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

Abstract

Provided is a resin composition that contains alumina particles and a resin, the resin composition being capable of suppressing dimensional change that could occur when repeatedly heated. The resin composition contains: alumina particles having OH groups on the surface thereof, where the ratio of isolated OH groups to hydrogen-bonded OH groups is less than 0.39; 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 a material constituting a semiconductor encapsulation member surrounding an IC chip to exhibit high thermal conductivity for heat dissipation. Such an encapsulation member may generally contain alumina particles and resin, as described in Patent Document 1.

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

[0004] In recent years, with the miniaturization of semiconductor devices and the narrowing of wiring pitches, stricter requirements have been placed on the encapsulating material with respect to dimensional change due to heat. In particular, semiconductor devices can be repeatedly exposed to high temperatures due to current flow, and it has become a problem that the dimensions of the encapsulating material change significantly when repeatedly heated. In the prior art such as that described in Patent Document 1, suppression of dimensional change when repeatedly heated has not been considered.

[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 is capable of suppressing dimensional change when repeatedly heated. 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 having OH groups on the surface thereof, the ratio of the number of isolated OH groups to the number of hydrogen-bonded OH groups being less than 0.39; and a resin.

[0007] In a second aspect of the present invention, the alumina particles have a number of isolated OH groups of 3.1 / nm ２The resin composition according to aspect 1, wherein the tensile strength is less than 1000 ppm.

[0008] In a third aspect of the present invention, the alumina particles have a specific surface area of ​​0.20 m ２ / g or more.

[0009] A fourth aspect of the present invention is the resin composition according to any one of the first to third aspects, wherein the alumina particles have a ratio (L2 / L1) of a total length L2 of the internal grain boundaries to a length L1 of the outer edge of the alumina particles is less than 139.1%.

[0010] A fifth aspect of the present invention is a sheet molding compound comprising the resin composition according to any one of the first to fourth aspects and having a thickness of 1000 μm or less.

[0011] A sixth aspect of the present invention is an alumina particle having a ratio of the number of isolated OH groups to the number of hydrogen-bonded OH groups of less than 0.39.

[0012] According to one embodiment of the present invention, there is provided a resin composition containing alumina particles and a resin, the resin composition being capable of suppressing dimensional change when repeatedly heated. According to another embodiment of the present invention, there is provided a sheet molding compound comprising such a resin composition. According to yet another embodiment of the present invention, there is provided alumina particles used in the resin composition.

[0013] The present inventors conducted extensive research to realize a resin composition containing alumina particles and a resin that can suppress dimensional change when repeatedly heated. As a result, they found that by including alumina particles in which the ratio of the number of isolated OH groups to the number of hydrogen-bonded OH groups is less than a predetermined value, dimensional change when repeatedly heated can be suppressed. This is thought to be because the smaller the ratio of the number of isolated OH groups to the number of hydrogen-bonded OH groups, the weaker the bonding strength between the alumina particles, suppressing aggregation between the alumina particles and facilitating appropriate interactions between the alumina particles and the resin, resulting in improved dimensional stability against external energy such as heat.

[0014] The resin composition according to this embodiment, the alumina particles used in the resin composition, and the sheet molding compound (SMC) comprising the resin composition are described below. In this specification, the term "resin composition" is intended to include all states of the resin composition, including the liquid state before the resin in the resin composition is cured, the semi-cured state (B stage) in which the resin is semi-cured, and the cured state (C stage) in which the resin is completely cured. The "liquid state" here also includes compositions in which the resin composition has fluidity, such as resin compositions containing solvents, as described below. The "semi-cured state" 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. The "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.

[0015] [Resin Composition] The resin composition according to this embodiment contains alumina particles having a ratio of the number of isolated OH groups to the number of hydrogen-bonded OH groups of less than 0.39 and a resin, which can suppress dimensional changes when repeatedly heated.

[0016] The alpha dose of the resin composition is 0.022 cph / cm ２ It 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. Furthermore, a low α dose reduces damage to semiconductor elements, makes it easier to maintain adhesion at the interface between the resin composition and the elements, and makes it easier to suppress deformation due to thermal history. 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 / cm２ 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.

[0017] The resin composition preferably has a modulus of elasticity (tensile modulus) of 2.0 GPa or more. The modulus of elasticity of the resin composition is more preferably 3.0 GPa or more, even more preferably 4.0 GPa or more, even more preferably 5.0 GPa or more, particularly preferably 6.0 GPa or more, and most preferably 7.0 GPa or more. The modulus of elasticity is measured for a resin composition in a semi-cured or cured state. In particular, the modulus of elasticity of the cured resin composition is preferably 2.0 GPa or more, allowing for the formation of a sealing member that can withstand deformation under typical usage conditions. The modulus of elasticity of the resin composition can be calculated from a stress-strain curve obtained in a tensile test in accordance with JIS K7161 (2014). The modulus of elasticity of the resin composition in the semi-cured and cured states can be increased by adjusting the content of alumina particles and the curing conditions. Typically, the modulus of elasticity of a resin composition in the cured state is higher than that of a resin composition in the semi-cured state.

[0018] The rupture stress of the resin composition 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. The rupture stress of the resin composition is measured in a semi-cured or cured state. It is particularly preferable that the rupture stress of the cured resin composition be greater than 41.2 MPa, greater than 50.0 MPa, greater than 60.0 MPa, or greater than 65.0 MPa, in this 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 semi-cured and cured resin compositions can be increased by adjusting the alumina particle content and curing conditions. Typically, the rupture stress of a cured resin composition is higher than that of a semi-cured resin composition.

[0019] The preferred blend ratio of alumina particles relative to the total resin composition is 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. This makes it easier to control the breaking stress and absorbed energy to break of the resin composition to desired values. Furthermore, in the 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 the semi-cured and cured resin compositions, the solids content 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).

[0020] The resin composition of the present invention exhibits little dimensional change when repeatedly heated and has excellent dimensional stability. In the present invention, the dimensional stability can be evaluated by measuring the CTE twice and then calculating the CTE change rate from the following formula (1). The CTE change rate is preferably less than 8.5, more preferably 8.4 or less, even more preferably 8.0 or less, still more preferably 7.0 or less, and particularly preferably 6.0 or less. CTE change rate (%) = (CTE at first measurement - CTE at second measurement) / (CTE at first measurement) × 100 (1)

[0021] Next, the alumina particles and resin that constitute the resin composition will be described in detail.

[0022] [Alumina Particles] The alumina particles according to this embodiment have a ratio of the number of isolated OH groups to the number of hydrogen-bonded OH groups of less than 0.39. This suppresses aggregation of the alumina particles in the resin composition, and facilitates appropriate interaction between the alumina particles and the resin. This ratio is more preferably 0.35 or less, and even more preferably 0.30 or less. The lower limit of this ratio is not particularly limited, but may be, for example, 0.01 or more. From the viewpoint of facilitating particle-resin interaction, this ratio is preferably 0.03 or more, and even more preferably 0.05 or more. The alumina particles may have OH groups on their surfaces due to, for example, reaction with moisture in the air.

[0023] The alumina particles according to this embodiment have an isolated OH group count of 3.1 / nm ２ This makes it possible to further suppress aggregation of particles in the resin composition, thereby improving dimensional stability and breaking stress against external energy such as heat. ２ More preferably, the number of isolated OH groups is 2.5 / nm or less. ２ It is more preferable that the number of isolated OH groups is 2.0 / nm or less. ２ It is more preferable that the number of isolated OH groups is 1.5 / nm or less. ２ On the other hand, it is particularly preferable that the number of isolated OH groups is less than 0.1 / nm ２ This makes it easier for an appropriate interaction to occur between the particles and the resin. The number of isolated OH groups is 0.2 / nm ２ More preferably, it is 0.3 particles / nm or more. ２ More preferably, it is equal to or greater than this.

[0024] In this embodiment, the number of isolated OH groups and the number of hydrogen-bonded OH groups of the alumina particles can be quantified using the measurement results of the Karl Fischer method (moisture vaporization-titration method) in accordance with the description of JIS K 0068:2001 "Method for measuring moisture content in chemical products." The moisture detected in the Karl Fischer measurement can be considered to be derived from the OH groups of the alumina particles, and moisture detected at a temperature of 550°C can be considered to be derived from hydrogen-bonded OH groups, while moisture detected at a temperature of 900°C can be considered to be derived from isolated OH groups. Note that the moisture detected in the Karl Fischer measurement is considered to be derived from two OH groups condensing to form one water molecule, and the number of OH groups can be calculated using the following formula (2): Number of OH groups [number / nm ２ ] = 0.0662 × (water content [ppm]) / (specific surface area of ​​alumina particles [m ２ / g])...(2)

[0025] When quantifying the number of isolated OH groups and the number of hydrogen-bonded OH groups 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. Using the separated alumina particles, the number of isolated OH groups and the number of hydrogen-bonded OH groups can be quantified in the same manner as above.

[0026] The alumina particles according to this embodiment have a specific surface area of ​​0.20 m ２ / g or more. This facilitates appropriate interaction between the particles and the resin. The specific surface area is 0.36 m ２ / g, and the specific surface area is more preferably 0.40 m ２ / g or more, and the specific surface area is more preferably 0.45 m ２ / g or more, and the specific surface area is 0.55 m ２ / g or more. Usually, the specific surface area is 3.00 m ２ / g or less, preferably 2.50m ２ / g or less. In this embodiment, the specific surface area of ​​the alumina particles is a nitrogen adsorption BET specific surface area, and is measured in accordance with JIS-Z8830 (2013). When the alumina particles are contained in a resin composition, the resin contained in the resin composition can be removed by, for example, dissolving it in an organic solvent or by heating it to a temperature of 500°C or higher to thermally decompose the resin, and only the alumina particles can be isolated, and the specific surface area can be measured using the alumina particles.

[0027] By reducing the grain boundary content within the alumina particles, the shielding effect against alpha rays generated from uranium and thorium within the alumina particles can be improved, and the amount of alpha rays emitted from the alumina particles can be reduced. In this embodiment, the ratio of the total length L2 of the grain boundaries to the length L1 of the outer edge (L2 / L1) is introduced as an index of the grain boundary content within the alumina particles. L1 and L2 are determined by observing the cross section of the alumina particles.

[0028] 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 L2 / L1 value have a low grain boundary content 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 the alumina particles are 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.

[0029] (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, making it easier to increase the mechanical strength, such as the breaking stress, of the resin composition. This L2 / L1 value becomes particularly large when alumina particles are produced by a flame fusion method using granulated raw material particles or polycrystalline raw material particles, and cannot be significantly reduced even by performing a post-process such as reheating.

[0030] 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 the alumina particle has cavities inside) (i.e., L2 = L3 + L4). When the alumina particles are contained in a resin composition, the resin contained in the resin composition can be removed by, for example, dissolving it in an organic solvent or heating it to a temperature of 500°C or higher to pyrolyze the resin, and only the alumina particles can be isolated, and L2 / L1 can be measured using the alumina particles.

[0031] Alumina particles with a sharp particle size distribution are preferred because they facilitate appropriate particle-resin interactions. For example, the ratio D90 / D50, the particle diameter D90 (hereinafter sometimes simply referred to as "D90") at the cumulative 90% of the number of particles counted from the finest particle side of the cumulative particle size distribution to the particle diameter D50 (hereinafter sometimes simply referred to as "D50") at the cumulative 50% of the number of particles counted from the finest particle side of the cumulative particle size distribution, is preferably 5.0 or less. D90 / D50 is more preferably 4.0 or less, even more preferably 3.0 or less, and particularly preferably 1.5 or less.

[0032] On the other hand, if the particle size distribution of the alumina particles is broad to some extent, the filling property is improved by allowing small particles to enter the gaps between large particles, and more alumina particles can be kneaded into the resin, which can improve 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.

[0033] The D50 of the alumina particles 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 a D50 within the above range, a resin composition suitable for miniaturizing semiconductor devices and narrowing the wiring pitch can be formed.

[0034] In this embodiment, the D90 and D50 of the alumina particles can be determined by measuring the particle size distribution of the alumina particles by laser diffraction using, for example, a laser particle size distribution measuring device such as a Microtrac MT3300EXII manufactured by Microtrac Bell Co., Ltd. The particle size of the alumina particles in the resin composition can be measured by removing the resin contained in the resin composition by, for example, dissolving it in an organic solvent or by heating it to a temperature of 500°C or higher to pyrolyze the resin, isolating only the alumina particles, and using the alumina particles.

[0035] Another method for determining the D90 and D50 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 to measure their particle diameters (circle-equivalent diameters), and the particle diameters equivalent to D90 and D50 may be calculated based on the measurement results.

[0036] The alumina particles according to this embodiment preferably have a uranium content of less than 550 ppb and a thorium content of less than 10 ppb. By suppressing the uranium and thorium contents 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. Furthermore, 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 ultimately improve the effect of suppressing the amount of α-rays emitted from the resin composition.

[0037] 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). When alumina particles are contained in the resin composition, the resin contained in the resin composition can be removed, for example, by dissolving it in an organic solvent or by heating it to a temperature of 500°C or higher to pyrolyze the resin, and only the alumina particles can be isolated, and the uranium content and thorium content can be measured using the alumina particles.

[0038] [Method for Producing Alumina Particles] The alumina particles according to this embodiment can be produced, for example, by the method described below.

[0039] (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.

[0040] 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 by mass, respectively, can be used to produce alumina particles, which are preferred because they allow for the production of alumina particles with low uranium and thorium contents.

[0041] (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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] (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 particular, in the flame fusion method, by setting the raw material supply rate to 50 kg / h or less, preferably 10 kg / h or less, the amount of thermal energy applied to the alumina particles can be controlled within a predetermined range, making it easier to obtain alumina particles that satisfy the above-mentioned predetermined requirements.

[0046] After the flame fusion, the alumina particles are collected by a cyclone and / or a bag filter and classified to obtain alumina particles having desired properties.

[0047] The number of isolated OH groups and the number of hydrogen-bonded OH groups of the alumina particles can be controlled by the conditions of the manufacturing method of the raw alumina, the pulverization method, and the flame fusion method, but 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 is preferably alumina particles to acidic solution of 1:2 to 1:10. The immersion time is preferably 5 hours or more. During immersion, heating may be performed as appropriate to shorten the immersion time, for example, heating to 50 to 90°C. After immersion, washing and drying are preferably performed.

[0048] [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 blocking alpha rays that may be emitted from alumina particles, and by using these resins, it becomes easier to obtain a resin composition that has high dimensional stability against external energy such as heat.

[0049] 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 can be used as long as they can dissolve the resin, but examples include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, amine-based solvents, amide-based solvents, halogen-based solvents, hydrocarbon-based solvents, and nitrile-based solvents. Ketone-based solvents and ester-based solvents are preferred because they are good solvents for epoxy resins and provide excellent coatability for the resulting resin composition.

[0050] 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.

[0051] [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.

[0052] 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.

[0053] [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.

[0054] 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.

[0055] The resin composition and SMC according to this embodiment can suppress dimensional changes when repeatedly heated, and are therefore suitable as sealing members for semiconductor elements.

[0056] [Preparation of Alumina Particles] The alumina particles (A to D) used in the resin compositions of Samples No. 1 to 6 were prepared as follows.

[0057] (Alumina particles A and B used in samples Nos. 1 to 4) Alumina particles A (used in samples Nos. 2 and 4) and alumina particles B (used in samples Nos. 1 and 3) described below were prepared.

[0058] 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.

[0059] 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.

[0060] The resulting alumina raw material powder was charged into a flame fusion furnace and melted to obtain spherical alumina particles. The ambient temperature in the flame fusion furnace was set to 1250°C, and the raw material feed rate was set to 5 kg / h. The resulting alumina particles were collected in a cyclone and classified by cyclone classification to remove particles 20 μm or larger, obtaining alumina particles A (D50 = 5.1 μm, used for samples 2 and 4). Furthermore, particles 10 μm or larger were removed to obtain alumina particles B (D50 = 2.3 μm, used for samples 1 and 3).

[0061] (Alumina Particles C Used in Sample No. 5) Sample No. 5 used alumina particles C prepared by the following procedure. Alumina raw material particles made of single-crystal alumina having a D50 of 3.5 μm were prepared, and the raw material feed rate was set to 50 kg / h or less. The raw material was charged into a flame melting furnace and melted to obtain spheroidized alumina particles. The obtained alumina particles were subjected to a classification process using a cyclone classifier to remove particles of 20 μm or larger, thereby obtaining alumina particles C.

[0062] (Alumina particles D used in sample No. 6) For sample No. 6, alumina particles (alumina particles D) manufactured by Denka DAW05 were used.

[0063] The alumina particles used in each sample were subjected to the following measurements.

[0064] [Number of Isolated OH Groups and Number of Hydrogen-Bonded OH Groups on Alumina Particles] The number of isolated OH groups and the number of hydrogen-bonded OH groups on alumina particles were determined using the measurement results of the Karl Fischer method (moisture vaporization-titration method) in accordance with JIS K 0068:2001 "Method for measuring moisture content in chemical products." The moisture detected in the Karl Fischer measurement was considered to be derived from the OH groups on the alumina particles, with the moisture detected at a temperature of 550°C being derived from hydrogen-bonded OH groups and the moisture detected at a temperature of 900°C being derived from isolated OH groups. Note that the moisture detected in the Karl Fischer measurement is considered to be derived from two OH groups condensing to form one water molecule, and the number of OH groups was calculated using the following formula (2): Number of OH groups [number / nm ２ ] = 0.0662 × (water content [ppm]) / (specific surface area of ​​alumina particles [m ２ / g])...(2)

[0065] [Particle size distribution of alumina particles] The particle size distribution of alumina particles, D50 and D90, was measured by laser diffraction using a laser particle size distribution measuring device, "Microtrac MT3300EXII" 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 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 of 40 W. The refractive index of alumina was 1.76.

[0066] [BET Specific Surface Area of ​​Alumina Particles] A Shimadzu Flowsorb III 2310 specific surface area measuring device was used, and the nitrogen adsorption BET specific surface area was determined by the single-point nitrogen adsorption method in accordance with the method specified in JIS-Z8830 (2013). The measurement conditions were as follows: Carrier gas: nitrogen / helium mixed gas; Sample amount: 0.1 g; Sample pretreatment conditions: 20 minutes at 200°C; Nitrogen adsorption temperature: liquid nitrogen temperature (-196°C or lower); Nitrogen desorption temperature: room temperature (approximately 20°C).

[0067] [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 6. To prepare the cross-sectional observation samples, the alumina particles were embedded in a resin for cross-sectional observation, and then the resin and the 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.

[0068] 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)

[0069] 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

[0070] 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.

[0071] 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 (%).

[0072] [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.

[0073] [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.

[0074] [Preparation of Resin Composition] Alumina particles, resin, etc. were kneaded to prepare resin compositions (Samples No. 1 to 6). The types of resin used are shown in Table 1, and the amounts of alumina particles added are shown in Table 3. The elastic modulus of the resin not containing alumina particles when cured was measured, and this is shown in the "Elastic Modulus" column of "Resin" in Table 3. Specifically, the resin compositions of Samples No. 1 to 6 were prepared according to the following preparation method. The "Resin Composition" in Table 3 refers to the resin composition in a cured state.

[0075] (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, a curing agent (4,4-diaminodiphenylmethane (manufactured by TCI)) was added in an amount of 0.074% by mass relative to 100% by mass of the mixed solution to prepare a varnish.

[0076] (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.

[0077] (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.

[0078] (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 then vacuum press molded at 140°C for 20 minutes at a pressure of 0.5 MPa using a press molding machine. The composition was then heated at 180°C for 120 minutes at normal pressure to thermally cure. This resulted in cured resin compositions (Samples No. 1 to 6). The resin compositions of Samples No. 1 to 5 had a solids content of 95% or more by volume relative to the total resin composition.

[0079]

[0080] Details of the types of resins listed in Table 1 are as follows:

[0081] 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.

[0082]

[0083] 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.

[0084] [Elastic modulus and breaking stress of resin composition] The elastic modulus and breaking stress of the resin composition 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

[0085] [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.

[0086] [Dimensional Change of Resin Composition When Repeatedly Heated] The dimensional change of the resin composition when repeatedly heated was evaluated as follows. First, the coefficient of thermal expansion (CTE) in the temperature range of 27°C to 150°C was determined by thermomechanical analysis in accordance with JIS K7197. The analysis conditions are as follows: Apparatus: TMA7100 (manufactured by Hitachi High-Tech Science) Measurement mode: Tensile mode Test piece width: 5 mm Chuck distance: 20 mm Temperature increase / decrease process: The temperature was increased from 20°C to 200°C at a rate of 5°C / min, and then cooled from 200°C to 20°C at a rate of 5°C / min. CTE calculation temperature range: 27°C to 150°C during the temperature increase process Measurement load: 0.05 N The above CTE measurement was performed twice, and the smaller the CTE change rate calculated from the following formula, the smaller the dimensional change when repeatedly heated. CTE change rate (%)=(CTE at first measurement−CTE at second measurement) / (CTE at first measurement)×100

[0087] The results of various measurements of the alumina particles are shown in Table 2, and the types of resins used (and their elastic moduli) and the results of various measurements of the resin compositions are shown in Table 3. In the table, "-" indicates that no measurement was performed.

[0088]

[0089]

[0090] The measurement results are discussed below. The resin compositions of Samples 1 to 5, which satisfied the requirements of this embodiment, were able to sufficiently suppress dimensional change when repeatedly heated (i.e., the CTE change rate was 8.4% or less). On the other hand, the resin composition of Sample 6, which did not satisfy the requirements of this embodiment, had a CTE change rate of 8.5%, and was unable to sufficiently suppress dimensional change when repeatedly heated.

Claims

1. A resin composition comprising: alumina particles having OH groups on their surfaces and a ratio of the number of isolated OH groups to the number of hydrogen-bonded OH groups of less than 0.39; and a resin.

2. The resin composition according to claim 1, wherein the alumina particles have a number of isolated OH groups of less than 3.1 / nm2.

3. The resin composition according to claim 1, wherein the alumina particles have a specific surface area of ​​0.20 m2 / g or more.

4. 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 alumina particles is less than 139.1%.

5. A sheet molding compound comprising the resin composition according to any one of claims 1 to 4 and having a thickness of 1000 μm or less.

6. Alumina particles having a ratio of the number of isolated OH groups to the number of hydrogen-bonded OH groups of less than 0.39.

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