Method for manufacturing resin composition layer, resin composition layer obtained by the method, and composite molded body comprising the resin composition layer

Abstract

A method for producing a resin composition layer, which is a method for producing a resin composition layer composed of a resin composition containing agglomerated inorganic filler and a thermosetting resin, the method for producing a resin composition layer having the following (a) step and (b) step: (a) a step of subjecting a support film and a sheet formed on the support film using the resin composition to a press treatment under conditions in which 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; and (b) a step of subjecting the sheet subjected to the (a) step to a press treatment under conditions in which the press temperature is 70°C or higher and 250°C or lower and the press pressure is 3 MPa or higher and 100 MPa or lower, to obtain a resin composition layer.

Description

TECHNICAL FIELD

[0001] The present application relates to a resin composition layer manufacturing method, a resin composition layer obtained by the manufacturing method, and a composite molded body including the resin composition layer. The resin composition layer and the composite molded body obtained by the resin composition layer manufacturing method of the present application are, for example, suitably used as a heat dissipation material for a power semiconductor device. BACKGROUND

[0002] Many studies have been made on heat dissipation sheets having good thermal conductivity and excellent insulation. In particular, attempts have been made to obtain a heat dissipation resin sheet satisfying high levels of thermal conductivity and insulation by mixing a filler in a resin. As the filler contained in the heat dissipation resin sheet, various oxides or nitrides are used, and many studies have been made on the particle diameter, particle size distribution, and the like thereof.

[0003] In the past, the use of hexagonal boron nitride has been studied as a filler contained in a heat dissipation sheet. Hexagonal boron nitride is generally a thin plate-like crystal, and has high thermal conductivity in the plane direction of the thin plate, but low thermal conductivity in the thickness direction of the thin plate. Therefore, if thin plate-like boron nitride is incorporated in a heat dissipation sheet, the boron nitride is oriented in parallel with the sheet surface when the sheet is manufactured, and thus sufficient thermal conductivity cannot be obtained in the thickness direction of the sheet.

[0004] As a material for improving the thermal conductivity in the thickness direction of the sheet, there is an agglomerated boron nitride filler. By using an agglomerated boron nitride filler, the thermal conductivity in the thickness direction of the sheet can be improved.

[0005] As an agglomerated boron nitride filler, an agglomerated boron nitride filler having a card-house structure has been developed (for example, see Patent Literature 1). Furthermore, an agglomerated boron nitride filler having a card-house structure and having a large average particle diameter and being less likely to collapse even if a pressure is applied has been developed (for example, see Patent Literature 2). Since the agglomerated boron nitride filler having a card-house structure can secure a heat conduction path of the card-house structure, by containing it in a heat dissipation sheet, the thermal conductivity in the thickness direction of the sheet can be made excellent.

[0006] The agglomerated boron nitride filler is agglomerated boron nitride particles without using a binder. Therefore, when the sheet is manufactured, even if an external force is applied, the card-house structure is not easily collapsed, a heat conduction path can be maintained, heat is dissipated in the thickness direction of the sheet, and excellent heat conduction can be achieved (for example, see Patent Literature 3).

[0007] As a molding method for improving the heat conduction in the thickness direction of the sheet, a method of improving the thermal conductivity by making the agglomerated boron nitride fillers in the sheet face contact with each other is known (for example, see Patent Literature 4).

[0008] In Patent Literatures 1 to 4, a thermosetting resin composition containing agglomerated boron nitride fillers is applied to a substrate and subjected to heating and pressurization to form a resin composition layer containing agglomerated boron nitride fillers. However, the pressing treatment conditions and the pressing process are not studied in detail.

[0009] In Patent Literature 5, it is disclosed that a coated layer of a resin composition containing boron nitride fillers and alumina is dried and subjected to heating and pressurization to obtain a B-stage resin sheet; and a C-stage resin sheet laminated body cured product provided with copper foils on both surfaces is obtained by sandwiching the B-stage resin sheet with copper foils.

[0010] Patent Literature 1: Japanese Patent No. 5679083

[0011] Patent Literature 2: Japanese Patent Application Laid-Open No. 2016-135730

[0012] Patent Literature 3: International Publication No. 2015 / 119198

[0013] Patent Literature 4: International Publication No. 2019 / 189746

[0014] Patent Literature 5: Japanese Patent Application Laid-Open No. 2016-79304

[0015] The agglomerated boron nitride fillers disclosed in Patent Literatures 1 to 3 sometimes have fine pores remaining between the fillers, and the insulation property needs to be further improved.

[0016] In Patent Literature 4, the handleability of the sheet is not studied, and the handleability needs to be improved for large-area use.

[0017] In Patent Literature 5, in order to obtain the flowability of the sheet, the pressing pressure in the B-stage is low, and therefore, pores remain in the sheet, and the withstand voltage becomes low. In Patent Literature 5, the sheet becomes brittle due to the remaining pores, and the handleability needs to be further improved for large-area use. SUMMARY

[0018] The present application has been made to solve the above problems, and provides a method for manufacturing a resin composition layer, which is capable of improving the handleability of a sheet formed using a resin composition containing agglomerated inorganic fillers and a thermosetting resin, reducing breakage or defects of the sheet due to handling, and improving the withstand voltage, adhesion, and heat resistance of the resin composition layer when the resin composition layer is manufactured using the resin composition.

[0019] The present inventors have found that the above problems can be solved by a specific pressing process in a method for manufacturing a resin composition layer containing agglomerated inorganic fillers and a thermosetting resin.

[0020] The gist of the present application is as follows:

[0021] [1] A method for manufacturing a resin composition layer, which is a method for manufacturing a resin composition layer composed of a resin composition containing agglomerated inorganic filler and a thermosetting resin, the method comprising the following (a) step and (b) step:

[0022] (a) a step of subjecting a carrier film and a sheet formed on the carrier film using the resin composition to a press treatment under conditions in which 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;

[0023] (b) a step of subjecting the sheet after the (a) step to a press treatment under conditions in which the press temperature is 70°C or higher and 250°C or lower and the press pressure is 3 MPa or higher and 100 MPa or lower, to obtain a resin composition layer.

[0024] [2] The method for manufacturing a resin composition layer according to [1], wherein the reaction rate of the thermosetting resin of the sheet after the (a) step, which is referred to as "reaction rate (A)", is less than 50%,

[0025] <Measurement and calculation method of reaction rate (A)>

[0026] The reaction rate (A) (%) is calculated from the heat generation amount of the exothermic peak obtained when the sheet before and after the (a) step is subjected to differential scanning calorimetry (DSC) at a temperature increase rate of 10°C / min from 40°C to 250°C, by the following formula:

[0027] Reaction rate (A) (%) = (1 - ((heat generation amount after the (a) step) / (heat generation amount before the (a) step))) x 100.

[0028] [3] The method for manufacturing a resin composition layer according to [1] or [2], wherein, when the press temperature of the (b) step is set to Tb (°C) and the press temperature of the (a) step is set to Ta (°C), Tb > Ta and 30°C ≦ Tb - Ta ≦ 220°C.

[0029] [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 of the sheet after the (b) step, which is referred to as "reaction rate (B)", is 60% or more.

[0030] <Measurement and calculation method of reaction rate (B)>

[0031] The reaction rate (B) (%) is calculated from the heat generation amount of the exothermic peak obtained when the sheet before the (a) step and after the (b) step is subjected to differential scanning calorimetry (DSC) at a temperature increase rate of 10°C / min from 40°C to 250°C, by the following formula:

[0032] Reaction rate (B) (%) = (1 - ((b) after the process heat quantity / (a) before the process heat quantity)) x 100.

[0033] [5] The method for producing a resin composition layer according to any one of [1] to [4], wherein, when a pressing pressure of the (b) process is set to Pb (MPa) and a pressing pressure of the (a) process is set to Pa (MPa), Pa > Pb and Pa / Pb is 1.5 or more and 50 or less.

[0034] [6] The method for producing a resin composition layer according to any one of [1] to [5], wherein, when a film thickness after the (b) process is set to Fb and a film thickness after the (a) process is set to Fa, Fb / Fa is 0.7 or more and 1.2 or less.

[0035] [7] The method for producing a resin composition layer according to any one of [1] to [6], wherein the pressing treatment of the (a) process is a flat plate pressing treatment.

[0036] [8] The method for producing a resin composition layer according to any one of [1] to [6], wherein the pressing treatment of the (a) process is a roll pressing treatment.

[0037] [9] The method for producing a resin composition layer according to any one of [1] to [6], wherein the pressing treatment of the (a) process is a hydrostatic pressure pressing treatment.

[0038]

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

[0039]

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

[10] , wherein the thermosetting resin comprises 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.

[0040]

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

[10] or

[11] , wherein the thermosetting resin comprises an epoxy compound having a weight average molecular weight of 600 or less and containing 3 or more epoxy groups per molecule.

[0041]

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

[12] , wherein the agglomerated inorganic filler comprises an agglomerated boron nitride filler.

[0042]

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

[13] , wherein the agglomerated inorganic filler comprises an agglomerated boron nitride filler having a sheet shelf structure.

[0043]

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

[14] .

[0044]

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

[15] and a metal portion.

[0045]

[17] A production method of a composite molded body, which is a method of producing a composite molded body having a resin composition layer and a metal portion, wherein the resin composition layer is formed by the production method of a resin composition layer according to any one of [1] to

[14] .

[0046] Effects of the Invention

[0047] According to the present application, by performing a specific pressing process when producing a resin composition layer containing agglomerated inorganic filler and thermosetting resin, it is possible to improve the operability of a sheet formed using the resin composition, reduce breakage or defects of the film due to the operation, while improving the voltage resistance, adhesion, and heat resistance of the obtained resin composition layer. Furthermore, since the adhesion is improved, it is also possible to expect a reduction in thermal resistance at the interface. DETAILED DESCRIPTION

[0048] Hereinafter, the embodiments of the present application will be described in detail, but the present application is not limited to the following embodiments, and various modifications can be made within the scope of the gist thereof.

[0049] [Production method of resin composition layer]

[0050] The production method of the resin composition layer of the present application is a method of producing a resin composition layer composed of a resin composition containing agglomerated inorganic filler and thermosetting resin, and the production method has the following (a) process and (b) process:

[0051] (a) a process of subjecting a carrier film and a sheet formed on the carrier film using the above resin composition to a pressing treatment under conditions of a pressing temperature of 0°C or higher and 110°C or lower and a pressing pressure of 40 MPa or higher and 1000 MPa or lower;

[0052] (b) a process of subjecting the sheet subjected to the process of (a) to a pressing treatment under conditions of 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.

[0053] Hereinafter, the resin composition layer produced by the production method of the resin composition layer of the present application will be sometimes referred to as "the resin composition layer of the present application". In addition, the resin composition containing agglomerated inorganic filler and thermosetting resin used for forming the resin composition layer of the present application will be sometimes referred to as "the resin composition of the present application".

[0054] In this invention, "sheet" refers to a film formed on a carrier film by the resin composition of this invention, which is different from the resin composition layer of this invention obtained by curing it.

[0055] The method for manufacturing the resin composition layer of the present invention may include other steps besides steps (a) and (b) described above. For example, other steps may be included between steps (a) and (b). For example, it may also include a drying step, a smoothing step, a lamination step, etc.

[0056] In the manufacturing method of the resin composition layer of the present invention, a sheet formed on a carrier film is pressed to become the resin composition layer of the present invention. Depending on the application and manufacturing process, the resin composition layer of the present invention can be used directly for various applications while still formed on a carrier film, or it can be separated from the carrier film and used as a monomer for various applications. The resin composition layer of the present invention can be covered by a protective sheet or the like.

[0057] One preferred approach is a composite molded body having a metal portion on one or both sides of the resin composition layer of the present invention.

[0058] The resin composition of the present invention may contain other components in addition to aggregated inorganic fillers and thermosetting resins.

[0059] [Resin Composition]

[0060] The resin composition of the present invention will be described.

[0061] <Agglomerated Inorganic Packing>

[0062] The resin composition of the present invention contains aggregated inorganic filler. To improve the thermal conductivity of the manufactured resin composition layer and control the coefficient of linear expansion, the resin composition of the present invention preferably contains a large amount of aggregated inorganic filler. By containing aggregated inorganic filler, in steps (a) and (b) described later, the aggregated inorganic filler deforms due to mutual contact, forming more heat conduction paths through surface contact, thereby tending to achieve high thermal conductivity. The aggregation morphology of the aggregated inorganic filler can be confirmed using scanning electron microscopy (SEM).

[0063] In addition to agglomerated inorganic fillers, the resin composition of the present invention may also contain non-agglomerated inorganic fillers and organic fillers.

[0064] As agglomerated inorganic filler, electrically insulating fillers can be used, such as fillers composed of at least one type of particles selected from metal carbides, metal oxides and metal nitrides.

[0065] Examples of metal carbides include silicon carbide, titanium carbide, and tungsten carbide.

[0066] Examples of metal oxides include: magnesium oxide, aluminum oxide, silicon oxide, calcium oxide, zinc oxide, yttrium oxide, zirconium oxide, cerium oxide, ytterbium oxide, and sialon (a ceramic composed of silicon, aluminum, oxygen, and nitrogen).

[0067] Examples of metal nitrides include boron nitride, aluminum nitride, and silicon nitride.

[0068] In power semiconductor applications, insulation is required; therefore, aggregated inorganic fillers with a volume resistivity of 1×10⁻⁶ are preferred. 12 Ω·cm and above, especially 1×10 13 It is composed of inorganic compounds with excellent insulating properties of Ω·cm or higher. Among them, oxides and nitrides are preferred because the formed resin composition layer has sufficient electrical insulation.

[0069] More specifically, examples of such aggregated inorganic fillers include: alumina (Al₂O₃, volume resistivity 1×10⁻⁶). 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), silicon dioxide (SiO2, volume resistivity >1×10 14 (Ω·cm), etc. As agglomerated inorganic filler, alumina, aluminum nitride, boron nitride, and silicon dioxide are preferred, with alumina and boron nitride being particularly preferred.

[0070] Aggregated inorganic fillers can be surface-treated using surface treatment agents. Well-known surface treatment agents can be used.

[0071] Agglomerated inorganic fillers can be used alone or in any combination and ratio of two or more.

[0072] There are no particular limitations on the aggregation method and degree of the aggregated inorganic filler used in this invention, but aggregated boron nitride filler as described below is preferred as the aggregated inorganic filler. Aggregated boron nitride filler as described below, as well as fillers of different shapes and types, can also be used in combination.

[0073] <Agglomerated boron nitride filler>

[0074] Although boron nitride has high thermal conductivity, its scaly structure exhibits high thermal conductivity in the planar direction of the scales, but low thermal conductivity in the direction perpendicular to the plane. For better processing, it is preferable to use aggregated particles that agglomerate into spherical shapes from the aggregated scales. In aggregated boron nitride packings formed by stacking particles like cabbage leaves, the particles are preferably arranged in a planar direction to improve radial thermal conductivity. More preferably, the aggregated boron nitride packing has a frame structure.

[0075] "Card-house structure" refers to a structure, for example, described in Ceramics 43 No. 2 (issued by the Japan Ceramic Society in 2008), where plate-like particles are complexly stacked without orientation. More specifically, condensed boron nitride filler with a card-house structure refers to an aggregate of primary boron nitride particles, where the planar portions and end portions of the primary particles contact each other to form, for example, a T-shaped association.

[0076] As the condensed boron nitride filler used in this invention, condensed boron nitride filler having the above-described shelf structure is particularly preferred. By using condensed boron nitride filler with a shelf structure, the thermal conductivity can be further improved.

[0077] The Mohs hardness of condensed boron nitride filler is not particularly limited, but is preferably 5 or less. The lower limit of the Mohs hardness of condensed boron nitride filler is not particularly limited, but may be, for example, 1 or more.

[0078] By setting the new Mohs hardness to below 5, the dispersed particles in the resin composition can easily become surface contacts, forming thermal conduction paths between particles, and the thermal conductivity of the resulting resin composition layer tends to increase.

[0079] The volume average particle size of the condensed boron nitride filler is not particularly limited, but is preferably 10 μm or more, more preferably 15 μm or more. The volume average particle size of the condensed boron nitride filler is preferably 100 μm or less, more preferably 90 μm or less. By making the volume average particle size 10 μm or more, the number of particles in the resin composition and resin composition layer of the present invention is relatively reduced, thus reducing the interparticle interface, decreasing thermal resistance, and resulting in a resin composition layer with high thermal conductivity. By making the volume average particle size below the above-mentioned upper limit, the surface smoothness of the formed resin composition layer tends to be excellent.

[0080] The volume average particle size of condensed boron nitride filler refers to the particle size when the cumulative volume is 50% of the total volume of the powder being measured and a cumulative curve is plotted.

[0081] Examples of determination methods include: wet determination using a laser diffraction / scattering particle size distribution measuring device for samples formed by dispersing agglomerated particles in a pure water medium containing sodium hexametaphosphate as a dispersing stabilizer; and dry determination using the "Morphologi" device manufactured by Malvern.

[0082] The same applies to the volume average particle size of other aggregated inorganic fillers and non-aggregated inorganic fillers.

[0083] <Breaking strength of aggregated inorganic fillers>

[0084] The breaking strength of the agglomerated inorganic filler is not particularly limited, but it is preferably 300 MPa or less, more preferably 100 MPa or less, even 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. By making the breaking strength below the above-mentioned upper limit, the agglomerated structure of the agglomerated inorganic filler deforms during the pressing process, and the agglomerated inorganic filler can easily make surface contact with each other.

[0085] There is no particular limitation on the lower limit of the breaking strength of the aggregated inorganic filler, but from the perspective of ease of operation, it is preferably 2.5 MPa or more, more preferably 3 MPa or more, further preferably 3.5 MPa or more, and particularly preferably 4 MPa or more.

[0086] <Elastic modulus of aggregated inorganic fillers>

[0087] The elastic modulus of the agglomerated inorganic filler is not particularly limited, but it is preferably 10 MPa or more, more preferably 20 MPa or more, further 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 above the above lower limit, the agglomerated inorganic filler undergoes plastic deformation in the compression direction, which can tend to suppress the collapse of the agglomerated structure.

[0088] There is no particular limit to the upper limit of the elastic modulus of the aggregated inorganic filler, but from the perspective of easily obtaining sufficient deformation, it is preferably 5 GPa or less, more preferably 2 GPa or less, further preferably 1.5 GPa or less, even more preferably 1 GPa or less, particularly preferably 500 MPa or less, especially preferably 300 MPa or less, and most preferably 250 MPa or less.

[0089] When the aggregated inorganic filler is within the aforementioned range of elastic modulus, it tends to maintain a spherical shape during pressing. When the breaking strength of the aggregated inorganic filler is within the aforementioned range, the portions of the aggregated inorganic fillers in contact with each other deform, and surface contact becomes easier. As a result, it is possible to maintain the high thermal conductivity inside the aggregated inorganic filler while reducing the contact thermal resistance at the interfaces between the aggregated inorganic fillers and between the metal portion (described later) and the resin composition layer of the present invention, thereby improving the overall thermal conductivity.

[0090] The breaking strength and elastic modulus of the aggregated inorganic filler were measured after the resin composition layer was removed and the aggregated inorganic filler was taken out, in order to prevent the aggregated inorganic filler from deteriorating, when the aggregated inorganic filler was located in the resin composition layer.

[0091] <Content of aggregated inorganic fillers>

[0092] The content of 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, further preferably 45% by mass or more, and particularly preferably 50% by mass or more, out of 100% by mass of the resin composition layer. Furthermore, it is preferably 99% by mass or less, more preferably 90% by mass or less, further preferably 85% by mass or less, and particularly preferably 80% by mass or less.

[0093] The combination of upper and lower limits of the content of 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.

[0094] Therefore, the content of aggregated inorganic filler in the resin composition of the present invention is preferably 30% by mass or more in 100% by mass of the solid components in the resin composition, more preferably 40% by mass or more, even 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, even more preferably 85% by mass or less, and particularly preferably 80% by mass or less.

[0095] The combination of upper and lower limits of the content of aggregated inorganic filler in the resin composition of the present invention is not particularly limited, but in the 100% by mass of solid content in the resin composition, 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.

[0096] Here, the solid component in the resin composition refers to the sum of all components in the resin composition except for the solvent.

[0097] By setting the content of aggregated inorganic filler to the lower limit or above mentioned above, it is easier to fully obtain the improved thermal conductivity and controlled linear expansion coefficient effects brought about by the presence of aggregated inorganic filler. By setting the content of aggregated inorganic filler to the upper limit or below mentioned above, it is possible to reduce the porosity of the resin composition layer, and improve the insulation and interfacial adhesion in the composite molded body.

[0098] <Other non-agglomerated inorganic fillers>

[0099] In this invention, in addition to agglomerated inorganic fillers, other non-agglomerated inorganic fillers can also be used.

[0100] There are no restrictions on the shape of non-agglomerated inorganic fillers; examples include spherical, whisker-like, fibrous, and plate-like shapes.

[0101] Other non-agglomerated inorganic fillers can be flake-shaped boron nitride primary particles, etc., and are not limited to their shape.

[0102] Other non-agglomerated inorganic fillers (non-agglomerated inorganic fillers) can be used alone or in any combination and ratio of two or more.

[0103] <Spherical packing>

[0104] As a non-agglomerated inorganic packing material other than agglomerated inorganic packing material, spherical packing material is preferred.

[0105] The thermal conductivity of the spherical packing is not particularly limited, but it is 1 W / m·K or more, preferably 10 W / m·K or more, more preferably 15 W / m·K or more, and even more preferably 20 W / m·K or more, for example 20 to 30 W / m·K.

[0106] The new Mohs hardness of the spherical filler is 3.1 or higher, preferably 5 to 10.

[0107] By combining such spherical fillers with the aforementioned aggregated inorganic fillers, the adhesion and heat dissipation of the resulting resin composition layer relative to the metal can be improved.

[0108] Here, "spherical" refers to anything generally considered to be spherical. For example, an average roundness of 0.4 or higher can be considered spherical, as can an average roundness of 0.6 or higher. Typically, the upper limit for average roundness is 1.

[0109] Circularity can be determined by image processing of its projected image. Circularity can be measured using, for example, Sysmex's FPIA series.

[0110] The spherical filler is preferably selected from at least one of alumina, synthetic magnesite, crystalline silica, aluminum nitride, silicon nitride, silicon carbide, zinc oxide, and magnesium oxide. Using these preferred spherical fillers can further improve the heat dissipation of the resulting resin composition layer.

[0111] The volume average particle size of the spherical filler is preferably in the range of 0.5 μm or more and 40 μm or less. It is believed that by making the volume average particle size 0.5 μm or more, the resin and filler can flow easily during thermoforming, thereby improving the interfacial adhesion in the composite molded article described later. By making the volume average particle size 40 μm or less, the insulating breakdown characteristics of the resin composition layer are easily maintained.

[0112] <Content of other non-agglomerated inorganic fillers>

[0113] When other non-aggregated inorganic fillers are used together with aggregated inorganic fillers, the content ratio of aggregated inorganic fillers to other non-aggregated inorganic fillers in the resin composition of the present invention and 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.

[0114] For the same reason as the content of condensed boron nitride filler in the resin composition layer of the present invention, the total content of condensed inorganic filler and other non-condensed 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, further preferably 45% by mass or more, particularly preferably 50% by mass or more, and on the other hand, preferably 99% by mass or less, more preferably 90% by mass or less, further preferably 85% by mass or less, and particularly preferably 80% by mass or less.

[0115] Therefore, the total content of aggregated inorganic filler and other non-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, further preferably 45% by mass or more, particularly preferably 50% by mass or more, and on the other hand, preferably 99% by mass or less, more preferably 90% by mass or less, further preferably 85% by mass or less, and particularly preferably 80% by mass or less.

[0116] By ensuring that the total content of agglomerated inorganic filler and other non-agglomerated inorganic filler is above the aforementioned lower limit, it is easier to fully obtain the improved thermal conductivity and controlled linear expansion coefficient effects brought about by the presence of inorganic filler. By ensuring that the total content of agglomerated inorganic filler and other non-agglomerated inorganic filler is below the aforementioned upper limit, porosity can be reduced, and insulation and interfacial adhesion in the composite molded body tend to improve.

[0117] <Other Organic Fillers>

[0118] In addition to aggregated inorganic fillers, the resin composition and resin composition layer of the present invention may also contain organic fillers. In the present invention, organic fillers refer to components that are free of epoxy groups, do not meet the definition of thermosetting catalysts, and are solid at room temperature, composed of organic components. Examples of organic fillers include: natural products such as wood flour, modified or unmodified cellulose, starch, various organic pigments, thermoplastic resins, thermosetting resins, etc. Specific examples include acrylic resin particles, nylon resin particles, polyester resin particles, polystyrene resin particles, and silicone resin particles.

[0119] By including organic fillers, resin compositions can sometimes be given moderate elongation, which can mitigate stress and suppress cracking during temperature cycling tests.

[0120] The upper limit of the average particle size of the organic filler is preferably 100 μm or less, more preferably 50 μm or less. By keeping the average particle size below the above-mentioned upper limit, it is possible to suppress the decrease in thermal conductivity and produce resin composition layers of various thicknesses. The average particle size of the organic filler is also determined based on the volume average particle size obtained from the particle size distribution measurement results measured using a laser diffraction particle size distribution measuring device.

[0121] Organic fillers can be used alone or in any combination and ratio of two or more.

[0122] <Thermosetting Resins>

[0123] As for the thermosetting resin contained in the resin composition of the present invention, it is not particularly limited as long as it can be cured in the presence of a curing agent or curing catalyst to obtain a cured product.

[0124] Specific examples of thermosetting resins include: epoxy resins, phenolic resins, polycarbonate resins, unsaturated polyester resins, cyanate ester resins, maleimide resins, polyurethane resins, melamine resins, and urea-formaldehyde resins. Among these, epoxy resins are preferred from the perspectives of viscosity, heat resistance, hygroscopicity, and processability. Examples of epoxy resins include: epoxy-containing silicone compounds, aliphatic epoxy resins, bisphenol A or F type epoxy resins, phenolic varnish-type epoxy resins, alicyclic epoxy resins, glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, multifunctional epoxy resins, and polymeric epoxy resins.

[0125] <Epoxy Resin>

[0126] Epoxy resin is a general term for compounds that have one or more epoxy rings (epoxy groups) in their molecules.

[0127] The epoxy ring (epoxy group) contained in the epoxy resin can be either alicyclic epoxy group or glycidyl group, but glycidyl group is preferred from the perspective of reaction rate or heat resistance.

[0128] The epoxy resin used in this invention can be a compound containing an aromatic epoxy ring (epoxy group). Specific examples include: bisphenol-type epoxy resins made by glycidizing bisphenols such as bisphenol A, bisphenol F, bisphenol AD, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol F, tetramethylbisphenol AD, tetramethylbisphenol S, and tetrafluorobisphenol A; biphenyl-type epoxy resins; epoxy resins made by glycidizing divalent phenols such as dihydroxynaphthalene and 9,9-bis(4-hydroxyphenyl)fluorene; epoxy resins made by glycidizing triphenols such as 1,1,1-tris(4-hydroxyphenyl)methane; epoxy resins made by glycidizing tetraphenols such as 1,1,2,2-tetra(4-hydroxyphenyl)ethane; and phenolic varnish-type epoxy resins made by glycidizing phenolic varnishes such as phenolic varnish, cresol varnish, bisphenol A varnish, and brominated bisphenol A varnish.

[0129] The epoxy resin contained in the resin composition of the present invention is not particularly limited, but for example, it is preferable to contain one or more of the following: 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 epoxy resins; and aromatic compounds having multiple hydroxyl groups such as dihydroxynaphthalene and 9,9-bis(4-hydroxyphenyl)fluorene. Epoxy resins obtained by glycidylation; epoxy resins obtained by glycidylation of triphenols such as 1,1,1-tris(4-hydroxyphenyl)methane; epoxy resins obtained by glycidylation of tetraphenols such as 1,1,2,2-tetra(4-hydroxyphenyl)ethane; phenolic varnish-type epoxy resins obtained by glycidylation of phenolic varnishes such as phenolic varnish, cresol varnish, bisphenol A varnish, and brominated bisphenol A varnish; and epoxy resins containing organosilicon.

[0130] The epoxy resin used in this invention can be a single type or a combination of multiple epoxy resins.

[0131] The molecular weight of the epoxy resin used in this invention is not particularly limited.

[0132] From the perspectives of film-forming properties, low moisture absorption, and flexibility, the epoxy resin used in this invention preferably contains a high molecular weight epoxy resin. Specifically, the high molecular weight epoxy resin is preferably an epoxy resin with a weight average molecular weight of 10,000 or more, more preferably an epoxy resin with a weight average molecular weight of 15,000 or more. The high molecular weight epoxy resin is preferably an epoxy resin with a weight average molecular weight of 200,000 or less, more preferably 180,000 or less.

[0133] High molecular weight epoxy resins are more preferably hydrophobic, and specifically, the higher 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.

[0134] From the perspective of improving the storage modulus of the resin composition layer of the present invention, the epoxy resin used in the present invention preferably contains an epoxy resin with 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 it is generally 100 or more.

[0135] The epoxy resin used in this invention with a weight average molecular weight of 600 or less is preferably an epoxy resin having two or more epoxy groups per molecule. Furthermore, it is more preferred to use a multifunctional epoxy resin with a weight average molecular weight of 600 or less containing three or more epoxy groups per molecule, as described later. Epoxy resins with a weight average molecular weight of 600 or less can also be used in combination with multifunctional epoxy resins having three or more epoxy groups per molecule and epoxy resins having two epoxy groups per molecule.

[0136] From the perspective of film-forming properties, coating properties and heat resistance after curing, the thermosetting resin of the resin composition of the present invention preferably includes epoxy resin with a weight average molecular weight of 10,000 or more and epoxy resin with a weight average molecular weight of 600 or less.

[0137] The weight-average molecular weight of epoxy resin is a value converted from polystyrene, determined by gel permeation chromatography.

[0138] The epoxy equivalent of epoxy resin is defined as "the weight of epoxy resin containing 1 equivalent of epoxy groups", and can be determined according to JIS K7236.

[0139] (Multifunctional epoxy resins with a molecular weight below 600)

[0140] The resin composition of the present invention more preferably contains a multifunctional epoxy resin with a molecular weight of less than 600 and having more than 3 epoxy groups per molecule as a thermosetting resin.

[0141] From the perspective of improving the energy storage modulus of the resin composition layer of the present invention, especially the high-temperature energy storage modulus which is important when power semiconductors and other devices generate a lot of heat, epoxy resins having three or more epoxy rings (epoxy groups) within the molecule are preferred, and epoxy resins having four or more epoxy rings (epoxy groups) within the molecule are more preferred. By having multiple epoxy rings (epoxy groups), especially glycidyl groups, within the molecule, the crosslinking density of the formed resin composition layer is increased, and the strength is improved. Therefore, when internal stress is generated in the resin composition layer during the moisture absorption and reflow test, the resin composition layer will not deform or break and will maintain its shape, thereby suppressing the formation of pores and other voids in the resin composition layer.

[0142] From the perspective of improving the storage modulus of the resin composition layer, the molecular weight of the multifunctional epoxy resin is preferably 600 or less, and more preferably 550 or less. There is no particular limitation on the lower limit of the molecular weight of the multifunctional epoxy resin, but it is generally 100 or more.

[0143] By adding multifunctional epoxy resins, highly polar epoxy rings (epoxy groups) can be introduced at high density. Therefore, the effects of physical interactions such as van der Waals forces and hydrogen bonds can be increased, improving the adhesion between the metal parts and the resin composition layers in the composite molded article described later.

[0144] By adding a multifunctional epoxy resin, the storage modulus of the thermosetting resin composition layer can be increased. Consequently, the cured resin composition exhibits a strong anchoring effect when it penetrates the uneven areas of the metal part of the substrate, thus improving the adhesion between the metal part and the resin composition layer.

[0145] As a multifunctional epoxy resin, epoxy resins having three or more epoxy groups are particularly preferred. Examples of multifunctional epoxy resins that can be used include jER630 manufactured by Mitsubishi Chemical Corporation; ELM-434 series and ELM-100 series manufactured by Sumitomo Chemical Corporation; EX321L, EX-411, and EX-512 manufactured by Nagase ChemteX Corporation; and BATG and PETG manufactured by Showa Denko Corporation.

[0146] Multifunctional epoxy resins can be used in combination with one type or two or more types.

[0147] <Content of thermosetting resin>

[0148] In the resin composition layer of the present invention, apart from inorganic fillers, the main component of the resin is preferably a thermosetting resin, and particularly preferably contains epoxy resin. Here, "main component" refers to the most abundant component.

[0149] The resin composition layer of the present invention preferably contains 5 to 90% by mass of thermosetting resin in 100% by mass of the resin composition layer, particularly preferably 10 to 60% by mass. Therefore, the proportion of thermosetting resin in 100% by mass of the solid components of the resin composition of the present invention is preferably 5 to 90% by mass, particularly preferably 10 to 60% by mass. When the content of thermosetting resin is above the above-mentioned lower limit, the moldability becomes good, and when it is below the above-mentioned upper limit, the content of other components can be ensured, and the thermal conductivity can be improved.

[0150] The content of thermosetting resin in the resin composition layer of the present invention, excluding the inorganic filler, is not particularly limited, but is preferably 20% by mass or more, more preferably 25% by mass or more, further preferably 30% by mass or more, and particularly preferably 45% by mass or more. Therefore, the content of thermosetting resin in the solid components of the resin composition of the present invention, excluding the inorganic filler, is preferably 20% by mass or more, more preferably 25% by mass or more, further preferably 30% by mass or more, and particularly preferably 45% by mass or more. The upper limit of the content of thermosetting resin in the resin components, excluding the inorganic filler, is 100% by mass, and the components other than the inorganic filler can be entirely thermosetting resin.

[0151] By setting the proportion of thermosetting resin within the above range, it achieves low hygroscopicity, high elastic modulus, and high toughness, while also making the reaction easy to control and tending to exhibit high reflow resistance, high reliability in cyclic testing, and high thermal conductivity.

[0152] In the resin composition layer of the present invention and the resin component of the resin composition of the present invention, the content of the aforementioned suitable epoxy resin with a weight average molecular weight of 10,000 or more of high molecular weight epoxy resin 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.

[0153] In the resin composition layer of the present invention and the resin component of the resin composition of the present invention, the content of epoxy resin with a weight average molecular weight of 600 or less 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.

[0154] The preferred mass ratio of high molecular weight epoxy resin with a weight average molecular weight of 10,000 or more to epoxy resin with a weight average molecular weight of 600 or less is 1:18 to 18:1.

[0155] By setting the content of high molecular weight epoxy resin to the lower limit or above, the film-forming properties of the resin composition of the present invention tend to be improved; by setting it to the upper limit or below, the strength of the resin composition layer of the present invention can be made excellent.

[0156] <Other Ingredients>

[0157] The resin composition and resin composition layer of the present invention may also contain other components besides aggregated inorganic fillers and thermosetting resins. Examples of other components, in addition to the aforementioned non-aggregated inorganic fillers and organic fillers, include, as shown below, curing catalysts, curing agents, surface treatment agents such as silane coupling agents, reducing agents such as insulating carbon components, viscosity modifiers, dispersants, thixotropic agents, flame retardants, colorants, organic solvents, and thermoplastic resins.

[0158] <Catalyst Solidification>

[0159] The resin composition of the present invention may also contain a curing catalyst (thermosetting catalyst) to adjust the curing speed, physical properties of the cured product, etc.

[0160] The curing catalyst is not particularly limited, but can be appropriately selected based on the type of thermosetting resin or other components used. Specific examples of curing catalysts include: chain or cyclic tertiary amines, organophosphorus compounds, quaternary phosphonium salts, or diazabicyclic olefins of organic acid salts, etc. Organometallic compounds, quaternary ammonium salts, or metal halides can be used as curing catalysts. Examples of organometallic compounds include: zinc octanoate, tin octanoate or aluminum acetylacetonate complexes, gallium acetylacetonate complexes, imidazoles, etc. Imidazoles are particularly preferred from the perspective of heat resistance and stability.

[0161] These can be used individually or in combination with two or more.

[0162] The curing catalyst preferably contains 0.1 to 10% by mass, particularly 0.1 to 5% by mass, of the resin composition of the present invention, excluding the solvent and inorganic filler. When the content of the curing catalyst is above the lower limit mentioned above, the curing reaction can be sufficiently promoted and curing can be carried out well. When the content of the curing catalyst is below the upper limit mentioned above, the curing rate is not too fast, and therefore the storage stability of the resin composition of the present invention can be good.

[0163] When the curing catalyst is a solid, its average particle size is not particularly limited, but the average particle size of at least one curing catalyst is preferably 15 μm or less, more preferably 10 μm or less. By setting the average particle size to the upper limit mentioned above, the solubility of the curing catalyst in the resin component is improved, the reaction rate tends to increase, and the elastic modulus of the formed resin composition layer can be further improved, tending to increase the glass transition temperature. Moreover, the dispersibility of the curing catalyst is improved, and the storage stability of the resin composition of the present invention tends to be improved. The lower limit value of the average particle size of the curing catalyst is not particularly limited.

[0164] <Curing agent>

[0165] The resin composition of the present invention may also contain a curing agent. The curing agent is not particularly limited, but may include phenolic resins, aliphatic amines, aromatic amines, modified amines, polyamide resins, imidazoles, polythiols, polysulfides, acid anhydrides, carboxylic acid compounds, dicyandiamide, etc.

[0166] Among these, phenolic resins, acid anhydrides having an aromatic or alicyclic backbone, or hydrogenated or modified acid anhydrides are preferred. By using these preferred curing agents, it is possible to obtain a resin composition layer with an excellent balance of heat resistance, moisture resistance, and electrophysical properties. One curing agent may be used alone, or two or more may be used in combination.

[0167] The phenolic resin used in the curing agent is not particularly limited. Specific examples of phenolic resins include: phenolic varnish, o-cresol varnish, p-cresol varnish, tert-butylphenol varnish, dicyclopentadiene cresol, poly(p-vinylphenol), bisphenol A type phenolic varnish, xylene-modified phenolic varnish, decahydronaphthalene-modified phenolic varnish, poly(di-o-hydroxyphenyl)methane, poly(di-m-hydroxyphenyl)methane, or poly(di-p-hydroxyphenyl)methane, etc. Among these, to further improve the flexibility and flame retardancy of the resin composition, and to improve the mechanical and physical properties and heat resistance of the resin composition layer, phenolic varnish-type phenolic resins with a rigid main chain backbone and phenolic resins with a triazine backbone are preferred. To improve the flexibility of the resin composition of the present invention and the toughness of the resin composition layer of the present invention, allyl phenolic resins are preferred.

[0168] Commercially available phenolic resins include: MEH-8005, MEH-8000H, and NEH-8015 (all manufactured by Meiwa Kasei Corporation); YLH903 (manufactured by Mitsubishi Chemical Corporation); LA-7052, LA-7054, LA-7751, LA-1356, and LA-3018-50P (all manufactured by Dai Nippon Ink & Chemical Co., Ltd.); and PSM6200, PS6313, and PS6492 (manufactured by Gunei Chemical Co., Ltd.).

[0169] There are no particular limitations on the acid anhydride with an aromatic skeleton, the hydride of the acid anhydride, or the modifier of the acid anhydride used in the curing agent. Specific examples include: SMA resin EF30 and SMA resin EF60 (both manufactured by Sartomer Japan); ODPA-M and PEPA (both manufactured by Manac); RIKACIDMTA-10, RIKACID TMTA, RIKACID TMEG-200, RIKACID TMEG-500, RIKACID TMEG-S, RIKACIDTH, RIKACID MH-700, RIKACID MT-500, RIKACID DSDA, and RIKACID TDA-100 (all manufactured by Shin Nippon Rikka Co., Ltd.); EPICLONB 4400 and EPICLONB 570 (both manufactured by Dai Nippon Ink Chemical Co., Ltd.), etc.

[0170] Acid anhydrides having an alicyclic skeleton, hydrides of such acid anhydrides, or modified forms of such acid anhydrides are preferably acid anhydrides having a polycyclic alicyclic skeleton, hydrides of such acid anhydrides, or modified forms of such acid anhydrides, or acid anhydrides having an alicyclic skeleton obtained by an addition reaction of a terpene compound with maleic anhydride. Specific examples include RIKACID HNA and RIKACID HNA-100 (both manufactured by Shin Nippon Rikka Co., Ltd.), and EPICURE YH306 and EPICURE YH309 (both manufactured by Mitsubishi Chemical Co., Ltd.).

[0171] The curing agent preferably comprises 0 to 70% by mass, particularly 0 to 55% by mass, of 100% by mass of the resin composition of the present invention, excluding the solvent and inorganic filler. Sufficient curing performance can be obtained when the content of the curing agent is above the lower limit mentioned above. If the content of the curing agent is below the upper limit mentioned above, the reaction can proceed effectively, increasing the crosslinking density, strength, and film-forming properties.

[0172] When the thermosetting resin is an epoxy resin, the content of reactive groups in the curing agent is not particularly limited, but relative to the amount of epoxy groups in the thermosetting resin, it can be 0 equivalents, preferably 0.05 equivalents or more, more preferably 0.1 equivalents or more, and even more preferably 0.15 equivalents or more. The content of reactive groups in the curing agent relative to the amount of epoxy groups in the thermosetting resin is preferably 2 equivalents or less, more preferably 1.2 equivalents or less.

[0173] By setting the content of reactive groups in the curing agent to the lower limit or above the aforementioned value relative to the amount of epoxy groups in the thermosetting resin, it tends to suppress the decrease in curing speed, reduce the likelihood of epoxy group residue, and achieve improved strength and reduced moisture absorption in the resulting resin composition layer. By setting the content of reactive groups in the curing agent to the upper limit or below the aforementioned value relative to the epoxy groups, the elastic modulus of the resulting resin composition layer tends to increase.

[0174] <Dispersant>

[0175] The resin composition of the present invention may also contain a dispersant. By containing a dispersant, a uniform resin composition layer can be formed, and sometimes the thermal conductivity and insulation breakdown properties of the resulting resin composition layer can be improved.

[0176] The dispersant preferably has a functional group containing hydrogen atoms that are capable of hydrogen bonding. By having a functional group containing hydrogen atoms that are capable of hydrogen bonding in the dispersant, the thermal conductivity and insulation breakdown properties of the formed resin composition layer can be further improved. Examples of such functional groups containing hydrogen atoms that are capable of hydrogen bonding include carboxyl groups (pKa = 4), phosphate groups (pKa = 7), or phenolic groups (pKa = 10).

[0177] The pKa of the functional group containing hydrogen atoms with hydrogen bonding is preferably in the range of 2 to 10, and more preferably in the range of 3 to 9. By making the pKa 2 or higher, the acidity of the dispersant is within an appropriate range, and it is sometimes easy to inhibit the reaction of the epoxy resin in the thermosetting resin component. Therefore, the storage stability tends to improve when storing the molded article in its uncured state. By making the pKa 10 or lower, it tends to function sufficiently as a dispersant, and the thermal conductivity and dielectric breakdown properties of the formed resin composition layer are sufficiently improved.

[0178] The functional group containing hydrogen atoms with hydrogen bonding is preferably a carboxyl group or a phosphate group. In this case, the thermal conductivity and insulation breakdown properties of the formed resin composition layer can be further improved.

[0179] Specific examples of dispersants include: polyester-based carboxylic acids, polyether-based carboxylic acids, polyacrylic acid-based carboxylic acids, aliphatic carboxylic acids, polysiloxane-based carboxylic acids, polyester-based phosphoric acid, polyether-based phosphoric acid, polyacrylic acid-based phosphoric acid, aliphatic phosphoric acid, polysiloxane-based phosphoric acid, polyester-based phenols, polyether-based phenols, polyacrylic acid-based phenols, and polysiloxane-based phenols. A single dispersant can be used, or two or more can be used in combination.

[0180] <Thermoplastic Resins>

[0181] The resin composition of the present invention may also contain a thermoplastic resin. By containing a thermoplastic resin, the formed resin composition layer may sometimes be given appropriate elongation, thus mitigating stress and suppressing crack formation during temperature cycling tests.

[0182] As a thermoplastic resin, any thermoplastic resin known in general can also be used. Specific examples of thermoplastic resins include: polyethylene, polypropylene, polystyrene, polyvinyl chloride, (meth)acrylic acid resin, vinyl-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, and other vinyl polymers; polyesters such as polylactic acid resin, polyethylene terephthalate, and polybutylene terephthalate; polyamides such as nylon and polyamide amine; polyvinyl alcohol acetal resins such as polyvinyl alcohol acetal, polyvinyl alcohol benzaldehyde, and polyvinyl alcohol butyral; ionomer resins, polyphenylene ether, polyphenylene sulfide, polycarbonate, polyetheretherketone, polyacetal, ABS resin, LCP (liquid crystal polymer), fluoropolymers, polyurethane resins, silicone resins, various elastomers, and modified versions of these resins.

[0183] The thermoplastic resin can be a uniform resin in the resin phase of the formed resin composition layer, or it can be a resin whose shape can be identified through phase separation. In the case of a phase-separated resin, the thermoplastic resin in the resin composition layer can be either granular or fibrous. The thermoplastic resin can be included as the aforementioned organic filler.

[0184] <Organic solvents>

[0185] The resin composition of the present invention may contain organic solvents to improve coatability in the coating process described later.

[0186] Examples of organic solvents that may be contained in the resin composition of the present invention include: methyl ethyl ketone, cyclohexanone, propylene glycol monomethyl ether acetate, butyl acetate, isobutyl acetate, propylene glycol monomethyl ether, etc.

[0187] Organic solvents can be used alone or in combination of two or more.

[0188] When the resin composition of the present invention contains an organic solvent, from the perspective of coatability in the coating process, it is preferable that the content is such that the concentration of the solid components (the sum of components other than the solvent) 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.

[0189] <Method for manufacturing resin composition>

[0190] The resin composition of the present invention can be obtained by uniformly mixing aggregated inorganic fillers, thermosetting resins, and other components added as needed by stirring or kneading. Conventional mixing equipment such as mixers, kneaders, single-screw or twin-screw mixers can be used for mixing. Heating may also be performed during mixing as needed.

[0191] The order in which the various components are mixed is arbitrary as long as there are no particular problems such as reactions or precipitation. However, examples include: mixing and dissolving thermosetting resin components in an organic solvent (e.g., methyl ethyl ketone) to prepare a resin solution, and then adding and mixing a mixture containing aggregated inorganic fillers and other components to the resulting resin solution.

[0192] [Method for manufacturing resin composition layer]

[0193] The method for manufacturing the resin composition layer of the present invention comprises step (a) and step (b).

[0194] The reasons for achieving improved operability, voltage resistance, adhesion, and heat resistance in the manufacturing method of the present invention are as follows.

[0195] In step (a), a pressing process is performed under specific pressing pressure and pressing temperature. This pressing temperature is lower than the curing temperature of the thermosetting resin contained in the resin composition of the present invention, allowing pressing to be performed while suppressing the reaction rate of the thermosetting resin. As a result, the thermosetting resin more easily penetrates the pores originating from the aggregated inorganic filler, reducing porosity. By impregnating the pores originating from the aggregated inorganic filler with resin, the brittleness of the resulting resin composition layer is reduced, improving workability.

[0196] Furthermore, in step (b), the sheet material that has undergone step (a) is pressed under specific pressing pressure and temperature. By performing the specific pressing treatment of step (b) while suppressing the reaction rate of the thermosetting resin after step (a), adhesion can be improved, and voltage resistance and heat resistance can be improved by allowing the reaction after step (b) to proceed fully.

[0197] Furthermore, by setting the pressing temperature in step (b) to be higher than that in step (a), the fluidity of the thermosetting resin before curing is increased, which further reduces porosity. Through these steps (a) and (b), a resin composition layer with improved voltage resistance, adhesion, and heat resistance can be obtained.

[0198] <(a) Process>

[0199] (a) The process is to press a sheet on which the resin composition of the present invention is formed on a carrier film under conditions of a pressing temperature of 0°C or higher and 110°C or lower, and a pressing pressure of 40 MPa or higher and 1000 MPa or lower.

[0200] In step (a), a sheet is formed on a carrier film using the resin composition of the present invention, and the sheet with the carrier film is pressed under specific conditions. By pressing the sheet with the carrier film under specific conditions in step (a), the operability of the sheet before step (b) can be improved.

[0201] The method for forming the sheet using the resin composition of the present invention is not particularly limited, but a method by means of a coating process can be cited. In this case, the resin composition of the present invention may contain an organic solvent to improve coatability.

[0202] There are no particular limitations on the coating method for the resin composition of the present invention, but methods such as dip coating, spin coating, spray coating, doctor blade coating, and other arbitrary methods can be used. Coating apparatuses such as spin coaters, slot coaters, die coaters, and doctor blade coaters can be used. These apparatuses allow for the uniform formation of a sheet (coating) of a specified thickness on a carrier film.

[0203] The carrier film used is not particularly limited, but it is desirable to be a carrier film that is insoluble in the resin composition of the present invention and exhibits minimal deformation under the pressing temperature and pressing pressure of step (a). Examples include: olefin-based films, polyester films such as PET (polyethylene terephthalate), polyimide films, copper materials, etc.

[0204] When forming sheets using the resin composition of the present invention containing organic solvents, it is preferable to remove the solvent by a process such as drying before pressing in step (a). The solid content concentration of the sheet before pressing in step (a) is preferably 95% by mass or more, more preferably 98% by mass or more.

[0205] The drying process is not particularly limited, but it is usually carried out at a temperature of 10 to 150°C, preferably 25 to 120°C, and more preferably 30 to 110°C.

[0206] By keeping the drying temperature below the upper limit mentioned above, the curing of the thermosetting resin in the sheet can be suppressed, allowing the resin to flow more easily in subsequent pressing processes and removing pores. When the drying temperature is above the lower limit mentioned above, organic solvents can be effectively removed.

[0207] When drying at temperatures below 80°C, the drying time is typically 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 temperatures above 80°C, the drying time is preferably 1 minute or more, preferably 30 minutes or less, more preferably 20 minutes or less, further preferably 15 minutes or less, and particularly preferably 10 minutes or less. By keeping the drying time above or below the aforementioned lower limit, it is easier to remove organic solvents sufficiently, and the formation of residual solvents as pores within the sheet can be suppressed. By keeping the drying time below or below the aforementioned upper limit, productivity tends to increase, and manufacturing costs can be suppressed.

[0208] The pressing temperature in step (a) is above 0°C and below 110°C, preferably above 3°C and below 100°C, more preferably below 100°C, and even more preferably below 95°C. Within this temperature range, the reaction rate of the thermosetting resin in step (a) can be suppressed, and a sheet with good workability can be obtained.

[0209] (a) The pressing pressure in the process is 40 MPa or more and 1000 MPa or less, preferably 45 MPa or more, more preferably 50 MPa or more, and preferably 900 MPa or less, more preferably 700 MPa or less, and even more preferably 500 MPa or less. Within this pressure range, the porosity tends to be reduced, resulting in a resin composition layer with good thermal conductivity.

[0210] (a) The pressing time of the process is not particularly limited, but it is preferably more than 1 minute, more preferably more than 3 minutes, more preferably within 5 hours, and more preferably within 2 hours.

[0211] By setting the pressing time within the above range, a sheet with good operability and adhesion to the metal part is obtained.

[0212] (a) The reaction rate (hereinafter, sometimes referred to as "reaction rate (A)") of the thermosetting resin contained in the sheet after the process is not particularly limited, but is preferably less than 50%. The reaction rate (A) is more preferably 40% or less, further preferably 30% or less, and particularly preferably 20% or less. By keeping the reaction rate (A) of the thermosetting resin below the above-mentioned upper limit, it is easier to obtain a sheet with good workability and adhesion.

[0213] The reactivity (A) of the thermosetting resin in the sheet is calculated based on the calorific value of the sheet before and after process (a) using the following formula, where the calorific value is the calorific value of the exothermic peak obtained by differential scanning calorimetry (DSC) at a rate of 10 °C / min from 40 °C to 250 °C:

[0214] Reaction rate (A)(%) = (1 - (calorific value after process (a) / calorific value before process (a))) × 100.

[0215] (a) The film thickness (Fa) of the sheet after the process is not particularly limited, but it is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, and preferably 1000 μm or less, more preferably 800 μm or less. By making the film thickness (Fa) of the sheet at or above the above lower limit, insulation is tended to be obtained, and by making it at or below the above upper limit, thermal resistance tends to be reduced.

[0216] The film thickness of the sheet can be measured using a contact or non-contact film thickness gauge.

[0217] The same applies to the film thickness (Fb) of the resin composition layer after process (b).

[0218] (a) There are no particular limitations on the pressing process, but flat pressing, roll pressing, and hydrostatic pressing are preferred.

[0219] There is no particular limitation on the specific configuration of the flatbed press for the pressing process. For example, it may include a pair of parallel flat plates (pressing discs) with a hard chrome-plated layer on the surface after mirror polishing, a pressure control mechanism for controlling the pressing pressure of the pressing discs, and a heating mechanism for heating the pressing discs to a specified temperature. The sheet is held between the pair of pressing discs and pressed from both sides while being heated to the specified temperature. In step (a), the flatbed pressing process, which applies pressure to the surface of the pressing discs with high smoothness, tends to make the surface of the sheet smoother, and the adhesion between the resulting resin composition layer and the metal part is improved.

[0220] By performing roll pressing, the surface of the sheet can be smoothed in process (a), thus increasing productivity.

[0221] There is no particular limitation on the specific configuration of the rolling mill used for roll pressing; various types of rolling mills, such as those with a pair of clamping rollers or those with multiple clamping rollers, can be used. Examples of rolling mills for roll pressing include devices comprising: a preheating roller (which may be omitted depending on the situation), at least a pair of clamping rollers, and preferably a heating mechanism for heating the clamping rollers. By clamping the sheet between the pair of clamping rollers and pressing it on both sides, pressure is applied to the surface of the sheet to smooth it.

[0222] Hydrostatic pressing allows for large-area high-pressure pressing, suppressing uneven pressing of sheets. Multiple sheets can be processed simultaneously, thus increasing productivity.

[0223] There are no particular limitations on the specific structure of a hydrostatic press. Examples include: a press equipped with a pressure vessel filled with a liquid such as oil or water, a pressure cylinder for pressurizing the liquid, a control mechanism for controlling the pressure applied to the liquid, and a heating mechanism for heating the liquid to a specified temperature. More specifically, an example is a device that involves vacuum-packing a sheet with a carrier film and immersing it in a liquid such as oil or water in a hydrostatic press for hydrostatic pressing, thereby subjecting the sheet to uniform pressure and smoothing its surface.

[0224] <(b) Process>

[0225] (b) is a process of pressing the sheet material that has undergone (a) 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.

[0226] (b) There are no particular restrictions on the pressing method in the process; for example, it can be done by pressing with a flat plate.

[0227] (b) is a process for supplying the sheet material that has undergone (a) and can perform pressing processing on sheet monomers, laminates of carrier film / sheet / metal portions, laminates of metal portions / sheets, etc. The manufacturing method of the present invention is a method with excellent adhesion and is suitable for manufacturing methods that perform pressing processing on laminates containing metal portions and sheets.

[0228] (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, and preferably 240°C or lower, more preferably 230°C or lower, and even more preferably 220°C or lower. Within this temperature range, a resin composition layer with high elastic modulus, adhesion and heat resistance is tended to be obtained.

[0229] (b) The pressing pressure in the process is 3 MPa or more and 100 MPa or less, preferably 3.5 MPa or more, and more preferably 4 MPa or more. Within this pressure range, a resin composition layer with excellent voltage resistance, thermal conductivity, and adhesion is tended to be obtained.

[0230] (b) The pressing time of the process is not particularly limited, but it is preferably 5 minutes or more, more preferably 10 minutes or more, and preferably within 24 hours. The pressing time is preferably the time for the reaction rate (B) of the thermosetting resin described later to reach 60% or more.

[0231] (b) The reaction rate (hereinafter sometimes referred to as "reaction rate (B)") of the thermosetting resin contained in the sheet after the process is not particularly limited, but is preferably 60% or more, more preferably 70% or more, further 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%. By making the reaction rate (B) of the thermosetting resin within the above range, sufficient curing is carried out, and a resin composition layer with excellent heat resistance and adhesion is tended to be obtained.

[0232] The reactivity (B) of the thermosetting resin in the sheet is calculated based on the calorific value of the sheet before (a) and after (b) the process, using the following formula, where the calorific value is the calorific value of the exothermic peak obtained by differential scanning calorimetry (DSC) at a rate of 10 °C / min from 40 °C to 250 °C:

[0233] Reaction rate (B)(%) = (1 - (calorific value after process (b) / calorific value before process (a))) × 100.

[0234] (b) The film thickness (Fb) of the resin composition layer after the process is not particularly limited, but it is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, and preferably 1000 μm or less, more preferably 800 μm or less. By making the film thickness (Fb) of the resin composition layer above the above lower limit, insulation is tended to be obtained, and by making it below the above upper limit, thermal resistance tends to be reduced.

[0235] <(a) combination of process and (b) process>

[0236] The pressing conditions of process (a) and process (b), as well as the film thickness of the sheet and resin composition layer, are not particularly limited as long as they are within the ranges described above, but the following combination is particularly preferred.

[0237] When the pressing temperature of process (b) is set to Tb (°C) and the pressing temperature of process (a) is set to Ta (°C),

[0238] The preferred values ​​are Tb > Ta and 30℃ ≦ Tb-Ta ≦ 220℃.

[0239] The Tb-Ta temperature is preferably 30°C or higher, more preferably 40°C or higher, and preferably 220°C or lower, more preferably 200°C or lower, and even more preferably 180°C or lower. By setting the Tb-Ta temperature within the above range, it is possible to balance the workability of the sheet material with the adhesion of the resin composition layer.

[0240] When the pressing pressure of process (b) is set to Pb (MPa) and the pressing pressure of process (a) is set to Pa (MPa),

[0241] Preferably, Pa > Pb and Pa / Pb is 1.5 or higher and 50 or lower.

[0242] The Pa / Pb ratio is preferably 1.5 or higher, more preferably 1.8 or higher, even more preferably 2 or higher, and preferably 50 or lower, more preferably 45 or lower, and even more preferably 40 or lower. By setting the Pa / Pb ratio to the above range, the porosity within the resin composition layer can be reduced, and by appropriately maintaining the shape of the aggregated inorganic filler, a resin composition layer with excellent voltage resistance and thermal conductivity can be obtained.

[0243] When the film thickness of the resin composition layer after step (b) is set as Fb and the film thickness of the sheet after step (a) is set as Fa, the ratio (Fb / Fa) is preferably 0.7 or more and 1.2 or less.

[0244] The Fb / Fa ratio is preferably 0.7 or higher, more preferably 0.8 or higher, even more preferably 0.85 or higher, and preferably 1.2 or lower, more preferably 1.1 or lower.

[0245] The range of Fb / Fa indicates that the porosity in the sheet is effectively reduced after process (a), and the film thickness change before and after process (b) is smaller, tending to obtain a resin composition layer with excellent voltage resistance and thermal conductivity.

[0246] In this invention, as step (a), a sheet is formed on a carrier film using the resin composition of this invention, and the sheet is pressed together with the carrier film. As step (b), it is particularly preferable to press a laminate containing the metal part and the sheet in a state where the sheet from step (a) is in contact with the metal part.

[0247] [Thermal conductivity and voltage resistance of the resin composition layer]

[0248] The thermal conductivity and voltage resistance 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.

[0249] The voltage withstand capability 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.

[0250] The methods for measuring thermal conductivity and voltage withstand capability in this invention are not particularly limited, but the methods shown in the embodiments described later can be cited.

[0251] [Composite Molded Body]

[0252] The composite molded article of the present invention is an integrally laminated resin composition layer and a metal portion thereof. The metal portion may be provided on only one surface of the resin composition layer, or on two or more surfaces. For example, the metal portion may be present on only one surface of the resin composition layer, or on both surfaces. Furthermore, the metal portion may be patterned.

[0253] Such a composite molded body of the present invention can be manufactured, for example, by using a metal portion as a substrate (carrier film), forming the resin composition of the present invention into a sheet on the substrate, and pressing it through the aforementioned steps (a) and (b). Overlapping it with other metal sheets during step (b) can also yield a composite molded body having metal portions on both sides.

[0254] Alternatively, the composite molded body of the present invention can also be manufactured by peeling a sheet-like resin composition formed on a substrate (carrier film) different from the metal part from the carrier film after step (a), overlapping it on the metal part material that becomes the metal part, and pressing it in step (b).

[0255] In this case, in addition to coating on a carrier film such as PET that has been optionally treated with a release agent, the sheet-like resin composition of the present invention can be peeled off from the carrier film after step (a) in the same manner as described above, and the sheet-like resin composition can be pressed in step (b) while placed on another metal plate or sandwiched between two metal plates to form an integral structure.

[0256] As the metal sheet, a metal sheet with a thickness of 10 μm to 10 cm made of copper, aluminum, nickel-plated metal, etc., can be used. The surface of the metal sheet can be physically roughened or chemically treated with a surface treatment agent, etc. From the perspective of the adhesion between the resin composition layer and the metal sheet, these treatments are more preferred.

[0257] [Semiconductor Devices]

[0258] The composite molded body of the present invention can be used as a semiconductor device. In particular, it can be effectively used in power semiconductor devices that achieve high output and high density by operating at high temperatures.

[0259] Example

[0260] The present invention will be further described in detail below through embodiments. The present invention is not limited to the following embodiments as long as it does not depart from its spirit.

[0261] The various conditions and evaluation results in the following embodiments are also conditions and values ​​that represent the preferred range of the present invention, just as the preferred range in the embodiments of the present invention. The preferred range of the present invention can be determined by the range represented by the preferred range in the above embodiments and the values ​​in the following embodiments or by a combination of values ​​between embodiments.

[0262] [raw materials]

[0263] The raw materials used in the examples and comparative examples are described below.

[0264] <Thermosetting Resins>

[0265] Resin component 1: Epoxy resin manufactured according to the epoxy resin manufacturing method disclosed in the examples of Japanese Patent Application Publication No. 2006-176658.

[0266] Polystyrene weight-average molecular weight (converted): 30,000

[0267] Epoxy equivalent: 9,000 g / equivalent

[0268] Resin component 2: Bisphenol A type liquid epoxy resin, weight average molecular weight: below 600

[0269] Resin component 3: Biphenyl-type solid epoxy resin, weight average molecular weight: below 600

[0270] Resin component 4: Non-aromatic multifunctional epoxy resin with more than 4 glycidyl groups per molecule, weight average molecular weight: below 600.

[0271] <Agglomerated Inorganic Packing>

[0272] Inorganic filler 1: Boron nitride aggregated particles with a shelf structure manufactured according to the method for manufacturing boron nitride aggregated particles disclosed in the examples of International Publication No. 2015 / 561028.

[0273] New Mohs hardness: 2

[0274] Volume average particle size: 45 μm

[0275] <Other packings>

[0276] Inorganic filler 2: Spherical alumina particles manufactured by ADOMATECHS.

[0277] New Mohs hardness: 9

[0278] Volume average particle size: 6.5 μm

[0279] Thermal conductivity: 20~30W / m·K

[0280] <Curing agent>

[0281] Hardener 1: MEH-8000H manufactured by Meiwa Kasei Corporation

[0282] Phenolic resin curing agent

[0283] <Catalyst Components>

[0284] Curing catalyst 1: "CUREZOL 2E4MZ-A" manufactured by Shikoku Chemical Industry Co., Ltd.

[0285] Curing catalyst 2: "CUREZOL 2PHZ-PW" manufactured by Shikoku Chemical Industry Co., Ltd.

[0286] [Determination Method]

[0287] <Reactivity of thermosetting resins>

[0288] Based on the differential scanning calorimetry (DSC) measurements of the sheets formed before and after each of steps (a) and (b) (after step (b) the resin composition layer), the calorific value of the exothermic peak obtained when the temperature is increased from 40°C to 250°C at a rate of 10°C / min was used to calculate the reaction rate using the following formula:

[0289] (a) Reaction rate of process (A)(%) = (1 - (calorific value after process (a) / calorific value before process (a)) × 100;

[0290] (b) Reaction rate of process (B)(%) = (1 - (calorific value after process (b) / calorific value before process (a))) × 100.

[0291] Thermal conductivity in the thickness direction of the resin composition layer

[0292] Using a thermal resistance measuring device (manufactured by Mentor Graphics Co., Ltd., product name "T3ster"), the thermal resistance values ​​of resin composition layers of different thicknesses produced under the same composition and conditions were measured, and the thermal conductivity was determined from the slope of the graph plotted by the thermal resistance value relative to the thickness.

[0293] <Voltage Resistance of Resin Composite Layer>

[0294] In insulating oil, the voltage applied to the resin composition layer is increased by 500V every minute, and the breakdown voltage of the resin composition layer is calculated. The obtained breakdown voltage value is converted into the breakdown voltage per unit film thickness of 1mm to obtain the withstand voltage (kV / mm).

[0295] <Sheet Handling Tests (Mandrel Test)>

[0296] Following step (a), the sheet with the carrier film is subjected to a bending test at 24°C with the carrier film on the inside, according to JISK 5600-5-1. A 180° bending test is performed using an 8mm diameter mandrel. Items with visible cracks or peeling are marked ×, and items without cracks or peeling are marked 〇.

[0297] [Example 1]

[0298] A mixture is prepared by mixing resin component 1, resin component 2, resin component 4, curing agent 1, curing catalyst 1, inorganic filler 1, and inorganic filler 2 in the mass ratios described in Composition A of Table 1 below using a rotary-revolutionary mixing device. When preparing this mixture, a slurry-like resin composition is prepared using 18.5% by mass each of methyl ethyl ketone and cyclohexanone, so that the mixture constitutes 63% by mass (solids concentration) in the coating slurry.

[0299] The obtained slurry-like resin composition was coated onto a PET film using a doctor blade method and dried at 60°C for 120 minutes. Then, as step (a), each PET film was pressed at 50°C and 147 MPa for 10 minutes using a flatbed press to obtain a sheet with a thickness of 150 μm. The total content of methyl ethyl ketone and cyclohexanone in the sheet was less than 1% by mass (solid content concentration greater than 99% by mass).

[0300] (a) The reaction rate (A) of the thermosetting resin in the sheet after the process is less than 10%.

[0301] A copper substrate was laminated onto the sheet after process (a), and then cured at 175°C and 9.8 MPa for 30 minutes as process (b) to obtain a resin composition layer. The thickness of the resin composition layer was 141 μm, and the ratio of the film thickness after process (b) to the film thickness after process (a) (Fb / Fa) was 0.94. The results of the sheet's operability evaluation (mandrel test) are shown in Table 2A.

[0302] (b) The reaction rate (B) of the thermosetting resin in the resin composition layer after the process is more than 90%, and the withstand voltage of the resin composition layer is 53kV / mm.

[0303] The thermal conductivity of the resin composition layer in Example 1 was determined using samples with the same composition and processed through the same (a) and (b) steps.

[0304] The sheet-like resin composition after step (a) is sandwiched in a PET film and cured at the pressure and temperature specified in step (b) to obtain a resin composition layer.

[0305] In addition, using the same method, after peeling off the carrier film from the sheet in step (a), samples with 2, 3, and 4 overlapping layers were clamped in PET film and processed in step (b) at a specified pressure / temperature to obtain four resin composition layers of different thicknesses. When the thermal conductivity of the resin composition layer was measured using the above method, it was 15 W / mK.

[0306] These results are summarized in Table 2A.

[0307] <Examples 2-6, Comparative Examples 1-7>

[0308] Resin compositions were prepared using components A or B as shown in Table 1, following the method of Example 1, and processed using the pressing conditions and pressing methods shown in Tables 2A and 2B. The results are summarized in Tables 2A and 2B.

[0309] [Table 1]

[0310]

[0311] [Table 2A]

[0312]

[0313] [Table 2B]

[0314]

[0315] As can be seen from Tables 2A and 2B, according to the present invention, a resin composition layer with good voltage resistance and thermal conductivity can be obtained by processing in steps (a) and (b) at a specified pressure / temperature.

[0316] Although the invention has been described in detail using specific methods, it will be apparent to those skilled in the art that various modifications may be made without departing from the intent and scope of the invention.

[0317] This application is based on Japanese Patent Application 2020-069766, filed on April 8, 2020, which is incorporated herein by reference in its entirety.

Claims

1. A method for manufacturing a resin composition layer, comprising a resin composition layer consisting of a resin composition containing aggregated inorganic filler and a thermosetting resin, the method comprising the following steps (a) and (b): (a) A process of pressing a carrier film and a sheet formed on the carrier film using the resin composition under conditions of a pressing temperature of 0°C or higher and 110°C or lower, and a pressing pressure of 40 MPa or higher and 1000 MPa or lower. (b) A process of pressing the sheet material that has undergone step (a) under conditions of 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. When the pressing pressure of process (b) is set to Pb and the pressing pressure of process (a) is set to Pa, Pa>Pb and Pa / Pb is greater than 1.5 and less than 50. The units of Pb and Pa are MPa.

2. A method for manufacturing a resin composition layer, comprising a resin composition layer consisting of a resin composition containing aggregated inorganic filler and a thermosetting resin, the method comprising the following steps (a) and (b): (a) A process of pressing a carrier film and a sheet formed on the carrier film using the resin composition under conditions of a pressing temperature of 0°C or higher and 110°C or lower, and a pressing pressure of 40 MPa or higher and 1000 MPa or lower. (b) A process of pressing the sheet material that has undergone step (a) under conditions of 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. When the film thickness after process (b) is set as Fb and the film thickness after process (a) is set as Fa, Fb / Fa is 0.7 or more and 1.2 or less.

3. The method for manufacturing the resin composition layer according to claim 1 or 2, wherein, When the pressing temperature of process (b) is set to Tb and the pressing temperature of process (a) is set to Ta, Tb > Ta and 30℃ ≦ Tb - Ta ≦ 220℃, the units of Tb and Ta are ℃.

4. The method for manufacturing the resin composition layer according to claim 1 or 2, wherein, The reaction rate of the thermosetting resin in the sheet after process (a), determined by the following method, i.e., the reaction rate A, is less than 50%. Methods for determining and calculating reaction rate A Based on the heat of the exothermic peak obtained by differential scanning calorimetry (DSC) of the sheets before and after process (a) at a rate of 10°C / min from 40°C to 250°C, the heat is calculated using the following formula: Reaction rate A = (1 - (calorific value after process (a) / calorific value before process (a))) × 100%.

5. The method for manufacturing the resin composition layer according to claim 1 or 2, wherein, The reaction rate of the thermosetting resin in the sheet after process (b), determined by the following method, i.e., the reaction rate B, is 60% or more: Methods for determining and calculating reaction rate B Based on the sheet material before process (a) and after process (b), the heat of the exothermic peak obtained by differential scanning calorimetry (DSC) at a heating rate of 10℃ / min from 40℃ to 250℃ is calculated using the following formula: Reaction rate B = (1 - (calorific value after process (b) / calorific value before process (a))) × 100%.

6. The method for manufacturing the resin composition layer according to claim 1 or 2, wherein, The pressing process in step (a) is a flat plate pressing process.

7. The method for manufacturing the resin composition layer according to claim 1 or 2, wherein, The pressing process in step (a) is a roller pressing process.

8. The method for manufacturing the resin composition layer according to claim 1 or 2, wherein, The pressing process in step (a) is hydrostatic pressing.

9. The method for manufacturing the resin composition layer according to claim 1 or 2, wherein, The thermosetting resin contains an epoxy compound.

10. The method for manufacturing the resin composition layer according to claim 9, wherein, The thermosetting resin comprises epoxy compounds with a weight average molecular weight of 10,000 or more and epoxy compounds with a weight average molecular weight of 600 or less.

11. The method for manufacturing a resin composition layer according to claim 9, wherein, The thermosetting resin comprises an epoxy compound with a weight average molecular weight of less than 600 and containing more than 3 epoxy groups per molecule.

12. The method for manufacturing the resin composition layer according to claim 1 or 2, wherein, The aggregated inorganic packing includes aggregated boron nitride packing.

13. The method for manufacturing the resin composition layer according to claim 12, wherein, The aggregated inorganic packing includes aggregated boron nitride packing with a shelf structure.

14. A resin composition layer obtained by the manufacturing method according to any one of claims 1 to 13.

15. A composite molded body having a resin composition layer as described in claim 14 and a metal portion.

16. A method for manufacturing a composite molded article, comprising a method for manufacturing a composite molded article having a resin composition layer and a metal portion, wherein, The resin composition layer is formed by the manufacturing method of the resin composition layer according to any one of claims 1 to 13.

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