Flux and method for manufacturing joined body

Abstract

Provided are: a flux capable of increasing the joining strength of a solder joint part without using an underfill; and a method for manufacturing a joined body using said flux.　According to the present invention, a flux containing an epoxy resin, a curing agent for curing the epoxy resin, and an activator is adopted. The mass ratio represented by the epoxy resin / curing agent is at least 5. The flux contains a coupling agent, and the coupling agent contains a compound represented by general formula (C-1). The content of the epoxy resin is 50-95 mass% with respect to the total mass of the flux. In the formula, Rc1 represents a C1-C6 alkyl group or a hydrogen atom. Rc2 represents a C1-C10 alkylene group or a single bond. A methylene group constituting the alkylene group may be substituted with an oxygen atom. Rc3 represents an epoxy group-containing group or a thiol group. nc is an integer of 1-3. mc is an integer of 0-2. nc+mc=3.

Description

Flux and method for manufacturing joint body

[0001] The present invention relates to a method for producing a flux and a joint body.

[0002] Fixing components to a board and electrically connecting the components to the board are generally performed by soldering, which uses flux, solder powder, and a solder paste made by mixing the flux and solder powder.

[0003] Flux chemically removes metal oxides present in the solder and the metal surfaces of the objects being soldered, allowing the movement of metal elements at the interface between the two. Therefore, when soldering is performed using flux, an intermetallic compound is formed between the two, resulting in a strong bond.

[0004] In soldering using solder paste, the solder paste is first printed on a board, components are then mounted, and the board with the components mounted is heated in a heating furnace called a reflow furnace, which melts the solder powder contained in the solder paste and solders the components to the board, resulting in a bonded assembly.

[0005] When joining a ball grid array with solder balls mounted thereon to a substrate, in order to increase the joining strength, the ball grid array and the substrate are soldered together, and then an underfill is filled around the joining point, and the underfill is then cured to fix the ball grid array to the substrate. For example, Patent Document 1 describes a flux that is compatible with the underfill and contains a thermosetting resin.

[0006] JP 2017-056485 A

[0007] When the thermosetting flux and underfill described in Patent Document 1 are used, a step of filling the underfill around the joint and a step of hardening the underfill are required, which reduces the manufacturing efficiency of the joint.

[0008] Therefore, the inventors investigated soldering using a flux containing epoxy resin without using an underfill, and found that with conventional flux containing epoxy resin, there is a problem in that the adhesion between the solder and the flux at the joint after reflow is low, resulting in a decrease in joint strength.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a flux that can increase the bonding strength of a solder joint without using an underfill, and a method for manufacturing a bonded body using the flux.

[0010] The present invention includes the following aspects: [1] A flux containing an epoxy resin, a curing agent for curing the epoxy resin, and an activator, wherein the mass ratio of the content of the epoxy resin to the content of the curing agent is 5 or more as a mass ratio expressed as epoxy resin / curing agent, the flux further contains a coupling agent, the coupling agent includes a compound having a methoxy group, the compound is a compound expressed by the following general formula (C-1), and the content of the epoxy resin is 50 mass % or more and 95 mass % or less with respect to the total mass of the flux.

[0011] [In the formula, R ｃ１ represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. ｃ２ represents an alkylene group having 1 to 10 carbon atoms or a single bond. However, the methylene group constituting the alkylene group may be substituted with an oxygen atom. R ｃ３ represents an epoxy group-containing group or a thiol group. ｃ is an integer from 1 to 3. ｃ is an integer from 0 to 2. ｃ +m ｃ = 3.]

[0012] [2] The flux according to [1], wherein the epoxy resin contains a bisphenol-type epoxy resin. [3] The flux according to [1] or [2], wherein the epoxy resin contains a naphthalene-type epoxy resin. [4] The flux according to [1], wherein the epoxy resin contains a bisphenol-type epoxy resin and a naphthalene-type epoxy resin, and wherein the mass ratio of the bisphenol-type epoxy resin content to the naphthalene-type epoxy resin content, expressed as a mass ratio of bisphenol-type epoxy resin / naphthalene-type epoxy resin, is 0.70 or more and 1.5 or less. [5] The flux according to any one of [1] to [4], wherein the curing agent contains an amine having a melting point of 190°C or more. [6] The flux according to any one of [1] to [5], wherein the curing agent contains guanamines. [7] The flux according to [1], further containing an activator. [8] The flux according to any one of [1] to [7], wherein the flux is used to join a component having solder balls to a substrate. [9] A method for manufacturing a bonded body, comprising the steps of: treating solder balls of a component having solder balls with the flux according to any one of [1] to [7]; and soldering the component having solder balls to a substrate to obtain a bonded body.

[0013] The present invention can also be said to include the following aspects. [P1] A flux containing an epoxy resin and a curing agent, wherein the mass ratio of the epoxy resin content to the curing agent content is 5 or more, expressed as the mass ratio of epoxy resin / curing agent, and the flux further contains a coupling agent, wherein the coupling agent includes a compound having a methoxy group. [P2] The flux according to [P1], wherein the epoxy resin includes a bisphenol-type epoxy resin. [P3] The flux according to [P1] or [P2], wherein the epoxy resin includes a naphthalene-type epoxy resin. [P4] The flux according to [P1], wherein the epoxy resin includes a bisphenol-type epoxy resin and a naphthalene-type epoxy resin, wherein the mass ratio of the bisphenol-type epoxy resin content to the naphthalene-type epoxy resin content is 0.70 or more and 1.5 or less, expressed as the mass ratio of bisphenol-type epoxy resin / naphthalene-type epoxy resin. [P5] The flux according to any of [P1] to [P4], wherein the curing agent includes an amine having a melting point of 190°C or higher. [P6] The flux according to any one of [P1] to [P5], wherein the curing agent contains a guanamine. [P7] The flux according to any one of [P1] to [P6], further containing an activator. [P8] The flux according to any one of [P1] to [P7], which is used for joining a component having solder balls to a substrate. [P9] A method for producing a joined body, comprising the steps of treating the solder balls of a component having solder balls with the flux according to any one of [P1] to [P7], and soldering the component having solder balls to a substrate to obtain a joined body.

[0014] According to the present invention, it is possible to provide a flux that can increase the bonding strength of a solder joint without using an underfill, and a method for manufacturing a bonded body using the flux.

[0015] 1 is a diagram showing a schematic diagram of a process for producing a flux film 3 using a squeegee 1; FIG. 2 is a diagram showing a process for contacting a solder ball 4 of a component 6 with the flux film 3; FIG. 3 is a diagram showing a process for placing a component 6 on a substrate 7; and FIG. 4 is a diagram showing a process for joining a component 6 and a substrate 7 to obtain a joined body 10.

[0016] In this specification, the terms "comprise" and "containing" are concepts that encompass all of "comprise," "consist essentially of," and "consist of." "Comprise" and "contain" can mean "consist essentially of," or "consist of."

[0017] In this specification, when the content of a component in a flux is specified as mass % relative to the total mass of the flux, the total mass % of the flux is 100 mass %.

[0018] (Flux) One embodiment of the flux according to the first aspect will be described. The flux according to this embodiment contains an epoxy resin and a curing agent. The mass ratio of the epoxy resin content to the curing agent content, expressed as the mass ratio of epoxy resin / curing agent, is 5 or more. The flux according to this embodiment further contains a coupling agent. The coupling agent includes a compound having a methoxy group.

[0019] The flux according to this embodiment contains an epoxy resin, a curing agent, and a coupling agent containing a compound having a methoxy group, and therefore can increase the bonding strength of the solder joints without using an underfill.

[0020] The flux according to this embodiment is suitable for use in a process for soldering a component having solder balls to a substrate to obtain a bonded assembly. This bonded assembly is manufactured by the process illustrated in FIGS. 1 to 4 . First, as illustrated in FIG. 1 , a flux film 3 is formed by spreading flux 3 on a table 2 using a squeegee 1. Next, as illustrated in FIG. 2 , a component 6 having solder balls 4 bonded to a chip 5 is prepared, and the solder balls 4 of the component 6 are brought into contact with the flux film 3. Next, as illustrated in FIG. 3 , the electronic component 6 having the solder balls 4 treated with the flux 3 is placed on a substrate 7. Next, as illustrated in FIG. 4 , the substrate 7 on which the electronic component 6 is placed is subjected to reflow soldering to obtain a bonded assembly 10 in which the electronic component 6 is bonded by the solder balls 4 and flux residue 9.

[0021] In the process of producing the flux film 3, it is necessary that the flux can be used continuously even after squeegeeing for a long period of time. The flux according to this embodiment can be used continuously even after squeegeeing for a long period of time, and is suitable for use in mounting solder balls on a chip.

[0022] <Epoxy Resin> Examples of epoxy resins include bisphenol-type epoxy resins, naphthalene-type epoxy resins, novolac-type epoxy resins, aliphatic epoxy resins, and alicyclic epoxy resins.

[0023] The bisphenol-type epoxy resin may be any epoxy resin having a structural unit containing a bisphenol skeleton. Examples of bisphenol-type resins include bisphenol A, bisphenol AP, bisphenol AF, bisphenol B, bisphenol BP, bisphenol C, bisphenol E, bisphenol F, bisphenol G, bisphenol M, bisphenol S, bisphenol P, bisphenol PH, bisphenol TMC, and bisphenol Z. One type of bisphenol-type epoxy resin may be used alone, or two or more types may be used in combination.

[0024] The naphthalene type epoxy resin may be any epoxy resin having a structural unit containing a naphthalene skeleton, such as 1,6-diglycidyloxynaphthalene, 1,3-diglycidyloxynaphthalene, 1,4-diglycidyloxynaphthalene, 1,5-diglycidyloxynaphthalene, 2,3-diglycidyloxynaphthalene, 2,6-diglycidyloxynaphthalene, 2,7-diglycidyloxynaphthalene, 1-(2,7-diglycidyloxynaphthyl)-1'-(2'-glycidyloxy) Examples of the naphthalene-type epoxy resin include naphthalene-type epoxy resins such as 1,1'-bis(2,7-diglycidyloxynaphthyl)methane, 1,1'-bis(2,7-diglycidyloxynaphthyl)methane, 1,1'-bis(2,7-diglycidyloxynaphthyl)-1-phenyl-methane, 2,2'-glycidyloxy-1,1'-binaphthalene, 2,2',7-triglycidyloxy-1,1'-binaphthalene, and 2,2',7,7'-tetraglycidyloxy-1,1'-binaphthalene. One type of naphthalene-type epoxy resin may be used alone, or two or more types may be used in combination.

[0025] The novolac epoxy resin may be any epoxy resin having a structural unit containing a novolac skeleton, and examples thereof include phenol novolac epoxy resin, cresol novolac epoxy resin, bisphenol A novolac epoxy resin, and bisphenol F novolac epoxy resin.

[0026] The epoxy resin may be used alone or in combination of two or more. The epoxy resin preferably contains one or more selected from the group consisting of bisphenol-type epoxy resins and naphthalene-type epoxy resins, and more preferably contains bisphenol-type epoxy resins and naphthalene-type epoxy resins. When the epoxy resin contains a bisphenol-type epoxy resin, it becomes easier to prevent the viscosity of the flux from becoming too high, making it easier to extend the continuous use time of the flux. When the epoxy resin contains a naphthalene-type epoxy resin, it becomes easier to increase the glass transition temperature.

[0027] The polystyrene-equivalent weight average molecular weight of the epoxy resin is preferably 200 to 500, more preferably 260 to 400. The epoxy equivalent of the epoxy resin is preferably 100 to 250 g / eq., more preferably 130 to 200 g / eq.

[0028] The content of the epoxy resin in the flux according to the present embodiment is preferably 50% by mass or more and 95% by mass or less, more preferably 60% by mass or more and 90% by mass or less, and even more preferably 70% by mass or more and 90% by mass or less, based on the total mass of the flux. By making the content of the epoxy resin equal to or more than the lower limit of the above range, the strength of the solder joint can be easily increased.

[0029] When the flux according to the present embodiment contains a bisphenol-type epoxy resin and a naphthalene-type epoxy resin, the mass ratio of the bisphenol-type epoxy resin content to the naphthalene-type epoxy resin content, expressed as the mass ratio of bisphenol-type epoxy resin / naphthalene-type epoxy resin, may be 0.01 to 100, preferably 0.10 to 4, more preferably 0.70 to 1.5, and may be 0.73 to 1.29. When the mass ratio of bisphenol-type epoxy resin / naphthalene-type epoxy resin is equal to or greater than the lower limit of the above range, the viscosity of the flux can be prevented from becoming too high, and the continuous use time of the flux can be extended. When the mass ratio is equal to or less than the upper limit of the above range, the glass transition temperature can be increased.

[0030] <Curing Agent> The curing agent contained in the flux according to this embodiment is a compound that has the effect of curing the epoxy resin. The curing agent is not particularly limited as long as the effects of the present invention are achieved, and examples thereof include guanamines, imidazoles, acid anhydrides, guanidines, aminoguanidines, ureas, modified polyamines and their derivatives, dicyandiamide, boron trifluoride amine complex, organic acid hydrazide, melamine, amine adduct curing agents, vinyl ether block carboxylic acid, onium salt, isocyanate curing agents, and phenols.

[0031] Examples of guanamines include compounds represented by the following general formula (H-1).

[0032] [In the formula, R ｈ represents an alkyl group, an aryl group, or an aralkyl group.

[0033] In the general formula (H-1), R ｈ In the general formula (H-1), the alkyl group in R is preferably an alkyl group having 1 to 4 carbon atoms. ｈ The aryl group in is preferably a phenyl group.

[0034] The guanamines are preferably one or more selected from the group consisting of benzoguanamine and acetoguanamine.

[0035] The imidazoles may be any compound having a five-membered heterocyclic ring in which the first and third positions of the ring are nitrogen atoms.

[0036] Examples of imidazoles include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, and 1-cyanoethyl. 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline Phosphorus, 2-methylbenzimidazole, 2-octylbenzimidazole, 2-pentylbenzimidazole, 2-(1-ethylpentyl)benzimidazole, 2-nonylbenzimidazole, 2-(4-thiazolyl)benzimidazole, benzimidazole, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2 , 4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, epoxy-imidazole adduct, and the like.

[0037] Examples of acid anhydrides include phthalic anhydride, maleic anhydride, cyclohexanedicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylnadic anhydride, nadic anhydride, glutaric anhydride, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, biphenyltetracarboxylic dianhydride, 3,3',4,4'-methylbicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride, bicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride, ethylene glycol bisanhydrotrimellitate, glycerin bisanhydrotrimellitate monoacetate, and tetrapropenyl succinic anhydride.

[0038] The melting point of the curing agent may be, for example, 150 to 400° C., and is preferably 190° C. or higher, more preferably 200° C. or higher, even more preferably 210° C. or higher, and particularly preferably 220° C. or higher. When the melting point of the curing agent is equal to or higher than the lower limit, excessive reaction between the epoxy resin and the curing agent can be easily suppressed, and the continuous use time can be easily extended.

[0039] As used herein, the melting point refers to the temperature at which a solid melts and becomes liquid. The melting point of the target compound may be, for example, the melting point listed in the "Iwanami Dictionary of Physics and Chemistry, 5th Edition." Alternatively, the melting point of the target compound may be the melting point measured by a method in accordance with JIS K 0064:1992.

[0040] The curing agent is preferably one or more selected from the group consisting of guanamines, imidazoles, and acid anhydrides, more preferably one or more selected from the group consisting of guanamines and imidazoles, and even more preferably guanamines. By containing guanamines in the flux, excessive reaction between the epoxy resin and the curing agent can be easily suppressed, making it easier to extend the continuous use time.

[0041] The content of the hardener in the flux according to the present embodiment is preferably 1 mass % or more and 30 mass % or less, and more preferably 2 mass % or more and 20 mass % or less, relative to the total mass of the flux.

[0042] When the flux according to the present embodiment contains guanamines, the content of guanamines in the flux is preferably 3% by mass to 30% by mass, and more preferably 5% by mass to 20% by mass, relative to the total mass of the flux. When the flux according to the present embodiment contains imidazoles, the content of imidazoles in the flux is preferably 1% by mass to 15% by mass, and more preferably 2% by mass to 10% by mass, relative to the total mass of the flux. When the flux according to the present embodiment contains acid anhydrides, the content of acid anhydrides in the flux is preferably 3% by mass to 30% by mass, and more preferably 5% by mass to 20% by mass, relative to the total mass of the flux.

[0043] In the flux according to this embodiment, the mass ratio of the epoxy resin content to the curing agent content, expressed as the mass ratio of epoxy resin / curing agent, is, for example, from 5 to 50, and preferably is 6 or more. The upper limit of the mass ratio expressed as epoxy resin / curing agent is not particularly limited, but may be, for example, 50 or 30.

[0044] <Specific Coupling Agent> The flux according to this embodiment contains a coupling agent, and the coupling agent includes a specific coupling agent. The specific coupling agent is a compound having a methoxy group. The specific coupling agent is preferably a silane compound. The specific coupling agent preferably has an epoxy group or a thiol group.

[0045] The specific coupling agent is preferably a compound represented by the following general formula (C-1).

[0046] [In the formula, R ｃ１ represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. ｃ２ represents an alkylene group having 1 to 10 carbon atoms or a single bond. However, the methylene group constituting the alkylene group may be substituted with an oxygen atom. R ｃ３ represents an epoxy group-containing group or a thiol group. ｃ is an integer from 1 to 3. ｃis an integer from 0 to 2. ｃ +m ｃ = 3.]

[0047] R ｃ１ The alkyl group in R may be linear or branched. ｃ１ is preferably an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group.

[0048] R ｃ２ The alkylene group in R may be linear or branched. ｃ２ is preferably an alkylene group having 1 to 7 carbon atoms.

[0049] R ｃ３ Examples of the epoxy group-containing group in (1) include a group consisting of only epoxy groups; a group consisting of only alicyclic epoxy groups; and a group having an epoxy group or alicyclic epoxy group and a divalent linking group. An alicyclic epoxy group is an alicyclic group having an oxacyclopropane structure, which is a three-membered ring ether, specifically a group having an alicyclic group and an oxacyclopropane structure. The alicyclic group that forms the basic skeleton of the alicyclic epoxy group may be monocyclic or polycyclic. Examples of monocyclic alicyclic groups include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of polycyclic alicyclic groups include a norbornyl group, an isobornyl group, a tricyclononyl group, a tricyclodecyl group, and a tetracyclododecyl group. The hydrogen atoms of these alicyclic groups may be substituted with an alkyl group, an alkoxy group, a hydroxyl group, or the like. In the case of a group having an epoxy group or an alicyclic epoxy group and a divalent linking group, R ｃ２ Preferably, the epoxy group or alicyclic epoxy group is bonded via a divalent linking group bonded to

[0050] In the general formula (C-1), preferably, R ｃ１ is an alkyl group having 1 to 4 carbon atoms; R ｃ２ is an alkylene group having 1 to 7 carbon atoms; R ｃ３ is an epoxy group-containing group or a thiol group; nｃ is an integer of 2 or 3. In the general formula (C-1), R ｃ１ is a methyl group; R ｃ２ is an alkylene group having 1 to 7 carbon atoms; R ｃ３ is a group consisting of only epoxy groups, a group consisting of only alicyclic epoxy groups, or a thiol group; n ｃ is an integer of 2 or 3.

[0051] The specific coupling agent is preferably a compound represented by the following chemical formulas (C-1-1) to (C-1-4).

[0052]

[0053] The content of the specific coupling agent in the flux is preferably 0.1 to 5 mass %, more preferably 0.3 to 3 mass %, and even more preferably 0.5 to 2 mass %, relative to the total mass of the flux.

[0054] <Other Components> The flux according to the present embodiment may contain other components as needed in addition to the epoxy resin, curing agent, and coupling agent. Examples of other components include an activator, a thixotropic agent, a solvent, resin components other than the epoxy resin (other resins), a metal deactivator, an antioxidant, a surfactant, and a colorant.

[0055] The flux according to the present embodiment may comprise one or more components selected from the group consisting of an epoxy resin, a curing agent, an activator, a coupling agent, and optionally, a thixotropic agent, a solvent, other resins, a metal deactivator, an antioxidant, a surfactant, and a colorant. Each component constituting the group of optional other components can be selected as desired.

[0056] <<Activator>> Examples of the activator include organic acids, amines, halogen compounds, and organic phosphorus compounds.

[0057] Organic Acids Examples of organic acids include carboxylic acids and organic sulfonic acids. Examples of carboxylic acids include aliphatic carboxylic acids, aromatic carboxylic acids, tricarboxylic acids, and hydroxycarboxylic acids. Examples of aliphatic carboxylic acids include aliphatic monocarboxylic acids and aliphatic dicarboxylic acids.

[0058] Examples of aliphatic monocarboxylic acids include caproic 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, talic acid, vaccenic acid, ricinoleic acid, vernolic acid, sterculic acid, nonadecanoic acid, eicosanoic acid, stearic acid, 12-hydroxystearic acid, oleic acid, linoleic acid, linolenic acid, myristic acid, glycolic acid, and thioglycolic acid.

[0059] Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, eicosanedioic acid, citraconic acid, diglycolic acid, tartaric acid, 2,4-diethylglutaric acid, etc. Examples of aromatic carboxylic acids include aromatic monocarboxylic acids such as benzoic acid, 3-hydroxybenzoic acid, salicylic acid, picolinic acid, p-anisic acid, m-anisic acid, o-anisic acid, parahydroxyphenylacetic acid, and 2-quinolinecarboxylic acid, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, phenylsuccinic acid, dipicolinic acid, and dibutylaniline diglycolic acid, picolinic acid, dipicolinic acid, and 3-hydroxypicolinic acid, etc.

[0060] An example of the tricarboxylic acid is citric acid.

[0061] Examples of hydroxycarboxylic acids include 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butanoic acid, citric acid, isocitric acid, malic acid, and tartaric acid.

[0062] Examples of the carboxylic acid include tris(2-carboxyethyl) isocyanurate and 1,3-cyclohexanedicarboxylic acid.

[0063] The carboxylic acid may be a polybasic carboxylic acid, such as a dimer acid, a trimer acid, a hydrogenated dimer acid obtained by adding hydrogen to a dimer acid, or a hydrogenated trimer acid obtained by adding hydrogen to a trimer acid.

[0064] Examples of organic sulfonic acids include aliphatic sulfonic acids, aromatic sulfonic acids, etc. Examples of aliphatic sulfonic acids include alkanesulfonic acids, alkanolsulfonic acids, etc.

[0065] The organic acid may be used alone or in combination of two or more. The organic acid is preferably a carboxylic acid, more preferably a dicarboxylic acid. The dicarboxylic acid is preferably at least one selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and azelaic acid, more preferably at least one selected from the group consisting of glutaric acid, adipic acid, pimelic acid, and suberic acid, and even more preferably at least one selected from the group consisting of glutaric acid, adipic acid, and pimelic acid.

[0066] Amines Examples of amines include azoles (excluding imidazoles that can function as a curing agent), guanidines, amino alcohols, alkylamine compounds, and amine polyoxyalkylene adducts.

[0067] Examples of azoles include 2,4-diamino-6-vinyl-s-triazine, 2,4-diamino-6-vinyl-s-triazine isocyanuric acid adduct, 2,4-diamino-6-methacryloyloxyethyl-s-triazine, 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-octylphenol, octyl-6'-tert-butyl-4'-methyl-2,2'-methylenebisphenol, 1,2,3-benzotriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole, carboxybenzotriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole, 2,2'-[[(methyl-1H-benzotriazol-1-yl)methyl]imino]bisethanol, 1-(1',2'-dicarboxyethyl)benzotriazole, 1-(2,3-dicarboxypropyl)benzotriazole, 1-[(2-ethylhexylamino)methyl]benzotriazole, 2,6-bis[(1H-benzotriazol-1-yl)methyl]-4-methylphenol, 5-methylbenzotriazole, 5-phenyltetrazole, and the like.

[0068] 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.

[0069] Examples of amino alcohols include N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine, N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, 1-amino-2-propanol, bis(2-hydroxypropyl)amine, and tris(2-hydroxypropyl)amine.

[0070] Examples of alkylamine compounds include ethylamine, triethylamine, ethylenediamine, triethylenetetramine, cyclohexylamine, hexadecylamine, and stearylamine.

[0071] Examples of the amine polyoxyalkylene adducts include terminal diamine polyalkylene glycols, aliphatic amine polyoxyalkylene adducts, aromatic amine polyoxyalkylene adducts, polyvalent amine polyoxyalkylene adducts, etc. Examples of the alkylene oxide added to the amine polyoxyalkylene adducts include ethylene oxide, propylene oxide, butylene oxide, etc.

[0072] Diamine-terminated polyalkylene glycols are compounds in which both terminals of a polyalkylene glycol are aminated. Examples of diamine-terminated polyalkylene glycols include diamine-terminated polyethylene glycols, diamine-terminated polypropylene glycols, and diamine-terminated polyethylene glycol-polypropylene glycol copolymers. Examples of diamine-terminated polyethylene glycol-polypropylene glycol copolymers include polyethylene glycol-polypropylene glycol copolymer bis(2-aminopropyl) ether and polyethylene glycol-polypropylene glycol copolymer bis(2-aminoethyl) ether.

[0073] The aliphatic amine polyoxyalkylene adduct, aromatic amine polyoxyalkylene adduct, and polyvalent amine polyoxyalkylene adduct are compounds in which a polyoxyalkylene group is bonded to a nitrogen atom of an amine. Examples of the amine include ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, hexamethylenediamine, diethylenetriamine, laurylamine, stearylamine, oleylamine, tallow amine, hardened tallow amine, tallow propyldiamine, metaxylenediamine, tolylenediamine, paraxylenediamine, phenylenediamine, isophoronediamine, 1,10-decanediamine, 1,12-dodecanediamine, 4,4-diaminodicyclohexylmethane, 4,4-diaminodiphenylmethane, butane-1,1,4,4-tetraamine, and pyrimidine-2,4,5,6-tetraamine.

[0074] Examples of halogen compounds include amine hydrohalides and organic halogen compounds other than amine hydrohalides.

[0075] The activator is preferably an organic acid. One type of activator may be used alone, or two or more types may be used in combination. The content of the activator in the flux is preferably 1% by mass or more and 20% by mass or less, more preferably 2% by mass or more and 15% by mass or less, and even more preferably 3% by mass or more and 10% by mass or less, based on the total mass of the flux.

[0076] <Thixotropic Agent> Examples of the thixotropic agent include ester-based thixotropic agents, amide-based thixotropic agents, and sorbitol-based thixotropic agents.

[0077] Examples of ester-based thixotropic agents include ester compounds, and specific examples include hydrogenated castor oil and ethyl myristate.

[0078] Examples of amide-based thixotropic agents include monoamides, bisamides, 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 (p-toluamide), p-toluenemethane amide, aromatic amide, hexamethylenehydroxystearic acid amide, substituted amide, methylolstearic acid amide, methylol amide, and fatty acid ester amide. Examples of bisamides include ethylenebisfatty acid (fatty acid carbon number: C6 to 24) amide, ethylenebishydroxyfatty acid (fatty acid carbon number: C6 to 24) amide, hexamethylenebisfatty acid (fatty acid carbon number: C6 to 24) amide, hexamethylenebishydroxyfatty acid (fatty acid carbon number: C6 to 24) amide, and aromatic bisamides. 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 acyclic amide oligomers.

[0079] 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 tricarboxylic acid, and a triamine, 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 triamine, and an amide oligomer obtained by cyclic polycondensation of a dicarboxylic acid, a tricarboxylic acid, a diamine, and a triamine.

[0080] The acyclic amide oligomer may be an amide oligomer obtained by acyclic polycondensation of a monocarboxylic acid with a diamine and / or triamine, or an amide oligomer obtained by acyclic polycondensation of a dicarboxylic acid and / or tricarboxylic acid with a monoamine. In the case of an amide oligomer containing a monocarboxylic acid or a monoamine, the monocarboxylic acid or monoamine functions as a terminal molecule, resulting in an acyclic amide oligomer with a reduced molecular weight. Furthermore, when the acyclic amide oligomer is an amide compound obtained by acyclic polycondensation of a dicarboxylic acid and / or tricarboxylic acid with a diamine and / or triamine, it becomes an acyclic high-molecular-weight amide polymer. Furthermore, the acyclic amide oligomer also includes an amide oligomer obtained by acyclic condensation of a monocarboxylic acid with a monoamine.

[0081] 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.

[0082] The thixotropic agent may be used alone or in combination of two or more. The thixotropic agent is preferably one or more selected from the group consisting of ester-based thixotropic agents and amide-based thixotropic agents. The content of the thixotropic agent in the flux is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.3% by mass or more and 5% by mass or less, and even more preferably 0.5% by mass or more and 3% by mass or less, relative to the total mass of the flux.

[0083] The flux according to this embodiment may contain a solvent, or may not contain a solvent, as long as the effects of the present invention are achieved. Examples of the solvent include water, alcohol-based solvents, glycol ether-based solvents, and terpineols.

[0084] Examples of alcohol-based solvents include 2-propanol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-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, and 2-ethyl-2-hydroxypropane. Examples of the hydroxymethyl-1,3-propanediol include 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, 2-methyl-2,4-pentanediol (hexylene glycol), and octanediol.

[0085] Examples of glycol ether solvents include dipropylene glycol monomethyl ether, diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, ethylene glycol monobutyl ether (butyl glycol), ethylene glycol monohexyl ether (hexyl glycol), diethylene glycol monohexyl ether (hexyl diglycol), diethylene glycol dibutyl ether, triethylene glycol monobutyl ether, methylpropylene triglycol, triethylene glycol butyl methyl ether, tetraethylene glycol, tetraethylene glycol dimethyl ether, and tripropylene glycol-n-butyl ether.

[0086] Examples of terpineols include α-terpineol, β-terpineol, γ-terpineol, and terpineol mixtures (that is, mixtures whose main component is α-terpineol and which contain β-terpineol or γ-terpineol).

[0087] The solvent may be used alone or in combination of two or more. The content of the solvent in the flux may be, for example, 0 to 40% by mass, more than 0% by mass and not more than 40% by mass, more than 0% by mass and not more than 30% by mass, more than 0% by mass and not more than 20% by mass, more than 0% by mass and not more than 10% by mass, or more than 0% by mass and not more than 5% by mass, relative to the total mass of the flux.

[0088] <<Resin Components Other Than Epoxy Resin (Other Resins)>> The flux according to the present embodiment may contain resin components other than epoxy resin (other resins) or may not contain other resins, as long as the effects of the present invention are achieved. Examples of other resins include rosin and resins other than rosin.

[0089] In this specification, the term "rosin" includes natural resins containing abietic acid as a main component, including a mixture of abietic acid and its isomers, as well as chemically modified natural resins (sometimes referred to as rosin derivatives). 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, 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, and acid-modified rosin soap.

[0090] Examples of resins other than rosin include terpene resins, modified terpene resins, terpene phenolic resins, modified terpene phenolic resins, styrene resins, modified styrene resins, xylene resins, modified xylene resins, acrylic resins, polyethylene resins, and acrylic-polyethylene copolymer resins. Examples of modified terpene resins include aromatic modified terpene resins, hydrogenated terpene resins, and hydrogenated aromatic modified terpene resins. Examples of modified terpene phenolic resins include hydrogenated terpene phenolic 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.

[0091] The other resins may be used singly or in combination of two or more. The content of the other resins in the flux may be, for example, 0 to 20% by mass, more than 0% by mass and not more than 20% by mass, more than 0% by mass and not more than 10% by mass, more than 0% by mass and not more than 5% by mass, or more than 0% by mass and not more than 3% by mass, relative to the total mass of the flux.

[0092] <<Metal Deactivator>> Examples of metal deactivators include hindered phenol compounds, nitrogen compounds, etc. The term "metal deactivator" used herein refers to a compound that has the ability to prevent metals from deteriorating due to contact with certain compounds.

[0093] 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. The hindered phenol compound is not particularly limited, and examples thereof include bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][ethylenebis(oxyethylene)], N,N'-hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide], 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2'-dihydroxy-3,3'-bis(2-methyl-2-propanol), ... bis(α-methylcyclohexyl)-5,5'-dimethyldiphenylmethane, 2,2'-methylenebis(6-tert-butyl-p-cresol), 2,2'-methylenebis(6-tert-butyl-4-ethylphenol), triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,4-bis(α-methylcyclohexyl)-5,5'-dimethyldiphenylmethane, 2,2'-methylenebis(6-tert-butyl-p-cresol), 2,2'-methylenebis(6-tert-butyl-4-ethylphenol), triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis ... N,N'-Hexamethyl bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), N-octylthio-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine, pentaerythrityl tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2-thio-diethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-Hexamethyl Examples of such compounds include benzenebis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, N,N'-bis[2-[2-(3,5-di-tert-butyl-4-hydroxyphenyl)ethylcarbonyloxy]ethyl]oxamide, and compounds represented by the following chemical formula:

[0094] (wherein Z is an optionally substituted alkylene group. R ８１ and R ８２ R is each independently an optionally substituted alkyl group, aralkyl group, aryl group, heteroaryl group, cycloalkyl group, or heterocycloalkyl group. ８３ and R ８４ are each independently an optionally substituted alkyl group.

[0095] 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.

[0096] The hydrazide nitrogen compound may be any nitrogen compound having a hydrazide skeleton, and examples thereof include dodecanedioic acid bis[N2-(2-hydroxybenzoyl)hydrazide], N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, decanedicarboxylic acid disalicyloylhydrazide, N-salicylidene-N'-salicylhydrazide, m-nitrobenzhydrazide, 3-aminophthalhydrazide, phthalic acid dihydrazide, adipic acid hydrazide, oxalobis(2-hydroxy-5-octylbenzylidenehydrazide), N'-benzoylpyrrolidonecarboxylic acid hydrazide, and N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hydrazine.

[0097] The amide nitrogen compound may be any nitrogen compound having an amide skeleton, and examples thereof include N,N'-bis{2-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxyl]ethyl}oxamide.

[0098] The triazole-based nitrogen compound may be any nitrogen compound having a triazole skeleton, and examples thereof include N-(2H-1,2,4-triazol-5-yl)salicylamide, 3-amino-1,2,4-triazole, and 3-(N-salicyloyl)amino-1,2,4-triazole.

[0099] The melamine-based nitrogen compound may be any nitrogen compound having a melamine skeleton, such as melamine, melamine derivatives, etc. More specific examples include trisaminotriazine, alkylated trisaminotriazine, alkoxyalkylated trisaminotriazine, melamine, alkylated melamine, alkoxyalkylated melamine, N2-butylmelamine, N2,N2-diethylmelamine, N,N,N',N',N'',N''-hexakis(methoxymethyl)melamine, etc.

[0100] The metal deactivator may be used singly or in combination of two or more. The content of the metal deactivator in the flux may be, for example, 0 to 10% by mass, more than 0% by mass and not more than 10% by mass, more than 0% by mass and not more than 5% by mass, more than 0% by mass and not more than 3% by mass, or more than 0% by mass and not more than 1% by mass, relative to the total mass of the flux.

[0101] <Antioxidant> Examples of the antioxidant include hindered phenol-based antioxidants such as 2,2'-dihydroxy-3,3'-bis(α-methylcyclohexyl)-5,5'-dimethyldiphenylmethane.

[0102] The antioxidant may be used alone or in combination of two or more. The content of the antioxidant in the flux may be, for example, 0 to 10% by mass, more than 0% by mass and not more than 10% by mass, more than 0% by mass and not more than 5% by mass, more than 0% by mass and not more than 3% by mass, or more than 0% by mass and not more than 1% by mass, relative to the total mass of the flux.

[0103] <<Surfactants>> Examples of surfactants include nonionic surfactants. Examples of nonionic surfactants include polyoxyalkylene adducts. Examples of alkylene oxides from which polyoxyalkylene adducts are derived include ethylene oxide, propylene oxide, and butylene oxide. Examples of polyoxyalkylene adducts include polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol copolymers, ethylene oxide-resorcinol copolymers, polyoxyalkylene acetylene glycols, polyoxyalkylene glyceryl ethers, polyoxyalkylene alkyl ethers, polyoxyalkylene esters, and polyoxyalkylene alkylamides. Alternatively, examples of nonionic surfactants include polyoxyalkylene adducts of alcohols. Examples of the alcohols include aliphatic alcohols, aromatic alcohols, and polyhydric alcohols.

[0104] The surfactant may be used singly or in combination of two or more. The content of the surfactant in the flux may be, for example, 0 to 20% by mass, more than 0% by mass and not more than 20% by mass, more than 0% by mass and not more than 10% by mass, more than 0% by mass and not more than 5% by mass, or more than 0% by mass and not more than 3% by mass, relative to the total mass of the flux.

[0105] The flux according to the present embodiment described above contains a specific coupling agent having a methoxy group, thereby increasing the joint strength of the solder joint without the use of an underfill. Furthermore, the joint strength is increased even during low-temperature reflow (e.g., 180°C). While the reason for this effect is unclear, it is presumed that the methoxy group of the specific coupling agent adheres to the solder, thereby increasing the adhesion between the solder and the flux, resulting in increased joint strength. The flux according to the present embodiment allows soldering without the process of filling and curing an underfill, thereby contributing to carbon neutrality.

[0106] The flux according to the first aspect is suitably used for joining a component having solder balls to a substrate.

[0107] (Method for manufacturing a bonded body) The method for manufacturing a bonded body according to the second aspect includes the following steps (a) and (b): Step (a): A step of treating solder balls of a component having solder balls with the flux according to the first aspect Step (b): A step of soldering the component having the solder balls to a substrate to obtain a bonded body Hereinafter, one embodiment of the method for manufacturing a bonded body according to the second aspect will be described.

[0108] <Step (a)> In step (a), the solder balls of a component having solder balls are treated with the flux according to the first aspect. An example of a component having solder balls is a ball grid array. As described above with reference to FIG. 1, the solder balls may be treated with the flux in the following manner.

[0109] As illustrated in Fig. 1, first, a flux 3 is spread on a table 2 using a squeegee 1 to form a flux film 3. Next, as shown in Fig. 2, the flux film 3 is brought into contact with solder balls 4 of a component 6.

[0110] The solder alloy used as the raw material for the solder balls can be any solder alloy with a known composition. Examples of solder alloys include a solder alloy containing only Sn, an Sn-based solder alloy, and an Sn-Bi-based solder alloy. An Sn-based solder alloy is a solder alloy produced by adding one or more elements selected from the group consisting of Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, Pb, and P to Sn. Elements other than Sn contained in the Sn-based solder alloy can be selected arbitrarily.

[0111] For example, 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 to which Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, or P has been added. Alternatively, the solder alloy may be a Sn—Pb solder alloy or a Sn—Pb solder alloy to which Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, or P has been added. Preferably, the solder alloy does not contain Pb.

[0112] <Step (b)> In step (b), the component having the flux-treated solder balls obtained in step (a) is soldered to a substrate to obtain a bonded assembly.

[0113] In step (b), a component 6 having solder balls 4 bonded to a chip 5 is prepared, and as illustrated in FIG. 3 , the component 6 having the solder balls 4 treated with flux 3 is placed on a substrate 7. Next, the substrate 7 on which the component 6 is placed is heated, thereby bonding the solder balls 4 of the component 6 to the electrodes 8 of the substrate 7. As a result, a bonded body 10 is obtained in which the component 6 and the substrate 7 are bonded via the solder balls 4 and the flux residue 9. The heating temperature for the component and the substrate is preferably 235 to 270°C, and more preferably 240 to 260°C.

[0114] According to the method for producing a bonded body according to the present embodiment described above, a bonded body having increased bonding strength can be obtained because the flux according to the first aspect is used.

[0115] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

[0116] <Preparation of Flux> (Examples 1 to 20, Comparative Examples 1 to 3) Each flux in the Examples and Comparative Examples was prepared with the composition shown in Tables 1 to 4. The components of the raw materials used are shown below. The contents in Tables 1 to 4 are in mass % when the total mass of the flux is 100 mass %, and blank spaces indicate 0 mass %.

[0117] Epoxy resin: A mixture of bisphenol F epoxy resin and bisphenol A epoxy resin was used as the bisphenol type epoxy resin mixture. 1,6-bis(glycidyloxy)naphthalene was used as the naphthalene type epoxy resin.

[0118] The epoxy equivalent weight of the bisphenol-type epoxy resin mixture as a whole was 156 to 170 g / eq. The epoxy equivalent weight of the naphthalene-type epoxy resin was 136 to 150 g / eq.

[0119] Curing agents: benzoguanamine (228°C), acetoguanamine (275°C), 2-phenyl-4-methyl-5-hydroxymethylimidazole (193°C), methyl-tetrahydrophthalic anhydride. The values ​​in parentheses indicate melting points.

[0120] Coupling agents: As specific coupling agents (1) to (4), compounds represented by the following chemical formulas (C-1-1) to (C1-4) were used, respectively. As other coupling agents (1) to (2), compounds represented by the following chemical formulas (C-2-1) to (C-2-2) were used, respectively.

[0121]

[0122]

[0123] Thixotropic agent The polyamide used was obtained by the following method. 12-hydroxystearic acid and dodecanedioic acid were added and heated to about 100°C, then hexamethylenediamine was added and heated to about 220°C and maintained for 3 hours to obtain the polyamide of Preparation Example 1. The raw materials used were X moles of dodecanedioic acid, Y moles of 12-hydroxystearic acid, and Z moles of hexamethylenediamine. The number of moles of the raw materials satisfied the relationship 2Z = 2X + Y. Hydrogenated castor oil

[0124] ・Activators: glutaric acid, adipic acid, pimelic acid, suberic acid, tertiary amine

[0125] According to the evaluation methods described in the following <Evaluation>, the evaluation of shear strength, viscosity, wettability, continuous use time, and glass transition temperature were performed. The results of these evaluations are shown in Tables 1 to 4.

[0126] <Evaluation> <Shear Strength Evaluation> (1) Evaluation Method Using a metal mask (opening size: φ0.6 mm, thickness: 0.02 mm), the flux of each example was printed on a ceramic plate. Next, a solder ball (96.5Sn-3.0Ag-0.5Cu (numbers indicate mass %), diameter 0.3 mm; M705, manufactured by Senju Metal Industry Co., Ltd.) was placed on the printed flux. Next, the ceramic plate with the solder ball mounted thereon was heated at 180°C for 30 minutes using a hot plate. Next, the shear strength was measured using a high-speed shear tester (DAGE-Series 4000HS) with a shear speed set to 1000 μm / s and a shear height set to 30 μm. Based on the shear strength measurement values, the shear strength between the solder ball and the ceramic plate was evaluated according to the following criteria.

[0127] (2) Evaluation Criteria A: The shear strength was 5.88 N or more. B: The shear strength was 2.94 N or more and less than 5.88 N. C: The shear strength was less than 2.94 N. Evaluation A was considered a pass, and evaluations B to C were considered a fail.

[0128] <<Evaluation of Viscosity>> (1) Evaluation Method The viscosity was measured using a viscometer (PCU-205, manufactured by Malcom Co., Ltd.). First, 100 to 150 g of the flux of each example was placed in a sample pot. The temperature of the flux was set to 25°C, and the flux was stirred at 10 rpm for 3 minutes, 3 rpm for 6 minutes, 4 rpm for 3 minutes, 5 rpm for 3 minutes, and 10 rpm for 3 minutes, in that order, and the viscosity was measured immediately after stirring.

[0129] (2) Judgment criteria A: The viscosity was 20 Pa·s or less. B: The viscosity was more than 20 Pa·s and 40 Pa·s or less. C: The viscosity was more than 40 Pa·s.

[0130] <Evaluation of Wettability> (1) Evaluation Method The meniscograph test was performed in accordance with JIS Z 3197 (2021) 8.3.1.2 "Wetting Balance Test." The flux of each example was applied to a bare copper plate (width 5 mm × length 25 mm × thickness 0.5 mm). The flux-coated copper plate was heat-treated in an air atmosphere at 120 ° C for 15 minutes to obtain a test plate. Five such test plates were prepared for each example and comparative example. Each obtained test plate was immersed in a solder bath to obtain the zero cross time (sec). Here, a Solder Checker SAT-5200 (manufactured by RHESCA) was used as the test device, and 96.5Sn-3.0Ag-0.5Cu (values ​​are in mass%, M705, manufactured by Senju Metal Industry Co., Ltd.) was used as the solder, and the evaluation was performed as follows. The solder wettability was evaluated based on the average value of the zero cross time (sec) of the five test boards for each example and comparative example. The test conditions were set as follows: Immersion speed in solder bath: 10 mm / sec Immersion depth in solder bath: 3 mm Immersion time in solder bath: 10 sec Solder bath temperature: 250°C The shorter the average zero cross time (sec), the faster the wetting speed, which means better solder wettability. Based on the zero cross time, the wettability was evaluated according to the following criteria.

[0131] (2) Judgment criteria A: 2.0 seconds or less B: Over 2.0 seconds and less than 4.0 seconds C: 4.0 seconds or more

[0132] <Evaluation of Continuous Use Time> (1) Evaluation Method: Flux was continuously squeezed using a test device (Solder Ball Mounter SBM370, manufactured by Shibuya Kogyo Co., Ltd.). The squeegeeing speed was 0.15 to 0.16 m / sec, the number of squeezes was 6 times / min, the test temperature was 23 to 26°C, and the test time was 24 hours. The viscosity of the flux for each example was measured every hour. Next, the time until the viscosity of the flux for each example increased by 5 Pa s compared to the viscosity immediately after the start of squeegeeing was defined as the continuous use time.

[0133] (2) Criteria for evaluation A: The continuous use time was 10 hours or more. B: The continuous use time was 5 hours or more but less than 10 hours. C: The continuous use time was less than 5 hours.

[0134] <Evaluation of Glass Transition Temperature> (1) Evaluation Method The flux of each example was allowed to stand at 170°C for 2 hours to harden, and test pieces (18 mm x 5 mm x 5 mm) were prepared. Using a thermomechanical analyzer (TMA, manufactured by Hitachi Corporation, SAT-5200), the glass transition temperature of each test piece was calculated based on the measured linear expansion coefficient. The glass transition temperature was defined as the temperature at which the measured linear expansion coefficient suddenly changed. For the measurement of the linear expansion coefficient, the starting temperature was set to 0°C, the measurement temperature range was set to 0 to 200°C, and the heating rate was set to 5°C / min.

[0135] (2) Criteria for evaluation A: The glass transition temperature was 110°C or higher. B: The glass transition temperature was 90°C or higher and lower than 110°C. C: The glass transition temperature was lower than 90°C.

[0136]

[0137] As shown in Table 1, the fluxes of Examples 1 to 4 containing the specific coupling agent had higher shear strength than the fluxes of Comparative Examples 1 to 3 containing no specific coupling agent.

[0138]

[0139] As shown in Table 2, the fluxes of Examples 7 to 10 containing an activator had sufficient wettability.

[0140]

[0141] As shown in Table 3, the fluxes of Examples 13 and 14, in which the mass ratio of bisphenol type epoxy resin / naphthalene type epoxy resin was 0.70 or more and 1.5 or less, were superior in the evaluation of viscosity, evaluation of continuous use time, and evaluation of glass transition temperature to the fluxes of Examples 11, 12, 15, and 16, in which the mass ratio of bisphenol type epoxy resin / naphthalene type epoxy resin was less than 0.70 or more than 1.5.

[0142]

[0143] As shown in Table 4, Examples 17 and 20 containing guanamines were superior in the evaluation of continuous use time and evaluation of glass transition temperature compared to Examples 18 and 19 containing curing agents other than guanamines.

[0144] According to the present invention, it is possible to provide a flux that can increase the bonding strength of a solder joint without using an underfill, and a method for manufacturing a bonded body using the flux. This flux is suitable for use in mounting solder balls on a chip.

[0145] REFERENCE SIGNS LIST 1 squeegee 2 table 3 flux (flux film) 4 solder ball 5 chip 6 component 7 substrate 8 electrode 9 flux residue 10 joint

Claims

1. A flux containing an epoxy resin, a curing agent for curing the epoxy resin, and an activator, wherein the mass ratio of the content of the epoxy resin to the content of the curing agent is 5 or more, expressed as a mass ratio of epoxy resin / curing agent, and the flux further contains a coupling agent, wherein the coupling agent includes a compound having a methoxy group, and the compound is a compound expressed by the following general formula (C-1), and the content of the epoxy resin is 50 mass % or more and 95 mass % or less, based on the total mass of the flux. [In the formula, R ｃ１ represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. ｃ２ represents an alkylene group having 1 to 10 carbon atoms or a single bond. However, the methylene group constituting the alkylene group may be substituted with an oxygen atom. R ｃ３ represents an epoxy group-containing group or a thiol group. ｃ is an integer from 1 to 3. ｃ is an integer from 0 to 2. ｃ +m ｃ = 3.] 2. The flux according to claim 1, wherein the epoxy resin includes a bisphenol-type epoxy resin.

3. The flux according to claim 1 or 2, wherein the epoxy resin includes a naphthalene-type epoxy resin.

4. The flux according to claim 1, wherein the epoxy resin contains a bisphenol-type epoxy resin and a naphthalene-type epoxy resin, and the mass ratio of the bisphenol-type epoxy resin content to the naphthalene-type epoxy resin content, expressed as a mass ratio of bisphenol-type epoxy resin / naphthalene-type epoxy resin, is 0.70 or more and 1.5 or less.

5. The flux according to any one of claims 1 to 4, wherein the hardener contains an amine having a melting point of 190°C or higher.

6. The flux according to any one of claims 1 to 5, wherein the hardener includes a guanamine.

7. The flux of claim 1, further comprising an activator.

8. The flux according to any one of claims 1 to 7, which is used to join a component having solder balls to a substrate.

9. A method for manufacturing a bonded body, comprising the steps of: treating solder balls of a component having solder balls with the flux according to any one of claims 1 to 7; and soldering the component having the solder balls to a substrate to obtain a bonded body.

Images