Flux and solder paste

Abstract

The present invention provides a flux and a solder paste which can reduce breakage of flux residue due to temperature change, can suppress separation of the solder paste into solder powder and flux over time during storage, and can suppress reduction in solder strength even in the case where an underfill agent is used. A flux containing a resin component, an active agent, and a solvent is used. The resin component contains a copolymer (A) having a repeating unit (a1) from an olefin and a repeating unit (a2) from acrylic acid whose hydrogen atom bonded to a carbon atom at an α position can be substituted with a substituent, and a rosin (B). The mixing ratio of the copolymer (A) to the rosin (B) is 1 or more in terms of a mass ratio represented by copolymer (A) / rosin (B).

Description

Technical Field

[0001] This invention relates to fluxes and solder pastes. This application claims priority based on Japanese Patent Application No. 2022-034818, filed on March 7, 2022, the contents of which are incorporated herein by reference. Background Technology

[0002] Components are typically attached to a substrate and electrically connected to the substrate by soldering. Soldering uses flux, solder powder, and solder paste, which is a mixture of flux and solder powder.

[0003] Flux has the ability to chemically remove metal oxides present on the surfaces of the metals being welded and in the solder, and to allow metal elements to move at the boundary between them. Therefore, by using flux for welding, an intermetallic compound is formed between the two metals, resulting in a strong bond.

[0004] In soldering using solder paste, firstly, solder paste is printed onto a substrate, then components are mounted on it, and the substrate with the mounted components is heated using a furnace called a reflow oven. As a result, the solder powder contained in the solder paste melts, and the components are soldered onto the substrate, thus forming a bond.

[0005] Fluxes typically contain resin components, solvents, activators, thixotropic agents, etc.

[0006] The resin component in the flux applied to the substrate will remain as flux residue in the joint. The flux residue may crack due to temperature rise caused by the operation of the jointing device, or by rise or fall of the external temperature.

[0007] For example, Patent Document 1 proposes a flux containing acrylic resin, which contains rosin, thixotropic agent, and solvent, and can reduce the cracking of flux residues caused by temperature changes.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent No. 6544498 Summary of the Invention

[0011] The problem to be solved by the present invention

[0012] The flux described in Patent Document 1 can reduce the cracking of flux residues caused by temperature changes. Furthermore, solder paste using the flux described in Patent Document 1 can prevent the separation of solder powder and flux over time during storage.

[0013] In the soldering of ball grid arrays or chip components, underfill is applied to the joint to improve solder strength, vibration resistance, and thermal shock resistance. The inventors have discovered that when using the flux and underfill described in Patent Document 1, the thixotropic agent contained in the flux reduces the solder strength.

[0014] Therefore, the object of the present invention is to provide a flux and solder paste that can reduce the cracking of flux residues caused by temperature changes, can suppress the separation of solder paste into solder powder and flux over time during storage, and can also suppress the reduction of solder strength when an underfiller is used.

[0015] Problem-solving methods

[0016] The inventors discovered that even if the flux does not contain a thixotropic agent, by containing a copolymer having repeating units from acrylic acid, it is possible to suppress the solder paste from separating into solder powder and flux over time during storage, thus completing the present invention.

[0017] The present invention includes the following methods.

[0018] [1] A flux comprising a resin component, an activator and a solvent, said resin component comprising a copolymer (A) and rosin (B), said copolymer (A) having repeating units (a1) from olefins and repeating units (a2) from acrylic acid from which hydrogen atoms bonded to carbon atoms at the α-position can be substituted by substituents, said copolymer (A) to said rosin (B) having a mixing ratio of 1 or more by mass as expressed as copolymer (A) / rosin (B).

[0019] [2] According to the flux of [1], wherein the content of the repeating unit (a2) in the copolymer (A) is 3% by mass or more relative to the total mass of the copolymer (A).

[0020] [3] According to the flux described in [1] or [2], wherein the content of the copolymer (A) is 5% by mass or more and 50% by mass or less relative to the total mass of the flux.

[0021] [4] The flux according to any one of [1] to [3], wherein the content of rosin (B) is more than 1% by mass and less than 20% by mass relative to the total mass of the flux.

[0022] [5] The flux according to any one of [1] to [4], wherein the dielectric constant of the solvent is 4 or less.

[0023] [6] According to the flux of [5], wherein the solvent is one or more selected from α-terpineol and 2-hexyl-1-decyl alcohol.

[0024] [7] The flux according to any one of [1] to [6], wherein the flux further comprises a compound represented by the following general formula (2).

[0025] [Chemical Formula 1]

[0026] R 21 -NH2…(2)

[0027] [In the formula, R] 21 This indicates an organic group.

[0028] [8] According to the flux described in [7], wherein the compound represented by the general formula (2) is selected from one or more of monoethanolamine, triethylenetetramine and dipropylenetriamine.

[0029] [9] The flux according to [7] or [8], wherein the flux further comprises a compound represented by the following general formula (3).

[0030] [Chemical Formula 2]

[0031]

[0032] [In the formula, R] 31 This indicates an organic group or a single bond.

[0033]

[10] According to the flux described in [9], wherein the compound represented by the general formula (3) is selected from one or more of malonic acid, succinic acid, glutaric acid, adipic acid and azelaic acid.

[0034]

[11] The flux according to any one of [1] to

[10] , wherein the flux further contains a thixotropic agent, wherein the content of the thixotropic agent is more than 0% by mass and less than 2% by mass relative to the total mass of the flux.

[0035]

[12] The flux according to any one of [1] to

[10] , wherein the flux does not contain a thixotropic agent.

[0036]

[13] A solder paste comprising solder alloy powder and flux as described in any one of [1] to

[12] .

[0037] Effects of the present invention

[0038] According to the present invention, a flux and solder paste can be provided that can reduce the cracking of flux residues caused by temperature changes, can prevent the solder paste from separating into solder powder and flux over time during storage, and can also suppress the reduction of solder strength when an underfiller is used. Attached Figure Description

[0039] Figure 1This is a graph showing the reflow curves of the test substrate used in the evaluation of temperature cycling reliability.

[0040] Figure 2 This is a schematic diagram of the patterned holes of I in the evaluation of the ability to suppress thermal collapse. Detailed Implementation

[0041] (Fluoride)

[0042] The flux in this embodiment contains resin components, activators, and solvents.

[0043] <Resin Composition>

[0044] The resin component contains copolymer (A) and rosin (B).

[0045] In the flux described in this embodiment, the mixing ratio of copolymer (A) and rosin (B) is 1 or more, expressed as the mass ratio of copolymer (A) / rosin (B), that is, the ratio of the total mass of copolymer (A) to the total mass of rosin (B).

[0046] Copolymer (A)

[0047] The copolymer (A) has repeating units (a1) from olefins and repeating units (a2) from acrylic acid from which hydrogen atoms bonded to the carbon atom at the α-position can be substituted by substituents. In addition to repeating units (a1) and (a2), the copolymer (A) may also have other repeating units (a3).

[0048] [Repeating unit (a1)]

[0049] The repeating unit (a1) comes from an olefin.

[0050] Examples of olefins include, for instance, C. n H 2n The compound shown. Here, n is an integer of 2 or more, preferably 2 or more and 10 or less, more preferably 2 or more and 6 or less, even more preferably 2 or more and 3 or less, and particularly preferably 2.

[0051] As C n H 2n The compounds shown may include, for example, ethylene, propylene, isobutylene, 1-butene, 1-pentene, 1-hexene, etc., preferably selected from one or more of ethylene and propylene, more preferably ethylene.

[0052] Alternatively, olefins that are the source of the repeating unit (a1) can be, for example, 1,3-butadiene, 2-methyl-1,3-butadiene, etc.

[0053] The copolymer (A) may have one or more repeating units (a1).

[0054] [Repeating unit (a2)]

[0055] The repeating unit (a2) is derived from acrylic acid. In the repeating unit (a2), the hydrogen atom bonded to the carbon atom at the α-position can be replaced by a substituent. When the carbon atom at the α-position has a substituent, chain-like or branched alkyl groups can be cited as examples of such substituents. The number of carbon atoms in the alkyl group is preferably 1 to 5.

[0056] As a repeating unit (a2), examples include repeating units from acrylic acid, repeating units from methacrylic acid, etc.

[0057] The copolymer (A) may have one or more repeating units (a2).

[0058] [Repeating unit (a3)]

[0059] The repeating unit (a3) ​​is a repeating unit other than repeating units (a1) and repeating units (a2).

[0060] Examples of repeating units (a3) ​​include repeating units from acrylates (hereinafter sometimes referred to as "(α-substituted) acrylates") whose hydrogen atoms bonded to the carbon atom at the α-position can be substituted by substituents, repeating units from epoxides, repeating units having aromatic groups, etc.

[0061] (α-substituted) acrylates refer to one or both of the following: acrylates, or substances formed by replacing the hydrogen atom bonded to the α-carbon atom of an acrylate with a substituent. Examples of such substituents include alkyl groups having 1 to 5 carbon atoms.

[0062] (α-substituted) acrylates are the reaction products of (α-substituted) acrylic acid and alcohols. Examples of alcohols include those with a linear carbon chain and 1 to 24 carbon atoms.

[0063] (α-substituted) acrylic acid refers to one or both of acrylic acid, or a substance in which a hydrogen atom bonded to the α-carbon atom in acrylic acid is replaced by a substituent. Examples of such substituents include alkyl groups having 1 to 5 carbon atoms.

[0064] Examples of (α-substituted) acrylates include, for example, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, tert-butyl acrylate, cyclohexyl acrylate, octyl acrylate, nonyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, benzyl acrylate, anthracene acrylate, glycidyl acrylate, 3,4-epoxycyclohexylmethane acrylate, propyltrimethoxysilane acrylate, etc.; methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, octyl methacrylate, nonyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, benzyl methacrylate, anthracene methacrylate, glycidyl methacrylate, 3,4-epoxycyclohexylmethane methacrylate, propyltrimethoxysilane methacrylate, etc.

[0065] Among them, methyl acrylate, ethyl acrylate, tert-butyl acrylate, methyl methacrylate, ethyl methacrylate, and tert-butyl methacrylate are preferred.

[0066] Examples of epoxides include ethylene oxide, propylene oxide, isopropane oxide, and butane oxide.

[0067] Examples of repeating units having aromatic groups include, for example, repeating units having aromatic groups such as phenyl or naphthyl groups. Examples of repeating units having phenyl groups include, for example, repeating units derived from styrene or its derivatives.

[0068] When copolymer (A) has repeating units (a3), the repeating units (a3) ​​in copolymer (A) can be one type or two or more types.

[0069] In copolymer (A), the content of repeating unit (a1) relative to the total content (100% by mass) of copolymer (A) is preferably 10% by mass or more, more preferably 40% by mass or more, and even more preferably 65% ​​by mass or more.

[0070] The content of the repeating unit (a1) relative to the total (100% by mass) of the copolymer (A) is preferably 98% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less.

[0071] By making the content of repeating unit (a1) above the aforementioned lower limit, the electrical reliability of the joint can be easily improved.

[0072] By keeping the content of repeating units (a1) below the aforementioned upper limit, it is easier to suppress the separation of solder paste into solder powder and flux over time. Furthermore, it is easier to reduce the breakage of flux residues due to temperature changes. Additionally, it is easier to improve solderability. Furthermore, it is easier to improve the solubility of the copolymer (A) in the flux.

[0073] In copolymer (A), the content of repeating unit (a1) relative to the total amount (100% by mass) of copolymer (A) is preferably 10% by mass or more and 98% by mass or less, more preferably 40% by mass or more and 97% by mass or less, and even more preferably 65% ​​by mass or more and 95% by mass or less.

[0074] By setting the content of the repeating unit (a1) to the lower limit of the aforementioned preferred range or higher, the electrical reliability of the joint is easily improved. By setting the content of the repeating unit (a1) to the upper limit of the aforementioned preferred range or lower, the separation of solder paste into solder powder and flux over time is easily suppressed. Furthermore, the cracking of flux residues due to temperature changes is easily reduced. Additionally, solderability is easily improved. Furthermore, the solubility of the copolymer (A) in the flux is easily improved.

[0075] In copolymer (A), the content of repeating unit (a2) relative to the total content (100% by mass) of copolymer (A) is preferably 2% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more.

[0076] The content of the repeating unit (a2) relative to the total (100% by mass) of the copolymer (A) is preferably 90% by mass or less, more preferably 60% by mass or less, and even more preferably 35% by mass or less.

[0077] By ensuring the content of the repeating unit (a2) is above the aforementioned lower limit, it is easier to suppress the separation of solder paste into solder powder and flux over time. Furthermore, it is easier to reduce the breakage of flux residues due to temperature changes. Additionally, it is easier to improve solderability. Furthermore, it is easier to improve the solubility of the copolymer (A) in the flux.

[0078] By keeping the content of repeating unit (a2) below the upper limit, the electrical reliability of the joint can be easily improved.

[0079] The content of the repeating unit (a2) relative to the total content of the copolymer (A) is preferably 2% by mass or more and 90% by mass or less, more preferably 3% by mass or more and 60% by mass or less, and even more preferably 5% by mass or more and 35% by mass or less.

[0080] By ensuring that the content of the repeating unit (a2) is at or above the lower limit of the aforementioned preferred range, it is easier to suppress the separation of solder paste into solder powder and flux over time. Furthermore, it is easier to reduce the breakage of flux residues due to temperature changes. Additionally, it is easier to improve solderability. Furthermore, it is easier to improve the solubility of the copolymer (A) in the flux.

[0081] By keeping the content of the repeating unit (a2) below the upper limit of the above-mentioned preferred range, the electrical reliability of the joint can be easily improved.

[0082] When the copolymer (A) has repeating units (a3), the content of repeating units (a3) ​​in the copolymer (A) is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less, relative to the total content (100% by mass) of the copolymer (A).

[0083] When the copolymer (A) has repeating units (a3), the lower limit of the content of repeating units (a3) ​​in the copolymer (A) is not particularly limited as long as the effect of the present invention can be achieved, and can be, for example, 0.1% by mass relative to the total (100% by mass) of the copolymer (A).

[0084] When the copolymer (A) has repeating units (a3), the content of repeating units (a3) ​​in the copolymer (A) is preferably 0.1% by mass or more and 30% by mass or less relative to the total (100% by mass) of the copolymer (A), more preferably 0.1% by mass or more and 20% by mass or less, and even more preferably 0.1% by mass or more and 10% by mass or less.

[0085] The copolymer (A) can be a random copolymer or a block copolymer.

[0086] Here, in copolymer (A), the number of repetitions of repeating unit (a1) is set to m, and the number of repetitions of repeating unit (a2) is set to n. The molecular weights of repeating unit (a1) and repeating unit (a2) are set to M1 and M2, respectively.

[0087] Let the acid value be P. Let the content of the repeating unit (a2) relative to the total mass (100% by mass) of the copolymer (A) be W% by mass. The formula weight of potassium hydroxide is 56. At this point, the following relationship holds.

[0088] W={n×M2 / (m×M1+n×M2)}×100

[0089] P / 56=(1000×W / 100) / M2

[0090] M / n={(100×560 / P)-M2} / M1

[0091] The copolymer (A) contained in the flux of this embodiment preferably has the structure shown in the following general formula (1).

[0092] [Chemical Formula 3]

[0093]

[0094] [In the formula, R] 1 Represents a hydrogen atom or a methyl group. R 2This represents a hydrogen atom or a methyl group. m and n represent integers greater than or equal to 1.

[0095] The acid value of copolymer (A) is preferably 20 or higher, more preferably 30 or higher, and even more preferably 40 or higher. The acid value is preferably 360 or lower, more preferably 240 or lower, and even more preferably 120 or lower.

[0096] By maintaining the acid value above the aforementioned lower limit, it is easier to suppress the separation of solder paste into solder powder and flux over time. Furthermore, it is easier to reduce the breakage of flux residues due to temperature changes. Additionally, it is easier to improve solderability. Furthermore, it is easier to improve the solubility of the copolymer (A) in the flux.

[0097] By keeping the acid value below the upper limit, the electrical reliability of the joint can be easily improved.

[0098] The acid value of copolymer (A) is preferably 20 or more and 360 or less, more preferably 30 or more and 240 or less, and even more preferably 40 or more and 120 or less.

[0099] By setting the acid value to at least the lower limit of the aforementioned preferred range, it is easy to suppress the separation of solder paste into solder powder and flux over time. Furthermore, it is easy to reduce the breakage of flux residues due to temperature changes. Additionally, it is easy to improve solderability. Furthermore, it is easy to improve the solubility of the copolymer (A) in the flux.

[0100] By setting the acid value below the upper limit of the aforementioned preferred range, the electrical reliability of the joint can be easily improved.

[0101] In this specification, the acid value of copolymer (A) refers to the number of milligrams of potassium hydroxide required to neutralize 1000 mg of copolymer (A).

[0102] The ratio of m to n in the copolymer (A), i.e., the ratio of the number of repetitions m of the repeating unit (a1) to the number of repetitions n of the repeating unit (a2), is preferably 0.1 or more, more preferably 1 or more, and even more preferably 3 or more. As m / n, it is preferably 100 or less, more preferably 75 or less, and even more preferably 50 or less.

[0103] By setting m / n above the aforementioned lower limit, the electrical reliability of the joint can be easily improved.

[0104] By keeping m / n below the aforementioned upper limit, it is easier to suppress the separation of solder paste into solder powder and flux over time. Furthermore, it is easier to reduce the breakage of flux residues due to temperature changes. Additionally, it is easier to improve solderability. Furthermore, it is easier to improve the solubility of the copolymer (A) in the flux.

[0105] As m / n, it is preferably 0.1 or more and 100 or less, more preferably 1 or more and 75 or less, and even more preferably 3 or more and 50 or less.

[0106] By setting m / n to a value above the lower limit of the aforementioned preferred range, the electrical reliability of the joint can be easily improved.

[0107] By setting m / n to below the upper limit of the aforementioned preferred range, it is easier to suppress the separation of solder paste into solder powder and flux over time. Furthermore, it is easier to reduce the breakage of flux residues due to temperature changes. Additionally, it is easier to improve solderability. Furthermore, it is easier to improve the solubility of the copolymer (A) in the flux.

[0108] The weight-average molecular weight of copolymer (A) is preferably 1,000 Mw or more and 50,000 Mw or less, more preferably 1,000 Mw or more and 20,000 Mw or less, even more preferably 1,000 Mw or more and 10,000 Mw or less, and particularly preferably 2,000 Mw or more and 10,000 Mw or less.

[0109] By setting the weight-average molecular weight to a value above the lower limit of the aforementioned preferred range, it is easier to reduce the cracking of flux residues caused by temperature changes.

[0110] By keeping the weight-average molecular weight below the upper limit of the above-mentioned preferred range, it is easy to prevent the solder paste from becoming too viscous.

[0111] In this specification, the weight-average molecular weight refers to the value determined by gel permeation chromatography (GPC), which is the converted molecular weight of polystyrene.

[0112] The copolymer (A) can be used alone or in combination with two or more.

[0113] The content of the copolymer (A) in the flux is preferably 10% by mass or more relative to the total mass (100% by mass) of the flux. The content of the copolymer (A) is preferably 30% by mass or less relative to the total mass (100% by mass) of the flux, more preferably 25% by mass or less, and even more preferably 20% by mass or less.

[0114] By keeping the content of the copolymer (A) above or above the aforementioned lower limit, temperature cycling reliability is easily improved. Furthermore, it is easier to prevent the solder paste from separating into solder powder and flux over time. By keeping the content of the copolymer (A) below or below the aforementioned upper limit, it is easier to prevent the solder paste from becoming excessively viscous.

[0115] The content of the copolymer (A) in the flux is preferably 10% or more and 30% or less relative to the total mass (100% by mass) of the flux, more preferably 10% or more and 25% or less, and even more preferably 10% or more and 20% or less.

[0116] By keeping the content of the copolymer (A) at or above the lower limit of the aforementioned preferred range, temperature cycling reliability is easily improved. Furthermore, it is easier to prevent the solder paste from separating into solder powder and flux over time. By keeping the content of the copolymer (A) below or above the upper limit of the aforementioned preferred range, it is easier to prevent the solder paste from becoming excessively viscous.

[0117] Rosin (B)

[0118] The flux involved in this embodiment contains rosin (B).

[0119] In this invention, "rosin" includes natural resins containing a mixture of arosin acid and its isomers, with arosin acid as the main component, as well as resins obtained by chemically modifying natural resins (sometimes referred to as rosin derivatives).

[0120] For example, the rosin acid content in natural resin is between 40% and 80% by mass relative to natural resin.

[0121] In this specification, "main component" refers to a component that constitutes a compound and is present in a concentration of 40% or more by mass.

[0122] Representative examples of isomers of abietic acid include neorosinic acid, longleaf abietic acid, and L-piperidine. The structure of abietic acid is shown below.

[0123] [Chemical Formula 4]

[0124]

[0125] Examples of "natural resins" include, for example, rosin, wood rosin, and oil rosin.

[0126] In this 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, alkyl epoxide addition, amidation, dimerization and polymerization, esterification and Diels-Alder cyclization addition.

[0127] As rosin derivatives, they include purified rosin and modified rosin.

[0128] Examples of modified rosin include, for example, hydrogenated rosin, polymerized rosin, polymerized hydrogenated rosin, disproportionated rosin, acid-modified rosin, rosin esters, acid-modified hydrogenated rosin, acid anhydride-modified hydrogenated rosin, acid-modified disproportionated rosin, acid anhydride-modified disproportionated rosin, phenol-modified rosin and α,β-unsaturated carboxylic acid modified products (acrylic acid modified rosin, maleic acid modified rosin, fumaric acid modified rosin, etc.), as well as purified products, hydrides and disproportionated products of polymerized rosin, purified products, hydrides and disproportionated products of α,β-unsaturated carboxylic acid modified products, rosin alcohol, rosin amine, hydrogenated rosin alcohol, rosin esters, hydrogenated rosin esters, rosin soap, hydrogenated rosin soap, acid-modified rosin soap, etc.

[0129] Examples of rosin amines include, for example, dehydrorosin ethylamine and dihydrorosin ethylamine. Rosin amines refer to so-called disproportionated rosin amines. The structures of dehydrorosin ethylamine and dihydrorosin ethylamine are shown below.

[0130] [Chemical Formula 5]

[0131]

[0132] Rosin (B) can be used alone or in combination with two or more other types.

[0133] Rosin (B) preferably contains rosin derivatives, and more preferably contains one or more selected from acid-modified hydrogenated rosin and hydrogenated rosin.

[0134] Acid-modified hydrogenated rosin is preferably made from maleic acid-modified hydrogenated rosin.

[0135] The content of rosin (B) in the flux is preferably 1% by mass or more, more preferably 2% by mass or more, relative to the total mass (100% by mass) of the flux.

[0136] The content of rosin (B) is preferably 10% by mass or less, more preferably 6% by mass or less, and even more preferably 4% by mass or less.

[0137] By keeping the rosin (B) content above the aforementioned lower limit, oxidation of the solder powder is easily suppressed. By keeping the rosin (B) content below the aforementioned upper limit, temperature cycling reliability is more easily improved.

[0138] The content of rosin (B) in the flux is preferably 1% or more and 10% or less, more preferably 2% or more and 10% or less, and even more preferably 2% or more and 6% or less, relative to the total mass (100% by mass) of the flux.

[0139] By setting the rosin (B) content to the lower limit of the aforementioned preferred range or above, oxidation of the solder powder is easily suppressed. By setting the rosin (B) content to the upper limit of the aforementioned preferred range or below, temperature cycling reliability is more easily improved.

[0140] In the flux of this embodiment, the mixing ratio of copolymer (A) to rosin (B), expressed as the mass ratio of copolymer (A) / rosin (B), i.e., the ratio of the total mass of copolymer (A) to the total mass of rosin (B), is 1 or more, preferably more than 1, more preferably 2 or more, and even more preferably 3 or more. The mass ratio is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less.

[0141] By setting the mixing ratio above the aforementioned lower limit, temperature cycling reliability can be easily improved. Additionally, solder paste separation suppression capability can be easily improved.

[0142] By keeping the mixing ratio below the aforementioned upper limit, it is easy to prevent the flux viscosity from becoming too high.

[0143] In the flux of this embodiment, the mixing ratio of copolymer (A) to rosin (B) is preferably 1 or more and 30 or less, more preferably more than 1 and 20 or less, even more preferably 2 or more and 10 or less, and particularly preferably 3 or more and 10 or less.

[0144] By setting the mixing ratio to a value above the lower limit of the aforementioned preferred range, temperature cycling reliability can be easily improved. Additionally, solder paste separation suppression capability can be easily improved.

[0145] By keeping the mixing ratio below the upper limit of the above-mentioned preferred range, it is easy to prevent the flux viscosity from becoming too high.

[0146] Other Resins

[0147] The flux of this embodiment may contain resins other than copolymer (A) and rosin (B), or it may not contain other resins, as long as it can achieve the effect of the present invention.

[0148] Other resins include, for example, terpene resins, modified terpene resins, terpene phenol resins, modified terpene phenol resins, styrene resins, modified styrene resins, xylene resins, modified xylene resins, acrylic resins (except for copolymer (A)), polyethylene resins, acrylic-polyethylene copolymer resins, and other thermosetting resins.

[0149] As an acrylic resin (excluding copolymer (A)), for example, an acrylic resin having repeating units derived from (α-substituted) acrylates in copolymer (A) can be cited. The acrylic resin (excluding copolymer (A)) may have one or more repeating units (a1) and (a3) ​​selected from copolymer (A) described above.

[0150] Examples of modified terpene resins include, for example, aromatic modified terpene resins, hydrogenated terpene resins, and hydrogenated aromatic modified terpene resins. Examples of modified terpene phenol resins include, for example, hydrogenated terpene phenol resins. Examples of modified styrene resins include, for example, styrene acrylic resins and styrene maleic acid resins. Examples of modified xylene resins include, for example, phenol modified xylene resins, alkylphenol modified xylene resins, phenol-modified methylphenolic resin-type xylene resins, polyol modified xylene resins, and polyoxyethylene addition xylene resins.

[0151] Other thermosetting resins, for example, include epoxy resins.

[0152] Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, glycidylamine type resin, alicyclic epoxy resin, aminopropane type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, anthracene type epoxy resin, triazine type epoxy resin, dicyclopentadiene type epoxy resin, triphenylmethane type epoxy resin, fluorene type epoxy resin, phenol aralkyl type epoxy resin, and phenolic varnish type epoxy resin.

[0153] When the flux of this embodiment contains other resins, the content of the other resins is preferably more than 0% by mass and less than 10% by mass relative to the total mass (100% by mass) of the flux. The upper limit of the content of the other resins relative to the total mass (100% by mass) of the flux can be 8% by mass, 6% by mass, 4% by mass, 2% by mass, 1% by mass, or 0.5% by mass.

[0154] The resin composition preferably consists only of copolymer (A) and rosin (B).

[0155] Relative to the total mass (100% by mass) of the flux, the total content of the resin component in the flux is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 45% by mass or less, and even more preferably 10% by mass or more and 40% by mass or less.

[0156] <Active Agent>

[0157] The flux in this embodiment contains an activator.

[0158] Examples of active agents include amines, organic acids, and halogen compounds.

[0159] "amine"

[0160] Examples of amines include, for example, rosin amines, azoles, guanidines, alkylamines, aromatic amines, amino alcohols, and amine polyoxyethylene adducts. Rosin amines, as exemplified in the section on rosin, are also examples.

[0161] Examples of azoles include, for instance, 2-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2-heptadecanylimidazole, 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, and 2,4-diamino-6-[2'-methylimidazole-(1')]-ethyltrimethylimidazole. Azine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyltriazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyltriazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyltriazine isocyanuric acid adduct, 2-phenylimidazolyl isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazolium, 2-phenyl-4-methyl-5-hydroxymethylimidazolium, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, 2,4-diamino-6-vinyltriazine, 2,4-Diamino-6-vinyltriazine isocyanuric acid adduct, 2,4-diamino-6-methacryloyloxyethyltriazine, epoxy-imidazolium 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]diethanol, 1-(1',2'-dicarboxyethyl)benzotriazole, 1-(2,3-dicarboxypropyl)benzotriazole, 1-[(2-ethylhexylamino)methyl]benzotriazole, 2,6-Bis[(1H-benzotriazol-1-yl]methyl]-4-methylphenol, 5-methylbenzotriazole, 5-phenyltetrazole, 3-[N-salicylic acid]amino-1,2,4-triazole, etc.

[0162] Examples of guanidines include, for example, 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylguanidine, 1,3-di-o-isopropylphenylguanidine and 1,3-di-o-isopropylphenyl-2-propionylguanidine.

[0163] Examples of alkylamines include ethylamine, triethylamine, ethylenediamine, triethylenetetramine, cyclohexylamine, hexadecylamine, stearylamine, etc.

[0164] Examples of aromatic amines include, for example, aniline, N-methylaniline, diphenylamine, N-isopropylaniline, p-isopropylaniline, m-xylenediamine, toluenediamine, p-xylenediamine, phenylenediamine, 4,4-diaminodiphenylmethane, pyrimidine-2,4,5,6-tetramine, etc.

[0165] Examples of amino alcohols include alkyl alcohols such as 1-amino-2-propanol and N,N,N',N'-tetra(2-hydroxypropyl)ethylenediamine.

[0166] Examples of amine polyoxyethylene adducts include terminal diamine polyalkylene glycols, aliphatic amine polyoxyethylene adducts, aromatic amine polyoxyethylene adducts, and polyamine polyoxyethylene adducts.

[0167] Examples of epoxides that are added to amine polyoxyethylene adducts include ethylene oxide, propylene oxide, and butane oxide.

[0168] Terminal diamine polyalkylene glycols are compounds formed by amylating both ends of polyalkylene glycols.

[0169] Examples of terminal diamine polyalkylene glycols include terminal diamine polyethylene glycol, terminal diamine polypropylene glycol, and terminal diamine polyethylene glycol-polypropylene glycol copolymers.

[0170] Examples of terminal diamine polyethylene glycol-polypropylene glycol copolymers include polyethylene glycol-polypropylene glycol copolymer bis(2-aminopropyl) ether and polyethylene glycol-polypropylene glycol copolymer bis(2-aminoethyl) ether.

[0171] Aliphatic amine polyoxyalkylene adducts, aromatic amine polyoxyalkylene adducts, and polyamine polyoxyalkylene adducts are adducts in which a polyoxyalkylene group is bonded to the nitrogen atom of an amine. Examples of such amines include ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, hexamethylenediamine, diethylenetriamine, laurylamine, stearylamine, oleylamine, tallow amine, cured tallow amine, tallow propyl diamine, m-xylenediamine, toluenediamine, p-xylenediamine, phenylenediamine, isophoronediamine, 1,10-decanediamine, 1,12-dodecanediamine, 4,4-diaminodicyclohexylmethane, 4,4-diaminodiphenylmethane, butane-1,1,4,4-tetramine, and pyrimidine-2,4,5,6-tetramine.

[0172] Amines can be used alone or in combination with two or more.

[0173] As an amine, it is preferably selected from one or more of azoles, alkylamines, aromatic amines and amino alcohols.

[0174] As alkylamines, aromatic amines and amino alcohols, compounds represented by the following general formula (2) are preferred.

[0175] [Chemical Formula 6]

[0176] R 21 -NH2…(2)

[0177] [In the formula, R] 21 This indicates an organic group.

[0178] In equation (2), R is used as 21 Organic groups in the form of substituents include, for example, chain hydrocarbon groups with 1 to 20 carbon atoms that may have substituents, alicyclic hydrocarbon groups with 3 to 20 carbon atoms that may have substituents, and aromatic groups that may have substituents.

[0179] As R 21 Examples of substituents include amino, hydroxyl, carboxyl, acyl, alkoxy, carbonyl, aromatic hydrocarbon groups, and halogen atoms. The aromatic group is a group having at least one aromatic ring; examples include aromatic hydrocarbon rings of benzene, naphthalene, anthracene, and phenanthrene; aromatic heterocycles in which a portion of the carbon atom constituting the aromatic hydrocarbon ring is replaced by a heteroatom; and fused rings formed by the condensation of aromatic hydrocarbon rings and aromatic heterocycles.

[0180] R 21 When the hydrocarbon group is a chain, it can be straight-chain or branched, preferably straight-chain. The chain hydrocarbon group can be saturated or unsaturated, preferably saturated.

[0181] As R 21The number of carbon atoms in the chain hydrocarbon group is preferably 1 to 20, more preferably 1 to 16, even more preferably 1 to 12, and particularly preferably 1 to 8.

[0182] R 21 When the alicyclic hydrocarbon group is used, the alicyclic hydrocarbon group can be a polycyclic group or a monocyclic group.

[0183] As R 21 The number of carbon atoms in the alicyclic hydrocarbon group is preferably 3 to 20, more preferably 3 to 16, even more preferably 3 to 12, and particularly preferably 3 to 8.

[0184] R 21 When it is an aromatic group, examples of such aromatic groups include those in R. 21 The substituents described herein are the groups.

[0185] As R 21 Organic groups, preferably chain hydrocarbon groups.

[0186] R 21 The organic groups in it preferably have amino or hydroxyl groups.

[0187] Examples of compounds represented by the general formula (2) above include monoethanolamine, triethylenetetramine, dipropylenetriamine, ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, hexamethylenediamine, m-xylenediamine, toluenediamine, p-xylenediamine, phenylenediamine, isophoronediamine, 1,10-decanediamine, 1,12-dodecanediamine, 4,4-diaminodicyclohexylmethane, 4,4-diaminodiphenylmethane, butane-1,1,4,4-tetramine, pyrimidine-2,4,5,6-tetramine, etc., preferably containing one or more selected from monoethanolamine, triethylenetetramine, and dipropylenetriamine.

[0188] When the flux of this embodiment contains the compound shown in the general formula (2) above, the content of the compound relative to the total mass (100% by mass) of the flux is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and even more preferably 0.05% by mass or more. Furthermore, the content of the compound relative to the total mass (100% by mass) of the flux is preferably 1.00% by mass or less, more preferably 0.50% by mass or less, and even more preferably 0.20% by mass or less.

[0189] By ensuring that the content of the compound is above the aforementioned lower limit, the ability to suppress thermal collapse can be easily improved.

[0190] By keeping the content of the compound below the aforementioned upper limit, the printability of the solder paste can be easily improved.

[0191] Relative to the total mass (100% by mass) of the flux, the content of the compound represented by the above general formula (2) is preferably 0.01% by mass or more and 1.00% by mass or less, preferably 0.03% by mass or more and 0.50% by mass or less, and more preferably 0.05% by mass or more and 0.20% by mass or less.

[0192] By setting the content of the compound above or below the lower limit of the above-preferred range, the ability to suppress heat-induced slump is easily improved; by setting it below the upper limit of the above-preferred range, the printability of the solder paste is easily improved.

[0193] Relative to the total mass (1 kg) of the flux, the content of the compound represented by the above general formula (2) is preferably 0.001 mol / kg or more and 0.050 mol / kg or less, more preferably 0.003 mol / kg or more and 0.030 mol / kg or less, and even more preferably 0.004 mol / kg or more and 0.020 mol / kg or less.

[0194] By setting the content of the compound above or below the lower limit of the above-preferred range, the ability to suppress heat-induced slump is easily improved; by setting it below the upper limit of the above-preferred range, the printability of the solder paste is easily improved.

[0195] When the flux of this embodiment contains azoles, the content of azoles is preferably 2% by mass or more and 8.5% by mass or less relative to the total mass (100% by mass) of the flux.

[0196] By setting the content of the azoles above or below the lower limit of the aforementioned preferred range, the wettability of the flux is easily improved. This, in turn, easily improves solderability. By setting the content of the azoles below or below the upper limit of the aforementioned preferred range, the electrical reliability of the joint is easily improved.

[0197] When the flux of this embodiment contains the compound shown in the above general formula (2) and azoles, the mixing ratio of the compound shown in the above general formula (2) to the azoles, expressed as the mass ratio of the compound / azole shown in the above general formula (2), is preferably 0.001 or more and 0.500 or less, more preferably 0.003 or more and 0.250 or less, even more preferably 0.005 or more and 0.100 or less, and particularly preferably 0.010 or more and 0.040 or less.

[0198] By setting the mixing ratio to the lower limit of the aforementioned preferred range or above, the ability to suppress heat-induced slump is easily improved; by setting it to the upper limit of the aforementioned preferred range or below, the printability of the solder paste is easily improved.

[0199] Organic acids

[0200] 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.

[0201] Examples of aliphatic monocarboxylic acids include, for example, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, isononanoic acid, decanoic acid, decenoic acid, lauric acid (dodecanoic acid), undecanoic acid, icosanoic acid, tridecanoic acid, myristone acid, pentadecanoic acid, isopalmitic acid, palmitoleic acid, hexadecanetrienoic acid, cyclopentene undecanoic acid, heptadecanic acid, isostearic acid, transoleic acid, phellandrene, stearatetraenoic acid, tung acid, tarric acid, isoleic acid, piperidinic acid, styracidin, nonadecanic acid, eicosanoic acid, stearic acid, 12-hydroxystearic acid, oleic acid, linoleic acid, linolenic acid, myristic acid, etc.

[0202] Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, eicosanoic acid, diethylene glycol, tartaric acid, and 2,4-diethylglutaric acid.

[0203] Examples of aromatic carboxylic acids include, for example, salicylic acid, dibutylaniline diethanolic acid, terephthalic acid, p-hydroxyphenylacetic acid, phenylsuccinic acid, phthalic acid, benzoic acid, 2,3-dihydroxybenzoic acid, 2-quinoline carboxylic acid, 3-hydroxybenzoic acid, and p-anestic acid.

[0204] In addition, examples of carboxylic acids include tris(2-carboxyethyl) isocyanurate and 1,3-cyclohexanedicarboxylic acid.

[0205] In addition, compounds represented by the following general formula (c1) can be cited as carboxylic acids.

[0206] R 11 -COOH···(c1)

[0207] [In the formula, R] 11 This refers to a chain hydrocarbon group with 2 to 15 carbon atoms, an alicyclic hydrocarbon group with 3 to 15 carbon atoms, or an aromatic group. Among them, R... 11 It contains hydroxyl groups.

[0208] R 11 The chain hydrocarbon group mentioned therein can be either straight-chain or branched.

[0209] The chain hydrocarbon group and the alicyclic hydrocarbon group can be saturated hydrocarbon groups or unsaturated hydrocarbon groups, preferably saturated hydrocarbon groups.

[0210] The chain hydrocarbon group preferably has 2 to 12 carbon atoms, more preferably 3 to 9, particularly preferably 3 to 7, and most preferably 3 to 5.

[0211] Examples of the chain hydrocarbon groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, tert-pentyl, neopentyl, n-hexyl, isohexyl, sec-hexyl, tert-hexyl, neohexyl, etc.

[0212] The alicyclic hydrocarbon group preferably has 3 to 12 carbon atoms, more preferably 4 to 12, and even more preferably 4 to 8.

[0213] Examples of alicyclic hydrocarbon groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, and cycloundecyl.

[0214] As R 11 The aromatic groups mentioned in R can be exemplified by those in R 21 The substituents described herein are the groups.

[0215] R 11 When the aromatic group in the text has a substituent, examples of substituents include hydrocarbon groups with 1 to 20 carbon atoms, aromatic hydrocarbon groups, carboxyl groups, hydroxyl groups, amino groups, halogen atoms, etc., with carboxyl groups or hydroxyl groups being preferred.

[0216] Hydroxycarboxylic acids can be cited as examples of organic acids represented by the above general formula (c1).

[0217] Examples of hydroxycarboxylic acids include, for example, 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butyric acid, citric acid, isocitric acid, malic acid, tartaric acid, etc.

[0218] In addition, polycarboxylic acids can be cited as examples of carboxylic acids.

[0219] Examples of polycarboxylic acids include dimer acids, trimer acids, hydrogenated dimer acids as hydrides of hydrogenated dimer acids, hydrogenated trimer acids as hydrides of hydrogenated trimer acids, and so on.

[0220] Examples of dimer and trimer acids include, for instance, dimer acids reacting with oleic acid and linoleic acid, trimer acids reacting with oleic acid and linoleic acid, dimer acids reacting with acrylic acid, trimer acids reacting with acrylic acid, dimer acids reacting with methacrylic acid, trimer acids reacting with methacrylic acid, dimer acids reacting with acrylic acid and methacrylic acid, trimer acids reacting with acrylic acid and methacrylic acid, dimer acids reacting with oleic acid, trimer acids reacting with linoleic acid, dimer acids reacting with linolenic acid, trimer acids reacting with linolenic acid, dimer acids reacting with acrylic acid and oleic acid, trimer acids reacting with acrylic acid and oleic acid, and dimer acids reacting with acrylic acid and linoleic acid. Acids, trimeric acids as reactants of acrylic acid and linoleic acid, dimeric acids as reactants of acrylic acid and linolenic acid, trimeric acids as reactants of acrylic acid and linolenic acid, dimeric acids as reactants of methacrylic acid and oleic acid, trimeric acids as reactants of methacrylic acid and oleic acid, trimeric acids as reactants of methacrylic acid and linoleic acid, trimeric acids as reactants of methacrylic acid and linolenic acid, trimeric acids as reactants of methacrylic acid and linolenic acid, trimeric acids as reactants of methacrylic acid and linolenic acid, trimeric acids as reactants of oleic acid and linolenic acid, trimeric acids as reactants of linoleic acid and linolenic acid, trimeric acids as reactants of linoleic acid and linolenic acid, hydrogenated dimeric acids as hydrogenates of the above-mentioned dimeric acids, hydrogenated trimeric acids as hydrogenates of the above-mentioned trimeric acids, etc.

[0221] For example, the dimer acid that is a reactant of oleic acid and linoleic acid is a dimer with 36 carbon atoms. Furthermore, the trimer acid that is a reactant of oleic acid and linoleic acid is a trimer with 54 carbon atoms.

[0222] When the flux in this embodiment contains a polycarboxylic acid, the content of the polycarboxylic acid is preferably 3% or more and 20% or less, more preferably 5% or more and 15% or less, relative to the total mass (100% by mass) of the flux.

[0223] By setting the content of the polycarboxylic acid above or below the lower limit of the aforementioned preferred range, weldability is easily improved. By setting the content of the polycarboxylic acid below or below the upper limit of the aforementioned preferred range, the electrical reliability of the joint is easily improved.

[0224] In addition, compounds represented by the following general formula (p1) can be cited as carboxylic acids.

[0225] [Chemical Formula 7]

[0226]

[0227] In formula (p1), R 71 R 72 R 73 and R 74 Each can independently represent a hydrocarbon group, hydroxyl group, halogen atom, or hydrogen atom.

[0228] As R 71 R 72 R 73 and R 74 Examples of hydrocarbon groups include chain hydrocarbon groups with 1 to 20 carbon atoms that can have substituents, alicyclic hydrocarbon groups with 3 to 20 carbon atoms that can have substituents, amino groups, hydroxyl groups, carboxyl groups, etc.

[0229] The chain-like hydrocarbon group can be straight-chain or branched. The chain-like hydrocarbon group can be saturated or unsaturated, preferably saturated.

[0230] The alicyclic hydrocarbon group can be a polycyclic group or a monocyclic group. As a monocyclic alicyclic hydrocarbon group, it is preferably a group formed by removing one or more hydrogen atoms from a monocyclic alkane. As a polycyclic alicyclic hydrocarbon group, it is preferably a group formed by removing one or more hydrogen atoms from a polycyclic alkane.

[0231] As R 71 R 72 R 73 and R 74 The hydrocarbon group in the hydrocarbon group can have substituents, such as amino, hydroxyl, carboxyl, acyl, alkoxy, carbonyl, and halogen atoms.

[0232] The preferred hydrocarbon group is a chain hydrocarbon group or carboxyl group having 1 to 5 carbon atoms and which may have substituents. 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, neopentyl, etc. Carboxyl groups are preferred.

[0233] Examples of compounds represented by the above general formula (p1) include pyridinecarboxylic acid, pyridinedicarboxylic acid, and 3-hydroxypyridinecarboxylic acid.

[0234] 3-Hydroxypyridinecarboxylic acid is R in the above general formula (p1) 71 It is a hydroxyl group and R 72 R 73 and R 74 Compounds containing hydrogen atoms.

[0235] Examples of organic sulfonic acids include, for example, aliphatic sulfonic acids and aromatic sulfonic acids. Examples of aliphatic sulfonic acids include, for example, alkane sulfonic acids and alkanolic sulfonic acids.

[0236] Examples of alkane sulfonic acids include, for example, methane sulfonic acid, ethane sulfonic acid, 1-propane sulfonic acid, 2-propane sulfonic acid, 1-butane sulfonic acid, 2-butane sulfonic acid, pentane sulfonic acid, hexane sulfonic acid, decane sulfonic acid, dodecane sulfonic acid, etc.

[0237] Examples of alkanol sulfonic acids include, for example, 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.

[0238] Examples of aromatic sulfonic acids include, for example, 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.

[0239] Organic acids can be used alone or in combination with two or more.

[0240] The organic acid preferably contains a carboxylic acid, and more preferably contains one or more selected from polycarboxylic acids, aliphatic dicarboxylic acids, and aromatic carboxylic acids.

[0241] As an aliphatic dicarboxylic acid, the compound represented by the following general formula (3) is preferred.

[0242] [Chemical Formula 8]

[0243]

[0244] [In the formula, R] 31 This indicates an organic group or a single bond.

[0245] In equation (3), R is used as 31 The organic group may include, for example, a chain hydrocarbon group having 1 to 20 carbon atoms that may have substituents, or an alicyclic hydrocarbon group having 3 to 20 carbon atoms that may have substituents, preferably a chain hydrocarbon group. The methylene group in the hydrocarbon group may also be replaced by an oxygen atom.

[0246] As R 31 Examples of substituents include amino, hydroxyl, carboxyl, acyl, alkoxy, carbonyl, and halogen atoms.

[0247] R 31 When the hydrocarbon group is a chain, it can be straight-chain or branched, preferably straight-chain. The chain hydrocarbon group can be saturated or unsaturated, preferably saturated.

[0248] As R 31The number of carbon atoms in the chain hydrocarbon group is preferably 1 to 20, more preferably 1 to 16, even more preferably 1 to 12, and particularly preferably 1 to 8.

[0249] R 31 When the alicyclic hydrocarbon group is used, the alicyclic hydrocarbon group can be a polycyclic group or a monocyclic group.

[0250] As R 31 The number of carbon atoms in the alicyclic hydrocarbon group is preferably 3 to 20, more preferably 3 to 16, even more preferably 3 to 12, and particularly preferably 3 to 8.

[0251] As the compound represented by the above general formula (3), it preferably contains one or more selected from oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, eicosanoic acid and diethylene glycol, and more preferably contains one or more selected from malonic acid, succinic acid, glutaric acid, adipic acid and azelaic acid.

[0252] When the flux of this embodiment contains the compound shown in the above general formula (3), the content of the compound is preferably 0.02% by mass or more, more preferably 0.04% by mass or more, and even more preferably 0.06% by mass or more, relative to the total mass (100% by mass) of the flux.

[0253] Furthermore, relative to the total mass (100% by mass) of the flux, the content of the compound is preferably 35% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less.

[0254] By setting the content of the compound above or above the aforementioned lower limit, the ability to suppress thermal collapse is easily improved. By setting the content of the compound below or above the aforementioned upper limit, the electrical reliability of the joint is easily improved.

[0255] When the flux of this embodiment contains the compound shown in the general formula (3) above, the content of the compound is preferably 0.02% by mass or more and 35% by mass or less relative to the total mass (100% by mass) of the flux, more preferably 0.04% by mass or more and 30% by mass or less, and even more preferably 0.06% by mass or more and 25% by mass or less.

[0256] By setting the content of the compound above or below the lower limit of the above-mentioned preferred range, the ability to suppress thermal collapse is easily improved; by setting it below the upper limit of the above-mentioned preferred range, the electrical reliability of the joint is easily improved.

[0257] In the flux of this embodiment, the mixing ratio of the compound shown in general formula (2) and the compound shown in general formula (3), measured by the molar ratio of the compound shown in general formula (3) to the compound shown in general formula (2), that is, the ratio of the total number of moles shown in general formula (3) to the total number of moles shown in general formula (2), is preferably 0.3 or more, more preferably 0.5 or more, further preferably 0.7 or more, and particularly preferably 1.00 or more. The upper limit of the molar ratio of the compound shown in general formula (3) to the compound shown in general formula (2) is not particularly limited; for example, it can be 1000 or 500.

[0258] The molar ratio of the compound represented by the above general formula (3) to the compound represented by the above general formula (2) is preferably 0.3 or more and 1000 or less, more preferably 0.5 or more and 1000 or less, even more preferably 0.7 or more and 1000 or less, and particularly preferably 1.00 or more and 1000 or less.

[0259] Alternatively, the molar ratio of the compound represented by the above general formula (3) to the compound represented by the above general formula (2) is preferably 0.3 or more and 500 or less, more preferably 0.5 or more and 500 or less, even more preferably 0.7 or more and 500 or less, and particularly preferably 1.00 or more and 500 or less.

[0260] The total content of the organic acid in the flux is preferably 5% by mass or more and 35% by mass or less, more preferably 7% by mass or more and 30% by mass or less, relative to the total mass (100% by mass) of the flux.

[0261] By setting the total content of the organic acids to the lower limit of the aforementioned preferred range, the wettability of the flux is easily improved. This, in turn, easily improves solderability. By setting the total content of the organic acids to the upper limit of the aforementioned preferred range, the electrical reliability of the joint is easily improved.

[0262] Halogen compounds

[0263] Examples of halogen compounds include, for example, hydrohalates and other organic halogen compounds.

[0264] Amino halides are compounds formed by reacting amines with hydrogen halides.

[0265] As for amines here, we can cite substances described in "Amines".

[0266] More specifically, examples of amine hydrohalides include, for instance, cyclohexylamine hydrobromide, hexadecylamine hydrobromide, stearylamine hydrobromide, ethylamine hydrobromide, diphenylguanidine hydrobromide, ethylamine hydrochloride, stearylamine hydrochloride, diethylaniline hydrochloride, diethanolamine hydrochloride, 2-ethylhexylamine hydrobromide, pyridine hydrobromide, isopropylamine hydrobromide, diethylamine hydrobromide, 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, diallyl... Allylamine hydrochloride, diallylamine hydrobromide, diethylamine hydrochloride, triethylamine hydrobromide, triethylamine hydrochloride, hydrazine monohydrochloride, hydrazine dihydrobromide, hydrazine monohydrobromide, hydrazine dihydrobromide, pyridine hydrochloride, aniline hydrobromide, butylamine hydrochloride, hexylamine hydrochloride, n-octylamine hydrochloride, dodecylamine hydrochloride, dimethylcyclohexylamine hydrobromide, ethylenediamine dihydrobromide, rosinamine hydrobromide, 2-phenylimidazolium 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.

[0267] Alternatively, as halogen activators, salts formed by reacting amines with tetrafluoroboric acid (HBF4) or complexes formed by reacting amines with boron trifluoride (BF3) can also be used.

[0268] Examples of such complexes include boron trifluoride piperidine.

[0269] Other than amine hydrohalides, organohalogen compounds include, for example, halogenated aliphatic compounds. A halogenated aliphatic hydrocarbon group is a group in which some or all of the hydrogen atoms constituting the aliphatic hydrocarbon group are replaced by halogen atoms.

[0270] Examples of halogenated aliphatic compounds include halogenated fatty alcohols and halogenated heterocyclic compounds.

[0271] Examples of halogenated aliphatic alcohols include, for example, 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-buten-1,4-diol.

[0272] Examples of halogenated heterocyclic compounds include those represented by the general formula (h1).

[0273] R 22 -(R 23 ) n (h1)

[0274] [In the formula, R] 22 Represents an n-valent heterocyclic group. R 23 This indicates a halogenated aliphatic hydrocarbon group.

[0275] As R 22 The heterocycle with an n-valent heterocyclic group can be exemplified by a ring structure in which a portion of the carbon atom constituting an aliphatic or aromatic hydrocarbon ring is replaced by a heteroatom. Examples of heteroatoms in this heterocycle include oxygen, sulfur, and nitrogen atoms. This heterocycle is preferably a 3- to 10-membered ring, more preferably a 5- to 7-membered ring. Examples of such heterocycles include isocyanurate rings.

[0276] R 23 The halogenated aliphatic hydrocarbon group in the compound preferably has 1 to 10 carbon atoms, more preferably 2 to 6 carbon atoms, and even more preferably 3 to 5 carbon atoms. Additionally, R... 23 Preferably, it is a brominated aliphatic hydrocarbon group or a chlorinated aliphatic hydrocarbon group, more preferably a brominated aliphatic hydrocarbon group, and even more preferably a brominated saturated aliphatic hydrocarbon group.

[0277] Examples of halogenated heterocyclic compounds include tri-(2,3-dibromopropyl)isocyanurate.

[0278] In addition, as organic halogen compounds other than aminohydrohalogenates, examples include iodinated carboxyl compounds such as 2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, and 5-iodoaminoanisic 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.

[0279] Halogen compounds can be used alone or in combination of two or more.

[0280] Relative to the total mass (100% by mass) of the flux, the total content of activator in the flux is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 45% by mass or less, and even more preferably 15% by mass or more and 40% by mass or less.

[0281] <Solvent>

[0282] Examples of solvents include water, alcohols, glycol ethers, and terpineols.

[0283] Examples of alcohol-based solvents include isopropanol, 1,2-butanediol, 1,3-butanediol, isobornylcyclohexanol, 2,4-diethyl-1,5-pentanediol, 2,2-dimethyl-1,3-propanediol, 2,5-dimethyl-2,5-hexanediol, 2,5-dimethyl-3-hexyn-2,5-diol, 2,3-dimethyl-2,3-butanediol, 2-methylpentane-2,4-diol, and 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-cyclohexanediol, 2,4,7,9-tetramethyl-5-decyn-4,7-diol, 2-hexyl-1-decanol, octanediol, etc.

[0284] Examples of glycol ether solvents include, for example, diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, diethylene glycol monohexyl ether (hexyl diethylene glycol), diethylene glycol dibutyl ether, triethylene glycol monobutyl ether, methpropylene triethylene glycol, triethylene glycol butyl methyl ether, tetraethylene glycol, tetraethylene glycol dimethyl ether, and tripropylene glycol n-butyl ether.

[0285] Examples of terpineols include, for example, α-terpineol, β-terpineol, γ-terpineol, and mixtures of terpineols (i.e., mixtures whose main component is α-terpineol and which contain β-terpineol or γ-terpineol).

[0286] Other solvents include, for example, dioctyl sebacate (DOS) and liquid paraffin.

[0287] The flux in this embodiment preferably contains a solvent with a dielectric constant of 4 or less.

[0288] Examples of solvents with a dielectric constant of 4 or less include α-terpineol, β-terpineol, γ-terpineol, mixtures of terpineols, 2-hexyl-1-decyl alcohol, octanediol, dioctyl sebacate (DOS), and liquid paraffin, preferably selected from one or more of α-terpineol and 2-hexyl-1-decyl alcohol.

[0289] As long as the effects of the present invention can be achieved, there is no particular limitation on the lower limit of the dielectric constant of solvents with a dielectric constant of 4 or less. For example, the lower limit can be 1.5, 1.7, 1.9 or 2.0.

[0290] In this specification, the dielectric constant of the solvent refers to the measured value of the dielectric constant at 1 GHz using a dielectric constant measuring device (manufactured by AET Corporation) based on the void resonator method according to JIS C2565:1992 standard.

[0291] Alternatively, the dielectric constant of the solvent can also refer to the measured value of the dielectric constant as determined according to ASTM D2520.

[0292] Solvents can be used alone or in combination with two or more.

[0293] When the flux of this embodiment contains a solvent with a dielectric constant of 4 or less, the content of the solvent with a dielectric constant of 4 or less is preferably 5% or more and 20% or less, more preferably 5% or more and 15% or less, and even more preferably 5% or more and 10% or less, relative to the total mass (100% by mass) of the flux.

[0294] The solvent is the remaining portion of the flux in this embodiment, and its content is determined based on the other components. In this embodiment, the solvent content, for example, relative to the total mass (100% by mass) of the flux, can be 25% by mass or more and 70% by mass or less, or 30% by mass or more and 60% by mass or less.

[0295] In addition to resin components, activators, and solvents, the flux in this embodiment may also contain other components as needed.

[0296] Other components include thixotropic agents, surfactants, metal passivators, antioxidants, silane coupling agents, and colorants.

[0297] Thixotropic agents

[0298] Examples of thixotropic agents include ester-based thixotropic agents, amide-based thixotropic agents, and sorbitol-based thixotropic agents.

[0299] Examples of ester-based thixotropic agents include, for example, ester compounds, specifically hydrogenated castor oil and ethyl myristate.

[0300] Examples of amide-based thixotropic agents include monoamides, diamides, and polyamides.

[0301] Examples of monoamides include laurylamide, palmitamide, stearamide, behenamide, hydroxystearamide, saturated fatty acid amide, oleamide, erucamide, unsaturated fatty acid amide, 4-methylbenzamide (p-toluamide), p-toluenemethaneamide, aromatic amide, hexamethylene hydroxystearamide, substituted amide, hydroxymethylstearamide, hydroxymethylamide, fatty acid ester amide, etc.

[0302] Examples of diamides include ethylenedicarboxylic acid (C6-24 carbon atoms in fatty acids) amides, ethylenedihydroxycarboxylic acid (C6-24 carbon atoms in fatty acids) amides, hexamethylenedicarboxylic acid (C6-24 carbon atoms in fatty acids) amides, hexamethylenedihydroxycarboxylic acid (C6-24 carbon atoms in fatty acids) amides, and aromatic diamides. Examples of fatty acids used as raw materials for these diamides include stearic acid (C18 carbon atoms), oleic acid (C18 carbon atoms), and lauric acid (C12 carbon atoms).

[0303] Examples of polyamides include saturated fatty acid polyamides, unsaturated fatty acid polyamides, aromatic polyamides, 1,2,3-propanetricarboxylic acid tris(2-methylcyclohexylamide), cyclic amide oligomers, and non-cyclic amide oligomers.

[0304] Examples of cyclic amide oligomers include amide oligomers obtained by condensing dicarboxylic acids and diamines into a cyclic form, amide oligomers obtained by condensing tricarboxylic acids and diamines into a cyclic form, amide oligomers obtained by condensing dicarboxylic acids and triamines into a cyclic form, amide oligomers obtained by condensing tricarboxylic acids and triamines into a cyclic form, amide oligomers obtained by condensing dicarboxylic acids and tricarboxylic acids and diamines into a cyclic form, amide oligomers obtained by condensing dicarboxylic acids and tricarboxylic acids and triamines into a cyclic form, amide oligomers obtained by condensing dicarboxylic acids and diamines and triamines into a cyclic form, and amide oligomers obtained by condensing dicarboxylic acids and tricarboxylic acids and diamines and triamines into a cyclic form.

[0305] Furthermore, examples of acyclic amide oligomers include those obtained by the condensation polymerization of monocarboxylic acids with diamines and / or triamines to form acyclic amide oligomers, and those obtained by the condensation polymerization of dicarboxylic acids and / or tricarboxylic acids with monoamines to form acyclic amide oligomers. When the amide oligomer contains a monocarboxylic acid or a monoamine, the monocarboxylic acid or monoamine functions as terminal molecules, resulting in acyclic amide oligomers with reduced molecular weight. Additionally, in the case of amide compounds obtained by the condensation polymerization of dicarboxylic acids and / or tricarboxylic acids with diamines and / or triamines to form acyclic amide compounds, the acyclic amide oligomer becomes an acyclic polymeric amide polymer. Furthermore, acyclic amide oligomers also include those obtained by the condensation polymerization of monocarboxylic acids and monoamines to form acyclic amide oligomers.

[0306] Examples of sorbitol-based thixotropic agents include, for example, dibenzylidene-D-sorbitol, di(4-methylbenzylidene)-D-sorbitol, (D-)sorbitol, monobenzylidene(-D-)sorbitol, and mono(4-methylbenzylidene)-(D-)sorbitol.

[0307] The flux in this embodiment may or may not contain a thixotropic agent.

[0308] The flux of this embodiment can prevent the solder paste from separating into solder powder and flux over time during storage, even if the content of thixotropic agent is low or there is no thixotropic agent.

[0309] When the flux in this embodiment contains a thixotropic agent, the thixotropic agent can be used alone or in combination with two or more.

[0310] When the flux in this embodiment contains a thixotropic agent, an ester-based thixotropic agent is preferred, and hydrogenated castor oil is more preferred.

[0311] When the flux in this embodiment contains a thixotropic agent, the content of the thixotropic agent relative to the total mass (100% by mass) of the flux is preferably more than 0% by mass and less than 5% by mass, more preferably more than 0% by mass and less than 4% by mass, particularly preferably more than 0% by mass and less than 3% by mass, and most preferably more than 0% by mass and less than 2% by mass. The upper limit of the thixotropic agent content can be 1.8% by mass, 1.6% by mass, 1.4% by mass, 1.2% by mass, 1.0% by mass, 0.8% by mass, 0.6% by mass, 0.4% by mass, 0.2% by mass, or 0.1% by mass.

[0312] By keeping the thixotropic agent content below the upper limit of the aforementioned preferred range, it is easy to suppress the precipitation of the thixotropic agent on the surface of flux residue. Therefore, when using an underfiller, it is easy to suppress the reduction in solder strength. Furthermore, even when the thixotropic agent content is below the upper limit, it is also possible to prevent the solder paste from separating into solder powder and flux over time during storage.

[0313] Surfactants

[0314] Examples of surfactants include, for instance, nonionic surfactants.

[0315] Examples of nonionic surfactants include, for instance, polyoxyethylene adducts.

[0316] Examples of epoxides derived from polyoxyethylene adducts include ethylene oxide, propylene oxide, and butane oxide.

[0317] Examples of polyoxyethylene adducts include, for example, polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol copolymer, ethylene oxide-resorcinol copolymer, polyoxyethylene acetylene glycol, polyoxyethylene glycerol ether, polyoxyethylene alkyl ether, polyoxyethylene ester, and polyoxyethylene alkylamide.

[0318] Alternatively, polyoxyethylene adducts of alcohols can be cited as nonionic surfactants. Examples of alcohols include, for instance, aliphatic alcohols, aromatic alcohols, and polyols.

[0319] Surfactants can be used alone or in combination with two or more.

[0320] Metal passivating agents

[0321] Examples of metal passivating agents include hindered phenolic compounds and nitrogen compounds.

[0322] The "metal passivating agent" mentioned here refers to a compound that has the property of preventing metals from deteriorating due to contact with a certain compound.

[0323] Hindered phenolic compounds are phenolic compounds that have a large substituent (such as a branched chain or cyclic alkyl group such as tert-butyl) at at least one ortho position of phenol.

[0324] As hindered phenolic compounds, there are no particular limitations; examples 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'-dihydroxy-3,3'-bis[α-methylcyclohexyl]-5,5'-dimethyldiphenylmethane, 2,2'-methylenebis(6-tert-butyl-p-cresol), 2,2'-methylenebis(6-tert-butyl-4-ethylphenol), triethylene glycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,4 -bis(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylimino)-1,3,5-triazine, pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2-thiodiethylidene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-hexamethylene Compounds such as 3,5-di-tert-butyl-4-hydroxy-hydrogenated cinnamamide, 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, N,N'-bis[2-[2-(3,5-di-tert-butyl-4-hydroxyphenyl)ethylcarbonyloxy]ethyl]oxalamide, and compounds shown in the following chemical formulas.

[0325] [Chemical Formula 9]

[0326]

[0327] (Where, Z represents a substituted alkylene group. R) 81 and R 82Each can be independently a substituted alkyl, aralkyl, aryl, heteroaryl, cycloalkyl, or heterocycloalkyl group. 83 and R 84 Each is an alkyl group that can be substituted independently.

[0328] Nitrogen compounds used as metal passivating agents include, for example, hydrazide nitrogen compounds, amide nitrogen compounds, triazole nitrogen compounds, and melamine nitrogen compounds.

[0329] As nitrogen compounds in the acylhydrazine system, any nitrogen compound with an acylhydrazine skeleton is acceptable. Examples include dodecanoic acid bis[N2-(2-hydroxybenzoyl)hydrazine], N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, decanedicarboxylic acid disalicylic acid hydrazine, N-salicyl-N'-salicyl hydrazine, m-nitrobenzoyl hydrazine, 3-aminophthalic acid hydrazine, phthalic acid dihydrazine, adipic acid hydrazine, oxaloyl di(2-hydroxy-5-octylphenylmethylene hydrazine), N'-benzoylpyrrolidone carboxylic acid hydrazine, and N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hydrazine.

[0330] As an amide-based nitrogen compound, any nitrogen compound with an amide skeleton is acceptable, such as N,N'-bis{2-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]ethyl}oxalamide.

[0331] As a triazole nitrogen compound, any nitrogen compound with a triazole skeleton is acceptable, such as N-(2H-1,2,4-triazol-5-yl)salicylic acid amide, 3-amino-1,2,4-triazole, 3-(N-salicylic acid)amino-1,2,4-triazole, etc.

[0332] As a melamine-based nitrogen compound, any nitrogen compound with a melamine skeleton is acceptable, including melamine and melamine derivatives. More specifically, examples 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.

[0333] Metal passivating agents can be used alone or in combination of two or more.

[0334] When the flux of this embodiment contains a metal passivator, the content of the metal passivator is preferably 1% or more and 10% or less, more preferably 2% or more and 6% or less, relative to the total mass (100% by mass) of the flux.

[0335] Antioxidants

[0336] As antioxidants, examples include hindered phenolic antioxidants such as 2,2'-dihydroxy-3,3'-bis(α-methylcyclohexyl)-5,5'-dimethyldiphenylmethane.

[0337] The term "antioxidant" as used here refers to compounds that have the property of inhibiting the acid value of solder alloy powder.

[0338] When the flux of this embodiment contains an antioxidant, the content of the antioxidant is preferably 1% or more and 10% or less, more preferably 2% or more and 6% or less, relative to the total mass (100% by mass) of the flux.

[0339] The flux described above reduces flux residue breakage due to temperature changes by ensuring that the mixing ratio of copolymer (A) to rosin (B) is 1 or more by mass ratio expressed as copolymer (A) / rosin (B). Furthermore, since the flux of this embodiment has a copolymer (A) / rosin (B) mass ratio of 1 or more, even with a low thixotropic agent content, it can suppress the separation of solder paste into solder powder and flux over time during storage, and can also suppress the reduction of solder strength when an underfiller is used.

[0340] In addition to the effects described above, fluxes containing compounds of the above general formula (2) can also improve the ability to suppress heat-induced slump.

[0341] (solder paste)

[0342] The solder paste of this embodiment contains solder alloy powder and the flux described above.

[0343] Solder alloy powder can be composed of solder powder with Sn monomer, or Sn-Ag system, Sn-Cu system, Sn-Ag-Cu system, Sn-Bi system, Sn-In system, etc., or solder alloy powder with added Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, P, etc.

[0344] Solder alloy powder can also be composed of Sn-Pb system or Sn-Pb system with added Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, P, etc.

[0345] The solder alloy powder is preferably a Pb-free solder.

[0346] As a solder alloy powder, for example, a solder alloy powder with a melting temperature of 150 to 250°C can be used.

[0347] Flux content:

[0348] In the solder paste, the flux content is preferably 5 to 30% by mass, more preferably 5 to 15% by mass, relative to the total mass of the solder paste.

[0349] The solder paste of this embodiment described above can reduce the cracking of flux residues caused by temperature changes. In addition, even without thixotropic agents, this solder paste can prevent the separation of solder powder and flux over time during storage, and can also prevent the reduction of solder strength when an underfiller is used.

[0350] Example

[0351] The present invention will be described below through embodiments, but the present invention is not limited to the following embodiments.

[0352] <Preparation of flux>

[0353] (Examples 1-53, Comparative Examples 1-12)

[0354] The fluxes of the formulation examples and comparative examples are shown in Tables 1-6. In the tables, the values ​​in the composition column refer to the content (mass%) of each component relative to the total mass (100% by mass) of each flux, and the blank column means "0% by mass".

[0355] Add all ingredients to a stainless steel container and heat until melted and uniformly dissolved while stirring. Then, maintain the temperature at 130°C for 10 minutes and cool for 24 hours to obtain the flux.

[0356] Copolymer (A):

[0357] Ethylene-acrylic acid copolymer #1:

[0358] The acid value is 120, and the weight-average molecular weight is approximately 8000. The content of repeating units from acrylic acid is 15% by mass relative to the total amount of the ethylene-acrylic acid copolymer (100% by mass). The ratio, expressed as the number of repeating units from ethylene to the number of repeating units from acrylic acid, is 14.1.

[0359] Ethylene-acrylic acid copolymer #2:

[0360] The acid value is 40, and the weight-average molecular weight is approximately 5000. The content of repeating units from acrylic acid is 5% by mass relative to the total amount of the ethylene-acrylic acid copolymer (100% by mass). The ratio, expressed as the number of repeating units from ethylene to the number of repeating units from acrylic acid, is 47.4.

[0361] Other resins:

[0362] Polyacrylate homopolymer (weight average molecular weight approximately 30,000), polyethylene homopolymer (weight average molecular weight approximately 3,000), 1,2-polybutadiene homopolymer (number average molecular weight 2,100).

[0363] Rosin (B):

[0364] Maleic acid modified hydrogenated rosin, hydrogenated rosin

[0365] Solvent:

[0366] α-Terpineol (dielectric constant 2.9), 2-hexyl-1-decyl alcohol (dielectric constant 2.1), diethylene glycol mono-2-ethylhexyl ether (dielectric constant 5.0), tetraethylene glycol (dielectric constant 35).

[0367] Organic acids:

[0368] Malonic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, phenylsuccinic acid, dimeramine:

[0369] Triethylenetetramine, dipropylenetrimine, monoethanolamine, diethylethylenediamine, bis(2-ethylhexyl)amine, N,N,N',N'-tetra(2-hydroxypropylethylenediamine)

[0370] Azoles:

[0371] 3-(N-Salicyloyl)amino-1,2,4-triazole,2-ethylimidazole

[0372] Thixotropic agents:

[0373] Hydrogenated castor oil

[0374] Antioxidants:

[0375] 2,2'-Dihydroxy-3,3'-bis(α-methylcyclohexyl)-5,5'-dimethylphenylmethane

[0376] <Preparation of solder paste>

[0377] Solder pastes were prepared by mixing the fluxes of Examples 1-53 and Comparative Examples 1-12 with the solder alloy powder described below. The prepared solder pastes contained 11% by mass of flux and 89% by mass of solder alloy powder.

[0378] The solder alloy powder is composed of a solder alloy with 3% by mass Ag, 0.5% by mass Cu, and the balance Sn. The solidus temperature of this solder alloy is 217℃, and the liquidus temperature is 220℃.

[0379] The evaluation methods described in the "Evaluation" section below were used to evaluate the "Temperature Cycling Reliability," "Solder Paste Separation Inhibition Capability," "Shear Strength," and "Heating Slump Inhibition Capability." The evaluation results are shown in Tables 1-6.

[0380] <Evaluation>

[0381] Evaluation of Temperature Cycle Reliability

[0382] (1) Evaluation Method

[0383] Prepare a printed circuit board (material: FR-4, thickness 1.0 mm, pad size 1.5 mm × 0.25 mm, pitch 0.5 mm, width between pads 0.25 mm, number of pads 64). Using a metal mask with a thickness of 150 μm, print the prepared solder paste onto the printed circuit board.

[0384] Next, using the printed circuit board after printing, perform reflow soldering to obtain a test substrate. The reflow curve is shown in Figure 1 . The reflow curve is as follows: preheating at 150 - 180 °C for 90 seconds, peak temperature at 240 °C, and solder melting time at 40 seconds. The reflow soldering is carried out in a nitrogen atmosphere with an oxygen concentration of 1000 ppm or less.

[0385] Next, place each of the obtained test substrates into a thermal cycling test device, with one cycle consisting of standing at low temperature (-40 °C) and high temperature (125 °C), and perform 3000 cycles. In this cycle, the standing time at both low and high temperatures is 30 minutes, and the time for one cycle is set to 70 minutes. After performing 3000 cycles, observe the cracking of the flux residue. Evaluate the temperature cycle reliability according to the following judgment criteria.

[0386] (2) Judgment Criteria

[0387] A: Cracking is not confirmed in all parts.

[0388] B: Cracking less than 0.125 mm is confirmed in the flux residue between pads.

[0389] C: Cracking of 0.125 mm or more is confirmed in the flux residue between pads.

[0390] D: Cracking across the flux residue between pads is confirmed.

[0391] Flux with an evaluation result of A or B is qualified, and flux with an evaluation result of C or D is unqualified.

[0392] Evaluation of Solder Paste Separation Inhibition Ability

[0393] (1) Evaluation Method

[0394] Place 500 g of the prepared solder paste in a container and let it stand in a constant temperature bath at 40 °C for 3 days. After the following specified time has elapsed, visually observe the solder paste and determine whether the solder paste has separated according to the following judgment criteria.

[0395] (2) Judgment Criteria

[0396] A: The solder paste did not separate after 72 hours.

[0397] B: The solder paste did not separate after 48 hours. It separated after more than 48 hours but less than 72 hours.

[0398] C: The solder paste did not separate after 12 hours. The solder paste separated after more than 12 hours but less than 48 hours.

[0399] D: The solder paste separated after less than 12 hours.

[0400] The evaluation results are as follows: fluxes A through C are qualified, while flux D is unqualified.

[0401] Evaluation of Shear Strength

[0402] (1) Evaluation Method

[0403] For the resist layer on the substrate (SMIC017-02 ver.3), 1 mL of the prepared flux was applied to the resist surface using a mask (SMIC017-02 ver.3, 0.12 mm thick), followed by reflow soldering. The reflow soldering temperature profile was set to be the same as that in the "Evaluation of Temperature Cycling Reliability". The reflow soldering was performed under a nitrogen atmosphere with an oxygen concentration set below 3000 ppm.

[0404] Next, apply approximately 0.1 mL of underfill onto the flux residue. UF3810 (made by Loctite) is used as the underfill.

[0405] Next, the chip (2012CC) is mounted on the underfill and placed in a constant temperature bath for curing. The curing conditions are 130°C for 8 minutes. In this curing process, the underfill and flux are mixed and cured.

[0406] Next, the load was set to 50 kgf, the shearing speed to 6.0 mm / min, and the height to 1.0 mm. The shear strength was then measured and judged according to the following criteria. Here, 1 kgf = 9.8 N.

[0407] (2) Judgment Criteria

[0408] A: Shear strength is above 20N.

[0409] B: Shear strength is above 10N and less than 20N.

[0410] C: Shear strength less than 10N.

[0411] The evaluation results are as follows: flux A or B is qualified, while flux C is unqualified.

[0412] Evaluation of Heating Slump Inhibition Capacity

[0413] (1) Evaluation Method

[0414] For the prepared solder paste, the heat slump was evaluated according to the method described in JIS Z3284-3:2014, "Slump Test During Heating". First, a test kit for "Slump Test During Printing" was used. Figure 2 A metal mask for the patterned hole shown in I (hole size 3.0 × 0.7) was used to print solder paste to obtain a test board. The obtained test board was then placed in a constant temperature bath at 150°C for 3 minutes. A schematic diagram of the pattern I above is shown in [the diagram]. Figure 2 .exist Figure 2 In this context, values ​​from 0.2 to 1.2 represent the distance between pattern holes. For the heated test board, the minimum gap at which the printed solder paste does not become a single piece is evaluated according to the following criteria.

[0415] (2) Judgment Criteria

[0416] A: In pattern I, the minimum spacing is less than 0.3mm.

[0417] B: In pattern I, the minimum interval is greater than 0.3mm and less than 0.4mm.

[0418] C: In the pattern of I, the minimum spacing exceeds 0.4 mm.

[0419] The evaluation results are as follows: flux A or B is qualified, while flux C is unqualified.

[0420] [Table 1]

[0421]

[0422] [Table 2]

[0423]

[0424] [Table 3]

[0425]

[0426] [Table 4]

[0427]

[0428] [Table 5]

[0429]

[0430] [Table 6]

[0431]

[0432] The flux of Comparative Example 6, which contains polyacrylate homopolymer and does not contain thixotropic agents, was rated A for temperature cycling reliability, but D for solder paste separation inhibition capability.

[0433] The flux of Comparative Example 12, which contains 6% by mass of polyacrylate homopolymer and thixotropic agent, has an improved solder paste separation inhibition rating of A, but its shear strength rating is C.

[0434] The fluxes of Comparative Examples 1 to 2, which have a mass ratio of copolymer (A) to rosin (B) of less than 1 and do not contain thixotropic agents, are rated as C or D for temperature cycling reliability and solder paste separation inhibition ability.

[0435] The flux of Example 1, which has a mass ratio of copolymer (A) / rosin (B) of 1 or more and does not contain thixotropic agents, was rated A for temperature cycling reliability and A for solder paste separation inhibition ability.

[0436] That is, by making the mass ratio of copolymer (A) / rosin (B) greater than 1, the temperature cycling reliability is improved even without thixotropic agents, and the solder paste separation inhibition capability is improved.

[0437] The fluxes of Comparative Examples 1-2, whose mass ratio of copolymer (A) / rosin (B) is less than 1, are rated as C or D for temperature cycling reliability.

[0438] In contrast, the fluxes of Examples 22, 46, and 49, which have a mass ratio of 1 or more but less than 2, were rated as B for temperature cycling reliability.

[0439] The fluxes of Examples 1-21, 23-45, 47-48, and 50-53 with a mass ratio of 2 or higher were rated as A for temperature cycling reliability.

[0440] The fluxes of Comparative Examples 3-11, which do not contain copolymer (A) and thixotropic agent, were rated as D in terms of their ability to inhibit solder paste separation.

[0441] The flux of Comparative Example 12, which does not contain copolymer (A) and contains 6% by mass of thixotropic agent, was rated as A in terms of its ability to inhibit solder paste separation.

[0442] The fluxes of Examples 22, 46, and 49, which do not contain thixotropic agents and have a mass ratio of copolymer (A) to rosin (B) of 1 or more but less than 2, are rated as having a solder paste separation inhibition ability of C.

[0443] In addition, the fluxes of Examples 6, 23, 47, 48, and 50, which have a mass ratio of 2 or more but less than 3, were rated as having a B-level ability to inhibit solder paste separation.

[0444] In addition, the fluxes of Examples 1-5, 7-21, 24-45, and 51-53 with a mass ratio of 3 or more were rated as A for their ability to inhibit solder paste separation.

[0445] In other words, it was confirmed that regardless of whether the thixotropic agent content was low or absent, maintaining a mass ratio of copolymer (A) / rosin (B) of 1 or higher improved the separation inhibition ability of the solder paste. Furthermore, it was confirmed that the higher this mass ratio, the better the separation inhibition ability of the solder paste.

[0446] The flux of Comparative Example 12, with a thixotropic agent content of 6% by mass, was rated as C in shear strength.

[0447] The flux of Example 3, with a thixotropic agent content of 2% by mass, was rated as B in shear strength.

[0448] The shear strength of the fluxes in Examples 1-2 and 4-53, which do not contain thixotropic agents, was rated as A.

[0449] Specifically, it was confirmed that by maintaining a mass ratio of copolymer (A) to rosin (B) of 1 or more, both the solder paste separation inhibition ability and shear strength can be balanced. Furthermore, it was confirmed that the solder paste separation inhibition ability can be improved even without a thixotropic agent.

[0450] The flux of Example 15, which does not contain solvents with a dielectric constant of 4 or less, was rated as C for its heat-induced slump suppression capability.

[0451] The fluxes of Examples 16, 27, and 28, which do not contain the compound represented by the general formula (2), were rated as C for their heat-induced slump suppression ability.

[0452] The flux of Example 37, which contains the compound represented by the general formula (2) and phenylsuccinic acid, was rated as B for its heat slump suppression ability.

[0453] That is, by further containing the specific amine represented by the general formula (2), the ability to suppress thermal collapse can be improved.

[0454] The fluxes containing the compound represented by the general formula (2) and one or more of malonic acid, succinic acid, glutaric acid, adipic acid and azelaic acid from Examples 1-14, 17-26, 29-36, 38-53 and Comparative Examples 1-12 were evaluated as having an A-level heat-induced slump suppression ability.

[0455] That is, the flux according to the present invention, by making the mass ratio of copolymer (A) / rosin (B) 1 or more, can reduce the cracking of flux residues due to temperature changes and can suppress the separation of solder paste into solder powder and flux over time during storage. Furthermore, when using an underfiller, it can suppress the reduction of solder strength. The flux according to the present invention can achieve the above-mentioned effects even when the thixotropic agent content is low.

[0456] Industrial applicability

[0457] The flux and solder paste of the present invention are suitable for soldering semiconductors that operate at high temperatures.

Claims

1. A flux comprising a resin component, an activator, and a solvent, said resin component comprising a copolymer (A) and rosin (B), said copolymer (A) having repeating units (a1) derived from an olefin and repeating units (a2) derived from acrylic acid from which hydrogen atoms bonded to the carbon atom at the α-position can be substituted by substituents. in, The mixing ratio of the copolymer (A) to the rosin (B), expressed as a mass ratio of copolymer (A) / rosin (B), is 3 or more and 10 or less. In the copolymer (A), the content of the repeating unit (a2) is 3% by mass or more relative to the total content of the copolymer (A). The copolymer (A) has the structure shown in the following general formula (1). In the formula, R 1 R represents a hydrogen atom or a methyl group. 2 This represents a hydrogen atom or a methyl group, where m and n represent integers greater than or equal to 1. The ratio m / n of the number of repetitions m of the repeating unit (a1) to the number of repetitions n of the repeating unit (a2) is 3 or more and 50 or less. The copolymer (A) has an acid value of 40 or higher and 120 or lower.

2. The flux according to claim 1, wherein, The dielectric constant of the solvent is 4 or less.

3. The flux according to claim 2, wherein, The solvent is selected from one or more of α-terpineol and 2-hexyl-1-decyl alcohol.

4. The flux according to claim 1, wherein, The content of the copolymer (A) is 5% by mass or more and 50% by mass or less relative to the total mass of the flux.

5. The flux according to claim 1, wherein, The content of rosin (B) relative to the total mass of flux is more than 1% by mass and less than 20% by mass.

6. The flux according to claim 1, wherein, The flux also contains a compound represented by the following general formula (2). [Chemical Formula 1] R 21 -NH2…(2) In the formula, R 21 It represents an organic group.

7. The flux according to claim 6, wherein, The compound represented by general formula (2) is selected from one or more of monoethanolamine, triethylenetetramine and dipropylenetriamine.

8. The flux according to claim 6, wherein, The flux also contains a compound represented by the following general formula (3). [Chemical Formula 2] In the formula, R 31 It represents an organic group or a single bond.

9. The flux according to claim 8, wherein, The compound represented by general formula (3) is selected from one or more of malonic acid, succinic acid, glutaric acid, adipic acid and azelaic acid.

10. The flux according to claim 1, wherein, The flux also contains a thixotropic agent. The thixotropic agent content is greater than 0% by mass and less than 2% by mass relative to the total mass of the flux.

11. The flux according to claim 1, wherein, The flux does not contain thixotropic agents.

12. A solder paste comprising solder alloy powder and flux as described in any one of claims 1 to 11.

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