Adhesive film, adhesive sheet, and method for manufacturing adhesive sheet

Abstract

To provide an adhesive film which has high adhesion to a fluororesin substrate and is excellent in circuit embedding property, an adhesive sheet, and a method for manufacturing the adhesive sheet.SOLUTION: An adhesive film contains (A) a maleimide compound having a saturated or unsaturated divalent hydrocarbon group, a peroxide, and an inorganic filler, and has minimum melt viscosity in a range of 100 to 135°C and melt viscosity at 100°C and 135°C of 5,000 Pa s or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to an adhesive film, an adhesive sheet, and a method for producing an adhesive sheet. [Background technology]

[0002] The speed and capacity of signals used in mobile communication devices such as mobile phones, their base station equipment, servers, routers and other network infrastructure equipment, large computers and other electronic devices are increasing year by year. Printed wiring board materials used in information and communication devices (antennas, servers, radars, etc.) compatible with the 5th generation mobile communication system are required to have low transmission loss.

[0003] 2. Description of the Related Art Conventionally, resins such as polyphenylene ether (PPE), polyimide (PI), liquid crystal polymer (LCP), and fluororesin have been used for printed wiring boards that require low transmission loss (see, for example, Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 58-69046 [Patent Document 2] JP 2012-255059 A [Patent Document 3] JP 2014-60449 A [Patent Document 4] JP 2003-171480 A Summary of the Invention [Problem to be solved by the invention]

[0005] Fluororesins such as polytetrafluoroethylene (PTFE) are materials with excellent low dielectric constants and low dielectric loss tangents, but are difficult to bond, making it difficult to laminate them with other materials. Therefore, adhesive films with excellent adhesion to fluororesin substrates are required. In addition, adhesive films used as interlayer adhesives are required to fully embed the circuits of printed wiring boards.

[0006] An object of the present disclosure is to provide an adhesive film, an adhesive sheet, and a method for producing an adhesive sheet that have high adhesion to fluororesin substrates and excellent circuit embedding properties. [Means for solving the problem]

[0007] One aspect of the present disclosure relates to the following adhesive film, adhesive sheet, and method for producing the adhesive sheet. [1] (A) An adhesive film containing a maleimide compound having a saturated or unsaturated divalent hydrocarbon group, a peroxide, and an inorganic filler, the adhesive film having a minimum melt viscosity in the range of 100 to 135°C and a melt viscosity at 100°C and 135°C of 5000 Pa s or less. [2] The adhesive film according to [1] above, wherein the minimum melt viscosity is 4000 Pa·s or less. [3] The adhesive film according to the above [1] or [2], wherein the saturated or unsaturated divalent hydrocarbon group has 8 to 100 carbon atoms. [4] The adhesive film according to any one of the above [1] to [3], wherein the saturated or unsaturated divalent hydrocarbon group is a group represented by the following formula (II): [ka] [In formula (II), R2 and R3 each independently represent an alkylene group having 4 to 50 carbon atoms, R4 represents an alkyl group having 4 to 50 carbon atoms, and R5 represents an alkyl group having 2 to 50 carbon atoms.] [5] The adhesive film according to any one of the above [1] to [4], wherein the (A) maleimide compound having a saturated or unsaturated divalent hydrocarbon group further has a divalent group having at least two imide bonds. [6] The adhesive film according to [5] above, wherein the divalent group having at least two imide bonds is a group represented by the following formula (I): [ka] [In formula (I), R1 represents a tetravalent organic group.] [7] An adhesive sheet comprising a supporting substrate and an adhesive layer formed on the supporting substrate, the adhesive layer being made of the adhesive film according to any one of [1] to [6] above. [8] (A) A method for producing an adhesive sheet, comprising the steps of applying a resin composition containing a maleimide compound having a saturated or unsaturated divalent hydrocarbon group, a peroxide, and an inorganic filler onto a supporting substrate, and then drying the resin composition at a temperature of 70°C or higher and lower than 130°C to form an adhesive layer, wherein the adhesive layer has a minimum melt viscosity in the range of 100 to 135°C and a melt viscosity at 100°C and 135°C of 5000 Pa s or less. [9] The method for producing an adhesive sheet according to [8] above, wherein the minimum melt viscosity is 4000 Pa·s or less.

[10] The method for producing an adhesive sheet according to the above [8] or [9], wherein the saturated or unsaturated divalent hydrocarbon group has 8 to 100 carbon atoms. [ka] [In formula (II), R2 and R3 each independently represent an alkylene group having 4 to 50 carbon atoms, R4 represents an alkyl group having 4 to 50 carbon atoms, and R5 represents an alkyl group having 2 to 50 carbon atoms.]

[11] The method for producing an adhesive sheet according to any one of [8] to

[10] above, wherein the (A) maleimide compound having a saturated or unsaturated divalent hydrocarbon group further has a divalent group having at least two imide bonds.

[12] The method for producing an adhesive sheet according to the above

[11] , wherein the divalent group having at least two imide bonds is a group represented by the following formula (I): [ka] [In formula (I), R1 represents a tetravalent organic group.] Effect of the Invention

[0008] According to the present disclosure, it is possible to provide an adhesive film, an adhesive sheet, and a method for producing an adhesive sheet that have high adhesion to fluororesin substrates and excellent circuit embedding properties. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, preferred embodiments of the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In this specification, the term "process" includes not only an independent process, but also a process that cannot be clearly distinguished from other processes, as long as the intended effect of the process is achieved. In this specification, the term "layer" includes a structure having a shape formed on the entire surface as well as a structure having a shape formed on a part of the surface when observed in a plan view. In this specification, the high frequency region refers to a region of 0.3 GHz to 300 GHz, and particularly refers to a region of 3 GHz to 300 GHz.

[0010] In this specification, a numerical range indicated using "~" indicates a range including the numerical values ​​described before and after "~" as the minimum and maximum values, respectively. In a numerical range described in stages in this specification, the upper limit or lower limit of a numerical range of a certain stage may be replaced with the upper limit or lower limit of a numerical range of another stage. In addition, in a numerical range described in this specification, the upper limit or lower limit of the numerical range may be replaced with a value shown in an example. When referring to the amount of each component in a composition in this specification, if a plurality of substances corresponding to each component are present in the composition, the total amount of the plurality of substances present in the composition is meant unless otherwise specified.

[0011] [Adhesive film] The adhesive film according to the present embodiment contains (A) a maleimide compound having a saturated or unsaturated divalent hydrocarbon group, a peroxide, and an inorganic filler, and has a minimum melt viscosity in the range of 100 to 135°C, and the melt viscosity at 100°C and 135°C is 5000 Pa·s or less. Such an adhesive film has excellent adhesion to a conductor layer and a fluororesin substrate, and by having a specific melt viscosity, when used as an interlayer adhesive, it can sufficiently embed the circuit of a printed wiring board. The melt viscosity can be measured by the method described in the examples.

[0012] The minimum melt viscosity of the adhesive film may be 4000 Pa·s or less, 3800 Pa·s or less, 3500 Pa·s or less, or 3200 Pa·s or less from the viewpoint of further improving the circuit embeddability. The minimum melt viscosity of the adhesive film may be 1000 Pa·s or more, 1200 Pa·s or more, 1600 Pa·s or more, or 1800 Pa·s or more from the viewpoint of suppressing exudation of the resin during press molding.

[0013] The melt viscosity of the adhesive film at 100°C may be 4800 Pa·s or less, 4700 Pa·s or less, 4600 Pa·s or less, or 4500 Pa·s or less, from the viewpoint of further improving the circuit embeddability. The melt viscosity of the adhesive film at 100°C may be 1000 Pa·s or more, 1500 Pa·s or more, 1800 Pa·s or more, or 2000 Pa·s or more, from the viewpoint of suppressing the exudation of the resin during press molding. The melt viscosity of the adhesive film at 135°C may be 4800 Pa·s or less, 4500 Pa·s or less, 4200 Pa·s or less, or 4000 Pa·s or less, from the viewpoint of further improving the circuit embeddability. The melt viscosity of the adhesive film at 135°C may be 1000 Pa·s or more, 1500 Pa·s or more, 1800 Pa·s or more, or 2000 Pa·s or more, from the viewpoint of suppressing the exudation of the resin during press molding.

[0014] The adhesive film according to the present disclosure can be produced using a thermosetting resin composition containing (A) a maleimide compound having a saturated or unsaturated divalent hydrocarbon group, a peroxide, and an inorganic filler. Each component contained in the resin composition will be described in detail below.

[0015] ((A) Maleimide Compound Having a Saturated or Unsaturated Divalent Hydrocarbon Group) The maleimide compound having a saturated or unsaturated divalent hydrocarbon group according to this embodiment may be referred to as component (A). Component (A) is a compound having (a) a maleimide group and (c) a saturated or unsaturated divalent hydrocarbon group. The (a) maleimide group may be referred to as structure (a), and the (c) saturated or unsaturated divalent hydrocarbon group may be referred to as structure (c). By using component (A), a resin composition having excellent high-frequency characteristics and adhesiveness may be obtained.

[0016] In addition to the structures (a) and (c), the component (A) may further have (b) a divalent group having at least two imide bonds. (b) The divalent group having at least two imide bonds is sometimes referred to as structure (b).

[0017] The (a) maleimide group is not particularly limited and is a general maleimide group. The (a) maleimide group may be bonded to an aromatic ring or an aliphatic chain, but from the viewpoint of dielectric properties, it is preferable that the (a) maleimide group is bonded to a long-chain aliphatic chain (for example, a saturated hydrocarbon group having 8 to 100 carbon atoms). When the (A) component has a structure in which the (a) maleimide group is bonded to a long-chain aliphatic chain, the high-frequency properties of the resin composition can be further improved.

[0018] Although there is no particular limitation on the structure (b), examples thereof include a group represented by the following formula (I): The structure (b) is a group that does not have a maleimide group.

[0019] [ka]

[0020] In formula (I), R1 represents a tetravalent organic group. R1 is not particularly limited as long as it is a tetravalent organic group, but from the viewpoint of ease of handling, it may be, for example, a hydrocarbon group having 1 to 100 carbon atoms, a hydrocarbon group having 2 to 50 carbon atoms, or a hydrocarbon group having 4 to 30 carbon atoms.

[0021] R1 may contain a substituted or unsubstituted siloxane moiety. Examples of the siloxane moiety include structures derived from dimethylsiloxane, methylphenylsiloxane, diphenylsiloxane, and the like.

[0022] When R1 is substituted, examples of the substituent include an alkyl group, an alkenyl group, an alkynyl group, a hydroxyl group, an alkoxy group, a mercapto group, a cycloalkyl group, a substituted cycloalkyl group, a heterocyclic group, a substituted heterocyclic group, an aryl group, a substituted aryl group, a heteroaryl group, a substituted heteroaryl group, an aryloxy group, a substituted aryloxy group, a halogen atom, a haloalkyl group, a cyano group, a nitro group, a nitroso group, an amino group, an amido group, -CHO, -NR x C(O)-N(R x )2, -OC(O)-N(R x ) 2, acyl groups, oxyacyl groups, carboxy groups, carbamate groups, and sulfonamide groups. x represents a hydrogen atom or an alkyl group. One or more of these substituents can be selected according to the purpose, application, etc.

[0023] R1 is preferably, for example, a tetravalent residue of an acid anhydride having two or more anhydride rings in one molecule, that is, a tetravalent group obtained by removing two acid anhydride groups (-C(=O)OC(=O)-) from an acid anhydride. Examples of the acid anhydride include compounds described below.

[0024] From the viewpoint of mechanical strength, R1 is preferably aromatic, and more preferably a group in which two acid anhydride groups have been removed from pyromellitic dianhydride. That is, structure (b) is more preferably a group represented by the following formula (III).

[0025] [ka]

[0026] From the viewpoint of fluidity and circuit embedding property, it is preferable that a plurality of structures (b) are present in the component (A). In this case, the structures (b) may be the same or different. The number of structures (b) in the component (A) is preferably 2 to 40, more preferably 2 to 20, and further preferably 2 to 10.

[0027] From the viewpoint of dielectric properties, the structure (b) may be a group represented by the following formula (IV) or the following formula (V).

[0028] [ka]

[0029] [ka]

[0030] Structure (c) is not particularly limited, and may be linear, branched, or cyclic. From the viewpoint of high frequency characteristics, structure (c) is preferably an aliphatic hydrocarbon group. In addition, the carbon number of the saturated or unsaturated divalent hydrocarbon group may be 8 to 100. Structure (c) is preferably an alkylene group having 8 to 100 carbon atoms which may be branched, more preferably an alkylene group having 10 to 70 carbon atoms which may be branched, and even more preferably an alkylene group having 15 to 50 carbon atoms which may be branched. When structure (c) is an alkylene group having 8 or more carbon atoms which may be branched, the molecular structure is easily three-dimensional, and the free volume of the polymer is easily increased to reduce the density. In other words, the dielectric constant can be reduced, and the high frequency characteristics of the resin composition are easily improved. In addition, when component (A) has structure (c), the flexibility of the resin composition is improved, and it is possible to increase the handleability (tackiness, cracking, powder fall, etc.) and strength of the adhesive layer (resin film) produced from the resin composition.

[0031] Examples of the structure (c) include alkylene groups such as a nonylene group, a decylene group, an undecylene group, a dodecylene group, a tetradecylene group, a hexadecylene group, an octadecylene group, and a nonadecylene group; arylene groups such as a benzylene group, a phenylene group, and a naphthylene group; arylene alkylene groups such as a phenylenemethylene group, a phenyleneethylene group, a benzylpropylene group, a naphthylenemethylene group, and a naphthyleneethylene group; and arylene dialkylene groups such as a phenylenedimethylene group and a phenylenediethylene group.

[0032] From the viewpoints of high frequency characteristics, low thermal expansion characteristics, adhesion to a conductor, heat resistance, and low moisture absorption, a group represented by the following formula (II) is particularly preferred as the structure (c).

[0033] [ka]

[0034] In formula (II), R2 and R3 each independently represent an alkylene group having 4 to 50 carbon atoms. From the viewpoint of further improving flexibility and ease of synthesis, R2 and R3 each independently represent an alkylene group having 5 to 25 carbon atoms, more preferably an alkylene group having 6 to 10 carbon atoms, and further preferably an alkylene group having 7 to 10 carbon atoms.

[0035] In formula (II), R4 represents an alkyl group having 4 to 50 carbon atoms. From the viewpoint of further improving flexibility and ease of synthesis, R4 is preferably an alkyl group having 5 to 25 carbon atoms, more preferably an alkyl group having 6 to 10 carbon atoms, and further preferably an alkyl group having 7 to 10 carbon atoms.

[0036] In formula (II), R5 represents an alkyl group having 2 to 50 carbon atoms. From the viewpoint of further improving flexibility and ease of synthesis, R5 is preferably an alkyl group having 3 to 25 carbon atoms, more preferably an alkyl group having 4 to 10 carbon atoms, and further preferably an alkyl group having 5 to 8 carbon atoms.

[0037] From the viewpoint of fluidity and circuit embedding property, it is preferable that a plurality of structures (c) are present in the (A) component. In this case, the structures (c) may be the same or different. For example, it is preferable that 2 to 40 structures (c) are present in the (A) component, more preferably 2 to 20 structures (c), and even more preferably 2 to 10 structures (c).

[0038] The content of the (A) component in the resin composition is not particularly limited. From the viewpoint of heat resistance, the content of the (A) component is preferably 2 to 98 mass % based on the total mass of the resin composition, more preferably 10 to 50 mass %, and further preferably 10 to 30 mass %.

[0039] The molecular weight of the component (A) is not particularly limited. From the viewpoints of handling, flowability, and circuit embedding properties, the weight average molecular weight (Mw) of the component (A) is preferably 500 to 10,000, more preferably 1,000 to 9,000, even more preferably 1,300 to 9,000, even more preferably 1,500 to 7,000, and particularly preferably 1,700 to 5,000.

[0040] The Mw of the component (A) can be measured by gel permeation chromatography (GPC).

[0041] The GPC measurement conditions are as follows. Pump: L-6200 type [manufactured by Hitachi High-Technologies Corporation] Detector: L-3300 type RI [Hitachi High-Technologies Corporation] Column oven: L-655A-52 [Hitachi High-Technologies Corporation] Guard column and column: TSK Guardcolumn HHR-L + TSKgel G4000HHR + TSKgel G2000HHR [all manufactured by Tosoh Corporation, product names] Column size: 6.0 x 40 mm (guard column), 7.8 x 300 mm (column) Eluent: Tetrahydrofuran Sample concentration: 30mg / 5mL Injection volume: 20μL Flow rate: 1.00mL / min Measurement temperature: 40℃

[0042] There are no limitations on the method for producing component (A). Component (A) may be produced, for example, by reacting an acid anhydride with a diamine to synthesize an amine-terminated compound, and then reacting the amine-terminated compound with an excess of maleic anhydride.

[0043] Examples of the acid anhydride include pyromellitic anhydride, maleic anhydride, succinic anhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride. The acid anhydride may be used alone or in combination of two or more types according to the purpose, application, etc. As described above, a tetravalent organic group derived from an acid anhydride such as those listed above can be used as R1 in the above formula (I). From the viewpoint of better dielectric properties, the acid anhydride is preferably pyromellitic anhydride.

[0044] Examples of diamines include dimer diamine, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diamino-3,3'-dihydroxybiphenyl, 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, polyoxyalkylene diamine, and [3,4-bis(1-aminoheptyl)-6-hexyl-5-(1-octenyl)]cyclohexene. Depending on the purpose, application, etc., one type of diamine may be used alone, or two or more types may be used in combination.

[0045] The component (A) may be, for example, a compound represented by the following formula (XIII). [ka]

[0046] In formula (XIII), R and Q each independently represent a divalent organic group. R may be the same as in the structure (c) above, and Q may be the same as R1 above. n represents an integer of 1 to 10.

[0047] A commercially available compound can also be used as component (A). Examples of commercially available compounds include products manufactured by Designer Molecules Inc., specifically, BMI-1500, BMI-1700, BMI-3000, BMI-5000, and BMI-9000 (all trade names). From the viewpoint of obtaining better high-frequency characteristics, it is more preferable to use BMI-3000 as component (A).

[0048] ((B) Aromatic Maleimide Compound) The resin composition according to the present embodiment preferably further contains an aromatic maleimide compound (B). The aromatic maleimide compound (B) according to the present embodiment may be referred to as the component (B). The component (B) is a maleimide compound different from the component (A). A compound that can be both the component (A) and the component (B) is considered to belong to the component (A). However, when two or more compounds that can be both the component (A) and the component (B) are included, one of them is considered to belong to the component (A) and the other compounds are considered to belong to the component (B). For example, a compound having an aromatic ring contained in the group represented by formula (I) may be considered to be the component (A), and a compound having an aromatic ring other than the aromatic ring contained in the group represented by formula (I) may be considered to be the component (B). By using the component (B), the hygroscopicity of the resin composition can be reduced. The cured product of the resin composition containing the components (A) and (B) can improve the low moisture absorption while maintaining good dielectric properties by containing a polymer having a structural unit made of the component (A) that has low dielectric properties and a structural unit made of the component (B) that has low moisture absorption.

[0049] The (B) component preferably has a lower thermal expansion coefficient than the (A) component. Examples of the (B) component having a lower thermal expansion coefficient than the (A) component include a maleimide group-containing compound having a lower molecular weight than the (A) component, a maleimide group-containing compound having more aromatic rings than the (A) component, and a maleimide group-containing compound having a shorter main chain than the (A) component.

[0050] The content of the (B) component in the resin composition is not particularly limited. From the viewpoint of low moisture absorption and dielectric properties, the content of the (B) component is preferably 1 to 95 mass %, more preferably 3 to 90 mass %, and further preferably 5 to 85 mass %, based on the total mass of the resin components.

[0051] The blending ratio of the (A) component to the (B) component in the resin composition is not particularly limited. From the viewpoint of low moisture absorption and dielectric properties, the mass ratio of the (A) component to the (B) component (B) / (A) is preferably 0.01 to 3, more preferably 0.03 to 2, and even more preferably 0.05 to 1.

[0052] The (B) component is not particularly limited as long as it has an aromatic ring. Since an aromatic ring is rigid and has low thermal expansion, the thermal expansion coefficient of the resin composition can be reduced by using a (B) component having an aromatic ring. The maleimide group may be bonded to an aromatic ring or an aliphatic chain, but from the viewpoint of low thermal expansion, it is preferable that the maleimide group is bonded to an aromatic ring. In addition, the (B) component may be a polymaleimide compound containing two or more maleimide groups. The (B) component may be used alone or in combination of two or more types.

[0053] Examples of the component (B) include 1,2-dimaleimidoethane, 1,3-dimaleimidopropane, bis(4-maleimidophenyl)methane, bis(3-ethyl-4-maleimidophenyl)methane, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, 2,7-dimaleimidofluorene, N,N'-(1,3-phenylene)bismaleimide, N,N'-(1,3-(4-methylphenylene))bismaleimide, bis(4-maleimidophenyl)sulfone, bis(4-maleimidophenyl)sulfide, bis(4-maleimidophenyl)ether, 1,3-bis(3-maleimidophenoxy)benzene, 1,3-bis(3-(3-maleimidophenoxy)phenoxy)benzene, bis( 4-maleimidophenyl)ketone, 2,2-bis(4-(4-maleimidophenoxy)phenyl)propane, bis(4-(4-maleimidophenoxy)phenyl)sulfone, bis[4-(4-maleimidophenoxy)phenyl]sulfoxide, 4,4'-bis(3-maleimidophenoxy)biphenyl, 1,3-bis(2-(3-maleimidophenyl)propyl)benzene, 1,3-bis(1-(4-(3-maleimidophenoxy)phenyl)-1-propyl)benzene, bis(maleimidocyclohexyl)methane, 2,2-bis[4-(3-maleimidophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, and bis(maleimidophenyl)thiophene. From the viewpoint of further reducing the moisture absorption and the thermal expansion coefficient, bis(3-ethyl-5-methyl-4-maleimidophenyl)methane may be used as the component (B). From the viewpoint of further increasing the breaking strength and metal foil peel strength of the resin film formed from the resin composition, 2,2-bis(4-(4-maleimidophenoxy)phenyl)propane may be used as the component (B).

[0054] From the standpoint of moldability, a compound represented by the following formula (VI) may be used as the component (B).

[0055] [ka]

[0056] In formula (VI), A4 represents a residue represented by the following formula (VII), (VIII), (IX) or (X), and A5 represents a residue represented by the following formula (XI). From the viewpoint of low thermal expansion, A4 may be a residue represented by the following formula (VII), (VIII) or (IX).

[0057] [ka]

[0058] In formula (VII), R 10 each independently represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 5 carbon atoms, or a halogen atom.

[0059] [ka]

[0060] In formula (VIII), R 11 and R 12 each independently represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 5 carbon atoms, or a halogen atom, and A6 represents an alkylene group or alkylidene group having 1 to 5 carbon atoms, an ether group, a sulfide group, a sulfonyl group, a ketone group, a single bond, or a residue represented by the following formula (VIII-1):

[0061] [ka]

[0062] In formula (VIII-1), R 13 and R 14 each independently represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogen atom, and A7 represents an alkylene group having 1 to 5 carbon atoms, an isopropylidene group, an ether group, a sulfide group, a sulfonyl group, a ketone group or a single bond.

[0063] [ka]

[0064] In formula (IX), i is an integer of 1 to 10.

[0065] [ka]

[0066] In formula (X), R 15 and R 16 each independently represents a hydrogen atom or an aliphatic hydrocarbon group having 1 to 5 carbon atoms; and j is an integer of 1 to 8.

[0067] [ka]

[0068] In formula (XI), R 17 and R 18 each independently represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a hydroxyl group, or a halogen atom, and A8 represents an alkylene group or alkylidene group having 1 to 5 carbon atoms, an ether group, a sulfide group, a sulfonyl group, a ketone group, a fluorenylene group, a single bond, a residue represented by the following formula (XI-1) or a residue represented by the following formula (XI-2).

[0069] [ka]

[0070] In formula (XI-1), R 19 and R 20 each independently represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 5 carbon atoms, or a halogen atom, and A9 represents an alkylene group having 1 to 5 carbon atoms, an isopropylidene group, an m-phenylenediisopropylidene group, a p-phenylenediisopropylidene group, an ether group, a sulfide group, a sulfonyl group, a ketone group, or a single bond.

[0071] [ka]

[0072] In formula (XI-2), R 21 each independently represents a hydrogen atom, an aliphatic hydrocarbon group having 1 to 5 carbon atoms, or a halogen atom; A 10 and A 11 each independently represents an alkylene group having 1 to 5 carbon atoms, an isopropylidene group, an ether group, a sulfide group, a sulfonyl group, a ketone group, or a single bond.

[0073] The component (B) may be a compound having an amino group and a maleimide group from the viewpoints of solubility in organic solvents, high frequency characteristics, high adhesion to conductors, etc. The compound having an amino group and a maleimide group can be obtained, for example, by subjecting a bismaleimide compound and an aromatic diamine compound having two primary amino groups to a Michael addition reaction in an organic solvent.

[0074] Examples of aromatic diamine compounds include 4,4'-diaminodiphenylmethane, 4,4'-diamino-3,3'-dimethyl-diphenylmethane, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, and 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline. These may be used alone or in combination of two or more.

[0075] From the viewpoints of high solubility in organic solvents, high reaction rate during synthesis, and high heat resistance, the aromatic diamine compound may be 4,4'-diaminodiphenylmethane or 4,4'-diamino-3,3'-dimethyl-diphenylmethane.

[0076] Examples of organic solvents include alcohol compounds such as methanol, ethanol, butanol, butyl cellosolve, ethylene glycol monomethyl ether, and propylene glycol monomethyl ether; ketone compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and mesitylene; ester compounds such as methoxyethyl acetate, ethoxyethyl acetate, butoxyethyl acetate, and ethyl acetate; and nitrogen-containing compounds such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone. One type of organic solvent may be used alone, or two or more types may be mixed and used. Among these, methyl ethyl ketone, cyclohexanone, propylene glycol monomethyl ether, N,N-dimethylformamide, and N,N-dimethylacetamide are preferred from the viewpoint of solubility.

[0077] (Peroxide) The resin composition according to the present embodiment contains a peroxide as a catalyst for promoting the curing of the component (A). The content of the peroxide is not particularly limited, but may be 0.1 to 5% by mass based on the total mass of the resin composition.

[0078] Examples of peroxides include dicumyl peroxide, dibenzoyl peroxide, 2-butanone peroxide, tert-butyl perbenzoate, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, bis(tert-butylperoxyisopropyl)benzene, and tert-butyl hydroperoxide.

[0079] (Inorganic filler) The resin composition according to the present embodiment contains an inorganic filler, which can improve the low thermal expansion properties, high elastic modulus, heat resistance, flame retardancy, etc. of the adhesive layer. Examples of inorganic fillers include silica, alumina, titanium oxide, mica, beryllia, barium titanate, potassium titanate, strontium titanate, calcium titanate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide, aluminum silicate, calcium carbonate, calcium silicate, magnesium silicate, silicon nitride, boron nitride, calcined clay, talc, aluminum borate, and silicon carbide. These may be used alone or in combination of two or more.

[0080] There is no particular restriction on the shape and particle size of the inorganic filler. The particle size of the inorganic filler may be, for example, 0.01 to 20 μm or 0.1 to 10 μm. The particle size refers to the average particle size, and is the particle size at the point corresponding to 50% volume when the cumulative frequency distribution curve of the particle size is calculated with the total volume of the particles being 100%. The average particle size can be measured by a particle size distribution measuring device using a laser diffraction scattering method.

[0081] When an inorganic filler is used, its amount is not particularly limited, but for example, the content ratio of the inorganic filler is preferably 3 to 75 volume % and more preferably 5 to 70 volume % based on the total solid content in the resin composition. When the content ratio of the inorganic filler in the resin composition is within the above range, good curability, moldability and chemical resistance are easily obtained.

[0082] When an inorganic filler is used, a coupling agent can be used in combination as necessary for the purpose of improving the dispersibility of the inorganic filler and the adhesion to the organic component. As the coupling agent, a silane coupling agent, a titanate coupling agent, etc. can be used. These can be used alone or in combination of two or more. The amount of the coupling agent added can be, for example, 0.1 to 5 parts by mass or 0.5 to 3 parts by mass per 100 parts by mass of the inorganic filler used. Within this range, the deterioration of various properties is small, and the features of the inorganic filler can be easily and effectively exhibited.

[0083] When using a coupling agent, the so-called integral blending method may be used in which the inorganic filler is blended in the resin composition and then the coupling agent is added, but it is preferable to use an inorganic filler that has been surface-treated in advance with the coupling agent in a dry or wet manner. By using this method, the characteristics of the inorganic filler can be more effectively expressed.

[0084] (thermosetting resin) The resin composition according to the present embodiment may further contain a thermosetting resin (C) (hereinafter, sometimes referred to as "component (C)") different from components (A) and (B). Compounds that may fall under component (A) or component (B) are not considered to belong to component (C). By including component (C), the low thermal expansion properties of the resin composition can be further improved. Examples of component (C) include epoxy resins and cyanate ester resins. One type of component (C) may be used alone, or two or more types may be used in combination.

[0085] Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, alicyclic epoxy resins, aliphatic chain epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins, phenol aralkyl type epoxy resins, naphthol novolac type epoxy resins, naphthol aralkyl type epoxy resins, and other naphthalene skeleton-containing epoxy resins, bifunctional biphenyl type epoxy resins, biphenyl aralkyl type epoxy resins, dicyclopentadiene type epoxy resins, and dihydroanthracene type epoxy resins. From the viewpoint of high frequency characteristics and thermal expansion characteristics, naphthalene skeleton-containing epoxy resins or biphenyl aralkyl type epoxy resins may be used.

[0086] Examples of cyanate ester resins include 2,2-bis(4-cyanatophenyl)propane, bis(4-cyanatophenyl)ethane, bis(3,5-dimethyl-4-cyanatophenyl)methane, 2,2-bis(4-cyanatophenyl)-1,1,1,3,3,3-hexafluoropropane, α,α'-bis(4-cyanatophenyl)-m-diisopropylbenzene, cyanate ester compounds of phenol-added dicyclopentadiene polymers, phenol novolac type cyanate ester compounds, and cresol novolac type cyanate ester compounds. Considering the overall balance of low cost, high frequency characteristics, and other characteristics, 2,2-bis(4-cyanatophenyl)propane may be used.

[0087] (hardening agent) When the resin composition according to the present embodiment contains the (C) component, it may further contain a curing agent for the (C) component. This allows the reaction to proceed smoothly when obtaining a cured product of the resin composition, and also allows the physical properties of the cured product of the obtained resin composition to be appropriately adjusted. The curing agent may be used alone or in combination of two or more types.

[0088] Examples of the curing agent for the epoxy resin include polyamine compounds such as diethylenetriamine, triethylenetetramine, diaminodiphenylmethane, m-phenylenediamine, and dicyandiamide; polyphenol compounds such as bisphenol A, phenol novolac resin, cresol novolac resin, bisphenol A novolac resin, and phenol aralkyl resin; acid anhydrides such as phthalic anhydride and pyromellitic anhydride; carboxylic acid compounds; and active ester compounds.

[0089] Examples of the curing agent for the cyanate ester resin include monophenol compounds, polyphenol compounds, amine compounds, alcohol compounds, acid anhydrides, and carboxylic acid compounds.

[0090] (Cure accelerator) The resin composition according to the present embodiment may further contain a curing accelerator depending on the type of component (C). Examples of the curing accelerator for the epoxy resin include imidazole-based curing accelerators, BF3 amine complexes, and phosphorus-based curing accelerators. From the viewpoints of storage stability of the resin composition, handling of the semi-cured resin composition, and solder heat resistance, imidazole-based curing accelerators and phosphorus-based curing accelerators are preferred.

[0091] (thermoplastic resin) The resin composition according to the present embodiment may further contain a thermoplastic resin from the viewpoint of improving the handleability of the resin film. The type of the thermoplastic resin is not particularly limited, and the molecular weight is also not limited, but the number average molecular weight (Mn) may be 200 to 60,000 from the viewpoint of further improving the compatibility with the (A) component.

[0092] From the viewpoint of film forming property and moisture absorption resistance, the thermoplastic resin is preferably a thermoplastic elastomer. Examples of the thermoplastic elastomer include saturated thermoplastic elastomers, and examples of the saturated thermoplastic elastomer include chemically modified saturated thermoplastic elastomers and unmodified saturated thermoplastic elastomers. Examples of the chemically modified saturated thermoplastic elastomer include styrene-ethylene-butylene copolymers modified with maleic anhydride. Specific examples of the chemically modified saturated thermoplastic elastomer include Tuftec M1911, M1913, M1943 (trade names, manufactured by Asahi Kasei Corporation). On the other hand, examples of the unmodified saturated thermoplastic elastomer include unmodified styrene-ethylene-butylene copolymers. Specific examples of the unmodified saturated thermoplastic elastomer include Tuftec H1041, H1051, H1043, H1053 (trade names, manufactured by Asahi Kasei Corporation).

[0093] From the viewpoints of film formability, dielectric properties, and moisture absorption resistance, it is more preferable that the saturated thermoplastic elastomer has a styrene unit in the molecule. In this specification, the styrene unit refers to a unit derived from a styrene monomer in a polymer, and the saturated thermoplastic elastomer refers to a structure in which the aliphatic hydrocarbon portion other than the aromatic hydrocarbon portion of the styrene unit is all constituted by a saturated bond group.

[0094] The content ratio of the styrene unit in the saturated thermoplastic elastomer is not particularly limited, but may be 10 to 80 mass%, 15 to 75 mass%, or 20 to 70 mass%, in terms of the mass percentage of the styrene unit relative to the total mass of the saturated thermoplastic elastomer. When the content ratio of the styrene unit is within the above range, the film appearance, heat resistance, and adhesiveness tend to be excellent.

[0095] A specific example of a saturated thermoplastic elastomer having a styrene unit in the molecule is a styrene-ethylene-butylene copolymer, which can be obtained, for example, by hydrogenating the unsaturated double bonds of the structural units derived from butadiene in a styrene-butadiene copolymer.

[0096] The content of the thermoplastic resin is not particularly limited, but from the viewpoint of further improving the dielectric properties, it may be 0.1 to 15 mass %, 0.3 to 10 mass %, or 0.5 to 5 mass % based on the total solid content of the resin composition.

[0097] (Flame retardant) The resin composition according to the present embodiment may further contain a flame retardant. The flame retardant is not particularly limited, but a bromine-based flame retardant, a phosphorus-based flame retardant, a metal hydroxide, or the like is preferably used. The flame retardant may be used alone or in combination of two or more kinds.

[0098] Examples of brominated flame retardants include brominated epoxy resins such as brominated bisphenol A type epoxy resins and brominated phenol novolac type epoxy resins; brominated additive type flame retardants such as hexabromobenzene, pentabromotoluene, ethylene bis(pentabromophenyl), ethylene bistetrabromophthalimide, 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane, tetrabromocyclooctane, hexabromocyclododecane, bis(tribromophenoxy)ethane, brominated polyphenylene ether, brominated polystyrene, and 2,4,6-tris(tribromophenoxy)-1,3,5-triazine; and brominated reaction type flame retardants containing unsaturated double bond groups such as tribromophenylmaleimide, tribromophenyl acrylate, tribromophenyl methacrylate, tetrabromobisphenol A type dimethacrylate, pentabromobenzyl acrylate, and brominated styrene.

[0099] Examples of phosphorus-based flame retardants include aromatic phosphoric acid esters such as triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, cresyl di-2,6-xylenyl phosphate, and resorcinol bis(diphenyl phosphate); phosphonic acid esters such as divinyl phenylphosphonate, diallyl phenylphosphonate, and bis(1-butenyl) phenylphosphonate; phosphinic acid esters such as phenyl diphenylphosphinate, methyl diphenylphosphinate, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide derivatives; phosphazene compounds such as bis(2-allylphenoxy)phosphazene and dicresylphosphazene; and phosphorus-based flame retardants such as melamine phosphate, melamine pyrophosphate, melamine polyphosphate, melam polyphosphate, ammonium polyphosphate, phosphorus-containing vinylbenzyl compounds, and red phosphorus. Examples of metal hydroxide flame retardants include magnesium hydroxide and aluminum hydroxide.

[0100] The resin composition according to the present embodiment can be obtained by uniformly dispersing and mixing the above-mentioned components. The preparation means and conditions of the resin composition are not particularly limited. The resin composition may be prepared, for example, by thoroughly and uniformly stirring and mixing the components in a predetermined amount with a mixer or the like, kneading the mixture with a mixing roll, an extruder, a kneader, a roll, an extruder, or the like, and then cooling and pulverizing the kneaded mixture.

[0101] [Adhesive sheet] The adhesive film according to the present embodiment can be used in the form of an adhesive sheet comprising a supporting substrate and an adhesive layer made of the above-mentioned adhesive film provided on the supporting substrate. The adhesive layer is formed by applying the above-mentioned resin composition onto the supporting substrate and drying the formed resin layer.

[0102] The method for producing an adhesive sheet according to this embodiment includes the steps of: applying (A) a resin composition containing a maleimide compound having a saturated or unsaturated divalent hydrocarbon group, a peroxide, and an inorganic filler onto a supporting substrate, and then drying the resin composition at a temperature of 70° C. or higher and lower than 130° C. to form an adhesive layer (adhesive film). The adhesive layer made of the adhesive film has a minimum melt viscosity in the range of 100 to 135° C., and the melt viscosity at 100° C. and 135° C. is 5000 Pa s or less.

[0103] The minimum melt viscosity of the adhesive layer may be 4000 Pa·s or less, 3800 Pa·s or less, 3500 Pa·s or less, or 3200 Pa·s or less from the viewpoint of further improving the circuit embeddability. The minimum melt viscosity of the adhesive layer may be 1000 Pa·s or more, 1200 Pa·s or more, 1600 Pa·s or more, or 1800 Pa·s or more from the viewpoint of suppressing exudation of the resin during press molding.

[0104] The melt viscosity of the adhesive layer at 100°C may be 4800 Pa·s or less, 4700 Pa·s or less, 4600 Pa·s or less, or 4500 Pa·s or less, from the viewpoint of further improving the circuit embeddability. The melt viscosity of the adhesive layer at 100°C may be 1000 Pa·s or more, 1500 Pa·s or more, 1800 Pa·s or more, or 2000 Pa·s or more, from the viewpoint of suppressing the exudation of the resin during press molding. The melt viscosity of the adhesive layer at 135°C may be 4800 Pa·s or less, 4500 Pa·s or less, 4200 Pa·s or less, or 4000 Pa·s or less, from the viewpoint of further improving the circuit embeddability. The melt viscosity of the adhesive layer at 135°C may be 1000 Pa·s or more, 1500 Pa·s or more, 1800 Pa·s or more, or 2000 Pa·s or more, from the viewpoint of suppressing the exudation of the resin during press molding.

[0105] A resin layer is formed by applying the resin composition onto a support substrate using a kiss coater, a roll coater, a comma coater, or the like. The support substrate on which the resin layer is formed is dried in a heating and drying oven or the like at a temperature of 70°C or higher and lower than 130°C to form an adhesive layer having a predetermined melt viscosity. The drying temperature for the resin layer is preferably 75 to 125°C, more preferably 80 to 120°C. The drying time can be adjusted depending on the temperature, and may be, for example, 1 to 30 minutes, 2 to 20 minutes, or 3 to 15 minutes. This makes it possible to obtain an adhesive film in which the resin composition is in a semi-cured state.

[0106] The thickness of the adhesive film (adhesive layer) is not particularly limited, and may be, for example, 1 to 200 μm, 3 to 180 μm, 5 to 150 μm, 10 to 100 μm, or 15 to 80 μm.

[0107] The material of the support substrate is not particularly limited, and examples thereof include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate; polyolefins such as polyethylene and polypropylene; polycarbonate, polyamide, polyimide, polyamideimide, polyetherimide, polyethersulfide, polyethersulfone, polyetherketone, polyphenylene ether, polyphenylene sulfide, polyarylate, polysulfone, and liquid crystal polymers. Among these, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polypropylene are preferred from the viewpoints of flexibility and toughness.

[0108] The thickness of the supporting substrate is not particularly limited, and may be, for example, 5 to 100 μm, 10 to 80 μm, or 20 to 50 μm.

[0109] The adhesive sheet may be a laminated film having a three-layer structure consisting of a supporting substrate, an adhesive film, and a protective film, whereby a protective film is attached onto the adhesive film, if necessary.

[0110] The material of the protective film is not particularly limited, and examples thereof include polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefins such as polyethylene and polypropylene. Among these, polyesters such as polyethylene terephthalate; and polyolefins such as polyethylene and polypropylene are preferred from the viewpoint of flexibility and toughness. From the viewpoint of improving the peelability from the adhesive film, a protective film that has been subjected to a release treatment with a silicone compound, a fluorine-containing compound, or the like may be used as necessary.

[0111] The dielectric constant of the cured product of the adhesive film (cured adhesive layer) is not particularly limited, but from the viewpoint of suitable use in the high frequency band, the dielectric constant at 10 GHz is preferably 3.6 or less, more preferably 3.1 or less, and even more preferably 3.0 or less. The lower limit of the dielectric constant is not particularly limited, but may be, for example, about 1.0. In addition, from the viewpoint of suitable use in the high frequency band, the dielectric loss tangent of the cured product of the adhesive film is preferably 0.004 or less, more preferably 0.003 or less. The lower limit of the dielectric constant is not particularly limited, but may be, for example, about 0.0001.

[0112] The adhesive film according to the present embodiment can be suitably used as an interlayer adhesive for a printed wiring board, which includes, as a component, a laminate formed of a metal part forming an electric circuit (conductor circuit) and a resin base material.

[0113] The substrate layer in the printed wiring board can be any resin that has been conventionally used as a substrate for printed wiring boards. Examples of the resin for the substrate layer include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, and fluorine-based resin such as polytetrafluoroethylene (PTFE).

[0114] The adhesive layer made of the adhesive film according to this embodiment has particularly excellent adhesion to conductor layers and fluororesin substrates, and can adequately embed the circuits of a printed wiring board.

[0115] Although the preferred embodiments of the present invention have been described above, these are merely examples for the purpose of explaining the present invention, and the scope of the present invention is not limited to these embodiments. The present invention can be embodied in various forms different from the above-described embodiments without departing from the gist of the present invention. EXAMPLES

[0116] The present invention will be described in more detail below with reference to examples and comparative examples, although the present invention is not limited to the following examples.

[0117] [Resin composition] Into a container equipped with a stirrer, 104.4 g of silica slurry (manufactured by Admatechs Co., Ltd., product name "SC-2050KNK"), 9.1 g of toluene, 21.3 g of a maleimide compound having a structure represented by the following formula (XII-3) (manufactured by Designer Molecules Inc., product name "BMI-3000"), 5.1 g of 2,2-bis(4-(4-maleimidophenoxy)phenylpropane (manufactured by Daiwa Chemical Industry Co., Ltd., product name "BMI-4000"), and 0.53 g of 2,5'-dimethyl-2,5-di(t-butylperoxy)hexane (manufactured by NOF Corporation, product name "Perhexyne 25B") were added and mixed at 25°C for 1 hour. The mixture was filtered using a #200 nylon mesh to obtain a resin composition.

[0118] [ka]

[0119] [Adhesive sheet] Example 1 The resin composition was applied onto a PET film (manufactured by Toyobo Co., Ltd., product name "G2-38", thickness: 38 μm) using a comma coater to form a resin layer, which was then dried at 80°C for 4 minutes to produce an adhesive sheet with a 65 μm-thick adhesive layer (adhesive film).

[0120] Example 2 An adhesive sheet was produced in the same manner as in Example 1, except that the drying temperature was changed to 100° C. and the drying time was changed to 1.5 minutes.

[0121] Example 3 An adhesive sheet was produced in the same manner as in Example 1, except that the drying temperature was changed to 110° C. and the drying time was changed to 1.5 minutes.

[0122] Example 4 An adhesive sheet was produced in the same manner as in Example 1, except that the drying temperature was changed to 120° C. and the drying time was changed to 1.5 minutes.

[0123] Comparative Example 1 An adhesive sheet was produced in the same manner as in Example 1, except that the drying temperature was changed to 130° C. and the drying time was changed to 1.5 minutes.

[0124] [evaluation] The adhesive sheets of the examples and comparative examples were subjected to the following evaluations. The results are shown in Table 1.

[0125] (Melt Viscosity) The PET film was removed from the adhesive sheet to leave only the adhesive film, and the melt viscosity of this adhesive film was measured using a viscoelasticity measuring device (manufactured by TA Instruments, product name "ARES-G2") under the following conditions: heating rate: 3°C / min, temperature range: 30 to 200°C, load: 0.2 N, frequency: 1 Hz, strain: 1%.

[0126] (Adhesion to PTFE substrate) One inner layer copper foil (thickness: 12 μm, Ra: 0.5 μm) and two single-sided copper-clad PTFE substrates (PTFE substrate thickness: 76 μm) were prepared. On the side of one single-sided copper-clad PTFE substrate not having copper foil, an adhesive film with a peeled PET film and an inner layer copper foil were placed in this order, and heated and pressed under conditions of 230 ° C, 2.0 MPa, and 80 minutes to produce a laminate. The copper foil on the single-sided copper-clad PTFE substrate side of the laminate was subjected to the same roughening treatment as the inner layer copper foil used previously (Ra: 0.5 μm). On the surface of the roughened copper foil, an adhesive film with a peeled PET film and another single-sided copper-clad PTFE substrate were placed in this order, and heated and pressed under conditions of 230 ° C, 2.0 MPa, and 80 minutes to produce a fluororesin substrate laminate in which the outer layer copper foil, PTFE substrate, adhesive layer, inner layer copper foil, PTFE substrate, adhesive layer, and inner layer copper foil were laminated in this order. The inner layer copper foil was placed so that the surface that had been subjected to the roughening treatment (Ra: 0.5 μm) was in contact with the adhesive layer, and then heated and pressed.

[0127] The fluororesin substrate laminate was cut into 50 mm squares to prepare test pieces. The test pieces were passed through a 260°C reflow oven 10 times to check for peeling at the interface between the PTFE substrate and the adhesive layer. If there was no peeling, it was judged as "OK", and if there was peeling or swelling, it was judged as "NG".

[0128] (Circuit embedding) A 250 mm square embedded evaluation board having circuit patterns with 20% and 90% copper residual ratios on both sides was prepared. An adhesive film and copper foil were placed on both sides of the evaluation board to obtain a laminate in the order of copper foil, adhesive film, evaluation board, adhesive film, and copper foil. The laminate was then heated and pressurized at 230°C, 3.0 MPa, and 80 minutes. The copper foil on both sides of the laminate after molding was removed by etching and observed under a microscope. The case where the circuit pattern was embedded with the cured adhesive film and had no voids was evaluated as "A," and the case where the circuit pattern was not embedded with the cured adhesive film and had voids was evaluated as "B."

[0129] [Table 1]

Claims

1. (A) An adhesive film containing a maleimide compound having a saturated or unsaturated divalent hydrocarbon group, a peroxide, and an inorganic filler, An adhesive film having a minimum melt viscosity in the range of 100 to 135°C, and a melt viscosity at 100°C and 135°C of 5000 Pa·s or less.

2. 2. The adhesive film according to claim 1, wherein the minimum melt viscosity is 4000 Pa·s or less.

3. 2. The adhesive film according to claim 1, wherein the saturated or unsaturated divalent hydrocarbon group has 8 to 100 carbon atoms.

4. 2. The adhesive film according to claim 1, wherein the saturated or unsaturated divalent hydrocarbon group is a group represented by the following formula (II): 【Chemistry 1】 [In formula (II), R ２ and R ３ each independently represents an alkylene group having 4 to 50 carbon atoms; R ４ represents an alkyl group having 4 to 50 carbon atoms; R ５ represents an alkyl group having 2 to 50 carbon atoms.

5. 2. The adhesive film according to claim 1, wherein the maleimide compound (A) having a saturated or unsaturated divalent hydrocarbon group further has a divalent group having at least two imide bonds.

6. The adhesive film according to claim 5 , wherein the divalent group having at least two imide bonds is a group represented by the following formula (I): 【Chemistry 2】 [In formula (I), R １ represents a tetravalent organic group.

7. An adhesive sheet comprising a supporting substrate and an adhesive layer formed on the supporting substrate, the adhesive layer being made of the adhesive film according to any one of claims 1 to 6.

8. (A) a step of applying a resin composition containing a maleimide compound having a saturated or unsaturated divalent hydrocarbon group, a peroxide, and an inorganic filler onto a supporting substrate, and then drying the applied resin composition at a temperature of 70° C. or higher and lower than 130° C. to form an adhesive layer; The adhesive layer has a minimum melt viscosity in the range of 100 to 135°C, and has a melt viscosity of 5000 Pa·s or less at 100°C and 135°C.

9. The method for producing an adhesive sheet according to claim 8 , wherein the minimum melt viscosity is 4000 Pa·s or less.

10. 10. The method for producing an adhesive sheet according to claim 8, wherein the saturated or unsaturated divalent hydrocarbon group has 8 to 100 carbon atoms. 【Chemistry 3】 [In formula (II), R ２ and R ３ each independently represents an alkylene group having 4 to 50 carbon atoms; R ４ represents an alkyl group having 4 to 50 carbon atoms; R ５ represents an alkyl group having 2 to 50 carbon atoms.

11. 10. The method for producing an adhesive sheet according to claim 8, wherein the maleimide compound (A) having a saturated or unsaturated divalent hydrocarbon group further has a divalent group having at least two imide bonds.

12. The method for producing an adhesive sheet according to claim 11 , wherein the divalent group having at least two imide bonds is a group represented by the following formula (I): 【Chemistry 4】 [In formula (I), R １ represents a tetravalent organic group.

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