Insulating sheet and semiconductor module

Abstract

Provided is an insulating sheet comprising a copper 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 an epoxy resin and a heat-conductive filler, and the substrate layer has, on a surface section overlapping the resin composition layer, an oxide film that includes a copper oxide and has an average thickness of 30 nm or less.

Description

Insulating sheet and semiconductor module CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from Japanese Patent Application No. 2024-007305, 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. For example, the resin composition layer includes an epoxy resin, a thermally conductive filler, a curing agent, and a curing accelerator.

[0004] Known examples of this type of insulating sheet include an insulating sheet in which a base layer made of a metal foil such as copper foil or aluminum foil and a resin composition layer are laminated together. Specifically, the resin composition layer contains an alumina filler as a thermally conductive filler, a phenolic curing agent as a curing agent, and a specific curing accelerator (see, for example, Patent Document 1).

[0005] In the insulating sheet described in Patent Document 1, the resin composition layer contains an epoxy resin, an alumina filler, a phenolic curing agent, and a specific curing accelerator, and therefore the adhesiveness of the resin composition layer after it is adhered to an adherend can be improved.

[0006] Japanese Patent Application Publication No. 2018-070687

[0007] However, when the insulating sheet described in Patent Document 1 employs a copper metal foil as the substrate layer, the resin composition layer may peel off from the substrate layer in a high-temperature environment, for example, above 100°C. When the insulating sheet is used as a component of, for example, a semiconductor power module in such a high-temperature environment, peeling of the resin composition layer from the substrate layer of the insulating sheet may degrade the performance of the semiconductor power module. Therefore, there is a demand for an insulating sheet in which peeling of the resin composition layer from the copper substrate layer is suppressed 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 copper substrate layer is suppressed in a high-temperature environment.

[0009] In order to solve the above problems, the insulating sheet of the present invention comprises a copper substrate layer and a resin composition layer overlying at least one surface of the substrate layer, the resin composition layer containing at least an epoxy resin and a thermally conductive filler, and the substrate layer has an oxide film containing copper oxide and having an average thickness of 30 nm or less on the surface portion overlying the resin composition layer.

[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 photograph 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] 1 , an insulating sheet 1 of this embodiment includes a copper substrate layer 2 and a resin composition layer 3 overlaid on one surface of the substrate layer 2. The resin composition layer 3 contains at least an epoxy resin and a thermally conductive filler, and the substrate layer 2 has an oxide film containing copper oxide and having an average thickness of 30 nm or less on the surface portion overlaid on the resin composition layer 3. The insulating sheet 1 of this embodiment having such a configuration is inhibited from peeling off the resin composition layer 3 from the copper substrate layer 2 in a high-temperature environment.

[0014] The substrate layer 2 is, for example, a copper foil. The substrate layer 2 is not particularly limited as long as it contains 95% or more copper among its constituent components. The substrate layer 2 may contain metallic copper and copper oxide as constituent components.

[0015] The thickness of the base layer 2 may be, for example, 35 μm or more and 2,000 μm or less.

[0016] An oxide film containing 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 has 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 oxide film is 30 nm or less, may be 25 nm or less, or may be 20 nm or less, and may be 1 nm or more, or may be 2 nm or more.

[0018] The average thickness of the oxide film can be increased by exposing the copper substrate layer 2 to a high-temperature oxygen-containing gas (e.g., air) for a longer period of time, whereas the average thickness of the oxide film can be decreased by exposing the copper substrate layer 2 to a high-temperature oxygen-containing gas for a shorter period of time.

[0019] The average thickness of the oxide film is measured as follows. Specifically, the surface of the substrate layer 2 that overlaps the resin composition layer 3 is measured using an X-ray photoelectron spectroscopy (ESCA, XPS). ２ Both a film composed of copper (I) oxide (CuO) and a film composed of copper (II) oxide (CuO) are oxide films. In measuring the thickness of the oxide film, the total thickness of the film composed of copper (I) oxide and the film composed of copper (II) oxide is measured as the oxide film thickness. When the analysis proceeds from the outermost surface of the base material layer 2 toward the inside, the respective contents of metallic copper and copper oxide are detected at each measurement depth, and the copper oxide content decreases as the measurement depth increases. The measurement depth at which the copper oxide ratio is 50% is taken as the average thickness of the oxide film.

[0020] The analytical conditions for the X-ray photoelectron analyzer were as follows: X-ray source: Monochrome Al Kα X-ray setting: 100 μmφ [15 kV, 25 W] Photoelectron take-off angle: 45 degrees to the sample surface Bond energy correction: The peak derived from the C—C bond in the C1s spectrum was corrected to 285.0 eV Charge neutralization conditions: A neutralization gun and an Ar ion gun (neutralization mode) were used in combination Ar ion gun acceleration voltage: 1 kV Ar ion gun raster size: 1 mm × 1 mm Etching rate of the Ar ion gun: SiO ２ Converted to approximately 5 nm / min

[0021] 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.

[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] 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. As the inorganic filler, boron nitride filler is preferred because it can have better durability, heat dissipation, and surface reactivity. 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 is boron nitride filler. The thermally conductive filler is dispersed in the resin composition layer in the form of primary particles or secondary particles.

[0026] The average particle size of the thermally conductive filler may be, for example, 20 μm or more and 60 μm or less.

[0027] 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.

[0028] 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 this mass ratio of 2 or more and 5 or less, the resin composition layer 3 can have thermal conductivity while also having better adhesiveness due to the fluidity when adhered to an adherend. Moreover, the resin composition layer 3 can have both appropriate heat dissipation and insulation properties. The mass ratio is more preferably 4 or less.

[0029] The resin composition layer 3 of this embodiment preferably further contains a curing agent for the epoxy resin and a curing accelerator. The resin composition layer 3 of this embodiment may further contain a silane coupling agent, an organic solvent, etc.

[0030] 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, and other curing agents. 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. Examples of other curing agents include dicyandiamide (Dicy, also known as cyanoguanidine), imidazoles, and ketimines.

[0031] In this embodiment, a phenolic resin may be used as a curing agent for the epoxy resin. When the curing agent is a phenolic resin, peeling is generally likely to occur between the copper substrate layer 2 and the resin composition layer 3. Even if a phenolic resin is used as the curing agent, the average thickness of the oxide film is 30 nm or less as described above in this embodiment, and therefore the above-mentioned peeling is suppressed.

[0032] Examples of phenolic resins include novolac phenolic resins, aralkyl phenolic resins, and resol phenolic resins. Examples of novolac phenolic resins include phenol novolac resins, cresol novolac resins, bisphenol A novolac resins, and triazine skeleton-containing phenol novolac resins. Examples of aralkyl phenolic resins include biphenyl aralkyl phenolic resins.

[0033] 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

[0034] 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.

[0035] Examples of the epoxy resin curing accelerator include tertiary amine compounds, imidazole compounds, and phosphorus-containing compounds. Examples of the tertiary amine compounds include 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), diazabicycloundecene (DBU) and its salts, diazabicyclononene (DBN) and its salts, and tris(dimethylaminomethyl)phenol. Examples of the imidazole compounds include 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole, 1-(2-cyanoethyl)-2-phenylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and 2-ethyl-4-methylimidazole. Examples of the phosphorus-containing compounds include triphenylphosphine (TPP), tetraphenylphosphonium tetraphenylborate, and tetraphenylphosphonium tetra(4-methylphenyl)borate.

[0036] As the curing accelerator for the epoxy resin, a phosphorus-containing compound (phosphorus-containing curing accelerator) is preferred. When the curing accelerator is a phosphorus-containing compound, the potential reactivity becomes higher, and the reaction rate after the start of the curing reaction can be relatively fast.

[0037] As the curing accelerator for the epoxy resin, commercially available products can be used. For example, commercially available products from reagent manufacturers can be used as the tertiary amine compound or imidazole compound.

[0038] 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.

[0039] As the silane coupling agent, a silane coupling agent containing a glycidyl group is preferred in that it can chemically bond the inorganic filler and the curing agent.

[0040] Examples of organic solvents that may be contained in the resin composition layer 3 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 organic solvents include ethyl acetate, methyl ethyl ketone, and toluene.

[0041] Next, a method for manufacturing the insulating sheet 1 of this embodiment will be described.

[0042] 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.

[0043] As the organic solvent, for example, ethyl acetate, methyl ethyl ketone (MEK), toluene, or the like can be used.

[0044] A general coating method such as a die coating method or a reverse coating method can be used when applying the mixture containing an organic solvent to the base layer 2. The temperature during application is, for example, room temperature (15 to 25° C.).

[0045] The resin composition layer 3 of the insulating sheet 1 of this embodiment may be in an uncured state, i.e., not subjected to a curing treatment such as a heat treatment. Alternatively, the resin composition layer 3 may be in a semi-cured state (B-stage state), in which the curing reaction has progressed partway through the curing treatment. In other words, the resin composition layer 3 may be partially cured by the curing treatment.

[0046] 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.

[0047] Next, an embodiment of a semiconductor module of the present invention will be described with reference to the drawings.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] In this embodiment, the resin composition layer 3 of the insulating sheet 1 is in a semi-cured state (B-stage state) before being adhered to the heat sink 102, and is in a fully cured state (C-stage state) after being adhered to the heat sink 102.

[0053] 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 dissipate heat generated inside the module to the outside. 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 transferred to the other heat sink and dissipated.

[0054] 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.

[0055] The present specification discloses the following: (1) An insulating sheet comprising a copper substrate layer and a resin composition layer overlying at least one surface of the substrate layer, wherein the resin composition layer contains at least an epoxy resin and a thermally conductive filler, and the substrate layer has an oxide film containing copper oxide and having an average thickness of 30 nm or less on a surface portion overlying the resin composition layer. (2) The insulating sheet according to (1) above, wherein the resin composition layer is in a semi-cured state. (3) The insulating sheet according to (1) or (2) above, wherein the resin composition layer further contains a phenolic resin as a curing agent. (4) A semiconductor module comprising the insulating sheet according to any one of (1) to (3) above.

[0056] 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.

[0057] 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.

[0058] <Raw materials for resin composition layer of insulating sheet> [Epoxy resin 1] Trisphenolmethane type epoxy resin (commercially available product) Epoxy equivalent: 167 [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] [Epoxy resin curing accelerator] Tetraphenylphosphonium tetraphenylborate (commercially available product) [Thermal conductive filler (inorganic filler)] Boron nitride filler (manufactured by Showa Denko K.K., product name "SHOBN UHP-1K"), average particle size: 8 μm [Silane coupling agent (containing glycidyl groups)] 3-glycidoxypropyltrimethoxysilane (Commercially available products) [Organic solvents] Methyl ethyl ketone (MEK), toluene

[0059]

[0060] <Insulating Sheet Substrate Layer (Simulated Substrate Layer)> Long copper plate: Tough pitch copper C1100 (thickness 3 mm, width 25 mm) A copper plate that had been heat-treated at 220°C in air and a copper plate that had not been heat-treated were prepared as simulated substrate layers. The average thickness of the oxide film on the substrate layer was adjusted by changing the heat treatment time. Specifically, the average thickness of the oxide film on the substrate layer was increased by extending the heat treatment time.

[0061] Example 1 The above-described long copper plate (simulated substrate layer) that had not been subjected to heat treatment was prepared as the substrate layer. The components were mixed at room temperature (20-30°C) according to the formulation shown in Table 1 to prepare a mixture for producing a resin composition layer. The prepared mixture was then applied to one side and the leading edge of the substrate layer using a coater, and the organic solvent was then volatilized to produce a resin composition layer. In this manner, an insulating sheet comprising a substrate layer and a resin composition layer was produced.

[0062] Example 2 In Example 2, a copper plate (simulated substrate layer) was used that had been heat-treated at 220°C for 2 minutes. That is, a copper plate was used in which the average thickness of the oxide film was thicker than that of Example 1. Except for this point, an insulating sheet was produced in the same manner as in Example 1.

[0063] Comparative Example 1 In Comparative Example 1, a copper plate (simulated substrate layer) was used that had been subjected to a heat treatment at 220°C for 7 minutes. That is, the copper plate used had an oxide film with a thicker average thickness than that of Example 2. Except for this point, an insulating sheet was produced in the same manner as in Example 1.

[0064] Comparative Example 2 In Comparative Example 2, a copper plate (simulated substrate layer) was used that had been subjected to a heat treatment at 220°C for 40 minutes. That is, a copper plate was used in which the average thickness of the oxide film was thicker than that of Comparative Example 1. Except for this point, an insulating sheet was produced in the same manner as in Example 1.

[0065] <Measurement of Average Thickness of Oxide Film> The average thickness of the oxide film was determined by performing elemental analysis of the surface portion of the copper plate using an X-ray photoelectron spectroscopy (ESCA). Details of how to determine the average thickness of the oxide film are as described above. The average thicknesses of the oxide films of the simulated substrate layers (copper plate) were as follows: Example 1: 1 nm / Example 2: 25 nm Comparative Example 1: 65 nm / Comparative Example 2: 190 nm

[0066] The simulated insulating sheets produced in each of the examples and comparative examples were evaluated for their performance in inhibiting separation between the substrate layer and the resin composition layer as follows.

[0067] <Evaluation: Anti-peel performance between the substrate layer and the resin composition layer> The long copper plate (2') described above was separately prepared, and as shown in FIG. 3, the copper plate (2) of the insulating sheet manufactured as described above and the newly prepared copper plate (2') were arranged so that their longitudinal directions were aligned. Furthermore, the two copper plates were arranged so that only the tip portion of one copper plate and the tip portion of the other copper plate faced each other. As a result, a resin composition layer (3) was arranged between the tip portions of the opposing copper plates (2', 2'). The length of the resin composition layer in the longitudinal direction of the copper plate was 12.5 mm. Next, in order to bond the tip portions of the two copper plates to each other via the resin composition layer, a compressive force was applied in the thickness direction to the opposing tip portions of the two copper plates at a temperature of 180 ° C. and a pressure of 5.9 MPa for 120 minutes. In this way, each measurement sample (each measurement sample in the state shown in FIG. 3) with a resin composition layer (semi-cured state) thickness of 160 μm was prepared. (Peel Test) At least three measurement samples were prepared for each Example and Comparative Example, and each measurement sample in the state shown in FIG. 3 was subjected to one of the following treatments: 1. Not exposed to a high-temperature environment (initial state); 2. Exposed to a high-temperature (175°C) environment for 50 hours in the state shown in FIG. 3; 3. Exposed to a high-temperature (175°C) environment for 100 hours in the state shown in FIG. 3. After that, the measurement samples were left to stand for 24 hours in an environment of 23°C and relative humidity 50%, and a peel test was performed on each measurement sample. In the peel test, using a tensile tester, the two copper plates of the measurement sample prepared as described above were pulled away from each other in the longitudinal direction at a pulling rate of 5 mm / min in an environment of room temperature (23°C). The tensile force when the copper plate and the resin composition layer were peeled off was measured. In addition, the state of the resin composition layer when peeled off and the state of the surface portion of the copper plate that was in contact with the resin composition layer were visually confirmed.

[0068] The results of the evaluation tests are shown in Table 2. Figure 4 shows an excerpt of the copper plate after peeling. In Table 2 and Figure 4, the values ​​in MPa indicate the tensile force when peeling occurred between the copper plate and the resin composition layer. "Cohesive failure" indicates that the resin composition layer broke down and peeling occurred, and "interfacial failure" indicates that peeling occurred between the oxide film on the copper plate and the unoxidized metallic copper portion. The two left and right photographs in Figure 4 are enlarged photographs of the tip portions of the two copper plates shown in Figure 3, where the upper and lower plates faced each other. As can be seen from Table 2, after long-term exposure to a high-temperature environment, 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, 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 copper substrate layer in a high-temperature environment.

[0069]

[0070] 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.

[0071] 1: insulating sheet, 2: substrate layer, 3: resin composition layer, 100: semiconductor module.

Claims

1. An insulating sheet comprising a copper-based substrate layer and a resin composition layer overlapping at least one surface of the substrate layer, wherein the resin composition layer contains at least an epoxy resin and a thermally conductive filler, and the substrate layer has an oxide film with an average thickness of 30 nm or less containing copper oxide on the surface portion overlapping the resin composition layer.

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

3. The insulating sheet according to claim 1 or 2, wherein the resin composition layer further contains a phenolic resin as a curing agent.

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

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