Sheet-shaped resin composition

Abstract

Provided is a sheet-shaped resin composition that exhibits excellent sealing properties and is not susceptible to α-ray-induced malfunctions. Specifically provided is a sheet-shaped resin composition that contains alumina particles and an epoxy resin, wherein the alumina particles have a cumulative 50% particle size D50 of 10 µm or smaller from the fine particle side in the volumetric cumulative particle size distribution, the thickness is 0.13-1.00 mm, and the α-ray dose is 0.05 cph / cm2 or less.

Description

Sheet-shaped resin composition

[0001] The present disclosure relates to a sheet-shaped resin composition.

[0002] Since heat generated by passing electricity through electronic components tends to adversely affect the performance of the electronic components, it is desirable to dissipate the heat quickly. Therefore, for example, a sealing member that seals an IC chip incorporated in an electronic component is desirably formed from a material that exhibits high thermal conductivity for heat dissipation. Generally, the sealing member can be formed from a resin composition containing alumina particles and a resin, as described in Patent Documents 1 to 3.

[0003] Furthermore, IC chips made of semiconductor materials are susceptible to the effects of alpha rays, which can cause malfunctions (soft errors).Patent documents 1 to 3 propose using alumina particles with extremely small amounts of uranium and thorium content in order to reduce the amount of alpha rays in the sealing member.

[0004] JP 2017-110146 A International Publication No. 2022 / 102697 JP 2014-5359 A

[0005] In recent years, IC chips have become more susceptible to the effects of α-rays due to the miniaturization and narrowing of wiring pitches of IC chips. Therefore, resin compositions used in semiconductor encapsulation members are required to reduce malfunctions caused by α-rays more than ever before.

[0006] Furthermore, in order to improve the functionality of electronic components, electronic components (panel level packages: PLPs) configured by mounting multiple IC chips on a substrate have been proposed. A typical PLP manufacturing method involves mounting multiple IC chips on a substrate and then encapsulating the multiple IC chips together with a liquid resin composition. In recent years, substrates have become larger in area in order to increase the number of chips that can be mounted. Since it is difficult to encapsulate large-area substrates with a uniform thickness using a liquid resin composition, the use of sheet-shaped resin compositions preformed into a sheet of uniform thickness instead of liquid resin compositions has been considered.

[0007] However, since a sheet-shaped resin composition is used in a solid state, it has poorer fluidity than a liquid resin composition, and therefore the sheet-shaped resin composition may have poorer sealing properties (ability to seal so that the IC chip is not exposed and the surface is flat) than a liquid resin composition.

[0008] In order to meet all of these requirements, a sheet-shaped resin composition that can reduce malfunction due to α rays and has good sealing properties is desired. However, Patent Documents 1 to 3 do not discuss a sheet-shaped resin composition that satisfies all of the requirements. In view of this situation, an object of one embodiment of the present invention is to provide a sheet-shaped resin composition that is less likely to malfunction due to α rays and has good sealing properties.

[0009] Aspect 1 of the present invention is a method for producing a coating composition comprising: alumina particles; and an epoxy resin; wherein the alumina particles have a particle diameter D50 of 10 μm or less at 50% cumulative from the fine particle side of a volume-based cumulative particle size distribution; a thickness of 0.13 mm or more and 1.00 mm or less; and an α dose of 0.05 cph / cm. ２ The following is a sheet-shaped resin composition.

[0010] A second aspect of the present invention is the sheet-shaped resin composition according to the first aspect, wherein the alumina particles have a D50 of less than 6.0 μm.

[0011] A third aspect of the present invention is the sheet-shaped resin composition according to the first or second aspect, wherein the thickness is 0.90 mm or less.

[0012] A fourth aspect of the present invention is the sheet-shaped resin composition according to any one of the first to third aspects, wherein the alumina particles have an average circularity of 0.85 or more.

[0013] A fifth aspect of the present invention is the sheet-shaped resin composition according to any one of the first to fourth aspects, further comprising a solvent.

[0014] A sixth aspect of the present invention is the sheet-shaped resin composition according to the fifth aspect, wherein the ratio of the mass of the alumina particles to the solid content of the sheet-shaped resin composition is 95 mass % or less.

[0015] A seventh aspect of the present invention is the sheet-shaped resin composition according to the fifth or sixth aspect, wherein the ratio of the mass of the alumina particles to the solid content of the sheet-shaped resin composition is 50 mass % or more.

[0016] According to one embodiment of the present invention, it is possible to provide a sheet-shaped resin composition that is less likely to malfunction due to alpha rays and has good sealing properties.

[0017] The present inventors have conducted extensive research with the aim of providing a sheet-shaped resin composition that can suppress malfunctions due to α-rays and achieve good sealing properties. As a result, a sheet-shaped resin composition containing alumina particles having a particle diameter D50 of 10 μm or less and an epoxy resin, having a thickness of 0.13 mm or more and 1.00 mm or less, and an α-ray dose of 0.05 cph / cm ２ It has been found that the above-mentioned object can be achieved if the sheet-shaped resin composition satisfies the following requirements.

[0018] Alumina particles with a low alpha dose and small particle size tend to aggregate and settle in the sheet-shaped composition, which can deteriorate the sealing performance. However, in the embodiment of the present invention, this problem can be solved by controlling the thickness of the sheet-shaped resin composition.

[0019] The sheet-shaped resin composition according to the embodiment will be described below.

[0020] [Sheet-shaped resin composition] The sheet-shaped resin composition according to this embodiment contains alumina particles and an epoxy resin. The alpha dose of the sheet-shaped resin composition is 0.05 cph / cm ２ This limits the alpha dose of the sheet-shaped resin composition to 0.020 cph / cm or less. When the sheet-shaped resin composition is used as a sealing member for an IC chip, malfunction of the IC chip due to alpha rays can be suppressed. The alpha dose of the sheet-shaped resin composition is preferably 0.020 cph / cm or less. ２ Less than or equal to 0.005 cph / cm ２ Below 0.002 cph / cm, particularly preferably ２ The lower limit of the α-ray dose of the sheet-shaped resin composition is not particularly limited, but is, for example, 0.001 cph / cm ２ is.

[0021] The alpha ray source of the sheet-shaped resin composition is mainly the radioactive element contained in the alumina particles. Therefore, in order to suppress the alpha ray dose of the sheet-shaped resin composition, it is effective to reduce the content of the radioactive element contained in the alumina particles. A suitable content range of the radioactive element contained in the alumina particles will be described later. Note that, although it is possible to suppress the alpha ray dose of the sheet-shaped resin composition by reducing the content of the alumina particles (alumina filling rate) contained in the sheet-shaped resin composition, this is not preferable because it may reduce the sealing property of the sheet-shaped resin composition or may reduce the thermal conductivity and therefore the heat dissipation property.

[0022] The "sheet-shaped resin composition" in the present invention refers to a sheet-shaped resin composition containing alumina particles and an epoxy resin, which has fluidity when heated and pressurized. Examples of the sheet-shaped resin composition include uncured sheet-shaped resin compositions (also referred to as A-stage sheet-shaped resin compositions) and sheet-shaped resin compositions obtained by semi-curing uncured sheet-shaped resin compositions (also referred to as B-stage resin compositions). 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 semi-curing the resin by further removing the solvent from the uncured (A-stage) sheet-shaped resin composition.

[0023] 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 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, and nitrile-based solvents. Ketone-based solvents and ester-based solvents are preferred for the resin composition because they are good solvents for the epoxy resin and provide excellent coatability for the resulting resin composition.

[0024] 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, normal propyl acetate, amine acetate, and sec-butyl acetate. The sheet-shaped resin composition preferably contains one or more solvents selected from the group consisting of methyl ethyl ketone, cyclopentanone, and cyclohexanone.

[0025] The amount of solvent in the uncured sheet-shaped resin composition and the semi-cured sheet-shaped resin composition is preferably 0.001 mass % or more and preferably 10 mass % or less, based on the mass of the entire sheet-shaped resin composition. When the amount of solvent is within the above range, the flowability during heating and pressurization is good, aggregation and sedimentation of alumina particles are prevented, and sealing properties are easily improved.

[0026] A semi-cured sheet-shaped resin composition can be produced, for example, by further drying an uncured sheet-shaped resin composition, reducing the amount of solvent by heating and pressurizing, or by reacting an 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 mass of the sheet-shaped resin composition before and after heating, such as drying, and specifically, can be determined by the method described in the examples below.

[0027] The sheet-shaped resin composition according to this embodiment has a thickness of 0.13 mm or more and 1.00 mm or less. A thickness of 0.13 mm or more can prevent the IC chip from being partially exposed or the surface from becoming uneven when the IC chip is encapsulated. 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 0.90 mm or less, more preferably 0.75 mm or less, even more preferably 0.60 mm or less, even more preferably 0.50 mm or less, and particularly preferably 0.40 mm or less, and is preferably 0.15 mm or more, more preferably 0.16 mm or more, even more preferably 0.20 mm or more, particularly preferably more than 0.20 mm, and particularly preferably 0.25 mm or more. When the thickness of the sheet-shaped resin composition is within the above range, the alumina particles (especially particles with a small particle size) and the epoxy resin flow uniformly when heated and pressurized, and voids are less likely to occur after encapsulation and curing. Furthermore, when the sheet-shaped resin composition is stored in the atmosphere, aggregation and sedimentation of alumina particles (especially particles with a small particle size) caused by evaporation of the solvent from the surface, etc., are unlikely to occur, and sealing properties are likely to be maintained for a long period of time.

[0028] The mass ratio of alumina particles to the solid content of the sheet-shaped resin composition (also referred to as "alumina filling rate") is preferably 95 mass% or less. This makes it possible to obtain a sheet-shaped resin composition with good sealing properties. From the viewpoint of further improving the sealing properties of the sheet-shaped resin composition, the alumina filling rate is more preferably 92 mass% or less, even more preferably 90 mass% or less, even more preferably 88 mass% or less, and preferably 50 mass% or more, more preferably 60 mass% or more, even more preferably 70 mass% or more, and even more preferably 80 mass% or more. Furthermore, when the alumina filling rate is equal to or greater than the above lower limit, the thermal conductivity of the cured product of the sheet-shaped resin composition can be improved.

[0029] The solid content of the sheet-shaped resin composition in the present invention refers to what remains as a solid content when the sheet-shaped resin composition is heated, excluding components that evaporate or volatilize upon heating, such as the above-mentioned solvents, etc. Even if a component is liquid at 25°C, if it is incorporated into the solid content of the sheet-shaped resin composition when heated, it is included in the solid content.

[0030] 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 by calculation from the amount of the sheet-shaped resin composition charged.

[0031] Next, the alumina particles and epoxy resin constituting the sheet-shaped resin composition will be described in detail.

[0032] [Alumina Particles] The alumina particles according to this embodiment have the following characteristics.

[0033] (Particle diameter of alumina particles) The alumina particles have a particle diameter D50 of 10 μm or less, which is the cumulative 50% from the fine particle side of the volume-based cumulative particle size distribution. Normally, alumina particles with a small particle diameter tend to aggregate and settle in the sheet-shaped resin composition, resulting in poor sealing performance. However, according to the present invention, good sealing performance can be achieved even when the particle diameter D50 of the alumina particles is 10 μm or less. The D50 of the alumina particles in the present invention is preferably less than 6.0 μm, more preferably 5.5 μm or less, even more preferably 5.0 μm or less, even more preferably 4.0 μm or less, and particularly preferably 3.0 μm or less, and is preferably 1.0 μm or more, more preferably 1.5 μm or more, even more preferably 1.8 μm or more, and particularly preferably 2.0 μm or more. When the D50 of the alumina particles in the present invention is within the above range, good dispersibility in epoxy resins can be achieved, resulting in improved sealing performance.

[0034] The particle diameter 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 diameter of the alumina particles in the sheet-shaped resin composition can be measured by removing the epoxy resin or the like contained in the sheet-shaped resin composition, for example, by dissolving it in an organic solvent or by heating it to a temperature of 500°C or higher to cause thermal decomposition, and isolating only the alumina particles.

[0035] (Average Circularity of Alumina Particles) The average circularity of the alumina particles is preferably 0.85 or more, more preferably 0.88 or more, even more preferably 0.90 or more, particularly preferably 0.93 or more, and is usually 1.00 or less, preferably 0.99 or less, more preferably 0.98 or less. When the average circularity of the alumina particles is within the above range, the filling rate of the alumina particles in the epoxy resin is easily increased, sedimentation in the resin composition is less likely to occur, and dispersibility is improved, thereby achieving good sealing properties. In particular, when the thickness of the sheet-shaped resin sealing material is within the above range, the alumina particles (especially particles with a small particle size) and the epoxy resin are more likely to flow uniformly upon heating and pressurization, and voids are less likely to occur after curing. In addition, when the average circularity of the alumina particles is high, the kneadability with the epoxy resin is also improved, thereby improving the fluidity of the liquid resin composition after kneading and facilitating its formation into a sheet.

[0036] Circularity (SPHT) can be analyzed in accordance with ISO 9276-6. SPHT = 4πA / P ２where A is the measured value of the area of ​​a projected particle image, and P is the measured value of the perimeter of a projected particle image. The average circularity of alumina particles is measured using a measuring device based on the principle of dynamic image analysis in accordance with ISO 13322-2 (for example, a CAMSIZER X2 (manufactured by VERDER Scientific)). The average circularity of alumina particles in a sheet-shaped resin composition can be measured by removing the epoxy resin and the like contained in the sheet-shaped resin composition, for example, by dissolving it in an organic solvent or by heating it to a temperature of 500°C or higher to cause thermal decomposition, and isolating only the alumina particles, and using the alumina particles.

[0037] Another method for determining the average circularity of alumina particles is to use image analysis, which may involve observing a cross section of a sheet-shaped resin composition using an SEM, analyzing the image of all alumina particles contained in a predetermined observation area (e.g., 200 μm × 200 μm), and calculating the average circularity based on the measurement results of the circularity of the alumina particles.

[0038] (Uranium Content and Thorium Content of Alumina Particles) As described above, by reducing the radioactive elements contained in the alumina particles, the alpha dose of the sheet-shaped resin composition can be set within a predetermined range. In the case of a sheet-shaped resin composition having an alumina filling rate in a general range (for example, 20% by mass to 99% by mass), the alpha dose of the sheet-shaped resin composition can be set to 0.050 cph / cm. ２ In order to achieve the above levels, it is preferable that the uranium content be, for example, 550 ppb or less and the thorium content be, for example, 10 ppb or less. By suppressing the uranium content and thorium content of the alumina particles to extremely small amounts as described above, the amount of α-rays emitted from the alumina particles can be reduced, and as a result, the amount of α-rays emitted from the sheet-shaped resin composition can be suppressed.

[0039] The uranium content is preferably 300 ppb or less, more preferably 100 ppb or less, even more preferably 50 ppb or less, and particularly preferably 30 ppb or less, for example 10 ppb or less, or 5 ppb or less. The lower limit of the uranium content is not particularly limited, but may be 0.1 ppb or more. The thorium content is preferably 8 ppb or less, more preferably 5 ppb or less, and particularly preferably 2 ppb or less. The lower limit of the thorium content is not particularly limited, but may be 0.1 ppb or more. The uranium content and thorium content of the alumina particles can be measured by inductively coupled plasma mass spectrometry (ICP-MS).

[0040] [Epoxy Resin] In the present embodiment, the sheet-shaped resin composition contains an epoxy resin. Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol AP type epoxy resins, bisphenol AF type epoxy resins, bisphenol B type epoxy resins, bisphenol BP type epoxy resins, bisphenol C type epoxy resins, bisphenol E type epoxy resins, bisphenol F type epoxy resins, bisphenol G type epoxy resins, bisphenol M type epoxy resins, bisphenol S type epoxy resins, bisphenol P type epoxy resins, bisphenol PH type epoxy resins, bisphenol TMC type epoxy resins, bisphenol Z type epoxy resins, bisphenol S type epoxy resins such as hexanediol bisphenol S diglycidyl ether, novolac phenol type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, bixylenol type epoxy resins such as bixylenol diglycidyl ether, hydrogenated bisphenol A type epoxy resins such as hydrogenated bisphenol A glycidyl ether, and dibasic acid-modified diglycidyl ether type epoxy resins thereof, aliphatic epoxy resins, and phenylcyclohexyl type epoxy resins. Preferred epoxy resins include aromatic epoxy resins, such as 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.These resins are expected to have the effect of shielding alpha rays emitted from alumina particles. Furthermore, aromatic epoxy resins have high dimensional stability against external energy such as heat, making it easy to obtain a sheet-shaped resin composition that can form a cured product with minimal surface unevenness.

[0041] The sheet-shaped resin composition may contain, as needed, known additives, such as plasticizers, curing agents, curing accelerators, coupling agents, 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. In one preferred embodiment of the present invention, the sheet-shaped resin composition contains alumina particles, an epoxy resin, a solvent, and a curing agent. Examples of the curing agent include amine-based curing agents such as 4,4-diaminodiphenylmethane.

[0042] [Method for producing sheet-shaped resin composition] A method for producing a sheet-shaped resin composition will be described. The alumina particles according to this embodiment and an epoxy resin are mixed using a commonly used known method, and the mixture is formed into a sheet to obtain a sheet-shaped resin composition. The mixing method is not particularly limited, and a mill, a mixer, a stirring blade, or the like can be used. In addition to the alumina particles and the epoxy resin, known additives such as plasticizers, curing accelerators, coupling agents, 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 of two or more, as needed, within a range that does not impair the effects of the invention.

[0043] In one example of a method for producing a sheet-shaped resin composition, an epoxy resin, alumina particles, a solvent, and a curing agent are mixed, and then the resulting mixture is applied to a substrate. A portion of the solvent is then removed by drying or the like to obtain a sheet-shaped resin composition (uncured). For example, a semi-cured sheet-shaped resin composition can be obtained by further reducing the amount of solvent by heating and pressurizing. 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.

[0044] [Method for Producing Alumina Particles] The alumina particles used in this embodiment can be produced, for example, by the method described below.

[0045] (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.

[0046] In the case of 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 for the production of high-purity raw alumina with low uranium and thorium contents. Raw alumina produced by these methods, with a uranium content of, for example, 550 ppb or less and a thorium content of, for example, 150 ppb or less, can be used to produce alumina particles, thereby resulting in alumina particles with reduced uranium and thorium contents. Furthermore, from the perspective of further reducing the uranium and thorium contents, it is more preferred to refine metallic aluminum to a purity of 99.999% by mass or more, produce aluminum hydroxide from the metallic aluminum, and then form alumina. The uranium content is preferably 500 ppb or less, more preferably 200 ppb or less, and even more preferably 10 ppb or less. The thorium content is preferably 100 ppb or less, more preferably 50 ppb or less, even more preferably 20 ppb or less, and particularly preferably 10 ppb or less.

[0047] (Pulverization of Raw Alumina) In order to easily obtain alumina particles of a desired size by the flame fusion method, the raw alumina is pulverized to obtain an alumina raw powder to be subjected to flame fusion. The raw alumina can be pulverized by a known method such as a vibration mill, a bead mill, a ball mill, or a jet mill, and may be pulverized in either a dry or wet state.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] (Flame fusion) A flame fusion method is a suitable method for producing alumina particles having a desired particle size and roundness. 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 allows alumina particles to be obtained 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 the flame fusion method, the raw material supply rate can be adjusted as appropriate, but by setting it to preferably 50 kg / h or less, and more 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.

[0052] After the flame fusion, the alumina particles are collected using a cyclone or a bag filter and classified to obtain alumina particles having the desired properties.

[0053] 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.

[0054] [Preparation of Alumina Particles] The alumina particles used in the Examples and Comparative Examples were prepared as follows: Various physical properties (D50, average circularity, uranium content, and thorium content) of the alumina particles were measured by the methods described above and are summarized in Table 1.

[0055] (1) Alumina Particles A0 As a raw material, high-purity metallic aluminum obtained by the method described in JP 2010-106329 A was prepared. Aluminum hydroxide was obtained from metallic aluminum by an aluminum alkoxide method according to the method described in JP 2018-048060 A, and then the aluminum hydroxide was calcined to obtain an alumina raw material.

[0056] Using a jet mill pulverizer (horizontal jet mill pulverizer PJM-280SP manufactured by Nippon Pneumatic Mfg. Co., Ltd.), processing was performed under conditions of a raw material alumina feed rate of 30 kg / h and a gauge pressure at the air supply port during pulverization of 0.5 MPa, to obtain an alumina raw material powder having an average secondary particle size of approximately 2 μm. The obtained alumina raw material powder was 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 feed 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, to obtain alumina particles A0 (D50 = 2.3 μm).

[0057] (2) Alumina Particles B0 Alumina particles before classification were prepared in the same manner as for alumina particles A0, and then classification was performed by cyclone classification to remove particles of 10 μm or more, thereby obtaining alumina particles B0 (D50=5.1 μm).

[0058] (3) DAW05 Alumina particles (D50=6 μm) manufactured by Denka Co., Ltd., DAW05, were used.

[0059] (4) AA-1.5 Alumina particles (D50=1.5 μm) manufactured by Sumitomo Chemical Co., Ltd., AA-1.5, were used.

[0060] [Preparation of Sheet-Shaped Resin Composition] Using the alumina particles, epoxy resin, and additives shown in Table 1, sheet-shaped resin compositions having the solid content shown in Table 2 were prepared according to the following procedure.

[0061] (1) Preparation of Varnish Mesogenic epoxy resin (phenylcyclohexyl type epoxy resin) (ME) or NC-7000 (naphthol-cresol novolac type epoxy resin, manufactured by Nippon Kayaku Co., Ltd.) 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 (DDM) (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.

[0062] Mesogenic epoxy resin (ME) 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.

[0063]

[0064] (2) Preparation of Alumina / Varnish Mixture Alumina particles were added to the obtained varnish in the compounding ratio shown in Table 2, and the mixture was kneaded at 2000 rpm for 60 seconds using a planetary centrifugal mixer (manufactured by Thinky Corporation) to prepare an alumina / varnish mixture.

[0065] (3) Film formation and drying The resulting alumina / varnish mixture was applied to a PET substrate using an applicator to form a film so that the film thickness after thermal curing would be 100 to 2000 μm, and then heated at 65°C for 5 minutes and then 100°C for 15 minutes to evaporate the solvent, yielding a sheet-shaped resin composition (uncured). The thickness of the sheet-shaped resin composition (uncured) was as shown in Table 3. The solvent amount in each of the resulting sheet-shaped resin compositions was 0.1 to 3 mass%.

[0066] 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 (1): Solvent amount (mass %) = {(W1 - W3) - (W2 - W3)} / (W2 - W3) × 100 (1)

[0067] (4) The thermosetting sheet-shaped resin composition (uncured) was laid on a 12-inch silicon wafer and subjected to vacuum press molding using a press molding machine at a pressure of 5 MPa at 140°C for 15 minutes, followed by heating at normal pressure at 175°C for 120 minutes to thermally cure. This gave a cured sheet-shaped resin composition.

[0068] The cured products of the sheet-shaped resin compositions obtained were evaluated as follows. (1) Evaluation of Surface Condition and Sealing Ability The color of the cured products of the sheet-shaped resin compositions on the silicon wafer was visually observed at an illuminance of 1000 lx. The observation results were evaluated based on the following evaluation criteria and are summarized in Table 3. The unevenness of evaluations A to C was evaluated as the area ratio of white regions (where the alumina particles have low dispersibility and voids between the particles and the resin or particle aggregation are observed) to the total area of ​​the sheet-shaped resin composition. Note that if there is color unevenness but there is no problem with sealing ability, the effect of the embodiment of the present invention (good sealing ability) is satisfied and the product is judged as "pass." [Evaluation criteria] A: Good sealing property, and the area ratio of the area with white unevenness is less than 10% B: Good sealing property, and the area ratio of the area with white unevenness is 10% or more but less than 20% C: Good sealing property, and the area ratio of the area with white unevenness is 50% or more D: There are parts on the silicon wafer that are not covered with the resin composition, and unevenness occurs on the surface of the resin composition E: The resin composition is insufficiently cured, and the area ratio of the area with white unevenness is 50% or more

[0069] (2) Evaluation of α-ray Dose The α-ray dose of the sheet-shaped resin composition was measured using a measuring device Model 1950 (manufactured by Alpha Sciences). The measurement area of ​​the sample was 1000 cm. ２ The measurement time was 99 hours, and the counting gas was PR-10 gas (Ar 90%, CH4 10%). The measurement results were evaluated based on the following evaluation criteria and are summarized in Table 3. [Evaluation criteria] A: 0.002 cph / cm ２ Below B: 0.002cph / cm ２ Super 0.010cph / cm ２ Below C: 0.010cph / cm ２ Super 0.050cph / cm ２ below

[0070] (3) Evaluation of Thermal Conductivity The thermal conductivity of the cured sheet-shaped resin composition was measured. For the thermal conductivity measurement, a 10 mm square piece of the cured sheet-shaped resin composition was cut out. The thermal conductivity of this test piece in the thickness direction was measured by temperature wave thermal analysis using an ai-Phase Mobile (manufactured by ai-Phase Co., Ltd., ai-Phase Mobile M3 type 1). The measurement was carried out under atmospheric conditions at 25°C. The measurement results were evaluated based on the following evaluation criteria and are summarized in Table 3. [Evaluation Criteria] A: 2.0 W / (m·K) or more B: 0.27 W / (m·K) or more but less than 2.0 W / (m·K) C: Less than 0.27 W / (m·K)

[0071]

[0072]

[0073]

[0074] Examples 1 to 11, which satisfied the conditions of the embodiment of the present invention, were evaluated as A to C in terms of surface condition and sealing property, confirming that they present no problems as sheet-shaped resin compositions for forming sealing members. On the other hand, Comparative Example 1, in which the sheet-shaped resin composition was thin, exhibited poor sealing property. Comparative Example 2, in which the sheet-shaped resin composition was thick, did not sufficiently cure under the above-mentioned curing conditions (curing temperature and curing time) due to the thick sheet film thickness.

[0075] Comparing Example 2 and Example 9, the alumina particles used in Example 9 had a smaller D50 than the alumina particles used in Example 2, but the average circularity of the alumina particles used in Example 9 was lower than that of the alumina particles used in Example 2. In these examples, the average circularity of the alumina particles had a more significant effect on sealing performance than the D50 of the alumina particles, which is probably why the sheet-shaped resin composition of Example 2 had better sealing performance than the sheet-shaped resin composition of Example 9.

Claims

1. A sheet-shaped resin composition comprising alumina particles and an epoxy resin, wherein the alumina particles have a particle diameter D50 of 10 μm or less at the cumulative 50% from the fine particle side of a volume-based cumulative particle size distribution, a thickness of 0.13 mm or more and 1.00 mm or less, and an alpha dose of 0.05 cph / cm2 or less.

2. The sheet-shaped resin composition according to claim 1, wherein the alumina particles have a D50 of less than 6.0 μm.

3. The sheet-shaped resin composition according to claim 1, wherein the thickness is 0.90 mm or less.

4. The sheet-shaped resin composition according to claim 1, wherein the alumina particles have an average circularity of 0.85 or more.

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

6. A sheet-shaped resin composition according to claim 5, wherein the mass ratio of the alumina particles to the solid content of the sheet-shaped resin composition is 95 mass % or less.

7. The sheet-shaped resin composition according to claim 5, wherein the mass ratio of the alumina particles to the solid content of the sheet-shaped resin composition is 50 mass % or more.

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