Laminate and resin-coated metal foil

Abstract

A multilayer body (1) is provided with a metal layer (2), a first insulating layer (31), and a second insulating layer (32) containing a cured product formed from a resin composition. The ratio of the thickness (T1) of the first insulating layer (31) to the thickness (T2) of the second insulating layer (32) is less than 10%. The resin composition includes an epoxy resin, a hardener, a fluidity regulator, and a thermally conductive filler. The flowability regulating agent comprises a polyether ester type flowability regulating agent. The content of the thermally conductive filler is 84 mass% to 97 mass% with respect to the total mass of the resin composition. In analysis by laser diffraction / scattering, the thermally conductive filler results in a volume-based particle size distribution having at least two peaks in a particle size range of 0.05 [mu] m to 25 [mu] m. The first insulating layer (31) does not contain an inorganic filler, or contains an inorganic filler that is less than the content of the thermally conductive filler contained in the second insulating layer (32).

Description

Technical Field

[0001] The present disclosure generally relates to laminates and resin-coated metal foils, and more particularly to: laminates including a metal layer and an insulating layer; and resin-coated metal foils including a metal foil and a resin layer. Background Art

[0002] Patent Document 1 discloses an epoxy resin composition for a heat conductive material. The epoxy resin composition for a heat conductive material contains an epoxy resin, a curing agent or a curing accelerator, and an inorganic filler (heat conductive filler). The epoxy resin is characterized in that it contains a benzophenanthrene skeleton.

[0003] The more heat conductive filler is filled in the resin composition, the better the thermal conductivity of the insulating layer formed from the resin composition can be, but the lower the insulation reliability of the insulating layer thus formed may be. The present inventors attribute this to the following reasons. The first reason is that ionic impurities migrate along the surface of the heat conductive filler. The second reason is that voids are left in the insulating layer, between the insulating layers, and between the insulating layer and the conductive layer. Patent Document 1 seemingly attempts to ensure thermal conductivity and insulation through the heat conductive filler itself (paragraph

[0051] ).

[0004] However, these two reasons cannot be solved by the heat conductive filler itself.

[0005] Citation List

[0006] Patent Documents

[0007] Patent Document 1: JP 2017-008153 A Summary of the Invention

[0008] An object of the present disclosure is to provide a laminate and a resin-coated metal foil capable of forming an insulating layer having high thermal conductivity and high insulation reliability.

[0009] A laminate according to one aspect of the present disclosure includes: a metal layer; a first insulating layer stacked on the metal layer; and a second insulating layer stacked on the first insulating layer and including a cured product of a resin composition. A ratio of a thickness of the first insulating layer to a thickness of the second insulating layer is less than 10%. The resin composition contains an epoxy resin (A), a curing agent (B), a fluidity regulator (C), and a heat conductive filler (D) having a heat conductivity of 10 W / m·K or more. The fluidity regulator (C) includes at least one of a polyether ester type fluidity regulator (C1) that does not contain a phosphorus atom or a polyether ester phosphate-type fluidity regulator (C2). Based on a total mass of the resin composition, a content of the heat conductive filler (D) is 84% by mass or more and 97% by mass or less. In a volume particle size distribution measured by a laser scattering / diffraction method, the heat conductive filler (D) has at least two peaks in a particle size range of 0.05 μm or more and 25 μm or less. The first insulating layer does not contain an inorganic filler, or contains an inorganic filler having a content lower than a content of the heat conductive filler (D) in the second insulating layer.

[0010] A resin-coated metal foil according to one aspect of the present disclosure includes: a metal foil; a first resin layer stacked on the metal foil; and a second resin layer stacked on the first resin layer and including a resin composition or a semi-cured product of the resin composition. A ratio of a thickness of the first resin layer to a thickness of the second resin layer is less than 10%. The resin composition contains an epoxy resin (A), a curing agent (B), a fluidity regulator (C), and a heat conductive filler (D) having a heat conductivity of 10 W / m·K or more. The fluidity regulator (C) includes at least one of a polyether ester type fluidity regulator (C1) that does not contain a phosphorus atom or a polyether ester phosphate-type fluidity regulator (C2). Based on a total mass of the resin composition, a content of the heat conductive filler (D) is 84% by mass or more and 97% by mass or less. In a volume particle size distribution measured by a laser scattering / diffraction method, the heat conductive filler (D) has at least two peaks in a particle size range of 0.05 μm or more and 25 μm or less. The first resin layer is thermoplastic or cured. The first resin layer does not contain an inorganic filler, or contains an inorganic filler having a content lower than a content of the heat conductive filler (D) in the second resin layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Figure 1 is a schematic cross-sectional view of a laminate according to an embodiment of the present disclosure;

[0012] ​​Figure 2 Figure 2 is a schematic cross-sectional view of a resin-coated metal foil according to an embodiment of the present disclosure;

[0013] Figure 3 Figure 3 is a schematic cross-sectional view of a test laminate; and

[0014] Figure 4 Figure 4 is a schematic plan view of a test pattern. DETAILED DESCRIPTION

[0015] 1. Overview

[0016] As described above, the more the resin composition is filled with the thermal conductive filler, the better the thermal conductivity of the insulating layer formed from such a resin composition can be, but the insulation reliability of the insulating layer thus formed may be lower.

[0017] The first reason for the reduction in insulation reliability is the migration of ionic impurities along the surface of the thermal conductive filler. Therefore, means for restricting the migration of ionic impurities are required.

[0018] On the other hand, the second reason for the reduction in insulation reliability is the presence of voids in the insulating layer, between the insulating layers, and between the insulating layer and the conductive layer. For example, when the build-up process is used to increase the number of layers of a printed circuit board, voids may be left if the insulating layer is not formed without gaps between adjacent conductors. When the resin composition is highly filled with the thermal conductive filler to ensure thermal conductivity, voids are more likely to be left. In contrast, when the viscosity is reduced to ensure the fluidity of the resin composition, the insulating layer is more likely to have an uneven thickness. When a single insulating layer has an uneven thickness, this thickness non-uniformity may accumulate in the case of the build-up process, which also has the risk of leaving voids.

[0019] Therefore, in view of these two reasons for the reduction in insulation reliability, the present inventors conducted intensive studies, and as a result, developed the laminate 1 including an insulating layer having high insulation reliability and high thermal conductivity.

[0020] That is, the laminate 1 according to the present embodiment includes: a metal layer 2; a first insulating layer 31 laminated on the metal layer 2; and a second insulating layer 32 laminated on the first insulating layer 31 and containing a cured product of the resin composition.

[0021] The ratio of the thickness T1 of the first insulating layer 31 to the thickness T2 of the second insulating layer 32 is less than 10% (T1 / T2 < 0.1).

[0022] ​​The resin composition contains an epoxy resin (A), a curing agent (B), a fluidity regulator (C), and a heat-conductive filler (D) having a heat conductivity of 10 W / m·K or higher.

[0023] The fluidity regulator (C) contains at least one of a polyether ester type fluidity regulator (C1) that does not contain a phosphorus atom or a polyether ester phosphate type fluidity regulator (C2).

[0024] Based on the total mass of the resin composition, the content of the heat-conductive filler (D) is 84% by mass or more and 97% by mass or less. Even when the heat-conductive filler (D) is filled at a high content as in this case, the fluidity regulator (C) can impart appropriate fluidity to the resin composition during molding. It is presumed that this suppresses the formation of voids and improves the insulation reliability of the insulating layer 3 (especially the second insulating layer 32).

[0025] In the volume particle size distribution measured by the laser scattering / diffraction method, the heat-conductive filler (D) has at least two peaks in the particle size range of 0.05 μm or more and 25 μm or less.

[0026] The first insulating layer 31 does not contain an inorganic filler, or contains an inorganic filler in an amount lower than the content of the heat-conductive filler (D) in the second insulating layer 32.

[0027] The first insulating layer 31 is present between the metal layer 2 and the second insulating layer 32, thereby suppressing the migration of ionic impurities between the metal layer 2 and the second insulating layer 32. This improves the insulation reliability of the insulating layer 3 (the first insulating layer 31 and the second insulating layer 32).

[0028] In addition, the content of the heat-conductive filler (D) in the second insulating layer 32 is higher than the content of the heat-conductive filler (D) in the first insulating layer 31. Further, the thickness T2 of the second insulating layer 32 is more than 10 times the thickness T1 of the first insulating layer 31.

[0029] Therefore, this embodiment enables the formation of an insulating layer 3 having high thermal conductivity and high insulation reliability.

[0030] 2. Detailed description

[0031] The laminate 1 and the resin-coated metal foil 10 according to the present embodiment will be described with reference to the accompanying drawings. Note that the drawings are schematic diagrams, and thus, the dimensions, thicknesses, and other properties of the respective constituent elements shown in those drawings are not always in proportion to the actual dimensions, thicknesses, and other properties. The arrows indicating the respective directions in the drawings do not define the directions of the laminate 1 and the resin-coated metal foil 10 during use, but are shown only for facilitating the understanding of the description and do not have any substantial meaning. Note that the X-axis, Y-axis, and Z-axis are perpendicular to each other. In the following description, the view along the Z-axis is referred to as the XY plan view.

[0032] (1) Laminate

[0033] First, the laminate 1 according to the present embodiment will be described. The laminate 1 is used, for example, in the manufacture of printed circuit boards.

[0034] As Figure 1 shown, the laminate 1 has a plate shape with a certain thickness in the Z-axis direction and extending in the X-axis and Y-axis directions. The laminate 1 includes a metal layer 2, a first insulating layer 31, and a second insulating layer 32. The first insulating layer 31 and the second insulating layer 32 may be collectively referred to as the "insulating layer 3". The laminate 1 may further include a core material 7.

[0035] <Metal layer>

[0036] The metal layer 2 may be formed of a metal foil, or may be formed by plating or vapor deposition. Examples of the metal forming the metal layer 2 include, but are not particularly limited to, copper, stainless steel, nickel, and nickel-chromium alloy. Examples of the thickness of the metal layer 2 are, but are not particularly limited to, greater than or equal to 5 μm and less than or equal to 35 μm. Note that one or more unnecessary portions of the metal layer 2 may be removed by etching, for example, as needed.

[0037] <First insulating layer>

[0038] The first insulating layer 31 is stacked on the metal layer 2. Specifically, the first insulating layer 31 is stacked on one surface (the surface in the negative direction of the Z-axis) of the metal layer 2 and is bonded to that surface.

[0039] The first insulating layer 31 is a layer formed of a resin composition having electrical insulating properties. The resin composition is not limited to a specific resin composition. The resin composition may be a resin composition containing a thermoplastic resin, or may be a resin composition containing a thermosetting resin.

[0040] Examples of the resin composition containing a thermoplastic resin include, but are not particularly limited to, a resin composition containing a polyamideimide resin.

[0041] Examples of the resin composition containing a thermosetting resin include, but are not particularly limited to, resin compositions containing at least one of an epoxy resin, a curing agent (e.g., a phenolic resin), a catalyst, a flame retardant, or a flexible component. The epoxy resin, the curing agent, the catalyst, and the flame retardant are the same as the epoxy resin (A), the curing agent (B), the catalyst, and the flame retardant of the second insulating layer 32, respectively, which will be described later. Examples of the flexible component include, but are not particularly limited to, an epoxy-modified acrylic resin.

[0042] Note that the first insulating layer 31 does not contain an inorganic filler, or the first insulating layer 31 contains an inorganic filler in an amount lower than the amount of the heat-conductive filler (D) in the second insulating layer 32. Note that in this specification, "inorganic filler" means a broad inorganic filler including the heat-conductive filler (D). That is, the heat-conductive filler (D) has a thermal conductivity of 10 W / m·K or higher, but the "inorganic filler" includes a non-heat-conductive filler having a thermal conductivity lower than 10 W / m·K.

[0043] The ratio of the thickness T1 of the first insulating layer 31 to the thickness T2 of the second insulating layer 32 is less than 10% (T1 / T2 < 0.1). This improves the thermal conductivity of the insulating layer 3. This particularly improves the thermal conductivity in the thickness direction defined for the insulating layer 3.

[0044] <Second Insulating Layer>

[0045] The second insulating layer 32 is stacked on the first insulating layer 31. Specifically, the second insulating layer 32 is stacked on one surface (the surface in the negative direction of the Z axis) of the first insulating layer 31 and bonded to the surface.

[0046] The second insulating layer 32 is an electrically insulating layer. The second insulating layer 32 contains a cured product of a resin composition. The resin composition contains an epoxy resin (A), a curing agent (B), a fluidity regulator (C), and a heat-conductive filler (D) having a thermal conductivity of 10 W / m·K or higher. The resin composition may further contain other components. Examples of the other components include, but are not particularly limited to: a catalyst, a flame retardant, a coupling agent, a dispersant, an inorganic filler, a metal deactivator, and an ion scavenger. Each component will be described in turn below.

[0047] <<Epoxy Resin (A)>>

[0048] The epoxy resin (A) has the property of curing by heating. Therefore, the epoxy resin (A) can impart thermosetting properties to the resin composition. The epoxy resin (A) is a compound in which each molecule contains at least one epoxy group. The epoxy resin (A) preferably contains two or more epoxy groups per molecule.

[0049] Examples of the epoxy resin (A) include, but are not particularly limited to: triphenylmethane epoxy resin, naphthalene epoxy resin, biphenyl aralkyl epoxy resin, biphenyl epoxy resin, and dicyclopentadiene epoxy resin.

[0050] Triphenylmethane epoxy resin is particularly preferred. Each molecule of triphenylmethane epoxy resin has three epoxy groups each having a phenylmethane skeleton. Therefore, triphenylmethane epoxy resin has a high functional group (epoxy group) density, and thus can increase the glass transition temperature (Tg) of the cured product of the resin composition.

[0051] <<Curing agent (B)>>

[0052] The curing agent (B) contains at least one of a phenolic resin and dicyandiamide.

[0053] The phenolic resin is a prepolymer that can react with the epoxy resin (A). The phenolic resin is a condensation reaction product of a phenol and an aldehyde.

[0054] Examples of the phenolic resin include, but are not particularly limited to: biphenyl aralkyl phenolic resin, phenyl aralkyl phenolic resin, novolak phenolic resin, cresol novolak phenolic resin, bisphenol A novolak phenolic resin, naphthol phenolic resin, tetraphenol phenolic resin, and phosphorus denatured phenol resin.

[0055] Biphenyl aralkyl phenolic resin is particularly preferred. The biphenyl aralkyl phenolic resin can impart flame retardancy, heat resistance, and adhesiveness to the cured product of the resin composition.

[0056] The content of the curing agent (B) (i.e., the ratio of the epoxy resin (A) to the curing agent (B)) is preferably in the range of greater than or equal to 0.3 to less than or equal to 1.3, more preferably greater than or equal to 0.4 to less than or equal to 1.0, in terms of the equivalent ratio of the phenolic resin (B) / epoxy resin (A). Since the equivalent ratio is greater than or equal to 0.3, the glass transition temperature (Tg) is not likely to decrease, and thus insufficient curing is not likely to occur. On the other hand, since the equivalent ratio is less than or equal to 1.3, an increase in polar groups (such as hydroxyl groups) is suppressed, and thus, for example, the formation of stains when forming pores in the insulating layer 3 can be suppressed.

[0057] <<Flowability regulator (C)>>

[0058] The flowability regulator (C) is a component that can adjust the flowability of the resin composition during molding. The flowability regulator (C) contains at least one of a phosphorus atom-free polyether ester type flowability regulator (C1) or a polyether ester phosphate type flowability regulator (C2).

[0059] Here, the phosphorus atom-free polyether ester type fluidity regulator (C1) is particularly effective in a resin system combining an epoxy resin (A) and a phenolic resin. That is to say, in such a resin system, even when a heat conductive filler (D) is filled at a high content, the phosphorus atom-free polyether ester type fluidity regulator (C1) can impart appropriate fluidity to the resin composition during molding.

[0060] On the other hand, the polyether ester phosphate type fluidity regulator (C2) is particularly effective in a resin system combining an epoxy resin (A) and dicyandiamide. That is to say, in such a resin system, even when a heat conductive filler (D) is filled at a high content, the polyether ester phosphate type fluidity regulator (C2) can impart appropriate fluidity to the resin composition during molding.

[0061] The fluidity regulator (C) is in a liquid form at 25 °C and is non-ionic. This can make the thickness T2 of the second insulating layer 32 uniform. The thickness T2 of the second insulating layer 32 is greater than 10 times the thickness T1 of the first insulating layer 31, which is also beneficial to making the thickness (T1 + T2) of the insulating layer 3 uniform.

[0062] The phosphorus atom-free polyether ester type fluidity regulator (C1) has multiple ether structures, multiple ester structures, and multiple carboxyl groups in each molecule. The phosphorus atom-free polyether ester type fluidity regulator (C1) as described above is obtained, for example, by reacting a polyol having two to six hydroxyl groups with a phosphorus group-introducing substance or a carboxyl group-introducing substance at a molar ratio of hydroxyl group to phosphorus group-introducing substance or carboxyl group-introducing substance of 3:1 to 1:1. The phosphorus atom-free polyether ester type fluidity regulator (C1) obtained in this way can inhibit the excessive increase or decrease in the viscosity of the resin composition during molding. This can make the thickness T2 of the second insulating layer 32 more uniform. Therefore, it is also beneficial to make the thickness (T1 + T2) of the insulating layer 3 more uniform.

[0063] Based on 100 parts by mass of the heat conductive filler (D), the content of the fluidity regulator (C) is greater than or equal to 0.005 parts by mass and less than or equal to 0.5 parts by mass, more preferably greater than or equal to 0.008 parts by mass and less than or equal to 0.4 parts by mass, and even more preferably greater than or equal to 0.01 parts by mass and less than or equal to 0.3 parts by mass. The content of the fluidity regulator (C) is greater than or equal to 0.005 parts by mass, so the effect of the fluidity regulator (C) can be exerted. Note that when the content of the fluidity regulator (C) is greater than 0.5 parts by mass, the effect of the fluidity regulator (C) may be saturated. This can make the thickness T2 of the second insulating layer 32 more uniform. Therefore, it is also beneficial to make the thickness (T1 + T2) of the insulating layer 3 more uniform.

[0064] <<Heat Conductive Filler (D)>>

[0065] The thermal conductive filler (D) is an aggregate of thermal conductive particles. The thermal conductivity of the thermal conductive filler (D) is higher than or equal to 10 W / m·K. The higher the thermal conductivity of the thermal conductive filler (D), the better the thermal conductivity, which is preferable, but the actual upper limit is lower than or equal to 300 W / m·K. The thermal conductive filler (D) preferably contains at least one filler selected from the group consisting of a magnesium oxide filler, an aluminum nitride filler, and an aluminum oxide filler. This enables the second insulating layer 32 to have improved thermal conductivity compared to the case where these fillers are not included. The thickness T2 of the second insulating layer 32 is more than 10 times the thickness T1 of the first insulating layer 31, and thus, the insulating layer 3 also easily has improved thermal conductivity.

[0066] Based on the total mass of the resin composition, the content of the thermal conductive filler (D) is greater than or equal to 84% by mass and less than or equal to 97% by mass, preferably greater than or equal to 85% by mass and less than or equal to 96% by mass, more preferably greater than or equal to 87% by mass and less than or equal to 94% by mass. The content of the thermal conductive filler (D) being greater than or equal to 84% by mass enables the second insulating layer 32 to have improved thermal conductivity. Thus, the insulating layer 3 also easily has improved thermal conductivity. On the other hand, the content of the thermal conductive filler (D) is less than or equal to 97% by mass, and thus, a decrease in the fluidity or an excessive increase in the viscosity of the resin composition during molding can be suppressed.

[0067] In the volume particle size distribution (frequency distribution) measured by the laser scattering / diffraction method, the thermal conductive filler (D) has at least two peaks in the particle size range of greater than or equal to 0.05 μm and less than or equal to 25 μm. This enables the particles of the thermal conductive filler (D) to be closer to each other in the second insulating layer 32.

[0068] Here, the particle size distribution is measured by the laser scattering / diffraction method. The particle size distribution is shown as a frequency distribution or an integral distribution (cumulative distribution). In this specification, the "integral distribution" represents the distribution of the cumulative undersize (integrated undersize distribution).

[0069] The frequency distribution is a distribution in which the horizontal axis represents the particle size and the vertical axis represents the ratio (by volume) of the particles having the corresponding particle size to the total particle volume. The horizontal axis can be shown in logarithmic display.

[0070] On the other hand, the integral distribution (distribution of the cumulative undersize) is a distribution in which the horizontal axis represents the particle size and the vertical axis represents the ratio (by volume) of the particles less than or equal to a certain particle size to the total particle volume. The horizontal axis can be shown in logarithmic display.

[0071] Preferably, the thermal conductive filler (D) includes: a first thermal conductive filler (D1); and a second thermal conductive filler (D2) having an average particle diameter smaller than that of the first thermal conductive filler (D1). This enables the particles of the first thermal conductive filler (D1) in the second insulating layer 32 to be in thermal contact with each other via the particles of the second thermal conductive filler (D2). This enables the second insulating layer 32 to have further improved thermal conductivity. As a result, the insulating layer 3 also easily has improved thermal conductivity. Note that in this specification, "average particle diameter" refers to the 50% diameter (D50 (median diameter)) in the integral distribution (distribution of the cumulative upper limit of particle size).

[0072] The average particle diameter of the first thermal conductive filler (D1) is preferably greater than 1 μm and less than or equal to 25 μm, more preferably greater than or equal to 4 μm and less than or equal to 20 μm. On the other hand, the average particle diameter of the second thermal conductive filler (D2) is preferably greater than or equal to 0.05 μm and less than or equal to 1 μm, more preferably greater than or equal to 0.1 μm and less than or equal to 0.4 μm. This further promotes the thermal contact between the particles of the first thermal conductive filler (D1) in the second insulating layer 32 via the particles of the second thermal conductive filler (D2). This enables the second insulating layer 32 to have further improved thermal conductivity. As a result, the insulating layer 3 also easily has improved thermal conductivity.

[0073] Preferably, in the volume particle size distribution (frequency distribution) measured by the laser scattering / diffraction method, the thermal conductive filler (D) has at least one peak in the particle size range greater than 1 μm and less than or equal to 25 μm, and at least one peak in the particle size range greater than or equal to 0.05 μm and less than or equal to 1 μm. This enables the particles of the thermal conductive filler (D) to be closer to each other in the second insulating layer 32. This enables the second insulating layer 32 to have further improved thermal conductivity. As a result, the insulating layer 3 also easily has improved thermal conductivity.

[0074] <<Other>>

[0075] Examples of the catalyst include, but are not particularly limited to, imidazole compounds such as 2-ethyl-4-methylimidazole. The resin composition contains the catalyst, whereby the curing reaction of the resin composition during molding can be promoted.

[0076] Examples of the flame retardant include, but are not particularly limited to, phosphorus-based flame retardants, halogen-based flame retardants, and inorganic flame retardants. The resin composition contains the flame retardant, and thus, the insulating layer 3 can be made flame retardant. The phosphorus-based flame retardant is halogen-free and is therefore preferred.

[0077] Examples of the coupling agent include, but are not particularly limited to, silane coupling agents, such as 8-glycidoxy octyltrimethoxysilane. Since the resin composition contains the coupling agent, the adhesion between the first insulating layer 31 and the second insulating layer 32 and the adhesion between the second insulating layer 32 and the conductive layer 8 (see Figure 1 ) can be improved.

[0078] Examples of the dispersant include, but are not particularly limited to, wetting dispersants. Since the resin composition contains the dispersant, the heat-conductive filler (D) can be uniformly dispersed in the second insulating layer 32.

[0079] Examples of the inorganic filler include, but are not particularly limited to: molybdenum compound fillers, silica fillers, aluminum hydroxide fillers, magnesium hydroxide fillers, talc fillers, clay fillers, and mica fillers.

[0080] Examples of the metal deactivator include, but are not particularly limited to: hydrazide derivatives, oxalic acid derivatives, and salicylic acid derivatives. Since the resin composition contains the metal deactivator, the metal deactivator forms a complex with the active metal ions (such as copper ions) that promote oxidative degradation. This inhibits the degradation of the second insulating layer 32.

[0081] Examples of the ion scavenger include, but are not particularly limited to, hydrotalcite. Since the resin composition contains the ion scavenger, the ion scavenger captures ionic impurities. This inhibits ion migration. Therefore, the insulation reliability of the second insulating layer 32 is ensured.

[0082] <Core material>

[0083] As described above, the laminate 1 does not necessarily include the core material 7. Examples of the core material 7 include, but are not particularly limited to, printed circuit boards. The core material 7 is in the shape of a plate having a certain thickness in the Z-axis direction and extending in the X-axis and Y-axis directions. The core material 7 includes an insulating substrate 9 and a conductive layer 8.

[0084] <<Insulating substrate>>

[0085] The insulating substrate 9 is an electrically insulating substrate. The insulating substrate 9 is in the shape of a plate having a certain thickness in the Z-axis direction and extending in the X-axis and Y-axis directions. The insulating substrate 9 is stacked on the second insulating layer 32. Specifically, the insulating substrate 9 is stacked on one surface (the surface in the negative direction of the Z-axis) of the second insulating layer 32 and bonded to this surface.

[0086] <<Conductive layer>>

[0087] The conductive layer 8 includes at least one of a signal layer for transmitting an electrical signal, a power supply layer for supplying power, or a ground layer for obtaining a ground potential.

[0088] The conductive layer 8 is bonded to the insulating substrate 9. Specifically, in the present embodiment, the conductive layer 8 is bonded to one surface of the insulating substrate 9 (the surface in the positive direction of the Z-axis). The conductive layer 8 may be bonded to the other surface of the insulating substrate 9 (the surface in the negative direction of the Z-axis).

[0089] In the present embodiment, the conductive layer 8 is embedded in the second insulating layer 32. Note that the conductive layer 8 does not contact the first insulating layer 31. Therefore, the thickness of the conductive layer 8 is less than the thickness T2 of the second insulating layer 32. For example, the thickness of the conductive layer 8 is but not specifically limited to being greater than or equal to 12 μm and less than or equal to 210 μm.

[0090] <Function and Advantage>

[0091] In the present embodiment, the first insulating layer 31 does not contain an inorganic filler, or contains an inorganic filler with a content lower than the content of the heat-conductive filler (D) in the second insulating layer 32. This inhibits the migration of ionic impurities within the first insulating layer 31.

[0092] Even when ionic impurities are present in the second insulating layer 32, the first insulating layer 31 is present between the metal layer 2 and the second insulating layer 32, thereby inhibiting the migration of ionic impurities between the metal layer 2 and the second insulating layer 32. This improves the insulation reliability of the insulating layer 3 (the first insulating layer 31 and the second insulating layer 32). For example, in Figure 1 a short circuit between the metal layer 2 and the conductive layer 8 is inhibited.

[0093] On the other hand, the content of the heat-conductive filler (D) in the second insulating layer 32 is higher than the content of the heat-conductive filler (D) in the first insulating layer 31. In addition, the thickness T2 of the second insulating layer 32 is more than 10 times the thickness T1 of the first insulating layer 31. Therefore, the insulating layer 3 (the first insulating layer 31 and the second insulating layer 32) has improved thermal conductivity.

[0094] Therefore, the present embodiment enables the formation of the insulating layer 3 having high thermal conductivity and high insulation reliability.

[0095] (2) Resin-Coated Metal Foil

[0096] Now, the resin-coated metal foil 10 according to the present embodiment will be described. The resin-coated metal foil 10 is used, for example, in the manufacture of printed circuit boards. Specifically, the resin-coated metal foil 10 is used when the number of layers of a printed circuit board is increased by a lamination method.

[0097] As Figure 2As shown, the resin-coated metal foil 10 is in the shape of a sheet having a certain thickness in the Z-axis direction and extending in the X-axis and Y-axis directions. The resin-coated metal foil 10 includes a metal foil 4, a first resin layer 51, and a second resin layer 52. The metal foil 4, the first resin layer 51, and the second resin layer 52 respectively correspond to the metal layer 2, the first insulating layer 31, and the second insulating layer 32 in the above laminate 1. The first resin layer 51 and the second resin layer 52 can be collectively referred to as the "resin layer 5". The formed resin layer 5 is the insulating layer 3. The resin-coated metal foil 10 can be used as, for example, a material for lamination.

[0098] <Metal foil>

[0099] The metal foil 4 corresponds to the metal layer 2 in the above laminate 1. Examples of the metal foil 4 include, but are not particularly limited to, copper foils (electrolytic copper foils and rolled copper foils), stainless steel foils, nickel foils, and nickel-chromium alloy (Nichrome) foils. For example, the thickness of the metal foil 4 is, but not particularly limited to, greater than or equal to 5 μm and less than or equal to 35 μm.

[0100] <First resin layer>

[0101] The first resin layer 51 corresponds to the first insulating layer 31 in the above laminate 1. The first resin layer 51 is stacked on the metal foil 4. Specifically, the first resin layer 51 is stacked on one surface (the surface in the negative direction of the Z-axis) of the metal foil 4 and is bonded to that surface.

[0102] The first resin layer 51 is thermoplastic or cured. This enables the first resin layer 51 to prevent the second resin layer 52 from contacting the metal foil 4 during molding.

[0103] The first resin layer 51 does not contain an inorganic filler, or the first resin layer 51 contains an inorganic filler in an amount lower than the content of the heat-conductive filler (D) in the second resin layer 52.

[0104] The ratio of the thickness T11 of the first resin layer 51 to the thickness T12 of the second resin layer 52 is less than 10% (T11 / T12 < 0.1). This is beneficial for the ratio of the thickness T1 of the first insulating layer 31 to the thickness T2 of the second insulating layer 32 to be less than 10% (T1 / T2 < 0.1) after the resin layer 5 is formed.

[0105] <Second resin layer>

[0106] The second resin layer 52 corresponds to the second insulating layer 32 in the above laminate 1. The formed second resin layer 52 is the second insulating layer 32.

[0107] The second resin layer 52 is stacked on the first resin layer 51. Specifically, the second resin layer 52 is stacked on one surface (the surface in the negative direction of the Z axis) of the first resin layer 51 and bonded to this surface.

[0108] The second resin layer 52 contains a resin composition or a semi-cured product of a resin composition. The resin composition contained in the second resin layer 52 is the same as the resin composition contained in the second insulating layer 32 described above. Therefore, the description of the resin composition contained in the second resin layer 52 is omitted.

[0109] <Function and Advantage>

[0110] The resin-coated metal foil 10 according to the present embodiment can be used as a material for lamination, whereby the laminate 1 can be easily manufactured. For example, the resin-coated metal foil 10 is stacked on the core material 7 and heated and pressed to manufacture the laminate 1. The insulating layer 3 in the laminate 1 thus obtained has high thermal conductivity and high insulation reliability.

[0111] 3. Aspect

[0112] As can be seen from the above embodiments, the present disclosure includes the aspects described below. In the following description, only the reference numerals in parentheses are added to clearly show the correspondence with the embodiments.

[0113] The first aspect is a laminate (1) including: a metal layer (2); a first insulating layer (31) stacked on the metal layer (2); and a second insulating layer (32) stacked on the first insulating layer (31) and containing a cured product of a resin composition. The ratio of the thickness (T1) of the first insulating layer (31) to the thickness (T2) of the second insulating layer (32) is less than 10%. The resin composition contains an epoxy resin (A), a curing agent (B), a fluidity regulator (C), and a thermal conductivity filler (D) having a thermal conductivity of 10 W / m·K or more. The fluidity regulator (C) includes at least one of a polyether ester type fluidity regulator (C1) or a polyether ester phosphate type fluidity regulator (C2) that does not contain a phosphorus atom. Based on the total mass of the resin composition, the content of the thermal conductivity filler (D) is 84% by mass or more and 97% by mass or less. In the volume particle size distribution measured by the laser scattering / diffraction method, the thermal conductivity filler (D) has at least two peaks in the particle size range of 0.05 μm or more and 25 μm or less. The first insulating layer (31) does not contain an inorganic filler, or contains an inorganic filler having a content lower than the content of the thermal conductivity filler (D) in the second insulating layer (32).

[0114] This aspect enables an insulating layer (3) having high thermal conductivity and high insulation reliability to be formed.

[0115] The second aspect is the laminate (1) based on the first aspect. In the second aspect, the heat-conductive filler (D) contains at least one filler selected from the group consisting of a magnesium oxide filler, an aluminum nitride filler, and an aluminum oxide filler.

[0116] This aspect enables the further improvement of the thermal conductivity of the insulating layer (3).

[0117] The third aspect is the laminate (1) based on the first aspect or the second aspect. In the third aspect, the heat-conductive filler (D) contains: a first heat-conductive filler (D1), and a second heat-conductive filler (D2) having an average particle diameter smaller than the average particle diameter of the first heat-conductive filler (D1).

[0118] This aspect enables the further improvement of the thermal conductivity of the insulating layer (3).

[0119] The fourth aspect is the laminate (1) based on the third aspect. In the fourth aspect, the average particle diameter of the first heat-conductive filler (D1) is greater than 1 μm and less than or equal to 25 μm. The average particle diameter of the second heat-conductive filler (D2) is greater than or equal to 0.05 μm and less than or equal to 1 μm.

[0120] This aspect enables the further improvement of the thermal conductivity of the insulating layer (3).

[0121] The fifth aspect is the laminate (1) based on any one of the first aspect to the fourth aspect. In the fifth aspect, in the volume particle size distribution measured by the laser scattering / diffraction method, the heat-conductive filler (D) has at least one peak in the particle size range greater than 1 μm and less than or equal to 25 μm, and has at least one peak in the particle size range greater than or equal to 0.05 μm and less than or equal to 1 μm.

[0122] This aspect enables the further improvement of the thermal conductivity of the insulating layer (3).

[0123] The sixth aspect is the laminate (1) based on any one of the first aspect to the fifth aspect. In the sixth aspect, the fluidity regulator (C) is in a liquid form at 25 °C and is non-ionic.

[0124] This aspect enables the insulating layer (3) to have a uniform thickness.

[0125] The seventh aspect is the laminate (1) based on any one of the first aspect to the sixth aspect. In the seventh aspect, each molecule of the phosphorus atom-free polyether ester type fluidity regulator (C1) has a plurality of ether structures, a plurality of ester structures, and a plurality of carboxyl groups.

[0126] This aspect enables the insulating layer (3) to have a more uniform thickness.

[0127] The eighth aspect is the laminate (1) based on any one of the first to seventh aspects. In the eighth aspect, based on 100 parts by mass of the thermal conductive filler (D), the content of the fluidity regulator (C) is greater than or equal to 0.005 part by mass and less than or equal to 0.5 part by mass.

[0128] This aspect enables the insulating layer (3) to have a more uniform thickness.

[0129] The ninth aspect is the laminate (1) based on any one of the first to eighth aspects. In the ninth aspect, the curing agent (B) contains at least one of phenolic resin or dicyandiamide.

[0130] This aspect enables the insulating layer (3) to have further improved insulation reliability.

[0131] The tenth aspect is a resin-coated metal foil (10), which includes: a metal foil (4); a first resin layer (51) stacked on the metal foil (4); and a second resin layer (52) stacked on the first resin layer (51) and containing a resin composition or a semi-cured product of the resin composition. The ratio of the thickness (T11) of the first resin layer (51) to the thickness (T12) of the second resin layer (52) is less than 10%. The resin composition contains an epoxy resin (A), a curing agent (B), a fluidity regulator (C), and a thermal conductive filler (D) with a thermal conductivity greater than or equal to 10 W / m·K. The fluidity regulator (C) contains at least one of a phosphorus atom-free polyether ester type fluidity regulator (C1) or a polyether ester phosphate type fluidity regulator (C2). Based on the total mass of the resin composition, the content of the thermal conductive filler (D) is greater than or equal to 84% by mass and less than or equal to 97% by mass. In the volume particle size distribution measured by the laser scattering / diffraction method, the thermal conductive filler (D) has at least two peaks in the particle size range of greater than or equal to 0.05 μm and less than or equal to 25 μm. The first resin layer is thermoplastic or cured. The first resin layer (51) does not contain an inorganic filler, or contains an inorganic filler with a content lower than the content of the thermal conductive filler (D) in the second resin layer (52).

[0132] This aspect enables an insulating layer (3) with high thermal conductivity and high insulation reliability to be formed.

[0133] The eleventh aspect is the resin-coated metal foil (10) based on the tenth aspect. In the eleventh aspect, the thermal conductive filler (D) contains at least one filler selected from the group consisting of a magnesium oxide filler, an aluminum nitride filler, and an aluminum oxide filler.

[0134] This aspect enables the thermal conductivity of the insulating layer (3) to be further improved.

[0135] The twelfth aspect is a resin-coated metal foil (10) based on the tenth or eleventh aspect. In the twelfth aspect, the heat-conductive filler (D) includes: a first heat-conductive filler (D1), and a second heat-conductive filler (D2) having an average particle size smaller than the average particle size of the first heat-conductive filler (D1).

[0136] This aspect enables further improvement of the thermal conductivity of the insulating layer (3).

[0137] The thirteenth aspect is a resin-coated metal foil (10) referring to the twelfth aspect. In the thirteenth aspect, the average particle size of the first heat-conductive filler (D1) is greater than 1 μm and less than or equal to 25 μm. The average particle size of the second heat-conductive filler (D2) is greater than or equal to 0.05 μm and less than or equal to 1 μm.

[0138] This aspect enables further improvement of the thermal conductivity of the insulating layer (3).

[0139] The fourteenth aspect is a resin-coated metal foil (10) referring to any one of the tenth to thirteenth aspects. In the fourteenth aspect, in the volume particle size distribution measured by the laser scattering / diffraction method, the heat-conductive filler (D) has at least one peak in the particle size range greater than 1 μm and less than or equal to 25 μm, and has at least one peak in the particle size range greater than or equal to 0.05 μm and less than or equal to 1 μm.

[0140] This aspect enables further improvement of the thermal conductivity of the insulating layer (3).

[0141] The fifteenth aspect is a resin-coated metal foil (10) referring to any one of the tenth to fourteenth aspects. In the fifteenth aspect, the fluidity regulator (C) is in a liquid form at 25°C and is non-ionic.

[0142] This aspect enables the insulating layer (3) to have a uniform thickness.

[0143] The sixteenth aspect is a resin-coated metal foil (10) referring to any one of the tenth to fifteenth aspects. In the sixteenth aspect, each molecule of the phosphorus atom-free polyether ester type fluidity regulator (C1) has a plurality of ether structures, a plurality of ester structures, and a plurality of carboxyl groups.

[0144] This aspect enables the insulating layer (3) to have a more uniform thickness.

[0145] The seventeenth aspect is the resin-coated metal foil (10) according to any one of the tenth to sixteenth aspects. In the seventeenth aspect, based on 100 parts by mass of the heat-conductive filler (D), the content of the fluidity regulator (C) is greater than or equal to 0.005 part by mass and less than or equal to 0.5 part by mass.

[0146] This aspect enables the insulating layer (3) to have a more uniform thickness.

[0147] The eighteenth aspect is the resin-coated metal foil (10) according to any one of the tenth to seventeenth aspects. In the eighteenth aspect, the curing agent (B) contains at least one of phenolic resin or dicyandiamide.

[0148] This aspect enables the insulating layer (3) to have further improved insulation reliability.

[0149] Examples

[0150] The present disclosure will be specifically described below with reference to examples. Note that the present disclosure is not limited to the examples.

[0151] 1. Examples and Comparative Examples

[0152] (1) Raw Materials

[0153] The raw materials for the resin composition in each example and comparative example are as follows.

[0154] <Epoxy Resin (A)>

[0155] · Epoxy Resin 1: Triphenolmethane epoxy resin, epoxy equivalent of 158 to 178 g / eq, produced by Nippon Kayaku Co., Ltd., product name "EPPN502H"

[0156] · Epoxy Resin 2: Triphenolmethane epoxy resin, epoxy equivalent of 150 to 180 g / eq, produced by DIC Corporation, product name "HP-7250"

[0157] Note that the epoxy resin in the first insulating layer is the same as the epoxy resin (A) in the second insulating layer.

[0158] <Curing Agent (B)>

[0159] · Curing Agent 1: Biphenyl aralkyl phenolic resin, hydroxyl equivalent of 132 g / eq, produced by UBE Corporation, product name "MEHC-7403H"

[0160] · Curing Agent 2: Dicyandiamide (Dicy)

[0161] Note that the phenolic resin in the first insulating layer is the same as the curing agent 1 in the second insulating layer.

[0162] <Flowability regulator (C)>

[0163] <<Phosphorus atom-free polyether ester type flowability regulator (C1)>>

[0164] · Polyether ester type: Produced by Kusumoto Chemicals, Ltd., product name "DISPARLON 3350EF"

[0165] <<Polyether ester phosphate type flowability regulator (C2)>>

[0166] · Polyether ester phosphate type: Produced by Kusumoto Chemicals, Ltd., product name "DISPARLON3500"

[0167] <Thermal conductivity filler (D)>

[0168] <<First thermal conductivity filler (D1)>>

[0169] · Alumina filler 1: Produced by NIPPON STEEL Chemical & Material Co., Ltd., product name "AZ10-20"

[0170] · Aluminum nitride filler: Produced by Tokuyama Corporation, product name "HF-10c"

[0171] <<Second thermal conductivity filler (D2)>>

[0172] · Alumina filler 2: Produced by Admatechs Company Limited, product name "AO-502" (specific surface area 6.5 to 9.0 m 2 / g)

[0173] <Others>

[0174] <<Catalyst>>

[0175] · 2-Ethyl-4-methylimidazole, produced by Shikoku Chemicals Corporation, product name "2E4MZ"

[0176] <<Flame retardant>>

[0177] · Phosphazene-based flame retardant (non-halogen flame retardant), produced by FUSHIMI Pharmaceutical Co., Ltd., product name "FP-100"

[0178] <<Flexible component>>

[0179] · Epoxy-modified acrylic resin, produced by Nagase ChemteX Corporation, product name "PASR-001"

[0180] <<Coupling agent>>

[0181] · Silane coupling agent (8-glycidyloxyoctyltrimethoxysilane), produced by Shin-Etsu Chemical Co., Ltd., product name "KBM-4803"

[0182] <<Dispersant>>

[0183] · Wetting dispersant, produced by BYK-Chemie, product name "BYK-W903"

[0184] <<Inorganic filler>>

[0185] · Molybdenum compound filler, produced by J. M. Huber Corporation, product name "KG-501"

[0186] <<Metal deactivator>>

[0187] · Hydrazide series: produced by ADEKA CORPORATION, product name "CDA-10"

[0188] <<Ion scavenger>>

[0189] · Hydrotalcite series: Inorganic ion scavenger, produced by TOAGOSEI CO., LTD., product name "IXEPLAS-A1"

[0190] (2) Resin composition

[0191] For each of the examples and comparative examples, the resin composition for the first insulating layer and the resin composition for the second insulating layer are manufactured in the following manner.

[0192] (2.1) Resin composition for the first insulating layer

[0193] (2.1.1) Examples 1 to 4 and Comparative Example 5

[0194] The resin composition for the first insulating layer in each of Examples 1 to 4 is a resin composition containing epoxy resin. The epoxy resin, phenolic resin, catalyst, flame retardant, and flexible component are dissolved in methyl ethyl ketone in the amounts (unit: parts by mass) shown in Tables 1 and 2, whereby the solutions of the resin compositions for the first insulating layer of Examples 1 to 4 and Comparative Example 5 are obtained.

[0195] (2.1.2) Examples 5 to 8

[0196] For each of Examples 5 to 8, the resin composition for the first insulating layer is a resin composition containing a polyamideimide resin. By mixing 192 g (50 mol%) of trimellitic anhydride (Nacalai Tesque, Inc.), 211 g (40 mol%) of 4,4'-diisocyanato-3,3'-dimethylbiphenyl, 35 g (10 mol%) of 2,4-toluene diisocyanate, 1 g of diazabicycloundecene (produced by San-Apro Ltd.), and 2482 g of N,N-dimethylacetamide (DMAC, Nacalai Tesque, Inc.) together, a mixture with a polymer concentration of 15% by mass is obtained. The mixture is heated to 100°C within 1 hour, and then the mixture is maintained at 100°C for 6 hours to promote the reaction.

[0197] Then, 1460 g of DMAC is further added to the mixture to adjust the polymer concentration to 10% by mass, and then the polymer is cooled to room temperature. Thus, a solution of the resin composition for the first insulating layer for each of Examples 5 to 8 is obtained.

[0198] (2.2) Resin composition for the second insulating layer

[0199] The raw materials in the amounts (unit: parts by mass) shown in Table 1 and Table 2 are mixed together to obtain a mixture. The mixture is dissolved or dispersed in a mixed solvent of methyl ethyl ketone and dimethylformamide, and then the mixed solvent is stirred in a rotary stirrer to prepare solutions of the resin compositions for each of the examples and comparative examples. The ratio of methyl ethyl ketone:dimethylformamide in the mixed solvent (volume ratio) = 0 to 100:100 to 0.

[0200] [Table 1]

[0201]

[0202] [Table 2]

[0203]

[0204] Table 3 shows the D50 (50% diameter of the integral distribution) and D99 (99% diameter of the integral distribution) of the thermally conductive filler (D).

[0205]

[0206] (3) Resin-coated metal foil

[0207] Use an electrolytic copper foil with surface treatment (produced by Furukawa Electric Co., Ltd., product name "F2-WS", nominal thickness: 18 μm, size: 550 mm × 700 mm) as the metal foil 4.

[0208] For Examples 1 to 4 and Comparative Example 5, the resin composition for the first insulating layer was coated on one surface of the metal foil 4 and dried at 200°C for 3 to 5 minutes, thereby forming a first resin layer 51 with a thickness of 5 to 20 μm.

[0209] On the other hand, for Examples 5 to 8, the resin composition for the first insulating layer was coated on one surface of the metal foil 4, heated at 200°C for 4 minutes, and then heated at 250°C for 10 minutes, thereby forming a first resin layer 51 with a thickness of 5 μm.

[0210] Then, the resin composition for the second insulating layer was coated on the first resin layer 51 and dried at 150°C for 2 to 5 minutes, thereby forming a second resin layer 52 with a thickness of 50 to 200 μm. Thus, a resin-coated metal foil (size: 510 mm × 340 mm) as shown in Figure 2 was obtained.

[0211] Note that for Comparative Examples 1 to 4 and 6, the first resin layer 51 was not formed, but the second resin layer 52 was directly formed on the metal foil 4. Note that the ratio of the thickness T11 of the first resin layer 51 to the thickness T12 of the second resin layer 52 is substantially equal to the ratio of the thickness T1 of the first insulating layer 31 to the thickness T2 of the second insulating layer 32.

[0212] (4) Test laminate

[0213] The test laminate 6 as shown in Figure 3 was manufactured as follows. A double-sided copper-clad laminate (produced by Panasonic Corporation, product name "R-1566S", high heat-resistant halogen-free multi-layer base material, thickness: 400 μm, thickness of each copper foil: 105 μm, size: 515 mm × 340 mm) was used as the core material 7. The copper foils on each of the two surfaces of the double-sided copper-clad laminate were etched, thereby forming a conductive layer 8 having a Figure 4 test pattern (comb pattern) as shown in the XY plan view.

[0214] Then, the resin layer 5 of the above resin-coated metal foil 10 was stacked on each of the two surfaces of the core material 13 and heated and pressed at 200°C and 3 MPa for 60 minutes, thereby manufacturing the test laminate 6 (see Figure 3)。Subsequently, one or more unnecessary portions of the copper foil on each of the two surfaces of the test laminate 6 are removed by etching, thereby forming a metal layer 2 having a comb-like pattern similar to that of the conductive layer 8 in the XY plane.

[0215] 2. Evaluation

[0216] (1) Thermal conductivity

[0217] The resin layer 5 of the resin-coated metal foil 10 is cured by heating to obtain the insulating layer 3. The thermal conductivity of the insulating layer 3 is measured by the laser-flash method defined in JIS R 1611. The results are shown in Tables 4 and 5.

[0218] (2) Insulation reliability

[0219] The above-mentioned test laminate 6 is placed in an environment of 85°C / 85% rh, and a voltage of 900 V is applied between the outer layer ( Figure 3 the shown metal layer 2a has a Figure 4 shown comb-like pattern in the XY plane) and the inner layer ( Figure 3 the shown conductive layer 8a has a Figure 4 shown comb-like pattern in the XY plane) while measuring the resistance value of the insulating layer 3 (the first insulating layer 31 and the second insulating layer 32). The time is monitored from the start of voltage application until the resistance value drops below 1×10 7 Ω (regardless of whether this time exceeds 150 hours). The results are shown in Tables 4 and 5.

[0220] [Table 4]

[0221]

[0222] [Table 5]

[0223]

[0224] List of reference numerals

[0225] 1 Laminate

[0226] 2 Metal layer

[0227] 3 Insulating layer

[0228] 31 First insulating layer

[0229] 32 Second insulating layer

[0230] 10 Resin-coated metal foil

[0231] 4 Metal foil

[0232] 51 First resin layer

[0233] 52 Second resin layer

Claims

1. A laminate, the laminate comprising: A metal layer; A first insulating layer stacked on the metal layer; And A second insulating layer stacked on the first insulating layer and containing a cured product of a resin composition, The ratio of the thickness of the first insulating layer to the thickness of the second insulating layer is less than 10%, The resin composition contains an epoxy resin (A), a curing agent (B), a fluidity regulator (C), and a heat conductive filler (D) having a thermal conductivity of 10 W / m·K or higher, The fluidity regulator (C) contains at least one of a phosphorus atom-free polyether ester type fluidity regulator (C1) or a polyether ester phosphate type fluidity regulator (C2), Based on the total mass of the resin composition, the content of the heat conductive filler (D) is 84% by mass or more and 97% by mass or less, In the volume particle size distribution measured by the laser scattering / diffraction method, the heat conductive filler (D) has at least two peaks in the particle size range of 0.05 μm or more and 25 μm or less, The first insulating layer does not contain an inorganic filler, or contains an inorganic filler having a content lower than the content of the heat conductive filler (D) in the second insulating layer.

2. The laminate according to claim 1, wherein The heat conductive filler (D) contains at least one filler selected from the group consisting of a magnesium oxide filler, an aluminum nitride filler, and an aluminum oxide filler.

3. The laminate according to claim 1, wherein The heat conductive filler (D) contains a first heat conductive filler (D1) and a second heat conductive filler (D2) having an average particle size smaller than the average particle size of the first heat conductive filler (D1).

4. The laminate according to claim 3, wherein The average particle size of the first heat conductive filler (D1) is greater than 1 μm and less than or equal to 25 μm, and The average particle size of the second heat conductive filler (D2) is greater than or equal to 0.05 μm and less than or equal to 1 μm.

5. The laminate according to claim 1, wherein In the volume particle size distribution measured by the laser scattering / diffraction method, the heat conductive filler (D) has at least one peak in the particle size range of greater than 1 μm and less than or equal to 25 μm, and at least one peak in the particle size range of greater than or equal to 0.05 μm and less than or equal to 1 μm.

6. The laminate according to claim 1, wherein The fluidity regulator (C) is in a liquid form at 25°C and is non-ionic.

7. The laminate according to claim 1, wherein Each molecule of the phosphorus atom-free polyether ester type fluidity regulator (C1) has a plurality of ether structures, a plurality of ester structures, and a plurality of carboxyl groups.

8. The laminate according to claim 1, wherein Based on 100 parts by mass of the heat conductive filler (D), the content of the fluidity regulator (C) is 0.005 parts by mass or more and 0.5 parts by mass or less.

9. The laminate according to claim 1, wherein The curing agent (B) contains at least one of a phenolic resin or dicyandiamide.

10. A resin-coated metal foil, the resin-coated metal foil comprising: a metal foil; a first resin layer laminated on the metal foil; and a second resin layer laminated on the first resin layer and containing a resin composition or a semi-cured product of the resin composition, a ratio of a thickness of the first resin layer to a thickness of the second resin layer is less than 10%, the resin composition contains an epoxy resin (A), a curing agent (B), a fluidity regulator (C), and a heat-conductive filler (D) having a thermal conductivity of 10 W / m·K or higher, the fluidity regulator (C) contains at least one of a phosphorus atom-free polyether ester type fluidity regulator (C1) or a polyether ester phosphate type fluidity regulator (C2), based on a total mass of the resin composition, a content of the heat-conductive filler (D) is 84% by mass or more and 97% by mass or less, in a volume particle size distribution measured by a laser scattering / diffraction method, the heat-conductive filler (D) has at least two peaks in a particle size range of 0.05 μm or more and 25 μm or less, the first resin layer is thermoplastic or cured, the first resin layer does not contain an inorganic filler, or contains an inorganic filler having a content lower than a content of the heat-conductive filler (D) in the second resin layer.

11. The resin-coated metal foil according to claim 10, wherein the heat-conductive filler (D) contains at least one filler selected from the group consisting of a magnesium oxide filler, an aluminum nitride filler, and an aluminum oxide filler.

12. The resin-coated metal foil according to claim 10, wherein the heat-conductive filler (D) contains a first heat-conductive filler (D1) and a second heat-conductive filler (D2) having an average particle size smaller than an average particle size of the first heat-conductive filler (D1).

13. The resin-coated metal foil according to claim 12, wherein the first heat-conductive filler (D1) has an average particle size greater than 1 μm and less than or equal to 25 μm, and the second heat-conductive filler (D2) has an average particle size greater than or equal to 0.05 μm and less than or equal to 1 μm.

14. The resin-coated metal foil according to claim 10, wherein in a volume particle size distribution measured by a laser scattering / diffraction method, the heat-conductive filler (D) has at least one peak in a particle size range of greater than 1 μm and less than or equal to 25 μm, and has at least one peak in a particle size range of greater than or equal to 0.05 μm and less than or equal to 1 μm.

15. The resin-coated metal foil according to claim 10, wherein the fluidity regulator (C) is in a liquid form at 25°C and is nonionic.

16. The resin-coated metal foil according to claim 10, wherein each molecule of the phosphorus atom-free polyether ester type fluidity regulator (C1) has a plurality of ether structures, a plurality of ester structures, and a plurality of carboxyl groups.

17. The resin-coated metal foil according to claim 10, wherein Based on 100 parts by mass of the thermal conductive filler (D), the content of the fluidity regulator (C) is greater than or equal to 0.005 parts by mass and less than or equal to 0.5 parts by mass.

18. The resin-coated metal foil according to any one of claims 10 to 17, wherein the curing agent (B) contains at least one of phenolic resin or dicyandiamide.

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