JP7557143B2 - Manufacturing method of flux and joint body - Google Patents

Description

The present invention relates to a method for manufacturing a flux and a joint.

Fixing components to a board and electrically connecting the components to the board are generally performed by soldering, which uses flux, solder, or a solder paste made by mixing the flux and solder.
Flux has the effect of chemically removing metal oxides that exist in the solder and in the metal surface of the objects to be soldered, enabling the movement of metal elements at the interface between the two. Therefore, by using flux for soldering, an intermetallic compound is formed between the two, resulting in a strong joint.

In soldering, a method such as flow soldering or reflow soldering is adopted depending on the size of the objects to be joined.
In flow soldering, flux is first applied to a board on which components are mounted, and then, while the board on which the components are mounted is being transported, molten solder is jetted from below and brought into contact with the surface to be soldered, thereby performing soldering.
In reflow soldering, first, a solder paste is printed on a board, then components are mounted on the board, and the board on which the components are mounted is heated in a heating furnace called a reflow furnace to perform soldering.

Fluxes used in soldering generally contain a resin component, a solvent, an activator, a thixotropic agent, etc. For example, the examples of Patent Document 1 describe a flux used in flow soldering that contains rosin as a resin component and an organic acid, an organic halogen compound, or an amine hydrohalide as an activator.

Patent No. 6617848

In recent years, from the viewpoint of energy conservation, solder containing Sn and Bi, which allows soldering at lower temperatures, has been used. Solder containing Sn and Bi is prone to producing oxides (called dross) in the molten state because Bi is easily oxidized. In addition, when solder containing Sn and Bi is used, the dross that is produced is prone to adhering to the circuit board. Dross that adheres to the circuit board may cause short circuits and reduced insulation.

The flux described in Patent Document 1 may easily cause dross to adhere to the surface of the substrate. Therefore, the present invention aims to provide a flux and a method for manufacturing a joint that can prevent dross from adhering to the surface of the substrate during soldering.

［式中、Ｒ^１は、連結基又は単結合である。Ｒ^２は、炭素数１～２のアルキル基又は水素原子である。ｍは、１以上４以下の整数である。ｎは、０以上３以下の整数である。ｍ＋ｎ≦４である。］ The present invention includes the following aspects.
[1] A composition comprising rosin, a solvent, and a compound represented by the following general formula (1):
A flux, the content of the solvent being 60 mass% or more with respect to the total mass (100 mass%) of the flux.

[In the formula, R ¹ is a linking group or a single bond. R ² is an alkyl group having 1 to 2 carbon atoms or a hydrogen atom. m is an integer of 1 to 4. n is an integer of 0 to 3. m+n≦4.]

[2] The flux according to [1], wherein in the general formula (1), n is 1.
[3] The flux according to [2], wherein the content of the compound represented by the general formula (1) is 0.03 mass % or more and 5 mass % or less with respect to the total mass (100 mass %) of the flux.
[4] The flux according to [2], further comprising an organic acid (excluding the compound represented by the general formula (1)), wherein a mass ratio of the compound represented by the general formula (1) to the organic acid is 0.05 to 10, as a mass ratio represented by the compound represented by the general formula (1)/organic acid.

[5] The flux according to [1], wherein in the general formula (1), n is 0.
[6] The flux according to [5], wherein the content of the compound represented by the general formula (1) is 0.2 mass % or more and 5 mass % or less with respect to the total mass (100 mass %) of the flux.
[7] The flux according to [5], further comprising an organic acid (excluding the compound represented by the general formula (1)), wherein a mass ratio of the compound represented by the general formula (1) to the organic acid is 0.25 to 10, as a mass ratio represented by the compound represented by the general formula (1)/organic acid.

[8] The flux according to any one of [1] to [7], wherein the rosin includes a rosin (PA) having a softening point of more than 100°C and a rosin (PB) having a softening point of 100°C or lower.
[9] The flux according to [8], wherein a mixing ratio of the rosin (PA) to the rosin (PB) is, as a mass ratio represented by (PA)/(PB), 1/9 to 5/5.

[10] The flux according to any one of [1] to [9], further comprising a halogenated salt of a primary amine.
[11] The flux according to any one of [1] to [8], which does not contain a halogen compound.
[12] The flux according to any one of [1] to [11], wherein the solvent includes one or more selected from the group consisting of ethanol and 2-propanol.

[13] A method for producing a bonded body, comprising the step of soldering a solder alloy to a surface of a substrate treated with the flux according to any one of [1] to [12] to obtain a bonded body.
[14] The method for producing a joint body according to [13], wherein the solder alloy is a solder alloy containing Sn and Bi.

The present invention provides a flux and a method for manufacturing a joint that can prevent dross from adhering to the surface of a substrate during soldering.

(Flux)
The flux according to the present embodiment contains rosin, a solvent, and an activator.
The content of the solvent is 60 mass % or more with respect to the total mass (100 mass %) of the flux. The flux according to the present embodiment is suitably used for flow soldering.

In this specification, the solid content of the flux refers to all remaining components of the flux excluding only the solvent.

<Rosin>
The flux according to the present embodiment contains rosin.
In the present invention, "rosin" includes natural resins containing abietic acid as a main component or a mixture of abietic acid and its isomers, as well as chemically modified natural resins (sometimes referred to as rosin derivatives).

The total content of abietic acid and abietic acid isomers in the natural resin is, for example, 40% by mass or more and 80% by mass or less with respect to the natural resin.
In this specification, the term "main component" refers to a component that is contained in a compound in an amount of 40 mass % or more among components constituting the compound.

Representative isomers of abietic acid include neoabietic acid, parastric acid, and levopimaric acid. The structure of abietic acid is shown below.

Examples of the "natural resins" include gum rosin, wood rosin, and tall oil rosin.

In the present invention, "chemically modified natural resins (rosin derivatives)" include those obtained by subjecting the "natural resins" to one or more treatments selected from the group consisting of hydrogenation, dehydrogenation, neutralization, alkylene oxide addition, amidation, dimerization and oligomerization, esterification, and Diels-Alder cycloaddition.

Examples of rosin derivatives include purified rosin and modified rosin.
Examples of modified rosins include hydrogenated rosin, polymerized rosin, polymerized hydrogenated rosin, disproportionated rosin, acid-modified rosin, rosin ester, acid-modified hydrogenated rosin, acid anhydride-modified hydrogenated rosin, acid-modified disproportionated rosin, acid anhydride-modified disproportionated rosin, phenol-modified rosin and α,β-unsaturated carboxylic acid modified products (acrylic acid-modified rosin, maleic acid-modified rosin, fumaric acid-modified rosin, etc.), as well as purified products, hydrogenated products and disproportionated products of the polymerized rosins, purified products, hydrogenated products and disproportionated products of the α,β-unsaturated carboxylic acid modified products, rosin alcohol, rosin amine, hydrogenated rosin alcohol, rosin ester, hydrogenated rosin ester, rosin soap, hydrogenated rosin soap, acid-modified rosin soap, etc.

The rosin amine is, for example, a mixture of dehydroabietylamine, dihydroabietylamine, and tetrahydroabietylamine, which means a so-called disproportionated rosin amine. The structures of dehydroabietylamine, dihydroabietylamine, and tetrahydroabietylamine are shown below.

The rosin may be used alone or in combination of two or more kinds.
The rosin preferably contains a rosin derivative, and preferably contains one or more selected from the group consisting of acid-modified hydrogenated rosin, hydrogenated rosin, disproportionated hydrogenated rosin, and hydrogenated rosin ester, and more preferably contains acid-modified hydrogenated rosin, hydrogenated rosin, disproportionated hydrogenated rosin, and hydrogenated rosin ester, and may be composed of acid-modified hydrogenated rosin, hydrogenated rosin, disproportionated hydrogenated rosin, and hydrogenated rosin ester.
The acid-modified hydrogenated rosin preferably contains acrylic acid-modified hydrogenated rosin.
The hydrogenated rosin ester preferably comprises a hydrogenated rosin glycerin ester.

The rosin preferably contains rosin (PA) with a softening point above 100°C and rosin (PB) with a softening point below 100°C.

The softening point of rosin can be measured by the ring and ball method. Examples of the ring and ball method include the method described in JIS K 5902.

By containing the rosin (PA) in the rosin (P), it becomes easier to reduce the stickiness of the flux residue.

The softening point of the rosin (PA) is preferably 110°C or higher, more preferably 115°C or higher, even more preferably 120°C or higher, particularly preferably 125°C or higher, and most preferably 130°C or higher.
When the softening point of the rosin (PA) is equal to or higher than the lower limit, the stickiness of the flux residue can be more easily reduced.

The softening point of the rosin (PA) is preferably 170°C or less, more preferably 160°C or less, and even more preferably 150°C or less.

The softening point of the rosin (PA) may be higher than 100°C and not higher than 170°C, preferably from 110°C to 160°C, more preferably from 115°C to 160°C, even more preferably from 120°C to 160°C, particularly preferably from 125°C to 160°C, and most preferably from 130°C to 160°C.
Alternatively, the softening point of the rosin (PA) is preferably 110°C or higher and 150°C or lower, more preferably 115°C or higher and 150°C or lower, even more preferably 120°C or higher and 150°C or lower, particularly preferably 125°C or higher and 150°C or lower, and most preferably 130°C or higher and 150°C or lower.
When the softening point of the rosin (PA) is within the above range, the stickiness of the flux residue can be more easily reduced.

By containing the rosin (PB) in the rosin (P), the fluidity of the flux is increased. This makes it easier to prevent soldering defects.

The softening point of the rosin (PB) is preferably 96° C. or lower, and more preferably 93° C. or lower.
The softening point of the rosin (PB) is preferably 60° C. or higher, more preferably 65° C. or higher, and even more preferably 70° C. or higher.

The softening point of the rosin (PB) may be 60°C or higher and 100°C or lower, preferably 60°C or higher and 96°C or lower, more preferably 65°C or higher and 96°C or lower, and even more preferably 70°C or higher and 96°C or lower.
Alternatively, the softening point of the rosin (PB) is preferably 60° C. or higher and 93° C. or lower, more preferably 65° C. or higher and 93° C. or lower, and even more preferably 70° C. or higher and 93° C. or lower.
When the softening point of the rosin (PB) is within the above range, the fluidity of the flux can be increased, which makes it easier to prevent soldering defects.

The rosin (PA) may be used alone or in combination of two or more kinds.
The rosin (PA) preferably contains an acid-modified hydrogenated rosin, and may consist of an acid-modified hydrogenated rosin.

The rosin (PB) may be used alone or in combination of two or more kinds.
The rosin (PB) preferably contains one or more selected from the group consisting of hydrogenated rosin, disproportionated hydrogenated rosin, rosin ester, and hydrogenated rosin ester, more preferably contains disproportionated hydrogenated rosin and hydrogenated rosin ester, and may be composed of disproportionated hydrogenated rosin and hydrogenated rosin ester.
Alternatively, the rosin (PB) preferably contains hydrogenated rosin and hydrogenated rosin ester, and may consist of hydrogenated rosin and hydrogenated rosin ester.

The rosin content in the flux is preferably 5% by mass or more and 20% by mass or less, and more preferably 8% by mass or more and 15% by mass or less, relative to the total mass of the flux (100% by mass).

In the solid content of the flux, the rosin content is preferably 30% by mass or more and 95% by mass or less, more preferably 40% by mass or more and 90% by mass or less, and even more preferably 50% by mass or more and 90% by mass or less, relative to the total amount of the solid content (100% by mass).

When the flux contains a halogen compound described later, the mixing ratio of the rosin (PA) to the rosin (PB), expressed as a mass ratio of (PA)/(PB), is preferably (PA)/(PB)=1/9 to 5/5, more preferably (PA)/(PB)=1/9 to 4/6, and even more preferably (PA)/(PB)=2/8 to 4/6.
When the mixing ratio is equal to or greater than the lower limit of the range, the stickiness of the flux residue can be more easily reduced. When the mixing ratio is equal to or less than the upper limit of the range, the fluidity of the flux can be more easily increased. This makes it easier to suppress soldering defects.

When the flux does not contain a halogen compound described later, the mixing ratio of the rosin (PA) to the rosin (PB), expressed as a mass ratio of (PA)/(PB), is preferably (PA)/(PB)=3/7 to 8/2, more preferably (PA)/(PB)=4/6 to 7/3, and further preferably (PA)/(PB)=5/5 to 6/4.
When the mixing ratio is equal to or greater than the lower limit of the range, the stickiness of the flux residue can be more easily reduced. When the mixing ratio is equal to or less than the upper limit of the range, the fluidity of the flux can be more easily increased. This makes it easier to suppress soldering defects.

<Solvent>
Examples of the solvent include water, alcohol-based solvents, glycol ether-based solvents, and terpineols.

Alcohol-based solvents include 2-propanol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, isobornylcyclohexanol, 2,4-diethyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2,5-dimethyl-2,5-hexanediol, 2,5-dimethyl-3-hexyne-2,5-diol, 2,3-dimethyl-2,3-butanediol, 2-methylpentane-2,4-diol, 1,1,1-tris(hydroxymethyl)propane, 2-ethyl-2-hydro Examples of such hydroxymethyl-1,3-propanediol include 2,2'-oxybis(methylene)bis(2-ethyl-1,3-propanediol), 2,2-bis(hydroxymethyl)-1,3-propanediol, 1,2,6-trihydroxyhexane, 1-ethynyl-1-cyclohexanol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 2-hexyl-1-decanol, 2-methyl-2,4-pentanediol (hexylene glycol), and octanediol.

Examples of glycol ether solvents include diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, ethylene glycol monobutyl ether (butyl glycol), ethylene glycol monohexyl ether (hexyl glycol), diethylene glycol monohexyl ether (hexyl diglycol), diethylene glycol dibutyl ether, triethylene glycol monobutyl ether, methylpropylene triglycol, triethylene glycol butyl methyl ether, tetraethylene glycol, tetraethylene glycol dimethyl ether, and tripropylene glycol-n-butyl ether.

Examples of terpineols include α-terpineol, β-terpineol, γ-terpineol, and terpineol mixtures (that is, mixtures whose main component is α-terpineol and contain β-terpineol or γ-terpineol).
Other examples of the solvent include dioctyl sebacate (DOS) and liquid paraffin.

The solvent may be used alone or in combination of two or more.
The solvent preferably contains a solvent having a boiling point of 100° C. or less, and preferably contains at least one selected from the group consisting of ethanol and 2-propanol.

The content of the solvent in the flux is 60 mass % or more, preferably 65 mass % or more and 95 mass % or less, more preferably 70 mass % or more and 95 mass % or less, and even more preferably 75 mass % or more and 95 mass % or less, relative to the total amount (100 mass %) of the flux.
When the content of the solvent is within the above range, the flux can be suitably used for flow soldering.

<Compound represented by general formula (1)>
The flux according to the present embodiment contains a compound represented by the following general formula (1).

［式中、Ｒ^１は、連結基又は単結合である。Ｒ^２は、炭素数１～２のアルキル基又は水素原子である。ｍは、１以上４以下の整数である。ｎは、０以上３以下の整数である。ｍ＋ｎ≦４である。］

[In the formula, R ¹ is a linking group or a single bond. R ² is an alkyl group having 1 to 2 carbon atoms or a hydrogen atom. m is an integer of 1 to 4. n is an integer of 0 to 3. m+n≦4.]

R ¹ is a divalent linking group or a single bond. The divalent linking group is not particularly limited, but examples thereof include a divalent hydrocarbon group which may have a substituent and a divalent linking group containing a hetero atom.

When R ¹ is a divalent hydrocarbon group which may have a substituent, the hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group.
The aliphatic hydrocarbon group means a hydrocarbon group having no aromaticity. The aliphatic hydrocarbon group may be saturated or unsaturated, and is usually preferably saturated.
Examples of the aliphatic hydrocarbon group include linear or branched aliphatic hydrocarbon groups, and aliphatic hydrocarbon groups containing a ring in the structure.

The linear aliphatic hydrocarbon group preferably contains 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, even more preferably 1 to 4 carbon atoms, particularly preferably 1 to 3 carbon atoms, and most preferably 1 carbon atom.
The linear aliphatic hydrocarbon group is preferably a linear alkylene group, such as a methylene group [-CH ₂ -], an ethylene group [-(CH ₂ ) ₂ -], a trimethylene group [-(CH ₂ ) ₃ -], a tetramethylene group [-(CH ₂ ) ₄ -], a pentamethylene group [-(CH ₂ ) ₅ -], etc.

The branched aliphatic hydrocarbon group preferably has 2 to 10 carbon atoms, more preferably has 2 to 6 carbon atoms, and even more preferably has 2 to 4 carbon atoms.
The branched aliphatic hydrocarbon group is preferably a branched alkylene group, and specific examples thereof include alkylmethylene groups such as -CH( _CH3 )-, -CH( _CH2CH3 )-, -C( _CH3 ) _2- , -C(CH3 _{) ( CH2CH3} )-, -C( _{CH3 )} ( _CH2CH2CH3 )- _, and -C( _CH2CH3 ) _2- ; alkylethylene groups such as -CH( _CH3 ) _{CH2- ,} -CH( _{CH3 )} CH( _CH3 )- _{, -C(CH3 ) 2CH2- ,} -CH( _CH2CH3 ) _{CH2- , and -C} ( _CH2CH3 ) _{2 - CH2-} ; alkyltrimethylene groups such as -CH( _CH3 ) _CH2CH2CH2- , _-CH2CH ( _CH3 ) _CH2CH2- , etc.; and alkylalkylene groups such as alkyltetramethylene groups such as -CH( _CH3 ) _{CH2CH2CH2- , -CH2CH} (CH3) _CH2CH2- , etc. The alkyl group in the alkylalkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

^R2 is an alkyl group having 1 to 2 carbon atoms or a hydrogen atom, preferably a methyl group or a hydrogen atom, and more preferably a hydrogen atom.

n is an integer of 0 or more and 3 or less, and is preferably 0 or 1.
m is an integer of 1 or more and 4 or less, preferably 1 or more and 2 or less, and more preferably 1.
m and n satisfy the relational expression m+n≦4, and preferably satisfy the relational expression m+n≦2.

Examples of the compound represented by the above general formula (1) include compounds represented by the following formulas (1-1) to (1-4).

The compound represented by the following formula (1-1) is 3,4,5-trihydroxybenzoic acid. The CAS registry number of this compound is 149-91-7. In this compound, R ¹ is a single bond, R ² is a hydrogen atom, m is 1, and n is 1 in the above general formula (1).

The compound represented by the following formula (1-2) is 2,3-dihydroxybenzoic acid. The CAS registry number of this compound is 303-38-8. In this compound, in the above general formula (1), R ¹ is a single bond, R ² is a hydrogen atom, m is 1, and n is 0.

The compound represented by the following formula (1-3) is 3,4-dihydroxyphenylacetic acid. The CAS registry number of this compound is 102-32-9. In this compound, in the above general formula (1), R ¹ is a methylene group, R ² is a hydrogen atom, m is 1, and n is 0.

The compound represented by the following formula (1-4) is 3,4,5-trihydroxybenzoic acid methyl ester. The CAS registry number of this compound is 99-24-1. In this compound, in the above general formula (1), R ¹ is a single bond, R ² is a methyl group, m is 1, and n is 1.

The compound represented by the above general formula (1) may be used alone or in combination of two or more.
The compound represented by the general formula (1) is preferably one or more selected from the group consisting of the formulas (1-1), (1-2), (1-3) and (1-4), and more preferably one or more selected from the group consisting of the formulas (1-1), (1-2) and (1-3).

The content of the compound in which n is 1 in the above general formula (1) in the flux is preferably 0.03 mass % or more and 5 mass % or less, and more preferably 0.08 mass % or more and 5 mass % or less, relative to the total mass (100 mass %) of the flux.
In the solid content of the flux, the content of the compound in which n is 1 in the above general formula (1) is preferably 0.2 mass % or more and 25 mass % or less, and more preferably 0.5 mass % or more and 25 mass % or less, relative to the total amount (100 mass %) of the solid content.
When the content is within the above range, the ability to inhibit dross adhesion can be further improved.

The content of the compound in which n is 1 in the above general formula (1) in the flux is preferably 0.03 mass % or more and 5 mass % or less, more preferably 0.03 mass % or more and 2 mass % or less, and even more preferably 0.05 mass % or more and 0.5 mass % or less, relative to the total mass (100 mass %) of the flux.
In the solid content of the flux, the content of the compound in which n is 1 in the above general formula (1) is preferably 0.2 mass % or more and 25 mass % or less, more preferably 0.2 mass % or more and 12 mass % or less, and even more preferably 0.33 mass % or more and 3.2 mass % or less, relative to the total amount (100 mass %) of the solid content.
When the content is within the above range, the solder wetting speed can be more easily increased.

The content of the compound in which n is 1 in the above general formula (1) in the flux is preferably 0.03 mass % or more and 5 mass % or less, more preferably 0.03 mass % or more and 2 mass % or less, and even more preferably 0.05 mass % or more and 1 mass % or less, relative to the total mass (100 mass %) of the flux.
In the solid content of the flux, the content of the compound in which n is 1 in the above general formula (1) is preferably 0.2 mass % or more and 25 mass % or less, more preferably 0.2 mass % or more and 12 mass % or less, and even more preferably 0.2 mass % or more and 6.2 mass % or less, relative to the total amount (100 mass %) of the solid content.
When the content is within the above range, the solder wettability can be more easily improved.

The content of the compound in which n is 1 in the general formula (1) in the flux is preferably 0.03 mass % or more and 5 mass % or less, more preferably 0.03 mass % or more and 2 mass % or less, and even more preferably 0.03 mass % or more and 1 mass % or less, relative to the total mass (100 mass %) of the flux.
In the solid content of the flux, the content of the compound in which n is 1 in the above general formula (1) is preferably 0.2 mass % or more and 25 mass % or less, more preferably 0.2 mass % or more and 12 mass % or less, and even more preferably 0.2 mass % or more and 6.2 mass % or less, relative to the total amount (100 mass %) of the solid content.
When the content is within the above range, the insulation resistance can be more easily increased.

The content of the compound in which n is 1 in the general formula (1) in the flux is preferably 0.03 mass % or more and 5 mass % or less, more preferably 0.03 mass % or more and 2 mass % or less, and even more preferably 0.08 mass % or more and 0.5 mass % or less, relative to the total mass (100 mass %) of the flux.
In the solid content of the flux, the content of the compound in which n is 1 in the above general formula (1) is preferably 0.2 mass % or more and 25 mass % or less, more preferably 0.2 mass % or more and 12 mass % or less, and even more preferably 0.5 mass % or more and 3.2 mass % or less, relative to the total amount (100 mass %) of the solid content.
When the content is within the above range, it becomes easier to simultaneously increase the ability to inhibit dross adhesion, the solder wetting speed, the solder wetting power, and the insulation resistance.

The content of the compound in which n is 0 in the general formula (1) in the flux is preferably 0.2 mass % or more and 5 mass % or less, and more preferably 2 mass % or more and 5 mass % or less, relative to the total mass (100 mass %) of the flux.
In the solid content of the flux, the content of the compound in which n is 0 in the above general formula (1) is preferably 1.2 mass % or more and 25 mass % or less, and more preferably 11 mass % or more and 25 mass % or less, relative to the total amount (100 mass %) of the solid content.
When the content is within the above range, the ability to inhibit dross adhesion can be further improved.

The content of the compound in which n is 0 in the above general formula (1) in the flux is preferably 0.2 mass % or more and 5 mass % or less, and more preferably 1 mass % or more and 5 mass % or less, relative to the total mass (100 mass %) of the flux.
In the solid content of the flux, the content of the compound in which n is 0 in the above general formula (1) is preferably 1.2 mass % or more and 25 mass % or less, and more preferably 6.1 mass % or more and 25 mass % or less, relative to the total amount (100 mass %) of the solid content.
When the content is within the above range, the solder wetting speed can be more easily increased.

The content of the compound in which n is 0 in the general formula (1) in the flux is preferably 0.2 mass % or more and 5 mass % or less, more preferably 0.2 mass % or more and 2 mass % or less, and even more preferably 0.5 mass % or more and 2 mass % or less, relative to the total mass (100 mass %) of the flux.
In the solid content of the flux, the content of the compound in which n is 0 in the above general formula (1) is preferably 1.2 mass % or more and 25 mass % or less, more preferably 1.2 mass % or more and 12 mass % or less, and even more preferably 3.1 mass % or more and 12 mass % or less, relative to the total amount (100 mass %) of the solid content.
When the content is within the above range, the solder wettability can be more easily improved.

The content of the compound in which n is 0 in the general formula (1) in the flux is preferably 0.2 mass % or more and 5 mass % or less, more preferably 0.2 mass % or more and 3 mass % or less, even more preferably 0.2 mass % or more and 2 mass % or less, and particularly preferably 0.5 mass % or more and 2 mass % or less, relative to the total mass (100 mass %) of the flux.
In the solid content of the flux, the content of the compound in which n is 0 in the above general formula (1) is preferably 1.2 mass % or more and 25 mass % or less, more preferably 1.2 mass % or more and 16.5 mass % or less, even more preferably 1.2 mass % or more and 12 mass % or less, and particularly preferably 3.1 mass % or more and 12 mass % or less, relative to the total amount (100 mass %) of the solid content.
When the content is within the above range, the insulation resistance can be more easily increased.

The content of the compound in the flux in which n is 0 in the general formula (1) is preferably 0.2% by mass or more and 5% by mass or less, more preferably 0.2% by mass or more and 3% by mass or less, and even more preferably 0.5% by mass or more and 3% by mass or less, relative to the total mass (100% by mass) of the flux. Within these ranges, the content is preferably more than 1% by mass and less than 3% by mass, more preferably 1.5% by mass or more and 2.5% by mass or less, and even more preferably 1.8% by mass or more and 2.2% by mass or less.
In the solid content of the flux, the content of the compound in which n is 0 in the general formula (1) is preferably 1.2% by mass or more and 25% by mass or less, more preferably 1.2% by mass or more and 16.5% by mass or less, and even more preferably 3.1% by mass or more and 16.5% by mass or less, relative to the total amount (100% by mass) of the solid content. Within these ranges, the content is preferably 6.5% by mass or more and 16% by mass or less, more preferably 9% by mass or more and 14% by mass or less, and even more preferably 10% by mass or more and 13% by mass or less.
When the content is within the above range, it becomes easier to simultaneously increase the ability to inhibit dross adhesion, the solder wetting speed, the solder wetting power, and the insulation resistance.

The flux according to the present embodiment may contain other components as necessary in addition to the rosin, the compound represented by the general formula (1), and the solvent.
Examples of other components include other activators other than the compound represented by formula (1), thixotropic agents, resin components other than rosin, surfactants, metal deactivators, antioxidants, silane coupling agents, colorants, etc.

Other activators include organic acids other than the compound represented by the above general formula (1) (other organic acids), amines, halogen compounds, organic phosphorus compounds, etc.

Other organic acids
Other organic acids include, for example, carboxylic acids and organic sulfonic acids. Carboxylic acids include, for example, aliphatic carboxylic acids and aromatic carboxylic acids. Aliphatic carboxylic acids include, for example, aliphatic monocarboxylic acids and aliphatic dicarboxylic acids.

Examples of aliphatic monocarboxylic acids include caproic acid, enanthic acid, caprylic acid, pelargonic acid, isopelargonic acid, capric acid, caproleic acid, lauric acid (dodecanoic acid), undecanoic acid, Linderic acid, tridecanoic acid, myristoleic acid, pentadecanoic acid, isopalmitic acid, palmitoleic acid, hiragonic acid, hydnocarpic acid, margaric acid, isostearic acid, elaidic acid, petroselinic acid, moroctic acid, eleostearic acid, talic acid, vaccenic acid, riminoleic acid, vernolic acid, sterculic acid, nonadecanoic acid, eicosanoic acid, stearic acid, 12-hydroxystearic acid, oleic acid, linoleic acid, linolenic acid, myristic acid, glycolic acid, and thioglycolic acid.

Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, eicosanedioic acid, citraconic acid, diglycolic acid, tartaric acid, and 2,4-diethylglutaric acid.
Examples of aromatic carboxylic acids include aromatic monocarboxylic acids such as benzoic acid, 3-hydroxybenzoic acid, salicylic acid, picolinic acid, p-anisic acid, m-anisic acid, o-anisic acid, parahydroxyphenylacetic acid, and 2-quinolinecarboxylic acid, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, phenylsuccinic acid, dipicolinic acid, and dibutylaniline diglycolic acid, picolinic acid, dipicolinic acid, and 3-hydroxypicolinic acid.

An example of the tricarboxylic acid is citric acid.
Examples of the carboxylic acid include tris(2-carboxyethyl) isocyanurate and 1,3-cyclohexanedicarboxylic acid.

Other organic acids include hydroxycarboxylic acids.
Examples of hydroxycarboxylic acids include 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butanoic acid, citric acid, isocitric acid, malic acid, and tartaric acid.

The carboxylic acid may also be a polybasic carboxylic acid.
Examples of polybasic carboxylic acids include dimer acid, trimer acid, hydrogenated dimer acid obtained by adding hydrogen to dimer acid, and hydrogenated trimer acid obtained by adding hydrogen to trimer acid.

Examples of organic sulfonic acids include aliphatic sulfonic acids and aromatic sulfonic acids. Examples of aliphatic sulfonic acids include alkane sulfonic acids and alkanol sulfonic acids.

The other organic acids may be used alone or in combination of two or more.
The other organic acid preferably includes a carboxylic acid, and more preferably includes one or more selected from a monocarboxylic acid and a dicarboxylic acid.
The monocarboxylic acid preferably includes at least one selected from the group consisting of aliphatic monocarboxylic acids and aromatic monocarboxylic acids.
The dicarboxylic acid preferably includes an aliphatic dicarboxylic acid.

The aliphatic monocarboxylic acid is preferably one or more selected from the group consisting of caproic acid, enanthic acid, caprylic acid, pelargonic acid, isopelargonic acid, capric acid, caproleic acid, lauric acid (dodecanoic acid), undecanoic acid, Linderic acid, tridecanoic acid, myristoleic acid, pentadecanoic acid, isopalmitic acid, palmitoleic acid, hiragonic acid, hydnocarpic acid, margaric acid, isostearic acid, elaidic acid, petroselinic acid, moroctic acid, eleostearic acid, talilic acid, vaccenic acid, riminoleic acid, vernolic acid, sterculic acid, nonadecanoic acid, eicosanoic acid, and stearic acid, more preferably one or more selected from the group consisting of capric acid, lauric acid (dodecanoic acid), myristic acid, palmitic acid, margaric acid, and stearic acid, and even more preferably palmitic acid.

The aromatic monocarboxylic acid is preferably a compound represented by the general formula (a1), more preferably one or more selected from the group consisting of picolinic acid, dipicolinic acid, and 3-hydroxypicolinic acid, and even more preferably picolinic acid.

The aliphatic dicarboxylic acid is more preferably one or more selected from the group consisting of succinic acid, suberic acid, citraconic acid, adipic acid, phthalic acid, glutaric acid, malonic acid, and maleic acid, and even more preferably one or more selected from the group consisting of succinic acid and adipic acid.
By including these aliphatic dicarboxylic acids in the flux, when flow soldering is performed using a solder alloy containing Sn and Bi, the wetting speed is likely to be increased at the melting temperature (i.e., 170 to 220° C.).

The total content of the organic acids in the flux is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.2% by mass or more and 10% by mass or less, relative to the total mass (100% by mass) of the flux.
The content of the monocarboxylic acid is preferably 0.1% by mass or more and 2% by mass or less, and more preferably 0.2% by mass or more and 1% by mass or less, relative to the total mass (100% by mass) of the flux.
The content of the dicarboxylic acid is preferably 0.1 mass % or more and 1 mass % or less, and more preferably 0.2 mass % or more and 0.5 mass % or less, relative to the total mass (100 mass %) of the flux.
In the case where the flux of the present embodiment does not contain a halogen compound described later, the content of the dicarboxylic acid is preferably 1 mass % or more and 10 mass % or less, and more preferably 1 mass % or more and 5 mass % or less, relative to the total mass (100 mass %) of the flux.

In the solid content of the flux, the total content of the organic acid is preferably 1 mass % or more and 60 mass % or less, and more preferably 2 mass % or more and 50 mass % or less, relative to the total amount (100 mass %) of the solid content.
The content of the monocarboxylic acid is preferably from 0.5% by mass to 10% by mass, and more preferably from 1% by mass to 5% by mass, relative to the total amount (100% by mass) of the solid contents.
The content of the dicarboxylic acid is preferably from 0.5% by mass to 5% by mass, and more preferably from 1% by mass to 2.5% by mass, relative to the total amount (100% by mass) of the solid contents.
In the case where the flux of the present embodiment does not contain a halogen compound described later, the content of the dicarboxylic acid is preferably 5 mass % or more and 50 mass % or less, and more preferably 10 mass % or more and 25 mass % or less, relative to the total amount (100 mass %) of the solid content.
When the flux of the present embodiment does not contain a halogen compound described later, the content of the aromatic monocarboxylic acid is preferably 0.1 mass % or more and 20 mass % or less, and more preferably 0.5 mass % or more and 5 mass % or less, relative to the total amount (100 mass %) of the solid content.

In the flux, the mass ratio of the compound in which n is 1 in the general formula (1) to the organic acid other than the compound represented by the general formula (1), that is, the mass ratio of the compound in which n is 1 in the general formula (1)/the organic acid other than the compound represented by the general formula (1), that is, the ratio of the total mass of the compound in which n is 1 in the general formula (1) to the total mass of the organic acid other than the compound represented by the general formula (1), is preferably 0.05 to 10, more preferably 0.1 to 10, and even more preferably 0.13 to 8.34.
When the mass ratio of the compound in which n is 1 in the above general formula (1) to the organic acid other than the compound represented by the above general formula (1) is within the above range, the ability to inhibit dross adhesion is more easily improved.

In the flux, the mass ratio of the compound in which n is 1 in the general formula (1) to the organic acid other than the compound represented by the general formula (1) is preferably 0.05 or more and 10 or less, more preferably 0.05 or more and 4.0 or less, even more preferably 0.05 or more and 3.34 or less, particularly preferably 0.08 or more and 1.0 or less, and most preferably 0.08 or more and 0.84 or less.
When the mass ratio of the compound in which n is 1 in the above general formula (1)/the organic acid other than the compound represented by the above general formula (1) is within the above range, the solder wetting rate can be more easily increased.

In the flux, the mass ratio of the compound in which n is 1 in the above general formula (1) to the organic acid other than the compound represented by the above general formula (1) is preferably 0.05 or more and 10 or less, more preferably 0.05 or more and 4.0 or less, even more preferably 0.05 or more and 2 or less, and particularly preferably 0.05 or more and 1.67 or less.
When the mass ratio of the compound in which n is 1 in the above general formula (1) to the organic acid other than the compound represented by the above general formula (1) is within the above range, the solder wetting ability can be more easily improved.

In the flux, the mass ratio of the compound in which n is 1 in the general formula (1) to the organic acid other than the compound represented by the general formula (1) is preferably 0.05 or more and 10 or less, more preferably 0.05 or more and 4.0 or less, even more preferably 0.05 or more and 3.34 or less, particularly preferably 0.10 or more and 1.0 or less, and most preferably 0.13 or more and 0.84 or less.
When the mass ratio of the compound in which n is 1 in the above general formula (1)/the organic acid other than the compound represented by the above general formula (1) is within the above range, it becomes easier to simultaneously increase the dross adhesion suppression ability, solder wetting speed, solder wetting power, and insulation resistance.

In the flux, the mass ratio of the compound in which n is 0 in the above general formula (1) to the organic acid other than the compound represented by the above general formula (1) is preferably 0.25 or more and 10 or less, more preferably 3.0 or more and 10 or less, and even more preferably 3.33 or more and 8.34 or less.
When the mass ratio of the compound in which n is 0 in the above general formula (1) to the organic acid other than the compound represented by the above general formula (1) is within the above range, the ability to inhibit dross adhesion is more easily improved.

In the flux, the mass ratio of the compound in which n is 0 in the general formula (1) to the organic acid other than the compound represented by the general formula (1) is preferably 0.25 or more and 10 or less, more preferably 1.5 or more and 10 or less, and even more preferably 1.66 or more and 8.34 or less.
When the mass ratio of the compound in which n is 0 in the above general formula (1)/the organic acid other than the compound represented by the above general formula (1) is within the above range, the solder wetting rate can be more easily increased.

In the flux, the mass ratio of the compound in which n is 0 in the above general formula (1) to the organic acid other than the compound represented by the above general formula (1) is preferably 0.25 or more and 10 or less, more preferably 0.5 or more and 4 or less, and even more preferably 0.83 or more and 3.34 or less.
When the mass ratio of the compound in which n is 0 in the above general formula (1) to the organic acid other than the compound represented by the above general formula (1) is within the above range, the solder wetting ability can be more easily improved.

In the flux, the mass ratio of the compound in which n is 0 in the general formula (1) to the organic acid other than the compound represented by the general formula (1) is preferably 0.25 or more and 10 or less, more preferably 0.25 or more and 5 or less, even more preferably 0.25 or more and 4 or less, particularly preferably 0.33 or more and 3.34 or less, and most preferably 0.83 or more and 3.34 or less.
When the mass ratio of the compound in which n is 0 in the above general formula (1)/the organic acid other than the compound represented by the above general formula (1) is within the above range, the insulation resistance is more easily increased.

In the flux, the mass ratio of the compound in which n is 0 in the above general formula (1) to the organic acid other than the compound represented by the above general formula (1) is preferably 0.25 or more and 10 or less, more preferably 1.67 or more and less than 5, more preferably 2 or more and 4 or less, and even more preferably 2.5 or more and 4 or less.
When the mass ratio of the compound in which n is 0 in the above general formula (1)/the organic acid other than the compound represented by the above general formula (1) is within the above range, it becomes easier to simultaneously increase the dross adhesion suppression ability, solder wetting speed, solder wetting power, and insulation resistance.

Amine
Examples of the amine include rosin amine, azoles, guanidines, alkylamines, aromatic amines, amino alcohols, amine polyoxyalkylene adducts, etc. Examples of the rosin amine include those exemplified in <Rosin>.

Examples of azoles include 2-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1 -cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine imidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5- Hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, 2,4-diamino-6-vinyl-s-triazine, 2,4-diamino-6-vinyl-s-triazine isocyanuric acid adduct, 2,4-diamino-6-methacryloyloxyethyl-s-triazine, ethylenediamine benzimidazole, 1,2,4-triazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-phenyl)benzo ... 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-tert-octylphenol], 6-(2-benzotriazolyl)-4-tert-octylphenol ethyl-6'-tert-butyl-4'-methyl-2,2'-methylenebisphenol, 1,2,3-benzotriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole, carboxybenzotriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole, 2,2'-[[(methyl-1H-benzotriazol-1-yl)methyl]imino]bisethanol, 1-(1',2'-dicarboxyethyl)benzotriazole, 1-(2,3-dicarboxypropyl)benzotriazole, 1-[(2-ethylhexylamino)methyl]benzotriazole, 2,6-bis[(1H-benzotriazol-1-yl)methyl]-4-methylphenol, 5-methylbenzotriazole, 5-phenyltetrazole, 3-(N-salicyloyl)amino-1,2,4-triazole, etc.

Examples of guanidines include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, 1,3-di-o-cumenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine.

Examples of alkylamines include ethylamine, triethylamine, ethylenediamine, triethylenetetramine, cyclohexylamine, hexadecylamine, and stearylamine.

Examples of aromatic amines include aniline, N-methylaniline, diphenylamine, N-isopropylaniline, p-isopropylaniline, metaxylenediamine, tolylenediamine, paraxylenediamine, phenylenediamine, 4,4-diaminodiphenylmethane, and pyrimidine-2,4,5,6-tetraamine.

Examples of amino alcohols include alkanolamines such as 1-amino-2-propanol and N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine.

Examples of the amine polyoxyalkylene adducts include terminal diamine polyalkylene glycols, aliphatic amine polyoxyalkylene adducts, aromatic amine polyoxyalkylene adducts, and polyvalent amine polyoxyalkylene adducts.
Examples of the alkylene oxide added to the amine polyoxyalkylene adduct include ethylene oxide, propylene oxide, butylene oxide, and the like.

The diamine-terminated polyalkylene glycol is a compound in which both terminals of a polyalkylene glycol are aminated.
Examples of diamine-terminated polyalkylene glycols include diamine-terminated polyethylene glycols, diamine-terminated polypropylene glycols, and diamine-terminated polyethylene glycol-polypropylene glycol copolymers.
Examples of diamine-terminated polyethylene glycol-polypropylene glycol copolymers include polyethylene glycol-polypropylene glycol copolymer bis(2-aminopropyl) ether and polyethylene glycol-polypropylene glycol copolymer bis(2-aminoethyl) ether.

Aliphatic amine polyoxyalkylene adducts, aromatic amine polyoxyalkylene adducts, and polyvalent amine polyoxyalkylene adducts are compounds in which a polyoxyalkylene group is bonded to the nitrogen atom of an amine. Examples of the amine include ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, hexamethylenediamine, diethylenetriamine, laurylamine, stearylamine, oleylamine, beef tallow amine, hardened beef tallow amine, beef tallow propyldiamine, metaxylenediamine, tolylenediamine, paraxylenediamine, phenylenediamine, isophoronediamine, 1,10-decanediamine, 1,12-dodecanediamine, 4,4-diaminodicyclohexylmethane, 4,4-diaminodiphenylmethane, butane-1,1,4,4-tetraamine, and pyrimidine-2,4,5,6-tetraamine.

The amines may be used alone or in combination of two or more.
The amine is preferably an amino alcohol.
The content of the amine in the flux is preferably 0.05% by mass or more and 1% by mass or less, and more preferably 0.1% by mass or more and 0.5% by mass or less, relative to the total mass (100% by mass) of the flux.
The content of the amine in the solid content of the flux is preferably 0.2 mass % or more and 10 mass % or less, and more preferably 0.5 mass % or more and 5 mass % or less, relative to the total amount (100 mass %) of the solid content.

<Halogen compounds>
Examples of the halogen compound include amine hydrohalides and organic halogen compounds other than amine hydrohalides.
An amine hydrohalide is a compound obtained by reacting an amine with a hydrogen halide.
The amines herein include those mentioned above in the section "Amines."

More specifically, examples of amine hydrohalides include cyclohexylamine hydrobromide, hexadecylamine hydrobromide, stearylamine hydrobromide, ethylamine hydrobromide, diphenylguanidine hydrobromide, ethylamine hydrochloride, stearylamine hydrochloride, diethylaniline hydrochloride, diethanolamine hydrochloride, 2-ethylhexylamine hydrobromide, pyridine hydrobromide, isopropylamine hydrobromide, diethylamine hydrobromide, dimethyl ... amine hydrochloride, rosinamine hydrobromide, 2-ethylhexylamine hydrochloride, isopropylamine hydrochloride, cyclohexylamine hydrochloride, 2-pipecoline hydrobromide, 1,3-diphenylguanidine hydrochloride, dimethylbenzylamine hydrochloride, hydrazine hydrate hydrobromide, dimethylcyclohexylamine hydrochloride, triphenylamine hydrobromide, diethylaniline hydrobromide, 2-diethylaminoethanol hydrobromide, 2-diethylaminoethanol hydrochloride, ammonium chloride, diallylamine hydrochloride, diarylamine hydrochloride amidine hydrobromide, diethylamine hydrochloride, triethylamine hydrobromide, triethylamine hydrochloride, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine monohydrobromide, hydrazine dihydrobromide, pyridine hydrochloride, aniline hydrobromide, butylamine hydrochloride, hexylamine hydrochloride, n-octylamine hydrochloride, dodecylamine hydrochloride, dimethylcyclohexylamine hydrobromide, ethylenediamine dihydrobromide, rosinamine hydrobromide, 2-phenylimidazole hydrobromide, 4-benzylpyr ... Examples include lysine hydrobromide, L-glutamic acid hydrochloride, N-methylmorpholine hydrochloride, betaine hydrochloride, 2-pipecoline hydroiodide, cyclohexylamine hydroiodide, 1,3-diphenylguanidine hydrofluoride, diethylamine hydrofluoride, 2-ethylhexylamine hydrofluoride, cyclohexylamine hydrofluoride, ethylamine hydrofluoride, rosinamine hydrofluoride, cyclohexylamine tetrafluoroborate, and dicyclohexylamine tetrafluoroborate.

Examples of halogen compounds other than amine hydrohalides include salts obtained by reacting amines with tetrafluoroboric acid (HBF ₄ ) and complexes obtained by reacting amines with boron trifluoride (BF ₃ ). Examples of the complexes include boron trifluoride piperidine.

Examples of halogen compounds other than amine hydrohalides include halogenated aliphatic compounds. A halogenated aliphatic hydrocarbon group refers to an aliphatic hydrocarbon group in which some or all of the hydrogen atoms constituting the aliphatic hydrocarbon group have been substituted with halogen atoms.
Examples of the halogenated aliphatic compounds include halogenated aliphatic alcohols and halogenated heterocyclic compounds.

Examples of halogenated aliphatic alcohols include 1-bromo-2-propanol, 3-bromo-1-propanol, 3-bromo-1,2-propanediol, 1-bromo-2-butanol, 1,3-dibromo-2-propanol, 2,3-dibromo-1-propanol, 1,4-dibromo-2-butanol, trans-2,3-dibromo-2-butene-1,4-diol, etc.

Examples of halogenated heterocyclic compounds include compounds represented by the following general formula (h1):

R ^h11 - (R ^h12 ) _n (h1)
[In the formula, R ^h11 represents an n-valent heterocyclic group. R ^h12 represents a halogenated aliphatic hydrocarbon group.]

The heterocycle of the n-valent heterocyclic group in R ^h11 may be a ring structure in which a portion of the carbon atoms constituting an aliphatic hydrocarbon or aromatic hydrocarbon ring is substituted with a heteroatom. Examples of the heteroatom in the heterocycle include an oxygen atom, a sulfur atom, and a nitrogen atom. The heterocycle is preferably a 3- to 10-membered ring, and more preferably a 5- to 7-membered ring. Examples of the heterocycle include an isocyanurate ring.
The halogenated aliphatic hydrocarbon group for R ^h12 preferably has 1 to 10 carbon atoms, more preferably has 2 to 6 carbon atoms, and still more preferably has 3 to 5 carbon atoms. Furthermore, R ^h12 is preferably a brominated aliphatic hydrocarbon group or a chlorinated aliphatic hydrocarbon group, more preferably a brominated aliphatic hydrocarbon group, and still more preferably a brominated saturated aliphatic hydrocarbon group.
Examples of halogenated heterocyclic compounds include tris-(2,3-dibromopropyl)isocyanurate.

Examples of halogen compounds other than amine hydrohalides include iodinated carboxyl compounds such as 2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, and 5-iodoanthranilic acid; chlorinated carboxyl compounds such as 2-chlorobenzoic acid and 3-chloropropionic acid; and brominated carboxyl compounds such as 2,3-dibromopropionic acid, 2,3-dibromosuccinic acid, and 2-bromobenzoic acid.

Examples of halogen compounds other than amine hydrohalides include organic chloro compounds. Examples of organic chloro compounds include chloroalkanes, chlorinated fatty acid esters, chlorendic acid, and chlorendic anhydride.

The halogen compounds may be used alone or in combination of two or more.
The halogen compound preferably includes at least one selected from the group consisting of a halogenated salt of a primary amine, a halogenated salt of a secondary amine, a halogenated aliphatic alcohol, and an organic chloro compound.

Examples of halogenated salts of primary amines include compounds represented by the following general formula (h2):

R ^h21 -NH ₂・R ^h22 ...(h2)
[In the formula, R ^h21 represents a hydrocarbon group which may have a substituent. R ^h22 represents HX, _BX3 or _HBX4 . X represents a halogen atom.]

In general formula (h2), examples of the hydrocarbon group of R ^h21 include a hydrocarbon group which may have a substituent. The hydrocarbon group which may have a substituent may be linear, branched, or cyclic. The hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group.

When the hydrocarbon group, which may have a substituent, is a linear or branched hydrocarbon group, the number of carbon atoms in the hydrocarbon group is preferably 1 to 10, more preferably 1 to 6, and even more preferably 2 to 4.

When the hydrocarbon group is linear or branched, examples of the hydrocarbon group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, tert-pentyl, neopentyl, n-hexyl, isohexyl, sec-hexyl, tert-hexyl, and neohexyl groups.

When the hydrocarbon group, which may have a substituent, is a cyclic hydrocarbon group, the number of carbon atoms in the hydrocarbon group is preferably 3 to 20, more preferably 4 to 12, and even more preferably 4 to 8.

When the hydrocarbon group is cyclic, examples of the hydrocarbon group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and a cycloundecyl group.

Examples of the substituents that the hydrocarbon group may have include halogen atoms, hydroxyl groups, and carboxy groups.

R ^h22 represents HX, _BX3 or _HBX4 . X represents a halogen atom.
Examples of X include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Preferably, _BX3 is boron trifluoride ( _BF3 ).
Preferably, _HBX4 is tetrafluoroboric acid ( _HBF4 ).
R ^h22 is preferably HX.

Examples of the compound represented by the above general formula (h2) include ethylamine hydrofluoride, ethylamine hydrochloride, ethylamine hydrobromide, cyclohexylamine tetrafluoroborate, etc.

Examples of halogenated salts of secondary amines include compounds represented by the following general formula (h3):

R ^h31a -NH-R ^h31b・R ^h32 ...(h3)
[In the formula, R ^h31a and R ^h31b each represent a hydrocarbon group which may have a substituent. R ^h32 represents HX, _BX3 or _HBX4 . X represents a halogen atom.]

Examples of the hydrocarbon group of R ^h31a and R ^h31b include those described above for R ^h21 . R ^h31a and R ^h31b may be the same or different.
Examples of R ^h32 include those mentioned above for R ^h22 .

Examples of the compound represented by the above general formula (h3) include diethylamine hydrofluoride, diethylamine hydrochloride, diethylamine hydrobromide, dimethylamine hydrofluoride, dimethylamine hydrochloride, and dimethylamine hydrobromide.

The halogen compounds may be used alone or in combination of two or more.
The total content of halogen compounds in the flux is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 5% by mass or less, relative to the total mass (100% by mass) of the flux.
The total content of the halogen compounds in the solid content of the flux is preferably 3 mass % or more and 30 mass % or less, and more preferably 5 mass % or more and 20 mass % or less, relative to the total amount (100 mass %) of the solid content.
Alternatively, from the viewpoint of reducing the burden on the environment, it is preferable that the flux of the present embodiment does not contain a halogen compound.

<Organophosphorus compounds>
Examples of the organic phosphorus compound include acid phosphate esters, acid phosphonate esters, and acid phosphinate esters.
Examples of acidic phosphate esters include methyl acid phosphate, ethyl acid phosphate, isopropyl acid phosphate, monobutyl acid phosphate, butyl acid phosphate, dibutyl acid phosphate, butoxyethyl acid phosphate, 2-ethylhexyl acid phosphate, bis(2-ethylhexyl)phosphate, monoisodecyl acid phosphate, diisodecyl acid phosphate, lauryl acid phosphate, isotridecyl acid phosphate, stearyl acid phosphate, oleyl acid phosphate, beef tallow phosphate, coconut oil phosphate, isostearyl acid phosphate, alkyl acid phosphate, tetracosyl acid phosphate, ethylene glycol acid phosphate, 2-hydroxyethyl methacrylate acid phosphate, and dibutyl pyrophosphate acid phosphate.
Examples of acidic phosphonates include alkyl phosphonates such as 2-ethylhexyl phosphonate, n-octyl phosphonate, n-decyl phosphonate, n-butyl phosphonate, and isodecyl phosphonate; and diethyl (p-methylbenzyl) phosphonate.
Examples of the acidic phosphinic acid ester include phenyl-substituted phosphinic acids, etc. Examples of the phenyl-substituted phosphinic acids include phenylphosphinic acid and diphenylphosphinic acid.

The organic phosphorus compounds may be used alone or in combination of two or more.
The organophosphorus compound preferably comprises an acid phosphonate, more preferably 2-ethylhexyl (2-ethylhexyl) phosphonate.
The total content of the organic phosphorus compounds in the flux is preferably 0.1 mass % or more and 2.0 mass % or less, and more preferably 0.3 mass % or more and 1.0 mass % or less, relative to the total amount (100 mass %) of the flux.
The total content of the organic phosphorus compounds in the solid content of the flux is preferably 0.5 mass % or more and 15 mass % or less, and more preferably 1.5 mass % or more and 8 mass % or less, relative to the total amount of the solid content (100 mass %).

<Thixotropic agent>
Examples of the thixotropic agent include ester-based thixotropic agents, amide-based thixotropic agents, and sorbitol-based thixotropic agents.

Examples of ester-based thixotropic agents include ester compounds, specifically hydrogenated castor oil, ethyl myristate, etc.

Examples of the amide-based thixotropic agent include monoamides, bisamides, and polyamides.
Examples of monoamides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, saturated fatty acid amide, oleic acid amide, erucic acid amide, unsaturated fatty acid amide, 4-methylbenzamide (p-toluamide), p-toluenemethane amide, aromatic amide, hexamethylene hydroxystearic acid amide, substituted amides, methylol stearic acid amide, methylol amide, and fatty acid ester amide.
Examples of bisamides include ethylene bis fatty acid (fatty acid carbon number: C6-24) amides, ethylene bis hydroxy fatty acid (fatty acid carbon number: C6-24) amides, hexamethylene bis fatty acid (fatty acid carbon number: C6-24) amides, hexamethylene bis hydroxy fatty acid (fatty acid carbon number: C6-24) amides, aromatic bisamides, etc. Examples of fatty acids that are raw materials for the bisamides include stearic acid (carbon number: C18), oleic acid (carbon number: C18), lauric acid (carbon number: C12), etc.
Examples of polyamides include saturated fatty acid polyamides, unsaturated fatty acid polyamides, aromatic polyamides, 1,2,3-propanetricarboxylic acid tris(2-methylcyclohexylamide), cyclic amide oligomers, and non-cyclic amide oligomers.

The cyclic amide oligomer may be an amide oligomer obtained by cyclic polycondensation of a dicarboxylic acid and a diamine, an amide oligomer obtained by cyclic polycondensation of a tricarboxylic acid and a diamine, an amide oligomer obtained by cyclic polycondensation of a dicarboxylic acid and a triamine, an amide oligomer obtained by cyclic polycondensation of a tricarboxylic acid and a triamine, an amide oligomer obtained by cyclic polycondensation of a dicarboxylic acid, a tricarboxylic acid, and a diamine, an amide oligomer obtained by cyclic polycondensation of a dicarboxylic acid, a diamine, and a triamine, an amide oligomer obtained by cyclic polycondensation of a tricarboxylic acid, a diamine, and a triamine, an amide oligomer obtained by cyclic polycondensation of a tricarboxylic acid, a diamine, and a triamine, an amide oligomer obtained by cyclic polycondensation of a dicarboxylic acid, ... and an amide oligomer obtained by cyclic polycondensation of a dicarboxylic acid, a tricarboxylic acid, a diamine, and a triamine.

The non-cyclic amide oligomer may be an amide oligomer in which a monocarboxylic acid and a diamine and/or a triamine are non-cyclically polycondensed, or an amide oligomer in which a dicarboxylic acid and/or a tricarboxylic acid and a monoamine are non-cyclically polycondensed. In the case of an amide oligomer containing a monocarboxylic acid or a monoamine, the monocarboxylic acid or the monoamine functions as a terminal molecule, resulting in a non-cyclic amide oligomer with a reduced molecular weight. In the case of an amide compound in which a dicarboxylic acid and/or a tricarboxylic acid and a diamine and/or a triamine are non-cyclically polycondensed, the non-cyclic amide oligomer becomes an non-cyclic polymeric amide polymer. In addition, the non-cyclic amide oligomer may also be an amide oligomer in which a monocarboxylic acid and a monoamine are non-cyclically condensed.

Examples of sorbitol-based thixotropic agents include dibenzylidene-D-sorbitol, bis(4-methylbenzylidene)-D-sorbitol, (D-)sorbitol, monobenzylidene (-D-) sorbitol, mono(4-methylbenzylidene)-(D-)sorbitol, etc.

The flux according to this embodiment may not contain a thixotropic agent, or may contain a thixotropic agent.
When the flux according to the present embodiment contains a thixotropic agent, the thixotropic agent may be used alone or in combination of two or more kinds.

<Resin components other than rosin (other resin components)>
Examples of resin components other than rosin-based resins include terpene resins, modified terpene resins, terpene phenol resins, modified terpene phenol resins, styrene resins, modified styrene resins, xylene resins, modified xylene resins, acrylic resins, polyethylene resins, acrylic-polyethylene copolymer resins, and epoxy resins.
Examples of modified terpene resins include aromatic modified terpene resins, hydrogenated terpene resins, and hydrogenated aromatic modified terpene resins. Examples of modified terpene phenol resins include hydrogenated terpene phenol resins. Examples of modified styrene resins include styrene acrylic resins and styrene maleic acid resins. Examples of modified xylene resins include phenol modified xylene resins, alkylphenol modified xylene resins, phenol modified resol type xylene resins, polyol modified xylene resins, and polyoxyethylene added xylene resins.
When the flux according to the present embodiment contains other resin components, the other resin components may be used alone or in combination of two or more.

<Surfactants>
The surfactant may be, for example, a nonionic surfactant.
Examples of nonionic surfactants include polyoxyalkylene adducts.
Examples of the alkylene oxide from which the polyoxyalkylene adduct is derived include ethylene oxide, propylene oxide, butylene oxide, and the like.
Examples of the polyoxyalkylene adducts include polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol copolymer, ethylene oxide-resorcinol copolymer, polyoxyalkylene acetylene glycols, polyoxyalkylene glyceryl ether, polyoxyalkylene alkyl ether, polyoxyalkylene ester, and polyoxyalkylene alkylamide.
Alternatively, the nonionic surfactant may be a polyoxyalkylene adduct of an alcohol, for example, an aliphatic alcohol, an aromatic alcohol, or a polyhydric alcohol.
The surfactant is preferably a nonionic surfactant, more preferably a polyoxyalkylene adduct, further preferably one or more selected from the group consisting of polyethylene glycol, polypropylene glycol, and polyethylene glycol-polypropylene glycol copolymer, and particularly preferably polyethylene glycol.
When a polyoxyalkylene adduct is used as the surfactant, the weight average molecular weight of the polyoxyalkylene adduct is preferably from 100 to 4,000, more preferably from 150 to 2,000, and even more preferably from 150 to 1,200.

The surfactant may be used alone or in combination of two or more kinds.
The content of the surfactant in the flux is preferably 0.2 mass % or more and 5 mass % or less, and more preferably 0.5 mass % or more and 3 mass % or less, relative to the total mass (100 mass %) of the flux.
The total content of the surfactant in the solid content of the flux is preferably 1 mass % or more and 20 mass % or less, and more preferably 2 mass % or more and 10 mass % or less, relative to the total amount of the solid content (100 mass %).

<Metal deactivator>
Examples of metal deactivators include hindered phenol compounds and nitrogen compounds.
The term "metal deactivator" as used herein refers to a compound that has the ability to prevent metals from deteriorating due to contact with certain compounds.

The hindered phenol compound refers to a phenol compound having a bulky substituent (for example, a branched or cyclic alkyl group such as a t-butyl group) at least on one of the ortho positions of the phenol.
The hindered phenol compound is not particularly limited, and examples thereof include bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][ethylene bis(oxyethylene)], N,N'-hexamethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide], 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2'-dihydroxy-3,3'-biphenyl ester, bis(α-methylcyclohexyl)-5,5'-dimethyldiphenylmethane, 2,2'-methylenebis(6-tert-butyl-p-cresol), 2,2'-methylenebis(6-tert-butyl-4-ethylphenol), triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,4-bis 4-hydroxy-3,5-di-tert-butylanilino)-1,3,5-triazine, pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2-thio-diethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-hexamethion Examples of the compound represented by the chemical formula below include benzenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, N,N'-bis[2-[2-(3,5-di-tert-butyl-4-hydroxyphenyl)ethylcarbonyloxy]ethyl]oxamide, and the compound represented by the chemical formula below.

（式中、Ｚは、置換されてもよいアルキレン基である。Ｒ^８１及びＲ^８２は、それぞれ独立して、置換されてもよい、アルキル基、アラルキル基、アリール基、ヘテロアリール基、シクロアルキル基又はヘテロシクロアルキル基である。Ｒ^８３及びＲ^８４は、それぞれ独立して、置換されてもよいアルキル基である。）

(In the formula, Z is an alkylene group which may be substituted. R ⁸¹ and R ⁸² are each independently an alkyl group, an aralkyl group, an aryl group, a heteroaryl group, a cycloalkyl group, or a heterocycloalkyl group which may be substituted. R ⁸³ and R ⁸⁴ are each independently an alkyl group which may be substituted.)

Examples of nitrogen compounds in metal deactivators include hydrazide-based nitrogen compounds, amide-based nitrogen compounds, triazole-based nitrogen compounds, and melamine-based nitrogen compounds.

The hydrazide-based nitrogen compound may be any nitrogen compound having a hydrazide skeleton, such as dodecanedioic acid bis[N2-(2-hydroxybenzoyl)hydrazide], N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, decanedicarboxylic acid disalicyloylhydrazide, N-salicylidene-N'-salicylhydrazide, m-nitrobenzhydrazide, 3-aminophthalhydrazide, phthalic acid dihydrazide, adipic acid hydrazide, oxalobis(2-hydroxy-5-octylbenzylidenehydrazide), N'-benzoylpyrrolidone carboxylic acid hydrazide, and N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hydrazine.

The amide nitrogen compound may be any nitrogen compound having an amide skeleton, such as N,N'-bis{2-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxyl]ethyl}oxamide.

Triazole-based nitrogen compounds may be any nitrogen compound having a triazole skeleton, such as N-(2H-1,2,4-triazol-5-yl)salicylamide, 3-amino-1,2,4-triazole, and 3-(N-salicyloyl)amino-1,2,4-triazole.

The melamine-based nitrogen compound may be any nitrogen compound having a melamine skeleton, and examples thereof include melamine, melamine derivatives, etc. More specific examples thereof include trisaminotriazine, alkylated trisaminotriazine, alkoxyalkylated trisaminotriazine, melamine, alkylated melamine, alkoxyalkylated melamine, N2-butylmelamine, N2,N2-diethylmelamine, N,N,N',N',N'',N'',N''-hexakis(methoxymethyl)melamine, etc.
The metal deactivators may be used alone or in combination of two or more.

<Antioxidants>
The antioxidant may, for example, be a hindered phenol-based antioxidant such as 2,2'-dihydroxy-3,3'-bis(α-methylcyclohexyl)-5,5'-dimethyldiphenylmethane.
The antioxidants may be used alone or in combination of two or more.

The solid content in the flux is preferably 40 mass % or less, more preferably 5 mass % or more and 30 mass % or less, and even more preferably 10 mass % or more and 25 mass % or less, relative to the total amount (100 mass %) of the flux.
By having the solid content within the above range, the flux becomes easier to use in flow soldering.

The flux according to the embodiment described above has a solvent content of 60 mass % or more relative to the total mass (100 mass %) of the flux, and is suitable for flow soldering.
The flux according to the above embodiment contains the compound represented by the general formula (1) above, and thus can suppress adhesion of dross to the surface of the board after soldering.
The reason why such an effect is exhibited is unclear, but is presumed to be as follows. In the compound represented by the above general formula (1), hydroxyl groups are bonded to adjacent carbon atoms forming a ring structure of a benzene ring. These hydroxyl groups coordinate with metal atoms on the surface of the substrate to form a coating. This coating prevents dross from adhering to the surface of the substrate after soldering.

(Method of manufacturing the bonded body)
The method for producing a bonded body according to the second aspect includes a step of obtaining a bonded body by soldering a solder alloy to the surface of a substrate that has been treated with the flux according to the first aspect.
Hereinafter, one embodiment of the method for producing a bonded body according to the second aspect will be described.
The method for manufacturing a bonded body according to this embodiment includes a component mounting step, a flux application step, a preheating step, and a soldering step, in this order.

In the component attachment process, the components are attached to the board.
The substrate may be, for example, a printed wiring board.
Examples of components include integrated circuits, transistors, diodes, resistors, and capacitors.

In the flux application step, the flux of the above embodiment is applied to the soldering surface of the board on which the components are mounted.
Examples of flux application devices include spray fluxers, foaming fluxers, etc. Among these, spray fluxers are preferred from the viewpoint of the stability of the amount of application.
From the viewpoint of solderability, the amount of flux applied is preferably 30 to 180 mL/ ^m2 , more preferably 40 to 150 mL/ ^m2 , and particularly preferably 50 to 120 mL/ ^m2 .

In the preheating process, the board on which the components are mounted is preheated. The temperature to which the board is heated in the preheating process is preferably 80 to 130°C, and more preferably 90 to 120°C.

In the soldering process, the surface to be soldered of the board on which the components are mounted is brought into contact with molten solder which is a melted solder alloy.
The method for bringing the molten solder into contact with the surface to be soldered is not particularly limited as long as it is a method that can bring the molten solder into contact with the board. Examples of such a method include a jet method and an immersion method.
The jet method is a method in which the soldering surface of a board with components mounted on it is brought into contact with a jet of molten solder, while the immersion method is a method in which the soldering surface of a board with components mounted on it is brought into contact with the liquid surface of a stationary molten solder.

As the solder alloy, a solder alloy having a known composition can be used.
The solder alloy may be a solder of simple Sn, or a solder alloy of Sn-Ag system, Sn-Cu system, Sn-Ag-Cu system, Sn-Bi system, Sn-In system, etc., or a solder alloy of these alloys to which Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, P, etc. have been added.
The solder alloy may be a Sn-Pb based solder alloy or a Sn-Pb based solder alloy to which Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, P, etc. have been added.
The solder alloy is preferably a solder alloy that does not contain Pb, and more preferably a solder alloy that contains Sn and Bi.

The soldering conditions in the soldering process may be set appropriately depending on the melting point of the solder. For example, when using a Sn-Ag-Cu solder alloy, the molten solder temperature is preferably 230-280°C, and more preferably 250-270°C. Alternatively, when using a Sn-Bi solder alloy (a solder alloy containing Sn and Bi), the molten solder temperature is preferably 170-220°C, and more preferably 180-200°C.

According to the manufacturing method of the joint body of the present embodiment described above, it is possible to suppress the adhesion of dross to the surface of the substrate after soldering. According to the manufacturing method of the joint body of the present embodiment, it is possible to suppress the adhesion of dross to the surface of the substrate even when a solder alloy containing Sn and Bi is used. Therefore, it is possible to manufacture a joint body with increased joint strength. In addition, it is possible to manufacture a joint body that is less likely to cause short circuits and deterioration of insulation.

The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

<Preparation of Flux>
(Examples 1 to 25, Comparative Examples 1 to 8)
The fluxes of the examples and comparative examples were prepared according to the compositions shown in Tables 1 to 5.

The types and softening points of the rosins used are as follows:
Acrylic acid modified hydrogenated rosin (softening point 130°C)
Hydrogenated rosin (softening point 74°C)
Disproportionated hydrogenated rosin (softening point 85℃)
Hydrogenated rosin glycerin ester (softening point 90°C)

The softening points of the above rosins were measured by the ring and ball method described in JIS K 5902. Rosins with softening points of 80°C or less were measured in a water bath. Rosins with softening points above 80°C were measured in a glycerin bath. Measurements were performed twice for each rosin. The above softening points are the average of the two measured values.

As the compound represented by the general formula (1), the following four types of compounds were used.
3,4,5-trihydroxybenzoic acid, CAS registration number: 149-91-7
2,3-Dihydroxybenzoic acid, CAS registration number: 303-38-8
3,4-Dihydroxyphenylacetic acid, CAS Registry Number: 102-32-9
3,4,5-trihydroxybenzoic acid methyl ester, CAS registration number: 99-24-1

3,4,5-trihydroxybenzoic acid is a compound represented by the following formula (1-1): In this compound, R ¹ is a single bond, R ² is a hydrogen atom, m is 1, and n is 1 in general formula (1).

2,3-Dihydroxybenzoic acid is a compound represented by the following formula (1-2): In this compound, R ¹ is a single bond, R ² is a hydrogen atom, m is 1, and n is 0 in the above general formula (1).

3,4-Dihydroxyphenylacetic acid is a compound represented by the following formula (1-3): In this compound, R ¹ is a methylene group, R ² is a hydrogen atom, m is 1, and n is 0 in the above general formula (1).

3,4,5-trihydroxybenzoic acid methyl ester is a compound represented by the following formula (1-4): In this compound, R ¹ is a single bond, R ² is a methyl group, m is 1, and n is 1 in the above general formula (1).

The following six compounds were used as comparative compounds.
2,4-Dihydroxybenzoic acid, CAS Registry Number: 89-86-1
2,5-Dihydroxybenzoic acid, CAS Registry Number: 490-79-9
2,6-Dihydroxybenzoic acid, CAS registration number: 303-07-1
Salicylic acid, CAS registration number: 69-72-7
3-Hydroxybenzoic acid, CAS Registry Number: 99-06-9
3,4,5-trihydroxybenzoic acid n-propyl ester, CAS registration number: 121-79-9

2,4-Dihydroxybenzoic acid is a compound represented by the following formula (2-1).
2,5-Dihydroxybenzoic acid is a compound represented by the following formula (2-2).
2,6-Dihydroxybenzoic acid is a compound represented by the following formula (2-3).
Salicylic acid is a compound represented by the following formula (2-4).
3-Hydroxybenzoic acid is a compound represented by the following formula (2-5).
3,4,5-Trihydroxybenzoic acid n-propyl ester is a compound represented by the following formula (2-6).

Other organic acids: palmitic acid, adipic acid, succinic acid, picolinic acid

Amine: 1-amino-2-propanol

Halogen compounds: ethylamine.HBr, diethylamine.HBr, cyclohexylamine.HBF ₄ , trans-2,3-dibromo-2-butene-1,4-diol, chlorinated fatty acid esters

Organophosphorus compound: 2-ethylhexyl (2-ethylhexyl) phosphonate

Solvent: 2-propanol

Nonionic surfactant: Polyethylene glycol with a weight average molecular weight of 400

<Preparation of Molten Solder>
An ingot of an alloy (Sn-58Bi) containing 58 mass % Bi and the remainder Sn was prepared as a master alloy, and the ingot was melted to prepare a molten solder.

According to the evaluation methods described in the <Evaluation> below, we performed the <Evaluation of dross adhesion suppression ability>, <Evaluation of solder wetting speed>, <Evaluation of solder wetting power>, and <Evaluation of insulation resistance>. The results of these evaluations are shown in Tables 1 to 5.

<Evaluation>
<Evaluation of dross adhesion suppression ability>
(1) Evaluation method The flux of each example was applied by brush to a board on which circular lands (diameter 2 mm) and bale-shaped lands (4 mm x 2 mm) were alternately arranged. Using a flow soldering device (manufactured by Senju Metal Industry Co., Ltd., Ecopascal), the above-mentioned Sn-58Bi molten solder was placed in a solder bath. In the flow soldering device, the far-infrared panel heater was set to 250°C, the solder bath temperature to 180°C, the primary jet output to 46%, and the secondary jet output to 66%. The distance between the molten solder liquid surface and the board surface on which the flux was applied was set to 8 mm, and the conveying speed was set to 1 m/min, and the molten solder was brought into contact with the board surface.
Next, the captured image was trimmed and the contrast was adjusted using image analysis software (ImageJ). Furthermore, the size and circularity of the measurement object were specified, and the parts other than the dross were removed. The total area of the dross was measured using the image analysis software.

(2) Evaluation criteria A: 0.24 ^mm2 or less B: More than 0.24 ^mm2 and 0.31 mm2 or ^less C: More than 0.31 ^mm2 and 0.40 ^mm2 or less D: More than 0.40 ^mm2 Fluxes with an evaluation result of A or B were deemed to have passed the test, and fluxes with an evaluation result of C or D were deemed to have failed the test.

<Evaluation of solder wetting speed and solder wetting power>
(1) Evaluation method The meniscograph test was performed in accordance with JIS Z3197 (2021) 8.3.1.2 “Wetting balance test”.
Specifically, first, a copper test plate of 10 mm x 30 mm x 0.3 mm was prepared. The test plate was washed in this order using dilute hydrochloric acid, purified water, 2-propanol, and acetone. Then, the test plate was oxidized in a dryer at 130°C for 20 minutes. The test piece was coated with flux by immersing the test piece in the flux to a depth of 2 to 4 mm from its end. The test piece coated with flux was attached to a mass meter of a wetting balance tester (Solder Checker SAT-5200, manufactured by RHESCA) and then immersed in a solder bath to measure the zero cross time (sec) and the maximum value of the wetting force (mN). Next, five measurements were performed for each example of flux, and the average value of the five zero cross times (sec) and wetting forces obtained was calculated. The test conditions were as follows.
Immersion speed in solder bath: 20 mm/sec
Immersion depth in solder bath: 2.00 mm
Immersion time in solder bath: 10 sec
Solder bath temperature: 180°C

(2) Criteria The solder wetting speed was judged based on the zero cross time.
Zero cross time:
A: Less than 1.6 seconds B: 1.6 to less than 2.4 seconds C: 2.4 seconds or more The shorter the average zero cross time (sec), the higher the wetting speed, which means better solder wettability.

The solder wetting force was evaluated based on the maximum wetting force.
Maximum wetting power:
A: 2.3 mN or more; B: more than 1.81 mN and less than 2.3 mN; C: 1.8 mN or less. The higher the average value of the solder wetting force, the higher the wetting force, which means better solder wettability.

<Insulation resistance evaluation>
(1) Evaluation method The insulation resistance test was performed in accordance with JIS Z3197 (2021) 8.5.3. "Insulation resistance test". Specifically, the flux of each example was applied to a board having a skewer pattern, and then soldered and dried at 100 ° C. for 5 minutes. The dried board was immersed for 5 seconds in a solder bath set at a temperature 35 ° C. higher than the liquidus temperature of the solder, and soldered. Next, the board was placed in a high-temperature and high-humidity bath and left to stand in an environment of 85 ° C. and 85% relative humidity for 24 hours, and the insulation resistance value of the board surface was measured.

(2) Judgment criteria Insulation resistance value A 4 x 10 ⁹ Ω or more B More than 1 x 10 ⁹ Ω but less than 4 x 10 ⁹ Ω C 1 x 10 ⁹ Ω or less

The fluxes of Examples 1 to 25 containing the compound represented by the above general formula (1) were rated A or B in terms of their ability to inhibit dross adhesion.
The fluxes of Comparative Examples 1 to 8, which did not contain the compound represented by the general formula (1), were rated C or D in terms of their ability to inhibit dross adhesion.

The fluxes of Examples 1 to 9, in which the content of the compound in which n is 1 in the above general formula (1) is 0.03 mass % or more and 5 mass % or less, were evaluated as A or B in terms of their ability to inhibit dross adhesion.
The fluxes of Examples 3 to 9, in which the content of the compound in which n is 1 in the above general formula (1) was 0.08 mass % or more and 5 mass % or less, were evaluated as A in terms of their ability to inhibit dross adhesion.

The fluxes of Examples 1 to 9, in which the mass ratio of the compound in which n is 1 in the above general formula (1)/the organic acid other than the compound in the above general formula (1) is 0.05 to 10, were evaluated as A or B in terms of their ability to inhibit dross adhesion.
The fluxes of Examples 3 to 9, in which the mass ratio of the compound in which n is 1 in the above general formula (1)/the organic acid other than the compound in the above general formula (1) is 0.1 to 10, were evaluated as A in terms of their ability to inhibit dross adhesion.

The fluxes of Examples 10 to 21, in which the content of the compound in which n is 0 in the above general formula (1) is 0.2 mass % or more and 5 mass % or less, were evaluated as A or B in terms of their ability to inhibit dross adhesion.
The fluxes of Examples 12 to 14 and Examples 19 to 21, in which the content of the compound in which n is 0 in the above general formula (1) is 2 mass % or more and 5 mass % or less, were evaluated as A in terms of their ability to inhibit dross adhesion.

The fluxes of Examples 10 to 21, in which the mass ratio of the compound in which n is 0 in the above general formula (1)/the organic acid other than the compound in the above general formula (1) is 0.25 or more and 10 or less, were evaluated as A or B in terms of their ability to inhibit dross adhesion.
The fluxes of Examples 12 to 14 and Examples 19 to 21, in which the mass ratio of the compound in which n is 0 in the above general formula (1) to the organic acid other than the compound in the above general formula (1) is 3 or more and 10 or less, were evaluated as A in terms of their ability to inhibit dross adhesion.

The fluxes of Examples 1 to 7, in which the content of the compound in which n is 1 in the above general formula (1) was 0.03 mass % or more and 2 mass % or less, were evaluated as A or B in the wetting speed.
The fluxes of Examples 2 to 5, in which the content of the compound in which n is 1 in the above general formula (1) was 0.05 mass % or more and 0.5 mass % or less, were evaluated as A in terms of the wetting speed.

The fluxes of Examples 1 to 7, in which the mass ratio of the compound in which n is 1 in the above general formula (1)/the organic acid other than the compound in the above general formula (1) is 0.05 or more and 4 or less, were evaluated as A or B in the wetting speed.
The fluxes of Examples 2 to 5, in which the mass ratio of the compound in which n is 1 in the above general formula (1) to the organic acid other than the compound in the above general formula (1) is 0.08 or more and 1 or less, were evaluated as A for the wetting speed.

The fluxes of Examples 10 to 21, in which the content of the compound in which n is 0 in the above general formula (1) is 0.2 mass % or more and 5 mass % or less, were evaluated as A or B in the wetting speed.
The evaluation results of the wetting speed of the fluxes of Examples 11 to 14, in which the content of the compound in which n is 0 in the above general formula (1) is 1 mass % or more and 5 mass % or less, and the fluxes of Examples 15 to 21, in which the content of the compound in which n is 0 in the above general formula (1) is 0.2 mass % or more and 5 mass % or less, were A.

The fluxes of Examples 10 to 21, in which the mass ratio of the compound in which n is 0 in the above general formula (1)/the organic acid other than the compound in the above general formula (1) is 0.25 or more and 10 or less, were evaluated as A or B in the wetting speed.
The fluxes of Examples 11 to 14 in which the mass ratio represented by the compound in which n is 0 in the above general formula (1)/the organic acid other than the compound in the above general formula (1) is 1.5 or more and 10 or less, and the fluxes of Examples 15 to 21 in which the mass ratio represented by the compound in which n is 0 in the above general formula (1)/the organic acid other than the compound in the above general formula (1) is 0.3 or more and 10 or less, were evaluated as having a wetting speed of A.

The fluxes of Examples 1 to 7, in which the content of the compound in which n is 1 in the above general formula (1) was 0.03 mass % or more and 2 mass % or less, were evaluated as B or C in terms of wetting power.
The fluxes of Examples 1 to 6, in which the content of the compound in which n is 1 in the above general formula (1) was 0.03 mass % or more and 1 mass % or less, were evaluated as B in the wettability.

The fluxes of Examples 10 to 21, in which the content of the compound in which n is 0 in the above general formula (1) is 0.2 mass % or more and 5 mass % or less, were evaluated as A or B in the wettability.
The fluxes of Examples 10 to 12, in which the content of the compound in which n is 0 in the above general formula (1) is 0.5 mass % or more and 2 mass % or less, and the fluxes of Examples 15 to 21, in which the content of the compound in which n is 0 in the above general formula (1) is 0.2 mass % or more and 5 mass % or less, were evaluated as A for the wetting power.

The fluxes of Examples 1 to 7, in which the mass ratio of the compound in which n is 1 in the above general formula (1) to the organic acid other than the compound in the above general formula (1) is 0.05 or more and 4 or less, were evaluated as B or C in terms of wetting power.
The fluxes of Examples 1 to 6, in which the mass ratio of the compound in which n is 1 in the above general formula (1) to the organic acid other than the compound in the above general formula (1) is 0.05 or more and 2 or less, were evaluated as B in the wettability.

The fluxes of Examples 10 to 21, in which the mass ratio of the compound in which n is 0 in the above general formula (1)/the organic acid other than the compound in the above general formula (1) was 0.25 or more and 10 or less, were evaluated as A or B in the wettability.
The fluxes of Examples 10 to 12, in which the mass ratio of the compound in which n is 0 in the above general formula (1) to the organic acid other than the compound in the above general formula (1) is 0.8 or more and 4 or less, were evaluated as A for the wetting power.
The fluxes of Examples 15 to 21, in which the mass ratio of the compound in which n is 0 in the above general formula (1) to the organic acid other than the compound in the above general formula (1) is 0.25 or more and 10 or less, were evaluated as A for the wetting power.

The fluxes of Examples 1 to 7, in which the content of the compound in which n is 1 in the above general formula (1) was 0.03 mass % or more and 2 mass % or less, were evaluated as A or B in terms of insulation resistance.
The fluxes of Examples 1 to 6, in which the content of the compound in which n is 1 in the above general formula (1) was 0.03 mass % or more and 1 mass % or less, were evaluated as A in terms of insulation resistance.

The fluxes of Examples 10 to 20, in which the content of the compound in which n is 0 in the above general formula (1) is 0.2 mass % or more and 5 mass % or less, were evaluated for insulation resistance as A or B.
The insulation resistance of the fluxes of Examples 10 to 14, in which the content of the compound in which n is 0 in the above general formula (1) is 0.5 mass % or more and 5 mass % or less, and the fluxes of Examples 15 to 19, in which the content of the compound in which n is 0 in the above general formula (1) is 0.2 mass % or more and 2 mass % or less, was evaluated as A.

The fluxes of Examples 1 to 7, in which the mass ratio of the compound in which n is 1 in the above general formula (1)/the organic acid other than the compound in the above general formula (1) is 0.05 or more and 4 or less, were evaluated as A or B in terms of insulation resistance.
The fluxes of Examples 1 to 6, in which the mass ratio of the compound in which n is 1 in the above general formula (1) to the organic acid other than the compound in the above general formula (1) is 0.05 or more and 2 or less, were evaluated as A for insulation resistance.

The fluxes of Examples 10 to 20, in which the mass ratio of the compound in which n is 0 in the above general formula (1)/the organic acid other than the compound in the above general formula (1) is 0.25 or more and 10 or less, were evaluated for insulation resistance as A or B.
The fluxes of Examples 10 to 14, in which the mass ratio of the compound in which n is 0 in the above general formula (1)/the organic acid other than the compound in the above general formula (1) is 0.5 or more and 10 or less, were evaluated as A for insulation resistance.
The fluxes of Examples 15 to 19, in which the mass ratio of the compound in which n is 0 in the above general formula (1)/the organic acid other than the compound in the above general formula (1) is 0.25 or more and 4 or less, were evaluated as A for insulation resistance.

Examples 12 and 19, which contain halogen compounds, were rated as A for wetting speed. Examples 24 and 25, which do not contain halogen compounds, were rated as B for wetting speed. From these results, it was confirmed that fluxes containing halogen compounds are more likely to increase the wetting speed.

The flux of Comparative Example 2, which did not contain either the compound represented by the general formula (1) or a halogen compound, was evaluated as having a wetting power of B. The fluxes of Examples 24 and 25, which contained the compound represented by the general formula (1) but did not contain a halogen compound, were evaluated as having a wetting power of A.
From the viewpoint of environmental load, it is considered that a flux that does not contain halogen compounds is preferable. It has been confirmed that by containing the compound represented by the above general formula (1), it is easy to improve the evaluation of wetting power even without containing a halogen compound.

The flux of the present invention is suitable for flow soldering. It is also suitable for flow soldering using lead-free solder, such as solder containing Sn and Bi.

Claims (13)

The composition contains rosin, a solvent, and a compound represented by the following general formula (1):
The content of the solvent is 60% by mass or more with respect to the total mass (100% by mass) of the flux,
The content of the compound represented by the general formula (1) is 0.2 mass% or more and 5 mass% or less with respect to the total mass (100 mass%) of the flux,
The rosin includes a rosin (PA) having a softening point of more than 100°C and a rosin (PB) having a softening point of 100°C or lower .

[In the formula, R ¹ is a linking group or a single bond, R ² is an alkyl group having 1 to 2 carbon atoms or a hydrogen atom, m is 1 , and n is 1. ] Further, it contains an organic acid (excluding the compound represented by the general formula (1)),
The flux according to claim 1, wherein a mass ratio of the compound represented by the general formula (1) to the organic acid is 0.05 to 10, as a mass ratio represented by the compound represented by the general formula ( 1 )/organic acid. The flux according to claim 1, wherein a mixing ratio of the rosin (PA) and the rosin (PB) is, as a mass ratio represented by (PA)/(PB), (PA)/(PB)=1/ 9 to 5.5/4.5 . The composition contains rosin, a solvent, and a compound represented by the following general formula (1):
The content of the solvent is 60% by mass or more with respect to the total mass (100% by mass) of the flux,
The content of the compound represented by the general formula (1) is 0.2 mass% or more and 5 mass% or less with respect to the total mass (100 mass%) of the flux,
The rosin includes a rosin (PA) having a softening point of more than 100° C. and a rosin (PB) having a softening point of 100° C. or less,
A mixing ratio of the rosin (PA) and the rosin (PB) is, as a mass ratio represented by (PA)/(PB), (PA)/(PB)=1/9 to 5.5/4.5 .

[In the formula, R ¹ is a linking group or a single bond, R ² is an alkyl group having 1 to 2 carbon atoms or a hydrogen atom, m is 1 , and n is 0. ] Further, it contains an organic acid (excluding the compound represented by the general formula (1)),
The flux according to claim 4, wherein a mass ratio of the compound represented by the general formula (1) to the organic acid is 0.25 to 10, as a mass ratio represented by the compound represented by the general formula ( 1 )/organic acid. The flux of claim 1, further comprising a halide salt of a primary amine. 5. The flux of claim 4 further comprising a halide salt of a primary amine. The flux according to claim 1, which does not contain any halogen compounds. 5. The flux of claim 4 which is halide-free. The flux according to claim 1, wherein the solvent includes at least one selected from the group consisting of ethanol and 2-propanol. The flux according to claim 4, wherein the solvent includes at least one selected from the group consisting of ethanol and 2-propanol. A method for producing a bonded body, comprising the step of obtaining a bonded body by soldering a solder alloy to a surface of a substrate that has been treated with the flux according to any one of claims 1 to 11 . The method for producing a joint body according to claim 12 , wherein the solder alloy is a solder alloy containing Sn and Bi.