Sheet, cured article, and cured adhesive article

Abstract

To provide a sheet that exhibits superior shear elongation while having high thermal conductivity.SOLUTION: A sheet comprising (A) a polymer having a siloxane skeleton and (B) an aluminum nitride filler, wherein the polymer having a siloxane skeleton (A) has a specific siloxane skeleton, and the aluminum nitride filler (B) has an average particle diameter of 25 to 80 μm, a specific surface area of 0.15 to 1.0 m2 / g, and a bulk density of 1.0 to 1.90 g / cm3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sheet suitable for use in electronic parts and electronic materials, and more particularly to a sheet having high thermal conductivity and high shear elongation that is used as a heat dissipation material or the like. [Background technology]

[0002] In recent years, as electronic devices have become more powerful, more functional, and lighter and more compact, many electronic components have been densely mounted on electronic circuit boards. Many of these mounted electronic components act as heat generators, and the heat generated by these electronic components has adversely affected the safety, performance, and reliability of the electronic devices, posing a major problem. Therefore, there is a growing demand for highly thermally conductive sheets that can transfer heat generated by electronic components from the components and circuit boards to the housing or heat sink without loss.

[0003] As a material used for a highly thermally conductive sheet, a sheet in which a highly heat-dissipating inorganic filler is added to a thermosetting resin such as an epoxy resin to increase thermal conductivity has been proposed (see, for example, Patent Document 1). Also, in the case of adhesives containing polyimide resin, an adhesive composition has been proposed in which the thermal conductivity, heat resistance, and adhesiveness have been improved by adding a highly heat-dissipating inorganic filler (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-59825 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-84072 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when sheets using conventional resin compositions contain a large amount of inorganic filler such as aluminum nitride filler in order to improve thermal conductivity, the dispersibility of the inorganic filler in the resin deteriorates, and although the thermal conductivity increases, the tensile modulus increases and the shear elongation decreases, resulting in the problem of peeling during thermal cycle tests of semiconductors, etc.

[0006] Therefore, an object of the present invention is to provide a sheet that exhibits high shear elongation over a wide temperature range while having high thermal conductivity by using an aluminum nitride filler with a specific surface state. [Means for solving the problem]

[0007] In order to solve the above problems, the gist of the present invention is a sheet containing (A) a polymer having a siloxane skeleton and (B) an aluminum nitride filler, wherein (A) the polymer having a siloxane skeleton has a siloxane skeleton represented by general formula (1), and (B) the aluminum nitride filler has an average particle size of 25 to 80 μm and a specific surface area of ​​0.15 to 1.0 m 2 / g, bulk density 1.0 to 1.90 g / cm 3 The sheet is characterized by:

[0008] [ka]

[0009] In general formula (1), R 1 ~R 4 may be the same or different and represent an alkyl group having 1 to 30 carbon atoms, a phenyl group, or a phenoxy group. However, the phenyl group and the phenoxy group may be substituted with an alkyl group having 1 to 30 carbon atoms. 1 and R 3 may be the same or different. 5 and R 6may be the same or different and represent an alkylene group or an arylene group having 1 to 30 carbon atoms, provided that the arylene group may be substituted with an alkyl group having 1 to 30 carbon atoms. m is an integer selected from 1 to 100. [Effects of the Invention]

[0010] According to the present invention, by using an aluminum nitride filler with a specific surface state, it is possible to obtain a sheet that has high thermal conductivity, large elongation in the shear direction, and little peeling from the substrate. [Brief explanation of the drawings]

[0011] [Figure 1] Shear test results of sheets of Examples 1 to 6 at 25°C [Figure 2] Shear test results at 25°C for sheets of Examples 2, 5, 7 to 10 [Figure 3] Shear test results of sheets of Comparative Examples 1 to 3 at 25 ° C. [Figure 4] Shear test results of sheets of Examples 4, 5, and 8 at -60°C [Figure 5] Shear test results of sheets of Examples 4, 5, and 8 at 150°C DETAILED DESCRIPTION OF THE INVENTION

[0012] The sheet of the present invention is a sheet comprising (A) a polymer having a siloxane skeleton and (B) an aluminum nitride filler, wherein (A) the polymer having a siloxane skeleton has a siloxane skeleton represented by general formula (1), and (B) the aluminum nitride filler has an average particle size of 25 to 80 μm, a specific surface area of ​​0.15 to 1.0 m / g, and a bulk density of 1.0 to 1.90 g / cm.

[0013] [(A) Polymer having a siloxane skeleton] The polymer (A) having a siloxane skeleton used in the present invention has a siloxane skeleton represented by general formula (1). Polymers having a siloxane skeleton represented by general formula (1) have excellent heat resistance and are less susceptible to resin degradation such as oxidation reactions due to heat exposure. Furthermore, by lengthening the chain of the siloxane skeleton, it is easy to reduce the tensile modulus, thereby improving adhesion to substrates such as support bodies and metal plates. The functional group of the polymer having a siloxane skeleton is preferably a methyl group, which has little steric hindrance. The use of bulky functional groups such as a phenyl group or a tert-butyl group tends to inhibit the curing of the sheet.

[0014] The polymer (A) having a siloxane skeleton used in the present invention preferably has a molecular weight of 40,000 to 100,000. If the molecular weight is 40,000 or less, the fluidity of the sheet increases, and the amount of change in sheet thickness during adhesion increases. If the molecular weight is 100,000 or more, cracks will occur between the sheet and the adherend during shear testing, making it more likely that interfacial peeling will occur.

[0015] The weight average molecular weight is measured by using a solution in which a polymer having a siloxane skeleton is dissolved and calculating the weight average molecular weight in terms of polystyrene using a GPC (gel permeation chromatograph) device.

[0016] In addition, the polymer (A) having a siloxane skeleton in the present invention is preferably solvent-soluble. Solvent-soluble polymers can reduce viscosity when preparing a resin composition, further improving the dispersibility of thermally conductive fillers. Solvent-soluble polymers refer to polymers that dissolve at 25°C in an amount of 1 g or more in 100 g of an organic solvent, such as an amide solvent (e.g., N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, N-vinylpyrrolidone, or N,N-diethylformamide), or an ether solvent (e.g., γ-butyrolactone, methyl monoglyme, methyl diglyme, methyl triglyme, ethyl monoglyme, ethyl diglyme, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol dimethyl ether, or ethylene glycol diethyl ether.

[0017] The polymer (A) having a siloxane skeleton in the present invention is preferably a polyimide having a siloxane skeleton. The polyimide having a siloxane skeleton in the present invention can be easily obtained mainly by reacting a tetracarboxylic dianhydride with a diamine, and has a tetracarboxylic dianhydride residue and a diamine residue. Here, the polyimide having a siloxane skeleton in the present invention preferably contains 20 mol % or more of residues corresponding to a tetracarboxylic dianhydride having a structure represented by the following general formula (2), where the total amount of tetracarboxylic dianhydride residues is taken as 100 mol %. By introducing a siloxane skeleton into the tetracarboxylic dianhydride residue, the linearity and rigidity of the molecular chain of the polyimide having a siloxane skeleton are reduced, and the glass transition temperature can be lowered, particularly to −30° C. or lower. Lowering the glass transition temperature can reduce the tensile modulus at low temperatures. From the viewpoint of lowering the glass transition temperature, the content of the residues of tetracarboxylic dianhydride having the structure represented by the following general formula (2) is more preferably 30 mol % or more, when the total amount of the residues of tetracarboxylic dianhydride is taken as 100 mol %. There is no particular upper limit, and 100 mol % is preferable, but from the viewpoint of improving the handleability of the sheet, it is practical to set it to about 95 mol %.

[0018] [ka]

[0019] In the general formula (2), m represents an integer of 1 or more and 100 or less. 7 and R 8 may be the same or different and represent an alkylene group or arylene group having 1 to 30 carbon atoms. The alkylene group having 1 to 30 carbon atoms is not particularly limited, but a methylene group, an ethylene group, a propylene group, or a butylene group is preferred. The arylene group having 1 to 30 carbon atoms may have a substituent, and the substituent is not particularly limited, but examples thereof include an alkyl group having 1 to 24 carbon atoms. R 1 ~R 6may be the same or different and represent an alkyl group having 1 to 30 carbon atoms, a phenyl group, or a phenoxy group. The alkyl group having 1 to 30 carbon atoms is not particularly limited, but a methyl group, an ethyl group, a propyl group, or a butyl group is preferred. The alkyl group and alkylene group do not necessarily have a linear structure. Y 1 and Y 2 may be the same or different and represent a trivalent hydrocarbon group having 1 to 20 carbon atoms.

[0020] Examples of products corresponding to the tetracarboxylic dianhydride represented by general formula (2) include, but are not limited to, X-22-168AS, X-22-168A, X-22-168B, and X-22-168-P5-B manufactured by Shin-Etsu Chemical Co., Ltd.

[0021] The polyimide having a siloxane skeleton used in the present invention may naturally contain residues of other tetracarboxylic dianhydrides in addition to the residue of the tetracarboxylic dianhydride containing the siloxane skeleton. Examples of such tetracarboxylic dianhydrides include pyromellitic dianhydride (PMDA), oxydiphthalic dianhydride (ODPA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride (BSAA), 4,4'-hexafluoroisopropylidenediphthalic anhydride (6FDA), and 1,2-ethylenebis(anhydrotrimellitate) (TMEG). These may be used in combination. However, examples of tetracarboxylic dianhydrides that can be used in the present invention are not limited to these.

[0022] The polyimide having a siloxane skeleton used in the present invention preferably contains 50 mol % or more of residues corresponding to a diamine having a structure represented by the following general formula (3), where the total amount of diamine residues is taken as 100 mol %. Because the siloxane skeleton is highly flexible, a sheet obtained using a polyimide having such a structure has a low tensile modulus and improved adhesion to a substrate. From the viewpoint of reducing the tensile modulus, the content corresponding to the diamine residue having the structure represented by the following general formula (3), where the total amount of diamine residues is taken as 100 mol %, is more preferably 60 mol % or more. Furthermore, from the viewpoint of compatibility with epoxy resins, the upper limit is preferably 99 mol % or less, and more preferably 95 mol % or less.

[0023] [ka]

[0024] In the general formula (3), n represents an integer of 1 or more and 100 or less. 7 and R 8 R may be the same or different and represent an alkylene group or an arylene group having 1 to 30 carbon atoms. The arylene group may have a substituent, and the substituent is not particularly limited, but examples thereof include an alkyl group having 1 to 24 carbon atoms. 1 ~R 6 may be the same or different and represent an alkyl group having 1 to 30 carbon atoms, a phenyl group, or a phenoxy group. The alkyl group having 1 to 30 carbon atoms is not particularly limited, but a methyl group, an ethyl group, a propyl group, or a butyl group is preferred. The alkylene group having 1 to 30 carbon atoms is not particularly limited, but a methylene group, an ethylene group, a propylene group, or a butylene group is preferred. The alkyl group and alkylene group do not need to have a linear structure.

[0025] Examples of products corresponding to the diamine represented by general formula (3) include X-22-161A, X-22-161B, KF8012, KF8008, and X-22-1660B-3 manufactured by Shin-Etsu Chemical Co., Ltd.

[0026] The polyimide having a siloxane skeleton used in the present invention preferably contains a diamine residue having a hydroxyl group or a carboxyl group. The presence of a diamine residue having a hydroxyl group or a carboxyl group promotes reaction with the epoxy resin, improving the toughness of the cured product after the curing reaction. Diamines having a carboxyl group are particularly preferred because they have stronger acidity, which can improve the dispersibility of thermally conductive fillers and thereby improve thermal conductivity. From the perspective of improving the toughness of the sheet, the content of the diamine residue having a hydroxyl group or a carboxyl group is preferably 1 mol% or more, where the total amount of diamine residues is 100 mol%. Furthermore, from the perspective of improving the flexibility of the sheet, the content is preferably 40 mol% or less, and more preferably 30 mol% or less. Examples of diamine residues having a hydroxyl group or a carboxyl group include the following:

[0027] [ka]

[0028] [ka]

[0029] [ka]

[0030] It is naturally acceptable that the polyimide having a siloxane skeleton (A) used in the present invention contains residues of other diamines in addition to the residue of the diamine containing a siloxane skeleton. Examples of such diamines include diamines containing one benzene ring such as 1,4-diaminobenzene, 1,3-diaminobenzene, 2,4-diaminotoluene, and 1,4-diamino-2,5-dihalogenobenzene; diamines containing two benzene rings such as bis(4-aminophenyl)ether, bis(3-aminophenyl)ether, bis(4-aminophenyl)sulfone, bis(3-aminophenyl)sulfone, bis(4-aminophenyl)methane, bis(3-aminophenyl)methane, bis(4-aminophenyl)sulfide, bis(3-aminophenyl)sulfide, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane, o-dianisidine, o-tolidine, and tolidine sulfonic acids; Examples of diamines include diamines containing three benzene rings such as 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]sulfone, 4,4'-(4-aminophenoxy)biphenyl, 9,9-bis(4-aminophenyl)fluorene, and 5,10-bis(4-aminophenyl)anthracene. These may be used in combination. However, the other diamines that can be used in the present invention are not limited to these.

[0031] In (A) polyimides having a siloxane skeleton, the tetracarboxylic dianhydride residues and diamine residues preferably satisfy one or more of the following: 1) few benzene rings, 2) high molecular weight and bulkiness, and 3) many bending sites such as ether bonds. Such a structure weakens the interactions between molecular chains, improving the solubility of the polyimide in organic solvents.

[0032] The polyimide (A) having a siloxane skeleton in the present invention may be composed solely of polyimide structural units, or may be a copolymer having other structures as copolymerization components in addition to the polyimide structural units. It may also contain a precursor of the polyimide structural unit (a polyamic acid structure). It may also be a mixture of these. Furthermore, any of these may be mixed with a polyimide represented by another structure. When other polyimides are mixed, it is preferable that the polyimide having a siloxane skeleton is contained in an amount of 50 mol % or more. The type and amount of structures used for copolymerization or mixing are preferably selected within a range that does not impair the effects of the present invention.

[0033] The synthesis method of the polyimide having a siloxane skeleton (A) used in the present invention is not particularly limited, and it can be synthesized by a known method using a diamine and a tetracarboxylic dianhydride. For example, a method of reacting a tetracarboxylic dianhydride with a diamine compound (which may be partially substituted with an aniline derivative) at low temperature, a method of reacting a tetracarboxylic dianhydride with an alcohol to obtain a diester, and then reacting it with a diamine (which may be partially substituted with an aniline derivative) in the presence of a condensing agent, or a method of reacting a tetracarboxylic dianhydride with an alcohol to obtain a diester, and then converting the remaining two carboxyl groups into acid chlorides and reacting them with a diamine (which may be partially substituted with an aniline derivative) to obtain a polyimide precursor, which can then be synthesized using a known imidization method.

[0034] [Other resins, etc.] The sheet of the present invention preferably contains an epoxy resin, which promotes the crosslinking reaction of the polymer (A) having a siloxane skeleton, improving the toughness of the sheet and improving the adhesive strength.

[0035] The epoxy resin used in the present invention is preferably an epoxy resin containing a siloxane skeleton, from the viewpoint of reducing the tensile modulus of elasticity of the cured sheet and improving flexibility. Examples of such epoxy resins include X-40-2695B and X-22-2046 manufactured by Shin-Etsu Chemical Co., Ltd.

[0036] The epoxy resin used in the present invention preferably has an epoxy equivalent of 400 g / eq or more in order to keep the crosslink density of the epoxy resin low and to lower the glass transition temperature after curing of the sheet. Examples of such epoxy resins include YX7105, YX7110, YX7400, YX7400N, and JER871 manufactured by Mitsubishi Chemical Corporation, and EXA-4850-150 manufactured by DIC Corporation.

[0037] The epoxy resin used in the present invention is preferably a crystalline epoxy resin from the viewpoint of improving the structural regularity of the sheet and improving thermal conductivity. Crystalline epoxy resins are epoxy resins having a mesogenic skeleton such as a biphenyl group, a naphthalene skeleton, an anthracene skeleton, a phenylbenzoate group, or a benzanilide group. Examples of products corresponding to such epoxy resins include Mitsubishi Chemical Corporation's 630, JERYX4000, JERYX4000H, JERYX8800, JERYL6121H, JERYL6640, JERYL6677, and JERYX7399; Nippon Kayaku Co., Ltd.'s NC3000, NC3000H, NC3000L, and CER-3000L; Nippon Steel Chemical Co., Ltd.'s YSLV-80XY and YDC1312; and DIC Corporation's HP4032, HP4032D, and HP4700.

[0038] The epoxy resin used in the present invention is preferably a liquid epoxy resin from the viewpoint of reducing the viscosity when dispersing the aluminum nitride filler (B).5 N / m 2 These epoxy resins have a viscosity of 150 Pa·s or less, for example, bisphenol A epoxy resins, bisphenol F epoxy resins, alkylene oxide-modified epoxy resins, glycidylamine epoxy resins, etc. Examples of products corresponding to these epoxy resins include JER827, JER828, JER806, JER807, JER801N, JER802, JER604, JER630, and JER630LSD manufactured by Mitsubishi Chemical Corporation, Epiclon 840S, Epiclon 850S, Epiclon 830S, Epiclon 705, and Epiclon 707 manufactured by DIC Corporation, YD127, YD128, PG207N, and PG202 manufactured by Nippon Steel Chemical Co., Ltd., and TEPIC-PASB26L, TEPIC-PASB22, TEPIC-VL, TEPIC-FL, and TEPIC-UC manufactured by Nissan Chemical Industries, Ltd.

[0039] The epoxy resin used in the present invention may be one type or a combination of two or more types. The content of the epoxy resin is preferably 0.1 parts by weight or more per 100 parts by weight of the polymer (A) having a siloxane skeleton from the viewpoint of improving the toughness and adhesive strength of the sheet, and is preferably 15 parts by weight or less from the viewpoint of improving the flexibility of the sheet and keeping the tensile modulus at low temperatures low.

[0040] The sheet of the present invention preferably contains a diamine compound as a curing agent for the epoxy resin. Siloxane diamine is particularly preferred. Combining an epoxy resin with a siloxane diamine accelerates the curing of the epoxy resin, allowing it to cure in a short time. Siloxane diamines have a highly flexible siloxane skeleton, which can reduce the tensile modulus of elasticity at low temperatures, particularly after curing. Furthermore, the reaction of the epoxy resin with the siloxane diamine results in a low crosslink density and high flexibility, thereby increasing the shear elongation at low temperatures. The siloxane diamine preferably has a structure represented by general formula (4). From the viewpoint of reducing the tensile modulus of elasticity of the sheet after curing, N is preferably 6 or more. Furthermore, from the viewpoint of improving the crosslink density and increasing the adhesive strength in the curing reaction with the epoxy resin, N is preferably 30 or less, more preferably 25 or less. Examples of products corresponding to the diamine represented by general formula (4) include KF8010, X-22-161A, and X-22-9409 manufactured by Shin-Etsu Chemical Co., Ltd. The content of (C) siloxane diamine is preferably 5% by weight or more and 20% by weight or less, when the total of (A) polymer having a siloxane skeleton, the epoxy resin, and the siloxane diamine is taken as 100% by weight. From the viewpoint of accelerating the curing reaction of the epoxy resin, it is preferably 5% by weight or more, and more preferably 6% by weight or more. Furthermore, from the viewpoint of suppressing the crosslink density after the curing reaction and thereby keeping the tensile modulus low, it is preferably 20% by weight or less, and more preferably 15% by weight or less.

[0041] [ka]

[0042] (In the general formula (4), N is an integer of 5 or more and 30 or less. R 7 and R 8 may be the same or different and represent an alkylene group or an arylene group having 1 to 30 carbon atoms. 1 ~R 6 may be the same or different and represent an alkyl group having 1 to 30 carbon atoms, a phenyl group, or a phenoxy group. Furthermore, the sheet of the present invention may contain a curing accelerator as needed. Combining an epoxy resin with a curing accelerator accelerates the curing of the epoxy resin, allowing it to cure in a short period of time. Examples of curing accelerators that can be used include imidazoles, polyhydric phenols, acid anhydrides, amines, hydrazides, polymercaptans, Lewis acid-amine complexes, and latent curing accelerators.

[0043] Examples of imidazoles include Curesol 2MZ, Curesol 2PZ, Curesol 2MZ-A, and Curesol 2MZ-OK (all trade names, manufactured by Shikoku Chemical Industry Co., Ltd.). Examples of polyhydric phenols include SUMILITE RESIN PR-HF3 and SUMILITE RESIN PR-HF6 (all trade names, manufactured by Sumitomo Bakelite Co., Ltd.), KAYAHARD KTG-105 and KAYAHARD NHN (all trade names, manufactured by Nippon Kayaku Co., Ltd.), PHENOLITE TD2131, PHENOLITE TD2090, PHENOLITE VH-4150, PHENOLITE KH-6021, PHENOLITE KA-1160, and PHENOLITE KA-1165 (all trade names, manufactured by DIC Corporation). Examples of the latent curing accelerator include dicyandiamide-type latent curing accelerators, amine adduct-type latent curing accelerators, organic acid hydrazide-type latent curing accelerators, aromatic sulfonium salt-type latent curing accelerators, microcapsule-type latent curing accelerators, and photocurable latent curing accelerators.

[0044] Examples of amine adduct-type latent curing accelerators include Amicure PN-23, Amicure PN-40, Amicure MY-24, and Amicure MY-H (all trade names, manufactured by Ajinomoto Fine-Techno Co., Ltd.), and Fujicure FXR-1030 (trade name, manufactured by Fuji Kasei Co., Ltd.). Examples of organic acid hydrazide-type latent curing accelerators include Amicure VDH and Amicure UDH (all trade names, manufactured by Ajinomoto Fine-Techno Co., Ltd.). Examples of aromatic sulfonium salt-type latent curing accelerators include San-Aid SI100, San-Aid SI150, and San-Aid SI180 (all trade names, manufactured by Sanshin Chemical Industry Co., Ltd.). Examples of microcapsule-type latent curing accelerators include those obtained by encapsulating the above-mentioned curing accelerators with a vinyl compound, a urea compound, or a thermoplastic resin. Among these, examples of microcapsule-type latent curing accelerators in which an amine adduct-type latent curing accelerator is treated with isocyanate include Novacure HX-3941HP, Novacure HXA3922HP, Novacure HXA3932HP, and Novacure HXA3042HP (all trade names, manufactured by Asahi Kasei Chemicals Corp.). Examples of photocurable latent curing accelerators include Optomer SP and Optomer CP (all trade names, manufactured by ADEKA Corp.).

[0045] When the sheet of the present invention contains a curing accelerator, the content thereof is preferably 0.1 parts by weight or more and 35 parts by weight or less relative to 100 parts by weight of the epoxy resin.

[0046] [(B) Aluminum nitride filler] The sheet of the present invention contains (B) aluminum nitride filler. Aluminum nitride is an insulating, thermally conductive filler with a high thermal conductivity of approximately 170 W / m·K, allowing the sheet to have a higher thermal conductivity. Examples of such (B) aluminum nitride filler include the FAN-f30 series manufactured by Furukawa Electronics Co., Ltd. and M30 manufactured by MARUWA Corporation. The thermal conductivity of (B) aluminum nitride filler can be determined by measuring in accordance with JIS R1611 (2010) after obtaining a sintered body with a thickness of approximately 1 mm and a porosity of 10% by volume or less.

[0047] (B) The average particle size of the aluminum nitride filler is 25 to 80 μm. When the average particle size is 25 μm or more, the interfacial thermal resistance between fillers and between fillers and resin within the sheet can be reduced, achieving high thermal conductivity. Furthermore, when the average particle size is 80 μm or less, it becomes easier to adjust the sheet film thickness during coating, and unevenness in the coated surface can be suppressed. The method for measuring the average particle size will be described later.

[0048] (B) The specific surface area of ​​the aluminum nitride filler is 0.15 to 1.0 m 2 / g. The specific surface area is 0.15m 2 / g or more, the interaction with the resin can be strengthened, and the shear elongation of the sheet after curing can be increased. 2 By ensuring that the viscosity is not more than 1 / g, it is possible to prevent the viscosity from increasing when mixed with the resin component.

[0049] The specific surface area can be calculated by measuring the BET specific surface area using the gas adsorption method based on JIS R 1626. The mass of the (B) aluminum nitride filler is measured, and then gas molecules of an inert gas such as nitrogen gas or helium gas are adsorbed, and the BET specific surface area is calculated from the monomolecular adsorption amount. The specific surface area is greatly influenced by the primary particle size, shape, and agglomeration state of the (B) aluminum nitride filler. One method for increasing the specific surface area is to crush the agglomerated particles of the (B) aluminum nitride filler using a dry jet mill or crusher. The bulk density is 1.0 to 1.90 g / cm. 3 This value indicates that the specific surface area is not derived from the fine particles of (B) aluminum nitride filler, but from the unevenness of the surface of (B) aluminum nitride filler. Bulk density 1.0 g / cm 3 If the bulk density is less than 1.90 g / cm, the sheet will have a high tensile modulus, which will cause cracking at low temperatures. 3 If this is the case, the surface irregularities of the aluminum nitride filler (B) are insufficient, and the shear elongation at 25°C does not exceed the target value of 180%.

[0050] In the present invention, the aluminum nitride filler (B) is preferably spherical. The use of a spherical filler reduces the viscosity of the sheet and improves adhesion to the substrate. In the present invention, "spherical" refers to a shape in which the primary particles of the thermally conductive filler are observed with a scanning electron microscope (e.g., Hitachi, Ltd., product name: FE-SEM S4700), and 50 randomly selected primary particles are subjected to calculations of the average maximum length and average minimum length. The value of (average maximum length) / (average minimum length) is 1.0 or more and 1.90 or less. Here, "length" is determined as the distance between two parallel lines that touch the outer edge of the image of the particle being measured at different points.

[0051] [Thermal conductive filler] The sheet desirably contains one or more thermally conductive fillers (hereinafter, sometimes referred to as "thermally conductive fillers") different from (B) aluminum nitride filler. In the present invention, thermally conductive fillers refer to inorganic particles having a thermal conductivity of 2 W / m·K or more at 25°C. Examples of thermally conductive fillers include inorganic fillers such as carbon black, silica, magnesium oxide, zinc oxide, alumina, boron nitride, silicon carbide, and silicon nitride, and metal fillers such as copper, aluminum, magnesium, silver, zinc, iron, and lead. Among these, alumina, boron nitride, zinc oxide, magnesium oxide, and silica are preferred. This is because the thermal conductivity of thermally conductive fillers is high, and they are highly effective in increasing the thermal conductivity of the sheet.

[0052] These thermally conductive fillers may be used alone in combination with (B) aluminum nitride filler in the sheet, or multiple thermally conductive fillers may be used in combination. The shape of the thermally conductive filler is not particularly limited, and examples include spherical, globular, scale-like, flake-like, foil-like, fibrous, and needle-like shapes. From the perspective of incorporating the thermally conductive filler at high density, it is preferable to use a spherical thermally conductive filler. Here, the two or more types may have the same composition but different average particle sizes, but they may also have different compositions. Furthermore, when peak division is performed on the particle size distribution curve, at least two peaks are shown, and the average particle size of the thermally conductive filler that constitutes the peak other than (B) aluminum nitride filler is preferably 30 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less.

[0053] The particle size distribution (average particle size) of (B) aluminum nitride filler and other thermally conductive fillers is measured by laser diffraction / scattering using a measuring instrument such as Shimadzu Corporation's SLD3100 or Horiba, Ltd.'s LA920, or equivalent. By incorporating two or more fillers with different average particle sizes, the (B) aluminum nitride filler and thermally conductive filler can be packed at high density, resulting in higher thermal conductivity. On the other hand, from the perspective of improving filler dispersibility, the average particle size of the smallest peak average particle size is preferably 0.001 μm or more, and from the perspective of achieving a smooth film surface when cured, the average particle size of the largest peak average particle size is preferably 100 μm or less.

[0054] Thus, there are no particular limitations on the method for making the particle size distribution curve show two or more peaks when peak division is performed. For example, a method can be used in which a thermally conductive filler having an average particle size of 10 μm or less is blended to have a frequency peak of 10 μm or less, and (B) aluminum nitride filler having an average particle size of 30 μm or more is blended to have a frequency peak of 30 μm or more, and these are mixed to form a sheet.

[0055] Furthermore, from the viewpoint of obtaining high thermal conductivity, the content of the thermally conductive filler is preferably 50% by volume or more, and more preferably 60% by volume or more, when the total volume of the (B) aluminum nitride filler and the thermally conductive filler is taken as 100% by volume. In the present invention, the total content of the (B) aluminum nitride filler and the thermally conductive filler preferably accounts for 50% by volume or more when the cured product is formed. A content of 50% by volume or more increases the thermal conductivity of the cured product. The filler volume content can be calculated from the cured product using the following thermogravimetric analysis method or an equivalent method. First, the cured product formed into a sheet is heated to 600 to 900°C to decompose and volatilize the resin, the weight of the contained filler is measured, and the weight of the resin is then calculated. One method for calculating the volume is to divide by the specific gravity of the filler and resin.

[0056] [Surfactants] The sheet of the present invention may contain a surfactant as needed to improve the surface smoothness of the cured product and the adhesion to the substrate. The sheet may also contain 0.5 to 10 wt % of a silane coupling agent such as methylmethacryloxydimethoxysilane or 3-aminopropyltrimethoxysilane, or a titanium chelating agent.

[0057] Next, a method for producing the sheet of the present invention will be described. The sheet of the present invention can be obtained, for example, by mixing the resin composition for forming the sheet of the present invention in a solvent onto a support, forming a varnish, applying the varnish, and drying the varnish to form a sheet.

[0058] The solvent used here may be appropriately selected from those that dissolve the above components, and examples include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone, ether solvents such as 1,4-dioxane, tetrahydrofuran, and diglyme, glycol ether solvents such as methyl cellosolve, ethyl cellosolve, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, and diethylene glycol methyl ethyl ether, as well as benzyl alcohol, propanol, N-methylpyrrolidone, γ-butyrolactone, ethyl acetate, and N,N-dimethylformamide. In particular, if the solvent contains a solvent having a boiling point of 120°C or less at atmospheric pressure, the solvent can be removed at a low temperature in a short time, making it easy to form the solvent into a sheet.

[0059] The method for converting the resin composition into a varnish is not particularly limited, but it is preferable to mix (A) a polymer having a siloxane skeleton, (B) an aluminum nitride filler, and other components that may be added as needed in the above-mentioned solvent using a propeller stirrer, homogenizer, kneader, or the like, and then mix them using a bead mill, ball mill, three-roll mill, or the like, from the viewpoint of improving the dispersibility of (B) the aluminum nitride filler.

[0060] Methods for applying the varnish to the support include spin coating using a spinner, spray coating, roll coating, screen printing, or coating methods using a blade coater, die coater, calendar coater, meniscus coater, bar coater, roll coater, comma roll coater, gravure coater, screen coater, slit die coater, etc.

[0061] The coating machine may be a roll coater, comma roll coater, gravure coater, screen coater, slit die coater, or the like, but a slit die coater is preferably used because it reduces solvent evaporation during coating and provides stable coating properties. The thickness of the sheeted resin composition (sheet) is not particularly limited, but is preferably in the range of 100 to 500 μm or less from the viewpoints of adhesion to the substrate, ease of handling the sheet, and heat dissipation.

[0062] Drying can be performed using an oven, a hot plate, infrared rays, or the like. The drying temperature and drying time may be within a range that allows the organic solvent to volatilize, and are preferably set appropriately within a range that leaves the sheet in an uncured or semi-cured state (B-stage state). Specifically, it is preferable to maintain the temperature in the range of 40°C to 120°C for one minute to several tens of minutes. Alternatively, the temperature may be increased stepwise using a combination of these temperatures; for example, heat treatment may be performed at 70°C, 80°C, and 90°C for one minute each.

[0063] The support is not particularly limited, and various commercially available films such as polyethylene terephthalate (PET) film, polyphenylene sulfide film, and polyimide film can be used.

[0064] The surface of the support to be bonded to the sheet may be surface-treated with silicone, a silane coupling agent, an aluminum chelating agent, polyurea, etc., to improve adhesion and releasability. The thickness of the support is not particularly limited, but is preferably in the range of 10 to 200 μm from the viewpoint of workability.

[0065] Furthermore, the laminate processed into a sheet may have a protective film to protect its surface, thereby protecting the sheet surface from pollutants such as dust and dirt in the atmosphere.

[0066] Examples of the protective film include a polyethylene film, a polypropylene (PP) film, a polyester film, etc. It is preferable that the protective film has a small adhesive strength with the laminate processed into a sheet.

[0067] Next, a method for bonding other members using the sheet of the present invention will be described with reference to an example.

[0068] If the sheet has a protective film, it is peeled off, and the sheet and another member are placed face-to-face and bonded together by pressure bonding. Examples of other members include thin metal plates such as aluminum, copper, and stainless steel (SUS), as well as semiconductor devices (such as their lead frame portions) to be bonded to them. Pressure bonding can be performed by applying heat, such as heat pressing, heat lamination, or thermal vacuum lamination. When applying heat, the bonding temperature is preferably 40°C or higher in terms of adhesion to the substrate and embeddability. Furthermore, since a high temperature during bonding shortens the time required for the sheet to harden and reduces workability, the bonding temperature is preferably 250°C or lower. If the sheet has a support, the support may be peeled off before bonding, or at any point during the thermocompression bonding process or after thermocompression bonding.

[0069] The substrate with the sheet thus obtained is then thermocompression bonded to another substrate or other member. The thermocompression temperature is preferably in the range of 100 to 400°C. The pressure during compression is preferably in the range of 0.01 to 10 MPa. The time is preferably from 1 second to several hours. The sheet is preferably cured during thermocompression bonding; for example, it is heat-treated at 100°C and a pressure of 0.5 MPa for 24 hours.

[0070] Alternatively, after thermocompression bonding, the sheet may be cured by heating to a temperature of 120°C to 400°C. This heat treatment is carried out by selecting a temperature and gradually increasing the temperature, or by selecting a temperature range and continuously increasing the temperature for 5 minutes to 24 hours. One example is heat treatment at 130°C and 200°C for 30 minutes each. Another method involves linearly increasing the temperature from room temperature to 250°C over 1 hour. In this case, the heating temperature is preferably 100°C or higher and 300°C or lower, and more preferably 120°C or higher and 200°C or lower.

[0071] The thus obtained sheet can reduce the contact thermal resistance at the interface with the substrate, and can be cooled to a lower temperature.

[0072] In this case, in order to reduce the thermal resistance of the sheet, the thermal conductivity of the sheet is preferably 0.8 W / m·K or more.

[0073] The tensile modulus of the sheet at 25°C is preferably 0.1 MPa or more and 1.5 MPa or less. If the tensile modulus of the sheet at 25°C is less than 0.1 MPa, the sheet is more likely to deform during adhesion, resulting in increased change in sheet thickness. If the tensile modulus of the sheet at 25°C exceeds 1.5 MPa, adhesion to the adherend during adhesion is reduced, increasing the likelihood of cracks occurring after curing.

[0074] The cured product of the present invention is a cured product obtained by curing the sheet of the present invention. Furthermore, the tensile modulus of the cured product of the sheet at 25°C is preferably 1.0 MPa or more and 100 MPa or less. From the viewpoint of improving the shear adhesive strength at low temperatures, the tensile modulus of the cured product of the sheet at 25°C is preferably 1.0 MPa or more, more preferably 2.0 MPa or more. Furthermore, from the viewpoint of reducing the thermal stress of the laminate at low temperatures and preventing peeling or cracking of the sheet or cured product, the tensile modulus is preferably 100 MPa or less, more preferably 50 MPa or less. The cured sheet desirably has a tensile modulus of elasticity at -60°C of 10 MPa or less.

[0075] The thickness of the cured product can be set arbitrarily, but is preferably 100 μm or more and 500 μm or less.

[0076] Next, an example of the use of the sheet of the present invention will be described, but the use of the resin composition and sheet of the present invention is not limited to the following.

[0077] The sheet of the present invention can be widely used as an adhesive sheet for electronic circuit boards and semiconductor devices that have many electronic components densely integrated. Even if the adherend of the sheet is made of a different material, it can be bonded due to the excellent adhesion provided by the high flexibility of the sheet. Generally, thermal cycle testing of semiconductor devices is performed in a temperature range of -55 to 150°C, and no peeling or cracking is required. The sheet of the present invention has high shear elongation over a wide temperature range, so it can be used as an adhesive even under low temperature conditions.

[0078] Furthermore, a cured adhesive obtained by curing a laminate in which a metal and a ceramic are bonded with a sheet can be used as a component for electronic devices such as semiconductor devices. That is, the cured adhesive of the present invention includes a laminate having a metal, the cured product of the present invention, and a ceramic, in this order. Examples of metals include aluminum, aluminum alloys, copper, copper alloys, titanium, and titanium alloys. Ceramics are required to have high thermal conductivity and durability. Examples of ceramic materials include polycrystalline inorganic materials such as Al2O3, AlN, SiC, YO3, and YAG. [Example]

[0079] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. Details of the raw materials indicated by abbreviations in each example are shown below.

[0080] <Polyimide raw material> X-22-168A: Polysiloxane modified with maleic anhydride at both ends (Shin-Etsu Chemical Co., Ltd.) BAHF: 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (manufactured by AZ Electronic Materials Co., Ltd.) X-22-161A: Amine-modified polysiloxane (Shin-Etsu Chemical Co., Ltd.) <Epoxy resin> YX7400N: Rubber elastic liquid epoxy resin (Mitsubishi Chemical Corporation) 630: Multifunctional epoxy resin (Mitsubishi Chemical Corporation) <Curing agent> X-22-161A: Diaminopolysiloxane (Shin-Etsu Chemical Co., Ltd.) <Spherical thermally conductive filler> FAN-f30: Aluminum nitride filler (average particle size: 30 μm, thermal conductivity: 170 W / m·K) (manufactured by Furukawa Denshi Co., Ltd.) FAN-f30A to FAN-f30J, which have different specific surface areas and bulk densities, were used.

[0081] AA3: Alumina particles (average particle size: 3 μm, specific surface area: 0.60 m 2 / g, thermal conductivity: 20 W / m K) (Sumitomo Chemical Co., Ltd.) AA04: Alumina particles (average particle size: 0.4 μm, specific surface area: 4.10 m 2 / g, thermal conductivity: 20 W / m K) (Sumitomo Chemical Co., Ltd.) The spherical thermally conductive fillers were confirmed to be spherical by observing the primary particles with a scanning electron microscope.

[0082] <Curing accelerator> 2P4MZ: 2-phenyl-4-methylimidazole (manufactured by Shikoku Chemicals Co., Ltd.) <Solvent> BDM: Diethylene glycol butyl methyl ether.

[0083] The evaluation methods used in each of the Examples and Comparative Examples are as follows.

[0084] [Polyimide evaluation] <Weight average molecular weight of polyimide> Using a solution of polyimide dissolved in N-methyl-2-pyrrolidone (hereinafter referred to as NMP) with a solids concentration of 0.1 wt%, the weight average molecular weight in terms of polystyrene was calculated using a GPC apparatus Waters 2690 (manufactured by Waters Corporation) with the configuration shown below. The GPC measurement conditions were as follows: the mobile phase was NMP in which LiCl and phosphoric acid were dissolved at concentrations of 0.05 mol / l, and the development rate was 0.4 ml / min. Detector: Waters996 System controller: Waters2690 Column oven: Waters HTR-B Thermocontroller: Waters TCM Column: TOSOH grard comn Column: THSOH TSK-GEL α-4000 Column: TOSOH TSK-GEL α-2500.

[0085] <Imidization rate of polyimide> First, the infrared absorption spectrum of the polymer was measured, and the absorption peak of the imide structure due to polyimide (1780 cm -1 Near 1377cm -1 Next, the polymer was heat-treated at 350°C for 1 hour, and then the infrared absorption spectrum was measured again. -1 The imidization rate of the polymer before the heat treatment was calculated by setting the imidization rate of the polymer after the heat treatment at 100%.

[0086] [Evaluation of thermally conductive fillers] <Average particle size of thermally conductive filler> The filler was dispersed in methanol, and the particle size distribution was measured by laser diffraction / scattering using an LA920 manufactured by Horiba, Ltd. The particle size D50, at which the cumulative particle size distribution from the small particle size side based on volume becomes 50%, was defined as the average particle size.

[0087] <Specific surface area of ​​thermally conductive filler> The specific surface area was measured by the single-point method using the BET flow method using a fully automatic specific surface area measuring device, Macsorb, manufactured by Mountec Co., Ltd.

[0088] <Bulk density of thermally conductive filler> Calculated in accordance with JIS R1634 (1998).

[0089] <Thermal conductive filler content> The weight of each component was divided by its specific gravity to calculate the volume, and the content of the thermally conductive filler relative to a total of 100 parts by volume of the polyimide resin, epoxy resin, siloxane diamine, and thermally conductive filler was calculated.

[0090] [Sheet Evaluation] <Thermal conductivity> The resin composition was applied to a 38 μm thick PET film using a comma roll coater so that the film thickness of the cured product was 250 μm. After drying at 125°C for 20 minutes, the resin composition was laminated using a roll laminator and thermally cured at 100°C for 1 hour and at 110°C for 24 hours to obtain a sheet-like laminate. The PET film was then peeled off, and the thermal diffusivity of the cured product was measured using a cyclic heating thermal diffusivity measurement device TA33 Professional manufactured by Bethel Hudson Laboratories, Inc. The specific gravity of the cured product was measured using the Archimedes method, and the specific heat of the sheet was measured using the DSC method. From the obtained measurements, the thermal diffusivity (m 2 / s) x specific gravity (kg / m 3 The thermal conductivity was calculated using the formula: ) × specific heat (J / kg·K).

[0091] <Tensile Modulus of Sheet and Cured Sheet> The resin composition was applied to a 38 μm-thick PET film using a comma roll coater to a cured film thickness of 250 μm. The film was dried at 125°C for 20 minutes, then laminated using a roll laminator and thermally cured at 100°C for 1 hour to obtain a sheet-like laminate. The PET film was then peeled off, and one piece was cut into a 10 x 20 mm piece. Another piece was cut into a 10 x 20 mm piece and thermally cured at 110°C for 24 hours. Tensile tests were performed on a Shimadzu AGX-V universal testing machine at a tension rate of 5.0 mm / min in an ambient atmosphere at 25°C or -60°C. The slope of the tensile elongation was measured in the range of 0 to 25%, and the tensile modulus was calculated.

[0092] <Shear adhesive strength, shear elongation, sheet thickness change> The resin composition was applied to a 38 μm-thick PET film using a comma roll coater to a cured film thickness of 250 μm. The film was then dried at 125°C for 20 minutes, laminated using a roll laminator, and thermally cured at 100°C for 1 hour to obtain a sheet-like laminate. The PET film was then peeled off, cut into 10 x 10 mm pieces, sandwiched between 50 x 15 mm, 1.6 mm-thick aluminum plates, and hot-pressed at 110°C and 0.03 MPa for 24 hours to measure the change in sheet thickness. The change in sheet thickness was preferably 10 μm or less to prevent changes in thermal conductivity. Shear tests were then performed in accordance with JIS K 6850 using a Shimadzu Corporation AGX-V universal testing machine at a tensile rate of 0.5 mm / min in an air atmosphere at 25°C, -60°C, or 150°C. The stress at the maximum stress was defined as the shear adhesive strength, and the elongation at the time of defining the shear adhesive strength was defined as the shear elongation, calculated from the shear test results. The shear failure mode was determined from the state of the sheet attached to the aluminum piece after the shear test. If the sheet components were attached to both aluminum surfaces, it was defined as cohesive failure, and if the sheet components were not attached to part or the entire surface of one side of the aluminum piece, it was defined as interfacial delamination.

[0093] Example 1 A 300 ml four-neck flask equipped with a stirrer, thermometer, nitrogen inlet tube, and dropping funnel was charged with 78.53 g of BDM and 40.40 g of X-22-168A under a nitrogen atmosphere and stirred to dissolve at 60°C. Subsequently, 7.33 g of BAHF and 30.80 g of X-22-161A were added while stirring at 60°C and stirred for 1 hour. The temperature was then raised to 180°C and stirred for 3 hours, after which the mixture was cooled to room temperature to obtain a polyimide A solution (solids concentration 80.0 wt%). The weight-average molecular weight of the polyimide was measured to be 71,991, and the imidization rate was measured to be 99%.

[0094] To 7.55 g of the polyimide solution A (6.04 g solids) obtained by the above method, 0.013 g of 630, 0.24 g of YX7400N, and 0.41 g of X-22-161A and 0.08 g of 2P4MZ were added and stirred. 13.2 g of FAN-f30A, 6 g of AA3, and 3 g of AA04 were added and stirred in a planetary stirring defoamer to obtain a viscous liquid resin composition. The resulting resin composition was coated onto PET film using a slit die coater to form a sheet. The thermal conductivity, tensile modulus, shear adhesive strength, and shear elongation were measured using the methods described above.

[0095] Example 2 A 300 ml four-neck flask equipped with a stirrer, thermometer, nitrogen inlet tube, and dropping funnel was charged with 78.53 g of BDM and 40.40 g of X-22-168A under a nitrogen atmosphere and stirred to dissolve at 60°C. Subsequently, 7.33 g of BAHF and 30.80 g of X-22-161A were added while stirring at 60°C and stirred for 1 hour. The temperature was then raised to 180°C and stirred for 3 hours, after which the mixture was cooled to room temperature to obtain a polyimide A solution (solids concentration 80.0 wt%). The weight-average molecular weight of the polyimide was measured to be 71,991, and the imidization rate was measured to be 99%.

[0096] To 7.55 g of polyimide solution A (6.04 g solids) obtained by the above method, 0.013 g of 630, 0.24 g of YX7400N, and 0.41 g of X-22-161A and 0.08 g of 2P4MZ were added and stirred. 13.2 g of FAN-f30B, 6 g of AA3, and 3 g of AA04 were added and stirred in a planetary stirring defoamer to obtain a viscous liquid resin composition. The resulting resin composition was coated onto PET film using a slit die coater to form a sheet. The thermal conductivity, tensile modulus, shear adhesive strength, and shear elongation were measured using the above methods.

[0097] Example 3 A 300 ml four-neck flask equipped with a stirrer, thermometer, nitrogen inlet tube, and dropping funnel was charged with 78.53 g of BDM and 40.40 g of X-22-168A under a nitrogen atmosphere and stirred to dissolve at 60°C. Subsequently, 7.33 g of BAHF and 30.80 g of X-22-161A were added while stirring at 60°C and stirred for 1 hour. The temperature was then raised to 180°C and stirred for 3 hours, after which the mixture was cooled to room temperature to obtain a polyimide A solution (solids concentration 80.0 wt%). The weight-average molecular weight of the polyimide was measured to be 71,991, and the imidization rate was measured to be 99%.

[0098] To 7.55 g of polyimide solution A (6.04 g solids) obtained by the above method, 0.013 g of 630, 0.24 g of YX7400N, and 0.41 g of X-22-161A and 0.08 g of 2P4MZ were added and stirred. 13.2 g of FAN-f30C, 6 g of AA3, and 3 g of AA04 were added and stirred in a planetary stirring defoamer to obtain a viscous liquid resin composition. The resulting resin composition was coated onto PET film using a slit die coater to form a sheet. The thermal conductivity, tensile modulus, shear adhesive strength, and shear elongation were measured using the methods described above.

[0099] Example 4 A 300 ml four-neck flask equipped with a stirrer, thermometer, nitrogen inlet tube, and dropping funnel was charged with 78.53 g of BDM and 40.40 g of X-22-168A under a nitrogen atmosphere and stirred to dissolve at 60°C. Subsequently, 7.33 g of BAHF and 30.80 g of X-22-161A were added while stirring at 60°C and stirred for 1 hour. The temperature was then raised to 180°C and stirred for 3 hours, after which the mixture was cooled to room temperature to obtain a polyimide A solution (solids concentration 80.0 wt%). The weight-average molecular weight of the polyimide was measured to be 71,991, and the imidization rate was measured to be 99%.

[0100] To 7.55 g of polyimide solution A (6.04 g solids) obtained by the above method, 0.013 g of 630, 0.24 g of YX7400N, and 0.41 g of X-22-161A and 0.08 g of 2P4MZ were added and stirred. 13.2 g of FAN-f30E, 6 g of AA3, and 3 g of AA04 were added and stirred in a planetary stirring defoamer to obtain a viscous liquid resin composition. The resulting resin composition was coated onto PET film using a slit die coater to form a sheet. The thermal conductivity, tensile modulus, shear adhesive strength, and shear elongation were measured using the above methods.

[0101] Example 5 A 300 ml four-neck flask equipped with a stirrer, thermometer, nitrogen inlet tube, and dropping funnel was charged with 78.53 g of BDM and 40.40 g of X-22-168A under a nitrogen atmosphere and stirred to dissolve at 60°C. Subsequently, 7.33 g of BAHF and 30.80 g of X-22-161A were added while stirring at 60°C and stirred for 1 hour. The temperature was then raised to 180°C and stirred for 3 hours, after which the mixture was cooled to room temperature to obtain a polyimide A solution (solids concentration 80.0 wt%). The weight-average molecular weight of the polyimide was measured to be 71,991, and the imidization rate was measured to be 99%.

[0102] To 7.55 g of the polyimide solution A (6.04 g solids) obtained by the above method, 0.013 g of 630, 0.24 g of YX7400N, and 0.41 g of X-22-161A and 0.08 g of 2P4MZ were added and stirred. 13.2 g of FAN-f30F, 6 g of AA3, and 3 g of AA04 were added and stirred in a planetary stirring defoamer to obtain a viscous liquid resin composition. The resulting resin composition was coated onto PET film using a slit die coater to form a sheet. The thermal conductivity, tensile modulus, shear adhesive strength, and shear elongation were measured using the methods described above.

[0103] Example 6 A 300 ml four-neck flask equipped with a stirrer, thermometer, nitrogen inlet tube, and dropping funnel was charged with 78.53 g of BDM and 40.40 g of X-22-168A under a nitrogen atmosphere and stirred to dissolve at 60°C. Subsequently, 7.33 g of BAHF and 30.80 g of X-22-161A were added while stirring at 60°C and stirred for 1 hour. The temperature was then raised to 180°C and stirred for 3 hours, after which the mixture was cooled to room temperature to obtain a polyimide A solution (solids concentration 80.0 wt%). The weight-average molecular weight of the polyimide was measured to be 71,991, and the imidization rate was measured to be 99%.

[0104] To 7.55 g of polyimide solution A (6.04 g solids) obtained by the above method, 0.013 g of 630, 0.24 g of YX7400N, and 0.41 g of X-22-161A and 0.08 g of 2P4MZ were added and stirred. 13.2 g of FAN-f30G, 6 g of AA3, and 3 g of AA04 were added and stirred in a planetary stirring defoamer to obtain a viscous liquid resin composition. The resulting resin composition was coated onto PET film using a slit die coater to form a sheet. The thermal conductivity, tensile modulus, shear adhesive strength, and shear elongation were measured using the above methods.

[0105] Example 7 A 300 ml four-neck flask equipped with a stirrer, thermometer, nitrogen inlet tube, and dropping funnel was charged with 78.53 g of BDM and 40.40 g of X-22-168A under a nitrogen atmosphere and stirred to dissolve at 60°C. Subsequently, 7.33 g of BAHF and 30.80 g of X-22-161A were added while stirring at 60°C and stirred for 1 hour. The temperature was then raised to 180°C and stirred for 3 hours, after which the mixture was cooled to room temperature to obtain a polyimide C solution (solids concentration 80.0 wt%). The weight-average molecular weight of the polyimide was measured to be 46,889, and the imidization ratio was measured to be 99%.

[0106] To 7.55 g of polyimide solution A (6.04 g solids) obtained by the above method, 0.013 g of 630, 0.24 g of YX7400N, and 0.41 g of X-22-161A and 0.08 g of 2P4MZ were added and stirred. 13.2 g of FAN-f30B, 6 g of AA3, and 3 g of AA04 were added and stirred in a planetary stirring defoamer to obtain a viscous liquid resin composition. The resulting resin composition was coated onto PET film using a slit die coater to form a sheet. The thermal conductivity, tensile modulus, shear adhesive strength, and shear elongation were measured using the above methods.

[0107] Example 8 A 300 ml four-neck flask equipped with a stirrer, thermometer, nitrogen inlet tube, and dropping funnel was charged with 78.53 g of BDM and 40.40 g of X-22-168A under a nitrogen atmosphere and stirred to dissolve at 60°C. Subsequently, 7.33 g of BAHF and 30.80 g of X-22-161A were added while stirring at 60°C and stirred for 1 hour. The temperature was then raised to 180°C and stirred for 3 hours, after which the mixture was cooled to room temperature to obtain a polyimide C solution (solids concentration 80.0 wt%). The weight-average molecular weight of the polyimide was measured to be 85,095, and the imidization ratio was measured to be 99%.

[0108] To 7.55 g of polyimide solution A (6.04 g solids) obtained by the above method, 0.013 g of 630, 0.24 g of YX7400N, and 0.41 g of X-22-161A and 0.08 g of 2P4MZ were added and stirred. 13.2 g of FAN-f30D, 6 g of AA3, and 3 g of AA04 were added and stirred in a planetary stirring defoamer to obtain a viscous liquid resin composition. The resulting resin composition was coated onto PET film using a slit die coater to form a sheet. The thermal conductivity, tensile modulus, shear adhesive strength, and shear elongation were measured using the methods described above.

[0109] Example 9 A 300 ml four-neck flask equipped with a stirrer, thermometer, nitrogen inlet tube, and dropping funnel was charged with 78.53 g of BDM and 40.40 g of X-22-168A under a nitrogen atmosphere and stirred to dissolve at 60°C. Subsequently, 7.33 g of BAHF and 30.80 g of X-22-161A were added while stirring at 60°C and stirred for 1 hour. The temperature was then raised to 180°C and stirred for 3 hours, after which the mixture was cooled to room temperature to obtain a polyimide D solution (solids concentration 80.0 wt%). The weight-average molecular weight of the polyimide was measured to be 26,230, and the imidization rate was measured to be 99%.

[0110] To 7.55 g of the polyimide solution A (6.04 g solids) obtained by the above method, 0.013 g of 630, 0.24 g of YX7400N, and 0.41 g of X-22-161A and 0.08 g of 2P4MZ were added and stirred. 13.2 g of FAN-f30F, 6 g of AA3, and 3 g of AA04 were added and stirred in a planetary stirring defoamer to obtain a viscous liquid resin composition. The resulting resin composition was coated onto PET film using a slit die coater to form a sheet. The thermal conductivity, tensile modulus, shear adhesive strength, and shear elongation were measured using the methods described above.

[0111] Example 10 A 300 ml four-neck flask equipped with a stirrer, thermometer, nitrogen inlet tube, and dropping funnel was charged with 78.53 g of BDM and 40.40 g of X-22-168A under a nitrogen atmosphere and stirred to dissolve at 60°C. Subsequently, 7.33 g of BAHF and 30.80 g of X-22-161A were added while stirring at 60°C and stirred for 1 hour. The temperature was then raised to 180°C and stirred for 3 hours, after which the mixture was cooled to room temperature to obtain a polyimide E solution (solids concentration 80.0 wt%). The weight-average molecular weight of the polyimide was measured to be 89,111, and the imidization ratio was measured to be 99%.

[0112] To 7.55 g of the polyimide solution A (6.04 g solids) obtained by the above method, 0.013 g of 630, 0.24 g of YX7400N, and 0.41 g of X-22-161A and 0.08 g of 2P4MZ were added and stirred. 13.2 g of FAN-f30F, 6 g of AA3, and 3 g of AA04 were added and stirred in a planetary stirring defoamer to obtain a viscous liquid resin composition. The resulting resin composition was coated onto PET film using a slit die coater to form a sheet. The thermal conductivity, tensile modulus, shear adhesive strength, and shear elongation were measured using the methods described above.

[0113] Comparative Example 1 A 300 ml four-neck flask equipped with a stirrer, thermometer, nitrogen inlet tube, and dropping funnel was charged with 78.53 g of BDM and 40.40 g of X-22-168A under a nitrogen atmosphere and stirred to dissolve at 60°C. Subsequently, 7.33 g of BAHF and 30.80 g of X-22-161A were added while stirring at 60°C and stirred for 1 hour. The temperature was then raised to 180°C and stirred for 3 hours, after which the mixture was cooled to room temperature to obtain a polyimide A solution (solids concentration 80.0 wt%). The weight-average molecular weight of the polyimide was measured to be 71,991, and the imidization rate was measured to be 99%.

[0114] To 7.55 g of the polyimide solution A (6.04 g solids) obtained by the above method, 0.013 g of 630, 0.24 g of YX7400N, 0.41 g of X-22-161A, and 0.08 g of 2P4MZ were added and stirred. To this mixture, 13.2 g of FAN-f30H, 6 g of AA3, and 3 g of AA04 were added and stirred in a planetary stirring degasser to obtain a viscous liquid resin composition. The resulting resin composition was measured for thermal conductivity, tensile modulus, shear adhesive strength, and shear elongation using the methods described above.

[0115] Comparative Example 2 A 300 ml four-neck flask equipped with a stirrer, thermometer, nitrogen inlet tube, and dropping funnel was charged with 78.53 g of BDM and 40.40 g of X-22-168A under a nitrogen atmosphere and stirred to dissolve at 60°C. Subsequently, 7.33 g of BAHF and 30.80 g of X-22-161A were added while stirring at 60°C and stirred for 1 hour. The temperature was then raised to 180°C and stirred for 3 hours, after which the mixture was cooled to room temperature to obtain a polyimide A solution (solids concentration 80.0 wt%). The weight-average molecular weight of the polyimide was measured to be 71,991, and the imidization rate was measured to be 99%.

[0116] To 7.55 g of the polyimide solution A (6.04 g solids) obtained by the above method, 0.013 g of 630, 0.24 g of YX7400N, and 0.41 g of X-22-161A and 0.08 g of 2P4MZ were added and stirred. 13.2 g of FAN-f30I, 6 g of AA3, and 3 g of AA04 were added and stirred in a planetary stirring defoamer to obtain a viscous liquid resin composition. The resulting resin composition was coated onto PET film using a slit die coater to form a sheet. The thermal conductivity, tensile modulus, shear adhesive strength, and shear elongation were measured using the methods described above.

[0117] Comparative Example 3 A 300 ml four-neck flask equipped with a stirrer, thermometer, nitrogen inlet tube, and dropping funnel was charged with 78.53 g of BDM and 40.40 g of X-22-168A under a nitrogen atmosphere and stirred to dissolve at 60°C. Subsequently, 7.33 g of BAHF and 30.80 g of X-22-161A were added while stirring at 60°C and stirred for 1 hour. The temperature was then raised to 180°C and stirred for 3 hours, after which the mixture was cooled to room temperature to obtain a polyimide A solution (solids concentration 80.0 wt%). The weight-average molecular weight of the polyimide was measured to be 71,991, and the imidization rate was measured to be 99%.

[0118] To 7.55 g of the polyimide solution A (6.04 g solids) obtained by the above method, 0.013 g of 630, 0.24 g of YX7400N, and 0.41 g of X-22-161A and 0.08 g of 2P4MZ were added and stirred. To this mixture, 13.2 g of FAN-f30J, 6 g of AA3, and 3 g of AA04 were added and stirred in a planetary stirring and defoaming machine to obtain a viscous liquid resin composition. The resulting resin composition was coated onto PET film using a slit die coater to form a sheet. The thermal conductivity, tensile modulus, shear adhesive strength, and shear elongation were measured using the methods described above.

[0119] [Table 1]

[0120] [Table 2]

[0121] [Table 3]

[0122] [Table 4]

[0123] [Table 5]

[0124] Figure 1 shows the average particle size of 30 μm and the specific surface area of ​​0.15 to 1.0 m 2 / g, bulk density 1.0 to 1.90 g / cm 3 The figure shows the results of a shear test at 25°C for a sheet containing FAN-f30, which has the same molecular weight as the polymer with a siloxane skeleton. The sheet containing FAN-f30 exhibits high thermal conductivity and achieves a shear elongation of 180%. The shear failure mode is cohesive failure.

[0125] Figure 2 shows the average particle size of 30 μm and the specific surface area of ​​0.15 to 1.0 m 2 / g, bulk density 1.0 to 1.90 g / cm 3 The results of shear tests at 25°C are shown for sheets containing FAN-f30, with different molecular weights of the polymer having a siloxane skeleton. The sheet containing the above-mentioned FAN-f30 has high thermal conductivity and achieves a shear elongation of 180%. Furthermore, as shown in Comparative Example 9 in Table 4, when the molecular weight of the polymer having a siloxane skeleton is less than 40,000, the fluidity increases and the amount of change in sheet thickness during adhesion increases. On the other hand, when the molecular weight of the polymer having a siloxane skeleton exceeds 100,000, the tackiness decreases, resulting in insufficient adhesion and interfacial peeling.

[0126] Figure 3 shows the average particle size of 30 μm and the specific surface area of ​​0.15 m 2 / g or less or bulk density of 1.90g / cm 3 The results of a shear test at 25°C for a sheet containing FAN-f30 exceeding 180% are shown below. The sheet containing FAN-f30 has high thermal conductivity, but its shear elongation does not reach 180%.

[0127] Figure 4 shows the average particle size of 30 μm and the specific surface area of ​​0.15 to 1.0 m 2 / g, bulk density 1.0 to 1.90 g / cm 3The results of a shear test at -60°C for a sheet containing FAN-f30 are shown below. The sheet containing FAN-f30 has high thermal conductivity and achieves a shear elongation of 180%, which is equal to or greater than the shear elongation at 25°C. The shear failure mode is cohesive failure.

[0128] Figure 5 shows the average particle size of 30 μm and the specific surface area of ​​0.15 to 1.0 m 2 / g, bulk density 1.0 to 1.90 g / cm 3 The results of a shear test at 150°C for a sheet containing FAN-f30 are shown below. The sheet containing FAN-f30 has high thermal conductivity and achieves a shear elongation of 180%, which is equal to or greater than the shear elongation at 25°C. The shear failure mode is cohesive failure.

Claims

1. A sheet comprising (A) a polymer having a siloxane skeleton and (B) an aluminum nitride filler, wherein (A) the polymer having a siloxane skeleton has a siloxane skeleton represented by general formula (1), and (B) the aluminum nitride filler has an average particle size of 25 to 80 μm and a specific surface area of ​​0.15 to 1.0 m ２ / g, bulk density is 1.0 to 1.90 g / cm ３ A sheet characterized by: 【Chemistry 1】 In general formula (1), R １ ~R ４ may be the same or different and represent an alkyl group having 1 to 30 carbon atoms, a phenyl group, or a phenoxy group. However, the phenyl group and the phenoxy group may be substituted with an alkyl group having 1 to 30 carbon atoms. １ and R ３ may be the same or different. ５ and R ６ may be the same or different and represent an alkylene group or an arylene group having 1 to 30 carbon atoms, provided that the arylene group may be substituted with an alkyl group having 1 to 30 carbon atoms. m is an integer selected from 1 to 100.

2. 2. The sheet according to claim 1, wherein the polymer (A) having a siloxane skeleton is a polyimide having a siloxane skeleton.

3. The sheet according to claim 1 , characterized in that the sheet contains an epoxy resin.

4. 2. The sheet according to claim 1, wherein the polymer (A) having a siloxane skeleton has a molecular weight of 40,000 or more and 100,000 or less.

5. 2. The sheet according to claim 1, wherein the sheet has a tensile modulus at 25°C of 0.1 MPa or more and 1.5 MPa or less.

6. A cured product obtained by curing the sheet according to any one of claims 1 to 5.

7. 7. The cured product according to claim 6, having a tensile modulus at 25°C of 1.0 MPa or more and 100 MPa or less.

8. A cured adhesive comprising a laminate having, in order, a metal, the cured product of claim 6, and a ceramic.

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