1-naphthylmethyl)imidazole, 4-(2,5-dichlorophenyl)-2-(2-naphthylmethyl)imidazole, 4-(2,6-dichlorophenyl)-2-(1-naphthylmethyl)imidazole, 4-(2,6-dichlorophenyl)-2-(2-naphthylmethyl)imidazole, 4-(3,4-dichlorophenyl)-2-(1-naphthylmethyl)imidazole, 4-(3,4-dichlorophenyl)-2-(2-naphthylmethyl)imidazole, 4-(3,5-dichlorophenyl)-2-(1-naphthylmethyl)imidazole, 4-(3,5-dichlorophenyl)-2-(2-naphthylmethyl)imidazole, 5-Methyl-2-(1-naphthylmethyl)-4-phenylimidazolium, 5-Methyl-2-(2-naphthylmethyl)-4-phenylimidazolium, 4-(2-chlorophenyl)-5-methyl-2-(1-naphthylmethyl)imidazolium, 4-(2-chlorophenyl)-5-methyl-2-(2-naphthylmethyl)imidazolium, 4-(3-chlorophenyl)-5-methyl-2-(1-naphthylmethyl)imidazolium, 4-(3-chlorophenyl)-5-methyl-2-(2-naphthylmethyl)imidazolium, 4-(4-chlorophenyl)-5-methyl-2-(1-naphthylmethyl)imidazolium, 4-(4-chlorophenyl)-5-methyl-2-(2-naphthylmethyl)imidazolium, 4-(2,3-dichlorophenyl)-5-methyl-2-(1-naphthylmethyl)imidazolium, 4-(2,3-dichlorophenyl)-5-methyl-2-(2-naphthylmethyl)imidazolium, 4-(2,4-dichlorophenyl)-5-methyl-2-(1-naphthylmethyl)imidazol, 4-(2,4-dichlorophenyl)-5-methyl-2-(2-naphthylmethyl)imidazol, 4-(2,5-dichlorophenyl)-5-methyl-2-(1-naphthylmethyl)imidazol, 4-(2,5-dichlorophenyl)-5-methyl-2-(2-naphthylmethyl)imidazol, 4-(2,6-dichlorophenyl)-5-methyl-2-(1-naphthylmethyl)imidazol, 4-(3,4-Dichlorophenyl)-5-methyl-2-(1-naphthylmethyl)imidazole, 4-(3,4-dichlorophenyl)-5-methyl-2-(2-naphthylmethyl)imidazole, 4-(3,5-dichlorophenyl)-5-methyl-2-(1-naphthylmethyl)imidazole, 4-(3,5-dichlorophenyl)-5-methyl-2-(2-naphthylmethyl)imidazole, etc.

[0046] Imidazole compounds represented by formula (I-6) include, for example, 4-phenyl-2-(2-thienyl)imidazolium, 4-phenyl-2-(3-thienyl)imidazolium, 4-(2-chlorophenyl)-2-(2-thienyl)imidazolium, 4-(2-chlorophenyl)-2-(3-thienyl)imidazolium, 4-(3-chlorophenyl)-2-(3-thienyl)imidazolium, 4-(4-chlorophenyl)-2-(2-thienyl)imidazolium, 4-(4-chlorophenyl)-2-(3-thienyl)imidazolium, 4-(2,3-dichlorophenyl)-2-(2-thienyl)imidazolium, 4-(2,3-dichlorophenyl)-2-(3-thienyl)imidazolium, 4-(2,4-dichlorophenyl)-2-(2-thienyl)imidazole, 4-(2,4-dichlorophenyl)-2-(3-thienyl)imidazole, 4-(2,5-dichlorophenyl)-2-(2-thienyl)imidazole, 4-(2,5-dichlorophenyl)-2-(3-thienyl)imidazole, 4-(2,6-dichlorophenyl)-2-(2-thienyl)imidazole, 4-(2,6-dichlorophenyl)-2-(3-thienyl)imidazole, 4-(3,4-dichlorophenyl)-2-(2-thienyl)imidazole, 4-(3,4-dichlorophenyl)-2-(3-thienyl)imidazole, 4-(3,5-dichlorophenyl)-2-(2-thienyl)imidazole, 4-(3,5-Dichlorophenyl)-2-(3-thienyl)imidazol, 4-(1-naphthyl)-2-(2-thienyl)imidazol, 4-(1-naphthyl)-2-(3-thienyl)imidazol, 4-(2-naphthyl)-2-(2-thienyl)imidazol, 4-(2-naphthyl)-2-(3-thienyl)imidazol, 5-methyl-4-phenyl-2-(2-thienyl)imidazol, 5-methyl-4-phenyl-2-(3-thienyl)imidazol, 4-(2-chlorophenyl)-5-methyl-2-(2-thienyl)imidazol, 4-(2-chlorophenyl)-5-methyl-2-(3-thienyl)imidazol, 4-(3-chlorophenyl)-5-methyl-2-(2-thienyl)imidazol, 4-(3-chlorophenyl)-5-methyl-2-(3-thienyl)imidazol, 4-(4-chlorophenyl)-5-methyl-2-(2-thienyl)imidazol, 4-(4-chlorophenyl)-5-methyl-2-(3-thienyl)imidazol, 4-(2,3-dichlorophenyl)-5-methyl-2-(2-thienyl)imidazol, 4-(2,3-dichlorophenyl)-5-methyl-2-(3-thienyl)imidazol, 4-(2,4-dichlorophenyl)-5-methyl-2-(2-thienyl)imidazol, 4-(2,4-dichlorophenyl)-5-methyl-2-(3-thienyl)imidazol, 4-(2,5-dichlorophenyl)-5-methyl-2-(2-thienyl)imidazol, 4-(2,5-Dichlorophenyl)-5-methyl-2-(3-thienyl)imidazol, 4-(2,6-dichlorophenyl)-5-methyl-2-(2-thienyl)imidazol, 4-(2,6-dichlorophenyl)-5-methyl-2-(3-thienyl)imidazol, 4-(3,4-dichlorophenyl)-5-methyl-2-(2-thienyl)imidazol, 4-(3,4-dichlorophenyl)-5-methyl-2-(3-thienyl)imidazol, 4-(3,5-dichlorophenyl)-5-methyl-2-(2-thienyl)imidazol, 4-(3,5-dichlorophenyl)-5-methyl-2-(3-thienyl)imidazol, 5-methyl-4-(1-naphthyl)-2-(2-thienyl)imidazol, 5-Methyl-4-(1-naphthyl)-2-(3-thienyl)imidazol, 5-Methyl-4-(2-naphthyl)-2-(2-thienyl)imidazol, 5-Methyl-4-(2-naphthyl)-2-(3-thienyl)imidazol, 4,5-diphenyl-2-(2-thienyl)imidazol, 4,5-diphenyl-2-(3-thienyl)imidazol, 4-(2-chlorophenyl)-5-phenyl-2-(2-thienyl)imidazol, 4-(2-chlorophenyl)-5-phenyl-2-(3-thienyl)imidazol, 4-(3-chlorophenyl)-5-phenyl-2-(2-thienyl)imidazol, 4-(3-chlorophenyl)-5-phenyl-2-(3-thienyl)imidazol, 4-(4-chlorophenyl)-5-phenyl-2-(2-thienyl)imidazol, 4-(4-chlorophenyl)-5-phenyl-2-(3-thienyl)imidazol, 4-(2,3-dichlorophenyl)-5-phenyl-2-(2-thienyl)imidazol, 4-(2,3-dichlorophenyl)-5-phenyl-2-(3-thienyl)imidazol, 4-(2,4-dichlorophenyl)-5-phenyl-2-(2-thienyl)imidazol, 4-(2,4-dichlorophenyl)-5-phenyl-2-(3-thienyl)imidazol, 4-(2,5-dichlorophenyl)-5-phenyl-2-(2-thienyl)imidazol, 4-(2,5-dichlorophenyl)-5-phenyl-2-(3-thienyl)imidazol, 4-(2,6-dichlorophenyl)-5-phenyl-2-(2-thienyl)imidazolium, 4-(2,6-dichlorophenyl)-5-phenyl-2-(3-thienyl)imidazolium, 4-(3,4-dichlorophenyl)-5-phenyl-2-(2-thienyl)imidazolium, 4-(3,4-dichlorophenyl)-5-phenyl-2-(3-thienyl)imidazolium, 4-(3,5-dichlorophenyl)-5-phenyl-2-(2-thienyl)imidazolium, 4-(3,5-Dichlorophenyl)-5-phenyl-2-(3-thienyl)imidazolium, 4-(1-naphthyl)-5-phenyl-2-(2-thienyl)imidazolium, 4-(1-naphthyl)-5-phenyl-2-(3-thienyl)imidazolium, 4-(2-naphthyl)-5-phenyl-2-(2-thienyl)imidazolium, 4-(2-naphthyl)-5-phenyl-2-(3-thienyl)imidazolium, etc.

[0047] Others, as specific examples of the imidazole compounds shown in formula (I), include, for example, 5-cyclohexyl-2,4-diphenylimidazolium, 5-cyclohexyl-2-(2,4-dichlorobenzyl)-4-phenylimidazolium, 2-(3,6-dichloro-2-naphthyl)-4-(2-isopropyl-5-fluorophenyl)-5-decylimidazolium, 4-phenyl-2-(2-thienylmethyl)imidazolium, 4-phenyl-2-(3-thienylmethyl)imidazolium, 4-(2-chlorophenyl)-2-(2-thienylmethyl)imidazolium, 4-(2-chlorophenyl)-2-(3-thienylmethyl)imidazolium, 4-(3-chlorophenyl)-2-(2-thienylmethyl)imidazolium, 4-(3-chlorophenyl)-2-(3-thienylmethyl)imidazolium, 4-(4-chlorophenyl)-2-(2-thienylmethyl)imidazole, 4-(4-chlorophenyl)-2-(3-thienylmethyl)imidazole, 4-(2,3-dichlorophenyl)-2-(2-thienylmethyl)imidazole, 4-(2,3-dichlorophenyl)-2-(3-thienylmethyl)imidazole, 4-(2,4-dichlorophenyl)-2-(2-thienylmethyl)imidazole, 4-(2,4-dichlorophenyl)-2-(3-thienylmethyl)imidazole, 4-(2,5-dichlorophenyl)-2-(2-thienylmethyl)imidazole, 4-(2,5-dichlorophenyl)-2-(3-thienylmethyl)imidazole, 4-(2,6-dichlorophenyl)-2-(2-thienylmethyl)imidazole, 4-(2,6-dichlorophenyl)-2-(3-thienylmethyl)imidazol, 4-(3,4-dichlorophenyl)-2-(2-thienylmethyl)imidazol, 4-(3,4-dichlorophenyl)-2-(3-thienylmethyl)imidazol, 4-(3,5-dichlorophenyl)-2-(2-thienylmethyl)imidazol, 4-(3,5-dichlorophenyl)-2-(3-thienylmethyl)imidazol, 4-(1-naphthyl)-2-(2-thienylmethyl)imidazol, 4-(1-naphthyl)-2-(3-thienylmethyl)imidazol, 4-(2-naphthyl)-2-(2-thienylmethyl)imidazol, 4-(2-naphthyl)-2-(3-thienylmethyl)imidazol, 5-methyl-4-phenyl-2-(2-thienylmethyl)imidazol, 5-Methyl-4-phenyl-2-(3-thienylmethyl)imidazolium, 4-(2-chlorophenyl)-5-methyl-2-(2-thienylmethyl)imidazolium, 4-(2-chlorophenyl)-5-methyl-2-(3-thienylmethyl)imidazolium, 4-(3-chlorophenyl)-5-methyl-2-(2-thienylmethyl)imidazolium, 4-(3-chlorophenyl)-5-methyl-2-(3-thienylmethyl)imidazolium, 4-(4-chlorophenyl)-5-methyl-2-(2-thienylmethyl)imidazolium, 4-(2,3-Dichlorophenyl)-5-methyl-2-(2-thienylmethyl)imidazol, 4-(2,3-dichlorophenyl)-5-methyl-2-(3-thienylmethyl)imidazol, 4-(2,4-dichlorophenyl)-5-methyl-2-(2-thienylmethyl)imidazol, 4-(2,4-dichlorophenyl)-5-methyl-2-(3-thienylmethyl)imidazol, 4-(2,5-dichlorophenyl)-5-methyl-2-(2-thienylmethyl)imidazol, 4-(2,5-dichlorophenyl)-5-methyl-2-(3-thienylmethyl)imidazol, 4-(2,6-dichlorophenyl)-5-methyl-2-(2-thienylmethyl)imidazol, 4-(2,6-dichlorophenyl)-5-methyl-2-(3-thienylmethyl)imidazol, 4-(3,4-dichlorophenyl)-5-methyl-2-(2-thienylmethyl)imidazol, 4-(3,4-dichlorophenyl)-5-methyl-2-(3-thienylmethyl)imidazol, 4-(3,5-dichlorophenyl)-5-methyl-2-(2-thienylmethyl)imidazol, 4-(3,5-dichlorophenyl)-5-methyl-2-(3-thienylmethyl)imidazol, 5-methyl-4-(1-naphthyl)-2-(2-thienylmethyl)imidazol, 5-methyl-4-(1-naphthyl)-2-(3-thienylmethyl)imidazol, 5-methyl-4-(2-naphthyl)-2-(2-thienylmethyl)imidazol, 5-methyl-4-(2-naphthyl)-2-(3-thienylmethyl)imidazol, 4,5-Diphenyl-2-(2-thienylmethyl)imidazole, 4,5-Diphenyl-2-(3-thienylmethyl)imidazole, 4-(2-chlorophenyl)-5-phenyl-2-(2-thienylmethyl)imidazole, 4-(2-chlorophenyl)-5-phenyl-2-(3-thienylmethyl)imidazole, 4-(3-chlorophenyl)-5-phenyl-2-(2-thienylmethyl)imidazole, 4-(3-chlorophenyl)-5-phenyl-2-(3-thienylmethyl)imidazole, 4-(4-chlorophenyl)-5-phenyl-2-(2-thienylmethyl)imidazole, 4-(4-chlorophenyl)-5-phenyl-2-(3-thienylmethyl)imidazole, 4-(2,3-dichlorophenyl)-5-phenyl-2-(2-thienylmethyl)imidazole, 4-(2,3-dichlorophenyl)-5-phenyl-2-(3-thienylmethyl)imidazolium, 4-(2,4-dichlorophenyl)-5-phenyl-2-(2-thienylmethyl)imidazolium, 4-(2,4-dichlorophenyl)-5-phenyl-2-(3-thienylmethyl)imidazolium, 4-(2,5-dichlorophenyl)-5-phenyl-2-(2-thienylmethyl)imidazolium, 4-(2,5-dichlorophenyl)-5-phenyl-2-(3-thienylmethyl)imidazolium, 4-(2,6-dichlorophenyl)-5-phenyl-2-(2-thienylmethyl)imidazolium, 4-(2,6-Dichlorophenyl)-5-phenyl-2-(3-thienylmethyl)imidazol, 4-(3,4-dichlorophenyl)-5-phenyl-2-(2-thienylmethyl)imidazol, 4-(3,4-dichlorophenyl)-5-phenyl-2-(3-thienylmethyl)imidazol, 4-(3,5-dichlorophenyl)-5-phenyl-2-(2-thienylmethyl)imidazol, 4-(3,5-dichlorophenyl)-5-phenyl-2-(3-thienylmethyl)imidazol, 4-(1-naphthyl)-5-phenyl-2-(2-thienylmethyl)imidazol, 4-(1-naphthyl)-5-phenyl-2-(3-thienylmethyl)imidazol, 4-(2-naphthyl)-5-phenyl-2-(2-thienylmethyl)imidazol, 4-(2-naphthyl)-5-phenyl-2-(3-thienylmethyl)imidazol, etc.

[0048] (The benzimidazole compound shown in formula (II)) The benzimidazole compound shown in formula (II) (hereinafter also referred to as benzimidazole compound (II)) has the following structure.

[0049] [Chemical 8]

[0050] (In formula (II), R 3 represents a linear or branched alkyl group with 1 to 18 carbon atoms, -(CH 2) m-Ph, -(CH 2) m-Np or a group shown in formula (1), Ph represents a phenyl group that may also have substituents, Np represents a naphthyl group that may also have substituents, and m represents an integer number from 1 to 5;

[0051] [Chemical 9]

[0052] (In formula (1), m represents an integer from 1 to 5.) R4 can be the same or different, representing a hydrogen atom, a straight-chain or branched-chain alkyl group with 1 to 18 carbon atoms, a nitro group, or a halogen atom.

[0053] In formula (II), R3 is a linear or branched alkyl group having 1 to 18 carbon atoms, -(CH2)m-Ph (Ph is a phenyl group that may also have substituents, and m is an integer from 1 to 5), -(CH2)m-Np (Np is a naphthyl group that may also have substituents, and m is an integer from 1 to 5), or a group shown in formula (1) above.

[0054] The straight-chain alkyl groups having 1 to 18 carbon atoms and the branched-chain alkyl groups are the same as those described in the imidazole compound (I) above. Also, the substituents that replace hydrogen in the phenyl and naphthyl groups are the same as those described in the imidazole compound (I) above.

[0055] R4 is a hydrogen atom, a straight-chain or branched alkyl group having 1 to 18 carbon atoms, a nitro group, or a halogen atom. This straight-chain or branched alkyl group having 1 to 18 carbon atoms is the same as that described in the imidazole compound (I) above. Examples of halogen atoms include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). The four R4s may be the same or different.

[0056] From the viewpoint of the heat resistance of the coating, R4 is preferably a hydrogen atom, a straight-chain or branched alkyl or halogen atom with 1 to 18 carbon atoms, and more preferably a hydrogen atom, a methyl atom or a chlorine atom (Cl).

[0057] The benzimidazole compound shown in formula (II) (benzimidazole compound (II)) is preferably a benzimidazole compound shown in formula (II-1) to formula (II-4).

[0058] [Chemical 10]

[0059] (In formula (II-1), R 312 represents a straight-chain or branched alkyl group having 1 to 18 carbon atoms; R 415 may be the same or different, representing a straight-chain or branched alkyl group or halogen atom having 1 to 18 carbon atoms; q represents an integer from 0 to 3. In formula (II-2), X may be the same or different, representing a halogen atom; m represents an integer from 1 to 5, and q represents an integer from 0 to 3. In formula (II-3), X may be the same or different, representing a halogen atom; m represents an integer from 1 to 5, q represents an integer from 0 to 3, and r represents an integer from 0 to 3. In formula (II-4), X may be the same or different, representing a halogen atom; m represents an integer from 1 to 5, and q represents an integer from 0 to 3.)

[0060] As a specific example of benzimidazole compound (II), the benzimidazole compound shown in formula (II-1) may include, for example, 2-methylbenzimidazole, 2-ethylbenzimidazole, 2-propylbenzimidazole, 2-butylbenzimidazole, 2-tert-butylbenzimidazole, 2-pentylbenzimidazole, 2-hexylbenzimidazole, 2-heptylbenzimidazole, 2-octylbenzimidazole, 2-nonylbenzimidazole, 2-decylbenzimidazole, 2-undecylbenzimidazole, 2-dodecylbenzimidazole, 2-tridecylbenzimidazole, 2-tetradecylbenzimidazole, 2-pentadecaylbenzimidazole, 2-hexadecylbenzimidazole, 2-heptadecylbenzimidazole, 2-heptyl-5,6-dimethylbenzimidazole, 2-octyl-5-chlorobenzimidazole, 2-Pentyl-5,6-Dichlorobenzimidazole, etc.

[0061] The benzimidazole compound shown in formula (II-2) can be, for example, 2-(2-thienylmethyl)benzimidazole, 2-(3-thienylmethyl)benzimidazole, etc.

[0062] The benzimidazole compound shown in formula (II-3) may include, for example, 2-(phenylmethyl)benzimidazole, 2-(4-chlorophenylmethyl)benzimidazole, 2-(2,4-dichlorophenylmethyl)benzimidazole, 2-(3,4-dichlorophenylmethyl)benzimidazole, 6-chloro-2-(3,4-dichlorophenylmethyl)benzimidazole, 2-(2-phenylethyl)benzimidazole, 2-[2-(4-chlorophenyl)ethyl]benzimidazole, 2-(3-phenylpropyl)benzimidazole, 2-[3-(2-chlorophenyl)propyl]benzimidazole, 2-(4-phenylbutyl)benzimidazole, 2-[4-(4-chlorophenyl)butyl]benzimidazole, 2-(5-phenylpentyl)benzimidazole, 2-[4-(2,4-dichlorophenyl)butyl]-4,7-dichlorobenzimidazole, etc.

[0063] The benzimidazole compounds shown in formula (II-4) can be, for example, 2-(1-naphthylmethyl)benzimidazole, 2-(2-naphthylmethyl)benzimidazole, 2-[2-(1-naphthyl)ethyl]benzimidazole, 2-[2-(2-naphthyl)ethyl]benzimidazole, 2-[3-(1-naphthyl)propyl]benzimidazole, 2-[3-(2-naphthyl)propyl]benzimidazole, 2-[4-(1-naphthyl)butyl]benzimidazole, 2-[4-(2-naphthyl)butyl]benzimidazole, 2-[5-(1-naphthyl)pentyl]benzimidazole, 2-[5-(2-naphthyl)pentyl]benzimidazole, etc.

[0064] Relative to the total amount of the surface treatment agent, imidazole compound (I) or benzimidazole compound (II) is preferably contained in a proportion of 0.01 to 10% by weight, more preferably in a proportion of 0.05 to 5% by weight, and even more preferably in a proportion of 0.05 to 1% by weight. If the content of imidazole compound (I) or benzimidazole compound (II) is 0.01% by weight or more, a chemically formed film can be formed on the copper surface at a thickness that can prevent oxidation. Furthermore, if the content of imidazole compound (I) or benzimidazole compound (II) is 10% by weight or less, the imidazole compound is easily soluble in the surface treatment agent and can improve the solderability of the copper surface.

[0065] Furthermore, in practice, one of the imidazole compounds selected from the group consisting of the above-mentioned imidazole compound (I) and benzimidazole compound (II) may be used alone or in combination with two or more.

[0066] Furthermore, the imidazole compound (I) and the benzimidazole compound (II) can be used in a state where they form salts with a suitable acid. Examples of such acids include HCl (hydrochloric acid) and HBr (hydrobromic acid), which can be used as HCl salts and HBr salts, respectively.

[0067] Furthermore, the surface treatment agent of the present invention may be used in combination with such imidazole compounds (I) and benzimidazole compounds (II) and imidazole compounds known in the same technical field as the present invention.

[0068] (Triazole compound shown in formula (III)) The triazole compound shown in formula (III) (hereinafter also referred to as triazole compound (III)) has the following structure.

[0069] [Chemical 11]

[0070] (In formula (III), R5 and R6 may be the same or different, representing hydrogen atoms, straight-chain or branched-chain alkyl or amino groups with 1 to 18 carbon atoms, phenyl groups with substituents, benzyl, naphthyl, pyridyl or groups shown in formula (2) below; wherein, the case where R5 and R6 are simultaneously groups shown in formula (2) below is excluded.

[0071] [Chemical 12]

[0072] (In formula (2), t represents an integer from 0 to 12.) R7 represents a hydrogen atom, benzyl group, or -(CH2)n-COOH, where n represents an integer from 1 to 5.

[0073] In formula (III), R5 and R6 are hydrogen atoms, straight-chain or branched alkyl groups having 1 to 18 carbon atoms, amino groups, phenyl groups that may have substituents, benzyl groups, naphthyl groups, pyridyl groups, or groups shown in formula (2) above. R5 and R6 may be the same or different, but not simultaneously groups shown in formula (2) above.

[0074] The linear alkyl groups having 1 to 18 carbon atoms and the branched alkyl groups are the same as those described in the imidazole compound (I) above. Furthermore, the substituents replacing the hydrogen atoms of the phenyl and naphthyl groups are also the same as those described in the imidazole compound (I) above.

[0075] From the viewpoint of the heat resistance of the formed film, R5 and R6 are preferably hydrogen atoms, straight-chain or branched-chain alkyl groups with 1 to 18 carbon atoms, amino groups, phenyl groups with substituents, benzyl groups with substituents, naphthyl groups, pyridyl groups, or groups shown in formula (2). In formula (2), t is preferably an integer from 0 to 10, more preferably an integer from 0 to 8, and even more preferably 0 to 6.

[0076] R7 represents a hydrogen atom, a benzyl group, or -(CH2)n-COOH (n is an integer from 1 to 5). From the viewpoint of heat resistance of the coating, R7 is preferably a hydrogen atom or -(CH2)n-COOH (n is an integer from 1 to 3).

[0077] The triazole compound shown in formula (III) (triazole compound (III)) is preferably a triazole compound shown in formula (III-1) to (III-5).

[0078] [Chemical 13]

[0079] (In formula (III-1), R 513 represents a hydrogen atom, an amino group, or a phenyl group that may also have substituents; R 515 represents a hydrogen atom, an amino group, or a phenyl group that may also have substituents; s represents an integer from 1 to 3. In formula (III-2), R 523 represents a straight-chain or branched-chain alkyl or pyridyl group having 1 to 18 carbon atoms; R 525 represents a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms, a phenyl group that may also have substituents, or a benzyl or pyridyl group that may also have substituents. In formula (III-3), R 531 represents a hydrogen atom or a benzyl group that may also have substituents; R 535 represents a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms, or a phenyl, naphthyl, or amino group that may also have substituents. In formula (III-4), R 545 represents a hydrogen atom, and may also be a phenyl group with substituents or a benzyl group with substituents. In formula (III-5), t represents an integer from 0 to 6.

[0080] As a specific example of triazole compound (III), the triazole compound shown in formula (III-1) may include, for example, 1,2,4-triazole-1-acetic acid, 1,2,4-triazole-1-propionic acid, 1,2,4-triazole-1-butyric acid, 3-amino-1,2,4-triazole-1-acetic acid, 3-amino-5-phenyl-1,2,4-triazole-1-acetic acid, etc.

[0081] Examples of triazole compounds represented by formula (III-2) include 3-methyl-1,2,4-triazole, 3-ethyl-1,2,4-triazole, 3-propyl-1,2,4-triazole, 3-isopropyl-1,2,4-triazole, 3-butyl-1,2,4-triazole, 3-pentyl-1,2,4-triazole, 3-hexyl-1,2,4-triazole, 3-octyl-1,2,4-triazole, 3-undecyl-1,2,4-triazole, 3,5-dimethyl-1,2,4-triazole, 3-ethyl-5-methyl-1,2,4-triazole, 3-methyl-5-propyl-1,2,4-triazole, 3-isopropyl-5-methyl-1,2,4-triazole, and 3-butyl-5-methyl-1,2,4-triazole. 3-Methyl-5-pentyl-1,2,4-triazole, 5-heptyl-3-methyl-1,2,4-triazole, 5-methyl-3-octyl-1,2,4-triazole, 3-methyl-5-undecyl-1,2,4-triazole, 3,5-diethyl-1,2,4-triazole, 3,5-dipropyl-1,2,4-triazole, 3,5-diisopropyl-1,2,4-triazole, 3,5-dibutyl-1,2,4-triazole, 3,5-dipentyl-1,2,4-triazole, 3,5-diheptyl-1,2,4-triazole, 3,5-dioctyl-1,2,4-triazole, 3,5-di(undecyl)-1,2,4-triazole, 3-methyl-5-phenyl-1,2,4-triazole 3-Ethyl-5-phenyl-1,2,4-triazole, 5-phenyl-3-propyl-1,2,4-triazole, 3-butyl-5-phenyl-1,2,4-triazole, 3-pentyl-5-phenyl-1,2,4-triazole, 3-methyl-5-(phenylmethyl)-1,2,4-triazole, 3-ethyl-5-(phenylmethyl)-1,2,4-triazole, 5-(phenylmethyl)-3-propyl-1,2,4-triazole, 3-methyl-5-(4-pyridyl)-1,2,4-triazole, 3,5-bis(4-pyridyl)-1,2,4-triazole, etc.

[0082] Examples of triazole compounds represented by formula (III-3) include 3-amino-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 3-amino-5-methyl-1,2,4-triazole, 3-amino-5-ethyl-1,2,4-triazole, 3-amino-5-propyl-1,2,4-triazole, 3-amino-5-isopropyl-1,2,4-triazole, 3-amino-5-butyl-1,2,4-triazole, 3-amino-5-pentyl-1,2,4-triazole, 3-amino-5-phenyl-1,2,4-triazole, 3-amino-5-(1-naphthyl)-1,2,4-triazole, and 3-amino-5-(2-naphthyl)-1,2,4-triazole. 1-Benzyl-3,5-diamino-1,2,4-triazole, etc.

[0083] Examples of triazole compounds represented by formula (III-4) include 3-phenyl-1,2,4-triazole, 3-benzyl-5-phenyl-1,2,4-triazole, and 3,5-diphenyl-1,2,4-triazole.

[0084] Examples of triazole compounds represented by formula (III-5) include 3,3'-bis(5-amino-1,2,4-triazole), 3,3'-methylenebis(5-amino-1,2,4-triazole), 3,3'-epethylbis(5-amino-1,2,4-triazole), 3,3'-trimethylenebis(5-amino-1,2,4-triazole), 3,3'-tetramethylenebis(5-amino-1,2,4-triazole), 3,3'-pentamethylenebis(5-amino-1,2,4-triazole), and 3,3'-hexamethylenebis(5-amino-1,2,4-triazole).

[0085] The triazole compound (III) is preferably contained in a proportion of 0.005 to 1% by weight, more preferably 0.01 to 0.5% by weight, and even more preferably 0.01 to 0.3% by weight, relative to the total amount of surface treatment agent.

[0086] Furthermore, in the implementation of the present invention, one or more of the above-mentioned triazole compounds (III) may be used, or a combination of two or more may be used. These triazole compounds may also be used in combination with triazole compounds known in the same technical field as the present invention.

[0087] In this invention, the triazole compound (III) is preferably contained in a molar ratio of 0.005 to 3.0 relative to the imidazole compound (I) or benzimidazole compound (II), more preferably in a molar ratio of 0.01 to 2.7, and even more preferably in a molar ratio of 0.05 to 2.5. By making the ratio of triazole compound (III) to imidazole compound (I) or benzimidazole compound (II) within the above range, a highly heat-resistant chemically formed film can be formed.

[0088] The surface treatment agent of the present invention is prepared by dissolving an imidazole compound (I) or a benzimidazole compound (II) and a triazole compound (III) in water. This yields a water-soluble pre-soldering flux.

[0089] Water is not specifically limited, and can be exemplified by tap water, ion-exchange water, purified water, pure water, etc.

[0090] In the surface treatment agent of the present invention, in order to make the imidazole compound (I) or benzimidazole compound (II) and triazole compound (III) readily soluble in water (aqueous solution), a solubilizing agent is preferably contained. As a solubilizing agent, an organic acid or an inorganic acid (sometimes referred to as an acid) is preferably used.

[0091] Representative organic acids include, for example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, isobutyric acid, 2-ethylbutyric acid, oleic acid, glycolic acid, lactic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, gluconic acid, glyceric acid, tartaric acid, malic acid, citric acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid, bromoacetic acid, iodoacetic acid, methoxyacetic acid, ethoxyacetic acid, propoxyacetic acid, butoxyacetic acid, 2-(2-methoxyethoxy)acetic acid, and 2-[2-(2-ethoxy)acetic acid. Ethoxy[ethoxy]acetic acid, 2-{2-[2-(2-ethoxyethoxy)ethoxy]ethoxy}acetic acid, 3-methoxypropionic acid, 3-ethoxypropionic acid, 3-propoxypropionic acid, 3-butoxypropionic acid, acetopropionic acid, glyoxylic acid, pyruvic acid, acetoacetic acid, acrylic acid, butenoic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, trans-butenoic acid, benzoic acid, p-nitrobenzoic acid, picric acid, salicylic acid, p-toluenesulfonic acid, methanesulfonic acid, aminesulfonic acid, etc.; as inorganic acids, examples include hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid, etc. One or more of these acids may be used.

[0092] The solubilizer is preferably contained in a proportion of 0.1 to 50% by weight relative to the total amount of surface treatment agent, and more preferably in a proportion of 0.1 to 40% by weight. By using the proportion of solubilizer in the above range, the imidazole compound (I) or benzimidazole compound (II) and triazole compound (III) are easily soluble in water and easily form a chemical film.

[0093] In embodiments of the present invention, an organic solvent may be used in combination with the aforementioned solubilizer. Preferably, alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, ethylene glycol, and tetrahydrofurfuryl alcohol; celerythrosine such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether; or acetone, N,N-dimethylformamide, acetoacetone, etc., which are freely miscible with water can be used. One or more of these organic solvents may be used.

[0094] The organic solvent is preferably contained in a proportion of 0.1 to 50% by weight, more preferably 1 to 40% by weight, relative to the total amount of surface treatment agent.

[0095] In the surface treatment agent of the present invention, in order to further improve the formation rate (film-forming property) and heat resistance of the formed film, it is preferable to contain halide ions. Examples of halide ions include fluoride ions, chloride ions, bromide ions, and iodide ions, and one or more types may be contained. From the viewpoint of improving the heat resistance of the formed film, it is more preferable that the surface treatment agent contains chloride ions.

[0096] The halide ions are preferably contained in a proportion of 0.005 to 1% by weight relative to the total amount of surface treatment agent, and more preferably 0.01 to 0.1% by weight.

[0097] Halogen ions may be present by adding halogen compounds to the surface treatment agent. Examples of halogen compounds include sodium fluoride, potassium fluoride, ammonium fluoride, sodium chloride, potassium chloride, ammonium chloride, chloropropionic acid, sodium bromide, potassium bromide, ammonium bromide, bromopropionic acid, sodium iodide, potassium iodide, ammonium iodide, iodopropionic acid, etc., and one type may be used alone or two or more types may be used in combination.

[0098] In order to further improve the heat resistance of the formed coating film, the surface treatment agent of the present invention preferably contains zinc ions. The zinc ions are preferably contained in a proportion of 0.05 to 2% by weight, more preferably 0.1 to 1% by weight.

[0099] Zinc ions may be present by adding a zinc compound as an additive to the surface treatment agent. Examples of such zinc compounds include zinc oxide, zinc formate, zinc acetate, zinc oxalate, zinc lactate, zinc citrate, zinc sulfate, zinc nitrate, zinc phosphate, zinc chloride, zinc bromide, and zinc iodide. One type may be used alone, or two or more types may be used in combination.

[0100] In the surface treatment agent of the present invention, in order to improve the formation rate (film-forming property) of the chemically formed film on the copper surface, it is preferable to contain copper ions. Relative to the total amount of the surface treatment agent, copper ions are preferably contained in a proportion of 0.005 to 1% by weight, more preferably 0.01 to 0.1% by weight.

[0101] Zinc ions may be present by adding a copper compound as an additive to the surface treatment agent. Examples of such copper compounds include copper formate, copper acetate, copper oxalate, cuprous chloride, copper chloride, cuprous bromide, copper bromide, cuprous iodide, copper hydroxide, copper phosphate, copper sulfate, and copper nitrate. One type may be used alone, or two or more types may be used in combination.

[0102] In addition to the aforementioned halogen compounds, zinc compounds, and copper compounds, the surface treatment agent of the present invention may also include metal compounds such as manganese compounds, cobalt compounds, and nickel compounds, or coordination compounds such as crown ethers, bipyridines, porphyrins, and phenobarbital as additives to improve the film-forming properties or enhance the physical properties of the formed film. Furthermore, examples of manganese compounds include manganese formate, manganese chloride, manganese oxalate, manganese sulfate, and manganese carbonate; examples of cobalt compounds include cobalt acetate, cobalt sulfate, and cobalt nitrate; and examples of nickel compounds include nickel chloride, nickel acetate, nickel nitrate, nickel carbonate, and nickel sulfate. Regarding these metal compounds, one type or two or more types may be used, preferably in a proportion of 0.05 to 2% by weight relative to the total amount of the surface treatment agent, more preferably 0.1 to 1% by weight. Similarly, regarding coordination compounds, one or more can be used in combination, preferably in a proportion of 0.05 to 2% by weight relative to the total amount of surface treatment agent, more preferably 0.1 to 1% by weight.

[0103] In the surface treatment agent of the present invention, in order to suppress the formation of the chemically formed film on the gold (Au) surface and at the same time improve the film-forming property of the chemically formed film on the copper surface, a binding agent and / or an iron compound may be contained as an additive (refer to Japanese Patent Application Publication No. 9-291372, which is incorporated herein by reference).

[0104] Examples of the aforementioned binding agents include iminodiacetic acid, triacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, 1,2-diaminocyclohexanetetraacetic acid, ethylene glycol diaminoethyl ethertetraacetic acid, N,N-bis(2-hydroxybenzyl)ethylenediaminediacetic acid, ethylenediaminedipropionic acid, ethylenediaminediacetic acid, diaminopropanoltetraacetic acid, hexamethylenediaminetetraacetic acid, hydroxyethyliminodiacetic acid, diaminopropanetetraacetic acid, triacetic acid, ethylenediamine-N,N'-disuccinic acid, ethylenediaminetetramethylene phosphorous acid, triacetic acid, 2-phosphatidylbutane-1,2,4-tricarboxylic acid, and their salts. The binding agent is preferably contained in a proportion of 0.01 to 0.4% by weight.

[0105] From the viewpoint of the film-forming properties (formation speed) of the chemically formed film, the surface treatment agent of the present invention preferably has a pH of 2.0 to 5.0, more preferably 2.2 to 4.8, and even more preferably 2.5 to 4.5.

[0106] Furthermore, when lowering the pH of the surface treatment agent, the aforementioned organic or inorganic acids can be used; when raising the pH, an alkali can be used. As an alkali, in addition to sodium hydroxide or potassium hydroxide, examples include ammonia or amines such as monoethanolamine, diethanolamine, triethanolamine, and triisopropanolamine. It is preferable to use substances with buffering properties, such as amines, as an alkali.

[0107] By bringing the surface treatment agent of the present invention into contact with a copper surface, a chemically formed film can be formed on the copper surface. When treating a copper surface using the surface treatment agent of the present invention, it is preferable to set the liquid temperature of the surface treatment agent to a range of 10~70°C and the contact time to a range of 1 second~10 minutes. Methods for contacting the copper with the surface treatment agent for treating the copper surface include, for example, immersion, spraying, and coating.

[0108] After the surface treatment agent comes into contact with the copper surface, it is preferable to rinse with water as needed, and then allow the copper surface to dry. Drying is preferably performed at a temperature of 60-120°C, preferably between room temperature (e.g., 20°C) and 150°C, and for a time of approximately 1 second to 10 minutes, preferably between 10 seconds and 3 minutes. Furthermore, the water used for rinsing is preferably pure water such as ion-exchanged water, distilled water, or purified water. There are no particular limitations on the method or time of rinsing; it can be performed for an appropriate time using methods such as spraying or immersion.

[0109] Before the surface treatment agent comes into contact with the copper surface, a pre-impregnation solution containing an azole compound may also be brought into contact with the copper surface. This pre-impregnation solution has the function of improving the film-forming properties of the chemically formed film on the copper surface. There are no particular limitations on the azole compound, and examples include commercially available imidazole compounds, triazole compounds, tetraazole compounds, etc. In addition to the azole compound, the pre-impregnation solution also contains water and additives. As additives, it may also contain, for example, the aforementioned organic solvents, amines, copper compounds, halogen compounds, or other additives (such as ammonium salts such as ammonium sulfate, ammonium formate, ammonium acetate, ammonium chloride, ammonium carbonate, and ammonium nitrate).

[0110] The thickness of the formed OSP film (surface treatment film) formed by the surface treatment agent of the present invention is preferably 0.10 to 0.50 μm. If the film thickness is 0.10 μm or more, sufficient heat resistance can be imparted, thus achieving the desired effect of the present invention. Furthermore, if the film thickness is 0.50 μm or less, good weldability can be maintained.

[0111] In addition to the conventional Sn-Pb eutectic solder, the solder used in the implementation of the present invention can also include lead-free solders such as Sn-Ag-Cu, Sn-Ag-Bi, Sn-Bi, Sn-Ag-Bi-In, Sn-Zn, and Sn-Cu.

[0112] Furthermore, the soldering method of the present invention can be applied to: a flow soldering method in which a printed circuit board with electronic components mounted is brought into contact with the surface of molten solder in a solder bath while being moved, thereby soldering the joint between the electronic components and the printed circuit board; or a reflow soldering method in which a paste-like solder paste is pre-printed on the printed circuit board in accordance with a circuit pattern, electronic components are mounted on it, and the printed circuit board is heated to melt the solder for soldering, etc. [Example]

[0113] The present invention will be described in more detail below by way of examples and comparative examples, but the present invention is not limited thereto.

[0114] [Imidazole Compounds] The imidazole compounds used in the examples are as follows.

[0115] (Synthesis Example 1) <Synthesis of 4-(3,4-dichlorophenyl)-5-methyl-2-nonylimidazole (A-1)> According to the method disclosed in Japanese Patent Application Publication No. 2010-77071, the imidazole compound "4-(3,4-dichlorophenyl)-5-methyl-2-nonylimidazole" (sometimes simply referred to as "A-1") was synthesized.

[0116] (Synthesis Example 2) <Synthesis of 2-phenyl-4-(1-naphthyl)-5-methylimidazolium (A-2)> According to the method disclosed in Japanese Patent Application Publication No. 2006-36683, the imidazole compound "2-phenyl-4-(1-naphthyl)-5-methylimidazolium (A-2)" (sometimes simply referred to as "A-2") was synthesized.

[0117] (Synthesis Example 3) <Synthesis of 5-methyl-4-phenyl-2-(2-thienyl)imidazolium (A-3)> According to the method disclosed in Japanese Patent Application Publication No. 2014-37370, the imidazolium compound "5-methyl-4-phenyl-2-(2-thienyl)imidazolium" (sometimes simply referred to as "A-3") was synthesized.

[0118] (Synthesis Example 4) <Synthesis of 2-(3-chlorobenzyl)-4-(1-naphthyl)imidazolium (A-4)> The imidazole compound "2-(3-chlorobenzyl)-4-(1-naphthyl)imidazolium" (sometimes simply referred to as "A-4") was synthesized according to the method disclosed in Japanese Patent Application Publication No. 2010-90105.

[0119] The chemical formulas of the imidazole compounds A-1 to A-4 are shown below.

[0120] [Chemistry 14]

[0121] [Benzimazole compound] The benzimidazole compound used in the examples is as follows.

[0122] (Synthesis Example 5) <Synthesis of 2-nonylbenzimidazole (B-1)> The benzimidazole compound "2-nonylbenzimidazole" (sometimes simply referred to as "B-1") was synthesized according to the method disclosed in Japanese Patent Application Publication No. 5-107814.

[0123] (Synthesis Example 6) <Synthesis of 6-chloro-2-(3,4-dichlorophenylmethyl)benzimidazole (B-2)> The benzimidazole compound "6-chloro-2-(3,4-dichlorophenylmethyl)benzimidazole" (sometimes simply referred to as "B-2") was synthesized by the following method. 133.0 g (0.715 mol) of 3,4-dichlorobenzyl nitrile was mixed with 190 g of dehydrated dichloromethane, and then 36.4 g (0.790 mol) of dehydrated ethanol was added. While stirring under ice, 29.6 g (0.812 mol) of hydrogen chloride gas was gradually blown in small amounts, and the mixture was stirred overnight at below 5°C. The resulting product was concentrated under reduced pressure to give 192.1 g (0.715 mol, 100% yield) of 2-(3,4-dichlorophenyl)ethaneimino ethyl hydrochloride as a white powder. 25.4 g (0.178 mol) of 4-chloro-1,2-phenylenediamine was mixed with 200 mL of dehydrated methanol, and then 48.0 g (0.179 mol) of 2-(3,4-dichlorophenyl)ethaneimino ethyl hydrochloride was added. After stirring under reflux for 2 hours, 23.6 g of 25% ammonia water was added. Subsequently, the mixture was concentrated under reduced pressure to obtain 76.4 g of a dark brown tar-like product. This product was stirred in hot water, and the resulting solid was hot-filtered, pulverized in a mortar, and then 400 mL of water was added and heated. After cooling, crystallization and filtration were performed to obtain dark purple crystals. Methanol and activated carbon were added, and the mixture was heated and stirred, then filtered. The filtrate was concentrated under reduced pressure, and the resulting product was recrystallized with acetonitrile to obtain 33.7 g (0.108 mol, yield 60.9%) of a milky white powder of 6-chloro-2-(3,4-dichlorophenylmethyl)benzimidazole compound.

[0124] (Synthesis Example 7) <Synthesis of 2-(2-naphthylmethyl)benzimidazole (B-3)> The benzimidazole compound "2-(2-naphthylmethyl)benzimidazole" (sometimes simply referred to as "B-3") was synthesized by the following method. 50.9 g (0.273 mol) of 2-naphthylacetic acid and 29.5 g (0.273 mol) of o-phenylenediamine were mixed and heated until no more water was exuded, yielding a purple solid. The obtained solid was ground into powder using a mortar and pestle, and then 1 L of water and 88 g of sodium carbonate were added and stirred under reflux for 30 minutes. After hot filtration, the same operation was repeated on the obtained solid. Methanol and activated carbon were added to the mixture, and the mixture was heated, stirred, and filtered. Water was added to the filtrate in small amounts as a solvent-poor solution to induce crystallization. The crystals were washed with methanol and water and then dried to obtain 39.4 g (0.153 mol, yield 55.8%) of pale yellow crystalline 2-(2-naphthylmethyl)benzimidazole. The chemical formulas of the benzimidazole compounds B-1 to B-3 are shown below.

[0126] [Chemistry 15]

[0127] [Triazole Compounds] The triazole compounds used in the examples are as follows.

[0128] (Synthesis Example 8) <Synthesis of 3-amino-1,2,4-triazol-1-acetic acid (C-1)> The triazole compound "3-amino-1,2,4-triazol-1-acetic acid" (sometimes simply referred to as "C-1") was synthesized by the following method. 30.1 g (0.357 mol) of 3-amino-1,2,4-triazole was mixed with 200 mL of methanol, and an aqueous solution of sodium hydroxide, pre-mixed with 14.5 g (0.363 mol) of sodium hydroxide and 80.0 g of water, was added gradually in small amounts. Subsequently, 41.6 g (0.357 mol) of sodium monochloroacetate was added and the mixture was heated and stirred under reflux overnight. The resulting product was concentrated under reduced pressure, and 100 mL of water was added. While cooling, 36.1 g of 36% hydrochloric acid was added gradually in small amounts. After filtering the precipitate, it was washed with water and dried to obtain 24.3 g (0.171 mol, yield 47.8%) of white powder 3-amino-1,2,4-triazol-1-acetic acid.

[0129] (Synthesis Example 9) <Synthesis of 5-methyl-3-octyl-1,2,4-triazole (C-2)> The triazole compound "5-methyl-3-octyl-1,2,4-triazole" (sometimes simply referred to as "C-2") was synthesized by the following method. 37.26 g (0.200 mol) of ethyl nonanoate was mixed with 100 g of methanol, and 20.02 g (0.400 mol) of hydrazine monohydrate was further added at room temperature and stirred for 1 hour. The mixture was then heated and stirred under reflux overnight. The crystals precipitated by cooling were filtered, washed with a small amount of methanol, and dried to give 28.26 g (0.164 mol, yield 82.0%) of white scaly crystalline hydrazine nonanoate. 15.60 g (0.165 mol) of acetamiprid hydrochloride was mixed with 100 g of methanol, followed by the addition of 34.72 g (0.180 mol) of 28% sodium methoxide / methanol solution and 25.84 g (0.150 mol) of hydrazine nonanoate. The mixture was stirred under reflux overnight, cooled, and filtered to remove NaCl. The filtrate was then concentrated under reduced pressure. 80 g of toluene and 80 g of water were added to the concentrate to dissolve the product in toluene. The organic layer was separated, and the concentrate was concentrated under reduced pressure to a total volume of 40 g. This concentrate was cooled and crystallized, then filtered and dried to obtain 20.51 g (0.105 mol, 70.0%) of 5-methyl-3-octyl-1,2,4-triazole as a white powder.

[0130] (Synthesis Example 10) <Synthesis of 3-benzyl-5-phenyl-1,2,4-triazole (C-3)> The triazole compound "3-benzyl-5-phenyl-1,2,4-triazole" (sometimes simply referred to as "C-3") was synthesized by the following method. 31.3 g (0.200 mol) of benzamide hydrochloride was mixed with 300 mL of ethanol, and a solution of 240 mL of ethanol and 14.0 g (0.259 mol) of sodium methoxide was added. After filtering to remove the precipitated NaCl, 3.00 g (0.200 mol) of phenylacetic acid hydrazine was added to the resulting filtrate. After stirring under reflux for 1 hour, the reaction solution was concentrated under reduced pressure to obtain 55.1 g of a tar-like product. Water was added and stirred, the resulting solid was filtered, dried, and then recrystallized by diethyl ether and dried to obtain 14.4 g (0.061 mol, yield 30.6%) of white powder 3-benzyl-5-phenyl-1,2,4-triazole.

[0131] (Synthetic Example 11) <Synthesis of 3,3'-methylenebis(5-amino-1,2,4-triazole)(C-4)> The triazole compound "3,3'-methylenebis(5-amino-1,2,4-triazole" (sometimes simply referred to as "C-4")" was synthesized according to the method described in Russ. J. Applied Chem., 82(2), 276(2009).

[0132] The chemical formulas of triazole compounds of C-1 to C-4 are shown below.

[0133] [Chemical 16]

[0134] The evaluation test methods used in the examples and comparative examples are as follows.

[0135] [Evaluation Test of Solder Rise Rate] A 120mm (longitudinal) × 150mm (horizontal) × 1.6mm (thickness) glass epoxy resin printed wiring board with 300 copper vias of inner diameters of 0.60, 0.80, and 1.00mm was used as a test piece. This test piece was subjected to soft etching, washing, and drying under the following conditions, then immersed in a pre-immersion solution maintained at a predetermined temperature for a predetermined time, washed, and dried, followed by immersion in a surface treatment agent maintained at a predetermined temperature, and then washed and dried to perform surface treatment, thereby forming a formation film of approximately 0.2μm thickness on the copper surface. This surface-treated test piece was then subjected to reflow heating using an infrared combined with hot air reflow apparatus (product name: SNR-725GT-MH, manufactured by Senju Metal Industries, Ltd.) under the conditions described in Tables 1-6, followed by soldering using a reflow soldering apparatus (conveyor speed: 1.0m / min). Furthermore, the solder used was "ECO SOLDER M705" (trade name, Sn-3.0Ag-0.5Cu lead-free solder) manufactured by Senju Metal Industries, Ltd., and the flux used during soldering was "ES-1062V-1" (trade name) manufactured by Senju Metal Industries, Ltd. The soldering temperature was set to 250°C. For the test pieces that underwent soldering, the number of vias in the copper vias that reached the upper connecting pad (after soldering) was measured, and the percentage (% rise rate) relative to the total number of vias (900 vias) was calculated. The greater the wettability of the solder on the copper surface, the easier it is for the molten solder to penetrate into the copper vias and rise to the upper connecting pad portion of the via. In other words, the higher the percentage of vias where solder rises to the upper connecting pad relative to the total number of vias, the better the solder wettability to copper and the better the solderability.

[0136] [Surface Treatment of Test Pieces] The test pieces were treated according to the following steps i~iii. i. Acid cleaning / 1 minute (room temperature), water washing, drying / 1 minute (100°C) ii. Immersion in pre-impregnation solution (PT20 manufactured by Shikoku Chemical Industry Co., Ltd.) / 30 seconds (30°C), water washing, drying / 1 minute (100°C) iii. Immersion in surface treatment solution / 1 minute (40°C), water washing, drying / 1 minute (100°C)

[0137] (Example 1) 2-(3-chlorobenzyl)-4-(1-naphthyl)imidazolium (A-4), 3-amino-1,2,4-triazol-1-acetic acid (C-1), acetic acid, and heptanoic acid were dissolved in deionized water, and the pH was adjusted to 3.20 with ammonia water to prepare a surface treatment agent with the composition listed in Table 1. The obtained surface treatment agent was used to conduct the above-mentioned solder rise rate evaluation test, and the solder rise rate (%) was measured. The reflow conditions were as described in Table 1, with the peak temperature set at 260°C, and the heating was performed twice. The test results are shown in Table 1.

[0138] (Examples 2-16, Comparative Examples 1-4) The same procedures as in Example 1 were followed. The surface treatment agent was prepared according to the composition described in Tables 1-2. Using the obtained surface treatment agent, an evaluation test of solder rise rate was conducted according to the treatment conditions described in Tables 1-2, and the solder rise rate (%) was measured. The test results are shown in Tables 1-2.

[0139] [Table 1] Example Comparative example Example Comparative example 1 2 3 4 1 5 6 7 8 2 Surface treatment agent composition (weight %) imidazole compounds A-4 0.2 0.2 0.2 0.2 0.2 benzimidazole compounds B-1 0.2 0.2 0.2 0.2 0.2 Triazole compounds C-1 0.1 0.1 C-2 0.075 0.05 C-3 0.025 0.025 C-4 0.01 0.1 acid Acetic acid 20 20 20 20 20 20 20 20 20 20 heptanoic acid 0.1 0.1 0.1 0.1 0.1 The ratio of triazole compounds to imidazole compounds or benzimidazole compounds (molar ratio) 1.12 0.61 0.17 0.09 ‒ 0.86 0.31 0.13 0.68 ‒ pH 3.20 3.20 3.20 3.25 3.20 3.60 3.60 3.60 3.65 3.50 Thickness of the membrane formed (μm) 0.22 0.19 0.22 0.21 0.17 0.20 0.21 0.23 0.22 0.18 Evaluation test Reflow conditions Peak temperature (°C) 260 250 Number of heating cycles 2 3 Solder rise rate (%) 98 97 99 67 56 52 26 72 38 10 A-4: 2-(3-chlorobenzyl)-4-(1-naphthyl)imidazolium B-1: 2-nonylbenzimidazole C-1: 3-amino-1,2,4-triazole-1-acetic acid C-2: 5-methyl-3-octyl-1,2,4-triazole C-3: 3-benzyl-5-phenyl-1,2,4-triazole C-4: 3,3'-methylenebis(5-amino-1,2,4-triazole)

[0140] [Table 2] Example Comparative example Example Comparative example 9 10 11 12 3 13 14 15 16 4 surface noodle Place reason Agent Group become (Heavy quantity %) imidazole compounds A-4 0.2 0.2 0.2 0.2 0.2 benzimidazole compounds B-1 0.2 0.2 0.2 0.2 0.2 Triazole compounds C-1 0.1 0.1 C-2 0.075 0.05 C-3 0.025 0.025 C-4 0.01 0.1 halide ions Cl - (Sodium chloride) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) acid Acetic acid 20 20 20 20 20 20 20 20 20 20 heptanoic acid 0.1 0.1 0.1 0.1 0.1 Triazole compounds relative to imidazole compounds or benzene The ratio (molar ratio) of imidazole compounds 1.12 0.61 0.17 0.09 ‒ 0.86 0.31 0.13 0.68 ‒ pH 3.20 3.20 3.20 3.25 3.20 3.60 3.60 3.60 3.60 3.50 Thickness of the membrane formed (μm) 0.20 0.20 0.21 0.18 0.21 0.20 0.22 0.21 0.17 0.23 Evaluation test Reflow conditions Peak temperature (°C) 260 250 Number of heating cycles (times) 3 3 Soldering rise rate (%) 35 43 59 34 15 93 99 91 90 83 A-4: 2-(3-chlorobenzyl)-4-(1-naphthyl)imidazolium B-1: 2-nonylbenzimidazole C-1: 3-amino-1,2,4-triazole-1-acetic acid C-2: 5-methyl-3-octyl-1,2,4-triazole C-3: 3-benzyl-5-phenyl-1,2,4-triazole C-4: 3,3'-methylenebis(5-amino-1,2,4-triazole)

[0141] As can be seen from the comparison between Examples 1-4 and Comparative Example 1, Examples 5-8 and Comparative Example 2, Examples 9-12 and Comparative Example 3, and Examples 13-16 and Comparative Example 4, the solder rise rate is increased because the surface treatment agent contains a triazole compound (III) together with an imidazole compound (I) or a benzimidazole compound (II). Therefore, the surface treatment agents of Examples 1-16 result in a coating with superior heat resistance.

[0142] (Examples 17-20, Comparative Examples 5-8) The same procedures as in Example 1 were followed. The surface treatment agent was prepared according to the composition described in Table 3. Using the obtained surface treatment agent, an evaluation test of solder rise rate was conducted according to the treatment conditions described in Table 3, and the solder rise rate (%) was measured. The test results are shown in Table 3.

[0143] [Table 3] Example Comparative example Example Comparative example Example Comparative example Example Comparative example 17 5 18 6 19 7 20 8 Surface treatment agent composition (weight %) imidazole compounds A-4 0.2 0.2 0.2 0.2 benzimidazole compounds B-1 0.2 0.2 0.2 0.2 Triazole compounds C-1 0.1 0.1 0.1 0.1 halide ions Br - (Ammonium bromide) 0.09 (0.20) 0.09 (0.20) 0.09 (0.20) 0.09 (0.20) I - (Sodium iodide) 0.01 (0.013) 0.01 (0.013) 0.01 (0.013) 0.01 (0.013) acid Acetic acid 20 20 20 20 20 20 20 20 heptanoic acid 0.2 0.2 0.2 0.2 The ratio of triazole compounds to imidazole compounds or benzimidazole compounds (molar ratio) 1.12 ‒ 1.12 ‒ 0.86 ‒ 0.86 ‒ pH 3.40 3.30 3.40 3.30 3.60 3.60 3.60 3.60 Thickness of the membrane formed (μm) 0.21 0.22 0.19 0.20 0.21 0.23 0.22 0.18 Evaluation test Reflow conditions Peak temperature (°C) 260 250 240 240 Number of heating cycles 2 3 3 3 Solder rise rate (%) 42 1 68 46 89 43 94 89 A-4: 2-(3-chlorobenzyl)-4-(1-naphthyl)imidazol B-1: 2-Nonylbenzimidazole C-1: 3-Amino-1,2,4-triazol-1-acetic acid

[0144] As can be seen from the comparison between Example 17 and Comparative Example 5, Example 18 and Comparative Example 6, Example 19 and Comparative Example 7, and Example 20 and Comparative Example 8, the solder rise rate is increased when the surface treatment agent contains triazole compound (III) together with imidazole compound (I) or benzimidazole compound (II) in a system containing bromide ions or iodide ions as halide ions.

[0145] (Examples 21-30, Comparative Examples 9-18) The same procedures as in Example 1 were followed. The surface treatment agent was prepared according to the composition described in Tables 4-5. Using the obtained surface treatment agent, an evaluation test of solder rise rate was conducted according to the treatment conditions described in Tables 4-5, and the solder rise rate (%) was measured. The test results are shown in Tables 4-5.

[0146] [Table 4] Example Comparative example Example Comparative example Example Comparative example Example Comparative example Example Comparative example twenty one 9 twenty two 10 twenty three 11 twenty four 12 25 13 Surface treatment agent composition (weight %) imidazole compounds A-1 0.2 0.2 A-2 0.2 0.2 A-3 0.2 0.2 benzimidazole compounds B-2 0.2 0.2 B-3 0.2 0.2 Triazole compounds C-1 0.2 0.1 0.1 0.1 0.05 halogen ions Cl - (Sodium chloride) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) acid Formic acid 2 2 Acetic acid 40 40 20 20 15 15 20 20 15 15 heptanoic acid 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 The ratio of triazole compounds to imidazole compounds or benzimidazole compounds (molar ratio) 2.49 ‒ 1.00 ‒ 0.85 ‒ 1.10 ‒ 0.45 ‒ pH 3.10 3.10 3.10 3.10 4.20 4.20 2.65 2.65 3.50 3.50 Thickness of the membrane formed (μm) 0.20 0.21 0.22 0.21 0.19 0.20 0.22 0.20 0.19 0.20 Evaluation test Reflow conditions (wave temperature / number of cycles) Peak temperature (°C) 250 240 240 260 250 Number of heating cycles 3 2 3 3 3 Solder rise rate (%) 70 60 93 36 78 63 80 31 87 46 A-1: 4-(3,4-dichlorophenyl)-5-methyl-2-nonylimidazole A-2: 2-phenyl-4-(1-naphthyl)-5-methylimidazole A-3: 5-methyl-4-phenyl-2-(2-thienyl)imidazole B-2: 6-chloro-2-(3,4-dichlorophenylmethyl)benzimidazole B-3: 2-(2-naphthylmethyl)benzimidazole C-1: 3-amino-1,2,4-triazol-1-acetic acid

[0147] [Table 5] Example Comparative example Example Comparative example Example Comparative example Example Comparative example Example Comparative example 26 14 27 15 28 16 29 17 30 18 Surface treatment agent composition (weight %) imidazole compounds A-1 0.2 0.2 A-2 0.2 0.2 A-3 0.2 0.2 benzimidazole compounds B-2 0.2 0.2 B-3 0.2 0.2 Triazole compounds C-1 0.2 0.1 0.1 0.1 0.05 acid Formic acid 2 2 Acetic acid 40 40 20 20 15 15 20 20 15 15 heptanoic acid 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 The ratio of triazole compounds to imidazole compounds or benzimidazole compounds (molar ratio) 2.49 ‒ 1.00 ‒ 0.85 ‒ 1.10 ‒ 0.45 ‒ pH 3.10 3.10 3.10 3.10 4.20 4.20 2.65 2.65 3.50 3.50 Thickness of the membrane formed (μm) 0.19 0.20 0.2 0.21 0.19 0.20 0.22 0.21 0.21 0.20 Evaluation test Reflow conditions Peak temperature (°C) 250 250 250 260 260 Number of heating cycles 3 3 2 3 3 Solder rise rate (%) 68 47 52 8 100 89 97 82 12 1 A-1: 4-(3,4-dichlorophenyl)-5-methyl-2-nonylimidazole A-2: 2-phenyl-4-(1-naphthyl)-5-methylimidazole A-3: 5-methyl-4-phenyl-2-(2-thienyl)imidazole B-2: 6-chloro-2-(3,4-dichlorophenylmethyl)benzimidazole B-3: 2-(2-naphthylmethyl)benzimidazole C-1: 3-amino-1,2,4-triazol-1-acetic acid

[0148] When 4-(3,4-dichlorophenyl)-5-methyl-2-nonylimidazole (A-1), 2-phenyl-4-(1-naphthyl)-5-methylimidazole (A-2) and 5-methyl-4-phenyl-2-(2-thienyl)imidazole (A-3) are added as imidazole compounds (I), and 6-chloro-2-(3,4-dichlorophenylmethyl)benzimidazole (B-2) and 2-(2-naphthylmethyl)benzimidazole (B-3) are used as benzimidazole compounds (II), the solder rise rate is also improved because the surface treatment agent contains triazole compounds (III) together with imidazole compounds (I) or benzimidazole compounds (II).

[0149] (Examples 31-32, Comparative Examples 19-20) The same procedures as in Example 1 were followed. The surface treatment agent was prepared according to the composition described in Table 6. Using the obtained surface treatment agent, an evaluation test of solder rise rate was conducted according to the treatment conditions described in Table 6, and the solder rise rate (%) was measured. The test results are shown in Table 6.

[0150] [Table 6] Example Comparative example Example Comparative example 31 19 32 20 surface noodle Place reason Agent Group become (Heavy quantity %) imidazole compounds A-2 0.2 0.2 A-3 0.2 0.2 Triazole compounds C-1 0.1 0.1 halide ions Cl - (Sodium chloride) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) 0.09 (0.15) acid Formic acid 2 2 Acetic acid 20 20 15 15 heptanoic acid 0.1 0.1 0.1 0.1 metal ions Zn 2+ (Zinc acetate) 0.3 (1.0) 0.3 (1.0) 0.3 (1.0) 0.3 (1.0) Clamping agent Geditamin (GEDTA) 0.06 0.06 0.06 0.06 Triazole compounds relative to imidazole compounds Or the ratio (molar ratio) of benzimidazole compounds. 1.00 ‒ 0.85 ‒ pH 3.10 3.10 4.20 4.20 Thickness of the membrane formed (μm) 0.20 0.19 0.19 0.21 evaluate test Reflow conditions Peak temperature (°C) 240 240 Number of heating cycles 2 2 Solder rise rate (%) 94 89 100 87 A-2: 2-Phenylacetyl-4-(1-naphthyl)-5-methylimidazolium A-3: 5-Methyl-4-phenyl-2-(2-thienyl)imidazolium C-1: 3-Amino-1,2,4-triazol-1-acetic acid

[0151] As can be seen from the comparison between Example 31 and Comparative Example 19, and Example 32 and Comparative Example 20, the solder rise rate is increased because the surface treatment agent contains triazole compound (III) together with imidazole compound (I) in the system containing metal ions.

[0152] The present invention has been described above with reference to detailed and specific embodiments. However, it will be understood by those skilled in the art that various changes or modifications can be made without departing from the spirit and scope of the present invention. This application is incorporated herein by reference to Japanese Patent Application No. 2022-054331, filed on March 29, 2022. (Industrial Applicability) According to the present invention, when electronic components such as solder are bonded to a printed circuit board, a chemically formed film with excellent heat resistance and wettability with solder is formed on the surface of copper or copper alloy of the circuit components of the printed circuit board, thereby providing a surface treatment agent and surface treatment method with good solderability.

Claims

1. A surface treatment agent for copper or copper alloys, comprising: an imidazole compound represented by chemical formula (I) or a benzimidazole compound represented by chemical formula (II); and a triazole compound represented by chemical formula (III-1), chemical formula (III-2), chemical formula (III-4), or chemical formula (III-5); [Chemical 1] (in formula (I), R1 represents a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms, a cycloalkyl group, a phenyl group that may have a substituent, a naphthyl group that may have a substituent, a benzyl group that may have a substituent, a naphthylmethyl group, -CH-(Ph)2, -(CH2)k-Ph, a thiophene group, a thiophene methyl group, a furanyl group, or a pyridyl group; wherein, Ph represents a phenyl group that may also have substituents, and k represents an integer from 2 to 5; R2 may be the same or different, representing a hydrogen atom, a straight-chain or branched alkyl group with 1 to 18 carbon atoms, a cycloalkyl group, a phenyl group that may also have substituents, a naphthyl group that may also have substituents, a thiophene group, or a furanyl group; where R2 is excluded from being a hydrogen atom at the same time); [Chemical 2] (In formula (II), R3 represents a straight-chain or branched alkyl group with 1 to 18 carbon atoms, -(CH2)m-Ph, -(CH2)m-Np, or a group shown in formula (1), Ph represents a phenyl group that may also have substituents, Np represents a naphthyl group that may also have substituents, and m represents an integer from 1 to 5; [Chemical 3] (In formula (1), m represents an integer from 1 to 5); R4 may be the same or different, representing a hydrogen atom, a straight-chain or branched alkyl group with 1 to 18 carbon atoms, a nitro group, or a halogen atom); [Chemical 4] (In formula (III-1), R513 represents a hydrogen atom, an amino group, or a phenyl group that may also have substituents; R515 represents a hydrogen atom, an amino group, or a phenyl group that may also have substituents; s represents an integer from 1 to 3. In formula (III-2), R523 represents a straight-chain or branched-chain alkyl or pyridyl group with 1 to 18 carbon atoms; R525 represents a hydrogen atom, a straight-chain or branched-chain alkyl group with 1 to 18 carbon atoms, a phenyl group that may also have substituents, or a benzyl or pyridyl group that may also have substituents. In formula (III-4), R545 represents a hydrogen atom, a phenyl group that may also have substituents, or a benzyl group that may also have substituents. In formula (III-5), t represents an integer from 0 to 6.) 2. A surface treatment agent for copper or copper alloys as described in claim 1, wherein, It further contains halide ions.

3. A surface treatment agent for copper or copper alloys as described in claim 2, wherein, The halide ions mentioned above are chloride ions.

4. A surface treatment agent for copper or copper alloys as described in any of claims 1 to 3, wherein, It further contains zinc ions.

5. A surface treatment agent for copper or copper alloys as described in any of claims 1 to 3, wherein, The triazole compounds represented by the above chemical formulas (III-1), (III-2), (III-4), or (III-5) are contained in a molar ratio of 0.005 to 3.0 relative to the imidazole compound represented by the above chemical formula (I) or the benzimidazole compound represented by the above chemical formula (II).

6. A surface treatment agent for copper or copper alloys as described in any of claims 1 to 3, wherein, pH is 2-5.