Resin composition, sheet molding compound, and alumina particles used in resin composition

Abstract

Provided is a resin composition containing alumina particles and a resin, the resin composition having a lower quantity of electric charge than conventional resin compositions. The resin composition contains alumina particles, which generate moisture in an amount exceeding 59.8 ppm when heated from 200°C to 900°C, and a resin.

Description

Resin composition and sheet molding compound, and alumina particles used in the resin composition

[0001] The present disclosure relates to resin compositions and sheet molding compounds, as well as alumina particles used in the resin compositions.

[0002] Since heat generated by passing current through electronic components tends to adversely affect the performance of the electronic components, it is desirable for the heat to be dissipated quickly. Therefore, for example, it is desirable for the material constituting a semiconductor encapsulation member surrounding an IC chip to exhibit high thermal conductivity for heat dissipation. Such encapsulation members generally contain inorganic particles (e.g., alumina particles) and resin, as described in Patent Document 1.

[0003] Japanese Patent Application Laid-Open No. 2020-200478

[0004] Adhesion of dust and other particles during the manufacture of semiconductor devices can cause defective products. In particular, in recent years, with the miniaturization of semiconductor devices and the narrowing of wiring pitches, even the adhesion of fine dust has become a problem. In order to more reliably suppress the adhesion of fine dust, resin compositions used in semiconductor encapsulation members are required to have a lower charge amount than ever before. However, no specific method for reducing the charge amount of resin compositions is known. Patent Document 1 does not consider the charge amount of resin compositions at all.

[0005] In view of these circumstances, one embodiment of the present invention aims to provide a resin composition containing alumina particles and a resin, which has a lower charge amount than conventional resin compositions. Another embodiment of the present invention aims to provide a sheet-shaped composition (sheet molding compound) made of such a resin composition. Yet another embodiment of the present invention aims to provide alumina particles used in the resin composition.

[0006] A first aspect of the present invention is a resin composition comprising: alumina particles that generate more than 59.8 ppm of moisture when heated at 200°C to 900°C; and a resin.

[0007] A second aspect of the present invention is the resin composition according to the first aspect, wherein the alumina particles generate more than 43.0 ppm of moisture when heated from 200°C to 550°C.

[0008] A third aspect of the present invention is the resin composition according to the first or second aspect, wherein the alumina particles have an absolute value of a charge of 0.17 kV or less.

[0009] In the fourth aspect of the present invention, the alpha dose is 0.022 cph / cm ２ The resin composition according to any one of Aspects 1 to 3, wherein the total mass of the resin composition is less than 1000 kJ / cm 2 .

[0010] Aspect 5 of the present invention is the resin composition according to any one of Aspects 1 to 4, wherein the alumina particles have a ratio (L2 / L1) of a total length L2 of internal grain boundaries to a length L1 of an outer edge of the alumina particles, of less than 139.1%.

[0011] A sixth aspect of the present invention is a sheet molding compound comprising the resin composition according to any one of the first to fifth aspects and having a thickness of 1000 μm or less.

[0012] A seventh aspect of the present invention is alumina particles that generate more than 59.8 ppm of moisture when heated from 200°C to 900°C.

[0013] According to one embodiment of the present invention, a resin composition having a lower charge amount than conventional resin compositions can be provided. According to another embodiment of the present invention, a sheet molding compound comprising such a resin composition can be provided. According to yet another embodiment of the present invention, alumina particles for use in the resin composition can be provided.

[0014] The inventors conducted extensive research into resin compositions with lower electrostatic charge levels than ever before in order to minimize the risk of fine dust particles adhering to the resin composition. As a result, they discovered for the first time that the electrostatic charge level of a resin composition can be effectively reduced by adjusting the amount of water contained in the alumina particles used in the resin composition to a certain level or more, and thus completed the present invention.

[0015] The resin composition according to the embodiment, the alumina particles used in the resin composition, and the sheet molding compound (SMC) made of the resin composition will be described below.

[0016] [Resin Composition] The resin composition according to this embodiment contains alumina particles and a resin. The alumina particles used have a moisture content of more than 59.8 ppm when heated from 200°C to 900°C. In this specification, the term "resin composition" is intended to include all states of resin compositions, including a liquid state before the resin in the resin composition is cured, a semi-cured state (B stage) in which the resin is semi-cured, and a cured state (C stage) in which the resin is completely cured. Here, "liquid state" also includes compositions in which the resin composition has fluidity, such as resin compositions containing solvents, as described below. "Semi-cured" refers to a state in which the resin composition has cured to the extent that it can be handled as a solid, but is not completely cured, and therefore the surface of the resin composition remains tacky. "Cured state" refers to a state in which the resin composition can be handled as a solid and has almost no tackiness on its surface.

[0017] Regarding the charge amount of a resin composition, the lower the absolute value of the charge amount, the less likely the resin composition is to become charged and attract dust. The inventors discovered that by forming a resin composition using alumina particles whose moisture content is controlled to a certain amount or more, the absolute value of the charge amount of the resulting resin composition can be reduced. In the resin composition according to the embodiment, in particular, by using alumina particles whose moisture content is greater than 59.8 ppm when heated from 200°C to 900°C, the absolute value of the charge amount of the resin composition can be set to 0.00 kV (substantially no charge). Therefore, the resin composition according to the embodiment can effectively suppress the adhesion of fine dust.

[0018] The alpha dose of the resin composition is 0.022 cph / cm ２It is preferable that the α dose of the resin composition is less than 0.020 cph / cm. This is because semiconductor devices are easily affected by α rays, and malfunctions (soft errors) caused by α rays are likely to become a problem. In addition, it is expected that a low α dose will make it difficult for the resin composition to be charged by the ionizing action of α rays. Therefore, it is considered that a resin composition with an extremely low charge amount can be formed relatively easily. The α dose of the resin composition is preferably 0.020 cph / cm. ２ or less, more preferably 0.015 cph / cm ２ More preferably, 0.005 cph / cm or less ２ Below 0.002 cph / cm, particularly preferably ２ In particular, the alpha dose of the cured resin composition is 0.022 cph / cm or less. ２ Less than 0.020 cph / cm ２ Below, 0.015cph / cm ２ Below, 0.005cph / cm ２ or less than 0.002 cph / cm ２ The lower the α dose of the resin composition, the more preferable it is, and the preferred lower limit is 0.000 cph / cm ２ The alpha dose of the resin composition is measured in a semi-cured or cured state using an alpha ray measuring device (e.g., Model 1950 manufactured by Alpha Sciences). The measurement area of ​​the sample is 1000 cm. ２ The measurement time was 99 hours, and the counting gas was PR-10 gas (Ar 90%, CH ４ 10%) is used.

[0019] The rupture stress measured for the resin composition in a semi-cured or cured state is preferably greater than 41.2 MPa, more preferably greater than 50.0 MPa, even more preferably greater than 60.0 MPa, and particularly preferably greater than 65.0 MPa. In particular, it is preferable for the rupture stress of the cured resin composition to be greater than 41.2 MPa, greater than 50.0 MPa, greater than 60.0 MPa, or greater than 65.0 MPa, in that order. This improves the strength of the resulting sealing member and also improves dimensional stability against external energy such as heat. The rupture stress of the resin composition can be calculated from a stress-strain curve obtained in a tensile test in accordance with JIS K7161 (2014). The rupture stress of the resin composition in a semi-cured or cured state can be increased by adjusting the alumina particle content and curing conditions. Typically, the rupture stress of a resin composition in a cured state is higher than that of a resin composition in a semi-cured state.

[0020] The absorption energy until breakage measured for the resin composition in a semi-cured or cured state is preferably 0.200 MPa or more, more preferably greater than 0.314 MPa, even more preferably 0.400 MPa or more, even more preferably 0.500 MPa or more, and particularly preferably 0.600 MPa or more. In particular, it is preferable that the absorption energy until breakage of the resin composition after curing is greater than 0.314 MPa, 0.400 MPa or more, 0.500 MPa or more, or 0.600 MPa or more, in that order. This improves the strength when used as a sealing member and can also improve dimensional stability against external energy such as heat. The absorption energy until breakage of the resin composition can be calculated from the area enclosed by the stress-strain curve obtained in a tensile test in accordance with JIS K7161 (2014). The absorption energy until breakage of the resin composition in a semi-cured or cured state can be increased by adjusting the content of alumina particles and the curing conditions. Generally, the absorbed energy until breakage is higher in a cured resin composition than in a semi-cured state.

[0021] The correlation coefficient when linearly approximating the stress-strain curve up to breakage measured for a resin composition in a semi-cured or cured state preferably exceeds 0.9765. A large correlation coefficient indicates that the resin composition stretches uniformly, and may mean, for example, that the inorganic particles are uniformly dispersed in the resin without agglomeration. In this case, appropriate particle-resin interactions are facilitated, making it easier to ensure dimensional stability against external energy such as heat. The correlation coefficient is preferably 0.9780 or greater, and more preferably 0.9795 or greater. In particular, the correlation coefficient when linearly approximating the stress-strain curve up to breakage of a cured resin composition is preferably greater than 0.9765, 0.9780 or greater, or 0.9795 or greater, in that order. The upper limit of the correlation coefficient is 1.0000.

[0022] Since alumina particles can form a resin composition without impairing the flexibility inherent to resins, their blending ratios, relative to the total resin composition, are preferably 5 to 75 volume% resin, 95 to 25 volume% alumina particles, or 8 to 50 volume% resin, 92 to 50 volume% alumina particles, or 10 to 40 volume% resin, 90 to 60 volume% alumina particles, or 12 to 40 volume% resin, and 88 to 60 volume% alumina particles. Furthermore, in semi-cured and cured resin compositions, the total proportion of resin and alumina particles relative to the total resin composition is preferably 60 volume% or more, more preferably 70 volume% or more, and even more preferably 80 volume% or more. Furthermore, in semi-cured and cured resin compositions, the proportion of solids relative to the total resin composition is preferably 80 volume% or more, more preferably 90 volume% or more, and even more preferably 95 volume% or more. The solid content of a resin composition refers to what remains as a solid when the resin composition is heated, excluding components that volatilize upon heating, such as the solvent. On the other hand, even if a component is liquid at 25°C, if it is incorporated into the solid content of the resin composition when heated, it is included in the solid content. The proportion of solids can be determined, for example, by determining the amount of solvent in the resin composition and subtracting it from the total. The amount of solvent in a resin composition can be measured, for example, by the following method. After measuring the mass W1 (g) of the resin composition, a sample is heated at 150°C for 10 minutes using a full exhaust oven to evaporate all of the solvent contained in the sample, and then the sample is left at room temperature for 5 minutes to return to room temperature, and the mass W2 (g) of the heated sample is measured. The amount of solvent in the resin composition can be determined by subtracting W2 (g) from W1 (g).

[0023] Next, the alumina particles and resin that constitute the resin composition will be described in detail.

[0024] [Alumina Particles] The alumina particles according to this embodiment have the following characteristics. The alumina particles preferably contain α-alumina particles. α-alumina is expected to have the effect of reducing the amount of α-rays emitted from the alumina particles, and the presence of α-alumina particles in the alumina particles can result in an improved effect of suppressing the amount of α-rays emitted from the resin composition. Furthermore, the α-alumina particles are also expected to have the effect of reducing the dielectric loss of the resin composition.

[0025] (Moisture content of alumina particles) The alumina particles according to the embodiment have a moisture content (sometimes referred to as the "total moisture content") of more than 59.8 ppm generated upon heating from 200°C to 900°C. By using alumina particles containing a certain amount of moisture or more, the charge amount of the resin composition can be effectively reduced. The total moisture content of the alumina particles is preferably 70.0 ppm or more, more preferably 80.0 ppm or more, and particularly preferably 95.0 ppm or more. The upper limit of the total moisture content of the alumina particles is not particularly limited from the viewpoint of reducing the charge amount of the resin composition, but may be 200.0 ppm or less.

[0026] Of the total moisture content of the alumina particles, the amount of moisture generated by heating from 200°C to 550°C (sometimes referred to as the "low-temperature side moisture content") may have a significant effect on the charge amount of the resin composition. The low-temperature side moisture content is preferably controlled to more than 43.0 ppm, thereby further reducing the charge amount of the resin composition. The low-temperature side moisture content of the alumina particles is more preferably 60.0 ppm or more, even more preferably 70.0 ppm or more, and particularly preferably 80.0 ppm or more. The upper limit of the low-temperature side moisture content of the alumina particles is not particularly limited from the viewpoint of reducing the charge amount of the resin composition, but may be 185.0 ppm or less.

[0027] The moisture content of the alumina particles (total moisture content and low-temperature moisture content) is measured based on the Karl Fischer titration method (moisture vaporization-titration method) in accordance with JIS K 0068:2001 "Method for measuring moisture content in chemical products."

[0028] (Amount of Charge of Alumina Particles) The alumina particles according to the embodiment preferably have an absolute value of the amount of charge of 0.17 kV or less. This can further reduce the amount of charge of the resin composition and improve the dispersibility of the alumina particles in the resin. In other words, since the alumina particles are dispersed relatively uniformly within the resin composition, the physical properties of the resin composition (breaking stress, absorbed energy until breakage, correlation coefficient when linearly approximating the stress-strain curve of the resin composition until breakage) can be improved. The amount of charge of the alumina particles can be affected by the amount of water contained in the alumina particles, the unevenness of the alumina particle surface, the disorder of the crystal structure of the alumina particles, etc., but it is believed that the amount of water is particularly influential. Therefore, the amount of charge can be controlled by controlling the amount of water in the alumina particles.

[0029] The absolute value of the charge amount of the alumina particles is more preferably 0.15 kV or less, even more preferably 0.10 kV or less, particularly preferably 0.08 kV or less, particularly more preferably 0.05 kV or less, and most preferably 0.02 kV or less. The lower the absolute value of the charge amount of the alumina particles, the better, with a preferred lower limit being 0.00 kV. The charge amount of the alumina particles is measured using a static electricity meter in accordance with JIS C 61340-2-1. For example, this can be done using a commercially available potential meter, a coulomb meter, a Faraday cage, or the like.

[0030] When measuring the water content and charge amount of alumina particles in a resin composition, first, the resin contained in the resin composition is removed by, for example, dissolving it in an organic solvent, etc., to separate only the alumina particles. The water content and charge amount can be measured using the separated alumina particles.

[0031] (Uranium Content and Thorium Content) The alumina particles have a uranium content of less than 550 ppb and a thorium content of less than 10 ppb. 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 resin composition can be suppressed. This makes it possible to suppress malfunction of the semiconductor device due to α-rays when used as an encapsulating material for a semiconductor device.

[0032] 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 can be measured by inductively coupled plasma mass spectrometry (ICP-MS).

[0033] (Ratio of the total length L2 of grain boundaries inside an alumina particle to the length L1 of the outer edge of the particle) Reducing the content of grain boundaries inside an alumina particle can improve the shielding effect against alpha rays generated from uranium and thorium inside the alumina particle, thereby reducing the amount of alpha rays emitted from the alumina particle. In this embodiment, the ratio (L2 / L1) of the total length L2 of the grain boundaries to the length L1 of the outer edge is introduced as an index of the content of grain boundaries inside an alumina particle. L1 and L2 are determined by observing the cross section of the alumina particle.

[0034] When the length of the outer edge of one alumina particle is L1 and the total length of the grain boundaries of that alumina particle is L2, alumina particles with a small value of L2 / L1 can be said to have a low content of grain boundaries and emit a low amount of alpha rays. In particular, it is preferable that (L2 / L1) (%) is less than 139.1%, which can further reduce the amount of alpha rays emitted when used as a filler for a resin composition. By reducing the amount of alpha rays emitted from the alumina particles, the amount of alpha rays emitted from a resin composition containing the alumina particles can also be reduced.

[0035] (L2 / L1) is preferably 120.0% or less, more preferably 100.0% or less, even more preferably 80.0% or less, even more preferably 60.0% or less, particularly preferably 52.0% or less, and most preferably 50.0% or less. The lower limit of (L2 / L1) is not particularly limited, but may be 10.0% or more, for example, 20.0% or more, 30.0% or more, 40.0% or more, or 43.0% or more. When the lower limit of L2 / L1 is within the above range, particle-resin interactions are more likely to occur, and in particular, the mechanical strength, such as the breaking stress, of the resin composition after semi-curing and curing is more likely to be increased. In order to control this L2 / L1 within a suitable range, single-crystal raw material particles may be used.

[0036] The "total length L2 of the grain boundaries" refers to the sum of the grain boundaries contained within the alumina particle and does not include the outer edges of the alumina particle. The total length L2 of the grain boundaries is the sum of the total length L3 of the grain boundaries within the alumina particle and the total length L4 of the inner walls of the cavities (if any) within the alumina particle (i.e., L2 = L3 + L4).

[0037] (Particle diameter of alumina particles) The particle diameter D50 of the alumina particles, which is the cumulative 50% particle diameter from the fine particle side of the volume-based cumulative particle size distribution, is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 20 μm or less, even more preferably 10 μm or less, particularly preferably 5 μm or less, and most preferably 3 μm or less. By having D50 within the above range, a resin composition suitable for miniaturizing semiconductor devices and narrowing the wiring pitch can be formed.

[0038] The alumina particles preferably have a ratio D90 / D50 of 5.0 or less, where D90 is the particle diameter at 90% of the cumulative number of particles counting from the finest particle side of the cumulative particle size distribution (hereinafter sometimes simply referred to as "D90") and D50 is the particle diameter at 50% of the cumulative number of particles counting from the finest particle side of the cumulative particle size distribution (hereinafter sometimes simply referred to as "D50"). This results in a sharp particle size distribution, facilitates appropriate particle-resin interaction, and particularly facilitates increasing the mechanical strength, such as the breaking stress, of the resin composition after semi-curing and curing. For example, D90 / D50 is more preferably 4.0 or less, even more preferably 3.0 or less, and particularly preferably 1.5 or less.

[0039] On the other hand, if the particle size distribution of the alumina particles is broad to some extent, the filling ability is improved by allowing small particles to fill the gaps between large particles, and more alumina particles can be kneaded into the resin, thereby improving the dimensional stability and breaking stress against external energy such as heat. Therefore, D90 / D50 is preferably 1.1 or more, more preferably 1.2 or more, and even more preferably 1.3 or more.

[0040] The particle diameters D50 and D90 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 resin composition can be measured by removing the resin contained in the resin composition by, for example, dissolving it in an organic solvent or by heating it to a temperature of 500°C or higher to pyrolyze the resin, and isolating only the alumina particles, and using the alumina particles.

[0041] Another method for determining the D50 and D90 of alumina particles is a method using image analysis. The resin composition may be subjected to cross-sectional observation using an SEM, and all alumina particles contained in a predetermined observation area (e.g., 200 μm × 200 μm) may be subjected to image analysis, and the particle diameters equivalent to D50 and D90 may be calculated based on the measurement results of their particle diameters (circle-equivalent diameters).

[0042] [Method for Producing Alumina Particles] The alumina particles according to this embodiment can be produced, for example, by the method described below.

[0043] (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.

[0044] In the case of the Bayer process, raw alumina can be produced by calcining aluminum hydroxide obtained from bauxite. Furthermore, the ammonium alum process, the AACH process, the solvent extraction process, and the aluminum alkoxide process are preferred because they allow for the production of high-purity raw alumina with low uranium and thorium contents. Raw alumina produced by these processes, with a uranium content of less than 550 ppb and a thorium content of less than 10 ppb, respectively, is preferably used to produce alumina particles, since alumina particles with reduced uranium and thorium contents can be obtained.

[0045] (Pulverization of Raw Alumina) In order to easily obtain alumina particles of a desired size by flame melting, the raw alumina is pulverized to obtain an alumina raw powder to be subjected to flame melting. Pulverization of the raw alumina can be carried out by a known method such as a vibration mill, a bead mill, a ball mill, or a jet mill, and may be carried out in either a dry or wet state.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] (Flame fusion) The flame fusion method is a method in which raw alumina is sprayed into a flame, turned into droplets, and then cooled and solidified. According to the flame fusion method, alumina particles can be obtained while roughly maintaining the particle diameter 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, 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.

[0050] 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.

[0051] The moisture content of the alumina particles can be controlled by the manufacturing method of the raw alumina, the pulverization method, and the conditions of the flame fusion method, but it can also be controlled by immersing the obtained alumina particles in an acidic solution such as hydrochloric acid. The type of acidic solution used during immersion is preferably hydrochloric acid because of its ease of concentration adjustment. The concentration of the acidic solution is preferably adjusted to 1 M to 12 M, more preferably 1 M to 10 M, and particularly preferably 2 M to 5 M. The mass ratio during immersion, i.e., alumina particles to acidic solution, is preferably 1:2 to 1:10. The immersion time is preferably 5 hours or longer. During immersion, heating may be performed as appropriate to shorten the immersion time, for example, heating to 50 to 90°C. After immersion, washing and drying are preferably performed.

[0052] [Resin] The resin used in the resin composition preferably includes one or more resins selected from the group consisting of epoxy resins and thermoplastic polyimides, and more preferably includes an epoxy resin. Preferred epoxy resins include mesogenic epoxy resins, phenylcyclohexyl epoxy resins, naphthalene epoxy resins, phenolic epoxy resins, biphenyl epoxy resins, butadiene epoxy resins, and bisphenol A epoxy resins. The mesogenic epoxy resin is an epoxy resin having a mesogenic group, and is preferably a resin that exhibits a phase transition temperature in the temperature range of 100°C to 200°C and exhibits liquid crystallinity. The resin contained in the resin composition may include one or more epoxy resins. That is, the resin contained in the resin composition may include one or more epoxy resins selected from the group consisting of mesogenic epoxy resins, phenylcyclohexyl epoxy resins, naphthalene epoxy resins, phenolic epoxy resins, biphenyl epoxy resins, butadiene epoxy resins, and bisphenol A epoxy resins, and may further include a thermoplastic polyimide. These resins are expected to have the effect of shielding alpha rays emitted from the alumina particles, and therefore it is possible to obtain a resin composition with even lower alpha rays.

[0053] Furthermore, these resin compositions may contain known additives, such as plasticizers, curing agents, curing accelerators, coupling agents, fillers, pigments, flame retardants, antioxidants, surfactants, compatibilizers, weathering agents, antiblocking agents, antistatic agents, leveling agents, and mold release agents, either singly or in combination, as long as the effects of the invention are not impaired. In one embodiment of the present application, the resin composition (particularly a liquid or semi-cured resin composition) may contain a solvent. When the resin composition contains a solvent, it is highly fluid, can be easily deformed to fit the fine structures of IC chips and substrates, and can seal dense structures without gaps. Known solvents may be used, and are not limited as long as they can dissolve the resin. Examples of such solvents 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 because they are good solvents for epoxy resins and provide excellent coatability for the resulting resin composition.

[0054] In a preferred embodiment of the present invention, the resin composition comprises alumina particles, an epoxy resin, a solvent, and a curing agent, such as an amine-based curing agent such as 4,4-diaminodiphenylmethane.

[0055] [Method for Producing Resin Composition] The method for producing the resin composition will be described. A resin composition can be obtained by mixing the alumina particles according to this embodiment with a resin using a commonly used known method. For example, when the resin is liquid (e.g., liquid epoxy resin), the liquid resin, alumina particles, and a curing agent are mixed, and then cured with heat or ultraviolet light to obtain a resin composition. Known curing agents, mixing methods, and curing methods can be used. On the other hand, when the resin is solid (e.g., epoxy resin, polyolefin resin, acrylic resin, etc.), the alumina particles and resin can be mixed, and then kneaded using a known method such as melt kneading, or the resin, alumina particles, and curing agent can be dissolved and mixed in a solvent to obtain the desired resin composition. The resin composition may contain a solvent.

[0056] The resin composition according to this embodiment includes resin compositions in all states, including a liquid state before the resin in the resin composition is cured, a semi-cured state (B stage) in which the resin is semi-cured, and a cured state (C stage) in which the resin is completely cured. Liquid resin compositions include blends in which alumina powder and resin are blended in a predetermined ratio, mixtures obtained by mixing such blends, and molded articles obtained by molding such mixtures. Semi-cured resin compositions include resin compositions obtained by semi-curing the resin contained in the mixture or molded article. Cured resin compositions include resin compositions obtained by completely curing the resin contained in the mixture, molded article, or semi-cured article.

[0057] [Sheet Molding Compound (SMC)] A sheet molding compound (SMC) can be provided using the resin composition according to the embodiment. The SMC is a resin composition molded into a sheet. The SMC preferably has fluidity when heated and pressurized, and may be in a semi-cured state. The SMC preferably has a thickness of 1000 μm or less. When incorporated into a semiconductor device, the semiconductor device can be made smaller and lighter, and the sealing performance can be improved when sealing an IC chip. The thickness is more preferably 800 μm or less, even more preferably 600 μm, even more preferably 500 μm or less, particularly preferably 400 μm or less, and particularly preferably 300 μm or less. The lower limit of the thickness is not particularly limited, but may be, for example, 10 μm or more, 50 μm or more, or even 100 μm or more, or 150 μm or more, depending on the dimensions of commonly used SMCs and the ability to enhance the sealing performance of IC chips.

[0058] SMCs can be produced by known methods. For example, an uncured resin composition is applied to a substrate, a protective film is placed thereon, and the resin composition is semi-cured. Another example is a solvent-containing uncured resin composition applied to a substrate, the solvent is removed from the resin composition by drying, or the like, and then a protective film is placed thereon. When using an SMC, the protective film is peeled off, the SMC is pressure-bonded to a wafer or the like, the substrate is removed, and the SMC is post-cured.

[0059] The resin composition and SMC of the present invention have a low alpha radiation dose and are therefore suitable as sealing materials for semiconductor elements.

[0060] [Preparation of Alumina Particles] The alumina particles (A to C) used in the resin compositions of Samples No. 1 to 5 were prepared as follows.

[0061] (Alumina particles A and B used in samples Nos. 1 to 4) As alumina particles, the following alumina particles A (used in samples Nos. 3 and 4) and alumina particles B (used in samples Nos. 1 and 2) were prepared.

[0062] As the raw alumina, γ-alumina obtained by the ammonium alum method (the average particle size of the primary particles calculated from the value of the BET specific surface area described below was 13 nm) was used. The BET specific surface area of ​​this γ-alumina measured by the nitrogen adsorption method was 120 m ２ Before pulverization, 4 mass % of propylene glycol was added as a surface protective agent to the raw alumina and mixed.

[0063] Next, the mixture was treated using a jet mill pulverizer (horizontal jet mill pulverizer PJM-280SP manufactured by Nippon Pneumatic Mfg. Co., Ltd.) under the 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 particle size of secondary particles of about 2 μm.

[0064] 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 classified by cyclone classification to remove particles of 20 μm or larger, thereby obtaining alumina particles A (D50 = 5.1 μm, used for Samples No. 3 and 4). Furthermore, particles of 10 μm or larger were removed to obtain alumina particles B (D50 = 2.3 μm, used for Samples No. 1 and 2).

[0065] (Alumina particles C used in sample No. 5) For sample No. 5, alumina particles (alumina particles C) manufactured by Denka DAW05 were used.

[0066] The alumina particles used in each sample were subjected to the following measurements.

[0067] [Particle size distribution of alumina particles] The particle size distribution of alumina particles, D50 and D90, was measured by laser diffraction using a Microtrac MT3300EXII laser particle size distribution analyzer manufactured by Microtrac Bell Co., Ltd. The D50 and D90 were determined from the particle size distribution measurement results. The measurement sample was an alumina particle dispersion obtained by adding the alumina particles to be measured to a 0.2% by mass aqueous solution of sodium hexametaphosphate so that the laser scattering intensity was appropriate, and dispersing the alumina particles for 5 minutes using the built-in ultrasonic wave at 40 W. The refractive index of alumina was 1.76.

[0068] [Charge Amount of Alumina Particles] The charge amount of alumina particles was measured using a static electricity meter under the following conditions: - Static electricity meter: FMX-004 (manufactured by SIMCO) - Measurement mode: Low MODE - Temperature: 23°C, humidity: 40% - 10 g of alumina particles were placed in an aluminum cup, and the static electricity meter was placed at a height of 25 mm from the surface to measure the charge potential. The obtained charge potential value is defined as the charge amount.

[0069] [Moisture Content of Alumina Particles] The moisture content of the alumina particles was measured by Karl Fischer titration (moisture vaporization-titration method) in accordance with JIS K 0068:2001 "Method for measuring moisture content in chemical products." Two moisture content measurements were performed: the amount of moisture generated upon heating from 200°C to 550°C (low-temperature moisture content) and the amount of moisture generated upon heating from 200°C to 900°C (total moisture content).

[0070] [Measurement of the length L1 of the outer edge of an alumina particle and the total length L2 of the grain boundary inside the particle] Samples for cross-sectional observation were prepared using alumina particles Nos. 1 to 5. To prepare the cross-sectional observation samples, the alumina particles were embedded in resin, and then the resin and alumina particles were cut using a diamond cutter. Subsequently, a protective film of platinum was vapor-deposited on the cross-section, and the cross-section was prepared by Ar ion milling. The sample was then fixed to the SEM sample stage with Cu double-sided tape, and SEM-EBSD measurement was performed without vapor deposition. The observation position was determined so that two or more alumina particles were completely contained within the observation area (i.e., two or more alumina particles did not come into contact with the frame of the observation area). All of the measured alumina particles were α-alumina particles.

[0071] The following equipment was used for sample pretreatment and EBSD measurement: Equipment used Ion milling equipment: IM-4000 (manufactured by Hitachi, Ltd.) Ion sputtering equipment: E-1030 (manufactured by Hitachi, Ltd.) Ultra-high resolution field emission scanning electron microscope: JSM-7800F Prime (manufactured by JEOL Ltd.) Backscattered electron diffraction equipment: Digiview V (manufactured by TSL)

[0072] The conditions for the EBSD measurement were as follows: Measurement area: 500.0 μm×400.0 μm Acceleration voltage: 20.0 kV Magnification: ×500 Vacuum degree: 30 Pa

[0073] In the obtained EBSD image, two or more alumina particles that were not in contact with the frame of the observation area were selected, and the average of the outer edge lengths L1 of each alumina particle was calculated using image processing software Image J (manufactured by the National Institute of Health). The "total grain boundary length L2" was the sum of the grain boundaries contained inside the alumina particle, excluding the outer edges of the alumina particle. The total grain boundary length L2 was calculated by adding the total length of the grain boundaries inside the alumina particle and the total length of the inner walls of the cavities (if any) inside the alumina particle.

[0074] The ratio of the total length L2 of the grain boundaries to the length L1 of the outer edge (L2 / L1) was expressed as a percentage (%). The more grain boundaries and voids there are inside the alumina particle, the larger the value of L2 / L1 (%).

[0075] [Uranium and Thorium Contents of Alumina Particles] The uranium content (U content) and thorium content (Th content) contained in the alumina particles were measured as follows. First, the alumina particles were placed in a mixed aqueous solution of sulfuric acid and phosphoric acid, and heated to dissolve the alumina particles, preparing an aqueous solution. Then, the aqueous solution was contacted with a cyclohexane solution of tributyl phosphate, which is commonly used as an extractant for uranium, to extract the uranium contained in the aqueous solution. Then, the uranium was transferred to the aqueous phase by back-extraction, where it was contacted again with pure water, and the intensities of U 238 amu and Th 232 amu were measured using ICP-MS. A standard solution manufactured by SPEX was used to create a calibration curve.

[0076] [α-ray dose emitted from alumina particles] The α-ray dose emitted from alumina particles 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%, CH ４ 10%) was used.

[0077] [Preparation of Resin Composition] Alumina particles, resin, etc. were kneaded to prepare resin compositions (Samples No. 1 to 5). The types of resin used are shown in Table 1, and the blending amounts of alumina particles are shown in Table 3. The resin compositions of Samples No. 1 to 5 were specifically prepared according to the following preparation method. The "resin composition" in Table 5 refers to the resin composition in a cured state.

[0078] (Samples No. 1 to 5) (1) Preparation of Varnish A 30% by mass mixed solution was prepared by dissolving the resin shown in Table 1 in the solvent shown in Table 1. Furthermore, 0.074% by mass of a curing agent (4,4-diaminodiphenylmethane (manufactured by TCI)) was added relative to 100% by mass of the mixed solution to prepare a varnish.

[0079] (2) Preparation of Alumina / Varnish Mixture Alumina particles were added to the obtained varnish and kneaded using a planetary centrifugal mixer (manufactured by Thinky Corporation) to prepare an alumina / varnish mixture.

[0080] (3) Film Formation The resulting alumina / varnish mixture was applied to a PET substrate and formed into a film using an applicator so that the film thickness after thermal curing would be 150 to 200 μm, thereby obtaining a resin composition before curing.

[0081] (4) Thermal Curing The obtained uncured resin composition was allowed to stand at room temperature for 1 hour, then heated at 140°C for 15 minutes, and further subjected to vacuum press molding at 140°C for 20 minutes at a pressure of 0.5 MPa using a press molding machine. After that, the resin composition was heated at 180°C for 120 minutes at normal pressure to be thermally cured. This resulted in cured resin compositions (Samples No. 1 to 5). In the resin compositions of Samples No. 1 to 5, the solid content of the entire resin composition was 95% by volume or more.

[0082]

[0083] Details of the types of resins listed in Table 1 are as follows:

[0084] Mesogenic epoxy resin (A) is a prepolymer obtained by reacting trans-4-{4-(2,3-epoxypropoxy)phenyl}cyclohexyl 4-(2,3-epoxypropoxy)benzoate (an epoxy resin represented by the structural formula below) with 6-hydroxy-2-naphthoic acid.

[0085]

[0086] Mixture of JP-100 and HP6000 This mixture was prepared by mixing JP-100 (manufactured by Nippon Soda), an epoxidized polybutadiene, and HP-6000 (manufactured by DIC), a naphthalene-based epoxy resin, in a mass ratio of 1:9.

[0087] [Charge Amount of Resin and Resin Composition] The charge amount of the resin and resin composition was measured using a static electricity meter under the following conditions. Statically meter: FMX-004 (manufactured by SIMCO) Measurement mode: Low MODE Temperature: 23°C, humidity: 40% The static electricity meter was placed at a height of 25 mm from the surface of a 10 cm square test piece, and the charge potential was measured. The obtained charge potential value is defined as the charge amount.

[0088] [α-ray Dose Emitted from Resin Composition] The α-ray dose emitted from the 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%, CH ４ 10%) was used.

[0089] [Rupture stress of resin composition, absorbed energy to break, and correlation coefficient of stress-strain curve to break] The rupture stress of the resin composition, absorbed energy to break, and correlation coefficient of the stress-strain curve to break were measured in accordance with JIS K7161 (2014). Specifically, a tensile test was performed under the following conditions, and the obtained stress-strain curve was analyzed and calculated. Testing equipment: Autograph AGS-X (manufactured by Shimadzu Corporation) Load cell: 1 kN Test piece dimensions: 100 mm x 10 mm Testing environment: 22°C / 59% RH Analysis software: TRAPEZIUMX

[0090] If the breaking stress of a resin composition is high, the strength of the resin composition when used as an encapsulating member can be improved, and the dimensional stability against external energy such as heat can also be improved. If the resin composition has a high absorption energy until rupture, the strength of the resin composition when used as an encapsulating member can be improved, and the dimensional stability against external energy such as heat can also be improved. If the correlation coefficient when the stress-strain curve of the resin composition until rupture is linearly approximated is high, it indicates that the resin composition stretches uniformly, and can mean, for example, that the inorganic particles are uniformly dispersed in the resin without agglomerating with each other.

[0091] The breaking stress of the resin composition was determined directly from the breaking point of the stress-strain curve. The absorbed energy of the resin composition up to break was calculated from the area enclosed by the stress-strain curve obtained in the tensile test. The correlation coefficient when the stress-strain curve of the resin composition up to break was linearly approximated was determined by analysis using analysis software. The maximum value of the correlation coefficient is 1.0000 (when the stress-strain curve from the start of the test to break is a straight line).

[0092] The results of various measurements of the alumina particles are shown in Tables 2 and 3, the types of resins used and the charge amounts of the resins are shown in Table 4, and the results of various measurements of the resin compositions are shown in Table 5.

[0093]

[0094]

[0095]

[0096]

[0097] The measurement results are discussed below. The resin compositions of Samples 1 to 4, which satisfy the requirements of the present embodiment, had a charge amount of 0.00 kV. On the other hand, the resin composition of Sample 5, which does not satisfy the requirements of the present embodiment, had a charge amount of -0.01, and it was not possible to achieve 0.00 kV.

[0098] Furthermore, the alumina particles used in the resin compositions of Samples 1 to 4 had a small absolute value of charge, which is thought to have resulted in good dispersion of the alumina particles in the resin. As a result, the resin compositions had a high breaking stress. The resin compositions also showed good results for the absorbed energy to break and the correlation coefficient of the stress-strain curve to break. On the other hand, the alumina particles used in the resin composition of Sample 5 had a large absolute value of charge, which is thought to have resulted in poor dispersibility of the alumina particles in the resin, resulting in a low breaking stress of the resin composition. The absorbed energy to break and the correlation coefficient of the stress-strain curve to break of the resin composition were lower than those of Samples 1 to 4.

[0099] The amount of α-ray radiation was low for the resin compositions of Samples No. 1 to 4, and high for the resin composition of Sample No. 5.

Claims

1. A resin composition comprising: alumina particles which generate more than 59.8 ppm of moisture when heated from 200°C to 900°C; and a resin.

2. The resin composition according to claim 1, wherein the alumina particles generate more than 43.0 ppm of moisture when heated from 200°C to 550°C.

3. The resin composition according to claim 1, wherein the alumina particles have an absolute charge of 0.17 kV or less.

4. Alpha radiation dose is 0.022 cph / cm ２ The resin composition according to claim 1 , wherein the molecular weight is less than 1.

0.

5. The resin composition according to claim 1, wherein the alumina particles have a ratio (L2 / L1) of the total length L2 of the internal grain boundaries to the length L1 of the outer edge of the particles being less than 139.1%.

6. A sheet molding compound comprising the resin composition according to any one of claims 1 to 5 and having a thickness of 1000 μm or less.

7. Alumina particles which generate more than 59.8 ppm of moisture when heated from 200°C to 900°C.

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