Underfill composition

Abstract

To provide an underfill composition which becomes a cured product having excellent dielectric characteristics (a low dielectric constant and a low dielectric loss tangent) and adhesiveness and is excellent in infiltrability.SOLUTION: The underfill composition contains the following components (A)-(F): (A) a biscitraconimide compound; (B) an epoxy resin; (C) an epoxy resin curing agent; (D) a curing accelerator; (E) one or more silane coupling agents represented by the following formula (1) (where each R independently represents a methyl group or an ethyl group; m represents a number of 8-12; and A represents a monovalent organic group having one functional group selected from an epoxy group, a glycidoxy group, an acryloxy group, a methacryloxy group and an amino group at a terminal thereof); and (F) spherical silica having an average particle diameter of 0.01-5 μm.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an underfill composition. [Background technology]

[0002] In electronic devices such as mobile communication devices, network infrastructure devices, and large computers, the speed and capacity of the signals they use is increasing year by year. In addition, new systems that handle high-frequency wireless signals are being put into practical use and planned for use in the ITS and indoor short-distance communications fields. As a result, the printed wiring boards mounted on these electronic devices must be capable of handling high frequencies in the 20 GHz range. Therefore, underfill materials are also required to have dielectric properties such as low dielectric constant and low dielectric tangent, which enable the reduction of transmission loss.

[0003] Known materials with low dielectric constants and low dielectric tangents include thermosetting resins such as modified polyphenylene ether resins and maleimide resins, and thermoplastic resins such as fluororesins, styrene resins, and liquid crystal polymers. However, these resins have high melt viscosities, and the resulting cured products are hard and brittle. In contrast, citraconic imide resins have low melt viscosities and give cured products with excellent dielectric properties and heat resistance (Patent Documents 1 and 2). However, these cured products have poor adhesion and do not have sufficient adhesive strength at high temperatures. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-018240 A [Patent Document 2] JP 2022-147022 A Summary of the Invention [Problem to be solved by the invention]

[0005] Accordingly, an object of the present invention is to provide an underfill composition with excellent penetration properties that gives a cured product with excellent dielectric properties (low dielectric constant and low dielectric tangent) and adhesive properties. [Means for solving the problem]

[0006] As a result of intensive research aimed at solving the above problems, the present inventors have found that the above object can be achieved by the following underfill composition containing a biscitraconimide compound and a silane coupling agent having a specific structure, and have completed the present invention. That is, the present invention provides the following underfill composition.

[0007] [1] An underfill composition comprising the following components (A) to (F) in the entire composition: (A) Biscitraconimide compound: 10 to 75% by mass (B) Epoxy resin: 0.1 to 75% by mass (C) Epoxy resin curing agent: an amount such that the molar equivalent ratio of epoxy reactive functional groups in component (C) per 1 mole of epoxy groups in component (B) is 0.1 to 8.0 (D) Curing accelerator: 0.0001~15% by mass (E) One or more silane coupling agents represented by the following formula (1): 0.1 to 5% by mass [ka] (In formula (1), R is independently a methyl group or an ethyl group. m is a number from 8 to 12. A is a monovalent organic group having at its terminal one functional group selected from an epoxy group, a glycidoxy group, an acryloxy group, a methacryloxy group, and an amino group.) (F) Spherical silica with an average particle size of 0.01 to 5 μm: 20 to 80% by mass [2] The underfill composition according to [1], wherein the (A) biscitraconimide compound is represented by the following formula (2): [ka] (In formula (2), B is a divalent organic group.) [3] The underfill composition according to [2], wherein B in formula (2) is a group selected from the group represented by the following structure and a hydrocarbon group derived from a dimer acid skeleton: [ka] (* means a bond with a nitrogen atom in a citraconimide group. n is 1 to 20.) [4] The underfill composition according to [3], wherein B in formula (2) is a group selected from aliphatic hydrocarbon groups represented by the following structures: [ka] (* means a bond with a nitrogen atom in a citraconimide group. n is 1 to 20.) [5] The underfill composition according to any one of [1] to [4], wherein component (A) has a number average molecular weight of 200 to 10,000. [6] (B) The underfill composition according to any one of [1] to [5], wherein the epoxy resin has two or more epoxy groups in one molecule. [7] The underfill composition according to any one of [1] to [6], wherein (C) the epoxy resin curing agent is at least one selected from an amine compound, a phenol compound, an acid anhydride compound, and an active ester compound. [8] The underfill composition according to any one of [1] to [7], wherein (D) the curing accelerator is at least one selected from the group consisting of imidazole curing accelerators, organophosphorus curing accelerators, and tertiary amine curing accelerators. [9] (F) The underfill composition according to any one of [1] to [8], wherein the spherical silica is sol-gel silica. Effect of the Invention

[0008] The underfill composition of the present invention has excellent penetration properties, and the cured product thereof has excellent dielectric properties (low dielectric constant and low dielectric tangent) and adhesive properties. Therefore, the composition of the present invention is useful for underfill applications. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described in detail below.

[0010] (A) Biscitraconimide compound The component (A) used in the present invention is a biscitraconimide compound. A citraconimide group is a maleimide group in which one hydrogen atom is replaced with a methyl group. Due to the effect of this methyl group, the compound not only exhibits a lower dielectric constant and a lower dielectric loss tangent than maleimide compounds of the same skeleton, but also has a lower melting point and improved compatibility with other components.

[0011] The biscitraconimide compound of component (A) is not particularly limited with respect to its properties at room temperature or number average molecular weight, but preferably has a number average molecular weight of 200 to 10,000, more preferably 200 to 5,000, and even more preferably 200 to 2,000. In this specification, the number average molecular weight is a number average molecular weight calculated using polystyrene standards and measured by gel permeation chromatography (GPC) under the following measurement conditions. [GPC measurement conditions] Developing solvent: Tetrahydrofuran (THF) Flow rate: 0.35mL / min Detector: Refractive index detector (RI) Column: TSK Guardcolumn SuperH-L TSKgel SuperHZ4000(4.6mmI.D.×15cm×1) TSKgel SuperHZ3000(4.6mmI.D.×15cm×1) TSKgel SuperHZ2000 (4.6mmI.D.×15cm×2) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 5 μL (0.2% by mass in THF solution)

[0012] The biscitraconimide compound of component (A) is preferably a biscitraconimide compound represented by the following formula (2) from the viewpoints of ease of procurement of the amine compound as the raw material, solubility of the biscitraconimide compound in a solvent, and ease of synthesis.

[0013] [ka] (In formula (2), B is a divalent organic group.)

[0014] In order to obtain low elasticity and excellent dielectric properties after curing (low relative dielectric constant and low dielectric tangent), the divalent organic group represented by B in the biscitraconimide compound is more preferably selected from the group represented by the following structure and a hydrocarbon group derived from a dimer acid skeleton.

[0015] [ka] (* means a bond with a nitrogen atom in a citraconimide group. n is 1 to 20.)

[0016] B in the above formula (2) is a group selected from aliphatic hydrocarbon groups represented by the following structures: [ka] (* means a bond with a nitrogen atom in a citraconimide group. n is 1 to 20.) Among B, aliphatic hydrocarbon groups that do not have an aromatic ring, such as groups derived from diamines such as 2-methyl-pentamethylenediamine, 2,2,4-trimethylhexamethylenediamine, and 1,4-cyclohexanedimethaneamine (i.e., groups obtained by removing the two amino groups of the diamines), are particularly preferred from the viewpoint of reducing the viscosity of the underfill composition.

[0017] Dimer acid is a liquid dibasic acid mainly composed of a dicarboxylic acid with 36 carbon atoms, produced by dimerization of unsaturated fatty acids with 18 carbon atoms, which are derived from natural products such as vegetable oils. The dimer acid skeleton is not a single skeleton, but has multiple structures, and there are several types of isomers. Representative dimer acids are classified as linear (a), monocyclic (b), aromatic (c), and polycyclic (d). In this specification, the dimer acid skeleton refers to a group derived from a dimer diamine having a structure in which the carboxy group of such a dimer acid is substituted with a primary aminomethyl group. That is, the hydrocarbon group derived from the dimer acid skeleton contained in the biscitraconimide compound of component (A) is preferably a branched divalent hydrocarbon group in which two carboxy groups are substituted with methylene groups in each of the dimer acids shown in (a) to (d) below. Furthermore, when the biscitraconimide compound of component (A) has a hydrocarbon group derived from a dimer acid skeleton, the hydrocarbon group derived from the dimer acid skeleton preferably has a structure in which the carbon-carbon double bond in the hydrocarbon group derived from the dimer acid skeleton is reduced by a hydrogenation reaction, from the viewpoint of the heat resistance and reliability of the cured product.

[0018] [ka]

[0019] The biscitraconimide compound of the component (A) may be used alone or in combination of two or more kinds.

[0020] In the underfill composition of the present invention, the proportion of component (A) in the entire composition is preferably 10 to 75 mass %, more preferably 20 to 65 mass %, and even more preferably 30 to 50 mass %.

[0021] (B) Epoxy resin The epoxy resin (B) is added for the purpose of promoting the reaction of the biscitraconimide compound (A) above.

[0022] The epoxy resin preferably has two or more epoxy groups in one molecule, and any conventionally known epoxy resin can be used. Examples of the epoxy resin include bisphenol-type epoxy resins such as bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and bisphenol S-type epoxy resins; novolac-type epoxy resins such as phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, bisphenol A novolac-type epoxy resins, and bisphenol F novolac-type epoxy resins; alicyclic epoxy resins such as dicyclopentadiene-type epoxy resins and 3,4-epoxycyclohexenylmethyl-3',4'-epoxycyclohexenecarboxylate; polyfunctional phenol-type epoxy resins such as resorcinol-type epoxy resins and resorcinol novolac-type epoxy resins; stilbene-type epoxy resins, triazine skeleton-containing epoxy resins, fluorene skeleton-containing epoxy resins, triphenol alkane-type epoxy resins, biphenyl-type epoxy resins, xylylene-type epoxy resins, biphenyl aralkyl-type epoxy resins, naphthalene-type epoxy resins, and diglycidyl ether compounds of polycyclic aromatics such as anthracene, and phosphorus-containing epoxy resins obtained by introducing a phosphorus compound into these. Among these, bisphenol A type epoxy resins, dicyclopentadiene type epoxy resins, biphenylaralkyl type epoxy resins and naphthalene type epoxy resins are preferably used. These may be used alone or in combination of two or more.

[0023] The proportion of component (B) in the entire composition is 0.1 to 75 mass%, preferably 0.5 to 50 mass%, and more preferably 1 to 25 mass%. When the amount of epoxy resin (B) blended is within this range, a cured product having low dielectric properties (low dielectric constant and low dielectric tangent) can be obtained.

[0024] (C) Epoxy resin hardener The epoxy resin curing agent (C) is added for the purpose of reacting with the epoxy group contained in the epoxy resin (B). The epoxy resin curing agent may have a functional group that reacts with the epoxy group, and among them, at least one selected from amine compounds, phenol compounds, acid anhydride compounds, and active ester compounds is preferable. Among them, phenol compounds are more preferable from the viewpoint of the dielectric properties of the composition.

[0025] The amine compound may be a generally known one. From the viewpoint of handling property and moisture resistance reliability, aromatic amine compounds are preferred. For example, aromatic diaminodiphenylmethane compounds such as 3,3'-diethyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetraethyl-4,4'-diaminodiphenylmethane; 2,4-diaminotoluene, 1,4-diaminobenzene, 1,3-diaminobenzene, etc. are preferred, and more preferred are aromatic diaminodiphenylmethane compounds such as 3,3'-diethyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetraethyl-4,4'-diaminodiphenylmethane. These may be used alone or in combination of two or more.

[0026] The amine compound may be liquid or solid at room temperature (20 to 30°C). There is no problem in blending the amine compound as it is, but blending the solid amine compound as it is increases the viscosity of the resin composition, which significantly deteriorates the workability. Therefore, it is preferable to melt-mix the amine compound with the epoxy resin in advance, and it is preferable to melt-mix the amine compound with the epoxy resin in a specific blending ratio described later at a temperature range of 70 to 150°C for 1 to 2 hours. If the mixing temperature is less than 70°C, the amine compound may not be sufficiently compatible, and if the temperature exceeds 150°C, the amine compound may react with the epoxy resin and increase the viscosity. In addition, if the mixing time is less than 1 hour, the amine compound may not be sufficiently compatible, which may lead to an increase in viscosity, and if the mixing time exceeds 2 hours, the amine compound may react with the epoxy resin and increase the viscosity.

[0027] The phenol compound may be a generally known one. For example, phenol novolac resin, naphthalene ring-containing phenol resin, aralkyl type phenol resin, triphenol alkane type phenol resin, biphenyl skeleton-containing aralkyl type phenol resin, biphenyl type phenol resin, alicyclic phenol resin, heterocyclic phenol resin, naphthalene ring-containing phenol resin, resorcinol type phenol resin, allyl group-containing phenol resin such as novolac type allyl phenol resin, bisphenol type phenol resin such as bisphenol A type resin and bisphenol F type resin, etc. may be mentioned. These may be used alone or in combination of two or more.

[0028] The acid anhydride compound can be a generally known one. For example, 4-methylcyclohexane-1,2-dicarboxylic anhydride, 3,4-dimethyl-6-(2-methyl-1-propenyl)-1,2,3,6-tetrahydrophthalic anhydride, 1-isopropyl-4-methyl-bicyclo[2.2.2]oct-5-ene-2,3-dicarboxylic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, methylhimic anhydride, pyromellitic dianhydride, maleic alloocimene, benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetrabisbenzophenonetetracarboxylic dianhydride, (3,4-dicarboxyphenyl)ether dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, etc. can be mentioned. These may be used alone or in combination of two or more.

[0029] The active ester compound can be generally known. For example, the active ester compound includes a dicyclopentadiene type phenolic resin structure, an active ester compound including a phenol novolac structure, an active ester compound including a naphthalene ring structure, an active ester compound including an aralkyl type phenolic resin structure, an active ester compound including a triphenolalkane type phenolic resin structure, an active ester compound including a biphenyl skeleton-containing aralkyl type phenolic resin structure, an active ester compound including a biphenyl type phenolic resin structure, an active ester compound including an alicyclic phenolic resin structure, an active ester compound including a heterocyclic phenolic resin structure, an active ester compound including a naphthalene ring-containing phenolic resin structure, an active ester compound including a resorcinol type phenolic resin structure, an active ester compound including an allyl group-containing phenolic resin structure, an active ester compound including a bisphenol A type resin structure, an active ester compound including a bisphenol type phenolic resin structure such as a bisphenol F type resin, etc. These may be used alone or in combination of two or more.

[0030] The amount of the epoxy resin curing agent is such that the molar equivalent ratio of the functional group in the epoxy resin curing agent to 1 molar equivalent of the epoxy group in the component (B) is 0.1 to 8.0, preferably 0.5 to 6.0, and particularly preferably 1.0 to 4.0. If the molar equivalent ratio is less than 0.1, unreacted epoxy groups remain, and adhesion may decrease, while if it exceeds 8.0, the moisture absorption rate of the cured product increases, and cracks may occur during reflow or temperature cycles. In the present invention, the equivalent weight is the molecular weight per functional group.

[0031] (D) Curing accelerator The curing accelerator of component (D) may be any that accelerates the curing of the biscitraconimide compound (A), and may be any commonly known accelerator, such as an imidazole-based curing accelerator, an organic phosphorus-based curing accelerator, a tertiary amine-based curing accelerator, etc. Among them, it is preferable to use an imidazole-based curing accelerator for the purpose of suppressing the viscosity of the composition. Examples of the curing accelerator of component (D) include phosphines such as triphenylphosphine, tributylphosphine, tri(p-methylphenyl)phosphine, and tri(nonylphenyl)phosphine; phosphine-borane complexes such as triphenylphosphine-triphenylborane; and phosphonium borane complexes such as tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, p-tolyltriphenylphosphonium tetra-p-tolylborate, and tri-tert-butylphosphonium tetraphenylborate. phosphate salts; organic phosphorus compounds such as bis(tetrabutylphosphonium)dihydrogenpyromellitate; tertiary amine compounds such as triethylamine, benzyldimethylamine, α-methylbenzyldimethylamine, and 1,8-diazabicyclo[5.4.0]undecene-7; salts of tertiary amine compounds such as 1,8-diazabicyclo[5.4.0]undecene-7; imidazole compounds such as 2-methylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, and 2-phenyl-4-methylimidazole. Among these, salts of tertiary amine compounds and organic phosphorus compounds are preferred, and salts of 1,8-diazabicyclo[5.4.0]undecene-7 and tetraphenylphosphonium tetraphenylborate are more preferred. The component (D) may use either a single type alone, or a combination of two or more types.

[0032] The proportion of the component (D) in the entire composition is from 0.0001 to 15 mass %, preferably from 0.001 to 10 mass %, and more preferably from 0.01 to 5 mass %.

[0033] (E) Silane coupling agent (E) The silane coupling agent is added for the purpose of improving the adhesion of the underfill composition to the substrate.

[0034] The silane coupling agent used in the present invention contains one or more compounds represented by the following formula (1). [ka] (In formula (1), R is each independently an alkyl group having 1 or 2 carbon atoms. m is a number from 8 to 12. A is a monovalent organic group having at its terminal one functional group selected from an epoxy group, a glycidoxy group, an acryloxy group, a methacryloxy group, and an amino group.)

[0035] Examples of the silane coupling agent of the component (E) include (9,10-epoxydecyl)trimethoxysilane, (9,10-epoxydecyl)triethoxysilane, (11,12-epoxydodecyl)trimethoxysilane, 8-glycidoxyoctyltrimethoxysilane, 8-glycidoxyoctyltriethoxysilane, 11-glycidoxyundecyltrimethoxysilane, 8-acryloxyoctyltrimethoxysilane, 8-acryloxyoctyltriethoxysilane, Examples of silane coupling agents include 8-methacryloxyoctyltrimethoxysilane, 8-methacryloxyoctyltriethoxysilane, 11-methacryloxyundecyltrimethoxysilane, 8-aminooctyltrimethoxysilane, 11-aminoundecyltrimethoxysilane, 8-aminooctyltriethoxysilane, N-2-(aminoethyl)-8-aminooctyltrimethoxysilane, and N-2-(aminoethyl)-8-aminooctyltriethoxysilane.

[0036] The silane coupling agent may be a compound represented by the above formula (1) that can be used alone, or a combination of two or more types including a silane coupling agent other than the compound represented by the above formula (1) may be used.

[0037] Silane coupling agents other than the compound represented by the above formula (1) are not particularly limited, and examples thereof include n-propyltrimethoxysilane, n-propyltriethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, 2-[methoxy(polyethyleneoxy)propyl]-trimethoxysilane, methoxytri(ethyleneoxy)propyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, and 3-isocyanatopropyltrimethoxysilane.

[0038] The proportion of the component (E) represented by formula (1) in the entire composition is 0.1 to 5 mass%, preferably 0.5 to 3 mass%, and the proportion of the silane coupling agent other than formula (1) in the entire composition is preferably 0 to 5 mass%, more preferably 0.1 to 3 mass%, of the total amount of the resin composition.

[0039] (F) Spherical silica (F) Spherical silica is added for the purposes of improving the resin strength of the underfill composition and reducing thermal expansion. The spherical silica used in the present invention has an average particle size of 0.01 to 5 μm. This average particle size is the volume average median diameter (d50) measured by a laser diffraction particle size distribution measuring device, and is preferably 0.05 to 2 μm.

[0040] (F) In order to control the average particle size and particle size distribution of spherical silica, the sol-gel method or the deflagration method is most suitable. The spherical silica produced by these methods has a true sphere compared to fused silica, and has the advantage that the particle size distribution can be easily designed. The sol-gel method and the deflagration method may be conventionally known methods. Among them, it is more preferable to use silica produced by the sol-gel method from the viewpoint of penetration into thin films.

[0041] It is preferable that 80% by mass or more, particularly 90 to 100% by mass, and especially 95 to 100% by mass of the (F) spherical silica is spherical silica produced by a sol-gel method. If it is 80% by mass or more, the flowability of the underfill composition is good.

[0042] The amount of (F) spherical silica is 20 to 80% by mass, and preferably 40 to 60% by mass, when the total amount of all components in the composition is 100% by mass. If it is less than 20% by mass, the expansion coefficient of the cured product may be large. If it exceeds 80% by mass, the viscosity of the underfill composition may be high, which may reduce its penetration into gaps.

[0043] In order to strengthen the bond strength between the spherical silica and the (A) and (B) components, it is preferable to use the spherical silica that has been surface-treated in advance with a coupling agent such as a silane coupling agent or a titanate coupling agent. Examples of such coupling agents include epoxy silanes such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino silanes such as N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, reaction product of imidazole and 3-glycidoxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane; and mercapto silanes such as 3-mercaptopropyltrimethoxysilane and 3-episulfidoxypropyltrimethoxysilane. The amount of the coupling agent used for the surface treatment and the surface treatment method are not particularly limited.

[0044] [Other additives] In addition to the above components (A) to (F), other additives may be added to the underfill composition of the present invention as necessary within the scope of not impairing the objects and effects of the present invention. Such additives include inorganic fillers other than component (F), flame retardants, ion trapping agents, antioxidants, adhesion promoters, stress reducing agents, colorants, etc.

[0045] Examples of inorganic fillers other than component (F) include silicas such as fused silica and crystalline silica, alumina, silicon nitride, aluminum nitride, boron nitride, barium sulfate, talc, clay, aluminum hydroxide, magnesium hydroxide, calcium carbonate, glass fibers, and glass particles. In addition, fluorine-containing resins, coating fillers, and / or hollow particles may be used to improve dielectric properties, and conductive fillers such as metal particles, metal-coated inorganic particles, carbon fibers, and carbon nanotubes may be added to provide conductivity. The inorganic fillers may be used alone or in combination of two or more.

[0046] The flame retardant is added for the purpose of imparting flame retardancy. There is no particular limitation on the flame retardant, and any known flame retardant can be used, such as a phosphazene compound, a silicone compound, zinc molybdate-supported talc, zinc molybdate-supported zinc oxide, aluminum hydroxide, magnesium hydroxide, or molybdenum oxide.

[0047] The ion trapping agent is added for the purpose of trapping ion impurities contained in the resin composition and preventing thermal deterioration and moisture absorption deterioration. The ion trapping agent is not particularly limited and any known agent can be used, and hydrotalcites, bismuth hydroxide compounds, rare earth oxides, etc. may be used.

[0048] The antioxidant is not particularly limited, and examples thereof include n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, n-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)acetate, neododecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, dodecyl-2-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, ethyl Octadecyl-1-(4-hydroxy-3,5-di-t-butylphenyl)isobutyrate, Octadecyl-1-(4-hydroxy-3,5-di-t-butylphenyl)isobutyrate, Octadecyl-1-(4-hydroxy-3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2-(n-octylthio)ethyl-3,5-di-t-butyl-4-hydroxyphenylacetate, 2-(n-octadecylthio)ethyl-3, 5-di-t-butyl-4-hydroxyphenyl acetate, 2-(n-octadecylthio)ethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2-(2-stearoyloxyethylthio)ethyl-7-(3-methyl-5-t-butyl-4-hydroxyphenyl)heptanoate, 2-hydroxyethyl-7-(3-methyl-5-t-butyl-4-hydroxyphenyl)propionate, pentaethyl Phenolic antioxidants such as rhythritol tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]; sulfur-based antioxidants such as dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, and pentaerythrityl tetrakis (3-laurylthiopropionate);Examples of phosphorus-based antioxidants include tridecyl phosphite, triphenyl phosphite, tris(2,4-di-t-butylphenyl)phosphite, 2-ethylhexyl diphenyl phosphite, diphenyl tridecyl phosphite, 2,2-methylene bis(4,6-di-t-butylphenyl)octyl phosphite, distearyl pentaerythritol diphosphite, bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, and 2-[[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f][1,3,2]dioxaphosphepin-6-yl]oxy]-N,N-bis[2-[[2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f][1,3,2]dioxaphosphepin-6-yl]oxy]-ethyl]ethanamine.

[0049] The amount of other additives to be added varies depending on the purpose of the composition, but is generally 10% by mass or less of the total composition.

[0050] [Method of producing the composition] The underfill composition of the present invention can be prepared by the following method. For example, the components (A) to (F) are mixed, simultaneously or separately, while being heated as necessary, and stirred, dissolved and / or dispersed to obtain a mixture of the components (A) to (F). Preferably, the mixture of the components (A) to (F) may be obtained by adding the epoxy resin curing agent (C) to a mixture of the components (A), (B), (D), (E) and (F), and stirring, dissolving and / or dispersing the mixture. Depending on the intended use, at least one of a flame retardant, a polymerization initiator and an ion trapping agent may be added to and mixed with the mixture of the components (A) to (F). Each component may be used alone or in combination of two or more.

[0051] In the method for producing the composition, the device for mixing, stirring, and dispersing is not particularly limited. Specifically, for example, a mortar and pestle machine equipped with a stirring and heating device, a two-roll mill, a three-roll mill, a ball mill, a planetary mixer, or a mass colloider may be used, and these devices may be used in appropriate combination.

[0052] [Cured product of underfill composition] The curing and molding method and curing and molding conditions of the underfill composition of the present invention may be known, but preferably, a thermal oven cure is first performed at 100-120°C for 0.5 hours or more, and then at 150-175°C for 3 hours or more. Heating at 100-120°C for 0.5 hours or more can suppress the generation of voids after curing. Furthermore, heating at 150-175°C for 3 hours or more can provide sufficient cured product properties. EXAMPLES

[0053] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In Tables 1 and 2, the blend amounts are shown in parts by mass.

[0054] The components used in the examples and comparative examples are shown below. In the following, the number average molecular weight (Mn) was measured by gel permeation chromatography (GPC) using polystyrene as the standard under the following measurement conditions. [GPC measurement conditions] Developing solvent: Tetrahydrofuran (THF) Flow rate: 0.35mL / min Detector: Refractive index detector (RI) Column: TSK Guardcolumn SuperH-L TSKgel SuperHZ4000(4.6mmI.D.×15cm×1) TSKgel SuperHZ3000(4.6mmI.D.×15cm×1) TSKgel SuperHZ2000 (4.6mmI.D.×15cm×2) (All manufactured by Tosoh Corporation) Column temperature: 40℃ Sample injection volume: 5 μL (0.2% by mass in THF solution)

[0055] (A) Biscitraconimide compound Synthesis Example 1 (Production of biscitraconimide compound) A 2L glass four-neck flask equipped with a stirrer, a Dean-Stark tube, a cooling condenser and a thermometer was charged with 52.29g (0.45 mol) of 2-methylpentamethylenediamine, 111.0g (0.99 mol) of citraconic anhydride and 150g of toluene to prepare a reaction solution, which was then stirred at 80°C for 3 hours to synthesize an amic acid. After that, 40g of methanesulfonic acid was added to the reaction solution, which was then heated to 110°C and stirred for 16 hours while distilling off the by-product water, and the reaction solution was washed five times with 200g of ion-exchanged water. After that, a reduced pressure strip at 60°C was performed to obtain 130.1g (yield 95%) of the target product ((A1), number average molecular weight 510) in the form of a brown liquid at room temperature (25°C). [ka]

[0056] Synthesis Example 2 (Production of biscitraconimide compound) A 2L glass four-neck flask equipped with a stirrer, a Dean-Stark tube, a cooling condenser and a thermometer was charged with 71.2g (0.45 mol) of 2,2,4-trimethylhexamethylenediamine, 111.0g (0.99 mol) of citraconic anhydride and 150g of toluene to prepare a reaction solution, which was then stirred at 80°C for 3 hours to synthesize an amic acid. After that, 40g of methanesulfonic acid was added to the reaction solution, which was then heated to 110°C and stirred for 16 hours while distilling off the by-product water, and the reaction solution was washed five times with 200g of ion-exchanged water. After that, a reduced pressure strip at 60°C was performed to obtain 149.7g (yield 96%) of the target product ((A2), number average molecular weight 590) in the form of a brown liquid at room temperature (25°C). [ka]

[0057] (B) Epoxy resin (B1) Bisphenol A type epoxy resin (jER828EL: manufactured by Mitsubishi Chemical Corporation, liquid at 25°C, epoxy group equivalent 189) (B2) Biphenyl aralkyl type epoxy resin (NC-3000: manufactured by Nippon Kayaku Co., Ltd., softening point 56°C, epoxy group equivalent 273)

[0058] (C) Epoxy resin hardener (C1) Novolac-type allylphenol resin (MEH-8000H: manufactured by Meiwa Kasei Co., Ltd., phenol hydroxyl group equivalent: 141) (C2) 3,3'-diethyl-4,4'-diaminodiphenylmethane (Kayahard AA, manufactured by Nippon Kayaku Co., Ltd., amino group equivalent: 63.5) (C3) 4-Methylcyclohexane-1,2-dicarboxylic anhydride (Rikacid MH: manufactured by New Japan Chemical Co., Ltd., acid anhydride equivalent: 168) (C4) Active ester compound containing a dicyclopentadiene-type phenolic resin structure (HPC-8000-65T: manufactured by DIC Corporation, active ester group equivalent 223, toluene varnish / solid content 65%) Tables 1 and 2 are shown in terms of solid content.

[0059] (D) Curing accelerator (D1) 2-Ethyl-4-methylimidazole (2E4MZ: manufactured by Shikoku Kasei Holdings Co., Ltd.) (D2) 2-Phenyl-4-methylimidazole (2P4MZ: Shikoku Kasei Holdings Co., Ltd.) (D3) Bis(tetrabutylphosphonium) dihydrogen pyromellitate (BTBP-pyromellitic acid: manufactured by Hokko Chemical Industry Co., Ltd.) (D4) Trimellitic acid salt (36%) and phenolic resin salt (46%) of 1,8-diazabicyclo[5.4.0]undecene-7 (DBU) (U-CAT SA838A: San-Apro Co., Ltd.)

[0060] (E) Silane coupling agent (E1) 8-Glycidoxyoctyltrimethoxysilane (KBM-4803: manufactured by Shin-Etsu Chemical Co., Ltd.) (E2) 8-Methacryloxyoctyltrimethoxysilane (KBM-5803: manufactured by Shin-Etsu Chemical Co., Ltd.) (E3) N-2-(aminoethyl)-8-aminooctyltrimethoxysilane (KBM-6803: manufactured by Shin-Etsu Chemical Co., Ltd.) (E4) 3-Glycidoxypropyltrimethoxysilane (KBM-403: Shin-Etsu Chemical Co., Ltd.)

[0061] (F) Spherical silica (F1) Spherical sol-gel silica (KE-S150: manufactured by Nippon Shokubai Co., Ltd., average particle size 1.5 μm) (F2) Spherical silica produced by the deflagration method (SO-E4-SX: manufactured by Admatechs Co., Ltd., average particle size 1.0 μm)

[0062] The above components were mixed in the amounts (parts by mass) shown in Tables 1 and 2 to obtain underfill compositions. Each composition and the cured product of each composition were evaluated for penetration, dielectric constant, dielectric tangent, and adhesion by the methods shown below. The results are shown in Tables 1 and 2. The "equivalent ratio" shown in Tables 1 and 2 refers to the ratio of the molar equivalent (active hydrogen equivalent) of the functional group of the epoxy resin curing agent in component (C) to 1 molar equivalent of the epoxy group contained in the epoxy resin in component (B).

[0063] 1. Penetration test A test piece with a 50 μm gap was prepared by sandwiching and fixing two 30 mm × 50 mm glass plates with a 50 μm thick polyimide tape. The test piece was heated to 120° C., and each underfill composition of the examples and comparative examples was poured into the gap, and the time required for the composition to penetrate 30 mm was measured. The time to reach 30 mm was evaluated as "Good" when it took 180 seconds or less, "Fair" when it took more than 180 seconds, and "Poor" when it did not reach 30 mm.

[0064] 2. Dielectric constant and dielectric tangent A frame with a diameter of 200 mm and a thickness of 150 μm was prepared, and each underfill composition of the Examples and Comparative Examples was sandwiched between a 50 μm-thick release-treated PET film (E7006, manufactured by Toyobo) and molded using a vacuum press (manufactured by Nikko Materials) at 180°C for 5 minutes to obtain a cured product. The cured product was removed from the PET film and further cured at 165°C for 3 hours to obtain a cured resin film. Using the cured resin film, a network analyzer (E5063-2D5 manufactured by Keysight Corporation) was connected to a strip line (manufactured by Keycom Corporation) to measure the relative dielectric constant and dielectric loss tangent of the cured resin film at a frequency of 10 GHz.

[0065] 3. Measurement of Adhesion Each underfill composition was applied to a 10 mm x 10 mm silicon wafer, a 2 mm x 2 mm silicon chip was placed on top of it, and then cured under the above-mentioned curing conditions to prepare a test piece for adhesion testing. The test piece was left on a stage at 260°C for 40 seconds using a bond tester DAGE-SERIES-4000PXY (manufactured by DAGE), after which the shear adhesive strength was measured and recorded as the initial value. The adhesive area between the frame and resin of the test piece was 4 mm 2 It was. The test pieces were then heated in a pressure cooker at 121°C for 2.03×10 5 After exposure to saturated water vapor at 10 Pa for 72 hours, the specimen was cooled to room temperature and the shear adhesive strength was measured in the same manner as above. The adhesive strength retention rate after storage at high temperature and high humidity was (121°C, 2.03×10 5 The shear adhesive strength at 260°C after 72 hours of exposure to saturated water vapor at 100 Pa was calculated as (shear adhesive strength at 260°C after 72 hours of exposure) / initial value × 100 (%). The initial adhesive strength of each test piece and the adhesive strength retention after storage at high temperature and high humidity are shown in Tables 1 and 2.

[0066] [Table 1] [Table 2]

[0067] From the results of Tables 1 and 2, it is clear that the underfill composition containing the biscitraconimide compound, the epoxy resin, the epoxy resin curing agent, the curing accelerator, the silane coupling agent having a specific structure, and the spherical silica has both penetration into the thin film, excellent dielectric properties (low relative dielectric constant and low dielectric tangent) of the cured product, and high adhesion to the substrate. Therefore, the composition of the present invention is useful for underfill applications.

Claims

1. An underfill composition comprising the following components (A) to (F) in the entire composition: (A) Biscitraconimide compound: 10 to 75% by mass (B) Epoxy resin: 0.1 to 75% by mass (C) Epoxy resin curing agent: an amount such that the molar equivalent ratio of epoxy-reactive functional groups in component (C) per 1 mole of epoxy groups in component (B) is 0.1 to 8.0 (D) Curing accelerator: 0.0001 to 15% by mass (E) One or more silane coupling agents represented by the following formula (1): 0.1 to 5 mass% 【Chemistry 1】 (In formula (1), each R is independently a methyl group or an ethyl group; m is a number from 8 to 12; and A is a monovalent organic group having at its terminal one functional group selected from an epoxy group, a glycidoxy group, an acryloxy group, a methacryloxy group, and an amino group.) (F) Spherical silica having an average particle size of 0.01 to 5 μm: 20 to 80% by mass

2. 2. The underfill composition according to claim 1, wherein the biscitraconimide compound (A) is represented by the following formula (2): 【Chemistry 2】 (In formula (2), B is a divalent organic group.)

3. 3. The underfill composition according to claim 2, wherein B in formula (2) is a group selected from the group represented by the following structure and a hydrocarbon group derived from a dimer acid skeleton. 【Chemistry 3】 (* means a bond with a nitrogen atom in a citraconimide group. n is 1 to 20.)

4. 4. The underfill composition according to claim 3, wherein B in formula (2) is a group selected from aliphatic hydrocarbon groups represented by the following structures: 【Chemistry 4】 (* means a bond with a nitrogen atom in a citraconimide group. n is 1 to 20.)

5. 2. The underfill composition according to claim 1, wherein the number average molecular weight of component (A) is 200 to 10,000.

6. 2. The underfill composition according to claim 1, wherein the epoxy resin (B) has two or more epoxy groups in one molecule.

7. 2. The underfill composition according to claim 1, wherein the epoxy resin curing agent (C) is at least one selected from the group consisting of amine compounds, phenol compounds, acid anhydride compounds and active ester compounds.

8. 2. The underfill composition according to claim 1, wherein the curing accelerator (D) is at least one selected from the group consisting of imidazole curing accelerators, organophosphorus curing accelerators, and tertiary amine curing accelerators.

9. 2. The underfill composition according to claim 1, wherein the spherical silica (F) is a sol-gel silica.

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