Resin Sheet

Abstract

This resin sheet is formed from a resin composition comprising (A) a thermosetting component and (C) a thermally conductive filler. The thermosetting component (A) comprises a maleimide resin. The thermal diffusivity of the resin sheet post-thermosetting is at least 1.0 × 10-6 m2 / s. The resin sheet satisfies the expression (F1) for observation, in a cross section (P) of the resin sheet taken in the direction perpendicular to the resin sheet surface, of a region (P1) that contains two sides of the resin sheet and is bounded by a square for which one side is four times the thickness of the resin sheet. (F1): 0.25 ≤ Ld / Lt ≤ 1 Ld: Length in the aforementioned perpendicular direction of the largest length in the perpendicular direction of the cross-sectional diameters of the thermally conductive filler (C) Lt: Length in the aforementioned perpendicular direction of the resin sheet

Description

[Technical field]

[0001] The present invention relates to a resin sheet. [Background technology]

[0002] It has been considered to blend a highly thermally conductive material such as alumina into a resin sheet used in a power semiconductor. Patent Document 1 proposes the application of a resin sheet, which is a sheet-shaped molded product of an epoxy resin composition containing an alumina filler, to a power semiconductor device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-160440 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the resin composition described in Patent Document 1 does not have sufficient heat resistance when applied to power semiconductor elements that are expected to operate at high temperatures of 200° C. or more. In addition, there were also issues to be addressed, such as further improving thermal conductivity and firmly adhering the resin sheet to an adherend.

[0005] An object of the present invention is to provide a resin sheet that can improve heat resistance, thermal conductivity, and adhesiveness after thermal curing. [Means for solving the problem]

[0006] A resin sheet according to one aspect of the present invention is a resin sheet formed from a resin composition containing (A) a thermosetting component and (C) a thermally conductive filler, wherein the (A) thermosetting component contains a maleimide resin, and the resin sheet has a thermal diffusivity of 1.0×10 after thermal curing. -6 m 2 / s or more, and when observing a region (P1) of a cross section (P) of the resin sheet cut perpendicular to the surface of the resin sheet, the region (P1) is surrounded by a square with one side four times the thickness of the resin sheet and includes two surfaces of the resin sheet, and is characterized in that the condition represented by the following formula (F1) is satisfied. 0.25≦Ld / Lt≦1 (F1) Ld: the length in the vertical direction of the cross-sectional diameter of the thermally conductive filler (C) that is the largest Lt: Length of the resin sheet in the vertical direction

[0007] In the resin sheet according to one embodiment of the present invention, it is preferable that the (A) thermosetting component contains (A1) a first maleimide resin, and the (A1) first maleimide resin is a maleimide resin that is solid at a temperature of 25°C, has two or more maleimide groups in one molecule, and has a bonding group connecting at least one pair of two maleimide groups having four or more methylene groups in the main chain.

[0008] In the resin sheet according to one aspect of the present invention, it is preferable that the (A) thermosetting component further contains (A4) a compound having a triazine skeleton.

[0009] In the resin sheet according to one aspect of the present invention, the compound having a triazine skeleton (A4) is preferably an imidazole compound having a triazine skeleton.

[0010] In the resin sheet according to one aspect of the present invention, it is preferable that the (A) thermosetting component further contains (A5) an allyl resin.

[0011] In the resin sheet according to one aspect of the present invention, it is preferable that the resin composition further contains (C1) boron nitride particles.

[0012] In the resin sheet according to one aspect of the present invention, it is preferable that the resin composition further contains (C2) alumina particles.

[0013] In the resin sheet according to one aspect of the present invention, the total content of the (C1) boron nitride particles and the (C2) alumina particles is preferably 78.5 mass % or more based on the total amount of solids in the resin composition.

[0014] The resin sheet according to one aspect of the present invention is preferably used to encapsulate a semiconductor element, or to be interposed between the semiconductor element and another electronic component.

[0015] The resin sheet according to one aspect of the present invention is preferably used to be interposed between a heat sink and an electronic component.

[0016] In the resin sheet according to one aspect of the present invention, it is preferable that the resin sheet is used for encapsulating a semiconductor element using a compound semiconductor, or for being interposed between the semiconductor element using the compound semiconductor and another electronic component.

[0017] In the resin sheet according to one aspect of the present invention, the resin sheet is preferably a coating film of the resin composition.

[0018] According to one aspect of the present invention, it is possible to provide a resin sheet capable of improving heat resistance, thermal conductivity, and adhesiveness after thermal curing, and a method for producing the same. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic diagram showing a cross section of a resin sheet according to an embodiment of the present invention. [Diagram 2] 1 is a schematic cross-sectional view of a laminate according to an embodiment of the present invention. [Diagram 3] 2 is a scanning electron microscope (SEM) photograph showing a cross section of the resin sheet obtained in Example 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] [Resin composition] First, a resin composition for forming the resin sheet according to the present embodiment will be described. The resin composition according to the present embodiment contains a thermosetting component (A). The thermosetting component (A) according to the present embodiment contains a maleimide resin. In addition, the thermosetting component (A) according to the present embodiment preferably contains a first maleimide resin (A1).

[0021] ((A) Thermosetting component) The thermosetting component (A) (hereinafter may be simply referred to as "component (A)") has the property of forming a three-dimensional network when heated and firmly adhering to an adherend. As described above, the thermosetting component (A) in this embodiment preferably contains the first maleimide resin (A1) (hereinafter may be simply referred to as "component (A1)").

[0022] Maleimide resin The maleimide resin in the present embodiment is not particularly limited as long as it is a maleimide resin containing two or more maleimide groups in one molecule. When the resin composition according to the present embodiment contains the maleimide resin, the heat resistance of the resin sheet according to the present embodiment after thermal curing is improved.

[0023] Examples of the maleimide resin in this embodiment include (A1) a first maleimide resin, (A2) a second maleimide resin, and (A3) a third maleimide resin.

[0024] (A1) First Maleimide Resin The first maleimide resin (A1) in this embodiment is a maleimide resin having two or more maleimide groups in one molecule, and a bonding group connecting at least one pair of two maleimide groups has four or more methylene groups in the main chain. Here, from the viewpoint of flexibility of the cured product, the linking group linking the two maleimide groups preferably has 6 or more methylene groups in the main chain, more preferably has 8 or more methylene groups in the main chain, and particularly preferably has 10 or more methylene groups in the main chain. Moreover, it is more preferable that these methylene groups are linked to form an alkylene group having 4 or more carbon atoms. In this alkylene group, at least one -CH2- may be replaced with -CH2-O- or -O-CH2-. In addition, the linking group connecting the two maleimide groups preferably has one or more side chains from the viewpoint of flexibility of the cured product. Examples of the side chain include an alkyl group and an alkoxy group. Furthermore, when there are two or more side chains, the side chains may be bonded to each other to form an alicyclic structure.

[0025] In addition, the first maleimide resin (A1) in this embodiment must be solid at a temperature of 25°C. It is presumed that the first maleimide resin (A1) being solid at a temperature of 25°C allows the component (A1) to function not only as a thermosetting component but also as a binder component. Since the component (A1) is easily softened, by replacing the binder component with the component (A1), the conformability of the resin sheet before curing to the irregularities of the adherend surface is improved, and this makes it possible to increase the amount of the thermally conductive filler while maintaining the adhesiveness. Therefore, the use of the component (A1) can improve both the thermal conductivity and adhesiveness of the resin sheet. In addition, the component (A1) is also highly compatible with other maleimide resins.

[0026] The first maleimide resin (A1) in this embodiment is preferably represented by the following general formula (A1) from the viewpoints of flexibility and heat resistance of the cured product.

[0027] [ka]

[0028] In the general formula (A1), n 11is an integer of 0 or more, preferably an integer of 1 to 10, and more preferably an integer of 1 to 5. 11 The average value of is preferably 0.5 or more and 5 or less, and more preferably 1 or more and 2 or less. L 11 and L 12 are each independently a substituted or unsubstituted alkylene group having 4 or more carbon atoms, in which at least one -CH2- may be replaced with -CH2-O- or -O-CH2-. From the viewpoint of flexibility of the cured product, the number of carbon atoms in this alkylene group is preferably 6 or more, more preferably 8 or more, and particularly preferably 10 to 30. In addition, when hydrogen of the alkylene group is substituted, the substituent is an alkyl group having 1 to 14 carbon atoms or an alkoxy group having 1 to 14 carbon atoms. Furthermore, these substituents may be bonded to each other to form an alicyclic structure or a heterocyclic structure. X 11 are each independently a group that does not have a substituted or unsubstituted alkylene group having 4 or more carbon atoms (including those in which at least one -CH2- is replaced with -CH2-O- or -O-CH2-), and further preferably a divalent group having a phthalimide group. The phthalimide group also includes groups derived from phthalimide. X 11 Specific examples of the alkyl group include groups represented by the following structural formula (A1-1).

[0029] [ka]

[0030] A specific example of the maleimide resin represented by the general formula (A1) in this embodiment is a compound represented by the following general formula (A1-1-1): This compound is a solid at a temperature of 25°C.

[0031] [ka]

[0032] In the general formula (A1-1-1), n 11 is an integer between 1 and 5 inclusive. Examples of the maleimide resin represented by the general formula (A1-1-1) include "SLK-3000" manufactured by Shin-Etsu Chemical Co., Ltd.

[0033] In this embodiment, the content of the (A1) component in the maleimide resin is preferably 10% by mass or more, more preferably 17.5% by mass or more, and particularly preferably 42.5% by mass or more, based on the total amount of solids in the maleimide resin (i.e., when the amount of non-volatile content of the maleimide resin excluding the solvent is taken as 100% by mass). The content of the (A1) component in the maleimide resin within such a range allows for a further increase in the amount of thermally conductive filler in the resin sheet. The content of the (A1) component in the maleimide resin is preferably 100% by mass or less, more preferably 75% by mass or less, and even more preferably 60% by mass or less, based on the total amount of solids in the maleimide resin.

[0034] From the same viewpoint, the content of the (A1) component in the maleimide resin is preferably 2.5% by mass or more, more preferably 4% by mass or more, and even more preferably 6% by mass or more, based on the total amount of solids in the resin composition (i.e., when the total amount of non-volatiles in the resin composition excluding the solvent is taken as 100% by mass). The content of the (A1) component in the maleimide resin is preferably 15% by mass or less, and more preferably 12% by mass or less, based on the total amount of solids in the resin composition.

[0035] (A2) Second maleimide resin The (A) thermosetting component contained in the resin composition in this embodiment may further contain (A2) a second maleimide resin having a different chemical structure from the (A1) first maleimide resin, from the viewpoint of increasing the storage modulus E' at 250°C of the cured resin sheet. The (A2) second maleimide resin in this embodiment (hereinafter may be simply referred to as "(A2) component") is not particularly limited as long as it is a maleimide resin having a different chemical structure from the (A1) first maleimide resin and containing two or more maleimide groups in one molecule. That is, the (A2) second maleimide resin is a maleimide resin having two or more maleimide groups in one molecule, and the linking group connecting any two maleimide groups does not have four or more methylene groups in the main chain. When the resin sheet contains the (A2) component, the cohesiveness of the resin sheet after curing is improved. Therefore, it is possible to prevent a decrease in adhesion caused by cohesive failure of the resin sheet after curing.

[0036] From the viewpoint of heat resistance, the second maleimide resin (A2) in the present embodiment preferably contains, for example, a benzene ring, and more preferably contains a structure in which a maleimide group is linked to a benzene ring. Also, the maleimide compound preferably has two or more structures in which a maleimide group is linked to a benzene ring.

[0037] The second maleimide resin (A2) in this embodiment is preferably a maleimide resin containing two or more maleimide groups and one or more biphenyl skeletons in one molecule (hereinafter, may be simply referred to as "biphenylmaleimide resin").

[0038] The second maleimide resin (A2) in this embodiment is preferably represented by the following general formula (1) from the viewpoints of heat resistance and adhesiveness.

[0039] [ka]

[0040] In the general formula (1), k is an integer of 1 or more, and the average value of k is preferably 1 to 10, more preferably 1 to 5, and even more preferably 1 to 3. m1 and m2 are each independently an integer of 1 to 2, and more preferably 1. However, the sum of m1 and m2 is 3 or less. n1 and n2 are each independently an integer of 0 to 4, and more preferably an integer of 0 to 2, and more preferably 0. R 1 and R 2 are each independently an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group. 1 are the same or different. 2 are the same or different from each other.

[0041] Specific examples of the maleimide resin represented by the general formula (1) in this embodiment include compounds represented by the following general formula (2) or (3).

[0042] [ka]

[0043] [ka]

[0044] In the general formulas (2) and (3), k is the same as k in the general formula (1). In the general formula (2), n1, n2, R 1 and R 2 are n1, n2, and R in the general formula (1). 1 and R 2 is the same as: An example of the maleimide resin represented by the general formula (3) is "MIR-3000-70" manufactured by Nippon Kayaku Co., Ltd.

[0045] In addition, the second maleimide resin (A2) in this embodiment is also preferably a maleimide resin containing two or more maleimide groups and two or more phenylene groups in one molecule. From the viewpoint of increasing solubility in a solvent and improving sheet formability, it is preferable that the phenylene group has a substituent. Examples of the substituent include alkyl groups such as methyl groups and ethyl groups, and alkylene groups. From the viewpoint of sheet formability, the second maleimide resin (A2) in this embodiment is preferably a maleimide resin having an ether bond between the maleimide group and the phenylene group.

[0046] The maleimide resin containing two or more maleimide groups and two or more phenylene groups in one molecule is represented, for example, by the following general formula (4).

[0047] [ka]

[0048] In the general formula (4), R 3 From R 6 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; L 1 is an alkylene group having 1 to 3 carbon atoms; L 2 and L 3 are each independently an alkylene group having 1 to 2 carbon atoms or an arylene group having 6 to 10 carbon atoms, and p and q are each independently 0 or 1. 1 , L 2 and L 3 Among these, the total number of carbon atoms of the alkylene groups is 3 or less.

[0049] The maleimide resin represented by the general formula (4) in this embodiment is specifically represented by, for example, the following general formula (5) or the following general formula (6).

[0050] [ka]

[0051] [ka]

[0052] In the general formulas (5) and (6), L 1 is an alkylene group having 1 to 3 carbon atoms. In the general formula (5), R 3 From R 6 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0053] (A3) Third Maleimide Resin From the viewpoint of easily maintaining the sheet strength of the resin sheet after heat curing, the thermosetting component (A) contained in the resin composition in this embodiment may further contain (A3) a third maleimide resin having properties different from those of the first maleimide resin (A1). The third maleimide resin (A3) in this embodiment (hereinafter sometimes simply referred to as "component (A3)") has a common chemical structure with the first maleimide resin (A1), but has different properties and is liquid at a temperature of 25°C. By containing component (A3) in the resin sheet, flexibility can be imparted to the resin sheet after curing, embrittlement is suppressed, and strength such as impact resistance is improved.

[0054] That is, the (A3) third maleimide resin in this embodiment is a spacer group-containing maleimide resin having two or more maleimide groups in one molecule, in which a linking group connecting at least one pair of two maleimide groups has four or more methylene groups in the main chain, and which is liquid at a temperature of 25° C. By using a spacer group-containing maleimide resin as the (A3) third maleimide resin, it becomes easier to maintain the sheet strength of the resin sheet after thermal curing. Here, from the viewpoint of flexibility of the resin sheet, the linking group linking the two maleimide groups preferably has six or more methylene groups in the main chain, more preferably has eight or more methylene groups in the main chain, and particularly preferably has ten or more methylene groups in the main chain. Moreover, it is more preferable that these methylene groups are linked to form an alkylene group having four or more carbon atoms. In this alkylene group, at least one -CH2- may be replaced by -CH2-O- or -O-CH2-. In addition, the linking group connecting the two maleimide groups preferably has one or more side chains from the viewpoint of flexibility of the resin sheet. Examples of the side chain include an alkyl group and an alkoxy group. Furthermore, when there are two or more side chains, the side chains may be bonded to each other to form an alicyclic structure or a heterocyclic structure.

[0055] The spacer group-containing maleimide resin in the present embodiment is preferably represented by the following general formula (7) from the viewpoints of flexibility and heat resistance of the resin sheet.

[0056] [ka]

[0057] In the general formula (7), n is an integer of 0 or more, preferably an integer of 1 to 10, and more preferably an integer of 1 to 5. The average value of n is preferably 0.5 to 5, and more preferably 1 to 2. L 4 and L 5are each independently a substituted or unsubstituted alkylene group having 4 or more carbon atoms, in which at least one -CH2- may be replaced with -CH2-O- or -O-CH2-. From the viewpoint of flexibility of the resin sheet, the number of carbon atoms in this alkylene group is preferably 6 or more, more preferably 8 or more, and particularly preferably 10 to 30. In addition, when hydrogen of the alkylene group is substituted, the substituent is an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms. Furthermore, these substituents may be bonded to each other to form an alicyclic structure. Each X is independently a group that does not have a substituted or unsubstituted alkylene group having 4 or more carbon atoms (including those in which at least one -CH2- is replaced with -CH2-O- or -O-CH2-), and is preferably a divalent group having a phthalimide group. The phthalimide group also includes a group derived from phthalimide. Specific examples of X include groups represented by the following structural formula (7-1) or the following general formula (7-2).

[0058] [ka]

[0059] In the general formula (7-2), Y 1 and Y 2 are each independently a hydrogen atom, a methyl group, or an ethyl group, and are preferably a methyl group. Specific examples of the maleimide resin represented by the general formula (7) in this embodiment include compounds represented by the following general formula (7-1-1) or (7-2-1).

[0060] [ka]

[0061] In the general formulas (7-1-1) and (7-2-1), n ​​is an integer of 1 or more and 5 or less. The average value of n is 1 or more and 2 or less. Examples of the maleimide resin represented by the general formula (7-1-1) include "BMI-1500" manufactured by Designer Molecules Inc. and "SLK-1500" manufactured by Shin-Etsu Chemical Co., Ltd. An example of the maleimide resin represented by the general formula (7-2-1) is "BMI-1700" manufactured by Designer Molecules Inc.

[0062] When the (A2) and (A3) components are used in this embodiment, the ratio of the contents of the (A2) and (A3) components in the maleimide resin is, from the viewpoint of achieving both cohesiveness and flexibility of the resin sheet after curing, preferably 25:75 to 75:25 by mass, more preferably 30:70 to 70:30, and particularly preferably 40:60 to 60:40. When the content ratio of the (A2) and (A3) components in the maleimide resin is within such a range, the flexibility of the resin sheet according to this embodiment can be further improved.

[0063] In this embodiment, the content of the maleimide resin in component (A) (the sum of components (A1) to (A3)) is preferably 60 mass % or more, more preferably 65 mass % or more, and particularly preferably 70 mass % or more, based on the total amount of solids in component (A) (i.e., when the amount of non-volatile content of component (A) excluding the solvent is taken as 100 mass %). The content of the maleimide resin in component (A) is preferably 97 mass % or less, more preferably 95 mass % or less, and even more preferably 92.5 mass % or less, based on the total amount of solids in component (A). When the content of the maleimide resin in component (A) is within such a range, the heat resistance after curing of the resin sheet according to this embodiment can be further improved.

[0064] (A4) Compound having a triazine skeleton The resin composition according to the present embodiment preferably contains a compound having a triazine skeleton (A4) from the viewpoint of increasing the peel strength of the resin sheet after thermal curing. The compound having a triazine skeleton (A4) in the present embodiment (hereinafter, sometimes simply referred to as "component (A4)") is not particularly limited as long as it is a compound having a triazine skeleton. From the viewpoint of promoting the polymerization reaction of the maleimide resin and lowering the temperature at which the thermosetting reaction of the resin sheet proceeds and achieving a peel strength after thermal curing, the component (A4) is preferably a compound such as the following. That is, the component (A4) is preferably a compound having a basic group and a triazine skeleton, more preferably a compound having a nitrogen-containing heterocycle and a triazine skeleton, and even more preferably an imidazole compound having a triazine skeleton. The imidazole compound having a triazine skeleton in the present embodiment is not particularly limited as long as it contains a triazine skeleton and an imidazole group and promotes the polymerization reaction of the maleimide resin. Examples of the imidazole compound having a triazine skeleton in this embodiment include a compound represented by the following general formula (A4') (hereinafter, sometimes simply referred to as "component (A4')").

[0065] [ka]

[0066] In the general formula (A4′), R 41 and R 42 are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a hydroxymethyl group, or a phenyl group, preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and more preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. 43 L is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a phenyl group, or an allyl group, preferably an alkyl group having 1 to 10 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms. 41is an alkylene group having 1 to 5 carbon atoms, preferably an alkylene group having 2 to 4 carbon atoms, and more preferably an ethylene group.

[0067] Specific examples of the (A4') component in this embodiment include 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine, 2,4-diamino-6-[2-(2-ethyl-4-methyl-1-imidazolyl)ethyl]-1,3,5-triazine, and 2,4-diamino-6-[2-(2-undecyl-1-imidazolyl)ethyl]-1,3,5-triazine. Among these compounds, from the viewpoint of the peel strength and reaction temperature of the resin sheet, 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine or 2,4-diamino-6-[2-(2-ethyl-4-methyl-1-imidazolyl)ethyl]-1,3,5-triazine is preferred.

[0068] In this embodiment, the content of the compound having a triazine skeleton (A4) in the resin composition is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, based on the total amount of solids in the resin composition (i.e., when the total amount of non-volatiles in the resin composition excluding the solvent is taken as 100% by mass). The upper limit of the content of the compound having a triazine skeleton (A4) is preferably 3% by mass or less, more preferably 2% by mass or less. If the content of the compound having a triazine skeleton (A4) is within the above range, the peel strength of the resin sheet can be further improved and the reaction temperature can be further lowered.

[0069] In the present embodiment, the compound (A4) having a triazine skeleton in the resin composition may be used alone or in combination of two or more.

[0070] (A5) Allyl resin The (A) thermosetting component contained in the resin composition in this embodiment preferably further contains an (A5) allyl resin. The (A5) allyl resin (hereinafter sometimes simply referred to as "(A5) component") is preferably liquid at room temperature. By including an allyl resin in the (A) thermosetting component, it becomes easier to improve the peel strength of the resin sheet after curing while lowering the reaction temperature of the resin sheet according to this embodiment. In addition, by including an (A5) allyl resin, the complex viscosity η of the resin sheet can be appropriately adjusted, and the flowability of the resin sheet when applied to an adherend can be secured, while further improving the heat resistance of the resin sheet after curing.

[0071] In this embodiment, the mass ratio of the maleimide resin to the (A5) allyl resin (maleimide resin / component (A5)) is preferably 1.5 or more, and more preferably 3 or more. The upper limit of the mass ratio (maleimide resin / component (A5)) may be, for example, 50 or less, preferably 25 or less, and more preferably 15 or less. If the mass ratio (maleimide resin / component (A5)) is within the above range, the heat resistance of the resin sheet can be improved. Furthermore, when the mass ratio (maleimide resin / component (A5)) is within the above range, bleeding out of the allyl resin from the resin sheet is also suppressed.

[0072] The allyl resin (A5) in this embodiment is not particularly limited as long as it is a resin having an allyl group. The allyl resin (A5) in this embodiment is preferably, for example, an allyl resin containing two or more allyl groups in one molecule. The allyl resin in the present embodiment is more preferably represented by the following general formula (8), the following general formula (9), or the following general formula (10).

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] In the general formula (8), R 7 and R 8 are each independently an alkyl group, preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and further preferably an alkyl group selected from the group consisting of a methyl group and an ethyl group. In the general formula (9), n3 is 1 or more and 4 or less, preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less. In the allyl resin represented by the general formula (9), the ratio of components in which n3 is 1 is preferably 90 mol % or more.

[0077] Specific examples of the allyl resin (A5) in this embodiment include diallyl bisphenol A (2,2-bis(3-allyl-4-hydroxyphenyl)propane), the allyl phenol resin represented by the general formula (9), and the allyl phenol resin represented by the general formula (10). These allyl resins may be used alone or in combination of two or more.

[0078] The thermosetting component (A) of the present embodiment may contain a thermosetting resin other than the components (A1) to (A3), a curing accelerator other than the component (A4'), and a curable resin other than the component (A5), as long as the object of the present invention is not impaired. The thermosetting resin other than the components (A1) to (A3) may be any thermosetting resin having high heat resistance, such as epoxy resin, benzoxazine resin, cyanate resin, melamine resin, etc. These thermosetting resins may be used alone or in combination of two or more. Examples of the curing accelerator other than the component (A4') include peroxides, phosphonium salts, benzopinacol and its derivatives, and imidazole compounds not having a triazine skeleton (e.g., 2-ethyl-4-methylimidazole, etc.) These curing accelerators can be used alone or in combination of two or more. Examples of the curable resin other than the component (A5) include resins such as phenol resins and resins having a C=C double bond other than the component (A5), as well as amines, acid anhydrides, and formaldehyde, etc. These curable resins can be used alone or in combination of two or more. When a thermosetting resin other than the components (A1) to (A3), a curing accelerator other than the component (A4), or a curing resin other than the component (A5) is used, the content of these is preferably 10 mass % or less, and more preferably 5 mass % or less, based on the total amount of solids in the component (A) (i.e., when the amount of non-volatile content of the component (A) excluding the solvent is taken as 100 mass %).

[0079] In this embodiment, the content of the thermosetting component (A) in the resin composition is preferably 2% by mass or more, more preferably 5% by mass or more, based on the total amount of solids in the resin composition (i.e., when the total amount of non-volatiles in the resin composition excluding the solvent is taken as 100% by mass). The upper limit of the content of the thermosetting component (A) is preferably 40% by mass or less, more preferably 30% by mass or less. When the content of the (A) thermosetting component is within the above range, the handleability, shape retention, and heat resistance of the resin sheet are improved.

[0080] In addition, when using the (A1) component according to this embodiment, the content of the (A) thermosetting component in the resin composition is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more, based on the total amount of solids in the resin composition (i.e., when the total amount of non-volatiles in the resin composition excluding the solvent is taken as 100% by mass). The upper limit of the content of the (A) thermosetting component is preferably 27% by mass or less, more preferably 25% by mass or less, and even more preferably 23% by mass or less. When the content of the (A) thermosetting component is within the above range, the handleability, shape retention, and heat resistance of the resin sheet are improved.

[0081] ((B) Binder Component) In this embodiment, the resin composition may contain a binder component (B) (hereinafter, may be simply referred to as "component (B)") in addition to component (A). When the resin composition of this embodiment further contains binder component (B), film-forming properties are imparted, and the resin composition can be easily molded into a sheet. However, when the resin composition of this embodiment contains component (A1) that also functions as a binder component, the resin composition may not contain a binder component. The binder component (B) of this embodiment is a resin component other than the component (A). The binder component (B) is an oligomer or polymer containing a repeating structure, and preferably has a functional group equivalent of 5000 or more. In this way, when the binder component (B) has a functional group, even if the binder component (B) can be involved in the curing of the resin sheet by heat, in the present invention, the binder component (B) is distinguished from the thermosetting component (A). The (B) binder component can be selected from a wide range of compounds, regardless of whether it is an aliphatic compound or an aromatic compound. The (B) binder component is preferably at least one resin selected from the group consisting of phenoxy resin, acrylic resin, methacrylic resin, polyester resin, urethane resin, and polyamideimide resin, and is more preferably a phenoxy resin from the viewpoint of heat resistance. The polyester resin is preferably a wholly aromatic polyester resin. The (B) binder component can be used alone or in combination of two or more kinds.

[0082] The phenoxy resin is preferably a phenoxy resin having one or more skeletons selected from the group consisting of a bisphenol A skeleton (hereinafter, bisphenol A may be referred to as "BisA"), a bisphenol F skeleton (hereinafter, bisphenol F may be referred to as "BisF"), a biphenyl skeleton, and a naphthalene skeleton, and is more preferably a phenoxy resin having a bisphenol A skeleton and a bisphenol F skeleton.

[0083] The weight average molecular weight (Mw) of the (B) binder component is preferably from 100 to 1,000,000, more preferably from 1,000 to 800,000, and even more preferably from 10,000 to 100,000, from the viewpoint of facilitating adjustment of the complex viscosity of the resin sheet to a desired range. The weight average molecular weight in this specification is a standard polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0084] In the present embodiment, when the binder component (B) is used, the content of the binder component (B) in the resin composition is preferably 1% by mass or more, more preferably 2% by mass or more, based on the total amount of solids in the resin composition (i.e., when the total amount of non-volatiles in the resin composition excluding the solvent is taken as 100% by mass). The upper limit of the content of the binder component (B) is preferably 10% by mass or less, more preferably 5% by mass or less. By setting the content of the (B) binder component in the resin composition within the above range, the complex viscosity of the resin sheet before curing can be easily adjusted to a desired range, and the handleability and sheet formability of the resin sheet are improved.

[0085] (C) Thermally conductive filler In this embodiment, the resin composition preferably contains, in addition to the component (A), a thermally conductive filler (C) (hereinafter, sometimes simply referred to as "component (C)". This component (C) can improve the thermal properties and / or mechanical properties of the resin sheet. Examples of the (C) thermally conductive filler include boron nitride particles, alumina particles, etc. Among these, (C1) boron nitride particles (hereinafter sometimes simply referred to as "component (C1)") and (C2) alumina particles (hereinafter sometimes simply referred to as "component (C2)") are preferred from the viewpoint of improving the thermal diffusivity of the resin sheet. The thermally conductive filler (C) may be used alone or in combination of two or more kinds. The thermally conductive filler (C) may be surface-treated.

[0086] The average particle size of the (C) thermally conductive filler is not particularly limited. The average particle size of the (C1) boron nitride particles is preferably 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.3 μm or more, in terms of d50 value. The upper limit of the average particle size of the (C1) boron nitride particles is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less. The average particle size of the (C2) alumina particles is preferably 3 μm or more, more preferably 4 μm or more, in terms of d50 value, and the upper limit of the average particle size of the (C2) alumina particles is preferably 50 μm or less, more preferably 35 μm or less, and even more preferably 20 μm or less. In this specification, the average particle size of the thermally conductive filler (C) is a value measured by dynamic light scattering.

[0087] The total content of the (C1) boron nitride particles and (C2) alumina particles in the resin composition is preferably 50% by mass or more, more preferably 65% ​​by mass or more, even more preferably 78.5% by mass or more, and particularly preferably 80% by mass or more, based on the total amount of solids in the resin composition (i.e., when the total amount of non-volatile content of the resin composition excluding the solvent is taken as 100% by mass). By making the total content of the (C1) component and the (C2) component in the resin composition equal to or more than the above lower limit, the thermal diffusivity of the resin sheet can be improved. The upper limit of the total content is preferably 90% by mass or less, more preferably 88% by mass or less, even more preferably 86% by mass or less, and particularly preferably 85% by mass or less. By making the total content of the (C1) component and the (C2) component in the resin composition equal to or less than the above upper limit, the thermal diffusivity of the resin sheet can be improved.

[0088] When the resin composition contains both the (C1) boron nitride particles and the (C2) alumina particles, the mass ratio of the (C1) boron nitride particles to the (C2) alumina particles in the resin composition is preferably such that the mass of the (C1) boron nitride particles is 0.1 or more, and more preferably 0.2 or more, when the mass of the (C2) alumina particles is 1. By making the mass ratio equal to or more than the above lower limit, the thermal diffusivity of the resin sheet can be improved. In addition, when the resin composition contains both the (C1) boron nitride particles and the (C2) alumina particles, the upper limit of the mass ratio of the (C1) boron nitride particles to the (C2) alumina particles in the resin composition is preferably 0.75 or less, more preferably 0.6 or less. By controlling the mass ratio to the above upper limit or less, the peel strength of the resin sheet after heat curing can be increased.

[0089] The content of the thermally conductive filler (C) in the resin composition is preferably 50% by mass or more, more preferably 65% ​​by mass or more, even more preferably 78.5% by mass or more, and particularly preferably 80% by mass or more, based on the total amount of solids in the resin composition (i.e., when the total amount of non-volatile content of the resin composition excluding the solvent is taken as 100% by mass). By making the content of the thermally conductive filler (C) in the resin composition equal to or more than the above lower limit, the thermal diffusivity of the resin sheet can be improved. The upper limit of the content of the thermally conductive filler (C) is preferably 90% by mass or less, more preferably 88% by mass or less, even more preferably 86% by mass or less, and particularly preferably 85% by mass or less. By making the content of the thermally conductive filler (C) in the resin composition equal to or less than the upper limit, the peel strength of the resin sheet after thermal curing can be increased.

[0090] ((D) Coupling Agent) In the present embodiment, the resin composition preferably further contains a coupling agent (D) in addition to the components (A) and (C). The coupling agent preferably has a group that reacts with the functional group contained in the above-mentioned (A) thermosetting component, and more preferably has a group that reacts with the functional group contained in the (A) thermosetting component.

[0091] (D) By using the coupling agent, the peel strength between the cured resin sheet and the adherend is improved.

[0092] As the (D) coupling agent, a silane type (silane coupling agent) is preferred from the viewpoint of obtaining the effects of the present invention. The (D) coupling agent may be used alone or in combination of two or more. The amount of the coupling agent as described above is usually 0.1 parts by mass or more, and preferably 0.3 parts by mass or more, per 100 parts by mass of the (A) thermosetting component. The upper limit of the content of the coupling agent is usually 7 parts by mass or less, preferably 5 parts by mass or less, and more preferably 3 parts by mass or less.

[0093] An example of the resin composition according to this embodiment is a resin composition containing only (A) a thermosetting component, (C) a thermally conductive filler, and (D) a coupling agent. Another example of the resin composition according to the present embodiment is a resin composition containing a thermosetting component (A), a thermally conductive filler (C), a coupling agent (D), and components other than the components (A), (C), and (D), as described below.

[0094] (Other Ingredients) In the present embodiment, the resin composition may further contain other components, such as at least one component selected from the group consisting of a crosslinking agent, a pigment, a dye, a defoaming agent, a leveling agent, an ultraviolet absorber, a foaming agent, an antioxidant, a flame retardant, a dispersant, an anti-settling agent, a thickener, and an ion trapping agent. For example, the resin composition may further contain a crosslinking agent in order to adjust the initial adhesiveness and cohesiveness before curing. Examples of the crosslinking agent include organic polyvalent isocyanate compounds, organic polyvalent imine compounds, etc. The crosslinking agent may be used alone or in combination of two or more kinds.

[0095] Examples of the organic polyisocyanate compound include aromatic polyisocyanate compounds, aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds, and trimers of these polyisocyanate compounds, as well as isocyanate-terminated urethane prepolymers obtained by reacting these polyisocyanate compounds with polyol compounds. More specific examples of the organic polyisocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, and lysine isocyanate. The organic polyisocyanate compound may be used alone or in combination of two or more.

[0096] Specific examples of the organic polyimine compound include N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), trimethylolpropane-tri-β-aziridinyl propionate, tetramethylolmethane-tri-β-aziridinyl propionate, and N,N'-toluene-2,4-bis(1-aziridinecarboxamide)triethylenemelamine, etc. The organic polyimine compound may be used alone or in combination of two or more.

[0097] The amount of the crosslinking agent is usually 0.01 parts by mass or more, and preferably 0.1 parts by mass or more, relative to 100 parts by mass of the resin component. The upper limit of the amount of the crosslinking agent is usually 12 parts by mass or less, and preferably 10 parts by mass or less.

[0098] [Resin sheet] The resin sheet according to this embodiment is formed from the resin composition according to this embodiment described above. The resin sheet is preferably made of only the resin composition according to the present embodiment from the viewpoint of conformity to the irregularities of the adherend to which it is attached when it is used for sealing the semiconductor element or for being interposed between the semiconductor element and other electronic components. In other words, the resin sheet is preferably not a composite material such as a combination of a resin composition and a fiber sheet, such as a prepreg.

[0099] In the resin sheet of this embodiment, when observing a cross section (P) of the resin sheet cut perpendicular to the surface of the resin sheet, the region (P1) surrounded by a square with one side four times the thickness of the resin sheet and including two sides of the resin sheet, it is necessary that the condition represented by the following mathematical formula (F1) is satisfied. 0.25≦Ld / Lt≦1 (F1) Ld: (C) The vertical length of the thermally conductive filler with the largest vertical length of the cross-sectional diameter (see Figure 1) Lt: Length of the resin sheet in the vertical direction (see Figure 1)

[0100] If the value of Ld / Lt is less than 0.25, the thermal conductivity is reduced. On the other hand, if the value of Ld / Lt is more than 1, unevenness occurs on the surface of the resin sheet, adversely affecting the adhesiveness. From the same viewpoint, the value of Ld / Lt is preferably 0.29 or more, and more preferably 0.33 or more. The upper limit of the value of Ld / Lt is preferably 0.99 or less, and more preferably 0.95 or less.

[0101] The thermal diffusivity of the resin sheet according to this embodiment after thermal curing is 1.0×10 -6 m 2 / s or more, and must be 1.1×10 -6 m 2 / s or more is preferable, and 1.2×10 -6 m 2 / s or more is more preferable, and 1.3×10 -6 m 2 / s or more is more preferable, and 1.35×10 -6 m 2 / s or more is even more preferable, and 1.5 × 10 -6 m 2 The upper limit of the thermal diffusivity after heat curing is preferably 1×10 -5 m 2 / s or less is preferable, and 8×10 -6 m 2 / s or less is more preferable, and 5×10 -6 m 2 / s or less is more preferable, and 4×10 -6 m 2 / s or less, and even more preferably 3×10 -6 m 2 It is particularly preferable that the ratio is equal to or less than 1 / s. When the thermal diffusivity of the resin sheet after thermal curing is within this range, a cured product having high thermal conductivity can be obtained. The thermal diffusivity of the resin sheet after thermal curing is a characteristic value obtained by the method described in the examples described below.

[0102] The peel strength of the resin sheet according to the present embodiment after heat curing is preferably 1.0 N / 10 mm or more, more preferably 2.0 N / 10 mm or more, even more preferably 3.0 N / 10 mm or more, and particularly preferably 4.0 N / 10 mm or more. The upper limit of the peel strength after heat curing is more preferably 50 N / 10 mm or less, and even more preferably 40 N / 10 mm or less. If the peel strength of the resin sheet according to this embodiment after thermal curing is 1.0 N / 10 mm or more, when the resin sheet is used as a sealing material, it is possible to maintain high adhesion to an adherend. The peel strength of the resin sheet according to this embodiment after thermal curing can be adjusted to within the above range, for example, by adjusting the types (particularly the types of curing accelerators) and amounts of the components used in the resin composition. The peel strength of the resin sheet according to the present embodiment after thermal curing was determined by performing a peel test at a peel angle of 90 degrees between the resin sheet after thermal curing and the adherend using the measurement method described below. Specifically, a test piece was prepared as described in the examples, and the peel test was performed. In the resin sheet according to this embodiment, the resin composition is formed into a sheet, which makes it easy to apply to an adherend, particularly when the adherend has a large area. If the resin composition is in a sheet form, it is preformed into a shape that matches the shape after the sealing process, so that it can be supplied as a sealing material that maintains a certain degree of uniformity simply by applying it. In addition, if the resin composition is in a sheet form, it is easy to handle.

[0103] The method of forming the resin composition into a sheet can be a conventionally known method, and is not particularly limited. From the viewpoint of easily obtaining a thin resin sheet, the resin sheet is preferably a coating film of the resin composition. The resin sheet, which is a coating film of the resin composition, can be obtained by a manufacturing method including a step of applying the resin composition. Here, the coating method is not particularly limited, and a known method can be used. After coating, the coating may be dried as necessary. The drying conditions are also not particularly limited as long as the resin composition is not cured. The resin sheet according to the present embodiment may be a strip-shaped sheet or may be provided in a rolled state. The resin sheet according to the present embodiment wound into a roll can be used by being unwound from the roll and cut to a desired size.

[0104] The thickness of the resin sheet according to the present embodiment is, for example, preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. The thickness is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 120 μm or less. In addition, when the resin sheet is a coating film of a resin composition, it is easy to make the resin sheet thin, and the thickness of the resin sheet according to the present embodiment is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 50 μm or less.

[0105] (Thermosetting conditions) Under the thermosetting conditions of the resin sheet according to this embodiment, the heating temperature is preferably 50°C or higher, more preferably 100°C or higher, even more preferably 130°C or higher, and even more preferably 160°C or higher. Also, the upper limit value of the heating temperature is preferably 300°C or lower, more preferably 250°C or lower, even more preferably 230°C or lower, and even more preferably 210°C or lower. Under the thermosetting conditions of the resin sheet according to this embodiment, the heating time is preferably 10 minutes or longer, and more preferably 20 minutes or longer. Also, the upper limit value of the heating time is preferably 10 hours or shorter, and more preferably 7 hours or shorter. By having the thermosetting conditions of the resin sheet within the above range, it is possible to achieve thermosetting of the resin sheet at low temperature and in a short time.

[0106] [Laminate] FIG. 2 shows a schematic cross-sectional view of the laminate 1 according to this embodiment. The laminate 1 of this embodiment includes a first release material 2, a second release material 4, and a resin sheet 3 provided between the first release material 2 and the second release material 4. The resin sheet 3 is the resin sheet according to this embodiment.

[0107] The first release material 2 and the second release material 4 have releasability, and it is preferable that there is a difference between the release force of the first release material 2 on the resin sheet 3 and the release force of the second release material 4 on the resin sheet 3. The materials of the first release material 2 and the second release material 4 are not particularly limited. The ratio (P2 / P1) of the release force P2 of the second release material 4 to the release force P1 of the first release material 2 is preferably 0.02 ≦ P2 / P1 < 1 or 1 < P2 / P1 ≦ 50.

[0108] The first release material 2 and the second release material 4 may be, for example, a material that has release properties in itself, a material that has been subjected to a release treatment, a material on which a release agent layer is laminated, etc. When the first release material 2 and the second release material 4 have not been subjected to a release treatment, examples of the material for the first release material 2 and the second release material 4 include olefin resins, fluororesins, etc. The first release material 2 and the second release material 4 can be a release material having a release substrate and a release agent layer formed by applying a release agent onto the release substrate. By using a release material having a release substrate and a release agent layer, handling becomes easy. In addition, the first release material 2 and the second release material 4 may have a release agent layer on only one side of the release substrate, or may have a release agent layer on both sides of the release substrate.

[0109] Examples of the release substrate include a paper substrate, a laminated paper obtained by laminating a thermoplastic resin such as polyethylene on the paper substrate, and a plastic film. Examples of the paper substrate include glassine paper, coated paper, and cast-coated paper. Examples of the plastic film include a polyester film (e.g., polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate), and a polyolefin film (e.g., polypropylene and polyethylene). Among these, a polyester film is preferred.

[0110] Examples of the release agent include silicone-based release agents made of silicone resins; long-chain alkyl group-containing compound-based release agents made of compounds containing long-chain alkyl groups, such as polyvinyl carbamates and alkyl urea derivatives; alkyd resin-based release agents made of alkyd resins (e.g., non-convertible alkyd resins and convertible alkyd resins); olefin resins (e.g., polyethylene (e.g., high-density polyethylene, low-density polyethylene, and linear low-density polyethylene), propylene homopolymers having an isotactic structure or a syndiotactic structure, etc.) Examples of the release agents include olefin resin-based release agents composed of crystalline polypropylene resins such as propylene-α-olefin copolymers; rubber-based release agents composed of rubbers such as natural rubber and synthetic rubbers (e.g., butadiene rubber, isoprene rubber, styrene-butadiene rubber, methyl methacrylate-butadiene rubber, and acrylonitrile-butadiene rubber); and acrylic resin-based release agents composed of acrylic resins such as (meth)acrylic acid ester copolymers. These can be used alone or in combination of two or more. Among these, alkyd resin-based release agents are preferred. In particular, when a phenoxy resin is used as the (B) binder component of the resin composition contained in the resin sheet 3, it is preferable to use an alkyd resin-based release agent because there is a concern that the release material may unintentionally peel off before the use of the resin sheet 3 if a general silicone-based release agent is used.

[0111] There is no particular limitation on the thickness of the first release material 2 and the second release material 4. It is usually from 1 μm to 500 μm, and preferably from 3 μm to 100 μm. The thickness of the release agent layer is not particularly limited. When the release agent layer is formed by applying a solution containing a release agent, the thickness of the release agent layer is preferably 0.01 μm or more and 3 μm or less, and more preferably 0.03 μm or more and 1 μm or less.

[0112] The method for manufacturing the laminate 1 is not particularly limited. For example, the laminate 1 is manufactured through the following steps. First, a resin composition is applied onto the first release material 2 to form a coating film. Next, the coating film is dried to form a resin sheet 3. Next, the resin sheet 3 and the second release material 4 are bonded together at room temperature to obtain the laminate 1. In this case, when the types of the release materials of the first release material 2 and the second release material 4 are the same, the ratio (P2 / P1) of the release force P2 of the second release material 4 to the release force P1 of the first release material 2 is likely to be P2 / P1<1. Even if the release materials of the first release material 2 and the second release material 4 are different, the value of P2 / P1 tends to be small because the resin composition is applied to the first release material 2.

[0113] [Effects of this embodiment] According to the resin sheet and laminate of this embodiment, the resin sheet has excellent heat resistance, and the thermal conductivity after heat curing can be improved, and further, the adhesiveness after heat curing can be improved.

[0114] As described above, the resin sheet according to the present embodiment can be suitably used for power semiconductor elements. In other words, in the semiconductor device according to the present embodiment, the semiconductor element is preferably a power semiconductor element. The power semiconductor element is also expected to operate at high temperatures of 200° C. or higher. Heat resistance is required for materials used in semiconductor devices having power semiconductor elements. Since the resin sheet according to the present embodiment has excellent heat resistance, it is suitable for use in covering the power semiconductor element in a semiconductor device or for being interposed between the power semiconductor element and other components. In addition, the resin sheet according to the present embodiment is preferably applied to a plurality of semiconductor elements collectively. For example, if the resin composition is in the form of a sheet, it can be used in a so-called panel level package in which a resin sheet is applied to a structure in which a semiconductor element is arranged in each gap of a frame having a plurality of gaps, and the frame and the semiconductor element are collectively sealed. The semiconductor element may be sealed by a covering for protecting the back surface of a flip-chip type element. A general protective sheet blocks heat generated from the element and the heat is trapped in the element, whereas the resin sheet according to the present embodiment is used as a back surface protective sheet for a flip-chip type element to efficiently dissipate heat generated from the element. Furthermore, the resin sheet according to the present embodiment has excellent thermal conductivity after thermal curing, and therefore can efficiently transfer heat generated from a power semiconductor element to a heat sink, etc. That is, the resin sheet according to the present embodiment has excellent heat resistance and thermal conductivity, and therefore can be used to seal a power semiconductor element that is expected to operate at high temperatures of 200° C. or higher, or can be interposed between the power semiconductor element and other electronic components, and has an excellent ability to transfer heat generated from the power semiconductor element to a heat sink, etc.

[0115] As described above, the resin sheet according to the present embodiment can be suitably used for semiconductor elements using compound semiconductors. In other words, in the semiconductor device according to the present embodiment, the semiconductor element is preferably a semiconductor element using compound semiconductors. Since a semiconductor element using a compound semiconductor has characteristics different from those of a silicon semiconductor element, it is preferably used for applications such as power semiconductor elements, high-output devices for base stations, sensors, detectors, and Schottky barrier diodes. In these applications, attention is also paid to the heat resistance of semiconductor elements using compound semiconductors, and since the resin sheet according to the present embodiment has excellent heat resistance, it is suitably used in combination with a semiconductor element using a compound semiconductor. In addition, since the resin sheet according to the present embodiment has excellent thermal conductivity after thermal curing, heat generated from a semiconductor element using a compound semiconductor can be efficiently transferred to a heat sink or the like. The resin sheet according to the present embodiment is preferably used to seal a semiconductor element using a compound semiconductor. Alternatively, the resin sheet according to the present embodiment is preferably used to be interposed between a semiconductor element using a compound semiconductor and another electronic component. Examples of the other electronic components include a printed wiring board and a lead frame. Since the upper limit of the operating temperature of silicon semiconductor elements is about 175° C., it is preferable to use semiconductor elements using compound semiconductors capable of operating at high temperatures for the power semiconductor elements. Examples of compound semiconductors include silicon carbide, gallium nitride, aluminum gallium nitride, gallium oxide, and gallium arsenide, and it is preferable to use at least one of silicon carbide, gallium nitride, aluminum gallium nitride, and gallium oxide. The resin sheet according to this embodiment has excellent heat resistance and thermal conductivity, and can therefore be used to encapsulate semiconductor elements using compound semiconductors that are expected to operate at high temperatures of 200°C or higher, or can be interposed between semiconductor elements using compound semiconductors and other electronic components, and has an excellent ability to transfer heat generated from these semiconductor elements to heat sinks, etc.

[0116] [Modifications of the embodiment] The present invention is not limited to the above-described embodiment, and any modifications or improvements that can achieve the object of the present invention are included in the present invention.

[0117] In the above embodiment, a laminate having a first release material, a second release material, and a resin sheet disposed between the first release material and the second release material has been described, but the laminate may also have a release material on only one side of the resin sheet.

[0118] In addition, although the semiconductor device embodiment has been described as being used for semiconductor encapsulation, the resin sheet of the present invention can also be used as an insulating material for circuit boards (e.g., a material for a rigid printed wiring board, a material for a flexible wiring board, and an interlayer insulating material for a build-up board, etc.), an adhesive film for build-up, and an adhesive, etc. EXAMPLES

[0119] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0120] [Examples and Comparative Examples] [Preparation of resin composition] Resin compositions according to Examples 1 to 4 were prepared according to the blending ratios shown in Table 1 (% by mass (proportion calculated as solid content)). The materials used in the preparation of the resin composition are as follows:

[0121] (thermosetting component) First maleimide resin: long-chain alkyl maleimide resin (solid at 25°C, maleimide resin represented by the general formula (A1-1-1) above, "SLK-3000" manufactured by Shin-Etsu Chemical Co., Ltd.) Second maleimide resin: a maleimide resin having a biphenyl group (maleimide resin represented by the general formula (3) above, "MIR-3000" manufactured by Nippon Kayaku Co., Ltd.) Third maleimide resin: long-chain alkyl maleimide resin (liquid at a temperature of 25°C, maleimide resin represented by the general formula (7-1-1) above, "SLK-1500" manufactured by Shin-Etsu Chemical Co., Ltd.) Allyl resin: Diallyl bisphenol A ("DABPA" manufactured by Daiwa Chemical Industry Co., Ltd.) Compounds with a triazine skeleton: 2,4-diamino-6-[2-(2-ethyl-4-methyl-1-imidazolyl)ethyl]-1,3,5-triazine ("2E4MZ-A" manufactured by Shikoku Chemical Industries, Ltd.)

[0122] (Coupling Agent) Coupling agent: 3-glycidoxypropyltriethoxysilane

[0123] (Thermal conductive filler) Alumina particles-1: (Showa Denko K.K. "CB-A50S", average particle size (d50): 50 μm) Alumina particles-2: (Showa Denko K.K. "CB-A30S", average particle size (d50): 30 μm) Alumina particles-3: (Showa Denko K.K. "CB-P05", average particle size (d50): 4 μm) Boron nitride particles-1: (Showa Denko K.K. "UHP-2", average particle size (d50): 11 μm) Boron nitride particles-2: (Showa Denko K.K. "UHP-S2", average particle size (d50): 0.7 μm)

[0124] <Evaluation of resin sheets before heat curing> [Preparation of laminate including resin sheet] A resin varnish (a coating solution prepared by dissolving a resin composition in cyclohexanone, solid content concentration was 72 mass%) was applied onto a first release material (a polyethylene terephthalate film having a release layer formed from an alkyd resin-based release agent, thickness 38 μm) using a knife coater, and dried at 90° C. for 1 minute and at 115° C. for 1 minute. The thickness of the resin composition after drying was as shown in Table 1. Immediately after removing from the drying oven, the dried resin composition and a second release material (a polyethylene terephthalate film having a release layer formed from a silicone-based release agent, thickness 38 μm) were laminated at room temperature to produce a laminate in which the first release material, a resin sheet consisting of the resin composition, and a second release material were laminated in this order.

[0125] <Evaluation of resin sheet after heat curing> [Preparation of laminate including resin sheet] A laminate was obtained in the same manner as in the evaluation of the resin composition before heat curing described above.

[0126] [Thickness of resin sheet] The measurements were performed using a constant pressure thickness gauge manufactured by Tecrock Corporation (model number: "PG-02J", standard specifications: compliant with JIS K6783, Z1702, Z1709). [Cross-section observation of resin sheet] One side of the resin sheet in the obtained laminate was bonded to a glass plate by vacuum pressure bonding at a lamination temperature of 130°C (laminating device: "V-130" manufactured by Nikko Materials Co., Ltd.; conditions: ultimate pressure 100 Pa, pressure 0.3 MPa, time 30 seconds), and the resin sheet was cured under thermal curing conditions at a temperature of 200°C for 4 hours. Next, a glass plate was bonded to the other side of the resin sheet with a two-part curing epoxy resin adhesive (manufactured by Konishi Co., Ltd., product name "Quick 5"). The second release material and the first release material of the resin sheet in the laminate were peeled off before being attached to the glass plate. Then, it was used as a sample. This sample was cut perpendicular to the surface of the resin sheet, and the cross section (P) was used with a scanning electron microscope (manufactured by ZEISS, product name "CrossBeam 550") to observe the area (P1) surrounded by a square whose one side is four times the thickness of the resin sheet and includes two sides of the resin sheet. The values ​​of Ld and Lt described below were then measured, and the value of Ld / Lt was calculated. The results are shown in Table 1. A SEM photograph showing a cross section of the resin sheet obtained in Example 4 is shown in FIG. Ld: (C) The vertical length of the thermally conductive filler having the largest vertical length of the cross-sectional diameter Lt: Length of the resin sheet in the vertical direction

[0127] [Measurement of thermal diffusivity of resin sheet after thermal curing] The resin sheets were laminated to a thickness of 200 μm, and cured under heat curing conditions at a temperature of 200° C. for 4 hours to obtain a sample. The first release material and the second release material of the laminate were appropriately removed during the lamination process. The thermal diffusivity of this sample was measured by a temperature wave method using a thermal diffusivity measuring device ("ai-Phase Mobile 1" manufactured by Ai-Phase Co., Ltd.). The results obtained are shown in Table 1.

[0128] [Peel strength measurement] One side of the resin sheet in the obtained laminate was bonded to a copper plate (JIS-C1220P specification, thickness 400 μm) by vacuum pressure bonding at a lamination temperature of 130 ° C. (Laminating device: "V-130" manufactured by Nikko Materials Co., Ltd.; conditions: ultimate pressure 100 Pa, pressure 0.3 MPa, time 30 seconds), and then copper foil (size 50 mm × 10 mm, thickness 150 μm, JIS H 3100 specification) was bonded to the other side of the resin sheet by vacuum pressure bonding under the same conditions as above. The second release material and the first release material of the resin sheet in the laminate were peeled off before being attached to the Si wafer and the copper plate, respectively. The resin sheet was then cured under thermal curing conditions at a temperature of 200 ° C. for 4 hours to prepare a sample. For this sample, the copper foil was peeled off from the cured resin sheet using a tensile tester (Shimadzu Corporation's "Autograph AG-IS") at a peel speed of 50 mm / min and a peel angle of 90 degrees, and the peel strength (unit: N / 10 mm) between the copper foil and the cured resin sheet was measured. The measurement was performed in an environment of 25°C and a relative humidity of 50%. The results are shown in Table 1.

[0129] [Table 1]

[0130] As is clear from the results shown in Table 1, the resin sheets obtained in Examples 1 to 4 had Ld / Lt values ​​in the range of 0.25 or more and 1 or less, high peel strength, and high thermal diffusivity after thermal curing. [Explanation of symbols]

[0131] 1... laminate, 2... first release material, 3... resin sheet, 4... second release material.

Claims

1. A resin sheet formed from a resin composition containing (A) a thermosetting component and (C) a thermally conductive filler, the (A) thermosetting component contains (A1) a first maleimide resin, (A2) a second maleimide resin, and (A3) a third maleimide resin; the (A1) first maleimide resin is a maleimide resin that is solid at a temperature of 25° C., has two or more maleimide groups in one molecule, and at least one pair of two maleimide groups is linked by a bonding group having an alkylene group having 4 or more carbon atoms in its main chain; The second maleimide resin (A2) is represented by the following general formula (1) or the following general formula (4), the third maleimide resin (A3) is a maleimide resin that is liquid at a temperature of 25° C., has two or more maleimide groups in one molecule, and at least one pair of two maleimide groups is linked by a bonding group having an alkylene group having 4 or more carbon atoms in its main chain; The first maleimide resin (A1) and the third maleimide resin (A3) have a common chemical structure, The first maleimide resin (A1) is represented by the following general formula (A1): The third maleimide resin (A3) is represented by the following general formula (7): The thermal diffusivity of the resin sheet after thermal curing is 1.0×10 －６ m ２ / s or more, When observing a region (P1) of a cross section (P) of the resin sheet cut in a direction perpendicular to the surface of the resin sheet, the region (P1) is surrounded by a square whose one side is four times the thickness of the resin sheet and includes two surfaces of the resin sheet, and the region (P1) satisfies the condition represented by the following formula (F1): Resin sheet. 0.25≦Ld / Lt≦1...(F1) Ld: the length in the vertical direction of the cross-sectional diameter of the thermally conductive filler (C) that is the maximum Lt: length of the resin sheet in the vertical direction 【Chemistry 1】 In the general formula (A1), n ​​11 is an integer of 0 or more, and the average value of n 11 is 0.5 or more and 5 or less, L 11 and L 12 are each independently a substituted or unsubstituted alkylene group having 4 or more carbon atoms, in which at least one -CH 2 - may be replaced with -CH 2 -O- or -O-CH 2 -, and when a hydrogen atom of the alkylene group is replaced, the substituent is an alkyl group having 1 to 14 carbon atoms or an alkoxy group having 1 to 14 carbon atoms, and further, these substituents may be bonded to each other to form an alicyclic structure or a heterocyclic structure, and X 11 are each independently a group that does not have a substituted or unsubstituted alkylene group having 4 or more carbon atoms (including those in which at least one -CH 2 - is replaced with -CH 2 -O- or -O-CH 2 -). 【Chemistry 2】 In the general formula (1), k is an integer of 1 or more, the average value of k is 1 or more and 10 or less, m1 and m2 are each independently an integer of 1 or more and 2 or less, with the proviso that the sum of m1 and m2 is 3 or less, n1 and n2 are each independently an integer of 0 or more and 4 or less, R 1 and R 2 are each independently an alkyl group having 1 to 6 carbon atoms, multiple R 1s are the same or different from each other, and multiple R 2s are the same or different from each other. 【Chemistry 3】 In the general formula (4), R 3 to R 6 are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, L 1 is an alkylene group having 1 to 3 carbon atoms, L 2 and L 3 are each independently an alkylene group having 1 to 2 carbon atoms or an arylene group having 6 to 10 carbon atoms, and p and q are each independently 0 or 1, with the proviso that the total carbon number of the alkylene groups among L 1 , L 2 and L 3 is 3 or less. 【Chemistry 4】 In the general formula (7), n is an integer of 0 or more and the average value of n is 0.5 or more and 5 or less, L 4 and L 5 are each independently a substituted or unsubstituted alkylene group having 4 or more carbon atoms, in which at least one -CH 2 - may be replaced with -CH 2 -O- or -O-CH 2 -, and when a hydrogen atom of the alkylene group is replaced, the substituent is an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and further, these substituents may be bonded to each other to form an alicyclic structure, and X is each independently a group that does not have a substituted or unsubstituted alkylene group having 4 or more carbon atoms (including those in which at least one -CH 2 - is replaced with -CH 2 -O- or -O-CH 2 -).

2. The resin sheet according to claim 1, The (A) thermosetting component further contains (A4) a compound having a triazine skeleton. Resin sheet.

3. The resin sheet according to claim 2, The compound (A4) having a triazine skeleton is an imidazole compound having a triazine skeleton. Resin sheet.

4. The resin sheet according to any one of claims 1 to 3, The (A) thermosetting component further contains (A5) an allyl resin. Resin sheet.

5. The resin sheet according to any one of claims 1 to 4, The resin composition further contains (C1) boron nitride particles. Resin sheet.

6. The resin sheet according to claim 5 , The resin composition further contains (C2) alumina particles. Resin sheet.

7. The resin sheet according to claim 6, The total content of the (C1) boron nitride particles and the (C2) alumina particles is 78.5 mass% or more based on the total amount of solids in the resin composition. Resin sheet.

8. The resin sheet according to any one of claims 1 to 7, Used to seal a semiconductor element or to be interposed between the semiconductor element and other electronic components. Resin sheet.

9. The resin sheet according to any one of claims 1 to 7, Used to be placed between a heat sink and an electronic component. Resin sheet.

10. The resin sheet according to any one of claims 1 to 7, It is used to seal a semiconductor element using a compound semiconductor, or to be interposed between the semiconductor element using the compound semiconductor and other electronic components. Resin sheet.

11. The resin sheet according to any one of claims 1 to 10, The resin sheet is a coating film of the resin composition. Resin sheet.

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