Insulating resin sheet, multilayer body and semiconductor device

Abstract

An insulating resin sheet according to the present invention is formed from a curable resin composition that contains a thermosetting resin, a curing agent and an insulating heat-dissipating filler having a thermal conductivity of 10 W / m·K or more, wherein: the curing agent is composed of an imide oligomer; the thermal decomposition temperature of a cured product of this insulating resin sheet is 280°C or more; and the thickness of this insulating resin sheet is from 50 μm to 500 μm.　The present invention is able to provide an insulating resin sheet which has excellent insulating properties, excellent thermal conductivity and high heat resistance, while being less susceptible to warping if used as a substrate.

Description

Insulating resin sheet, laminate, and semiconductor device

[0001] The present invention relates to an insulating resin sheet, a laminate including the insulating resin sheet, and a semiconductor device including the laminate.

[0002] Conventionally, power modules have been used in a wide range of fields, such as industrial equipment, household electrical appliances, and information terminals. Attempts have been made to use resin sheets as substrates in power modules, and power modules using resin sheets are expected to be used in, for example, high-voltage applications. Such resin sheets are generally required to have excellent insulating properties and thermal conductivity.

[0003] Patent Document 1 describes an invention relating to an insulating sheet that includes a resin composition layer, has a higher dielectric constant on one side than on the other side, has a circuit pattern formed on one side, and contains plate-like inorganic particles with a thermal conductivity of 10 W / m K or more. The insulating sheet is shown to have excellent thermal conductivity and insulation properties.

[0004] Patent Document 2 describes an invention relating to a method for manufacturing an insulating sheet, which involves laminating two resin sheets containing an aggregate containing boron nitride and an epoxy resin and hot pressing them to form an insulating layer, and which is characterized by adjusting the relationship between the thickness before and after hot pressing and the viscosity at 175° C. to specific ranges. It is shown that this manufacturing method can produce an insulating sheet with excellent thermal conductivity and insulation properties.

[0005] Patent Document 3 describes an invention relating to a thermally conductive adhesive composition containing a polyamideimide oligomer, a thermal crosslinking agent that crosslinks the oligomers, and thermally conductive inorganic particles including boron nitride particles, wherein the number average molecular weight of the polyamideimide oligomer, the content of the thermal crosslinking agent, and the content of the thermally conductive inorganic particles are within specific ranges. The thermally conductive adhesive composition is shown to have excellent thermal conductivity, adhesion, and heat resistance.

[0006] Patent Document 4 describes an invention relating to a curable resin composition containing a curable resin, an imide oligomer, and boehmite-type aluminum hydroxide. The curable resin composition is shown to have excellent flame retardancy, adhesiveness, high-temperature long-term heat resistance, and moisture absorption reflow resistance, and also has a low environmental impact.

[0007] Japanese Patent No. 6844066 Japanese Patent No. 6214336 JP 2017-149910 A International Publication No. 2019 / 083006

[0008] In recent years, particularly in automotive power devices, resin sheets used as substrates are required to have high heat resistance and little warping when used as a substrate, in addition to electrical insulation and thermal conductivity. The conventional resin sheets described above are insufficient in terms of improving heat resistance and suppressing warping while maintaining good electrical insulation and thermal conductivity, and therefore a resin sheet with a better balance of physical properties is needed. Therefore, the present invention aims to provide an insulating resin sheet that has excellent electrical insulation and thermal conductivity, high heat resistance, and little warping when used as a substrate.

[0009] The present inventors have conducted extensive research to achieve the above-mentioned object. As a result, they have discovered that the above-mentioned problems can be solved by an insulating resin sheet containing a thermosetting resin, a curing agent, and an insulating and heat-dissipating filler having a thermal conductivity of 10 W / m K or more, in which an imide oligomer is used as the curing agent, the thermal decomposition temperature of the cured product is set to a certain level or higher, and the thickness is within a specific range, and have completed the present invention. That is, the present invention relates to the following [1] to

[10] .

[0010] [1] An insulating resin sheet made of a curable resin composition containing a thermosetting resin, a curing agent, and an insulating and heat-dissipating filler having a thermal conductivity of 10 W / m·K or more, wherein the curing agent is an imide oligomer, the thermal decomposition temperature of the cured product is 280°C or more, and the thickness is 50 μm or more and 500 μm or less. [2] The insulating resin sheet according to [1] above, wherein the insulating and heat-dissipating filler is contained in an amount of 50% by volume or more. [3] The insulating resin sheet according to [1] or [2] above, wherein the imide oligomer has reactive functional groups at both ends or one end of the molecule that can react with the thermosetting resin, the reactive functional groups being acid anhydride groups, amine groups, or hydroxyl groups. [4] The insulating resin sheet according to any one of [1] to [3] above, wherein the higher of the softening point and melting point of the thermosetting resin is 150°C or less. [5] The insulating resin sheet according to any one of [1] to [4] above, wherein the imide oligomer does not have a linear saturated hydrocarbon chain having 16 or more carbon atoms in its skeleton. [6] The insulating resin sheet according to any one of [1] to [5] above, wherein the molecular weight of the imide oligomer is 500 to 10,000. [7] A laminate comprising the insulating resin sheet according to any one of [1] to [6] above, a metal base plate, and a metal plate, the insulating resin sheet and the metal plate being disposed in this order on the metal base plate. [8] The laminate according to [7] above, wherein the laminate is a circuit board. [9] The laminate according to [7] or [8] above, wherein the metal plate has a circuit pattern.

[10] A semiconductor device comprising the laminate according to any one of [7] to [9] above, and a semiconductor element provided on the metal plate.

[0011] According to the present invention, it is possible to provide an insulating resin sheet that has excellent insulating properties and thermal conductivity, high heat resistance, and is less likely to warp when used as a substrate.

[0012] 1 is a schematic cross-sectional view showing a stacked body according to an embodiment of the present invention; 2 is a schematic cross-sectional view showing a semiconductor device according to an embodiment of the present invention;

[0013] <Insulating Resin Sheet> An insulating resin sheet made of a curable resin composition containing a thermosetting resin, a curing agent, and an insulating and heat-dissipating filler having a thermal conductivity of 10 W / m·K or more, wherein the curing agent is an imide oligomer, the thermal decomposition temperature of the cured product is 280°C or more, and the thickness is 50 μm or more and 500 μm or less. The insulating resin sheet of the present invention is formed from a thermosetting resin, a curing agent, and a curable resin composition having a thermal conductivity of 10 W / m·K or more. The insulating resin sheet may be the curable resin composition itself (i.e., an uncured curable resin composition) or a cured curable resin composition. In other words, the insulating resin sheet of the present invention may be an insulating resin sheet before curing or may be an insulating resin sheet after curing (including a partially cured insulating resin sheet).

[0014] [Thermal decomposition temperature] The insulating resin sheet of the present invention has a thermal decomposition temperature of 280°C or higher when cured. If the thermal decomposition temperature is lower than 280°C, the heat resistance of the cured insulating resin sheet will be poor. From the viewpoint of improving the heat resistance of the insulating resin sheet, the thermal decomposition temperature is preferably 290°C or higher, and more preferably 300°C or higher. The higher the thermal decomposition temperature, the better, but it is usually 550°C or lower. The thermal decomposition temperature of the cured product refers to the thermal decomposition temperature of the insulating resin sheet after a certain heat treatment, as described below. The thermal decomposition temperature can be adjusted to a desired value by adjusting the type and amount of the curing agent, the type of thermosetting resin, etc., as described below.

[0015] In the present invention, the thermal decomposition temperature refers to the temperature at which a weight loss of 1% occurs in thermogravimetric analysis compared to the weight of the insulating resin sheet before measurement. Thermogravimetric analysis is performed using 10 mg of insulating resin sheet as a sample under conditions of a nitrogen flow rate of 100 ml / min, starting at 30°C, heating at a rate of 10°C / min to 550°C, and holding for 5 minutes. The insulating resin sheet used for thermogravimetric analysis is heat-treated at 150°C for 60 minutes.

[0016] [Glass transition temperature] The insulating resin sheet of the present invention preferably has a glass transition temperature of 150°C or higher when cured. A glass transition temperature of 150°C or higher improves the heat resistance of the insulating resin sheet after curing. The glass transition temperature of the insulating resin sheet is more preferably 160°C or higher, and even more preferably 170°C or higher. The glass transition temperature in the present invention refers to the peak temperature of the tan δ curve obtained when the temperature is raised from 0°C to 300°C at a heating rate of 10°C / min and a frequency of 10 Hz in a dynamic viscoelasticity measuring device. The insulating resin sheet used in the dynamic viscoelasticity measurement is heat-treated at 150°C for 60 minutes.

[0017] [Thermosetting Resin] The thermosetting resin contained in the curable resin composition of the present invention is not particularly limited, and examples thereof include amino resins such as urea resins and melamine resins, phenolic resins, thermosetting urethane resins, epoxy resins, phenoxy resins, thermosetting polyimide resins, and aminoalkyd resins. The thermosetting resin used in the insulating resin sheet may be used alone or in combination of two or more. Among the above, epoxy resins are preferred as the thermosetting resin.

[0018] Examples of epoxy resins include compounds containing two or more epoxy groups in the molecule. The epoxy resin has, for example, a weight-average molecular weight of less than 5,000. Specific examples of epoxy resins include styrene skeleton-containing epoxy resins, bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, phenol novolac epoxy resins, biphenol epoxy resins, naphthalene epoxy resins, biphenyl epoxy resins, fluorene epoxy resins, phenol aralkyl epoxy resins, naphthol aralkyl epoxy resins, dicyclopentadiene epoxy resins, anthracene epoxy resins, epoxy resins having an adamantane skeleton, epoxy resins having a tricyclodecane skeleton, epoxy resins having a triazine nucleus in the skeleton, and glycidylamine epoxy resins.

[0019] The epoxy equivalent of the epoxy resin is not particularly limited, but is, for example, 80 g / eq or more and 500 g / eq or less, preferably 90 g / eq or more and 400 g / eq or less, and more preferably 90 g / eq or more and 350 g / eq or less. The epoxy equivalent can be measured, for example, according to the method specified in JIS K 7236. The above-mentioned epoxy resins may be used alone or in combination of two or more.

[0020] The softening point and melting point of the thermosetting resin are not particularly limited, but from the viewpoint of ease of production of the insulating resin sheet, the higher of the softening point and the melting point is preferably 150°C or less, more preferably 145°C or less, more preferably 130°C or less, and even more preferably 100°C or less. In this specification, the softening point is a value measured by the softening point test method (ring and ball method) specified in JIS K 7234. The melting point is a value measured as the temperature of the endothermic peak when the temperature is raised at 10°C / min with a differential scanning calorimeter. Examples of the differential scanning calorimeter include the EXTEAR DSC6100 (manufactured by SII NanoTechnology Inc.).

[0021] The content of the thermosetting resin in the curable resin composition is not particularly limited, but is preferably 10% by volume or more and 40% by volume or less, more preferably 12% by volume or more and 35% by volume or less, and even more preferably 15% by volume or more and 30% by volume or less. When the content of the thermosetting resin is equal to or greater than these lower limits, the insulating and heat-dissipating filler can be sufficiently bound after curing, thereby obtaining an insulating resin sheet of the desired shape. When the content of the thermosetting resin is equal to or less than these upper limits, a certain amount or more of the insulating and heat-dissipating filler can be contained, thereby achieving good insulation and excellent thermal conductivity. The content of the thermosetting resin in the curable resin composition is the same as the content of the thermosetting resin in the insulating resin sheet.

[0022] [Imide Oligomer] The curable resin composition of the present invention contains an imide oligomer as a curing agent. The inclusion of an imide oligomer improves the heat resistance of the insulating resin sheet and suppresses warpage of the substrate. While the reason for this is unclear, compounds capable of forming polymers, such as cyanate and polyimide amide resins, react with thermosetting resins such as epoxy resins after forming the polymer, resulting in a high free volume, which can lead to uneven crosslinking. On the other hand, imide oligomers do not form trimers, and therefore do not have a high free volume like cyanate, thereby suppressing uneven crosslinking. It is presumed that the use of an imide oligomer facilitates uniform reaction with the thermosetting resin, making uneven crosslinking less likely to occur.

[0023] The imide oligomer in the present invention is a compound having an imide skeleton in its main chain, and is preferably a compound having an aromatic ring in its skeleton. By having an aromatic ring in its skeleton, thermal decomposition of the insulating resin sheet becomes less likely to occur, and heat resistance is likely to be improved. Furthermore, from the viewpoint of improving heat resistance, it is preferable that the imide oligomer does not have a linear saturated hydrocarbon chain having 16 or more carbon atoms in its skeleton.

[0024] The imide oligomer of the present invention has reactive functional groups at both or one end of the molecule that can react with the thermosetting resin, and the reactive functional groups are preferably acid anhydride groups, amine groups, or hydroxyl groups. The amine groups are not particularly limited and may be primary amino groups, secondary amino groups, or tertiary amino groups. The hydroxyl groups may be phenolic hydroxyl groups or hydroxyl groups other than phenolic hydroxyl groups. By using an imide oligomer having such reactive functional groups, the heat resistance of the insulating resin sheet is easily improved and warping is easily suppressed. From the viewpoints of storage stability and heat resistance, the reactive functional groups of the imide oligomer are more preferably acid anhydride groups or phenolic hydroxyl groups.

[0025] The molecular weight of the imide oligomer is preferably 500 to 10,000. When the molecular weight is within this range, the heat resistance of the insulating resin sheet is likely to be improved and warping is likely to be suppressed. The molecular weight of the imide oligomer is more preferably 700 to 7,000, and even more preferably 900 to 5,000. The molecular weight of the imide oligomer is preferably 500 or more, more preferably 700 or more, even more preferably 900 or more, and preferably 10,000 or less, more preferably 7,000 or less, and even more preferably 5,000 or less. The molecular weight is the number average molecular weight measured by gel permeation chromatography (GPC) and calculated in terms of polystyrene. Examples of columns used when measuring the number average molecular weight in terms of polystyrene by GPC include the JAIGEL-2H-A (manufactured by Japan Analytical Industry Co., Ltd.). Specifically, the measurement can be performed using tetrahydrofuran as a solvent at room temperature and a flow rate of 1 mL / min. The solvent is not particularly limited as long as it dissolves the sample to be measured, and the flow rate can be selected according to the column and the device.

[0026] The imide oligomer in the present invention may, for example, be an imide oligomer having a segment derived from an acid dianhydride represented by the following formula (1) and a segment derived from a polyamine compound. In this case, it is preferable that the segment derived from the acid dianhydride represented by formula (1) is present at an end of the main chain, and more preferably at both ends of the main chain. Furthermore, examples of the polyamine compound include aromatic diamine compounds, aliphatic diamine compounds, and aliphatic triamine compounds.

[0027] In formula (1), A is a tetravalent group represented by the following formula (3-1) or (3-2).

[0028] In formulas (3-1) and (3-2), * represents a bonding position, and in formula (3-1), Z represents a bond, an oxygen atom, a carbonyl group, a sulfur atom, a sulfonyl group, a linear or branched divalent hydrocarbon group which may have an oxygen atom at the bonding position, or a divalent group having an aromatic ring which may have an oxygen atom at the bonding position. The hydrogen atoms of the aromatic rings in formulas (3-1) and (3-2) may be substituted.

[0029] Examples of the acid dianhydride represented by the above formula (1) include pyromellitic dianhydride, 3,3'-oxydiphthalic dianhydride, 3,4'-oxydiphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 4,4'-bis(3,4-dicarboxylphenoxy)diphenyl ether, p-phenylenebis(trimellitate anhydride), 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 4,4'-carbonyldiphthalic dianhydride. Among these, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 3,4'-oxydiphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, and 4,4'-carbonyldiphthalic dianhydride are preferred because they are excellent in control of the softening point and solubility of the imide oligomer, heat resistance, and availability, and of these, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride is more preferred.

[0030] The polyamine compound may be an aromatic polyamine compound or an aliphatic polyamine compound, and among these, an aromatic polyamine compound is preferred. By using an imide oligomer having a segment derived from an aromatic polyamine compound, an insulating resin sheet having excellent heat resistance can be easily obtained.

[0031] The aromatic polyamine compound is preferably an aromatic diamine compound represented by the following formula (2). In formula (2), B is a divalent group represented by the following formula (4-1) or (4-2), and R １ ~R ４are each independently a hydrogen atom or a monovalent hydrocarbon group.

[0032] In formula (4-1) and formula (4-2), * represents a bonding position, and in formula (4-1), Y represents a bond, an oxygen atom, a carbonyl group, a sulfur atom, a sulfonyl group, a linear or branched divalent hydrocarbon group which may have an oxygen atom at the bonding position, or a divalent group having an aromatic ring which may have an oxygen atom at the bonding position. In formula (4-1) and formula (4-2), some or all of the hydrogen atoms of the phenylene group may be substituted with hydroxyl groups or monovalent hydrocarbon groups.

[0033] Examples of the aromatic diamine compound represented by formula (2) include 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 1,2-phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, bis(4-(4-aminophenoxy)phenyl)sulfone, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, bis(4-(4-amino

[0033] Examples of the bis(4-aminophenoxy)phenyl)methane include 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene, 1,4-bis(2-(4-aminophenyl)-2-propyl)benzene, 3,3'-diamino-4,4'-dihydroxyphenylmethane, 4,4'-diamino-3,3'-dihydroxyphenylmethane, 3,3'-diamino-4,4'-dihydroxyphenyl ether, bisaminophenylfluorene, bistruidinefluorene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diamino-3,3'-dihydroxyphenyl ether, 3,3'-diamino-4,4'-dihydroxybiphenyl, 4,4'-diamino-2,2'-dihydroxybiphenyl, and 3,3'-dihydroxybenzidine.Among these, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 1,2-phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, bis(4-(3-aminophenoxy)phenyl)sulfone, bis(4-(4-aminophenoxy)phenyl)sulfone, 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(2-(4-aminophenyl)-2-propyl)benzene, and 3,3'-dihydroxybenzidine are preferred, and 1,3-bis(3-aminophenoxy)benzene is more preferred, due to their excellent controllability of the softening point and solubility of the imide oligomer, heat resistance, and availability.

[0034] Examples of the aliphatic polyamine compound include aliphatic diamine compounds, aliphatic triamine compounds, etc. Examples of the aliphatic diamine compound and the aliphatic triamine compound include dimer diamine, hydrogenated dimer diamine, trimer triamine, hydrogenated trimer triamine, 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,14-tetradecanediamine, 1,16-hexadecanediamine, 1,18-octadecanediamine, 1,20-eicosanediamine, 2-methyl-1,8-octanediamine, 2-methyl-1,9-nonanediamine, 2,7 dimethyl-1,8-octanediamine, 3,3'-diamino-N-methyldipropylamine, 3,3'-diaminodipropylamine, diethylenetriamine, bis(hexamethylene)triamine, 2,2'-bis(methylamino)-N-methyldiethylamine, 2,2'-oxybis(ethylamine), 3,3'-oxybis(propylamine), 1,2-bis(2-aminoethoxy)ethane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, cyclohexanediamine, methylcyclohexanediamine, isophoronediamine, etc. Commercially available aliphatic diamine compounds and aliphatic triamine compounds include, for example, Versamine 551 and Versamine 552 manufactured by BASF, and Priamine 1071, Priamine 1073, Priamine 1074, and Priamine 1075 manufactured by Croda.

[0035] Examples of a method for producing an imide oligomer having an acid anhydride group as a reactive functional group include a method of reacting an acid dianhydride represented by the above formula (1) with a polyamine compound such as the above aromatic diamine compound, aliphatic diamine compound, or aliphatic triamine compound.

[0036] A specific example of a method for reacting the acid dianhydride represented by formula (1) with a polyamine compound is shown below. First, the polyamine compound is dissolved in a solvent (e.g., N-methylpyrrolidone, dimethylformamide, dimethylacetamide, etc.) in which the amic acid oligomer obtained by the reaction is soluble. The acid dianhydride represented by formula (1) is then added to the resulting solution and reacted to obtain an amic acid oligomer solution. The amic acid oligomer is then recovered by removing the solvent from the resulting amic acid oligomer solution by heating or reducing pressure, or by reprecipitation in a poor solvent such as water, methanol, or hexane. The amic acid oligomer is then further heated at about 200°C or higher for at least one hour to allow the imidization reaction to proceed. By adjusting the molar ratio of the acid dianhydride represented by formula (1) to the polyamine and the imidization conditions, an imide oligomer having a desired number-average molecular weight and acid anhydride groups as reactive functional groups at both ends can be obtained.

[0037] The imide oligomer of the present invention may be an imide oligomer having a segment derived from the acid dianhydride represented by the above formula (1) and a segment derived from a phenolic hydroxyl group-containing monoamine represented by the following formula (5). Furthermore, the imide oligomer of the present invention may be an imide oligomer having a segment derived from the acid dianhydride represented by the above formula (1), a segment derived from the above polyamine compound, and a segment derived from a phenolic hydroxyl group-containing monoamine represented by the following formula (5). In this case, it is preferable that the segment derived from the phenolic hydroxyl group-containing monoamine represented by the following formula (5) be present at an end of the main chain, and more preferably at both ends of the main chain.

[0038] In formula (5), Ar is an optionally substituted divalent aromatic group, and R ５ and R ６ are each independently a hydrogen atom or a monovalent hydrocarbon group.

[0039] Examples of the phenolic hydroxyl group-containing monoamine represented by the above formula (5) include 3-aminophenol, 4-aminophenol, 4-amino-o-cresol, 5-amino-o-cresol, 4-amino-2,3-xylenol, 4-amino-2,5-xylenol, 4-amino-2,6-xylenol, 4-amino-1-naphthol, 5-amino-2-naphthol, 6-amino-1-naphthol, 4-amino-2,6-diphenylphenol, etc. Among these, 3-aminophenol, 4-aminophenol, 4-amino-o-cresol, and 5-amino-o-cresol are preferred because they are easily available and have excellent storage stability and can give cured products having high glass transition temperatures.

[0040] Examples of methods for producing an imide oligomer having a hydroxyl group as a reactive functional group include the following: a method of reacting an acid dianhydride represented by the above formula (1) with a phenolic hydroxyl group-containing monoamine represented by the above formula (5), and a method of reacting an acid dianhydride represented by the above formula (1) with the above polyamine compound, and then further reacting the resulting mixture with a phenolic hydroxyl group-containing monoamine represented by the above formula (5).

[0041] A specific example of a method for reacting the acid dianhydride represented by formula (1) with the phenolic hydroxyl group-containing monoamine represented by formula (5) is shown below. First, the phenolic hydroxyl group-containing monoamine represented by formula (5) is dissolved in a solvent (e.g., N-methylpyrrolidone, dimethylformamide, dimethylacetamide, etc.) in which the amic acid oligomer obtained by the reaction is soluble. The acid dianhydride represented by formula (1) is then added to the resulting solution and reacted to obtain an amic acid oligomer solution. Next, the solvent is removed from the resulting amic acid oligomer solution by heating or reducing pressure, or the amic acid oligomer is recovered by reprecipitation in a poor solvent such as water, methanol, or hexane, and the amic acid oligomer is then recovered. The amic acid oligomer is then further heated at about 200°C or higher for at least 1 hour to allow the imidization reaction to proceed. By adjusting the molar ratio of the acid dianhydride represented by the above formula (1) to the phenolic hydroxyl group-containing monoamine represented by the above formula (5) and the imidization conditions, it is possible to obtain an imide oligomer having a desired number average molecular weight and having phenolic hydroxyl groups at both ends as reactive functional groups.

[0042] A specific example of a method for reacting the acid dianhydride represented by formula (1) with a polyamine compound and then further reacting it with a phenolic hydroxyl group-containing monoamine represented by formula (5) is shown below. First, the polyamine compound is dissolved in a solvent (e.g., N-methylpyrrolidone, dimethylformamide, dimethylacetamide, etc.) in which the amic acid oligomer obtained by the reaction is soluble. The acid dianhydride represented by formula (1) is added to the resulting solution and reacted to obtain a solution of amic acid oligomer (A) having acid anhydride groups at both ends. The solvent is then removed from the resulting amic acid oligomer (A) solution by heating or reducing pressure, or the amic acid oligomer (A) is recovered by reprecipitation in a poor solvent such as water, methanol, or hexane, and the amic acid oligomer (A) is then recovered. The amic acid oligomer (A) is then further heated at about 200°C or higher for at least 1 hour to allow the imidization reaction to proceed. The imide oligomer thus obtained, having acid anhydride groups as reactive functional groups at both ends, is again dissolved in a solvent (e.g., N-methylpyrrolidone, dimethylformamide, dimethylacetamide, etc.), and a phenolic hydroxyl-containing monoamine represented by formula (5) is added and reacted to obtain a solution of amic acid oligomer (B). The solvent is removed from the resulting amic acid oligomer (B) solution by heating or reducing pressure, or the amic acid oligomer (B) is recovered by reprecipitation in a poor solvent such as water, methanol, or hexane, and the solution is then heated at about 200°C or higher for at least 1 hour to allow the imidization reaction to proceed. By adjusting the molar ratio of the acid dianhydride represented by formula (1), the polyamine compound, and the phenolic hydroxyl-containing monoamine represented by formula (5), as well as the imidization conditions, an imide oligomer having a desired number-average molecular weight and having hydroxyl groups as reactive functional groups at both ends can be obtained.

[0043] The method for producing an imide oligomer having an amine group as a reactive functional group is not particularly limited, and examples thereof include a method in which an imide oligomer having an acid anhydride group at a terminal is obtained by the above-mentioned method and the imide oligomer is reacted with a polyamine compound (e.g., an aromatic diamine compound). Another method includes a method in which, when producing an imide oligomer by the above-mentioned method, the acid anhydride and the polyamine compound are adjusted to an appropriate molar ratio.

[0044] The imidization rate of the imide oligomer is preferably 70% or more. When the imidization rate is 70% or more, an insulating resin sheet having superior heat resistance can be obtained. The imidization rate is more preferably 75% or more, and even more preferably 80% or more. There is no particular preferred upper limit to the imidization rate of the imide oligomer, but the practical upper limit is 98%. The "imidization rate" can be determined by Fourier transform infrared spectroscopy (FT-IR). Specifically, measurement is performed by the attenuated total reflection method (ATR method) using a Fourier transform infrared spectrophotometer, and the 1660 cm －１ The imidization rate can be calculated from the peak absorbance area near the peak absorbance area using the following formula. An example of the Fourier transform infrared spectrophotometer is the UMA600 (manufactured by Agilent Technologies). In the following formula, the "peak absorbance area of ​​the amic acid oligomer" refers to the absorbance area of ​​the amic acid oligomer obtained by removing the solvent without performing the imidization step in each of the methods for producing the imide oligomer described above. The solvent can be removed by evaporation. Imidization rate (%) = 100 × (1 - (peak absorbance area after imidization) / (peak absorbance area of ​​the amic acid oligomer)). Here, the "imidization rate" refers to the actual reaction amount relative to the theoretical reaction amount in the reaction of an acid anhydride group with an amine group to form an imide group.

[0045] The content of the imide oligomer in the curable resin composition of the present invention is not particularly limited, but is preferably 10% by volume or more, more preferably 15% by volume or more, even more preferably 20% by volume or more, and preferably 50% by volume or less, more preferably 40% by volume or less, and even more preferably 30% by volume or less. When the content of the imide oligomer is within this range, the heat resistance of the insulating resin sheet is improved and the occurrence of warping is easily suppressed. Note that the content of the imide oligomer in the curable resin composition is the same as the content of the imide oligomer in the insulating resin sheet.

[0046] A curing agent other than the imide oligomer described above may be used in combination with the imide oligomer, as long as it does not impair the effects of the present invention. The content of the imide oligomer in the total amount of curing agent is preferably 5 to 100% by mass, more preferably 20 to 100% by mass, and even more preferably 40 to 100% by mass. When the amount of the imide oligomer is equal to or greater than the above lower limit, warping is more likely to be suppressed and heat resistance is more likely to be improved. Examples of curing agents other than the imide oligomer include cyanate ester compounds (cyanate ester curing agents), amine compounds (amine curing agents), thiol compounds (thiol curing agents), phosphine compounds, dicyandiamide, phenolic compounds (phenolic curing agents), acid anhydrides, active ester compounds, carbodiimide compounds (carbodiimide curing agents), and benzoxazine compounds (benzoxazine curing agents).

[0047] [Insulating heat-dissipating filler] The curable resin composition contains an insulating heat-dissipating filler having a thermal conductivity of 10 W / m·K or more. The inclusion of this insulating heat-dissipating filler improves the thermal conductivity and insulating properties of the insulating resin sheet. Furthermore, the inclusion of the insulating heat-dissipating filler can suppress warping of the insulating resin sheet. This is presumably because the insulating heat-dissipating filler improves heat dissipation and makes it easier for heat to be distributed uniformly within the sheet, thereby preventing uneven crosslinking of the thermosetting resin.

[0048] The thermal conductivity of the insulating and heat-dissipating filler is preferably 15 W / m K or more, more preferably 20 W / m K or more. There is no particular upper limit to the thermal conductivity of the insulating and heat-dissipating filler, but it may be, for example, 300 W / m K or less, or 250 W / m K or less. The thermal conductivity of the insulating and heat-dissipating filler can be measured, for example, by a cyclic heating thermoreflectance method using a thermal microscope manufactured by Bethel Co., Ltd., on a cross section of the filler machined with a cross-section polisher.

[0049] The average particle size of the insulating and heat-dissipating filler is not particularly limited, but is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. It is also preferably 100 μm or less, more preferably 60 μm or less, and even more preferably 40 μm or less. The average particle size of the insulating and heat-dissipating filler is determined by exposing a cross section of the cured insulating resin sheet, observing the exposed cross section with a scanning electron microscope (SEM), obtaining an observation image, measuring the major axis of 200 randomly selected primary particles of the insulating and heat-dissipating filler, and averaging the measurements to determine the average particle size.

[0050] Examples of insulating heat-dissipating fillers include inorganic fillers such as alumina, aluminum nitride, boron nitride, magnesium oxide, diamond, and silicon carbide. By using these insulating heat-dissipating fillers, the insulation required for the insulating resin sheet can be ensured and thermal conductivity can also be improved. The insulating heat-dissipating fillers may be used alone or in combination of two or more. Among the insulating heat-dissipating fillers listed above, alumina, diamond, and boron nitride are preferred, with boron nitride being more preferred, from the viewpoint of improving thermal conductivity and insulation while suppressing warpage.

[0051] The boron nitride preferably includes boron nitride agglomerated particles. Boron nitride agglomerated particles are agglomerated particles formed by agglomerating primary particles. Whether or not boron nitride agglomerated particles are agglomerated particles can generally be determined by, for example, cross-sectional observation using an SEM. Note that boron nitride agglomerated particles may maintain the agglomerated particle shape or may be deformed, collapsed, crushed, etc., through various processes such as press molding. However, even if the boron nitride agglomerated particles are deformed, collapsed, crushed, etc., through processes such as press molding after being mixed with a thermosetting resin, they are generally not oriented and exist in a certain degree of aggregation. Therefore, for example, by observing the above-mentioned cross section, it is suggested that they are boron nitride agglomerated particles, and whether or not they are agglomerated particles can be determined based on this.

[0052] From the viewpoint of effectively enhancing insulating properties and thermal conductivity, the boron nitride agglomerated particles blended into the insulating resin sheet preferably have an average particle diameter of 5 μm or more, more preferably 10 μm or more, and preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. The average particle diameter of the agglomerated particles can be measured by a laser diffraction / scattering method. The average particle diameter is calculated by using the particle diameter (d50) of the agglomerated particles when the cumulative volume is 50%.

[0053] The method for producing boron nitride agglomerated particles is not particularly limited, and they can be produced by known methods. For example, they can be obtained by agglomerating (granulating) pre-prepared primary particles. Specific examples include spray drying and fluidized bed granulation. Spray drying (also called spray drying) can be classified into two-fluid nozzle methods, disk methods (also called rotary methods), and ultrasonic nozzle methods, depending on the spray method, and any of these methods can be applied. Furthermore, a granulation step is not necessarily required for producing boron nitride agglomerated particles. For example, agglomerated particles may be formed by spontaneously agglomerating primary particles of boron nitride as crystals of boron nitride crystallized by a known method grow. Furthermore, examples of boron nitride agglomerated particles include "UHP-G1H" manufactured by Showa Denko K.K.

[0054] The content of the insulating and heat-dissipating filler in the curable resin composition is not particularly limited, but is, for example, 30% by volume or more. By making it 30% by volume or more, good thermal conductivity can be imparted to the insulating resin sheet. Furthermore, the content of the insulating and heat-dissipating filler in the curable resin composition is preferably 80% by volume or less. By making it 80% by volume or less, the adhesion of the insulating resin sheet to a metal plate or the like is improved. From the viewpoint of further improving thermal conductivity and insulation, the content of the insulating and heat-dissipating filler in the curable resin composition is more preferably 50% by volume or more, and even more preferably 55% by volume or more. The content of the insulating and heat-dissipating filler in the curable resin composition is the same as the content of the insulating and heat-dissipating filler in the insulating resin sheet.

[0055] [Curing Accelerator] The curable resin composition may further contain a curing accelerator. The use of a curing accelerator increases the curing rate, allowing the curable resin composition to be cured quickly and resulting in a uniform crosslinked structure in the insulating resin sheet. Furthermore, the number of unreacted functional groups is reduced, resulting in a higher crosslink density. The curing accelerator is not particularly limited, and conventionally known curing accelerators can be used. Specific examples include anionic curing accelerators such as imidazole compounds, cationic curing accelerators such as amine compounds, curing accelerators other than anionic and cationic curing accelerators such as phosphorus compounds and organometallic compounds, and radical curing accelerators such as peroxides. The content of the curing accelerator in the curable resin composition is, for example, 0.1 to 8% by volume, preferably 0.3 to 5% by volume. One type of curing accelerator may be used alone, or two or more types may be used in combination.

[0056] [Others] In addition to the above components, the curable resin composition according to the present invention may contain other additives such as a dispersant, a coupling agent such as a silane coupling agent, a flame retardant, an antioxidant, an ion scavenger, a tackifier, a plasticizer, a thiol imparting agent, and a colorant.

[0057] [Thickness] The thickness of the insulating resin sheet of the present invention is 50 μm or more and 500 μm or less. If the thickness is less than 50 μm, it becomes difficult to ensure a certain level of insulation. If the thickness exceeds 500 μm, it becomes difficult to thin circuit boards and semiconductor devices, as described below, and the influence of warping of the substrate becomes greater. The thickness of the insulating resin sheet is preferably 60 μm or more, more preferably 70 μm or more, and preferably 450 μm or less, more preferably 400 μm or less.

[0058] The insulating resin sheet of the present invention may have a single-layer structure or a multi-layer structure. Specifically, a single-layer insulating resin sheet may be formed using the curable resin composition described above, or two or more resin layers may be formed using the curable resin composition described above and then laminated to form a multi-layer insulating resin sheet. Furthermore, the insulating resin sheet may have a resin layer formed from a composition other than the curable resin composition laminated on one or both sides of the insulating resin sheet, as long as the effects of the present invention are not impaired.

[0059] 1 , the laminate of the present invention includes, in addition to the insulating resin sheet 10 of the present invention, a metal base plate 11 and a metal plate 12, and is a laminate 13 having the insulating resin sheet 10 and the metal plate 12 in this order on the metal base plate 11. Note that the insulating resin sheet 10 is preferably a cured insulating resin sheet.

[0060] Because the metal base plate 11 and the metal plate 12 each function as a thermal conductor, their thermal conductivity is preferably 10 W / m·K or higher. Materials used for these include metals such as aluminum, copper, gold, and silver, as well as graphite sheets. From the perspective of more effectively increasing thermal conductivity, aluminum, copper, or gold is preferred, and aluminum or copper is more preferred. The thickness of the metal base plate 11 is preferably 0.1 to 5 mm, and the thickness of the metal plate 12 is preferably 10 to 3000 μm, and more preferably 10 to 1500 μm. The metal plate may be a plate such as a copper plate or a foil such as copper foil.

[0061] The laminate 13 is preferably used as a circuit board. When used as a circuit board, the metal plate 12 in the laminate 13 may have a circuit pattern. The circuit pattern may be appropriately patterned depending on the elements to be mounted on the circuit board. The circuit pattern is not particularly limited, but may be formed by etching or the like. In addition, in the circuit board, the metal base plate 11 is used as a heat sink or the like.

[0062] [Semiconductor Device] The present invention also provides a semiconductor device having the above-described laminate. Specifically, as shown in Fig. 2, the semiconductor device 15 includes a laminate 13 having an insulating resin sheet 10, a metal base plate 11, and a metal plate 12, and a semiconductor element 14 provided on the metal plate 12 of the laminate 13. The metal plate 12 may be patterned by etching or the like to have a circuit pattern.

[0063] Although two semiconductor elements 14 are shown in FIG. 2 , the number of semiconductor elements 14 is not limited and may be any number greater than or equal to one. In addition to the semiconductor elements 14, other electronic components (not shown), such as transistors, may be mounted on the metal plate 12. Each semiconductor element 14 is connected to the metal plate 12 via a connecting conductive portion 16 formed on the metal plate 12. The connecting conductive portion 16 is preferably formed of solder. Furthermore, a sealing resin 19 is provided on the surface of the laminate 13 facing the metal plate 12. At least the semiconductor elements 14 are sealed with the sealing resin 19, and if necessary, the metal plate 12 and the semiconductor elements 14 may also be sealed with the sealing resin 19. The semiconductor elements 14 are not particularly limited, but at least one is preferably a power element (i.e., a power semiconductor element), thereby making the semiconductor device 15 a power module. Power modules are used, for example, in inverters. Power modules are also used, for example, in industrial equipment such as elevators and uninterruptible power supplies (UPS), but their applications are not particularly limited.

[0064] Leads 20 are connected to the metal plate 12. The leads 20 extend, for example, from the sealing resin 19 to the outside, and connect the metal plate 12 to an external device or the like. Wires 17 may also be connected to the semiconductor element 14. As shown in FIG. 2 , the wires 17 may connect the semiconductor element 14 to another semiconductor element 14, the metal plate 12, the leads 20, or the like. When power is supplied to the semiconductor element 14 via the leads 20 or the like to drive it, the semiconductor element 14 generates heat. The heat generated by the semiconductor element 14 is transmitted to the metal base plate 11 via the insulating resin sheet 10 and dissipated from the metal base plate 11. The metal base plate 11 may be connected to a heat sink consisting of heat dissipation fins or the like, as necessary.

[0065] The semiconductor device 15 may be manufactured through a reflow process. Specifically, in the manufacturing method of the semiconductor device 15, first, the laminate 13 is prepared, the connection conductive portions 16 are formed on the metal plate 12 of the laminate 13 by solder printing or the like, and the semiconductor element 14 is mounted on the connection conductive portions 16. The laminate 13 with the semiconductor element 14 mounted thereon is then passed through a reflow furnace and heated therein, and the semiconductor element 14 is connected to the metal plate 12 by the connection conductive portions 16. The temperature within the reflow furnace is not particularly limited, but is, for example, approximately 200 to 300°C. In the manufacturing method of the semiconductor device 15, after the reflow process, a sealing resin 19 may be laminated on the laminate 13 to seal the semiconductor element 14. Furthermore, before sealing with the sealing resin 19, wires 17, leads 20, etc. may be attached as appropriate. Although the above describes a mode in which the semiconductor element 14 is connected to the metal plate 12 by a reflow process, the present invention is not limited to such a mode. For example, the laminate 13 (i.e., the circuit board) may be connected to another board (not shown) by a reflow process.

[0066] [Method for manufacturing insulating resin sheet and laminate] The insulating resin sheet can be obtained by forming the above-mentioned curable resin composition into a sheet. For example, the curable resin composition may be formed into a sheet by coating or laminating it on a support such as a release sheet, or in the case of producing a laminate, it may be formed into a sheet by coating or laminating it on a metal base plate or the like. Here, the term "sheet-like" refers to a thin, flat material whose thickness is small relative to its length and width. The concept of a sheet-like material also includes a material formed into a film or layer on another member such as a support or a metal base plate. In this way, by forming the curable resin composition into a sheet, an insulating resin sheet before curing can be obtained.

[0067] The curable resin composition (insulating resin sheet before curing) formed into a sheet by coating, lamination, or the like may be partially or completely cured by heating and pressurizing by press molding or the like, or may be partially or completely cured before press molding, but it is preferable that the composition be partially or completely cured during press molding. Among these, it is preferable that the insulating resin sheet be partially cured. Partial curing improves the storage stability of the insulating resin sheet. Furthermore, when a laminate described below is produced using a partially cured insulating resin sheet, workability during molding of the laminate is improved.

[0068] Furthermore, when manufacturing a laminate including an insulating resin sheet, a metal base plate, and a metal plate, a curable resin composition (insulating resin sheet before curing) previously formed into a sheet shape can be placed between the metal base plate and the metal plate, and then heated and pressurized by press molding to bond the metal base plate and the metal plate via the insulating resin sheet, thereby manufacturing the laminate. The insulating resin sheet is preferably cured by heating during press molding, but may be partially or completely cured before press molding. In the laminate, it is most preferable that the insulating resin sheet is completely cured in the final product form. Complete curing stabilizes the insulation properties and heat resistance, improves the glass transition temperature, and stabilizes the quality of the laminate.

[0069] Alternatively, a laminate may be obtained by applying or laminating a curable resin composition onto a metal base plate to prepare an insulating resin sheet before curing, then laminating a metal plate on top of the insulating resin sheet, and then curing the insulating resin sheet by heating and pressurizing it using press molding or the like, as necessary, and adhering the metal plate to the metal base plate via the insulating resin sheet.

[0070] EXAMPLES The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these.

[0071] The methods for measuring and evaluating each physical property are as follows. [Molecular Weight] Gel permeation chromatography (GPC) was performed using tetrahydrofuran as a solvent at room temperature and a flow rate of 1 mL / min, and the number average molecular weight of the imide oligomer was determined in polystyrene equivalent terms. 100 μL of a 0.5 wt % THF solution of the imide oligomer was used as the measurement sample. The column used for the measurement was JAIGEL-2H-A (manufactured by Japan Analytical Industry Co., Ltd.).

[0072] [Thickness] The thickness of the insulating resin sheet in the laminate produced in each of the examples and comparative examples was measured.

[0073] [Thermal Conductivity] Each laminate of the Examples and Comparative Examples was cut into a 1 cm square, and then carbon black was sprayed on both sides of the measurement sample. The thermal conductivity of the measurement sample was measured by a laser flash method using a measurement device "HyperFlash" (NETZSCH, model number: LFA467).

[0074] [Breakdown voltage] A circular electrode of φ2 was formed on each laminate (6 cm × 6 cm) produced in the examples and comparative examples, and a voltage was applied to the electrode at a rate of 20 kV / min. The voltage at which the measurement sample suffered a breakdown was taken as the breakdown voltage.

[0075] [Thermal Decomposition Temperature] Each laminate produced in the Examples and Comparative Examples was heat-treated at 150°C for 60 minutes. The insulating resin sheet was then removed from the laminate, and the thermal decomposition temperature was measured. 10 mg of insulating resin sheet was weighed using a thermogravimetric analyzer (TG / DTA, Hitachi High-Tech Science Corporation, "TG / DTA7300"), and the sample was heated from a starting temperature of 30°C to 550°C at a rate of 10°C / min in a nitrogen atmosphere with a flow rate of 100 ml / min, and held there for 5 minutes. The temperature at which the weight of the insulating resin sheet decreased by 1% compared to the weight before measurement was defined as the thermal decomposition temperature. The above-mentioned heat treatment may be performed on the entire laminate or on the insulating resin sheet. If necessary, the laminate may be sandwiched between release PET sheets (40 μm thick) before the heat treatment. When the sample was heat-treated between release PET sheets, the insulating resin sheet was removed from the sample before measuring the thermal decomposition temperature.

[0076] [Glass transition temperature] An insulating resin sheet was prepared by heat treatment in the same manner as in the measurement of the thermal decomposition temperature described above. The insulating resin sheet was heated from 0°C to 300°C using a dynamic viscoelasticity measuring device (manufactured by A&D Co., Ltd., "Rheovibron DDV-25GP") at a heating rate of 10°C / min, a frequency of 10 Hz, and a chuck distance of 24 mm, and the peak temperature of the tan δ curve obtained when the temperature was increased was determined as the glass transition temperature.

[0077] [Evaluation of Warpage] The curable resin composition in each example and comparative example was coated onto a release PET sheet (40 μm thick) to a thickness of 200 μm and dried in an oven at 50°C for 10 minutes to form a sheet (insulating resin sheet) made of the curable resin composition on the release PET sheet. The release PET sheet was then peeled off, and the insulating resin sheet was sandwiched between a first metal layer (copper plate, 50 μm thick) and the release PET sheet. A laminated sample was prepared by vacuum pressing at a temperature of 150°C and a pressure of 10 MPa. The size of the laminated sample was 60 mm x 130 mm. The prepared laminated sample was measured in the minor axis direction at positions 10 mm, 65 mm, and 120 mm from the end of the major axis using a Keyence One-Shot 3D shape measuring instrument. The highest and lowest points at each measurement position were recorded as the warpage at that position. The average warpage value was recorded as the warpage value. A higher warpage value means that the laminated sample including the insulating resin sheet has a larger warpage.

[0078] The components used in the examples and comparative examples are as follows: (Thermosetting resin) Epoxy resin "EPICLON EXA-850CRP" manufactured by DIC Corporation, liquid at 25°C Epoxy resin "EPICLON EXA-830CRP" manufactured by DIC Corporation, liquid at 25°C

[0079] (Insulating heat dissipating filler) Boron nitride "UHP-G1H" manufactured by Showa Denko K.A., average particle size of agglomerated particles: 33 μm, thermal conductivity: 60 W / m·K Alumina "AL35-75R" manufactured by Nippon Steel Materials Co., Ltd., average particle size: 35 μm, thermal conductivity: 30 W / m·K Diamond Diamond powder, natural, average particle size: 40 to 60 μm, thermal conductivity: 2000 W / m·K Fujifilm Wako Pure Chemical Industries, Ltd.

[0080] (Other fillers) Silica: Admatechs "SO-G4", thermal conductivity 1 W / m·K

[0081] (Curing Agent) Imide Oligomer (IMO-1) IMO-1 was produced as follows. 20 parts by weight of 1,3-bis(3-aminophenoxy)benzene APB-N (manufactured by Mitsui Fine Chemicals, Inc.) was dissolved in 200 parts by weight of N-methylpyrrolidone (manufactured by Wako Pure Chemical Industries, Ltd.). 20 parts by weight of 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the resulting solution, and the mixture was stirred at 25°C for 2 hours to allow the reaction to proceed, yielding an amic acid oligomer solution. N-methylpyrrolidone was removed from the resulting amic acid oligomer solution under reduced pressure, and the mixture was heated at 300°C for 2 hours to yield the imide oligomer IMO-1 (imidization rate 97%). The imide oligomer had acid anhydride groups at both ends, no linear saturated hydrocarbon chain with 16 or more carbon atoms in its backbone, and a number-average molecular weight of 1,310.

[0082] Imide Oligomer (IMO-2) IMO-2 was produced as follows. 104 parts by weight of 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (Tokyo Chemical Industry Co., Ltd.) was dissolved in 300 parts by weight of N-methylpyrrolidone (Fujifilm Wako Pure Chemical Industries, Ltd., "NMP"). A solution prepared by diluting 56.8 parts by weight of Priamine 1073 (Croda) in 100 parts by weight of N-methylpyrrolidone was added to the resulting solution, and the mixture was stirred at 25°C for 2 hours to allow the reaction to occur, yielding an amic acid oligomer solution. After removing N-methylpyrrolidone from the resulting amic acid oligomer solution under reduced pressure, the solution was heated at 300°C for 2 hours to yield the imide oligomer IMO-2 (imidization rate 93%). The imide oligomer had acid anhydride groups at both ends, a linear saturated hydrocarbon chain with 16 or more carbon atoms in its backbone, and a number-average molecular weight of 2,200.

[0083] Imide Oligomer (IMO-3) IMO-3 was produced as follows. 21.8 parts by weight of 3-aminophenol (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in 200 parts by weight of N-methylpyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.). 17.2 parts by weight of 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the resulting solution, and the mixture was stirred at 25°C for 2 hours to allow the reaction to proceed, yielding an amic acid oligomer solution. N-methylpyrrolidone was removed from the resulting amic acid oligomer solution under reduced pressure, and the mixture was heated at 300°C for 2 hours to yield IMO-3 (imidization rate: 96%). The imide oligomer had phenolic hydroxyl groups at both ends, no linear saturated hydrocarbon chain with 16 or more carbon atoms in its skeleton, and a number-average molecular weight of 700.

[0084] Imide Oligomer (IMO-4) IMO-4 was produced as follows. 3.4 parts by weight of 3-aminophenol (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in 200 parts by weight of N-methylpyrrolidone (manufactured by Tokyo Chemical Industry Co., Ltd.). 13.1 parts by weight of IMO-1 (described above) was added to the resulting solution, and the mixture was stirred at 25°C for 2 hours to react, yielding an amic acid oligomer solution. N-methylpyrrolidone was removed from the resulting amic acid oligomer solution under reduced pressure, and the mixture was heated at 300°C for 2 hours to yield IMO-4 (imidization rate 94%). The imide oligomer had phenolic hydroxyl groups at both ends, no linear saturated hydrocarbon chain with 16 or more carbon atoms in its skeleton, and a number-average molecular weight of 1,560.

[0085] ・Cyanate ester compound: "BA-3000S" manufactured by Lonza Co., Ltd. ・Isocyanuric modified solid dispersion type imidazole: "2MZA" manufactured by Shikoku Kasei Co., Ltd. ・Acid anhydride: "Rikacid HH" manufactured by New Japan Chemical Co., Ltd. ・Polyimide amide resin: "Vylomax HR-15ET" manufactured by Toyobo Co., Ltd.

[0086] [Example 1] A thermosetting resin, a filler, and a curing agent shown in Table 1 were mixed in the amounts shown in Table 1 to obtain a curable resin composition. The curable resin composition was applied to a release PET sheet (thickness 40 μm) to a thickness of 200 μm and dried in an oven at 50°C for 10 minutes to form an insulating resin sheet made of the curable resin composition on the release PET sheet. The release PET sheet was then peeled off, and both sides of the insulating resin sheet were sandwiched between a first metal layer (copper plate, thickness 500 μm) and a second metal layer (aluminum plate, thickness 1.0 mm). The resulting mixture was vacuum-pressed at a temperature of 150°C and a pressure of 10 MPa to produce a laminate in which the first metal layer, the insulating resin sheet, and the second metal layer were stacked in this order.

[0087] Examples 2 to 12, Comparative Examples 1 to 7 Laminates were produced in the same manner as in Example 1, except that the types, amounts and thicknesses of the components contained in the curable resin composition were changed as shown in Table 1.

[0088]

[0089] It was found that the insulating resin sheets of each example satisfying the requirements of the present invention had insulation properties, high thermal conductivity, excellent heat resistance, and suppressed warpage. On the other hand, the insulating resin sheets of Comparative Examples 1 to 3 and 6, which did not use imide oligomer, had thermal decomposition temperatures below 280°C and poor heat resistance. Furthermore, the insulating resin sheet of Comparative Example 4, which did not contain an insulating and heat-dissipating filler with a thermal conductivity of 10 W / m·K or more, had low thermal conductivity and a large warpage value. The insulating resin sheet of Comparative Example 5, which had a thickness of over 500 μm, had a large warpage value. Furthermore, the insulating resin sheet of Comparative Example 7 had a thermal decomposition temperature below 280°C and poor heat resistance, and also had a large warpage value.

[0090] REFERENCE SIGNS LIST 10 insulating resin sheet 11 metal base plate 12 metal plate 13 laminate 14 semiconductor element 15 semiconductor device 16 connecting conductive part 17 wire 19 sealing resin 20 lead

Claims

1. An insulating resin sheet made of a curable resin composition containing a thermosetting resin, a curing agent, and an insulating and heat-dissipating filler having a thermal conductivity of 10 W / m·K or more, wherein the curing agent is an imide oligomer, the thermal decomposition temperature of the cured product is 280°C or more, and the thickness is 50 μm or more and 500 μm or less.

2. The insulating resin sheet according to claim 1, wherein the content of the insulating and heat-dissipating filler is 50% by volume or more.

3. An insulating resin sheet according to claim 1 or 2, wherein the imide oligomer has reactive functional groups at both ends or one end of the molecule that can react with the thermosetting resin, and the reactive functional groups are acid anhydride groups, amine groups, or hydroxyl groups.

4. The insulating resin sheet according to any one of claims 1 to 3, wherein the higher of the softening point and melting point of said thermosetting resin is 150°C or lower.

5. The insulating resin sheet according to any one of claims 1 to 4, wherein the imide oligomer does not have a linear saturated hydrocarbon chain having 16 or more carbon atoms in its skeleton.

6. The insulating resin sheet according to any one of claims 1 to 5, wherein the number average molecular weight of the imide oligomer is 500 to 10,000.

7. A laminate comprising an insulating resin sheet according to any one of claims 1 to 6, a metal base plate, and a metal plate, with the insulating resin sheet and the metal plate disposed in this order on the metal base plate.

8. The laminate according to claim 7, which is a circuit board.

9. The laminate according to claim 7 or 8, wherein the metal plate has a circuit pattern.

10. A semiconductor device comprising the laminate according to any one of claims 7 to 9 and a semiconductor element provided on the metal plate.