Insulating composition, thermosetting adhesive sheet, thermally conductive adhesive layer, coverlay layer, printed wiring board, and composite member

Abstract

To provide an insulating composition, a thermosetting adhesive sheet, a thermally conductive adhesive layer, and a composite member which are excellent in insulating properties, moisture resistance, heat resistance (solder reflow resistance), thermal conductivity, and adhesiveness.SOLUTION: The insulating composition of the present invention is a thermosetting composition and contains: a polyimide resin (A) containing acid anhydride group terminals, which is a reaction product of a tetracarboxylic acid dianhydride and a polyamine compound containing a dimer diamine; a curing agent (B); and a thermally conductive filler (C). The insulating composition contains boron nitride (c1) having a tap density of 0.4 g / cm3 or more as the thermally conductive filler (C).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a thermosetting insulating composition containing a polyimide resin. It also relates to a thermosetting adhesive sheet, a thermally conductive adhesive layer, and a composite member.

Background Art

[0002] With the development of high performance, high density, and thinness of electronic components mounted on electronic devices, high performance materials are also required for resin compositions used as insulating materials, encapsulating materials, adhesive materials, protective materials, etc. for electronic components.

[0003] For example, in Patent Document 1, a thermosetting adhesive sheet excellent in reworkability, adhesiveness, flexibility, electrical insulation, etc. is provided as an issue, and a resin selected from specific types, a curing agent that cures with the resin, and a specific amount of an alkali metal compound are blended. A thermosetting adhesive sheet has been proposed. Further, in Patent Document 2, a polyamide resin or a polyamideimide resin having a Tg of 150 ° C. or lower obtained by polycondensing an acid containing dimer acid and a diamine and / or diisocyanate is provided as an issue of providing an adhesive composition having all of low temperature adhesiveness, thermal fluidity, and reliability after heat curing. A polycondensation polymer selected from the above and an adhesive composition containing a thermosetting resin have been proposed.

[0004] Furthermore, in Patent Document 3, a binder resin selected from a polyether sulfone resin or a polyimide resin having the following general formula (α), a thermosetting resin, a curing agent, a thermally conductive filler, and an adhesive composition containing a titanium oxide filler having a specific average particle diameter is disclosed as an issue of providing an adhesive composition excellent in thermal conductivity, high light reflectance, heat resistance, and insulation.

Chemical Formula

[0005] Further, Patent Document 4 discloses a heat dissipation sheet comprising a heat dissipation filler and an imide-modified elastomer having a polyurethaneimide structure, with the problem of providing a heat dissipation sheet excellent in heat dissipation properties and dimensional stability at high temperatures.

[0006] Thermosetting resin compositions can temporarily fix between dissimilar members or parts before curing and function as an insulating layer after thermosetting treatment. However, there is a demand for resin compositions having excellent insulation reliability that can cope with the recent high density and narrow pitch of wirings in electronic components. In addition, in the manufacturing process of semiconductor packages, they are exposed to a high temperature of about 200 to 300 °C in the reflow process, and there is a demand for resin compositions having excellent adhesive strength even after such a high-temperature heat history.

[0007] The applications of electronic components are diverse. For example, when mounted on in-vehicle electronic devices, they may be used under severe conditions of high humidity, and there is a demand for resin compositions with high reliability even in a high-humidity environment. Furthermore, with the recent miniaturization and high power of electronic components, the amount of heat generated from heat sources has increased. In addition to excellent heat resistance, there is a demand for resin compositions with high thermal conductivity that can efficiently dissipate the heat inside electronic components to prevent malfunction due to heat generation.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0009] If a material that exhibits excellent adhesiveness while having insulation reliability, moisture resistance, heat resistance, and thermal conductivity can be provided, it can be expected to be used as an alternative material for conventional adhesive layers and to improve the performance of electronic components. In addition, a material with excellent handleability can be provided for applications other than adhesive layers. However, when a large amount of a thermal conductive filler is contained in a resin, although the thermal conductivity is improved, other properties such as adhesiveness tend to deteriorate. In the market, there is a demand for an insulating composition that can provide a material having excellent insulation, thermal conductivity, heat resistance, moisture resistance, and adhesiveness in a well-balanced manner.

[0010] In the above, the problems of the resin composition used for electronic components have been described, but similar problems can occur in all applications where insulation reliability, moisture resistance, heat resistance, thermal conductivity, and adhesiveness are required.

[0011] The present invention has been made in view of the above background, and an object thereof is to provide an insulating composition, a thermosetting adhesive sheet, a thermal conductive adhesive layer, and a composite member that are excellent in insulation, moisture resistance, heat resistance (solder reflow resistance), thermal conductivity, and adhesiveness.

Means for Solving the Problems

[0012] As a result of intensive studies by the present inventors, it has been found that the problems of the present invention can be solved in the following aspects, and the present invention has been completed. [1]: A thermosetting insulating composition containing a polyimide resin (A) which is a reaction product of a tetracarboxylic dianhydride and a polyamine compound containing a dimer diamine, a curing agent (B), and a thermal conductive filler (C), As the thermal conductive filler (C), boron nitride (c1) having a tap density of 0.4 g / cm 3 or more is included [2]: The tetracarboxylic dianhydride has the general formula (1):​ [Chemical formula] (X 1 is a tetravalent tetracarboxylic dianhydride residue and has at least one substituted or unsubstituted aromatic ring.) The insulating composition according to [1], comprising the compound represented by [3]: The insulating composition according to [1] or [2], wherein the content of the dimeric diamine contained in 100% by mass of the polyamine compound is 50 to 100% by mass. [4]: The insulating composition according to any one of [1] to [3], wherein the content of the hydrocarbon group having 20 to 60 carbon atoms derived from the dimeric diamine contained in the polyimide resin (A) is 30 to 90% by mass. [5]: The insulating composition according to any one of [1] to [4], wherein the weight average molecular weight of the polyimide resin (A) is 5,000 to 150,000. [6]: The insulating composition according to any one of [1] to [5], wherein the curing agent (B) contains an epoxy compound (b1). [7]: The insulating composition according to [6], wherein the epoxy compound (b1) has any one of a hydroxyl group, a secondary amino group, and a tertiary amino group and has two or more epoxy groups. [8]: The insulating composition according to any one of [1] to [7], wherein the average particle diameter D50 of the boron nitride (c1) is 10 to 100 μm. [9]: The insulating composition according to any one of [1] to [8], wherein the content of the boron nitride (c1) contained in 100% by volume of the heat conductive filler (C) is 40 to 100% by volume.

[10] : A thermosetting adhesive sheet formed from the insulating composition according to any one of [1] to [9].

[11] : The thermosetting adhesive sheet according to

[10] , which may have voids, wherein when having voids, the porosity is 45% by volume or less, and the heat conductive filler (C) is contained in an amount of 55 to 90% by volume based on 100% by volume of the composition excluding the voids.

[12] : A thermally conductive adhesive layer which is a cured product of the thermosetting adhesive sheet according to claim 11, wherein the porosity of the cured product is equal to or less than the porosity before curing and is 15% by volume or less.

[13] : The thermally conductive adhesive layer according to

[12] , having a thickness of 50 to 250 μm.

[14] : A heat generating member capable of generating heat, a heat dissipation base substrate for dissipating the heat of the heat generating member, and a thermally conductive adhesive layer for joining the heat generating member and the heat dissipation base substrate, wherein the thermally conductive adhesive layer is a cured product of the thermosetting adhesive sheet according to

[10] or

[11] .

[15] : The composite member according to

[14] , wherein at least a part of the joint between the heat generating member and the heat dissipation base substrate is copper, and at least a part of the joint between the heat dissipation base substrate and the heat generating member is copper or aluminum. [Advantages of the Invention]

[0013] According to the present invention, there is an excellent effect that an insulating composition, a thermosetting adhesive sheet, a thermally conductive adhesive layer, and a composite member excellent in insulation, moisture resistance, heat resistance (solder reflow resistance), thermal conductivity, and adhesiveness can be provided. [Embodiments for Carrying Out the Invention]

[0014] Hereinafter, the present invention will be described in detail. Needless to say, other embodiments are also included in the scope of the present invention as long as they conform to the gist of the present invention. In addition, in this specification, the numerical range specified using "~" includes the numerical values described before and after "~". In this specification, "film" and "sheet" are not distinguished by thickness. In addition, various components appearing in this specification may be used alone or in combination of two or more as long as they are not particularly noted.

[0015] [[Insulating Composition]] The insulating composition according to this embodiment is a thermosetting composition, and contains a polyimide resin (A) which is a reaction product of a tetracarboxylic dianhydride and a polyamine compound containing a dimer diamine, a curing agent (B), and a thermal conductivity filler (C). And the thermal conductivity filler (C) contains boron nitride (c1) having a tap density of 0.4 g / cm 3 or more.

[0016] Here, the "thermal conductivity filler (C)" refers to particles that are added to the insulating composition and have enhanced thermal conductivity when formed into a cured product. Also, a thermosetting type refers to a composition that forms a three-dimensional crosslinked structure of the resin by heat curing treatment and cures. In this specification, the cured product refers to a state cured to such an extent that the curing reaction does not substantially proceed even when further heated. When molding the insulating composition into a desired shape such as a sheet, although a part of it can undergo a curing reaction, a state where it can be cured by further heating is not included in the cured product referred to here. At the stage of the insulating composition, a part of the components may be in a B-stage state where they are semi-cured.

[0017] The insulating composition of this embodiment can be, for example, in a powder form, film form, sheet form, plate form, pellet form, paste form or liquid form. The liquid or paste-like insulating composition can be easily obtained by adjusting the viscosity using a solvent. Also, the film-like, sheet-like, and plate-like insulating compositions can be formed, for example, by coating and drying a liquid or paste-like insulating composition. Further, the powder-like and pellet-like insulating compositions can be obtained, for example, by pulverizing or dividing the insulating composition in the form of the film or the like into a desired size.

[0018] According to the insulating composition of this embodiment, a polyimide resin (A) which is a reaction product of a tetracarboxylic dianhydride and a polyamine compound containing a dimer diamine, a curing agent (B), and a tap density of 0.4 g / cm 3By containing the above-mentioned boron nitride (c1)-containing thermally conductive filler (C), an insulating composition excellent in the insulating properties and adhesiveness of its cured product can be obtained. Further, the cured product is excellent in moisture resistance, heat resistance (solder reflow resistance), and thermal conductivity. Although the reason is not clear, the dimer structure further promotes the suppression of the packing around the imide ring of the polyimide resin (A) to promote the uniform dispersion of the imide ring, and the tap density is 0.4 g / cm 3 By combining with the above-mentioned boron nitride (c1)-containing thermally conductive filler (C), the dispersibility of the thermally conductive filler (C) when formed into a cured product is remarkably improved, and it is considered that an insulating composition having adhesiveness, thermal conductivity, moisture resistance, and insulating properties after solder reflow is obtained. Hereinafter, each component of the insulating composition of the present embodiment will be described in detail.

[0019] [Polyimide resin (A)] The polyimide resin (A) is a reaction product of a tetracarboxylic dianhydride and a polyamine compound containing a dimer diamine. It can be obtained by various known polymerization methods, but it is important to use the aforementioned tetracarboxylic dianhydride and polyamine compound as raw materials. Although it is also possible to obtain a polyimide resin by reacting a polyisocyanate compound with a tetracarboxylic dianhydride instead of the polyamine compound, as a result of intensive studies by the present inventors, it has been found that the adhesiveness can be effectively improved by using a polyamine compound.

[0020] As a preferred example of the production method, a monomer containing a tetracarboxylic dianhydride and a polyamine compound is dissolved in a solvent and polymerized by stirring at a temperature of, for example, 60 to 120°C for 0.1 to 2 hours to produce a polyamic acid resin which is a polyimide precursor, and a method of cyclizing by heating to convert it into an imide group can be exemplified. In 100 mol% of the polyamine compound, the diamine compound is preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, and particularly preferably 98 mol% or more.

[0021] Examples of the organic solvent used for the polymerization include N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, and cresol. The solvent may be used alone or in combination of two or more kinds. Aromatic hydrocarbons such as xylene and toluene may be used in combination.

[0022] The method for imidizing the polyimide precursor to obtain the polyimide resin is not particularly limited, and examples thereof include heating at a temperature of 80 to 400 °C for 0.5 to 50 hours in a solvent. At this time, a catalyst and / or a dehydrating agent may be used as necessary.

[0023] Examples of the reaction catalyst include aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as dimethylaniline, and heterocyclic tertiary amines such as pyridine, picoline, and isoquinoline. Examples of the dehydrating agent include aliphatic acid anhydrides such as acetic anhydride and aromatic acid anhydrides such as benzoic anhydride.

[0024] The imidization ratio (formation ratio of imide ring) is not limited, but from the viewpoint of effectively exerting the effect of long-term heat resistance, it is preferably 80% or more, more preferably 90% or more, and still more preferably 95 to 100%. The imidization ratio can be determined by NMR, IR analysis, or the like.

[0025] (Molecular chain end) The molecular chain ends of the polyimide resin (A) are not limited. From the viewpoint of improving the pot life when made into a sheet, it is preferably to contain an acid anhydride group. The method for introducing an acid anhydride group to the molecular chain ends of the polyimide resin (A) is not particularly limited. As a simple method, a method of blending more polymerizable functional groups of a tetracarboxylic dianhydride than those of a polyamine compound can be exemplified. Depending on the desired weight average molecular weight, for example, the equivalent ratio of the polymerizable functional groups of the tetracarboxylic dianhydride / the polymerizable functional groups of the polyamine compound can be adjusted in the range exceeding 1.0 and not exceeding 5.0. More preferably, it is 1.01 to 3.0, and still more preferably, it is 1.02 to 2.0. Instead of the above method, after producing a polyimide precursor having an equivalent ratio of the polymerizable functional groups of the tetracarboxylic dianhydride / the polymerizable functional groups of the polyamine compound of 1 or less than 1, an acid anhydride group may be introduced to the end. Incidentally, the tetracarboxylic dianhydride and the polyamine compound may each independently be used alone or in combination of two or more.

[0026] In addition to the combination of the polyimide resin (A) having a dimer structure and the thermally conductive filler (C) containing boron nitride (c1) having a tap density of a specific value or more, further, by having an acid anhydride group at the molecular chain ends, the uniform dispersibility of the polyimide resin (A) itself can be more effectively enhanced, and the dispersibility with the thermally conductive filler (C) can be significantly enhanced. Further, the combination of the dimer structure and the ring structure due to the acid anhydride group at the molecular chain ends inhibits the packing property around the highly planar imide ring, and at the same time, the flexibility is enhanced by the synergistic effect due to the enhanced interaction between the molecular chain ends and the imide ring, and it is considered that the adhesiveness, moisture resistance, heat resistance, etc. are excellent. From the related aspect of effectively bringing out these effects, it is preferable that 80 to 100% of the molecular chain ends are acid anhydride groups, and it is still more preferable that 90 to 100% are acid anhydride groups. Incidentally, the "acid anhydride group" means a group represented by -C(=O)-O-C(=O)-.

[0027] The polyimide resin (A) may contain molecular chain ends having no functional groups. For example, a part of the acid anhydride groups at the molecular chain ends can be blocked with a monoamine compound to reduce the number of functional groups of the acid anhydride groups. According to this method, the amount of the acid anhydride groups at the molecular chain ends of the polyimide resin (A) can be easily adjusted. In addition, the molecular chain ends of the polyimide resin (A) may have functional groups other than the acid anhydride groups as long as the gist of the present invention is not deviated from.

[0028] (Tetracarboxylic dianhydride) The tetracarboxylic dianhydride is not particularly limited, and specific examples include pyromellitic dianhydride, 1,4-difluoro-pyromellitic dianhydride, 2,5-trifluoromethylpyromellitic dianhydride, trifluoromethylpyromellitic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-anthracenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 3,3',4,4'-diphenylmethane tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, ethylene glycol dibenzoate tetracarboxylic dianhydride, benzene-1,4-diylbis(1,3-oxo-1,3-dihydro-2-benzofuran-5-carboxylate), 4,4'-[propane-2,2-diylbis(1,4-phenyleneoxy)]diphthalic dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride. In addition, cyclo, bicyclo, and tricyclotetracarboxylic acids such as 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-pentanetetracarboxylic acid, 1,2,4,5-pentanetetracarboxylic acid, 1,2,3,4-hexanetetracarboxylic acid, 1,2,5,6-hexanetetracarboxylic acid, cyclobutane-1,2,3,4-tetracarboxylic acid, cyclopentane-1,2,3,4-tetracarboxylic acid, cyclohexane-1,2,3,4-tetracarboxylic acid, cyclohexane-1,2,4,5-tetracarboxylic acid, 1-carboxymethyl-2,3,5-cyclopentanetricarboxylic acid, 3-carboxymethyl-1,2,4-cyclopentanetricarboxylic acid, rel-dicyclohexyl-3,3’,4,4’-tetracarboxylic acid, tricyclo[4.2.2.02,5]dec-9-ene-3,4,7,8-tetracarboxylic acid, 5-carboxymethylbicyclo[2.2.1]heptane-2,3,6-tricarboxylic acid, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid, bicyclo[2.2.2]oct-7-ene-2,3,6,7-tetracarboxylic acid, bicyclo[3.3.0]octane-2,4,6,7-tetracarboxylic acid, 7,8-diphenylbicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid, 4,8-diphenyl-1,5-diazabicyclooctane-2,3,6,7-tetracarboxylic acid, 9-oxatricyclo[4.2.1.02,5]nonane-3,4,7,8-tetracarboxylic acid, 9,14-dioxopentacyclo[8.2.11,11.14,7.02,10.03,8]tetradecane-5,6,12,13-tetracarboxylic acid; spiro ring-containing tetracarboxylic acids such as 2,8-dioxaspiro[4.5]decane-1,3,7,9-tetrone; and tetracarboxylic dianhydrides having an alicyclic hydrocarbon structure such as 1,3,3a,4,5,9b-hexahydro-5(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-c]furan-1,3-dione can be exemplified.

[0029] Preferable examples of the tetracarboxylic dianhydride include the general formula (1):

Chemical formula

[0030] As a more preferred example, general formula (2):

Chemical formula

Chemical formula

Chemical formula

[0031] Particularly preferred examples include 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylethertetracarboxylic dianhydride, 4,4'-[propane-2,2-diylbis(1,4-phenyleneoxy)]diphthalic dianhydride, and 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride.

[0032] (Polyamine compound) The polyamine compound has at least a dimer diamine. The dimer diamine is a diamine compound having a dimer structure (also referred to as a dimer skeleton). Here, the "dimer structure" is a structure derived from a dimer of a fatty acid (hereinafter referred to as a fatty acid dimer). As the dimer diamine, a compound obtained by converting the carboxyl group of the dimer acid into an amino group can be used. Examples of the conversion method include a method of amidating a carboxylic acid, aminating it by Hofmann rearrangement, and further performing distillation and purification. The dimer acid is a polybasic acid having a dimer structure and is a fatty acid dimer. This fatty acid dimer preferably has 20 to 60 carbon atoms, more preferably 24 to 56 carbon atoms, still more preferably 28 to 48 carbon atoms, and particularly preferably 36 to 44 carbon atoms. The fatty acid dimer is preferably a dicarboxylic acid compound having a branched structure obtained by subjecting a fatty acid to a Diels-Alder reaction. The branched structure preferably has an aliphatic chain and a ring structure, and more preferably a ring structure. The ring structure preferably has one or more aromatic rings or alicyclic structures, and more preferably an alicyclic structure. The alicyclic structure may or may not have a double bond in the ring.

[0033] The dimer diamine is not particularly limited, but the dimer diamine is preferably a compound having 20 to 60 carbon atoms, more preferably a compound having 24 to 56 carbon atoms, still more preferably a compound having 28 to 48 carbon atoms, and still more preferably a compound having 36 to 44 carbon atoms. The dimer diamine having such a carbon number is preferable from the viewpoint of easy availability.

[0034] Commercially available products of dimer diamine include, for example, "Priamine 1071", "Priamine 1073", "Priamine 1074", "Priamine 1075" manufactured by Croda Japan, and "Versamine 551" manufactured by BASF Japan. The dimer diamine can be used alone or in combination of two or more.

[0035] Incidentally, examples of the polybasic acid having a dimer structure for obtaining the dimer diamine include the structures represented by the following chemical formulas (d1) to (d4). Needless to say, the polybasic acid having a dimer structure is not limited to the following structures.

[0036]

Chemical formula

[0037]

Chemical formula

[0038]

Chemical formula

[0039]

Chemical formula

[0040] The dimer structure is a structure with few interactions between molecular chains having a plurality of hydrocarbon chains and ring structures. By including the dimer structure in the polyimide resin (A), internal stress generated in the resin composition during curing can be relaxed. Due to the stress relaxation by the dimer structure contained in the polyimide resin (A), a decrease in adhesive strength and the occurrence of cracks caused by stress generated by repeated high and low temperatures can be suppressed. Therefore, heat resistance and moisture resistance can be effectively enhanced.

[0041] As the polyamine compound, the dimer diamine may be used alone, or the dimer diamine and other polyamine compounds may be used in combination. The other polyamine compounds are not particularly limited. Specifically, there are diamine compounds having an aliphatic structure (which may contain an unsaturated bond, a chain hydrocarbon structure and / or an alicyclic hydrocarbon structure), an aromatic ring, and any combination thereof, which may have a substituent. When a diamine having a phenolic hydroxyl group is used as the other diamine, a phenolic hydroxyl group can be introduced into the polyimide resin (A). By using the polyimide resin (A) having a phenolic hydroxyl group, the crosslinking points with the curing agent (B) can be adjusted and the three-dimensional crosslinked structure can be adjusted, so that a tough cured product can be obtained.

[0042] Other diamine compounds include, for example, aromatic diamines such as 1,4-diaminobenzene, 1,3-diaminobenzene, 1,2-diaminobenzene, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 2,3-diaminonaphthalene, 2,6-diaminotoluene, 2,4-diaminotoluene, 3,4-diaminotoluene, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diamino-1,2-diphenylethane, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,3'-diaminodiphenyl sulfone; aliphatic diamines such as ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,9-nonanediamine, 1,12-dodecamethylenediamine, metaxylylenediamine; alicyclic diamines such as isophoronediamine, norbornanediamine, 1,2-cyclohexanediamine, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 4,4'-diaminodicyclohexylmethane, piperazine, etc.

[0043] The diaminophenol compound is a phenol having two amino groups. Examples of the diaminophenol include diamines represented by the following general formula (5).

[0044]

Chemical formula

[0045] R in formula (5) 1represents a direct bond or a group containing carbon, hydrogen, oxygen, nitrogen, sulfur, or halogen. The group is, for example, a divalent hydrocarbon group having 1 to 30 carbon atoms or a divalent hydrocarbon group having 1 to 30 carbon atoms in which part or all of the hydrogen atoms are substituted by halogen atoms, -(C=O)-, -SO2-, -O-, -S-, -NH-(C=O)-, -(C=O)-O-, a group represented by the following general formula (6), and a group represented by the following general formula (7). In the formulae, r and s each independently represent an integer of 1 to 20, and R in formula (7) 2 represents a hydrogen atom or a methyl group.

[0046]

Chemical formula

[0047]

Chemical formula

[0048] The diamine represented by the general formula (5) includes, for example, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 9,9-bis(3-amino-4-hydroxyphenyl)fluorene, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, 4,4'-diamino-3,3'-dihydroxybiphenyl, and the like.

[0049] Among these, as other diamines, isophoronediamine or norbornanediamine is preferable in terms of further improving the adhesive strength and heat cycle resistance.

[0050] Also, a polyamine compound having three or more amino groups may be used. Examples of the polyamine compound having three or more amino groups include 1,2,4-triaminobenzene and 3,4,4'-triaminodiphenyl ether.

[0051] It is preferable to use a dimer diamine content of 50 to 100% by mass based on 100% by mass of the polyamine compound used for synthesizing the polyimide resin (A). More preferably, it is 70 to 100% by mass, and still more preferably, it is 90 to 100% by mass. By using 50 to 100% by mass, the effect of inhibiting the packing property around the imide ring with high planarity due to the dimer structure can be fully exerted.

[0052] Also, the content of the hydrocarbon group having 20 to 60 carbon atoms derived from the dimer diamine contained in the polyimide resin (A) is preferably 30 to 90% by mass. More preferably, it is 35 to 85% by mass, and still more preferably, it is 40 to 70% by mass. By using 30 to 90% by mass, the effect of inhibiting the packing property around the imide ring with high planarity due to the dimer structure can be fully exerted.

[0053] (Weight average molecular weight) The weight average molecular weight of the polyimide resin (A) is not particularly limited, but for example, it can be in the range of 5,000 to 200,000. Considering adhesiveness, dispersibility of the heat conductive filler (C), moisture resistance, heat resistance, etc., it is preferably 5,000 to 150,000, more preferably 7,500 to 125,000, and still more preferably 10,000 to 100,000.

[0054] [Curing agent (B)] The "curing agent (B)" refers to a compound having two or more reactive functional groups in one molecule and capable of constructing a crosslinked structure. The curing agent (B) is one or more selected from epoxy compounds (b1), isocyanate compounds, polycarbodiimide compounds, aziridine compounds, dicyandiamide compounds, amine compounds such as aromatic diamine compounds, phenol compounds such as phenol novolak resins, organometallic compounds, etc. The curing agent (B) may be a low molecular compound or a high molecular compound.

[0055] The curing agent (B) may be a compound that exhibits thermosetting properties itself, or it may be a compound that crosslinks with the polyimide resin (A). When crosslinking with the polyimide resin (A), in addition to the acid anhydride groups of the polyimide resin (A), there are also modes in which the functional groups contained in the side chains and side groups of the polyimide resin (A) crosslink with the curing agent (B). These may be arbitrarily combined.

[0056] <Epoxy compound (b1)> The epoxy compound (b1) refers to a compound having two or more epoxy groups in one molecule, and known compounds can be used. For example, gly Shiji ceryl ether type epoxy compound, gly Shiji cerylamine type epoxy compound, glycidyl ester type epoxy compound, cyclic aliphatic (alicyclic) epoxy compound, etc. can be mentioned.

[0057] Examples of the glycidyl ether type epoxy compound include bisphenol A type epoxy compound, bisphenol F type epoxy compound, bisphenol S type epoxy compound, bisphenol AD type epoxy compound, cresol novolak type epoxy compound, phenol novolak type epoxy compound, α-naphthol novolak type epoxy compound, bisphenol A type novolak type epoxy compound, dicyclopentadiene type epoxy compound, tetrabromobisphenol A type epoxy compound, brominated phenol novolak type epoxy compound, tris(glycidyloxyphenyl)methane, tetrakis(glycidyloxyphenyl)ethane, etc.

[0058] Examples of the glycidylamine type epoxy compound include tetraglycidyldiaminodiphenylmethane, triglycidyl para-aminophenol, triglycidyl meta-aminophenol, tetraglycidyl metaxylylenediamine, etc.

[0059] Examples of the glycidyl ester type epoxy compound include diglycidyl phthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, etc.

[0060] Examples of the cyclic aliphatic (alicyclic) epoxy compound include epoxycyclohexylmethyl-epoxycyclohexanecarboxylate, bis(epoxycyclohexyl)adipate, etc. Also, a liquid epoxy compound can be preferably used.

[0061] Among these, those having other functional groups in addition to the epoxy group are preferable. For example, as the other functional groups, a hydroxyl group, a secondary amino group, and a tertiary amino group can be exemplified. By using an epoxy compound (b1) having such other functional groups in addition to a difunctional or higher epoxy group, the crosslink density under predetermined curing conditions can be effectively increased, and the heat resistance can be enhanced. Furthermore, since the metal adhesiveness derived from the hydroxyl group and the amino group can be enhanced, good heat resistance and adhesiveness can be satisfied simultaneously.

[0062] The content ratio (mass ratio) of the polyimide resin (A) and the epoxy compound (b1) is preferably (A):(b1)=98:2 to 40:60, more preferably 95:5 to 50:50. By setting the above ratio, the heat resistance can be further improved. The epoxy compound (b1) can be used alone or in combination of two or more. The same applies to the other curing agent (B). Also, the epoxy compound (b1) and the other curing agent (B) can be optionally used in combination.

[0063] [Thermally conductive filler (C)] The insulating composition of this embodiment contains a thermally conductive filler (C). Also, as the thermally conductive filler (C), the tapped density is 0.4 g / cm 3It contains boron nitride (c1) as described above. Boron nitride (c1) may be used alone as the thermal conductivity filler (C), or may be used in combination with other fillers. The tapped density refers to the bulk density of the filler when, after dispersing the filler in a predetermined container and putting it into the container, an impact by tapping is applied to the container until the volume change of the filler ceases, and is obtained as the mass per unit volume of the powder in the vibrated container. The measurement of the tapped density can be carried out in accordance with the method for measuring the bulk density of fine ceramic powders specified in JIS R 1628:1997.

[0064] The tapped density of boron nitride (c1) is preferably 0.45 g / cm 3 or more, more preferably 0.5 g / cm 3 or more, still more preferably 0.60 g / cm 3 or more, particularly preferably 0.7 g / cm 3 or more. Although the upper limit value of the tapped density is not particularly limited, considering the ease of acquisition, the upper limit value is preferably 1.4 g / cm 3 more preferably 1.3 g / cm 3 and still more preferably 1.2 g / cm 3 is.

[0065] The thermal conductivity filler (C) preferably has a thermal conductivity of 5 W / (m·K) or more for the filler itself. More preferably 10 W / (m·K) or more, and still more preferably 20 W / (m·K) or more. By setting it to 5 W / (m·K) or more, the thermal conductivity effect can be effectively enhanced.

[0066] By setting the tapped density to 0.4 g / cm 3 or more, the dispersibility with respect to the polyimide resin (A) can be remarkably enhanced. As a result, it is possible to have both the characteristics of improving the thermal conductivity by increasing the filling rate and the trade-off with the adhesive strength.

[0067] Boron nitride (c1) may be used as primary particles, or secondary particles formed by aggregation of primary particles may also be used. More preferably, it is an aggregate in which primary particles are aggregated. Also, secondary particles of boron nitride sintered by heating may be used. The shape of boron nitride (c1) is not particularly limited, and examples thereof include spherical, fibrous, needle-like, flaky, and aggregates thereof. Since flaky boron nitride particles have thermal conductivity anisotropy, a granulated body obtained by granulating flaky primary particles or an aggregate thereof is preferably used. By using boron nitride of the granulated body or its aggregate, good thermal conductivity can be exhibited in both the thickness direction of the sheet after heating and pressing of the thermosetting adhesive sheet.

[0068] The average particle diameter D50 of boron nitride (c1) is preferably 10 to 100 μm. More preferably, it is 15 to 90 μm, and still more preferably, it is 20 to 80 μm. By setting it to 10 to 100 μm, the thermal conductivity curing can be enhanced while enhancing the dispersibility in the matrix. Note that the average particle diameter D50 indicates the particle diameter at a cumulative degree of 50% in the volume-standard particle size distribution. Specifically, a laser diffraction particle size distribution measuring device (SALD-2200, manufactured by Shimadzu Corporation) was used as the measuring device, and Wing SALD-2200 was used as the measurement control software.

[0069] The insulating composition of the present embodiment is thermally cured and used as a cured product as described later. In the state of the cured product, it is preferable that the thermal conductivity filler (C) is highly dispersed in the three-dimensional crosslinked resin serving as the matrix. In addition to the mode of dispersing the thermal conductivity filler (C) non-oriented, it may be dispersed with orientation. The thermal conductivity of the thermal conductivity filler (C) may be isotropic or anisotropic. For example, when it is used in a sheet form, in order to ensure excellent thermal conductivity, it is preferable that the thermal conductivity filler (C) is continuously dispersed without interruption in the direction in which heat conduction is desired. Thereby, a heat conduction path for dissipating heat from the heat source can be formed via the thermal conductivity filler (C).

[0070] Examples of boron nitride (c1) include hexagonal boron nitride (hBN) and cubic boron nitride. More preferably, it is hexagonal boron nitride. Hexagonal boron nitride has a plate-like particle shape and exhibits high thermal conductivity (usually about 400 W / (m·K) as the thermal conductivity) in the plate surface direction (within the ab plane or within the (002) plane). Therefore, from the viewpoint of efficiently enhancing the thermal conductivity, a mode in which hexagonal boron nitride is oriented and used in the direction in which the thermal conductivity is desired to be increased is preferable. Here, "oriented" includes a mode in which the orientation is such that anisotropy can be imparted to the thermal conductivity.

[0071] The content rate of the thermal conductivity filler (C) with respect to 100% by volume of the insulating composition of the present embodiment can be appropriately designed according to the application, but from the viewpoint of making the thermal conductivity and adhesiveness more excellent, it is preferably 55 to 90% by volume with respect to 100% by volume of the composition excluding voids. More preferably, it is 57 to 80% by volume, and still more preferably, it is 60 to 70% by volume.

[0072] In addition, the content rate of boron nitride (c1) with respect to 100% by volume of the thermal conductivity filler (C) contained in the insulating composition of the present embodiment can be appropriately designed according to the application, but from the viewpoint of making the thermal conductivity and adhesiveness more excellent, it is preferably 40 to 100% by volume. More preferably, it is 55 to 100% by volume, and still more preferably, it is 70 to 100% by volume.

[0073] Specific examples of the thermal conductivity filler (C) other than boron nitride (c1) include boron nitride having a tap density of less than 0.4, titanium oxide, aluminum oxide, aluminum nitride, aluminum hydroxide, silicon nitride, zinc oxide, titanium dioxide, beryllium oxide, magnesium oxide, nickel oxide, vanadium oxide, copper oxide, iron oxide, silver oxide and other metal oxides; silicon compounds such as quartz powder, silicon carbide, silicon carbide, mica and the like can be exemplified.

[0074] The average particle diameter D50 of the heat conductive filler (C) other than boron nitride (c1) is preferably 0.1 μm or more from the viewpoint of fully exerting the heat conductive effect. From the viewpoint of increasing the filling rate in combination with boron nitride (c1), particles having an average particle diameter D50 different from that of boron nitride may be used.

[0075] The heat conductive filler (C) may be subjected to a crushing / pulverizing step as necessary before being mixed with the polyimide resin (A) or the like. The surface of the heat conductive filler (C) can be surface-treated with, for example, silane-based, titanate-based, and aluminate-based coupling agents. By the surface treatment, the dispersibility of the heat conductive filler (C) with respect to the polyimide resin (A) can be enhanced. Also, the interfacial adhesion strength between the polyimide resin (A) and the heat conductive filler (C) can be enhanced. As the surface treatment agent for the silica filler, a silane coupling agent is preferable.

[0076] The silane coupling agent is a compound having a hydrolyzable group and a reactive functional group. Examples of the hydrolyzable group include alkoxy groups having 1 to 6 carbon atoms such as methoxy group and ethoxy group; acetoxy group; 2-methoxyethoxy group and the like. Among these, the methoxy group is preferable in terms of easily removing volatile components such as alcohol generated by hydrolysis. Examples of the reactive functional group include vinyl group, epoxy group, styryl group, methacryl group, acrylic group, amino group, ureido group, mercapto group, sulfide group, isocyanate group and the like, and among them, the epoxy group is preferable.

[0077] Silane coupling agents include, for example, vinyl group-containing silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane; epoxy group-containing silane coupling agents such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane; styryl group-containing silane coupling agents such as p-styryltrimethoxysilane; methacryl group-containing silane coupling agents such as 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane; acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane; amino group-containing silane coupling agents such as N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane; ureido group-containing silane coupling agents such as 3-ureidopropyltriethoxysilane; mercapto group-containing silane coupling agents such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane; sulfide group-containing silane coupling agents such as bis(triethoxysilylpropyl)tetrasulfide; and isocyanate group-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane. From the viewpoint of exhibiting excellent adhesion and heat cycle resistance of the curable composition, phenylamino silane treatment or / and vinyl silane treatment are preferred as the silane coupling agent.

[0078] Examples of titanate coupling agents include isopropyltriisostearoyl titanate, isopropyltri(N-aminoethyl-aminoethyl) titanate, tetra(2,2-diallyloxymethyl-1-butyl) bis(ditridecyl) phosphite titanate, bis(dioctyl pyrophosphate) oxyacetate titanate, bis(dioctyl pyrophosphate) ethylene titanate, diisopropyl bis(dioctyl phosphate) titanate, tetraisopropyl bis(dioctyl phosphite) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, and the like.

[0079] Examples of the method for treating a silica filler with a silane coupling agent include a wet method in which the silica filler and the silane coupling agent are mixed in a solvent, a dry method in which the silica filler and the silane coupling agent are treated in a gas phase, and the like. The treatment amount of the silane coupling agent is preferably about 0.1 to 1 part by mass with respect to 100 parts by mass of the untreated silica filler.

[0080] (Other filler (D)) The insulating composition of this embodiment may contain other filler (D) as an optional component. Filler (D) may be an inorganic filler or an organic filler. For example, silica filler, talc, carbon nanotube, graphite can be mentioned. Depending on the desired properties such as flame retardancy, mechanical strength, heat resistance, hygroscopicity, etc., it can be used alone or in combination of two or more.

[0081] (Other components) In addition, the insulating composition of the present embodiment may contain a catalyst (E) as an optional component in order to promote the crosslinking of the polyimide resin (A) and the curing agent (B). Examples of the crosslinking sites between the polyimide resin (A) and the curing agent (B) include functional groups such as acid anhydride groups at the molecular chain ends, and functional groups of side chains and / or side groups. Examples of the catalyst (E) include compounds having a tertiary amino group, phosphorus-based curing accelerators, urea compounds, dicyandiamide-based compounds, hydrazide compounds, and the like. Compounds having a tertiary amino group, urea compounds, and dicyandiamide are more preferred, and compounds having a tertiary amino group are most preferred. Compounds having a tertiary amino group include those with and without a heterocyclic ring, and those with a heterocyclic ring are more preferred. Any of these may be used alone, or two or more thereof may be used in combination.

[0082] Among these, a latent curing accelerator that is in a solid state at normal temperature and melts during heating and pressurization of the thermosetting adhesive sheet to exhibit the function of a curing accelerator is suitable, and a latent curing accelerator having a tertiary amino group is particularly suitable. Examples of the latent curing accelerator having a tertiary amino group include adduct-type latent curing accelerators in which a relatively low-molecular-weight epoxy compound is added to a relatively low-molecular-weight compound having a functional group capable of reacting with a tertiary amino group and an epoxy group. Examples of the adduct-type latent curing accelerator having a tertiary amino group include those with a heterocyclic ring such as an imidazole group and those without a heterocyclic ring.

[0083] Examples of the tertiary amine-adduct latent curing accelerator without a heterocyclic ring include Amicure MY-24, Amicure MY-25, Amicure MY-H, Amicure MY-24J, Amicure MY-HK-1 manufactured by Ajinomoto Fine-Techno Co., Ltd.; EH4380S, EH3616S, EH5001P, EH4357S, EH3615S manufactured by ADEKA Corporation, and the like.

[0084] Imidazole - adduct latent curing accelerators having a complex ring include, for example, Amicure PN - 23, Amicure PN - 23J, Amicure PN - 31, Amicure PN - 31J, Amicure PN - 40, Amicure PN - 40J, Amicure PN - 50, Amicure PN - H manufactured by Ajinomoto Fine - Techno Co., Ltd.; Adeka Hardener EH3293S, Adeka Hardener EH3366S, Adeka Hardener EH4346S manufactured by Adeka Corporation; Sunmide LH210 manufactured by Air Products Japan Co., Ltd., and the like.

[0085] Furthermore, as latent curing accelerators having a tertiary amino group other than adduct - type latent curing accelerators, dicyandiamide - modified polyamines (for example, EH3842 manufactured by Adeka Corporation, etc.), urea - bond - containing modified polyamines (for example, Fujicure FXE1000, Fujicure FXR1110, Fujicure FXR1121, Fujicure FXR1081 manufactured by T&K Toka Co., Ltd., etc.), urea - bond - containing modified aliphatic polyamines (for example, EH4353S manufactured by Adeka Corporation), urea - bond and imidazole - group - containing modified polyamines (for example, FXR1110, FXR1121 manufactured by T&K Toka Co., Ltd.), imidazole compounds (for example, Curezol 2MZ - A, Curezol 2MA - OK, Curezol 2PHZ, Curezol 2P4MHZ manufactured by Shikoku Kasei Kogyo Co., Ltd., etc.) and the like can also be mentioned.

[0086] Examples of urea compounds include aromatic dimethylureas (for example, U - CAT3512T manufactured by San - Apro Ltd., DYHARD UR200, UR300, UR500 manufactured by Evonik); aliphatic dimethylureas (for example, U - CAT3513N manufactured by San - Apro Ltd.); ureas such as 3 - (3,4 - dichlorophenyl) - 1,1 - dimethylurea (DCMU), 3 - (3 - chloro - 4 - methylphenyl) - 1,1 - dimethylurea, 2,4 - bis(3,3 - dimethylureido)toluene, and the like.

[0087] Examples of the hydrazide compound include carbohydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, iminodiacetic acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedihydrazide, hexadecanedihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, diglycolic acid dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthoic acid dihydrazide, 4,4'-bisbenzenedihydrazide, 1,4-naphthoic acid dihydrazide, naphthalene-2,6-dicarbohydrazide, 3-hydroxy-2-naphthoic acid hydrazide, citric acid trihydrazide, and the like. Examples of commercially available hydrazide compounds include Amicure VDH and Amicure UDH manufactured by Ajinomoto Fine-Techno Co., Inc.

[0088] As phosphorus-based hardening accelerators, there are organophosphine compounds such as primary, secondary, and tertiary organophosphine compounds like alkylphosphine, dialkylphosphine, trialkylphosphine, phenylphosphine, diphenylphosphine, triphenylphosphine, etc.; phosphinoalkane compounds such as (diphenylphosphino)methane, 1,2-bis(diphenylphosphino)ethane, 1,4-(diphenylphosphino)butane, etc.; diphosphine compounds such as triphenyldiphosphine; salts of triorganophosphine and triorganoborane such as triphenylphosphine-triphenylborane; tetraorganophosphonium and tetraorganoborate such as tetraphenylphosphonium·tetraphenylborate; primary to tertiary benzylphosphine, tris(p-methoxyphenyl)phosphine, tris(p-methylphenyl)phosphine, tricyclohexylphosphine, triphenyldiphosphine, tetrabutylphosphonium bromide, 40% aqueous solution of tetrabutylphosphonium hydroxide, 40% solution of tetrabutylphosphonium acetate, tetraphenylphosphonium bromide, methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, n-butyltriphenylphosphonium bromide, methoxymethyltriphenylphosphonium chloride, benzyltriphenylphosphonium chloride, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-triborate, tri-tert-butylphosphonium tetraphenylborate, triphenylphosphine triphenylborate, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(p-methoxyphenyl)phosphine, diphenylcyclohexylphosphine, tricyclohexylphosphine, tributylphosphine, tri-tert-butylphosphine, tri-n-octylphosphine, diphenylphosphinostyrene, diphenylphosphinoyl chloride, tri-n-octylphosphine oxide, triphenylphosphine oxide, diphenylphosphinyl hydroquinone, and the like.

[0089] The content ratio (mass ratio) of the curing agent (B) and the catalyst (E) is preferably (B):(E) = 50:50 to 95:5, more preferably 70:30 to 90:10. By setting the above ratio, it is possible to effectively promote curing while maintaining the pot life of the thermosetting adhesive sheet.

[0090] In addition, the insulating composition of the present embodiment can further contain other additives without departing from the gist of the present invention. For example, a polyimide resin that does not correspond to the polyimide resin (A) may be used. Also, any thermoplastic resin (elastomer) can be used. Examples thereof include dyes, pigments (e.g., carbon black), flame retardants, antioxidants, polymerization inhibitors, defoaming agents, leveling agents, ion scavengers, moisturizing agents, viscosity modifiers, preservatives, antibacterial agents, antistatic agents, antiblocking agents, ultraviolet absorbers, infrared absorbers, electromagnetic wave shielding agents, and the like.

[0091] [Method for manufacturing insulating composition] The insulating composition is obtained by blending each blending component. An imidized polyimide resin (A) rather than a polyimide precursor is used as a blending component. The polyimide resin (A) functions as a thermosetting resin in the insulating composition. A solvent can be appropriately used during blending. The solid content concentration can be, for example, 20 to 60 parts by mass. Since the polyimide resin (A) of the present embodiment has a dimer structure, it can be easily dissolved in various organic solvents.

[0092] [Method for manufacturing cured product] A cured product is obtained by subjecting the insulating composition of the present embodiment to a thermosetting treatment. Examples of the method include molding the insulating composition into a desired shape such as a sheet and then performing a thermosetting treatment. A molded article such as a sheet of the insulating composition can be easily obtained by applying and drying the insulating composition containing a solvent. Then, a cured product is formed by thermosetting the molded article. The timing of the molding and the curing may be simultaneous.

[0093] The heat curing temperature may be appropriately selected according to the type of the curing agent (B). For example, a method of heat treatment at a temperature of 150 to 230 °C for 30 to 180 minutes can be exemplified. By the heat curing treatment, a crosslinked structure such as crosslinking of the curing agent (B) itself, crosslinking of the polyimide resin (A) and the curing agent (B), or a crosslinked structure by any combination thereof is formed, and a three-dimensionally crosslinked cured product is obtained.

[0094] [[Thermosetting adhesive sheet]] The thermosetting adhesive sheet of the present embodiment is formed from the insulating composition of the present invention. The thermosetting adhesive sheet of the present embodiment can be appropriately designed according to the application, but from the viewpoint of well-balancedly having adhesiveness, heat resistance, moisture resistance, insulation properties, and thermal conductivity, the porosity is preferably 45% by volume or less. More preferably, it is 40% by volume or less, and still more preferably 35% by volume or less. The lower limit is not particularly limited, and the porosity may be 0% by volume. Here, the "void" refers to a value obtained by the method described in the examples below.

[0095] Further, the thermosetting adhesive sheet of the present embodiment preferably contains 55 to 90% by volume of the thermal conductivity filler (C) with respect to 100% by volume of the composition excluding voids. More preferably, it is 57 to 80% by volume, and still more preferably 60 to 70% by volume. By containing 55 to 90% by volume of the thermal conductivity filler (C), the thermal conductivity can be made more excellent. Here, the "volume of the thermal conductivity filler (C) with respect to 100% by volume of the composition excluding voids" refers to a value obtained by the method described in the examples below.

[0096] [[Thermally conductive adhesive layer]] The thermally conductive adhesive layer of this embodiment is the cured product of the thermosetting adhesive sheet of this embodiment. As a preferred embodiment, a sheet can be mentioned in which the porosity of the cured product of the thermosetting adhesive sheet of this embodiment is equal to or less than the porosity before curing and is 15% by volume or less. The porosity may be the same before and after curing. By setting the porosity to 15% by volume or less, the characteristics of thermal conductivity and adhesiveness can be more effectively exhibited. A more preferable range of the porosity is 10% by volume or less, and still more preferably 5% by volume or less.

[0097] The film thickness of the thermally conductive adhesive layer of this embodiment can be appropriately designed according to the application, but is preferably 50 to 250 μm. More preferably, it is 60 to 225 μm, and still more preferably 70 to 200 μm.

[0098] [[Composite member]] The composite member of this embodiment includes a heat generating member capable of generating heat, a heat dissipation base substrate for dissipating the heat of this heat generating member, and a thermally conductive adhesive layer for joining these. And this thermally conductive adhesive layer is made of the cured product of the thermosetting adhesive sheet of the present invention.

[0099] At least a part of the joint portion of the heat generating member with the heat dissipation base substrate is, for example, copper, and at least a part of the joint portion of the heat dissipation base substrate with the heat generating member is, for example, copper or aluminum. For example, the heat generating member can be exemplified by a printed wiring board for an LED, a high-frequency electronic circuit, or a printed wiring board for a power circuit. Further, the heat dissipation base can be exemplified by a housing of an electronic device or the like.

[0100] Hereinafter, an example of the use of the insulating composition of this embodiment will be described, but it goes without saying that it is not limited to the following examples. (Wiring board) The insulating composition of this embodiment can be suitably used as a thermosetting adhesive sheet for printed wiring boards or multilayer wiring boards, or as an insulating layer. An insulating thermally conductive adhesive layer that is a cured product of a thermosetting adhesive sheet formed from the insulating composition of this embodiment, or an insulating thermally conductive adhesive layer composed of a cured product of a prepreg formed using the insulating composition of this embodiment, is suitable as a bonding layer or an interlayer insulating layer. These can be suitably used, for example, as a printed wiring board having a layer made of a cured product obtained by thermosetting the insulating composition of this embodiment on a substrate.

[0101] For the thermally conductive adhesive layer that is the insulating cured product of this embodiment formed on one or both sides of the wiring board, openings can be provided by drilling or laser processing, etc., and a via can be formed by filling a conductive agent. Also, a circuit layer can be formed on the interlayer insulating layer (thermally conductive adhesive layer) of this embodiment. Since the thermally conductive adhesive layer of the cured product formed from the insulating composition of this embodiment is excellent in adhesiveness and long-term heat resistance, it is suitable for applications of multilayer circuit boards having a plurality of insulating layer / circuit layer configurations.

[0102] (Metal-clad laminate) The insulating composition of this embodiment can be used as a member of a metal-clad laminate. The metal-clad laminate can be a laminate of an insulating layer made of a cured product of the insulating composition and a metal layer. This insulating layer may be an insulating sheet formed only from the insulating composition, or may be a sheet made of the prepreg described above. For example, after laminating a metal layer and a thermosetting adhesive sheet made of the insulating composition of this embodiment, the thermosetting adhesive sheet is cured by thermocompression bonding to obtain an insulating layer (thermally conductive adhesive layer) and a metal-clad laminate can be obtained. Known methods can be used for the thermocompression bonding method. For example, it is carried out by thermopressing at a temperature of 120 to 200°C and a pressure of 0.5 to 15 MPa for 0.5 to 5 hours.

[0103] Examples of the laminated structure of the metal-clad laminate include a two-layer laminate of a metal layer / insulating layer, a laminate composed of multiple layers of a metal layer / insulating layer / metal layer, or a multi-layer structure in which a metal layer / insulating layer / metal layer / insulating layer / metal layer, etc. are alternately laminated. In addition, an insulating layer other than the insulating layer formed from the insulating composition of the present embodiment may be included in the laminate. Further, multiple prepregs can be stacked and cured to adjust the thickness of the insulating layer. Also, a conductive layer other than the metal layer may be laminated.

[0104] For example, a metal-clad laminate having a layer structure of a metal layer / insulating layer / metal layer can obtain a circuit board having a circuit pattern layer by forming a circuit pattern by etching or the like on the metal layers formed on both main surfaces of the insulating layer. Through holes and vias may be formed in the insulating layer by a laser or the like. The core substrate may be multi-layered by forming insulating layers and vias by a build-up process. The circuit board can be obtained, for example, by a method of forming a desired circuit pattern on the metal layer of the metal-clad laminate by a subtractive method or by forming a desired circuit pattern on one or both surfaces of the insulating layer by an additive method.

[0105] The formation of through holes in the insulating layer can be achieved, for example, by laser processing. Specifically, UV-YAG lasers, CO2 lasers, and excimer lasers can be exemplified.

[0106] (Prepreg) The insulating composition according to the present embodiment can be used as a prepreg by impregnating a fiber substrate. The prepreg can be manufactured, for example, by impregnating a fiber substrate with the insulating composition of the present embodiment and then heating and drying the insulating composition to semi-cure (B-stage).

[0107] The solid content adhesion amount of the insulating composition to the fiber base material is preferably 20 to 90% by mass in the content of the insulating composition after drying for the prepreg. More preferably, it is 30 to 80% by mass, and even more preferably, it is 40 to 70% by mass. For example, the insulating composition of this embodiment is impregnated or coated on the fiber base material so that the solid content adhesion amount of the insulating composition in the prepreg is 20 to 90% by mass, and then heated and dried at a temperature of, for example, 40 to 200°C for 1 to 30 minutes and semi-cured (B-staged) to produce it.

[0108] As the fiber base material, known materials can be used without limitation, and organic fibers, inorganic fibers, and glass fibers can be exemplified. Examples of organic fibers include polyimide, polyester, tetrafluoroethylene, and wholly aromatic polyamide. Examples of inorganic fibers include carbon fibers. Examples of glass fibers include E-glass cloth, D-glass cloth, S-glass cloth, Q-glass cloth, NE-glass cloth, L-glass cloth, T-glass cloth, spherical glass cloth, and low-dielectric glass cloth. Among these, from the viewpoint of low coefficient of thermal expansion, E-glass cloth, T-glass cloth, S-glass cloth, Q-glass cloth, and organic fibers are suitable. The fiber base material may be used alone or in combination of two or more.

[0109] The shape of the fiber base material can be appropriately selected according to the intended use and performance. Specific examples include woven fabric, non-woven fabric, roving, chopped strand mat, and surfacing mat. Examples of the weaving method of the woven fabric include plain weave, nanako weave, and twill weave. It can be arbitrarily selected and designed according to the desired characteristics. The thickness of the fiber base material can be, for example, in the range of about 0.01 to 1.0 mm. From the viewpoint of thinning the film, 500 μm or less is preferable, and 300 μm or less is more preferable.

[0110] The fiber substrate can be surface-treated with a silane coupling agent or the like or mechanically fibrillated to bring out desired properties as needed. In addition, corona treatment or plasma treatment may be performed. The surface treatment with a silane coupling agent includes aminosilane coupling treatment, vinylsilane coupling treatment, cationic silane coupling treatment, epoxy silane coupling treatment, etc.

[0111] The method of impregnating the fiber substrate with the insulating composition is not particularly limited. For example, a varnish of the insulating composition is prepared using an organic solvent such as alcohols, ethers, acetals, ketones, esters, alcohol esters, ketone alcohols, ether alcohols, ketone ethers, ketone esters, or ester ethers, and the fiber substrate is immersed in the varnish; the varnish is applied or sprayed onto the fiber substrate; or the two sides of the fiber substrate are laminated with a film made of the insulating composition.

Example

[0112] The present invention will be described more specifically, but the following examples do not limit the scope of the rights of the present invention in any way. In the examples, "parts" and "%" represent "parts by mass" and "mass%", respectively, and Mw means weight average molecular weight. The compounding amounts in the table are in parts by mass.

[0113] <Synthesis Example of Polyimide Resin> [Synthesis Example 1: Polyimide Resin (A)-1] Into a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, an inlet tube, and a thermometer, 378.7 g of a C36 diamine (Priamine 1075) as a polyamine compound, 380.0 g of bisphenol A type acid dianhydride (4,4'-[propane-2,2-diylbis(1,4-phenyleneoxy)]diphthalic dianhydride) (BISDA-1000) as a tetracarboxylic dianhydride, and 1100 g of cyclohexanone as a solvent were charged and stirred until homogeneous. After becoming homogeneous, the temperature was raised to 110 °C, and after 30 minutes, the temperature was raised to 140 °C. Then, the reaction was continued at 140 °C for 10 hours. After continuing the dehydration reaction, an antioxidant was added to obtain a solution of polyimide resin (A)-1 having an acid anhydride group terminal, containing 50.3% by mass of a C20-C60 hydrocarbon group derived from the diamine, with Mw 54,000, acid value 6.4 mg KOH / g, amine value 0.3 mg KOH / g, and a non-volatile content of about 54%. Note that Mw (weight average molecular weight), acid value, and amine value were determined by the methods described below.

[0114] [Synthesis Example 2: Polyimide Resin (A)-2] Into a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, an inlet tube, and a thermometer, 371.6 g of Priamine 1075 as a polyamine compound, 226.5 g of 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride (OPDA) as a tetracarboxylic dianhydride, and 860 g of xylene as a solvent were charged and stirred until homogeneous. After becoming homogeneous, the temperature was raised to 110 °C, and after 30 minutes, the temperature was raised to 140 °C. Then, the reaction was continued at 140 °C for 10 hours. After continuing the dehydration reaction, an antioxidant was added to obtain a solution of polyimide resin (A)-2 having an acid anhydride group terminal, containing 63.7% by mass of a C20-C60 hydrocarbon group derived from the diamine, with Mw 30,000, acid value 8.1 mg KOH / g, amine value 0.4 mg KOH / g, and a non-volatile content of about 54%.

[0115] [Synthesis Example 3: Polyimide Resin (A)-3] Into a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, an inlet tube, and a thermometer, 358.0 g of priamine 1075 as a polyamine compound, 214.8 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) as a tetracarboxylic dianhydride, and 823 g of xylene as a solvent were charged and stirred until homogeneous. After becoming homogeneous, the temperature was raised to 110 °C, and after 30 minutes, the temperature was raised to 140 °C. Then, the reaction was continued at 140 °C for 10 hours. After continuing the dehydration reaction, an antioxidant was added to obtain a solution of polyimide resin (A)-3 having an acid anhydride group terminal, containing 64.2% by mass of a hydrocarbon group having 20 to 60 carbon atoms derived from dimeric diamine, with Mw of 16,000, an acid value of 12.3 mgKOH / g, an amine value of 0.2 mgKOH / g, and a non-volatile content of about 54%.

[0116] [Synthesis Example 4: Polyimide Resin (A)-4] Into a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, an inlet tube, and a thermometer, 213.6 g of priamine 1075 as a polyamine compound, 54.0 g of 4,4'-diaminodiphenyl ether, 214.8 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) as a tetracarboxylic dianhydride, and 823 g of xylene as a solvent were charged and stirred until homogeneous. After becoming homogeneous, the temperature was raised to 110 °C, and after 30 minutes, the temperature was raised to 140 °C. Then, the reaction was continued at a temperature of 140 °C for 10 hours. After continuing the dehydration reaction, an antioxidant was added to obtain a solution of polyimide resin (A)-4 having an acid anhydride group terminal, containing 52.8% by mass of a hydrocarbon group having 20 to 60 carbon atoms derived from dimeric diamine, with Mw of 21,000, an acid value of 10.1 mgKOH / g, an amine value of 0.1 mgKOH / g, and a non-volatile content of about 53%.

[0117] [Synthesis Example 5: Polyimide Resin (A)-5] Into a four-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, an inlet tube, and a thermometer, 302.0 g of priamine 1075 as a polyamine compound, 177.2 g of 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride, and 823 g of xylene as a solvent were charged and stirred until homogeneous. Once homogeneous, the temperature was raised to 110 °C, and after 30 minutes, the temperature was raised to 140 °C. Then, the reaction was continued at 140 °C for 10 hours. After continuing the dehydration reaction, an antioxidant was added to obtain a solution (nonvolatile content of about 49%) of polyimide resin (A)-5 having an acid anhydride group terminal and containing 64.7% by mass of a hydrocarbon group having 20 to 60 carbon atoms derived from dimer diamine, with Mw of 22,000, an acid value of 10.0 mgKOH / g, and an amine value of 0.1 mgKOH / g.

[0118] [Comparative Synthesis Example 1: Polyimide Resin P1] According to Example 1 disclosed in the above Patent Document 3, ODPA and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane were reacted to obtain a solution (nonvolatile content of about 30%) of polyimide resin P1 having Mw of 26,000, an acid value of 0.2 mgKOH / g, an amine value of 7.2 mgKOH / g, and not containing a hydrocarbon group having 20 to 60 carbon atoms derived from dimer diamine.

[0119] [Comparative Synthesis Example 2: Imide-Modified Elastomer Resin P2] According to the synthesis example of Patent Document 4 above, a solution of an imide-modified elastomer resin P2 having a polyurethaneimide structure (non-volatile content: about 19%) was obtained. Specifically, a urethane prepolymer having isocyanato groups at both molecular ends was obtained using 4,4'-diphenylmethane diisocyanate and polyoxytetramethylene glycol, and further reacted with 4,4'-diaminodiphenylmethane (MDA) to obtain a solution of a polyurethane-urea compound. Then, pyromellitic dianhydride (PMDA) was added to the solution of the obtained polyurethane-urea compound (l) to obtain a solution of an imide-modified elastomer resin P2 having a polyurethaneimide structure without a dimer skeleton (non-volatile content: about 19%). The obtained resin P2 had an Mw of 23,000, an acid value of 4.5 mg KOH / g, and an amine value of 5.0 mg KOH / g.

[0120] [Comparative Synthesis Example 3: Dimer Acid Polyamideimide Resin P3] According to the synthesis example PAI-1 disclosed in the example of Patent Document 2 above, a solution of a dimer acid polyamideimide resin P3 was obtained. Specifically, by reacting dimer acid (manufactured by Harima Chemicals, Inc., Haridimer 250 (molecular weight 580, carbon number 36, dimer acid content 80% by weight)), 1,3-bis(3-aminopropyl)tetramethyldisiloxane, 4,9-dioxadodecane-1,12-diamine, and 4,4'-oxydiphthalic dianhydride, a solution of a dimer acid polyamideimide resin P3 having an Mw of 23,800, an acid value of 9.5 mg KOH / g, an amine value of 1.6 mg KOH / g, and containing 47.8% by mass of a hydrocarbon group having 20 to 60 carbon atoms derived from dimer diamine (non-volatile content: about 50%) was obtained.

[0121] <Measurement of Weight-Average Molecular Weight (Mw)> The measurement of Mw was carried out using GPC (Gel Permeation Chromatography) "HPC-8020" manufactured by Tosoh Corporation. GPC is a liquid chromatography that separates and quantifies substances dissolved in a solvent (THF: Tetrahydrofuran) based on the difference in their molecular sizes. In the measurement of the present invention, two "LF-604" (manufactured by Showa Denko KK: GPC column for rapid analysis: size 6 mm ID × 150 mm) were connected in series to the column and used, and the measurement was carried out under the conditions of a flow rate of 0.6 mL / min and a column temperature of 40°C. The determination of the weight average molecular weight (Mw) was carried out in terms of polystyrene conversion.

[0122] <Measurement of acid value> Precisely weigh about 1 g of the sample into a conical flask with a stopper, add 100 mL of cyclohexanone solvent, and dissolve it. To this, add phenolphthalein test solution as an indicator and hold for 30 seconds. Then, titrate with 0.1 N alcoholic potassium hydroxide solution until the solution shows a light pink color. The acid value was determined by the following formula (unit: mgKOH / g). Acid value (mgKOH / g) = (5.611 × a × F) / S However, S: Sampling amount of the sample (g) a: Consumption amount of 0.1 N alcoholic potassium hydroxide solution (mL) F: Normality of 0.1 N alcoholic potassium hydroxide solution

[0123] <Measurement of amine value> Precisely weigh about 1 g of the sample into a conical flask with a stopper, add 100 mL of cyclohexanone solvent, and dissolve it. To this, add 2 or 3 drops of an indicator prepared by mixing a solution of 0.20 g of Methyl Orange dissolved in 50 mL of distilled water and a solution of 0.28 g of Xylene Cyanol FF dissolved in 50 mL of methanol, and hold for 30 seconds. Then, titrate with 0.1 N alcoholic hydrochloric acid solution until the solution shows a bluish-gray color. The amine value was determined by the following formula (unit: mgKOH / g). Amine value (mgKOH / g) = (5.611 × a × F) / S However, S: Sampling amount of the sample (g) a: Consumption amount of 0.1 N alcoholic hydrochloric acid solution (mL) Titer of 0.1 N alcoholic hydrochloric acid solution

[0124] <Content ratio of hydrocarbon group having 20 to 60 carbon atoms derived from dimer diamine> The content ratio of the hydrocarbon group having 20 to 60 carbon atoms derived from dimer diamine contained in the polyimide resin (A) was calculated as follows from the monomers used as raw materials. The value obtained by multiplying the blending amount (mass) of the dimer diamine used as a raw material by the content ratio of the so-called diamine residue excluding the amino group with respect to the molecular weight of the dimer diamine is the content of the hydrocarbon group having 20 to 60 carbon atoms derived from the dimer diamine in the polyimide resin (A). Primene 1075 is an aggregate of various compounds because it uses unsaturated fatty acids derived from natural products as starting materials. The molecular weight of such compounds shall be determined as follows. That is, multiply the weight average molecular weight by the average valence number of the amine value, divide this by the amine value, and multiply by the valence number. In the case of Primene 1075, the molecular weight = weight average molecular weight × average valence number / amine value (mgKOH) = 56,110 × 2 / 210 = 534, and it is the following compound represented by the following formula.

[0125]

Chemical formula

[0126] Therefore, since the content ratio of the hydrocarbon group having 20 to 60 carbon atoms derived from the dimer diamine in Primene 1075 is the content ratio of the portion excluding the amino group, ((534 - 32) / 534)) × 100 = 94.0%, The hydrocarbon group having 20 to 60 carbon atoms derived from the dimer diamine contained in 378.7 g of Primene 1075 is 378.7 × 0.94 = 356.0 (g). Pryamine 1075 is bifunctional. During imidization, theoretically two waters are generated and eliminated for each amino group. Therefore, when reacting 378.7 g of Pryamine 1075 with 380.0 g of BISDA-1000, 51.1 g of water will be eliminated, calculated as (378.7 / 534)×18×2×2 = 51.1 g. Thus, the content ratio of hydrocarbon groups with 20 to 60 carbon atoms derived from the dimer diamine contained in (A)-1 generated by the reaction of 378.7 g of Pryamine 1075 and 380.0 g of BISDA-1000 is derived as 356.0 / (378.7 + 380.0 - 51.1)×100 = 50.3%.

[0127] [Example 1] Preparation of Insulating Composition and Thermosetting Adhesive Sheet A solution containing 14 parts of the polyimide resin (A)-1 obtained in Synthesis Example 1 and a solution containing 1.5 parts of the epoxy resin "jER828" manufactured by Mitsubishi Chemical Corporation as the curing agent (B) were mixed. Next, 84.5 parts of boron nitride (c1) HP40MF100 (boron nitride particles, tap density 0.85 g / cm 3 , average particle diameter D50: 35 μm, manufactured by Mizushima Alloy Iron Co., Ltd.) was added and stirred with a disper to obtain an insulating composition with a non-volatile content adjusted to 50 mass% with toluene. Note that the above blending amounts refer to the blending amounts of the solid components.

[0128] The obtained insulating composition was coated on a release sheet and dried to produce two sheets 1 with one side of a thermosetting adhesive sheet with a thickness of 100 μm covered by the release sheet. Then, these two sheets 1 were overlapped so that the thermosetting adhesive sheets were joined together, and joined under the conditions of 100 °C, 0.3 MPa, and 1 m / min to form sheet 2. Sheet 2 is a laminate in which the thermosetting adhesive sheet is sandwiched by two release sheets. The thickness of this thermosetting adhesive sheet was 190 μm by the above treatment. Also, the thermosetting adhesive sheet of sheet 2 theoretically contained 70 volume% of boron nitride (c1) and had a porosity of 36%. Note that the porosity, heat dissipation property, adhesive strength, insulation property, and solder reflow resistance of the cured product of the thermosetting adhesive sheet were evaluated according to the methods described later.

[0129] <Calculation Method for Theoretical Volume Fraction of the Heat Conductive Filler (C)> The true density of HP40-MF100, which is boron nitride (c1) used as the heat conductive filler (C) in Example 1, is 2.3 g / cm 3 Therefore, the volume occupied by the 84.5 g of the heat conductive filler (C) contained in 100 g of the thermosetting adhesive sheet is approximately 36.7 cm 3 Similarly, the true density of the polyimide resin (A)-1: 1 g / cm 3 , the true density of jER828: 1.16 g / cm 3 Therefore, the volumes occupied by the 14 g of the polyimide resin (A)-1 and 1.5 g of jER828 contained in 100 g of the thermosetting adhesive sheet are approximately 14 cm 3 , approximately 1.3 cm 3 respectively. From these, the theoretical volume fraction occupied by the heat conductive filler (C) contained in the thermosetting adhesive sheet can be obtained as approximately 70%. The true densities of the polyimide resins (A)-2 to (A)-5 and P1 to P4 were set to 1 g / cm 3 . The true densities of other compounds will be described later.

[0130] [Examples 2 to 18], [Comparative Examples 1 to 3] According to the formulations shown in Table 1 and Table 2, in the same manner as in Example 1, an insulating composition and a thermosetting adhesive sheet with a release sheet were obtained and evaluated in the same manner.

[0131] In addition, each component in Table 1 and Table 2 is as follows. (Hardener (B)) jER828 (product name): epoxy compound (b), manufactured by Mitsubishi Chemical Corporation, true density is 1.16 g / cm 3 . jER630 (product name): epoxy compound (b), manufactured by Mitsubishi Chemical Corporation, true density is 1.22 g / cm 3 . (Curing Accelerator) PN-40 (product name): manufactured by Ajinomoto Fine-Techno Co., Ltd. (Heat Conductive Filler (C)) HP40-MF100 (Product Name): Boron nitride (c1), manufactured by Mizushima Alloy Iron Co., Ltd., tap density 0.85 g / cm 3 , average particle size D50 is 35 μm, true density is 2.3 g / cm 3 . SGPS (Product Name): Boron nitride (c1), manufactured by Denka Co., Ltd., tap density 0.50 g / cm 3 , average particle size D50 is 12 μm, true density is 2.3 g / cm 3 . HP-P1 (Product Name): Boron nitride other than c1, manufactured by Mizushima Alloy Iron Co., Ltd., tap density 0.38 g / cm 3 , average particle size D50 is 3 μm, true density is 2.3 g / cm 3 . AO-502 (Product Name): Alumina, manufactured by Admatechs Co., Ltd., average particle size D50 is 0.2 μm, true density is 3.9 g / cm 3 . JR301 (Product Name): Titanium oxide, manufactured by Teika Co., Ltd., average particle size D50 is 0.3 μm, true density is 4.2 g / cm 3 .

[0132] [Example 19] According to the formulation shown in Table 2, the same insulating composition as in Example 9 was coated on a release sheet and dried to obtain a sheet in which one side of a thermosetting adhesive sheet with a thickness of 200 μm was covered with a release sheet. Then, under the conditions of 100 °C, 0.3 MPa, and 1 m / min, a release sheet was laminated on the surface (coated surface) of the thermosetting adhesive sheet to obtain a laminate in which the thermosetting adhesive sheet was sandwiched between two release sheets, and evaluation was carried out in the same manner as in Example 1.

[0133]

Table 1

[0134]

Table 2

[0135] Table 3 shows the porosity of the thermosetting adhesive sheets and the porosity of the cured products in each example and comparative example. Table 3 also shows the evaluation results of the heat dissipation property, the adhesive strength before the PCT test, the adhesive strength after the PCT test, the insulation property, and the heat resistance (solder reflow resistance) of each example and comparative example. The respective measurement methods and evaluation criteria are as follows.

[0136] <Porosity of thermosetting adhesive sheet> The porosity of the thermosetting adhesive sheet is determined from the theoretical density and the measured density. The theoretical density is determined as follows. Theoretical density = mass of thermosetting adhesive sheet (g) / volume of thermosetting adhesive sheet (cm 3 ) =(84.5 + 14 + 1.5) / {(84.5 / 2.3) + (14 / 1) + (1.5 / 1.16)} = 1.92.

[0137] Also, the measured density is determined as follows. That is, Sheet 2 is cut out to a size of 10 cm × 10 cm, and after peeling off the release sheets on both sides, the mass of the thermosetting adhesive sheet is determined. In the case of Example 1, it was 2.346 g. Measured density = mass of thermosetting adhesive sheet (g) / volume of thermosetting adhesive sheet (cm 3 = 2.346 / (10 × 10 × 0.019) = 1.235.

[0138] Since the porosity of the thermosetting adhesive sheet is determined by the formula porosity = (1 - (measured density / theoretical density)) × 100, in the case of Example 1, the porosity is (1 - (measured density / theoretical density)) × 100 =(1 - (1.235 / 1.92)) = 36%.

[0139] <Porosity of cured product> For each example and each comparative example, the sheet 2 (10 cm × 10 cm in size) obtained is pressed under the conditions of 180 °C and 3.0 MPa for 60 minutes, and the size in plan view after pressing is confirmed. Next, the release sheets on both sides are peeled off, and for the cured product (hereinafter also referred to as the measurement sample), the porosity of the cured product is determined in the same manner as in the case of the thermosetting adhesive sheet. For example, in the case of Example 1, during pressing, the cured product did not protrude from the release sheet, the size in plan view was the same as before pressing, 10 cm × 10 cm, and a cured product with a thickness of 130 μm was obtained. Since the mass of the sheet after curing was 2.346 g, the actually measured density of the cured product was = 2.346 / (10 × 10 × 0.013) = 1.804. Therefore, the porosity of the cured product is (1 - (actually measured density / theoretical density)) × 100 = (1 - (1.804 / 1.92)) × 100 = 6%. In addition, when the cured product protrudes from the release sheet during pressing, the protruding part is removed, and the mass of the cured product with a size of 10 cm × 10 cm is measured and calculated.

[0140] <Heat dissipation (thermal conductivity)> The thermal conductivity is obtained according to the following formula from the thermal diffusivity, specific heat, and density. Thermal conductivity (W / (m·K)) = density (g / cm 3 ) × specific heat (J / kg·K) × thermal diffusivity (mm 2 / s) The thermal diffusivity is obtained as follows. That is, the measurement sample is cut out into a 20 mm square, the surface of the measurement sample is vapor-deposited with gold, and then carbon-coated with a carbon spray. Next, the thermal diffusivity is measured using a xenon flash analyzer LFA447 Nano Flash (manufactured by NETZSCH). The measurement environment is 25 ± 1 °C, the measurement voltage is 202 kV, Amplitude is 2520, and the pulse width is 14 ms. In addition, the specific heat was measured using a high-sensitivity differential scanning calorimeter DSC220C manufactured by SII NanoTechnology Inc. The temperature increase rate was 5°C / min in the range from -50°C to 200°C, and the specific heat at 25°C was read. Furthermore, the density was calculated using the water displacement method. The obtained thermal conductivity was judged according to the following criteria. +++··· The thermal conductivity is 8 W / (m·K) or more. ++··· The thermal conductivity is 5 W / (m·K) or more and less than 8 W / (m·K). +··· The thermal conductivity is 2 W / (m·K) or more and less than 5 W / (m·K). NG··· The thermal conductivity is less than 2 W / (m·K). It is not suitable for practical use.

[0141] <90-degree peel adhesion strength> Sheet 2 was cut into a size of 65 mm × 65 mm. Also, two copper foils with a thickness of 35 μm of the same size [rolled copper foil RCF-T5B manufactured by Fukuda Metal Co., Ltd.] were prepared. Then, the release sheets of Sheet 2 were removed one by one, and the copper foils were temporarily pasted onto the thermosetting adhesive sheet in sequence under the conditions of 100°C, 0.3 MPa, and 1 m / min, and then cured at 180°C and 3.0 MPa for 60 minutes. A test piece with a width of 10 mm and a length of 65 mm was cut out from the obtained cured sample, and a peel test was carried out at 25°C and 50% RH environment with a pulling speed of 500 mm / min to measure the adhesion strength (N / cm). This test evaluates the adhesion strength of the cured product of the thermosetting adhesive sheet during normal temperature use. It was evaluated according to the following criteria. +++··· The 90-degree peel adhesion force is 5 N / cm or more. ++··· The 90-degree peel adhesion force is 3.5 N / cm or more and less than 5 N / cm. +··· The 90-degree peel adhesion force is 1 N / cm or more and less than 3.5 N / cm. NG··· The 90-degree peel adhesion force is less than 1 N / cm. It is not suitable for practical use.

[0142] <90-degree peel adhesion strength before and after PCT test> A sheet 2 cut to a size of 65 mm × 65 mm and a copper foil with a thickness of 35 μm cut to the same size [two sheets of "rolled copper foil RCF-T5B" manufactured by Fukuda Metal Co., Ltd. were prepared, the release sheets on both sides of the sheet 2 were removed one by one, and the copper foil was temporarily pasted onto the thermosetting adhesive sheet in sequence under the conditions of 100 °C, 0.3 MPa, and 1 m / min, and then a curing treatment was carried out at 180 °C and 3.0 MPa for 60 minutes. Test pieces with a width of 10 mm and a length of 65 mm were cut out from the cured samples, and a pressure cooker test (PCT test) was carried out in an environment of 120 °C and 100% RH for 48 hours. Using the test pieces before and after the PCT test, a peel test was carried out at 25 °C and 50% RH with a pulling speed of 500 mm / min, and the adhesive strength (N / cm) was measured. This test is to evaluate the adhesive strength of the cured product of the thermosetting adhesive sheet during normal temperature use, and the results were judged according to the following criteria. +++ ··· The 90-degree peel adhesive strength is 5 N / cm or more. ++ ··· The 90-degree peel adhesive strength is 3.5 N / cm or more and less than 5 N / cm. + ··· The 90-degree peel adhesive strength is 1 N / cm or more and less than 3.5 N / cm. NG ··· The 90-degree peel adhesive strength is less than 1 N / cm. It is not suitable for practical use.

[0143] <Insulation> A copper block (C1020P(1 / 2H)) with a size of 40 mm × 40 mm and a thickness of 2 mm, a polyimide film with a size of 50 mm × 50 mm and a thickness of 25 μm with a 25 mmφ hole punched in the central part, a thermosetting adhesive sheet (40 mm × 40 mm) with the release sheets on both sides peeled off from the sheet 2, and an aluminum block (A3003P(H24)) with a size of 40 mm × 40 mm and a thickness of 2 mm were prepared, and they were laminated to form a structure of copper block / polyimide film / thermosetting adhesive sheet / aluminum block, and a hot press was carried out at 180 °C and 3.0 MPa for 60 minutes.

[0144] The sample obtained above was allowed to stand overnight at 25°C and 50% RH. Then, using the "TM650, withstand voltage tester" manufactured by Tsuruoka Electric Co., Ltd., the aluminum block was grounded, and in an environment of 25°C and 50% RH, with the sample immersed in a fluorine-based inert liquid (manufactured by 3M Japan, Fluorinert FC-3283), the voltage was increased from 0 kV to 10 kV at a rate of 1000 V / second, with a threshold current of 2 mA, and the voltage at the time of dielectric breakdown was read as the dielectric breakdown voltage. ++ ··· The dielectric breakdown voltage is 4 kV or more. + ··· The dielectric breakdown voltage is 1 kV or more and less than 4 kV. NG ··· The dielectric breakdown voltage is less than 1 kV. It is not suitable for practical use.

[0145] <Heat resistance (solder reflow resistance)> Copper blocks, aluminum blocks, and thermosetting adhesive sheets similar to those in the insulation test were prepared, stacked so as to form a structure of copper block / thermosetting adhesive sheet / aluminum block, and hot pressed at 180°C and 3.0 MPa for 60 minutes to obtain test pieces. Using a solder reflow furnace, the temperature program was set so that the peak temperature of the test piece could be maintained at 300°C for 5 minutes. The test piece was conveyed into the furnace, and the test piece taken out of the furnace was observed. The evaluation criteria were as follows. ++ ··· Among 20 test pieces, the occurrence of peeling is 2 or less. + ··· Among 20 test pieces, the occurrence of peeling is more than 2 and 5 or less. NG ··· Among 20 test pieces, the occurrence of peeling is more than 5. It is not suitable for practical use.

[0146] The evaluation results of each example and each comparative example are shown in Table 3.

Table 3

[0147] As shown in Table 3, in Comparative Example 1 using a polyimide resin having no dimer structure, the moisture resistance and heat resistance after the PCT test were not sufficient. Also, in Comparative Example 2 using boron nitride with a tap density of less than 0.4 g / cm 3 ³, the heat dissipation was not sufficient. Further, in Comparative Example 4 using a polyamideimide resin having a dimer skeleton, the adhesive strength after the PCT test was not sufficient. On the other hand, according to the insulating composition of the present example, it was confirmed that it has excellent heat dissipation, excellent adhesive strength regardless of before and after the PCT test, and further excellent insulation and heat resistance (solder reflow resistance).

Industrial Applicability

[0148] Since the insulating composition of the present embodiment exhibits excellent adhesiveness after curing, it can be used as an adhesive material. Also, because of its excellent electrical insulation, it is suitably used as an insulating layer forming material on the circuit board itself or on the circuit board (including coverlay layers of printed wiring boards, interlayer insulating layers of build-up boards, etc., substrate forming materials, bonding sheets, etc.), a resin casting material such as an underfill material, a sealing material for semiconductor chips, a material for forming an insulating layer of a semiconductor chip package, etc. It is also suitable as a bonding material between components such as an electronic circuit board and electronic components. Furthermore, since it has excellent thermal conductivity, it can be applied to all applications that require heat dissipation. For example, by utilizing the moldability of the insulating composition, it can be suitably used as a heat dissipation component having a desired shape. In particular, it is useful as a heat dissipation member for electronic devices (such as smartphones and dual-screen terminals) and battery exterior materials that cannot be provided with a fan or heat sink due to their thin, light, short, and small size. Also, the cured product of the insulating composition of the present embodiment is suitable as an adhesive layer between a heating element and a heat sink or as a heat spreader. It can also be applied as a heat dissipation layer covering one or more electronic components mounted on a substrate. It can also be suitably used as an insulating heat dissipation sheet / molded product that dissipates heat generated from heat generating members such as liquid crystal display devices, plasma display panels, and LEDs to the outside. The insulating composition of the present invention is excellent in heat dissipation, has excellent adhesive strength regardless of before and after the PCT test, and is further excellent in insulation and heat resistance (solder reflow resistance). Therefore, in addition to electronic devices such as home appliances, industrial robots, and transportation equipment, and power semiconductor modules that require these characteristics, it can be widely used in building materials, vehicles, aircraft, and ships.

Claims

1. A thermosetting insulating composition containing a polyimide resin (A) which is a reaction product of a tetracarboxylic dianhydride and a polyamine compound containing a dimer diamine, a curing agent (B), and a thermally conductive filler (C) (provided that it does not contain a modified elastomer having an acid anhydride group). As the heat conductive filler (C), boron nitride (c1) having a tap density of 0.4 g / cm ３ or more is included A thermosetting insulating composition.

2. The insulating composition according to claim 1, wherein the tetracarboxylic dianhydride contains a compound represented by the general formula (1): 【Chemical Formula 1】 (X １ is a tetravalent tetracarboxylic dianhydride residue and has at least one substituted or unsubstituted aromatic ring.)

3. The insulating composition according to claim 1 or 2, wherein the content of the dimer diamine contained in 100% by mass of the polyamine compound is 50 to 100% by mass.

4. The insulating composition according to any one of claims 1 to 3, wherein the content of the hydrocarbon group having 20 to 60 carbon atoms derived from the dimer diamine contained in the polyimide resin (A) is 30 to 90% by mass.

5. The insulating composition according to any one of claims 1 to 4, wherein the weight average molecular weight of the polyimide resin (A) is 5,000 to 150,000.

6. The insulating composition according to any one of claims 1 to 5, wherein the curing agent (B) contains an epoxy compound (b1).

7. The insulating composition according to claim 6, wherein the epoxy compound (b1) is a compound having any one of a hydroxyl group, a secondary amino group, and a tertiary amino group and having two or more epoxy groups.

8. The insulating composition according to any one of claims 1 to 7, wherein the average particle diameter D50 of boron nitride (c1) is 10 to 100 μm.

9. The insulating composition according to any one of claims 1 to 8, wherein the content of boron nitride (c1) contained in 100% by volume of the thermally conductive filler (C) is 40 to 100% by volume.

10. A thermosetting adhesive sheet formed from the insulating composition according to any one of claims 1 to 9.

11. The thermosetting adhesive sheet according to claim 10, which may have voids, wherein when having voids, the porosity is 45% by volume or less, and the thermally conductive filler (C) is contained in an amount of 55 to 90% by volume based on 100% by volume of the composition excluding the voids.

12. A thermally conductive adhesive layer which is a cured product of the thermosetting adhesive sheet according to claim 11, wherein the porosity of the cured product is equal to or less than the porosity before curing and is 15% by volume or less.

13. The thermally conductive adhesive layer according to claim 12, having a thickness of 50 to 250 μm.

14. A heat generating member capable of generating heat, A heat dissipation base substrate for dissipating the heat of the heat generating member, ​ It has a thermally conductive adhesive layer that joins the heat generating member and the heat dissipation base material, The composite member in which the thermally conductive adhesive layer is a cured product of the thermosetting adhesive sheet according to claim 10 or 11.

15. The composite member according to claim 14, wherein at least a part of the joint portion between the heat generating member and the heat dissipation base material is copper, and at least a part of the joint portion between the heat dissipation base material and the heat generating member is copper or aluminum.

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