JP2003069205A - Preflux for printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a preflux for a printed wiring board that is superior in solderability. SOLUTION: A non-ionic organic halogen compound is given to a preflux for wiring board. In addition, the content of the organic halogen compound in the preflux ranges between 0.1 mass% and 50 mass% in terms of chlorine to preflux element excluding a solvent. Furthermore, the organic halogen compound is made by combining adjacent carbon with bromine.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a printed wiring board,
The present invention relates to a preflux for printed wiring boards, which is applied to prevent oxidation of circuit electrode portions.

[0002]

2. Description of the Related Art A printed wiring board is formed by molding paper, glass fiber or the like into a plate shape using, for example, a phenol resin or an epoxy resin as a binder, and forming a circuit electrode on the surface thereof using a metal such as copper. is there. Electronic components such as resistors, capacitors, and transformers are joined to the circuit electrode portion of the printed wiring board with a solder alloy. At that time, in order to improve the wettability of the solder alloy to the circuit electrode part on the printed wiring board, the surface is etched for the purpose of removing the oxide film on the surface of the circuit electrode, and flux is added for the purpose of preventing new oxidation. Is applied in advance. This flux is called pre-flux.

Conventionally, as the pre-flux, rosin has been used as it is or after refining, and if necessary, an anticorrosive agent is added. However, rosin usually contains abietic acid and its derivatives and is excellent in solderability but poor in moisture resistance and heat resistance. In addition, when the printed wiring board is stored for a long time or the printed wiring board is heat-treated, there is a problem that the circuit electrode portion is oxidized and the solderability is deteriorated.In order to remove this oxide film, the alkyl imidazole treatment is applied. It was necessary to take measures such as giving it.

For joining electronic parts to a printed wiring board,
Solder paste is used. Recently, lead-free solder has been used due to environmental issues. In conventional tin-lead solder, the paste is stable because the potentials of tin and lead are very close, but with lead-free solder, the potential difference between tin and silver, copper, and zinc causes the activation of the solder metal and flux. It has a drawback that it reacts with the agent, the stability of the solder paste is lowered, and the solderability is lowered. In order to improve the solderability, it is possible to use a strong activator as the flux of the solder paste and increase the amount of the activator, but when the activator becomes stronger and the amount increases, the solder metal and the flux react. And the stability of the solder paste decreases.

Further, the rosin contained in the conventional preflux cannot improve the solderability of lead-free solder.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide a pre-flux for a printed wiring board for providing a printed wiring board excellent in solderability. And

[0007]

As a result of intensive studies to solve the above-mentioned problems, the present inventor found that the use of a non-ionic organic halogen compound as a pre-flux for printed wiring boards leads to poor solderability. The present invention has been completed by finding that good solderability can be obtained even with sufficient lead-free solder. That is, the present invention relates to the following.

(1) A preflux for printed wiring boards containing an organic halogen compound.

(2) The pre-flux for printed wiring board according to (1), wherein the pre-flux for printed wiring board contains a solvent.

(3) The content of the organic halogen compound is 0. 1 in terms of chlorine based on the preflux component excluding the solvent.
The preflux for printed wiring boards according to (1) or (2), which is in the range of 1% by mass to 50% by mass.

(4) The organic halogen compound is a nonionic organic halogen compound (1) to
The pre-flux for printed wiring boards according to any one of (3).

(5) The preflux for printed wiring boards according to any one of (1) to (4), wherein the organic halogen compound is an organic halogen compound in which bromine is bonded to adjacent carbons. .

(6) Organohalogen compounds having Br bonded to adjacent carbons are 2,3-dibromo-1-propanol, 1,4-dibromo-2,3-butanediol, 2,
3-dibromo-2-butene-1,4-diol, 2,3
-Dibromopropene, 2,3-dibromosuccinic acid, 1,
2-dibromo-1-phenylethane, 1,2-dibromostyrene, 9,10,12,13,15,16-hexabromostearic acid, 9,10,12,13,15,1
6-hexabromostearic acid methyl ester, same ethyl ester, 9,10,12,13-tetrabromostearic acid, same methyl ester, same ethyl ester, 9,
10,12,13,15,16-hexabromostearyl alcohol, 9,10,12,13-tetrabromostearyl alcohol, 1,2,5,6,9,10-hexabromocyclododecane, bis (2,2 3-dibromopropyl) succinate, bis (2,3-dibromopropyl) o-phthalate, bis (2,3-dibromopropyl) p-phthalate, bis (2,3-dibromopropyl) o-phthalamide, bis (2,2 3-dibromopropyl) p-phthalamide, tris (2,3-dibromopropyl) trimellitate, tris (2,3-dibromopropyl) trimellitamide, tetra (2,3-dibromopropyl) pyromellitate, tetra (2,3- Dibromopropyl) pyromellitamide, bis (2,3-dibromopropyl) glycerol, Trimethylolpropane bis (2,3-dibromopropyl) ether, bis (2,3
-Dibromopropyl) tartamide, N, N'-bis (2,3-dibromopropyl) succinamide, N, N,
N ', N'-tetra (2,3-dibromopropyl) succinamide, N, N'-bis (2,3-dibromopropyl) urea, N, N, N', N'-tetra (2,3-dibromo) Propyl) urea, 2,2-bis [4- (2,3
-Dibromopropyl) -3,5-dibromophenyl] propane, α, β-dibromoethylbenzene, tris (2,3-dibromopropyl) isocyanurate, dibromoethylbenzene, dibromocinnamic acid, methyl ester, ethyl ester, 1, 2,3,4-tetrabromobutane, 1,2,5,6-tetrabromooctane,
The preflux for a printed wiring board according to (5), which is any one selected from the group consisting of 1,2,7,8-tetrabromododecane.

(7) The pre-flux for printed wiring board according to any one of (1) to (6), wherein the pre-flux for printed wiring board contains rosin.

(8) A step of applying the pre-flux for printed wiring board according to any one of (1) to (7) to the circuit electrode portion of the printed wiring board, and then applying solder paste to the printed wiring board. A method of manufacturing an electronic component mounting board, comprising: a step of placing an electronic component, a step of placing an electronic component, and a step of reflowing a solder paste.

(9) The method for manufacturing an electronic component mounting board according to (8), wherein the solder paste contains a lead-free solder alloy.

(10) The method for manufacturing an electronic component mounting board according to (8) or (9), wherein the solder paste contains a solder alloy containing zinc.

(11) The method for manufacturing an electronic component mounting board according to any one of (8) to (10), wherein the solder paste contains a Sn-Zn alloy.

(12) A printed wiring board coated with the preflux for printed wiring board according to any one of (1) to (7).

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The pre-flux for printed wiring according to the present invention is characterized by containing an organic halogen compound,
In addition to the organic halogen compound, a solvent, a rosin, an anticorrosive agent, an activator and the like can be added if necessary. By using the organic halogen compound as the pre-flux for the printed wiring, at the room temperature, the effect of preventing the oxidation of the circuit electrode surface of the printed wiring board is enhanced and the storage stability of the printed wiring board is improved. Further, during soldering, the organic halogen compound is decomposed to generate a strong acid of hydrogen halide, and the oxide film on the surface of the circuit electrode is removed to remarkably improve solderability.

The organic halogen compound used in the present invention may be any compound which is stable at room temperature and decomposes by heating, and halogen preferably contains bromine. An organic halogen compound containing bromine as a halogen is decomposed by heating to generate hydrogen bromide. Hydrogen bromide is relatively strong as an acid, on the other hand, it has a relatively weak corrosive action on metals and is suitable as a preflux. A substance containing chlorine as a halogen is decomposed by heating to generate hydrogen chloride, which is very strong as an acid, but has a high corrosive action on metals and may corrode circuit electrodes depending on conditions. Further, a substance containing iodine as a halogen is decomposed by heating to generate hydrogen iodide, but hydrogen iodide is weak as an acid and has a weak effect of removing an oxide film, but has little corrosion of circuit electrodes. These organic halogen compounds may be used alone or in combination of two or more.

The pre-flux for a printed wiring board of the present invention is used by diluting it with a solvent for workability in coating,
It is preferable from the viewpoint of uniformity of coating film thickness. As a solvent,
Well-known solvents conventionally used can be used, and for example, alcohols, ketones, aromatic compounds, ester compounds and the like can be preferably used.

At this time, the content of the organic halogen compound in the preflux for printed wiring board is 0.1% by mass to 5 in terms of chlorine based on the preflux component excluding the solvent.
Within the range of 0% by mass, more preferably within the range of 1% by mass to 20% by mass, and most preferably within the range of 2% by mass to 10% by mass.
Within the range of. Addition amount of organic halogen compound is 0.1
If it is less than mass%, there is almost no effect on solderability. If it is more than 50% by mass, the flux remaining after soldering lowers the insulation resistance of the circuit board and lowers the reliability of the electronic component mounting board. The chlorine equivalent is
The converted amount is shown using the molecular weight obtained by converting the halogen of the organic halogen compound into chlorine.

The organic halogen compound of the present invention is preferably a nonionic organic halogen compound. The nonionic organic halogen compound is a compound in which halogen is covalently bonded to the organic compound, and is a compound that thermally decomposes to generate, for example, hydrogen halide of a strong acid. By using this as the organic halogen compound of the present invention, the oxide film of the solder is destroyed and the effect of improving the wettability can be obtained.

Further, the organohalogen compound of the present invention is preferably an organohalogen compound in which bromine is bonded to adjacent carbons. The bromine-containing organohalogen compound is decomposed by heating to produce hydrogen bromide as described above. The generated hydrogen bromide removes the oxide film on the surface of the circuit electrode to improve the solderability, and since the corrosive action is relatively weak, it does not damage the circuit electrode more than necessary and is suitable as a pre-flux. This effect can be further enhanced by using a compound in which bromine is bonded to adjacent carbons of the organic halogen compound.

Examples of compounds suitable for the organic halogen compound of the present invention in which bromine is bonded to adjacent carbons include, for example, 1-bromo-2-butanol and 1-bromo-2-
Propanol, 3-bromo-1-propanol, 3-bromo-1,2-propanediol, 1,4-dibromo-
2-butanol, 1,3-dibromo-2-propanol, 2,3-dibromo-1-propanol, 1,4-dibromo-2,3-butanediol, 2,3-dibromo-
2-butene-1,4-diol, 1-bromo-3-methyl-1-butene, 1,4-dibromobutene, 1-bromo-1-propene, 2,3-dibromopropene, ethyl bromoacetate, α- Ethyl bromocaprylate, ethyl α-bromopropionate, ethyl β-bromopropionate, α
-Bromo-ethyl acetate, 2,3-dibromosuccinic acid, 2
-Bromosuccinic acid, 2,2-dibromoadipic acid, 2,
4-dibromoacetophenone, 1,1-dibromotetrachloroethane, 1,2-dibromo-1-phenylethane, 1,2-dibromostyrene, 4-stearoyloxybenzyl bromide, 4-stearyloxybenzyl bromide, 4-stearylbenzyl bromide , 4-
Bromomethylbenzyl stearate, 4-stearoylaminobenzyl bromide, 2,4-bisbromomethyl benzyl bromide, 4-palmitoyloxybenzyl bromide, 4-myristoyloxybenzyl bromide, 4-lauroyloxybenzil bromide, 4 −
Undecanoyloxybenzyl bromide, 9, 10,
12,13,15,16-hexabromostearic acid,
9,10,12,13,15,16-hexabromostearic acid methyl ester, ethyl ester, 9,1
0,12,13-tetrabromostearic acid, methyl ester, ethyl ester, 9,10,12,13,
15,16-hexabromostearyl alcohol, 9,
10,12,13-Tetrabromostearyl alcohol, 1,2,5,6,9,10-hexabromocyclododecane, bis (2,3-dibromopropyl) succinate, bis (2,3-dibromopropyl) o- Phthalate, bis (2,3-dibromopropyl) p-phthalate, bis (2,3-dibromopropyl) o-phthalamide, bis (2,3-dibromopropyl) p-phthalamide, tris (2,3-dibromopropyl) Trimellitate, tris (2,3-dibromopropyl) trimellitamide, tetra (2,3-dibromopropyl) pyromellitate, tetra (2,3-dibromopropyl) pyromellitamide, bis (2,3-dibromopropyl) glycerol, trimethylol Propane bis (2,3-dibromopropyl) ether, bis 2,3-dibromopropyl)
Tartamide, N, N'-bis (2,3-dibromopropyl) succinamide, N, N, N ', N'-tetra (2,2
3-dibromopropyl) succinamide, N, N'-bis (2,3-dibromopropyl) urea, N, N, N ',
N'-tetra (2,3-dibromopropyl) urea,
2,2-bis [4- (2,3-dibromopropyl)-
3,5-dibromophenyl] propane, α, α, α-tribromomethylsulfone, α, β-dibromoethylbenzene, tris (2,3-dibromopropyl) isocyanurate, dibromoethylbenzene, dibromocinnamic acid, the same methyl ester, Same ethyl ester, 1,2,
Examples include 3,4-tetrabromobutane, 1,2,5,6-tetrabromooctane, 1,2,7,8-tetrabromododecane and the like.

Among these, 2,3-dibromo-1-propanol, 1,4-dibromo-2,3-butanediol,
2,3-dibromo-2-butene-1,4-diol,
2,3-dibromopropene, 2,3-dibromosuccinic acid, 1,2-dibromo-1-phenylethane, 1,2-
Dibromostyrene, 9,10,12,13,15,16
-Hexabromostearic acid, 9, 10, 12, 13,
To 15,16-hexabromostearic acid methyl ester, ethyl ester, 9,10,12,13-tetrabromostearic acid, methyl ester, ethyl ester, 9,10,12,13,15,16- Xabromostearyl alcohol, 9,10,12,13-tetrabromostearyl alcohol, 1,2,5,6,9,
10-hexabromocyclododecane, bis (2,3-dibromopropyl) succinate, bis (2,3-dibromopropyl) o-phthalate, bis (2,3-dibromopropyl) p-phthalate, bis (2,3-) Dibromopropyl) o-phthalamide, bis (2,3-dibromopropyl) p-phthalamide, tris (2,3-dibromopropyl) trimellitate, tris (2,3-dibromopropyl) trimellitamide, tetra (2,3-) Dibromopropyl) pyromellitate, tetra (2,3-dibromopropyl) pyromellitamide, bis (2,3-dibromopropyl) glycerol, trimethylolpropane bis (2,3-dibromopropyl) ether, bis (2,2
3-dibromopropyl) tartamide, N, N′-bis (2,3-dibromopropyl) succinamide, N, N,
N ', N'-tetra (2,3-dibromopropyl) succinamide, N, N'-bis (2,3-dibromopropyl) urea, N, N, N', N'-tetra (2,3-dibromo) Propyl) urea, 2,2-bis [4- (2,3
-Dibromopropyl) -3,5-dibromophenyl] propane, α, β-dibromoethylbenzene, tris (2,3-dibromopropyl) isocyanurate, dibromoethylbenzene, dibromocinnamic acid, methyl ester, ethyl ester, 1, 2,3,4-tetrabromobutane, 1,2,5,6-tetrabromooctane,
It is particularly preferable to use any one selected from the group consisting of 1,2,7,8-tetrabromododecane.

The preflux for printed wiring board of the present invention preferably contains rosin. Since rosin has a strong adhesiveness with metals, it is used by being contained so as to cover it and prevent oxidation with the circuit electrodes of the printed wiring board. As the rosin, a well-known rosin that has been conventionally compounded in a flux can be used. Is mentioned. Terpene resins are α-pinene and β
-A resin obtained by polymerizing terpenes such as pinene, dipentene, and limonene.

Further, in the pre-flux for printed wiring board of the present invention, an activator other than the above, a rust preventive, an antioxidant, etc. can be added, if necessary.

Examples of the activator include hydrohalic acid amine salts such as isopropylamine hydrobromide, butylamine hydrobromide, cyclohexylamine hydrobromide, and 1,3-diphenylguanidine hydrobromide. Etc.

Examples of rust preventives include azoles such as benzotriazole, benzimidazole and tolyltriazole.

Examples of the antioxidant include phenol compounds, phosphoric acid compounds, sulfur compounds, tocophenol and its derivatives, and ascorbic acid and its derivatives.

The printed wiring board pre-flux of the present invention comprises a step of applying the printed wiring board pre-flux to the circuit electrode portion of the printed wiring board, a step of applying solder paste to the printed wiring board thereafter, and an electronic component. It is preferably used in a method of manufacturing an electronic component mounting board including a step of placing and a step of reflowing a solder paste.

The circuit electrode is a circuit portion formed on a substrate, and is usually made of copper, aluminum, silver or the like, and there is also one having its surface plated with copper, silver, solder alloy, tin or the like. .

By applying the pre-flux for a printed wiring board of the present invention to the circuit electrode portions of the printed wiring board, it is possible to prevent the surface of these circuit electrodes from being oxidized. Also, after that, in the process of applying solder paste to the printed wiring board, mounting electronic components, and reflowing the solder paste to bond the electronic components with a solder alloy, the oxide film formed on the surface of the circuit electrodes is removed and the solder is removed. It is possible to provide a method for manufacturing a highly reliable electronic component mounting plate that enhances the wettability of an alloy.

The method of applying the pre-flux for printed wiring board of the present invention to the circuit electrode portion includes, but is not limited to, the dipping method and the spray method.

By using the pre-flux for a printed wiring board of the present invention, a lead-free solder alloy, a solder alloy containing zinc, and Sn--Zn, which have been difficult to use conventionally, are used.
A method for manufacturing an electronic component mounting board using a solder paste containing a base alloy can be provided. The reason for this is considered to be that the organic halogen compound contained in the pre-flux is decomposed during heating to generate hydrogen halide of strong acid and destroy the oxide film on the surface of the solder alloy.

The lead-free solder is, for example, Sn-In.
System, Sn-Bi system, In-Ag system, In-Bi system, Sn
-Zn system, Sn-Ag system, Sn-Cu system, Sn-Sb
System, Sn-Au system, Sn-Bi-Ag-Cu system, Sn-
Ge system, Sn-Bi-Cu system, Sn-Cu-Sb-Ag
System, Sn-Ag-Zn system, Sn-Cu-Ag system, Sn-
Bi-Sb system, Sn-Bi-Sb-Zn system, Sn-Bi
-Cu-Zn system, Sn-Ag-Sb system, Sn-Ag-S
b-Zn system, Sn-Ag-Cu-Zn system, Sn-Zn-
Bi system can be mentioned.

As a specific example of the above, 48Sn / 52I
n, 43Sn / 57Bi, 97In / 3Ag, 58Sn
/ 42In, 95In / 5Bi, 60Sn / 40Bi,
91Sn / 9Zn, 96.5Sn / 3.5Ag, 99.
3Sn / 0.7Cu, 95Sn / 5Sb, 20Sn / 8
0Au, 90Sn / 10Ag, Sn90 / Bi7.5 /
Ag2 / Cu0.5, 97Sn / 3Cu, 99Sn / 1
Ge, 92Sn / 7.5Bi / 0.5Cu, 97Sn /
2Cu / 0.8Sb / 0.2Ag, 95.5Sn / 3.
5Ag / 1Zn, 95.5Sn / 4Cu / 0.5Ag,
96.5Sn / 3Ag / 0.5Cu, 52Sn / 45B
i / 3Sb, 51Sn / 45Bi / 3Sb / 1Zn, 8
5Sn / 10Bi / 5Sb, 84Sn / 10Bi / 5S
b / 1Zn, 88.2Sn / 10Bi / 0.8Cu / 1
Zn, 89Sn / 4Ag / 7Sb, 88Sn / 4Ag /
7Sb / 1Zn, 98Sn / 1Ag / 1Sb, 97Sn
/ 1Ag / 1Sb / 1Zn, 91.2Sn / 2Ag /
0.8Cu / 6Zn, 89Sn / 8Zn / 3Bi, 86
Sn / 8Zn / 6Bi, 89.1Sn / 2Ag / 0.9
Cu / 8Zn etc. are mentioned. Among these, the effect of the present invention is remarkable when a Zn-containing solder alloy, for example, a Sn—Zn-based solder alloy is used.

In the method for manufacturing an electronic component mounting board using the pre-flux for a printed wiring board of the present invention, two or more kinds of solder powders having different compositions may be mixed and used.

The printed wiring board coated with the pre-flux for a printed wiring board of the present invention is suitable for long-term storage because an oxide film does not easily form on the circuit electrode surface, and the oxide film formed on the circuit electrode surface is removed during solder reflow. As a result, the wettability of the solder alloy is increased and a highly reliable joint can be obtained.

[0042]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

(Example 1) Polymerized rosin 4 g, 9, 10,
0.1 g of 12,13,15,16-hexabromostearic acid methyl ester was added to isopropyl alcohol 95.
Pre-flux for printed wiring board 100g dissolved in 9g
Was manufactured. This pre-flux was applied to a FR-4 type printed circuit board having circuit electrodes made of copper by a dipping method. 89Sn / 8 after drying at 100 ° C for 3 minutes
A solder paste using a Zn / 3Bi solder alloy was applied by screen printing. Preheat 150 ° C 90
Second, reflow was performed at a peak temperature of 230 ° C.

The solder paste contains 5% by mass of hydrogenated castor oil as a thixotropic agent, 16% by mass of disproportionated rosin as a rosin, 24% by mass of a polymerized rosin, and 0% of cyclohexylamine hydrobromide as an activator. 1% by mass,
2% triethylamine as an amine, 1% tris (2,3-dibromopropyl) isocyanurate as an organic activator, 1% by mass benzotriazole as a rust inhibitor,
As a solvent, 10 mass% of flux for solder paste prepared by adding 50.9 mass% of 2-ethyl-1,3-hexanediol to 89Sn / 8Z having an average particle diameter of 30 μm.
90% by mass of n / 3Bi solder powder was added and kneaded with a planetary mill to produce.

(Example 2) In Example 1, only the solder alloy was changed to 96.5Sn / 3Ag / 0.5Cu, and the other conditions were the same.

Example 3 A preflux for a printed wiring board was prepared by mixing 5 g of polymerized rosin, 0.5 g of tris (2,3-dibromopropyl) isocyanurate and 94.5 g of isopropyl alcohol. Other conditions were the same as in Example 1.

Example 4 A preflux for printed wiring board was prepared by mixing 6 g of hydrogenated rosin, 0.2 g of 2,3-dibromo-2-butene-1,4-diol and 93.8 g of acetone. . Other conditions were the same as in Example 1.

Example 5 Pre-flux for a printed wiring board was prepared by adding 4 g of a leveled rosin, 0.1 g of phenylimidazole as a rust preventive agent, 0.4 g of tris (2,3-dibromopropyl) isocyanurate, 95. It was manufactured by mixing 5 g. Other conditions were the same as in Example 1.

Example 6 Pre-flux for a printed wiring board was prepared by using 4 g of disproportionated rosin, 0.1 g of phenylimidazole as a rust preventive agent, 0.4 g of tris (2,3-dibromopropyl) isocyanurate, and 95. It was manufactured by mixing 5 g. Other conditions were the same as in Example 2.

(Example 7) A pre-flux for printed wiring board was mixed with 2 g of disproportionated rosin, 2 g of polymerized rosin, 1, 2, and
It was produced by mixing 1 g of 5,6-tetrabromooctane and 95 g of isopropyl alcohol. Other conditions are Example 1
It carried out similarly to.

(Comparative Example 1) 5 g of polymerized rosin and 95% of isopropyl alcohol were used as a pre-flux for a printed wiring board.
It was produced by mixing g. Other conditions were the same as in Example 1.

Comparative Example 2 A preflux for printed wiring board was prepared by mixing 5 g of disproportionated rosin, 0.1 g of phenylimidazole as a rust preventive, and 94.9 g of acetone. Other conditions were the same as in Example 2.

(Evaluation of wettability) Examples 1 to 7, Comparative Example 1,
The entire solder appearance of the FR-4 type printed wiring board prepared in 2 was observed with a 10 × magnifying glass.

That is, the solder powder was completely melted, the solder surface was smooth, the solder balls were not melted, and the wettability was good. The solder powder was not completely melted and the solder surface was uneven or Poor wettability in which three or more unmelted solder balls were observed was defined as x.

(Evaluation of Void) Examples 1 to 7, Comparative Example 1,
The FR-4 type printed wiring board prepared in 2 was measured from above with a micro X-ray device. If there is a void inside the solder, that part looks like a shade, so that part was made a void, and the ratio of the area of the void part to the total solder part area was calculated.

(Evaluation of Solder Balls) The preflux prepared in Examples 1 to 7 and Comparative Examples 1 and 2 was applied by an immersion method to an alumina substrate having five circular copper patterns each having a diameter of 6.5 mm on its surface. And dried at 100 ° C. for 3 minutes.

Thereafter, the thickness is 0.2 mm and the diameter is 6.5 mm.
The solder paste used in Example 1 was printed on the alumina substrate using a printing mask having 5 holes. The substrate after printing was placed on a hot plate set to 235 ° C. in advance, taken out 5 seconds after the solder melted, and left until the solder cooled.

The entire appearance of the solidified solder was observed with a 10 × magnifying glass and evaluated by the agglomeration state of the solder particles specified in Table 1 of JIS Z-3284 (Appendix 11) and FIG.

That is, when the solder powder is melted, the solder becomes one large sphere, and there is no solder ball in the surrounding area. Evaluation 1 is made. When the solder powder is melted, the solder becomes one large sphere, and the diameter is 75 μm or less. The case where there are three or more solder balls is evaluated 2. The case where the solder powder is melted to form one large sphere and there are three or more solder balls with a diameter of 75 μm or less around them and they are not arranged in a semi-continuous ring shape are evaluated. 3, the solder powder is melted and the solder is 1
Evaluation is 4 when there are two large spheres and many fine spheres are lined up in a semi-continuous ring around.
And

The evaluation results are shown in Table 1.

[0061]

[Table 1]

As can be seen from Table 1, by adding a nonionic organic halogen compound to the pre-flux for a printed wiring board, the wettability evaluation, solder ball evaluation and void evaluation required for solderability are remarkable. Improvement was seen.

[0063]

By using the pre-flux for printed wiring board of the present invention, the solderability is remarkably improved. In particular, remarkable effects were seen in the reduction of solder balls and the reduction of voids after reflow.

The printed wiring board coated with the pre-flux for printed wiring board of the present invention has high storage stability,
It has become possible to store it for a long time. Furthermore, it has become easy to apply to lead-free solder alloy, which was difficult to use in the past.

Claims (12)

[Claims] 1. A pre-flux for a printed wiring board containing an organic halogen compound. 2. The pre-flux for printed wiring board according to claim 1, wherein the pre-flux for printed wiring board contains a solvent. 3. The content of the organohalogen compound is within the range of 0.1% by mass to 50% by mass in terms of chlorine based on the preflux component excluding the solvent. Pre-flux for printed wiring boards. 4. The preflux for printed wiring boards according to claim 1, wherein the organic halogen compound is a nonionic organic halogen compound. 5. The pre-flux for printed wiring boards according to claim 1, wherein the organic halogen compound is an organic halogen compound in which bromine is bonded to adjacent carbons. 6. An organohalogen compound having Br bound to adjacent carbons is 2,3-dibromo-1-propanol,
1,4-dibromo-2,3-butanediol, 2,3-
Dibromo-2-butene-1,4-diol, 2,3-dibromopropene, 2,3-dibromosuccinic acid, 1,2-
Dibromo-1-phenylethane, 1,2-dibromostyrene, 9,10,12,13,15,16-hexabromostearic acid, 9,10,12,13,15,16-
Hexabromostearic acid methyl ester, ethyl ethyl ester, 9,10,12,13-tetrabromostearic acid, methyl ester, ethyl ester, 9,1
0,12,13,15,16-hexabromostearyl alcohol, 9,10,12,13-tetrabromostearyl alcohol, 1,2,5,6,9,10-hexabromocyclododecane, bis (2,2 3-dibromopropyl) succinate, bis (2,3-dibromopropyl)
o-phthalate, bis (2,3-dibromopropyl) p
-Phthalate, bis (2,3-dibromopropyl) o-
Phthalamide, bis (2,3-dibromopropyl) p-
Phthalamide, tris (2,3-dibromopropyl) trimellitate, tris (2,3-dibromopropyl) trimellitamide, tetra (2,3-dibromopropyl)
Pyromellitate, tetra (2,3-dibromopropyl)
Pyromellitoamide, bis (2,3-dibromopropyl)
Glycerol, trimethylolpropane bis (2,3-
Dibromopropyl) ether, bis (2,3-dibromopropyl) tertamide, N, N′-bis (2,3-dibromopropyl) succinamide, N, N, N ′, N′-tetra (2,3-dibromopropyl) ) Succiamide, N,
N'-bis (2,3-dibromopropyl) urea, N,
N, N ', N'-tetra (2,3-dibromopropyl)
Urea, 2,2-bis [4- (2,3-dibromopropyl) -3,5-dibromophenyl] propane, α, β-
Dibromoethylbenzene, tris (2,3-dibromopropyl) isocyanurate, dibromoethylbenzene,
Dibromocinnamic acid, methyl ester, ethyl ester, 1,2,3,4-tetrabromobutane, 1,2,
The preflux for printed wiring boards according to claim 5, wherein the preflux is any one selected from the group consisting of 5,6-tetrabromooctane and 1,2,7,8-tetrabromododecane. 7. The pre-flux for printed wiring boards according to claim 1, wherein the pre-flux for printed wiring boards contains rosin. 8. A step of applying the pre-flux for printed wiring board according to claim 1 to a circuit electrode portion of the printed wiring board, and a step of subsequently applying a solder paste to the printed wiring board, A method of manufacturing an electronic component mounting board, comprising: a step of placing an electronic component; and a step of reflowing a solder paste. 9. The method for manufacturing an electronic component mounting board according to claim 8, wherein the solder paste contains a lead-free solder alloy. 10. The method for manufacturing an electronic component mounting board according to claim 8, wherein the solder paste contains a solder alloy containing zinc. 11. The method for manufacturing an electronic component mounting board according to claim 8, wherein the solder paste contains a Sn—Zn alloy. 12. A printed wiring board coated with the pre-flux for printed wiring board according to claim 1.