Thermosetting resin composition, cured product, and substrate

Abstract

A thermosetting resin composition containing a thermosetting resin, a thermally conductive filler, a curing agent, and an additive, where, when the shear rate is increased from 0 s-1 to 300 s-1, then held for one minute at 300 s-1, then decreased from 300 s-1 to 150 s-1 using a rheometer at 25° C, the shear stress of the thermosetting resin composition at 150 s-1 is 1000 Pa or more and the thermal conductivity of a cured product of the thermosetting resin composition is 3.0 W / m∙K or more.

Description

Thermosetting resin compositions, cured products, and substrates

[0001] The present invention relates to thermosetting resin compositions, cured products, and substrates.

[0002] In recent years, the electrification of automobiles has progressed from the perspective of reducing the burden on the environment, and power semiconductors, which are semiconductors that can conduct high voltage and large current, are increasingly being used in in-vehicle inverters, converters, etc. Because power semiconductors conduct high voltage and large current, the substrates on which they are mounted tend to become hot, and in order to maintain continuous and stable performance, it is necessary to improve the heat dissipation of the substrate.

[0003] Conventionally, heat dissipation materials containing thermally conductive inorganic particles and resin have been used to dissipate heat from substrates. For example, Patent Document 1 discloses a high voltage-resistant heat-dissipating insulating resin composition in which the particle size ratio of thermally conductive fillers is optimized, allowing for close-packed thermally conductive fillers in a curable resin.

[0004] International Publication No. 2020 / 105215

[0005] One technique used to improve the heat dissipation of circuit boards is to embed heat dissipation material in through-holes, grooves in inlay structures, and other perforations within the circuit board.

[0006] However, in the technology described in Patent Document 1, because the thermally conductive filler is highly concentrated, it is not easy to embed the resin composition in the penetration, and there is a problem that it bleeds out from the back side after embedding.

[0007] The present invention aims to provide a thermosetting resin composition that has good thermal conductivity, good embedding properties in through-holes, grooves in inlay structures, and recesses, and that can suppress bleed-out from the back surface after embedding. The present invention also aims to provide a cured product of the composition and a substrate equipped with the cured product.

[0008] In order to solve the above problems, the inventors have conducted extensive research and have found that when a thermosetting resin composition is used which includes a thermosetting resin, a thermally conductive filler, a curing agent, and an additive, and in which the shear stress is within a specific range and the thermal conductivity of the cured product is 3.0 W / m·K or higher, the thermal conductivity is good, the embedding properties in penetrations and the like are good, and bleed-out from the back surface after embedding can be suppressed.

[0009] The present invention was completed based on these findings and includes the following broad embodiments of the invention: [Item 1] A thermosetting resin composition comprising a thermosetting resin, a thermally conductive filler, a curing agent, and an additive, wherein the shear rate is 0 s at a temperature of 25°C using a rheometer. －１ From 300s －１ After increasing it to 300s －１ Hold for 1 minute, then 300 seconds －１ From 150s －１ When reduced to 150s －１ A thermosetting resin composition wherein the shear stress of the thermosetting resin composition is 1000 Pa or more, and the thermal conductivity of the cured product of the thermosetting resin composition is 3.0 W / m·K or more. [Item 2] The thermosetting resin composition according to Item 1, wherein the additive comprises a rheology modifier and a wetting dispersant. [Item 3] The thermosetting resin composition according to Item 2, wherein the rheology modifier comprises an inorganic rheology modifier and an organic rheology modifier. [Item 4] The thermosetting resin composition according to any one of Items 1 to 3, wherein the thermal conductivity of the thermal conductive filler is 20 W / m·K or more. [Item 5] The thermosetting resin composition according to any one of Items 1 to 4, wherein the content of the thermal conductive filler in the thermosetting resin composition is 75 to 95 parts by mass per 100 parts by mass of the thermosetting resin composition, on a solid content basis. [Item 6] A cured product of the thermosetting resin composition according to any one of Items 1 to 5. [Item 7] A substrate comprising the cured product according to Item 6.

[0010] According to the present invention, there can be provided a thermosetting resin composition that has excellent thermal conductivity, excellent embedding properties into through portions such as through-holes and grooves of an inlay structure, and recessed portions, and can suppress bleed-out from the back surface after embedding. Further, the present invention can also provide a cured product of the composition, and a substrate including the cured product.

[0011] In the present specification, the singular forms (a, an, the, etc.) shall include both the singular and the plural, unless otherwise explicitly stated herein or clearly contradicted by context. In the present specification, the term "comprise" is a concept that also includes "consist essentially of" and "consist of".

[0012] In the present specification, (meth)acrylate means at least one selected from the group consisting of acrylate (acrylic acid ester) and methacrylate (methacrylic acid ester). In addition, when a numerical range is expressed using "~" as in "A to B", this means "A or more and B or less" unless otherwise specified.

[0013] 1. Thermosetting resin composition The present invention provides a thermosetting resin composition. The thermosetting resin composition of the present invention includes a thermosetting resin, a thermally conductive filler, a curing agent, and an additive. The thermosetting resin composition of the present invention was measured using a rheometer at a temperature of 25°C, with a shear rate of 0 s －１ to 300 s －１ after the increase, 300 s －１ was held for 1 minute, then 300 s －１ to 150 s －１ when decreased, the shear stress at 150 s －１ is 1000 Pa or more. Further, the thermal conductivity of the cured product of the thermosetting resin composition of the present invention is 3.0 W / m·K or more.

[0014] Hereinafter, the components of the thermosetting resin composition of the present invention will be described.

[0015] <Thermosetting Resin> The thermosetting resin composition of the present invention contains a thermosetting resin. The thermosetting resin can be used without particular limitations as long as it can be cured by heat. Examples include isocyanate compounds, blocked isocyanate compounds, amino resins, maleimide compounds, benzoxazine resins, carbodiimide resins, cyclocarbonate compounds, epoxy resins, oxetane compounds, episulfide resins, etc. Among these, epoxy resins are preferred. The thermosetting resin may be used alone or in combination of two or more types.

[0016] As the epoxy resin mentioned above, known and conventional compounds having one or more epoxy groups can be used, and among these, compounds having two or more epoxy groups are preferred. Examples include, but are not limited to, monoepoxy compounds such as butyl glycidyl ether, phenyl glycidyl ether, and glycidyl (meth)acrylate; epoxy resins having a bisphenol-type skeleton such as bisphenol A-type epoxy resin, bisphenol S-type epoxy resin, and bisphenol F-type epoxy resin; and compounds having two or more epoxy groups in one molecule, such as phenol novolac-type epoxy resin, cresol novolac-type epoxy resin, trisphenolmethane-type epoxy resin, alicyclic epoxy resin, aminophenol-type epoxy resin, trimethylolpropane polyglycidyl ether, phenyl-1,3-diglycidyl ether, biphenyl-4,4'-diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol or propylene glycol diglycidyl ether, sorbitol polyglycidyl ether, tris(2,3-epoxypropyl) isocyanurate, and triglycidyl tris(2-hydroxyethyl) isocyanurate. Epoxy resins may be used individually or in combination of two or more types.

[0017] In one embodiment, the thermosetting resin composition of the present invention preferably contains an epoxy resin having a bisphenol-type skeleton. Examples of epoxy resins having a bisphenol-type skeleton include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E (AD) type epoxy resin, bisphenol S type epoxy resin, and the like.

[0018] Furthermore, epoxy resins having a bisphenol-type skeleton can be used in liquid, semi-solid, or solid form, but among these, liquid form is preferred from the viewpoint of filling properties. Note that "liquid" refers to a state of being a liquid that is fluid at 20°C.

[0019] Examples of oxetane compounds include polyfunctional oxetanes such as bis[(3-methyl-3-oxetanylmethoxy)methyl] ether, bis[(3-ethyl-3-oxetanylmethoxy)methyl] ether, 1,4-bis[(3-methyl-3-oxetanylmethoxy)methyl]benzene, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, (3-methyl-3-oxetanyl)methyl acrylate, (3-ethyl-3-oxetanyl)methyl acrylate, (3-methyl-3-oxetanyl)methyl methacrylate, (3-ethyl-3-oxetanyl)methyl methacrylate, oligomers or copolymers thereof, as well as etherified products of oxetane alcohol with novolac resin, poly(p-hydroxystyrene), cardo-type bisphenols, calixarenes, calixresorcinarenes, or hydroxyl group-containing resins such as silsesquioxane. Other examples include copolymers of unsaturated monomers having an oxetane ring and alkyl (meth)acrylates.

[0020] Examples of episulfide resins include bisphenol A type episulfide resins. Furthermore, episulfide resins obtained by replacing the oxygen atoms in the epoxy groups of novolac-type epoxy resins with sulfur atoms using a similar synthesis method can also be used.

[0021] Examples of amino resins such as melamine derivatives and benzoguanamine derivatives include methylol melamine compounds, methylol benzoguanamine compounds, methylol glycoluril compounds, and methylol urea compounds.

[0022] As the isocyanate compound, a polyisocyanate compound can be blended. Examples of the polyisocyanate compound include aromatic polyisocyanates such as 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthalene-1,5-diisocyanate, o-xylylene diisocyanate, m-xylylene diisocyanate, and 2,4-tolylene dimer; aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4-methylenebis(cyclohexyl isocyanate), and isophorone diisocyanate; alicyclic polyisocyanates such as bicycloheptane triisocyanate; and adducts, biurets, and isocyanurates of the above-listed isocyanate compounds, among others.

[0023] As the blocked isocyanate compound, an addition reaction product of an isocyanate compound and an isocyanate blocking agent can be used. Examples of isocyanate compounds capable of reacting with an isocyanate blocking agent include the above-mentioned polyisocyanate compounds, among others. Examples of the isocyanate blocking agent include phenolic blocking agents; lactam-based blocking agents; active methylene-based blocking agents; alcohol-based blocking agents; oxime-based blocking agents; mercaptan-based blocking agents; acid amide-based blocking agents; imide-based blocking agents; amine-based blocking agents; imidazole-based blocking agents; imine-based blocking agents, among others.

[0024] From the viewpoint of thermal conductivity and mechanical strength of the cured product, the content of the thermosetting resin in the thermosetting resin composition, in terms of solid content, is preferably 5 to 25 parts by mass, and more preferably 7 to 15 parts by mass, relative to 100 parts by mass of the thermosetting resin composition.

[0025] <Thermally conductive filler> The thermosetting resin composition of the present invention contains a thermally conductive filler. Any thermally conductive filler is not particularly limited and can be used as long as it is a particle capable of conducting heat. It can be expected that the thermal conductivity of the thermosetting resin composition is improved by blending the thermally conductive filler into the thermosetting resin composition. One type of thermally conductive filler may be used alone, or two or more types may be used in combination. When the thermosetting resin composition contains the thermally conductive filler, the heat conduction efficiency of the thermosetting resin composition can be improved, and the specific gravity can also be adjusted.

[0026] The type of the thermally conductive filler is not particularly limited as long as the effects of the present invention are exhibited, and examples thereof include aluminum oxide (alumina), aluminum nitride, boron nitride, silicon nitride, silicon carbide, magnesium oxide, zinc oxide, diamond and the like. Examples of commercially available thermally conductive fillers include Denka Spherical Alumina DAW-03, DAW-07, ASFP-20 manufactured by Denka Company Limited.

[0027] The thermal conductivity of the thermally conductive filler is preferably 20 W / m·K or more, and more preferably 25 W / m·K or more. The upper limit is not particularly limited, but is, for example, 300 W / m·K or less.

[0028] The shape of the thermally conductive filler is not particularly limited, and examples thereof include spherical, fibrous, plate-like, amorphous, balloon-like shapes and the like.

[0029] A thermally conductive filler having an average particle diameter of 10 µm or less can be preferably used, and from the viewpoint of dispersibility, 0.01 to 3.0 µm is preferred, and 0.1 to 1.0 µm is more preferred. The average particle diameter can be measured using a laser diffraction / scattering type apparatus.

[0030] It is preferable to use a combination of two or more types of thermally conductive fillers having different average particle diameters and having a particle size distribution that forms a closest packed structure when blended into the thermosetting resin composition. In a thermosetting resin composition, when the thermally conductive filler forms a closest packed structure, the filling rate becomes higher, and the thermal conductivity and storage stability can be further improved.

[0031] In the thermosetting resin composition of the present invention, the content of the thermally conductive filler is preferably 75 to 95 parts by mass, and more preferably 82 to 90 parts by mass, on a solid content basis, per 100 parts by mass of the thermosetting resin composition, from the viewpoint of thermal conductivity.

[0032] <Curing Agent> The thermosetting resin composition of the present invention contains a curing agent for curing the thermosetting resin. As the curing agent, a known curing agent commonly used for curing thermosetting resins can be used. Specific curing agents include, for example, amines, imidazoles, polyfunctional phenols, acid anhydrides, and polymers containing these functional groups. Examples of amines include dicyandiamide and diaminodiphenylmethane. Examples of imidazoles include alkyl-substituted imidazole and benzimidazole. Examples of polyfunctional phenols include hydroquinone, resorcinol, bisphenol A and its halogen compounds, as well as novolac and resol resins, which are condensates of these with aldehydes. Examples of acid anhydrides include phthalic anhydride, hexahydrophthalic anhydride, methylnadic anhydride, and benzophenonetetracarboxylic acid. The curing agent may be used alone or in combination of two or more types.

[0033] Of the curing agents mentioned above, amines or imidazoles are preferred from the viewpoint of adhesion to conductive and insulating parts, storage stability, and heat resistance. As for amines, for example, adduct compounds of aliphatic polyamines, adduct compounds of alicyclic polyamines, and mixtures of aliphatic polyamine adduct compounds and alicyclic polyamine adduct compounds are preferred. As for imidazoles, imidazole compounds and imidazole adduct compounds are preferred.

[0034] Preferred adduct compounds for aliphatic polyamines are those obtained by adding an aryl glycidyl ether (particularly phenyl glycidyl ether or tolyl glycidyl ether) or an alkyl glycidyl ether to an aliphatic polyamine. Preferred adduct compounds for alicyclic polyamines are those obtained by adding an n-butyl glycidyl ether, bisphenol A diglycidyl ether, or the like to an alicyclic polyamine.

[0035] Examples of aliphatic polyamines include alkylenediamines with 2 to 6 carbon atoms, such as ethylenediamine and propylenediamine; polyalkylene polyamines with 2 to 6 carbon atoms, such as diethylenetriamine and triethylenetriamine; and aromatic ring-containing aliphatic polyamines with 8 to 15 carbon atoms, such as xylylenediamine.

[0036] Examples of alicyclic polyamines include isophoronediamine, 1,3-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane, norbornenediamine, 1,2-diaminocyclohexane, and laromine.

[0037] Examples of imidazole compounds include 2-methylimidazole, 4-methyl-2-ethylimidazole, 2-phenylimidazole, 4-methyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and 1-cyanoethyl-2-undecylimidazole.

[0038] Examples of imidazole adduct compounds include reaction products of epoxy resins and imidazole compounds. Examples of epoxy compounds used as adducts include bisphenol A type epoxy resins. As imidazole compounds used as adducts, for example, the above-mentioned imidazole compounds can be preferably used.

[0039] In the thermosetting resin composition of the present invention, the content of the curing agent is preferably 0.1 to 3 parts by mass, and more preferably 0.4 to 1.5 parts by mass, on a solid content basis, per 100 parts by mass of the thermosetting resin composition, from the viewpoint of promoting the thermosetting reaction.

[0040] <Additives> The thermosetting resin composition of the present invention includes additives in addition to a thermosetting resin, a thermally conductive filler, and a curing agent. Preferably, the additives include a rheology modifier and a wetting dispersant, more preferably an organic rheology modifier and a wetting dispersant, and particularly preferably an inorganic rheology modifier, an organic rheology modifier, and a wetting dispersant. By combining a rheology modifier and a wetting dispersant, it becomes easier to suppress sagging and bleeding out from the back side after embedding in through-holes, grooves in inlay structures, and recesses.

[0041] (Rheology modifier) ​​The rheology modifier preferably includes an organic rheology modifier, and more preferably includes both an organic rheology modifier and an inorganic rheology modifier.

[0042] Examples of organic rheology modifiers include modified urea, modified urea polyamide, fatty acid amide, ethylene bis-stearamide, hexamethylene bis-hydroxy-stearamide, polyhydroxycarboxylic acid ester, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, polyacrylic acid, polyethylene glycol, polyethylene oxide, polyoxyethylene-polypropylene block polymer, polyalkylene glycol derivatives, polyvinyl alcohol, ethylene-modified polyvinyl alcohol, polyvinylpyrrolidone, gum arabic, guar gum, hydroxypropylated guar gum, xanthan gum, locust bean gum, gellan gum, dieutan gum, dextrin, starch, gelatin, corn starch, pectin, amylopectin, polyglutamate, polyacrylamide, polyethyleneimine, polynaphthalene sulfonate, polycarboxylic acid copolymer, vinyl alcohol copolymer, vinylpyrrolidone copolymer, alginic acid, alginic acid ester, cellulose nanofiber, chitin nanofiber, and polyolefin cotton-like fiber. Among these, modified urea and polyhydroxycarboxylic acid esters are preferred.

[0043] Examples of inorganic rheological modifiers include fine silica, synthetic or natural swellable layered mineral particles (e.g., bentonite, hectorite, vermiculite, halosite, swellable mica, etc.), and ultrafine oxide particles (e.g., titania, zirconia, etc.).

[0044] The rheological modifier may be used alone or in combination of two or more types.

[0045] Examples of commercially available rheology modifiers include modified ureas such as BYK-7410CA, BYK-410, BYK-410D, BYK-7411ES, BYK-411, BYK-7420ES, and BYK-420 from BIC Chemie Japan Co., Ltd.; modified urea polyamides such as BYK-430 and BYK-431 from BIC Chemie Japan Co., Ltd.; polyhydroxycarboxylic acid esters such as BYK-R606 from BIC Chemie Japan Co., Ltd.; silica such as AEROSIL® 200 and AEROSIL RY200 from Nippon Aerosil Co., Ltd.; and bentonite such as Olben M from Shiraishi Industries Co., Ltd.

[0046] The content of the rheology modifier in the thermosetting resin composition is preferably 0.2 to 10 parts by mass, and more preferably 0.8 to 6 parts by mass, based on solid content, per 100 parts by mass of the thermosetting resin composition.

[0047] The content of the organic rheology modifier in the thermosetting resin composition is preferably 0.2 to 10 parts by mass, and more preferably 0.4 to 6 parts by mass, based on solid content, per 100 parts by mass of the thermosetting resin composition.

[0048] The content of the inorganic rheology modifier in the thermosetting resin composition is preferably 0.2 to 2 parts by mass, and more preferably 0.5 to 1.5 parts by mass, based on solid content, per 100 parts by mass of the thermosetting resin composition.

[0049] (Wetting and Dispersing Agents) Examples of wetting and dispersing agents include copolymers containing acid groups, pigment affinity block copolymers, phosphate ester compounds, polyether phosphate ester compounds, fatty acid ester compounds, alkylene oxide copolymers, modified polyether polymers, fatty acid derivatives, urethane polymers, and the like. Examples of commercially available products include ANTI-TERRA-U, ANTI-TERRA-U100, ANTI-TERRA-204, ANTI-TERRA-205, DISPERBYK-101, DISPERBYK-102, DISPERBYK-103, DISPERBYK-106, DISPERBYK-108, DISPERBYK-109, DISPERBYK-110, DISPERBYK-111, DISPERBYK-112, DISPERBYK-116, DI SPERBYK-130, DISPERBYK-140, DISPERBYK-142, DISPERBYK-145, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DISPERBYK- 164, DISPERBYK-166, DISPERBYK-167, DISPERBYK-168, DISPERBYK-170, DISPERBYK-171, DISPERBYK-174, DISPERBYK-180, DISPE RBYK-182, DISPERBYK-183, DISPERBYK-185, DISPERBYK-184, DISPERBYK-2000, DISPERBYK-2001, DISPERBYK-2009, DISPERBYK- 2020, DISPERBYK-2025, DISPERBYK-2050, DISPERBYK-2070, DISPERBYK-2096, DISPERBYK-2150, BYK-P104, BYK-P104S, BYKP105, BYK-9076, BYK-9077, BYK-220S, BYK-1160, BYK-1165, BYK-W903, BYK-W908, BYK-W909, BYK-W940, BYK-W961, BYK-W966, BYK-W969, BYK-W972, BYK-W974, BYK-W980, BYK-W985, BYK-W995, BYK-W996, BYK-W9010, BYK-W9011, BYK-W9012 (all manufactured by Big Chemie Japan Co., Ltd.)Examples include Disparon 2150, Disparon 1210, Disparon KS-860, Disparon KS-873N, Disparon 7004, Disparon 1830, Disparon 1860, Disparon 1850, Disparon DA-400N, Disparon PW-36, Disparon DA-703-50 (all manufactured by Kusumoto Kasei Co., Ltd.), Floren G-450, Floren G-600, Floren G-820, Floren G-700, Floren DOPA-44, Floren DOPA-17 (all manufactured by Kyoeisha Chemical Co., Ltd.).

[0050] The content of the wetting and dispersing agent in the thermosetting resin composition is preferably 0.2 to 3 parts by mass, and more preferably 0.5 to 2 parts by mass, based on solid content, per 100 parts by mass of the thermosetting resin composition.

[0051] <Other Additives> The thermosetting resin composition of the present invention may optionally further contain additives such as solvents, adhesion promoters, defoamers, curing accelerators, colorants, polymerization inhibitors, surfactants, co-sensitizers, thickeners, UV absorbers, antioxidants, ion catchers, coupling agents, tackifiers, and surface modifiers, to the extent that the effects of the present invention are exhibited.

[0052] The content of other additives in the thermosetting resin composition is preferably 0.01 to 10 parts by mass per 100 parts by mass of the thermosetting resin composition, based on solid content.

[0053] <Preparation of Thermosetting Resin Composition> The thermosetting resin composition of the present invention is prepared as a homogeneous liquid composition by mixing a thermosetting resin, a thermally conductive filler, a curing agent, and an additive.

[0054] The thermosetting resin composition of the present invention, when measured at a temperature of 25°C using a rheometer, has a shear rate of 0 s. －１ From 300s －１ After increasing it to 300s －１ Hold for 1 minute, then 300 seconds －１ From 150s －１ When reduced to 150s －１The shear stress (hereinafter also referred to as shear stress (A)) is 1000 Pa or more, preferably 1500 Pa or more, and more preferably 2500 Pa or more. The upper limit is not particularly limited, but for example, 5000 Pa or less is preferred. By being within the above range, it is possible to suppress sagging and seepage (bleed-out) that flows out from the back side after embedding in through-holes, grooves in inlay structures, and recesses.

[0055] When embedding a thermosetting resin composition into a penetration, the composition first begins to flow into the hole, increasing its shear rate. Subsequently, the shear rate is maintained at a constant level while the thermosetting resin composition is flowing into the hole. Towards the end of the embedding process, the shear rate decreases to stop the flow of the thermosetting resin composition. When the shear rate decreases and there is no shear stress, it becomes difficult to retain the thermosetting resin composition in the penetration, and it flows out from the back side, resulting in bleed-out. However, when the shear rate decreases, if there is a shear stress above a certain level, it becomes possible to retain the thermosetting resin composition in the penetration, thereby suppressing bleed-out from the back side.

[0056] The shear stress (A) of the thermosetting resin composition can be measured using the HAAKE RS6000 rheometer manufactured by Thermo Fisher Scientific Co., Ltd. as follows. First, a φ20 mm sensor parallel plate is attached to the instrument as a rotor, and the temperature is maintained at 25.0°C. Next, 0.3 mL of the thermosetting resin composition is weighed out and placed on the sensor parallel plate, and the gap between the plates is maintained at 0.5 mm. In rotation mode, the parallel plate is sheared for 60 seconds at a shear rate of 0 s －１ From 300s －１ After rotating it to that point, 300s －１ Hold for 60 seconds. Then, increase the shear rate to 300 s for 60 seconds. －１ from 0s －１ Shear rate when rotation is changed to 150 s －１ The shear stress (A) at that time is measured.

[0057] The thermosetting resin composition of the present invention, when measured at a temperature of 25°C using a rheometer, has a shear rate of 0 s. －１ From 300s －１ After increasing it to 300s －１ The shear stress (hereinafter also referred to as shear stress (B)) when held for one minute is preferably 1500 Pa or more, and more preferably 2000 Pa or more. Furthermore, the upper limit is preferably 8000 Pa or less, and more preferably 6000 Pa or less. Being within the above range ensures good embedding in through-holes, grooves in inlay structures, and recesses, and also suppresses bleed-out from the back side after embedding.

[0058] As described above, when embedding a thermosetting resin composition into a penetration, the thermosetting resin composition first begins to flow into the penetration hole, increasing its shear rate. Subsequently, the shear rate is maintained at a constant level while the thermosetting resin composition is flowing into the penetration hole. Then, towards the end of the embedding process, the shear rate decreases to stop the flow of the thermosetting resin composition. Because the shear stress remains within a constant range while the thermosetting resin composition is flowing into the penetration hole, the embedding into the structure of the penetration is good, and bleed-out from the back side after embedding is also suppressed.

[0059] The shear stress (B) of the thermosetting resin composition can be measured using the HAAKE RS6000 rheometer manufactured by Thermo Fisher Scientific Co., Ltd. as follows. First, a φ20 mm sensor parallel plate is attached to the instrument as a rotor, and the temperature is maintained at 25.0°C. Next, 0.3 mL of the thermosetting resin composition is weighed out and placed on the sensor parallel plate, and the gap between the plates is maintained at 0.5 mm. In rotation mode, the parallel plate is sheared for 60 seconds at a shear rate of 0 s －１ From 300s －１ After rotating it to that point, 300s －１Hold for 60 seconds and measure the shear stress. Repeat the above procedure three times, and the average of the obtained values ​​will be taken as the shear stress (B).

[0060] The thermosetting resin composition of the present invention has a cured product with a thermal conductivity of 3.0 W / m·K or higher, preferably 3.2 W / m·K or higher, and more preferably 3.4 W / m·K or higher. The upper limit is not particularly limited, but for example, it is 20 W / m·K or lower. Having the thermal conductivity of the cured product within the above range allows for efficient cooling of the substrate containing the cured product.

[0061] In this specification, the thermal conductivity of a cured product of a thermosetting resin composition can be measured as follows. First, the thermosetting resin composition is applied to rolled copper foil using an 80-mesh polyester screen to a thickness of 75 μm, thereby printing a layer of the thermosetting resin composition. Then, it is left to stand in a hot air circulating box-type drying oven and heat-cured at 150°C for 60 minutes. After that, another layer of the thermosetting resin composition is applied using an 80-mesh polyester screen to a thickness of 75 μm, overlapping the first layer of cured product. Then, it is pre-cured in a hot air circulating box-type drying oven at 100°C for 60 minutes, followed by post-curing at 150°C for 90 minutes to form a cured product with a thickness of 150 μm. Next, the thermal diffusivity of the film-like cured product obtained by peeling off the rolled copper foil is measured using an FTC-1 manufactured by Advance Engineering Co., Ltd., under a load of 5 kgf / cm². ３ The specific heat capacity of the cured material is measured by periodic heating. The specific heat capacity of the cured material is measured using a Perkin-Elmer differential scanning calorimetry (DSC) with a heating rate of 20°C / min, a helium gas flow rate of 20 ml / min, and a sample volume of 15 mg. The specific gravity of the cured material is measured at room temperature (25°C) by water displacement. Based on the measured thermal diffusivity (α), specific heat capacity (c), and specific gravity (ρ) of the cured material, the thermal conductivity (λ) of the cured material is calculated using the following formula: Thermal conductivity (λ) = Thermal diffusivity (α) × Specific heat capacity (c) × Specific gravity (ρ)

[0062] The viscosity of the thermosetting resin composition of the present invention at 25°C is preferably 250 to 1000 dPa·s, more preferably 300 to 800 dPa·s, and particularly preferably 350 to 650 dPa·s, from the viewpoint of applicability in screen printing. The viscosity can be measured in accordance with JIS Z 8803:2011, item 10, "Method for measuring viscosity using a cone-plate rotational viscometer," at 25°C, 5 rpm, and 30 seconds, using a cone rotor of 3° × R9.7 and a cone-plate viscometer (Toki Sangyo Co., Ltd., TVE-33H).

[0063] The thermosetting resin composition of the present invention can be widely used, but is preferably used for forming a cured film on a substrate, more preferably for forming a permanent protective film, and even more preferably as a solder resist, interlayer insulating layer, coverlay, or hole-filling material. Among these uses, it is particularly preferred to use it as a hole-filling material, specifically as a hole-filling material for through-holes in a substrate, grooves in an inlay structure, and recesses.

[0064] 2. Cured product of thermosetting resin composition In one embodiment, a cured product of the thermosetting resin composition of the present invention is provided. In one embodiment, the cured product can be formed by applying the thermosetting resin composition to a substrate and then performing thermosetting while the substrate is placed horizontally.

[0065] The substrate is preferably a substrate having a wiring circuit (a substrate on which a circuit pattern is formed). Examples of substrates having a wiring circuit include printed circuit boards with circuits pre-formed using copper, flexible printed circuit boards, paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / nonwoven fabric epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, copper-clad laminates using fluororesin / polyethylene / polyphenylene ether, polyphenylene oxide / cyanate, etc., metal substrates, glass substrates, ceramic substrates, wafers, polyimide films, PET films, polyethylene naphthalate (PEN) films, and the like.

[0066] There are no particular limitations on the method for applying the thermosetting resin composition to the substrate, but examples include inkjet printing, dispenser printing, dip coating, flow coating, roll coating, bar coating, screen printing, and curtain coating. Among these, screen printing is preferred.

[0067] The thermosetting of the thermosetting resin composition can be performed by heating at a temperature of 130 to 200°C for 60 to 180 minutes, for example. In one preferred embodiment, the thermosetting of the thermosetting resin composition is performed by a step cure including pre-curing and post-curing. Specifically, after applying the thermosetting resin composition, it is heated at a temperature of 60 to 120°C (pre-curing) to reduce the apparent viscosity and promote defoaming leveling. Then, the cured product is formed by performing thermosetting at a temperature of 130 to 180°C. The pre-curing time can be, for example, 10 to 60 minutes, and the post-curing time can be 60 to 180 minutes.

[0068] The thermosetting (step curing) performed after applying the thermosetting resin composition according to the present invention can be carried out using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, or the like.

[0069] The cured product of the present invention has a thermal conductivity of 3.0 W / m·K or higher, preferably 3.2 W / m·K or higher, and more preferably 3.4 W / m·K or higher. The upper limit is not particularly limited, but for example, it is 20 W / m·K or lower. Because the thermal conductivity of the cured product is within the above range, the substrate equipped with the cured product can be efficiently cooled. The thermal conductivity of the cured product can be measured as described above.

[0070] The cured product of the present invention can be suitably used, for example, as a heat dissipation material for permanent hole filling in printed circuit boards, such as through-holes, grooves in inlay structures, and recesses. It can also be used as a solder resist, coverlay, or interlayer insulating layer for electronic components such as printed circuit boards.

[0071] <Substrate> In one embodiment, a substrate comprising a cured product of the thermosetting resin composition of the present invention is provided. Because the substrate of the present invention has good heat dissipation properties, it can be used in applications such as automobiles, ships, trains, robots, machine tools, factory power distribution boards, solar cells, and electronic components (LEDs, sensors, semiconductors, circuit boards, displays, home appliances, optical communication / optical circuits, optical recording, magnetic recording, etc.).

[0072] The present invention will be further described below with reference to examples, but the present invention is not limited thereto. In the examples, unless otherwise specified, "parts" and "%" all refer to mass.

[0073] <Materials Used> ・Thermosetting resin 1: ZX-1059 manufactured by Nippon Steel Chemical & Material Co., Ltd., a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin ・Thermosetting resin 2: jER630 manufactured by Mitsubishi Chemical Corporation, a para-aminophenol type liquid epoxy resin ・Thermosetting resin 3: jERYED216D manufactured by Mitsubishi Chemical Corporation, an alkyl diglycidyl ether ・Thermoconductive filler 1: Denka spherical alumina DAW-07 manufactured by Denka Co., Ltd. ・Thermoconductive filler 2: Denka spherical alumina DAW-03 manufactured by Denka Co., Ltd. ・Thermoconductive filler 3: Denka spherical alumina ASFP-20 manufactured by Denka Co., Ltd. ・Thermoconductive filler 4: Magnesium oxide RF-10CS-FC manufactured by Ube Materials Co., Ltd. ・Thermoconductive filler 5: Aluminum nitride AlNP300RWG manufactured by Through-Tech Applied Material Co., Ltd. • Hardener: Imidazole epoxy resin hardener Curazole 2MZA-PW manufactured by Shikoku Chemicals Co., Ltd. • Rheology modifier 1: Olben M (bentonite) manufactured by Shiraishi Industries Co., Ltd. • Rheology modifier 2: AEROSIL 200 (hydrophilic silica) manufactured by Nippon Aerosil Co., Ltd. • Rheology modifier 3: AEROSIL RY200 (hydrophobic silica) manufactured by Nippon Aerosil Co., Ltd. • Rheology modifier 4: Rheology modifier BYK-R606 manufactured by BIC Chemie Japan Co., Ltd. • Rheology modifier 5: Rheology modifier BYK-410 manufactured by BIC Chemie Japan Co., Ltd. • Rheology modifier 6: Rheology modifier BYK-7410CA manufactured by BIC Chemie Japan Co., Ltd. • Wetting and dispersing agent 1: Wetting and dispersing agent BYK-111 manufactured by BIC Chemie Japan Co., Ltd. • Wetting and dispersing agent 2: Wetting and dispersing agent BYK-W9010 manufactured by BIC Chemie Japan Co., Ltd. • Wetting and dispersing agent 3: BYK-W9011, manufactured by BIC Chemie Japan Co., Ltd. • Wetting and dispersing agent 4: BYK-W9012, manufactured by BIC Chemie Japan Co., Ltd. • Adhesion enhancer: KBM-403 silane coupling agent (chemical name: 3-glycidoxypropyltrimethoxysilane), manufactured by Shin-Etsu Chemical Co., Ltd. • Antifoaming agent: KS-66 oil compound type antifoaming agent, manufactured by Shin-Etsu Chemical Co., Ltd.

[0074] <Example 1> The components shown in Table 1 were mixed in the amounts shown in Table 1, pre-mixed using a stirrer, and then kneaded using a three-roll mill to prepare a thermosetting resin composition. The following evaluations were performed on the prepared thermosetting resin composition. The results are shown in Table 1.

[0075] <Shear stress measurement> The measurement was performed using a HAAKE RS6000 rheometer manufactured by Thermo Fisher Scientific Co., Ltd. as follows.

[0076] 1. Shear stress (A) (i) A φ20 mm sensor parallel plate was attached to the apparatus as a rotor, and the temperature was maintained at 25.0°C. (ii) 0.3 mL of thermosetting resin composition was weighed out and placed on the sensor parallel plate, and the gap between the plates was maintained at 0.5 mm. (iii) In rotation mode, the parallel plate was sheared for 60 seconds at a shear rate of 0 s －１ From 300s －１ After rotating it to that point, 300s －１ (iv) Then, the shear rate was increased to 300 s over 60 seconds. －１ from 0s －１ Shear rate when rotation is changed to 150 s －１ The shear stress was measured at that time. (v) The above operations (i) to (iv) were repeated three times, and the average value of the shear stress was calculated and defined as shear stress (A).

[0077] 2. Shear stress (B) (i) A φ20 mm sensor parallel plate was attached to the apparatus as a rotor, and the temperature was maintained at 25.0°C. (ii) 0.3 mL of thermosetting resin composition was weighed out and placed on the sensor parallel plate, and the gap between the plates was maintained at 0.5 mm. (iii) In rotation mode, the parallel plate was sheared for 60 seconds at a shear rate of 0 s －１ From 300s －１ After rotating it to that point, 300s －１ The device was held for 60 seconds, and the shear stress was measured. (iv) The above operations (i) to (iii) were repeated three times, and the average value of the shear stress was calculated and defined as shear stress (B).

[0078] <Bleed Evaluation After Embedding> Paste was embedded into a φ11.5 mm copper inlay groove (groove width 150 μm) penetrating a 1.9 mm thick FR-4 substrate using an 80-mesh polyester screen plate with a copper inlay groove pattern. The process involved a clearance of 3 mm, a squeegee pressure of 5 kgf, and a printing speed of 80 mm / sec. The substrate was left flat at room temperature (25°C) for 30 minutes, after which paste was again embedded into the copper inlay groove from the front of the substrate under the same conditions. The substrate was then heat-treated in a hot air circulating drying oven at 100°C for 60 minutes, followed by a heat-curing treatment at 150°C for 90 minutes. After the heat-curing treatment, the back surface of the substrate was observed to check for any sagging or bleeding of the paste. Pass: No sagging or bleeding. Fail: Sagging or bleeding present.

[0079] <Pattern Formation> A pattern was formed on a copper-based FR-4 substrate using an 80-mesh polyester screen plate with an L / S = 1 / 1 mm pattern, at a clearance of 3 mm, a squeegee pressure of 5 kgf, and a printing speed of 80 mm / sec. The substrate was left flat at room temperature (25°C) for 30 minutes. After that, the substrate was heat-treated in a hot air circulating drying oven at 100°C for 60 minutes, and then the temperature was increased to 150°C for 90 minutes for thermosetting treatment. The pattern formation was observed at 100x magnification using a Keyence Corporation VHX-8000 optical microscope. Pass: Good straightness Fail: Poor straightness

[0080] <Thermal Conductivity> A thermosetting resin composition was applied to rolled copper foil using an 80-mesh polyester screen to form a layer of thermosetting resin composition with a film thickness of 75 μm. This layer was then placed in a hot air circulating box-type drying oven and heat-cured at 150°C for 60 minutes. Subsequently, a coating film was printed on top of the cured material using an 80-mesh polyester screen to form a layer of coating film with a film thickness of 75 μm. This coating film was then pre-cured in a hot air circulating box-type drying oven at 100°C for 60 minutes, followed by post-curing at 150°C for 90 minutes to form a cured coating film with a thickness of 150 μm. Next, the thermal diffusivity of the film-like cured material obtained by peeling off the rolled copper foil was measured using an FTC-1 manufactured by Advance Riko Co., Ltd., under a load of 5 kgf / cm³ by the periodic heating method. Furthermore, the specific heat capacity of the cured material was measured using a Perkin-Elmer differential scanning calorimetry (DSC) with a heating rate of 20°C / min, a helium gas flow rate of 20 ml / min, and a sample volume of 15 mg. The specific gravity of the cured material was also measured at room temperature (25°C) using the water displacement method. Based on the measured thermal diffusivity (α), specific heat capacity (c), and specific gravity (ρ) of the cured material, the thermal conductivity (λ) was calculated using the following formula: Thermal conductivity (λ) = Thermal diffusivity (α) × Specific heat capacity (c) × Specific gravity (ρ)

[0081] <Examples 2-8, Comparative Examples 1-7> Thermosetting resin compositions were prepared in the same manner as in Example 1, except that the composition was changed as shown in Tables 1 and 2. Evaluation was then performed in the same manner as in Example 1. The results are shown in Table 1.

[0082]

[0083] The thermosetting resin compositions of Examples 1 to 8 showed no bleeding after embedding, good pattern formation, and good thermal conductivity. Due to the good pattern formation, it is considered that they also have good embedding properties in through-holes and recesses. On the other hand, the thermosetting resin compositions of Comparative Examples 1 to 7 were outside the scope of the present invention and therefore performed inferiorly to the present invention in at least one of the following aspects.

Claims

1. A thermosetting resin composition comprising a thermosetting resin, a thermally conductive filler, a curing agent, and an additive, wherein the shear rate is 0 s at a temperature of 25°C using a rheometer. －１ From 300s －１ After increasing it to 300s －１ Hold for 1 minute, then 300 seconds －１ From 150s －１ When reduced to 150s －１ A thermosetting resin composition wherein the shear stress of the thermosetting resin composition is 1000 Pa or more, and the thermal conductivity of the cured product of the thermosetting resin composition is 3.0 W / m·K or more.

2. The thermosetting resin composition according to claim 1, wherein the additive comprises a rheology modifier and a wetting dispersant.

3. The thermosetting resin composition according to claim 2, wherein the rheology modifier comprises an inorganic rheology modifier and an organic rheology modifier.

4. The thermosetting resin composition according to claim 1, wherein the thermal conductivity of the thermal conductive filler is 20 W / m·K or higher.

5. The thermosetting resin composition according to claim 1, wherein the content of the thermally conductive filler in the thermosetting resin composition is 75 to 95 parts by mass per 100 parts by mass of the thermosetting resin composition, on a solid content basis.

6. A cured product of the thermosetting resin composition according to claim 1.

7. A substrate comprising the cured product described in claim 6.

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