Manufacturing method of resin composition layer, resin composition layer obtained by the manufacturing method, and composite molding containing resin composition layer

Abstract

To provide a manufacturing method of a resin composition layer made of a resin composition containing an aggregated inorganic filler and a thermosetting resin.SOLUTION: A method of manufacturing a resin composition layer has the steps of: (a) press processing a carrier film and a sheet formed using the resin composition on the carrier film under the conditions of press temperature of 0°C or higher and 110°C or lower, and press pressure of 40 MPa or more and 1000 MPa or less; and (b) press processing the sheet subjected to the step (a), under the conditions of press temperature of 70°C or higher and 250°C or lower, and press pressure of 3 MPa or more and 100 MPa or less, to obtain the resin composition layer.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing a resin composition layer, a resin composition layer obtained by the production method, and a composite molded body including the resin composition layer. The resin composition layer and the composite molded body obtained by the method for producing a resin composition layer of the present invention can be suitably used, for example, as a heat dissipation material for a power semiconductor device.

Background Art

[0002] Regarding heat dissipation sheets having good thermal conductivity and excellent insulation properties, many studies have been conducted. In particular, attempts have been continuously made to mix fillers into resins to obtain heat dissipation resin sheets that satisfy high levels of thermal conductivity and insulation properties. As fillers contained in the heat dissipation resin sheets, various oxides and nitrides are used, and many studies have also been conducted on their particle sizes, particle size distributions, and the like.

[0003] Conventionally, the use of hexagonal boron nitride as a filler contained in a heat dissipation sheet has been studied. Hexagonal boron nitride is generally a thin plate-like crystal, and its thermal conductivity in the plane direction of the thin plate is high, but its thermal conductivity in the thickness direction of the thin plate is low. For this reason, when thin plate-like boron nitride is blended into a heat dissipation sheet, the boron nitride is oriented parallel to the sheet surface when forming the sheet, so sufficient thermal conductivity cannot be obtained in the thickness direction of the sheet.

[0004] There is an aggregated boron nitride filler as a material for increasing the thermal conductivity in the thickness direction of the sheet. By using the aggregated boron nitride filler, the thermal conductivity in the thickness direction of the sheet can be improved.

[0005] As an aggregated boron nitride filler, an aggregated boron nitride filler with a card house structure has been developed (see, for example, Patent Document 1). Furthermore, an aggregated boron nitride filler with a card house structure having a relatively large average particle diameter and being less likely to collapse even when pressure is applied has been developed (see, for example, Patent Document 2). Since the aggregated boron nitride filler with a card house structure secures a heat conduction path due to the card house structure, by incorporating this into a heat dissipation sheet, the heat conductivity in the thickness direction of the sheet becomes excellent. In the aggregated boron nitride filler, boron nitride particles are aggregated without using a separate binder. Therefore, even when an external force is applied during sheet formation, the card house structure does not easily collapse and maintains the heat conduction path, enabling heat dissipation in the thickness direction of the sheet and achieving excellent heat conductivity (see, for example, Patent Document 3). As a molding method for increasing the heat conductivity in the thickness direction of the sheet, a method of increasing the heat conductivity by bringing the aggregated boron nitride fillers in the sheet into surface contact with each other is known (see, for example, Patent Document 4).

[0006] In Patent Documents 1 to 4, a thermosetting resin composition containing an aggregated boron nitride filler is applied to a base material and heated and pressed to form an aggregated boron nitride filler-containing resin composition layer. However, no detailed study has been made on the pressing treatment conditions and the pressing process.

[0007] Patent Document 5 shows that a coating layer of a resin composition containing a boron nitride filler and alumina is dried, subjected to a heat and pressure treatment and laminated to obtain a resin sheet in a B-stage state, and the resin sheet in the B-stage state is sandwiched between copper foils to obtain a cured product of a resin sheet laminate in a C-stage state having copper foils provided on both sides.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0009] The aggregated boron nitride fillers disclosed in Patent Documents 1 to 3 may have fine voids remaining between the fillers, and further improvement in insulation is required. In Patent Document 4, the handling property of the sheet has not been examined, and improvement in handling property is required for large-area formation.

[0010] In Patent Document 5, since the press pressure at the B-stage is low to obtain the fluidity of the sheet, voids remain in the sheet and the breakdown voltage becomes low. In Patent Document 5, the sheet becomes brittle due to the remaining voids, and further improvement in handling property is required for large-area formation.

[0011] An object of the present invention is to provide a method for manufacturing a resin composition layer formed using a resin composition containing an aggregated inorganic filler and a thermosetting resin, which can improve the handling property of a sheet formed using the resin composition, reduce film breakage and defects due to handling, and improve the breakdown voltage, adhesiveness, and heat resistance of the resin composition layer.

Means for Solving the Problems

[0012] The present inventor has found that, in a method for manufacturing a resin composition layer containing an aggregated inorganic filler and a thermosetting resin, the above problems can be solved by passing through a specific pressing process. The present invention has the following gist.

[0013] [1] A method for manufacturing a resin composition layer comprising a resin composition containing an aggregated inorganic filler and a thermosetting resin, the method for manufacturing a resin composition layer having the following steps (a) and (b). (a) A step of pressing a carrier film and a sheet formed using the resin composition on the carrier film under conditions where the pressing temperature is 0°C or higher and 110°C or lower, and the pressing pressure is 40 MPa or higher and 1000 MPa or lower. (b) A step of pressing the sheet that has undergone step (a) under conditions where the pressing temperature is 70°C or higher and 250°C or lower, and the pressing pressure is 3 MPa or higher and 100 MPa or lower to obtain a resin composition layer.

[0014] [2] The method for manufacturing a resin composition layer according to [1], wherein the reaction rate of the thermosetting resin in the sheet after step (a) obtained by the following method (referred to as "reaction rate (A)") is less than 50%. <Method for measuring and calculating reaction rate (A)> (a) For the sheets before and after step (a), it is calculated by the following formula from the heat of exothermic peak obtained when the temperature is raised from 40°C to 250°C at 10°C / min by differential scanning calorimetry (DSC). Reaction rate (A) (%) = (1 - ((heat of exotherm after step (a)) / (heat of exotherm before step (a)))) × 100

[0015] [3] The method for manufacturing a resin composition layer according to [1] or [2], where when the pressing temperature in step (b) is Tb (°C) and the pressing temperature in step (a) is Ta (°C), Tb > Ta, and 30°C ≤ Tb - Ta ≤ 220°C.

[0016] [4] The method for manufacturing a resin composition layer according to any one of [1] to [3], wherein the reaction rate of the thermosetting resin in the sheet after step (b) obtained by the following method (referred to as "reaction rate (B)") is 60% or higher. <Method for measuring and calculating reaction rate (B)> (a) For the sheets before step (a) and after step (b), it is calculated by the following formula from the heat of exothermic peak obtained when the temperature is raised from 40°C to 250°C at 10°C / min by differential scanning calorimetry (DSC). Reaction rate (B) (%) = (1 - (heat generation amount after step (b) / heat generation amount before step (a))) × 100

[0017] [5] When the press pressure in the step (b) is Pb (MPa) and the press pressure in the step (a) is Pa (MPa), Pa > Pb and Pa / Pb is 1.5 or more and 50 or less. The method for producing a resin composition layer according to any one of [1] to [4].

[0018] [6] When the film thickness after the step (b) is Fb and the film thickness after the step (a) is Fa, Fb / Fa is 0.7 or more and 1.2 or less. The method for producing a resin composition layer according to any one of [1] to [5].

[0019] [7] The press treatment in the step (a) is a flat plate press treatment. The method for producing a resin composition layer according to any one of [1] to [6].

[0020] [8] The press treatment in the step (a) is a roll press treatment. The method for producing a resin composition layer according to any one of [1] to [6].

[0021] [9] The press treatment in the step (a) is a hydrostatic press treatment. The method for producing a resin composition layer according to any one of [1] to [6].

[0022]

[10] The thermosetting resin contains an epoxy compound. The method for producing a resin composition layer according to any one of [1] to [9].

[0023]

[11] The thermosetting resin contains an epoxy compound having a weight average molecular weight of 10,000 or more and an epoxy compound having a weight average molecular weight of 600 or less. The method for producing a resin composition layer according to

[10] .

[0024]

[12] The thermosetting resin contains an epoxy compound having a weight average molecular weight of 600 or less and containing three or more epoxy groups in one molecule. The method for producing a resin composition layer according to

[10] or

[11] .

[0025]

[13] The method for producing a resin composition layer according to any one of [1] to

[12] , wherein the aggregated inorganic filler contains an aggregated boron nitride filler.

[0026]

[14] The method for producing a resin composition layer according to

[13] , wherein the aggregated inorganic filler contains an aggregated boron nitride filler having a card house structure.

[0027]

[15] A resin composition layer obtained by the production method according to any one of [1] to

[14] .

[0028]

[16] A composite body having the resin composition layer according to

[15] and a metal part.

[0029]

[17] A method for producing a composite body having a resin composition layer and a metal part, the method comprising forming the resin composition layer by the method for producing a resin composition layer according to any one of [1] to

[14] . [Effect of the Invention]

[0030] According to the present invention, when producing a resin composition layer containing an aggregated inorganic filler and a thermosetting resin, by passing through a specific pressing step, the handleability of a sheet formed using the resin composition is improved, and damage and defects of the film due to handling are reduced. At the same time, the withstand voltage, adhesiveness, and heat resistance of the obtained resin composition layer can be improved. Furthermore, due to the improvement of adhesiveness, a reduction in thermal resistance at the interface can also be expected. [Embodiments for Carrying Out the Invention]

[0031] Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist.

[0032] [Method for Producing Resin Composition Layer] The method for producing a resin composition layer of the present invention is a method for producing a resin composition layer comprising a resin composition containing an aggregated inorganic filler and a thermosetting resin, and has the following steps (a) and (b). (a) A step of pressing a carrier film and a sheet formed on the carrier film using the resin composition under conditions where the pressing temperature is 0°C or higher and 110°C or lower, and the pressing pressure is 40 MPa or higher and 1000 MPa or lower (b) A step of pressing the sheet obtained in step (a) under conditions where the pressing temperature is 70°C or higher and 250°C or lower, and the pressing pressure is 3 MPa or higher and 100 MPa or lower to obtain a resin composition layer

[0033] Hereinafter, the resin composition layer produced by the method for producing a resin composition layer of the present invention may be referred to as "the resin composition layer of the present invention". Further, the resin composition containing the aggregated inorganic filler and the thermosetting resin for forming the resin composition layer of the present invention may be referred to as "the resin composition of the present invention". In the present invention, the "sheet" refers to a film-like object formed on a carrier film with the resin composition of the present invention, and is distinguished from the resin composition layer of the present invention obtained by curing this.

[0034] The method for producing a resin composition layer of the present invention may have other steps in addition to the above steps (a) and (b). For example, there may be other steps between step (a) and step (b). For example, it may include a drying step, a smoothing step, a lamination step, etc.

[0035] In the method for producing a resin composition layer of the present invention, the sheet formed on the carrier film is made into the resin composition layer of the present invention through a pressing process. The resin composition layer of the present invention may be provided for various uses as it is formed on the carrier film according to the use and the manufacturing process, or may be separated from the carrier film and provided for various uses as a single resin composition layer. The resin composition layer of the present invention may be covered with a protective sheet or the like. One of the preferred forms is a composite body having a metal part on one or both sides of the resin composition layer of the present invention. The resin composition of the present invention may contain other components in addition to the aggregated inorganic filler and the thermosetting resin.

[0036] [Resin Composition] The resin composition of the present invention will be described.

[0037] <Agglomerated inorganic filler> The resin composition of the present invention contains an agglomerated inorganic filler. In order to improve the thermal conductivity and control the coefficient of linear expansion of the resin composition layer to be produced, it is preferable to contain a large amount of the agglomerated inorganic filler. By containing the agglomerated inorganic filler, in the steps (a) and (b) described later, the agglomerated inorganic fillers come into contact with each other and deform, and by contacting with each other on the surface, more heat conduction paths are formed, tending to result in a high thermal conductivity. The agglomeration form of the agglomerated inorganic filler can be confirmed by a scanning electron microscope (SEM). In addition to the agglomerated inorganic filler, the resin composition of the present invention may contain a non-agglomerated inorganic filler and an organic filler.

[0038] As the agglomerated inorganic filler, those having electrical insulation properties can be used, and examples thereof include fillers composed of at least one kind of particles selected from the group consisting of metal carbides, metal oxides, and metal nitrides. Examples of the metal carbide include silicon carbide, titanium carbide, tungsten carbide, and the like. Examples of the metal oxide include magnesium oxide, aluminum oxide, silicon oxide, calcium oxide, zinc oxide, yttrium oxide, zirconium oxide, cerium oxide, ytterbium oxide, sialon (ceramics composed of silicon, aluminum, oxygen, and nitrogen), and the like. Examples of the metal nitride include boron nitride, aluminum nitride, silicon nitride, and the like.

[0039] In the case of power semiconductor applications, since insulation is required, the agglomerated inorganic filler preferably consists of an inorganic compound having a volume resistivity of 1×10 12 Ω·cm or more, particularly 1×10 13 Ω·cm or more and excellent insulation properties. Among them, oxides and nitrides are preferable because the electrical insulation of the resin composition layer formed is sufficient.

[0040] As such aggregated inorganic fillers, more specifically, alumina (Al2O3, volume resistivity 1×10 14 Ω·cm), aluminum nitride (AlN, volume resistivity >1×10 14 Ω·cm), boron nitride (BN, volume resistivity 1×10 14 Ω·cm), silicon nitride (Si3N4, volume resistivity >1×10 14 Ω·cm), silica (SiO2, volume resistivity >1×10 14 Ω·cm), etc. can be mentioned. As the aggregated inorganic filler, among them, alumina, aluminum nitride, boron nitride, and silica are preferable, and especially alumina and boron nitride are preferable.

[0041] The aggregated inorganic filler may be surface-treated with a surface treatment agent. As the surface treatment agent, known surface treatment agents can be used.

[0042] The aggregated inorganic filler may be used alone or two or more kinds may be mixed and used in any combination and ratio.

[0043] There are no particular restrictions on the method and degree of aggregation of the aggregated inorganic filler used in the present invention, but it is preferable to use the following aggregated boron nitride filler as the aggregated inorganic filler. The following aggregated boron nitride filler and a filler having a different shape and type from the aggregated boron nitride filler may be used in combination.

[0044] <Aggregated boron nitride filler> Boron nitride has high thermal conductivity but is in a flaky shape, showing high thermal conductivity in the plane direction of the flakes, but low thermal conductivity in the direction perpendicular to the plane. In order to improve handling, it is preferable to use aggregated particles obtained by collecting the flakes and aggregating them into a spherical shape. For those in which the aggregated boron nitride filler is laminated like a cabbage, it is preferable to align them in the plane direction and make the radial direction of the aggregated particles the direction with better thermal conductivity. The aggregated boron nitride filler more preferably has a card house structure.

[0045] The "card house structure" is described, for example, in Ceramics 43 No.2 (published by the Ceramic Society of Japan in 2008), and it is a structure in which plate-like particles are randomly stacked without orientation. More specifically, the aggregated boron nitride filler having a card house structure is an aggregate of boron nitride primary particles, in which the planar part and the end face part of the primary particles are in contact with each other, and for example, it is an aggregated boron nitride filler having a structure that forms a T-shaped aggregate.

[0046] As the aggregated boron nitride filler used in the present invention, an aggregated boron nitride filler having the above-mentioned card house structure is particularly preferable. By using an aggregated boron nitride filler having a card house structure, the thermal conductivity can be further increased.

[0047] The new Mohs hardness of the aggregated boron nitride filler is not particularly limited, but is preferably 5 or less. There is no particular lower limit for the new Mohs hardness of the aggregated boron nitride filler, but it is, for example, 1 or more. When the new Mohs hardness is 5 or less, the contact between the particles dispersed in the resin composition tends to be surface contact, a thermal conduction path between the particles is formed, and the thermal conduction of the formed resin composition layer tends to be improved.

[0048] The volume average particle diameter of the aggregated boron nitride filler is not particularly limited, but is preferably 10 μm or more, and more preferably 15 μm or more. The volume average particle diameter of the aggregated boron nitride filler is preferably 100 μm or less, and more preferably 90 μm or less. When the volume average particle diameter is 10 μm or more, the number of particles in the resin composition and the resin composition layer of the present invention is relatively small, so the interfacial thermal resistance is reduced due to the reduction of the particle interfaces, and the obtained resin composition layer may have high thermal conductivity. When the volume average particle diameter is equal to or less than the above upper limit value, the surface smoothness of the formed resin composition layer tends to be excellent.

[0049] The volume average particle diameter of the aggregated boron nitride filler means the particle diameter when the cumulative volume becomes 50% when a cumulative curve is drawn with the volume of the powder used for measurement as 100%. The measurement method includes a wet measurement method in which a sample in which aggregated particles are dispersed in a pure water medium containing sodium hexametaphosphate as a dispersion stabilizer is measured using a laser diffraction / scattering particle size distribution measuring device or the like, and a dry measurement method in which measurement is performed using "Morphologi" manufactured by Malvern. The same applies to the volume average particle diameters of other aggregated inorganic fillers and non-aggregated inorganic fillers.

[0050] <Breaking strength of aggregated inorganic filler> The breaking strength of the aggregated inorganic filler is not particularly limited, but is preferably 300 MPa or less, more preferably 100 MPa or less, still more preferably 50 MPa or less, even more preferably 20 MPa or less, particularly preferably 15 MPa or less, and most preferably 10 MPa or less. When the breaking strength is equal to or less than the above upper limit value, the aggregated structure of the aggregated inorganic filler is deformed when press-treated, and the aggregated inorganic fillers are likely to come into surface contact with each other. The lower limit value of the breaking strength of the aggregated inorganic filler is not particularly limited, but from the viewpoint of ease of handling, 2.5 MPa or more is preferable, more preferably 3 MPa or more, still more preferably 3.5 MPa or more, and particularly preferably 4 MPa or more.

[0051] <Elastic modulus of aggregated inorganic filler> The elastic modulus of the aggregated inorganic filler is not particularly limited, but is preferably 10 MPa or more, more preferably 20 MPa or more, still more preferably 30 MPa or more, even more preferably 48 MPa or more, particularly preferably 50 MPa or more, and most preferably 55 MPa or more. If the elastic modulus is equal to or more than the above lower limit value, the aggregated inorganic filler tends to plastically deform in the direction of the press pressure and suppress the collapse of the aggregated structure. The upper limit value of the elastic modulus of the aggregated inorganic filler is not particularly limited, but from the viewpoint that sufficient deformation is easily obtained, it is preferably 5 GPa or less, more preferably 2 GPa or less, still more preferably 1.5 GPa or less, even more preferably 1 GPa or less, particularly preferably 500 MPa or less, most preferably 300 MPa or less, and especially preferably 250 MPa or less.

[0052] When the aggregated inorganic filler is within the above elastic modulus range, it tends to easily maintain a spherical shape during the pressing process. When the fracture strength of the aggregated inorganic filler is within the above range, the portions where the aggregated inorganic fillers are in contact with each other are deformed, and surface contact tends to be facilitated. As a result, while maintaining the high thermal conductivity inside the aggregated inorganic filler, the contact thermal resistance at the interface between the aggregated inorganic fillers and at the interface between the metal part described later and the resin composition layer of the present invention can be reduced, and the overall thermal conductivity can be improved.

[0053] The fracture strength and elastic modulus of the aggregated inorganic filler can be measured after removing the resin of the resin composition layer by firing to take out the aggregated inorganic filler so that the aggregated inorganic filler does not deteriorate when the aggregated inorganic filler is in the resin composition layer.

[0054] <Content of aggregated inorganic filler> The content of the aggregated inorganic filler in the resin composition layer of the present invention is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 45% by mass or more, and particularly preferably 50% by mass or more in 100% by mass of the resin composition layer. Also, it is preferably 99% by mass or less, more preferably 90% by mass or less, still more preferably 85% by mass or less, and particularly preferably 80% by mass or less. The combination of the upper and lower limit values of the content of the aggregated inorganic filler in the resin composition layer of the present invention is not particularly limited, but it is preferably 30% by mass or more and 99% by mass or less, more preferably 40% by mass or more and 90% by mass or less, and particularly preferably 50% by mass or more and 80% by mass or less.

[0055] Therefore, the content of the aggregated inorganic filler in the resin composition of the present invention is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 45% by mass or more, particularly preferably 50% by mass or more, preferably 99% by mass or less, more preferably 90% by mass or less, still more preferably 85% by mass or less, and particularly preferably 80% by mass or less, based on 100% by mass of the solid content in the resin composition. The combination of the upper and lower limit values of the content of the aggregated inorganic filler in the resin composition layer of the present invention is not particularly limited, but is preferably 30% by mass or more and 99% by mass or less, more preferably 40% by mass or more and 90% by mass or less, and particularly preferably 50% by mass or more and 80% by mass or less. Here, the solid content in the resin composition refers to the total of all components other than the solvent in the resin composition.

[0056] When the content of the aggregated inorganic filler is equal to or higher than the above lower limit value, the effect of improving the thermal conductivity and the effect of controlling the coefficient of linear expansion by containing the aggregated inorganic filler can be sufficiently obtained. When the content of the aggregated inorganic filler is equal to or lower than the above upper limit value, the voids in the resin composition layer can be reduced, and the insulation and the interfacial adhesiveness in the composite body tend to be improved.

[0057] <Other non-aggregated inorganic fillers> In the present invention, other non-aggregated inorganic fillers may be used in combination with the aggregated inorganic filler. There is no limitation on the shape of the non-aggregated inorganic filler, and examples include spherical, whisker-like, fibrous, plate-like, etc. Other non-aggregated inorganic fillers may be, for example, scaly boron nitride primary particles, and are not limited to their shape. Other non-aggregated inorganic fillers (non-aggregated inorganic fillers) may be used alone or in any combination and ratio of two or more.

[0058] <Spherical filler> As the non-aggregated inorganic filler used in addition to the aggregated inorganic filler, a spherical filler is preferably used.

[0059] The thermal conductivity of the spherical filler is not particularly limited, but is 1 W / m·K or more, preferably 10 W / m·K or more, more preferably 15 W / m·K or more, still more preferably 20 W / m·K or more, for example, 20 to 30 W / m·K. The spherical filler preferably has a new Mohs hardness of 3.1 or more, for example, 5 to 10. By using such a spherical filler in combination with the above-described aggregated inorganic filler, the adhesion of the resulting resin composition layer to the metal and the heat dissipation property can be enhanced.

[0060] Here, "spherical" may be any material generally recognized as spherical. For example, the average circularity may be 0.4 or more for spherical, or 0.6 or more for spherical. Usually, the upper limit of the average circularity is 1. The circularity can be measured by image processing of its projection image. The circularity can be measured, for example, with the FPIA series of Sysmex Corporation.

[0061] The spherical filler is preferably at least one selected from the group consisting of alumina, synthetic magnesite, crystalline silica, aluminum nitride, silicon nitride, silicon carbide, zinc oxide, and magnesium oxide. By using these preferred spherical fillers, the heat dissipation property of the resulting resin composition layer can be further enhanced.

[0062] The volume average particle diameter of the spherical filler is preferably in the range of 0.5 μm or more and 40 μm or less. When the volume average particle diameter is 0.5 μm or more, the resin and the filler can easily flow during heat molding, and it is considered that the interfacial adhesion force in the composite molded body of the present invention described later can be enhanced. When the volume average particle diameter is 40 μm or less, it becomes easier to maintain the dielectric breakdown characteristics of the resin composition layer.

[0063] <Content of other non-aggregated inorganic fillers> When other non-aggregated inorganic fillers are used in combination with the aggregated inorganic filler, the content ratio of the aggregated inorganic filler to the other non-aggregated inorganic fillers in the resin composition of the present invention and in the resin composition layer of the present invention is not particularly limited, but is preferably 99:1 to 1:99 by mass ratio, more preferably 95:5 to 9:91.

[0064] For the same reason as the content of the aggregated boron nitride filler in the resin composition layer of the present invention, the total content of the aggregated inorganic filler and the other non-aggregated inorganic fillers in the resin composition layer of the present invention is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 45% by mass or more, particularly preferably 50% by mass or more in 100% by mass of the resin composition layer. On the other hand, it is preferably 99% by mass or less, more preferably 90% by mass or less, still more preferably 85% by mass or less, particularly preferably 80% by mass or less.

[0065] Therefore, the total content of the aggregated inorganic filler and the other non-aggregated inorganic fillers in the resin composition of the present invention is preferably 30% by mass or more, more preferably 40% by mass or more, still more preferably 45% by mass or more, particularly preferably 50% by mass or more in 100% by mass of the solid content in the resin composition. On the other hand, it is preferably 99% by mass or less, more preferably 90% by mass or less, still more preferably 85% by mass or less, particularly preferably 80% by mass or less.

[0066] When the total content of the aggregated inorganic filler and the other non-aggregated inorganic fillers is equal to or higher than the above lower limit value, the effect of improving the thermal conductivity and the effect of controlling the linear expansion coefficient by containing the inorganic filler can be sufficiently obtained. When the total content of the aggregated inorganic filler and the other non-aggregated inorganic fillers is equal to or lower than the above upper limit value, voids can be reduced, and the insulation property and the interfacial adhesion in the composite molded body tend to be improved.

[0067] <Other organic fillers> In the resin composition and the resin composition layer of the present invention, an organic filler may be contained separately from the aggregated inorganic filler. In the present invention, the organic filler is a solid component at room temperature composed of an organic component that does not contain an epoxy group and does not fall within the definition of a thermosetting catalyst. Examples of the organic filler include natural products such as wood powder, cellulose which may be modified, starch, various organic pigments, thermoplastic resins, thermosetting resins, and the like. Specific examples include acrylic resin particles, nylon resin particles, polyester resin particles, polystyrene resin particles, silicone resin particles, and the like.

[0068] The inclusion of an organic filler may impart appropriate extensibility to the resin composition, relieve the generated stress, and suppress the occurrence of cracks in the temperature cycle test.

[0069] The upper limit of the average particle diameter of the organic filler is preferably 100 μm or less, more preferably 50 μm or less. By the average particle diameter being below the above upper limit value, a decrease in thermal conductivity can be suppressed and resin composition layers of various thicknesses can be formed. The average particle diameter of the organic filler is also the volume average particle diameter determined from the measurement result of the particle size distribution by volume measured by a laser diffraction particle size distribution measuring device.

[0070] The organic filler may be used alone or in any combination and ratio of two or more.

[0071] <Thermosetting resin> The thermosetting resin contained in the resin composition of the present invention is not particularly limited as long as it can be cured in the presence of a curing agent and a curing catalyst to obtain a cured product.

[0072] Examples of the thermosetting resin include epoxy resins, phenolic resins, polycarbonate resins, unsaturated polyester resins, cyanate resins, maleimide resins, urethane resins, melamine resins, urea resins, and the like. Among these, epoxy resins are preferred from the viewpoints of viscosity, heat resistance, hygroscopicity, and handleability. Examples of the epoxy resin include silicon compounds containing epoxy groups, aliphatic epoxy resins, bisphenol A or F type epoxy resins, novolac type epoxy resins, alicyclic epoxy resins, glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, polyfunctional epoxy resins, and high molecular weight epoxy resins.

[0073] <Epoxy resin> An epoxy resin is a general term for compounds having one or more oxirane rings (epoxy groups) in the molecule. The oxirane ring (epoxy group) contained in the epoxy resin may be either an alicyclic epoxy group or a glycidyl group, but is preferably a glycidyl group from the viewpoints of reaction rate or heat resistance.

[0074] The epoxy resin used in the present invention may be a compound containing an aromatic oxirane ring (epoxy group). Specific examples thereof include bisphenol type epoxy resins obtained by glycidylating bisphenols such as bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethyl bisphenol A, tetramethyl bisphenol F, tetramethyl bisphenol AD, tetramethyl bisphenol S, and tetrafluorobisphenol A; biphenyl type epoxy resins; epoxy resins obtained by glycidylating divalent phenols such as dihydroxynaphthalene and 9,9-bis(4-hydroxyphenyl)fluorene; epoxy resins obtained by glycidylating tris-phenols such as 1,1,1-tris(4-hydroxyphenyl)methane; epoxy resins obtained by glycidylating tetrakis-phenols such as 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane; and novolak type epoxy resins obtained by glycidylating novolaks such as phenol novolak, cresol novolak, bisphenol A novolak, and brominated bisphenol A novolak.

[0075] The epoxy resin contained in the resin composition of the present invention is not particularly limited. For example, it preferably contains one or more selected from various bisphenol type epoxy resins obtained by glycidylating bisphenols such as bisphenol A type epoxy resin and bisphenol F type epoxy resin; various biphenyl type epoxy resins obtained by glycidylating biphenyls; aliphatic type epoxy resins; epoxy resins obtained by glycidylating aromatic compounds having a plurality of hydroxyl groups such as dihydroxynaphthalene and 9,9-bis(4-hydroxyphenyl)fluorene; epoxy resins obtained by glycidylating tris-phenols such as 1,1,1-tris(4-hydroxyphenyl)methane; epoxy resins obtained by glycidylating tetrakis-phenols such as 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane; novolak type epoxy resins obtained by glycidylating novolaks such as phenol novolak, cresol novolak, bisphenol A novolak, and brominated bisphenol A novolak; and silicone-containing epoxy resins.

[0076] The epoxy resin used in the present invention may be of one type or a combination of multiple types of epoxy resins may be used.

[0077] The molecular weight of the epoxy resin used in the present invention is not particularly limited. From the viewpoints of film-forming property, low moisture absorption, and flexibility, it is preferable that the epoxy resin used in the present invention contains a high molecular weight epoxy resin. Specifically, the high molecular weight epoxy resin is preferably an epoxy resin having a weight average molecular weight of 10,000 or more, more preferably an epoxy resin having a weight average molecular weight of 15,000 or more. The high molecular weight epoxy resin is preferably an epoxy resin having a weight average molecular weight of 200,000 or less, more preferably 180,000 or less.

[0078] The high molecular weight epoxy resin is preferably more hydrophobic. Specifically, the larger the epoxy equivalent of the epoxy component, the better. Specifically, the epoxy equivalent is preferably 5,000 g / equivalent or more, more preferably 7,000 g / equivalent or more, and on the other hand, preferably 100,000 g / equivalent or less.

[0079] From the viewpoint of increasing the storage modulus of the resin composition layer of the present invention, it is preferable that the epoxy resin used in the present invention contains an epoxy resin having a weight average molecular weight of 600 or less, particularly 550 or less. The lower limit of the weight average molecular weight of this epoxy resin is not particularly limited, but is usually 100 or more.

[0080] The epoxy resin having a weight average molecular weight of 600 or less used in the present invention is preferably an epoxy resin having two or more epoxy groups in one molecule. It is more preferable to further contain a polyfunctional epoxy resin having a weight average molecular weight of 600 or less and having three or more epoxy groups in one molecule, which will be described later. The epoxy resin having a weight average molecular weight of 600 or less may be used in combination with a polyfunctional epoxy resin having three or more epoxy groups in one molecule and an epoxy resin having two or less epoxy groups in one molecule.

[0081] From the viewpoints of film-forming property, coatability, and heat resistance after curing, it is preferable that the thermosetting resin of the resin composition of the present invention contains an epoxy resin having a weight average molecular weight of 10,000 or more and an epoxy resin having a weight average molecular weight of 600 or less.

[0082] The weight average molecular weight of the epoxy resin is a value in terms of polystyrene measured by gel permeation chromatography. The epoxy equivalent of the epoxy resin is defined as "the weight of the epoxy resin containing 1 equivalent of epoxy groups" and can be measured in accordance with JIS K7236.

[0083] (Polyfunctional epoxy resin with a molecular weight of 600 or less) The resin composition of the present invention more preferably contains, as a thermosetting resin, a polyfunctional epoxy resin having a molecular weight of 600 or less and having three or more epoxy groups in one molecule. in one molecule.

[0084] From the viewpoint of increasing the storage modulus of the resin composition layer, particularly in the case of a large amount of heat generation such as a power semiconductor, an epoxy resin having three or more oxirane rings (epoxy groups) in the molecule is preferable, and an epoxy resin having four or more oxirane rings (epoxy groups) in the molecule is more preferable. By having a plurality of oxirane rings (epoxy groups), particularly glycidyl groups, in the molecule, the crosslink density of the formed resin composition layer is improved, resulting in higher strength. Thereby, when internal stress is generated in the resin composition layer in the moisture absorption reflow test, the resin composition layer can suppress the generation of voids such as voids by maintaining its form without deforming or breaking.

[0085] From the viewpoint of increasing the storage modulus of the resin composition layer, the molecular weight of the polyfunctional epoxy resin is preferably 600 or less, and more preferably 550 or less. The lower limit of the molecular weight of the polyfunctional epoxy resin is not particularly limited, but is usually 100 or more.

[0086] By adding a polyfunctional epoxy resin, it is possible to introduce highly polar oxirane rings (epoxy groups) at a high density. As a result, the effects of physical interactions such as van der Waals forces and hydrogen bonds are enhanced, and the adhesiveness between the metal part and the resin composition layer in the composite body described below can be improved. By adding a polyfunctional epoxy resin, the storage modulus of the resin composition layer after thermosetting can be increased. As a result, after the cured product of the resin composition penetrates into the unevenness of the metal part which is the adherend, a strong anchor effect is exhibited, and the adhesiveness between the metal part and the resin composition layer can be improved.

[0087] Specifically, as the polyfunctional epoxy resin, an epoxy resin having three or more epoxy groups is preferable. As the polyfunctional epoxy resin, for example, jER630 manufactured by Mitsubishi Chemical Corporation, ELM-434 series and ELM-100 series manufactured by Sumitomo Chemical Co., Ltd., EX321L, EX-411, EX-512 manufactured by Nagase ChemteX Corporation, BATG, PETG manufactured by Showa Denko K.K. etc. can be used.

[0088] Only one kind of polyfunctional epoxy resin may be used, or two or more kinds may be used in combination.

[0089] <Content of thermosetting resin> Among the resin composition layers of the present invention, it is preferable that the main component of the resin component excluding the inorganic filler is a thermosetting resin, and particularly preferably contains an epoxy resin. Here, the main component refers to the most abundant component.

[0090] The resin composition layer of the present invention preferably contains 5 to 90% by mass, particularly 10 to 60% by mass of the thermosetting resin in 100% by mass of the resin composition layer. Therefore, the proportion of the thermosetting resin in 100% by mass of the solid content in the resin composition of the present invention is preferably 5 to 90% by mass, particularly 10 to 60% by mass. When the content of the thermosetting resin is above the above lower limit, the moldability becomes good, and when it is below the above upper limit, the content of other components can be ensured and the thermal conductivity can be increased.

[0091] The content of the thermosetting resin in the resin component excluding the inorganic filler in the resin composition layer of the present invention is not particularly limited, but is preferably 20% by mass or more, more preferably 25% by mass or more, still more preferably 30% by mass or more, and particularly preferably 45% by mass or more. Therefore, the content of the thermosetting resin in the solid content excluding the inorganic filler in the resin composition of the present invention is preferably 20% by mass or more, more preferably 25% by mass or more, still more preferably 30% by mass or more, and particularly preferably 45% by mass or more. The upper limit of the content of the thermosetting resin in the resin component excluding the inorganic filler is 100% by mass, and all components other than the inorganic filler may be thermosetting resins. When the proportion of the thermosetting resin is within the above range, low moisture absorption, high elastic modulus, high toughness can be achieved, and at the same time, reaction control becomes easy, and there is a tendency to exhibit the effects of high reflow resistance, high reliability in cycle tests, and high thermal conductivity.

[0092] The content of the high molecular weight epoxy resin having a weight average molecular weight of 10,000 or more, which is the aforementioned preferred epoxy resin, in the resin component of the resin composition layer of the present invention and the resin composition of the present invention is preferably 5% by mass or more, more preferably 10% by mass or more, and on the other hand, preferably 90% by mass or less. The content of the epoxy resin having a weight average molecular weight of 600 or less in the resin component of the resin composition layer of the present invention and the resin composition of the present invention is preferably 5% by mass or more, more preferably 10% by mass or more, and on the other hand, preferably 90% by mass or less. The content ratio of the high molecular weight epoxy resin having a weight average molecular weight of 10,000 or more to the epoxy resin having a weight average molecular weight of 600 or less is preferably 1:18 to 18:1 by mass ratio. When the content of the high molecular weight epoxy resin is above the above lower limit, the film-forming property of the resin composition of the present invention tends to be improved, and when it is below the above upper limit, the strength of the resin composition layer of the present invention can be made excellent.

[0093] <Other components> The resin composition and resin composition layer of the present invention may contain components other than the aggregated inorganic filler and the thermosetting resin. Examples of other components include, for example, the aforementioned non-aggregated inorganic filler, organic filler, and in addition, a curing catalyst, curing agent, surface treatment agent such as silane coupling agent, insulating carbon component such as reducing agent, viscosity modifier, dispersant, thixotropic agent, flame retardant, coloring agent, organic solvent, thermoplastic resin, and the like shown below.

[0094] <Curing catalyst> The resin composition of the present invention may contain a curing catalyst (thermosetting catalyst) in order to adjust the curing rate, physical properties of the cured product, and the like.

[0095] The curing catalyst is not particularly limited, but is appropriately selected according to the type of thermosetting resin used and other components. Specific examples of the curing catalyst include chain or cyclic tertiary amines, organic phosphorus compounds, diazabicycloalkenes such as quaternary phosphonium salts or organic acid salts. As the curing catalyst, organometallic compounds, quaternary ammonium salts, metal halides, or the like can also be used. Examples of organometallic compounds include zinc octylate, tin octylate, or aluminum acetylacetone complex, gallium acetylacetone complex, imidazoles, and the like. From the viewpoints of heat resistance and stability, imidazoles are particularly preferred. These may be used alone or in combination of two or more.

[0096] The curing catalyst is preferably contained in an amount of 0.1 to 10% by mass, particularly 0.1 to 5% by mass, based on 100% by mass of the resin composition of the present invention excluding the solvent and inorganic filler. When the content of the curing catalyst is at least the above lower limit, the progress of the curing reaction can be sufficiently promoted to achieve good curing. When the content of the curing catalyst is at most the above upper limit, the curing rate is not too fast, and thus the storage stability of the resin composition of the present invention can be made good.

[0097] When the curing catalyst is solid, its average particle size is not particularly limited, but the average particle size of at least one or more curing catalysts is preferably 15 μm or less, more preferably 10 μm or less. When the average particle size is below the above upper limit, the solubility of the curing catalyst in the resin component is improved, and the reaction rate tends to increase. Also, the elastic modulus of the formed resin composition layer can be made higher, and the glass transition temperature tends to increase. Furthermore, the dispersibility of the curing catalyst is improved, and the storage stability of the resin composition of the present invention tends to improve. The lower limit value of the average particle size of the curing catalyst is not particularly limited.

[0098] <Curing agent> The resin composition of the present invention may contain a curing agent. The curing agent is not particularly limited, but phenol resins, aliphatic amines, aromatic amines, modified amines, polyamide resins, imidazoles, polymercaptans, polysulfides, acid anhydrides, carboxylic acid-containing compounds, dicyandiamide, etc. are used.

[0099] Among these, for example, phenol resins, acid anhydrides having an aromatic skeleton or an alicyclic skeleton, or hydrogenated products or modified products of the acid anhydrides are preferred. By using these preferred curing agents, a resin composition layer excellent in the balance of heat resistance, moisture resistance, and electrical properties can be obtained. The curing agent may be used alone or in combination of two or more.

[0100] The phenolic resin used as the curing agent is not particularly limited. Specific examples of the phenolic resin include phenol novolac, o-cresol novolac, p-cresol novolac, t-butylphenol novolac, dicyclopentadiene cresol, polyparavinylphenol, bisphenol A type novolac, xylylene-modified novolac, decalin-modified novolac, poly(di-o-hydroxyphenyl)methane, poly(di-m-hydroxyphenyl)methane, or poly(di-p-hydroxyphenyl)methane, etc. Among them, for further improvement of the flexibility and flame retardancy of the resin composition, and improvement of the mechanical properties and heat resistance of the resin composition layer, novolac type phenolic resins having a rigid main chain skeleton or phenolic resins having a triazine skeleton are preferred. For improvement of the flexibility of the resin composition of the present invention and the toughness of the resin composition layer of the present invention, phenolic resins having an allyl group are preferred.

[0101] Commercially available products of phenolic resins include MEH-8005, MEH-8000H, and NEH-8015 (all manufactured by Meiwafosis Co., Ltd.), YLH903 (manufactured by Mitsubishi Chemical Corporation), LA-7052, LA-7054, LA-7751, LA-1356, and LA-3018-50P (all manufactured by Dainippon Ink and Chemicals, Inc.), and PSM6200, PS6313, and PS6492 (manufactured by Gunei Chemical Industry Co., Ltd.), etc.

[0102] The acid anhydride having an aromatic skeleton, the water addition product of the acid anhydride, or the modified product of the acid anhydride used as the curing agent is not particularly limited. Specific examples include SMA resin EF30 and SMA resin EF60 (both manufactured by Sartomer Japan Co., Ltd.), ODPA-M and PEPA (both manufactured by Mannak Co., Ltd.), Ricacidit MTA-10, Ricacidit TMTA, Ricacidit TMEG-200, Ricacidit TMEG-500, Ricacidit TMEG-S, Ricacidit TH, Ricacidit MH-700, Ricacidit MT-500, Ricacidit DSDA, and Ricacidit TDA-100 (all manufactured by Shin Nippon Rika Co., Ltd.), EPICLON B4400, and EPICLON B570 (both manufactured by Dainippon Ink and Chemicals, Inc.), etc.

[0103] The acid anhydride having an alicyclic skeleton, the hydrate of the acid anhydride, or the modified product of the acid anhydride is preferably an acid anhydride having a polyalicyclic skeleton, the hydrate of the acid anhydride, or the modified product of the acid anhydride, or an acid anhydride having an alicyclic skeleton, the hydrate of the acid anhydride, or the modified product of the acid anhydride obtained by the addition reaction of a terpene compound and maleic anhydride. Specific examples include Likazit HNA and Likazit HNA-100 (both manufactured by Shin Nippon Rika Co., Ltd.), and Epicure YH306 and Epicure YH309 (both manufactured by Mitsubishi Chemical Corporation), etc.

[0104] The curing agent is preferably contained in an amount of 0 to 70% by mass, particularly 0 to 55% by mass, in 100% by mass of the resin composition of the present invention excluding the solvent and the inorganic filler. When the content of the curing agent is at least the above lower limit, sufficient curing performance can be obtained. When the content of the curing agent is at most the above upper limit, the reaction proceeds effectively, the crosslink density can be improved, the strength can be increased, and the film-forming property is further improved.

[0105] When the thermosetting resin is an epoxy resin, the content of the reactive group of the curing agent is not particularly limited, but it may be 0 equivalent, preferably 0.05 equivalent or more, more preferably 0.1 equivalent or more, and still more preferably 0.15 equivalent or more, relative to the amount of epoxy groups in the thermosetting resin. The content of the reactive group of the curing agent is preferably 2 equivalents or less, more preferably 1.2 equivalents or less, relative to the amount of epoxy groups in the thermosetting resin. When the content of the reactive group of the curing agent is at least the above lower limit value relative to the amount of epoxy groups in the thermosetting resin, the reduction of the curing rate is suppressed, it becomes difficult for epoxy groups to remain, and there is a tendency to obtain an improvement in the strength of the formed resin composition layer and an effect of suppressing hygroscopicity. When the content of the reactive group of the curing agent relative to the epoxy groups is at most the above upper limit value, the elastic modulus of the formed resin composition layer tends to be high.

[0106] <Dispersant> The resin composition of the present invention may contain a dispersant. By including a dispersant, it becomes possible to form a uniform resin composition layer, and in some cases, the thermal conductivity and dielectric breakdown characteristics of the resulting resin composition layer can be improved.

[0107] The dispersant preferably has a functional group containing a hydrogen atom having hydrogen bonding properties. By having a functional group containing a hydrogen atom having hydrogen bonding properties, the thermal conductivity and dielectric breakdown characteristics of the formed resin composition layer can be further enhanced. Examples of the functional group containing a hydrogen atom having hydrogen bonding properties include a carboxyl group (pKa = 4), a phosphate group (pKa = 7), or a phenol group (pKa = 10), etc.

[0108] The pKa of the functional group containing a hydrogen atom having hydrogen bonding properties is preferably in the range of 2 to 10, and more preferably in the range of 3 to 9. When the pKa is 2 or more, the acidity of the dispersant is within an appropriate range, and in some cases, the reaction of the epoxy resin in the thermosetting resin component is likely to be suppressed. Therefore, when the uncured molded article is stored, the storage stability tends to be improved. When the pKa is 10 or less, the function as a dispersant is sufficiently exerted, and the thermal conductivity and dielectric breakdown characteristics of the formed resin composition layer tend to be sufficiently enhanced.

[0109] The functional group containing a hydrogen atom having hydrogen bonding properties is preferably a carboxyl group or a phosphate group. In this case, the thermal conductivity and dielectric breakdown characteristics of the formed resin composition layer can be further enhanced.

[0110] As the dispersant, specifically, polyester carboxylic acid, polyether carboxylic acid, polyacrylic carboxylic acid, aliphatic carboxylic acid, polysiloxane carboxylic acid, polyester phosphoric acid, polyether phosphoric acid, polyacrylic phosphoric acid, aliphatic phosphoric acid, polysiloxane phosphoric acid, polyester phenol, polyether phenol, polyacrylic phenol, and polysiloxane phenol, etc. may be mentioned. Only one kind of dispersant may be used, or two or more kinds may be used in combination.

[0111] <Thermoplastic resin> The resin composition of the present invention may contain a thermoplastic resin. By containing a thermoplastic resin, appropriate stretchability can be imparted to the formed resin composition layer, the generated stress can be relaxed, and the occurrence of cracks in the temperature cycle test may be suppressed.

[0112] As the thermoplastic resin, any generally known thermoplastic resin can be used. Specifically, as the thermoplastic resin, polyethylene, polypropylene, polystyrene, polyvinyl chloride, (meth)acrylic resin, vinyl polymers such as ethylene-vinyl acetate copolymer and ethylene-vinyl alcohol copolymer, polylactic acid resin, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon and polyamideamine, polyvinyl acetal resins such as polyvinyl acetoacetal, polyvinyl benzal, and polyvinyl butyral resin, ionomer resin, polyphenylene ether, polyphenylene sulfide, polycarbonate, polyether ether ketone, polyacetal, ABS resin, LCP (liquid crystal polymer), fluororesin, urethane resin, silicone resin, various elastomers, and modified products of these resins, etc. may be mentioned.

[0113] The thermoplastic resin may be uniform in the resin phase of the formed resin composition layer, or may be phase-separated and have a recognizable shape. When it is phase-separated, the shape of the thermoplastic resin in the resin composition layer may be particulate or fibrous. The thermoplastic resin may be included as the aforementioned organic filler.

[0114] <Organic solvent> The resin composition of the present invention may contain an organic solvent in order to improve the coatability in the coating step described later.

[0115] Examples of the organic solvent that the resin composition of the present invention may contain include methyl ethyl ketone, cyclohexanone, propylene glycol monomethyl ether acetate, butyl acetate, isobutyl acetate, propylene glycol monomethyl ether, and the like. Only one type of organic solvent may be used, or two or more types may be used in combination.

[0116] When the resin composition of the present invention contains an organic solvent, its content is preferably used such that the solid content (total of components other than the solvent) concentration in the resin composition of the present invention is 10% by mass or more, particularly 40% by mass or more, and 90% by mass or less, particularly 80% by mass or less, from the viewpoint of the coatability of the coating step.

[0117] <Method for producing resin composition> The resin composition of the present invention can be obtained by uniformly mixing the aggregated inorganic filler, the thermosetting resin, and other components added as necessary by stirring or kneading. For the mixing, for example, general kneading apparatuses such as mixers, kneaders, single-screw or twin-screw kneaders can be used. When mixing, heating may be performed as necessary.

[0118] The mixing order of each compounding ingredient is arbitrary as long as there are no particular problems such as reactions or precipitates occurring. For example, a method can be mentioned in which a thermosetting resin component is mixed and dissolved in an organic solvent (for example, methyl ethyl ketone) to prepare a resin solution, and a mixture obtained by sufficiently mixing an aggregated inorganic filler and other components is added to and mixed with the obtained resin solution.

[0119] [Method for manufacturing resin composition layer] The method for manufacturing the resin composition layer of the present invention has steps (a) and (b). In the manufacturing method of the present invention, the following reasons are considered for obtaining the effects of improving handleability, withstand voltage, adhesiveness, and heat resistance.

[0120] In step (a), press treatment is performed at a specific press pressure and press temperature. This press treatment is at a temperature lower than the curing temperature of the thermosetting resin contained in the resin composition of the present invention, and it becomes possible to press while suppressing the reaction rate of the thermosetting resin. As a result, the thermosetting resin easily enters the voids derived from the aggregated inorganic filler, and the voids can be reduced. The brittleness of the resin composition layer obtained by the penetration of the resin into the voids derived from the aggregated inorganic filler is reduced, and the handleability is improved. Furthermore, the sheet after step (a) is subjected to press treatment at a specific press pressure and press temperature in step (b). By performing the specific press treatment in step (b) while suppressing the reaction rate of the thermosetting resin after step (a), the adhesiveness can be improved, and the withstand voltage and heat resistance are improved by allowing the reaction after step (b) to proceed sufficiently. Also, in step (b), by setting the press temperature higher than that in step (a), the fluidity of the thermosetting resin before curing increases, and the voids can be further reduced. By going through these steps (a) and (b), a resin composition layer with improved withstand voltage, adhesiveness, and heat resistance can be obtained.

[0121] <(Step (a))> Step (a) is a step of performing press treatment on a sheet formed with a layer of the resin composition of the present invention on a carrier film under the conditions that the press temperature is 0°C or higher and 110°C or lower, and the press pressure is 40 MPa or higher and 1000 MPa or lower.

[0122] (a) In the process, a sheet is formed on a carrier film using the resin composition of the present invention, and the sheet with the carrier film is subjected to a pressing process under specific conditions. By subjecting the sheet with the carrier film to a pressing process under specific conditions in the (a) process, the sheet handling property up to the (b) process can be improved.

[0123] The method for forming a sheet using the resin composition of the present invention is not particularly limited, and examples include a method of forming by a coating process. In this case, the resin composition of the present invention may contain an organic solvent to improve coatability.

[0124] There are no particular restrictions on the coating method of the resin composition of the present invention. For example, a dip method, a spin coating method, a spray coating method, a blade method, or any other arbitrary method can be adopted. For coating, coating devices such as a spin coater, a slit coater, a die coater, and a blade coater can be used. By these devices, it is possible to uniformly form a sheet (coating film) with a predetermined film thickness on the carrier film.

[0125] The carrier film to be used is not particularly limited, but it is desirable that it does not dissolve in the resin composition of the present invention and has little deformation at the pressing temperature and pressing pressure in the (a) process. For example, an olefin-based film, a polyester film such as PET (polyethylene terephthalate), a polyimide film, a copper material, etc. can be mentioned.

[0126] When a sheet is formed using the resin composition of the present invention containing an organic solvent, it is preferable to remove the solvent by a process such as drying before the pressing in the (a) process. The solid content concentration of the sheet before the pressing in the (a) process is preferably 95% by mass or more, and more preferably 98% by mass or more.

[0127] The drying process is not particularly limited, but it is usually dried at a temperature of 10 to 150°C, preferably 25 to 120°C, more preferably 30 to 110°C. When the drying temperature is below the above upper limit, the curing of the thermosetting resin in the sheet is suppressed, and the resin tends to flow in the subsequent pressing process, making it easier to remove voids. When the drying temperature is above the above lower limit, the organic solvent can be effectively removed.

[0128] When drying at less than 80°C, the drying time is usually 5 minutes to 10 days, preferably 10 minutes to 3 days, more preferably 20 minutes to 1 day, and particularly preferably 30 minutes to 4 hours. When drying at 80°C or higher, 1 minute or more is preferred, 30 minutes or less is preferred, 20 minutes or less is more preferred, 15 minutes or less is even more preferred, and 10 minutes or less is particularly preferred. When the drying time is above the above lower limit, the organic solvent can be sufficiently removed, and the tendency to suppress the residual solvent from becoming voids in the sheet can be achieved. When the drying time is below the above upper limit, productivity tends to improve, and manufacturing costs can be suppressed.

[0129] The pressing temperature in step (a) is 0°C or higher and 110°C or lower, preferably 3°C or higher and 100°C or lower, more preferably less than 100°C, and even more preferably 95°C or lower. Within this temperature range, the reaction rate of the thermosetting resin in step (a) can be suppressed, and a sheet with good handleability can be obtained.

[0130] The pressing pressure in step (a) is 40 MPa or higher and 1000 MPa or lower, preferably 45 MPa or higher, more preferably 50 MPa or higher, preferably 900 MPa or lower, more preferably 700 MPa or lower, and even more preferably 500 MPa or lower. Within this pressure range, voids can be reduced, and a resin composition layer with good thermal conductivity can be obtained.

[0131] The pressing time in step (a) is not particularly limited, but is preferably 1 minute or more, more preferably 3 minutes or more, preferably within 5 hours, and more preferably within 2 hours. When the pressing time is within the above range, a sheet with good handleability and adhesiveness to the metal part can be obtained.

[0132] (a) The reaction rate of the thermosetting resin contained in the sheet after the process (hereinafter sometimes referred to as "reaction rate (A)") is not particularly limited, but is preferably less than 50%. The reaction rate (A) is more preferably 40% or less, still more preferably 30% or less, and particularly preferably 20% or less. When the reaction rate (A) of the thermosetting resin is below the above upper limit, a sheet with good handleability and adhesiveness tends to be obtained. The reaction rate (A) of the thermosetting resin in the sheet is calculated by the following formula from the calorific value of the exothermic peak obtained when the temperature is raised from 40 °C to 250 °C at 10 °C / min by differential scanning calorimetry (DSC) of the sheet before and after the (a) process. Reaction rate (A) (%) = (1 - ((calorific value after the (a) process) / (calorific value before the (a) process))) × 100

[0133] (a) The film thickness (Fa) of the sheet after the process is not particularly limited, but is preferably 10 μm or more, more preferably 20 μm or more, still more preferably 30 μm or more, and preferably 1000 μm or less, more preferably 800 μm or less. When the film thickness (Fa) of the sheet is above the above lower limit, insulation tends to be obtained, and when it is below the above upper limit, the thermal resistance tends to be reduced. The film thickness of the sheet can be measured using a contact-type or non-contact-type film thickness gauge. The same applies to the film thickness (Fb) of the resin composition layer after the (b) process.

[0134] (a) The pressing process is not particularly limited, but each of flat pressing, roll pressing, and isostatic pressing is preferred.

[0135] The specific configuration of the flat press machine for performing press treatment is not particularly limited. For example, it includes a pair of parallel flat plates (press plates) with a mirror-polished hard chromium plating layer disposed on the surface, a pressure control means for controlling the press pressure by the press plates, and a heating means for heating the press plates to a predetermined temperature. An apparatus that sandwiches a sheet between a pair of press plates and presses it from both sides while heating it to a predetermined temperature can be mentioned. In step (a), by performing a flat press treatment with a highly smooth press plate surface, it becomes easier to smooth the surface of the sheet, and the adhesiveness between the formed resin composition layer and the metal part tends to improve.

[0136] By performing roll press treatment, the smoothing of the sheet surface can be carried out in step (a), and the productivity tends to improve. The specific configuration of the roll machine for performing roll press treatment is not particularly limited, and various roll machines such as a type equipped with a pair of nip rolls and a multi-stage nip roll type can be used. As a roll machine for performing roll press treatment, for example, it includes a preheat roll (which may not be necessary in some cases), at least a pair of nip rolls, and preferably a heating means for heating the nip rolls, and is configured to press and smooth the surface of the sheet by sandwiching the sheet between a pair of nip rolls and pressing it from both sides.

[0137] By performing hydrostatic press treatment, high-pressure pressing over a large area becomes possible, and the press unevenness of the sheet tends to be suppressed. In hydrostatic press treatment, since multiple sheets can be processed simultaneously, the productivity tends to improve. The specific configuration of the hydrostatic press machine is not particularly limited. For example, it includes a pressure vessel filled with a liquid such as oil or water, a pressure cylinder for pressurizing the liquid, a control means for controlling the pressure for pressurizing the liquid, and a heating means for heating the liquid to a predetermined temperature. More specifically, a sheet with a carrier film is vacuum-packed and immersed in a liquid such as oil or water in a hydrostatic press machine to perform hydrostatic press, so that the sheet is pressed with a uniform pressure and the surface of the sheet is smoothed. An apparatus configured in this way can be mentioned.

[0138] <(b) process> (b) The process is a process of pressing the sheet that has undergone the (a) process at a pressing temperature of 70°C or higher and 250°C or lower and a pressing pressure of 3 MPa or higher and 100 MPa or lower to obtain a resin composition layer.

[0139] (b) The method of performing the pressing process is not particularly limited, and for example, it can be performed by a flat press.

[0140] (b) The process is for supplying the sheet that has undergone the (a) process, and a single sheet, a laminate of a carrier film / sheet / metal part, a laminate of a metal part / sheet, etc. may be pressed. The manufacturing method of the present invention is a method with excellent adhesiveness and is suitable for a manufacturing method of pressing a laminate including a metal part and a sheet.

[0141] (b) The pressing temperature in the process is 70°C or higher and 250°C or lower, preferably 75°C or higher, more preferably 80°C or higher, preferably 240°C or lower, more preferably 230°C or lower, and even more preferably 220°C or lower. By being within this temperature range, a resin composition layer having high elastic modulus, adhesiveness, and heat resistance tends to be obtained.

[0142] (b) The pressing pressure in the process is 3 MPa or higher and 100 MPa or lower, preferably 3.5 MPa or higher, and more preferably 4 MPa or higher. By being within this pressure range, a resin composition layer excellent in withstand voltage, thermal conductivity, and adhesiveness tends to be obtained.

[0143] (b) The pressing time of the pressing process is not particularly limited, but is preferably 5 minutes or longer, more preferably 10 minutes or longer, and preferably within 24 hours. The pressing time is preferably such that the reaction rate (B) of the thermosetting resin described later becomes 60% or higher.

[0144] (b) The reaction rate of the thermosetting resin contained in the sheet after the process (hereinafter, may be referred to as "reaction rate (B)") is not particularly limited, but is preferably 60% or more, more preferably 70% or more, still more preferably 80% or more, and particularly preferably 80% or more. The upper limit of the reaction rate (B) is not particularly limited, but is 100%. When the reaction rate (B) of the thermosetting resin is within the above range, sufficient curing proceeds, and a resin composition layer excellent in heat resistance and adhesiveness tends to be obtained. The reaction rate (B) of the thermosetting resin in the sheet is calculated by the following formula from the calorific value of the exothermic peak obtained when the temperature is raised from 40°C to 250°C at 10°C / min by differential scanning calorimetry (DSC) of the sheet before the process (a) and after the process (b). Reaction rate (B) (%) = (1 - ((calorific value after the process (b)) / (calorific value before the process (a)))) × 100

[0145] (b) The film thickness (Fb) of the resin composition layer after the process is not particularly limited, but is preferably 10 μm or more, more preferably 20 μm or more, still more preferably 30 μm or more, and preferably 1000 μm or less, more preferably 800 μm or less. When the film thickness (Fb) of the resin composition layer is at least the above lower limit, insulation tends to be obtained, and when it is at most the above upper limit, the thermal resistance tends to be reduced.

[0146] <Combination of the process (a) and the process (b)> (a) The pressing conditions of the process and the process (b), and the film thicknesses of the sheet and the resin composition layer are not particularly limited as long as they are within the above ranges, but the following combinations are particularly preferred.

[0147] When the pressing temperature of the process (b) is Tb (°C) and the pressing temperature of the process (a) is Ta (°C), Tb > Ta and 30°C ≤ Tb - Ta ≤ 220°C is preferred. Tb - Ta is preferably 30 °C or higher, more preferably 40 °C or higher, preferably 220 °C or lower, more preferably 200 °C or lower, and even more preferably 180 °C or lower. When Tb - Ta is within the above range, the handleability of the sheet and the adhesiveness of the resin composition layer tend to be compatible.

[0148] Regarding the press pressure, when the press pressure in step (b) is Pb (MPa) and the press pressure in step (a) is Pa (MPa), Pa > Pb, and Pa / Pb is 1.5 or more and 50 or less which is preferable. Pa / Pb is preferably 1.5 or more, more preferably 1.8 or more, even more preferably 2 or more, preferably 50 or less, more preferably 45 or less, and even more preferably 40 or less. When Pa / Pb is within the above range, voids in the resin composition layer can be reduced, and the shape of the aggregated inorganic filler is moderately maintained, so that a resin composition layer excellent in withstand voltage and thermal conductivity can be obtained.

[0149] Regarding the film thickness of the resin composition layer and the sheet, when the film thickness of the resin composition layer after step (b) is Fb and the film thickness of the sheet after step (a) is Fa, the ratio (Fb / Fa) is preferably 0.7 or more and 1.2 or less. Fb / Fa is preferably 0.7 or more, more preferably 0.8 or more, even more preferably 0.85 or more, preferably 1.2 or less, and more preferably 1.1 or less. That Fb / Fa is within the above range indicates that voids in the sheet are efficiently reduced after step (a) and the film thickness change before and after step (b) becomes small, and there is a tendency to obtain a resin composition layer excellent in withstand voltage and thermal conductivity.

[0150] In the present invention, as step (a), a sheet is formed on a carrier film using the resin composition of the present invention, and the carrier film is subjected to a press treatment together. As step (b), it is particularly preferable to perform a press treatment on a laminate including the metal part and the sheet in a state where the sheet that has undergone step (a) is in contact with the metal part.

[0151] [Thermal Conductivity and Dielectric Strength of the Resin Composition Layer] The thermal conductivity and dielectric strength of the resin composition layer of the present invention are not particularly limited, but the thermal conductivity is preferably 8 W / mK or more, more preferably 9 W / mK or more, and even more preferably 10 W / mK or more. The dielectric strength of the resin composition layer of the present invention is preferably 30 kV / mm or more, more preferably 35 kV / mm or more, and particularly preferably 40 kV / mm or more. The method for measuring the thermal conductivity and dielectric strength in the present invention is not particularly limited, and examples include the methods shown in the examples described below.

[0152] [Composite Molded Body] The composite molded body of the present invention is formed by laminating and integrating the resin composition layer of the present invention and the metal part. The metal part may be provided only on one surface of the resin composition layer of the present invention, or may be provided on two or more surfaces. For example, it may have a metal part only on one surface of the resin composition layer, or may have metal parts on both surfaces. Further, the metal part may be patterned.

[0153] Such a composite molded body of the present invention can be manufactured, for example, by using a metal part as a base material (carrier film), forming the resin composition of the present invention in a sheet shape on this base material, and performing the pressing in the aforementioned steps (a) and (b). By overlapping with another metal plate during step (b), a composite molded body having metal parts on both sides can also be obtained.

[0154] Further, the composite molded body of the present invention can also be manufactured by peeling the sheet-shaped resin composition formed on a base material (carrier film) different from the metal part from the carrier film after step (a), overlapping it on a metal member serving as the metal part, and performing the pressing in step (b).

[0155] In this case, the sheet-like resin composition of the present invention may be peeled from the carrier film after step (a) in the same manner as above, except that it is applied onto a carrier film such as PET which may be treated with a release agent, and then the sheet-like resin composition is placed on another metal plate or sandwiched between two metal plates, and integrated by performing the press in step (b).

[0156] As the metal plate, a metal plate having a thickness of about 10 μm to 10 cm made of copper, aluminum, nickel-plated metal, etc. can be used. The surface of the metal plate may be physically roughened or chemically treated with a surface treatment agent or the like. From the viewpoint of the adhesiveness between the resin composition layer and the metal plate, it is more preferable that these treatments are performed.

[0157] [Semiconductor device] The composite body of the present invention can be used as a semiconductor device. In particular, it can be effectively used in a power semiconductor device capable of achieving high output and high density by operating at a high temperature. [Examples]

[0158] Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples as long as the gist thereof is not exceeded. The various conditions and the values of the evaluation results in the following examples show the preferable ranges in the embodiments of the present invention, in the same manner as the preferable ranges in the embodiments of the present invention. The preferable range of the present invention can be determined in consideration of the preferable ranges in the above-described embodiments and the ranges shown by the values in the following examples or the combinations of the values between the examples.

[0159] [Raw materials] The raw materials used in the examples and comparative examples are as follows.

[0160] [Thermosetting resin] Resin component 1: An epoxy resin produced according to the production method of the epoxy resin disclosed in the examples of JP-A-2006-176658 Weight average molecular weight in terms of polystyrene: 30,000 Epoxy equivalent: 9,000 g / equivalent Resin component 2: Bisphenol A type liquid epoxy resin, weight average molecular weight: 600 or less Resin component 3: Biphenyl type solid epoxy resin, weight average molecular weight: 600 or less Resin component 4: Non-aromatic polyfunctional epoxy resin containing a structure having 4 or more glycidyl groups per molecule, weight average molecular weight: 600 or less

[0161] <Aggregated inorganic filler> Inorganic filler 1: Boron nitride aggregated particles having a card house structure, manufactured in accordance with the method for manufacturing boron nitride aggregated particles disclosed in the examples of International Publication No. 2015 / 561028 New Mohs hardness: 2 Volume average particle diameter: 45 μm

[0162] <Other fillers> Inorganic filler 2: Spherical alumina particles manufactured by Admatechs Co., Ltd. New Mohs hardness: 9 Volume average particle diameter: 6.5 μm Thermal conductivity: 20 - 30 W / m·K

[0163] <Hardener> Hardener 1: "MEH-8000H" manufactured by Meiwa Kasei Co., Ltd. Phenolic resin-based hardener

[0164] <Hardening catalyst component> Hardening catalyst 1: "Curezol 2E4MZ-A" manufactured by Shikoku Kasei Co., Ltd. Hardening catalyst 2: "Curezol 2PHZ-PW" manufactured by Shikoku Kasei Co., Ltd.

[0165] [Measurement method] <Reaction rate of thermosetting resin> (a) Process, differential scanning calorimetry (DSC) was performed on the sheet formed before and after each process of the (b) process ((resin composition layer after the (b) process)), and the reaction rate was calculated from the heat of exothermic peak obtained when the temperature was raised from 40 °C to 250 °C at 10 °C / min using the following formula for each case. Reaction rate (A) (%) of the (a) process = (1 - ((heat of exotherm after the (a) process) / (heat of exotherm before the (a) process))) × 100 Reaction rate (B) (%) of the (b) process = (1 - ((heat of exotherm after the (b) process) / (heat of exotherm before the (a) process))) × 100

[0166] <Thermal conductivity in the thickness direction of the resin composition layer> Using a thermal resistance measuring device (manufactured by Mentor Graphics Corporation, product name "T3ster"), the thermal resistance values of resin composition layers with different thicknesses prepared under the same composition and the same conditions were measured, and the thermal conductivity was determined from the slope of the graph obtained by plotting the thermal resistance values against the thickness.

[0167] <Dielectric strength of the resin composition layer> In insulating oil, the voltage applied to the resin composition layer was increased by 500 V every minute, and the voltage at which the resin composition layer was broken down was determined. The obtained breakdown voltage value was converted to the breakdown voltage per 1 mm of film thickness to obtain the dielectric strength (kV / mm) value.

[0168] <Handling property test of the sheet (mandrel test)> The sheet with the carrier film after the (a) process was subjected to a bending test at 24 °C with the carrier film on the inside in accordance with JIS K 5600-5-1. A 180° bending test was performed using an 8-mm diameter mandrel, and those with cracks or peeling visible to the naked eye were marked with ×, and those without cracks or peeling were marked with 〇.

[0169] [Example 1] Using a rotation-revolution stirring device, Resin Component 1, Resin Component 2, Resin Component 4, Hardening Agent 1, Hardening Catalyst 1, Inorganic Filler 1, and Inorganic Filler 2 were mixed to form a mixture in the mass ratio described in Composition A of Table 1 below. When preparing this mixture, a slurry-like resin composition was prepared using 18.5 mass% each of methyl ethyl ketone and cyclohexanone so that the above mixture would be 63 mass% (solid content concentration) in the coating slurry.

[0170] The obtained slurry-like resin composition was applied onto a PET film by the doctor blade method and heated and dried at 60°C for 120 minutes. Then, as step (a), using a flat press machine, pressure was applied to the PET film together at 50°C and 147 MPa for 10 minutes to obtain a sheet with a thickness of 150 μm. The total content of methyl ethyl ketone and cyclohexanone in the sheet was 1 mass% or less (solid content concentration 99 mass% or more). The reaction rate (A) of the thermosetting resin in the sheet after step (a) was less than 10%.

[0171] After laminating a copper substrate onto the sheet that had undergone step (a), as step (b), curing was performed at 175°C and 9.8 MPa for 30 minutes to obtain a resin composition layer. The thickness of the resin composition layer was 141 μm, and the ratio of the film thickness after step (b) to the film thickness after step (a) (Fb / Fa) was 0.94. The evaluation results of the handling property of the sheet (mandrel test) are shown in Table 2A. The reaction rate (B) of the thermosetting resin in the resin composition layer after step (b) was 90% or more, and the breakdown voltage of the resin composition layer was 53 kV / mm.

[0172] The measurement of the thermal conductivity of the resin composition layer of Example 1 was performed on the following samples having the same composition and having undergone the same steps (a) and (b). The sheet-like resin composition after step (a) was sandwiched between PET films and cured at the predetermined pressure and temperature of step (b) to obtain a resin composition layer. Also, in the same manner, after peeling off the carrier film of the sheet after step (a), samples stacked two, three, and four layers were each sandwiched between PET films and processed at a predetermined pressure / temperature in step (b), thereby obtaining four resin composition layers with different thicknesses. When the thermal conductivity of the resin composition layer was measured by the above method, it was 15 W / mK. These results are summarized in Table 2A.

[0173] <Examples 2 to 6, Comparative Examples 1 to 7> Based on the method of Example 1, a resin composition was prepared with Composition A or B shown in Table 1 and processed under the press conditions and press methods shown in Tables 2A and 2B. The results are summarized in Tables 2A and 2B.

[0174]

Table 1

[0175]

Table 2A

[0176]

Table 2B

[0177] From Tables 2A and 2B, it can be seen that according to the present invention, by processing at a predetermined pressure / temperature in steps (a) and (b), a resin composition layer with good withstand voltage and thermal conductivity can be obtained.

[0178] Although the present invention has been described in detail using specific embodiments, it is obvious to those skilled in the art that various changes can be made without departing from the intention and scope of the present invention. This application is based on Japanese Patent Application No. 2020-069766 filed on April 8, 2020, the entire contents of which are incorporated herein by reference.

Claims

1. A method for manufacturing a resin composition layer comprising a resin composition containing an aggregated inorganic filler and a thermosetting resin, the method for manufacturing a resin composition layer having the following steps (a) and (b). (a) A step of pressing a carrier film and a sheet formed using the resin composition on the carrier film under conditions where the pressing temperature is 3°C or higher and 95°C or lower, the pressing pressure is 40 MPa or higher and 500 MPa or lower, and the pressing time is 3 minutes or longer and 2 hours or shorter (b) A step of pressing the sheet that has undergone step (a) under conditions where the pressing temperature is 70°C or higher and 250°C or lower, the pressing pressure is 3 MPa or higher and 100 MPa or lower, and the pressing time is 5 minutes or longer and 24 hours or shorter to obtain a resin composition layer

2. The method for manufacturing a resin composition layer according to claim 1, wherein the reaction rate of the thermosetting resin in the sheet after step (a) (referred to as "reaction rate (A)") obtained by the following method is less than 50%. <Method for measuring and calculating reaction rate (A)> For the sheets before and after step (a), it is calculated by the following formula from the heat of exothermic peak obtained when the temperature is raised from 40°C to 250°C at 10°C / min by differential scanning calorimetry (DSC). Reaction rate (A) (%) = (1 - ((heat of exotherm after step (a)) / (heat of exotherm before step (a)))) × 100

3. The method for manufacturing a resin composition layer according to claim 1 or 2, wherein when the pressing temperature in step (b) is Tb (°C) and the pressing temperature in step (a) is Ta (°C), Tb > Ta and 30°C ≤ Tb - Ta ≤ 220°C.

4. The method for manufacturing a resin composition layer according to any one of claims 1 to 3, wherein the reaction rate of the thermosetting resin in the sheet after step (b) (referred to as "reaction rate (B)") obtained by the following method is 60% or higher. <Method for measuring and calculating reaction rate (B)> For the sheets before step (a) and after step (b), it is calculated by the following formula from the heat of exothermic peak obtained when the temperature is raised from 40°C to 250°C at 10°C / min by differential scanning calorimetry (DSC). Reaction rate (B) (%) = (1 - ((heat of exotherm after step (b)) / (heat of exotherm before step (a)))) × 100

5. The method for manufacturing a resin composition layer according to any one of claims 1 to 4, wherein when the pressing pressure in step (b) is Pb (MPa) and the pressing pressure in step (a) is Pa (MPa), Pa > Pb and Pa / Pb is 1.5 or more and 50 or less.

6. In the case where the film thickness after the step (b) is Fb and the film thickness after the step (a) is Fa, the manufacturing method of the resin composition layer according to any one of claims 1 to 5, wherein Fb / Fa is 0.7 or more and 1.2 or less.

7. The manufacturing method of the resin composition layer according to any one of claims 1 to 6, wherein the pressing treatment in the step (a) is a flat pressing treatment.

8. The manufacturing method of the resin composition layer according to any one of claims 1 to 6, wherein the pressing treatment in the step (a) is a roll pressing treatment.

9. The pressing treatment in the step (a) is a hydrostatic pressing treatment, according to any one of claims 1 to 6 in the manufacturing method of the resin composition layer described in the section.

10. The manufacturing method of the resin composition layer according to any one of claims 1 to 9, wherein the thermosetting resin contains an epoxy compound.

11. The manufacturing method of the resin composition layer according to claim 10, wherein the thermosetting resin contains an epoxy compound having a weight average molecular weight of 10,000 or more and an epoxy compound having a weight average molecular weight of 600 or less.

12. The manufacturing method of the resin composition layer according to claim 10 or 11, wherein the thermosetting resin contains an epoxy compound having a weight average molecular weight of 600 or less and containing three or more epoxy groups in one molecule.

13. The manufacturing method of the resin composition layer according to any one of claims 1 to 12, wherein the aggregated inorganic filler contains an aggregated boron nitride filler.

14. The manufacturing method of the resin composition layer according to claim 13, wherein the aggregated inorganic filler contains an aggregated boron nitride filler having a card house structure.

15. A method for manufacturing a composite body having a resin composition layer and a metal part, wherein the resin composition layer is formed by the method for manufacturing a resin composition layer according to any one of claims 1 to 14.

Images