Soldering flux and method for producing a bonded body

Abstract

The present application provides a flux capable of improving the bonding strength of a solder bonding even without using an underfill adhesive, and a method for producing a bonded body using the flux. A flux containing an epoxy resin, a curing agent for curing the epoxy resin, and an active agent is used. The mass ratio of the epoxy resin / curing agent is 5 or more. The flux contains a coupling agent containing a compound represented by general formula (C-1). 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. In the formula, R c1 represents an alkyl group having 1 to 6 carbon atoms or a hydrogen atom. R c2 represents an alkylene group having 1 to 10 carbon atoms or a single bond. The methylene group constituting the alkylene group can be substituted with an oxygen atom. R c3 represents an epoxy group-containing group or a thiol group. n c is an integer of 1 to 3. m c is an integer of 0 to 2. n c + m c = 3.[Chemical Formula 1]

Description

Technical Field

[0001] This invention relates to a method for preparing flux and a bonding agent. Background Technology

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

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

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

[0005] In addition, when bonding a ball grid array with solder balls to a substrate, in order to improve the bonding strength, sometimes after soldering the ball grid array to the substrate, underfill adhesive is filled around the bonding area, and then the underfill adhesive is cured to fix the ball grid array to the substrate.

[0006] For example, Patent Document 1 describes a flux containing a thermosetting resin that is compatible with the underfill adhesive.

[0007] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2017-056485 Summary of the Invention The problem to be solved by the present invention When using the thermosetting flux and underfill as described in Patent Document 1, there are steps to fill the underfill around the joint and to cure the underfill, which reduces the efficiency of joint preparation.

[0008] Therefore, the inventors of this invention have studied soldering using a flux containing epoxy resin without using an underfill adhesive.

[0009] The inventors of this invention have discovered that in existing fluxes containing epoxy resin, after reflow soldering, there is a problem of reduced joint strength due to the low adhesion between the solder and the flux at the joint.

[0010] The present invention was made in view of the above circumstances, and its object is to provide a flux that can improve the bonding strength of solder joints even without the use of underfill adhesive, and a method for preparing a joint using the flux.

[0011] Problem-solving methods The present invention includes the following methods.

[0012] [1] A flux comprising an epoxy resin, a curing agent for curing the epoxy resin, and an activator, wherein the mass ratio of the epoxy resin content to the curing agent content is 5 or more as expressed as an epoxy resin / curing agent mass ratio, wherein the flux further comprises a coupling agent comprising a compound having a methoxy group, the compound being a compound represented by the following general formula (C-1), and the epoxy resin content relative to the total mass of the flux is 50% by mass or more and 95% by mass or less.

[0013] [Chemical Formula 1]

[0014] [In the formula, R] c1 R represents an alkyl group or a hydrogen atom with 1 to 6 carbon atoms. c2 Represents an alkylene group or a single bond with 1 to 10 carbon atoms. The methylene group constituting the alkylene group can be substituted with an oxygen atom. R c3 This indicates a group containing an epoxy group or a thiol group. c m is an integer between 1 and 3. c n is an integer between 0 and 2. c +m c =3. [2] According to the flux of [1], wherein the epoxy resin comprises a bisphenol type epoxy resin.

[0015] [3] The flux according to [1] or [2], wherein the epoxy resin comprises a naphthalene-type epoxy resin.

[0016] [4] According to the flux described in [1], wherein the epoxy resin comprises bisphenol type epoxy resin and naphthalene type epoxy resin, and the mass ratio of the content of bisphenol type epoxy resin to the content of naphthalene type epoxy resin, expressed as the mass ratio of bisphenol type epoxy resin / naphthalene type epoxy resin, is 0.70 or more and 1.5 or less.

[0017] [5] The flux according to any one of [1] to [4], wherein the curing agent comprises an amine with a melting point of 190°C or higher.

[0018] [6] The flux according to any one of [1] to [5], wherein the curing agent comprises guanidine.

[0019] [7] The flux according to [1], wherein the flux further comprises an activator.

[0020] [8] The flux according to any one of [1] to [7], wherein the flux is used to bond a component having solder balls to a substrate.

[0021] [9] A method for preparing a bonding body, comprising: a step of treating the solder balls of a component having solder balls with any one of the fluxes described in [1] to [7]; and a step of welding the component having the solder balls to a substrate to obtain a bonding body.

[0022] The present invention may also include the following methods.

[0023] [P1] A flux comprising an epoxy resin and a curing agent, wherein the mass ratio of the epoxy resin content to the curing agent content, expressed as an epoxy resin / curing agent mass ratio, is 5 or more, wherein the flux further comprises a coupling agent comprising a compound having a methoxy group.

[0024] [P2] According to the flux described in [P1], wherein the epoxy resin comprises a bisphenol type epoxy resin.

[0025] [P3] The flux according to [P1] or [P2], wherein the epoxy resin comprises a naphthalene-type epoxy resin.

[0026] [P4] According to the flux described in [P1], wherein the epoxy resin comprises bisphenol-type epoxy resin and naphthalene-type epoxy resin, and the mass ratio of the content of bisphenol-type epoxy resin to the content of naphthalene-type epoxy resin, expressed as the mass ratio of bisphenol-type epoxy resin / naphthalene-type epoxy resin, is 0.70 or more and 1.5 or less.

[0027] [P5] The flux according to any one of [P1] to [P4], wherein the curing agent comprises an amine with a melting point of 190°C or higher.

[0028] [P6] The flux according to any one of [P1] to [P5], wherein the curing agent comprises guanidine.

[0029] [P7] The flux according to any one of [P1] to [P6], wherein the flux further comprises an activator.

[0030] [P8] The flux according to any one of [P1] to [P7], wherein the flux is used to bond a component having solder balls to a substrate.

[0031] [P9] A method for preparing a bonding body, comprising: a step of treating the solder balls of a component having solder balls using a flux described in any one of [P1] to [P7]; and a step of welding the component having the solder balls to a substrate to obtain a bonding body.

[0032] Effects of the present invention According to the present invention, a flux that can improve the bonding strength of solder joints even without the use of underfill adhesive and a method for preparing a joint using the flux are provided. Attached Figure Description

[0033] Figure 1 This diagram schematically illustrates the process of using a scraper 1 to create a flux film 3.

[0034] Figure 2 This diagram schematically illustrates the contact between the solder ball 4 of component 6 and the flux film 3.

[0035] Figure 3 This diagram schematically illustrates the arrangement of component 6 on substrate 7.

[0036] Figure 4 This diagram schematically illustrates the situation where the joining member 6 and the substrate 7 are joined to form the joint 10. Detailed Implementation

[0037] As used herein, the terms “comprise” and “contain” are concepts that include any one of “comprise”, “consist essentially of”, and “consist of”. “Comprise” and “contain” can mean “consist essentially of” or “consist of”.

[0038] In this specification, where the content of a component in the flux is specified as a percentage of mass relative to the total mass of the flux, the total mass percentage of the flux is 100% by mass.

[0039] (Fluoride) An embodiment of the flux of the first method will be described.

[0040] The flux in this embodiment includes epoxy resin and a curing agent.

[0041] The mass ratio of epoxy resin content to curing agent content, expressed as epoxy resin / curing agent mass ratio, is 5 or more.

[0042] The flux in this embodiment also includes a coupling agent.

[0043] Coupling agents contain compounds with methoxy groups.

[0044] The flux of this embodiment, by comprising epoxy resin, curing agent, and coupling agent comprising a compound having a methoxy group, can improve the bonding strength of the solder joint even without the use of underfill adhesive.

[0045] The flux of this embodiment is suitable for the process of welding components with solder balls to a substrate to obtain a joint.

[0046] The joint passes through Figures 1-4 The illustrated process is as follows. First, as... Figure 1 As shown, flux 3 is spread on the worktable 2 using a scraper 1 to create a flux film 3. Next, as... Figure 2 As shown, a component 6 with solder balls 4 is prepared to be bonded to chip 5, such that the solder balls 4 of component 6 come into contact with flux film 3. Next, as... Figure 3 As shown, an electronic component 6 having solder balls 4 treated with flux 3 is disposed on a substrate 7. Next, as... Figure 4 As shown, a substrate 7 with electronic components 6 is reflow soldered to obtain a joint 10 bonded by solder balls 4 and flux residue 9.

[0047] In the process of fabricating flux film 3, it is required that the flux can be used continuously even after prolonged application. The flux of this embodiment can be used continuously even after prolonged application, making it suitable for mounting solder balls onto chips.

[0048] <Epoxy Resin> Examples of epoxy resins include bisphenol type epoxy resins, naphthalene type epoxy resins, phenolic varnish type epoxy resins, aliphatic epoxy resins, and cycloaliphatic epoxy resins.

[0049] As a bisphenol type epoxy resin, any epoxy resin that has structural units containing a bisphenol backbone is acceptable.

[0050] Examples of bisphenol types 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.

[0051] Bisphenol-type epoxy resins can be used alone or in combination with two or more types.

[0052] As a naphthalene-type epoxy resin, any epoxy resin that has structural units containing a naphthalene skeleton is acceptable.

[0053] Examples of naphthalene-type epoxy resins include 1,6-diglycidyloxynaphthalene, 1,3-diglycidyloxynaphthalene, 1,4-diglycidyloxynaphthalene, 1,5-diglycidyloxynaphthalene, 2,3-diglycidyloxynaphthalene, 2,6-diglycidyloxynaphthalene, 2,7-diglycidyloxynaphthalene, 1-(2,7-diglycidyloxynaphthalene)-1'-(2'-diglycidyloxynaphthalene)methane, 1,1'-bis(2,7-diglycidyloxynaphthalene)methane, 1,1'-bis(2,7-diglycidyloxynaphthalene)-1-phenyl-methane, 2,2'-diglycidyloxy-1,1'-binaphthalene, 2,2',7-triglycidyloxy-1,1'-binaphthalene, and 2,2',7,7'-tetraglycidyloxy-1,1'-binaphthalene.

[0054] Naphthalene-type epoxy resins can be used alone or in combination with two or more types.

[0055] As a phenolic varnish-type epoxy resin, any epoxy resin that has structural units containing a phenolic varnish skeleton can be used. Examples include phenolic varnish-type epoxy resin, cresol varnish-type epoxy resin, bisphenol A varnish-type epoxy resin, and bisphenol F varnish-type epoxy resin.

[0056] Epoxy resin can be used alone or in combination with two or more types.

[0057] The epoxy resin preferably includes one or more selected from bisphenol-type epoxy resin and naphthalene-type epoxy resin, and more preferably includes bisphenol-type epoxy resin and naphthalene-type epoxy resin.

[0058] By including bisphenol-type epoxy resin in the epoxy resin, it is easier to prevent the flux viscosity from becoming too high and to extend the continuous use time of the flux.

[0059] By including naphthalene-type epoxy resin in the epoxy resin, the glass transition temperature can be easily increased.

[0060] The polystyrene equivalent molecular weight of the epoxy resin is preferably 200-500, more preferably 260-400.

[0061] The epoxy equivalent of the epoxy resin is preferably 100~250 g / eq., more preferably 130~200 g / eq.

[0062] The epoxy resin content in the flux of this embodiment is preferably 50% by mass or more and 95% by mass or less relative to the total mass of the flux, 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.

[0063] By setting the epoxy resin content above the lower limit of the above range, the strength of the solder joint can be easily improved.

[0064] When the flux of this embodiment contains bisphenol-type epoxy resin and naphthalene-type epoxy resin, the mass ratio of the content of bisphenol-type epoxy resin to the content of naphthalene-type epoxy resin, expressed as the mass ratio of bisphenol-type epoxy resin / naphthalene-type epoxy resin, can be 0.01 or more and 100 or less, preferably 0.10 or more and 4 or less, more preferably 0.70 or more and 1.5 or less, and may also be 0.73 or more and 1.29 or less.

[0065] By setting the mass ratio of bisphenol-type epoxy resin to naphthalene-type epoxy resin to the lower limit of the above range, it is easier to prevent the flux viscosity from becoming too high and to extend the continuous use time of the flux. By setting it to the upper limit of the above range, the glass transition temperature is more likely to increase.

[0066] <Curing agent> The curing agent contained in the flux of this embodiment is a compound that has the function of curing epoxy resin.

[0067] As a curing agent, there are no particular limitations as long as the present invention is effective. For example, guanidines, imidazoles, acid anhydrides, guanidines, aminoguanidines, ureas, modified polyamines and their derivatives, dicyandiamide, boron trifluoride amine complexes, organic acid hydrazides, melamine, amine adduct curing agents, vinyl ether-terminated carboxylic acids, onium salts, isocyanate curing agents, phenols, etc.

[0068] As guanidines, compounds represented by the following general formula (H-1) can be cited.

[0069] [Chemical Formula 2]

[0070] [In the formula, R] h Indicates alkyl, aryl, or aralkyl. In the above general formula (H-1), R is... h The alkyl group in the formula is preferably an alkyl group with 1 to 4 carbon atoms.

[0071] In the above general formula (H-1), R is... h The aryl group in the aryl group is preferably phenyl.

[0072] As a guanidine class, it is preferably selected from one or more of benzoguanidine and acetylguanidine.

[0073] As imidazoles, any compound with a five-membered heterocycle having nitrogen atoms at positions 1 and 3 is acceptable.

[0074] Examples of imidazoles include, for instance, imidazole, 2-methylimidazolium, 2-ethylimidazolium, 2-undecylimidazolium, 2-heptadecylimidazolium, 1,2-dimethylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 2-phenyl-4-methylimidazolium, 1-benzyl-2-phenylimidazolium, 1-benzyl-2-phenylimidazolium, 1-cyanoethyl-2-methylimidazolium, 1-cyanoethyl-2-undecylimidazolium, 1-cyanoethyl-2-ethyl-4-methylimidazolium, 1-cyanoethyl-2-phenylimidazolium, 2-phenyl-4,5-dihydroxymethylimidazolium, 2-phenyl-4-methyl-5-hydroxymethylimidazolium, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, 2-methylimidazoline, etc. 2-Octylbenzimidazole, 2-Pentylbenzimidazole, 2-(1-Ethylpentyl)benzimidazole, 2-Nonylbenzimidazole, 2-(4-Thiazolyl)benzimidazole, benzimidazole, 2,4-Diamino-6-[2'-Methylimidazolyl-(1')]-Ethyl-triazine, 2,4-Diamino-6-[2'-Undecylimidazolyl-(1')]-Ethyl-triazine, 2,4-Diamino-6-[2'-Undecylimidazolyl-(1')]-Ethyl-triazine, 2,4-Di Amino-6-[2'-ethyl-4'-methylimidazolium-(1')]-ethyl-triazine, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolium-(1')]-ethyl-triazine isocyanuric acid adduct, 2-phenylimidazolium isocyanuric acid adduct, epoxy-imidazolium adduct, etc.

[0075] Examples of acid anhydrides include phthalic anhydride, maleic anhydride, cyclohexane dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylnadic anhydride, nadic anhydride, glutaric anhydride, methylhexahydrophthalic anhydride and 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 bis(triphenyl) anhydride, glycerol bis(triphenyl) anhydride monoacetate, tetrapropylene succinic anhydride, etc.

[0076] The melting point of the curing agent can be, for example, 150~400℃, preferably 190℃ or higher, more preferably 200℃ or higher, even more preferably 210℃ or higher, and particularly preferably 220℃ or higher.

[0077] By setting the melting point of the curing agent above the aforementioned lower limit, it is easier to suppress excessive reaction between the epoxy resin and the curing agent, and to extend the continuous service life.

[0078] In this specification, melting point refers to the temperature at which a solid melts into a liquid. The melting point of the target compound may be, for example, the melting point described in the "Iwanami Rikan Dictionary of Chemical Dictionary, 5th Edition". Alternatively, the melting point of the target compound may be the melting point measured according to the method of JISK 0064:1992.

[0079] The curing agent is preferably selected from one or more of guanidine, imidazole and acid anhydrides, more preferably selected from one or more of guanidine and imidazole, and even more preferably guanidine.

[0080] By including guanidines in the flux, excessive reaction between epoxy resin and curing agent can be easily suppressed, thus extending the continuous service life.

[0081] The curing agent content in the flux of this embodiment is preferably 1% or more and 30% or less by mass relative to the total mass of the flux, and more preferably 2% or more and 20% or less by mass.

[0082] When the flux in this embodiment contains guanidine, the content of guanidine in the flux is preferably 3% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 20% by mass or less, relative to the total mass of the flux.

[0083] When the flux in this embodiment contains imidazoles, the content of imidazoles in the flux is preferably 1% by mass or more and 15% by mass or less, more preferably 2% by mass or more and 10% by mass or less, relative to the total mass of the flux.

[0084] When the flux in this embodiment contains anhydride, the content of anhydride in the flux is preferably 3% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 20% by mass or less, relative to the total mass of the flux.

[0085] In the flux of this embodiment, the mass ratio of epoxy resin content to curing agent content, expressed as epoxy resin / curing agent mass ratio, is, for example, 5 or more and 50 or less, preferably 6 or more.

[0086] There is no particular upper limit to the mass ratio of epoxy resin to curing agent; for example, it can be 50 or 30.

[0087] Specific coupling agents The flux in this embodiment includes a coupling agent, which includes a specific coupling agent.

[0088] The specific coupling agent is a compound containing a methoxy group.

[0089] Silane compounds are preferred as specific coupling agents.

[0090] Certain coupling agents preferably have epoxy or thiol groups.

[0091] As a specific coupling agent, the compound represented by the following general formula (C-1) is preferred.

[0092] [Chemical Formula 3]

[0093] [In the formula, R] c1 R represents an alkyl group or a hydrogen atom with 1 to 6 carbon atoms. c2 Represents an alkylene group or a single bond with 1 to 10 carbon atoms. The methylene group constituting the alkylene group can be substituted with an oxygen atom. R c3 This indicates a group containing an epoxy group or a thiol group. c m is an integer between 1 and 3. c n is an integer between 0 and 2. c +m c =3. R c1 The alkyl group can be either straight-chain or branched.

[0094] R c1 Preferably, it is an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group.

[0095] R c2 The alkylene groups in the form can be either straight-chain or branched.

[0096] R c2 Preferably, it is an alkylene group having 1 to 7 carbon atoms.

[0097] As R c3 The epoxy group in the text includes, for example, groups consisting only of epoxy groups; groups consisting only of alicyclic epoxy groups; and groups having an epoxy group or an alicyclic epoxy group and a divalent linking group.

[0098] Alicyclic epoxy groups refer to alicyclic groups with an oxetine structure that are three-membered cyclic ethers. Specifically, they refer to groups with both alicyclic and oxetine structures.

[0099] The alicyclic group that forms the basic skeleton of the alicyclic epoxy group can be monocyclic or polycyclic. Examples of monocyclic alicyclic groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Examples of polycyclic alicyclic groups include norbornyl, isobornyl, tricyclononyl, tricyclodecyl, and tetracyclododecyl. Furthermore, the hydrogen atoms in these alicyclic groups can be substituted with alkyl, alkoxy, or hydroxyl groups.

[0100] In the case where the group has an epoxy group or an alicyclic epoxy group and a divalent linker, it is preferred that the epoxy group or alicyclic epoxy group is connected via R in the formula. c2The bonded divalent linker is bonded.

[0101] In the above general formula (C-1), R is preferred. c1 It is an alkyl group having 1 to 4 carbon atoms; R c2 It is an alkylene group having 1 to 7 carbon atoms; R c3 It is an epoxy group or a thiol group; n c It is an integer of 2 or 3.

[0102] In the above general formula (C-1), R is more preferred. c1 Methyl; R c2 It is an alkylene group having 1 to 7 carbon atoms; R c3 It is a group consisting only of epoxy groups, a group consisting only of alicyclic epoxy groups, or a thiol group; n c It is an integer of 2 or 3.

[0103] The preferred coupling agent is a compound represented by the following chemical formulas (C-1-1) to (C-1-4).

[0104] [Chemical Formula 4]

[0105] In the flux, the content of a specific coupling agent relative to the total mass of the flux is preferably 0.1 to 5% by mass, more preferably 0.3 to 3% by mass, and even more preferably 0.5 to 2% by mass.

[0106] <Other Ingredients> The flux in this embodiment may contain other components as needed, in addition to epoxy resin, curing agent and coupling agent, or it may not contain other components.

[0107] Other components include, for example, surfactants, thixotropic agents, solvents, resin components other than epoxy resins (other resins), metal passivators, antioxidants, surfactants, colorants, etc.

[0108] The flux in this embodiment may also be composed of epoxy resin, curing agent, activator, coupling agent, and one or more of the following: thixotropic agent, solvent, other resin, metal passivator, antioxidant, surfactant, and colorant. The components constituting any other group of ingredients may be arbitrarily selected.

[0109] Surfactants Examples of active agents include, for example, organic acids, amines, halogen compounds, and organophosphorus compounds.

[0110] 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.

[0111] Examples of aliphatic monocarboxylic acids include, for example, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, isononanoic acid, decanoic acid, decenoic acid, lauric acid (dodecanoic acid), undecanoic acid, lindeic acid, tridecanoic acid, myristone acid, pentadecanoic acid, isopalmitic acid, palmitoleic acid, hexadecanetrienoic acid, cyclopentene undecanoic acid, heptadecanic acid, isostearic acid, transoleic acid, phellandrenic acid, stearatetraenoic acid, tungsten acid, tarric acid, octadec-11-enoic acid, ricinoleic acid, piperidinic acid, styracidin, nonadecanic acid, eicosanoic acid, stearic acid, 12-hydroxystearic acid, oleic acid, linoleic acid, linolenic acid, myristic acid, glycolic acid, and thioglycolic acid.

[0112] Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, dodecanoic acid, eicosanoic acid, citralic acid, diethylene glycolic acid, tartaric acid, and 2,4-diethylglutaric acid.

[0113] Examples of aromatic carboxylic acids include, for example, aromatic monocarboxylic acids such as benzoic acid, 3-hydroxybenzoic acid, salicylic acid, pyridinecarboxylic acid, p-anisic acid, m-anisic acid, o-anisic acid, p-hydroxyphenylacetic acid, and 2-quinolinecarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, phenylsuccinic acid, pyridinecarboxylic acid, and dibutylaniline diglycolic acid; and pyridinecarboxylic acid, pyridinecarboxylic acid, and 3-hydroxypyridinecarboxylic acid.

[0114] Examples of tricarboxylic acids include, for example, citric acid.

[0115] Examples of hydroxycarboxylic acids include, for example, 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butyric acid, citric acid, isocitric acid, malic acid, tartaric acid, etc.

[0116] In addition, examples of carboxylic acids include tris(2-carboxyethyl) isocyanurate and 1,3-cyclohexanedicarboxylic acid.

[0117] In addition, polycarboxylic acids can be cited as examples of carboxylic acids.

[0118] Examples of polycarboxylic acids include dimer acids, trimer acids, hydrogenated dimer acids as hydrides of hydrogenated dimer acids, and hydrogenated trimer acids as hydrides of hydrogenated trimer acids.

[0119] Examples of organic sulfonic acids include, for example, aliphatic sulfonic acids and aromatic sulfonic acids. Examples of aliphatic sulfonic acids include, for example, alkane sulfonic acids and alkanolic sulfonic acids.

[0120] Organic acids can be used alone or in combination of two or more.

[0121] As an organic acid, carboxylic acids are preferred, and dicarboxylic acids are more preferred.

[0122] The dicarboxylic acid is preferably selected from one or more of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, and azelaic acid; more preferably selected from one or more of glutaric acid, adipic acid, pimelic acid, and octanoic acid; and even more preferably selected from one or more of glutaric acid, adipic acid, and pimelic acid.

[0123] ·amine Examples of amines include azoles (excluding imidazoles which function as curing agents), guanidines, amino alcohols, alkylamine compounds, and amine polyoxyethylene adducts.

[0124] Examples of azoles include, for instance, 2,4-diamino-6-vinyl-triazine, 2,4-diamino-6-vinyl-triazine isocyanuric acid adduct, 2,4-diamino-6-methacryloyloxyethyl-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-pentylphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2,2'-methylenebis[6-(2H-benzotriazol-2-yl)-4-tert-octylphenol], and 6-(2-benzotriazolyl)-4 -tert-octyl-6'-tert-butyl-4'-methyl-2,2'-methylenebisphenol, 1,2,3-benzotriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole, carboxybenzotriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole, 2,2'-[[(methyl-1H-benzotriazole-1-yl)methyl]imino]diethanol, 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, 5-methylbenzotriazole, 5-phenyltetrazole, etc.

[0125] Examples of guanidines include, for example, 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylguanidine, 1,3-di-o-isopropylphenylguanidine, and 1,3-di-o-isopropylphenyl-2-propionylguanidine.

[0126] Examples of amino alcohols include, for example, N,N,N',N'-tetra(2-hydroxypropyl)ethylenediamine, N,N,N',N'-tetra(2-hydroxyethyl)ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, 1-amino-2-propanol, bis(2-hydroxypropyl)amine, tri(2-hydroxypropyl)amine, etc.

[0127] Examples of alkylamine compounds include, for example, ethylamine, triethylamine, ethylenediamine, triethylenetetramine, cyclohexylamine, hexadecylamine, stearylamine, etc.

[0128] Examples of amine polyoxyethylene adducts include terminal diamine polyalkylene glycols, aliphatic amine polyoxyethylene adducts, aromatic amine polyoxyethylene adducts, and polyamine polyoxyethylene adducts.

[0129] Examples of epoxides that are added to amine polyoxyethylene adducts include ethylene oxide, propylene oxide, and butane oxide.

[0130] Terminal diamine polyalkylene glycols are compounds formed by amylating both ends of polyalkylene glycols.

[0131] Examples of terminal diamine polyalkylene glycols include, for example, terminal diamine polyethylene glycol, terminal diamine polypropylene glycol, and terminal diamine polyethylene glycol-polypropylene glycol copolymer.

[0132] Examples of terminal diamine polyethylene glycol-polypropylene glycol copolymers include polyethylene glycol-polypropylene glycol copolymer bis(2-aminopropyl) ether and polyethylene glycol-polypropylene glycol copolymer bis(2-aminoethyl) ether.

[0133] Aliphatic amine polyoxyalkylene adducts, aromatic amine polyoxyalkylene adducts, and polyamine polyoxyalkylene adducts are substances in which a polyoxyalkylene group is bonded to the nitrogen atom of an amine. Examples of such amines include ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, hexamethylenediamine, diethylenetriamine, laurylamine, stearylamine, oleylamine, tallow amine, cured tallow amine, tallow propyl diamine, m-xylenediamine, toluenediamine, p-xyleneamine, phenylenediamine, isophoronediamine, 1,10-decanediamine, 1,12-dodecanediamine, 4,4-diaminodicyclohexylmethane, 4,4-diaminodiphenylmethane, butane-1,1,4,4-tetramine, and pyrimidine-2,4,5,6-tetramine.

[0134] Examples of halogen compounds include, for example, hydrohalates and other organic halogen compounds.

[0135] Organic acids are preferred as surfactants.

[0136] One type of surfactant can be used alone, or two or more types can be used in combination.

[0137] The content of the activator in the flux is preferably 1% or more and 20% or less by mass relative to the total mass of the flux, more preferably 2% or more and 15% or less by mass, and even more preferably 3% or more and 10% or less by mass.

[0138] Thixotropic agents Examples of thixotropic agents include ester-based thixotropic agents, amide-based thixotropic agents, and sorbitol-based thixotropic agents.

[0139] Examples of ester-based thixotropic agents include, for example, ester compounds, specifically hydrogenated castor oil and ethyl myristate.

[0140] Examples of amide-based thixotropic agents include monoamides, diamides, and polyamides.

[0141] Examples of monoamides include laurylamide, palmitamide, stearamide, behenamide, hydroxystearamide, saturated fatty acid amide, oleamide, erucamide, unsaturated fatty acid amide, 4-methylbenzamide (p-toluamide), p-toluenemethaneamide, aromatic amide, hexamethylene hydroxystearamide, substituted amide, hydroxymethylstearamide, hydroxymethylamide, fatty acid ester amide, etc.

[0142] Examples of diamides include ethylenedicarboxylic acid (C6-24 carbon atoms in fatty acids) amides, ethylenedihydroxycarboxylic acid (C6-24 carbon atoms in fatty acids) amides, hexamethylenedicarboxylic acid (C6-24 carbon atoms in fatty acids) amides, hexamethylenedihydroxycarboxylic acid (C6-24 carbon atoms in fatty acids) amides, and aromatic diamides. Examples of fatty acids used as raw materials for these diamides include stearic acid (C18 carbon atoms), oleic acid (C18 carbon atoms), and lauric acid (C12 carbon atoms).

[0143] Examples of polyamides include saturated fatty acid polyamides, unsaturated fatty acid polyamides, aromatic polyamides, 1,2,3-propanetricarboxylic acid tris(2-methylcyclohexylamide), cyclic amide oligomers, and non-cyclic amide oligomers.

[0144] Examples of cyclic amide oligomers include amide oligomers obtained by condensation polymerization of dicarboxylic acids and diamines into a cyclic form, amide oligomers obtained by condensation polymerization of tricarboxylic acids and diamines into a cyclic form, amide oligomers obtained by condensation polymerization of dicarboxylic acids and triamines into a cyclic form, amide oligomers obtained by condensation polymerization of dicarboxylic acids and tricarboxylic acids and diamines into a cyclic form, amide oligomers obtained by condensation polymerization of dicarboxylic acids and tricarboxylic acids and triamines into a cyclic form, amide oligomers obtained by condensation polymerization of dicarboxylic acids and diamines and triamines into a cyclic form, and amide oligomers obtained by condensation polymerization of dicarboxylic acids and tricarboxylic acids and diamines and triamines into a cyclic form.

[0145] Furthermore, examples of acyclic amide oligomers include those obtained by the condensation polymerization of monocarboxylic acids with diamines and / or triamines to form acyclic amide oligomers, and those obtained by the condensation polymerization of dicarboxylic acids and / or tricarboxylic acids with monoamines to form acyclic amide oligomers. When the amide oligomer contains a monocarboxylic acid or a monoamine, the monocarboxylic acid or monoamine functions as terminal molecules, resulting in acyclic amide oligomers with reduced molecular weight. Additionally, in the case of amide compounds obtained by the condensation polymerization of dicarboxylic acids and / or tricarboxylic acids with diamines and / or triamines to form acyclic amide compounds, the acyclic amide oligomer becomes an acyclic polymeric amide polymer. Furthermore, acyclic amide oligomers also include those obtained by the condensation polymerization of monocarboxylic acids and monoamines to form acyclic amide oligomers.

[0146] Examples of sorbitol-based thixotropic agents include, for example, dibenzylidene-D-sorbitol, di(4-methylbenzylidene)-D-sorbitol, (D-)sorbitol, monobenzylidene(-D-)sorbitol, and mono(4-methylbenzylidene)-(D-)sorbitol.

[0147] Thixotropic agents can be used alone or in combination of two or more.

[0148] As a thixotropic agent, it is preferably selected from one or more of ester-based thixotropic agents and amide-based thixotropic agents.

[0149] The content of the thixotropic agent in the flux is preferably 0.1% by mass or more and 10% by mass or less relative to the total mass of the flux, 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.

[0150] The flux in this embodiment may or may not contain solvent, as long as it achieves the effect of the present invention.

[0151] Examples of solvents include water, alcohols, glycol ethers, and terpineols.

[0152] 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-hexyn-2,5-diol, 2,3-dimethyl-2,3-butanediol, 2-methylpentane-2,4-diol, and 1,1,1-tris(hydroxymethyl)propane. 2-Ethyl-2-hydroxymethyl-1,3-propanediol, 2,2'-oxybis(methylene)bis(2-ethyl-1,3-propanediol), 2,2-bis(hydroxymethyl)-1,3-propanediol, 1,2,6-trihydroxyhexane, 1-ethynyl-1-cyclohexanol, 1,4-cyclohexanediol, 1,4-cyclohexanediol, 2,4,7,9-tetramethyl-5-decyn-4,7-diol, 2-hexyl-1-decanol, 2-methyl-2,4-pentanediol (hexanediol), octanediol, etc.

[0153] Examples of ethylene glycol ether solvents include dipropylene glycol monomethyl ether, diethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, ethylene glycol monobutyl ether (butyl ethylene glycol), ethylene glycol monohexyl ether (hexyl ethylene glycol), diethylene glycol monohexyl ether (hexyl diethylene glycol), diethylene glycol dibutyl ether, triethylene glycol monobutyl ether, methyl propylene glycol triether, triethylene glycol butyl methyl ether, tetraethylene glycol, tetraethylene glycol dimethyl ether, and tripropylene glycol n-butyl ether.

[0154] Examples of terpineols include α-terpineol, β-terpineol, γ-terpineol, and mixtures of terpineols (i.e., mixtures whose main component is α-terpineol and which contain β-terpineol or γ-terpineol).

[0155] One solvent can be used alone, or two or more solvents can be used in combination.

[0156] The solvent content in the flux, relative to the total mass of the flux, can be, for example, 0 to 40% by mass, or more than 0% by mass and less than 40% by mass, or more than 0% by mass and less than 30% by mass, or more than 0% by mass and less than 20% by mass, or more than 0% by mass and less than 10% by mass, or more than 0% by mass and less than 5% by mass.

[0157] Resin components other than epoxy resin (other resins) The flux in this embodiment may contain resin components other than epoxy resin (other resins) or may not contain other resins, as long as it can achieve the effect of the present invention.

[0158] Other examples of resins include rosin and resins other than rosin.

[0159] In this specification, "rosin" includes natural resins containing a mixture of abrasive acid and its isomers, with abrasive acid as the main component, as well as substances that are chemically modified from natural resins (sometimes referred to as rosin derivatives).

[0160] Examples of rosin derivatives include purified rosin and modified rosin.

[0161] Examples of modified rosin include hydrogenated rosin, polymerized rosin, polymerized hydrogenated rosin, disproportionated rosin, acid-modified rosin, rosin esters, acid-modified hydrogenated rosin, acid anhydride-modified hydrogenated rosin, acid-modified disproportionated rosin, acid anhydride-modified disproportionated rosin, phenol-modified rosin, and α,β-unsaturated carboxylic acid modified products (acrylated rosin, maleated rosin, fumaric acid-modified rosin, etc.), as well as purified products, hydrides and disproportions of the polymerized rosin, and purified products, hydrides and disproportions of the α,β-unsaturated carboxylic acid modified products, rosin alcohol, rosin amine, hydrogenated rosin alcohol, rosin esters, hydrogenated rosin esters, rosin soap, hydrogenated rosin soap, acid-modified rosin soap, etc.

[0162] Other resins besides rosin include, for example, terpene resins, modified terpene resins, terpene phenol resins, modified terpene phenol resins, styrene resins, modified styrene resins, xylene resins, modified xylene resins, acrylic resins, polyethylene resins, and acrylic-polyethylene copolymer resins.

[0163] 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 methylphenolic resin-type xylene resins, polyol modified xylene resins, and polyoxyethylene addition xylene resins.

[0164] Other resins can be used alone or in combination of two or more.

[0165] The content of other resins in the flux, relative to the total mass of the flux, can be, for example, 0 to 20% by mass, more than 0% by mass and less than 20% by mass, more than 0% by mass and less than 10% by mass, more than 0% by mass and less than 5% by mass, or more than 0% by mass and less than 3% by mass.

[0166] Metal passivating agents Examples of metal passivating agents include hindered phenolic compounds and nitrogen compounds.

[0167] The "metal passivating agent" mentioned here refers to a compound that has the property of preventing metals from deteriorating due to contact with a certain compound.

[0168] Hindered phenolic compounds are phenolic compounds that have a large substituent (such as a branched chain or cyclic alkyl group such as tert-butyl) at at least one ortho position of phenol.

[0169] As hindered phenolic compounds, there are no particular limitations; examples include bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][ethylene bis(oxyethylene)], N,N'-hexamethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and 2,2'-dihydroxy-3 3'-bis(α-methylcyclohexyl)-5,5'-dimethyldiphenylmethane, 2,2'-methylenebis(6-tert-butyl-p-cresol), 2,2'-methylenebis(6-tert-butyl-4-ethylphenol), triethylene glycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,4 -bis(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylimino)-1,3,5-triazine, pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2-thiodiethylidene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-hexamethylene Compounds such as 3,5-di-tert-butyl-4-hydroxy-hydrogenated cinnamamide, 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, N,N'-bis[2-[2-(3,5-di-tert-butyl-4-hydroxyphenyl)ethylcarbonyloxy]ethyl]oxalamide, and compounds represented by the following chemical formulas.

[0170] [Chemical Formula 5]

[0171] (In the formula, Z is a substituted alkylene group. R) 81 and R 82 Each can be independently a substituted alkyl, aralkyl, aryl, heteroaryl, cycloalkyl, or heterocycloalkyl group. 83 and R 84 Each alkyl group can be substituted independently. Nitrogen compounds used as metal passivating agents include, for example, hydrazide nitrogen compounds, amide nitrogen compounds, triazole nitrogen compounds, and melamine nitrogen compounds.

[0172] As nitrogen compounds in the acylhydrazine system, any nitrogen compound with an acylhydrazine skeleton is acceptable. Examples include dodecanoic acid bis[N2-(2-hydroxybenzoyl)hydrazine], N,N'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hydrazine, decanedicarboxylic acid disalicylic acid hydrazine, N-salicyl-N'-salicylic acid hydrazine, m-nitrobenzoyl hydrazine, 3-aminophthalic acid hydrazine, phthalic acid dihydrazine, adipic acid hydrazine, oxaloyl di(2-hydroxy-5-octylphenylmethylene hydrazine), N'-benzoylpyrrolidone carboxylic acid hydrazine, and N,N'-bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hydrazine.

[0173] As an amide-based nitrogen compound, any nitrogen compound with an amide skeleton is acceptable, such as N,N'-bis{2-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]ethyl}oxalamide.

[0174] As a triazole nitrogen compound, any nitrogen compound with a triazole skeleton is acceptable, such as N-(2H-1,2,4-triazol-5-yl)salicylic acid amide, 3-amino-1,2,4-triazole, 3-(N-salicylic acid)amino-1,2,4-triazole, etc.

[0175] As a melamine-based nitrogen compound, any nitrogen compound with a melamine skeleton is acceptable, including melamine and melamine derivatives. More specifically, examples include triaminotriazine, alkylated triaminotriazine, alkoxyalkylated triaminotriazine, melamine, alkylated melamine, alkoxyalkylated melamine, N2-butylmelamine, N2,N2-diethylmelamine, and N,N,N',N',N",N"-hexa(methoxymethyl)melamine.

[0176] Metal passivating agents can be used alone or in combination of two or more.

[0177] The content of the metal passivating agent in the flux, relative to the total mass of the flux, can be, for example, 0 to 10% by mass, more than 0% by mass and less than 10% by mass, more than 0% by mass and less than 5% by mass, more than 0% by mass and less than 3% by mass, or more than 0% by mass and less than 1% by mass.

[0178] Antioxidants As antioxidants, examples include hindered phenolic antioxidants such as 2,2'-dihydroxy-3,3'-bis(α-methylcyclohexyl)-5,5'-dimethyldiphenylmethane.

[0179] Antioxidants can be used alone or in combination of two or more.

[0180] The content of antioxidant in the flux, relative to the total mass of the flux, can be, for example, 0 to 10% by mass, more than 0% by mass and less than 10% by mass, more than 0% by mass and less than 5% by mass, more than 0% by mass and less than 3% by mass, or more than 0% by mass and less than 1% by mass.

[0181] Surfactants Examples of surfactants include, for instance, nonionic surfactants.

[0182] Examples of nonionic surfactants include, for instance, polyoxyethylene adducts.

[0183] Examples of epoxides derived from polyoxyethylene adducts include ethylene oxide, propylene oxide, and butane oxide.

[0184] Examples of polyoxyethylene adducts include, for example, polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol copolymer, ethylene oxide-resorcinol copolymer, polyoxyethylene acetylene glycol, polyoxyethylene glycerol ether, polyoxyethylene alkyl ether, polyoxyethylene ester, polyoxyethylene alkylamide, etc.

[0185] Alternatively, polyoxyethylene adducts of alcohols can be cited as nonionic surfactants. Examples of alcohols include aliphatic alcohols, aromatic alcohols, and polyols.

[0186] Surfactants can be used alone or in combination of two or more.

[0187] The content of surfactant in the flux, relative to the total mass of the flux, can be, for example, 0 to 20% by mass, more than 0% by mass and less than 20% by mass, more than 0% by mass and less than 10% by mass, more than 0% by mass and less than 5% by mass, or more than 0% by mass and less than 3% by mass.

[0188] The flux of this embodiment described above, by containing a specific coupling agent having a methoxy group, can improve the bonding strength of the solder joint even without the use of underfill. Furthermore, it can improve the bonding strength even during low-temperature reflow soldering (e.g., 180°C).

[0189] The reason for this effect is not yet clear, but it is speculated that it is due to the methoxy group of a certain coupling agent bonding with the solder, thereby improving the adhesion between the solder and the flux, and as a result, the bonding strength is improved.

[0190] According to the embodiment of the flux, welding can be performed without the need for filling and curing of the underfill adhesive, and it can contribute to carbon neutralization.

[0191] The flux of the first embodiment is suitable for bonding components with solder balls to a substrate.

[0192] (Preparation method of the conjugate) The second method for preparing the conjugate comprises the following steps (a) and (b).

[0193] Process (a): The process of treating the solder balls of a component with solder balls using the flux of the first method. Process (b): The process of welding the component having the solder balls to the substrate to obtain a joint. Hereinafter, one embodiment of the preparation method of the second type of conjugate will be described.

[0194] <Process (a)> In step (a), the solder balls of the component having solder balls are treated with flux of the first type. For example, a ball grid array can be considered as a component having solder balls. (Example follows) Figure 1 As explained above, flux can also be used to treat solder balls in the following order.

[0195] like Figure 1 As shown, firstly, flux 3 is spread on the worktable 2 using a scraper 1 to create a flux film 3. Then, as... Figure 2 As shown, the flux film 3 is brought into contact with the solder ball 4 of component 6.

[0196] Solder alloys used as raw materials for solder balls can be solder alloys with known compositions.

[0197] Examples of solder alloys include, for example, Sn monomer solder alloys, Sn-based solder alloys, and Sn-Bi-based solder alloys.

[0198] Sn-based solder alloys are solder alloys prepared by adding one or more elements selected from Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, Pb, and P to Sn. Elements other than Sn in Sn-based solder alloys can be chosen arbitrarily.

[0199] For example, solder alloys can be Sn monomer solders, or Sn-Ag system, Sn-Cu system, Sn-Ag-Cu system, Sn-Bi system, Sn-In system, etc., or solder alloys with added Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, P, etc.

[0200] Alternatively, the solder alloy can be a Sn-Pb based alloy, or a Sn-Pb based alloy with added Sb, Bi, In, Cu, Zn, As, Ag, Cd, Fe, Ni, Co, Au, Ge, P, etc.

[0201] Solder alloys that do not contain Pb are preferred.

[0202] <Process (b)> In step (b), the component with flux-treated solder balls obtained in step (a) is soldered to the substrate to obtain a joint.

[0203] In step (b), solder balls 4 are prepared to be bonded to component 6 of chip 5, and as follows Figure 3 As shown, a component 6 having solder balls 4 treated with flux 3 is disposed on a substrate 7. Next, by heating the substrate 7 on which the component 6 is disposed, the solder balls 4 of the component 6 are bonded to the electrodes 8 of the substrate 7. As a result, a bonded body 10 is obtained, formed by bonding the component 6 and the substrate 7 using the solder balls 4 and flux residue 9.

[0204] The preferred heating temperature for components and substrates is 235~270°C, and more preferably 240~260°C.

[0205] According to the preparation method of the joint body of this embodiment described above, since the flux of the first method is used, a joint body with improved bonding strength can be obtained.

[0206] Example The present invention will be described below through embodiments, but the present invention is not limited to the following embodiments.

[0207] <Preparation of flux> (Examples 1-20, Comparative Examples 1-3) The fluxes of the formulation examples and comparative examples are shown in Tables 1-4. The composition of the raw materials used is shown below. The contents in Tables 1-4 are based on the total mass of the flux as 100% by mass, with blank columns indicating 0% by mass.

[0208] Epoxy resin: As a bisphenol type epoxy resin mixture, a mixture of bisphenol F type epoxy resin and bisphenol A type epoxy resin is used.

[0209] 1,6-bis(glycidoxy)naphthalene is used as a naphthalene-type epoxy resin.

[0210] The overall epoxy equivalent of bisphenol-type epoxy resin mixtures is 156~170 g / eq. The epoxy equivalent of naphthalene-type epoxy resins is 136~150 g / eq.

[0211] Hardener: Benzoguanidine (228℃), acetylguanidine (275℃), 2-phenyl-4-methyl-5-hydroxymethylimidazolium (193℃), methyltetrahydrophthalic anhydride. Melting point is indicated in parentheses.

[0212] Coupling agent: As specific coupling agents (1) to (4), compounds represented by the following chemical formulas (C-1-1) to (C1-4) are used respectively.

[0213] As other coupling agents (1) to (2), the compounds represented by the following chemical formulas (C-2-1) to (C-2-2) are used respectively.

[0214] [Chemical Formula 6]

[0215] [Chemical Formula 7]

[0216] ·Thixotropic agents Polyamides are substances obtained through the following methods.

[0217] 12-hydroxystearic acid and dodecanoic acid were added, and the mixture was heated to about 100°C. Then, hexamethylenediamine was added, and the mixture was heated to about 220°C and held for 3 hours to obtain the polyamide of Preparation Example 1.

[0218] The raw materials used are: dodecanoic acid (X moles), 12-hydroxystearic acid (Y moles), and hexamethylenediamine (Z moles). The molar numbers of the raw materials satisfy the relationship 2Z = 2X + Y.

[0219] Hydrogenated castor oil Surfactant Glutaric acid, adipic acid, pimelic acid, octanoic acid, tertiary amines The evaluation methods described in the "Evaluation" section below were used to evaluate the shear strength, viscosity, wettability, continuous service time, and glass transition temperature. The results of these evaluations are shown in Tables 1-4.

[0220] <Evaluation> Evaluation of Shear Strength (1) Evaluation method Flux for each example was printed onto a ceramic plate using a metal mask (opening size: φ0.6mm, thickness: 0.02mm). Next, solder balls (96.5Sn-3.0Ag-0.5Cu (numbers indicate mass %), 0.3mm diameter, M705, manufactured by Senju Metal Industries, Ltd.) were placed on the printed flux. Then, the ceramic plate with the solder balls was heated at 180°C for 30 minutes using a hot plate.

[0221] Next, using a high-speed shear test apparatus (DAGE-Series 4000 HS), with a shear speed of 1000 μm / s and a shear height of 30 μm, the shear strength was measured. Based on the measured shear strength values, the shear strength between the solder ball and the ceramic plate was evaluated according to the following criteria.

[0222] (2) Judgment Criteria A has a shear strength of 5.88 N or higher.

[0223] B has a shear strength of 2.94 N or more and less than 5.88 N.

[0224] C. Shear strength less than 2.94 N Evaluation A is considered satisfactory, while evaluations B through C are considered unsatisfactory.

[0225] Viscosity Evaluation (1) Evaluation method Viscosity was measured using a viscometer (Malcom, PCU-205). First, 100-150g of flux for each sample was placed in a sample vial. The flux temperature was set to 25°C, and the mixture was stirred in the following order: 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. The viscosity immediately after stirring was then measured.

[0226] (2) Judgment Criteria A has a viscosity of less than 20 Pa·s.

[0227] B. Viscosity exceeding 20 Pa·s but below 40 Pa·s.

[0228] C has a viscosity exceeding 40 Pa·s.

[0229] Evaluation of wettability (1) Evaluation method The meniscus test was conducted according to JIS Z3197 (2021) 8.3.1.2 "Wetting balance test".

[0230] Each example of flux was applied to a bare copper plate (5 mm wide × 25 mm long × 0.5 mm thick). The flux-coated copper plate was then heated at 120°C for 15 minutes in atmospheric atmosphere to obtain a test plate. Five such test plates were prepared for each example and each comparative example.

[0231] The obtained test plates were immersed in solder baths to obtain the zero-crossing time (sec). Here, a Solder Checker SAT-5200 (manufactured by RHESCA) was used as the test apparatus, and 96.5Sn-3.0Ag-0.5Cu (values ​​are by mass%, M705, manufactured by Senju Metal Industries, Ltd.) was used as the solder. The evaluation was conducted as follows. Solder wettability was evaluated based on the average zero-crossing time (sec) of five test plates from each example and comparative example. The test conditions were set as follows.

[0232] Immersion speed into the solder bath: 10 mm / sec Dipping depth into the solder bath: 3mm Immersion time in solder bath: 10 seconds Solder bath temperature: 250℃ A shorter average zero-crossing time (sec) indicates a faster wetting speed, meaning better solder wettability. Based on the zero-crossing time, wettability is evaluated according to the following criteria.

[0233] (2) Judgment Criteria A below 2.0 sec B. More than 2.0 sec but less than 4.0 sec C 4.0 sec or more Evaluation of continuous usage time (1) Evaluation method Flux was continuously applied using a test apparatus (SBM370 solder ball placement machine, manufactured by Shibuya Kogyo Co., Ltd.). The application speed was set to 0.15–0.16 m / s, the number of applications to 6 times / minute, the test temperature to 23–26°C, and the test duration to 24 hours. The viscosity of the flux applied in each case was measured every hour. Then, for each case, the time required for the viscosity of the flux to increase by 5 Pa·s from the start of application was defined as the continuous usage time.

[0234] (2) Judgment Criteria A. Continuous use time is more than 10 hours.

[0235] B. Continuous use time is more than 5 hours and less than 10 hours.

[0236] C. Continuous use time is less than 5 hours.

[0237] Evaluation of Glass Transition Temperature (1) Evaluation method The flux for each example was cured by standing at 170°C for 2 hours, and test pieces (18mm×5mm×5mm) were prepared for each example. The glass transition temperature was calculated for each test piece based on the measured value of the coefficient of linear expansion using a thermomechanical analysis apparatus (TMA, manufactured by HITACHI, SAT-5200).

[0238] The glass transition temperature is the temperature at which the measured value of the coefficient of linear expansion changes drastically. In the determination of the coefficient of linear expansion, the starting temperature is set to 0℃, the measurement temperature range is set to 0~200℃, and the heating rate is set to 5℃ / min.

[0239] (2) Judgment Criteria A has a glass transition temperature of 110℃ or higher.

[0240] B has a glass transition temperature of 90°C or higher but less than 110°C.

[0241] C has a glass transition temperature of less than 90℃.

[0242] [Table 1]

[0243] As shown in Table 1, the fluxes of Examples 1-4, which contain a specific coupling agent, exhibit improved shear strength compared to the fluxes of Comparative Examples 1-3, which do not contain a specific coupling agent.

[0244] [Table 2]

[0245] As shown in Table 2, the fluxes in Examples 7-10, which contain activators, have sufficient wettability.

[0246] [Table 3]

[0247] As shown in Table 3, the fluxes of Examples 13 and 14, which have a bisphenol-type epoxy resin / naphthalene-type epoxy resin mass ratio of 0.70 or more and 1.5 or less, exhibit superior viscosity, continuous use time, and glass transition temperature compared to Examples 11, 12, 15, and 16, which have a bisphenol-type epoxy resin / naphthalene-type epoxy resin mass ratio of less than 0.70 or greater than 1.5.

[0248] [Table 4]

[0249] As shown in Table 4, Examples 17 and 20, which contain guanidine, showed superior performance in terms of continuous use time and glass transition temperature compared to Examples 18 and 19, which contain curing agents other than guanidine.

[0250] Industrial applicability According to the present invention, a flux that can improve the bonding strength of solder joints even without the use of underfill adhesive, and a method for preparing a joint using the flux, are provided. This flux is suitable for mounting solder balls onto a chip.

[0251] Explanation of symbols 1. Scraper 2 workbenches 3. Flux (flux film) 4 Welding balls 5 chips 6 components 7 substrate 8 electrodes 9. Flux residue 10. Assembly

Claims

1. A flux comprising an epoxy resin, a curing agent for curing the epoxy resin, and an activator. The mass ratio of the epoxy resin content to the curing agent content, expressed as an epoxy resin / curing agent mass ratio, is 5 or more. in, The flux also contains a coupling agent. The coupling agent comprises a compound having a methoxy group. The compound is represented by the following general formula (C-1). The epoxy resin content is 50% by mass or more and 95% by mass or less relative to the total mass of the flux. [Chemical Formula 1] In the formula, R c1 R represents an alkyl group or hydrogen atom with 1 to 6 carbon atoms; c2 Represents an alkylene group or a single bond with 1 to 10 carbon atoms, wherein the methylene group constituting the alkylene group may be substituted with an oxygen atom; R c3 Indicates a group containing an epoxy group or a thiol group; n c m is an integer between 1 and 3. c n is an integer between 0 and 2. c +m c =3.

2. The flux according to claim 1, wherein, The epoxy resin includes 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 includes bisphenol-type epoxy resin and naphthalene-type epoxy resin. The mass ratio of bisphenol-type epoxy resin content to 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 curing agent contains an amine with a melting point of 190°C or higher.

6. The flux according to any one of claims 1 to 5, wherein, The curing agent contains guanidines.

7. The flux according to claim 1, wherein, The flux also contains an activator.

8. The flux according to any one of claims 1 to 7, wherein, The flux is used to bond components with solder balls to a substrate.

9. A method for preparing a bonding body, comprising: a step of treating the solder balls of a component having solder balls using the flux according to any one of claims 1 to 7; and a step of welding the component having solder balls to a substrate to obtain a bonding body.

Images