JP6967050B2 - Flux composition for soldering - Google Patents

Description

The present invention relates to a flux composition for soldering.

As a method of soldering an electronic board and an electronic component, in addition to the so-called reflow soldering method, a method of soldering an electronic component temporarily fastened to the electronic board by contacting it with a jet of molten solder, a so-called flow soldering method. Has also been adopted. In this flow soldering method, for example, a flux composition as described in Patent Document 1 is used before being brought into contact with the molten solder to be jetted.

On the other hand, with the recent trend toward lead-free soldering, solders having a high melting point tend to be used. The most used lead-free solder alloys are tin (Sn) -silver (Ag) -copper (Cu) -based solder alloys, so-called SAC-based solder alloys. Compared with the conventional tin-lead eutectic solder, this SAC-based solder alloy has poor wetting spread on the oxidized copper foil. Therefore, such a flux composition is required to have improved solderability (soldering bridge inhibitory property, solder wettability, wet spread, etc.).
Further, such a flux composition is applied to an electronic substrate by a spray device or the like. However, in some spraying devices, when the flux composition is applied, the components of the flux composition may precipitate, causing flux clogging such as nozzle clogging or draft filter clogging. rice field. When such flux clogging occurs, it is necessary to clean the nozzle or replace the filter, which causes a problem that productivity is lowered.

Japanese Unexamined Patent Publication No. 8-243787

An object of the present invention is to provide a flux composition for soldering, which has excellent solderability and can sufficiently suppress the occurrence of flux clogging.

In order to solve the above problems, the present invention provides the following flux composition for soldering.
The soldering flux composition of the present invention comprises (A) a rosin-based resin, (B) an activator, (C) a solvent, and (D) an aliphatic carboxylic acid having 12 to 24 carbon atoms and 1 to 4 carbon atoms. The component (B) contains a dicarboxylic acid having (B1) 2 to 4 carbon atoms, and the component (C) has a boiling point of 240 ° C. at (C1) 1013 hPa. It is characterized by containing a glycol-based solvent or a terpene-based solvent having a temperature of 320 ° C. or lower.

In the flux composition for soldering of the present invention, it is preferable that the component (B) further contains (B2) a dicarboxylic acid having 5 to 8 carbon atoms.
In the flux composition for soldering of the present invention, it is preferable that the component (B) further contains (B3) rosinamine.

Although it is not always clear why the soldering flux composition of the present invention is excellent in solderability and can sufficiently suppress the occurrence of flux clogging, the present inventors presume as follows.
That is, the present inventors presume that the cause of the flux clogging is the precipitation of the activator in the flux composition. The flux composition for soldering of the present invention uses (B1) a dicarboxylic acid having 2 to 4 carbon atoms from the viewpoint of ensuring the active action, but the component (B1) is precipitated and easily crystallized. be. The soldering flux composition of the present invention comprises a glycol-based solvent or a terpene-based solvent having a boiling point of 240 ° C. or higher and 320 ° C. or lower at (C1) 1013 hPa, which is a solvent remaining after spray coating, and (D) 12 to 12 carbon atoms. It contains 24 aliphatic carboxylic acids and a higher aliphatic ester consisting of an alcohol having 1 to 4 carbon atoms. Then, this component (D) can suppress the precipitation of the component (B1) from the component (C1). In this way, the present inventors presume that the present invention is excellent in solderability and can sufficiently suppress the occurrence of flux clogging.

According to the present invention, it is possible to provide a flux composition for soldering, which is excellent in solderability and can sufficiently suppress the occurrence of flux clogging.

The soldering flux composition of the present embodiment (hereinafter, also simply referred to as “flux composition”) is described below as (A) rosin-based resin, (B) activator, (C) solvent and (D) higher fat. It contains a group ester.
As used herein, lead-free solder refers to solder metals or alloys to which lead is not added. However, it is permissible for lead to be present as an unavoidable impurity in the lead-free solder, but in this case, the amount of lead is preferably 300 mass ppm or less.

Specific examples of the solder alloy in lead-free solder include Sn-Ag, Sn-Ag-Cu, Sn-Cu, Sn-Ag-Bi, Sn-Bi, Sn-Ag-Cu-Bi, and Sn-Sb. Examples thereof include Sn-Zn-Bi, Sn-Zn, Sn-Zn-Al, Sn-Ag-Bi-In, Sn-Ag-Cu-Bi-In-Sb, and In-Ag. Among these, Sn-Ag-Cu based solder alloys are preferably used from the viewpoint of the strength of the solder joint. The melting point of the Sn—Ag—Cu-based solder is usually 200 ° C. or higher and 250 ° C. or lower. Among the Sn—Ag—Cu type solders, the melting point of the solder having a low silver content is 210 ° C. or higher and 250 ° C. or lower (more preferably 220 ° C. or higher and 240 ° C. or lower).

[(A) component]
Examples of the (A) rosin-based resin used in the present embodiment include rosins and rosin-based modified resins. Examples of rosins include gum rosin, wood rosin and tall oil rosin. Examples of the rosin-based modified resin include disproportionated rosin, polymerized rosin, hydrogenated rosin and derivatives thereof. Hydrogenated rosins include fully hydrogenated rosins, partially hydrogenated rosins, and aliphatic unsaturated monobasic acids such as unsaturated organic acids ((meth) acrylic acid, and α, β- such as fumaric acid and maleic acid. Hydrogenated additive of unsaturated organic acid-modified rosin, which is a modified rosin of aliphatic unsaturated dibasic acid such as unsaturated carboxylic acid, unsaturated carboxylic acid having an aromatic ring such as cinnamic acid, etc.) Also known as "rosin"). One of these rosin-based resins may be used alone, or two or more thereof may be mixed and used.

The blending amount of the component (A) is preferably 0.5% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 10% by mass or less, based on 100% by mass of the flux composition. It is particularly preferable that it is 2% by mass or more and 6% by mass or less. When the blending amount of the component (A) is at least the above lower limit, the generation of bridges and icicles can be suppressed more reliably. On the other hand, if the blending amount of the component (A) is not more than the upper limit, the flux residue can be further reduced.

[(B) component]
The (B) activator used in this embodiment contains (B1) a dicarboxylic acid having 2 to 4 carbon atoms. With this component (B1), solderability (soldering bridge restraint, solder wettability, wet spread, etc.) can be improved.
Examples of the component (B1) include oxalic acid, malonic acid and succinic acid. Among these, succinic acid is preferable from the viewpoint of active action. One of these may be used alone, or two or more thereof may be mixed and used.

The blending amount of the component (B1) is preferably 0.1% by mass or more and 5% by mass or less, more preferably 0.5% by mass or more and 4% by mass or less, and 1% by mass or more and 3% by mass or less. Is particularly preferable. When the blending amount of the component (B1) is at least the above lower limit, the generation of bridges and icicles can be suppressed more reliably. On the other hand, when the blending amount of the component (B1) is not more than the upper limit, the occurrence of flux clogging can be suppressed more reliably.

The component (B) preferably further contains (B2) a dicarboxylic acid having 5 to 8 carbon atoms. With this component (B2), there is a tendency that the crystal when the component (B1) is crystallized can be made finer, and the occurrence of flux clogging can be suppressed more reliably.
Examples of the component (B2) include glutaric acid, adipic acid, pimelic acid and suberic acid. Among these, adipic acid is preferable from the viewpoint of miniaturization of the crystal composed of the component (B1). One of these may be used alone, or two or more thereof may be mixed and used.

The blending amount of the component (B2) is preferably 0.1% by mass or more and 3% by mass or less, more preferably 0.2% by mass or more and 2% by mass or less, and 0.3% by mass or more and 1% by mass. % Or less is particularly preferable. When the blending amount of the component (B2) is within the above range, the occurrence of flux clogging can be suppressed more reliably.

The component (B) preferably further contains (B3) rosinamine. With this component (B3), the occurrence of flux clogging can be suppressed more reliably, and copper foil corrosion can also be suppressed.
Examples of the component (B3) include those containing dehydroabiethylamine as a main component (preferably 50% by mass or more, more preferably 70% by mass or more, particularly preferably 90% by mass or more). This rosin amine can be produced, for example, by reacting rosins with ammonia and then hydrogenating them. Examples of rosins include those similar to the component (A).

The blending amount of the component (B3) is preferably 0.1% by mass or more and 3% by mass or less, more preferably 0.2% by mass or more and 2% by mass or less, and 0.3% by mass or more and 1% by mass. % Or less is particularly preferable. When the blending amount of the component (B3) is within the above range, the occurrence of flux clogging can be more reliably suppressed, and the corrosion of copper foil can also be suppressed.

The component (B) may further contain a known activator (component (B4)) other than the components (B1) to (B3). Examples of the component (B4) include organic acids other than the components (B1) and (B2), non-dissociative activators composed of non-dissociative halogenated compounds, and amine-based activators. One of these may be used alone, or two or more thereof may be mixed and used.
Examples of the organic acid other than the component (B1) and the component (B2) include a monocarboxylic acid, a dicarboxylic acid other than the component (B1) and the component (B2), and other organic acids.
Monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid and tubercrostearic acid. , Arakidic acid, behenic acid, lignoseric acid, and glycolic acid.
Examples of the dicarboxylic acid include azelaic acid, sebacic acid, fumaric acid, maleic acid, tartaric acid, and diglycolic acid.
Other organic acids include dimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anis acid, citric acid, picolin acid and the like.

Examples of the non-dissociable activator composed of a non-dissociable halogenated compound include non-salt organic compounds in which halogen atoms are covalently bonded. The halogenated compound may be a compound formed by a covalent bond of each single element of chlorine, bromine, and fluorine, such as chlorinated, bromine, and fluoride, but any two or all of chlorine, bromine, and fluorine can be used. It may be a compound having a covalent bond of. These compounds preferably have polar groups such as hydroxyl groups and carboxyl groups, such as alcohol halides and carboxyl halides, in order to improve solubility in aqueous solvents. Examples of the halogenated alcohol include brominated alcohols (2,3-dibromopropanol, 2,3-dibromobutandiol, trans-2,3-dibromo-2-butene-1,4-diol (TDBD), 1,4. -Dibromo-2-butanol, tribromoneopentyl alcohol, etc.), chlorinated alcohol (1,3-dichloro-2-propanol, and 1,4-dichloro-2-butanol, etc.), fluorinated alcohol (3-fluoro, etc.) (Catecol, etc.), and other similar compounds. Halogenated carboxyls include carboxyl iodide (2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, 5-iodoanthranic acid, etc.), carboxyl chloride (2-chlorobenzoic acid, etc.). , And 3-chloropropionic acid, etc.), carboxylated bromide (2,3-dibromopropionic acid, 2,3-dibromosuccinic acid, 2-bromobenzoic acid, etc.), and other similar compounds.

Amine-based activators include amines (polyamines such as ethylenediamine), amine salts (amines such as trimethylolamine, cyclohexylamine and diethylamine, organic acid salts such as aminoalcohol and inorganic acid salts (hydrochloride, sulfuric acid, bromide). Hydrogen acid etc.)), amino acids (glycine, alanine, aspartic acid, glutamic acid, valine etc.), amide compounds and the like. Specifically, diphenylguanidine hydrobromide, cyclohexylamine hydrobromide, diethylamine salts (salts, succinates, adipates, sebacates, etc.), triethanolamine, monoethanolamine, and , Hydrobromide of these amines and the like.

The blending amount of the component (B) is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 8% by mass or less with respect to 100% by mass of the flux composition. It is particularly preferable that the content is 2% by mass or more and 5% by mass or less. When the blending amount is not less than the lower limit, the solderability can be improved, while when it is not more than the upper limit, the insulating property of the flux composition can be ensured.

[(C) component]
The solvent (C) used in the present embodiment contains a glycol-based solvent or a terpene-based solvent having a boiling point of (C1) 1013 hPa of 240 ° C. or higher and 320 ° C. or lower. With this component (C1), the component (B1) can be dissolved in the flux composition after spray coating.

The components (C1) include triethylene glycol monomethyl ether (249 ° C), polyethylene glycol monomethyl ether (295 ° C), triethylene glycol monobutyl ether (271 ° C), diethylene glycol monohexyl ether (259 ° C), and diethylene glycol mono2-ethylhexyl. Ether (272 ° C), ethylene glycol monophenyl ether (245 ° C), diethylene glycol monophenyl ether (283 ° C), ethylene glycol monobenzyl ether (256 ° C), diethylene glycol monobenzyl ether (302 ° C), tripropylene glycol monoethyl ether (242 ° C), tripropylene glycol monobutyl ether (274 ° C), propylene glycol monophenyl ether (243 ° C), diethylene glycol dibutyl ether (255 ° C), tetraethylene glycol dimethyl ether (275 ° C) and isobornylcyclohexanol (310 ° C). 318 ° C.) and the like. Among these, tripropylene glycol monobutyl ether, propylene glycol monophenyl ether, diethylene glycol mono2-ethylhexyl ether, and isobornylcyclohexanol are preferable. One of these may be used alone, or two or more thereof may be mixed and used. The temperature shown in parentheses is the boiling point of the above solvent.

The blending amount of the component (C1) is preferably 0.5% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 5% by mass or less, and 1.5% by mass or more and 3% by mass or less. Is particularly preferable. When the blending amount of the component (C1) is within the above range, the occurrence of flux clogging can be suppressed more reliably.

The component (C) preferably contains (C2) a water-soluble solvent having a boiling point of 100 ° C. or lower. With this component (C2), the flux composition can be adjusted to an appropriate range.
Examples of the component (C2) include ethyl alcohol and isopropyl alcohol. One of these may be used alone, or two or more thereof may be mixed and used.

The component (C) may further contain a solvent (component (C3)) other than the component (C1) and the component (C2). Examples of the component (C3) include hydrocarbon solvents (isooctane and the like) and the like. One of these may be used alone, or two or more thereof may be mixed and used.

The blending amount of the component (C) is preferably 70% by mass or more and 95% by mass or less, more preferably 75% by mass or more and 92% by mass or less, and 80% by mass with respect to 100% by mass of the flux composition. It is particularly preferable that it is% or more and 90% by mass or less. When the blending amount is within the above range, the coatability of the flux composition can be adjusted within an appropriate range.

[(D) component]
The (D) higher aliphatic ester used in the present embodiment is a higher aliphatic ester composed of an aliphatic carboxylic acid having 12 to 24 carbon atoms and an alcohol having 1 to 4 carbon atoms. This component (D) can improve the solubility of the component (B1) in the component (C1) and suppress precipitation. Further, when the component (B1) is precipitated by being left for a long time, it can be quickly redissolved in the liquid by supplying a new liquid, and flux clogging can be suppressed. When the number of carbon atoms of the aliphatic carboxylic acid is 11 or less, the above effect is insufficient. On the other hand, aliphatic carboxylic acids having 25 or more carbon atoms are difficult to obtain. Further, when the number of carbon atoms of the alcohol is 5 or more, the above effect is insufficient. The aliphatic carboxylic acid preferably has 12 to 18 carbon atoms, and particularly preferably 18. The carbon number of the alcohol is preferably 2 to 4, and particularly preferably 4.
One of these higher aliphatic esters may be used alone, or two or more thereof may be mixed and used.

Here, the aliphatic carboxylic acid may be saturated or unsaturated. Further, the aliphatic carboxylic acid may have a branch.
The aliphatic carboxylic acids include lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearate, nonadesilic acid, arachidic acid, henicosyl acid, bechenic acid, tricosyl acid, lignoceric acid, α-linolenic acid, and linoleic acid. , And oleic acid and the like.
Examples of the alcohol include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, tert-butyl alcohol and the like.

The blending amount of the component (D) is preferably 0.1% by mass or more and 5% by mass or less, and preferably 0.2% by mass or more and 3% by mass or less with respect to 100% by mass of the flux composition. It is more preferably 0.5% by mass or more and 2% by mass or less. When the blending amount is not less than the lower limit, the occurrence of flux clogging can be suppressed more reliably, while when it is not more than the upper limit, insulation reliability can be maintained.

In the flux composition of the present embodiment, in addition to the components (A) to (D), additives such as a thix agent, an antioxidant, an antifoaming agent, a rust preventive agent, and a surfactant are added, if necessary. May be contained. The blending amount of these additives is preferably 0.01% by mass or more and 5% by mass or less with respect to 100% by mass of the flux composition.

[Soldering method]
Next, a soldering method using the flux composition of the present embodiment will be described. The soldering method of the present embodiment is a method including a component mounting step, a flux applying step, and a soldering step described below.

In the component mounting process, first, the electronic component is inserted into the electronic board and mounted.
Examples of the electronic board include a printed wiring board and the like.
Electronic components can be inserted into through-holes on an electronic board, and are used in a method of mounting by soldering after insertion (so-called through-hole mounting). Electronic components include integrated circuits, transistors, diodes, resistors and capacitors.

In the flux application step, the above-mentioned flux composition is applied to the soldered surface of the electronic substrate.
As a flux composition coating device, a spray fluxer or the like can be adopted from the viewpoint of stability of the coating amount. Since the flux composition of the present embodiment can sufficiently suppress the occurrence of flux clogging, it can be suitably used for a spray fluxer.
From the viewpoint of solderability, the coating amount of the flux composition ^{is preferably 30 mL / m 2} or more and 180 mL / m ² or less, more preferably 40 mL / m ² or more and 150 mL / m ² or less, and more preferably 50 mL / m /. it is particularly preferred m is ² or more 120 mL / ^{m 2} or less.

In the soldering process, the soldered surface of the electronic board is brought into contact with the molten solder for soldering.
The method of contacting the molten solder is not particularly limited as long as it can contact the molten solder with the electronic substrate. As such a method, for example, a method of contacting with molten solder jetting on an electronic substrate (flow soldering method) may be adopted. Further, a method of bringing the solder bath containing the molten solder into contact with the electronic board may be adopted.
The soldering conditions may be appropriately set according to the melting point of the solder. For example, when a Sn—Au—Cu based solder alloy is used, the temperature of the molten solder may be set to 230 ° C. or higher and 280 ° C. or lower (preferably 250 ° C. or higher and 270 ° C. or lower). The preheat temperature may be set to a heating temperature of 80 ° C. or higher and 130 ° C. or lower (preferably 90 ° C. or higher and 120 ° C. or lower).

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these examples. The materials used in Examples and Comparative Examples are shown below.
((A) component)
Rosin resin: Product name "China Rosin X", manufactured by Arakawa Chemical Industry Co., Ltd. ((B1) component)
Activator A: Succinic acid ((B2) component)
Activator B: Adipic acid ((B3) component)
Activator C: Product name "Rodinamine", manufactured by Maruzen Yuka Shoji Co., Ltd. ((B3) ingredient)
Activator D: Trans-2,3-dibromo-2-butene-1,4-diol (TDBD), manufactured by Maruzen Yuka Shoji Co., Ltd. ((C1) component)
Solvent A: Tripropylene glycol monobutyl ether ((C2) component)
Solvent B: Isopropyl alcohol ((C3) component)
Solvent C: Isooctane, manufactured by Maruzen Yuka Shoji Co., Ltd. (component (D))
Higher fatty acid ester: Butyl stearate, trade name "Exepearl BS", manufactured by Shimada Trading Co., Ltd.

[Example 1]
Rosin resin 3% by mass, activator A 1.7% by mass, activator B 0.3% by mass, activator C 0.3% by mass, activator D 0.7% by mass, higher fatty acid ester 0.5% by mass, solvent A2 .5% by mass, solvent B86% by mass and solvent C5% by mass were put into a container and mixed to obtain a flux composition.

[Examples 2 to 7 and Comparative Examples 1 to 3]
A flux composition was obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 1.

<Evaluation of flux composition>
The characteristics of the flux composition (flux clogging, solder bridge, copper foil corrosion) were evaluated by the following methods. The results obtained are shown in Table 1.
(1) Flux clogging A flux composition was applied with a spray fluxer (“TAF40-12PV”, manufactured by Tamura Corporation) under the following conditions.
Spray nozzle diameter: 1.2mm
Application amount: 100 mL / m ²
Then, after the application of the flux composition was carried out for 1 hour, the states of (i) the spray nozzle and (ii) the drain filter were visually confirmed, and the flux clogging was evaluated according to the following criteria.
(I) Spray nozzle ○: There are no crystals around the spray nozzle.
Δ: There are a few crystals around the spray nozzle.
X: There are crystals around the spray nozzle.
(Ii) Drain filter ◯: There is no deposit on the drain filter, or the deposit on the drain filter is liquid.
X: The deposits adhering to the drain filter are powdery or solid.
(2) A board into which a solder bridge connector can be inserted (deteriorated copper foil) is prepared, and from the back side of this board, a connector (“B8b-EH (LF) (SN)”, JST. Mfg. Co., manufactured by Ltd., tin-plated 8-pin) was inserted at 10 points and temporarily fixed with tape to obtain a test plate.
A flux composition was applied to this test plate with a spray fluxer (“TAF40-12PV”, manufactured by Tamura Corporation) under the following conditions.
Spray nozzle diameter: 1.2mm
Application amount: 110 mL / m ²
Then, flow soldering was performed on this test plate to obtain a sample for evaluation. The flow soldering conditions here are a preheat temperature of 100 to 120 ° C. (30 to 60 seconds), a solder temperature of 250 ° C., and a solder alloy composition of 96.5 Sn-3.0Ag-0.5Cu.
Ten points of the connector portion of the obtained evaluation sample were observed, and the portion where the adjacent land or the connector pin was short-circuited by the solder was counted as a defective portion. Three evaluation samples were prepared, and the solder bridge was evaluated according to the following criteria from the total number of defective parts in all connectors.
◯: The number of defective points is less than 40.
X: The number of defective points is 40 or more.
(3) Corrosion of copper foil A copper plate (size: 50 mm × 50 mm, thickness: 0.5 mm) was cleaned, and a steel ball having a diameter of 20 mm was formed in the center to form a depression having a depth of 3 mm. Next, 1 g of wire solder (alloy composition: 96.5 Sn-3.0Ag-0.5Cu) was spirally wound and placed in the center of the copper plate. Next, a test plate was obtained by repeating dropping and drying the flux composition in the recesses of the copper plate so that the solid content was 0.035 to 0.040 g. This test plate was heated on a solder bath set at a temperature of 250 ° C., and heating was continued for 5 seconds after the solder was melted. Then, after allowing to cool to room temperature, it was put into a constant temperature and humidity chamber having a temperature of 40 ° C. and a humidity of 90% RH for 96 hours. Then, the change of the test plate before and after charging was visually observed, and the copper foil corrosion was evaluated according to the following criteria.
◯: There is no significant discoloration or corrosion on the copper plate in the flux residue portion spread on the copper plate.
Δ: Significant discoloration or corrosion to the copper plate is observed in the flux residue portion spread on the copper plate.

As is clear from the results shown in Table 1, when the flux composition of the present invention is used (Examples 1 to 7), all of the flux clogging, the solder bridge, and the copper foil corrosion are good. Do you get it. Therefore, according to the present invention, it has been confirmed that the solderability is excellent and the occurrence of flux clogging can be sufficiently suppressed.

The flux composition for soldering of the present invention can be particularly preferably used as a technique for mounting an electronic component on an electronic board such as a printed wiring board of an electronic device.

Claims (3)

(A) rosin resin, (B) a active agent, (C) a solvent, and contains a higher aliphatic ester consisting of (D) an alcohol having 1 to 4 aliphatic carboxylic acid with a carbon number of 12 to 24 carbon atoms It is a flux composition
The component (B) contains (B1) a dicarboxylic acid having 2 to 4 carbon atoms.
The component (C) contains a glycol-based solvent or a terpene-based solvent having a boiling point of 240 ° C. or higher and 320 ° C. or lower at (C1) 1013 hPa.
The blending amount of the component (B1) is 0.1% by mass or more and 5% by mass or less with respect to 100% by mass of the flux composition.
The blending amount of the component (C1) is 0.5% by mass or more and 10% by mass or less with respect to 100% by mass of the flux composition.
A flux composition for soldering, wherein the blending amount of the component (D) is 0.1% by mass or more and 5% by mass or less with respect to 100% by mass of the flux composition. In the soldering flux composition according to claim 1,
A flux composition for soldering, wherein the component (B) further contains (B2) a dicarboxylic acid having 5 to 8 carbon atoms. In the soldering flux composition according to claim 1 or 2.
A flux composition for soldering, wherein the component (B) further contains (B3) rosinamine.