Resin composition for molding and electronic device

Abstract

The present disclosure provides a resin composition for molding, said resin composition easily increasing the thermal conductivity of a cured product thereof and suppressing thermal expansion, while preventing the cured product from having an extremely high elastic modulus, and said resin composition being insusceptible to deterioration of moldability. This resin composition for molding contains a reaction curable resin (A) and an inorganic filler (B). The inorganic filler (B) contains spherical boron nitride (b1). The inorganic filler (B) does not contain flake boron nitride (b2), or alternatively, the inorganic filler (B) contains flake boron nitride (b2) and the ratio of the flake boron nitride (b2) in the inorganic filler (B) relative to the resin composition for molding is more than 0% by mass but less than 3% by mass.

Description

Technical Field

[0001] The present disclosure relates to a resin composition for molding and an electronic device. More specifically, it relates to a resin composition for molding containing a reaction-curable resin and an inorganic filler, and an electronic device provided with a sealing material made from this resin composition for molding.

Background Art

[0002] As a resin composition for molding for encapsulating electronic components such as semiconductor elements, Patent Document 1 discloses an epoxy resin composition for encapsulation characterized in that an epoxy resin, a curing agent, a curing aid, and an inorganic filler are essential components, the inorganic filler is contained in the range of 75 to 95% by mass of the entire resin composition, and the inorganic filler contains 60 Vol% or more of alumina, 99.9 Vol% or more of particles having a particle size of 32 μm or less, 5 Vol% or more of particles having a particle size of 0.5 μm or less, and has a particle size distribution with an average particle size in the range of 1 to 10 μm.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] An object of the present disclosure is to provide a resin composition for molding that easily increases the thermal conductivity of the cured product, is less likely to have an excessively high elastic modulus of the cured product, can lower the thermal expansion coefficient of the cured product, and is less likely to deteriorate in moldability, and an electronic device provided with a sealing material made from this resin composition for molding.

[0005] The resin composition for molding according to one aspect of the present disclosure contains a reaction-curable resin (A) and an inorganic filler (B). The inorganic filler (B) contains spherical boron nitride (b1). The inorganic filler (B) does not contain flaky boron nitride (b2), or the inorganic filler (B) contains flaky boron nitride (b2) and the proportion of the flaky boron nitride (b2) in the inorganic filler (B) is more than 0% by mass and less than 3% by mass with respect to the resin composition for molding.

[0006] An electronic device according to one aspect of the present disclosure includes a base material, an electronic component mounted on the base material, and a sealing material that seals the electronic component. The sealing material is a cured product of the resin composition for molding.

Brief Description of Drawings

[0007]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0008] According to the inventor's investigation, when the resin composition for molding contains alumina as disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2014-31460), since alumina has good thermal conductivity, the thermal conductivity and heat dissipation of the sealing material produced from the resin composition for molding are likely to increase.

[0009] However, when the proportion of alumina in the resin composition for molding is increased to enhance the thermal conductivity, the sealing material becomes excessively hard, resulting in deterioration of processability or warping of the sealing material.

[0010] Therefore, the inventor conducted research and development to provide a resin composition for molding that can easily enhance the thermal conductivity of the cured product, is less likely to have an excessively high elastic modulus of the cured product, can lower the thermal expansion coefficient of the cured product, and is less likely to deteriorate the moldability, and thus completed the present disclosure.

[0011] Hereinafter, an embodiment of the present disclosure will be described.

[0012] The resin composition for molding according to this embodiment (hereinafter, also referred to as composition (X)) contains a reaction-curable resin (A) and an inorganic filler (B). The inorganic filler (B) contains spherical boron nitride (b1). The inorganic filler (B) does not contain flaky boron nitride (b2), or the inorganic filler (B) contains flaky boron nitride (b2) and the proportion of flaky boron nitride (b2) in the inorganic filler (B) is more than 0% by mass and less than 3% by mass with respect to the composition (X).

[0013] According to this embodiment, when the composition (X) is caused to flow and molded, since the spherical boron nitride (b1) hardly inhibits the flow of the composition (X), it hardly deteriorates the moldability of the composition (X). Further, since the spherical boron nitride (b1) has high thermal conductivity as compared with alumina or the like, it is easy to increase the thermal conductivity and heat dissipation of the cured product of the composition (X). Furthermore, since the spherical boron nitride (b1) has a lower hardness than alumina or the like, it is difficult to increase the elastic modulus of the cured product.

[0014] Therefore, according to this embodiment, it is easy to increase the thermal conductivity of the cured product of the composition (X), the elastic modulus of the cured product hardly becomes excessively high, and the moldability of the composition (X) hardly deteriorates.

[0015] The components of the composition (X) will be further described.

[0016] The reaction-curable resin (A) contains at least one of, for example, a thermosetting resin (A1) and a photocurable resin (A2).

[0017] The curable component (A) preferably contains a thermosetting resin (A1). In this case, the composition (X) can have thermosetting properties.

[0018] The thermosetting resin (A1) can contain at least one thermosetting resin selected from the group consisting of, for example, an epoxy resin (a), a maleimide resin, a phenol resin, a thermosetting polyphenylene ether oligomer, and a cyanate resin. Depending on the use of the composition (X) and the like, the thermosetting resin (A1) can contain various resins. When producing the encapsulant 4 from the composition (X), the thermosetting resin (A1) preferably contains, in particular, the epoxy resin (a).

[0019] The thermosetting polyphenylene ether oligomer has a structure in which the ends of the molecular chains of the polyphenylene ether oligomer are modified to bond a functional group having an ethylenic double bond. The structure of the thermosetting polyphenylene ether oligomer is known and is synthesized, for example, by reacting a polyphenylene ether oligomer having phenolic hydroxyl groups at both ends with vinylbenzyl chloride to vinylbenzyl etherify the phenolic hydroxyl groups.

[0020] The epoxy resin (a) preferably has two or more epoxy groups in one molecule. The epoxy resin (a) can contain various resins such as, for example, glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, olefin oxidation type (alicyclic) epoxy resins, etc. More specifically, the epoxy resin is, for example, bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin; hydrogenated bisphenol type epoxy resins such as hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin; biphenyl type epoxy resins; naphthalene ring-containing epoxy resins; alicyclic epoxy resins; dicyclopentadiene type epoxy resins; phenol novolac type epoxy resins; cresol novolac type epoxy resins; triphenylmethane type epoxy resins; aliphatic epoxy resins; triglycidyl isocyanurate; and at least one selected from the group consisting of glycidyl group-containing silicone resins. In particular, the epoxy resin preferably contains at least one selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, naphthalene ring-containing epoxy resin and alicyclic epoxy resin.

[0021] The epoxy resin (a) may be solid or liquid at 25°C. When the composition (X) is liquid at 25°C, the epoxy resin (a) is preferably liquid at 25°C.

[0022] When the epoxy resin (a) is liquid at 25°C, the viscosity at 25°C is preferably 0.1 Pa·s or more and 150 Pa·s or less, more preferably 0.1 Pa·s or more and 100 Pa·s or less. In this specification, the viscosity is the value measured at 25°C with an HB type rotational viscometer (rotation speed 50 rpm). When the epoxy resin (a) is liquid, if the epoxy resin (a) is a mixture of a plurality of components, as long as the epoxy resin (a) is liquid as a whole, components that are solid at normal temperature may be contained in the epoxy resin (a) alone.

[0023] Note that the components contained in the epoxy resin (a) are not limited to the above.

[0024] In particular, the epoxy resin (a) preferably contains an epoxy resin (a1) having a mesogenic skeleton. That is, the reaction-curable resin (A) preferably contains an epoxy resin (a1) having a mesogenic skeleton. In this case, the composition (X) is likely to have good fluidity, and thus the composition (X) is likely to have high moldability. The mesogenic skeleton refers to a molecular structure capable of expressing crystallinity.

[0025] The mesogenic skeleton in the epoxy resin (a1) includes at least one skeleton selected from the group consisting of, for example, a phenyl benzoate skeleton, a biphenyl skeleton, a benzophenone skeleton, a phenyl ether skeleton, a benzanilide skeleton, a stilbene skeleton, a diazobenzene skeleton, and a benzylidene aniline skeleton, and skeletons of derivatives in which substituents are bonded to these skeletons. In this case, the fluidity of the composition (X) is particularly likely to increase.

[0026] The benzoic acid phenyl skeleton has a structure in which any two hydrogens are removed from the structure shown in the following formula (I) or a structure in which a substituent is bonded to this structure. The biphenyl skeleton has a structure in which any two hydrogens are removed from the structure shown in the following formula (II) or a structure in which a substituent is bonded to this structure. The benzophenone skeleton has a structure in which any two hydrogens are removed from the structure shown in the following formula (III) or a structure in which a substituent is bonded to this structure. The phenyl ether skeleton has a structure in which any two hydrogens are removed from the structure shown in the following formula (IV) or a structure in which a substituent is bonded to this structure. The benzanilide skeleton has a structure in which any two hydrogens are removed from the structure shown in the following formula (V) or a structure in which a substituent is bonded to this structure. The stilbene skeleton has a structure in which any two hydrogens are removed from the structure shown in the following formula (VI) or a structure in which a substituent is bonded to this structure. The diazobenzene skeleton has a structure in which any two hydrogens are removed from the structure shown in the following formula (VII) or a structure in which a substituent is bonded to this structure. The benzylidene aniline skeleton has a structure in which any two hydrogens are removed from the structure shown in the following formula (VIII) or a structure in which a substituent is bonded to this structure. It is more preferable that no substituent is bonded to these skeletons.

[0027]

Chemical formula

[0028] The epoxy resin (a1) having a mesogenic skeleton contains at least one selected from the group consisting of, for example, biphenyl type epoxy resins, stilbene type epoxy resins, modified epoxy resins synthesized by reacting a mixture of hydroquinone and 4,4'-dihydroxybiphenyl with epichlorohydrin, and phenyl benzoate type epoxy resins.

[0029] The epoxy resin (a1) having a mesogenic skeleton preferably contains a modified epoxy resin (a11) synthesized by reacting a mixture of hydroquinone and 4,4'-dihydroxybiphenyl with epichlorohydrin.

[0030] The epoxy resin (a1) having a mesogen skeleton preferably contains an epoxy resin (a12) synthesized by the following method. First, a compound represented by formula (1) and a compound represented by formula (2) are reacted to obtain a phenol compound. This phenol compound is reacted with epihalohydrin in the presence of an alkali metal hydroxide. After melting the crystal components in the product by heating the product thus obtained to 150 °C or higher, it is rapidly cooled to 50 °C or lower. Thereby, an epoxy resin (a12) is obtained.

[0031]

Chemical formula

[0032] In formula (1), each of the plurality of R1 is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a hydroxyl group, a nitro group, or a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms. l represents the number of R1 and is an integer from 0 to 4.

[0033]

Chemical formula

[0034] In formula (2), R2 (when there are a plurality of R2 in one molecule, each of the plurality of R2) is a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, a hydroxyl group, a nitro group, a formyl group, an allyl group, or a substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms. k represents the number of R2 and is an integer from 0 to 4.

[0035] The proportion of the epoxy resin (a1) with respect to the entire epoxy resin (a) is preferably 50% by mass or more and 100% by mass or less. This proportion is more preferably 70% by mass or more and 100% by mass or less, and even more preferably 80% by mass or more and 100% by mass or less.

[0036] When the composition (X) contains an epoxy resin, the composition (X) preferably contains a curing agent. The curing agent contains at least one selected from the group consisting of, for example, acid anhydrides, amines, imidazoles, phenols, hydrazides, polymercaptans, and Lewis acid-amine complexes.

[0037] The acid anhydrides contain at least one selected from the group consisting of, for example, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, methylhimic anhydride, pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, 3,4-dimethyl-6-(2-methyl-1-propenyl)-1,2,3,6-tetrahydrophthalic anhydride, and 1-isopropyl-4-methyl-bicyclo[2.2.2]oct-5-ene-2,3-dicarboxylic anhydride.

[0038] The amines contain, for example, a compound having at least one primary or secondary amino group in the molecule. The amines preferably contain aromatic amines. The aromatic amines contain at least one selected from the group consisting of, for example, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiphenylsulfide, metaxylenediamine, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetraethyl-4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfide, 2,2-bis-[4-(4-aminophenoxy)phenyl]-hexafluoropropane, 2,2-bis(4-aminophenyl)-hexafluoropropane, 2,4-diaminotoluene, 1,4-diaminobenzene, 1,3-diaminobenzene, diethyltoluenediamine, dimethyltoluenediamine, anilines, alkylated anilines, and N-alkylated anilines.

[0039] The imidazoles contain at least one selected from the group consisting of, for example, 2MZ, C11Z, 2PZ, 2E4MZ, 2P4MZ, 1B2MZ, 1B2PZ, 2MZ-CN, 2E4MZ-CN, 2PZ-CN, C11Z-CN, 2PZ-CNS, C11Z-CNS, 2MZ-A, C11Z-A, 2E4MZ-A, 2P4MHZ, 2PHZ, 2MA-OK, 2PZ-OK (product names manufactured by Shikoku Chemicals Corporation), and compounds obtained by adding these imidazoles to an epoxy resin. The imidazoles may be microencapsulated.

[0040] The phenols contain at least one selected from the group consisting of, for example, bisphenol resins, phenol novolak resins, naphthol novolak resins, allylated phenol novolak resins, biphenol resins, cresol novolak resins, phenol aralkyl resins, cresol naphthol formaldehyde polycondensates, triphenylmethane type polyfunctional phenol resins, xylylene-modified phenol novolak resins, xylylene-modified naphthol novolak resins, and various polyfunctional phenol resins.

[0041] Note that the components contained in the curing agent are not limited to the above.

[0042] The stoichiometric equivalent ratio of the curing agent to the epoxy resin (curing agent equivalent / epoxy group equivalent) is preferably 0.6 or more and 1.4 or less. In this case, an appropriate blending amount of the curing agent with respect to the epoxy resin can be achieved, and it is possible to less likely cause undercuring, a decrease in the heat resistance of the cured product, a decrease in the strength of the cured product, an increase in the moisture absorption amount of the cured product, etc.

[0043] When the composition (X) contains an epoxy resin, the composition (X) may contain a curing accelerator. The curing accelerator includes, for example, imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole; cycloamidines such as 1,8-diazabicyclo[5.4.0]undecene-7, 1,5-diazabicyclo[4.3.0]nonene-5, 5,6-dibutylamino-1,8-diazabicyclo[5.4.0]undecene-7; tertiary amines such as 2-(dimethylaminomethyl)phenol, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, tris(dimethylaminomethyl)phenol; organic phosphines such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, tris(4-methylphenyl)phosphine, diphenylphosphine, phenylphosphine; tetra-substituted phosphonium tetra-substituted borates such as tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium ethyltriphenylborate, tetrabutylphosphonium tetrabutylborate; and tetraphenylboron salts such as 2-ethyl-4-methylimidazole tetraphenylborate, N-methylmorpholine tetraphenylborate, and contains at least one selected from the group consisting of.

[0044] The proportion of the curing accelerator is, for example, 0.05% by mass or more and 5% by mass or less based on the total amount of the epoxy resin and the curing agent.

[0045] On the other hand, when the reaction-curable resin (A) contains a photocurable resin (A2), the composition (X) may have photocurability. The photocurable resin (A2) contains at least one compound selected from the group consisting of, for example, monofunctional (meth)acrylates such as 2-(meth)acryloyloxyethyl phthalate and polyfunctional (meth)acrylates such as pentaerythritol tri(meth)acrylate. Note that “(meth)acryl-” means at least one of “acryl-” and “methacryl-”, and for example, (meth)acrylate means one or both of acrylate and methacrylate.

[0046] The inorganic filler (B) contains spherical boron nitride (b1) as described above. That the shape of the spherical boron nitride (b1) is spherical is determined from common general knowledge in the art.

[0047] In particular, it is preferable that the circularity of the spherical boron nitride (b1) is 0.8 or more. In this case, the spherical boron nitride (b1) is particularly unlikely to inhibit the fluidity of the composition (X).

[0048] The circularity of the spherical boron nitride (b1) is defined as follows.

[0049] By photographing the particles of spherical boron nitride (b1) with an electron microscope such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM) at a magnification of 10,000 to 100,000 times, an image with a resolution of 1280×1024 pixels is obtained, and this image is subjected to image analysis in a manual recognition mode using image analysis software (for example, MacView, a product name manufactured by Mountech Co., Ltd.) to measure the projected area (S) and the perimeter (L) of the particles. From this result, the circularity of the particles is calculated by the following formula. (Circularity) = 4πS / L 2 For 100 arbitrarily selected particles of the spherical boron nitride (b1) having a particle diameter of 20 nm or more, the circularity is calculated by the above method, and the arithmetic mean value of the 100 circularity values thus obtained is defined as the circularity of the spherical boron nitride (b1).

[0050] Since the circularity of the spherical boron nitride (b1) improves the filling property and reduces the influence of orientation, it is preferably 0.8 or more, and more preferably 0.9 or more.

[0051] The spherical boron nitride (b1) preferably contains hexagonal boron nitride. In this case, since the hardness of the hexagonal boron nitride is low, an excessive increase in the elastic modulus of the cured product is particularly unlikely to occur. It is also preferable that all of the spherical boron nitride (b1) is hexagonal boron nitride.

[0052] Spherical boron nitride (b1) containing hexagonal boron nitride is produced, for example, by a vapor phase synthesis method. Specifically, for example, first, boric acid alkoxide volatilized in an inert gas stream and ammonia are heated at 750 to 1100 °C for a time within 30 seconds to obtain a white boron nitride powder. Next, the white boron nitride powder is heated at 1000 to 1600 °C for 1 hour or more in an atmosphere containing ammonia gas to obtain a fired product. Next, the fired product is heated at 1000 to 3000 °C for 0.5 hour or more in a nitrogen atmosphere to obtain spherical boron nitride (b1) containing hexagonal boron nitride.

[0053] The proportion of spherical boron nitride (b1) is preferably 1% by mass or more and 20% by mass or less with respect to the molding resin composition. When this proportion is 3% by mass or more, the thermal conductivity of the cured product is likely to increase. When this proportion is 20% by mass or less, the fluidity of the composition (X) is particularly unlikely to be inhibited, and therefore the composition (X) is particularly likely to have good moldability. The proportion of spherical boron nitride (b1) is more preferably 3% by mass or more and 20% by mass or less, and even more preferably 10% by mass or more and 15% by mass or less.

[0054] Also, the proportion of spherical boron nitride (b1) is preferably 10% by mass or more and 40% by mass or less with respect to the inorganic filler (B). This proportion is more preferably 15% by mass or more and 30% by mass or less.

[0055] The median diameter of spherical boron nitride (b1) is preferably 0.05 μm or more and 1 μm or less. When the median diameter is 0.05 μm or more, the thixotropy of the composition (X) is less likely to increase excessively, and therefore the fluidity of the composition (X) is less likely to be inhibited further. Also, when the median diameter is 1 μm or less, the composition (X) is likely to flow in a narrow space, for example, smoothly flow in a space with a width of 1 mm. This median diameter is more preferably 0.1 μm or more and 0.8 μm or less, and even more preferably 0.3 μm or more and 0.6 μm or less. The median diameter of spherical boron nitride (b1) is calculated from the volume-based particle size distribution obtained by measuring spherical boron nitride (b1) by the laser diffraction / scattering method.

[0056] In addition to the spherical boron nitride (b1), the inorganic filler (B) preferably further contains a filler (b3) having a median diameter of 0.1 μm or more and 10 μm or less. In this case, since the particles of the spherical boron nitride (b1) are likely to be arranged between the particles of the filler (b3) in the composition (X), the spherical boron nitride (b1) and the filler (b3) are likely to be densely filled in the composition (X). Therefore, even if the amount of the inorganic filler (B) is increased, the fluidity of the composition (X) is less likely to be inhibited. Also, since the particles of the spherical boron nitride (b1) are likely to be arranged between the particles of the filler (b3) even in the cured product, the spherical boron nitride (b1) and the filler (b3) are likely to be densely filled in the composition (X). Therefore, a heat conduction path due to the inorganic filler (B) is likely to be formed in the cured product, and the thermal conductivity of the cured product is more likely to be further increased. The median diameter of the filler (b3) is more preferably 0.5 μm or more and 5 μm or less, and even more preferably 1 μm or more and 3 μm or less.

[0057] There is no particular limitation on the material of the filler (b3). Preferably, the filler (b3) contains at least one selected from the group consisting of aluminum hydroxide, boehmite, magnesium oxide, zinc oxide, aluminum nitride, silicon nitride, silicon carbide, and diamond. In this case, the thermal conductivity of the cured product is more likely to be further increased.

[0058] The filler (b3) may contain alumina. In particular, it is preferable that the filler (b3) contains α-alumina. In this case, the thermal conductivity of the cured product is more likely to be further increased. If the α conversion rate of α-alumina is 80% or more, it is more preferable. In this case, the thermal conductivity of the cured product is particularly likely to be increased. The α conversion rate of α-alumina is calculated from the diffraction spectrum of α-alumina obtained using a powder X-ray diffractometer, from the height (I 25.6 ) of the peak of the α-phase of alumina that appears at the position of 2θ = 25.6°, and the peak heights (I 46 ) of the γ-phase, η-phase, χ-phase, κ-phase, θ-phase, and δ-phase that appear at the position of 2θ = 46°, according to the formula of I 25.6 / (I 25.6 +I 46 )×100 (%).

[0059] It is particularly preferred that the composition (X) contains both an epoxy resin (a1) having a mesogenic skeleton and α-alumina. In this case, the fluidity of the composition (X) and the thermal conductivity of the cured product are particularly likely to be enhanced. The reason is not clear, but it is presumed that in the composition (X), the molecules of the epoxy resin (a1) having a mesogenic skeleton are likely to be oriented perpendicular to the surface of the α-alumina particles, which is involved in the improvement of fluidity and thermal conductivity.

[0060] The proportion of the filler (b3) is preferably 70% by mass or more and 97% by mass or less based on the total amount of the inorganic filler (B). When the filler (b3) contains α-alumina, the proportion of α-alumina is preferably 70% by mass or more and 97% by mass or less based on the total amount of the inorganic filler (B).

[0061] When the inorganic filler (B) contains spherical boron nitride (b1) and the filler (b3), the total proportion of the spherical boron nitride (b1) and the filler (b3) is preferably 75% by mass or more and 95% by mass or less based on the composition (X). When this proportion is 75% by mass or more, the cured product is particularly likely to have high thermal conductivity. Also, when this proportion is 95% by mass or less, the fluidity of the composition (X) is particularly unlikely to be inhibited. This proportion is more preferably 80% by mass or more and 93% by mass or less, and even more preferably 83% by volume or more and 91% by volume or less.

[0062] Also, the proportion of the inorganic filler (B) is preferably 75% by mass or more and 95% by mass or less based on the composition (X). When this proportion is 75% by mass or more, the cured product is particularly likely to have high thermal conductivity. Also, when this proportion is 95% by mass or less, the fluidity of the composition (X) is particularly unlikely to be inhibited. This proportion is more preferably 80% by mass or more and 93% by mass or less, and even more preferably 83% by mass or more and 91% by mass or less.

[0063] The inorganic filler (B) may further contain spherical boron nitride (b1) and a filler (b4) other than the filler (b3). However, the proportion of the filler (b4) is preferably 15% by mass or less, more preferably 10% by mass or less, and still more preferably 10% by mass or less with respect to the inorganic filler (B).

[0064] The proportion of the flaky boron nitride (b2) in the inorganic filler (B) is 0% by mass or more and less than 3% by mass with respect to the composition (X). That is, the inorganic filler (B) does not contain flaky boron nitride (b2), or even if it contains flaky boron nitride (b2), the proportion of the flaky boron nitride (b2) in the inorganic filler (B) is more than 0% by mass and less than 3% by mass with respect to the composition (X). Flaky particles tend to be a factor that inhibits the fluidity of the composition (X). However, as described above, if the inorganic filler (B) does not contain flaky boron nitride (b2), or if the proportion of the flaky boron nitride (b2) is more than 0% by mass and less than 3% by mass, the fluidity of the composition (X) is less likely to be inhibited. The proportion of the flaky boron nitride (b2) is more preferably 2% by mass or less, and still more preferably 1% by mass or less. It is particularly preferable that the inorganic filler (B) does not contain flaky boron nitride (b2).

[0065] The proportion of the flaky particles in the inorganic filler (B) is preferably 0% by mass or more and less than 3% by mass with respect to the composition (X). That is, the inorganic filler (B) is not limited to the flaky boron nitride (b2), and does not contain flaky particles, or even if it contains flaky particles, the proportion of the flaky particles in the inorganic filler (B) is preferably more than 0% by mass and less than 3% by mass with respect to the composition (X). In this case, the fluidity of the composition (X) is less likely to be inhibited by the inorganic filler (B). The proportion of the flaky particles is more preferably 2% by mass or less, and still more preferably 1% by mass or less. It is particularly preferable that the inorganic filler (B) does not contain flaky particles.

[0066] The proportion of particles with a particle size of 32 μm or less in the inorganic filler (B) is preferably 99.9% by volume or more based on the inorganic filler (B). In this case, the filling property of the composition (X) is particularly unlikely to be inhibited by the inorganic filler (B), and the composition (X) is particularly likely to fill a narrow space. For example, it can smoothly fill a space with a width of 1 mm. Further, it is more preferable that the maximum particle size of the inorganic filler (B) is 32 μm or less, still more preferable that it is 30 μm or less, and particularly preferable that it is 25 μm or less. The proportion of particles with a particle size of 32 μm or less and the maximum particle size in the inorganic filler (B) are determined from the volume-based particle size distribution obtained by measuring the inorganic filler (B) by the laser diffraction / scattering method.

[0067] The inorganic filler (B) may be surface-treated with a coupling agent such as a silane coupling agent. Further, the composition (X) may contain a coupling agent.

[0068] The composition (X) may further contain components other than the components described above. For example, the composition (X) may contain appropriate additives. The additives contain at least one selected from the group consisting of, for example, fluxes, ion trap agents, viscosity modifiers, surface modifiers, defoamers, leveling agents, low stress agents, pigments, and mold release agents.

[0069] The composition (X) can be obtained, for example, by blending the above-described components and adding an appropriate solvent as necessary and mixing them.

[0070] When the composition (X) is liquid, the composition (X) can be prepared, for example, by the following method. First, components that can be included in the composition (X) described above are blended simultaneously or sequentially to obtain a mixture. This mixture is stirred and mixed while performing heat treatment or cooling treatment as necessary. Next, additives are added to this mixture as necessary, and it is stirred again while performing heat treatment or cooling treatment as necessary until it is uniformly dispersed. Thereby, the composition (X) can be obtained. For stirring the mixture, for example, a disper, a planetary mixer, a ball mill, a three-roll mill, and a bead mill can be appropriately combined and applied as necessary.

[0071] When the composition (X) is in a solid state, the composition (X) can be prepared, for example, by the following method. First, the components that may be included in the composition (X) described above are blended simultaneously or sequentially to obtain a mixture. This mixture is mixed using a mixer, blender, etc. until it becomes sufficiently uniform, and then melt-kneaded using a kneader such as a hot roll or a kneader. Subsequently, after cooling the mixture to room temperature, it is pulverized to obtain a powdery composition (X). Further, a tablet-shaped composition (X) may be obtained by tableting the powdery composition (X).

[0072] When molding the composition (X), the composition (X) can have good fluidity as described above. In particular, the spiral flow length of the composition (X) is preferably 50 cm or more. In this case, the composition (X) can have particularly good moldability. The spiral flow length is more preferably 80 cm or more, and even more preferably 100 cm or more. The details of the method for measuring the spiral flow length will be described in the Examples section below.

[0073] Also, when the composition (X) is in a liquid state, the viscosity of the composition (X) at 25°C is preferably less than 35 Pa·s. In this case, when molding the composition (X), the coating workability and discharge stability by jet dispensing can be improved. The viscosity of the composition (X) at 25°C is more preferably 25 Pa·s or less, and even more preferably 20 Pa·s or less. The lower limit of the viscosity of the composition (X) at 25°C is not particularly limited, but is, for example, 500 mPa·s or more.

[0074] In addition, the cured product obtained by curing the composition (X) can have high thermal conductivity as described above. In particular, the thermal conductivity of the cured product is preferably 2 W / mK or more. In this case, the sealing material 4 produced from the composition (X) can have excellent thermal conductivity and heat dissipation properties. This thermal conductivity is more preferably 3 W / mK or more, and even more preferably 5 W / mK or more. The thermal conductivity is measured by the xenon flash method. Details of the measurement method will be described in the Examples section below.

[0075] Also, as described above, the elastic modulus of the cured product of the composition (X) does not easily become excessively high, and therefore, the cured product can have a low elastic modulus. In particular, the flexural elastic modulus of the cured product according to JIS K6911 is preferably 10 GPa or more and 30 GPa or less. In this case, the processability of the sealing material 4 produced from the composition (X) tends to be good, and warping of the sealing material 4 is less likely to occur. The flexural elastic modulus is more preferably 10 GPa or more and 25 GPa or less, and even more preferably 10 GPa or more and 20 GPa or less. Details of the measurement method for the flexural elastic modulus will be described in the Examples section below.

[0076] As described above, a sealing material 4 for encapsulating the electronic component 3 can be produced from the composition (X). The sealing material 4 and the electronic device 1 including the sealing material 4 will be described.

[0077] The electronic device 1 shown in FIG. 1 includes a substrate 2, an electronic component 3 flip-chip mounted on the substrate 2, and a sealing material 4 for encapsulating the electronic component 3. There is a gap between the substrate 2 and the electronic component 3, and a plurality of bumps 5 for electrically connecting the substrate 2 and the electronic component 3 are provided in this gap.

[0078] The substrate 2 is, for example, a printed wiring board. There is no limitation on the configuration of the electronic component 3 as long as it can be flip-chip mounted on the substrate 2. The electronic component 3 is, for example, an interposer or a semiconductor element. The semiconductor element may be a bare chip or a semiconductor package.

[0079] In the electronic device 1 shown in FIG. 1, the encapsulant 4 covers the entire electronic component 3 and fills the gap between the electronic component 3 and the base material 2. This encapsulant 4 is produced, for example, by molding the composition (X) by a mold molding method such as a transfer molding method after mounting the electronic component 3 on the base material 2. When the encapsulant 4 is produced in this way, in this embodiment, since the composition (X) can have good fluidity, when the composition (X) flows through the gap between the electronic component 3 and the base material 2, the composition (X) is likely to be sufficiently filled in this gap. Further, the composition (X) is likely to flow through the gap between adjacent bumps 5 in the gap between the electronic component 3 and the base material 2. Therefore, unfilling of the encapsulant 4 is less likely to occur. Also, the encapsulant 4 can have good thermal conductivity and heat dissipation properties, the processability of the encapsulant 4 is good, and further, warping is less likely to occur in the encapsulant 4.

[0080] The electronic device 1 shown in FIG. 2 includes, similarly to the case of FIG. 1, a base material 2, an electronic component 3 flip-chip mounted on the base material 2, and an encapsulant 4 that encapsulates the electronic component 3. There is a gap between the base material 2 and the electronic component 3, and a plurality of bumps 5 that electrically connect the base material 2 and the electronic component 3 are provided in this gap.

[0081] In the electronic device 1 shown in FIG. 2, the encapsulant 4 fills the gap between the electronic component 3 and the base material 2. That is, this encapsulant 4 is an underfill. This encapsulant 4 is produced, for example, by a capillary flow method after mounting the electronic component 3 on the base material 2. That is, the encapsulant 4 can be produced by injecting a liquid composition (X) into the gap between the base material 2 and the electronic component 3 and then curing the composition (X). Also in the case of producing the encapsulant 4 in this way, in this embodiment, since the composition (X) can have good fluidity, when the composition (X) flows through the gap between the electronic component 3 and the base material 2, the composition (X) is likely to be sufficiently filled in this gap. Further, the composition (X) is likely to flow through the gap between adjacent bumps 5 in the gap between the electronic component 3 and the base material 2. Therefore, unfilling of the encapsulant 4 is less likely to occur. Also, the encapsulant 4 can have good thermal conductivity and heat dissipation properties, the processability of the encapsulant 4 is good, and further, warping is less likely to occur in the encapsulant 4.

[0082] The form of the sealing material 4 is not limited to the above. Also, for example, when producing the sealing material 4 shown in FIG. 2, the sealing material 4 may be produced by a method other than the capillary flow method. For example, the sealing material 4 can also be produced by the NCF (Non Conductive Film) method. Specifically, for example, the composition (X) is formed into a sheet shape and then semi-cured to produce a film material (NCF). The electronic component 3 is stacked on the base material 2 via the film material, and in this state, by heating, the film material is melted and then cured to produce the sealing material 4, and the electronic component 3 is electrically connected to the base material 2 via the bump 5. Even in this case, since good fluidity can be exhibited when the film material melts, it is difficult for unfilled portions to occur in the sealing material 4.

[0083] In addition, the composition (X) may be used to produce molded articles and the like other than the sealing material 4. For example, parts or portions having electrical insulation in various electronic devices can be produced from the composition (X). Regardless of the molded article to be produced, since the composition (X) can have good fluidity, the moldability is good, and it is easy to increase the thermal conductivity of the molded article, and it is difficult for the elastic modulus of the molded article to become excessively high.

Example

[0084] 1. Preparation of composition The raw materials shown in the table were blended, uniformly mixed and dispersed with a mixer, and then heat-kneaded at about 110 °C for about 10 minutes using a mixing roll to obtain a mixture. Subsequently, the mixture was cooled and then pulverized. By tableting the obtained powder, a tablet-shaped composition was obtained. The details of the raw materials are as follows. - Spherical alumina (45 μm): manufactured by Denka Co., Ltd. Product number DAW-45. Median diameter 45 μm. - Spherical alumina (10 μm): manufactured by Denka Co., Ltd. Product number DAW-10. Median diameter 10 μm. - Spherical alumina (5 μm): manufactured by Denka Co., Ltd. Product number DAW-0525. Median diameter 5 μm. - Spherical alumina (0.3 μm): manufactured by Admatechs Co., Ltd. Product number AO-502. Median diameter 0.3 μm. - Polyhedral α-alumina (5 μm): manufactured by Sumitomo Chemical Co., Ltd. Product number AA-5. Median diameter 5 μm. α conversion rate 100%. - Polyhedral α-alumina (1.5 μm): manufactured by Sumitomo Chemical Co., Ltd. Product number AA-1.5. Median diameter 1.5 μm. α conversion rate 100%. - Polyhedral α-alumina (0.3 μm): manufactured by Sumitomo Chemical Co., Ltd. Product number AA-03F. Median diameter 0.3 μm. α conversion rate 100%. - Spherical boron nitride (0.5 μm): hexagonal spherical boron nitride. Median diameter 0.5 μm. Circularity 0.9. - Flake-shaped boron nitride (6 μm): manufactured by Denka Co., Ltd. Product number SP-3. Median diameter 6 μm. - Flake-shaped boron nitride (0.7 μm): manufactured by Showa Denko K.K. Product number UHP-S2. Median diameter 0.7 μm. - Silane coupling agent: N-phenyl-3-aminopropyltrimethoxysilane. Manufactured by Shin-Etsu Chemical Co., Ltd. Product number KBM-573. - Epoxy resin A: biphenyl type epoxy resin. Manufactured by Mitsubishi Chemical Corporation. Product number YX4000H. Epoxy equivalent 190 g / eq. - Epoxy resin B: stilbene type epoxy resin corresponding to the above epoxy resin (a12). Manufactured by Nippon Kayaku Co., Ltd. Product number TCX-8. Epoxy equivalent 225 g / eq. - Epoxy resin C: a modified epoxy resin synthesized by reacting a mixture of hydroquinone and 4,4'-dihydroxybiphenyl with epichlorohydrin. Epoxy equivalent 140 g / eq. - Hardening agent: phenol novolak resin. Manufactured by Meiwafosis Co., Ltd. Product number DL-92. OH equivalent 105 g / eq. - Release agent: carnauba wax. Manufactured by Dainichi Chemical Industry Co., Ltd. Product number F1-100. - Curing accelerator: Phosphorus-based curing accelerator. Manufactured by Panasonic Corporation. Product number KXM-J. A compound with a phosphonium cation concentration of 10% by mass obtained by heating tetraphenylphosphonium tetraphenylborate (product number TPP-K manufactured by Kitakyo Chemical Industry Co., Ltd.) and low-viscosity phenol novolak resin (product number H-4 manufactured by Meiwafosis Co., Ltd.) at 170 - 180 °C in a nitrogen atmosphere, cooling the resulting product, and then pulverizing it. - Pigment: Carbon black. Manufactured by Mitsubishi Chemical Corporation. #40.

[0085] 2. Evaluation tests (1) Thermal conductivity Using a transfer molding machine, the composition was molded by the transfer molding method under the conditions of a mold temperature of 175 °C, an injection pressure of 6.9 MPa, and a curing time of 180 seconds, and then post-cured by heating at 175 °C for 6 hours to produce a disk-shaped cured product with a diameter of 50 mm and a thickness of 1 mm. This cured product was cut to produce a sample with dimensions of 9.8 mm × 9.8 mm. A graphite spray (FC-153) manufactured by Fine Chemical Japan was sprayed onto this sample.

[0086] The thermal diffusivity in the thickness direction of this sample at 25 °C (unit: cm 2 / s) was measured using a xenon flash method thermal diffusivity measuring device (manufactured by NETZSCH, model number NanoFlash LFA447). Also, the density of the test piece (unit: g / cm 3 ) was measured by the Archimedes method, and the specific heat of the test piece (unit: J / (g·K)) was measured by a method using a differential scanning calorimeter (DSC method). From these results, the thermal conductivity in the thickness direction of the sample (unit: W / mK) was calculated using the following formula. (Thermal conductivity) = (density) × (thermal diffusivity) × (specific heat)

[0087] (2) Flexural modulus Using a transfer molding machine, the composition was molded by the transfer molding method under the conditions of a mold temperature of 175 °C, an injection pressure of 6.9 MPa, and a curing time of 180 seconds, and then post-cured by heating at 175 °C for 6 hours to prepare a test piece with dimensions of 10 mm × 80 mm × 3 mm. For this test piece, a three-point bending test was performed using a universal tensile compression testing machine at room temperature (25 °C) to measure the flexural modulus. The measurement conditions were a test speed of 2 mm / min and a distance between supports of 48 mm.

[0088] (3) Coefficient of thermal expansion Test pieces were prepared in the same manner as in the case of the above-mentioned "(2) Flexural modulus". Using a thermomechanical analyzer (manufactured by TA Instruments), the temperature of the test piece was raised from 40 °C to 280 °C at a rate of 5 °C per minute, and the average linear expansion coefficient in the thickness direction of the test piece from 50 °C to 80 °C was measured.

[0089] (4) Gel time Using a curastometer (manufactured by TSE Engineering Co., Ltd.), the torque value was measured while heating the composition at 175 °C. The time until the torque value reached 4.9 N / m (0.5 kgf·cm) was defined as the gel time.

[0090] (5) Spiral flow length Using a transfer molding machine (manufactured by Kando Metal Industry Co., Ltd.), the composition was injected into a spiral flow dedicated mold prepared based on ASTM D 3123 under the conditions of a mold temperature of 175 °C, an injection pressure of 6.9 MPa, and a curing time of 180 seconds, and the length of the flowing composition was measured.

[0091] (6) Moldability Using a transfer molding machine (manufactured by Kando Metal Industry Co., Ltd.), a cured product was prepared by molding the composition by the transfer molding method in a mold having a disk-shaped cavity with a diameter of 50 mm and a thickness of 1 mm under the conditions of a mold temperature of 175 °C, an injection pressure of 6.9 MPa, and a curing time of 180 seconds. The appearance of this cured product was visually observed, and it was evaluated as "good" when there were no voids, cracks, or flow marks, and as "bad" when there was at least one of voids, cracks, and flow marks.

[0092] The above results are shown in Table 1.

[0093]

Table 1

Explanation of Symbols

[0094] 1 Electronic device 2 Substrate 3 Electronic component 4 Encapsulant

Claims

1. A resin composition for molding, containing a reactive curable resin (A) and an inorganic filler (B), The inorganic filler (B) contains spherical boron nitride (b1), The inorganic filler (B) does not contain flaky boron nitride (b2), or the inorganic filler (B) contains flaky boron nitride (b2) and the proportion of the flaky boron nitride (b2) in the inorganic filler (B) is more than 0% by mass and less than 3% by mass with respect to the resin composition for molding, The median diameter of the spherical boron nitride (b1) is 0.05 μm or more and 0.8 μm or less, The inorganic filler (B) further contains a filler (b3) having a median diameter of 1 μm or more and 10 μm or less, The filler (b3) contains α-alumina, A resin composition for molding.

2. The circularity of the spherical boron nitride (b1) is 0.8 or more, The resin composition for molding according to Claim 1.

3. The spherical boron nitride (b1) contains hexagonal boron nitride, The resin composition for molding according to Claim 1 or 2.

4. The proportion of the spherical boron nitride (b1) is 1% by mass or more and 20% by mass or less with respect to the resin composition for molding, The resin composition for molding according to any one of Claims 1 to 3.

5. The filler (b3) contains at least one selected from the group consisting of aluminum hydroxide, boehmite, magnesium oxide, zinc oxide, aluminum nitride, silicon nitride, silicon carbide, and diamond, The resin composition for molding according to any one of Claims 1 to 4.

6. The total proportion of the spherical boron nitride (b1) and the filler (b3) is 75% by mass or more and 95% by mass or less with respect to the resin composition for molding, The resin composition for molding according to any one of claims 1 to 5.

7. The proportion of particles having a particle size of 32 μm or less in the inorganic filler (B) is 99.9% by volume or more based on the inorganic filler (B). The resin composition for molding according to any one of claims 1 to 6.

8. The reactive curable resin (A) contains an epoxy resin (a). The resin composition for molding according to any one of claims 1 to 7.

9. It is used for producing a sealing material for sealing electronic components. The resin composition for molding according to any one of claims 1 to 8.

10. The reactive curable resin (A) contains an epoxy resin (a1) having a mesogenic skeleton, and the resin composition for molding according to any one of claims 1 to 9.

11. The mesogenic skeleton includes at least one skeleton selected from the group consisting of a benzoic acid phenyl skeleton, a biphenyl skeleton, a benzophenone skeleton, a phenyl ether skeleton, a benzanilide skeleton, a stilbene skeleton, a diazobenzene skeleton, and a benzylideneaniline skeleton. The resin composition for molding according to claim 10.

12. A base material, An electronic component mounted on the base material, And a sealing material for sealing the electronic component, The sealing material is a cured product of the resin composition for molding according to any one of claims 1 to 11. An electronic device.

13. The sealing material at least seals the gap between the base material and the electronic component. The electronic device according to claim 12.

Images