Flux and solder paste

Abstract

This invention provides a flux that enhances the effect of suppressing the occurrence of pillow defects (HiP), and a solder paste containing the same. [Solution] The present invention relates to a flux containing a resin, a solvent, a thixotropic agent, and an activator, characterized in that the thixotropic agent contains a compound represented by the general formula (T-0). In the general formula (T-0), p is an integer from 2 to 8. [C1] TIFF2026078744000026.tif25170

Description

[Technical Field]

[0001] This invention relates to flux and solder paste. [Background technology]

[0002] When manufacturing electronic components, the components are fixed to the circuit board, and the electrical connections between the components and the circuit board are made by soldering. Soldering uses flux, solder powder, and solder paste, which is a mixture of flux and solder powder. Flux chemically removes metal oxides present on the metal surfaces of the objects to be soldered and the solder itself, allowing for the movement of metal elements at the boundary between them. Therefore, using flux during soldering results in the formation of intermetallic compounds between the two, leading to a strong bond.

[0003] In soldering using solder paste, the solder paste is first printed onto the circuit board, then the components are mounted, and the circuit board with the components mounted is heated in a heating furnace called a reflow oven. This melts the solder powder contained in the solder paste, and the components are bonded to the circuit board, creating a joint.

[0004] During the aforementioned soldering process, the condition of the joint between the component and the circuit board is crucial. For example, depending on the oxidation state of the component and the activity level of the flux, metal oxides on the component surface may not be removed, resulting in a phenomenon where the component and solder paste do not fuse properly during reflow soldering (head-in-pillow (HiP)). If the joint is in such a head-in-pillow (HiP) state, the component to be mounted and the circuit board will not bond properly. To address such bonding defects, fluxes have been proposed that use a combination of specific organic acids and specific halogen compounds as activators, or by adjusting the proportions of these compounds (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2021-102231 [Patent Document 2] Japanese Patent Publication No. 2020-82106 [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, with the recent trend towards miniaturization of electronic devices and reduction of circuit board size, there is a demand for space-saving and high-performance components. In this context, 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, the narrow process window makes high-impedance (HiP) defects more likely to occur, and this is also common in BGA components. However, conventional fluxes make it difficult to suppress the occurrence of hi-p (High-Intensity Pitting) defects in BGA components and the like.

[0007] This invention has been made in view of the above circumstances, and aims to provide a flux that can enhance the effect of suppressing the occurrence of pillow defects (HiP), and a solder paste containing the same. [Means for solving the problem]

[0008] To solve the above problems, the present invention employs the following configuration.

[0009] [1] Contains resin, solvent, thixotropic agent and activator, A flux comprising a compound represented by the following general formula (T-0) as the thixotropic agent.

[0010] [ka] [In the formula, p is an integer between 2 and 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% by mass or more and 1% by mass or less based on the total mass (100% by 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]

Chemical formula

[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) and 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]

Chemical formula

[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 the items [7] to [9], wherein the 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% by mass or more and 10% by mass or less with respect to the total mass (100% by mass) of the flux.

[0022]

[11] Solder paste comprising the flux described in any one of items [1] to

[10] and solder powder. [Effects 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 same. [Brief explanation of the drawing]

[0024] [Figure 1] This figure shows the reflow profile in the evaluation of the example. [Modes for carrying out the invention]

[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 by containing a compound represented by the following general formula (T-0).

[0026] [ka] [In the formula, p is an integer between 2 and 8.]

[0027] <Resin> The resin contained in the flux of this embodiment can be rosin, copolymer, or the like. Examples of copolymers include olefin / (α-substituted) acrylic resin.

[0028] Rosin In this invention, "rosin" includes natural resins mainly composed of abietic acid, including a mixture of abietic acid and its isomers, and chemically modified natural resins (sometimes referred to as rosin derivatives).

[0029] The abietic acid content in natural resins is, for example, between 40% and 80% by mass relative to the natural resin. In this specification, "main component" refers to a component that makes up a compound and is present in an amount of 40% by mass or more.

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

[0031] In the present invention, "natural resins that have been chemically modified (rosin derivatives)" include those that have been subjected to one or more treatments selected from the group consisting of hydrogenation, dehydrogenation, neutralization, alkylene oxide addition, amidation, dimerization and polymerization, esterification, and Diels-Alder cycloaddition.

[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 esters, acid-modified hydrogenated rosin, acid-modified hydrogenated rosin, acid-modified disproportionated rosin, acid-modified disproportionated rosin, phenol-modified rosin, and α,β-unsaturated carboxylic acid modified products (acrylic rosin, maleated rosin, fumarated rosin, etc.), as well as purified, hydrated and disproportionated products of the polymerized rosin, and purified, hydrated 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, and the like. Examples of rosinamines include dehydroabiethylamine and dihydroabiethylamine. Rosinamine refers to so-called disproportionated rosinamines.

[0033] ≪Olefin / (α-substituted) acrylic resin≫ The olefin / (α-substituted) acrylic acid resin has repeating units (a1) derived from alkenes and repeating units (a2) derived from acrylic acid (hereinafter referred to as "(α-substituted) acrylic acid") in which the hydrogen atom bonded to the carbon atom at the α position may be substituted with a substituent. In addition to repeating units (a1) and (a2), the olefin / (α-substituted) acrylic acid resin may also have other repeating units (a3). (α-substituted) acrylic acid means either acrylic acid, or acrylic acid in which the hydrogen atom bonded to the α-carbon atom is substituted with a substituent, or both.

[0034] [Repeating unit (a1)] The repeating unit (a1) is derived from an alkene. Examples of the aforementioned alkenes include C n H 2n Examples of compounds represented by the formula are shown. Here, n is an integer of 2 or more, preferably between 2 and 10, more preferably between 2 and 6, even more preferably between 2 and 3, and particularly preferably 2. C n H 2nExamples of compounds represented by include ethylene, propylene, isobutene, 1-butene, 1-pentene, and 1-hexene, with one or more selected from the group consisting of ethylene and propylene being preferred, and ethylene being more preferred.

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

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

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

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

[0039] [Repeating Unit (a3)] Repeating unit (a3) ​​is any repeating unit other than repeating unit (a1) and repeating unit (a2).

[0040] Examples of repeating units (a3) ​​include repeating units derived from acrylic acid esters in which the hydrogen atom bonded to the α-carbon atom may be substituted with a substituent (hereinafter referred to as "(α-substituted) acrylic acid esters"), repeating units derived from alkylene oxides, and repeating units having aromatic groups.

[0041] (α-substituted) acrylic acid ester means either an acrylic acid ester, or an acrylic acid ester in which the hydrogen atom bonded to the α-carbon atom is substituted with a substituent, or both. Examples of such substituents include alkyl groups having 1 to 5 carbon atoms.

[0042] (α-substituted) acrylic acid esters are reaction products of (α-substituted) acrylic acid and alcohols. Examples of alcohols include those with a linear carbon chain having 1 to 24 carbon atoms.

[0043] Examples of (α-substituted) acrylic acid esters include 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. Among these, methyl acrylate, ethyl acrylate, t-butyl acrylate, methyl methacrylate, ethyl methacrylate, and t-butyl methacrylate are preferred.

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

[0045] Examples of repeating units having aromatic groups include repeating units having aromatic groups such as phenyl groups and naphthyl groups. Examples of repeating units having phenyl groups include repeating units derived from styrene or its derivatives.

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

[0047] In olefin / (α-substituted)acrylic resins, the content of repeating units (a1) is preferably 10% to 98% by mass, more preferably 40% to 97% by mass, and even more preferably 65% ​​to 95% by mass, based on the total amount (100% by mass) of the olefin / (α-substituted)acrylic resin. When the content of repeating units (a1) is above the lower limit of the preferred range mentioned above, the electrical reliability of the joint is more easily improved. When the content of repeating units (a1) is below the upper limit of the preferred range mentioned above, the separation of the solder paste into solder powder and flux over time is more easily suppressed. Furthermore, cracking of the flux residue due to temperature changes is more easily reduced. Furthermore, solderability is more easily improved. Furthermore, the solubility of the olefin / (α-substituted) acrylic resin in the flux is more easily improved.

[0048] In olefin / (α-substituted)acrylic resins, the content of repeating units (a2) is preferably 2% to 90% by mass, more preferably 3% to 60% by mass, and even more preferably 5% to 35% by mass, based on the total amount (100% by mass) of the olefin / (α-substituted)acrylic resin. By ensuring that the content of repeating units (a2) is above the lower limit of the preferred range described above, it becomes easier to suppress the separation of the solder paste into solder powder and flux over time. It also becomes easier to reduce cracking of the flux residue due to temperature changes. Furthermore, it becomes easier to improve solderability. In addition, it becomes easier to improve the solubility of olefin / (α-substituted) acrylic resin in the flux. By keeping the content of repeating units (a2) below the upper limit of the preferred range mentioned above, the electrical reliability of the joint can be easily improved.

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

[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 resins>> Examples of resins other than rosin and olefin / (α-substituted) acrylic resins include terpene resins, modified terpene resins, terpene phenol resins, modified terpene phenol resins, styrene resins, modified styrene resins, xylene resins, modified xylene resins, acrylic resins, polyethylene resins, and the like. 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 this embodiment, the resin may be used alone or as a mixture of two or more types. 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 resins, even 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 particularly preferably a combination of 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] In this embodiment, the resin content in the flux is preferably 20% to 60% by mass, more preferably 25% to 55% by mass, and even more preferably 30% to 50% by mass, based on the total mass (100% by mass) of the flux.

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

[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- Examples include tyl-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-decine-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, and monoalkylpropylene glycol.

[0057] Examples of terpineols include α-terpineol, β-terpineol, γ-terpineol, and terpineol mixtures (i.e., mixtures in which the main component is α-terpineol and which also contain β-terpineol or γ-terpineol). Other solvents include, for example, dioctyl sebacate and liquid paraffin.

[0058] In the flux of this embodiment, one solvent may be used alone, or two or more solvents may be used in combination. Among the above, glycol ether-based solvents are preferred, and more preferably, at least one selected from the group consisting of HeDG, EHDG, and tetraethylene glycol dimethyl ether is used, from the viewpoint of viscosity stability when used as a solder paste and the melting properties of the solder powder.

[0059] In this embodiment, the solvent content in the flux is the remainder of the flux and is determined according to the content of other components. For example, the solvent content in the flux of this embodiment may be 20% to 70% by mass, 25% to 65% by mass, or 30% to 60% by mass, based on the total mass (100% by mass) of the flux.

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

[0061] In this embodiment, the total content of the thixotropin in the flux is preferably 1% to 20% by mass, more preferably 2% to 15% by mass, and even more preferably 3% to 14% by mass, based on the total mass (100% by mass) of the flux.

[0062] Compounds represented by the general formula (T-0) Compounds represented by the general formula (T-0) (compound (T0)) have an ester bond (-CO-O-) in their molecule between a hydroxyl group (-OH) derived from 12-hydroxystearic acid and a carboxyl group (-COOH) also derived from 12-hydroxystearic acid.

[0063] [ka] [In the formula, p is an integer between 2 and 8.]

[0064] In the above formula (T-0), p is an integer between 2 and 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] The following are specific examples of compounds represented by the general formula (T-0).

[0066] [ka]

[0067] In the flux of this embodiment, compound (T0) may be used alone or in combination of two or more compounds. Suitable examples of compound (T0) include the compound represented by p=6 in general formula (T-0), the compound represented by p=2 in general formula (T-0), a combination of the compound represented by p=6 in general formula (T-0) and the compound represented by p=2 in general formula (T-0), and a combination of the compound represented by p=6 in general formula (T-0) and the compound represented by p=8 in general formula (T-0). In this embodiment, the content of compound (T0) in the flux is preferably 0.1% by mass or more and 1% by mass or less, more preferably 0.2% by mass or more and 1% by mass or less, and even more preferably 0.3% by mass or more and 1% by mass or less, based on the total mass (100% by mass) of the flux. If the content of compound (T0) is within the aforementioned preferred range, the effect of suppressing HiP generation is more easily obtained. If it is above the lower limit of the aforementioned preferred range, the effect of suppressing HiP generation is more easily enhanced.

[0068] Compounds represented by the general formula (T-1) The compound represented by the general formula (T-1) (compound (T1)) has two 12-hydroxyoctadecanoyl groups in its molecule via an alkylene diimino group (-NH-(CH2)q-NH-).

[0069] [ka] [In the formula, q is an integer between 2 and 8.]

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

[0071] The following are specific examples of compounds represented by the general formula (T-1).

[0072] [ka]

[0073] In the flux of this embodiment, compound (T1) may be used alone or in combination of two or more types. Suitable examples of compound (T1) include the compound represented by p=6 in general formula (T-1), the compound represented by p=2 in general formula (T-1), and a combination of the compound represented by p=6 in general formula (T-1) and the compound represented by p=2 in general formula (T-1). In this embodiment, the content of compound (T1) in the flux is preferably 0.5% by mass or more and 7% by mass or less, more preferably 1% by mass or more and 7% by mass or less, and even more preferably 2% by mass or more and 7% by mass or less, based on the total mass (100% by mass) of the flux. If the content of compound (T1) is within the aforementioned preferred range, the effect of suppressing HiP generation is more easily obtained. If it is above the lower limit of the aforementioned preferred range, the effect of suppressing HiP generation is more easily enhanced.

[0074] In the flux of this embodiment, it is preferable that the mixing ratio of compound (T0) and compound (T1) is 4 to 40 as a mass ratio expressed as compound (T1) / compound (T0). If such a mass ratio falls within the aforementioned preferred range, the effect of suppressing HiP generation can be more easily enhanced.

[0075] Compounds represented by the general formula (T-2) The compound represented by the general formula (T-2) (compound (T2)) has one 12-hydroxyoctadecanoyl group and an acyl group (RC(=O)-) via an alkylene diimino group (-NH-(CH2)r-NH-) within its molecule.

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

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

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

[0079]

Chemical formula

[0080] In the flux of the present embodiment, the compound (T2) may be used alone or in combination of two or more. As the compound (T2), a compound represented by p = 6 in the general formula (T-2) and a compound represented by p = 2 in the general formula (T-2) are preferably mentioned. Alternatively, as the compound (T2), R = C in the general formula (T-2) 17 H 35 - represented by the formula, R = C in the general formula (T-2) 11 H 23 - represented by the formula are preferably mentioned. Alternatively, as the compound (T2), p = 6, R = C in the general formula (T-2) 17 H 35 - represented by the formula, p = 2, R = C in the general formula (T-2) 17 H 35 - represented by the formula, p = 6, R = C in the general formula (T-2) 11 H 23 - represented by the formula, p = 2, R = C in the general formula (T-2) 11 H 23 - represented by the formula are preferably mentioned.

[0081] In this embodiment, the content of compound (T2) in the flux is preferably 0.1% to 2% by mass, more preferably 0.2% to 2% by mass, and even more preferably 0.5% to 2% by mass, based on the total mass (100% by mass) of the flux. If the content of compound (T2) is within the preferred range described above, the effect of suppressing HiP generation is more easily obtained. If it is above the lower limit of the preferred range described above, the effect of suppressing HiP generation is more easily enhanced.

[0082] In the flux of this embodiment, the mixing ratio of compound (T0) and compound (T2) is preferably 1 to 3 as a mass ratio expressed as compound (T2) / compound (T0), more preferably 1.2 to 2.6, and even more preferably 1.3 to 2.5. If such a mass ratio falls within the aforementioned preferred range, the effect of suppressing HiP generation can be more easily enhanced.

[0083] In the flux of this embodiment, it is preferable that the thixotropic agent further contains compound (T1) in addition to compound (T0). This further enhances the effect of suppressing HiP generation. When the thixotropic agent contains the compound (T0) and the compound (T1), the total content of these two components may be 0.5% by mass or more, preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, and particularly preferably 4% by mass or more, based on the total mass (100% by mass) of the flux. For example, the total content of these two components is preferably 1% to 7% by mass, more preferably 2% to 6% by mass, even more preferably 3% to 5.5% by mass, and particularly preferably 4% to 5% by mass, based on the total mass of the flux (100% by mass). If the total content of compound (T0) and compound (T1) is within the aforementioned preferred range, the effect of suppressing HiP generation is more easily obtained. If it is above the lower limit of the aforementioned preferred range, the effect of suppressing HiP generation is more easily enhanced.

[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% by mass) of these two components is preferably 2% by mass or more and 25% by mass or less, more preferably 4% by mass or more and 20% by mass or less, and may also be 10% by mass or more and 19% by mass or less. If the ratio (mass ratio) of the content of compound (T0) to the total content of compound (T1) is within the preferred range, the effect of suppressing HiP generation is more likely to be obtained. If it is above the lower limit of the preferred range, the effect of suppressing HiP generation is more likely to be enhanced.

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

[0086] In the flux of this embodiment, the thixotropic agent is preferably a compound (T1) and a compound (T2) in addition to the compound (T0). This further enhances the effect of suppressing HiP generation. When compound (T0), compound (T1), and compound (T2) are included, the total content of these three components is preferably 1% by mass or more and 10% by mass or less, more preferably 1.5% by mass or more and 10% by mass or less, and even more preferably 2.5% by mass or more and 10% by mass or less, based on the total mass (100% by mass) of the flux. If the total content of compound (T0), compound (T1), and compound (T2) is within the aforementioned preferred range, the effect of suppressing HiP generation is more likely to be obtained. If it is above the lower limit of the aforementioned preferred range, the effect of suppressing HiP generation is more likely to be further enhanced.

[0087] When the thixotropic agent contains compound (T0), compound (T1), and compound (T2), the ratio of the content of compound (T0) to the total content (100% by mass) of these three components is preferably 3% by mass or more and 20% by mass or less, more preferably 4% by mass or more and 17.5% by mass or less, and even more preferably 5% by mass or more and 15% by mass or less. If the ratio of the content of compound (T0) to the total content of compound (T1) and compound (T2) is within the preferred range, the effect of suppressing HiP generation is more likely to be obtained. If it is above the lower limit of the preferred range, the effect of suppressing HiP generation is more likely to be enhanced.

[0088] In the flux of this embodiment, when compound (T0), compound (T1), and compound (T2) are included, a preferred mixing ratio of these three components is, for example, a form in which, based on the total content (100% by mass) of the three components, the content of compound (T1) is 50% by mass or more and 87.5% by mass or less, the content of compound (T2) is 7.5% by mass or more and 32.5% by mass or less, and the content of compound (T0) is 5% by mass or more and 17.5% by mass or less.

[0089] <<Other thixotropic agents>> The thixotropic agent contained in the flux of this embodiment may include other thixotropic agents other than the compounds (T0), (T1), and (T2) described above. Other thixotropic agents include, for example, amide-based thixotropic agents, ester-based thixotropic agents, and sorbitol-based thixotropic agents.

[0090] Examples of amide-based thixotropes include monoamides, bisamides (excluding the aforementioned 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 amide, methylol stearate amide, methylol amide, and fatty acid ester amide. Examples of bisamides include ethylenebis-fatty acid (fatty acid with 6 to 24 carbon atoms) amide, hexamethylenebis-fatty acid (fatty acid with 6 to 24 carbon atoms) amide, and aromatic bisamides. Examples of fatty acids that are raw materials for the bisamides include stearic acid (18 carbon atoms), oleic acid (18 carbon atoms), and lauric acid (12 carbon atoms). 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 acyclic amide oligomers.

[0091] The aforementioned cyclic amide oligomers include amide oligomers obtained by cyclic polycondensation of a dicarboxylic acid and a diamine, amide oligomers obtained by cyclic polycondensation of a tricarboxylic acid and a diamine, amide oligomers obtained by cyclic polycondensation of a dicarboxylic acid and a triamine, amide oligomers obtained by cyclic polycondensation of a tricarboxylic acid and a triamine, amide oligomers obtained by cyclic polycondensation of a dicarboxylic acid and a tricarboxylic acid and a diamine, amide oligomers obtained by cyclic polycondensation of a dicarboxylic acid and a tricarboxylic acid and a triamine, amide oligomers obtained by cyclic polycondensation of a dicarboxylic acid, a diamine and a triamine, amide oligomers obtained by cyclic polycondensation of a tricarboxylic acid, a diamine and a triamine, and the like.

[0092] Furthermore, the acyclic amide oligomer may be an amide oligomer formed by acyclic polycondensation of a monocarboxylic acid and a diamine and / or triamine, or an amide oligomer formed by acyclic polycondensation of a dicarboxylic acid and / or tricarboxylic acid and a monoamine. When an amide oligomer contains a monocarboxylic acid or a monoamine, the monocarboxylic acid or monoamine functions as terminal molecules, resulting in an acyclic amide oligomer with a reduced molecular weight. Also, when the acyclic amide oligomer is an amide compound formed by acyclic polycondensation of a dicarboxylic acid and / or tricarboxylic acid and a diamine and / or triamine, it becomes an acyclic polymer. Moreover, acyclic amide oligomers also include amide oligomers formed by acyclic condensation of a monocarboxylic acid and a monoamine.

[0093] Examples of ester-based thixotropes include ester compounds, specifically 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 this embodiment, the other thixotropic agent may be used alone or in combination of two or more. Among the above, the thixotropic agent preferably contains at least one selected from the group consisting of amide-based thixotropic agents and ester-based thixotropic agents, for example, one that contains at least one selected from the group consisting of polyamide and hydrogenated castor oil.

[0096] The content of other thixotropic agents in the flux of this embodiment is preferably 0.5% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 7.5% by mass or less, and even more preferably 2% by mass or more and 5% by mass or less, based on the total mass (100% by mass) of the flux.

[0097] <Activating agent> Examples of activators contained in the flux of this embodiment include organic acids, amine compounds, and halogen compounds. In the flux of this embodiment, two or more activators may be used in combination. It is preferable to use an activator selected from the group consisting of organic acids, amine compounds, and halogen compounds, and it is more preferable to use one that contains at least an organic acid. In this embodiment, the total content of the activator in the flux is preferably 25% by mass or less, more preferably 2.5% by mass or more and 20% by mass or less, and even more preferably 5% by mass or more and 15% by mass or less, based on the total mass (100% by mass) of the flux.

[0098] ≪Organic acid≫ Examples of organic acids include carboxylic acids and organic sulfonic acids. Examples of carboxylic acids 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, isoperargonic acid, capric acid, caproleic acid, lauric acid (dodecanoic acid), undecanoic acid, lindelic acid, tridecanoic acid, myristoleic acid, pentadecanoic acid, isopalmitic acid, palmitoleic acid, hyragonic acid, hydrocarpic acid, margaric acid, isostearic acid, elaidic acid, petroseric acid, molocinic acid, eleostearic acid, taliric acid, vaccenic acid, liminoleic acid, vernolic acid, sterkric 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, 3-hydroxypicolinic acid, etc. 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, dodecanediic acid, eicosanedioic acid, o-phthalic acid, m-phthalic acid (isophthalic acid), and p-phthalic acid (terephthalic acid).

[0100] Furthermore, examples of carboxylic acids 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, isocitric acid, malic acid, and tartaric acid; dimer acid, trimer acid, hydrogenated dimer acid (a hydrogenated product of dimer acid), and hydrogenated trimer acid (a hydrogenated product of trimer acid).

[0101] Examples of organic sulfonic acids include aliphatic sulfonic acids and aromatic sulfonic acids. Examples of aliphatic sulfonic acids include alkanesulfonic acids and alkanolsulfonic acids.

[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-naphthalene sulfonic acid, 2-naphthalene sulfonic acid, p-toluenesulfonic acid, xylene sulfonic acid, p-phenol sulfonic acid, cresol sulfonic acid, sulfosalicylic acid, nitrobenzenesulfonic acid, sulfobenzoic acid, and diphenylamine-4-sulfonic acid.

[0103] When using organic acids as activators, 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 dicarboxylic acids, and more preferably 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 organic acids in the flux of this embodiment is preferably 15% by mass or less, more preferably 1% by mass or more and 13% by mass or less, and even more preferably 2.5% by mass or more and 12.5% ​​by mass or less, based on the total mass (100% by mass) of the flux.

[0104] ≪Amine Compounds≫ Examples of amine compounds include rosinamines, azoles, guanidines, alkylamine compounds, and amino alcohol compounds. Examples of rosinamines include those exemplified in the section on <rosin> above.

[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, and 1-ben. Zyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 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')]- Tyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanurate adduct, 2-phenylimidazole isocyanurate 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 Examples include triazole compounds such as N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole, 2,2'-[[(methyl-1H-benzotriazole-1-yl)methyl]imino]bisethanol, 1-(1',2'-dicarboxyethyl)benzotriazole, 1-(2,3-dicarboxypropyl)benzotriazole, 1-[(2-ethylhexylamino)methyl]benzotriazole, 2,6-bis[(1H-benzotriazole-1-yl)methyl]-4-methylphenol, and 5-methylbenzotriazole; triazine 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 alkylamine compounds include ethylamine, triethylamine, ethylenediamine, triethylenetetramine, cyclohexylamine, hexadecylamine, and stearylamine.

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

[0109] When using amine compounds as activators, one compound may be used alone, or two or more compounds may be used in combination. The amine compound content in the flux of this embodiment is preferably 5% by mass or less, more preferably 0.5% by mass or more and 4% by mass or less, and even more preferably 1% by mass or more and 3% by mass or less, based on the total mass (100% by mass) of the flux.

[0110] ≪Halogen compounds≫ Examples of halogen compounds include amine hydrohalides and organic halogen compounds other than amine hydrohalides.

[0111] Amine hydrohalides are compounds formed by reacting an amine with a hydrogen halide. Examples of amines include aliphatic amines, azoles, and guanidines. Examples of hydrogen halides include chlorine, bromine, and iodine hydrides. Examples of aliphatic amines include ethylamine, diethylamine, triethylamine, and ethylenediamine. Examples of guanidines and azoles are those exemplified in the description of amines, which will be discussed later.

[0112] Examples of organic halogen compounds other than amine hydrohalides include halogenated aliphatic compounds. Halogenated aliphatic compounds are those in which some or all of the hydrogen atoms constituting the aliphatic hydrocarbon group are 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 halogen compounds are used as activators, one type may be used alone, or two or more types may be used in combination. Among halogen compounds, halogenated aliphatic compounds may be used, and halogenated aliphatic alcohols are preferred. The halogen compound content in the flux of this embodiment is preferably 5% by mass or less, more preferably 0.5% by mass or more and 4% by mass or less, and even more preferably 1% by mass or more and 2.5% by mass or less, based on the total mass (100% by mass) of the flux.

[0114] <Other ingredients> In addition to the resin, solvent, thixotropic agent, and activator described above, the flux of this embodiment may contain other components as needed. Other components include, for example, metal deactivators, surfactants, antioxidants (e.g., hindered phenol antioxidants), silane coupling agents, and colorants.

[0115] ≪Metal deactivator≫ Examples of metal deactivators include hindered phenol compounds and nitrogen compounds. In this context, "metal deactivator" refers to a compound that has the property of preventing metal degradation upon contact with certain compounds. Hindered phenol compounds are phenol compounds that have a bulky substituent (for example, a branched or cyclic alkyl group such as a t-butyl group) at at least one of the ortho positions of the phenol. Examples of nitrogen compounds used as metal deactivators include hydrazide-based nitrogen compounds, amide-based nitrogen compounds, triazole-based nitrogen compounds, and melamine-based nitrogen compounds.

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

[0117] As described above, the flux of this embodiment contains a resin, a solvent, a compound represented by the general formula (T-0) (compound (T0)), and an activator. By employing compound (T0), which has an ester bond (-CO-O-) between a hydroxyl group (-OH) derived from 12-hydroxystearic acid and a carboxyl group (-COOH) derived from 12-hydroxystearic acid in its molecule, although the reason is unclear, this flux enhances the effect of suppressing the occurrence of HiP (high-intensity pin placement) in the mounting of BGA components and the like.

[0118] The flux of the preferred embodiment (1) further contains, in addition to compound (T0), a compound represented by general formula (T-1), i.e., a compound (T1) having two 12-hydroxyoctadecanoyl groups via an alkylene diimino group (-NH-(CH2)q-NH-) in its molecule. According to the flux of this preferred embodiment (1), the effect of suppressing HiP generation in the mounting of BGA components and the like can be further enhanced.

[0119] Alternatively, the flux of the preferred embodiment (2) further contains, in addition to compounds (T0) and (T1), a compound represented by general formula (T-2), namely, a compound (T2) having one 12-hydroxyoctadecanoyl group and an acyl group (RC(=O)-) via an alkylene diimino group (-NH-(CH2)r-NH-) within its molecule. The flux of this preferred embodiment (2) further enhances the effect of suppressing HiP generation during the mounting of BGA components and the like.

[0120] Furthermore, the flux of the above embodiment can suppress the generation of HiP (High-Intensity Plasma) and reduce voids during the mounting of BGA components and the like.

[0121] (Solder paste) One embodiment of the solder paste according to the second embodiment contains the flux of the above-described embodiment and solder powder. Such solder paste can be prepared by mixing the flux of the above-described embodiment and solder powder using a known method. As the solder metal constituting the solder powder, solder alloys of known compositions can be used. The solder alloy may be a solder of elemental Sn, or a solder alloy of Sn-Ag, Sn-Cu, Sn-Ag-Cu, Sn-Bi, Sn-In, etc., or a solder alloy to which Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, P, etc. are added. The solder alloy may be a Sn-Pb system, or a solder alloy in which Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, P, etc. are added to the Sn-Pb system. The solder alloy is preferably one that does not contain Pb, and more preferably one that consists of a solder alloy containing Sn, Ag, and Cu (Sn-Ag-Cu type solder alloy).

[0122] The soldering conditions in the soldering process can be appropriately set according to the melting point of the solder alloy. For example, when using a Sn-Ag-Cu solder alloy, the molten solder temperature is preferably 230-280°C, and more preferably 240-260°C. Alternatively, when using a solder alloy containing Sn and Bi (Sn-Bi solder alloy), the molten solder temperature is preferably 170-220°C, and more preferably 180-200°C. In this context, "Sn-Bi solder alloy" refers to a solder alloy whose main components are Sn and Bi. As an example, this refers to a solder alloy in which the combined mass of Sn and Bi accounts for 90% or more of the total mass of the solder alloy, and the mass of Bi accounts for 30-65% of the total mass of the solder alloy.

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

[0124] As described above, the solder paste of this embodiment uses the flux of the above-described embodiment, thus enhancing the effect of suppressing the occurrence of hi-p (High-Intensity Plating) defects. The solder paste of this embodiment is particularly suitable for soldering surface mount components such as BGAs and CSPs, which are prone to high-impact (HiP) soldering.

[0125] (Method of manufacturing the joint) One embodiment of the manufacturing method for a joint according to the third aspect is a method that includes the step of obtaining a joint by soldering a component and a substrate. In this manufacturing method for a joint, reflow is performed using the solder paste according to the second aspect described above during the soldering. The following describes one embodiment of a method for manufacturing such a jointed body. The method for manufacturing a bonded body according to this embodiment includes, in this order, a solder paste application step, a component mounting step, and a reflow step.

[0126] [Solder paste application process] In the solder paste application process, the solder paste according to the second embodiment is applied to the surface of the substrate. Examples of substrates include printed circuit boards and wafers. Methods for applying solder paste include, for example, printing the solder paste using a mask with openings, dispensing the solder paste using a dispenser, and transferring the solder paste using a probe pin.

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

[0128] [Reflow Process] The atmosphere during the reflow process may be, for example, a nitrogen gas atmosphere, a reducing gas atmosphere, or an atmospheric atmosphere. The reducing gas atmosphere may be formed, for example, by volatilizing a reducing compound in a reflow oven, or by supplying a reducing gas obtained by passing nitrogen through a liquid reducing compound to the reflow oven. Formic acid is preferred as the reducing compound. Reflow soldering in an atmospheric environment (air reflow) generally refers to soldering in heated air (approximately 80 vol% nitrogen and 20 vol% oxygen).

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

[0130] The reflow process may include a preheating step before the main heating step. The preheating process involves heating the circuit board after component mounting in a reflow oven 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] As described above, the method for manufacturing a bonded body according to this embodiment employs a solder paste containing the flux of this embodiment, thereby suppressing the occurrence of pitting defects (HiP) at the joint between the component and the substrate, and enabling the manufacture of a highly reliable bonded body. In particular, this method for manufacturing a bonded body is useful as a method for manufacturing a bonded body to which surface mount components such as BGAs and CSPs 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 1-65, Comparative Examples 1-7) Each flux for the examples and comparative examples was prepared by mixing the components to achieve the compositions shown in Tables 1 to 11.

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

[0135] ·resin Rosin and copolymer were used. For the rosin used, acrylic acid-modified hydrogenated rosin, hydrogenated rosin, and polymerized rosin were used, respectively. Ethylene / acrylic acid copolymer was used as the 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 agents Bisamide, hydrogenated castor oil, and polyamide (saturated fatty acid polyamide, melting point below 200°C) were used.

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

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

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

[0141] [ka]

[0142] Compounds represented by p=6 in the general formula (T-0) Compounds represented by p=2 in the general formula (T-0) Compounds represented by p=8 in the general formula (T-0)

[0143] • Activating agent 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, respectively. 1,2,3-benzotriazole was used as the amine compound. The halogen compound used was trans-2,3-dibromo-2-butene-1,4-diol.

[0144] ·others A hindered phenol antioxidant (product name IRGANOX 245, manufactured by BASF Japan) was used as an antioxidant.

[0145] <Preparation of Solder Paste> Solder pastes were prepared by mixing each of the fluxes described above in the examples and comparative examples with the solder powders listed below. In all of the prepared solder pastes, the flux content was 11% by mass and the solder powder content was 89% by mass.

[0146] Solder powder: A powder consisting of a solder alloy with 0.5% by mass of Cu, 3.0% by mass of Ag, and the remainder being 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 such that it satisfies symbol 5 in the powder size classification (Table 2) of JIS Z 3284-1:2014 (particle size distribution).

[0147] <Rating> The effectiveness of suppressing the occurrence of pillow defects (HiP) was evaluated as shown below. The evaluation results are shown in Tables 1 to 11.

[0148] [Evaluation of the ability to suppress the occurrence of pillow malformation (HiP)] The following printed circuit boards and BGA components were used. Printed circuit board: Material FR-4, thickness 0.8mm, land diameter 0.24mm, pad diameter 300μm, surface treatment Cu-OSP BGA component: 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, BGA bump (I / O) count 432 x BGA component count 3 = 1296

[0149] Heat treatment: The BGA components were subjected to a heat treatment at 85°C / 85% RH for 24 hours, followed by a further heat treatment at 125°C for 1 hour.

[0150] Solder paste was printed onto a printed circuit board using a 0.08 mm thick metal mask. The heat-treated BGA components were then mounted on top of this. After that, reflow soldering (air reflow) was performed in an atmospheric environment. The reflow conditions (reflow profile) involved preheating to 130-220°C for 90 seconds, followed by continuous heating at 220°C or higher for 42 seconds. The peak temperature during this process was 242°C. The reflow profile is shown in Figure 1.

[0151] After reflow soldering, the fusion state of each BGA ball in the BGA Bump with the solder paste was checked, and the number of BGA balls that did not fuse properly and resulted in a poor solder joint was counted. The suppression of HiP (High-Intensity Plasma) generation was then evaluated based on the following criteria. Ranks 1-4 were considered pass, and rank 5 was considered fail. Judgment criteria Rank 1: 0 items Rank 2: 1-3 items Rank 3: 4-7 items Rank 4: 8-10 items Rank 5: 11 or more

[0152] [Table 1]

[0153] Table 1 shows that when the flux of Comparative Example 1, which contains a compound represented by general formula (T-1) as a thixotropic agent, was used, the evaluation of its ability to suppress HiP generation was inferior. On the other hand, when the flux of Example 1 was used, which employed the compound represented by general formula (T-0) instead of the compound represented by general formula (T-1), the number of BGA balls with pillow defects decreased compared to when the flux of Comparative Example 1 was used, and the effect of suppressing HiP generation improved.

[0154] Furthermore, when using the flux of Example 5, which combines the compound represented by general formula (T-0) and the compound represented by general formula (T-1), the number of BGA balls with pillow defects was significantly reduced, and the effect of suppressing HiP generation was dramatically improved.

[0155] [Table 2]

[0156] [Table 3]

[0157] The results shown in Tables 2 and 3 confirm that the effect of suppressing HiP generation is enhanced when the mass ratio of the compound represented by general formula (T-1) to the compound represented by general formula (T-0) is between 4 and 40. Furthermore, as can be seen in Table 3, a comparison between Comparative Example 1 and Examples 5-13 confirms that including 0.1% by mass or more of the compound represented by general formula (T-0) relative to the total mass (100% by mass) of the flux makes it easier to obtain the effect of suppressing HiP generation.

[0158] [Table 4]

[0159] Table 4 shows that, by comparing Examples 8, 14, and 19 with Examples 15-18, it can be confirmed that by using the compound represented by general formula (T-2) in combination with the compound represented by general formula (T-0) and the compound represented by general formula (T-1), it is possible to reduce the number of BGA balls with pillow defects to zero, and the effect of suppressing HiP generation becomes even easier to obtain.

[0160] [Table 5]

[0161] Table 5 shows that, by comparing Examples 8, 20, and 21 with Examples 22-24, it can be confirmed that by using the compound represented by general formula (T-2) in combination with the compound represented by general formula (T-0) and the compound represented by general formula (T-1), it is possible to reduce the number of BGA balls with pillow defects to zero, and the effect of suppressing HiP generation becomes even easier to obtain.

[0162] [Table 6]

[0163] [Table 7]

[0164] [Table 8]

[0165] [Table 9]

[0166] [Table 10]

[0167] [Table 11]

[0168] Tables 6-11 show that when the fluxes of Examples 8 and 25-65 to which the present invention was applied were used, the evaluation results were rank 3, 2, or 1 in all cases, confirming that the effect of suppressing HiP generation was good.

[0169] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Additions, omissions, substitutions, and other modifications to the configuration are possible without departing from the spirit of the present invention. The present invention is not limited by the foregoing description and is limited only by the appended claims.

Claims

1. It contains resin, solvent, thixotropic agent and activator, A flux comprising a compound represented by the following general formula (T-0) as the thixotropic agent. 【Chemistry 1】 [In the formula, p is an integer between 2 and 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 comprises a compound represented by the following general formula (T-1). 【Chemistry 2】 [In the formula, q is an integer between 2 and 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 comprises a compound represented by the following general formula (T-2). 【Transformation 3】 [In the formula, r is an integer between 2 and 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% by mass or more and 1% by mass or less, based on the total mass (100% by mass) of the flux.

9. The mixing ratio of the compound represented by the general formula (T-0) and the compound represented by the general formula (T-1) is, Compounds represented by general formula (T-1) / Compounds 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. The compound represented by the general formula (T-0), The compound represented by the general formula (T-1) above, The compound represented by the general formula (T-2) above, The flux according to claim 5, wherein the total content of is 1% by mass or more and 10% by mass or less based on the total mass of the flux (100% by mass).

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

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