Sheet-like resin composition

Abstract

Provided is a sheet-like resin composition that suppresses deterioration of sealability even when being stored for a long period of time, and that is unlikely to exhibit appearance defects.　This sheet-like resin composition comprises alumina particles, an epoxy resin, a phenol-based curing agent, and a solvent. The proportion of the alumina particles in 100 mass% of the solid content is 40-99 mass%. The contained amount of the solvent is 0.10-5.00 mass%.

Description

Sheet-like resin composition

[0001] This disclosure relates to a sheet-like resin composition.

[0002] The heat generated when an electric current is passed through an electronic component can easily adversely affect its performance, so it is desirable that the heat be dissipated quickly. Therefore, for example, the sealing member that encloses an IC chip incorporated into an electronic component should be made from a material that exhibits high thermal conductivity for heat dissipation. A sheet-like resin composition containing epoxy resin and alumina particles is known as a material that can form a sealing member with excellent thermal conductivity (for example, Patent Document 1).

[0003] Japanese Patent Publication No. 2020-200478

[0004] The sheet-like resin composition is manufactured by applying a liquid resin composition containing epoxy resin, alumina particles, a solvent, and a curing agent to a substrate, and then removing a portion of the solvent. When the obtained sheet-like resin composition is heated and pressurized in contact with an object to be sealed, such as an IC chip, the epoxy resin constituting the sheet-like resin composition softens and covers the IC chip, and then the epoxy resin reacts with the curing agent and hardens, forming a sealing member that seals the IC chip.

[0005] If the period between the manufacture of a sheet-like resin composition and its use (sometimes referred to as the "storage period") is extended, the sheet-like resin composition may become less flexible when heated and pressurized, or the softening time (hereinafter sometimes referred to as the "gelling time") may be shortened. If the sheet-like resin composition does not soften sufficiently or the softening time is short, handling during sealing of IC chips and other components becomes difficult, and the sealing performance deteriorates. Furthermore, it has been found that if a sheet-like resin composition containing a high concentration of alumina particles is stored at room temperature or below for a long period, surface defects, thought to be caused by phase separation, may occur on the surface of the sheet-like resin composition, resulting in an uneven surface. In this specification, the phenomenon of decreased sealing performance and surface defects in a sheet-like resin composition due to extended storage (long-term storage) may be referred to as "deterioration over time."

[0006] Therefore, the objective of one embodiment of the present invention is to provide a sheet-like resin composition that suppresses a decrease in sealing properties even when stored for a long period of time and is less prone to appearance defects.

[0007] One aspect of the present invention is a sheet-like resin composition comprising alumina particles, an epoxy resin, a phenolic curing agent, and a solvent, wherein the proportion of alumina particles in 100% by mass of solid content is 40% by mass or more and 99% by mass or less, and the content of the solvent is 0.10% by mass or more and 5.00% by mass or less.

[0008] Aspect 2 of the present invention is a sheet-like resin composition according to aspect 1, wherein the solvent comprises one or more selected from the group consisting of ketone-based solvents and ester-based solvents.

[0009] Aspect 3 of the present invention is a sheet-like resin composition according to aspect 1 or 2, wherein the alumina particles have a moisture content of 1.0 ppm or more and 100 ppm or less at temperatures from 550°C to 900°C, as measured by Karl Fischer measurement.

[0010] Aspect 4 of the present invention is that the alumina particles have a BET specific surface area of ​​0.2 m² as measured by the nitrogen adsorption method. ２ / g or more 10m ２ The sheet-like resin composition is less than or equal to / g, as described in any one of embodiments 1 to 3.

[0011] Embodiment 5 of the present invention is a sheet-like resin composition according to any one of Embodiments 1 to 4, wherein the average roundness of the alumina particles is 0.80 or more and 0.99 or less.

[0012] Aspect 6 of the present invention is a sheet-like resin composition according to any one of aspects 1 to 5, having a thickness of 0.10 mm or more and 1.00 mm or less.

[0013] According to one embodiment of the present invention, it is possible to provide a sheet-like resin composition that suppresses a decrease in sealing properties and is less prone to appearance defects, even when stored for a long period of time.

[0014] This is an example of a photograph of the surface of a sheet-like resin composition that developed surface defects after long-term storage at low temperatures. This is an example of a photograph of the surface of a sheet-like resin composition that developed surface defects after long-term storage at room temperature.

[0015] The inventors diligently conducted research to provide a sheet-like resin composition that suppresses the deterioration of sealing properties even when stored for a long period of time and is less prone to appearance defects. As a result, they discovered for the first time that these can be achieved with a sheet-like resin composition that uses a phenolic curing agent and limits the solvent content to 0.10% by mass or more and 5.00% by mass or less, thus completing the present invention.

[0016] Our research has revealed that one of the causes of deterioration of sheet-like resin compositions over time, particularly the decrease in sealing properties, is the use of highly reactive curing agents. While storage at low temperatures suppresses the reaction between the curing agent and epoxy resin in the sheet-like resin composition compared to storage at room temperature, these reactions become significant over long storage periods, ultimately leading to deterioration of the sheet-like resin composition over time. Phenolic curing agents are relatively less reactive, further slowing the reaction rate between the curing agent and epoxy resin. As a result, deterioration of the sheet-like resin composition over time can be suppressed, enabling long-term storage of the sheet-like resin composition.

[0017] Furthermore, the inventors have for the first time discovered that when a sheet-like resin composition containing alumina particles is stored for a long period of time at temperatures below room temperature (e.g., below 30°C), the sheet-like resin composition develops appearance defects that appear to be caused by phase separation. Moreover, as will be described later, the inventors have also for the first time discovered that the appearance defects that appear to be caused by phase separation differ depending on the storage temperature during long-term storage and the solvent content contained in the sheet-like resin composition. When these appearance defects occur, problems may arise when printing on the surface of the cured product after sealing with the sheet-like resin composition using a laser. Note that if the sheet-like resin composition is black due to a coloring agent, for example, the phase-separated portion can be observed as a white area.

[0018] When a sheet-like resin composition containing more than 5.00% by mass of solvent is stored at a low temperature (-20°C) for a long period, dendritic patterns (referred to as "dendritic defects") may form within the sheet-like resin composition, as shown in Figure 1. These dendritic defects are thought to be caused by the localized precipitation and / or recrystallization of some of the monomer components and curing agent components of the epoxy resin that were dissolved in the solvent, due to the long-term storage of the sheet-like resin composition at low temperatures. Although the details are unclear, it is thought that the higher the solvent content in the sheet-like resin composition, the greater the amount of epoxy resin monomer components and curing agent components that precipitate / recrystallize due to low-temperature storage, resulting in dendritic defects of a visible size and number.

[0019] On the other hand, when a sheet-like resin composition with a solvent content of less than 0.10% by mass is stored at room temperature (10°C to 30°C) for a long period of time, a mesh-like pattern may form within the sheet-like resin composition, as shown in Figure 2. The mesh-like pattern is thought to be the result of phase separation between the epoxy resin and alumina particles due to the long-term storage of the sheet-like resin composition at room temperature. Although the details are unclear, it is presumed that the lower the solvent content in the sheet-like resin composition, the less easily the epoxy resin, which was excessively dissolved in the solvent, can maintain its dissolved state and readily phase separates from the alumina particles. The lower the solvent content in the sheet-like resin composition, the more sensitive it is to changes in solvent content due to evaporation, etc., which is why a mesh-like pattern was observed when it was stored at room temperature for a long period of time.

[0020] The following describes in detail a sheet-like resin composition according to one embodiment of the present invention.

[0021] [Sheet-like resin composition] The sheet-like resin composition according to one embodiment of the present invention comprises alumina particles, epoxy resin, a phenolic curing agent, and a solvent. The ratio of the mass of alumina particles to the solid content of the sheet-like resin composition (also referred to as the "alumina filling rate") is 40% by mass or more and 99% by mass or less. The solvent content in the sheet-like resin composition is 0.10% by mass or more and 5.00% by mass or less.

[0022] In this disclosure, "sheet-like resin composition" refers to a sheet-like resin composition containing alumina particles, epoxy resin, a phenolic curing agent, and a solvent, which is fluid when heated and pressurized, and includes an uncured sheet-like resin composition (also referred to as a "Stage A" sheet-like resin composition). For example, an uncured (Stage A) sheet-like resin composition can be obtained by applying a liquid resin composition containing a solvent to a substrate in a sheet-like manner, and then removing a portion of the solvent by evaporation or other means.

[0023] The substrate is preferably in the form of a film, and a general polymer film can be used. Examples of polymer films include polyethylene film, polyolefin films such as polypropylene film, vinyl films such as polyvinyl chloride film, polyester films such as polyethylene terephthalate film, polycarbonate film, acetylcellulose film, and tetrafluoroethylene film. The thickness of the substrate is not particularly limited, but from the viewpoint of excellent workability and drying properties, 20 to 200 μm is preferred.

[0024] (Alumina Filling Rate) The proportion of alumina particles in 100% by mass of the solid content of the sheet-like resin composition (alumina filling rate) is 40% by mass or more and 99% by mass or less. By setting the alumina filling rate to 40% by mass or more, the thermal conductivity of the sealing member obtained by curing the sheet-like resin composition can be made sufficiently high. The lower limit of the alumina filling rate is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more. By setting the alumina filling rate to the above lower limit or higher, the thermal conductivity of the sealing member can be further increased.

[0025] By setting the alumina filling rate to 99% by mass or less, a sheet-like resin composition with good sealing properties can be obtained. The upper limit of the alumina filling rate is preferably 95% by mass or less, more preferably 92% by mass or less, even more preferably 90% by mass or less, and even more preferably 88% by mass or less. By setting the alumina filling rate to or below the above upper limit, the sealing properties of the sheet-like resin composition can be further improved.

[0026] The solid content of the sheet-like resin composition in the present disclosure refers to what remains as the solid content after heating the sheet-like resin composition at 150°C for 10 minutes, and for example, components that evaporate and volatilize upon heating, such as solvents, are excluded. Even components that are liquid at 25°C and are contained in the sheet-like resin composition after heating are included in the solid content.

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

[0028] (Content of solvent) The content of the solvent contained in the sheet-like resin composition is 0.10% by mass or more and 5.00% by mass or less. Here, the "content of solvent" is the content of the solvent determined with the mass of the sheet-like resin composition before heating as 100% by mass. By setting the content of the solvent within the above range, it is possible to suppress the occurrence of appearance defects after long-term storage at normal temperature and after long-term storage at low temperature.

[0029] As described above, when the content of the solvent is less than 0.10% by mass, there is a possibility that a net-like pattern may occur when the sheet-like resin composition is stored at normal temperature (10°C to 30°C) for a long time. The net-like pattern is considered to be due to phase separation of the epoxy resin or the like and is likely to occur during storage at normal temperature. On the other hand, when the content of the solvent exceeds 5.00% by mass, there is a possibility that dendritic defects may occur when the sheet-like resin composition is stored at low temperature (-20°C) for a long time. The dendritic defects are considered to be due to recrystallization of the epoxy resin monomer component and the curing agent component in the sheet-like resin composition and are likely to occur during storage at low temperature.

[0030] The content of the solvent is preferably 0.20% by mass or more, more preferably 0.30% by mass or more, still more preferably 0.40% by mass or more, particularly preferably 0.50% by mass or more, and is preferably 4.00% by mass or less, more preferably less than 3.00% by mass, still more preferably 2.00% by mass or less, particularly preferably 1.50% by mass or less. When the content of the solvent is within the above range, the occurrence of appearance defects can be more effectively suppressed.

[0031] Further, when the content of the solvent is within the above range, the deterioration over time of the sheet-like resin composition during the storage period can be suppressed, the fluidity during heating and pressing is good, and the aggregation and sedimentation of alumina particles can be suppressed, so that the sealing property of the sheet-like resin composition can be enhanced.

[0032] The content of the solvent contained in the sheet-like resin composition is determined from the mass change of the sheet-like resin composition before and after heating. Specifically, a sample of the sheet-like resin composition with a predetermined size (for example, 4 cm square) is prepared, and the mass X1 (g) of the sample before heating is measured. Next, using a full evacuation oven, the sample is heated at 150 °C for 10 minutes to evaporate the solvent contained in the sheet-like resin composition. Then, it is left to stand at room temperature for 5 minutes to return to room temperature, and the mass X2 (g) of the sample after heating is measured. The content of the solvent (mass%) is obtained by dividing the mass difference (X1 - X2) obtained by subtracting the mass X2 (g) of the sample after heating from the mass X1 (g) of the sample before heating by the mass X1 (g) of the sample before heating (see the following formula (1)). Content of solvent (mass%) = (X1 - X2) / X1 × 100 (1)

[0033] (Thickness of the sheet-like resin composition) The thickness of the sheet-like resin composition is, for example, 0.10 mm or more and 1.00 mm or less. When the thickness is 0.10 mm or more, when sealing an IC chip, it is possible to suppress the partial exposure of the IC chip or the occurrence of unevenness on the surface. When the thickness is 1.00 mm or less, the heating time required for sufficient curing can be shortened, and a sheet-like resin composition in which alumina particles are uniformly dispersed can be obtained.

[0034] The thickness of the sheet-like resin composition is preferably 0.13 mm or more, more preferably 0.15 mm or more, even more preferably 0.20 mm or more, particularly preferably more than 0.20 mm, preferably 0.90 mm or less, more preferably 0.70 mm or less, even more preferably 0.50 mm or less, even more preferably 0.40 mm or less, and particularly preferably 0.35 mm or less. When the thickness of the sheet-like resin composition is within the above range, deterioration of the sheet-like resin composition over time is easily suppressed. Furthermore, when the sheet-like resin composition is heated and pressurized during sealing, the alumina particles (especially particles with small particle sizes) and epoxy resin flow uniformly, and voids are less likely to occur after sealing and curing. In addition, when the sheet-like resin composition is stored in the atmosphere, aggregation and sedimentation of alumina particles (especially particles with small particle sizes) caused by evaporation of solvent from the surface are less likely to occur, and the sealing performance is easily maintained over a long period of time.

[0035] The thickness of the sheet-like resin composition can be measured, for example, using a micrometer (Mitutoyo Corporation, PMU150-25MX). If the sheet-like resin composition is on a PET substrate, the total thickness of the PET substrate and the sheet-like resin composition, and the thickness of the PET substrate can be measured separately, and the thickness can be calculated by subtracting the thickness of the PET substrate from the total thickness. It is preferable to measure the thickness at three or more locations and obtain the average value. Specifically, it can be determined, for example, by the method described in the examples.

[0036] Next, the alumina particles, epoxy resin, phenolic curing agent, and solvent that constitute the sheet-like resin composition will be described in detail.

[0037] [Alumina Particles] The alumina particles according to this embodiment have the following characteristics.

[0038] (Moisture content of alumina particles) The moisture content of alumina particles was measured by Karl Fischer measurement at temperatures from 550°C to 900°C ("H ２ O ５５０－９００℃ (Also referred to as "), but preferably 1.0 ppm or more and 100 ppm or less. ２ O ５５０－９００℃is considered to correspond to the number of isolated OH groups on the surface of the alumina particles. By controlling the number of isolated OH groups, the interaction between the alumina particles or the like can be more appropriately controlled. Here, the isolated OH group means an OH group that is not hydrogen-bonded to other OH groups. H ２ O ５５０－９００℃ is more preferably 5.0 ppm or more, further preferably 6.0 ppm or more, still more preferably 10.0 ppm or more, particularly preferably 15.0 ppm or more, particularly more preferably 18 ppm or more, particularly even more preferably 20 ppm or more, and more preferably 80 ppm or less, further preferably 60 ppm or less, still more preferably 40 ppm or less, particularly preferably 35 ppm or less. H ２ O ５５０－９００℃ By controlling H ２ O ５５０－９００℃ within the above range, the affinity between the alumina particles and the epoxy resin or curing agent component is likely to be maintained. Therefore, it is easy to prevent the occurrence of appearance defects in the sheet-like resin composition, and further, the aggregation of the alumina particles can be more suppressed, and the sealing property of the sheet-like resin composition can be further enhanced. H ２ O ５５０－９００℃ is the amount of water detected by the Karl Fischer method (water vaporization - titration method) in accordance with the description of JIS K 0068:2001 "Method for Measuring Moisture in Chemical Products" when the temperature is raised from 550 °C to 900 °C at a constant rate over 30 minutes.

[0039] H ２ O ５５０－９００℃ is considered to correspond to the number of isolated OH groups on the surface of the alumina particles. By controlling the number of isolated OH groups, the interaction between the alumina particles or the like can be more appropriately controlled. Here, the isolated OH group means an OH group that is not hydrogen-bonded to other OH groups.

[0040] (BET specific surface area of alumina particles) The BET specific surface area of the alumina particles measured by the nitrogen adsorption method is preferably 0.2 m ２ / g or more and 10 m ２ / g or less, more preferably 0.2 m ２ / g or more and 5.0 m ２ / g or less, further preferably 0.3 m ２ / g or more and 3.0 m ２ / g or less, more preferably 0.35m ２ / g or more 1.0m ２ / g or less, particularly preferably 0.40m ２ / g or more 1.0m ２ It is less than or equal to / g. When the BET specific surface area of ​​the alumina particles is within the above range, it is easier to prevent defects in the appearance of the sheet-like resin composition and to improve its fluidity, resulting in good sealing properties of the resulting sheet-like resin composition.

[0041] The BET specific surface area is measured in accordance with JIS-Z8830 (2013). If alumina particles are present in a sheet-like resin composition, the epoxy resin and other components in the composition can be removed by dissolving them with an organic solvent, heating them 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 of ​​these alumina particles can then be measured.

[0042] (Average roundness of alumina particles) From the viewpoint of fluidity with epoxy resin, the alumina particles are preferably spherical, and their average roundness is preferably 0.80 to 0.99, and more preferably 0.90 to 0.95. When the average roundness of the alumina particles is within the above range, it is easier to increase the alumina filling rate, sedimentation in the sheet-like resin composition is less likely to occur, and dispersibility is improved, so that appearance defects are less likely to occur and good sealing performance can be achieved. In particular, when the thickness of the sheet-like resin composition is within the above range, the alumina particles (especially particles with small particle diameters) and epoxy resin flow uniformly when heated and pressurized, and voids are less likely to occur after curing. Furthermore, when the average roundness of the alumina particles is high, the kneadability with epoxy resin is also good, which has the effect of increasing the fluidity of the liquid resin composition after kneading and making it easier to mold into a sheet.

[0043] Roundness (SPHT) can be analyzed in accordance with ISO 9276-6. SPHT = 4πA / P ２It can be determined from the following. In the formula, A is the measured area of ​​the projected particle image, and P is the measured outer circumference of the particle projection image. The average roundness 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, CAMSIZER X2 (manufactured by VERDER Scientific)). The average roundness of alumina particles in a sheet-like resin composition can be measured by removing epoxy resin etc. contained in the sheet-like resin composition by dissolving it with an organic solvent, heating it to a temperature of 500°C or higher to cause thermal decomposition, etc., separating only the alumina particles, and using those alumina particles.

[0044] Another method for determining the average roundness of alumina particles is to use image analysis. For a sheet-like resin composition, cross-sectional observation can be performed using a scanning electron microscope (SEM), and all alumina particles contained within a predetermined observation area (e.g., 200 μm × 200 μm) can be image-analyzed. Based on the measurement results of their roundness, the average roundness can be calculated.

[0045] (Particle size of alumina particles) The alumina particles have a particle size D50 of 50% of the cumulative particle size distribution from the finest particle side based on volume, for example, 10 μm or less. Normally, if the particle size of alumina particles is small, aggregation occurs and they tend to settle in the sheet-like resin composition, which tends to worsen the sealing performance of the sheet-like resin composition. However, in the sheet-like resin composition of this disclosure, good sealing performance can be achieved even if the particle size D50 of the alumina particles is 10 μm or less. The D50 of the alumina particles in this disclosure is preferably less than 6.0 μm, more preferably 5.0 μm or less, even more preferably 3.0 μm or less, preferably 0.5 μm or more, more preferably 0.7 μm or more, even more preferably 1.0 μm or more, and particularly preferably 1.5 μm or more. When the D50 of the alumina particles in this disclosure is within the above range, good dispersibility in the epoxy resin can be achieved, making it easier to prevent defects in the appearance of the sheet-like resin composition and further improving sealing performance.

[0046] The particle size D50 of alumina particles can be determined, for example, by measuring the particle size distribution of alumina particles using the laser diffraction method with a Microtrac MT3300EXII laser particle size distribution analyzer manufactured by Microtrac Bell Co., Ltd. The particle size measurement of alumina particles in a sheet-like resin composition can be performed by removing the epoxy resin and other components contained in the sheet-like resin composition, for example by dissolving them with an organic solvent or by thermal decomposition by heating them to a temperature of 500°C or higher, separating only the alumina particles, and then using those alumina particles.

[0047] [Epoxy Resin] In this embodiment, the sheet-like resin composition contains an epoxy resin. The epoxy resin may be a single type or two or more types. Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol AP type epoxy resin, bisphenol AF type epoxy resin, bisphenol B type epoxy resin, bisphenol BP type epoxy resin, bisphenol C type epoxy resin, bisphenol E type epoxy resin, bisphenol F type epoxy resin, bisphenol G type epoxy resin, bisphenol M type epoxy resin, bisphenol S type epoxy resin, bisphenol P type epoxy resin, bisphenol PH type epoxy resin, bisphenol TMC type epoxy resin, bisphenol Z type epoxy resin, bisphenol S type epoxy resin such as hexanediol bisphenol S diglycidyl ether, novolacphenol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, bixylenol type epoxy resin such as bixylenol diglycidyl ether, hydrogenated bisphenol A type epoxy resin such as hydrogenated bisphenol A glycidyl ether, and their dibasic acid modified diglycidyl ether type epoxy resins, aliphatic epoxy resins, and phenylcyclohexyl type epoxy resins. Preferred epoxy resins include phenylcyclohexyl epoxy resins, naphthalene epoxy resins, biphenyl epoxy resins, bisphenol A epoxy resins, and bisphenol F 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 temperature range of 100°C to 200°C during sealing and exhibit liquid crystalline properties.The total amount of phenylcyclohexyl epoxy resin, naphthalene epoxy resin, phenol epoxy resin, biphenyl epoxy resin, bisphenol A epoxy resin, and bisphenol F epoxy resin in 100% by mass of epoxy resin is preferably 95 to 100% by mass, more preferably 98 to 100% by mass, and even more preferably 100% by mass, and among these, it is preferable that the amount of epoxy resin having a mesogenic group satisfies the above range.

[0048] The amount of epoxy resin (total amount if multiple types are included) in 100% by mass of the solid content of the sheet-like resin composition layer is preferably 5% by mass or more and 20% by mass or less, more preferably 7% by mass or more and 18% by mass or less, and even more preferably 8% by mass or more and 16% by mass or less.

[0049] [Phenol-based curing agent] By using a phenol-based curing agent (phenol resin-based curing agent) as a curing agent for sheet-like resin compositions, the reaction rate between the curing agent and the epoxy resin can be suppressed in a room temperature or low temperature environment.

[0050] In embodiments of the present invention, studies were conducted to obtain a sheet-like resin composition that can be stored for a long period of time, and it was found that using a phenolic curing agent is effective. In other words, by using a phenolic curing agent, a sheet-like resin composition suitable for long-term storage can be produced.

[0051] The phenolic curing agent included in the sheet-like resin composition is not particularly limited, but a phenolic resin having two or more phenolic groups in one molecule that are reactive with the glycidyl groups of the epoxy resin is preferred. One type of phenolic curing agent may be used alone, or two or more types may be used in combination. Known phenolic curing agents can be used, and commercially available products can be used.

[0052] Suitable phenolic resins as phenolic curing agents include, for example, resins obtained by condensing or co-condensing phenols such as phenol, cresol, xylenol, resorcinol, catechol, bisphenol A and bisphenol F, naphthols such as α-naphthol, β-naphthol and dihydroxynaphthalene, and aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde and salicylaldehyde under an acidic catalyst; biphenyl skeleton phenolic resins; paraxylylene-modified phenolic resins; metaxylylene / paraxylylene-modified phenolic resins; melamine-modified phenolic resins; terpene-modified phenolic resins; dicyclopentadiene-modified phenolic resins; cyclopentadiene-modified phenolic resins; polycyclic aromatic ring-modified phenolic resins; novolac-type phenolic resins; phenol aralkyl resins; allylphenolic resins; and xylylene-modified naphthol resins. In particular, phenols such as bisphenol A and bisphenol F, biphenyl skeleton-type phenol resins, novolac-type phenol resins, phenol aralkyl resins, or allylphenol resins are preferred, and the use of novolac-type phenol resins, phenol aralkyl resins, or allylphenol resins is more preferred. Examples of novolac-type phenol resins include phenol novolac, catechol novolac, resorcinol novolac, o-cresol novolac, m-cresol novolac, and p-cresol novolac.

[0053] Examples of commercially available phenolic resins include Phenolite LF2882, Phenolite LF2822, Phenolite TD-2090, Phenolite TD-2131, Phenolite TD-2149, Phenolite VH-4150, and Phenolite VH4170 from DIC Corporation; PAPS-PN from Asahi Organic Chemicals Co., Ltd.; XLC-LL and XLC-4L from Mitsui Chemicals, Inc.; SN-100, SN-180, SN-300, SN-395, and SN-400 from Nippon Steel & Sumitomo Metal Chemicals, Ltd.; TrisP-HAP, TrisP-PA, TriP-PHBA, CyRS-PRD4, and MTPC from Honshu Chemical Industry Co., Ltd.; MEHC-7851 from Meiwa Chemicals, Inc.; and LVA from Gun-ei Chemical Industry Co., Ltd.

[0054] The equivalent ratio (phenolic hydroxyl group / glycidyl group (molar ratio)) of the phenolic resin curing agent to the epoxy resin is preferably 0.3 to 1.5, more preferably 0.4 to 1.0, and even more preferably 0.5 to 1.0, from the viewpoint of excellent curability, adhesion, and storage stability of the sheet-like resin composition. When the equivalent ratio is within the above range, the sealing properties and adhesive strength of the sheet-like resin composition tend to improve, the water absorption rate is kept low, and the insulation reliability tends to improve further.

[0055] In one embodiment of the present invention, the content of the phenolic curing agent in the sheet-like resin composition is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 7% by mass or less, and particularly preferably 6% by mass or less, based on 100% by mass of the solid content of the sheet-like resin composition. When the content of the phenolic curing agent is within the above range, the sheet-like resin composition can be stored for a long period of time, and deterioration of the sheet-like resin composition over time during storage is less likely to occur.

[0056] [Solvent] As described above, the sheet-like resin composition according to one embodiment of the present invention always contains a solvent. The resin composition disclosed in Patent Document 1 may or may not contain a solvent. Because the sheet-like resin composition of this disclosure contains a solvent, it is easily fluid, can be easily deformed to conform to the fine structure of IC chips and substrates, and can seal dense structures without gaps. In one embodiment of the present invention, the solvent has a molecular weight of 500 or less, a boiling point of 250°C or less, and is liquid from -40°C to 30°C. The boiling point of the solvent is preferably 200°C or less, more preferably 180°C or less, even more preferably 160°C or less, preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher. When the boiling point of the solvent is within the above range, the reaction between the epoxy resin and the phenolic curing agent can be suppressed and effectively removed during drying when the sheet-like resin composition is formed into a sheet, and the deterioration of the sheet-like resin composition over time can be suppressed.

[0057] Any known solvent can be used, and it is not limited to any solvent that can dissolve epoxy resin. Examples include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, amine-based solvents, amide-based solvents, halogen-based solvents, hydrocarbon-based solvents, and nitrile-based solvents. From the viewpoint of being a good solvent for epoxy resin and having excellent coatability of the resulting resin composition, it is preferable that the resin composition contains one or more solvents selected from the group consisting of ketone-based solvents and ester-based solvents.

[0058] 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. Preferably, the solvent includes one or more selected from the group consisting of methyl ethyl ketone, cyclopentanone, and cyclohexanone. These solvents are liquid at the storage temperature of the sheet-like resin composition (-40°C to 30°C).

[0059] [Other Additives] The sheet-like resin composition may, if necessary, contain 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 mold release agents, either alone or in combination of two or more, as long as they do not impair the effects of the invention.

[0060] In one embodiment of the present invention, the sheet-like resin composition may further contain a curing accelerator. The curing accelerator may be included alone or in combination of two or more types. The curing accelerator may include one or more curing accelerators selected from the group consisting of phosphorus-based curing accelerators and imidazole-based curing accelerators. Examples of phosphorus-based curing accelerators include triphenylphosphine (TPP). Examples of imidazole-based curing accelerators include 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole, and commercially available products include "Cureazole® 2E4MZ-CN" and "Cureazole® 2PHZ-PW" manufactured by Shikoku Chemicals, Inc. When the sheet-like resin composition contains a phosphorus-based curing accelerator and an imidazole-based curing accelerator, deterioration of the sheet-like resin composition over time can be suppressed, making it easier to store the sheet-like resin composition for a long period of time.

[0061] In one embodiment of the present invention, the content of curing accelerators in the sheet-like resin composition (total amount if multiple types are included) is preferably 0.01% by mass or more and 5.0% by mass or less, more preferably 0.05% by mass or more and 0.80% by mass or less, and even more preferably 0.10% by mass or more and 0.50% by mass or less, based on 100% by mass of the solid content of the sheet-like resin composition. When the content of curing accelerators in the sheet-like resin composition is within the above range, deterioration of the sheet-like resin composition over time can be suppressed, and the sheet-like resin composition can be stored for a long period of time.

[0062] [Method for Manufacturing Sheet-Like Resin Compositions] In one example of a method for manufacturing sheet-like resin compositions, first, epoxy resin, a phenolic curing agent, alumina particles, and a solvent are mixed, and the resulting mixture is applied to a substrate. Then, the applied mixture is dried or otherwise removed to remove part of the solvent, thereby obtaining a sheet-like resin composition.

[0063] Known phenolic curing agents can be used. If necessary, 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 mold release agents may be added individually or in combination of two or more, as long as they do not impair the effects of the invention. In particular, it is preferable to add one or more curing accelerators selected from the group consisting of phosphorus-based curing accelerators and imidazole-based curing accelerators.

[0064] The mixing method is not particularly limited, and mills, mixers, stirring blades, etc., can be used. The method of applying the mixture is not particularly limited, but coating equipment such as comma coaters, lip coaters, roll coaters, gravure coaters, die coaters, and spin coaters can be used.

[0065] Drying is preferably carried out by heating, for example, with a heating temperature of 50 to 120°C and a heating time of 5 to 40 minutes, preferably 10 to 30 minutes. In this disclosure, from the viewpoint of easily controlling the amount of solvent in the sheet-like resin composition, it is preferable to carry out heating by a combination of multiple steps with different heating temperatures and heating times, and it is more preferable that the heating temperature increases and the heating time increases with each step. It is preferable that there are two heating steps, in which the first step is a heating temperature of 50 to 70°C and a heating time of 7 to 12 minutes, and the second step is a heating temperature of 80 to 120°C and a heating time of 3 to 30 minutes, preferably 10 to 20 minutes.

[0066] [Method for producing alumina particles] The alumina particles used in this embodiment can be produced, for example, by the method shown below.

[0067] (Alumina raw material) Alumina raw material is produced by known methods. Examples include the Bayer process, ammonium alum process, ammonium aluminum carbonate hydroxide process (AACH process), solvent extraction method, organoaluminum hydrolysis method (aluminum alkoxide process), CZ process, Bernoulli process, Chiroporous process, Bridgman process, EFG process, and other melt growth methods.

[0068] 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.

[0069] (Grinding of raw alumina) In order to easily obtain alumina particles of the desired size by the flame melting method, the raw alumina is ground to obtain alumina raw material powder for flame melting. The raw alumina can be ground using known methods such as a vibratory mill, bead mill, ball mill, or jet mill, and may be ground in either a dry or wet state.

[0070] In the above grinding process, a surface protectant may be used. The surface protectant not only protects the surface of the alumina raw material powder after grinding, but may also have the function of inactivating the surface of the alumina raw material powder. Because the surface protectant reduces aggregation of alumina raw material powders due to its surface inactivation function, it is suitable for obtaining alumina particles of a target particle size after flame melting using raw material alumina with a high BET specific surface area that is prone to aggregation. Suitable surface protectants include, for example, monohydric alcohols such as methanol, ethanol, 1-propanol, and 2-propanol; glycols such as ethylene glycol, polyethylene glycol, propylene glycol, and polypropylene glycol; amines such as triethanolamine; and higher fatty acids such as palmitic acid, stearic acid, and oleic acid. One of these surface protectants may be used alone, or two or more may be used in combination. Of these, glycols are preferred, and one or more of ethylene glycol, polyethylene glycol, propylene glycol, and polypropylene glycol are particularly preferred.

[0071] Polyethylene glycol and polypropylene glycol, which are preferably used as surface protective agents, do not have any particular restrictions on their molecular weight, but liquid forms with an average molecular weight of about 200 to 600 are preferred for ease of addition.

[0072] 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.

[0073] (Flame Melting) The flame melting method is preferred as a method for producing alumina particles having a desired average roundness. The flame melting method is a method in which raw material alumina is sprayed into a flame, liquefied, and then cooled and solidified. In the flame melting method, the temperature of the flame melting furnace is preferably 1000°C or higher. In the flame melting method, the raw material supply rate can be adjusted as appropriate, but it is preferably 50 kg / hour or less, and more preferably 10 kg / hour or less. By setting the amount of thermal energy applied to the alumina particles within a predetermined range, it becomes easier to obtain alumina particles that satisfy the above-mentioned predetermined requirements.

[0074] The alumina particles after flame melting are collected by a cyclone or bag filter and classified as necessary. After classification, it is preferable to immerse the obtained alumina particles in an acidic solution such as hydrochloric acid. The surface of the alumina particles is modified, H ２ O ５５０－９００℃ The concentration can be adjusted to the desired value. Hydrochloric acid is preferred as the type of acidic solution to be used due to the ease of concentration adjustment. The concentration of the acidic solution is preferably 1 M to 12 M, more preferably 1 M to 10 M, and even more preferably 2 M to 5 M. The preferred mass ratio of alumina particles to acidic solution is alumina particles:acidic solution = 1:2 to 1:10. The preferred immersion time is 5 hours or more. The immersion time can be shortened by heating the acidic solution. The temperature of the heated acidic solution is, for example, 50 to 90°C. After immersion in the acidic solution, the alumina particles are washed and dried.

[0075] [Preparation of Alumina Particles] Alumina particles A to C, to be used in the examples and comparative examples, were prepared as follows. Furthermore, various physical properties of the alumina particles (moisture content (H) were also prepared. ２ O ５５０－９００℃The average roundness and BET specific surface area were measured and are listed in Table 1.

[0076] - Alumina particles A: As a raw material, high-purity metallic aluminum obtained by the method described in Japanese Patent Application Publication No. 2010-106329 was prepared. After obtaining aluminum hydroxide from metallic aluminum by the aluminum alkoxide method described in Japanese Patent Application Publication No. 2018-048060, the aluminum hydroxide was calcined to obtain the alumina raw material.

[0077] Next, using a jet mill grinder (horizontal jet mill grinder PJM-280SP manufactured by Nippon Pneumatic Mfg. Co., Ltd.), the raw material alumina was processed under the conditions of a supply rate of 30 kg / hour 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.

[0078] 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 was set to 5 kg / hour. The obtained alumina particles were recovered using a cyclone and subjected to classification by cyclone classification to remove particles larger than 5 μm, thereby obtaining alumina particles (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.

[0079] The obtained alumina particles were immersed in 2M hydrochloric acid. The mass ratio of alumina particles to hydrochloric acid was alumina particles:hydrochloric acid = 1:5, the hydrochloric acid temperature was 80°C, and the immersion time was 12 hours. After immersion in hydrochloric acid, the alumina particles were washed by immersing them in water multiple times. For this washing, the alumina particles and water were placed in a container, and all the water was replaced each time, repeating until the water used for washing became neutral. After the washing was completed, the alumina particles were removed from the container and allowed to stand at 80°C for 6 hours to dry, thereby obtaining alumina particle A. The D50 of alumina particle A was 2.3 μm.

[0080] Alumina particles B were prepared in the same manner as alumina particles A, except that the concentration of the hydrochloric acid used for immersion was changed to 0.1 M. The D50 of alumina particles B was 2.3 μm.

[0081] Alumina particle C: Alumina particle A was dried at 1000°C for 1 hour to obtain alumina particle C. The D50 of alumina particle C was 2.3 μm.

[0082] The following measurements were performed on each alumina particle.

[0083] (H ２ O ５５０－９００℃ (Measurement of moisture content) For each alumina particle, the amount of moisture (H) was measured when the temperature was raised from 550°C to 900°C at a constant rate over 30 minutes using the Karl Fischer method (moisture vaporization-titration method) in accordance with the description in JIS K 0068:2001 "Method for measuring moisture content of chemical products". ２ O ５５０－９００℃ ) was measured.

[0084] (Measurement of average roundness) The average roundness of alumina particles A to C was measured using a CAMSIZER X2 (manufactured by VERDER Scientific) based on the principle of dynamic image analysis in accordance with ISO 13322-2.

[0085] (Measurement of Specific Surface Area) The specific surface area of ​​each alumina particle was measured as follows. A Shimadzu FlowSorb III 2310 was used as the specific surface area measuring device, and the nitrogen adsorption BET specific surface area obtained by the nitrogen adsorption single-point method according to the method specified in JIS-Z8830 (2013) was used as the specific surface area of ​​the alumina particle. The measurement conditions were as follows: Carrier gas: Nitrogen / helium mixed gas filling Sample amount: 0.1 g Sample pretreatment conditions: Treatment at 200°C for 20 minutes Nitrogen adsorption temperature: Liquid nitrogen temperature (-196°C or below) Nitrogen desorption temperature: Room temperature (approximately 20°C)

[0086] [Preparation of Sheet-like Resin Composition] Sheet-like resin compositions were prepared using the alumina particles listed in Table 1 and the epoxy resin, curing agent, and curing accelerator listed in Table 2, following the procedures (1) to (3) described below.

[0087] As shown in Table 2, the epoxy resins used were mesogenic epoxy resin (phenylcyclohexyl epoxy resin (ME); details will be described later), biphenyl epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER YX4000HK), or bisphenol A epoxy resin (manufactured by ADEKA Corporation, EP-4100HF).

[0088] 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.

[0089]

[0090] As shown in Table 2, the curing agents used were phenolic resin (TD-2131 from DIC Corporation, a novolac-type phenolic resin; MEHC-7851 from Meiwa Chemical Industries, Ltd., a biphenol aralkyl resin; allylphenolic resin (phenolic resin represented by the structural formula below); or 4,4-diaminodiphenylmethane (DDM) (from Tokyo Chemical Industries, Ltd.).

[0091]

[0092] As shown in Table 2, triphenylphosphine (TPP) (manufactured by Tokyo Chemical Industry Co., Ltd.) and Cureazole 2E4MZ-CN (manufactured by Shikoku Chemicals Co., Ltd.) were used as curing accelerators.

[0093] As solvents, methyl ethyl ketone (MEK) and cyclopentanone (CYP) were used, either individually or in combination.

[0094] (1) Preparation of varnish [Examples 1-12] An epoxy resin was dissolved in a mixed solvent of methyl ethyl ketone (MEK) and cyclopentanone (CYP) (mass ratio 3:1) to prepare a 30% by mass mixed solution. Furthermore, a curing agent and a curing accelerator were added in predetermined amounts (mixing ratios are shown in Tables 2 and 3) per 100% by mass of the mixed solution to prepare the varnish. The equivalent ratio of the phenolic resin curing agent to the epoxy resin was 1.0.

[0095] [Example 13] A varnish was prepared in the same manner as in Example 1, except that the epoxy resin was dissolved in methyl ethyl ketone (MEK).

[0096] (2) Preparation of alumina / varnish mixture Alumina particles were added to the obtained varnish in the proportions shown in Tables 2 and 3, and the mixture was kneaded at 2000 rpm for 60 seconds using a rotational mixer (manufactured by Sinky Co., Ltd.) to prepare the alumina / varnish mixture.

[0097] (3) Film Forming and Drying The obtained alumina / varnish mixture was applied to a PET substrate and, using an applicator, was formed to create a sheet-like resin composition with a thickness of 300 μm (0.30 mm) after drying. Then, it was heated under the conditions shown in Table 8. By heating, the solvent was evaporated and the sheet-like resin composition was formed on the PET substrate (sheet-like resin composition with PET substrate). The drying conditions were carried out in the order of the first drying step and the second drying step. The heating temperature was determined by measuring the temperature of the PET substrate with a thermocouple. In Comparative Example 3, after drying under the conditions shown in Table 8, vacuum drying was further performed at 25°C for 12 hours.

[0098] The following tests were performed on the obtained sheet-like resin composition.

[0099] (i) Thickness measurement of the sheet-like resin composition The thickness of the sheet-like resin assembly was calculated by using a micrometer (Mitutoyo Corporation, PMU150-25MX) to measure the total thickness of the PET substrate and the sheet-like resin composition, and the thickness of the PET substrate, respectively, and subtracting the thickness of the PET substrate from the total thickness. Five arbitrary measurement points were selected, and the average value was calculated from the thickness of the sheet-like resin composition obtained at each measurement point using the above method, and this average value was taken as the thickness of the sheet-like resin composition (average thickness). The thickness of the sheet-like resin composition was 0.30 mm in all cases.

[0100] (ii) Measurement of Solvent Content The solvent content of the sheet-like resin composition was determined by the following measurement. A 4 cm square sample was cut from each example and comparative example of the PET substrate-attached 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 W3 (g) of the PET substrate was measured. The mass of the sample before and after heating was 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 solvent contained in the sheet-like resin composition. The ratio of the mass of solvent to the mass of the sample before heating was taken as the solvent content. The formula for calculating the solvent content is as follows: Solvent content (mass%) = {(W1 - W3) - (W2 - W3)} / (W1 - W3) × 100 ... (2) Substituting the mass of the sample before heating X1 (g) = W1 - W3 and the mass of the sample after heating X2 (g) = W2 - W3 into the above formula (2), we obtain the following formula (1): Solvent content (mass%) = (X1 - X2) / X1 × 100 ... (1)

[0101] (iii) Presence or absence of dendritic defects A 5 cm square sheet-like resin composition with a PET substrate (observation sample) was prepared and stored in a freezer at -20°C. One hour, one day, and one week after the start of storage, the observation sample was removed from the freezer and both sides of the observation sample were visually inspected to check for the presence or absence of dendritic defects. If one or more dendritic defects were found, it was judged that "defects were found". Based on the evaluation criteria described in Table 5, the PET substrate-like sheet-like resin compositions (observation samples) obtained in the examples and comparative examples were evaluated and the results are shown in Table 4. Evaluations A to C are considered passing grades, and evaluation D is considered failing grades.

[0102] (iv) Evaluation of sealing properties To evaluate the sealing properties of the sheet-like resin composition, the gelation time of the sheet-like resin composition was used as an indicator. The gelation time is the time it takes for the sheet-like resin composition to soften (gel) and reach the optimal state for sealing (gel state). Dynamic viscoelasticity measurements were performed using a rheometer (Anton Paar, MCR302) (measurement conditions: starting temperature: 25°C, target temperature: 140°C (heating from 25°C to 135°C at 0.93°C / sec, from 135°C to 140°C at 0.03°C / sec, then held at 140°C), frequency 1 Hz, normal force 1 N, strain control 0.05%, sample size 1 cm square × thickness 0.3 mm). The gelation time was defined as the time it took for the composition to soften from its initial complex viscosity value to a predetermined viscosity of 200 Pa·s or less and then return to its original initial viscosity.

[0103] A 1 cm square sheet-like resin composition (measurement sample) was prepared and stored in a -20°C freezer for 3 months. After that, the measurement sample was removed from the freezer and left to stand to return to room temperature. The gelation time was measured using the dynamic viscoelasticity measurement described above, and the sealing properties (presence or absence of deterioration due to changes over time) were evaluated. Based on the evaluation criteria described in Table 6, the measurement samples for the examples and comparative examples were evaluated and the results are shown in Table 4. Evaluations A to C are considered passing grades, and evaluation D is considered failing grade.

[0104] (v) Presence or absence of mesh-like patterns A 5 cm square sheet-like resin composition with a PET substrate (observation sample) was prepared and stored at room temperature (20°C). Twelve hours, one day, and two days after the start of storage, both sides of the observation sample were visually observed to check for the presence or absence of a mesh-like pattern. If a visible pattern was observed, it was judged that "a pattern was observed". Based on the evaluation criteria described in Table 7, the PET substrate-like sheet-like resin compositions (observation samples) obtained in the examples and comparative examples were evaluated and the results are shown in Table 4. Evaluations A to C are considered passing grades, and evaluation D is considered failing grades.

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113] The sheet-like resin compositions obtained in Examples 1 to 13 were found to have superior sealing properties after long-term storage and to be less prone to appearance defects after long-term storage compared to the sheet-like resin compositions obtained in Comparative Examples 1 to 3.

Claims

1. A sheet-like resin composition comprising alumina particles, epoxy resin, a phenolic curing agent, and a solvent, wherein the proportion of alumina particles in 100% by mass of solids is 40% by mass or more and 99% by mass or less, and the content of the solvent is 0.10% by mass or more and 5.00% by mass or less.

2. The sheet-like resin composition according to claim 1, wherein the solvent comprises one or more selected from the group consisting of ketone-based solvents and ester-based solvents.

3. The sheet-like resin composition according to claim 1 or 2, wherein the alumina particles have a moisture content of 1.0 ppm or more and 100 ppm or less at temperatures from 550°C to 900°C, as measured by Karl Fischer measurement.

4. The alumina particles have a BET specific surface area of ​​0.2 m² as measured by the nitrogen adsorption method. ２ / g or more 10m ２ A sheet-like resin composition according to claim 1 or 2, wherein the amount is less than or equal to / g.

5. The sheet-like resin composition according to claim 1 or 2, wherein the average roundness of the alumina particles is 0.80 or more and 0.99 or less.

6. The sheet-like resin composition according to claim 1 or 2, wherein the thickness is 0.10 mm or more and 1.00 mm or less.

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