Resin sheets and laminates

Abstract

To provide a resin sheet that can achieve both low thermal resistance and high insulation reliability. [Solution] The resin sheet 1 comprises a support 2, a first resin layer 31 derived from a first resin composition, and a second resin layer 32 derived from a second resin composition. The ratio of the thickness of the first resin layer 31 to the thickness of the second resin layer 32 is less than 10%. The first resin composition contains epoxy resin (A1), a curing agent (B1), and an inorganic filler (C1) including a nanofiller (C1-1) with a median diameter of 100 nm or less. The second resin composition contains epoxy resin (A2), a curing agent (B2), and an inorganic filler (C2) including a thermally conductive filler (C2-1) with a thermal conductivity of 10 W / (m·K) or more. The content of nanofiller (C1-1) is 5 to 200 parts by mass per 100 parts by mass of the resin component of the first resin composition. The content of thermally conductive filler (C2-1) is 80 to 97% by mass of the total amount of the second resin composition.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to resin sheets and laminates, and more particularly to a resin sheet comprising a support and a resin layer, and a laminate comprising a support and an insulating layer. BACKGROUND ART

[0002] Patent Document 1 discloses an epoxy resin composition for use as an electrical insulating material. This epoxy resin composition comprises an epoxy resin and a curing agent for epoxy resins which is a specific liquid polyhydric hydroxy resin. PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0003] PATENT DOCUMENT 1 Japanese Patent Laid-Open No. 2017-110198 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] In the prior art, as a method for reducing the thermal resistance of an insulating layer containing the epoxy resin composition of Patent Document 1, addition of a thermally conductive filler to the epoxy resin composition may be mentioned. However, the more the epoxy resin composition is filled with the thermally conductive filler, the more the thermal resistance of the insulating layer formed from the epoxy resin composition is reduced, but on the other hand, there is a risk that the insulation reliability may be lowered. That is, the insulating layer containing the epoxy resin composition of Patent Document 1 has a problem that it is difficult to achieve both low thermal resistance and high insulation reliability.

[0005] An object of the present disclosure is to provide a resin sheet and a laminate that can achieve both low thermal resistance and high insulation reliability. MEANS FOR SOLVING THE PROBLEMS

[0006] A resin sheet according to one aspect of the present disclosure comprises a support, a first resin layer containing a semi-cured or cured product of a first resin composition superimposed on the support, and a second resin layer containing a second resin composition or a semi-cured product of a second resin composition superimposed on the first resin layer. The ratio of the thickness of the first resin layer to the thickness of the second resin layer is less than 10%. The first resin composition contains an epoxy resin (A1), a curing agent (B1), and an inorganic filler (C1) containing a nanofiller (C1-1) having a median diameter (value of 50% of the cumulative value in the volume-based particle size distribution by laser diffraction / scattering method) of 100 nm or less. The second resin composition contains an epoxy resin (A2), a curing agent (B2), and an inorganic filler (C2) containing a thermally conductive filler (C2-1) having a thermal conductivity of 10 W / (m·K) or more. The content of the nanofiller (C1-1) is 5 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the resin component of the first resin composition. The content of the thermally conductive filler (C2-1) is 80% by mass or more and 97% by mass or less of the total amount of the second resin composition.

[0007] A laminate according to one aspect of the present disclosure comprises a support, a first insulating layer containing a cured product of a first resin composition superimposed on the support, and a second insulating layer containing a cured product of a second resin composition superimposed on the first insulating layer. The ratio of the thickness of the first insulating layer to the thickness of the second insulating layer is less than 10%. The first resin composition contains an epoxy resin (A1), a curing agent (B1), and an inorganic filler (C1) containing a nanofiller (C1-1) having a median diameter of 100 nm or less. The second resin composition contains an epoxy resin (A2), a curing agent (B2), and an inorganic filler (C2) containing a thermally conductive filler (C2-1) having a thermal conductivity of 10 W / (m·K) or more. The content of the nanofiller (C1-1) is 5 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the resin component of the first resin composition. The content of the thermally conductive filler (C2-1) is 80% by mass or more and 97% by mass or less, based on the total amount of the second resin composition. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide resin sheets and laminates that can achieve both low thermal resistance and high insulation reliability. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic cross-sectional view showing a resin sheet according to an embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view showing a laminate according to the embodiment. [Figure 3] Figure 3 is a schematic cross-sectional view showing the evaluation laminate of the embodiment. [Figure 4] Figure 4 is a schematic plan view showing the test pattern of the embodiment. [Modes for carrying out the invention]

[0010] The embodiments of this disclosure are described below. However, this disclosure is not limited to the embodiments described below. The embodiments described below are only a part of the various embodiments of this disclosure, and various modifications are possible depending on the design, as long as the objectives of this disclosure are achieved. The figures referenced below are all schematic diagrams, and the dimensional ratios of the components in the figures do not necessarily reflect the actual dimensional ratios. The mechanisms of operation of the embodiments may be described below, but the descriptions of the mechanisms of operation include those based on speculation, and this disclosure is not bound by the descriptions of the mechanisms of operation below.

[0011] 1. Overview As mentioned above, the more thermally conductive fillers are added to the resin composition, the lower the thermal resistance of the insulating layer formed by the resin composition may be. On the other hand, this may reduce the insulating reliability of the formed insulating layer.

[0012] One of the causes of reduced insulation reliability is the migration of ionic impurities along the surface of thermally conductive fillers within the resin composition. Therefore, means to restrict the migration of ionic impurities are required.

[0013] Therefore, based on the above-mentioned causes, the inventors diligently conducted research and succeeded in developing a resin sheet and a laminate formed from this resin sheet that can achieve both low thermal resistance and high insulation reliability.

[0014] The resin sheet 1 according to the embodiment of this disclosure comprises a support 2, a first resin layer 31 containing a semi-cured or cured product of the first resin composition superimposed on the support 2, and a second resin layer 32 containing a second resin composition or a semi-cured product of the second resin composition superimposed on the first resin layer 31. The ratio of the thickness of the first resin layer 31 to the thickness of the second resin layer 32 is less than 10%. The first resin composition contains an epoxy resin (A1), a curing agent (B1), and an inorganic filler (C1) containing a nanofiller (C1-1) having a median diameter (value of 50% of the cumulative value in the volume-based particle size distribution by laser diffraction / scattering method) of 100 nm or less. The second resin composition contains an epoxy resin (A2), a curing agent (B2), and an inorganic filler (C2) containing a thermally conductive filler (C2-1) having a thermal conductivity of 10 W / (m·K) or more. The content of nanofiller (C1-1) is 5 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the resin component of the first resin composition. The content of thermally conductive filler (C2-1) is 80% by mass or more and 97% by mass or less of the total amount of the second resin composition.

[0015] The resin sheet 1 and the laminate 10 formed from the resin sheet 1, having the above-described configuration, can achieve both low thermal resistance and high insulation reliability. This is presumed to be due to the following mechanism.

[0016] The first resin layer 31 is interposed between the support 2 and the second resin layer 32. This can restrict the movement of ionic impurities generated in the second resin layer 32 from the second resin layer 32 to the support 2. Therefore, the resin sheet 1 having the first resin layer 31 and the laminate 10 formed from the resin sheet 1 can have high insulation reliability.

[0017] The second resin composition forming the second resin layer 32 contains an inorganic filler (C2) including a thermally conductive filler (C2-1) having a thermal conductivity of 10 W / (m·K) or more. The content of the thermally conductive filler (C2-1) is 80 mass% or more and 97 mass% or less with respect to the total amount of the second resin composition. Accordingly, the thermal resistance of the resin sheet 1 provided with the second resin layer 32 and the laminate 10 formed from the resin sheet 1 can be reduced.

[0018] The ratio of the thickness of the first resin layer 31 to the thickness of the second resin layer 32 is less than 10%. That is, the constituent ratio of the second resin layer 32 capable of reducing thermal resistance is large with respect to the entire resin sheet 1. Accordingly, the resin sheet 1 provided with the first resin layer 31 and the laminate 10 formed from the resin sheet 1 can have improved insulation reliability and reduced thermal resistance.

[0019] The first resin composition contains an inorganic filler (C1) including a nanofiller (C1-1) having a median diameter of 100 nm or less. The content of the nanofiller (C1-1) is 5 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the resin component of the first resin composition. Accordingly, the resin sheet 1 provided with the first resin layer 31 and the laminate 10 formed from the resin sheet 1 can have improved insulation reliability and reduced thermal resistance.

[0020] As described above, the resin sheet 1 according to the embodiment of the present disclosure and the laminate 10 formed from the resin sheet 1 can achieve both reduction in thermal resistance and high insulation reliability.

[0021] In addition, the thermal resistance between two cross sections of an object having a thickness T and a cross-sectional area A of the two cross sections facing each other in the thickness direction is calculated from the following formula.

[0022] (Thermal resistance) = (Thickness T) / {(Thermal conductivity) × (Cross-sectional area A)} Therefore, from the above formula, the thermal conductivity and thermal resistance of an object having certain dimensions are inversely related. Thus, reducing thermal resistance is synonymous with increasing thermal conductivity. In other words, the resin sheet 1 and the laminate 10 formed from the resin sheet 1 according to the embodiment of this disclosure can achieve both high thermal conductivity and high insulation reliability.

[0023] In this disclosure, "median diameter" refers to the 50% integrated value of the volume-based particle size distribution obtained by laser diffraction and scattering. The median diameter may also be referred to as D50.

[0024] 2.Details The resin sheet 1 and laminate 10 according to the embodiment will be described below with reference to the drawings. The arrows indicating directions in each figure are not intended to define the direction of use of the resin sheet 1 and laminate 10, but are merely there to facilitate understanding of the explanation and do not represent any actual physical object. The X, Y, and Z axes are mutually orthogonal. Hereinafter, viewing along the Z axis will be referred to as the XY planar view.

[0025] 2.1 Resin Sheet The resin sheet 1 according to this embodiment has thickness in the Z-axis direction and is sheet-shaped, extending in the X-axis and Y-axis directions (see Figure 1). The resin sheet 1 comprises a support 2, a first resin layer 31, and a second resin layer 32. The first resin layer 31 and the second resin layer 32 are sometimes collectively referred to as the resin layer 3.

[0026] 〔composition〕 (Support) The support 2 is located on at least one of the outermost layers in the thickness direction of the resin sheet 1. Examples of the support 2 include a support film, metal foil, metal film, and release paper.

[0027] The support film is an electrically insulating film made of a resin material. The material of the support film is not particularly limited, but examples include polyethylene terephthalate (PET) film, polyimide film, polyester film, polyparabanic acid film, polyether ether ketone film, polyphenylene sulfide film, polyamide film, polycarbonate film, and polyarylate film.

[0028] The material of the metal foil and metal film is not particularly limited, but examples include copper (Cu), aluminum (Al), stainless steel, nickel (Ni), and nichrome. The manufacturing method of the metal foil and metal film is not particularly limited, but examples include electrolytic methods and rolling methods. The metal film may also be formed by plating, steaming, etc.

[0029] The surface of the support 2 that supports the first resin layer 31 may be subjected to matte treatment, corona treatment, antistatic treatment, plasma treatment, silane coupling agent treatment, etc.

[0030] (1st resin layer) The first resin layer 31 is superimposed on the support 2. Specifically, the first resin layer 31 is superimposed on one surface of the support 2 (the surface in the negative Z-axis direction). The first resin layer 31 may also be superimposed on and bonded to the support 2.

[0031] The thickness ratio of the first resin layer 31 is less than 10% of the thickness of the second resin layer 32. This can reduce the thermal resistance of the resin sheet 1 and the laminate 10 formed from the resin sheet 1. This ratio is preferably 8% or less, and more preferably 5% or less. This ratio is, for example, 0.1% or more.

[0032] The thickness of the first resin layer 31 is preferably 0.1 μm or more. In this case, the insulation reliability of the resin sheet 1 and the laminate 10 formed from the resin sheet 1 can be further improved. This thickness is more preferably 0.5 μm or more, and even more preferably 1.0 μm or more. The thickness of the first resin layer 31 is preferably less than 5.0 μm. In this case, the thermal resistance of the resin sheet 1 and the laminate 10 formed from the resin sheet 1 can be further reduced. This thickness is more preferably 4.5 μm or less, and even more preferably 4.0 μm or less.

[0033] The first resin layer 31 includes a semi-cured product or a cured product of the first resin composition.

[0034] <First resin composition> The first resin composition contains epoxy resin (A1), a curing agent (B1), and an inorganic filler (C1).

[0035] ≪Epoxy resin≫ The epoxy resin (A1) is a compound having one or more epoxy groups as functional groups in one molecule. Preferably, the epoxy resin (A1) has two or more epoxy groups in one molecule. In this case, the reactivity of the curing reaction of the first resin composition is increased, and the glass transition temperature of the cured product of the first resin composition can be further increased.

[0036] The epoxy resin (A1) is not particularly limited, but examples include trisphenolmethane type epoxy resin, naphthalene type epoxy resin, biphenyl aralkyl type epoxy resin, biphenyl type epoxy resin, and dicyclopentadiene type epoxy resin. Among these, the epoxy resin (A1) is preferably a trisphenolmethane type epoxy resin. A trisphenolmethane type epoxy resin has three phenylmethane skeleton epoxy groups in one molecule. Thus, because the trisphenolmethane type epoxy resin has a high epoxy group concentration, the glass transition temperature of the cured product of the first resin composition can be further increased.

[0037] ≪Hardening agent≫ The curing agent (B1) is a compound that reacts with the epoxy resin (A1) to form a crosslinked (cured) structure, and is a component that can increase the glass transition temperature of the cured product of the first resin composition. The curing agent (B1) is not particularly limited, but examples include phenolic resins and dicyandiamides. A phenolic resin is preferred as the curing agent (B1).

[0038] Phenolic resins are compounds having one or more phenolic hydroxyl groups as functional groups in one molecule. Preferably, phenolic resins have two or more phenolic hydroxyl groups in one molecule.

[0039] The phenolic resin is not particularly limited, but examples include biphenyl aralkyl phenolic resins, long-chain alkylphenolic resins, phenyl aralkyl phenolic resins, novolac phenolic resins, cresol novolac phenolic resins, bisphenol A novolac phenolic resins, naphthalene phenolic resins, tetrakisphenol phenolic resins, and phosphorus atom-containing phenolic resins. Among these, the phenolic resin is preferably at least one selected from the group consisting of biphenyl aralkyl phenolic resins and long-chain alkylphenolic resins. Biphenyl aralkyl phenolic resins can impart flame retardancy, heat resistance, and adhesion to the cured product of the first resin composition. Long-chain alkylphenolic resins can impart low viscosity and high fluidity to the first resin composition.

[0040] The functional group equivalent of the curing agent (B1) relative to the functional group equivalent of the epoxy resin (A1) (functional group equivalent of curing agent (B1) / functional group equivalent of epoxy resin (A1)) is preferably 0.3 or more and 1.3 or less, and more preferably 0.4 or more and 1.0 or less. A ratio of 0.3 or more in this equivalence ratio can further suppress the decrease in the glass transition temperature of the cured product of the first resin composition. A ratio of 1.3 or less can suppress the increase of polar groups such as hydroxyl groups, thereby further improving the insulation reliability of the resin sheet 1 and the laminate 10 formed from the resin sheet 1.

[0041] Inorganic fillers The inorganic filler (C1) is a component that can lower the coefficient of thermal expansion of the cured product of the first resin composition and reduce its thermal resistance.

[0042] The inorganic filler (C1) is not particularly limited, but examples include silica fillers such as synthetic silica filler, fused silica filler, or crystalline silica filler, talc filler, boehmite filler, magnesium hydroxide filler, aluminum hydroxide filler, magnesium hydroxide filler, aluminum silicate filler, magnesium silicate filler, zinc molybdate filler, calcium molybdate filler, clay filler, and mica filler. The inorganic filler (C1) contained in the first resin composition may be one type or two or more types.

[0043] The inorganic filler (C1) may be surface-treated with a coupling agent. Such coupling agents are not particularly limited, but examples include vinyltriethoxysilane, vinyltrimethoxysilane, methacryloxypropylmethyldimethoxysilane, p-styryltrimethoxysilane, p-styryltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropylethyldiethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, glycidoxypropyltriethoxysilane, 8-glycidoxyoctyltrimethoxysilane, isocyanatetopropyltriethoxysilane, and the like. The silane coupling agent used may be a single type or a combination of two or more types.

[0044] The inorganic filler (C1) contains nanofiller (C1-1). The median diameter of the nanofiller (C1-1) is 100 nm or less. Therefore, the first resin layer 31 can be formed thinly and uniformly. Thus, the decrease in the insulation reliability of the resin sheet 1 and the laminate 10 formed from the resin sheet 1 can be suppressed, and the thermal resistance can be reduced. This median diameter is more preferably 90 nm or less, and even more preferably 80 nm or less. This median diameter is, for example, 5 nm or more.

[0045] The nanofiller (C1-1) preferably contains silica filler. In this case, the resin sheet 1 and the laminate 10 formed from the resin sheet 1 can be adjusted to the desired moldability.

[0046] It is more preferable that the inorganic filler (C1) contains only nanofiller (C1-1). In this case, the thermal resistance can be particularly reduced while the decrease in the insulation reliability of the resin sheet 1 and the laminate 10 formed from the resin sheet 1 is particularly suppressed.

[0047] The content of nanofiller (C1-1) is 5 parts by mass or more per 100 parts by mass of the resin component of the first resin composition. A content of 5 parts by mass or more can reduce the thermal resistance of the resin sheet 1 and the laminate 10 formed from the resin sheet 1. This content is preferably 10 parts by mass or more, and more preferably 30 parts by mass or more. The content of nanofiller (C1-1) is 200 parts by mass or less per 100 parts by mass of the resin component of the first resin composition. A content of 200 parts by mass or less can improve the moldability of the resin sheet 1 and the laminate 10 formed from the resin sheet 1. This content is preferably 180 parts by mass or less, and more preferably 170 parts by mass or less. In this disclosure, "resin component of the first resin composition" refers to epoxy resin (A1) and curing agent (B1).

[0048] Elastomer The first resin composition may further contain elastomer (D1). Elastomer (D1) can enhance the adhesion of the first resin composition and increase the toughness of the cured product. This is because elastomer (D1) has sufficient dispersibility in the first resin composition and can impart flexibility to the cured product of the first resin composition.

[0049] The elastomer (D1) is not particularly limited, but examples include polyvinyl acetal resin, styrene-butadiene resin, butadiene resin, isoprene resin, silicone resin, acrylic resin, methacrylic resin, styrene resin, etc. The elastomer (D1) may contain only one type or two or more types.

[0050] The elastomer (D1) content is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, based on the total amount of the first resin composition. The elastomer (D1) content is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less, based on the total amount of the first resin composition. Within the above range, the fluidity of the first resin composition can be suppressed during the molding of the laminate 10, and the first resin layer 31 can be adjusted to a suitable thickness.

[0051] <<Other ingredients>> The first resin composition may contain other components besides those listed above. Such components are not particularly limited, but examples include curing accelerators.

[0052] A curing accelerator can accelerate the curing reaction of the first resin composition. While not particularly limited, examples of curing accelerators include imidazole compounds such as 2-ethyl-4-methylimidazole.

[0053] (2nd resin layer) The second resin layer 32 is superimposed on the first resin layer 31. Specifically, the second resin layer 32 is superimposed on the surface of the first resin layer 31 opposite to the surface facing the support 2 (the surface in the negative Z-axis direction). The second resin layer 32 may also be superimposed on and bonded to the first resin layer 31.

[0054] The second resin layer 32 includes the second resin composition or a semi-cured product of the second resin composition.

[0055] <Second resin composition> The second resin composition contains epoxy resin (A2), a curing agent (B2), and an inorganic filler (C2).

[0056] ≪Epoxy resin≫ Epoxy resin (A2) is the same as epoxy resin (A1). Therefore, the effects and preferred structures when epoxy resin (A2) is included are the same as those described for epoxy resin (A1) above. For this reason, the description of epoxy resin (A2) may be omitted as appropriate.

[0057] ≪Hardening agent≫ The curing agent (B2) is the same as that of curing agent (B1). Therefore, the effects and preferred structure when curing agent (B2) is included are the same as those described for curing agent (B1) above. For this reason, the description of curing agent (B2) may be omitted as appropriate.

[0058] Inorganic fillers Inorganic filler (C2) is similar to inorganic filler (C1) in terms of preferred compounds and coupling agents used. However, inorganic filler (C2) differs from inorganic filler (C1) in that it does not contain nanofiller (C1-1) but does contain thermally conductive filler (C2-1). Therefore, the similarities between inorganic filler (C2) and inorganic filler (C1) will be omitted as appropriate, and the difference, thermally conductive filler (C2-1), will be explained in detail.

[0059] As described above, the inorganic filler (C2) includes a thermally conductive filler (C2-1). The thermal conductivity of the thermally conductive filler (C2-1) is 10 W / (m·K) or higher. Therefore, the thermal resistance of the resin sheet 1 and the laminate 10 formed from the resin sheet 1 can be reduced. A higher thermal conductivity of the thermally conductive filler (C2-1) is preferable because it can reduce the thermal resistance of the resin sheet 1 and the laminate 10 formed from the resin sheet 1, but the practical upper limit is, for example, 300 W / (m·K) or less.

[0060] The thermally conductive filler (C2-1) preferably includes at least one selected from the group consisting of magnesium oxide filler, aluminum nitride filler, and aluminum oxide filler. In this case, the thermal resistance of the resin sheet 1 and the laminate 10 formed from the resin sheet 1 can be further reduced.

[0061] Preferably, the thermal conductive filler (C2-1) includes a first thermal conductive filler and a second thermal conductive filler (C2-2) having a median diameter smaller than that of the first thermal conductive filler. This allows the second thermal conductive filler (C2-2), with its smaller median diameter, to be positioned between the first thermal conductive fillers (C2-1), which have larger median diameters, within the second resin composition, thereby increasing thermal contact between the thermal conductive fillers (C2-1). Consequently, the thermal resistance of the resin sheet 1 and the laminate 10 formed from the resin sheet 1 can be further reduced.

[0062] The median diameter of the first thermally conductive filler is preferably greater than 1 μm and 25 μm or less, and more preferably 4 μm or more and 20 μm or less. The median diameter of the second thermally conductive filler (C2-2) is preferably 0.05 μm or more and 1 μm or less, and more preferably 0.1 μm or more and 0.4 μm or less. As a result, thermal contact between the first thermally conductive fillers via the second thermally conductive filler (C2-2) in the second resin composition can be further promoted, thereby further reducing the thermal resistance of the resin sheet 1 and the laminate 10 formed from the resin sheet 1.

[0063] The content of the thermally conductive filler (C2-1) is 80% by mass or more of the total amount of the second resin composition. This content of 80% by mass or more can reduce the thermal resistance of the resin sheet 1 and the laminate 10 formed from the resin sheet 1. This content is preferably 82% by mass or more, and more preferably 84% by mass or more. The content of the thermally conductive filler (C2-1) is 97% by mass or less of the total amount of the second resin composition. This content of 97% by mass or less can suppress an increase in the viscosity of the second resin composition and improve its fluidity. This content is preferably 96% by mass or less, and more preferably 95% by mass or less.

[0064] <<Other ingredients>> The second resin composition may contain other components besides those listed above. Such components are not particularly limited, but examples include curing accelerators, flame retardants, coupling agents, dispersants, ion scavengers, heavy metal deactivators, and flow regulators.

[0065] The curing accelerator can accelerate the curing reaction of the second resin composition, similar to the contents of the first resin composition described above. The curing accelerator is not particularly limited, but examples include imidazole compounds such as 2-ethyl-4-methylimidazole.

[0066] The flame retardant can enhance the flame retardancy of the cured product of the second resin composition. While not particularly limited, examples of flame retardants include phosphorus-based flame retardants, halogen-based flame retardants, and inorganic flame retardants. A halogen-free phosphorus-based flame retardant is more preferable.

[0067] A coupling agent can improve the adhesion between the cured product of the first resin composition and the cured product of the second resin composition. The inorganic fillers listed above (C1) can be used as coupling agents.

[0068] The dispersant can uniformly disperse the inorganic filler (C2) in the second resin composition. The dispersant is not particularly limited, but examples include wetting dispersants.

[0069] The metal deactivator can suppress the degradation of the second resin composition by forming a complex with active metal ions (e.g., copper ions) that promote oxidative degradation in the second resin composition. The metal deactivator is not particularly limited, but examples include hydrazide derivatives, oxalic acid derivatives, salicylic acid derivatives, etc.

[0070] The ion scavenger can further improve the insulation reliability of the resin sheet 1 and the laminate 10 formed from the resin sheet 1 by capturing ionic impurities in the second resin composition and suppressing ion migration. The ion scavenger is not particularly limited, but examples include hydrotalcite.

[0071] The flow modifier adjusts the second resin composition to an appropriate fluidity, thereby enabling the second resin layer 32 to be formed with a uniform thickness. Furthermore, as in this embodiment, even if the second resin composition is highly filled with a thermally conductive filler (C2-1), the flow modifier can impart appropriate fluidity to the second resin composition during molding. This can suppress the generation of voids in the second resin composition. Because the generation of voids can be suppressed in this way, the occurrence of partial discharge within the second resin composition can be suppressed, which can further reduce the insulation reliability of the resin sheet 1 and the laminate 10 formed from the resin sheet 1. The flow modifier is not particularly limited, but examples include polyether ester types.

[0072] [Effects and Effects] In the resin sheet 1, the first resin layer 31 is interposed between the support 2 and the second resin layer 32. This can restrict the movement of ionic impurities in the resin sheet 1, thereby suppressing the occurrence of ion migration.

[0073] Furthermore, the resin sheet 1 contains an inorganic filler (C1) in the first resin composition, which includes nanofillers (C1-1) with a median diameter of 100 nm or less. The content of nanofillers (C1-1) is 5 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the resin component of the first resin composition. Therefore, the content and volume fraction of nanofillers (C1-1) in the first resin layer 31 are small. Moreover, it is preferable that the nanofillers (C1-1) include silica fillers. These features allow for a reduction in thermal resistance while restricting the movement of ionic impurities in the resin sheet 1.

[0074] Thus, the resin sheet 1 can restrict the movement of ionic impurities within it, thereby suppressing the occurrence of ion migration. Consequently, the insulation reliability of the resin sheet 1 and the laminate 10 formed from the resin sheet 1 can be improved.

[0075] The resin sheet 1 contains an inorganic filler (C2) which includes a thermally conductive filler (C2-1) with a thermal conductivity of 10 W / (m·K) or more, in the second resin composition that forms the second resin layer 32. The content of the thermally conductive filler (C2-1) is 80% by mass or more and 97% by mass or less of the total amount of the second resin composition. Furthermore, in the resin sheet 1, the ratio of the thickness of the first resin layer 31 to the thickness of the second resin layer 32 is less than 10%. In other words, the proportion of the second resin layer 32 that can reduce the thermal resistance is large relative to the entire resin sheet 1.

[0076] Furthermore, it is preferable that the resin sheet 1 includes a thermal conductive filler (C2-1) comprising a first thermal conductive filler and a second thermal conductive filler (C2-2) having a median diameter smaller than that of the first thermal conductive filler. This allows the thermal conductive fillers (C2-1) in the second resin composition to be in greater thermal contact with each other.

[0077] Thus, the resin sheet 1 includes a second resin layer 32 in which thermal resistance is reduced due to thermal contact between thermally conductive fillers (C2-1). Furthermore, the proportion of the second resin layer 32 in the resin sheet 1 is large. Therefore, the thermal resistance of the resin sheet 1 and the laminate 10 formed from the resin sheet 1 can be reduced.

[0078] As described above, the resin sheet 1 according to the embodiment can achieve both low thermal resistance and high insulation reliability. Furthermore, by using the resin sheet 1 as a build-up material, for example, by stacking the resin sheet 1 on a core material 14 such as a wiring board and heating and pressurizing it, a laminate 10 that can achieve both low thermal resistance and high insulation reliability can be easily manufactured.

[0079] 2.2 Laminate The laminate 10 according to this embodiment has thickness in the Z-axis direction and is plate-shaped, extending in the X-axis and Y-axis directions (see Figure 2). The laminate 10 comprises a support 12, a first insulating layer 131, and a second insulating layer 132. The first insulating layer 131 and the second insulating layer 132 are sometimes collectively referred to as the insulating layer 13.

[0080] 〔composition〕 (Support) Support 12 corresponds to support 2 of resin sheet 1. Therefore, the preferred material and other details of support 12 are the same as those of support 2 of resin sheet 1 described above. For this reason, the description of support 12 may be omitted as appropriate.

[0081] (First insulating layer) The first insulating layer 131 corresponds to the first resin layer 31 of the cured resin sheet 1. The first insulating layer 131 differs from the first resin layer 31 only in that it does not contain the semi-cured material of the first resin composition. Therefore, the preferred material, preferred numerical range, and other details of the first insulating layer 131 are the same as those of the first resin layer 31 of the resin sheet 1 described above. For this reason, the description of the first insulating layer 131 may be omitted as appropriate.

[0082] The first insulating layer 131 is superimposed on the support 12. Specifically, the first insulating layer 131 is superimposed on one side of the support 12 (the side in the negative Z-axis direction). The first insulating layer 131 may also be superimposed on and bonded to the support 12.

[0083] The thickness ratio of the first insulating layer 131 is less than 10% of the thickness of the second insulating layer 132. This can reduce the thermal resistance of the laminate 10.

[0084] The thickness of the first insulating layer 131 is preferably 0.1 μm or more. In this case, the insulation reliability of the laminate 10 can be further improved. The thickness of the first insulating layer 131 is preferably less than 5.0 μm. In this case, the thermal resistance of the laminate 10 can be further reduced.

[0085] The first insulating layer 131 contains a cured product of the first resin composition. The first resin composition contains an epoxy resin (A1), a curing agent (B1), and an inorganic filler (C1) containing a nanofiller (C1-1) having a median diameter of 100 nm or less.

[0086] The content of nanofiller (C1-1) is 5 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the resin component of the first resin composition. Therefore, the first insulating layer 131 can be formed thinly and uniformly. In addition, the moldability of the laminate 10 can be improved and the thermal resistance can be reduced.

[0087] The nanofiller (C1-1) preferably contains silica filler. In this case, the laminate 10 can be adjusted to the desired moldability.

[0088] It is more preferable that the inorganic filler (C1) contains only nanofiller (C1-1). In this case, the thermal resistance can be particularly reduced while the decrease in the insulation reliability of the laminate 10 is particularly suppressed.

[0089] The first resin composition may further contain elastomer (D1). When elastomer (D1) is included, the elastomer (D1) content is preferably 10% by mass or more and 95% by mass or less of the total amount of the first resin composition. Within this range, the fluidity of the first resin composition can be suppressed when molding the laminate 10, and the first insulating layer 131 can be adjusted to a suitable thickness.

[0090] (Second insulating layer) The second insulating layer 132 corresponds to the second resin layer 32 of the cured resin sheet 1. The second insulating layer 132 differs from the second resin layer 32 only in that it contains cured material of the second resin composition and does not contain uncured or semi-cured material of the second resin composition. Therefore, the preferred material, preferred numerical range, and other details of the second insulating layer 132 are the same as those of the second resin layer 32 of the resin sheet 1 described above. For this reason, the description of the second insulating layer 132 may be omitted as appropriate.

[0091] The second insulating layer 132 is superimposed on the first insulating layer 131. Specifically, the second insulating layer 132 is superimposed on the surface of the first insulating layer 131 opposite to the surface facing the support 12 (the surface in the negative Z-axis direction). The second insulating layer 132 may also be superimposed on and bonded to the first insulating layer 131.

[0092] The second insulating layer 132 contains a cured product of the second resin composition. The second resin composition contains an epoxy resin (A2), a curing agent (B2), and an inorganic filler (C2) containing a thermally conductive filler (C2-1) with a thermal conductivity of 10 W / (m·K) or more. As a result, the thermal resistance of the laminate 10 can be reduced.

[0093] The content of the thermally conductive filler (C2-1) is 80% by mass or more and 97% by mass or less of the total amount of the second resin composition. If the content is 80% by mass or more, the thermal resistance of the laminate 10 may be reduced. If the content is 97% by mass or less, the increase in viscosity of the second resin composition may be suppressed and the fluidity may be improved. Therefore, the thickness of the second insulating layer 132 can be formed uniformly.

[0094] The thermally conductive filler (C2-1) preferably includes at least one selected from the group consisting of magnesium oxide filler, aluminum nitride filler, and aluminum oxide filler. In this case, the thermal resistance of the laminate 10 can be further reduced.

[0095] Preferably, the thermally conductive filler (C2-1) includes a first thermally conductive filler and a second thermally conductive filler (C2-2) having a median diameter smaller than that of the first thermally conductive filler. This allows the second thermally conductive filler (C2-2), with its smaller median diameter, to be positioned between the first thermally conductive fillers (C2-1), which have larger median diameters, within the second resin composition, thereby increasing thermal contact between the thermally conductive fillers (C2-1). Consequently, the thermal resistance of the laminate 10 can be further reduced.

[0096] The median diameter of the first thermally conductive filler is preferably greater than 1 μm and less than or equal to 25 μm. The median diameter of the second thermally conductive filler (C2-2) is preferably between 0.05 μm and 1 μm. As a result, thermal contact between the thermally conductive fillers (C2-1) in the second resin composition can be further promoted, thereby further reducing the thermal resistance of the laminate 10.

[0097] (Core material) The laminate 10 may further comprise a core material 14 (see Figure 2). The core material 14 is not particularly limited, but examples include printed circuit boards. The core material 14 has thickness in the Z-axis direction and is plate-shaped, extending in the X-axis and Y-axis directions. The core material 14 comprises an insulating substrate 15 and a conductive layer 16.

[0098] <Insulating substrate> The insulating substrate 15 is an electrically insulating substrate. The insulating substrate 15 has thickness in the Z-axis direction and is plate-shaped, extending in the X-axis and Y-axis directions. The insulating substrate 15 is superimposed on the second insulating layer 132. Specifically, the insulating substrate 15 is superimposed on the side of the second insulating layer 132 opposite to the side facing the first insulating layer 131 (the side in the negative Z-axis direction). The insulating substrate 15 may also be superimposed on and bonded to the second insulating layer 132.

[0099] <Conductor layer> The conductor layer 16 includes at least one of a signal layer for transmitting electrical signals, a power layer for supplying power, and a ground layer for maintaining ground potential. The conductor layer 16 is bonded to the insulating substrate 15. Specifically, the conductor layer 16 is bonded to one side of the insulating substrate 15 (the side in the positive Z-axis direction). The conductor layer 16 may also be bonded to the other side of the insulating substrate 15 (the side in the negative Z-axis direction). In Figure 2, the conductor layer 16 is embedded within the second insulating layer 132. However, the conductor layer 16 is not in contact with the first insulating layer 131. Thus, the thickness of the conductor layer 16 is thinner than the thickness of the second insulating layer 132. The thickness of the conductor layer 16 is not particularly limited, but for example, it is 12 μm or more and 210 μm or less.

[0100] [Effects and Effects] The laminate 10 according to this embodiment can be easily manufactured by using the resin sheet 1 as a build-up material. That is, the laminate 10 can be manufactured from a resin sheet 1 that can achieve both low thermal resistance and high insulation reliability. Therefore, the laminate 10 can achieve both low thermal resistance and high insulation reliability. The method for manufacturing the laminate 10 is not particularly limited, but for example, it can be carried out by stacking the resin sheet 1 on a core material 14 such as a wiring board and heating and pressurizing it.

[0101] 3. Appearance As is clear from the embodiments described above, this disclosure includes the following aspects. In the following, reference numerals are enclosed in parentheses solely to indicate their correspondence with the embodiments.

[0102] The resin sheet (1) according to the first embodiment comprises a support (2), a first resin layer (31) containing a semi-cured or cured product of the first resin composition superimposed on the support (2), and a second resin layer (32) containing a second resin composition or a semi-cured product of the second resin composition superimposed on the first resin layer (31). The ratio of the thickness of the first resin layer (31) to the thickness of the second resin layer (32) is less than 10%. The first resin composition contains an epoxy resin (A1), a curing agent (B1), and an inorganic filler (C1) containing a nanofiller (C1-1) having a median diameter (the value of 50% of the cumulative value in the volume-based particle size distribution measured by laser diffraction and scattering) of 100 nm or less. The second resin composition contains an epoxy resin (A2), a curing agent (B2), and an inorganic filler (C2) containing a thermally conductive filler (C2-1) with a thermal conductivity of 10 W / (m·K) or higher. The content of the nanofiller (C1-1) is 5 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the resin component of the first resin composition. The content of the thermally conductive filler (C2-1) is 80% by mass or more and 97% by mass or less of the total amount of the second resin composition.

[0103] According to this embodiment, the resin sheet (1) can achieve both low thermal resistance and high insulation reliability.

[0104] In the second embodiment, the resin sheet (1) comprises, in the first embodiment, at least one thermally conductive filler (C2-1) selected from the group consisting of magnesium oxide filler, aluminum nitride filler, and aluminum oxide filler.

[0105] The resin sheet (1) according to the third embodiment, in the first or second embodiment, comprises a thermal conductive filler (C2-1) comprising a first thermal conductive filler and a second thermal conductive filler (C2-2) having a median diameter smaller than the median diameter of the first thermal conductive filler. The median diameter of the first thermal conductive filler is greater than 1 μm and 25 μm or less. The median diameter of the second thermal conductive filler (C2-2) is 0.05 μm or more and 1 μm or less.

[0106] The resin sheet (1) according to the fourth embodiment is, in any one of the first to third embodiments, the nanofiller (C1-1) includes silica filler.

[0107] The resin sheet (1) according to the fifth embodiment has a thickness of 0.1 μm or more and less than 5 μm in any one of the first to fourth embodiments.

[0108] The resin sheet (1) according to the sixth embodiment further contains an elastomer (D1) in any one of the first to fifth embodiments. The elastomer (D1) content is 10% by mass or more and 95% by mass or less with respect to the total amount of the first resin composition.

[0109] The laminate (10) according to the seventh embodiment comprises a support (12), a first insulating layer (131) containing a cured product of a first resin composition superimposed on the support (12), and a second insulating layer (132) containing a cured product of a second resin composition superimposed on the first insulating layer (131). The ratio of the thickness of the first insulating layer (131) to the thickness of the second insulating layer (132) is less than 10%. The first resin composition contains an epoxy resin (A1), a curing agent (B1), and an inorganic filler (C1) containing a nanofiller (C1-1) having a median diameter of 100 nm or less. The second resin composition contains an epoxy resin (A2), a curing agent (B2), and an inorganic filler (C2) containing a thermally conductive filler (C2-1) having a thermal conductivity of 10 W / (m·K) or more. The content of nanofiller (C1-1) is 5 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the resin component of the first resin composition. The content of thermally conductive filler (C2-1) is 80% by mass or more and 97% by mass or less of the total amount of the second resin composition.

[0110] According to this embodiment, the laminate (10) can achieve both low thermal resistance and high insulation reliability.

[0111] The laminate (10) according to the eighth embodiment, in the seventh embodiment, comprises at least one thermally conductive filler (C2-1) selected from the group consisting of magnesium oxide filler, aluminum nitride filler, and aluminum oxide filler.

[0112] The laminate (10) according to the ninth embodiment, in the seventh or eighth embodiment, comprises a thermal conductive filler (C2-1) comprising a first thermal conductive filler and a second thermal conductive filler (C2-2) having a median diameter smaller than that of the first thermal conductive filler. The median diameter of the first thermal conductive filler is greater than 1 μm and 25 μm or less. The median diameter of the second thermal conductive filler (C2-2) is 0.05 μm or more and 1 μm or less.

[0113] The laminate (10) according to the tenth embodiment includes, in any one of the seventh to ninth embodiments, a silica filler (C1-1).

[0114] In the laminate (10) according to the 11th embodiment, the thickness of the first insulating layer (131) is 0.1 μm or more and less than 5 μm, according to any one of the 7th to 10th embodiments.

[0115] The laminate (10) according to the twelfth embodiment further contains an elastomer (D1) in any one of the seventh to eleventh embodiments. The elastomer (D1) content is 10% by mass or more and 95% by mass or less, based on the total amount of the first resin composition. [Examples]

[0116] The present disclosure will be described in detail below with reference to examples. However, the present disclosure is not limited to the following examples.

[0117] 1. Preparation of the first resin composition and the second resin composition Each component was blended in the amounts shown in Tables 1 and 2, and methyl ethyl ketone was used as the solvent. The mixture was stirred and mixed to homogenize it, resulting in a first resin composition in a varnish state.

[0118] Similarly, each component was blended in the amounts shown in Tables 1 and 2, and methyl ethyl ketone was used as the solvent. The mixture was stirred and mixed to homogenize it, resulting in a varnish-like second resin composition with a solid content concentration of 90-99% by mass.

[0119] The details of the components used in the preparation of the first and second resin compositions are as follows.

[0120] (Epoxy resin) -Epoxy resin #1: Manufactured by Nippon Kayaku Co., Ltd., product name: EPPN502H, trisphenolmethane type epoxy resin, epoxy equivalent 158-178 g / eq. -Epoxy resin #2: Manufactured by DIC Corporation, product name: HP-7250, trisphenolmethane type epoxy resin, epoxy equivalent weight 150-180 g / eq.

[0121] (Hardening agent) -Hardening agent #1: Manufactured by UBE Corporation, product name: MEHC-7403H, biphenyl aralkyl type phenolic resin, hydroxyl group equivalent 132 g / eq. -Hardening agent #2: Manufactured by Gun-ei Chemical Industry Co., Ltd., product name: Resitopp ELP83H, long-chain alkyl liquid phenol resin, hydroxyl group equivalent 226 g / eq.

[0122] (Inorganic filler) - Nanofiller #1: Manufactured by Nissan Chemical Corporation, Product name: MEK-EC-2130Y, Methyl ethyl ketone dispersed silica filler, D50; 10-15nm - Nanofiller #2: Manufactured by Nissan Chemical Corporation, Product name: MEK-AC-4130Y, Methyl ethyl ketone dispersed silica filler, D50; 40~50nm - Thermally conductive filler #1:1: Manufactured by Nippon Steel Chemical & Material Co., Ltd., product name; AZ10-20, aluminum oxide filler, D50; 8~10μm - Thermally conductive filler #2: Manufactured by Ube Arterial Co., Ltd., Product name: RF-10CS, Magnesium oxide filler, D50; 5~10μm - Thermally conductive filler #3: Manufactured by Tokuyama Corporation, product name: HF-10c, aluminum nitride filler, D50: 16~22μm - Thermally conductive filler #4: Manufactured by Admatex Co., Ltd., product name: AO-502, aluminum oxide filler, D50; 0.2~0.3μm -Other inorganic fillers: Huber Engineered Materials, product name: Kemgard 501, calcium molybdate composite, D50: 3.7 μm.

[0123] (Elastomer) - Elastomer #1: Manufactured by Sekisui Chemical Co., Ltd., product name: Esrec KS-23Z, polyvinyl acetal resin.

[0124] (Other ingredients) - Curing accelerator: Manufactured by Shikoku Chemicals Co., Ltd., Product name: 2E4MZ, Chemical name: 2-ethyl-4-methylimidazole -Flame retardant: Manufactured by Fushimi Pharmaceutical Co., Ltd., product name: FP-100, phosphazene-based flame retardant (non-halogen flame retardant) - Coupling agent: Manufactured by Shin-Etsu Chemical Co., Ltd., Product name: KBM-4803, Silane coupling agent, Chemical name: 8-Glycidoxyoctyltrimethoxysilane - Dispersant: BYK-Chemie, product name; BYK-W903, wetting dispersant - Ion scavenger: Manufactured by Toagosei Co., Ltd., Product name: IXEPLAS-A1, Inorganic ion scavenger, Hydrotalcite-based - Heavy metal deactivator: Manufactured by ADEKA Corporation, Product name: ADEKA Stab CDA-10, Chemical name: N,N'-Bis「3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl」hydrazine - Flow regulator: Manufactured by Kusumoto Kasei Co., Ltd., product name: Disparon 3350EF, polyether ester type, phosphorus atom-free.

[0125] 2. Preparation of resin sheets First, a surface-treated electrolytic copper foil (manufactured by Furukawa Electric Industry Co., Ltd., product name "F2-WS", nominal thickness 35 μm, size 550 mm x 700 mm) was prepared as a support.

[0126] The first resin composition was applied to one side of the support and heated at 200°C for 3 to 5 minutes to dry and partially cure the first resin composition, forming a first resin layer with a thickness of 5 μm.

[0127] Next, the second resin composition was applied to the side of the first resin layer opposite to the side in contact with the support, and the second resin composition was heated and dried at 150°C for 2 to 5 minutes to form a second resin layer with a thickness of 100 μm. After the resin layer was formed, it was cut to a size of 515 mm × 340 mm to produce a resin sheet.

[0128] In Comparative Example 3, the amount of nanofiller added to the first resin composition was too large, preventing the formation of the first resin layer and thus the production of a resin sheet.

[0129] 3. Preparation of evaluation laminates The evaluation laminate 10A shown in Figure 3 was fabricated. The details of the fabrication procedure are described below.

[0130] First, a double-sided copper-clad laminate (manufactured by Panasonic Industries, Ltd., product name "R-1566S", thickness 400 μm, copper foil thickness 105 μm, size 515 mm x 340 mm) was prepared as the core material 14. This double-sided copper-clad laminate is a high heat-resistant halogen-free multilayer substrate material that has an insulating substrate 15 and copper foil on both surfaces of the insulating substrate 15. By etching the copper foil on both surfaces of this double-sided copper-clad laminate, a conductive layer 16 (16a, 16b) with the test pattern (comb pattern) shown in Figure 4 was formed in an XY plan view.

[0131] Next, the resin layers of the resin sheet prepared in "2. Preparation of Resin Sheet" were placed on top of both surfaces of the core material 14 and brought into contact with it. The resin layers (first resin layer and second resin layer) were cured by heating and pressurizing under the conditions of 200°C, 3MPa, and 60 minutes, forming an insulating layer 13 (first insulating layer 131 and second insulating layer 132). After the insulating layer 13 was formed, the outermost support layer was etched to form metal layers 12a and 12b, which have the same test pattern as the conductive layer 16 in an XY plan view, and an evaluation laminate 10A was prepared. In the case of Comparative Example 3, as mentioned above, a resin sheet could not be prepared, so an evaluation laminate 10A was not prepared.

[0132] 4. Evaluation (thermal resistance) The resin layer of the resin sheet prepared in "2. Preparation of Resin Sheet" was cured at 200°C for 60 minutes. The thermal resistance of this cured resin layer was measured using a thermal properties evaluation device (Siemens, model number "T3Ster DynTIM Tester") in accordance with ASTM D5470.

[0133] Furthermore, the thermal resistance index of the examples was calculated with the comparative example set to 100. If this index is 97 or less, it is judged as "good," indicating that the thermal resistance has been sufficiently reduced. Here, this index is based on Comparative Example 1 for Examples 1-3, and Comparative Example 2 for Examples 4 and 5.

[0134] The indices calculated from the measured thermal resistance are shown in Tables 1 and 2.

[0135] (Insulation reliability) The evaluation laminate 10A was placed in an environment of 85°C / 85%RH, and a voltage of 900V was applied between the outer metal layer 12a and the inner conductor layer 16a to measure the resistance of the insulating layer 13. From the start of voltage application, the resistance of the insulating layer 13 was 1 × 10⁻¹⁰. 7 The time it took for the resistance to drop below Ω was monitored. The results are shown in Tables 1 and 2. Note that the resistance value is 1 × 10⁻⁶. 7The time until the value becomes less than or equal to Ω is recorded as an actual value if it is 1500 hours or less, and as ">1500(h)" if it is more than 1500 hours.

[0136] [Table 1]

[0137] [Table 2]

[0138] In the evaluation of insulation reliability, the results of the evaluation laminates 10A in Examples 1-5 were comparable to those of Comparative Examples 1-2. On the other hand, in the evaluation of thermal resistance, the calculated index of the evaluation laminates 10A in Examples 1-3 was 97 or less compared to the result of Comparative Example 1, confirming a sufficient reduction in thermal resistance. Furthermore, the calculated index of the evaluation laminates 10A in Examples 4-5 was 97 or less compared to the result of Comparative Example 2, confirming a sufficient reduction in thermal resistance. Therefore, the evaluation laminates 10A in Examples 1-5 achieve both low thermal resistance and high insulation reliability. As mentioned above, Comparative Example 3 was not evaluated because it was not possible to produce the resin sheet. [Explanation of symbols]

[0139] 1. Resin sheet 2 Support 31 1st resin layer 32 Second resin layer 10 Laminate 12 Support 131 First insulating layer 132 Second insulating layer

Claims

1. The apparatus comprises a support, a first resin layer superimposed on the support and containing a semi-cured or cured product of a first resin composition, and a second resin layer superimposed on the first resin layer and containing a second resin composition or a semi-cured product of a second resin composition, The ratio of the thickness of the first resin layer to the thickness of the second resin layer is less than 10%. The first resin composition contains an epoxy resin (A1), a curing agent (B1), and an inorganic filler (C1) containing nanofillers (C1-1) with a median diameter (the 50% cumulative value in the volume-based particle size distribution measured by laser diffraction and scattering) of 100 nm or less. The second resin composition contains an epoxy resin (A2), a curing agent (B2), and an inorganic filler (C2) containing a thermally conductive filler (C2-1) having a thermal conductivity of 10 W / (m·K) or more. The content of the nanofiller (C1-1) is 5 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the resin component of the first resin composition. The content of the thermally conductive filler (C2-1) is 80% by mass or more and 97% by mass or less, based on the total amount of the second resin composition. Resin sheet.

2. The thermally conductive filler (C2-1) includes at least one selected from the group consisting of magnesium oxide filler, aluminum nitride filler, and aluminum oxide filler. The resin sheet according to claim 1.

3. The thermally conductive filler (C2-1) includes a first thermally conductive filler and a second thermally conductive filler (C2-2) having a median diameter smaller than the median diameter of the first thermally conductive filler. The median diameter of the first thermally conductive filler is greater than 1 μm and less than or equal to 25 μm. The median diameter of the second thermally conductive filler (C2-2) is 0.05 μm or more and 1 μm or less. The resin sheet according to claim 1.

4. The nanofiller (C1-1) contains silica filler, The resin sheet according to claim 1.

5. The thickness of the first resin layer is 0.1 μm or more and less than 5 μm. The resin sheet according to claim 1.

6. The first resin composition further contains an elastomer (D1), The content of the elastomer (D1) is 10% by mass or more and 95% by mass or less, based on the total amount of the first resin composition. The resin sheet according to claim 1.

7. The device comprises a support, a first insulating layer containing a cured product of a first resin composition superimposed on the support, and a second insulating layer containing a cured product of a second resin composition superimposed on the first insulating layer. The ratio of the thickness of the first insulating layer to the thickness of the second insulating layer is less than 10%. The first resin composition contains an epoxy resin (A1), a curing agent (B1), and an inorganic filler (C1) containing nanofillers (C1-1) with a median diameter (the 50% cumulative value in the volume-based particle size distribution measured by laser diffraction and scattering) of 100 nm or less. The second resin composition contains an epoxy resin (A2), a curing agent (B2), and an inorganic filler (C2) containing a thermally conductive filler (C2-1) having a thermal conductivity of 10 W / (m·K) or more. The content of the nanofiller (C1-1) is 5 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the resin component of the first resin composition. The content of the thermally conductive filler (C2-1) is 80% by mass or more and 97% by mass or less, based on the total amount of the second resin composition. Laminated structure.

8. The thermally conductive filler (C2-1) includes at least one selected from the group consisting of magnesium oxide filler, aluminum nitride filler, and aluminum oxide filler. The laminate according to claim 7.

9. The thermally conductive filler (C2-1) includes a first thermally conductive filler and a second thermally conductive filler (C2-2) having a median diameter smaller than the median diameter of the first thermally conductive filler. The median diameter of the first thermally conductive filler is greater than 1 μm and less than or equal to 25 μm. The median diameter of the second thermally conductive filler (C2-2) is 0.05 μm or more and 1 μm or less. The laminate according to claim 7.

10. The nanofiller (C1-1) contains silica filler, The laminate according to claim 7.

11. The thickness of the first insulating layer is 0.1 μm or more and less than 5 μm. The laminate according to claim 7.

12. The first resin composition further contains an elastomer (D1), The content of the elastomer (D1) is 10% by mass or more and 95% by mass or less, based on the total amount of the first resin composition. The laminate according to claim 7.

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