Flux and solder paste

Abstract

Provided is a flux capable of enhancing the effect of suppressing the occurrence of HiP (pillow defect), and a solder paste containing the same. The present invention relates to a flux containing a resin, a solvent, a thixotropic agent, and an activator, the thixotropic agent containing a compound represented by general formula (T-0): In general formula (T-0), p is an integer of 2 to 8. [C1] TIFF0007640923000026.tif25170

Description

[Technical field]

[0001] The present invention relates to a flux and a solder paste. [Background technology]

[0002] In manufacturing electronic components, components are fixed to a substrate and electrically connected to the substrate by soldering, which uses flux, solder powder, and a solder paste made by mixing the flux and the solder powder. Flux has the effect of chemically removing metal oxides that exist in the solder and in the metal surface of the objects to be soldered, enabling the movement of metal elements at the interface between the two. Therefore, by using flux for soldering, an intermetallic compound is formed between the two, resulting in a strong bond.

[0003] In soldering using solder paste, the solder paste is first printed on a board, components are then mounted on it, and the board with the components mounted on it is heated in a heating furnace called a reflow furnace, which melts the solder powder contained in the solder paste and bonds the components to the board, thereby obtaining a bonded body.

[0004] During the soldering, the condition of the joint between the component and the board is important. For example, depending on the oxidation state of the component and the activity of the flux, metal oxides on the surface of the component may not be removed, causing a phenomenon in which the component and the solder paste do not fuse together during reflow (a head in pillow (HiP)). If the joint is in this kind of head in pillow (HiP) state, the component to be mounted will have a poor connection with the board. To address such poor bonding, fluxes have been proposed that use a specific organic acid and a specific halogen compound in combination as activators, or that have their blended amounts adjusted (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-102231 [Patent Document 2] JP 2020-82106 A Summary of the Invention [Problem to be solved by the invention]

[0006] Recently, with the trend towards more compact electronic devices and smaller circuit boards, there is a demand for space-saving, high-performance components. In response, the use of surface mount components such as BGA (Ball Grid Array) and CSP (Chip Size Package) is increasing, mainly for the purpose of high-density mounting. In high-density mounting, due to the narrow process window, pillow defects (HiP) are likely to occur, and they are also likely to occur in BGA components. However, it is difficult to prevent the occurrence of HiP in BGA components using conventional flux.

[0007] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a flux that can enhance the effect of suppressing the occurrence of HiP defects, and a solder paste containing the flux. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention employs the following configuration.

[0009] [1] Contains resin, solvent, thixotropic agent and activator, The flux, wherein the thixotropic agent contains a compound represented by the following general formula (T-0):

[0010] [ka] [In the formula, p is an integer of 2 to 8.]

[0011] [2] The flux according to [1], wherein p in the general formula (T-0) is 2 or 6.

[0012] [3] The flux according to [1] or [2], wherein the content of the compound represented by the general formula (T-0) is 0.1 mass % or more and 1 mass % or less with respect to the total mass (100 mass %) of the flux.

[0013] [4] The flux according to any one of [1] to [3], wherein the thixotropic agent further contains a compound represented by the following general formula (T-1):

[0014] [ka] [In the formula, q is an integer of 2 to 8.]

[0015] [5] The flux according to [4], wherein q in the general formula (T-1) is 2 or 6.

[0016] [6] The mixing ratio of the compound represented by the general formula (T-0) to the compound represented by the general formula (T-1) is Compound represented by general formula (T-1) / compound represented by general formula (T-0), The flux according to [4] or [5], wherein the mass ratio represented by is 4 or more and 40 or less.

[0017] [7] The flux according to any one of [4] to [6], wherein the thixotropic agent further contains a compound represented by the following general formula (T-2):

[0018] [ka] [In the formula, r is an integer of 2 to 8. R is an aliphatic hydrocarbon group having 11 to 19 carbon atoms.]

[0019] [8] The flux according to [7], wherein r in the general formula (T-2) is 2 or 6.

[0020] [9] The flux according to [7] or [8], wherein R in the general formula (T-2) is a linear alkyl group having 17 carbon atoms.

[0021]

[10] The flux according to any one of [7] to [9], wherein a total content of the compound represented by the general formula (T-0), the compound represented by the general formula (T-1), and the compound represented by the general formula (T-2) is 1 mass % or more and 10 mass % or less with respect to a total mass (100 mass %) of the flux.

[0022]

[11] A solder paste comprising the flux according to any one of [1] to

[10] and a solder powder. Effect of the Invention

[0023] According to the present invention, it is possible to provide a flux that can enhance the effect of suppressing the occurrence of pillow defects (HiP), and a solder paste containing the flux. [Brief description of the drawings]

[0024] [Figure 1] FIG. 13 is a diagram showing a reflow profile in the evaluation of the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] (Flux) One embodiment of the flux according to the first aspect contains a resin, a solvent, a thixotropic agent, and an activator. The thixotropic agent is characterized in that it contains a compound represented by the following general formula (T-0).

[0026] [ka] [In the formula, p is an integer of 2 to 8.]

[0027] <Resin> The resin contained in the flux of this embodiment may be rosin, a copolymer, etc. An example of the copolymer is an olefin / (α-substituted) acrylic acid resin.

[0028] <Rosin> In the present invention, "rosin" includes natural resins containing abietic acid as the main component or a mixture of abietic acid and its isomers, as well as chemically modified natural resins (sometimes referred to as rosin derivatives).

[0029] The content of abietic acid in the natural resin is, for example, 40% by mass or more and 80% by mass or less with respect to the natural resin. In this specification, the term "main component" refers to a component that is contained in a compound at a content of 40 mass % or more among components constituting the compound.

[0030] Representative isomers of abietic acid include neoabietic acid, palustric acid, and levopimaric acid. Examples of the "natural resin" include gum rosin, wood rosin, tall oil rosin, and the like.

[0031] In the present invention, the term "chemically modified natural resin (rosin derivative)" includes the "natural resin" that has been subjected to one or more treatments selected from the group consisting of hydrogenation, dehydrogenation, neutralization, alkylene oxide addition, amidation, dimerization, oligomerization, esterification, and Diels-Alder cycloaddition.

[0032] Examples of rosin derivatives include purified rosin and modified rosin. Examples of modified rosins include hydrogenated rosin, polymerized rosin, polymerized hydrogenated rosin, disproportionated rosin, acid-modified rosin, rosin ester, acid-modified hydrogenated rosin, acid anhydride-modified hydrogenated rosin, acid-modified disproportionated rosin, acid anhydride-modified disproportionated rosin, phenol-modified rosin and α,β-unsaturated carboxylic acid modified products (acrylated rosin, maleated rosin, fumarated rosin, etc.), as well as purified products, hydrogenated products and disproportionated products of the polymerized rosins, as well as purified products, hydrogenated products and disproportionated products of the α,β-unsaturated carboxylic acid modified products, rosin alcohol, rosin amine, hydrogenated rosin alcohol, rosin ester, hydrogenated rosin ester, rosin soap, hydrogenated rosin soap, acid-modified rosin soap, etc. Examples of rosin amines include dehydroabietylamine, dihydroabietylamine, etc. The rosin amine refers to a so-called disproportionated rosin amine.

[0033] <Olefin / (α-substituted) acrylic acid resin> The olefin / (α-substituted) acrylic acid resin has a repeating unit (a1) derived from an alkene and a repeating unit (a2) derived from an acrylic acid in which the hydrogen atom bonded to the carbon atom at the α-position may be substituted with a substituent (hereinafter referred to as "(α-substituted) acrylic acid"). The olefin / (α-substituted) acrylic acid resin may have a repeating unit (a3) ​​other than the repeating units (a1) and (a2). The term "(α-substituted) acrylic acid" refers to either or both of acrylic acid and acrylic acid in which the hydrogen atom bonded to the carbon atom at the α-position is replaced with a substituent.

[0034] [Repeating unit (a1)] The repeating unit (a1) is derived from an alkene. The alkene may, for example, be n H 2n 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. C n H 2nExamples of the compound represented by the formula (I) include ethylene, propylene, isobutene, 1-butene, 1-pentene, 1-hexene, and the like. Of these, one or more selected from the group consisting of ethylene and propylene is preferred, and ethylene is more preferred.

[0035] Alternatively, examples of the alkene from which the repeating unit (a1) is derived include 1,3-butadiene, 2-methyl-1,3-butadiene, and the like.

[0036] The repeating unit (a1) contained in the olefin / (α-substituted) acrylic acid resin may be of one type or of two or more types.

[0037] [Repeating unit (a2)] The repeating unit (a2) is derived from (α-substituted) acrylic acid. In the repeating unit (a2), the hydrogen atom bonded to the carbon atom at the α-position may be substituted with a substituent. When the carbon atom at the α-position has a substituent, the substituent may be a linear or branched alkyl group. The number of carbon atoms in the alkyl group is preferably 1 to 5. Examples of the repeating unit (a2) include a repeating unit derived from acrylic acid and a repeating unit derived from methacrylic acid.

[0038] The repeating unit (a2) contained in the olefin / (α-substituted) acrylic acid resin may be of one type or of two or more types.

[0039] [Repeating unit (a3)] The repeating unit (a3) ​​is a repeating unit other than the repeating unit (a1) and the repeating unit (a2).

[0040] Examples of the repeating unit (a3) ​​include a repeating unit derived from an acrylate ester in which the hydrogen atom bonded to the carbon atom at the α-position may be substituted with a substituent (hereinafter referred to as an “(α-substituted) acrylate ester”), a repeating unit derived from an alkylene oxide, and a repeating unit having an aromatic group.

[0041] The (α-substituted) acrylate ester refers to either or both of an acrylate ester and an acrylate ester in which the hydrogen atom bonded to the carbon atom at the α-position is substituted with a substituent. Examples of the substituent include an alkyl group having 1 to 5 carbon atoms.

[0042] The (α-substituted) acrylic ester is a reaction product of (α-substituted) acrylic acid and an alcohol, such as an alcohol having a linear carbon chain and 1 to 24 carbon atoms.

[0043] Examples of the (α-substituted) acrylic acid esters include acrylic acid esters such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, t-butyl acrylate, cyclohexyl acrylate, octyl acrylate, nonyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, benzyl acrylate, anthracene acrylate, glycidyl acrylate, 3,4-epoxycyclohexylmethane acrylate, and propyltrimethoxysilane acrylate; and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, octyl methacrylate, nonyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, benzyl methacrylate, anthracene methacrylate, glycidyl methacrylate, 3,4-epoxycyclohexylmethane methacrylate, and propyltrimethoxysilane methacrylate. Of these, methyl acrylate, ethyl acrylate, t-butyl acrylate, methyl methacrylate, ethyl methacrylate, and t-butyl methacrylate are preferred.

[0044] Examples of the alkylene oxide include ethylene oxide, propylene oxide, isopropylene oxide, butylene oxide, and the like.

[0045] Examples of the repeating unit having an aromatic group include a repeating unit having an aromatic group such as a phenyl group, a naphthyl group, etc. Examples of the repeating unit having a phenyl group include a repeating unit derived from styrene or a derivative thereof.

[0046] When the olefin / (α-substituted) acrylic acid resin has the repeating unit (a3), the repeating unit (a3) ​​contained in the olefin / (α-substituted) acrylic acid resin may be of one type or two or more types.

[0047] In the olefin / (α-substituted) acrylic acid resin, the content of the repeating unit (a1) 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, based on the entire olefin / (α-substituted) acrylic acid resin (100% by mass). When the content of the repeating unit (a1) is equal to or greater than the lower limit of the preferred range, the electrical reliability of the bonded body is easily improved. When the content of the repeating unit (a1) is equal to or less than the upper limit of the preferred range, the separation of the solder paste into the solder powder and the flux over time is easily suppressed. Also, cracking of the flux residue due to temperature change is easily reduced. Also, the solderability is easily improved. Also, the solubility of the olefin / (α-substituted) acrylic acid resin in the flux is easily improved.

[0048] In the olefin / (α-substituted) acrylic acid resin, the content of the repeating unit (a2) is preferably from 2 to 90% by mass, more preferably from 3 to 60% by mass, and even more preferably from 5 to 35% by mass, based on the entire olefin / (α-substituted) acrylic acid resin (100% by mass). When the content of the repeating unit (a2) is equal to or greater than the lower limit of the above-mentioned preferred range, separation of the solder paste into solder powder and flux over time is easily suppressed. Also, cracking of the flux residue due to temperature change is easily reduced. Also, solderability is easily improved. Also, the solubility of the olefin / (α-substituted) acrylic acid resin in the flux is easily improved. When the content of the repeating unit (a2) is equal to or less than the upper limit of the above preferred range, the electrical reliability of the bonded structure is easily improved.

[0049] When the olefin / (α-substituted) acrylic acid resin has the repeating unit (a3), the content of the repeating unit (a3) ​​in the olefin / (α-substituted) acrylic acid resin is preferably from 0.1 to 30% by mass, more preferably from 0.1 to 20% by mass, and even more preferably from 0.1 to 10% by mass, based on the entire olefin / (α-substituted) acrylic acid resin (100% by mass).

[0050] The olefin / (α-substituted) acrylic resin may be a random copolymer or a block copolymer.

[0051] <Resins other than rosin and olefin / (α-substituted) acrylic acid resins> Examples of resins other than rosin and olefin / (α-substituted) acrylic acid resins include terpene resins, modified terpene resins, terpene phenol resins, modified terpene phenol resins, styrene resins, modified styrene resins, xylene resins, modified xylene resins, acrylic resins, and polyethylene resins. Examples of modified terpene resins include aromatic modified terpene resins, hydrogenated terpene resins, and hydrogenated aromatic modified terpene resins. Examples of modified terpene phenol resins include hydrogenated terpene phenol resins. Examples of modified styrene resins include styrene acrylic resins and styrene maleic acid resins. Examples of modified xylene resins include phenol modified xylene resins, alkylphenol modified xylene resins, phenol modified resol type xylene resins, polyol modified xylene resins, and polyoxyethylene added xylene resins.

[0052] In the flux of the present embodiment, the resin may be used alone or in combination of two or more kinds. Among the above, the resin is preferably at least one selected from the group consisting of rosin and copolymers, more preferably at least one selected from the group consisting of modified rosin and olefin / (α-substituted) acrylic acid resin, still more preferably at least one selected from the group consisting of hydrogenated rosin, polymerized rosin, acid-modified hydrogenated rosin, and ethylene / acrylic acid copolymer, and it is particularly preferable to combine at least one selected from the group consisting of hydrogenated rosin, polymerized rosin, and ethylene / acrylic acid copolymer with acid-modified hydrogenated rosin. As the acid-modified hydrogenated rosin, acrylic acid-modified hydrogenated rosin is preferred.

[0053] The resin content in the flux of the present embodiment is preferably 20 mass % or more and 60 mass % or less, more preferably 25 mass % or more and 55 mass % or less, and even more preferably 30 mass % or more and 50 mass % or less, relative to the total mass (100 mass %) of the flux.

[0054] <Solvent> Examples of the solvent contained in the flux of this embodiment include water, alcohol-based solvents, glycol ether-based solvents, and terpineols.

[0055] Examples of alcohol-based solvents include isopropyl alcohol, 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-hexyne-2,5-diol, 2,3-dimethyl-2,3-butanediol, 2-methylpentane-2,4-diol, 1,1,1-tris(hydroxymethyl)propane, 2-ethylhexyl ... ethyl-2-hydroxymethyl-1,3-propanediol, 2,2'-oxybis(methylene)bis(2-ethyl-1,3-propanediol), 2,2-bis(hydroxymethyl)-1,3-propanediol, 1,2,6-trihydroxyhexane, 1-ethynyl-1-cyclohexanol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 2-hexyl-1-decanol, octanediol, and the like.

[0056] Examples of glycol ether solvents include diethylene glycol mono-2-ethylhexyl ether (EHDG), ethylene glycol monophenyl ether, diethylene glycol monohexyl ether (hexyl diglycol: HeDG), diethylene glycol dibutyl ether, triethylene glycol monomethyl ether, triethylene glycol monobutyl ether, triethylene glycol butyl methyl ether, tetraethylene glycol, tetraethylene glycol dimethyl ether; monoalkyl propylene glycols, and the like.

[0057] Examples of terpineols include α-terpineol, β-terpineol, γ-terpineol, and terpineol mixtures (that is, mixtures whose main component is α-terpineol and contain β-terpineol or γ-terpineol). Other examples of the solvent include dioctyl sebacate and liquid paraffin.

[0058] In the flux of the present embodiment, the solvent may be used alone or in combination of two or more kinds. Among the above, the solvent is preferably a glycol ether-based solvent, and it is particularly preferable to use at least one selected from the group consisting of HeDG, EHDG, and tetraethylene glycol dimethyl ether, from the viewpoints of viscosity stability when made into a solder paste and melting property of the solder powder.

[0059] The content of the solvent in the flux of the present embodiment is the balance in the flux, and is determined depending on the contents of the other components. For example, the content of the solvent in the flux of the present embodiment may be 20 mass % or more and 70 mass % or less, 25 mass % or more and 65 mass % or less, or 30 mass % or more and 60 mass % or less, relative to the total mass (100 mass %) of the flux.

[0060] <Thixotropic agent> The thixotropic agent contained in the flux of this embodiment includes a compound represented by general formula (T-0) described below (hereinafter also referred to as "compound (T0)"). The thixotropic agent contained in the flux of the present embodiment preferably contains, in addition to the compound (T0), a compound represented by general formula (T-1) described below (hereinafter also referred to as "compound (T1)"). The thixotropic agent contained in the flux of the present embodiment preferably contains, in addition to the compound (T0), a compound represented by general formula (T-2) described below (hereinafter also referred to as "compound (T2)"), and more preferably contains, in addition to the compound (T0) and the compound (T1), the compound (T2). The thixotropic agent contained in the flux of the present embodiment may further include, in addition to the compound (T0), another thixotropic agent other than the compound (T0), the compound (T1), and the compound (T2).

[0061] The total content of the thixotropic agent in the flux of this embodiment is preferably 1 mass % or more and 20 mass % or less, more preferably 2 mass % or more and 15 mass % or less, and even more preferably 3 mass % or more and 14 mass % or less, relative to the total mass (100 mass %) of the flux.

[0062] <Compound represented by general formula (T-0)> The compound represented by general formula (T-0) (compound (T0)) has, in the molecule, an ester bond (-CO-O-) between a hydroxy group (-OH) derived from 12-hydroxystearic acid and a carboxy group (-COOH) derived from 12-hydroxystearic acid.

[0063] [ka] [In the formula, p is an integer of 2 to 8.]

[0064] In the formula (T-0), p is an integer of 2 to 8, preferably at least one selected from the group consisting of 2, 6 and 8, and more preferably at least one selected from the group consisting of 2 and 6.

[0065] Specific examples of the compound represented by general formula (T-0) are shown below.

[0066] [ka]

[0067] In the flux of the present embodiment, the compound (T0) may be used alone or in combination of two or more kinds. Suitable examples of the compound (T-0) include a compound represented by p=6 in the general formula (T-0), a compound represented by p=2 in the general formula (T-0), a combination of a compound represented by p=6 in the general formula (T-0) and a compound represented by p=2 in the general formula (T-0), and a combination of a compound represented by p=6 in the general formula (T-0) and a compound represented by p=8 in the general formula (T-0). The content of the compound (T0) in the flux of the present embodiment is preferably 0.1 mass % or more and 1 mass % or less, more preferably 0.2 mass % or more and 1 mass % or less, and further preferably 0.3 mass % or more and 1 mass % or less, relative to the total mass (100 mass %) of the flux. When the content of the compound (T0) is within the above-mentioned preferred range, the effect of suppressing the occurrence of HiP is easily obtained. When the content is equal to or more than the lower limit of the above-mentioned preferred range, the effect of suppressing the occurrence of HiP is easily improved.

[0068] <Compound represented by general formula (T-1)> The compound represented by the general formula (T-1) (compound (T1)) has an alkylenediimino group (-NH-(CH 2 It has two 12-hydroxyoctadecanoyl groups connected via q-NH-).

[0069] [ka] [In the formula, q is an integer of 2 to 8.]

[0070] In the formula (T-1), q is an integer of 2 to 8, and at least one selected from the group consisting of 2 and 6 is preferable.

[0071] Specific examples of the compound represented by general formula (T-1) are shown below.

[0072] [ka]

[0073] In the flux of the present embodiment, the compound (T1) may be used alone or in combination of two or more kinds. Suitable examples of the compound (T1) include a compound represented by general formula (T-1) where p=6, a compound represented by general formula (T-1) where p=2, and a combination of a compound represented by general formula (T-1) where p=6 and a compound represented by general formula (T-1) where p=2. The content of compound (T1) in the flux of the present embodiment is preferably 0.5 mass% or more and 7 mass% or less, more preferably 1 mass% or more and 7 mass% or less, and even more preferably 2 mass% or more and 7 mass% or less, relative to the total mass (100 mass%) of the flux. When the content of the compound (T1) is within the above-mentioned preferred range, the effect of suppressing the occurrence of HiP is easily obtained. When the content is equal to or more than the lower limit of the above-mentioned preferred range, the effect of suppressing the occurrence of HiP is easily improved.

[0074] In the flux of the present embodiment, the mixing ratio of the compound (T0) to the compound (T1) is preferably 4 or more and 40 or less in terms of a mass ratio expressed as compound (T1) / compound (T0). When this mass ratio is within the above-mentioned preferred range, the effect of suppressing the occurrence of HiP can be more easily improved.

[0075] <Compound represented by general formula (T-2)> The compound represented by the general formula (T-2) (compound (T2)) has an alkylenediimino group (-NH-(CH 2 It has one 12-hydroxyoctadecanoyl group and an acyl group (RC(=O)-) via the aryl group (r-NH-).

[0076] [ka] [In the formula, r is an integer of 2 to 8. R is an aliphatic hydrocarbon group having 11 to 19 carbon atoms.]

[0077] In the formula (T-2), r is an integer of 2 to 8, and at least one selected from the group consisting of 2 and 6 is preferable. In the formula (T-2), R is an aliphatic hydrocarbon group having 11 to 19 carbon atoms, and preferably an aliphatic hydrocarbon group having 11 to 17 carbon atoms. The aliphatic hydrocarbon group in R may be a saturated aliphatic hydrocarbon group, or an unsaturated aliphatic hydrocarbon group, and may be linear or branched. Among these, the aliphatic hydrocarbon group in R is preferably a linear saturated aliphatic hydrocarbon group, and more preferably a linear alkyl group having 17 carbon atoms.

[0078] Specific examples of the compound represented by general formula (T-2) are shown below.

[0079] [ka]

[0080] In the flux of the present embodiment, the compound (T2) may be used alone or in combination of two or more kinds. Suitable examples of the compound (T2) include a compound represented by general formula (T-2) in which p=6 and a compound represented by general formula (T-2) in which p=2. Alternatively, the compound (T2) may be a compound represented by the general formula (T-2) in which R=C 17 H 35 -, a compound represented by the general formula (T-2) where R=C 11 H 23 Preferred examples of the compound are compounds represented by the formula: Alternatively, the compound (T2) may be a compound represented by the general formula (T-2), in which p=6 and R=C 17 H 35 -, a compound represented by the general formula (T-2), where p=2 and R=C 17 H 35 -, a compound represented by the general formula (T-2), p=6, R=C 11 H 23 -, a compound represented by the general formula (T-2), where p=2 and R=C 11 H 23 Preferred examples of the compound are compounds represented by the formula:

[0081] The content of the compound (T2) in the flux of the present embodiment is preferably 0.1 mass % or more and 2 mass % or less, more preferably 0.2 mass % or more and 2 mass % or less, and further preferably 0.5 mass % or more and 2 mass % or less, relative to the total mass (100 mass %) of the flux. When the content of the compound (T2) is within the above-mentioned preferred range, the effect of suppressing the occurrence of HiP is easily obtained. When the content is equal to or more than the lower limit of the above-mentioned preferred range, the effect of suppressing the occurrence of HiP is easily improved.

[0082] In the flux of the present embodiment, the mixing ratio of the compound (T0) to the compound (T2), expressed as a mass ratio of compound (T2) / compound (T0), is preferably 1 or more and 3 or less, more preferably 1.2 or more and 2.6 or less, and even more preferably 1.3 or more and 2.5 or less. When this mass ratio is within the above-mentioned preferred range, the effect of suppressing the occurrence of HiP can be more easily improved.

[0083] In the flux of this embodiment, the thixotropic agent preferably contains the compound (T1) in addition to the compound (T0), which further enhances the effect of suppressing the occurrence of HiP. When the thixotropic agent contains the compound (T0) and the compound (T1), the total content of these two components may be 0.5 mass% or more, preferably 1 mass% or more, more preferably 2 mass% or more, even more preferably 3 mass% or more, and particularly preferably 4 mass% or more, relative to the total mass (100 mass%) of the flux. For example, the total content of these two components is preferably 1 mass% or more and 7 mass% or less, more preferably 2 mass% or more and 6 mass% or less, even more preferably 3 mass% or more and 5.5 mass% or less, and particularly preferably 4 mass% or more and 5 mass% or less, relative to the total mass (100 mass%) of the flux. When the total content of the compound (T0) and the compound (T1) is within the above-mentioned preferred range, the effect of suppressing the occurrence of HiP is easily obtained. When the total content of the compound (T0) and the compound (T1) is equal to or more than the lower limit of the above-mentioned preferred range, the effect of suppressing the occurrence of HiP is easily improved.

[0084] When the thixotropic agent contains the compound (T0) and the compound (T1), the ratio of the content of the compound (T0) to the total content (100 mass%) of these two components is preferably 2 mass% or more and 25 mass% or less, more preferably 4 mass% or more and 20 mass% or less, and may be 10 mass% or more and 19 mass% or less. When the ratio (mass ratio) of the content of the compound (T0) to the total content of the compound (T0) and the compound (T1) is within the above-mentioned preferred range, the effect of suppressing the occurrence of HiP is easily obtained. When the ratio is equal to or greater than the lower limit of the above-mentioned preferred range, the effect of suppressing the occurrence of HiP is easily improved.

[0085] When the thixotropic agent contains the compound (T0) and the compound (T1), the total content of these two components is preferably 4 mass% or more with respect to the total mass (100 mass%) of the flux, and the mixing ratio of the compound (T0) and the compound (T1), expressed as a mass ratio of compound (T1) / compound (T0), is preferably 4 or more and 40 or less, more preferably 4 or more and 30 or less, even more preferably 4 or more and 25 or less, particularly preferably 4 or more and less than 10, and most preferably 4 or more and 9 or less.

[0086] In the flux of this embodiment, the thixotropic agent preferably contains the compound (T1) and the compound (T2) in addition to the compound (T0), which further enhances the effect of suppressing the occurrence of HiP. When the flux contains the compound (T0), the compound (T1), and the compound (T2), the total content of these three components is preferably 1 mass % or more and 10 mass % or less, more preferably 1.5 mass % or more and 10 mass % or less, and even more preferably 2.5 mass % or more and 10 mass % or less, relative to the total mass (100 mass %) of the flux. When the total content of the compound (T0), the compound (T1) and the compound (T2) is within the above-mentioned preferred range, the effect of suppressing the occurrence of HiP is easily obtained. When the total content of the compound (T0), the compound (T1) and the compound (T2) is equal to or more than the lower limit of the above-mentioned preferred range, the effect of suppressing the occurrence of HiP is easily improved.

[0087] When the thixotropic agent contains the compound (T0), the compound (T1), and the compound (T2), the ratio of the content of the compound (T0) to the total content (100 mass%) of these three components is preferably 3 mass% or more and 20 mass% or less, more preferably 4 mass% or more and 17.5 mass% or less, and even more preferably 5 mass% or more and 15 mass% or less. When the ratio of the content of the compound (T0) to the total content of the compound (T0), the compound (T1) and the compound (T2) is within the preferred range, the effect of suppressing the occurrence of HiP is easily obtained. When the ratio is equal to or greater than the lower limit of the preferred range, the effect of suppressing the occurrence of HiP is easily improved.

[0088] In the flux of the present embodiment, when the compound (T0), the compound (T1), and the compound (T2) are contained, preferred mixing ratios of these three components are, for example, relative to the total content (100 mass%) of the three components, such that the content of the compound (T1) is 50 mass% or more and 87.5 mass% or less, the content of the compound (T2) is 7.5 mass% or more and 32.5 mass% or less, and the content of the compound (T0) is 5 mass% or more and 17.5 mass% or less.

[0089] <Other thixotropic agents> The thixotropic agent contained in the flux of the present embodiment may include a thixotropic agent other than the above-mentioned compound (T0), compound (T1), and compound (T2). Other examples of thixotropic agents include amide-based thixotropic agents, ester-based thixotropic agents, and sorbitol-based thixotropic agents.

[0090] Examples of the amide-based thixotropic agent include monoamides, bisamides (excluding the above-mentioned compounds (T0), (T1) and (T2)), and polyamides. Examples of monoamides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, saturated fatty acid amide, oleic acid amide, erucic acid amide, unsaturated fatty acid amide, 4-methylbenzamide, aromatic amide, hexamethylene hydroxystearic acid amide, substituted amides, methylol stearic acid amide, methylol amide, and fatty acid ester amide. Examples of bisamides include ethylene bis fatty acid (fatty acid carbon number C6-24) amides, hexamethylene bis fatty acid (fatty acid carbon number C6-24) amides, aromatic bisamides, etc. Examples of fatty acids that are raw materials for the bisamides include stearic acid (carbon number C18), oleic acid (carbon number C18), lauric acid (carbon number C12), etc. Examples of polyamides include saturated fatty acid polyamides, unsaturated fatty acid polyamides, aromatic polyamides, 1,2,3-propanetricarboxylic acid tris(2-methylcyclohexylamide), cyclic amide oligomers, and non-cyclic amide oligomers.

[0091] Examples of the cyclic amide oligomer include an amide oligomer obtained by cyclic polycondensation of a dicarboxylic acid and a diamine, an amide oligomer obtained by cyclic polycondensation of a tricarboxylic acid and a diamine, an amide oligomer obtained by cyclic polycondensation of a dicarboxylic acid and a triamine, an amide oligomer obtained by cyclic polycondensation of a tricarboxylic acid and a triamine, an amide oligomer obtained by cyclic polycondensation of a dicarboxylic acid, a tricarboxylic acid, and a diamine, an amide oligomer obtained by cyclic polycondensation of a dicarboxylic acid, a diamine, and a triamine, an amide oligomer obtained by cyclic polycondensation of a tricarboxylic acid, a diamine, and a tri ... tricarboxylic acid, a diamine, and a triamine, and an amide oligomer obtained by cyclic polycondensation of a dicarboxylic acid, a tricarboxylic acid, a diamine, and a triamine.

[0092] The non-cyclic amide oligomer may be an amide oligomer in which a monocarboxylic acid and a diamine and / or a triamine are non-cyclically polycondensed, or an amide oligomer in which a dicarboxylic acid and / or a tricarboxylic acid and a monoamine are non-cyclically polycondensed. In the case of an amide oligomer containing a monocarboxylic acid or a monoamine, the monocarboxylic acid or the monoamine functions as a terminal molecule, resulting in a non-cyclic amide oligomer with a reduced molecular weight. In the case of an amide compound in which a dicarboxylic acid and / or a tricarboxylic acid and a diamine and / or a triamine are non-cyclically polycondensed, the non-cyclic amide oligomer becomes a non-cyclic polymeric amide polymer. In addition, the non-cyclic amide oligomer may also be an amide oligomer in which a monocarboxylic acid and a monoamine are non-cyclically condensed.

[0093] Examples of the ester-based thixotropic agent include ester compounds, and specific examples thereof include hydrogenated castor oil and ethyl myristate.

[0094] Examples of sorbitol-based thixotropic agents include dibenzylidene-D-sorbitol, bis(4-methylbenzylidene)-D-sorbitol, (D-)sorbitol, monobenzylidene (-D-) sorbitol, and mono(4-methylbenzylidene)-(D-) sorbitol.

[0095] In the flux of the present embodiment, the other thixotropic agents may be used alone or in combination of two or more kinds. Among the above, the thixotropic agent preferably contains at least one selected from the group consisting of an amide-based thixotropic agent and an ester-based thixotropic agent, and examples thereof include at least one selected from the group consisting of polyamide and hydrogenated castor oil.

[0096] The content of the other thixotropic agent in the flux of the present embodiment is preferably 0.5 mass % or more and 10 mass % or less, more preferably 1 mass % or more and 7.5 mass % or less, and even more preferably 2 mass % or more and 5 mass % or less, relative to the total mass (100 mass %) of the flux.

[0097] <Activator> Examples of the activator contained in the flux of the present embodiment include organic acids, amine compounds, and halogen compounds. In the flux of the present embodiment, two or more activators may be used in combination. The activator is preferably an activator selected from the group consisting of organic acids, amine compounds, and halogen compounds, and more preferably an activator containing at least an organic acid. The total content of the activator in the flux of the present embodiment is preferably 25 mass % or less, more preferably 2.5 mass % or more and 20 mass % or less, and even more preferably 5 mass % or more and 15 mass % or less, relative to the total mass (100 mass %) of the flux.

[0098] ≪Organic acid≫ Examples of the organic acid include carboxylic acids and organic sulfonic acids. Examples of the carboxylic acid include aliphatic carboxylic acids and aromatic carboxylic acids.

[0099] Examples of aliphatic monocarboxylic acids include caproic acid, 2-bromohexanoic acid, enanthic acid, caprylic acid, pelargonic acid, isopelargonic acid, capric acid, caproleic acid, lauric acid (dodecanoic acid), undecanoic acid, Linderic acid, tridecanoic acid, myristoleic acid, pentadecanoic acid, isopalmitic acid, palmitoleic acid, Hiragonic acid, hydnocarpic acid, margaric acid, isostearic acid, elaidic acid, petroselinic acid, moroctic acid, eleostearic acid, talilic acid, vaccenic acid, riminoleic acid, vernolic acid, sterculic acid, nonadecanoic acid, eicosanoic acid, stearic acid, 12-hydroxystearic acid, oleic acid, linoleic acid, linolenic acid, myristic acid, 2,2-bis(hydroxymethyl)propionic acid, and 2,2-bis(hydroxymethyl)butanoic acid. Examples of aromatic monocarboxylic acids include salicylic acid, parahydroxyphenylacetic acid, benzoic acid, 2,3-dihydroxybenzoic acid, 2-quinolinecarboxylic acid, 3-hydroxybenzoic acid, p-anisic acid; picolinic acid, dipicolinic acid, and 3-hydroxypicolinic acid. Examples of dicarboxylic acids include oxalic acid, malonic acid, succinic acid, maleic acid, glutaric acid, diglycolic acid, citraconic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, eicosanedioic acid, o-phthalic acid, m-phthalic acid (isophthalic acid), and p-phthalic acid (terephthalic acid).

[0100] Further, examples of the carboxylic acid include tris(2-carboxyethyl) isocyanurate, 1,3-cyclohexanedicarboxylic acid; hydroxycarboxylic acids such as 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butanoic acid, citric acid, isocitrate, malic acid, and tartaric acid; dimer acid, trimer acid, hydrogenated dimer acid obtained by adding hydrogen to dimer acid, and hydrogenated trimer acid obtained by adding hydrogen to trimer acid.

[0101] Examples of the organic sulfonic acid include aliphatic sulfonic acids, aromatic sulfonic acids, etc. Examples of the aliphatic sulfonic acids include alkanesulfonic acids, alkanolsulfonic acids, etc.

[0102] Examples of alkanesulfonic acids include methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, 2-propanesulfonic acid, 1-butanesulfonic acid, 2-butanesulfonic acid, pentanesulfonic acid, hexanesulfonic acid, decanesulfonic acid, and dodecanesulfonic acid. Examples of alkanol sulfonic acids include 2-hydroxyethane-1-sulfonic acid, 2-hydroxypropane-1-sulfonic acid, 2-hydroxybutane-1-sulfonic acid, 2-hydroxypentane-1-sulfonic acid, 1-hydroxypropane-2-sulfonic acid, 3-hydroxypropane-1-sulfonic acid, 4-hydroxybutane-1-sulfonic acid, 2-hydroxyhexane-1-sulfonic acid, 2-hydroxydecane-1-sulfonic acid, and 2-hydroxydodecane-1-sulfonic acid. Examples of aromatic sulfonic acids include 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, p-toluenesulfonic acid, xylenesulfonic acid, p-phenolsulfonic acid, cresolsulfonic acid, sulfosalicylic acid, nitrobenzenesulfonic acid, sulfobenzoic acid, and diphenylamine-4-sulfonic acid.

[0103] When an organic acid is used as an active agent, one type may be used alone, or two or more types may be used in combination. Among the organic acids, it is preferable to include a dicarboxylic acid, and more preferable to include at least one selected from the group consisting of malonic acid, succinic acid, glutaric acid, suberic acid, and azelaic acid. The content of the organic acid in the flux of the present embodiment is preferably 15 mass % or less, more preferably 1 mass % or more and 13 mass % or less, and even more preferably 2.5 mass % or more and 12.5 mass % or less, relative to the total mass (100 mass %) of the flux.

[0104] <Amine compounds> Examples of the amine compound include rosin amine, azoles, guanidines, alkylamine compounds, and aminoalcohol compounds. Examples of the rosin amine include those exemplified in the above <Rosin>.

[0105] Examples of azoles include 2-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzoethyl ... 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazo imidazole compounds such as 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, epoxy-imidazole adduct, 2-methylbenzimidazole, 2-octylbenzimidazole, 2-pentylbenzimidazole, 2-(1-ethylpentyl)benzimidazole, 2-nonylbenzimidazole, 2-(4-thiazolyl)benzimidazole, and 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-amylphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-tert-octylphenol], 6-(2-benzotriazolyl)-4-tert-octyl-6'-tert-butyl-4'-methyl-2,2'-methylenebisphenol, 1,2,3-benzotriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole, carboxybenzotriazole, 1-[N triazole compounds such as 2,4-diamino-6-vinyl-s-triazine, 2,4-diamino-6-vinyl-s-triazine isocyanuric acid adduct, and 2,4-diamino-6-methacryloyloxyethyl-s-triazine; and tetrazole compounds such as 5-phenyltetrazole.

[0106] Examples of guanidines include 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, 1,3-di-o-cumenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine.

[0107] Examples of the alkylamine compound include ethylamine, triethylamine, ethylenediamine, triethylenetetramine, cyclohexylamine, hexadecylamine, and stearylamine.

[0108] Examples of the amino alcohol compound include alkanolamines such as 1-amino-2-propanol and N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine.

[0109] When an amine compound is used as the activator, one type may be used alone, or two or more types may be used in combination. The content of the amine compound in the flux of the present embodiment is preferably 5 mass % or less, more preferably 0.5 mass % or more and 4 mass % or less, and even more preferably 1 mass % or more and 3 mass % or less, relative to the total mass (100 mass %) of the flux.

[0110] <Halogen compounds> Examples of the halogen compound include amine hydrohalides and organic halogen compounds other than amine hydrohalides.

[0111] Amine hydrohalides are compounds obtained by reacting amines with hydrogen halides. Examples of amines include aliphatic amines, azoles, guanidines, etc. Examples of hydrogen halides include chlorine, bromine, and iodine hydrides. Examples of the aliphatic amine include ethylamine, diethylamine, triethylamine, and ethylenediamine. Examples of the guanidines and azoles include those exemplified in the description of amines below.

[0112] Examples of organic halogen compounds other than amine hydrohalides include halogenated aliphatic compounds, which are compounds in which some or all of the hydrogen atoms constituting the aliphatic hydrocarbon group have been substituted with halogen atoms. Examples of halogenated aliphatic compounds include halogenated aliphatic alcohols and halogenated heterocyclic compounds. Examples of halogenated aliphatic alcohols include 1-bromo-2-propanol, 3-bromo-1-propanol, 3-bromo-1,2-propanediol, 1-bromo-2-butanol, 1,3-dibromo-2-propanol, 2,3-dibromo-1-propanol, 1,4-dibromo-2-butanol, and trans-2,3-dibromo-2-butene-1,4-diol.

[0113] When a halogen compound is used as an activator, one type may be used alone or two or more types may be used in combination. Among the halogen compounds, a halogenated aliphatic compound may be used, and it is preferable to use a halogenated aliphatic alcohol. The content of the halogen compound in the flux of the present embodiment is preferably 5 mass % or less, more preferably 0.5 mass % or more and 4 mass % or less, and even more preferably 1 mass % or more and 2.5 mass % or less, relative to the total mass (100 mass %) of the flux.

[0114] <Other ingredients> The flux of the present embodiment may contain other components as necessary in addition to the above-mentioned resin, solvent, thixotropic agent, and activator. Examples of other components include metal deactivators, surfactants, antioxidants (such as hindered phenol-based antioxidants), silane coupling agents, and colorants.

[0115] ≪Metal deactivator≫ Examples of metal deactivators include hindered phenol compounds and nitrogen compounds. The term "metal deactivator" as used herein refers to a compound that has the ability to prevent metals from deteriorating due to contact with certain compounds. The hindered phenol compound refers to a phenol compound having a bulky substituent (for example, a branched or cyclic alkyl group such as a t-butyl group) at least on one of the ortho positions of the phenol. Examples of the nitrogen compound in the metal deactivator include hydrazide-based nitrogen compounds, amide-based nitrogen compounds, triazole-based nitrogen compounds, and melamine-based nitrogen compounds.

[0116] <Surfactants> Examples of the surfactant include nonionic surfactants and cationic surfactants. Examples of the nonionic surfactants include aliphatic alcohol polyoxyethylene adducts, aromatic alcohol polyoxyethylene adducts, polyhydric alcohol polyoxyethylene adducts, aliphatic alcohol polyoxypropylene adducts, aromatic alcohol polyoxypropylene adducts, polyhydric alcohol polyoxypropylene adducts, etc. Examples of the cationic surfactants include diamine-terminated polyethylene glycol, diamine-terminated polyethylene glycol-polypropylene glycol copolymers, aliphatic amine polyoxyethylene adducts, aromatic amine polyoxyethylene adducts, polyvalent amine polyoxyethylene adducts, polyvalent amine polyoxypropylene adducts, etc.

[0117] As described above, the flux of this embodiment contains a resin, a solvent, a compound (compound (T0)) represented by the general formula (T-0), and an activator. By adopting compound (T0) having an ester bond (-CO-O-) between a hydroxy group (-OH) derived from 12-hydroxystearic acid and a carboxy group (-COOH) derived from 12-hydroxystearic acid in the molecule, the flux can enhance the effect of suppressing the occurrence of pillow defects (HiP) when mounting BGA components, etc., although the reason is unclear.

[0118] The flux of the preferred embodiment (1) contains, in addition to the compound (T0), a compound represented by the general formula (T-1), i.e., an alkylenediimino group (-NH-(CH 2 The flux further contains a compound (T1) having two 12-hydroxyoctadecanoyl groups via a 12-hydroxyoctadecanoyl group (Q-NH-). The flux of the preferred embodiment (1) can further enhance the effect of suppressing the occurrence of HiP during mounting of BGA components and the like.

[0119] Alternatively, the flux of the preferred embodiment (2) may contain, in addition to the compound (T0) and the compound (T1), a compound represented by the general formula (T-2), i.e., an alkylenediimino group (-NH-(CH 2 The flux according to the preferred embodiment (2) further contains a compound (T2) having one 12-hydroxyoctadecanoyl group and an acyl group (RC(=O)-) via a 12-hydroxyoctadecanoyl group (R-NH-). The flux according to the preferred embodiment (2) further enhances the effect of suppressing the occurrence of HiP during the mounting of BGA components and the like.

[0120] Furthermore, the flux according to the above embodiment can suppress the occurrence of HiP and also reduce voids when mounting BGA components and the like.

[0121] (Solder paste) One embodiment of the solder paste according to the second aspect contains the flux of the above-mentioned embodiment and solder powder. Such a solder paste can be prepared by mixing the flux of the above-mentioned embodiment and the solder powder using a known method. As the solder metal constituting the solder powder, a solder alloy having a known composition can be used. The solder alloy may be a solder containing only Sn, or a solder alloy such as Sn-Ag, Sn-Cu, Sn-Ag-Cu, Sn-Bi, or Sn-In, or an alloy of these with added elements such as Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, or P. The solder alloy may be a Sn-Pb-based solder alloy or a Sn-Pb-based solder alloy to which Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, P, etc. have been added. The solder alloy is preferably a solder alloy that does not contain Pb, and more preferably a solder alloy that contains Sn, Ag, and Cu (Sn-Ag-Cu based solder alloy).

[0122] The soldering conditions in the soldering step may be appropriately set according to the melting point of the solder alloy. For example, when a Sn-Ag-Cu solder alloy is used, the temperature of the molten solder is preferably 230 to 280°C, more preferably 240 to 260°C. Alternatively, when a solder alloy containing Sn and Bi (Sn-Bi solder alloy) is used, the temperature of the molten solder is preferably 170 to 220°C, more preferably 180 to 200°C. The term "Sn-Bi solder alloy" as used herein refers to a solder alloy containing Sn and Bi as the main components. An example of such a solder alloy is one in which the total mass of Sn and Bi is 90 mass% or more of the total mass of the solder alloy, and the mass of Bi is 30 to 65 mass% of the total mass of the solder alloy.

[0123] Flux Content: The content of the flux in the solder paste of this embodiment is preferably 5 to 30 mass %, and more preferably 5 to 15 mass %, based on the total mass of the solder paste.

[0124] According to the solder paste of the present embodiment described above, since the flux of the above-mentioned embodiment is used, the effect of suppressing the occurrence of the HiP defect can be enhanced. The solder paste of this embodiment is particularly suitable for soldering to surface mount components such as BGA and CSP, which are prone to pillow defects (HiP).

[0125] (Method of Manufacturing Joint) One embodiment of the method for producing a bonded body according to the third aspect is a method including a step of obtaining a bonded body by soldering a component and a substrate, in which reflow is performed using the solder paste according to the second aspect described above. Hereinafter, one embodiment of a method for producing such a bonded body will be described. The method for manufacturing a bonded body according to this embodiment includes a solder paste application step, a component attachment step, and a reflow step, in this order.

[0126] [Solder paste application process] In the solder paste application step, the solder paste according to the second aspect is applied to the surface of the board. Examples of the substrate include a printed wiring board and a wafer. Examples of methods for applying the solder paste include a method of printing and applying the solder paste using a mask having an opening, a method of ejecting the solder paste using a dispenser or the like, and a method of transferring the solder paste using a probe pin or the like.

[0127] [Parts installation process] In the component mounting process, components are mounted at predetermined positions on the board on which the solder paste has been applied. Examples of components include chips, integrated circuits, transistors, diodes, resistors, capacitors, semiconductor packages such as CSPs (Chip Size Packages), and BGA (Ball Grid Array) substrates.

[0128] [Reflow process] In the reflow step, the atmosphere for the reflow operation may be, for example, a nitrogen gas atmosphere, a reducing gas atmosphere, or an air atmosphere. The reducing gas atmosphere may be formed, for example, by volatilizing a reducing compound in a reflow furnace, or by supplying a reducing gas obtained by passing nitrogen through a liquid reducing compound to the reflow furnace. As the reducing compound, formic acid is preferable. Reflow in an air atmosphere (air reflow) generally refers to soldering in heated air (approximately 80 vol% nitrogen, approximately 20 vol% oxygen).

[0129] In the reflow process, the inside of a reflow furnace is heated, and the board after mounting the components is heated to a temperature higher than the melting point of the solder powder contained in the solder paste (i.e., the peak temperature) (this is called the main heating process). The heating temperature may be, for example, a temperature higher than the melting point of the solder powder by 5 to 30° C. The heating time may be, for example, 30 seconds to 3 minutes.

[0130] The reflow process may include a preheating step prior to the main heating step. In the preheating step, the board after mounting the components is heated in a reflow furnace at a temperature lower than the melting point of the solder powder contained in the solder paste. The heating temperature may be, for example, 150 to 180° C. The heating time may be, for example, 1 to 5 minutes.

[0131] According to the manufacturing method of the bonded body according to the present embodiment described above, the use of the solder paste containing the flux of the present embodiment described above suppresses the occurrence of head-on defects (HiP) at the joint between the component and the board, making it possible to manufacture a highly reliable bonded body. In particular, this manufacturing method of the bonded body is useful as a method for manufacturing a bonded body to which surface-mounted components such as BGA and CSP are soldered. EXAMPLES

[0132] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

[0133] <Preparation of flux> (Examples 1 to 65, Comparative Examples 1 to 7) Each flux of the examples and comparative examples was prepared by mixing the components so as to obtain the composition shown in Tables 1 to 11.

[0134] In the table, the content of each component is shown as a percentage (mass%) relative to the total mass (100 mass%) of the flux. The raw materials used are shown below. "Total content of bisamides" indicates the total content (mass%) of the compound represented by general formula (T-1), the compound represented by general formula (T-2), the compound represented by general formula (T-0), and hexamethylene bis(lauric acid amide). The "general formula (T-1) / general formula (T-0) mass ratio" indicates the ratio of the mass of the compound represented by general formula (T-1) to the mass of the compound represented by general formula (T-0). The "general formula (T-2) / general formula (T-0) mass ratio" indicates the ratio of the mass of the compound represented by general formula (T-2) to the mass of the compound represented by general formula (T-0).

[0135] ·resin Rosin and copolymers were used. The rosins used were acrylic acid modified hydrogenated rosin, hydrogenated rosin, and polymerized rosin. The copolymer used was an ethylene / acrylic acid copolymer.

[0136] ·solvent Diethylene glycol monohexyl ether (HeDG), diethylene glycol mono-2-ethylhexyl ether (EHDG), and tetraethylene glycol dimethyl ether were used, respectively.

[0137] Thixotropic agent Bisamide, hydrogenated castor oil, and polyamide (saturated fatty acid polyamide, melting point 200°C or less) were used.

[0138] Bisamide Compounds represented by general formula (T-1) where q=6 Compounds represented by general formula (T-1) where q=2

[0139] r=6 / R=C in general formula (T-2) 17 H 35 Compounds represented by the formula r=2 / R=C in general formula (T-2) 17 H 35 Compounds represented by the formula r=6 / R=C in general formula (T-2) 11 H 23 Compounds represented by the formula r=2 / R=C in general formula (T-2) 11 H 23 Compounds represented by the formula

[0140] Hexamethylenebis(lauric acid amide): A compound represented by the following chemical formula

[0141] [ka]

[0142] Compound represented by general formula (T-0) where p=6 Compound represented by general formula (T-0) where p=2 Compound represented by general formula (T-0) where p=8

[0143] ·Activators Organic acids, amine compounds and halogen compounds were used. The organic acids used were dimer acid, malonic acid, succinic acid, glutaric acid, suberic acid, azelaic acid, and 2-bromohexanoic acid. The amine compound used was 1,2,3-benzotriazole. The halogen compound used was trans-2,3-dibromo-2-butene-1,4-diol.

[0144] ·others As the antioxidant, a hindered phenol-based antioxidant (product name IRGANOX 245, manufactured by BASF Japan Ltd.) was used.

[0145] <Preparation of solder paste> The fluxes of the above-mentioned Examples and Comparative Examples were mixed with the solder powders shown below to prepare solder pastes. Each of the prepared solder pastes contained 11 mass % flux and 89 mass % solder powder.

[0146] Solder powder: Powder made of a solder alloy containing 0.5 mass% Cu, 3.0 mass% Ag, and the remainder Sn. The solidus temperature of this solder alloy is 217° C., and the liquidus temperature is 220° C. The size of the solder powder is a size (particle size distribution) that satisfies symbol 5 in the powder size classification (Table 2) in JIS Z 3284-1:2014.

[0147] <Evaluation> The suppression of the occurrence of pillow defects (HiP) was evaluated as follows. The evaluation results are shown in Tables 1 to 11.

[0148] [Evaluation of the prevention of pillow defects (HiP)] The following printed circuit boards and BGA components were used. Printed circuit board: Material: FR-4, thickness: 0.8 mm, land dimensions: diameter 0.24 mm, pad diameter 300 μm, surface treatment: Cu-OSP BGA components: component size 13mm x 13mm, thickness 0.5mm, pad diameter 300μm, surface treatment electroless NiAu (nickel gold); ball composition M705 (Sn-3.0Ag-0.5Cu), ball size 250μm, bump pitch 400μm, number of BGA bumps (I / O) 432 x number of BGA components 3 = 1296 pieces

[0149] Heat Treatment: The BGA components were subjected to a heat treatment at a temperature of 85°C and a relative humidity of 85% RH for 24 hours, and then further to a heat treatment at 125°C for 1 hour.

[0150] A solder paste was printed on a printed circuit board using a metal mask with a thickness of 0.08 mm. The BGA components that had been subjected to the heat treatment were mounted on top of the solder paste. Then, reflow was performed in the air (air reflow). The reflow conditions (reflow profile) were preheating at 130-220°C for 90 seconds, followed by heating at 220°C or higher for 42 seconds. The peak temperature was 242°C. This reflow profile is shown in Figure 1.

[0151] After reflow, the fusion state of each BGA ball on the BGA bump with the solder paste was checked, and the number of BGA balls where the two were not fused properly and pillow defects were generated was counted. The suppression of HiP generation was evaluated based on the following criteria. Ranks 1 to 4 were considered to be pass, and rank 5 was considered to be fail. Judgment criteria Rank 1: 0 Rank 2: 1 to 3 Rank 3: 4 to 7 Rank 4: 8 to 10 Rank 5: 11 or more

[0152] [Table 1]

[0153] In Table 1, when the flux of Comparative Example 1, which contains the compound represented by general formula (T-1) as a thixotropic agent, was used, the evaluation result of the suppression of HiP generation was poor. On the other hand, when the flux of Example 1 was used, in which the compound represented by general formula (T-0) was adopted instead of the compound represented by general formula (T-1), the number of BGA balls with pillow defects decreased compared to the case where the flux of Comparative Example 1 was used, and the effect of suppressing the occurrence of HiP was improved.

[0154] Furthermore, in the case of using the flux of Example 5 in which the compound represented by general formula (T-0) and the compound represented by general formula (T-1) were used in combination, the number of BGA balls with pillow defects was significantly reduced, and the effect of suppressing the occurrence of HiP was significantly improved.

[0155] [Table 2]

[0156] [Table 3]

[0157] From the results shown in Tables 2 and 3, it can be seen that the effect of suppressing HiP generation is easily enhanced by setting the mass ratio of the compound represented by general formula (T-1) / the compound represented by general formula (T-0) to be 4 or more and 40 or less. Furthermore, in Table 3, by comparing Comparative Example 1 with Examples 5 to 13, it can be seen that the effect of suppressing the occurrence of HiP is easily obtained by containing 0.1 mass % or more of the compound represented by general formula (T-0) relative to the total mass (100 mass %) of the flux.

[0158] [Table 4]

[0159] In Table 4, by comparing Examples 8, 14, and 19 with Examples 15 to 18, it can be seen that by using the compound represented by general formula (T-0), the compound represented by general formula (T-1), and further the compound represented by general formula (T-2) in combination, it is possible to reduce the number of BGA balls that had pillow defects to zero, and the effect of suppressing the occurrence of HiP is further easily obtained.

[0160] [Table 5]

[0161] In Table 5, by comparing Examples 8, 20, and 21 with Examples 22 to 24, it can be seen that by using the compound represented by general formula (T-0), the compound represented by general formula (T-1), and further the compound represented by general formula (T-2) in combination, it is possible to reduce the number of BGA balls that had pillow defects to zero, and the effect of suppressing the occurrence of HiP is further easily obtained.

[0162] [Table 6]

[0163] [Table 7]

[0164] [Table 8]

[0165] [Table 9]

[0166] [Table 10]

[0167] [Table 11]

[0168] In Tables 6 to 11, when the fluxes of Examples 8 and 25 to 65 to which the present invention is applied were used, the evaluation result was rank 3, 2, or 1, and it can be confirmed that the effect of suppressing the occurrence of HiP is good.

[0169] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Addition, omission, substitution, and other modifications of the configuration are possible without departing from the spirit of the present invention. The present invention is not limited by the above description, but is limited only by the scope of the attached claims.

Claims

1. Contains resin, solvent, thixotropic agent and activator, The flux, wherein the thixotropic agent contains a compound represented by the following general formula (T-0): 【Chemistry 1】 [In the formula, p is an integer from 2 to 8.]

2. The flux according to claim 1, wherein p in the general formula (T-0) is 2 or 6.

3. The flux according to claim 1, wherein the thixotropic agent further contains a compound represented by the following general formula (T-1): 【Chemistry 2】 [In the formula, q is an integer from 2 to 8.]

4. The flux according to claim 3, wherein q in the general formula (T-1) is 2 or 6.

5. The flux according to claim 3, wherein the thixotropic agent further contains a compound represented by the following general formula (T-2): 【Chemistry 3】 [In the formula, r is an integer from 2 to 8. R is an aliphatic hydrocarbon group having 11 to 19 carbon atoms.]

6. The flux according to claim 5, wherein r in the general formula (T-2) is 2 or 6.

7. The flux according to claim 5, wherein R in the general formula (T-2) is a linear alkyl group having 17 carbon atoms.

8. The flux according to claim 1, wherein the content of the compound represented by the general formula (T-0) is 0.1 mass% or more and 1 mass% or less with respect to the total mass (100 mass%) of the flux.

9. The mixing ratio of the compound represented by the general formula (T-0) to the compound represented by the general formula (T-1) is Compound represented by general formula (T-1) / compound represented by general formula (T-0), The flux according to claim 3, wherein the mass ratio represented by is 4 or more and 40 or less.

10. A compound represented by the general formula (T-0), A compound represented by the general formula (T-1), A compound represented by the general formula (T-2), The flux according to claim 5, wherein the total content of the above is 1 mass % or more and 10 mass % or less with respect to the total mass (100 mass %) of the flux.

11. A solder paste comprising the flux according to any one of claims 1 to 10 and solder powder.

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