Resin composition and cured film

Abstract

The purpose of the present invention is to provide a resin composition capable of forming a cured film having high puncture strength. The resin composition includes an epoxy resin, alumina particles, and a flux, and has a value Z, which is obtained from formula (1), of 220 (g0.5×m / mol) or less.　Formula (1): Z = S0.5 × E [In formula (1), S represents the BET specific surface area (m2 / g) of the alumina particles as measured by a nitrogen adsorption method, and E represents the acid equivalent weight of the flux (g / mol).]

Description

Resin composition and cured film

[0001] This disclosure relates to a resin composition and a cured film.

[0002] In recent years, with the advancement of high integration and miniaturization of semiconductor devices, advanced packaging technologies such as flip-chip mounting technology and fan-out wafer-level packaging (FOWLP) have been widely adopted. In these technologies, underfill materials play an important role in ensuring high reliability of the connection between the chip and the substrate. Underfill materials such as capillary underfill (CUF), non-conductive paste (NCP), and non-conductive film (NCF) are used, and examples of such underfill materials are known, such as those described in Patent Document 1.

[0003] Patent No. 3606253

[0004] With advancements in packaging technology, the integration and high-density mounting of individual components are accelerating. This technological evolution necessitates higher performance characteristics for underfill materials than ever before. In particular, underfill materials connecting chips and substrates are essential for ensuring reliability in highly integrated and high-density mounting applications, and must possess high mechanical strength against stress in the thickness direction caused by external shocks and vibrations. However, no material is known that satisfies these sufficient mechanical properties, making the development of underfill materials suitable for highly integrated and high-density mounting a challenge. The inventors focused on the fact that puncture strength is a suitable indicator for evaluating the thickness-direction strength of underfill materials and conducted diligent research.

[0005] This invention was made against the backdrop of the aforementioned technical problems. In other words, the object of this invention is to provide a resin composition capable of forming a cured film with high puncture strength.

[0006] The inventors of this invention conducted intensive research, focusing particularly on puncture strength among mechanical strengths. As a result, they discovered that by keeping the BET specific surface area S, measured by the nitrogen adsorption method of alumina particles, and the value Z, calculated based on the acid equivalent E of the flux, below a predetermined value, a resin composition capable of forming a cured film with high puncture strength can be obtained, thus completing the present invention.

[0007] The present invention, which has achieved the above objectives, is as follows: [1] A material comprising epoxy resin, alumina particles and flux, wherein the value Z obtained from formula (1) is 220 (g ０．５ A resin composition having a concentration of less than or equal to × m / mol. Z = S 0.5 ×E …(1) [In formula (1), S is the BET specific surface area (m²) measured by the nitrogen adsorption method of the alumina particles. ２ [1] The resin composition according to [1], wherein the volume-based D50 in the cumulative particle size distribution of the alumina particles is 3.0 μm or less. [3] The alpha dose of the alumina particles is 0.006 cph / cm². ２ The resin composition according to [1] or [2] below. [4] The BET specific surface area S is 0.9 m ２[1] to [3] or more resin composition. [5] A resin composition according to any one of [1] to [4], wherein the epoxy resin is a polyfunctional epoxy resin. [6] A resin composition according to any one of [1] to [5], wherein the flux is a carboxylic acid. [7] A resin composition according to any one of [1] to [6], wherein the flux content is 0.5 to 20 parts by mass per 100 parts by mass of the alumina particles. [8] A resin composition according to any one of [1] to [7], wherein it may further contain inorganic particles (excluding alumina particles), and the content of the alumina particles is 50% by mass or more of the total of the alumina particles and the inorganic particles (excluding alumina particles) in a total of 100% by mass. [9] A resin composition according to any one of [1] to [8], further containing a curing accelerator.

[10] A resin composition according to any one of [1] to [9], for semiconductor encapsulation.

[11] The resin composition according to

[10] for pre-supplied underfill.

[12] A cured film of the resin composition according to any one of [1] to [9].

[0008] The present invention provides a resin composition capable of forming a cured film with high puncture strength.

[0009] <Resin Composition> The resin composition according to the present invention comprises an epoxy resin, alumina particles, and flux, and the value Z obtained from formula (1) is 220 (g ０．５ It is characterized by being less than or equal to × m / mol. By keeping the value Z below the upper limit, the puncture strength of the cured film formed from the resin composition can be increased. Z = S 0.5 ×E …(1) [In formula (1), S is the BET specific surface area (m²) measured by the nitrogen adsorption method of the alumina particles. ２ E represents the amount (g / g) and E represents the acid equivalent (g / mol) of the flux.

[0010] The value Z obtained from the BET specific surface area of alumina particles measured by the nitrogen adsorption method and the acid equivalent of the flux is presumed to affect the dispersibility of the alumina particles and the flux in the resin composition. When the value Z is equal to or less than the upper limit, the amount of flux adsorbed on the surface of the alumina particles tends to be maintained at an appropriate level, so the dispersibility of the alumina particles in the resin composition becomes good, and aggregation of the alumina particles is suppressed. This is considered to allow the cured film to exhibit excellent puncture strength. From the viewpoint of improving the dispersibility of alumina particles in the resin composition, the value Z is preferably 210 (g ０．５ ×m / mol) or less, more preferably 200 (g ０．５ ×m / mol) or less, still more preferably 190 (g ０．５ ×m / mol) or less, even more preferably 180 (g ０．５ ×m / mol) or less. From the viewpoint of increasing the glass transition temperature (Tg) of the cured film, the lower limit of the value Z is preferably 50 (g ０．５ ×m / mol) or more, more preferably 60 (g ０．５ ×m / mol) or more, still more preferably 70 (g ０．５ ×m / mol) or more, particularly preferably 75 (g ０．５ ×m / mol) or more, and may be 100 (g ０．５ ×m / mol) or more, or 110 (g ０．５ ×m / mol) or more. When the value Z is equal to or higher than the lower limit, intermolecular force acts between the alumina particles and the flux, so the flux is more likely to be adsorbed onto the alumina particles. Since the flux is easily adsorbed onto the alumina particles, the amount of flux taken into the epoxy resin in the resin composition during curing decreases, so a crosslinked structure of the epoxy resin is easily formed at high density, and the molecular mobility of the epoxy resin is restricted. This is considered to make it easier for the Tg of the cured film to improve.

[0011] Hereinafter, the components contained in the resin composition will be described in detail. Unless otherwise specified, the compounds exemplified as each component may be used alone or in combination of two or more. In the present disclosure, the term "resin composition" is a concept that broadly encompasses varnishes, paste-like resin compositions, sheet-like resin compositions, etc., and refers to a resin composition before curing.

[0012] <Epoxy Resin> The term "epoxy resin" is used herein to mean both an epoxy compound having an epoxy group and a polymer of the epoxy compound. Any epoxy resin containing an epoxy group (preferably a glycidyl group) in the molecule can be used without particular limitation. As the epoxy resin, a polyfunctional epoxy resin having 2 or more (preferably 2 to 6, more preferably 2 to 5, still more preferably 2 to 4) epoxy groups (preferably glycidyl groups) in the molecule is preferred. A polyfunctional epoxy resin can form a high-density crosslinked structure, and the cured film after curing has good puncture strength and further heat resistance.

[0013] From the viewpoint of improving the puncture strength of the cured film and further enhancing heat resistance, the epoxy resin preferably contains a trifunctional epoxy resin having 3 or more glycidyl groups in the molecule, and more preferably contains a trifunctional epoxy resin having 3 glycidyl groups in the molecule. Further, in order to improve the puncture strength and heat resistance of the cured film, it is further preferable that the epoxy resin includes two types of the above-mentioned trifunctional epoxy resin and a difunctional epoxy resin having two glycidyl groups in the molecule. When the resin composition contains these two types of polyfunctional epoxy resins, the content of the trifunctional epoxy resin is preferably 50 parts by mass or more and 500 parts by mass or less, more preferably 100 parts by mass or more and 400 parts by mass or less, and still more preferably 150 parts by mass or more and 300 parts by mass or less, relative to 100 parts by mass of the difunctional epoxy resin.

[0014] The epoxy equivalent of the epoxy resin is preferably 50 g / eq or more and 300 g / eq or less, more preferably 60 g / eq or more and 250 g / eq or less, and still more preferably 70 g / eq or more and 200 g / eq or less. Within the above range, a cured film having high puncture strength and excellent heat resistance can be formed. Note that when two or more types of epoxy resins are contained in the resin composition, the epoxy equivalent of the epoxy resin is calculated with W being the blending amount of component i ｉ (g), and E being the epoxy equivalent ｉ (g / eq), according to Σ(W ｉ ) / Σ(W ｉ / E ｉ ).

[0015] Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol AP type epoxy resin, bisphenol AF type epoxy resin, bisphenol B type epoxy resin, bisphenol BP type epoxy resin, bisphenol C type epoxy resin, bisphenol E type epoxy resin, bisphenol F type epoxy resin, bisphenol G type epoxy resin, bisphenol M type epoxy resin, bisphenol S type epoxy resin, bisphenol P type epoxy resin, bisphenol PH type epoxy resin, bisphenol TMC type epoxy resin, bisphenol Z type epoxy resin, bisphenol type epoxy resin such as hexanediol bisphenol S diglycidyl ether; novolacphenol type epoxy resin; biphenyl type epoxy resin; naphthalene type epoxy resin; dicyclopentadiene type epoxy resin; bixylenol type epoxy resin such as bixylenol diglycidyl ether; hydrogenated bisphenol A Examples include hydrogenated bisphenol-type epoxy resins such as glycidyl ethers and their dibasic acid-modified diglycidyl ether-type epoxy resins; aliphatic epoxy resins; phenylcyclohexyl-type epoxy resins; triazine-type epoxy resins; glycidylamine-type epoxy resins such as triglycidyl p-aminophenol, N-[2-methyl-4-(oxyranylmethoxy)phenyl]-N-(oxyranylmethyl)oxiranmethaneamine, tetraglycidyldiaminodiphenylmethane, and tetraglycidylmetaxylylenediamine; tetrakisphenolethane-type epoxy resins; and the like.

[0016] As the epoxy resin, from the viewpoint of increasing the puncture strength of the cured film and further improving heat resistance, bisphenol-type epoxy resins, novolac phenol-type epoxy resins, naphthalene-type epoxy resins or glycidylamine-type epoxy resins are particularly preferred, and it is more preferable to include at least a bisphenol-type epoxy resin and / or a glycidylamine-type epoxy resin. When the resin composition contains a bisphenol-type epoxy resin and a glycidylamine-type epoxy resin, the content of the glycidylamine-type epoxy resin is preferably 50 parts by mass or more and 500 parts by mass or less, more preferably 100 parts by mass or more and 400 parts by mass or less, and still more preferably 150 parts by mass or more and 300 parts by mass or less, relative to 100 parts by mass of the bisphenol-type epoxy resin. By setting the content within the above range, a cured film having high puncture strength and excellent heat resistance can be formed.

[0017] The content of the epoxy resin in the resin composition is preferably 1% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less, and still more preferably 15% by mass or more and 30% by mass or less, based on 100% by mass of the solid content of the resin composition. When the content is within the above range, a cured film having high puncture strength and excellent heat resistance can be formed.

[0018] The solid content of the resin composition in the present invention refers to the component remaining as a solid content after heating the resin composition at 150°C for 10 minutes. Specifically, it excludes components that evaporate or volatilize upon heating (e.g., solvents, etc.). Note that even if a component is liquid at 25°C, it is included in the solid content if it remains in the resin composition after heating.

[0019] <Alumina Particles> The BET specific surface area S of alumina particles measured by the nitrogen adsorption method is preferably 0.9 m ２ / g or more, more preferably 2.0 m ２ / g or more, still more preferably 4.0 m ２ / g or more, even more preferably 6.0 m ２ / g or more, and preferably 30 m ２ / g or less, more preferably 25 m ２ / g or less, still more preferably 20 m ２ / g or less, even more preferably 15 m２ The amount is less than or equal to / g. Within this range, the dispersibility of alumina particles in the resin composition is good, and the puncture strength of the cured film can be increased. The BET specific surface area of ​​the alumina particles is measured in accordance with JIS-Z8830 (2013).

[0020] The volume-based D50 in the cumulative particle size distribution of alumina particles is preferably 3.0 μm or less, more preferably 2.4 μm or less, even more preferably 2.0 μm or less, even more preferably 1.5 μm or less, particularly preferably 1.0 μm or less, especially preferably 0.5 μm or less, preferably 0.01 μm or more, more preferably 0.1 μm or more, and even more preferably 0.2 μm or more. Within this range, the dispersibility of alumina particles in the resin composition is good, and the puncture strength of the cured film can be increased. Furthermore, by setting the particle size D50 within the above range, the underfill material can be filled into fine gaps of several μm. Since the resin composition of the present invention has good puncture strength after curing, the cured film can maintain the necessary mechanical strength even if it is thin, and the range of applications as an underfill material is broadened. The particle size D50 of alumina particles can be determined, for example, by measuring the particle size distribution of alumina particles using the laser diffraction method with a Microtrac MT3300EXII laser particle size distribution analyzer manufactured by Microtrac Bell Co., Ltd.

[0021] The alpha dose of alumina particles is preferably 0.006 cph / cm². ２ More preferably, 0.005 cph / cm² ２ More preferably, 0.004 cph / cm² ２ More preferably, 0.003 cph / cm² ２ The following applies: The lower limit of the alpha dose of alumina particles is not particularly limited, but for example, 0.0001 cph / cm². ２ The result is 0.0005 cph / cm². ２ Above or above, or 0.0008 cph / cm² ２The above is also acceptable. When the resin composition is used as an underfill for semiconductor devices, a low alpha dose is preferred. Therefore, it is necessary to reduce the content of alpha-emitting radionuclides such as uranium and thorium in the alumina particles. The alpha dose of alumina particles is measured using a measuring device model 1950 (manufactured by Alpha Science Co., Ltd.).

[0022] When measuring the BET specific surface area S, particle size D50, and α-dose of alumina particles in a sheet-like resin composition or cured film, it is preferable to remove the epoxy resin, etc., contained in the sheet-like resin composition or cured film by, for example, dissolving it with an organic solvent or by thermally decomposing the resin by heating it to a temperature of 500°C or higher, thereby separating only the alumina particles, and then measuring using the separated alumina particles. If the resin composition contains two or more types of alumina particles, the BET specific surface area S, particle size D50, and α-dose should be measured while the alumina particles in the resin composition are mixed.

[0023] The alumina particles may be surface-treated with a silane coupling agent. This can improve the dispersibility of the alumina particles in the resin composition. The silane coupling agent may be one or more types.

[0024] Known silane coupling agents can be used. A silane coupling agent may be represented by the following chemical formula (A): X ３－ｎ Me ｎ -Si-Y...(A) (wherein Me is a methyl group, X is a hydrolysis group, Y is a monovalent organic group, and n is 0, 1, or 2)

[0025] In chemical formula (A), X (hydrolysis group) can be, for example, a methoxy group (CH ３ O-), ethoxy group (CH ３ CH ２ O-), propoxy group (CH ３ CH ２ CH ２ O-), isopropoxy group ((CH ３ ) ２ CHO-), chloro group, or 2-methoxyethoxy group (CH ３ OCH２ CH ２ Examples include O-). n is preferably 0 or 1, and more preferably 0.

[0026] In chemical formula (A), Y is a monovalent organic group. Y is preferably a C1-C20 alkyl group which may have vinyl, epoxy, phenyl, styryl, methacrylic, acrylic, amino, ureido, mercapto, isocyanate, etc., at its terminals. Part of the carbon skeleton may be substituted with -O-, -NH-, -S-, -CO-, -COO- as long as they are not adjacent. Among these, unsubstituted C1-C20 alkyl groups having vinyl, phenyl, or epoxy groups are more preferred. Unsubstituted C1-C20 alkyl groups are even more preferred. This improves the dispersibility of alumina particles in the resin composition and improves the puncture strength and heat resistance of the cured film.

[0027] In chemical formula (A), Y is preferably a linear alkyl group having 1 to 20 carbon atoms, more preferably 2 or more carbon atoms, even more preferably 5 or more carbon atoms, and preferably 15 or less carbon atoms. This makes it easier to achieve an effect that suppresses aggregation between alumina particles by allowing the flux to be adsorbed appropriately onto the surface of the alumina particles and by causing steric hindrance by the silane coupling agent.

[0028] Examples of the above-mentioned silane coupling agents include decyltrimethoxysilane, tetramethoxysilane, vinyltrimethoxysilane, 7-octenyltrimethoxysilane, 8-glycidoxyoctyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, hexamethyldisilazane, phenyltrimethoxysilane, glycidoxyoctyltrimethoxysilane, 2-phenylethyltrimethoxysilane, 2,2-diphenylethyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane Tacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2(aminoethyl)3-aminopropylmethyldimethoxysilane, N-2(aminoethyl)3-aminopropyltrimethoxysilane, N-2(aminoethyl)3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, hydrochloride of N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatetopropyltriethoxysilane, hexamethyldisilazane, etc. can be used.

[0029] The mass ratio of the alumina particles (g) to the silane coupling agent (g) is, for example, 1:0.0005 to 1:0.03. When the mass ratio of the alumina particles (g) to the silane coupling agent (g) is within the above range, the dispersibility of the alumina particles in the resin composition is improved, thereby improving the puncture strength and heat resistance of the cured film.

[0030] The alumina particle content in the resin composition is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, based on 100% by mass of the solid content of the resin composition. By keeping it within the above range, puncture strength and heat resistance can be improved, and a cured film with excellent thermal conductivity can be obtained.

[0031] Examples of methods for producing alumina particles include: obtaining aluminum hydroxide from a slurry containing seed crystal alumina and an aluminum alkoxide, and then calcining the aluminum hydroxide to obtain alumina particles (production method 1); obtaining raw material alumina by a known method such as the Bayer process, and then obtaining alumina particles from the raw material alumina by flame melting (production method 2); or calcining transition alumina such as the θ phase or γ phase, or an aluminum compound that generates transition alumina by calcination, in an atmosphere gas containing hydrogen halide gas (production method 3).

[0032] <Method 1 for producing alumina particles> Method 1 includes the steps of: preparing a seed crystal slurry in which seed crystal alumina is dispersed; mixing the seed crystal slurry with aluminum alkoxide to obtain an aluminum hydroxide slurry; and drying and calcining the aluminum hydroxide slurry to obtain alumina particles.

[0033] After dispersing alumina particles, which serve as seed crystals, in water, wet grinding is performed using a ball mill. Subsequently, centrifugation is performed using a centrifuge to remove the precipitate. This yields a seed crystal slurry in which the seed crystals are dispersed. The seed crystals are preferably α-alumina. By using α-alumina seed crystals, the α-conversion of alumina can be promoted at low temperatures during the sintering process described later.

[0034] Next, the seed crystal slurry and aluminum alkoxide are continuously supplied to a stirrer and mixed. By stirring this mixture at high speed using a stirrer, the water in the seed crystal slurry and the aluminum alkoxide undergo a hydrolysis reaction, yielding a slurry (aluminum hydroxide slurry) containing aluminum hydroxide particles, which are the hydrolysis products.

[0035] Furthermore, alumina particles can be obtained by drying the aluminum hydroxide slurry by a known method, for example, at about 100 to 200°C, and then calcining the resulting aluminum hydroxide in a calcination furnace. Calcination is preferably carried out at 800°C to 1000°C. Calcination may also be carried out in the atmosphere or in an inert gas such as nitrogen gas or argon gas.

[0036] <Method for producing alumina particles 2> (Alumina raw material) Alumina raw material is produced by known methods. Examples include the Bayer process, ammonium alum process, ammonium aluminum carbonate hydroxide process (AACH process), solvent extraction method, organoaluminum hydrolysis method (aluminum alkoxide process), CZ method, Bernoulli process, Chiroporous process, Bridgman process, EFG method, and other melt growth methods.

[0037] In the Bayer process, raw alumina can be produced by calcining aluminum hydroxide obtained from bauxite. Furthermore, the ammonium alum method, AACH method, solvent extraction method, and aluminum alkoxide method are preferable because they can produce high-purity raw alumina.

[0038] (Grinding of raw alumina) In order to easily obtain alumina particles of the desired size by the flame melting method, the raw alumina is ground to obtain alumina raw material powder for flame melting. The raw alumina can be ground using known methods such as a vibratory mill, bead mill, ball mill, or jet mill, and may be ground in either a dry or wet state.

[0039] In the above grinding process, a surface protectant may be used. The surface protectant not only protects the surface of the alumina raw material powder after grinding, but may also have the function of inactivating the surface of the alumina raw material powder. Because the surface protectant reduces aggregation of alumina raw material powders due to its surface inactivation function, it is suitable for obtaining alumina particles of a target particle size after flame melting using raw material alumina with a high BET specific surface area that is prone to aggregation. Suitable surface protectants include, for example, monohydric alcohols such as methanol, ethanol, 1-propanol, and 2-propanol; glycols such as ethylene glycol, polyethylene glycol, propylene glycol, and polypropylene glycol; amines such as triethanolamine; and higher fatty acids such as palmitic acid, stearic acid, and oleic acid. One of these surface protectants may be used alone, or two or more may be used in combination. Of these, glycols are preferred, and one or more of ethylene glycol, polyethylene glycol, propylene glycol, and polypropylene glycol are particularly preferred.

[0040] Polyethylene glycol and polypropylene glycol, which are preferably used as surface protective agents, do not have any particular restrictions on their molecular weight, but liquid forms with an average molecular weight of about 200 to 600 are preferred for ease of addition.

[0041] The amount of surface protective agent added is preferably 0.01 parts by mass or more when the raw material alumina is 100 parts by mass, in order to allow the surface protective agent to exert its full effect. However, if the amount of surface protective agent added is too large, the effect of the surface protective agent will saturate, so it is preferable to add 10 parts by mass or less. The amount of surface protective agent added is more preferably 0.05 to 8 parts by mass, and even more preferably 0.1 to 5 parts by mass.

[0042] (Flame Melting) The flame melting method can be applied as a method for producing alumina particles. The flame melting method is a method in which raw material alumina is sprayed into a flame, liquefied, and then cooled and solidified. In the flame melting method, the temperature of the flame melting furnace is preferably 1000°C or higher. In the flame melting method, the raw material supply rate can be adjusted as appropriate, but it is preferably 50 kg / hour or less, and more preferably 10 kg / hour or less, so that the amount of thermal energy applied to the alumina particles can be controlled within a predetermined range.

[0043] The alumina particles after flame melting are collected using a cyclone or bag filter and classified as necessary. After classification, the obtained alumina particles may be immersed in an acidic solution such as hydrochloric acid. Hydrochloric acid is preferred as the type of acidic solution to be used due to the ease of concentration adjustment. The concentration of the acidic solution is preferably 1 M to 12 M, more preferably 1 M to 10 M, and even more preferably 2 M to 5 M. The preferred mass ratio of alumina particles to acidic solution is alumina particles:acidic solution = 1:2 to 1:10. The preferred immersion time is 5 hours or more. The immersion time can be shortened by heating the acidic solution. The temperature of the heated acidic solution is, for example, 50 to 90°C. After immersion in the acidic solution, the alumina particles are washed and dried.

[0044] <Method 3 for producing alumina particles> Method 3 involves using transition alumina such as the θ phase or γ phase, or an aluminum compound that produces transition alumina by calcination, as a raw material, and calcining this raw material in an atmosphere gas containing hydrogen halide gas. Aluminum chloride and aluminum hydroxide can be used as the aluminum compound that produces transition alumina by calcination.

[0045] When controlling the particle size of alumina particles (α-alumina) using the aforementioned raw materials, approximately 0.01 to 10% by mass of seed crystals such as α-alumina powder should be added to the raw materials. By increasing the amount of seed crystals added within this range, the particle size of the resulting alumina particles can be reduced.

[0046] When calcining transition alumina or an aluminum compound that produces transition alumina by calcination in an atmosphere gas containing hydrogen halide gas, the hydrogen halide gas in the atmosphere gas is, for example, 1 volume% or more, preferably 5 volume% or more, and can be increased up to 100 volume%. Other components in the atmosphere gas during calcination include inert gases such as nitrogen and argon, and the concentration of hydrogen halide gas in the atmosphere gas is preferably 10 to 100 volume%. As the hydrogen halide gas, hydrogen chloride gas, hydrogen fluoride gas, hydrogen bromide gas, or hydrogen iodide gas can be used, and among these, hydrogen chloride gas is preferred.

[0047] <Flux> Specifically, flux is a compound that has functions such as removing oxide films from electrode terminals, preventing re-oxidation, or improving wettability when coating with a resin composition. Any compound having the above functions can be used as flux without particular limitations, but the flux is preferably a carboxylic acid.

[0048] The acid equivalent of the flux is preferably 40 g / mol or more, more preferably 50 g / mol or more, even more preferably 55 g / mol or more, even more preferably 60 g / mol or more, preferably 450 g / mol or less, more preferably 300 g / mol or less, even more preferably 200 g / mol or less, even more preferably 140 g / mol or less, particularly preferably 120 g / mol or less, and may also be 100 g / mol or less or 85 g / mol or less. Within the above range, the value Z can be easily adjusted to the desired range, and the oxide film removal function will also be sufficient. The acid equivalent of the flux is defined by the molecular weight of the flux per 1 mol of carboxyl groups in the flux, and specifically, it is obtained by dividing the molecular weight of the flux by the number of carboxyl groups present in one molecule of flux. If the resin composition contains two or more types of flux, the acid equivalent of the flux is obtained by the weighted average of the fluxes contained in the resin composition.

[0049] The molecular weight of the flux is preferably 80 or more, more preferably 100 or more, even more preferably 110 or more, even more preferably 120 or more, and also preferably 900 or less, more preferably 600 or less, even more preferably 400 or less, even more preferably 280 or less, particularly preferably 240 or less, and may also be 200 or less, 170 or less, or 160.0 or less. Within the above range, the alumina particles and the flux can fully exhibit the heat conduction function of the alumina particles and the oxide film removal function of the flux without impairing each other's functions.

[0050] A carboxylic acid is preferred as the flux, and the carboxylic acids include saturated or unsaturated dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, methylsuccinic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, pimelic acid, 2-methylpimelic acid, suberic acid, 2-methylsuberic acid, azelaic acid, 2-methylazelaic acid, sebacic acid, 2-methylsebacic acid, undecanediic acid, dodecanediic acid, fumaric acid, maleic acid, and diglycolic acid; saturated or unsaturated fatty acids such as formic acid, acetic acid, propionic acid, butyric acid, pivalic acid, valeric acid, caproic acid, caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, and crotonic acid; and benzoic acid, toluic acid, salicylic acid, xylic Examples include aromatic monocarboxylic acids such as lylic acid, hemeltic acid, mesitylene acid, cinnamic acid, 3-phenylpropionic acid, and 4-phenylbutyric acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, and 2,6-naphthalenedicarboxylic acid; hydroxy acids such as malic acid, tartaric acid, and lactic acid; keto acids such as 5-ketohexanoic acid and levulinic acid; thio acids such as thiodiglycolic acid; heterocyclic carboxylic acids such as 2-furanic acid; trifunctional or more carboxylic acids such as 1,3,5-pentanetricarboxylic acid, citric acid, propanetricarboxylic acid, trimellitic acid, trimesic acid, prenitic acid, prenitylic acid, 1,2,3-benzenetricarboxylic acid, merophanic acid, pyromellitic acid, and mellitic acid; (meth)acrylic acids such as acrylic acid and methacrylic acid; and abietic acid and ascorbic acid. Among these, saturated or unsaturated dicarboxylic acids are preferred, saturated dicarboxylic acids are more preferred, oxalic acid, malonic acid, succinic acid, methylsuccinic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, 2,2-dimethylglutaric acid, adipic acid, 2-methyladipic acid, pimelic acid, 2-methylpimelic acid, suberic acid, 2-methylsuberic acid, azelaic acid, 2-methylazelaic acid, sebacic acid, 2-methylsebacic acid, undecanediic acid, and dodecanediic acid are even more preferred, and succinic acid, methylsuccinic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, and 2,2-dimethylglutaric acid are even more preferred.

[0051] The flux content in the resin composition is preferably 0.05% to 20% by mass, more preferably 0.1% to 15% by mass, even more preferably 0.5% to 10% by mass, and even more preferably 0.8% to 5% by mass, based on 100% by mass of the solid content of the resin composition. Within this range, the value Z can be easily adjusted to the desired range, and the oxide film removal function of the flux can be fully exhibited.

[0052] The flux content in the resin composition is preferably 0.5 parts by mass to 20 parts by mass, more preferably 1.0 part by mass to 10 parts by mass, and even more preferably 2.0 parts by mass to 5 parts by mass, per 100 parts by mass of alumina particles. Within this range, the value Z can be easily adjusted to the desired range, and the alumina particles and flux can fully exhibit their respective functions without impairing each other's functions, allowing the heat conduction function of the alumina particles and the oxide film removal function of the flux to be fully utilized.

[0053] The resin composition may further contain one or more selected from curing agents, curing accelerators, solvents, and plasticizers.

[0054] <Curing Agent> The resin composition may further contain a curing agent. Known curing agents can be used. From the viewpoint of easily controlling the reactivity with the epoxy resin, phenolic curing agents, amine curing agents, or acid anhydride curing agents are preferred.

[0055] When the resin composition contains a curing agent, the curing agent content is preferably 1% to 10% by mass of the solid content of the resin composition. Within this range, the epoxy resin reacts sufficiently, and a cured film with high puncture strength and excellent heat resistance is obtained.

[0056] <Curing Accelerator> The resin composition may further contain a curing accelerator. The curing accelerator can be one that promotes the reactivity of the epoxy groups (preferably glycidyl groups) of the epoxy resin, preferably a phosphorus-based curing accelerator or an imidazole-based curing accelerator, and more preferably an imidazole-based curing accelerator. These curing accelerators are useful for controlling the reactivity of the epoxy resin.

[0057] Examples of phosphorus-based curing accelerators include triphenylphosphine (TPP). Examples of imidazole-based curing accelerators include 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole, and a commercially available example is "Curezol® 2E4MZ-CN" manufactured by Shikoku Chemicals Holdings Co., Ltd.

[0058] The content of the curing accelerator is preferably 0.01% by mass or more, more preferably 0.10% by mass or more, even more preferably 1.0% by mass or more, preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less, based on 100% by mass of the solid content of the resin composition. Within the above range, the reactivity of the epoxy resin can be easily controlled.

[0059] <Solvent> The resin composition may further contain a solvent. This makes the resin composition more fluid, facilitating the formation of sheet-like resin compositions and cured films. The solvent may, for example, have a molecular weight of 500 or less, a boiling point of 250°C or less, and be liquid between -40°C and 30°C. The boiling point of the solvent is preferably 200°C or less, more preferably 180°C or less, even more preferably 160°C or less, preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher. When the boiling point of the solvent is within the above range, the solvent can be effectively removed during the drying process when forming the resin composition into a sheet, while suppressing the reaction of the epoxy resin.

[0060] Any known solvent can be used, and it is not limited to any solvent that can dissolve epoxy resin. Examples include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, amine-based solvents, amide-based solvents, halogen-based solvents, hydrocarbon-based solvents, and nitrile-based solvents. From the viewpoint of being a good solvent for epoxy resin and having excellent coatability of the resulting resin composition, it is preferable that the resin composition contains one or more solvents selected from the group consisting of ketone-based solvents and ester-based solvents.

[0061] Examples of ketone solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone. Examples of ester solvents include methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, n-propyl acetate, amyl acetate, and sec-butyl acetate. Preferably, the solvent includes one or more selected from the group consisting of methyl ethyl ketone, cyclopentanone, and cyclohexanone.

[0062] The solvent content is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, based on 100% by mass of the resin composition. Within the above range, the coating properties of the resin composition will be good, and the resin composition can be used according to the application.

[0063] <Plasticizer> The resin composition preferably contains a plasticizer. The plasticizer content in the resin composition is preferably 1% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, based on 100% by mass of the solid content of the resin composition. By keeping it within the above range, sufficient conformability can be provided to the sheet-like resin composition and cured film, and it is easy to improve puncture strength and heat resistance. Known plasticizers can be used as the plasticizer, and from the viewpoint of heat resistance, polymer-based plasticizers such as acrylic plasticizers are preferred. Examples of acrylic plasticizers include Clarity LA3320, Clarity LA2330, Clarity LA2250, Clarity LA2270, Clarity LA4285, Clarity LA2140, Clarity LA3710, and Clarity LK9243, all manufactured by Kuraray Co., Ltd.

[0064] <Other Components> The resin composition may, as necessary, contain known additives such as inorganic particles (excluding alumina particles), coupling agents, fillers, pigments, flame retardants, antioxidants, surfactants, compatibilizers, weathering agents, antiblocking agents, antistatic agents, leveling agents, and mold release agents, to the extent that they do not impair the effects of the invention.

[0065] As inorganic particles (excluding alumina particles), ceramic particles consisting of silica, aluminum nitride, boron nitride, silicon nitride, silicon carbide, etc. are preferred. Since ceramics have high thermal conductivity, using ceramic particles can improve the heat dissipation performance of the cured film formed from the resin composition. The resin composition may further contain inorganic particles (excluding alumina particles), but in the present invention, from the viewpoint of thermal conductivity, the higher the content of alumina particles, the more desirable. Of the total 100% by mass of alumina particles and inorganic particles (excluding alumina particles), the content of alumina particles is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, particularly preferably 90% by mass or more, particularly more preferably 95% by mass or more, and most preferably 100% by mass.

[0066] <Method for Manufacturing Resin Composition and Cured Film> The resin composition can be manufactured by a method that includes a step of mixing predetermined components and other components used as needed. The method for manufacturing the resin composition preferably includes a step of mixing alumina particles into an epoxy resin varnish containing epoxy resin and flux. The epoxy resin varnish may optionally contain one or more selected from curing agents, curing accelerators, solvents and plasticizers. The mixing method is not particularly limited, and a mill, mixer, stirring blades, etc., can be used.

[0067] A sheet-like resin composition can be formed into a sheet by applying a resin composition containing a solvent onto a substrate and drying the applied mixture to remove the solvent.

[0068] The method for applying the solvent-containing resin composition is not particularly limited, but coating equipment such as a comma coater, lip coater, roll coater, gravure coater, die coater, or spin coater can be used.

[0069] The substrate is preferably in the form of a film, and a general polymer film can be used. Examples of polymer films include polyethylene film, polyolefin films such as polypropylene film, vinyl films such as polyvinyl chloride film, polyester films such as polyethylene terephthalate film, polycarbonate film, acetylcellulose film, and tetrafluoroethylene film. The thickness of the substrate is not particularly limited, but from the viewpoint of excellent workability and drying properties, 20 to 200 μm is preferred.

[0070] The drying is preferably carried out by heating, for example, with a heating temperature of 50 to 120°C and a heating time of 10 to 60 minutes. Furthermore, the heating is preferably carried out by a combination of multiple steps with different heating temperatures and heating times, and it is more preferable that the heating temperature increases with each step. The process is preferably two steps, with the first step being a heating temperature of 50 to 70°C and a heating time of 7 to 40 minutes, and the second step being a heating temperature of 80 to 120°C and a heating time of 5 to 20 minutes, which is more preferable.

[0071] The resulting sheet-like resin composition is fluid when heated and pressurized. That is, the sheet-like resin composition includes an uncured sheet-like resin composition (also called the "A-stage" sheet-like resin composition). The sheet-like resin composition may also contain a solvent to the extent that it does not impair handling properties.

[0072] The thickness of the sheet-like resin composition is preferably 500 μm or less. Within this range, the heating time required for sufficient curing can be shortened, and a cured film in which alumina particles are uniformly dispersed can be formed. The lower limit of the thickness of the sheet-like resin composition is not particularly limited, but may be, for example, 1 μm or more. The thickness of the sheet-like resin composition can be measured, for example, using a micrometer (Mitutoyo Corporation, PMU150-25MX). If the sheet-like resin composition is on a PET film as a base material, the total thickness of the PET film and the sheet-like resin composition and the thickness of the PET film can be measured separately, and the thickness can be calculated by subtracting the thickness of the PET film from the total thickness. It is preferable to measure the thickness at, for example, three or more locations and obtain the average value.

[0073] The resin composition of the present invention may be used to fill the gaps around solder bumps or in the substrate when mounting semiconductor chips.

[0074] The resin composition is cured by heating, producing a cured film. The curing conditions are not particularly limited, but for example, the heating temperature is 150 to 220°C and the heating time is 30 to 360 minutes.

[0075] In one embodiment, a pressurized heating step may be provided after the drying step, in which heating is performed under pressurized conditions. The pressurized heating step can be carried out using a vacuum press, transfer molding machine, compression molding machine, laminator, etc. The heating temperature is preferably 130°C to 170°C, the pressure is preferably 0.5 MPa to 20 MPa, and the pressurized heating time is preferably 10 seconds to 15 minutes.

[0076] The puncture strength of the cured film, when converted to a thickness of 300 μm, is preferably 1.50 N or more, more preferably 1.75 N or more, and even more preferably 1.90 N or more. Being above the lower limit makes the cured film suitable for high integration and high-density mounting. The upper limit of the puncture strength is not particularly limited, but is preferably 5.00 N or less, more preferably 4.00 N or less, and even more preferably 3.00 N or less. When this puncture strength is expressed as puncture strength per unit thickness, it is preferably 0.0050 N / μm or more, more preferably 0.0058 N / μm or more, even more preferably 0.0063 N / μm or more, and 0.0167 N / μm or less, preferably 0.0133 N / μm or less, and even more preferably 0.0100 N / μm or less. The puncture strength of the cured film can be measured in accordance with JIS-Z1707 under conditions of 23°C and 50% relative humidity using a small benchtop tester EZ-LX (manufactured by Shimadzu Corporation). The cured film is used as a test specimen with a width of 50 mm, a length of 50 mm, and a thickness of 300 μm. A semicircular needle pressure element with a diameter of Φ2.5 mm and a tip shape of 0.5 mm is used as a pressure element, and the test is performed under conditions of a load cell of 50 N and a test speed of 200 mm / min. The displacement at the breaking point is measured, and the maximum load at that time is defined as the puncture strength.

[0077] The glass transition temperature of the cured film is preferably 130°C or higher, more preferably 140°C or higher, and even more preferably 150°C or higher. Being above the lower limit satisfies the heat resistance requirements for the underfill material. The upper limit of the glass transition temperature is not particularly limited, but is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower. The glass transition temperature of the cured film can be measured, for example, by the method described in the examples.

[0078] <Applications> The resin composition of the present invention is preferably used as a resin composition for semiconductor encapsulation in the semiconductor packaging process, and more particularly as an underfill resin composition. For underfill applications, pre-supplied underfill applications are particularly preferred, and more preferably, a sheet-like resin composition for non-conductive film (NCF) or a paste-like resin composition for non-conductive paste (NCP). The resin composition of the present invention has good puncture strength when cured. Therefore, even if the cured film is thin, it can maintain the necessary mechanical strength and can be widely applied as an underfill material to fine gaps.

[0079] The present invention will be described in more detail below with reference to examples. The present invention is not limited by the following examples, and it is certainly possible to implement it with appropriate modifications within the scope that is consistent with the spirit described above, and all such modifications are included within the technical scope of the present invention. In the following, unless otherwise specified, "parts" means "parts by mass" and "%" means "percent mass".

[0080] 1. Evaluation Method and Measurement Method <Measurement of BET Specific Surface Area of ​​Alumina Particles> The BET specific surface area of ​​each alumina particle was measured using a FlowSorb III 2310 (manufactured by Shimadzu Corporation). The nitrogen adsorption BET specific surface area obtained by the nitrogen adsorption single-point method according to the method specified in JIS-Z8830 (2013) was used as the BET specific surface area of ​​each alumina particle. The measurement conditions were as follows: Carrier gas: Nitrogen / helium mixed gas filling Sample amount: 0.1 g Sample pretreatment conditions: Treatment at 200°C for 20 minutes Nitrogen adsorption temperature: Liquid nitrogen temperature (-196°C or below) Nitrogen desorption temperature: Room temperature (approximately 20°C)

[0081] <Measurement of Alumina Particle Size (D50)> The particle size of each alumina particle was measured by laser diffraction using a Microtrac MT3300EXII (manufactured by Microtrac Bell Co., Ltd.) as a laser particle size distribution analyzer. D50 was determined from the measurement results of the particle size distribution. As the sample for measurement, an alumina particle dispersion was used, which was prepared by adding the alumina particles to be measured to a 0.2 mass% sodium hexametaphosphate aqueous solution in an appropriate laser scattering intensity, and then dispersing it with the instrument's built-in ultrasonic device at 40W for 5 minutes. The refractive index of alumina was assumed to be 1.76.

[0082] <Measurement of Alpha Dose of Alumina Particles> The alpha dose of each alumina particle was measured using a measuring device model 1950 (manufactured by Alpha Science Co., Ltd.). The measurement area of ​​the sample was 1000 cm². ２ The measurement time was set to 99 hours, and the counting gas was PR-10 gas (Ar 90%, CH4). ４ Measurement was performed using 10%.

[0083] <Measurement of Cured Film Thickness> The thickness of each cured film was measured using a micrometer (Mitutoyo Corporation, PMU150-25MX). Five arbitrary measurement points were selected, and the average value was taken as the thickness of the cured film (average thickness).

[0084] <Measurement of Puncture Strength> The puncture strength of each cured film was measured in accordance with JIS-Z1707 under conditions of 23°C and 50% relative humidity using a small benchtop testing machine EZ-LX (manufactured by Shimadzu Corporation). Specifically, a test specimen with a width of 50 mm, a length of 50 mm, and a thickness of 300 μm was used, and a semicircular needle pressure element with a diameter of Φ2.5 mm and a tip shape of 0.5 mm was used under conditions of a load cell of 50 N and a test speed of 200 mm / min. The displacement at the breaking point was measured, and the maximum load at that time was defined as the puncture strength.

[0085] <Measurement of Glass Transition Temperature> The glass transition temperature of each cured film was calculated by measuring it under the following conditions. A dynamic viscoelasticity measuring device DVA-220 (manufactured by IT Measurement Control Co., Ltd.) was used to obtain a tanδ curve, which is the ratio of the storage modulus to the loss modulus. The peak of the tanδ curve was defined as the glass transition temperature. The shape of the test specimen and the measurement conditions were as follows: Test specimen: rectangular parallelepiped with a length of 40 mm, a width of 5 mm, and a thickness of 300 μm Experiment mode: single frequency, constant rate heating Experiment method: tensile Sample gripping distance: 15 mm Measurement start temperature: 20°C to 250°C Heating rate: 5°C / min Frequency: 10 Hz Static / dynamic stress ratio: 1.8 The glass transition temperature was evaluated as follows: A if it was 150°C or higher, B if it was 140°C or higher but less than 150°C, and C if it was less than 140°C.

[0086] 2. Synthesis of Alumina Particles (1) Synthesis of Alumina Particle 1 First, a seed crystal (α-alumina) slurry was prepared. Specifically, alumina particles (raw material for seed crystals) were dispersed in water, and then wet-milled in a ball mill to obtain a wet-milled product. Subsequently, the wet-milled product was centrifuged at a rotation speed of 4000 rpm for 30 minutes to remove precipitate and obtain a seed crystal slurry in which seed crystals were dispersed. Next, the seed crystal slurry and aluminum isopropoxide were mixed at high speed and hydrolyzed to obtain an aluminum hydroxide slurry. The obtained aluminum hydroxide slurry was dried at 150°C to obtain aluminum hydroxide particles. Next, the aluminum hydroxide particles were calcined in a gas furnace at 965°C to obtain alumina particles 1. The particle size (D50) of the obtained alumina particles 1 was 0.23 μm, and the BET specific surface area was 9.7 m². ２ / g, alpha dose is 0.005 cph / cm² ２ That was the case.

[0087] (2) Synthesis of Alumina Particles 2 Alumina particles 2 were obtained in the method for producing alumina particles 1 by changing the mixing ratio of the aluminum isopropoxide and seed crystal slurry. The particle size (D50) of the obtained alumina particles 2 was 0.25 μm, and the BET specific surface area was 7.5 m². ２ It was / g.

[0088] (3) Synthesis of Alumina Particles 3 High-purity metallic aluminum obtained by the method described in Japanese Patent Publication No. 2010-106329 was prepared as a raw material. Aluminum hydroxide was obtained from metallic aluminum by the aluminum alkoxide method using the method described in Japanese Patent Publication No. 2018-048060, and then the aluminum hydroxide was calcined to obtain alumina raw material. Next, using a jet mill pulverizer (horizontal jet mill pulverizer PJM-280SP manufactured by Nippon Pneumatic Mfg. Co., Ltd.), the material was processed under the conditions of a raw material alumina supply rate of 30 kg / hour and a gauge pressure at the air supply port during pulverization of 0.5 MPa to obtain alumina raw material particles with an average particle diameter of approximately 2 μm for secondary particles. The obtained alumina raw material particles were put into a flame melting furnace and melted to obtain spherical alumina particles. The atmosphere temperature inside the flame melting furnace was set to 1250°C and the raw material supply rate was set to 5 kg / hour. The obtained alumina particles were collected using a cyclone and subjected to classification by cyclone classification to remove particles larger than 5 μm, thereby obtaining alumina particles 3. The obtained alumina particles 3 had a particle size (D50) of 2.5 μm and a BET specific surface area of ​​1.1 m². ２ / g, alpha dose is 0.001 cph / cm² ２ That was the case.

[0089] (4) Synthesis of alumina particles 4 Alumina particles 4 were obtained by referring to Example 2 of Japanese Patent Publication No. 7-206434. The particle size (D50) of the obtained alumina particles 4 was 0.40 μm and the BET specific surface area was 5.6 m². ２ / g, alpha dose is 0.005 cph / cm² ２ That was the case.

[0090] 3. Preparation of an epoxy resin varnish (resin composition) containing alumina particles. The resin composition was prepared as follows.

[0091] (Comparative Example 1) Epoxy resin 1 and epoxy resin 2 were dissolved in a mixed solvent of methyl ethyl ketone (MEK) and cyclopentanone (CYP) (mass ratio 3:1) in the proportions shown in Table 1 to prepare a 25% by mass mixed solution. Furthermore, flux 1 was dissolved in the mixed solution as a curing accelerator, plasticizer, and flux in the proportions shown in Table 1 to prepare an epoxy resin varnish. Next, alumina particles 1 were added to the obtained epoxy resin varnish in the proportions shown in Table 1, and the mixture was kneaded at 2000 rpm for 60 seconds using a rotation-orbit mixer (manufactured by Thinky Co., Ltd.) to prepare resin composition 1.

[0092] (Examples 1-6) Resin compositions 2-7 were prepared by compounding and kneading in the same manner as in Comparative Example 1, except that epoxy resin, curing accelerator, alumina particles, plasticizer, and flux were used in the components and mixing ratios listed in Table 1.

[0093]

[0094] The components in Table 1 are as follows: (Epoxy resin) Epoxy resin 1: N-[2-methyl-4-(oxyranylmethoxy)phenyl]-N-(oxyranylmethyl)oxiranmethaneamine (SumiEpoxy® ELM-100, manufactured by Sumitomo Chemical Co., Ltd.) Epoxy resin 2: Bisphenol F type epoxy resin (jER YL983U, manufactured by Mitsubishi Chemical Corporation) (Curing accelerator) Curing accelerator: 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole (Curezol® 2E4MZ-CN, manufactured by Shikoku Chemicals Holdings Co., Ltd.) (Plasticizer) Plasticizer: Acrylic block copolymer (Clarity® LA2250, manufactured by Kuraray Co., Ltd.) (Flux) Flux 1: 2-methylglutaric acid (manufactured by Tokyo Chemical Industry Co., Ltd., acid equivalent: 73.07 g / mol, molecular weight: 146.14) Flux 2: Glutaric acid (manufactured by Tokyo Chemical Industry Co., Ltd., acid equivalent: 66.06 g / mol, molecular weight: 132.12) Flux 3: Methylsuccinic acid (manufactured by Tokyo Chemical Industry Co., Ltd., acid equivalent: 66.06 g / mol, molecular weight: 132.12)

[0095] 4. Preparation of Cured Film The obtained resin composition was applied onto a PET film and coated using an applicator to obtain a coating film with a drying thickness of 300 μm. The coating film was heated at 65°C for 30 minutes, then at 100°C for 10 minutes to dry, and the resin composition was formed into a sheet to produce a sheet-like resin composition with a PET film on one side. Next, a PET film was placed on the side of the prepared sheet-like resin composition opposite to the bonded side of the PET film as a release paper, and then vacuum pressed at 140°C for 10 minutes under a pressure of 10 MPa to produce a sheet-like resin composition with PET film on both sides. The PET film was peeled off from both sides of the prepared sheet-like resin composition with PET film on both sides, and a cured film was prepared by heating at 175°C for 2 hours to cure it. Measurements and evaluations were performed on the obtained cured films 1 to 7. The measurement results are shown below.

[0096]

[0097] The cured films obtained in Examples 1 to 6 were all confirmed to have higher puncture strength than the cured film obtained in Comparative Example 1. In addition, the cured films obtained in Examples 1 to 2 and 4 to 6 were all confirmed to have higher glass transition temperatures than the cured film obtained in Example 3.

Claims

1. Containing epoxy resin, alumina particles, and flux, the value Z obtained from formula (1) is 220 (g ０．５ A resin composition having a concentration of less than or equal to × m / mol. Z = S 0.5 ×E …(1) [In formula (1), S is the BET specific surface area (m²) measured by the nitrogen adsorption method of the alumina particles. ２ E represents the amount (g / g) and E represents the acid equivalent (g / mol) of the flux.

2. The resin composition according to claim 1, wherein the volume-based D50 in the cumulative particle size distribution of the alumina particles is 3.0 μm or less.

3. The alpha dose of the alumina particles is 0.006 cph / cm². ２ The resin composition according to claim 1, wherein the following applies:

4. The BET specific surface area S is 0.9 m². ２ The resin composition according to claim 1, wherein the amount is 1 / g or more.

5. The resin composition according to claim 1, wherein the epoxy resin is a polyfunctional epoxy resin.

6. The resin composition according to claim 1, wherein the flux is a carboxylic acid.

7. The resin composition according to claim 1, wherein the flux content is 0.5 to 20 parts by mass per 100 parts by mass of the alumina particles.

8. The resin composition according to claim 1, which may further contain inorganic particles (excluding alumina particles), wherein the content of alumina particles is 50% by mass or more of the total 100% by mass of the alumina particles and the inorganic particles (excluding alumina particles).

9. The resin composition according to claim 1, further comprising a curing accelerator.

10. A resin composition according to any one of claims 1 to 9, for use in semiconductor encapsulation.

11. The resin composition according to claim 10, which is for pre-supplied underfill.

12. A cured film of the resin composition according to any one of claims 1 to 9.

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