JP2022052939A - Flux and solder paste - Google Patents

Abstract

To prevent residual cracking in flux residues.SOLUTION: The present invention discloses a flux composition comprising one or more first rosin compounds selected from the group consisting of imidized maleic acid-modified rosin and its hydrogenated product. The present invention discloses a flux for soldering a solder alloy, comprising the flux composition. The present invention discloses a solder paste comprising the flux and a solder alloy.SELECTED DRAWING: None

Description

The present invention relates to a flux composition, a flux and a solder paste.

Fixing and electrical connection of electronic components in electronic devices, such as mounting electronic components on printed circuit boards, is generally performed by soldering, which is advantageous in terms of cost and reliability.
Commonly used methods for soldering include (i) a flow soldering method in which a printed circuit board and electronic components are brought into contact with molten solder for soldering, and (ii) solder paste, solder preform, or solder balls. There is a reflow soldering method in which the solder of the form is remelted in a reflow furnace and soldered.

In soldering, flux, which is an auxiliary agent that makes it easier for solder to adhere to printed circuit boards and electronic components, may be used. The flux has a useful effect in soldering, for example, as follows.
(1) Metal surface cleaning action: Chemically removes the oxide film on the metal surface of printed boards and electronic parts to clean the surface so that soldering is possible (2) Anti-oxidation action: Cleaning The action of covering the metal surface that has become formed during soldering to block contact with oxygen and preventing the metal surface from being reoxidized by heating (3) The action of lowering the interfacial tension: The surface tension of the molten solder is reduced. And the action of improving the wettability of the metal surface by soldering

As the flux, a flux using a rosin derivative is known. For example, Patent Document 1 describes that a rosin derivative compound obtained by dehydrating and condensing a rosin-based carboxyl group-containing resin and a dimer acid derivative flexible alcohol compound is used as a flux for soldering.

Japanese Unexamined Patent Publication No. 2014-185298

As mentioned above, the flux has a useful effect in soldering. However, the use of flux was not without problems.
For example, in the conventional flux, "residue cracking" may occur in the flux residue after soldering. Such cracks can be problematic in terms of reliability of printed circuit boards and electronic components.

The present invention has been made in view of such circumstances. One of the objects of the present invention is to suppress the cracking of the flux residue.

The present inventors have completed the inventions provided below and solved the above problems.

According to the present invention
A flux composition comprising an imidized maleic acid-modified rosin and one or more first rosin compounds selected from the group consisting of hydrogenated products thereof is provided.

Further, according to the present invention,
A flux for soldering a solder alloy, which comprises the above flux composition, is provided.

Further, according to the present invention,
A solder paste containing the above flux and a solder alloy is provided.

According to the present invention, it is possible to suppress the residual cracking of the flux residue.

Hereinafter, embodiments of the present invention will be described in detail.
In the present specification, the notation "XY" in the description of the numerical range indicates X or more and Y or less unless otherwise specified. For example, "1 to 5% by mass" means "1% by mass or more and 5% by mass or less".
In the chemical formula in the present specification, the bond represented by the wavy line indicates that the configuration of the bond is not specified. In other words, each compound represented by each of the general formulas described below may be a racemate or a single compound having a specific configuration.
In the notation of a group (atomic group) in the present specification, the notation that does not indicate whether it is substituted or unsubstituted includes both those having no substituent and those having a substituent. For example, the "alkyl group" includes not only an alkyl group having no substituent (unsubstituted alkyl group) but also an alkyl group having a substituent (substituted alkyl group).
The notation "(meth) acrylic" herein represents a concept that includes both acrylic and methacrylic. The same applies to similar notations such as "(meth) acrylate".

<Composition for flux>
The composition for flux of the present embodiment contains one or more first rosin compounds selected from the group consisting of imidized maleic acid-modified rosin and hydrogenated products thereof.
According to the findings of the present inventors, when the flux contains the first rosin compound, the flux residue after soldering becomes moderately soft, so that cracking of the residue is suppressed.

Specifically, the first rosin compound is a compound having a partial structure represented by the following general formula (1-1) or (1-2), and a hydrogenated product of this compound (carbon-in the general formula). It contains one or more compounds selected from the group consisting of (compounds with hydrogen added to carbon double bonds).

In the above general formula, * represents a bond with another chemical structure.

Preferably, the first rosin compound is a compound represented by the following general formula (1a-1) or (1a-2) and a hydrogenated product thereof (a compound in which hydrogen is added to a carbon-carbon double bond in the general formula). ) Contains one or more compounds selected from the group consisting of.

In the above general formula, R independently represents a linear or branched alkyl group, an alkylene glycol group, or a terminally modified polyalkylene oxide group. When R is any of these groups, the flux residue after soldering tends to be sufficiently soft.
In each group of R, the hydrogen atom may be substituted with an arbitrary substituent.

The alkylene glycol group of R is preferably a monovalent group represented by the following formula (i). In formula (i), R ¹ is an independently linear or branched alkylene group having 1 to 4 carbon atoms, and n is an integer of 1 to 500.
H- (OR ¹ ) _n- (i)

The terminal-modified polyalkylene oxide group of R is preferably a monovalent group represented by the following formula (ii). In formula (ii), R ¹ is an independently linear or branched alkylene group having 1 to 4 carbon atoms, and X is an amino group, a linear or branched alkyl ester group having 1 to 40 carbon atoms, or carbon. It is a linear or branched alkyl ether group of the number 1 to 40, and n is an integer of 0 to 500.
X-R ^1- (OR ¹ ) _n- (ii)

The number of carbon atoms of the alkyl group represented by R is not particularly limited, but is preferably 1 to 54, more preferably 4 to 24, still more preferably 8 to 22, and particularly preferably 12 to 22.
The carbon number of the alkylene glycol group and the terminal-modified polyalkylene oxide group represented by R is not particularly limited, but is preferably 1 to 500, more preferably 4 to 24, still more preferably 8 to 22, and particularly preferably 12 to 22. be.
In the formula (i) and the formula (ii), the carbon number of the alkyl portion of X is preferably 1 to 24, and the carbon number of ^R1 is preferably 1 to 3. Further, in the formula (i) and the formula (ii), n is preferably 1 to 500, more preferably 1 to 100, and further preferably 1 to 10.

Terminal-modified polyalkylene oxide groups include polyethylene glycol, polypropylene glycol, and the hydroxyl end of polyalkylene glycol such as a copolymer of ethylene oxide and propylene oxide, such as cetyl alcohol, stearyl alcohol, and behenyl alcohol. A group to which an alcohol having 1 to 40 carbon atoms or a carboxylic acid having 1 to 40 carbon atoms such as palmitic acid, stearic acid, and behenic acid is added; and a polyalkylene such as a copolymer of ethylene oxide and propylene oxide. Examples thereof include a group in which the hydroxyl end of glycol is modified to an amino group.

The molecular weight of the first rosin compound is, for example, 1000 or less, preferably 850 or less, and more preferably 700 or less. By not increasing the molecular weight too much, the flux is less likely to become hard, and residual cracking is further suppressed.

The composition for flux of the present embodiment further preferably contains one or more second rosin compounds selected from the group consisting of maleic acid-modified rosin amides and hydrogenated products thereof. As a result, residual cracking is further suppressed. Although the details are unknown, probably, the flux composition of the present embodiment is a mixture of the first rosin compound and the second rosin compound, so that the flux residue after soldering is sufficiently softened. it is conceivable that.

Specifically, the second rosin compound is a compound having a partial structure represented by the following general formulas (2-1), (2-2), (3-1) or (3-2) and a hydrogenation thereof. It contains one or more compounds selected from the group consisting of compounds (compounds in which hydrogen is added to a carbon-carbon double bond in the general formula).

In the above general formula, * represents a bond with another chemical structure.

Preferably, the second rosin compound is selected from the group consisting of compounds represented by the following general formulas (2a-1), (2a-2), (3a-1) or (3a-2) and hydrogenated products thereof. Includes 1 or 2 or more.

In the above general formula, R represents a linear or branched alkyl group, an alkylene glycol group, or a terminally modified polyalkylene oxide group, which may be substituted independently of each other. Specific examples and preferred embodiments of these groups are the same as those of the general formulas (1a-1) and (1a-2).

The flux composition of the present embodiment contains the compound represented by the general formula (1a-1) or (1a-2) as the first rosin compound, and the general formula (2a-1) as the second rosin compound. , (2a-2), (3a-1) or (3a-2), if both are included, R in the general formula (1a-1) or (1a-2), and It is preferable that R in the general formula (2a-1), (2a-2), (3a-1) or (3a-2) is common. This is because of the ease of synthesis and the like.

The molecular weight of the second rosin compound is, for example, 1000 or less, preferably 850 or less, and more preferably 700 or less. By not increasing the molecular weight too much, the flux is less likely to become hard, and residual cracking is further suppressed.

When the composition for flux of the present embodiment contains both the first rosin compound and the second rosin compound, the first rosin compound and the second rosin compound are used from the viewpoint of sufficiently obtaining the effect of "containing both". The mass ratio is, for example, 1st rosin compound: 2nd rosin compound = 1: 99 to 99: 1, specifically 5: 95 to 95: 5.
The mass ratio of the first rosin compound to the second rosin compound can be known, for example, by using the mass spectrometric spectrum as a clue.

Examples of the raw material of the maleic acid-modified rosin, which is the raw material of the first rosin compound and the second rosin compound, include gum rosin, tall oil rosin, wood rosin, and purified products (purified rosin) thereof. In addition, as raw material rosin, raw pine tar and commercial products as described in "DF Zinkel, J. Russell ed., Translated by Yoshihiro Hasegawa (1993), Chemistry Production / Chemistry / Applications of Pine, 361-362". Gumrosin may be used. The first rosin compound and the second rosin compound can be obtained by reacting these raw materials with an appropriate amine compound (by appropriately selecting the reaction conditions, the first rosin compound and the second rosin compound can be obtained. You can also get a mixture).

<Flux>
The flux of the present embodiment contains the above-mentioned flux composition and is used for soldering a solder alloy.

The total amount (ratio) of the first rosin compound and the second rosin compound in the flux is preferably more than 0% by mass and 60% by mass or less with respect to the entire flux. The lower limit is more preferably 5% by mass or more, further preferably 10% by mass or more, still more preferably 20% by mass or more, and particularly preferably 30% by mass or more. The upper limit is more preferably 50% by mass or less, still more preferably 40% by mass or less. The larger the content of the first rosin compound or the second rosin compound, the more remarkable the effect of suppressing the residual cracking of the flux residue tends to be.

The flux of the present embodiment may contain a component (resin or the like) other than the first rosin compound and the second rosin compound contained in the above-mentioned flux composition.
As the resin, various resins conventionally used for soldering flux can be used. Examples of such resins include rosin resins, (meth) acrylic resins, polyesters, polyethylenes, polypropylenes, polyamides, styrene-maleic acid copolymers, epoxy resins, phenol resins, phenoxy resins, terpene resins, and terpenephenols. Examples include resins and mixtures thereof. Among these, rosin-based resins are generally often used. Examples of the rosin-based resin include natural rosins such as gum rosin and wood rosin, and derivatives thereof (polymerized rosin, hydrogenated rosin, disproportionated rosin, acid-modified rosin, rosin ester and the like).
As a reminder, the rosin-based resin here is a component different from the first rosin compound and the second rosin compound.

The content of the resin in the flux is not limited. When used as a flux for reflow soldering, for example, it may be in the range of 10 to 80% by mass, may be in the range of 20 to 70% by mass, or may be in the range of 30 to 60% by mass. When used as a flux for flow soldering, for example, it may be in the range of 3 to 18% by mass, may be in the range of 6 to 15% by mass, or may be in the range of 9 to 12% by mass. good.

The flux of this embodiment may contain a solvent.
Examples of the solvent include water, alcohol-based solvents, glycol ether-based solvents, terpineols and the like.
Examples of the alcohol solvent include isopropyl alcohol, 1,2-butanediol, isobornylcyclohexanol, 2,4-diethyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2, 5-Dimethyl-2,5-hexanediol, 2,5-dimethyl-3-hexine-2,5-diol, 2,3-dimethyl-2,3-butanediol, 1,1,1-tris (hydroxymethyl) ) Ether, 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, bis [2,2,2-tris (hydroxymethyl) ethyl] ether, 1-ethynyl-1-cyclohexanol, 1,4-cyclohexane Diol, 1,4-cyclohexanedimethanol, erythritol, tretol, guayacol glycerol ether, 3,6-dimethyl-4-octin-3,6-diol, 2,4,7,9-tetramethyl-5-decine- Examples thereof include 4,7-diol.
Glycol ether-based solvents include hexyl diglycol, diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, 2-methylpentane-2,4-diol, diethylene glycol monohexyl ether, diethylene glycol dibutyl ether, and triethylene glycol monobutyl ether. , Tetraethylene glycol monomethyl ether and the like.

The flux of the present embodiment may or may not further contain an organic acid, an amine, and a halogen (organic halogen compound, an amine hydrohalide) (content may be 0%). These can contribute to the activator (improvement of solderability).

When the flux of the present embodiment is used as a flux for reflow soldering, it preferably contains an organic acid in an amount of more than 0% by mass and 10% by mass or less. When used as a flux for reflow soldering, the flux of the present embodiment preferably contains amine in an amount of more than 0% by mass and 20% by mass or less, and more preferably contains an amine in an amount of more than 0% by mass and 5% by mass or less. When the flux of the present embodiment is used as a flux for soldering for reflow, it is preferable that the halogen contains an organic halogen compound in an amount of more than 0% by mass and 5% by mass or less, and an amine halide hydrohalide is contained in an amount of more than 0% by mass and 2% by mass. % Or less is preferable.
When the flux of the present embodiment is used as a flux for soldering for flow, it preferably contains an activator in an amount of 0.1% by mass or more and 12.0% by mass or less, more preferably 0.3% by mass or more and 8.0. It contains mass% or less, more preferably 0.5% by mass or more and 4.0% by mass or less.

Organic acids include glutaric acid, adipic acid, azelaic acid, eicosandioic acid, citric acid, glycolic acid, succinic acid, salicylic acid, diglycolic acid, dipicolinic acid, dibutylaniline diglycolic acid, suberic acid, sebacic acid, and thioglycol. Acid, terephthalic acid, dodecanedioic acid, parahydroxyphenylacetic acid, phenylsuccinic acid, phthalic acid, fumaric acid, maleic acid, malonic acid, lauric acid, benzoic acid, tartaric acid, tris isocyanurate (2-carboxyethyl), glycine, 1,3-Cyclohexanedicarboxylic acid, 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butanoic acid, 2,3-dihydroxybenzoic acid, 2,4-diethylglutaric acid, 2- Examples thereof include quinoline carboxylic acid, 3-hydroxybenzoic acid, malic acid, p-anisic acid, stearic acid, 12-hydroxystearic acid, oleic acid, linoleic acid and linolenic acid.

Examples of the organic acid include dimer acid, trimer acid, hydrogenated dimer acid which is a hydrogenated product of dimer acid and hydrogenated dimer acid, and hydrogenated trimeric acid which is a hydrogenated product of trimer acid and hydrogen added. ..
For example, dimer acid which is a reaction product of oleic acid and linoleic acid, trimer acid which is a reaction product of oleic acid and linoleic acid, dimer acid which is a reaction product of acrylic acid, trimer acid which is a reaction product of acrylic acid, and methacrylic acid. Dimer acid which is a reaction product of, trimer acid which is a reaction product of methacrylic acid, dimer acid which is a reaction product of acrylic acid and methacrylic acid, trimer acid which is a reaction product of acrylic acid and methacrylic acid, and a reaction product of oleic acid. A certain dimer acid, trimer acid which is a reaction product of oleic acid, dimer acid which is a reaction product of linoleic acid, trimer acid which is a reaction product of linoleic acid, dimer acid which is a reaction product of linolenic acid, and a reaction product of linolenic acid. A certain trimer acid, dimer acid which is a reaction product of acrylic acid and oleic acid, trimer acid which is a reaction product of acrylic acid and oleic acid, dimer acid which is a reaction product of acrylic acid and linoleic acid, reaction of acrylic acid and linoleic acid. Trimmer acid which is a reaction product of acrylic acid and linolenic acid, dimer acid which is a reaction product of acrylic acid and linolenic acid, trimer acid which is a reaction product of acrylic acid and linolenic acid, dimer acid which is a reaction product of methacrylic acid and oleic acid, methacrylic acid and oleic acid. Trimmer acid, which is a reaction product of methacrylic acid and linoleic acid, dimer acid, which is a reaction product of methacrylic acid and linoleic acid, trimeric acid, which is a reaction product of methacrylic acid and linoleic acid, dimer acid, which is a reaction product of methacrylic acid and linolenic acid, and methacrylic acid. Trimmer acid, which is a reaction product of linolenic acid, dimer acid, which is a reaction product of oleic acid and linolenic acid, trimeric acid, which is a reaction product of oleic acid and linolenic acid, dimer acid, which is a reaction product of linoleic acid and linolenic acid, linole. Examples thereof include trimeric acid which is a reaction product of acid and linolenic acid, hydrogenated dimer acid which is a hydrogenated product of each of the above-mentioned dimer acids, and hydrogenated trimeric acid which is a hydrogenated product of each of the above-mentioned trimer acids.

Examples of amines include monoethanolamine, diphenylguanidine, ditrilguanidine, ethylamine, triethylamine, cyclohexylamine, ethylenediamine, triethylenetetramine, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethyl. Imidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methyl Imidazole, 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, 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-phenylimidazolin, 2,4-diamino-6-vinyl-s-triazine, 2,4-diamino-6-vinyl-s-triazine isocyanuric acid adduct, 2,4-diamino-6-methacryloyloxy Ethyl-s-triazine, epoxy-imidazole admazole, 2-methylbenzoimidazole, 2-octylbenzoimidazole, 2-pentylbenzoimidazole, 2- (1-ethylpentyl) benzoimidazole, 2-nonylbenzoimidazole, 2- (4) -Thiazolyl) benzoimidazole, benzoimidazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole , 2- (2'-Hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3', 5'-di-tert-amylphenyl) Benzotriazole, 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole, 2,2'-methylenebis [6- (2H-benzotriazole-2-yl) -4-tert-octylphenol], 6 -(2-Benzotriazolyl) -4-tert-octyl-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- Benzotriazole-1-yl) methyl] imino] bisethanol, 1- (1', 2'-dicarboxyethyl) benzotriazole, 1- (2,3-dicarboxypropyl) benzotriazole, 1-[(2-2-) Ethylhexylamino) methyl] benzotriazole, 2,6-bis [(1H-benzotriazole-1-yl) methyl] -4-methylphenol, 5-methylbenzotriazole, 5-phenyltetrazole and the like can be mentioned.

Examples of the organic halogen compound include trans-2,3-dibromo-2-butene-1,4-diol, triallyl isocyanurate 6 bromide, 1-bromo-2-butanol, 1-bromo-2-propanol and 3-bromo. -1-propanol, 3-bromo-1,2-propanediol, 1,4-dibromo-2-butanol, 1,3-dibromo-2-propanol, 2,3-dibromo-1-propanol, 2,3- Dibromo-1,4-butanediol, 2,3-dibromo-1,4-butanediol, 2,3-dibromo-2-butene-1,4-diol, tris isocyanurate (2,3-dibromopropyl), Examples thereof include chlorendic anhydride.

Amine halide hydrohydrate is a compound obtained by reacting an amine with hydrogen halide.
As the amine of the amine hydrohalide, the above-mentioned amine can be used, and examples thereof include ethylamine, cyclohexylamine, ethylenediamine, triethylamine, diphenylguanidine, ditrilguanidine, methylimidazole, 2-ethyl-4-methylimidazole and the like. Will be. Examples of hydrogen halide include hydrides of chlorine, bromine, iodine and fluorine (hydrogen chloride, hydrogen bromide, hydrogen iodide, hydrogen fluoride). Further, borofluoride may be contained instead of or in combination with the amine hydrohalide hydrochloride, and examples of the borofluoride include borohydric acid and the like.
Examples of the amine halide hydride include aniline hydrogen chloride, cyclohexylamine hydrogen chloride, aniline bromide hydrogen, diphenylguanidine hydrogen bromide, ditrilguanidine hydrogen bromide, ethylamine bromide hydrogen and the like.

The flux of the present embodiment may further contain an antioxidant. Examples of the antioxidant include a hindered phenolic antioxidant, and when used as a reflow soldering flux, it is preferable that the antioxidant is contained in an amount of more than 0% by mass and 5% by mass or less, as the flow soldering flux. When used, the antioxidant is preferably contained in an amount of more than 0% by mass and 5% by mass or less, more preferably more than 0% by mass and 2% by mass or less.

The flux of the present embodiment may contain a thixotropic agent. Due to the action of the thixotropic agent, it is possible to suppress separation after the flux is mixed with the solder alloy to form a solder paste.
Examples of the thixotropic agent include a wax-based thixotropic agent, an amide-based thixotropic agent, a sorbitol-based thixotropic agent, and the like. Examples of the wax-based thixotropic agent include castor oil and the like. Examples of the amide-based thixotropic agent include monoamide-based thixotropic agents, bis-amide-based thixotropic agents, and polyamide-based thixotropic agents. Hydroxyl stearic acid amide, saturated fatty acid amide, oleic acid amide, erucic acid amide, unsaturated fatty acid amide, p-toluenemethane amide, aromatic amide, methylene bisstearate amide, ethylene bislauric acid amide, ethylene bishydroxystearate amide , Saturated fatty acid bisamide, methylene bisoleic acid amide, unsaturated fatty acid bisamide, m-xylylene bisstearic acid amide, aromatic bisamide, saturated fatty acid polyamide, unsaturated fatty acid polyamide, aromatic polyamide, substituted amaide, methylolstearic acid amide, Examples thereof include methylol amide and fatty acid ester amide. Examples of the sorbitol-based thixotropic agent include dibenzylidene-D-sorbitol, bis (4-methylbenzylidene) -D-sorbitol and the like.

Further, the flux of the present embodiment may contain an ester compound as a thixotropic agent. Examples of the ester compound include castor oil and the like.

When used as a reflow soldering flux, the total amount of the thixotropic agent contained in the flux is preferably more than 0% by mass and 15% by mass or less, and more preferably more than 0% by mass and 10% by mass or less. The content of the amide-based thixotropic agent is preferably more than 0% by mass and 12% by mass or less when used as a reflow soldering flux, and the content of the ester compound is preferably used as a reflow soldering flux. In the case, it is more than 0% by mass and 8.0% by mass or less, more preferably 0% by mass or more and 4.0% by mass or less.
When used as a flow soldering flux, the total amount of thixotropic agent contained in the flux is preferably more than 0% by mass and 3% by mass or less, and more preferably more than 0% by mass and 1% by mass or less.

<Solder paste>
The solder paste of the present embodiment contains the above-mentioned flux and a solder alloy.
The solder paste of this embodiment can be used for both flow soldering and reflow soldering. From the viewpoint of the effect of suppressing residual cracking, it is preferable to use it for reflow soldering.

The type of solder alloy (alloy composition, etc.) is not particularly limited. Specifically, Sn-Ag alloy, Sn-Cu alloy, Sn-Ag-Cu alloy, Sn-In alloy, Sn-Pb alloy, Sn-Bi alloy, Sn-Ag-Cu-Bi alloy, and the above alloy composition. Examples thereof include alloys to which Ag, Cu, In, Ni, Co, Sb, Ge, P, Fe, Zn, Ga and the like are further added.

The solder paste of the present embodiment can usually be produced by mixing the above-mentioned flux with solder alloy powder (metal powder). The mixing ratio of the flux and the metal powder is not particularly limited, and the solder paste finally obtained may have a viscosity sufficient for practical use. The mixing ratio of the flux and the metal powder is a mass ratio, typically flux: metal powder = 1: 99 to 30:70, preferably flux: metal powder = 3: 97 to 20:80, more preferably. , Flux: metal powder = 5:95 to 15:85.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above can be adopted. Further, the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like to the extent that the object of the present invention can be achieved are included in the present invention.

Embodiments of the present invention will be described in detail based on Examples and Comparative Examples. As a reminder, the invention is not limited to examples.

<Manufacturing of flux composition>
The raw material rosin (including maleic anhydride-modified rosin and / or maleic anhydride-modified hydrogenated rosin) and the monoamine compound were placed in an equimolar amount in a stainless steel beaker. Then, it was heated at 150 ° C. for 10 minutes in the atmosphere. In this way, the raw material rosin was imidized to obtain a flux composition.
By changing the monoamine compound, a composition for flux containing the components described in "Immidized maleic acid-modified rosin or hydrogenated product thereof" in the table below was obtained. For example, the N- (2-ethyl) hexyl succinimided maleic acid-modified rosin was obtained by reacting the raw material rosin with N- (2-ethyl) hexylamine.

A mass spectrum of the obtained flux composition was obtained by a time-of-flight mass spectrometer (ESI-TOF-MS). Specifically, noise-cut spectra were obtained by software processing for both the cation spectrum and the anion spectrum.
In the spectrum of anions, a peak having a mass number (m / z) 18 larger than that of the imidized maleic acid-modified rosin (first compound), which is the main reactant, was confirmed. Based on the fact that the mass number of the water molecule is 18, the reaction product obtained above also contains a certain amount of maleic acid-modified rosinamide (second compound) having a structure in which the imide ring in the first compound is opened. It was confirmed.

<Preparation of flux>
First, a flux having the composition shown in the table below was prepared. The composition ratio of each component in the table below is the amount when the total amount of flux is 100 parts by mass.

The prepared flux and the metal powder were mixed at a ratio of 11% by mass of the flux: 89% by mass of the metal powder to obtain a solder paste. As the metal powder, a Sn—Ag—Cu-based solder alloy having an Ag of 3.0% by mass, Cu of 0.5% by mass, and a balance of Sn (the average particle size of the metal powder is φ20 μm) was used.

<Evaluation of residual crack suppression>
First, the paste was printed on a substrate in which 64 rows of electrode pads having a size of 1.5 × 0.25 mm were lined up at a pitch of 0.4 mm using a metal mask having a thickness of 0.15 mm.
Next, soldering was performed using a reflow oven (reflow peak temperature is 240 ° C.).
After reflow, it was left in a normal temperature environment for 24 hours or more. Then, the number of cracks in the flux residue existing between the pads was counted and evaluated according to the following.
〇 (Good): 15 or less residual cracks × (Bad): Over 15 residual cracks

Various information is summarized in the table below.
Incidentally, as described above, the "imidized maleic acid-modified rosin or its hydrogenated product" also includes the corresponding maleic acid-modified rosin amide.

As shown in the above table, by soldering with a flux containing imidized maleic acid-modified rosin or its hydrogenated product, residual cracking could be suppressed.

<Reference: Liquid flux>
In the above, a "solder paste" was prepared using a flux containing imidized maleic acid-modified rosin or a hydrogenated product thereof, and soldering was performed using the solder paste.
On the other hand, a flux containing imidized maleic acid-modified rosin or a hydrogenated product thereof can also be used as a liquid flux for flow soldering. That is, it is also possible to use the flux of the present embodiment in an application in which the flux is spray-applied to the substrate and the molten solder is applied by a jet to join them.
The table below is an example of the composition of such a "liquid flux".

According to the present invention
An imidized maleic acid-modified rosin and one or more first rosin compounds selected from the group consisting of hydrogenated products thereof .
One or more second rosin compounds selected from the group consisting of maleic acid-modified rosin amide and hydrogenated products thereof, and
A flux for soldering a solder alloy, which comprises a flux composition comprising.
The total amount of the first rosin compound and the second rosin compound is 10% by mass or more and 60% by mass or less with respect to the entire flux.
Is provided.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above can be adopted. Further, the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like to the extent that the object of the present invention can be achieved are included in the present invention.
Hereinafter, an example of the reference form will be added.
1. 1. A composition for a flux containing one or more first rosin compounds selected from the group consisting of imidized maleic acid-modified rosin and hydrogenated products thereof.
2. 2. 1. 1. The flux composition according to the above.
The first rosin compound contains one or more compounds selected from the group consisting of compounds having a partial structure represented by the above-mentioned general formula (1-1) or (1-2) and hydrogenated products thereof. Composition for flux.
In the above general formula, * represents a bond with another chemical structure.
3. 3. 1. 1. Or 2. The flux composition according to the above.
The first rosin compound is a flux composition containing one or more compounds selected from the group consisting of the compounds represented by the above-mentioned general formula (1a-1) or (1a-2) and hydrogenated products thereof. ..
In the above general formula, R independently represents a linear or branched alkyl group, an alkylene glycol group, or a terminally modified polyalkylene oxide group.
4. 1. 1. ~ 3. The flux composition according to any one of the above.
Further, a composition for a flux containing one or more second rosin compounds selected from the group consisting of maleic acid-modified rosin amide and hydrogenated products thereof.
5. 4. The flux composition according to the above.
The second rosin compound comprises a compound having a partial structure represented by the above-mentioned general formulas (2-1), (2-2), (3-1) or (3-2) and a hydrogenated product thereof. A composition for a flux containing one or more compounds selected from the group.
In the above general formula, * represents a bond with another chemical structure.
6. 4. Or 5. The flux composition according to the above.
The second rosin compound is selected from the group consisting of the compounds represented by the above-mentioned general formulas (2a-1), (2a-2), (3a-1) or (3a-2) and hydrogenated products thereof. A flux composition containing 1 or 2 or more.
In the above general formula, R represents a linear or branched alkyl group, an alkylene glycol group, or a terminally modified polyalkylene oxide group, which may be substituted independently of each other.
7. 1. 1. ~ 6. A flux for soldering a solder alloy, which comprises the flux composition according to any one of the above.
8. 7. The flux described in
Flux containing thixotropic agent.
9. 7. Or 8. The flux described in
Further, a flux containing one or more selected from the group consisting of amines, organic halogen compounds, amine hydrohalates, antioxidants and resins.
10. 7. ~ 9. A solder paste comprising the flux according to any one of the above and a solder alloy.

According to the present invention
An imidized maleic acid-modified rosin and one or more first rosin compounds selected from the group consisting of hydrogenated products thereof.
One or more second rosin compounds selected from the group consisting of maleic acid-modified rosin amide and hydrogenated products thereof, and
A flux for soldering a solder alloy, which comprises a flux composition comprising.
The total amount of the first rosin compound and the second rosin compound is 10% by mass or more and 60% by mass or less with respect to the entire flux .
A flux is provided in which the first rosin compound has a molecular weight of 700 or less and the second rosin compound has a molecular weight of 700 or less .

Claims (10)

A composition for a flux containing one or more first rosin compounds selected from the group consisting of imidized maleic acid-modified rosin and hydrogenated products thereof. The flux composition according to claim 1.
The first rosin compound is a flux containing one or more compounds selected from the group consisting of compounds having a partial structure represented by the following general formula (1-1) or (1-2) and hydrogenated products thereof. Composition for.

In the above general formula, * represents a bond with another chemical structure. The flux composition according to claim 1 or 2.
The first rosin compound is a flux composition containing one or more compounds selected from the group consisting of compounds represented by the following general formulas (1a-1) or (1a-2) and hydrogenated products thereof.

In the above general formula, R independently represents a linear or branched alkyl group, an alkylene glycol group, or a terminally modified polyalkylene oxide group. The flux composition according to any one of claims 1 to 3.
Further, a composition for a flux containing one or more second rosin compounds selected from the group consisting of maleic acid-modified rosin amide and hydrogenated products thereof. The flux composition according to claim 4.
The second rosin compound is a group consisting of a compound having a partial structure represented by the following general formulas (2-1), (2-2), (3-1) or (3-2) and a hydrogenated product thereof. A composition for a flux containing one or more compounds selected from the above.

In the above general formula, * represents a bond with another chemical structure. The flux composition according to claim 4 or 5.
The second rosin compound is selected from the group consisting of compounds represented by the following general formulas (2a-1), (2a-2), (3a-1) or (3a-2) and hydrogenated products thereof1 Or a composition for flux containing 2 or more.

In the above general formula, R represents a linear or branched alkyl group, an alkylene glycol group, or a terminally modified polyalkylene oxide group, which may be substituted independently of each other. A flux for soldering a solder alloy, which comprises the flux composition according to any one of claims 1 to 6. The flux according to claim 7.
Flux containing thixotropic agent. The flux according to claim 7 or 8.
Further, a flux containing one or more selected from the group consisting of amines, organic halogen compounds, amine hydrohalogenates, antioxidants and resins. A solder paste containing the flux according to any one of claims 7 to 9 and a solder alloy.