Sheet-like resin composition

Abstract

To provide a sheet-like resin composition having a good appearance. [Solution] A sheet-like resin composition comprising alumina particles, an aromatic epoxy resin, and a silane coupling agent, wherein the ratio of alumina particles to the solid content of the sheet-like resin composition is 50% by mass or more and 99% by mass or less, and the alumina particles are found to contain 90 ppm to 500 ppm of H2O when heated from 200°C to 900°C over 50 minutes in a Karl Fischer measurement, and have a thickness of 0.10 mm or more and 1.00 mm or less.

Description

Technical Field

[0001] The present invention relates to a sheet-shaped resin composition, and particularly to a sheet-shaped resin composition for a sealing material.

Background Art

[0002] Since heat generated by energizing an electronic component tends to adversely affect the performance of the electronic component, it is desirable to dissipate the heat promptly. Therefore, for example, a member constituting a semiconductor sealing member surrounding an IC chip is desirably highly thermally conductive for heat dissipation. Generally, as described in Patent Documents 1 to 3, the sealing member may contain alumina particles and a resin.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, as a sealing member, a sheet-shaped resin composition containing alumina particles has been studied. As a result of the study by the present inventors, it has been found that in these sheet-shaped resin compositions, surface unevenness due to aggregation of particles or the like occurs in a cured product obtained by curing the sheet-shaped resin composition. Patent Documents 1 to 3 do not disclose at all about surface unevenness of a cured product and its improvement study when curing a sheet-shaped resin composition containing alumina particles at a high filling rate. Therefore, an embodiment of the present invention aims to provide a sheet-shaped resin composition capable of forming a cured product with less surface unevenness.

Means for Solving the Problems

[0005] Aspect 1 of the present invention is comprising alumina particles, an aromatic epoxy resin, and a silane coupling agent, where the proportion of the alumina particles with respect to the solid content of the sheet-shaped resin composition is 50% by mass or more and 99% by mass or less, when the alumina particles are heated from 200°C to 900°C over 50 minutes in the Karl Fischer measurement, 90 ppm or more and 500 ppm or less of H2O is detected, and is a sheet-shaped resin composition having a thickness of 0.10 mm or more and 1.00 mm or less.

[0006] Aspect 2 of the present invention is the sheet-shaped resin composition according to Aspect 1, wherein in the Karl Fischer measurement, the H2O detected at a temperature of 550°C to 900°C for the alumina particles is 5 ppm or more and 100 ppm or less.

[0007] Aspect 3 of the present invention is the sheet-shaped resin composition according to Aspect 1 or Aspect 2, wherein in the Karl Fischer measurement, the H2O detected at a temperature of 200°C to 550°C for the alumina particles is 80 ppm or more and 300 ppm or less.

[0008] Aspect 4 of the present invention is the sheet-shaped resin composition according to any one of Aspects 1 to 3, further comprising a solvent.

[0009] Aspect 5 of the present invention is the sheet-shaped resin composition according to any one of Aspects 1 to 4, 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.

Advantages of the Invention

[0010] According to an embodiment of the present invention, it is possible to provide a sheet-shaped resin composition capable of forming a cured product with less surface unevenness. [Modes for carrying out the invention]

[0011] The inventors diligently conducted research to provide a sheet-like resin composition capable of forming cured products with minimal surface unevenness. First, the inventors conceived of using a predetermined ratio of alumina particles and a specific resin (aromatic epoxy resin), in addition to including a silane coupling agent. Furthermore, the inventors controlled the amount of H2O corresponding to the number of OH groups on the surface of the alumina particles (i.e., the amount of H2O detected in Karl Fischer measurement when the temperature is raised from 200°C to 900°C over 50 minutes) to a predetermined range. As a result, particle aggregation is suppressed, and the compatibility (mixability) of the particles and aromatic epoxy resin is improved via the silane coupling agent, enabling the realization of a sheet-like resin composition capable of forming cured products with minimal surface unevenness. The requirements of this embodiment will be described in detail below.

[0012] [Sheet-like resin composition] The sheet-like resin composition according to this embodiment is It contains alumina particles, aromatic epoxy resin, and silane coupling agent. The proportion of alumina particles relative to the solid content of the sheet-like resin composition is 50% by mass or more and 99% by mass or less. In Karl Fischer measurements, when the alumina particles were heated from 200°C to 900°C over 50 minutes, H2O was detected in concentrations of 90 ppm to 500 ppm. The thickness is between 0.10 mm and 1.00 mm. The above-mentioned sheet-like resin composition can form a cured product with minimal surface irregularities. Because the cured product has minimal surface irregularities, variations in properties such as thermal conductivity and mechanical strength are reduced.

[0013] The "sheet-like resin composition" in the present invention is fluid when heated and pressurized. The sheet-like resin composition includes, for example, an uncured sheet-like resin composition (also called a Stage A sheet-like resin composition) and a sheet-like resin composition obtained by partially curing an uncured sheet-like resin composition (also called a Stage B resin composition). If the sheet-like resin composition contains a solvent, for example, an uncured (Stage A) sheet-like resin composition can be obtained by applying a liquid resin composition in a sheet-like manner to a substrate, and then removing part of the solvent by evaporation or the like. Furthermore, as will be described later, a Stage B sheet-like resin composition can be obtained by further partially curing the resin by removing the solvent from the uncured (Stage A) sheet-like resin composition.

[0014] In one embodiment of the present invention, the sheet-like resin composition contains a solvent. When the sheet-like resin composition contains a solvent, it flows easily, can be easily deformed to conform to the fine structure of the IC chip and substrate, and can seal a dense structure without gaps. The solvent can be any known solvent, and is not limited as long as it can dissolve the aromatic epoxy resin, but 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, nitrile-based solvents, etc. From the viewpoint of being a good solvent for aromatic epoxy resins and having excellent coatability of the resulting resin composition, it is preferable that the sheet-like resin composition 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. Examples of ester solvents include methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, n-propyl acetate, amine acetate, and sec-butyl acetate. The sheet-like 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-like resin composition and the semi-cured sheet-like resin composition is preferably 0.001% by mass or more, and preferably 10% by mass or less, relative to the total mass of the sheet-like resin composition. When the amount of solvent is within the above range, the fluidity during heating and pressurization is good, and aggregation and sedimentation of alumina particles are prevented, making it easier to improve sealing performance. A semi-cured sheet-like resin composition can be produced, for example, by further drying an uncured sheet-like resin composition, reducing the amount of solvent by heating and pressurizing, or by reacting it with an aromatic epoxy resin. In the present invention, the amount of solvent in the semi-cured sheet-like resin composition is less than the amount of solvent in the uncured sheet-like resin composition. The amount of solvent in the sheet-like resin composition can be determined, for example, from the weight change of the resin sheet before and after heating, and specifically by the method described in the examples below.

[0017] In the alumina particles according to this embodiment, when the temperature is raised from 200°C to 900°C over 50 minutes using Karl Fischer measurement, H2O is detected in a concentration of 90 ppm to 500 ppm. Here, in Karl Fischer measurements, the amount of H2O detected when the temperature is raised from 200°C to 900°C over 50 minutes (hereinafter referred to as "H2O") 200-900℃ This (also referred to as "...") can correspond to all OH groups on the surface of alumina particles. By appropriately controlling the number of OH groups on the surface of alumina particles, the interactions between alumina particles and silane coupling agents, and / or between alumina particles, can be appropriately controlled, thereby improving the sealing properties of the sheet-like resin composition. H2O 200-900℃ If the concentration exceeds 500 ppm (i.e., if there are many OH groups on the surface of the alumina particles), the interaction between alumina particles becomes stronger, making it difficult to suppress the aggregation of alumina particles. Therefore, H2O 200-900℃ The concentration is 500 ppm or less, preferably 300 ppm or less, more preferably 200 ppm or less, and even more preferably 190 ppm or less. On the other hand, H2O 200-900℃If it is less than 90 ppm (that is, if the OH groups on the surface of the alumina particles are few), the interaction between the alumina particles / silane coupling agent becomes weak, and it becomes difficult to improve the compatibility between the alumina particles and the aromatic epoxy resin via the silane coupling agent. Therefore, H2O 200-900℃ should be 90 ppm or more, preferably 140 ppm or more, and even more preferably 150 ppm or more.

[0018] In the Karl Fischer measurement, the amount of H2O detected when the temperature is raised from 550 °C to 900 °C over 30 minutes (hereinafter also referred to as "H2O 550-900℃ ") can correspond to the number of isolated OH groups on the surface of the alumina particles. By controlling the number of isolated OH groups, it is considered that the interactions between the alumina particles / silane coupling agent and / or between the alumina particles can be more appropriately controlled. Here, an isolated OH group means an OH group that is not hydrogen-bonded to other OH groups. H2O 550-900℃ is preferably 5 ppm or more and 100 ppm or less. By setting H2O 550-900℃ to 100 ppm or less, the aggregation of the alumina particles can be further suppressed, and the sealing property of the sheet-like resin composition can be enhanced. H2O 550-900℃ is more preferably 80 ppm or less, further preferably 60 ppm or less, even more preferably 40 ppm or less, and particularly preferably 30 ppm or less. On the other hand, by setting H2O 550-900℃ to 5 ppm or more, the interaction between the alumina particles / silane coupling agent is strengthened, and it becomes easier to further improve the compatibility between the alumina particles and the aromatic epoxy resin via the silane coupling agent, and the sealing property of the sheet-like resin composition can be enhanced. H2O 550-900℃ is more preferably 13 ppm or more, further preferably 15 ppm or more, and even more preferably 18 ppm or more.

[0019] In the Karl Fischer measurement, the amount of H2O detected when the temperature is raised from 200 °C to 550 °C over 20 minutes (hereinafter also referred to as "H2O 200-550℃This term (also referred to as "...") can correspond to the number of hydrogen-bonded OH groups in alumina particles. By controlling the number of hydrogen-bonded OH groups, it is thought that interactions between alumina particles and silane coupling agents, and / or between alumina particles, can be controlled more appropriately. Here, a hydrogen-bonded OH group refers to an OH group that is hydrogen-bonded to another OH group. H2O 200-550℃ It is preferable that the concentration is between 80 ppm and 300 ppm. H2O 200-550℃ By reducing the concentration to 300 ppm or less, aggregation of alumina particles can be further suppressed, thereby improving the sealing properties of the sheet-like resin composition. H2O 200-550℃ The concentration is more preferably 200 ppm or less, even more preferably 145 ppm or less, and even more preferably 130 ppm or less. On the other hand, H2O 200-550℃ By increasing the concentration to 80 ppm or higher, the interaction between alumina particles and the silane coupling agent is strengthened, making it easier to improve the compatibility between alumina particles and aromatic epoxy resin via the silane coupling agent, and thereby enhancing the sealing properties of the sheet-like resin composition. H2O 200-550℃ The concentration is more preferably 85 ppm or more, even more preferably 100 ppm or more, and even more preferably 120 ppm or more.

[0020] H2O 200-550℃ H2O 550-900℃ Ratio (H2O 550-900℃ / H2O 200-550℃ ) is preferably 0.02 or higher, more preferably 0.05 or higher, even more preferably 0.12 or higher, even more preferably 0.16 or higher, preferably 0.30 or lower, more preferably 0.28 or lower, and even more preferably 0.25 or lower. H2O 550-900℃ / H2O 200-550℃ When the range is within the above range, the dispersibility of alumina particles in the composition is easily improved, and the interaction between alumina particles and the silane coupling agent is strengthened, making it easier to further improve the compatibility between alumina particles and aromatic epoxy resin via the silane coupling agent, thus resulting in a better appearance of the cured sheet-like resin composition.

[0021] In this embodiment, H2O 200-900℃ H2O 550-900℃ and H2O 200-550℃ This can be measured by the Karl Fischer method (water vaporization-titration method) in accordance with JIS K 0068:2001 "Method for Measuring Moisture Content of Chemical Products". If alumina particles are present in the resin composition, the alumina particles should be separated by dissolving the resin with an organic solvent or the like. 200-900℃ H2O 550-900℃ and H2O 200-550℃ This represents the amount of water released from alumina particles per unit mass.

[0022] The specific surface area of ​​alumina particles is measured by the nitrogen adsorption method, with a BET specific surface area of ​​10 m². 2 It is preferable that the amount is less than or equal to / g. This makes it easier to improve the dispersibility of alumina particles in the composition and improves the appearance of the cured sheet-like resin composition. The specific surface area of ​​the alumina particles is more preferably 5 m². 2 / g or less, more preferably 3m 2 / g or less, more preferably 1.8m 2 / g or less, particularly preferably 1.5m 2 It is less than / g. Furthermore, by reducing the specific surface area, the amount of OH groups in the alumina particles that may be present on the surface decreases below a predetermined amount (i.e., H2O 200-900℃ It is possible that the appearance of the sheet-like resin composition may deteriorate (as the H2O content decreases to less than 90 ppm). However, with the manufacturing method of this embodiment, even if the specific surface area is small, H2O 200-900℃ The amount can be controlled to a predetermined level (90 ppm) or higher, and as a result, a sheet-like resin composition that can form a cured product with less surface unevenness can be realized. On the other hand, the BET specific surface area of ​​alumina particles is H2O 200-900℃ From the viewpoint of easily controlling it to a predetermined amount or more, preferably 0.2 m 2 / g or more, more preferably 0.3m 2 / g or more, more preferably 0.5m 2 It is 1 / g or more. In this embodiment, the BET specific surface area is measured in accordance with JIS-Z8830(2013). If alumina particles are included in the resin composition, the resin included in the resin composition can be removed by dissolving it with an organic solvent, heating it to a temperature of 500°C or higher to thermally decompose the resin, and only the alumina particles can be separated. The specific surface area can then be measured using these alumina particles.

[0023] The particle size D50 (hereinafter sometimes simply referred to as "D50") of the cumulative particle size distribution of alumina particles, where the cumulative particle size distribution from the finest particle side reaches 50%, is preferably 20 μm or less, more preferably 10 μm or less, even more preferably less than 6.0 μm, even more preferably 5.0 μm or less, particularly preferably 4.0 μm or less, particularly more preferably 3.0 μm or less, 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 less surface unevenness.

[0024] In this embodiment, the D50 of alumina particles can be determined, for example, by measuring the particle size distribution of alumina particles using the "Microtrac MT3300EXII" manufactured by Microtrac-Bell Co., Ltd. as a laser particle size distribution analyzer, by the laser diffraction method. Furthermore, the particle size measurement of alumina particles in a resin composition can be performed by removing the resin contained in the resin composition, for example by dissolving it with an organic solvent or by thermally decomposing the resin by heating it to a temperature of 500°C or higher, separating only the alumina particles, and then using those alumina particles.

[0025] The sheet-like resin composition according to this embodiment contains an aromatic epoxy resin. Examples of aromatic 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 S type epoxy resin such as hexanediol bisphenol S diglycidyl ether, novolacphenol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, bixylenol type epoxy resin such as bixylenol diglycidyl ether, hydrogenated bisphenol A type epoxy resin such as hydrogenated bisphenol A glycidyl ether, and dibasic acid modified diglycidyl ether type epoxy resins thereof, as well as phenylcyclohexyl type epoxy resin. Preferred aromatic epoxy resins include phenylcyclohexyl epoxy resins, naphthalene epoxy resins, phenolic epoxy resins, biphenyl epoxy resins, and bisphenol A epoxy resins. Furthermore, from the viewpoint of thermal conductivity, epoxy resins having mesogenic groups (sometimes referred to as mesogenic epoxy resins) are more preferred among these, and even more preferred are epoxy resins having mesogenic groups that exhibit a phase transition temperature in the encapsulation temperature range of 100°C to 200°C and exhibit liquid crystalline properties. The sheet-like resin composition may also contain one or more aromatic epoxy resins. In other words, the sheet-like resin composition may contain 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 a shielding effect against alpha rays that may be emitted from alumina particles.Furthermore, because aromatic epoxy resins have high dimensional stability against external energy such as heat, it is easy to obtain sheet-like resin compositions that can form cured products with minimal surface unevenness.

[0026] The ratio of alumina particles to the solid content of the sheet-like 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-like resin composition that can suppress surface unevenness of the cured product. From the viewpoint of improving the sealing properties of the sheet-like 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-like 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 the solid content that remains when the resin composition is heated, excluding components that volatilize upon heating, such as the solvent. Even components that are liquid at 25°C are included in the solid content if they are incorporated into the solid content of the resin composition upon heating.

[0027] The alumina packing ratio can be determined, for example, by the following method: First, the volatile components such as solvents are removed by heating, and then the mass of the sheet-like resin composition (corresponding to the mass of "solids") is measured. Next, epoxy resin and other components contained in the sheet-like resin composition are removed by, for example, dissolving them in an organic solvent or thermal decomposing them by heating to a temperature of 500°C or higher, separating only the alumina particles, and the mass of these alumina particles is measured. The alumina packing ratio can then be calculated using these measurement results. Alternatively, the alumina packing ratio can also be calculated from the amount of sheet-like resin composition used.

[0028] The sheet-like resin composition according to this embodiment contains a silane coupling agent. This improves the compatibility between alumina particles and aromatic epoxy resin. The silane coupling agent may be one or more types.

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

[0030] In formula (1), X (hydrolysis group) can be, for example, a methoxy group (CH3O-), an ethoxy group (CH3CH2O-), a propoxy group (CH3CH2CH2O-), an isopropoxy group ((CH3)2CHO-), a chloro group, or a 2-methoxyethoxy group (CH3OCH2CH2O-). n is preferably 0 or 1, and more preferably 0.

[0031] In formula (1), Y is a monovalent organic group. Y is preferably a C1-C20 alkyl group which may have a vinyl group, epoxy group, phenyl group, styryl group, methacrylic group, acrylic group, amino group, ureido group, mercapto group, isocyanate group, etc. at its terminal end. Part of the carbon skeleton may be substituted with -O-, -NH-, -S-, -CO-, -COO- as long as they are not adjacent, and among these, an unsubstituted C1-C20 alkyl group having a vinyl group, phenyl group, or epoxy group is more preferred. This improves the compatibility between alumina particles and aromatic epoxy resin, and allows for the formation of a cured product with less surface unevenness.

[0032] In formula (1), Y is preferably a linear alkyl group having 1 to 20 carbon atoms, more preferably 2 or more carbon atoms, 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 above silane coupling agents include decyltrimethoxysilane, tetramethoxysilane, vinyltrimethoxysilane, 7-octenyltrimethoxysilane, 8-glycidoxyoctyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, hexamethyldisilazane, phenyltrimethoxysilane, glycidoxyoctyltrimethoxysilane, and 2-phenylethyltrimethoxysilane. Lan, 2,2-diphenylethyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyl Tyldiethoxysilane, 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-dicylidene)propylamine, N -Phenyl-3-aminopropyltrimethoxysilane, hydrochloride of N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatetopropyltriethoxysilane, hexamethyldisilazane, etc. can be used.

[0034] In this embodiment, the sheet-like resin composition preferably has a mass ratio of silane coupling agent content to alumina particle content of 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 makes it easier to further improve the compatibility between alumina particles and aromatic epoxy resin. When the mass ratio of silane coupling agent content to alumina particle content is greater than these preferred lower limits, the surface modification properties of the alumina particles tend to improve, and the compatibility with aromatic epoxy resin tends to improve. When it is less than these preferred upper limits, the self-condensation of hydrolyzable groups remaining without bonding to the surface of the alumina particles is suppressed, thereby suppressing aggregation between alumina particles. This makes it easier to further improve the compatibility between alumina particles and aromatic epoxy resin. Furthermore, it becomes easier to obtain a sheet-like resin composition with a good appearance.

[0035] The sheet-like 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 suppress partial exposure of the IC chip and 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 and allow for a composition in which 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, 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-like resin composition is within the above range, the alumina particles and aromatic epoxy resin flow more uniformly when heated and pressurized, and voids are less likely to occur after sealing and curing. In addition, aggregation and sedimentation of alumina particles caused by evaporation of solvent from the surface when stored in the atmosphere are less likely to occur, and sealing performance is easily maintained over a long period of time.

[0036] The sheet-like resin composition according to this embodiment may optionally contain, in part or in combination of two or more 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 mold release agents, as long as the effects of the invention are not impaired.

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

[0038] [Method for producing sheet-like resin compositions] The sheet-like resin composition according to this embodiment is obtained by mixing alumina particles, aromatic epoxy resin, and silane coupling agent according to this embodiment in predetermined ratios using a commonly used and known method, and then molding them into a sheet. The mixing method is not particularly limited, and mills, mixers, stirring blades, etc., can be used. In addition to 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 mold release agents may be mixed together, either alone or in combination of two or more, as long as they do not impair the effects of the invention.

[0039] As an example of a method for producing a sheet-like resin composition, a known method is used to first mix alumina particles and a silane coupling agent in a predetermined ratio, then mix in 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 other means to obtain a sheet-like resin composition (uncured). For example, by further reducing the amount of solvent by heating and pressurizing, a semi-cured sheet-like resin composition can be obtained. The method of applying the mixture 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. 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 manufactured, for example, by the method shown below.

[0041] (Alumina as raw material) The raw material alumina is produced by known methods. Examples include the Bayer process, ammonium alum process, ammonium aluminum carbonate hydroxide process (AACH process), solvent extraction, organoaluminum hydrolysis (aluminum alkoxide process), CZ process, Bernoulli process, Chiroporus process, Bridgman process, EFG process, and other melt growth methods.

[0042] 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 with low uranium and thorium content, which can adversely affect electronic components.

[0043] (Crushing of raw material alumina) To easily obtain alumina particles of a desired size by flame melting, the raw alumina is pulverized to obtain alumina raw material powder for flame melting. The raw alumina can be pulverized by known methods such as a vibratory mill, bead mill, ball mill, or jet mill, and may be pulverized in either a dry or wet state.

[0044] 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 in particular, one or more of ethylene glycol, polyethylene glycol, propylene glycol, and polypropylene glycol are preferred.

[0045] 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 due to their ease of addition.

[0046] 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.

[0047] (Flame melting) The flame melting method is preferred as a method for producing alumina particles having a desired particle size. The flame melting method involves spraying raw alumina into a flame, causing it to liquefy, and then cooling and solidifying it. The flame melting method allows for the production of alumina particles while maintaining the particle size of the raw alumina. In the flame melting method, the temperature of the flame melting furnace is preferably 1000°C or higher. In particular, in the flame melting 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 melting described above, alumina particles can be collected and classified using a cyclone and / or a bag filter to obtain alumina particles with the 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 allows the number of OH groups to be controlled within a predetermined range, thus enabling H2O 200-900℃ H2O 550-900℃ and / or H2O 200-550℃ This makes it easier to adjust the H2O to the desired value. Hydrochloric acid is preferred as the acidic solution during immersion due to the ease of concentration adjustment. The concentration of the acidic solution is preferably adjusted to 1M to 12M, more preferably to 1M to 10M, and particularly preferably to 2M to 5M. This allows the number of OH groups in the alumina particles to be controlled within a predetermined range, and H2O 200-900℃ H2O 550-900℃ and / or H2O 200-550℃ This can be adjusted to the desired value. The preferred mass ratio during immersion is alumina particles to acidic solution of 1:2 to 1:10. The preferred immersion time is 5 hours or more. During immersion, the solution may be heated as needed to shorten the immersion time; for example, it may be heated to 50 to 90°C. After immersion, it is preferable to wash and dry the material. [Examples]

[0050] The following describes in detail this embodiment with reference to examples implemented to clarify its effects. However, this embodiment is not limited in any way to the following examples.

[0051] [Preparation of alumina particles] As the raw material alumina, γ-alumina obtained by the ammonium alum method (average particle size of primary particles calculated from the BET specific surface area value below was 13 nm) was used. The BET specific surface area of ​​this γ-alumina obtained by nitrogen adsorption method was 120 m². 2 The value was / g. Before grinding, 4% by mass of propylene glycol was added to the raw alumina as a surface protective agent and mixed.

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

[0053] The obtained alumina raw material particles were introduced into a flame melting furnace and melted to obtain spherical alumina particles. The ambient temperature inside the flame melting furnace was set to 1250°C and the raw material supply rate to 5 kg / h. The obtained alumina particles were recovered using a cyclone and subjected to classification by cyclone classification to remove particles larger than 5 μm to obtain alumina particle A (D50 = 2.3 μm). In this example, the D50 of the alumina particles was measured by laser diffraction using a Microtrac MT3300EXII laser particle size distribution analyzer manufactured by Microtrac-Bell Co., Ltd.

[0054] The obtained alumina particles A were immersed in 2M hydrochloric acid. The mass ratio of alumina particles to hydrochloric acid during immersion was 1:5, the immersion temperature was 80°C, and the immersion time was 12 hours. After immersion, the particles were immersed in water multiple times. The water was changed each time, and this process was repeated 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 particle A2 was prepared by changing the concentration of hydrochloric acid immersion from 2M to 10M in the manufacturing method of alumina particle A1 described above. Alumina particle B (D50 = 5.1 μm) was prepared by changing the size of the particles removed during cyclone classification from 5 μm or larger to 10 μm or larger, based on the manufacturing method of alumina particle A described above.

[0056] Alumina particle B1 was prepared using the same method as the method for producing alumina particle A1 described above, except that alumina particle B was used.

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

[0058] [H2O 200-900℃ H2O 550-900℃ and H2O 200-550℃ Measurement) H2O in each alumina particle 200-900℃ H2O 550-900℃ and H2O 200-550℃ The amount was measured using the Karl Fischer method (water vaporization-titration method) in accordance with JIS K 0068:2001 "Method for determining the moisture content of chemical products". H2O 200-900℃ This 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 is H2O. 550-900℃ This 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 is H2O. 200-550℃ This represents 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 each moisture content is given by equation (1) below. H2O 550-900℃ +H2O 200-550℃ =H2O200-900℃··· (1)

[0059] [Specific surface area] The specific surface area of ​​each alumina particle was determined as follows. As the specific surface area measuring device, a "FlowSorb III 2310" manufactured by Shimadzu Corporation was used, and the nitrogen adsorption BET specific surface area, determined by the nitrogen adsorption single-point method according to the method specified in JIS-Z8830 (2013), was used as the specific surface area of ​​each alumina particle. The measurement conditions were as follows. Carrier gas: Nitrogen / helium mixture Packing sample amount: 0.1g 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)

[0060] <Preparation of sheet-like resin compositions> Sheet-like resin compositions of Examples 1-6 and Comparative Examples 1-2 were prepared by mixing (kneading) each alumina particle, silane coupling agent (hereinafter sometimes referred to as "SC agent"), aromatic epoxy resin, and 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 performed to fix the silane coupling agent to the surface of the alumina particles. A slurry was prepared by mixing 50 g of each alumina particle with 20 g of isopropanol. To the prepared slurry, 0.5% by mass of silane coupling agent KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd.) was added relative to the alumina particles, and then 0.02 g of formic acid was added and the mixture was stirred for 30 minutes. After that, 0.2 g of 10% by mass aqueous ammonia was added and the mixture was stirred for 60 minutes. The slurry after stirring was heated at 120°C for 3 hours to remove the solvent, thereby obtaining each alumina particle treated with the silane coupling agent.

[0062] Alumina particles treated with a silane coupling agent were subjected to thermogravimetric analysis using a differential thermogravimetric analyzer (NEXTA STA200, Hitachi High-Tech). The mass reduction ratio 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 aromatic epoxy resins, mesogenic epoxy resin (phenylcyclohexyl type epoxy resin) (A) (used in Examples 1-5 and Comparative Examples 1-2) or NC-7000 (manufactured by Nippon Kayaku Co., Ltd., naphthol-cresol novolac type epoxy resin) (used in Example 6) were 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 at a concentration of 4.14% by mass per 100% by mass of the mixed solution to prepare a varnish. Here, 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. [ka]

[0064] (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 rotation-orbit mixer (manufactured by Sinky Co., Ltd.) to prepare the alumina particle / varnish mixture.

[0065] (4) Film formation and drying The obtained alumina particle / varnish mixture was applied to a PET substrate, and after forming a film using an applicator, the solvent was evaporated by heating at 65°C for 5 minutes and then at 100°C for 15 minutes to obtain a sheet-like resin composition (uncured). The thickness of the sheet-like resin composition (uncured) was 300 μm. The solvent content of the obtained sheet-like resin composition was 0.1 to 3% by mass in all cases.

[0066] The amount of solvent in the sheet-like resin composition was determined by the following measurement. A 4 cm square sample was cut from each example and comparative example sheet-like resin composition, along 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 fully exhausted oven to evaporate all the solvent contained in the sample. After that, it was 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 off the heated sample, and the mass of the PET substrate W3 (g) was measured. The masses of the sample before and after heating were determined by subtracting W3 (g) from W1 (g) and W2 (g), respectively. The value obtained by subtracting the mass of the sample after heating (W2-W3) from the mass of the sample before heating (W1-W3) was taken as the mass of the solvent contained in the sheet-like resin composition. The ratio of the mass of the solvent to the mass of the sample before heating was taken as the solvent content (solvent amount). The formula for calculating the solvent content (solvent amount) is as shown in equation (2) below. Solvent volume (mass%) = {(W1-W3)-(W2-W3)} / (W2-W3) × 100···(2)

[0067] (5) Heat curing A sheet-like resin composition (uncured) was vacuum press molded using a press molding machine at a pressure of 5 MPa and 140°C for 15 minutes, and then heat-cured by heating at atmospheric pressure at 175°C for 120 minutes. This yielded a cured sheet-like resin composition with a thickness of 270 μm.

[0068] [Table 1]

[0069] The surface uniformity of the cured sheet compositions obtained in Examples 1-6 and Comparative Examples 1-2 as described above was evaluated, and the results are summarized in Table 2 below.

[0070] <Evaluation of surface unevenness of cured products made from sheet-like resin compositions> The cured product of the above sheet-like resin composition was visually observed in a 2cm x 2cm area under an illumination of 1000lx, and the number of white spots caused by aggregation of alumina particles, etc., was evaluated as follows, with A to C being considered acceptable (having a good surface condition). A: Fewer than 8 white spots larger than 2mm in diameter B: 8 to 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: More than 30 white spots with a diameter of 2 mm or more.

[0071] [Table 2]

[0072] The results in Table 2 will be discussed below. The cured products obtained from the sheet-like resin compositions of Examples 1 to 6, which satisfied the requirements of this embodiment, had little surface unevenness and a good appearance. On the other hand, the cured products obtained from the sheet-like resin compositions of Comparative Examples 1 to 2, which did not satisfy the requirements of this embodiment, had a lot of surface unevenness and an inferior appearance.

Claims

1. It contains alumina particles, aromatic epoxy resin, and silane coupling agent. The proportion of alumina particles to the solid content of the sheet-like resin composition is 50% by mass or more and 99% by mass or less. In Karl Fischer measurements, the alumina particles were found to have a concentration of 90 ppm to 500 ppm of H when the temperature was raised from 200°C to 900°C over 50 minutes. ２ O was detected, A sheet-like resin composition having a thickness of 0.10 mm or more and 1.00 mm or less.

2. The alumina particles are H, which is detected in the Karl Fischer measurement at temperatures from 550°C to 900°C. ２ The sheet-like resin composition according to claim 1, wherein the oxygen content is 5 ppm or more and 100 ppm or less.

3. The alumina particles are H, which is detected in the Karl Fischer measurement at temperatures from 200°C to 550°C. ２ The sheet-like resin composition according to claim 1 or 2, wherein the oxygen content is 80 ppm or more and 300 ppm or less.

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

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

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