Preparation method of soldering flux and joint body

Abstract

A soldering flux containing rosin (P), a compound (SA), an activator for removing a substance corresponding to the compound (SA), and a solvent for removing a substance corresponding to the compound (SA) is used. The compound (SA) is a compound represented by the general formula (sa). In the formula (sa), R 11 represents a hydrocarbon group which may have a hydroxyl group. 12 and R 13 Each is a hydrocarbon group having 5 or less carbon atoms which may have a substituent, a hydroxyl group or a hydrogen atom. m represents a positive integer. [Chemical Formula 1]

Description

Technical Field

[0001] The present invention relates to a method for preparing a soldering flux and a joint body. This application claims priority based on Japanese Patent Application No. 2021-199990 filed in Japan on December 9, 2021, the contents of which are incorporated herein by reference. Background Art

[0002] Fixing components to a substrate and electrically connecting components to the substrate are generally performed by soldering. In soldering, flux, solder, and solder paste containing a mixture of flux and solder are used.

[0003] Flux chemically removes metal oxides from the metal surfaces of the objects being soldered and the solder, allowing metal elements to migrate across the boundary between them. Therefore, soldering with flux forms intermetallic compounds between the two, resulting in a strong bond.

[0004] In soldering, a method such as flow soldering or reflow soldering is used depending on the size of the objects to be joined.

[0005] In flow soldering, flux is first applied to a substrate with components mounted on it. Then, while the substrate with components mounted on it is being transported, molten solder jetting from below is brought into contact with the soldering surface, thereby performing soldering.

[0006] In reflow soldering, solder paste is first printed on a substrate. Components are then mounted on the substrate, and the substrate with the components mounted on it is heated in a heating furnace called a reflow oven to perform soldering.

[0007] The flux used in soldering generally contains a resin component, a solvent, an activator, a thixotropic agent, etc. For example, the examples of Patent Document 1 describe a flux for flow soldering containing rosin as a resin component and an organic acid, an organic halogen compound, or an amine hydrohalide as an activator.

[0008] Prior art documents

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent No. 6617848 Summary of the Invention

[0011] Problems to be solved by the present invention

[0012] However, in recent years, due to concerns about the negative impact on the environment, lead-free solder has been used. Because lead-free solder has a high melting point, it must be heated to a higher temperature to melt during soldering. The higher the temperature of the molten solder, the more oxides (called scum) are likely to form.

[0013] In particular, solder containing Sn and Bi can produce dross in the molten state because Bi is easily oxidized. Furthermore, when using solder containing Sn and Bi, the resulting dross is likely to adhere to the substrate. This dross can cause short circuits and reduced insulation.

[0014] The flux described in Patent Document 1 may easily cause scum to adhere to the surface of a substrate. Therefore, an object of the present invention is to provide a flux and a method for producing a joint body that can suppress scum from adhering to the surface of a substrate during soldering.

[0015] Means of solving the problem

[0016] In order to solve the above-mentioned problems, the present invention adopts the following configuration.

[0017] That is, the first aspect of the present invention is a flux containing rosin (P), a compound (SA) represented by the following general formula (sa), an activator for removing a substance corresponding to the compound (SA), and a solvent for removing a substance corresponding to the compound (SA).

[0018] [Chemical Formula 1]

[0019]

[0020] [In formula (sa), R 11 represents a hydrocarbon group which may have a hydroxyl group. 12 and R 13 Each independently represents a hydrocarbon group having 5 or less carbon atoms, a hydroxyl group, or a hydrogen atom which may have a substituent. m represents a positive integer.

[0021] In the soldering flux according to the first aspect, the rosin (P) preferably contains rosin (PA) having a softening point exceeding 100° C. and rosin (PB) having a softening point of 100° C. or less.

[0022] In the soldering flux according to the first aspect, the mixing ratio of the rosin (PA) to the rosin (PB) is preferably (PA) / (PB) = 5 / 5 to 9 / 1, as expressed by a mass ratio of (PA) / (PB).

[0023] In the soldering flux according to the first aspect, it is preferred that the rosin (PA) contains at least one rosin (P1) selected from acrylic acid-modified hydrogenated rosin and polymerized rosin, and the rosin (PB) contains hydrogenated rosin.

[0024] In the soldering flux of the first aspect, the content of the compound (SA) is preferably 1 to 60 parts by mass relative to 100 parts by mass of the rosin (P).

[0025] In the soldering flux according to the first aspect, the activator preferably contains a compound represented by the following general formula (a1).

[0026] [Chemical Formula 2]

[0027]

[0028] [In formula (a1), R 1 、R 2 、R 3 and R 4 Each independently represents a hydrocarbon group, a hydroxyl group, a halogen atom or a hydrogen atom.]

[0029] In the soldering flux according to the first aspect, the activator preferably contains an alkanolamine.

[0030] In the soldering flux according to the first aspect, the solvent preferably contains at least one selected from ethanol and 2-propanol.

[0031] In the flux according to the first aspect, the solid content concentration is preferably 20% by mass or less.

[0032] Furthermore, a second aspect of the present invention is a method for producing a bonded body, the method including the step of obtaining the bonded body by soldering a solder alloy onto the surface of a substrate treated with the flux of the first aspect.

[0033] In the method for joining a joined body according to the second aspect, the solder alloy preferably includes a solder alloy containing Sn and Bi.

[0034] Effects of the present invention

[0035] According to the present invention, it is possible to provide a flux capable of suppressing scum from adhering to the surface of a substrate during soldering and a method for producing a joint body. DETAILED DESCRIPTION

[0036] (Flux)

[0037] The flux of the first embodiment can be used for either flow soldering or reflow soldering, but is preferably used for flow soldering.

[0038] Hereinafter, an embodiment in which the flux of the first aspect is applied to a flux for flow soldering will be described.

[0039] The soldering flux of the embodiment described above contains rosin (P), an activator for removing a substance corresponding to the compound (SA), and a solvent for removing a substance corresponding to the compound (SA). The compound (SA) will be described later.

[0040] In this specification, the solid content of the flux refers to all components remaining after removing only the solvent from the flux.

[0041] <Rosin>

[0042] The flux of this embodiment contains rosin (P).

[0043] In the present invention, "rosin" includes natural resins containing abietic acid as a main component, mixtures of abietic acid and its isomers, and substances obtained by chemically modifying natural resins (sometimes referred to as rosin derivatives).

[0044] The total content of abietic acid and isomers of abietic acid in the natural resin is, for example, 40% by mass or more and 80% by mass or less relative to the natural resin.

[0045] In this specification, the "main component" refers to a component whose content in the compound is 40% by mass or more among the components constituting the compound.

[0046] Representative examples of isomers of abietic acid include neoabietic acid, palustric acid, and levopimaric acid. The structure of abietic acid is shown below.

[0047] [Chemical Formula 3]

[0048]

[0049] Examples of the “natural resin” include gum rosin, wood rosin, and tall oil rosin.

[0050] In the present invention, "substances obtained by chemically modifying natural resins (rosin derivatives)" include substances obtained by subjecting the "natural resins" to one or more treatments selected from hydrogenation, dehydrogenation, neutralization, alkylene oxide addition, amidation, dimerization and polymerization, esterification, and Diels-Alder cycloaddition.

[0051] Examples of rosin derivatives include purified rosin and modified rosin.

[0052] Examples of the modified rosin include hydrogenated rosin, polymerized rosin, polymerized hydrogenated rosin, disproportionated rosin, acid-modified rosin, rosin ester, acid-modified hydrogenated rosin, acid-anhydride-modified hydrogenated rosin, acid-modified disproportionated rosin, acid-anhydride-modified disproportionated rosin, phenol-modified rosin, and α,β-unsaturated carboxylic acid-modified products (such as acrylated rosin, maleated rosin, and fumarated rosin), as well as purified products, hydrogenated products, and disproportionated products of such polymerized rosin, purified products, hydrogenated products, and disproportionated products of such α,β-unsaturated carboxylic acid-modified products, abietic alcohol, rosin amine, hydrogenated abietic alcohol, rosin ester, hydrogenated rosin ester, rosin soap, hydrogenated rosin soap, and acid-modified rosin soap.

[0053] Examples of the rosin amine include dehydroabietin amine and dihydroabietin amine.

[0054] Rosin amine refers to so-called disproportionated rosin amine.

[0055] The structures of dehydroabietamine and dihydroabietamine are shown below.

[0056] [Chemical Formula 4]

[0057]

[0058] The rosin (P) may be used alone or in combination of two or more.

[0059] The rosin (P) preferably contains a rosin derivative, more preferably contains one or more selected from acid-modified rosin, polymerized rosin, hydrogenated rosin, acid-modified hydrogenated rosin, and rosin esters, further preferably contains one or more selected from acid-modified hydrogenated rosin, polymerized rosin, hydrogenated rosin, and rosin esters, and particularly preferably contains one or more selected from acid-modified hydrogenated rosin and hydrogenated rosin.

[0060] As the acid-modified hydrogenated rosin, acrylic acid-modified hydrogenated rosin is preferred.

[0061] The rosin (P) preferably contains a rosin (PA) having a softening point exceeding 100°C and a rosin (PB) having a softening point of 100°C or less.

[0062] The softening point of rosin can be measured by the ring and ball method. As an example of the ring and ball method, the method described in JIS K5902 can be mentioned. Specifically, the softening point can be measured by the following procedure.

[0063] First, the sample to be measured is quickly melted at the lowest possible temperature and carefully filled into a ring placed on a flat metal plate to prevent bubbles from forming. After cooling, the raised portion of the flat surface containing the upper end of the ring is removed with a slightly heated knife. Next, a support (ring holder) is placed in a glass container (heating bath) with a diameter of at least 85 mm and a height of at least 127 mm, and a heating medium is poured into the container until the depth reaches at least 90 mm. Next, a steel ball (9.5 mm diameter, 3.5 g weight) and the ring filled with the sample are immersed in the heating medium without contact with each other, and the temperature of the heating medium is maintained at 20°C plus or minus 5°C for 15 minutes. The steel ball is then placed in the center of the surface of the sample in the ring and fixed in place on the support. A thermometer is then placed with the center of the mercury bulb at the same height as the center of the ring, and the container is heated. The flame of the Bunsen burner used for heating is positioned between the center and edge of the container bottom to ensure uniform heating. Furthermore, the bath temperature must rise at a rate of 5.0°C plus or minus 0.5°C per minute after reaching 40°C from the start of heating. The temperature at which the sample gradually softens and falls from the circulating flow until it finally contacts the bottom plate is measured and designated as the softening point. Two or more softening point measurements should be performed simultaneously, and the average value of these values ​​should be used.

[0064] When the softening point of the measurement object is 80° C. or lower, water is used as the heat medium. When the softening point of the measurement object exceeds 80° C., glycerin is used as the heat medium.

[0065] By making the rosin (P) contain the rosin (PA), it is easy to further reduce the stickiness of the flux residue.

[0066] The softening point of the rosin (PA) is preferably 110° C. or higher, more preferably 115° C. or higher, further preferably 120° C. or higher, particularly preferably 125° C. or higher, and most preferably 130° C. or higher.

[0067] When the softening point of the rosin (PA) is equal to or higher than the lower limit, the stickiness of the flux residue can be further easily reduced.

[0068] The softening point of the rosin (PA) is preferably 170° C. or lower, more preferably 160° C. or lower, and even more preferably 150° C. or lower.

[0069] The softening point of the rosin (PA) may be higher than 100°C and lower than 170°C, preferably higher than 110°C and lower than 160°C, more preferably higher than 115°C and lower than 160°C, further preferably higher than 120°C and lower than 160°C, particularly preferably higher than 125°C and lower than 160°C, and most preferably higher than 130°C and lower than 160°C.

[0070] Alternatively, the softening point of the rosin (PA) is preferably 110°C to 150°C, more preferably 115°C to 150°C, further preferably 120°C to 150°C, particularly preferably 125°C to 150°C, and most preferably 130°C to 150°C.

[0071] When the softening point of the rosin (PA) is within the above range, the stickiness of the flux residue can be further easily reduced.

[0072] When the rosin (P) contains the rosin (PB), the fluidity of the flux can be further improved, thereby making it easier to suppress soldering defects.

[0073] The softening point of the rosin (PB) is preferably 96° C. or lower, more preferably 93° C. or lower.

[0074] When the softening point of the rosin (PB) is below the upper limit, the fluidity of the flux can be further improved, thereby making it easier to suppress soldering defects.

[0075] The softening point of the rosin (PB) is preferably 60° C. or higher, more preferably 65° C. or higher, and even more preferably 70° C. or higher.

[0076] The softening point of the rosin (PB) may be 60° C. or higher and 100° C. or lower, preferably 60° C. or higher and 96° C. or lower, more preferably 65° C. or higher and 96° C. or lower, and even more preferably 70° C. or higher and 96° C. or lower.

[0077] Alternatively, the softening point of the rosin (PB) is preferably 60° C. or higher and 93° C. or lower, more preferably 65° C. or higher and 93° C. or lower, and even more preferably 70° C. or higher and 93° C. or lower.

[0078] When the softening point of the rosin (PB) is within the above range, the fluidity of the flux can be further improved, thereby making it easier to suppress soldering defects.

[0079] The rosin (PA) may be used alone or in combination of two or more.

[0080] The rosin (PA) preferably contains at least one rosin (P1) selected from the group consisting of acid-modified hydrogenated rosin and polymerized rosin, but may also be composed solely of the rosin (P1).

[0081] The rosin (PB) may be used alone or as a mixture of two or more.

[0082] Examples of the rosin (PB) include hydrogenated rosin and rosin ester.

[0083] From the viewpoint of improving the fluidity of the soldering flux, the rosin (PB) preferably contains hydrogenated rosin, but may be composed solely of hydrogenated rosin.

[0084] From the viewpoint of improving the heat resistance of the flux, the rosin (PB) preferably contains a rosin ester.

[0085] The content of the rosin (P) in the flux is preferably 2% by mass or more and 30% by mass or less, more preferably 4% by mass or more and 20% by mass or less, and further preferably 6% by mass or more and 15% by mass or less, relative to the total amount of the flux (100% by mass).

[0086] When the rosin (P) contains the rosin (PA), the content of the rosin (PA) relative to the total amount (100 mass%) of the flux is preferably 2 mass% or more and 30 mass% or less, more preferably 4 mass% or more and 20 mass% or less, further preferably 5 mass% or more and 15 mass% or less, particularly preferably 6 mass% or more and 15 mass% or less, and most preferably 8 mass% or more and 15 mass% or less.

[0087] When the rosin (P) contains the rosin (PB), the content of the rosin (PB) relative to the total amount of the flux (100 mass%) is preferably greater than 0 mass% and 15 mass% or less, more preferably greater than 0 mass% and 10 mass% or less, further preferably greater than 0 mass% and 6 mass% or less, particularly preferably greater than 0 mass% and 4 mass% or less, and most preferably greater than 0 mass% and 2 mass% or less.

[0088] In the solid content of the flux, the content of the rosin (P) relative to the total amount of the solid content (100 mass%) is preferably 15 mass% or more and 95 mass% or less, more preferably 30 mass% or more and 90 mass% or less, and further preferably 45 mass% or more and 90 mass% or less.

[0089] When the rosin (P) contains the rosin (PA), the content of the rosin (PA) relative to the total amount (100% by mass) of the solid content of the flux is preferably 15% by mass or more and 95% by mass or less, more preferably 20% by mass or more and 90% by mass or less, further preferably 30% by mass or more and 90% by mass or less, particularly preferably 40% by mass or more and 90% by mass or less, and most preferably 50% by mass or more and 90% by mass or less.

[0090] When the rosin (P) contains the rosin (PB), the content of the rosin (PB) in the solid content of the flux, relative to the total amount of the solid content (100 mass%), is preferably greater than 0 mass% and less than 50 mass%, more preferably greater than 0 mass% and less than 40 mass%, further preferably greater than 0 mass% and less than 30 mass%, particularly preferably greater than 0 mass% and less than 20 mass%, and most preferably greater than 0 mass% and less than 10 mass%.

[0091] When the rosin (P) contains the rosin (PA) and the rosin (PB), the mixing ratio of the rosin (PA) to the rosin (PB) is preferably 4 / 6 to 9 / 1, more preferably 5 / 5 to 9 / 1, and even more preferably 6 / 4 to 9 / 1, in terms of the mass ratio represented by (PA) / (PB).

[0092] When the mass ratio is within the preferred range, it is easy to further reduce the stickiness of the flux residue.

[0093] <Compound (SA)>

[0094] The soldering flux of the present embodiment contains a compound (SA) represented by the following general formula (sa).

[0095] [Chemical Formula 5]

[0096]

[0097] [In formula (sa), R 11 represents a hydrocarbon group which may have a hydroxyl group. 12 and R 13 Each independently represents a hydrocarbon group having 5 or less carbon atoms, a hydroxyl group, or a hydrogen atom which may have a substituent. m represents a positive integer.

[0098] R 11 The hydrocarbon group in can be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. The aliphatic hydrocarbon group can be saturated or unsaturated, and is usually preferably saturated.

[0099] More specifically, examples of the aliphatic hydrocarbon group include a linear or branched aliphatic hydrocarbon group, and an aliphatic hydrocarbon group containing a ring in its structure.

[0100] The linear or branched aliphatic hydrocarbon group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, further preferably 1 to 4 carbon atoms, and most preferably 1 to 3 carbon atoms.

[0101] As R 11The straight-chain aliphatic hydrocarbon group in the group is preferably a straight-chain alkylene group, specifically, methylene [-CH2-], ethylene [-(CH2)2-], trimethylene [-(CH2)3-], tetramethylene [-(CH2)4-], pentamethylene [-(CH2)5-], etc., preferably ethylene [-(CH2)2-].

[0102] As R 11 The branched aliphatic hydrocarbon group in the is preferably a branched alkylene group, specifically, -CH(CH3)-, -CH2-CH(CH3)-, -CH(CH2CH3)-, -C(CH3)2-, -C(CH3)(CH2CH3)-, -C(CH3)(CH2CH2CH3)-, -C(CH2CH3)2- and the like alkylmethylene groups; -CH(CH3)CH2-, -CH(CH3)CH(CH3)- The alkyl group in the alkylalkylene group is preferably a linear alkyl group having 1 to 5 carbon atoms.

[0103] Examples of the aliphatic hydrocarbon group containing a ring in the structure include an alicyclic hydrocarbon group (a group formed by removing two hydrogen atoms from an aliphatic hydrocarbon ring), a group in which an alicyclic hydrocarbon group is bonded to the end of a linear or branched aliphatic hydrocarbon group, and a group in which an alicyclic hydrocarbon group is interposed in the middle of a linear or branched aliphatic hydrocarbon group. Examples of the linear or branched aliphatic hydrocarbon group include the same groups as those for the linear aliphatic hydrocarbon group or the branched aliphatic hydrocarbon group.

[0104] The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, more preferably 3 to 12 carbon atoms.

[0105] The alicyclic hydrocarbon group may be a polycyclic or a monocyclic group. As a monocyclic alicyclic hydrocarbon group, a group formed by removing two hydrogen atoms from a monocycloalkane is preferred. As the monocycloalkane, an alkane having 3 to 6 carbon atoms is preferred, and specifically, cyclopentane, cyclohexane, etc. can be mentioned. As a polycyclic alicyclic hydrocarbon group, a group formed by removing two hydrogen atoms from a polycycloalkane is preferred, and as the polycycloalkane, a polycycloalkane having 7 to 12 carbon atoms is preferred, and specifically, adamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane, etc. can be mentioned.

[0106] As R11 The aromatic hydrocarbon group of the divalent hydrocarbon group is a hydrocarbon group having an aromatic ring.

[0107] The number of carbon atoms in the aromatic hydrocarbon group is preferably 3 to 30, more preferably 5 to 30, further preferably 5 to 20, particularly preferably 6 to 15, and most preferably 6 to 10. The number of carbon atoms mentioned above does not include the number of carbon atoms in the substituent.

[0108] Specific examples of the aromatic ring possessed by the aromatic hydrocarbon group include aromatic hydrocarbon rings such as benzene, biphenyl, fluorene, naphthalene, anthracene, and phenanthrene; aromatic heterocyclic rings in which a portion of the carbon atoms constituting the aromatic hydrocarbon rings are substituted with heteroatoms; and condensed rings formed by condensing an aromatic hydrocarbon ring with an aromatic heterocyclic ring. Examples of heteroatoms in the aromatic heterocyclic ring include oxygen atoms, sulfur atoms, and nitrogen atoms.

[0109] Specific examples of the aromatic hydrocarbon group include a group formed by removing two hydrogen atoms from an aromatic hydrocarbon ring (arylene group); a group formed by removing one hydrogen atom from an aromatic hydrocarbon ring (aryl group) in which one hydrogen atom is replaced by an alkylene group (for example, a group formed by further removing one hydrogen atom from an aryl group in an aralkyl group such as benzyl, phenethyl, 1-naphthylmethyl, 2-naphthylmethyl, 1-naphthylethyl, or 2-naphthylethyl). The alkylene group (the alkyl chain in the arylalkyl group) preferably has 1 to 4 carbon atoms, more preferably 1 to 2, and particularly preferably 1.

[0110] R 11 Among the above hydrocarbon groups, a group in which a hydrogen atom is replaced by a hydroxyl group may be used. 11 It may also have a substituent other than a hydroxyl group. Examples of the substituent other than a hydroxyl group include a carbonyl group, a carboxyl group, an amino group, a halogen atom, etc. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0111] As R having a hydroxyl group 11 , preferably -CH2-CH(OH)-CH2-.

[0112] In compound (SA), the presence of multiple R 11 They can be the same or different from each other.

[0113] In the general formula (sa), R 12 In the case of a hydrocarbon group having 5 or less carbon atoms which may have a substituent, R 12 Preferably R 121 O-. R 121 It represents a hydrocarbon group having 5 or less carbon atoms which may have a substituent.

[0114] R 121The hydrocarbon group in can be an aliphatic hydrocarbon group. The aliphatic hydrocarbon group can be saturated or unsaturated, and is usually preferably saturated.

[0115] More specifically, examples of the aliphatic hydrocarbon group include a linear or branched aliphatic hydrocarbon group, and an aliphatic hydrocarbon group containing a ring in its structure.

[0116] R 121 The hydrocarbon group in preferably has 1 to 3 carbon atoms, more preferably 1 to 2 carbon atoms, and most preferably 1 carbon atom.

[0117] Among them, R 12 A hydroxy group is preferred.

[0118] R 13 In the general formula (sa), R 13 In the case of a hydrocarbon group having 5 or less carbon atoms which may have a substituent, R 13 Preferably -C(=O)-R 131 . R 131 It represents a hydrocarbon group having 5 or less carbon atoms which may have a substituent.

[0119] As R 131 The hydrocarbon group in R 121 Substances with the same hydrocarbon group in.

[0120] R 131 The hydrocarbon group in the carbon number is preferably 1 to 3, more preferably 1 to 2, and most preferably 1.

[0121] Among them, R 13 Preferred is a hydrogen atom.

[0122] In the above general formula (sa), m is not particularly limited as long as the effects of the present invention are achieved, and may be 1-300, preferably 1-200, more preferably 2-100, further preferably 2-70, particularly preferably 2-40, and most preferably 2-20.

[0123] In the above general formula (sa), R 11 In the case of ethylene, m is not particularly limited as long as the effects of the present invention are achieved, but is preferably 2 to 100, more preferably 2 to 70, further preferably 2 to 40, and particularly preferably 2 to 20.

[0124] In the above general formula (sa), R 11 In the case of -CH2-CH(CH3)-, m is not particularly limited as long as the effects of the present invention are achieved, but is preferably 2 to 100, more preferably 2 to 70, further preferably 2 to 40, and particularly preferably 2 to 20.

[0125] In the above general formula (sa), R 11In the case of -CH2-CH(OH)-CH2-, m is not particularly limited as long as the effects of the present invention are achieved, but is preferably 1 to 15, more preferably 1 to 7, and even more preferably 1 to 3.

[0126] The soldering flux of this embodiment may contain a single compound (SA) or two or more compounds (SA) having different m. When the soldering flux of this embodiment contains two or more compounds (SA), the average molecular weight of the compounds (SA) may be as follows.

[0127] In this specification, the "average molecular weight" refers to the weight average molecular weight measured by gel permeation chromatography (GPC). In this specification, the "average molecular weight" refers to the PEG-equivalent molecular weight.

[0128] The average molecular weight measured by this method is a weight average molecular weight calculated based on all the compounds (SA) contained in the flux.

[0129] The average molecular weight of the compound (SA) is preferably 100 to 4000, more preferably 100 to 3600, further preferably 100 to 1600, and particularly preferably 100 to 800.

[0130] R 11 In the case of ethylene, as R 11 The average molecular weight of the ethylene group compound (SA) is preferably 100 to 4,000, more preferably 100 to 2,000, further preferably 100 to 1,000, and particularly preferably 100 to 800.

[0131] When the average molecular weight is within the above range, it is easy to further suppress the adhesion of scum to the surface of the substrate and to further reduce the stickiness of the flux residue.

[0132] R 11 In the case of -CH2-CH(CH3)-, as R 11 -CH 2- The average molecular weight of the compound (SA) containing CH(CH3)- is preferably 100 to 4000, more preferably 300 to 4000.

[0133] R 11 In the case of -CH2-CH(OH)-CH2-, as R 11 The average molecular weight of the compound (SA) representing -CH2-CH(OH)-CH2- is preferably 100 to 1000, more preferably 200 to 600, and even more preferably 200 to 350.

[0134] Examples of the compound (SA) include polyethylene glycol, polypropylene glycol, polyglycerol, polyethylene glycol-polypropylene glycol copolymers, and ethylene oxide-resorcinol copolymers. The copolymer may be an alternating copolymer, a random copolymer, or a block copolymer.

[0135] When the compound (SA) is polyethylene glycol, the freezing point of the compound (SA) is preferably -100°C or higher and 60°C or lower, more preferably -70°C or higher and 60°C or lower, further preferably -70°C or higher and 48°C or lower, particularly preferably -70°C or higher and 30°C or lower, and most preferably -70°C or higher and 25°C or lower.

[0136] The compound (SA) may be used alone or in combination of two or more.

[0137] The compound (SA) preferably contains at least one selected from polyethylene glycol, polypropylene glycol, and polyglycerol, and more preferably contains at least one selected from polyethylene glycol and polypropylene glycol.

[0138] By making the compound (SA) contain one or more selected from polyethylene glycol and polypropylene glycol, it is easy to further suppress the adhesion of scum to the substrate surface and to further reduce the stickiness of the flux residue.

[0139] The content of the compound (SA) in the soldering flux is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, relative to the total mass (100% by mass) of the soldering flux.

[0140] The content of the compound (SA) in the solid content of the flux is preferably 0.7 mass % or more, more preferably 3.4 mass % or more, and even more preferably 6.7 mass % or more, relative to the total amount of the solid content (100 mass %).

[0141] When the content of the compound (SA) is at least the above lower limit, it is easier to suppress scum from adhering to the surface of the substrate during soldering.

[0142] The content of the compound (SA) in the flux is preferably 6 mass% or less, more preferably 5 mass% or less, further preferably 4 mass% or less, particularly preferably 3 mass% or less, most preferably 2 mass% or less, and may also be 1.5 mass% or less, relative to the total mass of the flux (100 mass%).

[0143] The content of the compound (SA) in the flux is preferably 30 mass% or less, more preferably 26 mass% or less, further preferably 22 mass% or less, particularly preferably 17 mass% or less, most preferably 12 mass% or less, and can be 9.7 mass% or less, relative to the total amount of the solid component (100 mass%).

[0144] When the content of the compound (SA) is equal to or less than the above upper limit, the stickiness of the flux residue can be further easily reduced.

[0145] The content of the compound (SA) in the flux is preferably 0.1% by mass or more and 6% by mass or less, more preferably 0.5% by mass or more and 4% by mass or less, further preferably 1% by mass or more and 3% by mass or less, particularly preferably 1% by mass or more and 2% by mass or less, and most preferably 1% by mass or more and 1.5% by mass or less, relative to the total mass of the flux (100% by mass).

[0146] The content of the compound (SA) in the flux is preferably 0.7 mass % to 30 mass % relative to the total amount of the solid component (100 mass %), more preferably 3.4 mass % to 22 mass % or less, further preferably 6.7 mass % to 22 mass % or less, particularly preferably 6.7 mass % to 17 mass % or less, and most preferably 6.7 mass % to 9.7 mass % or less.

[0147] When the content of the compound (SA) is at least the lower limit of the preferred range, adhesion of scum to the substrate surface can be further suppressed, while when it is at most the upper limit of the preferred range, stickiness of flux residue can be further reduced.

[0148] The content of the compound (SA) in the flux is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of rosin (P). When the content of the compound (SA) is at least the lower limit, scum adhesion to the substrate surface during soldering is further suppressed.

[0149] The content of the compound (SA) in the soldering flux is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 40 parts by mass or less, particularly preferably 30 parts by mass or less, and most preferably 20 parts by mass or less, and may be 15 parts by mass or less, 10 parts by mass or less, 5 parts by mass or less, or 1 part by mass or less. When the content of the compound (SA) is below the upper limit, the stickiness of the flux residue can be further reduced.

[0150] The content of the compound (SA) in the flux is preferably from 1 part by mass to 60 parts by mass, more preferably from 5 parts by mass to 40 parts by mass, further preferably from 10 parts by mass to 30 parts by mass, particularly preferably from 10 parts by mass to 20 parts by mass, and most preferably from 10 parts by mass to 15 parts by mass, relative to 100 parts by mass of rosin (P).

[0151] When the content of the compound (SA) is at least the lower limit of the preferred range, scum adhesion to the substrate surface during soldering can be further suppressed, while when it is at most the upper limit of the preferred range, the stickiness of the flux residue can be further reduced.

[0152] <Activator>

[0153] The soldering flux of this embodiment contains an activator (except for the activator corresponding to the compound (SA)).

[0154] Examples of the activator include organic acids, amines, and halogen compounds.

[0155] Organic Acids

[0156] Examples of organic acids include carboxylic acids and organic sulfonic acids. Examples of carboxylic acids include aliphatic carboxylic acids and aromatic carboxylic acids. Examples of aliphatic carboxylic acids include aliphatic monocarboxylic acids and aliphatic dicarboxylic acids.

[0157] Examples of the aliphatic monocarboxylic acid include hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, isononanoic acid, decanoic acid, decenoic acid, lauric acid (dodecanoic acid), undecanoic acid, 5-dodecenoic acid, tridecanoic acid, myristoleic acid, pentadecanoic acid, isopalmitic acid, palmitoleic acid, hexadecatrienoic acid, cyclopentenoundecanoic acid, heptadecanoic acid, isostearic acid, elaidic acid, parsleyic acid, stearatetraenoic acid, eleostearic acid, tarronic acid, vaccenic acid, ricinoleic acid, vernolic acid, sterculic acid, nonadecanoic acid, eicosanoic acid, stearic acid, 12-hydroxystearic acid, oleic acid, linoleic acid, linolenic acid, myristic acid, 2,2-bis(hydroxymethyl)propionic acid, and 2,2-bis(hydroxymethyl)butyric acid.

[0158] Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, eicosanedioic acid, and tartaric acid.

[0159] Examples of the aromatic carboxylic acid include salicylic acid, dibutylanilinodiglycolic acid, terephthalic acid, p-hydroxyphenylacetic acid, phenylsuccinic acid, phthalic acid, benzoic acid, 2,3-dihydroxybenzoic acid, 2,4-diethylglutaric acid, 2-quinolinecarboxylic acid, 3-hydroxybenzoic acid, and p-anisic acid.

[0160] Examples of the carboxylic acid include tris(2-carboxyethyl)isocyanurate and 1,3-cyclohexanedicarboxylic acid.

[0161] Examples of the carboxylic acid include dimer acid, trimer acid, hydrogenated dimer acid which is a hydrogenated product of dimer acid, and hydrogenated trimer acid which is a hydrogenated product of trimer acid.

[0162] Examples of the dimer acid and trimer acid include a dimer acid as a reaction product of oleic acid and linoleic acid, a trimer acid as a reaction product of oleic acid and linoleic acid, a dimer acid as a reaction product of acrylic acid, a trimer acid as a reaction product of acrylic acid, a dimer acid as a reaction product of methacrylic acid, a trimer acid as a reaction product of methacrylic acid, a dimer acid as a reaction product of acrylic acid and methacrylic acid, a trimer acid as a reaction product of acrylic acid and methacrylic acid, a dimer acid as a reaction product of oleic acid, a trimer acid as a reaction product of oleic acid, a dimer acid as a reaction product of linoleic acid, a trimer acid as a reaction product of linolenic acid, a dimer acid as a reaction product of linolenic acid, a trimer acid as a reaction product of linolenic acid, a dimer acid as a reaction product of acrylic acid and oleic acid, a trimer acid as a reaction product of acrylic acid and linoleic acid, and a dimer acid as a reaction product of acrylic acid and oleic acid. acid, trimer acid which is a reaction product of acrylic acid and linoleic 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, trimer acid which is a reaction product of methacrylic acid and oleic acid, dimer acid which is a reaction product of methacrylic acid and linoleic acid, trimer 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, trimer acid which is a reaction product of methacrylic acid and linolenic acid, dimer acid which is a reaction product of oleic acid and linolenic acid, trimer acid which is a reaction product of linoleic acid and linolenic acid, dimer acid which is a reaction product of linoleic acid and linolenic acid, trimer acid which is a reaction product of linoleic acid and linolenic acid, hydrogenated dimer acid which is a hydrogenated product of the above dimer acids, hydrogenated trimer acid which is a hydrogenated product of the above trimer acids, etc.

[0163] For example, dimer acid, which is a reaction product of oleic acid and linoleic acid, is a dimer having 36 carbon atoms. Furthermore, trimer acid, which is a reaction product of oleic acid and linoleic acid, is a trimer having 54 carbon atoms.

[0164] Examples of carboxylic acids include compounds represented by the following general formula (a1).

[0165] [Chemical Formula 6]

[0166]

[0167] [In formula (a1), R 1 、R 2、R 3 and R 4 Each independently represents a hydrocarbon group, a hydroxyl group, a halogen atom or a hydrogen atom.]

[0168] As R 1 、R 2 、R 3 and R 4 Examples of the hydrocarbon group include a chain hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, an alicyclic hydrocarbon group having 3 to 20 carbon atoms which may have a substituent, an amino group, a hydroxyl group, and a carboxyl group.

[0169] The chain hydrocarbon group may be straight chain or branched chain. The chain hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group, preferably a saturated hydrocarbon group.

[0170] The alicyclic hydrocarbon group may be a polycyclic group or a monocyclic group. A monocyclic alicyclic hydrocarbon group is preferably a group formed by removing one or more hydrogen atoms from a monocycloalkane. A polycyclic alicyclic hydrocarbon group is preferably a group formed by removing one or more hydrogen atoms from a polycycloalkane.

[0171] As R 1 、R 2 、R 3 and R 4 The substituent that the hydrocarbon group in may have includes an amino group, a hydroxyl group, a carboxyl group, an acyl group, an alkoxy group, a carbonyl group, a halogen atom and the like.

[0172] The hydrocarbon group is preferably a chain hydrocarbon group having 1 to 5 carbon atoms and optionally having a substituent or a carboxyl group. Examples of the chain hydrocarbon group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, tert-pentyl, and neopentyl. The hydrocarbon group is preferably a carboxyl group.

[0173] Examples of the compound represented by the general formula (a1) include picolinic acid, dipicolinic acid, and 3-hydroxypicolinic acid.

[0174] The compound represented by the general formula (a1) is preferably picolinic acid. Picolinic acid is 1 、R 2 、R 3 and R 4 A compound containing hydrogen atoms.

[0175] Alternatively, the compound represented by the above general formula (a1), R 1 、R 2 、R 3 、R 4 Each is independently preferably a hydroxyl group, more preferably 3-hydroxypicolinic acid.

[0176] 3-Hydroxypicolinic acid is R in the above general formula (a1) 1 is hydroxyl and R 2 、R 3 and R 4 A compound containing hydrogen atoms.

[0177] Examples of the organic sulfonic acid include aliphatic sulfonic acid and aromatic sulfonic acid. Examples of the aliphatic sulfonic acid include alkylsulfonic acid and alkanolsulfonic acid.

[0178] Examples of the alkylsulfonic acid include methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, 2-propanesulfonic acid, 1-butanesulfonic acid, 2-butanesulfonic acid, pentanesulfonic acid, hexanesulfonic acid, decanesulfonic acid, and dodecanesulfonic acid.

[0179] Examples of the alkanol sulfonic acid include 2-hydroxyethane-1-sulfonic acid, 2-hydroxypropane-1-sulfonic acid, 2-hydroxybutane-1-sulfonic acid, 2-hydroxypentane-1-sulfonic acid, 1-hydroxypropane-2-sulfonic acid, 3-hydroxypropane-1-sulfonic acid, 4-hydroxybutane-1-sulfonic acid, 2-hydroxyhexane-1-sulfonic acid, 2-hydroxydecane-1-sulfonic acid, and 2-hydroxydodecane-1-sulfonic acid.

[0180] Examples of the aromatic sulfonic acid include 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, p-toluenesulfonic acid, xylenesulfonic acid, p-phenolsulfonic acid, cresolsulfonic acid, sulfosalicylic acid, nitrobenzenesulfonic acid, sulfobenzoic acid, and diphenylamine-4-sulfonic acid.

[0181] The organic acid may be used alone or in combination of two or more.

[0182] The organic acid preferably contains one or more selected from aliphatic carboxylic acids and compounds represented by the above-mentioned general formula (a1).

[0183] The aliphatic carboxylic acid preferably contains at least one selected from aliphatic monocarboxylic acids and aliphatic dicarboxylic acids.

[0184] The compound represented by the general formula (a1) is preferably at least one selected from picolinic acid and dipicolinic acid, and more preferably picolinic acid.

[0185] The total content of the organic acid in the flux is preferably 1% to 10% by mass, more preferably 2% to 8% by mass, and even more preferably 3% to 6% by mass, relative to the total mass of the flux (100% by mass).

[0186] In the solid content of the flux, the content of the organic acid is preferably 5 mass % or more and 50 mass % or less, more preferably 10 mass % or more and 40 mass % or less, and further preferably 15 mass % or more and 35 mass % or less, relative to the total amount of the solid content (100 mass %).

[0187] The content of the compound represented by the general formula (a1) in the flux is preferably 0.05% by mass or more and 1% by mass or less, more preferably 0.1% by mass or more and 0.5% by mass or less, and further preferably 0.1% by mass or more and 0.3% by mass or less, relative to the total mass of the flux (100% by mass).

[0188] In the solid content of the flux, the content of the compound represented by the above-mentioned general formula (a1) is preferably greater than or equal to 0.3% by mass and less than or equal to 7% by mass, more preferably greater than or equal to 0.5% by mass and less than or equal to 3% by mass, and further preferably greater than or equal to 0.5% by mass and less than or equal to 2% by mass, relative to the total amount of the solid content (100% by mass).

[0189] "amine"

[0190] Examples of the amine include rosin amine, azoles, guanidines, alkylamine compounds, amino alcohol compounds, etc. Examples of the rosin amine include those exemplified in <rosin>.

[0191] 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 trimellitate, 1-cyanoethyl-2-phenylimidazole trimellitate, 2,4-diamino-6-[2″-methylimidazolyl-(1′)]-ethyl-s-trimethylol 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-benzylimidazole chloride, 2-methylimidazoline, 2-phenylimidazoline, 2,4-diamino-6-vinyl-s-triazine, 2 ,4-diamino-4,6-vinyl-s-triazine isocyanuric acid adduct, 2,4-diamino-6-methacryloyloxyethyl-s-triazine, epoxy-imidazole adduct, 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-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-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, etc.

[0192] Examples of the guanidines include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylguanidine, 1,3-di-o-isopropylphenylguanidine, and 1,3-di-o-isopropylphenyl-2-propionylguanidine.

[0193] Examples of the alkylamine compound include ethylamine, triethylamine, ethylenediamine, triethylenetetramine, cyclohexylamine, hexadecylamine, and stearylamine.

[0194] Examples of the amino alcohol compound include alkanolamines such as 1-amino-2-propanol and N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine.

[0195] The amines may be used alone or in combination of two or more.

[0196] As the amine, an amino alcohol compound is preferred, an alkanolamine is more preferred, and 1-amino-2-propanol is further preferred.

[0197] The content of the amine in the soldering flux is preferably 0.05% by mass or more and 2% by mass or less relative to the total amount (100% by mass) of the soldering flux.

[0198] In the solid content of the soldering flux, the content of the amine is preferably 0.5% by mass or more and 10% by mass or less relative to the total amount (100% by mass) of the solid content.

[0199] Halogen Compounds

[0200] Examples of the halogen compound include amine hydrohalides and organic halogen compounds other than amine hydrohalides.

[0201] Amine hydrohalides are compounds formed by reacting amines with hydrogen halides.

[0202] Examples of the amine include aliphatic amines, azoles, and guanidines. Examples of the hydrogen halide include hydrides of chlorine, bromine, and iodine.

[0203] Examples of the aliphatic amine include ethylamine, diethylamine, triethylamine, and ethylenediamine.

[0204] Examples of the guanidines and azoles include those mentioned above in the section "Amines".

[0205] More specifically, examples of the amine hydrohalide salt include cyclohexylamine hydrobromide, hexadecylamine hydrobromide, stearylamine hydrobromide, ethylamine hydrobromide, diphenylguanidine hydrobromide, ethylamine hydrochloride, stearylamine hydrochloride, diethylaniline hydrobromide, diethanolamine hydrochloride, 2-ethylhexylamine hydrobromide, pyridine hydrobromide, isopropylamine hydrobromide, diethylamine hydrobromide, dimethylamine hydrobromide, dimethylamine hydrochloride, rosinamine hydrobromide, 2-ethylhexylamine hydrochloride, isopropylamine hydrochloride, cyclohexylamine hydrochloride, 2-piperidine hydrobromide, 1,3-diphenylguanidine hydrochloride, dimethylbenzylamine hydrochloride, hydrazine hydrate hydrobromide, dimethylcyclohexylamine hydrochloride, trinonylamine hydrobromide, diethylaniline hydrobromide, 2-diethylaminoethanol hydrobromide, 2-diethylaminoethanol hydrochloride, ammonium chloride, diallylhydrazine, amine 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-phenylimidazole hydrobromide, 4-benzylpyridine hydrobromide, L-glutamic acid hydrochloride, N-methylmorpholine hydrochloride, betaine hydrochloride, 2-piperidine hydroiodide, cyclohexylamine hydroiodide, 1,3-diphenylguanidine hydrofluoride, diethylamine hydrofluoride, 2-ethylhexylamine hydrofluoride, cyclohexylamine hydrofluoride, ethylamine hydrofluoride, rosinamine hydrofluoride, cyclohexylamine tetrafluoroborate and dicyclohexylamine tetrafluoroborate, etc.

[0206] Furthermore, as the halogen compound, for example, a salt formed by reacting an amine with tetrafluoroboric acid (HBF 4 ) or a complex formed by reacting an amine with boron trifluoride (BF 3 ) can also be used.

[0207] Examples of the complex include boron trifluoride-piperidine and the like.

[0208] Examples of organic halogen compounds other than amine hydrohalides include halogenated aliphatic compounds. A halogenated aliphatic hydrocarbon group is a group in which a part or all of the hydrogen atoms constituting an aliphatic hydrocarbon group are substituted with halogen atoms.

[0209] Examples of the halogenated aliphatic compound include halogenated aliphatic alcohols and halogenated heterocyclic compounds.

[0210] Examples of the halogenated aliphatic alcohol 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.

[0211] Examples of the halogenated heterocyclic compound include compounds represented by the following general formula (1H).

[0212] R 61 -(R 62 ) n (1H)

[0213] [Where R 61 represents an n-valent heterocyclic group. 62 represents a halogenated aliphatic hydrocarbon group.]

[0214] As R 61 The heterocyclic ring of the n-valent heterocyclic group in the formula (I) may be a ring structure in which a portion of the carbon atoms constituting an aliphatic hydrocarbon or aromatic hydrocarbon ring are substituted with a heteroatom. Examples of heteroatoms in the heterocyclic ring include oxygen, sulfur, and nitrogen atoms. The heterocyclic ring is preferably a 3- to 10-membered ring, more preferably a 5- to 7-membered ring. Examples of the heterocyclic ring include an isocyanurate ring.

[0215] R 62 The halogenated aliphatic hydrocarbon group in preferably has 1 to 10 carbon atoms, more preferably 2 to 6 carbon atoms, and even more preferably 3 to 5 carbon atoms. 62 Preferred are brominated aliphatic hydrocarbon groups and chlorinated aliphatic hydrocarbon groups, more preferred are brominated aliphatic hydrocarbon groups, and even more preferred are brominated saturated aliphatic hydrocarbon groups.

[0216] Examples of the halogenated heterocyclic compound include tris-(2,3-dibromopropyl)isocyanurate.

[0217] In addition, as organic halogen compounds other than amine hydrohalides, for example, iodinated carboxyl compounds such as 2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, and 5-iodoanthranilic acid; chlorinated carboxyl compounds such as 2-chlorobenzoic acid and 3-chloropropionic acid; and halogenated carboxyl compounds such as brominated carboxyl compounds such as 2,3-dibromopropionic acid, 2,3-dibromosuccinic acid, and 2-bromobenzoic acid.

[0218] The halogen-based activators may be used alone or in combination of two or more.

[0219] Solvents

[0220] The solvent contained in the flux of this embodiment does not correspond to the compound (SA). Examples of the solvent include water, alcohol solvents, glycol ether solvents, and terpineols.

[0221] Examples of the alcoholic solvent include ethanol, 1-propanol, 2-propanol, 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-hexyne-2,5-diol, 2,3-dimethyl-2,3-butanediol, 2-methylpentane-2,4-diol, 1,1,1 -tris(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-decyne-4,7-diol, etc.

[0222] Examples of glycol ether solvents include diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, diethylene glycol monohexyl ether (hexyldiglycol), diethylene glycol dibutyl ether, triethylene glycol monobutyl ether, methpropylene triethylene glycol, butylpropylene triethylene glycol, triethylene glycol butyl methyl ether, and tetraethylene glycol dimethyl ether.

[0223] The solvent may be used alone or as a mixture of two or more.

[0224] From the perspective of increasing volatility during preheating, the solvent preferably contains a solvent with a boiling point of 100°C or less. The boiling point of the solvent with a boiling point of 100°C or less may be 50°C or greater, 60°C or greater, or even 70°C or greater. From the perspective of solubility of the specific active agent, the solvent with a boiling point of 100°C or less is preferably an alcoholic solvent.

[0225] The alcohol solvent preferably contains at least one selected from ethanol and 2-propanol.

[0226] The content of the solvent in the flux is preferably 60% by mass or more and 95% by mass or less, more preferably 70% by mass or more and 95% by mass or less, and further preferably 80% by mass or more and 95% by mass or less, relative to the total amount of the flux (100% by mass).

[0227] <Other ingredients>

[0228] The flux in this embodiment may contain other components as needed in addition to the rosin, the activator, and the solvent.

[0229] Examples of other components include a thixotropic agent, a resin component other than rosin, a metal deactivator, a surfactant, a silane coupling agent, an antioxidant, and a colorant.

[0230] Resin components other than rosin

[0231] Examples of resin components other than rosin-based resins include terpene resins, modified terpene resins, terpene-phenol resins, modified terpene-phenol resins, styrene resins, modified styrene resins, xylene resins, modified xylene resins, acrylic resins, polyethylene resins, acrylic-polyethylene copolymer resins, and epoxy resins.

[0232] Examples of modified terpene resins include aromatic modified terpene resins, hydrogenated terpene resins, and hydrogenated aromatic modified terpene resins. Examples of modified terpene phenol resins include hydrogenated terpene phenol resins. Examples of modified styrene resins include styrene acrylic resins and styrene maleic resins. Examples of modified xylene resins include phenol-modified xylene resins, alkylphenol-modified xylene resins, phenol-modified resol-type xylene resins, polyol-modified xylene resins, and polyethylene oxide-added xylene resins.

[0233] Metal passivator

[0234] Examples of the metal deactivator include hindered phenol compounds and nitrogen compounds.

[0235] The term "metal deactivator" as used herein refers to a compound that has the ability to prevent metal from deteriorating due to contact with a certain compound.

[0236] Hindered phenol compounds refer to phenolic compounds having a bulky substituent (for example, a branched or cyclic alkyl group such as a tert-butyl group) at at least one ortho position of phenol.

[0237] The hindered phenol compound is 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-butylimino)-1,3,5-triazine, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2-thiodiethylenebis[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 -hydrocinnamic acid amide), 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, 2,6-di-tert-butyl-4-methylphenol, and compounds represented by the following chemical formulas.

[0238] [Chemical Formula 7]

[0239]

[0240] (wherein, Z is an alkylene group which may be substituted. 81 and R 82 Each is independently an alkyl group, an aralkyl group, an aryl group, a heteroaryl group, a cycloalkyl group or a heterocycloalkyl group which may be substituted. 83 and R 84 Each independently represents an alkyl group which may be substituted.)

[0241] Examples of the nitrogen compound in the metal deactivator include hydrazide nitrogen compounds, amide nitrogen compounds, triazole nitrogen compounds, and melamine nitrogen compounds.

[0242] As the hydrazide-based nitrogen compound, any nitrogen compound having a hydrazide skeleton may be used, and examples thereof include dodecanedioic acid bis[N2-(2-hydroxybenzoyl)hydrazide], N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, decanedicarboxylic acid disalicylicylhydrazide, N-salicylic-N'-salicylic hydrazide, m-nitrophenylhydrazide, 3-aminophthalhydrazide, phthalic acid dihydrazide, adipic acid hydrazide, oxaloylbis(2-hydroxy-5-octylbenzylidenehydrazide), N'-benzoylpyrrolidonecarboxylic acid hydrazide, and N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hydrazine.

[0243] The amide nitrogen compound may be any nitrogen compound having an amide skeleton, and examples thereof include N,N′-bis{2-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]ethyl}oxamide.

[0244] The triazole nitrogen compound may be any nitrogen compound having a triazole skeleton, and examples thereof include N-(2H-1,2,4-triazol-5-yl)salicylamide, 3-amino-1,2,4-triazole, and 3-(N-salicyloyl)amino-1,2,4-triazole.

[0245] The melamine-based nitrogen compound may be any nitrogen compound having a melamine skeleton, and examples thereof include melamine and melamine derivatives. More specifically, examples thereof include triaminotriazine, alkylated triaminotriazine, alkoxyalkylated triaminotriazine, melamine, alkylated melamine, alkoxyalkylated melamine, N2-butylmelamine, N2,N2-diethylmelamine, and N,N,N',N',N',N"-hexa(methoxymethyl)melamine.

[0246] The metal deactivators may be used alone or in combination of two or more.

[0247] Surfactants

[0248] Examples of the surfactant include nonionic surfactants and cationic surfactants.

[0249] Examples of the nonionic surfactant include fatty alcohol polyoxyethylene adducts, aromatic alcohol polyoxyethylene adducts, polyhydric alcohol polyoxyethylene adducts, fatty alcohol polyoxypropylene adducts, aromatic alcohol polyoxypropylene adducts, and polyhydric alcohol polyoxypropylene adducts.

[0250] Examples of the cationic surfactant include terminal diamine polyethylene glycol, terminal diamine polyethylene glycol-polypropylene glycol copolymers, aliphatic amine polyoxyethylene adducts, aromatic amine polyoxyethylene adducts, and polyvalent amine polyoxypropylene adducts.

[0251] Examples of surfactants other than those mentioned above include polyoxyalkylene acetylene glycols, polyoxyalkylene glycerol ethers, polyoxyalkylene alkyl ethers, polyoxyalkylene esters, polyoxyalkylene alkylamines, and polyoxyalkylene alkylamides.

[0252] The surfactant may be used alone or in combination of two or more.

[0253] The solid content of the flux is preferably 20% by mass or less, more preferably 5% by mass or more and 20% by mass or less, and further preferably 10% by mass or more and 20% by mass or less, relative to the total amount of the flux (100% by mass).

[0254] When the solid content is within the above range, the flux can be easily used by flow soldering.

[0255] The flux of one embodiment described above contains rosin, compound (SA), activator, and solvent, and is suitable for flow soldering.

[0256] During flow soldering, molten solder easily generates oxides (dross). If the molten solder comes into contact with a substrate, this dross may adhere to the substrate. The flux of this embodiment can suppress dross from adhering to the surface of the substrate after soldering during flow soldering.

[0257] Especially when using solder containing Sn and Bi, dross easily forms on the surface of the molten solder because Bi easily oxidizes. The flux of this embodiment can suppress dross from adhering to the substrate surface after soldering, even when using solder containing Bi. Furthermore, soldering using the flux of this embodiment can produce a joint with excellent insulation reliability.

[0258] The flux of the above embodiment contains the compound (SA) and rosin in combination, thereby being able to suppress scum from adhering to the surface of the substrate after soldering and reducing the stickiness of the flux residue.

[0259] (Method for preparing a conjugate)

[0260] The method for producing a bonded body according to the second aspect includes the step of obtaining the bonded body by soldering a solder alloy on the surface of the substrate treated with the flux according to the first aspect.

[0261] Hereinafter, one embodiment of the method for producing a joined body according to the second aspect will be described.

[0262] The method for producing a bonded structure according to the present embodiment includes a component mounting step, a flux coating step, a preheating step, and a soldering step in this order.

[0263] In the component mounting step, components are mounted on the substrate.

[0264] Examples of the substrate include printed wiring boards.

[0265] Examples of the components include integrated circuits, transistors, diodes, resistors, and capacitors.

[0266] In the flux application step, the flux of the above-described embodiment is applied to the soldering surface of the substrate on which components are mounted.

[0267] As the flux coating apparatus, there are a spray fluxer, a foam fluxer, etc. Among them, a spray fluxer is preferred from the viewpoint of the stability of the coating amount.

[0268] From the viewpoint of solderability, the amount of flux applied is preferably 30 to 180 mL / m 2 , more preferably 40 to 150 mL / m 2 , particularly preferably 50 to 120 mL / m 2 .

[0269] In the preheating step, the substrate on which the components are mounted is preheated. The temperature of the heated substrate in the preheating step is preferably 80 to 130°C, more preferably 90 to 120°C.

[0270] In the soldering step, the soldering surface of the substrate on which the components are mounted is brought into contact with molten solder formed by melting a solder alloy.

[0271] The method for bringing the molten solder into contact with the soldering surface is not particularly limited as long as it is a method that can bring the molten solder into contact with the substrate. Examples of such methods include a jet method and a dipping method.

[0272] The jet method is a method in which the soldering surface of a substrate with components mounted thereon is brought into contact with a jet of molten solder. The immersion method is a method in which the soldering surface of a substrate with components mounted thereon is brought into contact with a still molten solder liquid surface.

[0273] As the solder alloy, a solder alloy having a known composition can be used.

[0274] The solder alloy can also be a solder of Sn alone, or a solder alloy of Sn-Ag, Sn-Cu, Sn-Ag-Cu, Sn-Bi, Sn-In, etc., or a solder alloy with Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, P, etc. added to these alloys.

[0275] The solder alloy may be a Sn-Pb based alloy or a Sn-Pb based alloy with additions of Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, P, etc.

[0276] The solder alloy is preferably a solder alloy not containing Pb, and more preferably a solder alloy containing Sn and Bi.

[0277] The soldering conditions in the soldering process can be appropriately set according to the melting point of the solder. For example, when using a Sn-Ag-Cu solder alloy, the temperature of the molten solder is preferably 230-280°C, more preferably 250-270°C. Alternatively, when using a Sn-Bi solder alloy (a solder alloy containing Sn and Bi), the temperature of the molten solder is preferably 170-220°C, more preferably 180-200°C.

[0278] The above-described method for preparing a joint according to this embodiment can suppress scum from adhering to the surface of the substrate after soldering. Even when using a solder alloy containing Sn and Bi, this method can suppress scum from adhering to the surface of the substrate. Consequently, a joint with improved bonding strength can be produced. Furthermore, a joint that is less likely to cause short circuits or reduce insulation properties can be produced.

[0279] Example

[0280] Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited to the following Examples.

[0281] <Preparation of Flux>

[0282] (Examples 1 to 27, Comparative Examples 1 to 6)

[0283] The fluxes of Examples and Comparative Examples were prepared according to the compositions shown in Tables 2 to 7.

[0284] The raw materials used are as follows.

[0285] The types and softening points of the rosin used are as follows.

[0286] Rosin (P):

[0287] Acrylic acid modified hydrogenated rosin (softening point 130℃)

[0288] Polymerized rosin (softening point 139℃)

[0289] Hydrogenated rosin (softening point 74℃)

[0290] Rosin ester (softening point 90℃)

[0291] The softening point of the rosin is measured by the ring and ball method described in JIS K5902.

[0292] Specifically, first, the sample to be measured is melted as quickly as possible at a low temperature and carefully filled into a ring placed on a flat metal plate so as not to produce bubbles. After cooling, the raised portion of the plane containing the upper end of the ring is cut off with a slightly heated knife. Next, the support (ring holder) is placed in a glass container (heating bath) with a diameter of at least 85 mm and a height of at least 127 mm, and a heat medium is poured into it until the depth is at least 90 mm. Next, a steel ball (diameter 9.5 mm, weight 3.5 g) and the ring filled with the sample are immersed in the heat medium without contact with each other, and the temperature of the heat medium is maintained at 20°C plus or minus 5°C for 15 minutes. Then, the steel ball is placed in the center of the surface of the sample in the ring and placed in a fixed position on the support. Then, the distance from the upper end of the ring to the heat medium surface is maintained at 50 mm, a thermometer is placed so that the center of the mercury ball of the thermometer is at the same height as the center of the ring, and the container is heated. The flame of the Bunsen burner used for heating is located between the center and edge of the bottom of the container, heating it evenly. The rate of bath temperature increase after reaching 40°C after the start of heating was set to 5.0°C plus or minus 0.5°C per minute. The temperature at which the sample gradually softened and finally came into contact with the bottom plate was measured and taken as the softening point.

[0293] Rosins with a softening point of 80°C or less were measured in a water bath using water as the heat medium. Rosins with a softening point exceeding 80°C were measured in a glycerin bath using glycerin as the heat medium. Each rosin was measured twice. The softening point shown above is the average of these two measurements.

[0294] Compound (SA): polyethylene glycol (PEG), polypropylene glycol (PPG), and polyglycerol were used.

[0295] In the general formula (sa), R 11 O is -(CH2)2-O-.

[0296] In the general formula (sa), R 11 O is -CH2-CH(CH3)-O-.

[0297] In the general formula (sa), R 11 O is -CH2-CH(OH)-CH2-O-.

[0298] In PEG, PPG and polyglycerol, R 12 is a hydroxyl group, and R 13 A hydrogen atom.

[0299] Specifically, the following substances were used.

[0300] As PEG, PEG200 (manufactured by Sanyo Chemical Industries, Ltd.), PEG400 (manufactured by Sanyo Chemical Industries, Ltd.), PEG600 (manufactured by Sanyo Chemical Industries, Ltd.), PEG1500 (manufactured by Sanyo Chemical Industries, Ltd.), PEG1540 (manufactured by Sanyo Chemical Industries, Ltd.), and PEG4000S (manufactured by Sanyo Chemical Industries, Ltd.) were used.

[0301] As PPG, PPG400 (manufactured by Wako Pure Chemical Industries, Ltd.), PPG1000 (manufactured by Wako Pure Chemical Industries, Ltd.), and PPG3000 (manufactured by Wako Pure Chemical Industries, Ltd.) were used.

[0302] As the polyglycerol, a mixture of 3 to 6 polymers was used.

[0303] Comparative compounds: Polyoxyethylene behenyl ether, polyethylene glycol stearate, diglycerol monoester, sorbitan monolaurate, sorbitan monostearate

[0304] The chemical formulas of the comparative compounds are shown below, but they do not correspond to the general formula (sa).

[0305] Polyoxyethylene behenyl ether is a compound represented by the following formula (1).

[0306] [Chemical Formula 8]

[0307]

[0308] [In formula (1), n1 is 25 to 35.]

[0309] Polyethylene glycol stearate is a compound represented by the following formula (2).

[0310] [Chemical Formula 9]

[0311]

[0312] [In formula (2), n2 is 100 to 150.]

[0313] Diglycerin monoester is a compound represented by the following formula (3).

[0314] [Chemical Formula 10]

[0315]

[0316] Sorbitan monolaurate is a compound represented by the following formula (4).

[0317] [Chemical Formula 11]

[0318]

[0319] Sorbitan monostearate is a compound represented by the following formula (5).

[0320] [Chemical Formula 12]

[0321]

[0322] Active ingredients: Picolinic acid, 1-amino-2-propanol, adipic acid

[0323] Solvents: 2-propanol, ethanol

[0324] For the above-mentioned compound (SA) and comparative compound, the average molecular weight was determined by gel permeation chromatography (GPC). The average molecular weight is the PEG-converted molecular weight. The equipment and measurement conditions used in the GPC measurement are as follows. The measurement results are shown in Table 1. In Table 1, Mw represents the weight-average molecular weight. In addition, the freezing point of each PEG is also shown.

[0325] Analyzer: EcoSEC HLC-8320GPC manufactured by Tosoh

[0326] Mobile phase: tetrahydrofuran

[0327] Column: TSKguardcolumn HXL manufactured by Tosoh, TSKgel G2000HXL manufactured by Tosoh, TSKgel G1000HXL manufactured by Tosoh

[0328] Column temperature: 40°C

[0329] Flow rate: 1.0 (mL / min), reference 1 / 3

[0330] Detector: RI, Pol(+), Res(0.5s)

[0331] Injection volume: 50 μl

[0332] [Table 1]

[0333] Mw Freezing point PEG200 196 -60℃ PEG400 414 6℃ PEG600 587 20℃ PEG1500 950 40℃ PEG1540 1339 45℃ PEG4000S 3523 56℃ PPG400 463 - PPG1000 988 - PPG3000 3249 - polyglycerol 326 - Polyoxyethylene behenyl ether 1726 - Macrogol stearate 6444 -

[0334] <Preparation of Molten Solder>

[0335] As a mother alloy, an ingot composed of an alloy containing 58 mass % of Bi and the balance of Sn was prepared, and this ingot was melted to prepare a molten solder.

[0336] The evaluation methods described in the following <Evaluation> were used: <Evaluation of Scum Adhesion Suppression Ability>, <Evaluation of Flux Residue Tackiness>. The evaluation results are shown in Tables 2 to 7.

[0337] <Evaluation>

[0338] 《Evaluation of the ability to suppress scum adhesion》

[0339] (1) Evaluation method

[0340] 0.15 mL of the flux of each example was applied to a glass substrate (50 mm×50 mm, 0.7 mm thick) and the obtained substrate was heated at 100° C. for 5 minutes to dry, thereby obtaining a pretreated substrate.

[0341] Next, the pre-treated substrate was immersed in molten solder in a small jet soldering tank in an air atmosphere for 5 seconds.

[0342] The presence or absence of scum on the substrate was visually checked and evaluated based on the following criteria.

[0343] (2) Criteria for determination

[0344] A: No scum was found.

[0345] B: A very small amount of scum was observed.

[0346] C: A small amount of scum was observed.

[0347] D: A large amount of scum was confirmed.

[0348] In the evaluation results, the amount of scum attached to the substrate increased in the order of A to D. The fluxes A to C were found to be acceptable, while the flux D was found to be unacceptable.

[0349] Evaluation of Flux Residue Stickiness

[0350] Evaluation Method

[0351] 0.15 mL of each flux was applied to a glass epoxy substrate (50 mm x 50 mm, 1 mm thick) and then heated to dry to obtain a pretreated substrate. The tackiness of the flux residue was measured for each pretreated substrate in the following manner.

[0352] The pretreated substrate was left to stand on a pedestal heated to 60°C for 3 minutes, and then the tack was measured. The tack was measured using the following apparatus and under the following conditions. In Tables 2 to 7, the unit of the measured tack values ​​is gf. Here, 1 [gf] = 9.8 × 10 -3 [N].

[0353] Apparatus: Viscosity tester (Malcom, model TK-1)

[0354] New entry method: constant pressure intrusion method

[0355] Stamping time: 0.2sec

[0356] Punching pressure: 50gf

[0357] Penetration speed: 2.0mm / sec

[0358] Pull-off speed: 10mm / sec

[0359] [Table 2]

[0360]

[0361] [Table 3]

[0362]

[0363] [Table 4]

[0364]

[0365] [Table 5]

[0366]

[0367] [Table 6]

[0368]

[0369] [Table 7]

[0370]

[0371] It was confirmed that the fluxes of Examples 1 to 27 containing rosin, compound (SA), an activator, and a solvent had higher ability to suppress scum adhesion than the fluxes of Comparative Examples 1 to 6 not containing compound (SA).

[0372] Although the reason for obtaining this effect is not clear, it is speculated as follows.

[0373] In compound (SA), R 12 and R 13 All of these compounds contain hydrocarbon groups, hydroxyl groups, or hydrogen atoms with 5 or fewer carbon atoms, resulting in low hydrophobicity and poor compatibility with rosin. Consequently, rosin and compound (SA) separate, and a layer of compound (SA) easily forms on top of the rosin layer. Consequently, dross on the surface of the molten solder easily flows into the solder tank along with the layer of compound (SA).

[0374] On the other hand, the comparative compound has an alkyl group with 6 or more carbon atoms, is highly hydrophobic, and has high compatibility with rosin. Therefore, rosin and compound (SA) are miscible, making it difficult to form a layer of the comparative compound. Consequently, scum present on the surface of the molten solder tends to remain attached to the flux applied to the substrate.

[0375] From the results of Examples 1, 2, 4, 5, and 27, it can be seen that when rosin (PB) and rosin (PA) are used in combination as rosin (P), the mixing ratio of rosin (PA) having a softening point exceeding 100°C and rosin (PB) having a softening point below 100°C, expressed as a mass ratio (PA) / (PB), is such that when (PA) / (PB) is 4 / 6 or more, the stickiness of the flux residue is further reduced, when it is 5 / 5 or more, the stickiness of the flux residue is further reduced, and when it is 8 / 2 or more, the stickiness of the flux residue is significantly reduced.

[0376] Industrial Applicability

[0377] According to the present invention, a flux and a method for preparing a joint body can be provided that can suppress scum from adhering to the surface of a substrate during soldering. The flux is suitable for flow soldering. The present invention is also suitable for flow soldering using lead-free solder.

Claims

1. A soldering flux comprising rosin (P), a compound (SA) represented by the following general formula (sa), an activator for removing a substance corresponding to the compound (SA), and a solvent for removing a substance corresponding to the compound (SA), The rosin (P) contains rosin (PA) having a softening point exceeding 100° C. and rosin (PB) having a softening point below 100° C., The mixing ratio of the rosin (PA) to the rosin (PB) is (PA) / (PB)=5 / 5 to 9 / 1 in terms of mass ratio represented by (PA) / (PB). The content of the compound (SA) is 0.1% by mass or more and 6% by mass or less relative to the total mass (100% by mass) of the soldering flux, [Chemical formula 1] In formula (sa), R 11 represents a hydrocarbon group which may have a hydroxyl group; R 12 and R 13 Each independently represents a hydrocarbon group having 5 or less carbon atoms which may have a substituent, a hydroxyl group or a hydrogen atom; and m represents a positive integer.

2. The soldering flux according to claim 1, wherein The rosin (PA) contains at least one rosin (P1) selected from the group consisting of acrylic acid-modified hydrogenated rosin and polymerized rosin, and the rosin (PB) contains hydrogenated rosin.

3. The soldering flux according to claim 1 or 2, wherein The content of the compound (SA) is 1 to 60 parts by mass based on 100 parts by mass of the rosin (P).

4. The soldering flux according to claim 1 or 2, wherein The active agent contains a compound represented by the following general formula (a1): [Chemical formula 2] In formula (a1), R 1 , R 2 , R 3 and R 4 Each independently represents a hydrocarbon group, a hydroxyl group, a halogen atom or a hydrogen atom.

5. The soldering flux according to claim 1 or 2, wherein: The active agent contains an alkanolamine.

6. The soldering flux according to claim 1 or 2, wherein: The solvent contains at least one selected from ethanol and 2-propanol.

7. The soldering flux according to claim 1 or 2, wherein: The solid content concentration is 20% by mass or less.

8. A method for preparing a conjugate, the method comprising: A process for obtaining a joint body by soldering a solder alloy on the surface of a substrate treated with the flux according to any one of claims 1 to 7.

9. The method for preparing a conjugate according to claim 8, wherein: The solder alloy includes a solder alloy containing Sn and Bi.

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