TWI895647B - Flux and method of manufacturing conjugate - Google Patents

Abstract

The present invention uses a flux containing rosin, a terpene phenolic resin, and an activator. The hydroxyl value of the terpene phenolic resin is greater than 70 mg KOH/g. The activator contains an organic acid having a solubility parameter (SP value) of 11.00 or more, or an organic acid represented by general formula (1). In formula (1), R¹ represents a chain hydrocarbon group having 2 to 15 carbon atoms, an alicyclic hydrocarbon group having 3 to 15 carbon atoms, an aromatic group, or a carboxy group. However, the chain hydrocarbon group and the alicyclic hydrocarbon group each have a hydroxy group or a carboxy group.

R¹-COOH…(1)

Description

Flux and method for manufacturing joint body

This invention relates to a flux and a method for manufacturing a bonded body. This application claims priority based on Japanese Patent Application No. 2021-182145 filed in Japan on November 8, 2021, and the contents of that application are incorporated herein by reference.

Soldering is typically used to secure components to a substrate and to electrically connect components to the substrate. Soldering uses flux, solder, and solder paste, which is a mixture of flux and solder.

Flux chemically removes metal oxides from the metal surfaces of the objects being soldered and the solder, and it also mobilizes metal elements at the interface between the two. Therefore, using flux during soldering creates an intermetallic compound between the two, creating a strong joint.

In welding, methods such as reflow and flow soldering are used depending on the size of the objects being joined.

In reflow, solder paste is first printed on the substrate. Then, the substrate with components mounted on it is heated in a heating furnace called a reflow oven to perform soldering.

In flow soldering, flux is first applied to the substrate with components mounted on it. Then, the substrate with components mounted on it is transported while molten solder, sprayed from below, contacts the soldering surface, allowing soldering to proceed.

The flux used in soldering generally contains a resin component, a solvent, an activator, and the like. For example, Patent Document 1 describes 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.

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent No. 6617848

After soldering, the resin and activator components in flux leave a residue at the junction between the component and the substrate, known as flux slag. The activator in flux is prone to precipitation after soldering. The activator in the flux slag absorbs moisture from the air and ionizes. The ionized activator can corrode metals and cause migration.

Therefore, the object of the present invention is to provide a flux and a method for manufacturing a joint body that can further suppress the precipitation of an activator in the flux residue after soldering.

This invention includes the following aspects.

The first aspect of the present invention is a soldering flux comprising rosin, a terpene phenol resin, and an activator. The terpene phenol resin has a hydroxyl value exceeding 70 mgKOH/g, and the activator comprises an organic acid (A1) having a solubility parameter (SP value) of 11.00 or greater.

In the flux of the first embodiment, the content of the organic acid (A1) is preferably not less than 0.05% by mass and not more than 6% by mass relative to the total mass of the flux (100% by mass).

In the flux of the first aspect, the content ratio (mass ratio) of the organic acid (A1) relative to the content (100 parts by mass) of the terpene phenol resin is preferably 1 part by mass or more and 600 parts by mass or less.

Furthermore, the second aspect of the present invention is a flux comprising rosin, a terpene phenol resin, and an activator, wherein the terpene phenol resin has a hydroxyl value exceeding 70 mgKOH/g, and the activator comprises an organic acid (A2) represented by the following general formula (1).

R ¹ -COOH‧‧‧(1) [In the formula, R ¹ represents a carbon chain alkyl group having 2 to 15 carbon atoms, an alicyclic alkyl group having 3 to 15 carbon atoms, an aromatic group, or a carboxyl group, but the aforementioned carbon chain alkyl group and the aforementioned alicyclic alkyl group each have a hydroxyl group or a carboxyl group.]

In the aforementioned second aspect of the flux, the content of the organic acid (A2) is preferably not less than 0.05% by mass and not more than 6% by mass relative to the total mass of the flux (100% by mass).

In the aforementioned second aspect of the flux, the content ratio (mass ratio) of the aforementioned organic acid (A2) relative to the content (100 parts by mass) of the aforementioned terpene phenol resin is preferably 1 part by mass or more and 600 parts by mass or less.

In the flux of the first or second aspect, the content of the terpene phenol resin is preferably not less than 0.1% by mass and not more than 20% by mass relative to the total mass of the flux (100% by mass).

Furthermore, a third aspect of the present invention is a method for manufacturing a joint, comprising the steps of: soldering a solder alloy onto the surface of a substrate treated with the flux of the first aspect or the second aspect to obtain a joint.

According to the present invention, a method for manufacturing a flux and a joint body can be provided that can further suppress the precipitation of an activator in the flux residue after soldering.

(Flux)

The fluxes in Type 1 and Type 2 can be used for both flow soldering and reflow soldering, but are specifically designed for flow soldering.

The substrates used in flow soldering are characterized by being inexpensive, made of a poorly wetted material, and easily oxidized. Furthermore, flow soldering requires a short soldering time. For these reasons, highly active activators are used in flow soldering. However, these highly active activators can become difficult to dissolve in flux residues, such as resins, after soldering, and may precipitate within the flux residue. The specific organic acids described below may be used as highly active activators.

In the fluxes of Aspects 1 and 2, a terpene phenol resin with a hydroxyl value exceeding 70 mgKOH/g is used for the specific organic acid. This suppresses the precipitation of the activator in the flux residue.

The following details the flux used in the first and second examples.

In this manual, the solid content of flux refers to all components remaining after removing the solvent from the flux.

In this manual, the hydroxyl value of terpene phenol resins refers to the hydroxyl value measured by the potentiometric titration method in accordance with Section 7.2 of JIS K0070 "Test methods for acid value, saponification value, ester value, iodine value, hydroxyl value, and unsaponifiable matter of chemicals."

The hydroxyl value determined by this method is the weighted average of the hydroxyl values of all types of terpene phenolic resins contained in the flux.

[Model 1]

One embodiment of the first aspect of the flux is as follows. The flux of this embodiment contains rosin, terpene phenol resin, activator, solvent (S), and other ingredients as needed.

The terpene phenol resin has a hydroxyl value exceeding 70 mgKOH/g. The activator comprises an organic acid (A1) having a solubility parameter (SP value) of 11.00 or greater. The flux of this embodiment is suitable for flow soldering.

<Rosin>

In the present invention, "rosin" includes natural resins containing rosinic acid as the main component, mixtures of rosinic acid and its isomers, and chemically modified natural resins (sometimes also referred to as rosin derivatives).

The total content of rosinic acid and its isomers in natural resin, for example, is not less than 40% by mass and not more than 80% by mass relative to the natural resin.

In this specification, the term "main component" refers to a component that constitutes a compound and whose content in the compound is 40% by mass or more.

Representative isomers of rosinic acid include neorosinic acid, palustric acid, and levopimaric acid. The structure of rosinic acid is shown below.

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

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

Rosin derivatives include purified rosin, modified rosin, etc.

Examples of modified rosins include hydrogenated rosin, polymerized rosin, polymerized hydrogenated rosin, disproportionated rosin, acid-modified rosin, rosin esters, 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 rosin, maleic rosin, fumaric rosin, etc.), as well as purified, hydrogenated, and disproportionated products of polymerized rosin, as well as purified, hydrogenated, and disproportionated products of α,β-unsaturated carboxylic acid modified products, rosin alcohol, rosinamine, hydrogenated rosin alcohol, rosin esters, hydrogenated rosin esters, rosin soap, hydrogenated rosin soap, and acid-modified rosin soap.

Examples of rosinamines include deferoxamine and dihydrorosinamine. Rosinamine refers to disproportionated rosinamine. The structures of deferoxamine and dihydrorosinamine are shown below.

Rosin can be used alone or as a mixture of two or more.

It is best to use rosin derivatives as rosin.

As the rosin derivative, it is preferred to use at least one selected from the group consisting of acid-modified hydrogenated rosin, acid-modified rosin, hydrogenated rosin, polymerized rosin, and rosin ester.

As the acid-modified hydrogenated rosin, acrylic acid-modified hydrogenated rosin is preferably used.

As the acid-modified rosin, acrylic acid-modified rosin is preferably used.

The content of the aforementioned rosin in the aforementioned flux, relative to the total amount of the aforementioned flux (100 mass%), is preferably 1 mass% to 30 mass%, more preferably 2 mass% to 25 mass%, and even more preferably 2 mass% to 20 mass%.

In the solid content of the aforementioned flux, the content of the aforementioned rosin relative to the total solid content (100 mass%) is preferably 10 mass% to 90 mass%, more preferably 20 mass% to 80 mass%, and even more preferably 30 mass% to 75 mass%.

<Terpene phenol resin>

In this specification, the term "terpene phenolic resin" refers to copolymers of terpene monomers and phenols, their hydrogenated copolymers, and copolymers of terpene monomers and monomers other than terpene monomers and phenols, and their hydrogenated copolymers.

Examples of terpene phenolic resins include terpene resins, modified terpene resins, terpene phenolic resins, and modified terpene phenolic resins.

Examples of modified terpene resins include hydrogenated terpene resins, aromatic modified terpene resins, and hydrogenated aromatic modified terpene resins.

Examples of modified terpene phenolic resins include hydrogenated terpene phenolic resins.

Examples of terpene monomers include hemiterpenes with a carbon number of 5, such as isoprene, monoterpenes with a carbon number of 10, sesquiterpenes with a carbon number of 15, diterpenes with a carbon number of 20, disesquiterpenes with a carbon number of 25, triterpenes with a carbon number of 30, and tetraterpenes with a carbon number of 40.

Examples of phenols include phenol, cresol, xylenol, etc.

The hydroxyl value of the terpene phenol resin is greater than 70 mgKOH/g, and may be greater than 90 mgKOH/g, preferably greater than 110 mgKOH/g, more preferably greater than 130 mgKOH/g, even more preferably greater than 140 mgKOH/g, particularly preferably greater than 170 mgKOH/g, and most preferably greater than 190 mgKOH/g.

The upper limit of the hydroxyl value of the terpene phenol resin is not particularly limited as long as the effects of the present invention can be exerted, but for example, it may be 300 mgKOH/g or less, 250 mgKOH/g or less, or 230 mgKOH/g or less.

For example, the hydroxyl value of terpene phenolic resins can be greater than 70 mgKOH/g and less than 300 mgKOH/g, can be greater than 90 mgKOH/g and less than 300 mgKOH/g, preferably greater than 110 mgKOH/g and less than 300 mgKOH/g, more preferably greater than 130 mgKOH/g and less than 300 mgKOH/g, even more preferably greater than 140 mgKOH/g and less than 300 mgKOH/g, particularly preferably greater than 170 mgKOH/g and less than 300 mgKOH/g, and can be greater than 190 mgKOH/g and less than 300 mgKOH/g.

Alternatively, the hydroxyl value of the terpene phenol resin may be greater than 70 mgKOH/g and less than 250 mgKOH/g, or may be greater than 90 mgKOH/g and less than 250 mgKOH/g, preferably greater than 110 mgKOH/g and less than 250 mgKOH/g, more preferably greater than 130 mgKOH/g and less than 250 mgKOH/g, even more preferably greater than 140 mgKOH/g and less than 250 mgKOH/g, particularly preferably greater than 170 mgKOH/g and less than 250 mgKOH/g, and may be greater than 190 mgKOH/g and less than 250 mgKOH/g.

By having the hydroxyl value of the terpene phenol resin exceed the aforementioned lower limit, the effect of suppressing the precipitation of the highly polar organic acid (A1) in the flux residue can be further enhanced.

By keeping the hydroxyl value of the terpene phenol resin below the aforementioned upper limit, moisture absorption can be further reduced. This can further suppress the decrease in the flux's insulation resistance and the occurrence of migration.

Examples of readily available terpene phenol resins include YS Polystar (terpene phenol resin: manufactured by Yasuhara Chemical Co., Ltd.), TAMANOL (terpene phenol resin: manufactured by Arakawa Chemical Industries, Ltd.), TERTAC 80 (terpene phenol resin: manufactured by Japan Terpene Chemical Co., Ltd.), and Sylvares TP (terpene phenol resin: manufactured by Air Brown Co., Ltd.). Terpene phenol resins can be selected from these to achieve the desired hydroxyl value.

Terpene phenolic resins can be used alone or as a mixture of two or more.

The flux of this embodiment may contain one terpene phenolic resin having a hydroxyl value exceeding 70 mgKOH/g. Alternatively, the flux of this embodiment may contain two or more terpene phenolic resins having different hydroxyl values, and the weighted average of these hydroxyl values may exceed 70 mgKOH/g.

The content of the terpene phenol resin in the flux is preferably not less than 0.1 mass% and not more than 20 mass%, more preferably not less than 0.2 mass% and not more than 10 mass%, and even more preferably not less than 0.5 mass% and not more than 5 mass%, relative to the total amount of the flux (100 mass%).

In the solid content of the aforementioned flux, the content of the aforementioned terpene phenol resin relative to the total solid content (100 mass%) is preferably 3 mass% to 50 mass%, more preferably 4 mass% to 40 mass%, and even more preferably 5 mass% to 30 mass%.

By keeping the terpene phenol resin content above the aforementioned lower limit, the precipitation of organic acid (A1) in the flux residue after soldering can be further suppressed.

By keeping the terpene phenol resin content below the aforementioned upper limit, the risk of the flux viscosity becoming excessively high can be reduced.

The mixing ratio of rosin to terpene phenol resin refers to the mass ratio expressed as rosin/terpene phenol resin, that is, the ratio of the rosin content to the terpene phenol resin content. It is preferably 0.5 to 20, more preferably 1 to 10, and even more preferably 1.5 to 8.

<Activator>

《Specific Activator》

The flux of this embodiment, as a specific activator, includes an organic acid (A1) having a solubility parameter (SP value) of 11 or greater.

[Dissolution parameter (SP value)]

In this specification, the solubility parameter (SP value) refers to the value calculated from the molecular structure using the Fedors method. The SP value (δ) can be obtained using the following formula (sp).

δ=(△E/△V) ^1/2 (cal/cm ³ ) ^1/2 ‧‧‧(sp)

In formula (sp), ΔE represents the sum of the vaporization energies (cal/mol) of the atoms and atomic groups in the molecule of the organic acid (A1).

ΔV represents the total molar volume (cm ³ /mol) of atoms and atomic groups in the molecule of the organic acid (A1) at 25°C.

The values of evaporation energy and molar volume can be calculated using the values described in Robert F. Fedors, A method for estimating both the solubility parameters and molar volumes of liquids. Polymer Engineering and Science, 14, 147-154 (1974).

The SP value of the organic acid (A1) is 11.00 or higher, preferably 11.50 or higher, more preferably 11.70 or higher, even more preferably 12.00 or higher, particularly preferably 12.50 or higher, and most preferably 13.00 or higher.

The upper limit of the SP value of the organic acid (A1) is not particularly limited, but may be, for example, 25 or less, or 23 or less.

For example, the SP value of the organic acid (A1) may be 11.00 to 25.00, 11.50 to 25.00, 11.70 to 25.00, 12.00 to 25.00, 12.50 to 25.00, or 13.00 to 25.00.

Alternatively, the SP value of the organic acid (A1) may be 11.00 to 23.00, 11.50 to 23.00, 11.70 to 23.00, 12.00 to 23.00, 12.50 to 23.00, or 13.00 to 23.00.

Organic acids (A1) with SP values above the aforementioned lower limit are highly polar and therefore tend to precipitate in flux residues, such as resins, after soldering.

The flux of this embodiment utilizes a terpene phenol resin with a hydroxyl value exceeding 70 mgKOH/g. This suppresses the precipitation of organic acids (A1) with SP values above the aforementioned lower limit into the flux residue.

The organic acid (A1) may be a dicarboxylic acid.

Examples of the aforementioned dicarboxylic acids include oxalic acid (15.22), malonic acid (14.03), succinic acid (13.21), glutaric acid (12.61), adipic acid (12.15), pimelic acid, suberic acid (11.49), azelaic acid (11.25), sebacic acid (11.04), 2,4-diethylglutaric acid (14.89), and 1,3-cyclohexanedicarboxylic acid (12.80).

The values in parentheses represent the SP value of each dicarboxylic acid.

Alternatively, the organic acid (A1) may be a hydroxycarboxylic acid.

Examples of the aforementioned hydroxycarboxylic acids include 2,2-bis(hydroxymethyl)propionic acid (16.12), 2,2-bis(hydroxymethyl)butanoic acid (18.31), etc.

The values in parentheses represent the SP value of each hydroxycarboxylic acid.

Alternatively, the organic acid (A1) may be an aromatic carboxylic acid.

Examples of the aforementioned aromatic carboxylic acids include picolinic acid (12.78) and dipicolinic acid (13.37).

The organic acid (A1) is preferably succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, or 2,2-bis(hydroxymethyl)propionic acid, more preferably succinic acid, glutaric acid, adipic acid, or 2,2-bis(hydroxymethyl)propionic acid, and even more preferably succinic acid or 2,2-bis(hydroxymethyl)propionic acid.

The organic acid (A1) may be used alone or in combination of two or more.

The content of the aforementioned organic acid (A1) in the aforementioned flux is preferably not less than 0.05 mass% and not more than 6 mass%, more preferably not less than 0.1 mass% and not more than 4 mass%, and even more preferably not less than 0.1 mass% and not more than 3 mass%, relative to the total mass of the flux (100 mass%).

In the solid content of the flux, the content of the organic acid (A1) relative to the total solid content (100 mass%) is preferably 0.5 mass% to 50 mass%, more preferably 0.5 mass% to 40 mass%, and even more preferably 1 mass% to 40 mass%.

By setting the content of the organic acid (A1) above the lower limit, the wettability of the flux can be further improved.

By keeping the content of the organic acid (A1) below the aforementioned upper limit, the precipitation of the organic acid (A1) in the flux residue after soldering can be further suppressed.

The mixing ratio of the organic acid (A1) to the terpene phenol resin refers to the mass ratio of organic acid (A1) to terpene phenol resin, that is, the ratio of the organic acid (A1) to the content of the terpene phenol resin (100 parts by mass). It can be from 1 part by mass to 600 parts by mass, preferably from 2 parts by mass to 600 parts by mass, more preferably from 1 part by mass to 400 parts by mass, even more preferably from 1 part by mass to 200 parts by mass, particularly preferably from 1 part by mass to 100 parts by mass, and most preferably from 1 part by mass to 50 parts by mass.

By setting the content ratio of the organic acid (A1) to be above the lower limit, weldability can be improved.

By keeping the content ratio of the organic acid (A1) below the aforementioned upper limit, the precipitation of the organic acid (A1) in the flux residue after soldering can be further suppressed.

《Other Activators》

The activator contained in the flux of this embodiment may include other activators in addition to the organic acid (A1).

Examples of other activators include organic acid-based activators other than organic acid (A1), amine-based activators, and halogen-based activators.

[Other organic acid activators]

Examples of organic acid activators include undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, nonadecanedioic acid, eicosandioic acid, 4-tert-butylbenzoic acid, palmitic acid, 2-ethylhexyl 2-ethylhexylsulfonate, dimer acid, trimer acid, hydrogenated dimer acid which is a hydrogenation product of dimer acid, and hydrogenated trimer acid which is a hydrogenation product of trimer acid.

Examples of the dimer acid and trimer acid include the dimer acid of the reaction product of oleic acid and linoleic acid, the trimer acid of the reaction product of oleic acid and linoleic acid, the dimer acid of the reaction product of acrylic acid, the trimer acid of the reaction product of acrylic acid, the dimer acid of the reaction product of methacrylic acid, the trimer acid of the reaction product of methacrylic acid, the dimer acid of the reaction product of acrylic acid and methacrylic acid, and the Trimer acid, dimer acid belonging to the reaction product of oleic acid, trimer acid belonging to the reaction product of oleic acid, dimer acid belonging to the reaction product of linoleic acid, trimer acid belonging to the reaction product of linolenic acid, dimer acid belonging to the reaction product of hypolinolenic acid, trimer acid belonging to the reaction product of hypolinolenic acid, dimer acid belonging to the reaction product of acrylic acid and oleic acid, trimer acid belonging to the reaction product of acrylic acid and oleic acid, dimer acid belonging to the reaction product of acrylic acid and linolenic acid, trimer acid of the reaction product of acrylic acid and linolenic acid, dimer acid of the reaction product of acrylic acid and linolenic acid, trimer acid of the reaction product of acrylic acid and linolenic acid, dimer acid of the reaction product of methacrylic acid and oleic acid, trimer acid of the reaction product of methacrylic acid and oleic acid, dimer acid of the reaction product of methacrylic acid and linolenic acid, trimer acid of the reaction product of methacrylic acid and linolenic acid, dimer acid of the reaction product of methacrylic acid and linolenic acid, trimer acid of the reaction product of oleic acid and linolenic acid, dimer acid of the reaction product of oleic acid and linolenic acid, trimer acid of the reaction product of linolenic acid and linolenic acid, dimer acid of the reaction product of linolenic acid and linolenic acid, trimer acid of the reaction product of linolenic acid and linolenic acid, hydrogenated dimer acid of the hydrogenated products of the above dimer acids, hydrogenated trimer acid of the hydrogenated products of the above trimer acids, etc.

For example, the dimer acid, which is the reaction product of oleic acid and linoleic acid, is a dimer with 36 carbon atoms. Furthermore, the trimer acid, which is the reaction product of oleic acid and linoleic acid, is a trimer with 54 carbon atoms.

Other organic acid-based activators can be used alone or in combination of two or more.

[Amine Activator]

Examples of amine-based activators include rosinamine, azoles, guanidines, alkylamine compounds, and aminoalcohol compounds.

Rosinamines include those listed above in <rosin>.

Examples of the 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-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole trimellitate, 1-cyanoethyl-2-phenylimidazole trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-trimethylammonium ester, , 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-tri , 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-tri , 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-tri 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-triazol , 2,4-diamino-6-vinyl-s-tri Isocyanuric acid adduct, 2,4-diamino-6-methacryloyloxyethyl-s-tri , epoxy-imidazole adducts, 2-methylbenzimidazole, 2-octylbenzimidazole, 2-pentylbenzimidazole, 2-(1-ethylpentyl)benzimidazole, 2-nonylbenzimidazole, 2-(4-thiazolyl)benzimidazole, benzimidazole, 1,2,4-triazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-pentylphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-tert-octylphenol], 6-(2-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, and the like.

Examples of guanidines include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanidine, 1,3-di-o-cumylguanidine, and 1,3-di-o-cumyl-2-propionylguanidine.

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

Examples of amino alcohol compounds include N,N,N’,N’-tetrakis(2-hydroxypropyl)ethylenediamine and monoisopropanolamine.

Amine-based activators can be used alone or as a mixture of two or more.

[Halogen Activator]

Examples of halogen compounds include amine hydrochlorides and organic halogen compounds other than amine hydrochlorides.

Amine hydrohalides are compounds formed by reacting amines with hydrogen halides. Examples of amines include those listed in "Amine Activators." Examples of hydrogen halides include chlorine, bromine, and iodine hydrides.

More specifically, examples of amine hydrochlorides include cyclohexylamine hydrobromide, hexadecylamine hydrobromide, stearylamine hydrobromide, ethylamine hydrobromide, 1,3-diphenylguanidine hydrobromide, ethylamine hydrobromide, stearylamine hydrobromide, diethylaniline hydrobromide, diethanolamine hydrobromide, 2-ethylhexylamine hydrobromide, pyridine hydrobromide, isopropylamine hydrobromide, diethylamine hydrobromide, and dimethylamine hydrobromide. , dimethylamine hydrochloride, pinoresinamine hydrobromide, 2-ethylhexylamine hydrochloride, isopropylamine hydrochloride, cyclohexylamine hydrochloride, 2-methylpiperidinium hydrobromide, 1,3-diphenylguanidine hydrochloride, dimethylbenzylamine hydrochloride, hydrazine hydrobromide, dimethylcyclohexylamine hydrochloride, trinonylamine hydrobromide, diethylaniline hydrobromide, 2-diethylaminoethanol hydrobromide, 2-diethylaminoethanol hydrochloride, ammonium chloride, diphenylamine hydrochloride Allylamine hydrochloride, diallylamine 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-phenyl Imidazole hydrobromide, 4-benzylpyridinium hydrobromide, L-glutamine hydrochloride, N-methylfolin hydrochloride, betaine hydrochloride, 2-methylpiperidinium hydroiodate, cyclohexylamine hydroiodate, 1,3-diphenylguanidine hydrofluoride, diethylamine hydrofluoride, 2-ethylhexylamine hydrofluoride, cyclohexylamine hydrofluoride, ethylamine hydrofluoride, pinoresinamine hydrofluoride, cyclohexylamine tetrafluoroborate, and dicyclohexylamine tetrafluoroborate, etc.

Furthermore, as halogen compounds, for example, salts formed by reacting amines with tetrafluoroboric acid (HBF ₄ ) or complexes formed by reacting amines with boron trifluoride (BF ₃ ) can also be used. Examples of the complexes include boron trifluoride-piperidine.

Examples of organic halogen compounds other than amine hydrohalides include halogenated aliphatic compounds. Halogenated aliphatic alkyl groups are those in which some or all of the hydrogen atoms constituting an aliphatic alkyl group are replaced by halogen atoms.

Examples of 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, and trans-2,3-dibromo-2-butene-1,4-diol.

Examples of halogenated heterocyclic compounds include the compounds represented by the following general formula (2).

R ¹¹ -(R ¹² ) _n (2)

[In the formula, R ¹¹ represents an n-valent heterocyclic group. R ¹² represents a halogenated aliphatic hydrocarbon group.]

Examples of heterocyclic rings in the n-valent heterocyclic group in ^R11 include ring structures formed by substituting a portion of the carbon atoms constituting an aliphatic hydrocarbon ring or an aromatic hydrocarbon ring with heteroatoms. Examples of heteroatoms in the heterocyclic ring include oxygen atoms, sulfur atoms, and nitrogen atoms. The heterocyclic ring is preferably a 3- to 10-membered ring, more preferably a 5- to 7-membered ring. Examples of heterocyclic rings include isocyanurate rings.

The halogenated aliphatic alkyl group in R ¹² preferably has 1 to 10 carbon atoms, more preferably 2 to 6 carbon atoms, and even more preferably 3 to 5 carbon atoms. Furthermore, R ¹² is preferably a brominated aliphatic alkyl group, a chlorinated aliphatic alkyl group, more preferably a brominated aliphatic alkyl group, and even more preferably a brominated saturated aliphatic alkyl group.

Examples of halogenated heterocyclic compounds include tris-(2,3-dibromopropyl) isocyanate.

Examples of organic halogen compounds other than amine hydrohalides include: carboxyl iodides such as 2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, and 5-iodoaminobenzoic acid; carboxyl chlorides such as 2-chlorobenzoic acid and 3-chloropropionic acid; carboxyl bromides such as 2,3-dibromopropionic acid, 2,3-dibromosuccinic acid, and 2-bromobenzoic acid; hydrobromic acid, carbon tetrabromide, fatty acid methyl ester chlorides (paraffin chloride), and tetrabromoethane.

Halogen compounds may be used alone or in combination of two or more.

<Solvent(S)>

Examples of the solvent (S) include water, alcohol-based solvents, glycol ether-based solvents, and terpene alcohols.

Examples of alcoholic solvents include ethanol, 1-propanol, 2-propanol, 1,2-butanediol, isoborneol, 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-trifluoromethane, 1,2-dimethyl ...yne-2,5-diol, 2,3-dimethyl-2,3-butanediol, 2-methylpentane-2,4-diol, 1,1,1-trifluoromethane, 1,2-dimethyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2,5-dimethyl-2,5-hexyne-2,5-diol, 2,3-dimethyl-2,3-butanediol, 2-methylpentane-2,4-diol, 1,1,1-trifluoromethane, 1,2-diethyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2 (Hydroxymethyl)propane, 2-ethyl-2-hydroxymethyl-1,3-propanediol, 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-decyn-4,7-diol, etc.

Examples of glycol ether solvents include diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, diethylene glycol monohexyl ether (hexanediol), diethylene glycol dibutyl ether, triethylene glycol monobutyl ether, methyl glycerol, butyl glycerol, triethylene glycol butyl methyl ether, and tetraethylene glycol dimethyl ether.

Solvents (S) can be used alone or as a mixture of two or more.

From the perspective of increasing volatility during preparatory heating, the solvent (S) preferably includes a solvent (S1) having a boiling point of 100°C or less. The boiling point of the solvent (S1) is preferably 60°C to 100°C, more preferably 70°C to 100°C, even more preferably 75°C to 100°C, and particularly preferably 80°C to 100°C.

The content of the solvent (S1) relative to the total mass of the solvent (S) (100 mass%) is preferably 70 mass% to 100 mass%, more preferably 80 mass% to 100 mass%, even more preferably 90 mass% to 100 mass%, particularly preferably 95 mass% to 100 mass%, and can be 100 mass%. By having the content of the solvent (S1) be greater than the lower limit, the volatility of the solvent (S) during preheating can be easily increased.

From the perspective of the solubility of the specific activator, the solvent (S1) having a boiling point below 100°C is preferably an alcoholic solvent.

The aforementioned alcoholic solvent preferably contains 2-propanol.

The content of the aforementioned solvent (S) in the aforementioned flux is preferably not less than 40 mass% and not more than 98 mass%, more preferably not less than 60 mass% and not more than 98 mass%, and even more preferably not less than 70 mass% and not more than 98 mass%, relative to the total amount of the aforementioned flux (100 mass%).

<Other ingredients>

The flux of this embodiment may contain other ingredients as needed, in addition to rosin, terpene phenol resin, activator, and solvent.

Other ingredients include: contact detackifiers, resin components other than rosin and terpene phenol resins, metal passivating agents, surfactants, silane coupling agents, antioxidants, colorants, etc.

Resin components other than rosin and terpene phenolic resins

Examples of resin components other than rosin-based resins include styrene resins, modified styrene resins, xylene resins, modified xylene resins, acrylic resins, polyethylene resins, acrylic-polyethylene copolymer resins, epoxy resins, and silicone resins.

Examples of modified styrene resins include styrene acrylic resin and styrene maleic acid resin. Examples of modified xylene resins include phenol-modified xylene resin, alkylphenol-modified xylene resin, phenol-modified resol-type xylene resin, polyol-modified xylene resin, and polyoxyethylene-added xylene resin.

≪Metal Passivating Agent≫

Examples of metal passivating agents include hindered phenol compounds and nitrogen compounds. The term "metal passivating agent" here refers to a compound that has the ability to prevent metal degradation by contact with a certain compound.

The so-called hindered phenol compounds refer to phenolic compounds in which at least one of the adjacent positions of the phenol has a bulky substituent (e.g., a branched or cyclic alkyl group such as a tert-butyl group).

The hindered phenol compounds are not particularly limited, and examples thereof include: bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][ethylenebis(oxyethylene)], N,N'-hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2'-methylenebis[6-(1-methylcyclohexyl)-p-cresol], 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-(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylanilino)-1,3,5-tris(2-hydroxy-3,5-di-tert-butylanilino)-1,3,5-tris(2-hydroxy-3,5-di-tert-butylanilino)-1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], , Pentaerythritol-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'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyphenyl)propionate 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]oxalamide, and compounds represented by the following chemical formulas.

(In the formula, Z is an optionally substituted alkylene group. R ¹⁰¹ and R ¹⁰² are each independently an optionally substituted alkyl group, aralkyl group, aryl group, heteroaryl group, cycloalkyl group, or heterocycloalkyl group. R ¹⁰³ and R ¹⁰⁴ are each independently an optionally substituted alkyl group.)

Examples of nitrogen compounds used in metal passivating agents include hydrazide nitrogen compounds, amide nitrogen compounds, triazole nitrogen compounds, and melamine nitrogen compounds.

The hydrazide nitrogen compound is any nitrogen compound having a hydrazide skeleton, and examples thereof include: dodecanedioic acid bis[N2-(2-hydroxybenzyl)hydrazine], N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, decanedicarboxylic acid dihydrate hydrazide, N-hydroxysalicylidene -N'-Hydroxybenzoic acid hydrazide, m-nitrobenzoic acid hydrazide, 3-aminophthalhydrazide, phthalodihydrazide, hexamethylenedihydrazide, oxadiazine (2-hydroxy-5-octylbenzylidenehydrazide), N'-benzoylpyrrolidonecarboxylic acid hydrazide, N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hydrazine, etc.

As the amide nitrogen compound, any nitrogen compound having an amide skeleton may be used, and examples thereof include N,N'-bis{2-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]ethyl}oxalamide.

The triazole nitrogen compound can be any nitrogen compound having a triazole skeleton, and examples thereof include N-(2H-1,2,4-triazol-5-yl)salinamide, 3-amino-1,2,4-triazole, and 3-(N-salinamide)amino-1,2,4-triazole.

The melamine-based nitrogen compound is any nitrogen compound having a melamine skeleton, and examples thereof include melamine and melamine derivatives. More specifically, examples thereof include melamine-based nitrogen compounds. , alkylated phenylaminotriazine , alkoxyalkylated trisaminoglycan , melamine, alkylated melamine, alkoxyalkylated melamine, N2-butyl melamine, N2,N2-diethyl melamine, N,N,N',N',N",N"-tert-(methoxymethyl) melamine, etc.

The metal passivating agent preferably comprises bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][ethylidenebis(oxyethylidene)].

Surfactants

Examples of surfactants include non-ionic surfactants, weakly cationic surfactants, etc.

Examples of non-ionic surfactants include polyethylene glycol, polyethylene glycol-polypropylene glycol copolymers, aliphatic alcohol polyoxyethylene adducts, aromatic alcohol polyoxyethylene adducts, and polyol polyoxyethylene adducts.

Examples of weakly cationic surfactants include: terminal diamine polyethylene glycol, terminal diamine polyethylene glycol-polypropylene glycol copolymers, aliphatic amine polyoxyethylene adducts, aromatic amine polyoxyethylene adducts, and polyamine polyoxyethylene adducts.

Examples of surfactants other than those mentioned above include polyoxyalkylene acetylene glycols, polyoxyalkylene glyceryl ethers, polyoxyalkylene alkyl ethers, polyoxyalkylene esters, polyoxyalkylene alkylamines, and polyoxyalkylene alkylamides.

One embodiment of the flux described above in the first aspect contains rosin, terpene phenol resin, an organic acid (A1) with an SP value of 11.00 or greater, and a solvent, and is suitable for flow soldering.

The specific organic acid (A1) is highly active and easily precipitates in the flux residue. However, the flux of this embodiment may contain the organic acid (A1). In addition to rosin, by also including a terpene phenol resin with a hydroxyl value exceeding 70 mgKOH/g, the precipitation of the organic acid (A1) in the flux residue after soldering can be further suppressed.

The reason for this effect is unclear, but it is speculated that the terpene phenol resin with a hydroxyl value exceeding 70 mgKOH/g contained in the flux of this embodiment improves the compatibility of the organic acid (A1) with the resin components in the flux residue.

[Second version]

One embodiment of the second aspect of the flux is as follows. The flux of this embodiment contains rosin, terpene phenol resin, activator, solvent (S), and other ingredients as needed.

The hydroxyl value of the terpene phenol resin is greater than 70 mgKOH/g. The activator comprises an organic acid (A2) represented by the following general formula (1). The flux of this embodiment is suitable as a flux for flow soldering.

R ¹ -COOH‧‧‧(1)

[In the formula, ^R1 represents a carbon chain alkyl group having 2 to 15 carbon atoms, an alicyclic alkyl group having 3 to 15 carbon atoms, an aromatic group, or a carboxyl group. However, the carbon chain alkyl group and the alicyclic alkyl group may each have a hydroxyl group or a carboxyl group.]

<Rosin>

Examples of rosin include those mentioned above in the first aspect.

Rosin can be used alone or as a mixture of two or more.

It is best to use rosin derivatives as rosin.

As the rosin derivative, it is preferred to use at least one selected from the group consisting of acid-modified hydrogenated rosin, acid-modified rosin, hydrogenated rosin, polymerized rosin, and rosin ester.

As the acid-modified hydrogenated rosin, acrylic acid-modified hydrogenated rosin is preferably used.

As the acid-modified rosin, acrylic acid-modified rosin is preferably used.

The content of the aforementioned rosin in the aforementioned flux is preferably not less than 1 mass% and not more than 30 mass%, more preferably not less than 2 mass% and not more than 25 mass%, and even more preferably not less than 2 mass% and not more than 20 mass%, relative to the total amount of the aforementioned flux (100 mass%).

In the solid content of the aforementioned flux, the content of the aforementioned rosin relative to the total solid content (100 mass%) is preferably not less than 10 mass% and not more than 90 mass%, more preferably not less than 20 mass% and not more than 80 mass%, and even more preferably not less than 30 mass% and not more than 75 mass%.

<Terpene phenol resin>

Examples of terpene phenolic resins include those listed above in the first aspect.

Terpene phenol resins can be used alone or in combination of two or more.

The hydroxyl value of the terpene phenol resin is greater than 70 mgKOH/g, and may be greater than 90 mgKOH/g, preferably greater than 110 mgKOH/g, more preferably greater than 130 mgKOH/g, even more preferably greater than 140 mgKOH/g, particularly preferably greater than 170 mgKOH/g, and most preferably greater than 190 mgKOH/g.

The upper limit of the hydroxyl value of the terpene phenol resin is not particularly limited as long as the effects of the present invention can be exerted, but for example, it may be 300 mgKOH/g or less, 250 mgKOH/g or less, or even 230 mgKOH/g or less.

For example, the hydroxyl value of terpene phenol resins can be greater than 70 mgKOH/g and less than 300 mgKOH/g, and can be greater than 90 mgKOH/g and less than 300 mgKOH/g, preferably greater than 110 mgKOH/g and less than 300 mgKOH/g, more preferably greater than 130 mgKOH/g and less than 300 mgKOH/g, even more preferably greater than 140 mgKOH/g and less than 300 mgKOH/g, particularly preferably greater than 170 mgKOH/g and less than 300 mgKOH/g, and can be greater than 190 mgKOH/g and less than 300 mgKOH/g.

Alternatively, the hydroxyl value of the terpene phenol resin may be greater than 70 mgKOH/g and less than 250 mgKOH/g, and may be greater than 90 mgKOH/g and less than 250 mgKOH/g, preferably greater than 110 mgKOH/g and less than 250 mgKOH/g, more preferably greater than 130 mgKOH/g and less than 250 mgKOH/g, even more preferably greater than 140 mgKOH/g and less than 250 mgKOH/g, particularly preferably greater than 170 mgKOH/g and less than 250 mgKOH/g, and may be greater than 190 mgKOH/g and less than 250 mgKOH/g.

By keeping the hydroxyl value of the terpene phenol resin above the aforementioned lower limit, the precipitation of organic acid (A1) in the flux residue after soldering can be further suppressed.

By keeping the hydroxyl value of the terpene phenol resin below the aforementioned upper limit, moisture absorption can be further reduced. This can further suppress the decrease in the flux's insulation resistance and the occurrence of migration.

The content of the terpene phenol resin in the flux is preferably not less than 0.1 mass% and not more than 20 mass%, more preferably not less than 0.2 mass% and not more than 10 mass%, and even more preferably not less than 0.5 mass% and not more than 5 mass%, relative to the total amount of the flux (100 mass%).

In the solid content of the aforementioned flux, the content of the aforementioned terpene phenol resin relative to the total solid content (100 mass%) is preferably 3 mass% to 50 mass%, more preferably 4 mass% to 40 mass%, and even more preferably 5 mass% to 30 mass%.

By keeping the terpene phenol resin content above the aforementioned lower limit, the precipitation of the activator in the flux residue after soldering can be further suppressed.

By keeping the terpene phenol resin content below the aforementioned upper limit, the risk of the flux viscosity becoming excessively high can be reduced.

The mixing ratio of rosin to terpene phenol resin refers to the mass ratio expressed as rosin/terpene phenol resin, that is, the ratio of the rosin content to the terpene phenol resin content. It is preferably 0.5 to 20, more preferably 1 to 10, and even more preferably 1.5 to 8.

<Activator>

《Specific Activator》

The flux of this embodiment contains an organic acid (A2) represented by the following general formula (1) as a specific activator.

R ¹ -COOH‧‧‧(1)

[In the formula, ^R1 represents a carbon chain alkyl group having 2 to 15 carbon atoms, an alicyclic alkyl group having 3 to 15 carbon atoms, an aromatic group, or a carboxyl group. However, the carbon chain alkyl group and the alicyclic alkyl group may each have a hydroxyl group or a carboxyl group.]

The aforementioned chain alkyl group in R ¹ may be a straight chain or a branched chain.

The aforementioned chain alkyl group and the aforementioned alicyclic alkyl group may be a saturated alkyl group or an unsaturated alkyl group, with saturated alkyl groups being preferred.

The carbon number of the aforementioned chain alkyl group is preferably 2 to 12, more preferably 3 to 9, particularly preferably 3 to 7, and most preferably 3 to 5.

Examples of the aforementioned chain hydrocarbon groups 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.

The carbon number of the aforementioned alicyclic alkyl group is preferably 3 to 12, more preferably 4 to 12, and even more preferably 4 to 8.

Examples of the aforementioned alicyclic hydrocarbon groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, and cycloundecyl.

Examples of the aforementioned aromatic group in ^R1 having at least one aromatic ring include aromatic hydroxyl rings such as benzene, naphthalene, anthracene, and phenanthrene, aromatic heterocyclic rings in which a portion of the carbon atoms constituting the aromatic hydroxyl ring are substituted with heteroatoms, and condensed rings formed by condensing an aromatic hydroxyl ring with an aromatic heterocyclic ring.

When the aforementioned aromatic group in R ¹ has a substituent, examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aromatic alkyl group, a carboxyl group, a hydroxyl group, an amino group, and a halogen atom, preferably a carboxyl group or a hydroxyl group.

The organic acid (A2) represented by the general formula (1) above can be exemplified by dicarboxylic acids, hydroxycarboxylic acids, aromatic carboxylic acids, etc.

Examples of dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioc acid, hexadecanedioic acid, 2,4-diethylglutaric acid, and 1,3-cyclohexanedicarboxylic acid.

Examples of hydroxycarboxylic acids include 2,2-bis(hydroxymethyl)propionic acid and 2,2-bis(hydroxymethyl)butanoic acid.

Examples of aromatic carboxylic acids include picolinic acid and pyridinedicarboxylic acid.

Among the organic acids (A2) represented by the general formula (1), preferably, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid or 2,2-bis(hydroxymethyl)propionic acid is selected, more preferably, succinic acid, glutaric acid, adipic acid or 2,2-bis(hydroxymethyl)propionic acid is selected, and even more preferably, succinic acid or 2,2-bis(hydroxymethyl)propionic acid is selected.

The organic acid (A2) represented by the general formula (1) may be used alone or in combination of two or more.

The content of the aforementioned organic acid (A2) in the aforementioned flux is preferably not less than 0.05 mass% and not more than 6 mass%, more preferably not less than 0.1 mass% and not more than 4 mass%, and even more preferably not less than 0.1 mass% and not more than 3 mass%, relative to the total mass of the flux (100 mass%).

In the solid content of the flux, the content of the organic acid (A2) relative to the total solid content (100 mass%) is preferably 0.5 mass% to 50 mass%, more preferably 0.5 mass% to 40 mass%, and even more preferably 1 mass% to 40 mass%.

By setting the content of the organic acid (A2) above the lower limit, the wettability of the flux can be further improved.

By keeping the content of the organic acid (A2) below the aforementioned upper limit, the precipitation of the activator in the flux residue after soldering can be further suppressed.

The mixing ratio of the organic acid (A2) to the terpene phenol resin refers to the mass ratio of organic acid (A2) to terpene phenol resin, that is, the ratio of the organic acid (A2) to the content of the terpene phenol resin (100 parts by mass). The mixing ratio can be from 1 part by mass to 600 parts by mass, preferably from 2 parts by mass to 600 parts by mass, more preferably from 1 part by mass to 400 parts by mass, even more preferably from 1 part by mass to 200 parts by mass, particularly preferably from 1 part by mass to 100 parts by mass, and most preferably from 1 part by mass to 50 parts by mass.

By setting the content ratio of the organic acid (A2) to be above the aforementioned lower limit, weldability can be improved.

By keeping the content ratio of the organic acid (A2) below the aforementioned upper limit, the precipitation of the organic acid (A2) in the flux residue after soldering can be further suppressed.

《Other Activators》

Other activators include those mentioned above in the first aspect.

<Solvent(S)>

The solvent (S) may include those mentioned above in the first aspect.

Solvents (S) can be used alone or as a mixture of two or more.

From the perspective of increasing volatility during preparatory heating, the solvent (S) preferably includes a solvent (S1) having a boiling point of 100°C or less. The boiling point of the solvent (S1) is preferably 60°C to 100°C, more preferably 70°C to 100°C, even more preferably 75°C to 100°C, and particularly preferably 80°C to 100°C.

The content of the solvent (S1) relative to the total mass of the solvent (S) (100 mass%) is preferably 70 mass% to 100 mass%, more preferably 80 mass% to 100 mass%, even more preferably 90 mass% to 100 mass%, particularly preferably 95 mass% to 100 mass%, and can be 100 mass%. By having the content of the solvent (S1) be at least the lower limit, the volatility of the solvent (S) during preheating can be easily increased.

The aforementioned alcoholic solvent preferably includes 2-propanol.

The content of the aforementioned solvent (S) in the aforementioned flux is preferably not less than 40 mass% and not more than 98 mass%, more preferably not less than 60 mass% and not more than 98 mass%, and even more preferably not less than 70 mass% and not more than 98 mass%, relative to the total amount of the aforementioned flux (100 mass%).

<Other ingredients>

Other ingredients include those listed above in the first aspect.

One embodiment of the second aspect of the flux described above contains rosin, terpene phenol resin, the organic acid (A2) represented by the general formula (1), and a solvent, and is suitable for flow soldering.

The specific organic acid (A2) is highly active and easily precipitates in the flux residue. However, even though the flux of this embodiment contains the organic acid (A2), in addition to rosin, it also contains a terpene phenol resin with a hydroxyl value exceeding 70 mgKOH/g. This further suppresses the precipitation of the organic acid (A2) in the flux residue after soldering.

The reason for this effect is unclear, but it is speculated that the terpene phenol resin with a hydroxyl value exceeding 70 mgKOH/g contained in the flux of this embodiment improves the compatibility of the organic acid (A2) with the resin components in the flux residue.

(Method for manufacturing a joint)

The method for manufacturing a joint body according to the third aspect comprises the following steps: soldering a solder alloy onto the surface of a substrate treated with the flux according to the first or second aspect to obtain a joint body.

The following describes one embodiment of the method for manufacturing the joint body of the third aspect.

The manufacturing method of the joint body of this embodiment sequentially comprises a parts mounting step, a flux coating step, a preliminary heating step, and a welding step.

In the component installation step, the component is mounted on the substrate.

Examples of substrates include printed wiring boards, etc.

Examples of components include integrated circuits, transistors, diodes, resistors, and capacitors.

In the flux application step, the flux of the above-described embodiment is applied to the soldering surface of the substrate on which the components are mounted.

Examples of flux application equipment include spray-type flux equipment and foam-type flux equipment. Of these, spray-type flux equipment is preferred from the perspective of stable application volume.

From the perspective of solderability, the flux coating amount is preferably 30 to 180 mL/m ² , more preferably 40 to 150 mL/m ² , and particularly preferably 50 to 120 mL/m ² .

During the soldering process, the soldering surface of the substrate with the components mounted thereon is brought into contact with the molten solder, which melts the solder alloy.

The method for bringing the molten solder into contact with the soldering surface is not particularly limited, as long as it allows the molten solder to contact the substrate. Examples of such methods include spraying and dipping.

The jet method is a method in which the soldering surface of the substrate with the components mounted on it comes into contact with the sprayed molten solder. The immersion method is a method in which the soldering surface of the substrate with the components mounted on it comes into contact with the liquid surface of the stationary molten solder.

As the solder alloy, a solder alloy with a known composition can be used.

The solder alloy can be a single Sn solder, or a Sn-Ag system, Sn-Cu system, Sn-Ag-Cu system, Sn-Bi system, Sn-In system, etc., or a solder alloy formed by adding Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, P, etc. to these alloys.

The solder alloy can be a Sn-Pb system, or a solder alloy made by adding Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, P, etc. to the Sn-Pb system.

The solder alloy is preferably Pb-free.

During the soldering step, the soldering conditions simply need to be appropriately set according to the melting point of the solder. For example, when using a Sn-Ag-Cu solder alloy, the molten solder temperature is preferably between 230 and 280°C, more preferably between 250 and 270°C.

In the preheating step, the substrate with the components mounted thereon is preheated. The temperature of the heated substrate in the preheating step is preferably 80 to 130°C, more preferably 90 to 120°C.

According to the above-described method for manufacturing a bonded structure according to this embodiment, the precipitation of the activator in the flux residue on the resulting bonded structure can be further suppressed. This reduces the risk of activator migration within the resulting bonded structure.

Other implementation types:

The flux used in the above-mentioned embodiments is suitable for flow soldering, but the fluxes in the first and second embodiments are not limited to this purpose and can also be used for reflow soldering.

[Example]

The present invention is described below by way of examples, but the present invention is not limited to the following examples.

<Preparation of the mixed solution>

(Test Examples 1 to 35)

Prepare the test mixtures using the compositions shown in Tables 1 to 7. In Tables 1 to 7, the values represent the weight (g) of each component.

The raw materials used are listed below.

Activator:

2,2-Dihydroxymethylpropionic acid (SP value: 16.12)

Succinic acid (SP value: 13.21)

Glutaric acid (SP value: 12.61)

Adipic acid (SP value: 12.15)

Suberic acid (SP value: 11.49)

Sebacic acid (SP value: 11.04)

4-tert-Butylbenzoic acid (SP value: 10.52)

Terpene phenol resin:

Resin A 200±10mgKOH/g

Resin B 150±10mgKOH/g

Resin C 120±10mgKOH/g

Resin D 100±10mgKOH/g

Resin E 60±10mgKOH/g

<Assessment>

Evaluation of the Solubility of Activators

An activator was added to resins A through E to create a mixture. The mixture was heated to above the softening point of the resin and then cooled to room temperature. The presence of precipitates in the mixture during heating and after cooling was examined and evaluated according to the following criteria. The results are presented in Tables 1 through 7.

Judgment Criteria:

A: The activator dissolves in the mixture upon heating, and no precipitate is visible upon cooling.

B: Even when heated, the activator does not dissolve in the mixture, and a precipitate is visible after cooling.

[Table 1]

As shown in Table 1, in Test Examples 1 and 2 containing either succinic acid, Resin A, or Resin B, no precipitate was observed after cooling.

In contrast, in Test Examples 3 to 5 containing succinic acid and any of Resins C to E, precipitates were observed after cooling.

[Table 2]

As shown in Table 2, in Test Example 6 containing glutaric acid and Resin A, no precipitate was observed after cooling.

In contrast, in Test Examples 7 to 10 containing glutaric acid and any of Resins B to E, precipitates were observed after cooling.

[Table 3]

As shown in Table 3, in Test Example 11 containing adipic acid and Resin A, no precipitate was observed after cooling.

In contrast, in Test Examples 12 to 15 containing adipic acid and any of Resins B to E, precipitates were observed after cooling.

[Table 4]

As shown in Table 4, in Test Examples 16 to 19 containing suberic acid and any of Resins A to D, no precipitate was observed after cooling.

In contrast, in Test Example 20, which contained suberic acid and Resin E, precipitates were observed after cooling.

[Table 5]

As shown in Table 5, in Test Examples 21 to 24 containing sebacic acid and any of Resins A to D, no precipitate was observed after cooling.

In contrast, in Test Example 25, which contained sebacic acid and Resin E, precipitates were observed after cooling.

[Table 6]

As shown in Table 6, in Test Examples 26 and 27 containing 2,2-dihydroxymethylpropionic acid and either Resin A or Resin B, no precipitate was observed after cooling.

In contrast, in Test Examples 28 to 30 containing 2,2-dihydroxymethylpropionic acid and any of Resins C to E, precipitates were observed after cooling.

[Table 7]

As shown in Table 7, in Test Examples 31 to 35 containing 4-tert-butylbenzoic acid and any of Resins A to E, no precipitate was observed after cooling.

From the above results, it is clear that the organic acid (A1) with an SP value of 11.00 or greater and the organic acid (A2) represented by the above general formula (1) are dissolved by selecting a terpene phenol resin with a hydroxyl value exceeding 70 mgKOH/g.

Furthermore, it is clear that the organic acid (A1) with an SP value of 11.00 or more and the organic acid (A2) represented by the above general formula (1) cannot dissolve terpene phenol resins with a hydroxyl value of 70 mgKOH/g or less.

<Preparation of flux>

(Examples 1 to 23, Comparative Examples 1 to 2, Reference Examples 1 to 2)

The fluxes for the Examples and Comparative Examples were prepared according to the compositions shown in Table 7 below. The compositions in Table 7 are expressed in mass % with the total amount of the flux as 100 mass %.

Specific activators:

2,2-Dihydroxymethylpropionic acid (SP value: 16.12)

Succinic acid (SP value: 13.21)

Glutaric acid (SP value: 12.61)

Adipic acid (SP value: 12.15)

Suberic acid (SP value: 11.49)

Sebacic acid (SP value: 11.04)

Other activators: 4-tert-butylbenzoic acid (SP value: 10.52)

Terpene phenol resin:

Resin A 200±10mgKOH/g

Resin B 150±10mgKOH/g

Resin C 120±10mgKOH/g

Resin D 100±10mgKOH/g

Resin E 60±10mgKOH/g

Rosin: Acrylic acid modified hydrogenated rosin, acrylic acid modified rosin, hydrogenated rosin, polymerized rosin, rosin ester

Solvent: 2-propanol

Other resin ingredients: silicone

Antioxidant: Quinoline compounds

<Preparation of molten solder>

As a master alloy, a cast ingot consisting of 3% by mass of Ag, 0.5% by mass of Cu, and the balance of Sn is prepared.

The ingot is dissolved to prepare molten solder.

<Assessment>

《Precipitation on the Surface of Flux Residue》

Verification method:

By spraying each example of flux onto the substrate, a pre-treated substrate was obtained.

Then, flow soldering is performed on the pre-treated substrate by contacting it with molten solder in a nitrogen environment.

The presence of flux residue precipitation on the substrate was determined and evaluated based on the following criteria. The results are presented in Tables 8 to 10.

Judgment Criteria:

A: No precipitates are visible on the surface of the flux residue.

B: A small amount of precipitate can be seen on the surface of the flux residue.

C: A large amount of precipitates can be seen on the surface of the flux residue.

In the evaluation results, the amount of precipitates on the surface of the flux residue increases from A to C. Fluxes rated A to B pass, while fluxes rated C fail.

[Table 8]

[Table 9]

[Table 10]

The fluxes of Examples 1 to 23, which contain a highly active specific organic acid and a terpene phenol resin with a hydroxyl value exceeding 70 mgKOH/g, were rated A or B for precipitation on the surface of the flux residue.

In contrast, the fluxes of Comparative Examples 1 and 2, which contain a highly active specific organic acid and a terpene phenol resin with a hydroxyl value of 70 mgKOH/g or less, received a C rating for precipitation on the surface of the flux residue.

Furthermore, the flux of Reference Example 2, which contains a low-activity organic acid and a terpene phenol resin, received an A rating for precipitation on the surface of the flux residue, even though the hydroxyl value of the terpene phenol resin was below 70 mgKOH/g.

That is, according to the present invention, even when containing a highly active specific organic acid, the precipitation of flux residue can be suppressed by including a terpene phenol resin with a hydroxyl value exceeding 70 mgKOH/g.

[Industrial Availability]

According to the present invention, a flux and a method for manufacturing a joint body can be provided that further suppress the precipitation of an activator in the flux residue after soldering. The flux is suitable for flow soldering. Furthermore, the flux is suitable for soldering electronic substrates used in high-temperature and high-humidity environments.

Claims (11)

A flux comprising rosin, a terpene phenol resin, and an activator. The terpene phenol resin has a hydroxyl value of 140 mgKOH/g or greater. The activator comprises an organic acid (A1) having a solubility parameter (SP value) of 12.00 or greater. The flux as claimed in claim 1, wherein the content of the organic acid (A1) is not less than 0.05 mass % and not more than 6 mass % relative to the total mass of the flux (100 mass %). The flux according to claim 1 or 2, wherein the content ratio (mass ratio) of the organic acid (A1) relative to the content (100 parts by mass) of the terpene phenol resin is not less than 1 part by mass and not more than 600 parts by mass. A soldering flux comprises rosin, a terpene phenol resin, and an activator, wherein: The terpene phenol resin has a hydroxyl value of 140 mgKOH/g or greater, and The activator comprises one or more organic acids (A2) selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, 2,4-diethylglutaric acid, 1,3-cyclohexanedicarboxylic acid, 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butanoic acid, picolinic acid, and dipicolinic acid. The flux as claimed in claim 4, wherein the content of the organic acid (A2) is not less than 0.05 mass % and not more than 6 mass % relative to the total mass of the flux (100 mass %). The flux according to claim 4 or 5, wherein the content ratio (mass ratio) of the organic acid (A2) relative to the content (100 parts by mass) of the terpene phenol resin is not less than 1 part by mass and not more than 600 parts by mass. The flux as claimed in claim 1 or 2, wherein the content of the terpene phenol resin is not less than 0.1 mass % and not more than 20 mass % relative to the total mass of the flux (100 mass %). The flux as described in claim 3, wherein the content of the terpene phenol resin is not less than 0.1 mass% and not more than 20 mass% relative to the total mass of the flux (100 mass%). The flux as described in claim 4 or 5, wherein the content of the terpene phenol resin is not less than 0.1 mass% and not more than 20 mass% relative to the total mass of the flux (100 mass%). The flux as described in claim 6, wherein the content of the terpene phenol resin is not less than 0.1 mass% and not more than 20 mass% relative to the total mass of the flux (100 mass%). A method for manufacturing a joint body comprises the following steps: soldering a solder alloy on the surface of a substrate treated with the flux described in any one of claims 1 to 10 to obtain a joint body.