JP5313044B2 - Surface treatment agent for copper or copper alloy and use thereof - Google Patents

Abstract

A surface treating agent for copper or a copper alloy, which contains an imidazole compound represented by the formula (I): wherein R represents a hydrogen atom or an alkyl group, X1 and X2 are the same or different and represent a chlorine atom or a bromine atom; m and n represent an integer of 0 to 3 and at least one of m or n is 1 or more. The surface treating agent is also used in surface treating methods, in making printed wiring boards and in soldering methods.

Description

  The present invention relates to a surface treatment agent used when soldering an electronic component or the like to copper or a copper alloy of a printed wiring board, and the use thereof.

Recently, surface mounting with improved mounting density has been widely adopted as a method for mounting printed wiring boards. Such surface mounting methods can be classified into double-sided surface mounting in which chip components are joined by cream solder, mixed mounting in which surface mounting by chip solder cream soldering and through-hole mounting of discrete components are combined. In any mounting method, since the printed wiring board is soldered a plurality of times, it is exposed to a high temperature each time and receives a severe thermal history.
As a result, the surface of the copper or copper alloy (hereinafter sometimes simply referred to as copper) constituting the circuit part of the printed wiring board is heated to promote the formation of an oxide film. It is not possible to maintain good solderability.

  In order to protect the copper circuit portion of such a printed wiring board from air oxidation, a treatment for forming a chemical conversion film on the surface of the circuit portion using a surface treatment agent is widely performed. It is required to protect the copper circuit portion without changing (deteriorating) the chemical film even after receiving the heat history of the times, thereby maintaining good solderability.

Conventionally, tin-lead alloy eutectic solder has been widely used for joining electronic components to printed wiring boards, etc., but in recent years there is concern about the harmfulness of the lead contained in the solder alloy to the human body. There is a need to use solder that does not contain lead.
For this purpose, various lead-free solders have been studied. For example, lead-free solders having a metal such as silver, zinc, bismuth, indium, antimony and copper as a base metal have been proposed.

By the way, the conventional tin-lead eutectic solder has excellent wettability with respect to the metal used for the bonding base material, particularly copper, and is firmly bonded to copper, so that the bonding property between the copper members is high. Reliability is obtained.
In contrast, lead-free solder is inferior in wettability to the copper surface compared to conventional tin-lead solder, so solderability is poor, bonding defects such as voids occur, and bonding strength is low Met.
Therefore, when using lead-free solder, selection of a solder alloy with better solderability and a flux suitable for lead-free solder is required, but surface treatment used to prevent oxidation of copper or copper alloy surfaces Also for the agent, a function of improving the wettability of the lead-free solder and improving the solderability is required.
In addition, most lead-free solders have a high melting point, and the soldering temperature is about 20 to 50 ° C. higher than that of conventional tin-lead eutectic solder. Therefore, the surface treatment agent has excellent heat resistance. It is also desired to form a chemical conversion film.

  Various imidazole compounds have been proposed as active ingredients of such surface treatment agents. For example, Patent Document 1 includes 2-alkylimidazole compounds such as 2-undecylimidazole, and Patent Document 2 includes 2-arylimidazole compounds such as 2-phenylimidazole and 2-phenyl-4-methylimidazole. Patent Document 3 discloses a 2-alkylbenzimidazole compound such as 2-nonylbenzimidazole, and Patent Document 4 discloses a 2-aralkylbenzimidazole compound such as 2- (4-chlorophenylmethyl) benzimidazole. Discloses 2-aralkylimidazole compounds such as 2- (4-chlorophenylmethyl) imidazole and 2- (2,4-dichlorophenylmethyl) 4,5-diphenylimidazole.

  However, when the surface treatment agent containing these imidazole compounds is used, the heat resistance of the chemical conversion film formed on the copper surface has not yet been satisfactory. Also, when soldering, the solder wettability is insufficient, and good solderability cannot be obtained. In particular, in the case where soldering is performed using lead-free solder instead of eutectic solder, the surface treatment agent is difficult to be practically used.

Japanese Patent Publication No.46-17046 JP-A-4-206681 Japanese Patent Laid-Open No. 5-25407 Japanese Patent Laid-Open No. 5-186888 Japanese Patent Laid-Open No. 7-243054

The present invention has been made in view of such circumstances, and the surface of copper or a copper alloy constituting a circuit portion or the like of a printed wiring board when an electronic component or the like is joined to the printed wiring board using solder. An object of the present invention is to provide a surface treatment agent and a surface treatment method that form a chemical conversion film having excellent heat resistance, improve wettability with solder, and improve solderability.
Also, a printed wiring board in which the surface treatment agent is brought into contact with the surface of copper or a copper alloy constituting the circuit part, and a lead-free solder is used after the surface of the copper or copper alloy is brought into contact with the surface treatment agent. An object of the present invention is to provide a soldering method for performing soldering.

As a result of intensive studies in order to solve the above-mentioned problems, the present inventors have developed a printed wiring board having a copper circuit portion with a surface treatment agent containing an imidazole compound represented by the chemical formula (I) of Chemical Formula 1 By performing the treatment, it is possible to form a chemical conversion film excellent in heat resistance on the surface of the copper circuit portion, that is, capable of withstanding the soldering temperature of lead-free solder, and when performing soldering using lead-free solder, Alternatively, the present invention has been completed by recognizing that good solderability can be obtained by improving the wettability of the solder to the surface of the copper alloy.
That is, the first invention is a surface treating agent for copper or copper alloy characterized by containing an imidazole compound represented by the chemical formula (I). 2nd invention is the surface treatment method of copper or copper alloy characterized by making the surface treating agent of 1st invention contact the surface of copper or copper alloy. 3rd invention is the printed wiring board characterized by making the surface treatment agent of 1st invention contact the surface of the copper or copper alloy of a copper circuit part. A fourth invention is a soldering method, wherein the surface of copper or a copper alloy is brought into contact with the surface treatment agent of the first invention, and then soldering is performed using lead-free solder.

（式中、Ｒは水素原子またはアルキル基を表し、Ｘ_１およびＸ_２は同一または異なって塩素原子もしくは臭素原子を表す。ｍおよびｎは０〜３の整数を表し、ｍまたはｎの少なくとも一方が１以上である。）

(In the formula, R represents a hydrogen atom or an alkyl group, and X ₁ and X ₂ are the same or different and represent a chlorine atom or a bromine atom. M and n represent an integer of 0 to 3, and at least one of m or n Is 1 or more.)

The surface treatment agent of the present invention can form a chemical conversion film having excellent heat resistance on the surface of copper or copper alloy constituting the circuit portion of the printed wiring board, etc., and also has the wettability of lead-free solder on the surface. It is possible to dramatically improve the solderability.
In addition, the soldering method of the present invention is useful from the viewpoint of environmental protection because it enables the use of solder that does not contain lead, which is a harmful metal.

Hereinafter, the present invention will be described in detail.
The imidazole compound used in the practice of the present invention is represented by the chemical formula (I) of Chemical Formula 2, and a benzyl group (hereinafter simply referred to as a benzyl group) is bonded to the 2-position of the imidazole ring. (5) An imidazole compound having a basic skeleton in which a phenyl group (hereinafter simply referred to as a phenyl group) is bonded to the position, and at least one of a benzyl ring or a phenyl group of a benzyl group, a chlorine atom and / or a bromine atom ( Hereinafter, it is an imidazole compound in which one or more substituted chlorine atoms and bromine atoms are sometimes referred to as halogen atoms.

（但し、式中のＲ、Ｘ_１、Ｘ_２、ｍおよびｎは、前記と同様である。）

(However, R, X ₁ , X ₂ , m and n in the formula are the same as described above.)

  As such imidazole compounds, (A) one in which only one of the benzyl group or the phenyl group is substituted with a halogen atom, and (B) one in which both the benzyl group and the phenyl group are substituted with one halogen atom (C) one in which only one of benzyl group or phenyl group is substituted with two or more halogen atoms, (D) one in which either benzyl group or phenyl group is substituted with two or more halogen atoms, and the other Can be classified into those in which one halogen atom is substituted, and (E) those in which two or more halogen atoms are substituted on both the benzyl group and the phenyl group.

  According to the knowledge obtained by the present inventors, a chemical conversion film is formed on the surface of copper or a copper alloy using the surface treatment agent containing the imidazole compounds (A) to (E), and lead-free solder is used. The solderability when soldering was performed was good in the order of (A) <(B) <(C) to (E). That is, using the surface treatment agent containing the imidazole compound of (B), compared with the solderability when the chemical conversion film is formed on the copper surface using the surface treatment agent containing the imidazole compound of (A). The solderability when the chemical film was formed on the copper surface was excellent. Similarly, the solderability of the imidazole compound (C) was superior to that of the imidazole compound (B). Moreover, when the chemical conversion film was formed on the copper surface using the surface treating agent containing (C), (D) and (E), almost the same solderability was obtained.

  According to the above findings, the imidazole compound suitable for the practice of the present invention has both m and n of 1 or more in the chemical formula (I) as compared with the case where at least one of m or n is 1 or more. It is preferable that at least one of m or n is 2 or more.

  R in the chemical formula (I) is a hydrogen atom or an alkyl group, and the alkyl group is a linear or branched saturated aliphatic group having 1 to 8 carbon atoms. Examples of such alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, etc. Is mentioned.

  The imidazole compound used in the practice of the present invention can be synthesized, for example, by employing the synthesis method shown in the reaction scheme of Chemical Formula 3. In addition, as a phenylacetamidine compound, a phenylacetamidine hydrochloride compound can be used conveniently.

（但し、式中のＲ、Ｘ_１、Ｘ_２、ｍおよびｎは前記と同様であり、Ｘ_３は塩素原子、臭素原子または沃素原子を表す。）

(However, R, X ₁ , X ₂ , m and n in the formula are the same as described above, and X ₃ represents a chlorine atom, a bromine atom or an iodine atom.)

As an imidazole compound represented by the chemical formula (I) used in the practice of the present invention, for example, when R is a hydrogen atom,
2-benzyl-4- (2-chlorophenyl) imidazole,
2-benzyl-4- (3-chlorophenyl) imidazole,
2-benzyl-4- (4-chlorophenyl) imidazole,
2-benzyl-4- (2-bromophenyl) imidazole,
2-benzyl-4- (3-bromophenyl) imidazole,
2-benzyl-4- (4-bromophenyl) imidazole,
2-benzyl-4- (2,3-dichlorophenyl) imidazole,
2-benzyl-4- (2,4-dichlorophenyl) imidazole,
2-benzyl-4- (2,5-dichlorophenyl) imidazole,
2-benzyl-4- (2,6-dichlorophenyl) imidazole,
2-benzyl-4- (3,4-dichlorophenyl) imidazole,
2-benzyl-4- (3,5-dichlorophenyl) imidazole,
2-benzyl-4- (2,4-dibromophenyl) imidazole,
2-benzyl-4- (2,5-dibromophenyl) imidazole,
2-benzyl-4- (2,4,5-trichlorophenyl) imidazole,
2-benzyl-4- (3,4,5-trichlorophenyl) imidazole,
2-benzyl-4- (2,4,5-tribromophenyl) imidazole,
2- (2-chlorobenzyl) -4-phenylimidazole,
2- (3-chlorobenzyl) -4-phenylimidazole,
2- (4-chlorobenzyl) -4-phenylimidazole,
2- (2-bromobenzyl) -4-phenylimidazole,
2- (3-bromobenzyl) -4-phenylimidazole,
2- (4-bromobenzyl) -4-phenylimidazole,
2- (2-chlorobenzyl) -4- (2-chlorophenyl) imidazole,
2- (2-chlorobenzyl) -4- (4-chlorophenyl) imidazole,
2- (4-chlorobenzyl) -4- (2-chlorophenyl) imidazole,
2- (4-chlorobenzyl) -4- (4-chlorophenyl) imidazole,
4- (4-bromophenyl) -2- (4-chlorobenzyl) imidazole,
2- (4-bromobenzyl) -4- (2-chlorophenyl) imidazole,
2- (4-bromobenzyl) -4- (4-chlorophenyl) imidazole,
2- (4-bromobenzyl) -4- (4-bromophenyl) imidazole,
2- (2-chlorobenzyl) -4- (2,3-dichlorophenyl) imidazole,
2- (2-chlorobenzyl) -4- (2,4-dichlorophenyl) imidazole,
2- (2-chlorobenzyl) -4- (2,5-dichlorophenyl) imidazole,
2- (2-chlorobenzyl) -4- (2,6-dichlorophenyl) imidazole,
2- (2-chlorobenzyl) -4- (3,4-dichlorophenyl) imidazole,
2- (2-chlorobenzyl) -4- (3,5-dichlorophenyl) imidazole,
2- (3-chlorobenzyl) -4- (2,4-dichlorophenyl) imidazole,
2- (3-chlorobenzyl) -4- (3,4-dichlorophenyl) imidazole,
2- (4-chlorobenzyl) -4- (2,3-dichlorophenyl) imidazole,
2- (4-chlorobenzyl) -4- (2,4-dichlorophenyl) imidazole,
2- (4-chlorobenzyl) -4- (2,5-dichlorophenyl) imidazole,
2- (4-chlorobenzyl) -4- (2,6-dichlorophenyl) imidazole,
2- (4-chlorobenzyl) -4- (3,4-dichlorophenyl) imidazole,
2- (4-chlorobenzyl) -4- (3,5-dichlorophenyl) imidazole,
2- (4-chlorobenzyl) -4- (2,4-dibromophenyl) imidazole,
2- (2-bromobenzyl) -4- (2,5-dichlorophenyl) imidazole,
2- (2-bromobenzyl) -4- (3,4-dichlorophenyl) imidazole,
2- (2-bromobenzyl) -4- (2,5-dibromophenyl) imidazole,
2- (2-chlorobenzyl) -4- (2,4,5-trichlorophenyl) imidazole,
2- (4-chlorobenzyl) -4- (2,4,5-tribromophenyl) imidazole,
2- (4-bromobenzyl) -4- (2,4,5-trichlorophenyl) imidazole,
2- (2-bromobenzyl) -4- (2,4,6-tribromophenyl) imidazole,
2- (2,3-dichlorobenzyl) -4-phenylimidazole,
2- (2,4-dichlorobenzyl) -4-phenylimidazole,
2- (2,5-dichlorobenzyl) -4-phenylimidazole,
2- (2,6-dichlorobenzyl) -4-phenylimidazole,
2- (3,4-dichlorobenzyl) -4-phenylimidazole,
2- (3,5-dichlorobenzyl) -4-phenylimidazole,
2- (2,4-dibromobenzyl) -4-phenylimidazole,
4- (2-chlorophenyl) -2- (2,3-dichlorobenzyl) imidazole,
4- (2-chlorophenyl) -2- (2,4-dichlorobenzyl) imidazole,
4- (2-chlorophenyl) -2- (2,5-dichlorobenzyl) imidazole,
4- (2-chlorophenyl) -2- (2,6-dichlorobenzyl) imidazole,
4- (2-chlorophenyl) -2- (3,4-dichlorobenzyl) imidazole,
4- (2-chlorophenyl) -2- (3,5-dichlorobenzyl) imidazole,
4- (3-chlorophenyl) -2- (2,4-dichlorobenzyl) imidazole,
4- (3-chlorophenyl) -2- (2,6-dichlorobenzyl) imidazole,
4- (3-chlorophenyl) -2- (3,4-dichlorobenzyl) imidazole,
4- (4-chlorophenyl) -2- (2,3-dichlorobenzyl) imidazole,
4- (4-chlorophenyl) -2- (2,4-dichlorobenzyl) imidazole,
4- (4-chlorophenyl) -2- (2,5-dichlorobenzyl) imidazole,
4- (4-chlorophenyl) -2- (2,6-dichlorobenzyl) imidazole,
4- (4-chlorophenyl) -2- (3,4-dichlorobenzyl) imidazole,
4- (4-chlorophenyl) -2- (3,5-dichlorobenzyl) imidazole,
4- (2-bromophenyl) -2- (2,4-dichlorobenzyl) imidazole,
4- (2-bromophenyl) -2- (3,4-dichlorobenzyl) imidazole,
4- (4-Chlorophenyl) -2- (2,5-dibromobenzyl) imidazole 4- (4-bromophenyl) -2- (2,5-dibromobenzyl) imidazole 2- (2,3-dichlorobenzyl)- 4- (2,3-dichlorophenyl) imidazole,
2- (2,4-dichlorobenzyl) -4- (2,3-dichlorophenyl) imidazole,
2- (2,5-dichlorobenzyl) -4- (2,3-dichlorophenyl) imidazole,
2- (2,6-dichlorobenzyl) -4- (2,3-dichlorophenyl) imidazole,
2- (3,4-dichlorobenzyl) -4- (2,3-dichlorophenyl) imidazole,
2- (3,5-dichlorobenzyl) -4- (2,3-dichlorophenyl) imidazole,
2- (2,3-dichlorobenzyl) -4- (2,4-dichlorophenyl) imidazole,
2- (2,4-dichlorobenzyl) -4- (2,4-dichlorophenyl) imidazole,
2- (2,5-dichlorobenzyl) -4- (2,4-dichlorophenyl) imidazole,
2- (2,6-dichlorobenzyl) -4- (2,4-dichlorophenyl) imidazole,
2- (3,4-dichlorobenzyl) -4- (2,4-dichlorophenyl) imidazole,
2- (3,5-dichlorobenzyl) -4- (2,4-dichlorophenyl) imidazole,
2- (2,3-dichlorobenzyl) -4- (2,5-dichlorophenyl) imidazole,
2- (2,4-dichlorobenzyl) -4- (2,5-dichlorophenyl) imidazole,
2- (2,5-dichlorobenzyl) -4- (2,5-dichlorophenyl) imidazole,
2- (2,6-dichlorobenzyl) -4- (2,5-dichlorophenyl) imidazole,
2- (3,4-dichlorobenzyl) -4- (2,5-dichlorophenyl) imidazole,
2- (3,5-dichlorobenzyl) -4- (2,5-dichlorophenyl) imidazole,
2- (2,3-dichlorobenzyl) -4- (2,6-dichlorophenyl) imidazole,
2- (2,4-dichlorobenzyl) -4- (2,6-dichlorophenyl) imidazole,
2- (2,5-dichlorobenzyl) -4- (2,6-dichlorophenyl) imidazole,
2- (2,6-dichlorobenzyl) -4- (2,6-dichlorophenyl) imidazole,
2- (3,4-dichlorobenzyl) -4- (2,6-dichlorophenyl) imidazole,
2- (3,5-dichlorobenzyl) -4- (2,6-dichlorophenyl) imidazole,
2- (2,3-dichlorobenzyl) -4- (3,4-dichlorophenyl) imidazole,
2- (2,4-dichlorobenzyl) -4- (3,4-dichlorophenyl) imidazole,
2- (2,5-dichlorobenzyl) -4- (3,4-dichlorophenyl) imidazole,
2- (2,6-dichlorobenzyl) -4- (3,4-dichlorophenyl) imidazole,
2- (3,4-dichlorobenzyl) -4- (3,4-dichlorophenyl) imidazole,
2- (3,5-dichlorobenzyl) -4- (3,4-dichlorophenyl) imidazole,
2- (2,3-dichlorobenzyl) -4- (3,5-dichlorophenyl) imidazole,
2- (2,4-dichlorobenzyl) -4- (3,5-dichlorophenyl) imidazole,
2- (2,5-dichlorobenzyl) -4- (3,5-dichlorophenyl) imidazole,
2- (2,6-dichlorobenzyl) -4- (3,5-dichlorophenyl) imidazole,
2- (3,4-dichlorobenzyl) -4- (3,5-dichlorophenyl) imidazole,
2- (3,5-dichlorobenzyl) -4- (3,5-dichlorophenyl) imidazole,
4- (2,5-dibromophenyl) -2- (2,4-dichlorobenzyl) imidazole,
4- (2,5-dibromophenyl) -2- (3,4-dichlorobenzyl) imidazole,
2- (2,5-dibromobenzyl) -4- (3,4-dichlorophenyl) imidazole,
2- (2,4-dibromobenzyl) -4- (3,4-dibromophenyl) imidazole,
2- (2,4-dichlorobenzyl) -4- (3,4,5-trichlorophenyl) imidazole,
2- (2,4-dichlorobenzyl) -4- (2,4,6-tribromophenyl) imidazole,
2- (2,4-dibromobenzyl) -4- (3,4,5-trichlorophenyl) imidazole,
2- (2,4-dibromobenzyl) -4- (2,4,5-tribromophenyl) imidazole,
4-phenyl-2- (3,4,5-trichlorobenzyl) imidazole,
4-phenyl-2- (2,4,5-tribromobenzyl) imidazole,
4- (4-chlorophenyl) -2- (2,3,6-trichlorobenzyl) imidazole,
4- (2-bromophenyl) -2- (3,4,5-trichlorobenzyl) imidazole,
4- (4-chlorophenyl) -2- (2,3,5-tribromobenzyl) imidazole,
4- (4-bromophenyl) -2- (2,4,6-tribromobenzyl) imidazole,
4- (2,4-dichlorophenyl) -2- (3,4,5-trichlorobenzyl) imidazole,
4- (2,4-dibromophenyl) -2- (3,4,5-trichlorobenzyl) imidazole,
4- (3,4-dichlorophenyl) -2- (2,4,5-tribromobenzyl) imidazole,
4- (2,5-dibromophenyl) -2- (2,3,5-tribromobenzyl) imidazole,
2- (3,4,5-trichlorobenzyl) -4- (2,4,5-trichlorophenyl) imidazole,
4- (2,4,5-tribromophenyl) -2- (3,4,5-trichlorobenzyl) imidazole,
2- (2,4,6-tribromobenzyl) -4- (2,4,5-trichlorophenyl) imidazole,
2- (2,4,6-tribromobenzyl) -4- (2,4,6-tribromophenyl) imidazole and the like.

Similarly, for example, when R is a methyl group,
2-benzyl-4- (2-chlorophenyl) -5-methylimidazole,
2-benzyl-4- (3-chlorophenyl) -5-methylimidazole,
2-benzyl-4- (4-chlorophenyl) -5-methylimidazole,
2-benzyl-4- (2-bromophenyl) -5-methylimidazole,
2-benzyl-4- (3-bromophenyl) -5-methylimidazole,
2-benzyl-4- (4-bromophenyl) -5-methylimidazole,
2-benzyl-4- (2,3-dichlorophenyl) -5-methylimidazole,
2-benzyl-4- (2,4-dichlorophenyl) -5-methylimidazole,
2-benzyl-4- (2,5-dichlorophenyl) -5-methylimidazole,
2-benzyl-4- (2,6-dichlorophenyl) -5-methylimidazole,
2-benzyl-4- (3,4-dichlorophenyl) -5-methylimidazole,
2-benzyl-4- (3,5-dichlorophenyl) -5-methylimidazole,
2-benzyl-4- (2,4-dibromophenyl) -5-methylimidazole,
2-benzyl-4- (2,5-dibromophenyl) -5-methylimidazole,
2-benzyl-5-methyl-4- (2,4,5-trichlorophenyl) imidazole,
2-benzyl-5-methyl-4- (3,4,5-trichlorophenyl) imidazole,
2-benzyl-5-methyl-4- (2,4,5-tribromophenyl) imidazole,
2- (2-chlorobenzyl) -5-methyl-4-phenylimidazole,
2- (3-chlorobenzyl) -5-methyl-4-phenylimidazole,
2- (4-chlorobenzyl) -5-methyl-4-phenylimidazole,
2- (2-bromobenzyl) -5-methyl-4-phenylimidazole,
2- (3-bromobenzyl) -5-methyl-4-phenylimidazole,
2- (4-bromobenzyl) -5-methyl-4-phenylimidazole,
2- (2-chlorobenzyl) -4- (2-chlorophenyl) -5-methylimidazole,
2- (2-chlorobenzyl) -4- (4-chlorophenyl) -5-methylimidazole,
2- (4-chlorobenzyl) -4- (2-chlorophenyl) -5-methylimidazole,
2- (4-chlorobenzyl) -4- (4-chlorophenyl) -5-methylimidazole,
4- (4-bromophenyl) -2- (2-chlorobenzyl) -5-methylimidazole,
2- (4-bromobenzyl) -4- (2-chlorophenyl) -5-methylimidazole,
2- (4-bromobenzyl) -4- (4-chlorophenyl) -5-methylimidazole,
2- (4-bromobenzyl) -4- (4-bromophenyl) -5-methylimidazole,
2- (2-chlorobenzyl) -4- (2,3-dichlorophenyl) -5-methylimidazole,
2- (2-chlorobenzyl) -4- (2,4-dichlorophenyl) -5-methylimidazole,
2- (2-chlorobenzyl) -4- (2,5-dichlorophenyl) -5-methylimidazole,
2- (2-chlorobenzyl) -4- (2,6-dichlorophenyl) -5-methylimidazole,
2- (2-chlorobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole,
2- (2-chlorobenzyl) -4- (3,5-dichlorophenyl) -5-methylimidazole,
2- (3-chlorobenzyl) -4- (2,4-dichlorophenyl) -5-methylimidazole,
2- (3-chlorobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole,
2- (4-chlorobenzyl) -4- (2,3-dichlorophenyl) -5-methylimidazole,
2- (4-chlorobenzyl) -4- (2,4-dichlorophenyl) -5-methylimidazole,
2- (4-chlorobenzyl) -4- (2,5-dichlorophenyl) -5-methylimidazole,
2- (4-chlorobenzyl) -4- (2,6-dichlorophenyl) -5-methylimidazole,
2- (4-chlorobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole,
2- (4-chlorobenzyl) -4- (3,5-dichlorophenyl) -5-methylimidazole,
2- (4-chlorobenzyl) -4- (2,4-dibromophenyl) -5-methylimidazole,
2- (4-bromobenzyl) -4- (2,4-dichlorophenyl) -5-methylimidazole,
2- (4-bromobenzyl) -4- (2,5-dichlorophenyl) -5-methylimidazole,
2- (4-bromobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole,
2- (4-bromobenzyl) -4- (2,5-dibromophenyl) -5-methylimidazole,
2- (2-chlorobenzyl) -5-methyl-4- (2,4,5-trichlorophenyl) imidazole,
2- (4-chlorobenzyl) -5-methyl-4- (2,4,5-tribromophenyl) imidazole,
2- (4-bromobenzyl) -5-methyl-4- (2,4,5-trichlorophenyl) imidazole,
2- (2-bromobenzyl) -5-methyl-4- (2,4,6-tribromophenyl) imidazole,
2- (2,3-dichlorobenzyl) -5-methyl-4-phenylimidazole,
2- (2,4-dichlorobenzyl) -5-methyl-4-phenylimidazole,
2- (2,5-dichlorobenzyl) -5-methyl-4-phenylimidazole,
2- (2,6-dichlorobenzyl) -5-methyl-4-phenylimidazole,
2- (3,4-dichlorobenzyl) -5-methyl-4-phenylimidazole,
2- (3,5-dichlorobenzyl) -5-methyl-4-phenylimidazole,
2- (2,4-dibromobenzyl) -5-methyl-4-phenylimidazole,
4- (2-chlorophenyl) -2- (2,3-dichlorobenzyl) -5-methylimidazole,
4- (2-chlorophenyl) -2- (2,4-dichlorobenzyl) -5-methylimidazole,
4- (2-chlorophenyl) -2- (2,5-dichlorobenzyl) -5-methylimidazole,
4- (2-chlorophenyl) -2- (2,6-dichlorobenzyl) -5-methylimidazole,
4- (2-chlorophenyl) -2- (3,4-dichlorobenzyl) -5-methylimidazole,
4- (2-chlorophenyl) -2- (3,5-dichlorobenzyl) -5-methylimidazole,
4- (3-chlorophenyl) -2- (2,4-dichlorobenzyl) -5-methylimidazole,
4- (3-chlorophenyl) -2- (2,6-dichlorobenzyl) -5-methylimidazole,
4- (3-chlorophenyl) -2- (3,4-dichlorobenzyl) -5-methylimidazole,
4- (4-chlorophenyl) -2- (2,3-dichlorobenzyl) -5-methylimidazole,
4- (4-chlorophenyl) -2- (2,4-dichlorobenzyl) -5-methylimidazole,
4- (4-chlorophenyl) -2- (2,5-dichlorobenzyl) -5-methylimidazole,
4- (4-chlorophenyl) -2- (2,6-dichlorobenzyl) -5-methylimidazole,
4- (4-chlorophenyl) -2- (3,4-dichlorobenzyl) -5-methylimidazole,
4- (4-chlorophenyl) -2- (3,5-dichlorobenzyl) -5-methylimidazole,
4- (2-bromophenyl) -2- (2,4-dichlorobenzyl) -5-methylimidazole,
4- (4-bromophenyl) -2- (3,4-dichlorobenzyl) -5-methylimidazole,
4- (4-chlorophenyl) -2- (2,5-dibromobenzyl) -5-methylimidazole,
4- (4-bromophenyl) -2- (2,5-dibromobenzyl) -5-methylimidazole,
2- (2,3-dichlorobenzyl) -4- (2,3-dichlorophenyl) -5-methylimidazole,
2- (2,4-dichlorobenzyl) -4- (2,3-dichlorophenyl) -5-methylimidazole,
2- (2,5-dichlorobenzyl) -4- (2,3-dichlorophenyl) -5-methylimidazole,
2- (2,6-dichlorobenzyl) -4- (2,3-dichlorophenyl) -5-methylimidazole,
2- (3,4-dichlorobenzyl) -4- (2,3-dichlorophenyl) -5-methylimidazole,
2- (3,5-dichlorobenzyl) -4- (2,3-dichlorophenyl) -5-methylimidazole,
2- (2,3-dichlorobenzyl) -4- (2,4-dichlorophenyl) -5-methylimidazole,
2- (2,4-dichlorobenzyl) -4- (2,4-dichlorophenyl) -5-methylimidazole,
2- (2,5-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- (3,5-dichlorobenzyl) -4- (2,4-dichlorophenyl) -5-methylimidazole,
2- (2,3-dichlorobenzyl) -4- (2,5-dichlorophenyl) -5-methylimidazole,
2- (2,4-dichlorobenzyl) -4- (2,5-dichlorophenyl) -5-methylimidazole,
2- (2,5-dichlorobenzyl) -4- (2,5-dichlorophenyl) -5-methylimidazole,
2- (2,6-dichlorobenzyl) -4- (2,5-dichlorophenyl) -5-methylimidazole,
2- (3,4-dichlorobenzyl) -4- (2,5-dichlorophenyl) -5-methylimidazole,
2- (3,5-dichlorobenzyl) -4- (2,5-dichlorophenyl) -5-methylimidazole,
2- (2,3-dichlorobenzyl) -4- (2,6-dichlorophenyl) -5-methylimidazole,
2- (2,4-dichlorobenzyl) -4- (2,6-dichlorophenyl) -5-methylimidazole,
2- (2,5-dichlorobenzyl) -4- (2,6-dichlorophenyl) -5-methylimidazole,
2- (2,6-dichlorobenzyl) -4- (2,6-dichlorophenyl) -5-methylimidazole,
2- (3,4-dichlorobenzyl) -4- (2,6-dichlorophenyl) -5-methylimidazole,
2- (3,5-dichlorobenzyl) -4- (2,6-dichlorophenyl) -5-methylimidazole,
2- (2,3-dichlorobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole,
2- (2,4-dichlorobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole,
2- (2,5-dichlorobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole,
2- (2,6-dichlorobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole,
2- (3,4-dichlorobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole,
2- (3,5-dichlorobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole,
2- (2,3-dichlorobenzyl) -4- (3,5-dichlorophenyl) -5-methylimidazole,
2- (2,4-dichlorobenzyl) -4- (3,5-dichlorophenyl) -5-methylimidazole,
2- (2,5-dichlorobenzyl) -4- (3,5-dichlorophenyl) -5-methylimidazole,
2- (2,6-dichlorobenzyl) -4- (3,5-dichlorophenyl) -5-methylimidazole,
2- (3,4-dichlorobenzyl) -4- (3,5-dichlorophenyl) -5-methylimidazole,
2- (3,5-dichlorobenzyl) -4- (3,5-dichlorophenyl) -5-methylimidazole,
4- (2,5-dibromophenyl) -2- (2,4-dichlorobenzyl) -5-methylimidazole,
4- (2,5-dibromophenyl) -2- (3,4-dichlorobenzyl) -5-methylimidazole,
2- (2,5-dibromobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole,
2- (2,4-dibromobenzyl) -4- (3,4-dibromophenyl) -5-methylimidazole,
2- (2,4-dichlorobenzyl) -5-methyl-4- (3,4,5-trichlorophenyl) imidazole,
2- (3,4-dichlorobenzyl) -5-methyl-4- (2,4,6-tribromophenyl) imidazole,
2- (2,4-dibromobenzyl) -5-methyl-4- (3,4,5-trichlorophenyl) imidazole,
2- (2,4-dibromobenzyl) -5-methyl-4- (2,4,5-tribromophenyl) imidazole,
5-methyl-4-phenyl-2- (3,4,5-trichlorobenzyl) imidazole,
5-methyl-4-phenyl-2- (2,4,5-tribromobenzyl) imidazole,
4- (4-chlorophenyl) -5-methyl-2- (2,3,6-trichlorobenzyl) imidazole,
4- (4-bromophenyl) -5-methyl-2- (3,4,5-trichlorobenzyl) imidazole,
4- (4-chlorophenyl) -5-methyl-2- (2,3,5-tribromobenzyl) imidazole,
4- (4-bromophenyl) -5-methyl-2- (2,4,6-tribromobenzyl) imidazole,
4- (2,4-dichlorophenyl) -5-methyl-2- (3,4,5-trichlorobenzyl) imidazole,
4- (2,4-dibromophenyl) -5-methyl-2- (3,4,5-trichlorobenzyl) imidazole,
4- (3,4-dichlorophenyl) -5-methyl-2- (2,4,5-tribromobenzyl) imidazole,
4- (2,5-dibromophenyl) -5-methyl-2- (2,3,5-tribromobenzyl) imidazole,
5-methyl-2- (3,4,5-trichlorobenzyl) -4- (2,4,5-trichlorophenyl) imidazole,
5-methyl-4- (2,4,5-tribromophenyl) -2- (3,4,5-trichlorobenzyl) imidazole,
5-methyl-2- (2,4,6-tribromobenzyl) -4- (2,4,5-trichlorophenyl) imidazole,
And 5-methyl-2- (2,4,6-tribromobenzyl) -4- (2,4,6-tribromophenyl) imidazole.

These imidazole compounds are used as an active ingredient of a surface treatment agent prepared by dissolving in water. These imidazole compounds are contained in the surface treatment agent in a proportion of 0.01 to 10% by weight, preferably in a proportion of 0.1 to 5% by weight. When the content ratio of the imidazole compound is less than 0.01% by weight, the film thickness of the chemical conversion film formed on the copper surface becomes thin, and oxidation of the copper surface cannot be sufficiently prevented. On the other hand, when the amount is more than 10% by weight, the imidazole compound remains undissolved in the surface treatment agent or may be re-precipitated even if it is completely dissolved.
In the practice of the present invention, among the imidazole compounds represented by the chemical formula (I), only one appropriate type may be used, or different types of imidazole compounds may be used in combination.

  In the practice of the present invention, an organic acid or an inorganic acid is generally used as an acid for dissolving (making an aqueous solution) an imidazole compound in water, but a small amount of an organic solvent may be used in combination. Typical organic acids used in this case include formic acid, acetic acid, propionic acid, butyric acid, glyoxylic acid, pyruvic acid, acetoacetic acid, levulinic acid, heptanoic acid, caprylic acid, capric acid, lauric acid, glycolic acid, Glyceric acid, lactic acid, acrylic acid, methoxyacetic acid, ethoxyacetic acid, propoxyacetic acid, butoxyacetic acid, 2- (2-methoxyethoxy) acetic acid, 2- [2- (2-ethoxyethoxy) ethoxy] acetic acid, 2- {2- [2- (2-Ethoxyethoxy) ethoxy] ethoxy} acetic acid, 3-methoxypropionic acid, 3-ethoxypropionic acid, 3-propoxypropionic acid, 3-butoxypropionic acid, benzoic acid, paranitrobenzoic acid, paratoluenesulfonic acid , Salicylic acid, picric acid, succinic acid, succinic acid, maleic acid, fumaric acid, tartaric acid, adipic acid Acid, and examples of the inorganic acids, hydrochloric acid, phosphoric acid, sulfuric acid, and nitric acid. These acids are contained in the surface treatment agent in a proportion of 0.1 to 50% by weight, preferably 1 to 30% by weight.

  As the organic solvent, those which are freely miscible with water such as lower alcohols such as methanol, ethanol and isopropyl alcohol or water such as acetone, N, N-dimethylformamide and ethylene glycol are suitable.

A copper compound can be added to the surface treatment agent of the present invention in order to increase the formation rate of the chemical conversion film on the surface of copper or copper alloy, and zinc can be added to further improve the heat resistance of the formed chemical conversion film. A compound may be added.
Representative examples of the copper compound include copper acetate, cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, copper iodide, copper hydroxide, copper phosphate, copper sulfate. Typical examples of the zinc compound include zinc oxide, zinc formate, zinc acetate, zinc oxalate, zinc lactate, zinc citrate, zinc sulfate, zinc nitrate, zinc phosphate and the like. In any case, the surface treatment agent may contain 0.01 to 10% by weight, preferably 0.02 to 5% by weight.

  When these copper compounds and zinc compounds are used, in addition to organic or inorganic acids, substances having a buffering action such as ammonia or amines such as monoethanolamine, diethanolamine and triethanolamine are added to the solution. It is preferable to stabilize the pH.

  In the surface treatment agent of the present invention, a halogen compound is added in an amount of 0.001 to 1% by weight, preferably 0.01 to 0% in the surface treatment agent in order to further improve the formation rate of the chemical conversion film and the heat resistance of the film. .1% by weight can be added. Examples of the halogen compound include sodium fluoride, potassium fluoride, ammonium fluoride, sodium chloride, potassium chloride, ammonium chloride, sodium bromide, potassium bromide, ammonium bromide, sodium iodide, potassium iodide, and ammonium iodide. Etc.

  As conditions for treating the surface of copper or a copper alloy using the surface treatment agent of the present invention, it is preferable that the liquid temperature of the surface treatment agent is 10 to 70 ° C. and the contact time is 1 second to 10 minutes. Examples of the contact method include dipping, spraying, and application methods.

Moreover, after performing the surface treatment of this invention, it is also possible to form a double structure with a thermoplastic resin on a chemical conversion film, and to further improve heat resistance.
That is, after forming a chemical conversion film on the surface of copper or copper alloy, rosin derivatives such as rosin and rosin ester, terpene resin derivatives such as terpene resin and terpene phenol resin, aromatic hydrocarbon resin and aliphatic hydrocarbon resin A thermoplastic resin excellent in heat resistance composed of a hydrocarbon resin such as the above or a mixture thereof is dissolved in a solvent such as toluene, ethyl acetate, isopropyl alcohol, and the thickness of 1 to 30 μm on the chemical conversion film by a roll coater or the like. It is sufficient to apply uniformly to form a double structure of the chemical conversion film and the thermoplastic resin.

  Lead-free solders suitable for the practice of the present invention include Sn—Ag—Cu, Sn—Ag—Bi, Sn—Bi, Sn—Ag—Bi—In, Sn—Zn, Sn—Cu, etc. Lead-free solder is mentioned.

  In addition, the soldering method of the present invention is a flow method in which a printed wiring board is flowed over a solder bath containing heated and melted liquid solder, and soldering is performed on the joint between the electronic component and the printed wiring board, or It can be applied to the reflow method, etc., in which paste-like cream solder is printed on the printed wiring board according to the circuit pattern in advance, electronic components are mounted on the printed wiring board, the printed wiring board is heated to melt the solder, and soldering is performed. Is.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to these.
In addition, the imidazole compound used in the Example and the comparative example and the evaluation test method are as follows.

[Imidazole compound]
The imidazole compounds used in the examples are as follows, and synthesis examples are shown in Reference Examples 2 to 20. Reference Example 1 shows a synthesis example of (4-chlorophenyl) acetamidine hydrochloride, which is a raw material for the imidazole compound of Reference Example 2.

2- (4-chlorobenzyl) -4-phenylimidazole (abbreviated as “A-1”)
2-Benzyl-4- (4-chlorophenyl) -5-methylimidazole (abbreviated as “A-2”)
2- (2-chlorobenzyl) -5-methyl-4-phenylimidazole (abbreviated as “A-3”)
2- (2-chlorobenzyl) -4- (4-chlorophenyl) -5-methylimidazole (abbreviated as “B-1”)
2- (4-chlorobenzyl) -4- (2-chlorophenyl) -5-methylimidazole (abbreviated as “B-2”)
2- (4-chlorobenzyl) -4- (4-chlorophenyl) -5-methylimidazole (abbreviated as “B-3”)
2- (2,4-dichlorobenzyl) -4-phenylimidazole (abbreviated as “C-1”)
2-Benzyl-4- (2,4-dichlorophenyl) -5-methylimidazole (abbreviated as “C-2”)
5-hexyl-4-phenyl-2- (3,4,5-trichlorobenzyl) imidazole (abbreviated as “C-3”)
4- (4-chlorophenyl) -2- (2,4-dichlorobenzyl) -5-methylimidazole (abbreviated as “D-1”)
4- (4-Bromophenyl) -2- (2,4-dichlorobenzyl) -5-methylimidazole (abbreviated as “D-2”)
2- (2-chlorobenzyl) -4- (2,4-dichlorophenyl) imidazole (abbreviated as “D-3”)
2- (4-Chlorobenzyl) -4- (2,4-dichlorophenyl) imidazole (abbreviated as “D-4”)
2- (4-bromobenzyl) -4- (2,4-dichlorophenyl) -5-methylimidazole (abbreviated as “D-5”)
2- (4-bromobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole (abbreviated as “D-6”)
2- (4-chlorobenzyl) -5-methyl-4- (3,4,5-trichlorophenyl) imidazole (abbreviated as “D-7”)
2- (2,4-dichlorobenzyl) -4- (2,4-dichlorophenyl) -5-methylimidazole (abbreviated as “E-1”)
2- (2,4-dichlorobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole (abbreviated as “E-2”)
2- (3,4-dichlorobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole (abbreviated as “E-3”)

  As described above, the symbols A to E are (A) an imidazole compound in which one of the benzyl group and the phenyl group is substituted with one halogen atom, and (B) a halogen atom in both the benzyl group and the phenyl group. One substituted imidazole compound, (C) an imidazole compound in which only one of the benzyl group and the phenyl group is substituted with two or more halogen atoms, and (D) two halogen atoms in either the benzyl group or the phenyl group It represents that it is an imidazole compound substituted with one or more halogen atoms and (E) an imidazole compound substituted with two or more halogen atoms on both the benzyl group and the phenyl group.

[Reference Example 1]
<Synthesis of (4-chlorophenyl) acetamidine hydrochloride>
To a solution consisting of 137.2 g (0.905 mol) of (4-chlorophenyl) acetonitrile and 51.1 g (1.11 mol) of dehydrated ethanol, 36.7 g (1.01 mol) of hydrogen chloride gas at 15 to 20 ° C. under cooling. Was blown in over 2 hours. A solid formed during the blowing. The reaction mixture was left at room temperature overnight to give ethyl (4-chlorophenyl) acetimidate as a white solid. After crushing the solid, a solution consisting of 28.4 g (1.67 mol) of ammonia and 250 g of dehydrated ethanol was added little by little while shaking under ice cooling. After the addition was completed, the mixture was returned to room temperature for 1 hour under ice-cooling and stirred overnight. After filtering off the white solid insoluble matter, the filtrate was evaporated to dryness under reduced pressure to give (4-chlorophenyl) acetamidine as white crystals. 178 g (0.868 mol, yield 96%) of hydrochloride was obtained.

[Reference Example 2]
<Synthesis of A-1>
16.2 g (0.30 mol) of sodium methylate was added to a solution consisting of 61.5 g (0.30 mol) of (4-chlorophenyl) acetamidine hydrochloride and 250 ml of tetrahydrofuran, heated at 50 ° C. for 1 hour, and then carbonated. 83 g (0.60 mol) of potassium was added, and a solution consisting of 59.7 g (0.30 mol) of 2-bromoacetophenone and 200 ml of tetrahydrofuran was added dropwise to the suspension at 50 to 55 ° C. After completion of the dropwise addition, the mixture was heated to reflux for 2 hours. Next, the reaction solution was cooled to room temperature, insolubles were removed by filtration, the filtrate was concentrated under reduced pressure, and the concentrate was washed with water and then stirred with toluene to precipitate crystals. The crystals collected by filtration were decolorized with activated carbon in methanol and recrystallized to obtain 25 g (0.093 mol, 31% yield) of 2- (4-chlorobenzyl) -4-phenylimidazole as slightly pink crystals. .

[Reference Example 3]
<Synthesis of A-2>
First, phenylacetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with phenylacetonitrile.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with phenylacetamidine hydrochloride and 2-bromoacetophenone was replaced with 2-bromo-4′-chloropropiophenone, and conforming to the method of Reference Example 2 Thus, 2-benzyl-4- (4-chlorophenyl) -5-methylimidazole was synthesized.

[Reference Example 4]
<Synthesis of A-3>
First, (2-chlorophenyl) acetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with (2-chlorophenyl) acetonitrile.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with (2-chlorophenyl) acetamidine hydrochloride and 2-bromoacetophenone was replaced with 2-bromopropiophenone, and the method of Reference Example 2 was followed. 2- (2-chlorobenzyl) -5-methyl-4-phenylimidazole was synthesized.

[Reference Example 5]
<Synthesis of B-1>
First, (2-chlorophenyl) acetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with (2-chlorophenyl) acetonitrile.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with (2-chlorophenyl) acetamidine hydrochloride and 2-bromoacetophenone was replaced with 2-bromo-4′-chloropropiophenone, Reference Example 2 2- (2-Chlorobenzyl) -4- (4-chlorophenyl) -5-methylimidazole was synthesized according to the above method.

[Reference Example 6]
<Synthesis of B-2>
Instead of 2-bromoacetophenone in Reference Example 2 with 2-bromo-2′-chloropropiophenone, 2- (4-chlorobenzyl) -4- (2-chlorophenyl)- 5-methylimidazole was synthesized.

[Reference Example 7]
<Synthesis of B-3>
Instead of 2-bromoacetophenone in Reference Example 2 with 2-bromo-4′-chloropropiophenone, 2- (4-chlorobenzyl) -4- (4-chlorophenyl)- 5-methylimidazole was synthesized.

[Reference Example 8]
<Synthesis of C-1>
First, (2,4-dichlorophenyl) acetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with (2,4-dichlorophenyl) acetonitrile.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with (2,4-dichlorophenyl) acetamidine hydrochloride, and 2- (2,4-dichlorobenzyl) was used according to the method of Reference Example 2. -4-Phenylimidazole was synthesized.

[Reference Example 9]
<Synthesis of C-2>
First, phenylacetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with phenylacetonitrile.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with phenylacetamidine hydrochloride and 2-bromoacetophenone was replaced with 2-bromo-2 ′, 4′-dichloropropiophenone. According to the method, 2-benzyl-4- (2,4-dichlorophenyl) -5-methylimidazole was synthesized.

[Reference Example 10]
<Synthesis of C-3>
First, (3,4,5-trichlorophenyl) acetamidine hydrochloride is used in accordance with the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with (3,4,5-trichlorophenyl) acetonitrile. A salt was synthesized.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with (3,4,5-trichlorophenyl) acetamidine hydrochloride and 2-bromoacetophenone was replaced with 2-bromooctanophenone, Reference Example 2 According to the method of 5-hexyl-4-phenyl-2- (3,4,5-trichlorobenzyl) imidazole was synthesized.

[Reference Example 11]
<Synthesis of D-1>
First, (2,4-dichlorophenyl) acetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with (2,4-dichlorophenyl) acetonitrile.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with (2,4-dichlorophenyl) acetamidine hydrochloride, and 2-bromoacetophenone was replaced with 2-bromo-4′-chloropropiophenone. According to the method of Example 2, 4- (4-chlorophenyl) -2- (2,4-dichlorobenzyl) -5-methylimidazole was synthesized.

[Reference Example 12]
<Synthesis of D-2>
First, (2,4-dichlorophenyl) acetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with (2,4-dichlorophenyl) acetonitrile.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with (2,4-dichlorophenyl) acetamidine hydrochloride and 2-bromoacetophenone was replaced with 2,4′-dibromopropiophenone, Reference Example 2 According to the method of 4- (4-bromophenyl) -2- (2,4-dichlorobenzyl) -5-methylimidazole was synthesized.

[Reference Example 13]
<Synthesis of D-3>
First, (2-chlorophenyl) acetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with (2-chlorophenyl) acetonitrile.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with (2-chlorophenyl) acetamidine hydrochloride and 2-bromoacetophenone was replaced with 2-bromo-2 ′, 4′-dichloroacetophenone, Reference Example According to the method of 2, 2- (2-chlorobenzyl) -4- (2,4-dichlorophenyl) imidazole was synthesized.

[Reference Example 14]
<Synthesis of D-4>
The 2-bromoacetophenone of Reference Example 2 was replaced with 2-bromo-2 ′, 4′-dichloroacetophenone, and 2- (4-chlorobenzyl) -4- (2,4- Dichlorophenyl) imidazole was synthesized.

[Reference Example 15]
<Synthesis of D-5>
First, (4-bromophenyl) acetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with (4-bromophenyl) acetonitrile.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with (4-bromophenyl) acetamidine hydrochloride, and 2-bromoacetophenone was replaced with 2-bromo-2 ′, 4′-dichloropropiophenone. According to the method of Reference Example 2, 2- (4-bromobenzyl) -4- (2,4-dichlorophenyl) -5-methylimidazole was synthesized.

[Reference Example 16]
<Synthesis of D-6>
First, (4-bromophenyl) acetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with (4-bromophenyl) acetonitrile.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with (4-bromophenyl) acetamidine hydrochloride, and 2-bromoacetophenone was replaced with 2-bromo-3 ′, 4′-dichloropropiophenone. According to the method of Reference Example 2, 2- (4-bromobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole was synthesized.

[Reference Example 17]
<Synthesis of D-7>
In place of 2-bromoacetophenone in Reference Example 2 instead of 2-bromo-3 ′, 4 ′, 5′-trichloropropiophenone, 2- (4-chlorobenzyl) -5-5- Methyl-4- (3,4,5-trichlorophenyl) imidazole was synthesized.

[Reference Example 18]
<Synthesis of E-1>
First, (2,4-dichlorophenyl) acetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with (2,4-dichlorophenyl) acetonitrile.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with (2,4-dichlorophenyl) acetamidine hydrochloride, and 2-bromoacetophenone was replaced with 2-bromo-2 ′, 4′-dichloropropiophenone. Then, 2- (2,4-dichlorobenzyl) -4- (2,4-dichlorophenyl) -5-methylimidazole was synthesized according to the method of Reference Example 2.

[Reference Example 19]
<Synthesis of E-2>
First, (2,4-dichlorophenyl) acetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with (2,4-dichlorophenyl) acetonitrile.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with (2,4-dichlorophenyl) acetamidine hydrochloride, and 2-bromoacetophenone was replaced with 2-bromo-3 ′, 4′-dichloropropiophenone. According to the method of Reference Example 2, 2- (2,4-dichlorobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole was synthesized.

[Reference Example 20]
<Synthesis of E-3>
First, (3,4-dichlorophenyl) acetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with (3,4-dichlorophenyl) acetonitrile.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with (3,4-dichlorophenyl) acetamidine hydrochloride, and 2-bromoacetophenone was replaced with 2-bromo-3 ′, 4′-dichloropropiophenone. Then, 2- (3,4-dichlorobenzyl) -4- (3,4-dichlorophenyl) -5-methylimidazole was synthesized according to the method of Reference Example 2.

The imidazole compounds used in the comparative examples are as follows.
2-Benzyl-4-phenylimidazole (abbreviated as “Z-1”)
2-Benzyl-5-chloro-4-methylimidazole (abbreviated as “Z-2”)
2- (4-Chlorobenzyl) imidazole (abbreviated as “Z-3”)
2- (2,4-dichlorobenzyl) -4,5-diphenylimidazole (abbreviated as “Z-4”)
4-methyl-2-phenylimidazole (abbreviated as “Z-5”)
2- (4-Chlorobenzyl) benzimidazole (abbreviated as “Z-6”)

  Reference examples 21 to 24 show synthesis examples of Z-1, Z-2, Z-3, and Z-4. For Z-5 and Z-6, trade names “CUREZOL 2P4MZ” manufactured by Shikoku Kasei Kogyo Co., Ltd. and reagents manufactured by Wako Pure Chemical Industries, Ltd. were used.

[Reference Example 21]
<Synthesis of Z-1>
First, phenylacetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with phenylacetonitrile.
Subsequently, 2-benzyl-4-phenylimidazole was synthesized according to the method of Reference Example 2 by replacing (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 with phenylacetamidine hydrochloride.

[Reference Example 22]
<Synthesis of Z-2>
To a solution consisting of 16 g (0.093 mol) of 2-benzyl-4-methylimidazole (POLY ORGANIX, “2B4MI”) and 100 ml of ethanol, 13.3 g (0.1 mol) of N-chlorosuccinimide was gradually added at room temperature. In addition, after stirring for 1 hour, the reaction solution was dried under reduced pressure, and the dried product was washed with hot water and then recrystallized from acetonitrile to give 2-benzyl-5-chloro as needle crystals with a light beige color. 8.5 g (0.041 mol, yield 44%) of -4-methylimidazole was obtained.

[Reference Example 23]
<Synthesis of Z-3>
A solution consisting of 52.0 g (0.343 mol) of (4-chlorophenyl) acetonitrile, 22.8 g (0.38 mol) of ethylenediamine and 0.21 g (6.5 mmol) of sulfur was heated and stirred, and 150 ° C. to 280 ° C. for 2 hours. The temperature increased over time. After allowing to cool, a solution consisting of 1.0 g of sodium hydroxide and 10 ml of methanol was added and heated to reflux for 3 hours. After the reaction product was concentrated under reduced pressure, the concentrate was distilled under reduced pressure to obtain 43 g (0.22 mol, yield 64%) of 2- (4-chlorobenzyl) imidazoline as a fraction having a boiling point of 163-170 ° C./4 mmHg.
Next, 27 g (0.17 mol) of potassium permanganate was added little by little at room temperature to a solution consisting of 21 g (0.108 mol) of 2- (4-chlorobenzyl) imidazoline and 250 ml of dioxane, and the mixture was heated to reflux for 8 hours. Insoluble matter was removed by filtration, the filtrate was evaporated to dryness under reduced pressure, and the dried product was washed with water and recrystallized from water-acetonitrile to give 13.5 g of 2- (4-chlorobenzyl) imidazole as milky white crystals ( 0.070 mol, yield 65%) was obtained.

[Reference Example 24]
<Synthesis of Z-4>
First, (2,4-dichlorophenyl) acetamidine hydrochloride was synthesized according to the method of Reference Example 1 by replacing (4-chlorophenyl) acetonitrile of Reference Example 1 with (2,4-dichlorophenyl) acetonitrile.
Subsequently, (4-chlorophenyl) acetamidine hydrochloride of Reference Example 2 was replaced with (2,4-dichlorophenyl) acetamidine hydrochloride and 2-bromoacetophenone was replaced with 2-bromo-2-phenylacetophenone. According to the method, 2- (2,4-dichlorobenzyl) -4,5-diphenylimidazole was synthesized.

  Chemical formulas of imidazole compounds used in Examples are shown in Chemical Formulas 4-6.

  The chemical formula of the imidazole compound used in the comparative example is shown in Chemical formula 7.

  The evaluation test methods employed in the examples and comparative examples are as follows.

[Evaluation test of solderability]
As a test piece, a printed wiring board made of glass epoxy resin of 120 mm (vertical) × 150 mm (horizontal) × 1.6 mm (thickness) having 300 copper through holes with an inner diameter of 0.80 mm was used. The test piece was degreased, soft-etched and washed with water, then immersed in a surface treatment agent maintained at a predetermined liquid temperature for a predetermined time, then washed with water and dried to a thickness of about 0.10 to 0.00 on the copper surface. A 50 μm chemical conversion film was formed.
About the test piece which performed this surface treatment, the reflow heating whose peak temperature is 240 degreeC was performed 3 times using the infrared reflow apparatus (product name: MULTI-PRO-306, Vitronics company make), then, flow solder Soldering was performed using an attaching device (conveyor speed: 1.0 m / min).
The solder used was tin-lead eutectic solder (trade name: H63A, manufactured by Senju Metal Industry Co., Ltd.) having a composition of 63 tin-37 lead (weight%), and the flux used for soldering was JS- 64MSS (manufactured by Hiroki). The solder temperature was 240 ° C.
Further, the test piece subjected to the surface treatment was soldered using lead-free solder in the same manner as in the case of tin-lead eutectic solder. The solder used is a lead-free solder (trade name: H705 “Eco Solder”, manufactured by Senju Metal Industry Co., Ltd.) having a composition of 96.5 tin-3.0 silver-0.5 copper (% by weight). The flux used for attaching is JS-E-09 (manufactured by Hiroki). The peak temperature of reflow heating was 245 ° C., and the solder temperature was 245 ° C.
For the soldered test piece, the number of through holes in which the solder went up to the upper land portion of the copper through hole (soldered) was measured, and the ratio (%) to the total number of through holes (300 holes) was calculated. .
The higher the solder wettability with respect to the copper surface, the more easily the molten solder penetrates into the copper through hole and rises to the upper land portion of the through hole. That is, it is determined that the higher the ratio of the number of through holes in which the solder has reached the upper land portion with respect to the total number of through holes, the better the solder wettability with respect to copper and the better the solderability.

[Evaluation test of solder spreadability]
As a test piece, a printed wiring board made of glass epoxy resin of 50 mm (vertical) × 50 mm (horizontal) × 1.2 mm (thickness) (as a circuit pattern, a circuit part having a conductor width of 0.80 mm and a length of 20 mm made of copper foil) 10 were formed in the width direction at intervals of 1.0 mm). The test piece was degreased, soft-etched and washed with water, then immersed in a surface treatment agent maintained at a predetermined liquid temperature for a predetermined time, then washed with water and dried to a thickness of about 0.10 to 0.00 on the copper surface. A 50 μm chemical conversion film was formed.
About the test piece which performed this surface treatment, the reflow heating whose peak temperature is 240 degreeC was performed once using the infrared reflow apparatus (Product name: MULTI-PRO-306, Vitronics company make). After that, using a metal mask having an opening diameter of 1.2 mm and a thickness of 150 μm, tin-lead cream solder was printed at the center of the copper circuit portion, and reflow heating was performed under the previous conditions to perform soldering. The tin-lead cream solder used is a eutectic solder (trade name: OZ-63-330F-40-10, manufactured by Senju Metal Industry Co., Ltd.) composed of 63 tin-37 lead (% by weight).
Moreover, about the test piece which performed the said surface treatment, it soldered using the lead-free cream solder similarly to the case of a tin-lead cream solder. The lead-free cream solder used was a lead-free solder (commercial name: M705-221BM5-42-11, manufactured by Senju Metal Industry Co., Ltd.) composed of 96.5 tin-3.0 silver-0.5 copper (% by weight). ). The reflow heating performed before and after the cream solder printing was set so that the peak temperature was 245 ° C.
About the obtained test piece, the length (mm) of the solder which wet-spreaded on the copper circuit part was measured.
The larger this length, the better the solder wettability and the better the solderability.

[Example 1]
After dissolving 2- (4-chlorobenzyl) -4-phenylimidazole as an imidazole compound, levulinic acid as an acid, copper acetate and zinc chloride as a metal salt in ion-exchanged water so as to have the composition described in Table 1, A surface treatment agent was prepared by adjusting the pH to 3.6 with aqueous ammonia.
Next, the test piece of the printed wiring board was immersed in a surface treatment agent adjusted to 40 ° C. for 30 seconds, then washed with water and dried, and the solder finish and solder spreadability were measured. These test results were as shown in Table 1.

[Examples 2 to 19]
In the same manner as in Example 1, using the imidazole compounds, acids, metal salts and halogen compounds described in Tables 1-2, surface treatment agents having the compositions described in Tables 1-2 were prepared. Surface treatment was performed under the described treatment conditions. About the obtained test piece, solder rising property and solder spreading property were measured. These test results were as shown in Tables 1-2.

[Comparative Examples 1-6]
In the same manner as in Example 1, using the imidazole compound, acid, metal salt and halogen compound described in Table 3, a surface treatment agent having the composition described in Table 3 was prepared, and the treatment conditions described in Table 3 were used. Surface treatment was performed. About the obtained test piece, solder rising property and solder spreading property were measured. The test results were as shown in Table 3.

  According to the test results shown in Table 1 (Examples 1 to 9) and Table 2 (Examples 10 to 19), the surface treatment agent of the present invention was brought into contact with the copper surface of the printed wiring board to form a chemical on the copper surface. By forming a film, it is recognized that the wettability of eutectic solder or lead-free solder on the copper surface is improved, and the solderability of the eutectic solder or lead-free solder on the copper surface (solderability, solder spreadability) It became good.

  In Examples 1 to 19, the solderability when eutectic solder is used is 100% (only Example 3 is 98%), and there is no difference between Examples 1 to 19, Examples 1 to 3 (hereinafter referred to as “case A”) and Examples 4 to 6 (hereinafter referred to as “case A”) regarding solderability when lead-free solder is used and solder easiness when eutectic solder or lead-free solder is used. , Case B) and Examples 7 to 19 (hereinafter referred to as Case C) were found to be different. That is, in the order of Case A <Case B <Case C, the solder liftability when the lead-free solder is used and the solder spreadability when eutectic solder or lead-free solder is used are improved.

  The imidazole compound used in Case A is a compound in which one of the benzyl group and the phenyl group is substituted with one halogen atom. The imidazole compound used in Case B is a compound in which one halogen atom is substituted on both the benzyl group and the phenyl group. The imidazole compound used in Case C is either (i) one in which only one of the benzyl group or the phenyl group is substituted with two or more halogen atoms (Examples 7 to 9), and (ii) either the benzyl group or the phenyl group. One is substituted with two or more halogen atoms, the other is substituted with one halogen atom (Examples 10 to 16), and (iii) two halogen atoms are present in both the benzyl group and the phenyl group. Substituted (Examples 17 to 19).

According to the test results shown in Table 3 (Comparative Examples 1 to 6), the solderability when the surface treating agent of Comparative Example 4 was used was relatively good. The imidazole compound (Z-4) used in this surface treatment agent is a compound in which two halogen atoms are substituted on the benzyl group, but is bonded to the 5-position of the imidazole ring with the imidazole compound suitable for the practice of the present invention. It differs in the kind of substituent. That is, in the test result of Comparative Example 4, the effect of improving solderability derived from a chemical structure in which a benzyl group substituted with two halogen atoms is bonded to the 2-position of the imidazole ring and a phenyl group is bonded to the 4-position. However, an imidazole compound suitable for practicing the present invention has the above chemical structure and, unlike Z-4, is a hydrogen atom instead of a phenyl group at the 5-position of the imidazole ring. Alternatively, the structure is one in which an alkyl group is bonded, and this is a feature of an imidazole compound suitable for the practice of the present invention.
The surface treatment agent of the present invention can be used without problems even when soldering using eutectic solder, but when soldering using lead-free solder which is inferior in solderability compared to eutectic solder. Can be suitably used.

According to the present invention, when an electronic component or the like is bonded to a printed wiring board using solder, a chemical conversion film having excellent heat resistance is formed on the surface of copper or a copper alloy constituting a circuit portion or the like of the printed wiring board. In addition, a surface treatment agent and a surface treatment method that improve wettability with solder and improve solderability can be provided.
Also, a printed wiring board in which the surface treatment agent is brought into contact with the surface of copper or a copper alloy constituting the circuit part, and a lead-free solder is used after the surface of the copper or copper alloy is brought into contact with the surface treatment agent. Thus, a soldering method for performing soldering can be provided.

Claims (4)

A surface treatment agent for copper or copper alloy comprising an imidazole compound represented by the chemical formula (I) of Chemical Formula 1.

(In the formula, R represents a hydrogen atom or an alkyl group, and X ₁ and X ₂ are the same or different and represent a chlorine atom or a bromine atom. M and n represent an integer of 0 to 3, and at least one of m or n Is 1 or more.) A surface treatment method for copper or copper alloy, wherein the surface treatment agent according to claim 1 is brought into contact with the surface of copper or copper alloy. A printed wiring board, wherein the surface treatment agent according to claim 1 is brought into contact with the surface of copper or copper alloy of the copper circuit portion. A soldering method, wherein the surface of copper or a copper alloy is brought into contact with the surface treatment agent according to claim 1 and then soldered using lead-free solder.