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

Abstract

Provided is a resin composition which contains alumina particles and a resin and which is capable of suppressing dimensional changes during repeated heating. The resin composition contains alumina particles having OH groups on the surface, and a resin, the ratio of the number of isolated OH groups to the number of hydrogen bond OH groups being less than 0.39.

Description

Technical Field

[0001] This disclosure relates to resin compositions and sheet molding compounds, as well as alumina particles used in resin compositions. Background Technology

[0002] Since the heat generated by the energization of electronic components can adversely affect their performance, rapid heat dissipation is desirable. Therefore, it is desirable for components, such as those constituting a semiconductor sealing component surrounding an IC chip, to exhibit high thermal conductivity for heat dissipation. This sealing component generally comprises alumina particles and resin, as described in Patent Document 1.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-200478 Summary of the Invention

[0006] In recent years, with the miniaturization of semiconductor devices and the reduction of wiring spacing, there are stringent requirements regarding the dimensional changes of sealing components due to heat. In particular, when semiconductor devices may repeatedly reach high temperatures due to power-on or other reasons, the significant dimensional changes of the sealing components under repeated heating are also a problem.

[0007] In the prior art as described in Patent Document 1, the study does not focus on suppressing dimensional changes during repeated heating.

[0008] In view of this situation, one embodiment of the present invention aims to provide a resin composition comprising alumina particles and resin, and capable of suppressing dimensional changes during repeated heating.

[0009] Another embodiment of the present invention aims to provide a sheet composition (sheet molding compound) composed of such a resin composition.

[0010] Another embodiment of the present invention aims to provide alumina particles for use in a resin composition.

[0011] Method 1 of the present invention is a resin composition comprising alumina particles and resin, wherein the alumina particles have OH groups on their surface, and the ratio of isolated OH groups to hydrogen-bonded OH groups is less than 0.39.

[0012] Method 2 of the present invention is the resin composition described in Method 1, wherein the number of isolated OH groups in the alumina particles is less than 3.1 per nm. 2 .

[0013] The third embodiment of the present invention is the resin composition described in embodiment 1 or 2, wherein the specific surface area of ​​the alumina particles is 0.20 m².2 / g or more.

[0014] The fourth embodiment of the present invention is the resin composition of any one of embodiments 1 to 3, wherein the ratio (L2 / L1) of the total length L2 of the internal grain boundaries of the alumina particles to the length L1 of the outer edge is less than 139.1%.

[0015] The fifth embodiment of the present invention is a sheet molding compound composed of any one of the resin compositions of embodiments 1 to 4, with a thickness of 1000 μm or less.

[0016] Method 6 of the present invention is an alumina particle in which the ratio of isolated OH groups to hydrogen-bonded OH groups is less than 0.39.

[0017] According to one embodiment of the present invention, a resin composition comprising alumina particles and resin can be provided, and dimensional changes during repeated heating can be suppressed.

[0018] According to another embodiment of the present invention, it is possible to provide a sheet molding compound composed of such a resin composition.

[0019] According to another embodiment of the present invention, it is possible to provide alumina particles for use in a resin composition. Detailed Implementation

[0020] The inventors conducted extensive research to develop a resin composition comprising alumina particles and resin that could suppress dimensional changes during repeated heating. As a result, they discovered that by including alumina particles with a ratio of isolated OH groups to hydrogen-bonded OH groups lower than a predetermined value, dimensional changes during repeated heating could be suppressed. This is believed to be because a smaller ratio of isolated OH groups to hydrogen-bonded OH groups reduces the binding force between alumina particles, suppressing particle aggregation and facilitating appropriate interactions between the alumina particles and the resin. Consequently, dimensional stability relative to external energies such as heat is also improved.

[0021] Hereinafter, the resin composition of this embodiment, the alumina particles used in the resin composition, and the sheet molding compound (SMC) formed by the resin composition will be described.

[0022] It should be noted that the term "resin composition" in this specification is intended to encompass all states of a resin composition, including its liquid state before the resin in the resin composition is cured, its semi-cured state (stage B) before the resin is partially cured, and its cured state (stage C) before the resin is fully cured. Here, "liquid state" also includes compositions in which the resin composition has a fluidity, such as resin compositions containing solvents described later. "Semi-cured state" refers to a state where, although cured to the point of being treatable in solid form, the surface of the resin composition remains tacky due to incomplete curing. "Cureable state" refers to a state where the resin composition is treated in solid form and its surface is almost non-tacky.

[0023] [Resin Composition]

[0024] The resin composition of this embodiment comprises alumina particles with an isolated OH group to a hydrogen-bonded OH group ratio of less than 0.39 and resin. This allows for the suppression of dimensional changes during repeated heating.

[0025] The alpha ray content of the resin composition is preferably less than 0.022 cph / cm. 2 This is because semiconductor devices are susceptible to the effects of alpha rays, and malfunctions (soft errors) caused by alpha rays can easily become problems. Furthermore, lower alpha ray levels cause less damage to semiconductor components, better maintain the adhesion between the resin composition and the component interface, and more easily suppress deformation caused by thermal processes. The preferred alpha ray level in the resin composition is 0.020 cph / cm². 2 The following is more preferably 0.015 cph / cm 2 The following is a further preferred value: 0.005 cph / cm 2 The following is particularly preferred: 0.002 cph / cm 2 The following is particularly important: the alpha radiation content of the cured resin composition is preferably less than 0.022 cph / cm. 2 0.020 cph / cm 2 Below, 0.015 cph / cm 2 Below, 0.005 cph / cm 2 Below or 0.002 cph / cm 2 The lower the alpha radiation content of the resin composition, the better; the preferred lower limit is 0.000 cph / cm. 2 It should be noted that the alpha radiation content of the resin composition is determined in both the semi-cured and cured states using an alpha radiation measuring device (e.g., the Alpha Sciens Model 1950). The measurement area of ​​the sample is set to 1000 cm². 2The measurement time was set to 99 hours, and PR-10 gas (Ar 90%, CH4 10%) was used for counting.

[0026] The elastic modulus (tensile elastic modulus) of the resin composition is preferably 2.0 GPa or higher. More preferably, it is 3.0 GPa or higher, even more preferably 4.0 GPa or higher, even more preferably 5.0 GPa or higher, particularly preferably 6.0 GPa or higher, and most preferably 7.0 GPa or higher. The above elastic modulus is measured in the resin composition in either a semi-cured or cured state. It is particularly preferred that the elastic modulus of the cured resin composition is 2.0 GPa or higher, enabling the formation of a sealing component that can withstand deformation under normal use conditions. The elastic modulus of the resin composition can be calculated from the stress-strain curve obtained from a tensile test according to JIS K 7161 (2014). The elastic modulus of the resin composition in both the semi-cured and cured states can be increased by adjusting the content of alumina particles and the curing conditions. Generally, the elastic modulus shows a higher value in the cured state compared to the semi-cured state.

[0027] The fracture stress of the resin composition is preferably greater than 41.2 MPa, more preferably 50.0 MPa or more, even more preferably 60.0 MPa or more, and particularly preferably 65.0 MPa or more. The fracture stress of the above-mentioned resin composition is measured in the semi-cured or cured state of the resin composition. In particular, the fracture stress of the cured resin composition is preferably greater than 41.2 MPa, 50.0 MPa or more, 60.0 MPa or more, or 65.0 MPa or more, in that order. This improves the strength when used to manufacture sealing components and also enhances dimensional stability relative to external energies such as heat. It should be noted that the fracture stress of the resin composition can be calculated from the stress-strain curve obtained from a tensile test according to JIS K7161 (2014). The fracture stress of the resin composition in the semi-cured and cured states can be increased by adjusting the alumina particle content and curing conditions. Generally, the fracture stress shows a higher value for the cured resin composition compared to the semi-cured state.

[0028] The proportion of alumina particles, relative to the total resin composition, is preferably 5-75% by volume of resin and 95-25% by volume of alumina particles, or 8-50% by volume of resin and 92-50% by volume of alumina particles, or 10-40% by volume of resin and 90-60% by volume of alumina particles, or 12-40% by volume of resin and 88-60% by volume of alumina particles. This allows for easy control of the fracture stress and absorbed energy until fracture of the resin composition to desired values. Furthermore, in both the semi-cured and cured states of the resin composition, the total proportion of resin and alumina particles relative to the total resin composition is preferably 60% by volume or more, more preferably 70% by volume or more, and even more preferably 80% by volume or more. Additionally, in both the semi-cured and cured states of the resin composition, the proportion of solid components relative to the total resin composition is preferably 80% by volume or more, more preferably 90% by volume or more, and even more preferably 95% by volume or more. The solid component of a resin composition refers to the component that remains in solid form when the resin composition is heated, such as the component obtained after removing components that evaporate through heating, such as the solvent mentioned above. On the other hand, even components that are liquid at 25°C are included in the solid component of the resin composition when heated. The proportion of solid components can be obtained, for example, by determining the amount of solvent in the resin composition and removing it from the whole. The amount of solvent in the resin composition can be determined, for example, by the following method: After measuring the mass W1 (g) of the resin composition, the sample is heated at 150°C for 10 minutes in a fully exhaust oven to evaporate all the solvent contained in the sample. After that, it 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).

[0029] The resin composition of the present invention exhibits minimal dimensional change and excellent dimensional stability upon repeated heating. In this invention, dimensional stability can be evaluated by calculating the CTE change rate using the following formula (1) after two CTE measurements. This CTE change rate is preferably less than 8.5, more preferably 8.4 or less, even more preferably 8.0 or less, even more preferably 7.0 or less, and particularly preferably 6.0 or less.

[0030] CTE change rate (%) = (CTE measured in the first measurement - CTE measured in the second measurement) / (CTE measured in the first measurement) × 100 (1)

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

[0032] [Alumina particles]

[0033] In this embodiment, the ratio of isolated OH groups to hydrogen-bonded OH groups in the alumina particles is less than 0.39. Therefore, in the resin composition, the aggregation of alumina particles is suppressed, and appropriate interactions between the alumina particles and the resin are readily achieved. This ratio is more preferably 0.35 or less, and even more preferably 0.30 or less. There is no particular limitation on the lower limit of this ratio; for example, it can be 0.01 or more. From the viewpoint of facilitating interactions between the particles and the resin, this ratio is preferably 0.03 or more, and even more preferably 0.05 or more. It should be noted that alumina particles can acquire OH groups on their surface through reactions with moisture in the atmosphere, etc.

[0034] In this embodiment, the alumina particles preferably have less than 3.1 isolated OH radicals per nm. 2 Therefore, in the resin composition, particle aggregation can be further suppressed, resulting in improved dimensional stability and fracture stress relative to external energies such as heat. The number of isolated OH radicals is more preferably 2.8 per nm. 2 The number of isolated OH radicals is further preferably 2.5 per nm. 2 The preferred isolated OH radical number is 2.0 per nm. 2 The number of isolated OH radicals is particularly preferred to be less than 1.5 per nm. 2 On the other hand, the preferred number of isolated OH radicals is 0.1 per nm. 2 The above. Therefore, it is easier to achieve appropriate interactions between particles and resin. The number of isolated OH groups is more preferably 0.2 per nm. 2 The above is further preferably 0.3 per nm. 2 above.

[0035] In this embodiment, the quantitative determination of the number of isolated OH radicals and hydrogen-bonded OH radicals in alumina particles can be performed using the Karl Fischer method (moisture vaporization-titration method) as described in JISK 0068:2001 "Method for determination of moisture content in chemical products". Moisture detected in the Karl Fischer determination can be considered as a source of OH radicals in alumina particles; moisture detected at 550°C can be considered as a source of hydrogen-bonded OH radicals; and moisture detected at 900°C can be considered as a source of isolated OH radicals.

[0036] It should be noted that the water detected in the Karl Fischer assay is considered to be the condensation of two OH groups into one water molecule, and the number of OH groups can be determined by the following equation (2).

[0037] OH radicals [number / nm] 2 = 0.0662 × (moisture content [ppm]) / (specific surface area of ​​alumina particles [m²]) 2 / g]) (2)

[0038] When quantifying the number of isolated OH groups and hydrogen-bonded OH groups of alumina particles in a resin composition, firstly, the resin contained in the resin composition is removed by dissolving it in, for example, an organic solvent, and only the alumina particles are separated. The isolated alumina particles can then be used to quantify the number of isolated OH groups and hydrogen-bonded OH groups in the same manner as described above.

[0039] The specific surface area of ​​the alumina particles in this embodiment is preferably 0.20 m². 2 / g or more. This facilitates appropriate interactions between particles and resin. A more preferred specific surface area is greater than 0.36 m². 2 / g, with a specific surface area further preferably 0.40m². 2 / g or more, with a more preferably specific surface area of ​​0.45m². 2 / g or more, with a particularly preferred specific surface area of ​​0.55m². 2 / g or more. Typically, the specific surface area is 3.00m². 2 / g or less, preferably 2.50m 2 / g or less. It should be noted that in this embodiment, the specific surface area of ​​the alumina particles is the nitrogen adsorption BET specific surface area, measured according to JIS-Z8830 (2013). It should be noted that when alumina particles are contained in a resin composition, the resin contained in the resin composition can be dissolved in, for example, an organic solvent, and removed by thermal decomposition at a temperature of 500°C or higher, separating only the alumina particles, and using these alumina particles to measure the specific surface area.

[0040] By reducing the content of grain boundaries within alumina particles, the shielding effect against alpha rays generated by uranium and thorium within the alumina particles can be improved, thereby reducing the amount of alpha rays emitted by the alumina particles.

[0041] 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 used as an indicator of the content of grain boundaries inside the alumina particles. L1 and L2 are determined by observing the cross-section of the alumina particles.

[0042] When the length of the outer edge of a single alumina particle is defined as L1, and the total length of the grain boundaries of that alumina particle is defined as L2, alumina particles with a small L2 / L1 ratio can be considered to have a low grain boundary content and a low amount of emitted alpha rays. Particularly preferred is a (L2 / L1) ratio of less than 139.1%, thereby further reducing the amount of emitted alpha rays when used as a filler in resin compositions. By reducing the amount of alpha rays emitted by the alumina particles, the amount of alpha rays emitted by the resin composition containing alumina particles can also be reduced.

[0043] The (L2 / L1) content is preferably 120.0% or less, more preferably 100.0% or less, further 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 and can be 10.0% or more, for example, 20.0% or more, 30.0% or more, 40.0% or more, or 43.0% or more. If the lower limit of L2 / L1 is within the above range, it is easier for the particle-resin interaction to occur, and it is easier to improve the mechanical strength of the resin composition, such as the fracture stress.

[0044] The L2 / L1 values ​​become particularly large when alumina particles are manufactured using granulated or polycrystalline raw material particles via flame melting, and even subsequent processes such as reheating cannot significantly reduce them.

[0045] It should be noted that the "total length of grain boundaries L2" refers to the sum of all grain boundaries contained within the alumina particle, excluding the outer edge of the alumina particle. The total length of grain boundaries L2 is the value obtained by adding the total length of grain boundaries L3 within the alumina particle to the total length of the inner wall of the cavity (in the case of a cavity within the alumina particle) L4 (i.e., L2 = L3 + L4).

[0046] It should be noted that when alumina particles are contained in a resin composition, the resin contained in the resin composition can be dissolved in, for example, an organic solvent, or heated to a temperature of 500°C or higher to thermally decompose the resin and remove it, thus separating only the alumina particles, which can then be used to determine L2 / L1.

[0047] Alumina particles with a sharp particle size distribution are preferred because they readily exhibit appropriate interactions between the particles and the resin. For example, the ratio D90 / D50, which is the cumulative particle size distribution of 90% of the particles (hereinafter sometimes abbreviated as "D90"), to the cumulative particle size distribution of 50% of the particles (hereinafter sometimes abbreviated as "D50"), 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.

[0048] On the other hand, when the particle size distribution of alumina particles has a certain width, it can improve the filling capacity by allowing small particles to enter the gaps between large particles, thus enabling more alumina particles to be mixed into the resin. This can improve the dimensional stability and fracture stress relative to 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.

[0049] 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 keeping the D50 within the above range, a resin composition suitable for miniaturization of semiconductor devices and reduction of wiring spacing can be formed.

[0050] It should be noted that in this embodiment, the D90 and D50 of the alumina particles can be determined, for example, by using the "Microtrac MT3300EXII" manufactured by MicrotracBEL Co., Ltd. as a laser particle size distribution measuring device to determine the particle size distribution of the alumina particles by laser diffraction.

[0051] It should be noted that the particle size of alumina particles in the resin composition can be determined by dissolving the resin contained in the resin composition with, for example, an organic solvent, or by thermally decomposing the resin at a temperature of 500°C or higher, thereby removing only the alumina particles and using those alumina particles.

[0052] Another method for determining the D90 and D50 of alumina particles is image analysis. The resin composition can be cross-sectionally observed using SEM, and image analysis can be performed on all alumina particles contained within a specified observation area (e.g., 200 μm × 200 μm). Based on the measured particle size (equivalent circle diameter), the particle size corresponding to D90 and D50 can be calculated.

[0053] In this embodiment, the alumina particles 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 content of the alumina particles to extremely low levels as described above, the amount of alpha rays emitted by the alumina particles can be reduced, thereby suppressing the amount of alpha rays emitted by the resin composition. Therefore, when used as a sealing material for semiconductor devices, malfunctions of the semiconductor device caused by alpha rays can be suppressed. Furthermore, the alumina particles preferably contain alpha alumina particles. Alpha alumina is expected to reduce the amount of alpha rays emitted by the alumina particles; by having alpha alumina particles in the alumina particles, the suppression effect on the amount of alpha rays emitted by the resin composition can be improved.

[0054] The uranium content is preferably below 300 ppb, more preferably below 100 ppb, even more preferably below 50 ppb, and particularly preferably below 30 ppb, for example below 10 ppb or 5 ppb. The lower limit of the uranium content is not particularly limited and can be above 0.1 ppb.

[0055] The thorium content is preferably 8 ppb or less, more preferably 5 ppb or less, and particularly preferably 2 ppb or less. There is no particular limitation on the lower limit of the thorium content, which can be 0.1 ppb or more.

[0056] Uranium and thorium contents can be determined using inductively coupled plasma mass spectrometry (ICP-MS).

[0057] It should be noted that when alumina particles are contained in a resin composition, the resin contained in the resin composition can be dissolved with, for example, an organic solvent, or heated to a temperature of 500°C or higher to thermally decompose the resin and remove it, thus separating only the alumina particles. The alumina particles can then be used to determine the uranium and thorium content.

[0058] [Method for manufacturing alumina particles]

[0059] The alumina particles of this embodiment can be manufactured, for example, by the method described below.

[0060] (Raw material: alumina)

[0061] Alumina can be produced using well-known methods. Examples include the Bayer process, ammonium alum process, basic aluminum ammonium carbonate process (AACH process), solvent extraction process, organoaluminum hydrolysis process (aluminum alkoxide process), CZ process, Varnoy flame fusion process, bubble growth process, Bridgman process, EFG process, and other melt growth methods.

[0062] In the case of the Bayer process, aluminum hydroxide obtained from bauxite can be calcined to produce raw alumina. Furthermore, high-purity raw alumina with low uranium and thorium content can be produced using the ammonium alum process, AACH process, solvent extraction process, and aluminum alkoxide process, which are therefore preferred. If raw alumina with uranium content suppressed to, for example, less than 550 ppb and thorium content suppressed to, for example, less than 10 ppb, produced using these methods is used to produce alumina particles, alumina particles with suppressed uranium and thorium content can be obtained, which is also preferred.

[0063] (Pulverization of raw material alumina)

[0064] To easily obtain alumina particles of the desired size for flame melting, raw alumina is pulverized to obtain alumina raw material powder for flame melting. The pulverization of raw alumina can be carried out using known methods such as vibratory mills, bead mills, ball mills, and jet mills, and can be performed in either dry or wet conditions.

[0065] In the above-mentioned pulverization process, surface protectants can be used. Surface protectants not only protect the surface of the pulverized alumina raw material powder but also have the function of deactivating the surface of the alumina raw material powder. Because surface protectants reduce the agglomeration of alumina raw material powder by utilizing their surface deactivation function, they are suitable for using easily agglomerated alumina raw material with a high BET specific surface area to obtain alumina particles of the target particle size after flame melting. Suitable surface protectants include, for example, monohydric alcohols such as methanol, ethanol, 1-propanol, and 2-propanol; diols 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. These surface protectants can be used alone or in combination of two or more. Among them, diols are preferred, and one or more of ethylene glycol, polyethylene glycol, propylene glycol, and polypropylene glycol are particularly preferred.

[0066] For example, polyethylene glycol and polypropylene glycol, which are preferred as surface protectants, there is no particular limitation on their molecular weight. From the perspective of ease of addition, liquid glycols with an average molecular weight of about 200 to 600 are preferred.

[0067] Regarding the amount of surface protectant added, when the raw material alumina is set to 100 parts by weight, in order to fully exert the effect of the surface protectant, it is preferable to add 0.01 parts by weight or more. In addition, even if the amount of surface protectant added is too large, the effect of the surface protectant will be saturated, so it is preferable to add 10 parts by weight or less. The amount of surface protectant added is more preferably 0.05 to 8 parts by weight, and even more preferably 0.1 to 5 parts by weight.

[0068] (Flame melting)

[0069] Flame melting is a method in which raw alumina is sprayed into a flame and then cooled and solidified after dropletization. According to flame melting, alumina particles can be obtained while maintaining a relatively consistent particle size. In flame melting, the temperature of the flame melting furnace is preferably 1000°C or higher. In particular, by setting the raw material supply rate to 50 kg / h or less, preferably 10 kg / h or less, the thermal energy applied to the alumina particles can be controlled within a specified range, thus easily obtaining alumina particles that meet the aforementioned requirements.

[0070] After the flame melts, alumina particles can be captured using a cyclone separator and / or a bag filter, and then classified to obtain alumina particles with the desired properties.

[0071] The number of isolated OH radicals and hydrogen-bonded OH radicals in alumina particles can be controlled by the manufacturing method, pulverization method, and flame melting conditions of the raw alumina, or by immersing the obtained alumina particles in an acidic solution such as hydrochloric acid. For ease of concentration adjustment, hydrochloric acid is preferred as the acidic solution for immersion. The concentration of the acidic solution is preferably adjusted to 1M to 12M, more preferably to 1M to 10M, and particularly preferably to 2M to 5M. The mass ratio of alumina particles to acidic solution during immersion is preferably 1:2 to 1:10. The immersion time is preferably 5 hours or more. Heating can be applied appropriately during immersion in a manner that shortens the immersion time, for example, heating to 50 to 90°C. After immersion, washing and drying are preferred.

[0072] [Resin]

[0073] The resin used in the resin composition preferably includes one or more selected from epoxy resins and thermoplastic polyimides, and more preferably includes epoxy resins. Examples of preferred epoxy resins include mesocrystalline epoxy resins, phenylcyclohexyl epoxy resins, naphthalene-based epoxy resins, phenolic epoxy resins, biphenyl epoxy resins, butadiene-based epoxy resins, and bisphenol A epoxy resins. Mesocrystalline epoxy resins are epoxy resins having mesocrystalline groups, and resins that exhibit a phase transition temperature and liquid crystal properties within a sealed temperature range of 100°C to 200°C are preferred. It should be noted that the resin included in the resin composition may include one or more epoxy resins. That is, the resin included in the resin composition may include one or more epoxy resins selected from mesocrystalline epoxy resins, phenylcyclohexyl epoxy resins, naphthalene-based epoxy resins, phenolic epoxy resins, biphenyl epoxy resins, butadiene-based epoxy resins, and bisphenol A epoxy resins, and may further include thermoplastic polyimides. These resins are expected to have the effect of shielding alpha rays emitted by alumina particles. Furthermore, by using these resins, resin compositions with high dimensional stability relative to external energies such as heat can be readily obtained.

[0074] Furthermore, these resin compositions may, as needed and without impairing the effects of the invention, appropriately incorporate one or more of the known additives such as plasticizers, curing agents, curing accelerators, coupling agents, fillers, pigments, flame retardants, antioxidants, surfactants, compatibilizers, weathering agents, anti-blocking agents, antistatic agents, leveling agents, and release agents. Additionally, as an embodiment of this application, the resin composition (particularly liquid or semi-cured resin compositions) may contain a solvent. When the resin composition contains a solvent, it flows easily, can easily deform to conform to the fine structure of the IC chip and substrate, and can seal the dense structure without gaps. As the solvent, known solvents can be used; there are no limitations as long as the solvent can dissolve the aforementioned resin. Examples include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, amine-based solvents, amide-based solvents, halogen-based solvents, hydrocarbon-based solvents, and nitrile-based solvents. From the viewpoint of being a good solvent for epoxy resins and resulting in resin compositions with excellent coatability, ketone-based and ester-based solvents are preferred.

[0075] In a preferred embodiment of the present invention, the resin composition comprises alumina particles, epoxy resin, solvent, and curing agent. Examples of curing agents include amine-based curing agents such as 4,4-diaminodiphenylmethane.

[0076] [Method for manufacturing the resin composition]

[0077] The method for manufacturing the resin composition is described.

[0078] A resin composition can be obtained by mixing the alumina particles of this embodiment with a resin using a generally known method. For example, when the resin is liquid (e.g., liquid epoxy resin), the resin composition can be obtained by mixing the liquid resin, alumina particles, and a curing agent, and then curing it using heat or ultraviolet light. Known curing agents and methods can be used as the curing agent, mixing method, and curing method. On the other hand, when the resin is solid (e.g., epoxy resin, polyolefin resin, or acrylic resin), the target resin composition can be obtained by mixing the alumina particles with the resin and then compounding it using a known method such as melt compounding, or by dissolving and mixing the resin, alumina particles, and curing agent in a solvent. The resin composition may contain a solvent.

[0079] The resin composition of this embodiment includes all states of the resin composition, including a liquid state before the resin in the resin composition is cured, a semi-cured state (stage B) where the resin is partially cured, and a cured state (stage C) where the resin is fully cured.

[0080] The liquid resin composition comprises a complex of alumina powder and resin in a specified ratio, a mixture of the complex, and a molded article obtained by molding the mixture.

[0081] A semi-cured resin composition comprises a resin composition obtained by semi-curing a resin contained in a mixture or molded article.

[0082] The cured resin composition comprises a grease composition obtained by completely curing the resin contained in a mixture, molded article, or semi-cured article.

[0083] [Sheet molding compound (SMC)]

[0084] The resin compositions described in the embodiments can be used to provide sheet molding compounds (SMCs). SMCs are resin compositions molded into sheets. SMCs preferably have flowability when heated and pressurized, but can also be in a semi-cured state.

[0085] The thickness of SMC is preferably below 1000 μm, which enables the miniaturization of the semiconductor device when assembled into it. The thickness is lightweight, and it also improves the sealing performance when sealing the IC chip. More preferably, the thickness is 800 μm or less, further preferably 600 μm, even more preferably 500 μm or less, particularly preferably 400 μm or less, and particularly more preferably 300 μm or less. The lower limit of the thickness is not particularly limited; from the viewpoint of the commonly used SMC dimensions and improving the sealing performance of the IC chip, it can be, for example, 10 μm or more, 50 μm or more, and further, 100 μm or more, or 150 μm or more.

[0086] SMC can be manufactured using known methods. As an example, it is obtained by coating an uncured resin composition onto a substrate and then depositing a protective film thereon to partially cure the resin composition. Alternatively, as another example, it is obtained by coating an uncured resin composition containing a solvent onto a substrate, removing the solvent from the resin composition using drying or the like, and then depositing a protective film. In the use of SMC, the protective film is peeled off, it is pressed onto a wafer or the like, the substrate is removed, and post-curing is performed.

[0087] The resin composition and SMC of this embodiment are suitable as sealing components for semiconductor devices because they can suppress dimensional changes during repeated heating.

[0088] Example

[0089] [Preparation of alumina particles]

[0090] The alumina particles (A-D) used in the resin compositions of samples No. 1-6 were prepared as follows.

[0091] (Alumina particles A and B used in samples No. 1 to 4)

[0092] Prepare alumina particles A (used in samples No. 2 and 4) and alumina particles B (used in samples No. 1 and 3) as described below.

[0093] The alumina used as raw material was γ-alumina obtained by the ammonium alum method (the average particle size of the primary particles, calculated based on the BET specific surface area value below, was 13 nm). The BET specific surface area of ​​this γ-alumina, based on the nitrogen adsorption method, was 120 m². 2 / g. Before pulverization, 4% by mass of propylene glycol is added to the raw alumina as a surface protectant and mixed.

[0094] Next, the material was processed using a jet mill (a horizontal jet mill PJM-280SP manufactured by Nippon Pneumatic Industries, Ltd.) at a feed rate of 30 kg / h for the raw alumina and a gauge pressure of 0.5 MPa at the air supply port during grinding, to obtain alumina raw material powder with an average particle size of about 2 μm for the secondary particles.

[0095] The obtained alumina raw material powder was fed into a flame melting furnace to melt it and obtain spherical alumina particles. The atmosphere temperature in the flame melting furnace was set to 1250℃, and the raw material feed rate was set to 5 kg / h. The obtained alumina particles were recovered using a cyclone separator and classified using the cyclone separator to remove particles larger than 20 μm, obtaining alumina particles A (D50 = 5.1 μm, used in samples No. 2 and 4). Furthermore, particles larger than 10 μm were removed to obtain alumina particles B (D50 = 2.3 μm, used in samples No. 1 and 3).

[0096] (Alumina particles C used in sample No. 5)

[0097] Sample No. 5 used alumina particles C prepared according to the following steps.

[0098] Alumina raw material particles composed of single-crystal alumina with a D50 of 3.5 μm were prepared and fed into a flame melting furnace at a feed rate of less than 50 kg / h to melt and obtain spherical alumina particles. The obtained alumina particles were then classified using a cyclone separator to remove particles larger than 20 μm, yielding alumina particles C.

[0099] (Alumina particles D used in sample No. 6)

[0100] Sample No. 6 used alumina particles (alumina particles D) made by Denka DAW05.

[0101] The following determinations were made on the alumina particles used in each sample.

[0102] [Number of isolated OH groups and hydrogen-bonded OH groups in alumina particles]

[0103] The quantitative determination of the number of isolated OH radicals and hydrogen-bonded OH radicals in alumina particles is based on the Karl Fischer method (moisture vaporization-titration method) described in JIS K 0068:2001 "Methods for Determination of Moisture in Chemical Products". Moisture detected in the Karl Fischer determination is considered to be from the OH radical source of alumina particles; moisture detected at 550°C is considered from the hydrogen-bonded OH radical source; and moisture detected at 900°C is considered from the isolated OH radical source.

[0104] It should be noted that the water detected in the Karl Fischer determination is considered to be the condensation of two OH groups into one water molecule, and the number of OH groups is determined according to the following formula (2).

[0105] OH radicals [number / nm] 2 = 0.0662 × (moisture content [ppm]) / (specific surface area of ​​alumina particles [m²]) 2 / g]) (2)

[0106] [Particle size distribution of alumina particles]

[0107] For the D50 and D90 of alumina particles, a Microtrac MT3300EXII laser particle size distribution measuring device (manufactured by MicrotracBEL Co., Ltd.) was used as the laser particle size distribution measuring device, and the particle size distribution of alumina particles was determined by laser diffraction. Based on the particle size distribution measurement results, D50 and D90 were calculated. As the sample for measurement, an alumina particle dispersion was prepared by adding alumina particles to a 0.2% (w / w) sodium hexametaphosphate aqueous solution at an appropriate laser scattering intensity and dispersing the particles using the device's built-in ultrasonic wave at 40W for 5 minutes. The refractive index of alumina is 1.76.

[0108] [BET specific surface area of ​​alumina particles]

[0109] The specific surface area was determined using the Shimadzu Flowsorb III 2310 as the specific surface area measuring device, following the method specified in JIS-Z8830 (2013), by using the single-point method of nitrogen adsorption. The measurement conditions are as follows.

[0110] Carrier gas: nitrogen / helium mixture

[0111] Sample weight: 0.1g

[0112] Sample pretreatment conditions: Treat at 200℃ for 20 minutes

[0113] Nitrogen adsorption temperature: Liquid nitrogen temperature (below -196℃)

[0114] Nitrogen desorption temperature: room temperature (approximately 20°C)

[0115] [Determination of the combined length L1 of the outer edge of the alumina particle and L2 of the grain boundary within the particle]

[0116] Alumina particles from samples No. 1 to 6 were used to prepare cross-sectional observation specimens. In the preparation of these specimens, alumina particles were embedded in cross-sectional observation resin, and then the resin and alumina particles were cut using a diamond cutter. Pt was then deposited onto the cross-section as a protective film, and the cross-section was prepared using Ar ion polishing. The specimens were then fixed to the SEM stage using Cu double-sided adhesive, and SEM-EBSD measurements were performed without evaporation. The observation position was determined by ensuring that two or more alumina particles were completely within the observation area (i.e., without contacting the frame of the observation area). All alumina particles measured were α-alumina particles.

[0117] The following instruments were used for sample pretreatment and EBSD determination.

[0118] Using instruments

[0119] Ion milling device: IM-4000 (manufactured by Hitachi, Ltd.)

[0120] Ion sputtering equipment: E-1030 (manufactured by Hitachi, Ltd.)

[0121] Ultra-high resolution field emission scanning electron microscope: JSM-7800F Prime (manufactured by Nippon Electron Ltd.)

[0122] Backscattered electron diffraction apparatus: Digiview V (TSL fabrication)

[0123] The conditions for EBSD determination are as follows.

[0124] Measurement area: 500.0 μm × 400.0 μm

[0125] Accelerating voltage: 20.0kV

[0126] Magnification:×500

[0127] Vacuum degree: 30Pa

[0128] In the obtained EBSD image, two or more alumina particles that do not contact the observation area are selected, and the average length L1 of the outer edge of each alumina particle is calculated using ImageJ (made by the National Institute of Health). The "total grain boundary length L2" is the sum of the grain boundaries contained within the alumina particle, excluding the outer edge of the alumina particle. The total grain boundary length L2 is obtained by adding the total length of the grain boundaries within the alumina particle to the total length of the inner wall of the cavity (in the case of a cavity within the alumina particle).

[0129] The ratio of the total length L2 of grain boundaries to the length L1 of the outer edge (L2 / L1) is expressed as a percentage (%). The more grain boundaries and voids inside the alumina particle, the larger the value of L2 / L1 (%).

[0130] [Uranium and thorium content of alumina particles]

[0131] The uranium (U) and thorium (Th) content in alumina particles was determined as follows. First, alumina particles were dissolved in a mixed aqueous solution of sulfuric acid and phosphoric acid by heating. This aqueous solution was then contacted with a cyclohexane solution of tributyl phosphate, a commonly used uranium extractant, to extract the uranium. The uranium transferred to the aqueous phase by back-extraction with pure water was then determined by ICP-MS based on the intensities of U238amu and Th232amu. It should be noted that standard solutions manufactured by SPEX were used to prepare the standard curve.

[0132] [Amount of alpha rays emitted by alumina particles]

[0133] The amount of alpha rays emitted by alumina particles was measured using a Model 1950 measuring apparatus (manufactured by Alpha Sciens). The measurement area of ​​the sample was set to 1000 cm². 2 The measurement time was set to 99 hours, and PR-10 gas (Ar 90%, CH4 10%) was used for counting.

[0134] [Preparation of the resin composition]

[0135] Alumina particles, resin, and other materials were mixed to prepare resin compositions (samples No. 1 to 6). The types of resins used are listed in Table 1, and the amount of alumina particles is listed in Table 3. In addition, the elastic modulus of the resin when cured without alumina particles was measured and recorded in the "Elastic Modulus" column of "Resin" in Table 3.

[0136] The resin compositions for samples No. 1 to 6 were prepared according to the following method. The term "resin composition" in Table 3 refers to the resin composition in its cured state.

[0137] (1) Preparation of varnish

[0138] Dissolve the resins shown in Table 1 in the solvents shown in Table 1 to prepare a 30% by mass mixed solution. Then, add 0.074% by mass of a curing agent (4,4-diaminodiphenylmethane (TCI)) relative to 100% by mass of the mixed solution to prepare a varnish.

[0139] (2) Preparation of alumina / varnish mixture

[0140] Alumina particles were added to the obtained varnish, and the mixture was kneaded using a rotary mixer (Thinky Corporation) to prepare an alumina / varnish mixture.

[0141] (3) Film making

[0142] The obtained alumina / varnish mixture was coated onto a PET substrate, and a film was formed using a coating tool to achieve a film thickness of 150-200 μm after heat curing, thus obtaining the resin composition before curing.

[0143] (4) Thermosetting

[0144] The obtained resin composition before curing was left to stand at room temperature for 1 hour, then heated at 140°C for 15 minutes. Following this, it was vacuum-pressed at 140°C for 20 minutes using a pressure molding machine at 0.5 MPa, and then heat-cured at 180°C for 120 minutes under normal pressure. This yielded the cured resin compositions (samples No. 1-6). In the resin compositions of samples No. 1-5, the proportion of solid components relative to the total resin composition was 95% by volume or more.

[0145]

[0146] The details of the types of resins listed in Table 1 are as follows.

[0147] Mesocrystalline epoxy resin (A)

[0148] A prepolymer obtained by reacting trans-4-{4-(2,3-epoxypropoxy)phenyl}cyclohexyl=4-(2,3-epoxypropoxy)benzoate (an epoxy resin represented by the following structural formula) with 6-hydroxy-2-naphthoic acid.

[0149]

[0150] A mixture of JP-100 and HP6000

[0151] It is made by mixing JP-100 of epoxidized polybutadiene (manufactured by Nippon Soda) and HP-6000 of naphthalene-based epoxy resin (manufactured by DIC) at a mass ratio of 1:9.

[0152] [Elastic modulus and breaking stress of the resin composition]

[0153] The elastic modulus and stress at break of the resin composition were determined according to JIS K7161 (2014). Specifically, the stress-strain curves obtained from tensile tests performed under the following conditions were analyzed and calculated.

[0154] Experimental apparatus; Autograph AGS-X (manufactured by Shimadzu Corporation)

[0155] Load sensor: 1kN

[0156] Test piece size: 100mm × 10mm

[0157] Test environment: 22℃ / 59%RH

[0158] Analysis software: TRAPEZIUMX

[0159] [Amount of alpha rays emitted by the resin composition]

[0160] The amount of alpha rays emitted by the resin composition was determined using a Model 1950 measuring apparatus (manufactured by Alpha Sciens). The measurement area of ​​the sample was set to 1000 cm². 2 The measurement time was set to 99 hours, and PR-10 gas (Ar 90%, CH4 10%) was used for counting.

[0161] [Dimensional changes of the resin composition during repeated heating]

[0162] The dimensional changes of the resin composition under repeated heating were evaluated as follows.

[0163] First, the coefficient of thermal expansion (CTE) over the temperature range of 27°C to 150°C was determined using thermomechanical analysis according to JIS K7197. The analytical conditions are shown below.

[0164] Device: TMA7100 (Hitachi High Technology Manufacturing)

[0165] Measurement mode: Tensile mode

[0166] Test piece width: 5mm

[0167] Chuck spacing: 20mm

[0168] Temperature rise and fall process: heat from 20°C to 200°C at a rate of 5°C / min, then cool from 200°C to 20°C at a rate of 5°C / min.

[0169] CTE calculation temperature range: 27℃~150℃ during the heating step.

[0170] Measurement load: 0.05N

[0171] The sample with the smaller CTE change rate calculated according to the following formula is evaluated as the sample with smaller dimensional change during repeated heating.

[0172] CTE change rate (%) = (CTE measured in the first measurement - CTE measured in the second measurement) / (CTE measured in the first measurement) × 100

[0173] Table 2 shows the various test results for alumina particles, and Table 3 shows the various test results for the types of resins used (and their elastic modulus) and resin compositions. It should be noted that “-” in the tables indicates that a test was performed.

[0174]

[0175]

[0176] The measurement results are analyzed below.

[0177] The resin compositions of samples No. 1 to 5, which meet the requirements of this embodiment, are able to sufficiently suppress dimensional changes during repeated heating (even if the CTE change rate is 8.4% or less). On the other hand, the resin composition of sample No. 6, which does not meet the requirements of this embodiment, has a CTE change rate of 8.5% and cannot sufficiently suppress dimensional changes during repeated heating.

Claims

1. A resin composition comprising alumina particles and a resin, wherein the alumina particles have OH groups on their surface, and the ratio of isolated OH groups to hydrogen-bonded OH groups is less than 0.

39.

2. The resin composition according to claim 1, wherein, The number of isolated OH radicals in the alumina particles is less than 3.1 per nm. 2 .

3. The resin composition according to claim 1, wherein, The specific surface area of ​​the alumina particles is 0.20 m². 2 / g or more.

4. The resin composition according to claim 1, wherein, The ratio of the total length L2 of the internal grain boundaries of the alumina particles to the length L1 of the outer edge, L2 / L1, is less than 139.1%.

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

6. An alumina particle having a ratio of isolated OH groups to hydrogen-bonded OH groups of less than 0.39.

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