Insulating sheet and semiconductor module

Abstract

Provided is an insulating sheet comprising a metal substrate layer and a resin composition layer that overlaps at least one surface of the substrate layer, wherein: the resin composition layer at least includes a heat-conductive filler, an epoxy resin, a curing agent, and an additive; and the additive contains at least one selected from the group consisting of compounds having an imidazole structure in each molecule, compounds having a cyano group in each molecule, and compounds having a triazole structure in each molecule.

Description

Insulating sheet and semiconductor module CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from Japanese Patent Application No. 2024-007308, which is incorporated herein by reference.

[0002] The present invention relates to, for example, an insulating sheet that constitutes a semiconductor module, and a semiconductor module that includes the insulating sheet.

[0003] Conventionally, an insulating sheet has been known that includes a base layer and a resin composition layer overlaid on one surface of the base layer. The resin composition layer contains, for example, a thermally conductive filler, an epoxy group-containing compound, a curing agent, and an additive.

[0004] Known examples of this type of insulating sheet include an insulating sheet formed by laminating a substrate layer made of a metal foil and a resin composition layer, in which the resin composition layer contains a thermally conductive filler such as a boron nitride filler and an aluminum nitride filler, a specific epoxy monomer as an epoxy group-containing compound, a phenolic compound as a curing agent, and an onium salt curing accelerator as an additive (see, for example, Patent Document 1).

[0005] More specifically, in the insulating sheet described in Patent Document 1, the resin composition layer contains a boron nitride filler and an aluminum nitride filler, an epoxy monomer having a specific molecular structure as an epoxy compound, 4,4',4"-methylidynetrisphenol as a curing agent, and further contains tetraphenylphosphonium tetraphenylborate as an additive. In the insulating sheet described in Patent Document 1, the cured product of the resin composition layer can have good thermal conductivity.

[0006] Japan Publication No. 2015-059186

[0007] However, when the insulating sheet described in Patent Document 1 is used for a long period of time in a high-temperature environment, for example, above 150°C, the resin composition layer may peel off from the substrate layer. For example, when an insulating sheet is used as a component of a semiconductor power module, the insulating sheet may be exposed to such a high-temperature environment for a long period of time during use. If the resin composition layer peels off from the substrate layer of the insulating sheet during use, the performance of the semiconductor power module may deteriorate. Therefore, there is a demand for an insulating sheet in which the resin composition layer is prevented from peeling off from the metal substrate layer even after a long period of time has passed in a high-temperature environment.

[0008] In view of the above problems and demands, an object of the present invention is to provide an insulating sheet in which peeling of a resin composition layer from a metal substrate layer is suppressed even after a long period of time in a high-temperature environment.

[0009] In order to solve the above problems, the insulating sheet of the present invention comprises a metal substrate layer and a resin composition layer overlying at least one surface of the substrate layer, wherein the resin composition layer contains at least a thermally conductive filler, an epoxy resin, a curing agent, and an additive, and the additive contains at least one compound selected from the group consisting of a compound having an imidazole structure in its molecule, a compound having a cyano group in its molecule, and a compound having a triazole structure in its molecule.

[0010] A semiconductor module according to the present invention includes the insulating sheet described above.

[0011] Fig. 1 is a schematic cross-sectional view of an insulating sheet according to this embodiment cut in the thickness direction. Fig. 2 is a schematic cross-sectional view of a semiconductor module according to this embodiment cut. Fig. 3 is a schematic view showing a method for evaluating the delamination suppression performance between a base layer and a resin composition layer of an insulating sheet. Fig. 4 is a graph showing the results of an evaluation test of the delamination suppression performance between a base layer and a resin composition layer of an insulating sheet.

[0012] Hereinafter, an embodiment of an insulating sheet according to the present invention will be described with reference to the drawings.

[0013] As shown in Figure 1, the insulating sheet 1 of this embodiment includes a metal substrate layer 2 and a resin composition layer 3 superimposed on one surface of the substrate layer 2. The resin composition layer 3 contains at least a thermally conductive filler, an epoxy resin, a curing agent, and an additive. The additive contains at least one compound selected from the group consisting of a compound having an imidazole structure in its molecule, a compound having a cyano group in its molecule, and a compound having a triazole structure in its molecule. The insulating sheet 1 of this embodiment having such a configuration is inhibited from peeling off the resin composition layer 3 from the metal substrate layer 2 even when exposed to a high-temperature environment for a long period of time.

[0014] The thickness of the substrate layer 2 may be, for example, 35 μm or more and 2,000 μm or less.

[0015] The substrate layer 2 is made of metal. There are no particular limitations on the substrate layer 2 as long as the constituent components contain 95% or more metal. The substrate layer 2 is, for example, copper foil. The substrate layer 2 may contain copper oxide as a constituent component in addition to metallic copper.

[0016] An oxide film containing, for example, copper oxide is formed on a surface portion of one surface of the substrate layer 2 that overlaps with the resin composition layer 3. In other words, the substrate layer 2 may have an oxide film containing copper oxide on a surface layer portion of the surface that overlaps with the resin composition layer 3. The average thickness of the oxide film is the average thickness of the oxide film formed from the outermost surface of the substrate layer 2 toward the inside in the thickness direction.

[0017] The average thickness of the resin composition layer 3 is not particularly limited and may be, for example, 10 μm or more and 300 μm or less, and preferably 100 μm or more and 200 μm or less.

[0018] The resin composition layer 3 preferably contains 40% by volume or more and 70% by volume or less of the thermally conductive filler.

[0019] The thermally conductive filler contained in the resin composition layer 3 is, for example, a particulate inorganic filler composed of an inorganic compound. Examples of inorganic fillers include boron nitride filler, aluminum nitride filler, silicon nitride filler, gallium nitride filler, alumina filler, silicon carbide filler, silicon dioxide filler, magnesium oxide filler, and diamond filler. Boron nitride filler is preferred as the inorganic filler because it has better durability and heat dissipation properties and has less adverse effects on inhibiting the reactivity of epoxy resins and the like. The boron nitride filler typically contains 95% by mass or more of boron nitride. It is preferable that 90% by mass or more of the thermally conductive filler be boron nitride filler. The thermally conductive filler is dispersed in the resin composition layer in the form of primary particles or secondary particles.

[0020] The average particle size of the thermally conductive filler may be, for example, 20 μm or more and 60 μm or less.

[0021] As the inorganic filler, commercially available products can be used, for example, inorganic fillers available from JFE Mineral Co., Ltd., Resonac Co., Ltd., Denka Co., Ltd., etc.

[0022] Examples of the epoxy resin contained in the resin composition layer 3 include dicyclopentadiene type, cresol novolac type, phenol novolac type, bisphenol type, biphenyl type, and trisphenolmethane type. These epoxy resins may be used alone or in combination of two or more.

[0023] The epoxy equivalent of the epoxy resin may be 100 g / eq or more and 500 g / eq or less. The "epoxy equivalent" of the epoxy resin can be determined in accordance with JIS K7236:2001.

[0024] As the epoxy resin, commercially available products can be used, for example, epoxy resins available from ADEKA Corporation, DIC Corporation, Mitsubishi Chemical Corporation, Nippon Steel Chemical & Material Co., Ltd., Nippon Kayaku Co., Ltd., etc.

[0025] In the resin composition layer 3, the mass ratio of the thermally conductive filler to the epoxy resin (total amount) is preferably 2 or more and 5 or less. By having the mass ratio of 2 or more and 5 or less, the resin composition layer 3 can have thermal conductivity while also having appropriate fluidity. Therefore, it can have better adhesion to the adherend. Moreover, the resin composition layer 3 can have both appropriate heat dissipation properties and appropriate insulation properties. The mass ratio is more preferably 4 or less.

[0026] In this embodiment, the curing agent contained in the resin composition layer 3 acts as a curing agent for the epoxy resin.

[0027] Examples of the curing agent for the epoxy resin include a polymeric addition type curing agent having active hydrogen in the molecule, a catalytic type curing agent, etc. Examples of the polymeric addition type curing agent include amines, acids such as organic acids and acid anhydrides, mercaptans, and phenols (e.g., phenolic resins). Examples of the phenols include phenol novolacs. Examples of the catalytic type curing agent include boron trifluoride-amine complexes.

[0028] In this embodiment, a phenolic resin may be used as a curing agent for the epoxy resin. Examples of the phenolic resin include novolac-type phenolic resin, aralkyl-type phenolic resin, and resol-type phenolic resin.

[0029] Examples of novolac phenolic resins include phenol novolac resin, cresol novolac resin, bisphenol A novolac resin, and triazine skeleton-containing phenol novolac resin. Examples of aralkyl phenolic resins include biphenyl aralkyl phenolic resin.

[0030] The curing agent preferably contains a phenol novolac resin and a biphenyl aralkyl phenol resin, which allows the reactivity of the epoxy resin or the like to be appropriately adjusted.

[0031] The phenolic hydroxyl group equivalent of the phenolic resin may be, for example, 100 g / eq or more and 300 g / eq or less. The "hydroxyl group equivalent" of the phenolic resin can be calculated based on the hydroxyl value determined in accordance with JIS K0070:1992 (basically neutralization titration method, and optionally potentiometric titration method) using the following formula: Hydroxyl group equivalent = molecular weight of potassium hydroxide / hydroxyl group value

[0032] Commercially available products can be used as the curing agent for the epoxy resin. For example, phenolic resins are available from Sumitomo Bakelite Co., Ltd., DIC Corporation, UBE Corporation (formerly Meiwa Kasei Co., Ltd.), Gun-ei Chemical Industry Co., Ltd., etc.

[0033] The resin composition layer 3 of this embodiment contains, as an additive, at least one selected from the group consisting of a compound having an imidazole structure in its molecule, a compound having a cyano group in its molecule, and a compound having a triazole structure in its molecule. The resin composition layer 3 may further contain, as an additive, a phosphorus-containing compound. The additive may function as a curing accelerator for the epoxy resin. Furthermore, when the substrate layer 2 contains copper, the additive may function to improve adhesion to a copper oxide film on the surface of the substrate layer 2.

[0034] The resin composition layer 3 of this embodiment preferably contains additives (total amount) of 0.1% by mass or more and 0.4% by mass or less. When the total content of additives in the resin composition layer 3 is within the above range, the curing reaction rate of the resin composition layer 3 becomes appropriate, and the occurrence of problems during production can be sufficiently suppressed. Furthermore, when the base layer 2 contains copper, the strong adhesive force between the base layer having an oxide film on its surface and the resin composition layer 3 can be maintained for a longer period of time.

[0035] A compound having an imidazole structure in the molecule has a structure of the following formula (1) in the molecule: The dashed lines indicate bonds to hydrogen (H) as well as bonds to various groups.

[0036] Examples of compounds having an imidazole structure in the molecule include the following compounds: 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-(2-cyanoethyl)-2-phenylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine (isocyanuric acid adduct) [alias: 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct], 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, etc.

[0037] The compound having an imidazole structure in the molecule is preferably a compound having two heterocyclic structures, and more preferably a compound having a molecular weight of 150 or more and 250 or less.

[0038] A preferred compound having an imidazole structure in the molecule is 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine (isocyanuric acid adduct), which can further prevent the resin composition layer 3 from peeling off from the metal substrate layer 2 even when exposed to a high-temperature environment for a long period of time.

[0039] An example of a compound having a cyano group in the molecule is dicyandiamide.

[0040] Dicyandiamide is preferred as the compound having a cyano group in the molecule, which can further prevent the resin composition layer 3 from peeling off from the metal substrate layer 2 even when exposed to a high-temperature environment for a long period of time.

[0041] A compound having a triazole structure in its molecule has a structure of the following formula (2) in its molecule: The dashed lines indicate bonds to hydrogen (H) as well as bonds to various groups.

[0042] The compound having a triazole structure in the molecule is preferably benzotriazole (BTA), 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole, tolyltriazole (TTA), or 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole, which can further prevent the resin composition layer 3 from peeling off from the metal substrate layer 2 even when exposed to a high-temperature environment for a long period of time.

[0043] Examples of the phosphorus-containing compound that can be contained in the resin composition layer 3 include triphenylphosphine (TPP), tetraphenylphosphonium tetraphenylborate, and tetraphenylphosphonium tetra(4-methylphenyl)borate.

[0044] As the additive, commercially available products can be used. For example, commercially available products from reagent manufacturers can be used as the compound having an imidazole structure in the molecule, the compound having a cyano group in the molecule, or the compound having a triazole structure in the molecule.

[0045] The resin composition layer 3 of this embodiment may further contain a silane coupling agent or the like.

[0046] Examples of the silane coupling agent include a silane coupling agent containing a vinyl group, a silane coupling agent containing a glycidyl group, a silane coupling agent containing a (meth)acryloyl group, a silane coupling agent containing an amino group, and a silane coupling agent containing a mercapto group.

[0047] The silane coupling agent is preferably a silane coupling agent containing a glycidyl group, which can chemically bond to both the inorganic filler and the curing agent, and thus can bond the inorganic filler and the curing agent via the silane coupling agent.

[0048] Next, a method for manufacturing the insulating sheet 1 of this embodiment will be described.

[0049] The insulating sheet 1 of this embodiment can be manufactured, for example, by preparing a mixture containing each component that will constitute the above-mentioned resin composition layer 3 and an organic solvent, applying the mixture to the substrate layer 2, and volatilizing the organic solvent contained in the applied mixture.

[0050] Examples of the organic solvent include aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, alicyclic hydrocarbon solvents, ester group-containing polar solvents, ketone group-containing polar solvents, hydroxy group-containing polar solvents, ether group-containing polar solvents, amino group-containing polar solvents, and halogen-containing polar solvents. Specific examples of the organic solvent include ethyl acetate, methyl ethyl ketone, and toluene.

[0051] When applying the mixture containing the organic solvent to the base layer 2, a common application method such as a die coating method or a reverse coating method can be used. The temperature during application is, for example, room temperature (15 to 25°C). Thereafter, the organic solvent is volatilized by a heat treatment or the like to produce an uncured resin composition layer 3.

[0052] The resin composition layer 3 of the insulating sheet 1 of this embodiment is in a semi-cured state in which the curing reaction has progressed partway due to the curing treatment. In other words, a portion of the resin composition layer 3 has been cured by the curing treatment. In other words, the epoxy resin contained in the resin composition layer 3 is in a B-stage state. For example, the uncured resin composition layer 3 is pressed at 120°C for 20 minutes, and then the resin composition layer 3 is pressure-bonded to the base layer 2 under conditions of 120°C for 20 minutes, thereby producing an insulating sheet 1 including a semi-cured resin composition layer 3 and a base layer 2.

[0053] The insulating sheet 1 manufactured as described above is used, for example, as a component for a semiconductor module. Since the resin composition layer 3 of the insulating sheet 1 contains an epoxy resin and a thermally conductive filler, the resin composition layer 3 has electrical insulation properties and thermal conductivity.

[0054] Next, an embodiment of a semiconductor module of the present invention will be described with reference to the drawings.

[0055] The semiconductor module 100 of this embodiment includes the insulating sheet 1 described above. The semiconductor module 100 of this embodiment is, for example, a component constituting a power control part. The semiconductor module 100 is equipped with, for example, a power transistor as a semiconductor element. The semiconductor module 100 includes, for example, a member such as an aluminum heat sink to radiate heat generated by the operation of the semiconductor element to the outside of the module and suppress an internal temperature rise.

[0056] As shown in FIG. 2 , the semiconductor module 100 of this embodiment includes a semiconductor element 101, a rectangular parallelepiped heat sink 102 (e.g., a heat sink) for absorbing heat from the semiconductor element 101, and a rectangular frame-like case 104 for accommodating the semiconductor element 101, the heat sink 102, and the like. The semiconductor module 100 of this embodiment also includes a lead frame 103 that forms an electrical circuit together with the semiconductor element 101 and constitutes the external terminals of the semiconductor module 100. The semiconductor module 100 of this embodiment has, for example, a flat rectangular parallelepiped shape. In the semiconductor module 100 of this embodiment, the semiconductor element 101 and the heat sink 102 are embedded in molded resin 105 inside the case 104. The semiconductor element 101 is disposed on the upper side of the heat sink 102 and is fixed to the heat sink 102 with solder 106, thereby electrically connecting the semiconductor element 101 to the heat sink 102. The semiconductor element 101 and the heat sink 102 are electrically connected to the lead frame 103 by bonding wires 107. In the semiconductor module 100 of this embodiment, the heat sink 102 is disposed so that its lower surface is flush with the lower surface of the molded resin 105.

[0057] The insulating sheet 1 is adhered to the heat sink 102 so as to cover the lower surface of the heat sink 102 from below. The insulating sheet 1 is adhered to the heat sink 102 with the resin composition layer 3 in contact with the heat sink 102. In other words, the resin composition layer 3 is disposed between the heat sink 102 and the base material layer 2 of the insulating sheet 1. The resin composition layer 3 of the insulating sheet 1 is also adhered to the lower surface of the molded resin 105 around the heat sink 102.

[0058] In the semiconductor module 100 of this embodiment, the semiconductor element 101 and the lead frame 103 are electrically connected to the heat sink 102, and the heat sink 102 forms an electrical circuit together with the semiconductor element 101 and the lead frame 103. The semiconductor module 100 of this embodiment includes an insulating sheet 1 to insulate the electrical circuit from the outside.

[0059] In this embodiment, the resin composition layer 3 of the insulating sheet 1 is in a semi-cured state (epoxy resin, etc., is in a B-stage state) before being adhered to the heat sink 102, and is in a fully cured state (epoxy resin, etc., is in a C-stage state) after being adhered to the heat sink 102.

[0060] The semiconductor module 100 of this embodiment includes the insulating sheet 1, which is arranged in contact with another heat sink (such as a heat sink fin) made of, for example, aluminum, in order to conduct and dissipate heat generated inside the module 100. The insulating sheet 1 not only provides electrical insulation between the semiconductor module 100 and the other heat sink, but also thermal conductivity. Therefore, the insulating sheet 1 allows heat generated in the semiconductor module 100 to be conducted to and dissipated by the other heat sink.

[0061] The insulating sheet and semiconductor module of this embodiment are as exemplified above, but the present invention is not limited to the insulating sheet or semiconductor module exemplified above. In other words, various forms used in general insulating sheets or semiconductor modules can be adopted within the scope that does not impair the effects of the present invention.

[0062] The present specification discloses the following: (1) An insulating sheet comprising a metal substrate layer and a resin composition layer overlying at least one surface of the substrate layer, wherein the resin composition layer contains at least a thermally conductive filler, an epoxy resin, a curing agent, and an additive, and the additive contains at least one selected from the group consisting of a compound having an imidazole structure in its molecule, a compound having a cyano group in its molecule, and a compound having a triazole structure in its molecule. (2) The insulating sheet according to (1) above, wherein the resin composition layer is in a semi-cured state. (3) A semiconductor module comprising the insulating sheet according to (1) or (2) above.

[0063] The present invention will now be described in more detail with reference to experimental examples, but the present invention is not limited to these examples.

[0064] An insulating sheet was produced by preparing a mixture for producing a resin composition layer as follows, applying the prepared mixture to a substrate layer to form a resin composition layer, and volatilizing the organic solvent. The formulation of the resin composition layer for producing the insulating sheet is shown in Table 1.

[0065] <Raw materials for resin composition layer of insulating sheet> [Epoxy resin 1] Trisphenolmethane type epoxy resin (commercially available product) Epoxy equivalent: 169 [g / eq] [Epoxy resin 2] Bisphenol A type epoxy resin (commercially available product) Epoxy equivalent: approximately 190 [g / eq] [Epoxy resin curing agent 1 (phenolic resin)] Phenol novolac resin (commercially available product) Hydroxyl equivalent: 105 [g / eq] [Epoxy resin curing agent 2 (phenolic resin)] Biphenyl aralkyl type phenolic resin (commercially available product) Hydroxyl equivalent: 242 [g / eq] [Additive A (compound having an imidazole structure in the molecule)] 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct (commercially available product) [Additive B (compound having a cyano group in the molecule)] Dicyandiamide (DICY) (commercially available product) [Additive C1 (compound having a triazole structure in the molecule)] Benzotriazole (BTA) (commercially available product) [Additive C2 (compound having a triazole structure in the molecule)] 1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole (manufactured by Johoku Chemical Co., Ltd., product name "BT-LX") [Additive C3 (compound having a triazole structure in the molecule)] Tolyltriazole (TTA) (manufactured by Daiwa Kasei Co., Ltd., product name "VERZONE TTA") [Additive C4 (compound having a triazole structure in the molecule)] 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole (manufactured by Johoku Chemical Co., Ltd., product name "TT-LX") [Additive D (curing accelerator for epoxy resin)] Tetraphenylphosphonium tetraphenylborate (commercially available product) [Thermal conductive filler (inorganic filler)] Boron nitride filler (Showa Denko K.K. product name: Showbn UHP-1K) Average particle size: 8 μm [Silane coupling agent containing glycidyl group] ・3-glycidoxypropyltrimethoxysilane (commercially available product) [Organic solvent] Methyl ethyl ketone (MEK), toluene (TOL)

[0066] <Base layer of insulating sheet> Long copper plate: tough pitch copper C1100 (thickness 3 mm, width 25 mm) The copper plate was subjected to heat treatment in air at a temperature of 220°C for 7 minutes and used as the base layer. The thickness of the oxide film on the surface was 50 nm.

[0067]

[0068] (Examples 1 to 6) A mixture for producing a resin composition layer was prepared by mixing the components at room temperature according to the formulation shown in Table 1. The prepared mixture was then applied to one side and the tip of the copper plate using a coater, and the organic solvent was then volatilized. In this manner, an insulating sheet was produced.

[0069] Comparative Example 1 An insulating sheet was produced in the same manner as in the above-described Example, except that the blending composition of the resin composition layer was changed.

[0070] <Evaluation: Delamination Inhibition Performance Between Substrate Layer and Resin Composition Layer> Measurement samples were prepared using the insulating sheets of each Example and Comparative Example 1, and the delamination inhibition performance between the resin composition layer and the substrate layer was evaluated by measuring shear strength. (Preparation of Measurement Samples) The long copper plate described above was separately prepared, and two copper plates and a resin composition layer (uncured state) were arranged as shown in FIG. 3. Specifically, the two copper plates (2, 2') were arranged so that the longitudinal directions of the two copper plates were aligned and only the tip portion of one copper plate and the tip portion of the other copper plate faced each other, and a resin composition layer (3) was arranged between the facing tip portions. The length of the resin composition layer in the longitudinal direction of the copper plate was 12.5 mm. After temporary pressure bonding by pressing at 120 ° C and 5.9 MPa for 20 minutes, the resin composition layer was further pressure-bonded to the substrate layer at 180 ° C and 5.9 MPa for 120 minutes. In this way, each measurement sample (each measurement sample in the state shown in Figure 3) comprising a semi-cured resin composition layer (thickness 160 μm) and a substrate layer was prepared. The prepared measurement samples were used in the following peel test. (Peel Test (Measurement of Shear Strength)) At least two measurement samples were prepared for each Example and Comparative Example 1, and each measurement sample in the state shown in Figure 3 was subjected to one of the following treatments: 1. Not exposed to a high-temperature environment 2. Exposed to a high-temperature (175°C) environment for 100 hours in the state shown in Figure 3 Then, the measurement samples were left to stand for 24 hours in an environment of 23°C and 50% relative humidity, and a peel test was performed on each measurement sample. In the peel test, the two copper plates of the measurement sample prepared as described above were pulled away from each other in the longitudinal direction using a tensile tester at room temperature (23°C) at a pulling rate of 5 mm / min. The tensile force when the copper plates and the resin composition layer were peeled off was measured. The ultimate shear strength was calculated as the arithmetic average of the two measurements.

[0071] The results of the above evaluation tests are summarized in Figure 4. As can be seen from Figure 4, after a long period of time at high temperature (175°C), the insulating sheets of the examples had a higher tensile force when peeling occurred than the insulating sheets of the comparative examples. In other words, the phenomenon of peeling of the resin composition layer from the copper plate was less likely to occur. It can be said that the insulating sheets of the examples suppress peeling of the resin composition layer from the metal substrate layer after a long period of time in a high-temperature environment.

[0072] The insulating sheet of the present invention is preferably used by being attached to a heat sink provided in a semiconductor module, for example, and is preferably used as a component of a semiconductor module, for example.

[0073] 1: insulating sheet, 2: substrate layer, 3: resin composition layer, 100: semiconductor module.

Claims

1. An insulating sheet comprising a metal base material layer and a resin composition layer overlapping at least one surface of the base material layer, wherein the resin composition layer contains at least a heat conductive filler, an epoxy resin, a curing agent, and an additive, and the additive contains at least one selected from the group consisting of a compound having an imidazole structure in the molecule, a compound having a cyano group in the molecule, and a compound having a triazole structure in the molecule.

2. The insulating sheet according to claim 1, wherein the resin composition layer is in a semi-cured state.

3. A semiconductor module comprising the insulating sheet according to claim 1 or 2.

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