Sheet-shaped resin composition

Abstract

Provided is a sheet-shaped resin composition that has an excellent external appearance. Specifically provided is a sheet-shaped resin composition that contains alumina particles, an aromatic epoxy resin, and a silane coupling agent, wherein the proportion of the alumina particles is 50-99 mass% with respect to the solid content of the sheet-shaped resin composition, H2O is detected at a concentration of 90-500 ppm when the alumina particles are subjected to a Karl-Fischer measurement while increasing the temperature from 200-900°C over 50 minutes, and the thickness of the sheet-shaped resin composition is 0.10-1.00 mm.

Description

Sheet-shaped resin composition

[0001] The present invention relates to a sheet-shaped resin composition, and more particularly to a sheet-shaped resin composition for use as an encapsulating material.

[0002] Heat generated by passing current through electronic components is likely to adversely affect the performance of the electronic components, so it is desirable for the heat to be dissipated quickly. Therefore, for example, it is desirable for the material constituting the semiconductor sealing member surrounding the IC chip to exhibit high thermal conductivity for heat dissipation. Such sealing members can generally contain alumina particles and resin, as described in Patent Documents 1 to 3.

[0003] JP 2005-068258 A JP 2011-98841 A JP 2023-146761 A

[0004] In recent years, sheet-shaped resin compositions containing alumina particles have been studied as sealing materials. As a result of studies by the present inventors, it was found that when these sheet-shaped resin compositions are cured, surface unevenness occurs in the cured product due to particle aggregation, etc. Patent Documents 1 to 3 do not disclose any surface unevenness in the cured product when a sheet-shaped resin composition containing alumina particles at a high filling rate is cured, or any studies on improving the surface unevenness. Therefore, an object of an embodiment of the present invention is to provide a sheet-shaped resin composition that can form a cured product with minimal surface unevenness.

[0005] Aspect 1 of the present invention is a sheet-shaped resin composition comprising alumina particles, an aromatic epoxy resin, and a silane coupling agent, wherein the ratio of the alumina particles to the solid content of the sheet-shaped resin composition is 50 mass % or more and 99 mass % or less, and the alumina particles have a H concentration of 90 ppm or more and 500 ppm or less when heated from 200°C to 900°C over 50 minutes in a Karl Fischer measurement. ２ O is detected, and the sheet-shaped resin composition has a thickness of 0.10 mm or more and 1.00 mm or less.

[0006] In a second aspect of the present invention, the alumina particles have a H content detected at a temperature of 550° C. to 900° C. in the Karl Fischer measurement. ２The sheet-shaped resin composition according to aspect 1, wherein O is 5 ppm or more and 100 ppm or less.

[0007] In a third aspect of the present invention, the alumina particles have a H content detected at a temperature of 200° C. to 550° C. in the Karl Fischer measurement. ２ 3. The sheet-shaped resin composition according to claim 1, wherein O is 80 ppm or more and 300 ppm or less.

[0008] A fourth aspect of the present invention is the sheet-shaped resin composition according to any one of the first to third aspects, further comprising a solvent.

[0009] A fifth aspect of the present invention is the sheet-shaped resin composition according to any one of the first to fourth aspects, wherein a mass ratio of the content of the silane coupling agent to the content of the alumina particles is 1:0.001 to 1:0.05.

[0010] According to an embodiment of the present invention, it is possible to provide a sheet-shaped resin composition that can form a cured product with little surface unevenness.

[0011] The present inventors have conducted extensive research to provide a sheet-shaped resin composition capable of forming a cured product with minimal surface unevenness. The present inventors first came up with the idea of ​​using alumina particles and a specific resin (aromatic epoxy resin) in a predetermined ratio, and also containing a silane coupling agent. Furthermore, the present inventors have come up with the idea of ​​using a specific ratio of alumina particles and a specific resin (aromatic epoxy resin) in a predetermined ratio, and further came ... ２ The amount of O (i.e., the amount of H detected when the temperature is raised from 200°C to 900°C over 50 minutes in Karl Fischer measurement) ２ The amount of silane coupling agent (O) was controlled within a predetermined range. As a result, particle aggregation was suppressed, and the compatibility (mixability) of the particles and the aromatic epoxy resin was improved via the silane coupling agent, resulting in a sheet-shaped resin composition that can form a cured product with little surface unevenness. The requirements of this embodiment are described in detail below.

[0012] [Sheet-shaped resin composition] The sheet-shaped resin composition according to the present embodiment includes alumina particles, an aromatic epoxy resin, and a silane coupling agent, wherein the ratio of the alumina particles to the solid content of the sheet-shaped resin composition is 50 mass % or more and 99 mass % or less, and the alumina particles have a H content of 90 ppm or more and 500 ppm or less when heated from 200°C to 900°C over 50 minutes in a Karl Fischer measurement. ２ The sheet-shaped resin composition can form a cured product with little surface unevenness. Because the cured product has little surface unevenness, variations in thermal conductivity, mechanical strength, etc. are reduced.

[0013] The "sheet-shaped resin composition" of the present invention has fluidity when heated and pressurized. Examples of the sheet-shaped resin composition include an uncured sheet-shaped resin composition (also referred to as an A-stage sheet-shaped resin composition) and a sheet-shaped resin composition obtained by semi-curing an uncured sheet-shaped resin composition (also referred to as a B-stage resin composition). When the sheet-shaped resin composition contains a solvent, for example, an uncured (A-stage) sheet-shaped resin composition can be obtained by applying a liquid resin composition to a substrate or the like in a sheet form and then removing a portion of the solvent by evaporation or the like. Furthermore, as described below, a B-stage sheet-shaped resin composition can be obtained by further semi-curing the resin by further removing the solvent from the uncured (A-stage) sheet-shaped resin composition.

[0014] In one embodiment of the present invention, the sheet-shaped resin composition contains a solvent. When the sheet-shaped resin composition contains a solvent, it flows easily, can be easily deformed to fit the fine structure of the IC chip and the substrate, and can seal the dense structure without gaps. Any known solvent can be used as the solvent as long as it can dissolve the aromatic epoxy resin. Examples of the solvent 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 the aromatic epoxy resin and providing excellent coatability to the resulting resin composition, the sheet-shaped resin composition preferably contains one or more solvents selected from the group consisting of ketone-based solvents and ester-based solvents.

[0015] Examples of ketone solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone, and examples of ester solvents include methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, normal propyl acetate, amine acetate, sec-butyl acetate, etc. The sheet-shaped resin composition preferably contains one or more solvents selected from the group consisting of methyl ethyl ketone, cyclopentanone, and cyclohexanone.

[0016] The amount of solvent in the uncured sheet-shaped resin composition and the semi-cured sheet-shaped resin composition is preferably 0.001% by mass or more and preferably 10% by mass or less, based on the mass of the entire sheet-shaped resin composition. When the amount of solvent is within this range, the fluidity is good when heated and pressurized, and aggregation and sedimentation of alumina particles are prevented, making it easy to improve sealing properties. The semi-cured sheet-shaped resin composition can be produced, for example, by further drying the uncured sheet-shaped resin composition, reducing the amount of solvent by heating and pressurizing, or by reacting an aromatic epoxy resin. In the present invention, the amount of solvent in the semi-cured sheet-shaped resin composition is less than the amount of solvent in the uncured sheet-shaped resin composition. The amount of solvent in the sheet-shaped resin composition can be determined, for example, from the change in weight of the resin sheet before and after heating, specifically by the method described in the Examples below.

[0017] The alumina particles according to this embodiment have a H concentration of 90 ppm or more and 500 ppm or less when heated from 200° C. to 900° C. over 50 minutes in a Karl Fischer measurement. ２ In the Karl Fischer measurement, H detected when the temperature was raised from 200°C to 900°C over 50 minutes ２ The amount of O (hereinafter referred to as "H ２ O ２００－９００℃ ") can correspond to the total number of OH groups on the surface of the alumina particles. By appropriately controlling the number of OH groups on the surface of the alumina particles, it is possible to appropriately control the interaction between the alumina particles and the silane coupling agent and / or between the alumina particles, and to improve the sealing property of the sheet-shaped resin composition. ２ O ２００－９００℃ If the content of OH groups exceeds 500 ppm (i.e., if there are many OH groups on the surface of the alumina particles), the interaction between the alumina particles becomes strong, making it difficult to suppress the aggregation of the alumina particles. ２ O ２００－９００℃ is 500 ppm or less, preferably 300 ppm or less, more preferably 200 ppm or less, and further preferably 190 ppm or less. ２ O ２００－９００℃ If the content of OH groups on the surface of the alumina particles is less than 90 ppm (i.e., if there are few OH groups on the surface of the alumina particles), the interaction between the alumina particles and the silane coupling agent will be weak, making it difficult to improve the compatibility between the alumina particles and the aromatic epoxy resin via the silane coupling agent. ２ O ２００－９００℃ is 90 ppm or more, preferably 140 ppm or more, and even more preferably 150 ppm or more.

[0018] In Karl Fischer measurement, the H detected when the temperature was raised from 550°C to 900°C over 30 minutes ２ The amount of O (hereinafter referred to as "H ２ O ５５０－９００℃") can correspond to the number of isolated OH groups on the surface of the alumina particles. It is believed that by controlling the number of isolated OH groups, it is possible to more appropriately control the interaction between the alumina particles and the silane coupling agent and / or between the alumina particles. Here, an isolated OH group means an OH group that is not hydrogen bonded to other OH groups. H ２ O ５５０－９００℃ is preferably 5 ppm or more and 100 ppm or less. ２ O ５５０－９００℃ By making the content of H 100 ppm or less, it is possible to further suppress the aggregation of the alumina particles, and to improve the sealing property of the sheet-shaped resin composition. ２ O ５５０－９００℃ is more preferably 80 ppm or less, even more preferably 60 ppm or less, even more preferably 40 ppm or less, and particularly preferably 30 ppm or less. ２ O ５５０－９００℃ By making the content of H 5 ppm or more, the interaction between the alumina particles and the silane coupling agent is strengthened, and the compatibility between the alumina particles and the aromatic epoxy resin is more easily improved via the silane coupling agent, thereby improving the sealing property of the sheet-shaped resin composition. ２ O ５５０－９００℃ is more preferably 13 ppm or more, even more preferably 15 ppm or more, and even more preferably 18 ppm or more.

[0019] In Karl Fischer measurement, the H detected when the temperature was raised from 200°C to 550°C over 20 minutes ２ The amount of O (hereinafter referred to as "H ２ O ２００－５５０℃ ") can correspond to the number of hydrogen-bonded OH groups of the alumina particles. It is believed that by controlling the number of hydrogen-bonded OH groups, it is possible to more appropriately control the interaction between the alumina particles and the silane coupling agent and / or between the alumina particles. Here, the hydrogen-bonded OH group means an OH group that is hydrogen-bonded with another OH group. H ２ O ２００－５５０℃ is preferably 80 ppm or more and 300 ppm or less. ２ O ２００－５５０℃By making the content of H 300 ppm or less, it is possible to further suppress the aggregation of alumina particles, and it is possible to improve the sealing property of the sheet-shaped resin composition. ２ O ２００－５５０℃ is more preferably 200 ppm or less, even more preferably 145 ppm or less, and even more preferably 130 ppm or less. ２ O ２００－５５０℃ By making the content of H 80 ppm or more, the interaction between the alumina particles and the silane coupling agent is strengthened, and the compatibility between the alumina particles and the aromatic epoxy resin is more easily improved via the silane coupling agent, thereby improving the sealing property of the sheet-shaped resin composition. ２ O ２００－５５０℃ is more preferably 85 ppm or more, even more preferably 100 ppm or more, and even more preferably 120 ppm or more.

[0020] H ２ O ２００－５５０℃ H against ２ O ５５０－９００℃ The ratio (H ２ O ５５０－９００℃ / H ２ O ２００－５５０℃ ) is preferably 0.02 or more, more preferably 0.05 or more, even more preferably 0.12 or more, still more preferably 0.16 or more, and is preferably 0.30 or less, more preferably 0.28 or less, even more preferably 0.25 or less. ２ O ５５０－９００℃ / H ２ O ２００－５５０℃ When the amount of the silane coupling agent is within the above range, the dispersibility of the alumina particles in the composition is easily increased, and the interaction between the alumina particles and the silane coupling agent is strengthened, which makes it easier to further improve the compatibility of the alumina particles and the aromatic epoxy resin via the silane coupling agent, and therefore the appearance of the cured product of the sheet-shaped resin composition is likely to be good.

[0021] In this embodiment, H ２ O ２００－９００℃ , H ２ O ５５０－９００℃ and H ２ O ２００－５５０℃can be measured by the Karl Fischer method (water vaporization-titration method) in accordance with JIS K 0068:2001 "Method for measuring water content in chemical products." When alumina particles are contained in a resin composition, the alumina particles may be separated by dissolving the resin in an organic solvent or the like. ２ O ２００－９００℃ , H ２ O ５５０－９００℃ and H ２ O ２００－５５０℃ represents the amount of moisture generated from alumina particles per unit mass.

[0022] The specific surface area of ​​the alumina particles is 10 m2, measured by the BET specific surface area method using a nitrogen adsorption method. ２ This makes it easy to improve the dispersibility of the alumina particles in the composition, and the appearance of the cured product of the sheet-shaped resin composition tends to be good. The specific surface area of ​​the alumina particles is more preferably 5 m ２ / g or less, more preferably 3m ２ / g or less, and even more preferably 1.8m ２ / g or less, particularly preferably 1.5m ２ By reducing the specific surface area, the number of OH groups present on the surface of the alumina particles is reduced below a predetermined amount (i.e., H ２ O ２００－９００℃ However, if the production method of this embodiment described later is used, the H ２ O ２００－９００℃ The BET specific surface area of ​​the alumina particles can be controlled to a predetermined amount (90 ppm) or more, and as a result, a sheet-shaped resin composition can be realized that can form a cured product with less surface unevenness. ２ O ２００－９００℃ From the viewpoint of easily controlling the thickness to a predetermined value or more, it is preferably 0.2 m ２ / g or more, more preferably 0.3m ２ / g or more, more preferably 0.5m ２ / g or more. In this embodiment, the BET specific surface area is measured in accordance with JIS-Z8830 (2013). When alumina particles are contained in the resin composition, the resin contained in the resin composition can be removed by, for example, dissolving it in an organic solvent or by heating it to a temperature of 500°C or higher to thermally decompose the resin, and only the alumina particles can be isolated, and the specific surface area can be measured using the alumina particles.

[0023] The particle diameter D50 (hereinafter sometimes simply referred to as "D50") of the alumina particles at 50% cumulative particle size from the fine particle side of the cumulative particle size distribution on a volume basis is preferably 20 μm or less, more preferably 10 μm or less, even more preferably less than 6.0 μm, still more preferably 5.0 μm or less, particularly preferably 4.0 μm or less, especially preferably 3.0 μm or less, and is preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.5 μm or more. Having D50 within the above range makes it easier to obtain a cured product with little surface unevenness.

[0024] In this embodiment, the D50 of the alumina particles can be determined by measuring the particle size distribution of the alumina particles by laser diffraction using, for example, a laser particle size distribution measuring device such as a "Microtrac MT3300EXII" manufactured by Microtrac-Bell Co., Ltd. The particle size of the alumina particles in the resin composition can be measured by removing the resin contained in the resin composition by, for example, dissolving it in an organic solvent or by heating it to a temperature of 500°C or higher to pyrolyze the resin, isolating only the alumina particles, and using the alumina particles.

[0025] The sheet-shaped resin composition according to the present embodiment contains an aromatic epoxy resin, such as bisphenol A epoxy resins, bisphenol AP epoxy resins, bisphenol AF epoxy resins, bisphenol B epoxy resins, bisphenol BP epoxy resins, bisphenol C epoxy resins, bisphenol E epoxy resins, bisphenol F epoxy resins, bisphenol G epoxy resins, bisphenol M epoxy resins, bisphenol S epoxy resins, bisphenol P epoxy resins, bisphenol PH epoxy resins, bisphenol TMC epoxy resins, bisphenol Z epoxy resins, bisphenol S epoxy resins such as hexanediol bisphenol S diglycidyl ether, novolac phenol epoxy resins, biphenyl epoxy resins, naphthalene epoxy resins, bixylenol epoxy resins such as bixylenol diglycidyl ether, hydrogenated bisphenol A epoxy resins such as hydrogenated bisphenol A glycidyl ether, and dibasic acid-modified diglycidyl ether-type epoxy resins thereof, and phenylcyclohexyl epoxy resins. Preferred aromatic epoxy resins include phenylcyclohexyl epoxy resins, naphthalene epoxy resins, phenolic epoxy resins, biphenyl epoxy resins, and bisphenol A epoxy resins. From the viewpoint of thermal conductivity, mesogenic epoxy resins (sometimes referred to as "mesogenic epoxy resins") are more preferred, and mesogenic epoxy resins that exhibit a phase transition temperature in the temperature range of 100°C to 200°C and exhibit liquid crystallinity are even more preferred. The resin contained in the sheet-shaped resin composition may include one or more aromatic epoxy resins. That is, the resin contained in the sheet-shaped resin composition may include one or more aromatic epoxy resins selected from the group consisting of phenylcyclohexyl epoxy resins, naphthalene epoxy resins, phenolic epoxy resins, biphenyl epoxy resins, and bisphenol A epoxy resins. Aromatic epoxy resins are expected to have the effect of shielding alpha rays that may be emitted from alumina particles.Furthermore, aromatic epoxy resins have high dimensional stability against external energy such as heat, and therefore it is easy to obtain a sheet-shaped resin composition that can be used to form a cured product with little surface unevenness.

[0026] The ratio of alumina particles to the solid content of the sheet-shaped resin composition (also referred to as the "alumina filling rate") is preferably 50% by mass or more and 99% by mass or less. This makes it possible to obtain a sheet-shaped resin composition that can suppress surface unevenness of the cured product. From the viewpoint of improving the sealing ability of the sheet-shaped resin composition and suppressing surface unevenness of the cured product, the alumina filling rate is more preferably 92% by mass or less, even more preferably 90% by mass or less, and even more preferably 88% by mass or less. Furthermore, from the viewpoint of improving the thermal conductivity of the cured product of the sheet-shaped resin composition, it is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. In this embodiment, the solid content of the resin composition refers to what remains as solid content when the resin composition is heated, excluding, for example, components that volatilize upon heating, such as the solvent. Even if a component is liquid at 25°C, if it is incorporated into the solid content of the resin composition when heated, it is included in the solid content.

[0027] The alumina filling rate can be determined, for example, by the following method. First, the sheet-shaped resin composition is heated to remove volatile components such as solvents, and then the mass of the sheet-shaped resin composition (corresponding to the mass of the "solid content") is measured. Next, the epoxy resin and other components contained in the sheet-shaped resin composition are removed, for example, by dissolving the composition in an organic solvent or by heating the composition to a temperature of 500°C or higher to cause thermal decomposition, and only the alumina particles are separated, and the mass of the alumina particles is measured. The alumina filling rate can be calculated using these measurement results. Alternatively, the alumina filling rate can be calculated from the amount of the sheet-shaped resin composition charged.

[0028] The sheet-shaped resin composition according to the present embodiment contains a silane coupling agent, which can improve the compatibility between the alumina particles and the aromatic epoxy resin. The silane coupling agent may be one type or two or more types.

[0029] As the silane coupling agent, a known one can be used. In one embodiment of the present invention, the silane coupling agent can be represented by the following formula (1): X ３－ｎ Me ｎ —Si—Y (1) (wherein Me is a methyl group, X is a hydrolyzable group, Y is a monovalent organic group, and n is 0, 1, or 2)

[0030] In formula (1), X (hydrolyzable group) is, 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-), a chloro group, or a 2-methoxyethoxy group (CH ３ OCH ２ CH ２ n is preferably 0 or 1, and more preferably 0.

[0031] In formula (1), Y is a monovalent organic group. Y is preferably an alkyl group having 1 to 20 carbon atoms which may have a terminal vinyl group, epoxy group, phenyl group, styryl group, methacryl group, acrylic group, amino group, ureido group, mercapto group, isocyanate group, or the like, and Y may have a part of its carbon skeleton substituted with -O-, -NH-, -S-, -CO-, or -COO- as long as it is not adjacent. Among these, an unsubstituted alkyl group having 1 to 20 carbon atoms, or an alkyl group having a vinyl group, a phenyl group, or an epoxy group is more preferred. This improves the compatibility between the alumina particles and the aromatic epoxy resin, allowing the formation of a cured product with little surface unevenness.

[0032] In formula (1), Y is preferably a linear alkyl group having 1 to 20 carbon atoms, more preferably 2 or more, and even more preferably 5 or more carbon atoms. This makes it easier to obtain the effect of suppressing aggregation between alumina particles due to steric hindrance of the silane coupling agent.

[0033] Examples of the silane coupling agent include decyltrimethoxysilane, tetramethoxysilane, vinyltrimethoxysilane, 7-octenyltrimethoxysilane, 8-glycidoxyoctyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, hexamethyldisilazane, phenyltrimethoxysilane, glycidoxyoctyltrimethoxysilane, and 2-phenylethyltrimethoxysilane. silane, 2,2-diphenylethyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyl ethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2(aminoethyl)3-aminopropylmethyldimethoxysilane, N-2(aminoethyl)3-aminopropyltrimethoxysilane, N-2(aminoethyl)3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-ditylidene)propylamine, N N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, hexamethyldisilazane, and the like can be used.

[0034] In the sheet-shaped resin composition according to this embodiment, the mass ratio of the silane coupling agent content to the alumina particle content is preferably 1:0.0005 to 1:0.03, more preferably 1:0.001 to 1:0.02, and even more preferably 1:0.0015 to 0.01. This facilitates further improvement of the compatibility between the alumina particles and the aromatic epoxy resin. When the mass ratio of the silane coupling agent content to the alumina particle content is greater than these preferred lower limits, the surface modification of the alumina particles tends to improve, and the compatibility with the aromatic epoxy resin tends to improve. When the mass ratio is less than these preferred upper limits, self-condensation of the hydrolyzable groups remaining without bonding to the alumina particle surface tends to be suppressed, thereby suppressing aggregation of the alumina particles. This facilitates further improvement of the compatibility between the alumina particles and the aromatic epoxy resin. Furthermore, a sheet-shaped resin composition with good appearance is easily obtained.

[0035] The sheet-shaped resin composition according to this embodiment has a thickness of 0.10 mm or more and 1.00 mm or less. A thickness of 0.10 mm or more can prevent partial exposure of the IC chip or the occurrence of surface irregularities when sealing the IC chip. A thickness of 1.00 mm or less can reduce the heating time required for sufficient curing, resulting in a composition in which the alumina particles are uniformly dispersed. The thickness is preferably 0.80 mm or less, more preferably 0.60 mm or less, even more preferably 0.40 mm or less, and preferably 0.13 mm or more, more preferably 0.15 mm or more, and even more preferably 0.20 mm or more. When the thickness of the sheet-shaped resin composition is within the above range, the alumina particles and aromatic epoxy resin flow uniformly when heated and pressurized, and voids are less likely to occur after sealing and curing. Furthermore, aggregation or precipitation of the alumina particles caused by evaporation of the solvent from the surface during storage in the atmosphere is less likely to occur, and sealing properties are more likely to be maintained over a long period of time.

[0036] The sheet-shaped resin composition according to the present embodiment may contain, as needed, any of known additives such as plasticizers, curing agents, curing accelerators, fillers, pigments, flame retardants, antioxidants, surfactants, compatibilizers, weather resistance agents, antiblocking agents, antistatic agents, leveling agents, and release agents, either singly or in combination, within the scope of the invention.

[0037] In a preferred embodiment of the present invention, the sheet-shaped resin composition contains alumina particles, an aromatic epoxy resin, a silane coupling agent, a solvent, and a curing agent, such as an amine-based curing agent such as 4,4-diaminodiphenylmethane.

[0038] [Method for Producing Sheet-Like Resin Composition] The sheet-like resin composition according to the present embodiment can be obtained by mixing the alumina particles according to the present embodiment, the aromatic epoxy resin, and the silane coupling agent in a predetermined ratio using a commonly used known method, followed by forming the mixture into a sheet. The mixing method is not particularly limited, and a mill, mixer, stirring blade, or the like can be used. In addition to the alumina particles, aromatic epoxy resin, and silane coupling agent, known additives such as plasticizers, curing agents, curing accelerators, fillers, pigments, flame retardants, antioxidants, surfactants, compatibilizers, weathering agents, antiblocking agents, antistatic agents, leveling agents, and release agents may be mixed alone or in combination as needed, provided that the effects of the present invention are not impaired.

[0039] One example of a method for producing a sheet-shaped resin composition is to use a commonly used known method. First, alumina particles and a silane coupling agent are mixed in a predetermined ratio, followed by further mixing an aromatic epoxy resin, a solvent, and a curing agent. The resulting mixture is then applied to a substrate, and a portion of the solvent is removed by drying or the like to obtain a sheet-shaped resin composition (uncured). For example, the amount of solvent can be further reduced by heating and pressurizing, and the composition can be semi-cured to obtain a semi-cured sheet-shaped resin composition. The method for applying the mixture is not particularly limited, and coating devices such as a comma coater, lip coater, roll coater, gravure coater, die coater, and spin coater can be used. Known curing agents can be used, and known mixing and curing methods can be employed.

[0040] [Method for Producing Alumina Particles] The alumina particles according to this embodiment can be produced, for example, by the method described below.

[0041] (Raw Alumina) Raw alumina is produced by a known method, such as the Bayer method, the ammonium alum method, the ammonium aluminum carbonate hydroxide method (AACH method), the solvent extraction method, the organoaluminum hydrolysis method (aluminum alkoxide method), or a melt growth method such as the CZ method, the Verneuil method, the chiroporous method, the Bridgman method, or the EFG method.

[0042] In the Bayer process, raw alumina can be produced by calcining aluminum hydroxide obtained from bauxite. The ammonium alum process, the AACH process, the solvent extraction process, and the aluminum alkoxide process are also preferred because they allow the production of high-purity raw alumina with low contents of uranium and thorium, which can have adverse effects on electronic components.

[0043] (Pulverization of Raw Alumina) In order to easily obtain alumina particles of a desired size by flame melting, the raw alumina is pulverized to obtain an alumina raw powder to be subjected to flame melting. Pulverization of the raw alumina can be carried out by a known method such as a vibration mill, a bead mill, a ball mill, or a jet mill, and may be carried out in either a dry or wet state.

[0044] A surface protective agent may be used in the above-described pulverization. The surface protective agent not only protects the surface of the alumina raw material powder after pulverization but may also have the function of inactivating the surface of the alumina raw material powder. The surface inactivation function of the surface protective agent can reduce aggregation of the alumina raw material powder. Therefore, the surface protective agent is suitable for obtaining alumina particles of a desired particle size after flame fusion using raw alumina with a high BET specific surface area, which is prone to aggregation. Suitable surface protective agents 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 protective agents may be used alone, or two or more may be used in combination. Among these, glycols are preferred, and one or more of ethylene glycol, polyethylene glycol, propylene glycol, and polypropylene glycol are particularly preferred.

[0045] The molecular weight of the polyethylene glycol and polypropylene glycol preferably used as the surface protective agent is not particularly limited, but liquids with an average molecular weight of about 200 to 600 are preferred for ease of addition.

[0046] The amount of the surface protective agent added is preferably 0.01 parts by mass or more relative to 100 parts by mass of raw alumina in order to fully exert the effect of the surface protective agent, and is preferably 10 parts by mass or less because the effect of the surface protective agent becomes saturated if the amount of the surface protective agent added is too large. The amount of the 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.

[0047] (Flame fusion) A flame fusion method is suitable as a method for producing alumina particles having a desired particle size. The flame fusion method is a method in which raw alumina is sprayed into a flame, turned into droplets, and then cooled and solidified. The flame fusion method makes it possible to obtain alumina particles while roughly maintaining the particle size of the raw alumina. In the flame fusion method, the temperature of the flame fusion furnace is preferably 1000°C or higher. In particular, in the flame fusion method, by setting the raw material supply rate to 50 kg / h or less, preferably 10 kg / h or less, the amount of thermal energy applied to the alumina particles can be controlled within a predetermined range, making it easier to obtain alumina particles that meet the above-mentioned predetermined requirements.

[0048] After the flame fusion, the alumina particles are collected by a cyclone and / or a bag filter and classified to obtain alumina particles having desired properties.

[0049] After classification, it is preferable to immerse the obtained alumina particles in an acidic solution such as hydrochloric acid. This modifies the surface of the alumina particles and controls the number of OH groups within a predetermined range. ２ O ２００－９００℃ , H ２ O ５５０－９００℃ and / or H ２ O ２００－５５０℃ The type of acid solution used for immersion is preferably hydrochloric acid, as it is easy to adjust the concentration. The concentration of the acid solution is preferably adjusted to 1M to 12M, more preferably 1M to 10M, and particularly preferably 2M to 5M. This allows the number of OH groups on the alumina particles to be controlled within a predetermined range, and the H ２ O ２００－９００℃ , H ２ O ５５０－９００℃ and / or H ２ O ２００－５５０℃ can be adjusted to a desired value. The mass ratio during immersion is preferably 1:2 to 1:10 (alumina particles: acidic solution). The immersion time is preferably 5 hours or more. During immersion, heating may be performed as appropriate to shorten the immersion time, for example, heating to 50 to 90°C. After immersion, washing and drying are preferably performed.

[0050] The present embodiment will be described in detail below with reference to examples carried out to clarify the effects of the present embodiment, but the present embodiment is not limited to the following examples.

[0051] [Preparation of Alumina Particles] As raw alumina, γ-alumina obtained by the ammonium alum method (the average particle size of the primary particles calculated from the value of the BET specific surface area described below was 13 nm) was used. The BET specific surface area of ​​this γ-alumina measured by the nitrogen adsorption method was 120 m ２ Before pulverization, 4 mass % of propylene glycol was added as a surface protective agent to the raw alumina and mixed.

[0052] Next, using a jet mill pulverizer (horizontal jet mill pulverizer PJM-280SP manufactured by Nippon Pneumatic Mfg. Co., Ltd.), the alumina raw material was treated under the conditions of a feed rate of 30 kg / h and a gauge pressure at the air supply port during pulverization of 0.5 MPa, to obtain alumina raw material particles having an average particle size of secondary particles of about 2 μm.

[0053] The obtained alumina raw material particles were charged into a flame fusion furnace and melted to obtain spherical alumina particles. The atmospheric temperature in the flame fusion furnace was set to 1250°C, and the raw material supply rate was set to 5 kg / h. The obtained alumina particles were recovered using a cyclone and subjected to classification by cyclone classification to remove particles of 5 μm or larger, thereby obtaining alumina particles A (D50 = 2.3 μm). In the examples, the D50 of the alumina particles was measured by laser diffraction using a laser particle size distribution analyzer "Microtrac MT3300EXII" manufactured by Microtrac Bell Co., Ltd.

[0054] The obtained alumina particles A were immersed in 2 M hydrochloric acid. The mass ratio of alumina particles to hydrochloric acid during immersion was 1:5, the temperature during immersion was 80°C, and the immersion time was 12 hours. After immersion, the particles were immersed in water multiple times. The immersion in water was repeated, replacing the water each time, until the water after immersion became neutral. After removing the water, the particles were left to stand at 80°C for 6 hours and dried to obtain alumina particles A1.

[0055] Alumina particles A2 were produced by the method for producing alumina particles A1, except that the concentration during immersion in hydrochloric acid was changed from 2 M to 10 M. Alumina particles B (D50 = 5.1 μm) were produced by the method for producing alumina particles A, except that the size of the particles removed during cyclone classification was changed from 5 μm or more to 10 μm or more.

[0056] Alumina particles B1 were prepared in the same manner as the alumina particles A1 except that alumina particles B were used.

[0057] The following measurements were carried out on each alumina particle.

[0058] [H ２ O ２００－９００℃ , H ２ O ５５０－９００℃ and H ２ O ２００－５５０℃ Measurement of H of each alumina particle ２ O ２００－９００℃ , H ２ O ５５０－９００℃ and H ２ O ２００－５５０℃ was measured by the Karl Fischer method (water evaporation-titration method) in accordance with JIS K 0068:2001 "Method for measuring water content in chemical products." ２ O ２００－９００℃ is the amount of water detected when the temperature is raised from 200°C to 900°C at a constant rate over 50 minutes, and H ２ O ５５０－９００℃ is the amount of water detected when the temperature is raised from 550°C to 900°C at a constant rate over 30 minutes, and H ２ O ２００－５５０℃ is the amount of moisture detected when the temperature is raised from 200°C to 550°C at a constant rate over 20 minutes. The relationship between the amounts of moisture is given by the following formula (1): ２ O ５５０－９００℃ +H ２ O ２００－５５０℃ = H ２ O ２００－９００℃・・・ (1)

[0059] [Specific Surface Area] The specific surface area of ​​each alumina particle was determined as follows. A Shimadzu Flowsorb III 2310 specific surface area measuring device was used, and the nitrogen adsorption BET specific surface area determined by the single-point nitrogen adsorption method in accordance with the method specified in JIS-Z8830 (2013) was taken as the 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 lower) Nitrogen desorption temperature: Room temperature (approximately 20°C)

[0060] <Preparation of Sheet-Shaped Resin Compositions> Sheet-shaped resin compositions of Examples 1 to 6 and Comparative Examples 1 and 2 were prepared by mixing (kneading) each of the alumina particles, a silane coupling agent (hereinafter sometimes referred to as "SC agent"), an aromatic epoxy resin, and a curing agent in the predetermined ratios shown in Table 1 below. The detailed preparation methods are shown below.

[0061] (1) Silane Coupling Agent Treatment The following treatment was carried out to fix the silane coupling agent to the alumina particle surface. 50 g of each alumina particle was mixed with 20 g of isopropanol to prepare a slurry. 0.5% by mass of silane coupling agent KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the prepared slurry relative to the alumina particles, and 0.02 g of formic acid was further added, followed by stirring for 30 minutes. 0.2 g of 10% by mass ammonia water was then added, followed by stirring for 60 minutes. The stirred slurry was heated at 120°C for 3 hours, and the solvent was removed to obtain each alumina particle treated with a silane coupling agent.

[0062] The alumina particles treated with the silane coupling agent were subjected to thermogravimetric analysis using a simultaneous differential thermal analyzer (NEXTA STA200, Hitachi High-Tech), and the mass loss rate from the initial mass when the temperature was increased from 60°C to 500°C at a rate of 10°C / min was defined as the mass ratio of the silane coupling agent content to the alumina particles.

[0063] (2) Preparation of Varnish: As an aromatic epoxy resin, a mesogenic epoxy resin (phenylcyclohexyl type epoxy resin) (A) (used in Examples 1 to 5 and Comparative Examples 1 and 2) or NC-7000 (a naphthol-cresol novolac type epoxy resin manufactured by Nippon Kayaku Co., Ltd.) (used in Example 6) was dissolved in a mixed solvent of methyl ethyl ketone and cyclopentanone (mass ratio 3:1) to prepare a 30% by mass mixed solution. Furthermore, 4,4-diaminodiphenylmethane (manufactured by TCI) was added as a curing agent in an amount of 4.14% by mass relative to 100% by mass of the mixed solution to prepare a varnish. Here, the mesogenic epoxy resin (A) is a prepolymer obtained by reacting trans-4-{4-(2,3-epoxypropoxy)phenyl}cyclohexyl 4-(2,3-epoxypropoxy)benzoate (an epoxy resin represented by the structural formula below) with 6-hydroxy-2-naphthoic acid.

[0064]

[0065] (3) Preparation of Alumina Particle / Varnish Mixture Alumina particles treated with a silane coupling agent (or alumina particles not treated with a silane coupling agent) were added to the obtained varnish, and the mixture was kneaded at 2000 rpm for 60 seconds using a planetary centrifugal mixer (manufactured by Thinky Corporation) to prepare an alumina particle / varnish mixture.

[0066] (4) Film Formation and Drying The resulting alumina particle / varnish mixture was applied to a PET substrate and formed into a film using an applicator. The film was then heated at 65°C for 5 minutes and then at 100°C for 15 minutes to remove the solvent, yielding a sheet-shaped resin composition (uncured). The thickness of the sheet-shaped resin composition (uncured) was 300 μm. The solvent content of each of the resulting sheet-shaped resin compositions was 0.1 to 3 mass%.

[0067] The amount of solvent in the sheet-shaped resin composition was determined by the following measurement. A 4 cm square sample was cut from each sheet-shaped resin composition of each Example and Comparative Example, together with the PET substrate, and the mass W1 (g) of the sample (with PET substrate) was measured. Next, the sample was heated at 150°C for 10 minutes using a full exhaust oven to evaporate all of the solvent contained in the sample. The sample was then left at room temperature for 5 minutes to return to room temperature, and the mass W2 (g) of the heated sample (with PET substrate) was measured. The PET substrate was peeled from the heated sample, and the mass W3 (g) of the PET substrate was measured. The masses of the sample before and after heating were determined by subtracting W3 (g) from W1 (g) and W2 (g). The mass of the sample after heating (W2 - W3) was determined by subtracting the mass of the sample before heating (W1 - W3) from the mass of the sample before heating (W1 - W3). The mass of the solvent contained in the sheet-shaped resin composition was determined. The ratio of the mass of the solvent to the mass of the sample before heating was determined as the solvent content (solvent amount). The solvent content (solvent amount) is calculated using the following formula (2): Solvent amount (mass %) = {(W1 - W3) - (W2 - W3)} / (W2 - W3) × 100 (2)

[0068] (5) The uncured thermosetting sheet-shaped resin composition was subjected to vacuum press molding at 140°C for 15 minutes under a pressure of 5 MPa using a press molding machine, and then heated at 175°C for 120 minutes under normal pressure to be thermally cured, thereby obtaining a cured sheet-shaped resin composition having a thickness of 270 μm.

[0069]

[0070] The cured products of the sheet-shaped compositions of Examples 1 to 6 and Comparative Examples 1 and 2 obtained as described above were evaluated for surface unevenness, and the results are summarized in Table 2 below.

[0071] <Evaluation of Surface Unevenness of Cured Product Produced from Sheet-Shaped Resin Composition> The cured product of the sheet-shaped resin composition was visually observed in an area of ​​2 cm x 2 cm under an illuminance of 1000 lx, and the number of white spots due to aggregation of alumina particles, etc. was evaluated as follows, with A to C being considered pass (having a good surface condition): A: Less than 8 white spots with a diameter of 2 mm or more B: 8 to less than 15 white spots with a diameter of 2 mm or more C: 15 to less than 22 white spots with a diameter of 2 mm or more D: 22 to less than 30 white spots with a diameter of 2 mm or more E: 30 or more white spots with a diameter of 2 mm or more

[0072]

[0073] The results in Table 2 are discussed below. The cured products obtained from the sheet-shaped resin compositions of Examples 1 to 6, which satisfied the requirements of this embodiment, had little surface unevenness and good appearance. On the other hand, the cured products obtained from the sheet-shaped resin compositions of Comparative Examples 1 and 2, which did not satisfy the requirements of this embodiment, had much surface unevenness and poor appearance.

Claims

1. A sheet-shaped resin composition comprising alumina particles, an aromatic epoxy resin, and a silane coupling agent, wherein the ratio of the alumina particles to the solid content of the sheet-shaped resin composition is 50% by mass or more and 99% by mass or less, wherein the alumina particles have a detected H2O content of 90 ppm or more and 500 ppm or less when heated from 200°C to 900°C over 50 minutes in Karl Fischer measurement, and wherein the thickness is 0.10 mm or more and 1.00 mm or less.

2. The sheet-shaped resin composition according to claim 1, wherein the alumina particles have an H2O content of 5 ppm or more and 100 ppm or less at temperatures of 550°C to 900°C in the Karl Fischer measurement.

3. The sheet-shaped resin composition according to claim 1 or 2, wherein the alumina particles have an H2O content of 80 ppm or more and 300 ppm or less at temperatures of 200°C to 550°C in the Karl Fischer measurement.

4. The sheet-shaped resin composition according to claim 1 or 2, further comprising a solvent.

5. A sheet-shaped resin composition according to claim 1 or 2, wherein the mass ratio of the content of the silane coupling agent to the content of the alumina particles is 1:0.001 to 1:0.05.

Images