Curable resin composition, cured product, varnish, prepreg, and circuit board

Abstract

To provide a curable resin composition that is capable of yielding a cured product having excellent heat resistance (high glass transition temperature) and excellent dielectric characteristics (low dielectric characteristics).SOLUTION: A curable resin composition comprises: a curable resin (A) having an indane skeleton represented by general formula (1); and a maleimide compound (B). (In general formula (1), X represents a (meth)acryloyl group; Ra and Rb each independently represent an alkyl group, an aryl group, an aralkyl group, or a cycloalkyl group having 1 to 12 carbon atoms; j represents an integer of 1 to 3; k and l each independently represent an integer of 0 to 4; n represents an average number of repeating units, which is a numerical value of 0.5 to 20; and m represents an integer of 0 to 2, where the straight lines from Ra, X, and the carbon atom to the aromatic ring indicate that attachment may occur at any position on the aromatic ring.)SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a curable resin composition, and a cured product, varnish, prepreg, and circuit board obtained using the curable resin composition. [Background technology]

[0002] With the increase in the volume of information and communication in recent years, information and communication in the high frequency band has become more prevalent. This has created a demand for electrical insulating materials with better electrical properties, particularly low dielectric constant and low dielectric tangent, in order to reduce transmission loss in the high frequency band.

[0003] Furthermore, printed circuit boards and electronic components using these electrical insulating materials are exposed to high-temperature solder reflow during mounting, so materials with excellent heat resistance and a high glass transition temperature are required. In particular, lead-free solders with high melting points have recently been used from the perspective of environmental issues, so there has been an increasing demand for electrical insulating materials with higher heat resistance.

[0004] In response to these demands, vinyl group-containing curable resins having various chemical structures have been proposed, such as divinylbenzyl ether of bisphenol or polyvinylbenzyl ether of novolac (see, for example, Patent Documents 1 and 2).

[0005] In order to improve the dielectric properties and the like of vinylbenzyl ethers having the above-mentioned improved properties, several polyvinylbenzyl ethers having specific structures have been proposed (see, for example, Patent Documents 3 to 5).

[0006] Furthermore, in order to improve heat resistance and dielectric properties, a curable resin having a specific indane skeleton has also been proposed (for example, Patent Document 6). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 63-68537 [Patent Document 2] Japanese Patent Application Publication No. 64-65110 [Patent Document 3] Special Publication No. 1-503238 [Patent Document 4] Japanese Patent Application Publication No. 9-31006 [Patent Document 5] JP 2005-314556 A [Patent Document 6] International Publication No. 2021 / 205806 Summary of the Invention [Problem to be solved by the invention]

[0008] Thus, attempts have been made to suppress the dielectric tangent and improve the heat resistance. However, the techniques of Patent Documents 1 to 5 have not yet achieved sufficient improvement in these properties, and further improvement in heat resistance is desired for the technique of Patent Document 6.

[0009] Therefore, an object of the present invention is to provide a curable resin composition that can provide a cured product having excellent heat resistance (high glass transition temperature) and dielectric properties (low dielectric properties). [Means for solving the problem]

[0010] Therefore, the present inventors conducted intensive research to solve the above problems, and as a result, found that a cured product obtained from a curable resin composition containing a curable resin having a specific indane skeleton and a maleimide compound has excellent heat resistance (high glass transition temperature) and dielectric properties (low dielectric properties), and thus completed the present invention.

[0011] That is, the gist of the present invention is as follows. [1] A curable resin composition comprising a curable resin (A) having an indane skeleton represented by the following general formula (1) and a maleimide compound (B): [ka] (In the above formula (1), X represents a (meth)acryloyl group. Ra and Rb each independently represent an alkyl group, an aryl group, an aralkyl group or a cycloalkyl group having 1 to 12 carbon atoms. j represents an integer of 1 to 3, k and l each independently represent an integer of 0 to 4. n is the average number of repeating units and represents a value of 0.5 to 20, and m represents an integer of 0 to 2. Note that Ra, X and the straight lines from the carbon atoms to the aromatic ring indicate that they may be bonded to any position on the aromatic ring.) [2] The curable resin composition according to [1], wherein (A) is a curable resin having an indane skeleton represented by the following general formula (2): [ka] (In the above formula (2), R1 and R2 are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group, an aralkyl group, or a cycloalkyl group, and R1 and R2 are not both hydrogen atoms at the same time, and n is the average number of repeating units and is a value of 0.5 to 20.) [3] The curable resin composition according to [1] or [2], wherein (B) is one or more bismaleimide compounds selected from the group consisting of 4,4'-diphenylmethane bismaleimide, m-phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 1,6'-bismaleimide-(2,2,4-trimethyl)hexane, 4,4'-diphenyl ether bismaleimide, 4,4'-diphenylsulfone bismaleimide, 1,3-bis(3-maleimidophenoxy)benzene, and 1,3-bis(4-maleimidophenoxy)benzene. [4] The curable resin composition according to any one of [1] to [3], wherein (B) is a maleimide compound having an indane skeleton. [5] The curable resin composition according to any one of [1] to [4], wherein the mass of (B) is 10 to 80 parts by mass per 100 parts by mass of the total of the mass of (A) and the mass of (B). [6] A cured product obtained by subjecting the curable resin composition according to any one of [1] to [5] to a curing reaction. [7] A varnish obtained by diluting the curable resin composition according to any one of [1] to [5] with an organic solvent. [8] A prepreg having a reinforcing substrate and a semi-cured product of the varnish of [7] impregnated into the reinforcing substrate. [9] [8] A circuit board obtained by laminating the prepreg and copper foil and molding them under heat and pressure. Effect of the Invention

[0012] INDUSTRIAL APPLICABILITY The curable resin composition of the present invention is useful since it can provide a cured product having excellent heat resistance (high glass transition temperature) and dielectric properties (low dielectric properties). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention will be described in detail below.

[0014] <Curable resin composition> [Curable resin (A)] The curable resin composition of the present invention contains a curable resin (A) having an indane skeleton represented by the following general formula (1).

[0015] [ka]

[0016] (In the above formula (1), X represents a (meth)acryloyl group. Ra and Rb each independently represent an alkyl group, an aryl group, an aralkyl group, or a cycloalkyl group having 1 to 12 carbon atoms. j represents an integer of 1 to 3, k and l each independently represent an integer of 0 to 4. n is the average number of repeating units and represents a value of 0.5 to 20, and m represents an integer of 0 to 2. Note that Ra, X, and the straight lines from the carbon atoms to the aromatic ring indicate that they may be bonded to any position on the aromatic ring.)

[0017] The curable resin (A) is preferably because it has an indane skeleton with low polarity, which reduces the proportion of polar functional groups in the structure of the curable resin, and the cured product produced using the curable resin has excellent dielectric properties. In addition, the curable resin (A) is preferably because it has an indane skeleton, which is excellent in flexibility and softness, and is expected to improve brittleness resistance.

[0018] In the above formula (1), X is a (meth)acryloyl group that serves as a crosslinking group, that is, an acryloyl group or a methacryloyl group, and a methacryloyl group is particularly preferred. By having a (meth)acryloyl group in the curable resin, a cured product having a low dielectric tangent can be obtained compared to other crosslinking groups (e.g., a vinylbenzyl ether group (styryl group) or a dihydroxybenzene group), which is a preferred embodiment.

[0019] Incidentally, the detailed reason why the presence of the (meth)acryloyl group results in a cured product that exhibits low dielectric properties is not clear; however, in the case of a vinylbenzyl ether group (styryl group) or the like contained in a conventionally used curable resin, it has an ether group, which is a polar group, and in the case of a dihydroxybenzene group, it has a plurality of hydroxyl groups, which are polar groups. It is speculated that this is due to the fact that an ester group based on a (meth)acryloyl group, such as the curable resin (A) of the present invention, has lower molecular mobility (when a highly polar group such as an ether group or a hydroxyl group is present, the dielectric constant and dielectric loss tangent tend to be high).

[0020] In addition, when the crosslinking group is a methacryloyl group, it is presumed that the steric hindrance increases and the molecular mobility further decreases because the crosslinking group contains a methyl group in the structure, and therefore it is preferable to obtain a cured product with a lower dielectric tangent. In addition, when there are multiple crosslinking groups, the crosslinking density increases and the heat resistance improves.

[0021] In the above formula (1), Ra each independently represents an alkyl group, an aryl group, an aralkyl group, or a cycloalkyl group having 1 to 12 carbon atoms, and is preferably an alkyl group, an aryl group, or a cycloalkyl group having 1 to 4 carbon atoms. The alkyl group having 1 to 12 carbon atoms reduces the planarity in the vicinity of any of the benzene ring, the naphthalene ring, and the anthracene ring described below, and the reduced crystallinity improves the solvent solubility and lowers the melting point, which is a preferred embodiment. In addition, it is presumed that the presence of the above Ra causes steric hindrance and further reduces molecular mobility, and thus a cured product with a lower dielectric tangent can be obtained, which is preferable.

[0022] In the above formula (1), Rb's each independently represent an alkyl group, an aryl group, an aralkyl group, or a cycloalkyl group having 1 to 12 carbon atoms, and are preferably an alkyl group, an aryl group, or a cycloalkyl group having 1 to 4 carbon atoms. By being an alkyl group or the like having 1 to 12 carbon atoms, the planarity in the vicinity of any of the benzene ring, the naphthalene ring, and the anthracene ring described below is reduced, and the reduced crystallinity improves the solvent solubility and lowers the melting point, which is a preferred embodiment.

[0023] In the above formula (1), j represents an integer of 1 to 3, and is preferably an integer of 1 to 2. Within the above range, flexibility is ensured, which is a preferred embodiment. Note that, by introducing a plurality of the above X serving as a crosslinking group into the same benzene ring or the like, the plurality of crosslinking groups inhibit (suppress) each other in molecular mobility, and even when the above Ra serving as a substituent is not present, a cured product exhibiting a low dielectric tangent is obtained, which is preferred.

[0024] In the above formula (1), k and l each independently represent an integer of 0 to 4, and preferably an integer of 0 to 2. Being within the above range results in excellent reactivity, which is a preferred embodiment.

[0025] In the above formula (1), m represents an integer of 0 to 2, that is, when m is 0, it is a benzene ring, when m is 1, it is a naphthalene ring, and when m is 2, it is an anthracene ring, and preferably, it is a benzene ring with m being 0. When it is within the above range, the solvent solubility is excellent, which is a preferred embodiment.

[0026] In the above formula (1), n ​​is the average number of repeating units, and is a value of 0.5 to 20, preferably 0.5 to 5, and more preferably 0.95 to 2.5. By having an indane skeleton within the above range, the solvent solubility is excellent, which is a preferred embodiment. If the n is less than 0.5, the content of high-melting point substances in the structure of the curable resin having the indane skeleton becomes high, resulting in poor solvent solubility, and furthermore, the proportion of high molecular weight components that contribute to flexibility becomes low, so that the brittleness resistance of the obtained cured product decreases, and furthermore, flexibility and softness may also decrease, which is not preferred. If the n exceeds 20, the viscosity increases when dissolved in a solvent, and there is a concern that the heat resistance of the obtained cured product may be poor, and furthermore, the amount of high molecular weight components becomes too large, so that the flowability decreases when the cured product is molded, and there is a concern that the handleability may be poor, which is not preferred. In addition, the value of n is particularly preferably 0.95 to 2.5 from the viewpoint of high heat distortion temperature and high glass transition temperature of the cured product.

[0027] Since the curable resin (A) has an indane skeleton, an alicyclic structure having an excellent balance between heat resistance and dielectric properties is introduced into the structure of the curable resin, and a cured product produced using the curable resin has an excellent balance between heat resistance and dielectric properties (particularly, low dielectric tangent). Furthermore, since the molecular structure has a (meth)acryloyl group that serves as a crosslinking group, steric hindrance becomes large, and further low dielectric properties can be expressed, which is preferable.

[0028] The curable resin (A) in the present invention preferably has an indane skeleton represented by the following general formula (2).

[0029] [ka]

[0030] (In the above formula (2), R1 and R2 are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group, an aralkyl group, or a cycloalkyl group, and R1 and R2 are not both hydrogen atoms at the same time, and n is the average number of repeating units and is a value of 0.5 to 20.)

[0031] In the above formula (2), R1 and R2 are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group, an aralkyl group, or a cycloalkyl group, and are not both hydrogen atoms at the same time, and are preferably an alkyl group, an aryl group, or a cycloalkyl group having 1 to 4 carbon atoms. By being an alkyl group having 1 to 12 carbon atoms, the planarity in the vicinity of the benzene ring is reduced, and the crystallinity is reduced, which improves the solvent solubility and lowers the melting point, which is a preferred embodiment. In addition, by having the above R1 and R2, it is presumed that the steric hindrance is increased (unless they are hydrogen atoms), and the molecular mobility is further reduced, and a cured product with a lower dielectric tangent can be obtained, which is preferable.

[0032] In the above formula (2), n is the average number of repeating units, and is a value of 0.5 to 20, preferably 0.5 to 5, and more preferably 0.95 to 2.5. By having an indane skeleton within the above range, the solvent solubility is excellent, which is a preferred embodiment. If the n is less than 0.5, the content of high melting point substances in the structure of the curable resin (A) is high, the solvent solubility is poor, and the proportion of high molecular weight components that contribute to flexibility is low, so that the brittleness resistance of the obtained cured product is reduced, and further, the flexibility and softness may also be reduced, which is not preferred. If the n exceeds 20, the viscosity increases when dissolved in a solvent, and there is a concern that the heat resistance of the obtained cured product is deteriorated, and further, the amount of high molecular weight components becomes too large, so that the flowability decreases when the cured product is molded, and there is a concern that the handleability is deteriorated, which is not preferred. In addition, the value of n is particularly preferably 0.95 to 2.5 from the viewpoint of high heat distortion temperature and high glass transition temperature of the cured product.

[0033] The softening point of the curable resin (A) is preferably 150° C. or lower, and more preferably 30 to 100° C. If the softening point of the curable resin (A) is within the above range, excellent processability is achieved, which is preferable.

[0034] The curable resin (A) may be a single resin or a combination of two or more resins in any ratio.

[0035] The curable resin (A) can be produced by the production method described in WO 2021 / 205806.

[0036] [Maleimide compound (B)] The curable resin composition of the present invention contains a maleimide compound (B). There are no particular limitations on the maleimide compound (B) as long as it is a compound containing one or more maleimide groups.

[0037] As the maleimide compound (B), from the viewpoint of heat resistance, a bismaleimide compound containing two maleimide groups is preferable, and examples thereof include 4,4'-diphenylmethane bismaleimide, m-phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 1,6'-bismaleimide-(2,2,4-trimethyl)hexane, 4,4'-diphenyl ether bismaleimide, 4,4'-diphenylsulfone bismaleimide, 1,3-bis(3-maleimidophenoxy)benzene, and 1,3-bis(4-maleimidophenoxy)benzene.

[0038] In terms of dielectric properties, maleimide compounds containing an indane skeleton can also be preferably used as the maleimide compound (B). Examples of such compounds include the maleimides described in WO 2020 / 217679.

[0039] For example, a maleimide compound having an indane skeleton represented by the following general formula (3) can be used. [ka] In formula (3), Ra', Rb', k' and l' have the same meanings as Ra, Rb, k and l in formula (1), respectively, and the illustrative and preferred examples thereof are also applicable. n' is the average number of repeating units and is a value of 0.95 to 10.0.

[0040] The maleimide described in JP 2023-59784 A can also be preferably used as the maleimide compound (B). Specifically, the maleimide compound represented by the following general formula (4) can be mentioned. [ka] In formula (4), there are multiple X 11 , R 11 , p 11 Each exists independently, and X11 R represents any one of the structures represented by the following formulas (4-a) to (4-f). 11 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aromatic group having 1 to 20 carbon atoms which may have a substituent, p 11 represents a real number from 1 to 3. 11 is the number of repetitions, the average of which is 1 <n 11 <10. [ka] In formula (4-a) to formula (4-f), * represents a bond to a benzene ring. 12 , m 11 , q 11 , r 11 exist independently, and R 12 represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aromatic group having 1 to 20 carbon atoms which may have a substituent; m 11 is 1 to 50, q 11 is 1 to 4, r 11 represents a real number from 1 to 3.

[0041] The maleimide described in JP 2023-7239 A can also be preferably used as the maleimide compound (B). Specifically, the maleimide compound represented by the following general formula (5) can be mentioned. [ka] In formula (5), R 21 each independently represents an alkyl group, R 22 each independently represents an alkyl group, alkoxy group, or alkylthio group having 1 to 10 carbon atoms; an aryl group, aryloxy group, or arylthio group having 6 to 10 carbon atoms; a cycloalkyl group having 3 to 10 carbon atoms; a halogen atom; a hydroxyl group; or a mercapto group, R 23 , R 24 , R 25 and R 26 each independently represents a hydrogen atom or a methyl group, and R 23 and R24 One of the groups is a hydrogen atom and the other is a methyl group, and R 25 and R 26 one of which is a hydrogen atom and the other is a methyl group, X 21 is represented by the following general formula (6): [ka] In formula (6), R 27 and R 28 each independently represents a hydrogen atom or a methyl group, and R 7 and R 8 One of the groups is a hydrogen atom and the other is a methyl group, and R 29 each independently represents an alkyl group, an alkoxy group, or an alkylthio group having 1 to 10 carbon atoms; an aryl group, an aryloxy group, or an arylthio group having 6 to 10 carbon atoms; a cycloalkyl group having 3 to 10 carbon atoms; a halogen atom; a hydroxyl group; or a mercapto group; 21 represents an integer from 0 to 4.) r represents a substituent represented by 21 X 21 X per benzene ring to which 21 is the average number of substitutions, and represents a number from 0 to 4; p 21 represents an integer from 1 to 3, and q 21 represents an integer from 0 to 4, and k 21 represents an integer from 1 to 100.

[0042] The maleimide compound (B) may be used alone or in any combination of two or more kinds in any ratio.

[0043] [Amount] The curable resin composition of the present invention contains a curable resin (A) having an indane skeleton represented by general formula (1) and a maleimide compound (B). By combining these, a cured product having excellent heat resistance (high glass transition temperature) and dielectric properties (low dielectric properties) can be obtained.

[0044] The mass of the curable resin (A) and the mass of the maleimide compound (B) are preferably 10 to 80 parts by mass of (B) relative to 100 parts by mass of the total of (A) and (B) from the viewpoint of achieving both excellent heat resistance and excellent dielectric properties, and more preferably 10 to 70 parts by mass.

[0045] [Other resins, etc.] The curable resin composition of the present invention can contain a resin component within a range that does not impair the purpose. For example, the resin component can be a thermoplastic elastomer. In addition, maleimide resin, thermosetting polyimide resin, epoxy resin, phenolic resin, active ester resin, benzoxazine resin, cyanate resin, etc. can also be appropriately contained depending on the purpose.

[0046] [Hardening agent] The curable resin composition of the present invention may contain a curing agent. Examples of the curing agent include amine compounds, amide compounds, acid anhydride compounds, phenolic compounds, and cyanate ester compounds. These curing agents may be used alone or in combination of two or more kinds in any ratio.

[0047] [Cure accelerator] The curable resin composition of the present invention may also be used with a curing accelerator as necessary. Various types of curing accelerators can be used, including phosphorus compounds, tertiary amines, imidazoles, organic acid metal salts, Lewis acids, and amine complex salts. In particular, when used as a semiconductor encapsulation material, phosphorus compounds such as triphenylphosphine or imidazoles are preferred because of their excellent curability, heat resistance, electrical properties, and moisture resistance reliability. These curing accelerators may be used alone or in combination of two or more types in any ratio.

[0048] [Flame retardant] The curable resin composition of the present invention may contain a non-halogen flame retardant that does not substantially contain halogen atoms in order to exhibit flame retardancy, if necessary. Examples of the non-halogen flame retardant include phosphorus-based flame retardants, nitrogen-based flame retardants, silicone-based flame retardants, inorganic flame retardants, and organic metal salt-based flame retardants. These may be used alone or in combination of two or more kinds in any ratio.

[0049] [Filler] The curable resin composition of the present invention may contain a filler as necessary. Examples of the filler include inorganic fillers, such as fused silica, crystalline silica, alumina, silicon nitride, and aluminum hydroxide. When the amount of the inorganic filler to be added is particularly large, it is preferable to use fused silica. The fused silica may be either crushed or spherical, but in order to increase the amount of fused silica and suppress an increase in the melt viscosity of the molding material, it is preferable to mainly use spherical silica. In order to further increase the amount of spherical silica to be added, it is preferable to appropriately adjust the particle size distribution of the spherical silica. In addition, when the curable resin composition is used for applications such as a conductive paste, which will be described in detail below, a conductive filler such as silver powder or copper powder can be used.

[0050] [Other compounding agents] To the curable resin composition of the present invention, various compounding agents such as a silane coupling agent, a release agent, a pigment, an emulsifier, etc. may be added, if necessary.

[0051] The curable resin composition of the present invention can be prepared by adding the curable resin (A), the compound (B) and, optionally, the above-mentioned optional components, and mixing them uniformly.

[0052] <Cured product> The present invention also relates to a cured product obtained by curing the curable resin composition of the present invention. The method of the curing reaction is not particularly limited, and can be carried out by a conventionally known method. The cured product can be a molded cured product such as a laminate, a cast product, an adhesive layer, a coating film, or a film.

[0053] The curing reaction includes heat curing and ultraviolet curing, and among them, the heat curing reaction is easily carried out even without a catalyst, but when it is desired to react more quickly, a polymerization initiator such as an organic peroxide or an azo compound is effective, such as benzoyl peroxide, dicumyl peroxide, or azobisisobutyronitrile.

[0054] <Application> The cured product obtained by the curable resin composition of the present invention has excellent heat resistance (high glass transition temperature) and dielectric properties (low dielectric properties), and therefore can be suitably used for heat-resistant members and electronic members. In particular, it can be suitably used for prepregs, circuit boards, semiconductor encapsulants, semiconductor devices, build-up films, build-up boards, adhesives, resist materials, etc. It can also be suitably used for matrix resins of fiber-reinforced resins, and is particularly suitable as highly heat-resistant prepregs. In addition, the curable resin having the indane skeleton contained in the curable resin composition exhibits excellent solubility in various solvents, and can be made into paint. The heat-resistant members and electronic members thus obtained can be suitably used for various applications, such as industrial machine parts, general machine parts, automobile, railway, vehicle parts, space and aviation related parts, electronic and electrical parts, building materials, containers and packaging materials, daily necessities, sports and leisure goods, and housing members for wind power generation, but are not limited thereto.

[0055] Representative products produced using the curable resin composition of the present invention will be described below with reference to examples.

[0056] [varnish] The present invention relates to a varnish obtained by diluting the curable resin composition with an organic solvent. A known method can be used to prepare the varnish, and the curable resin composition can be dissolved (diluted) in an organic solvent to obtain a resin varnish. The present invention is advantageous in that it provides a resin varnish that is excellent in tack-free properties and suppresses stickiness when the resin varnish is in a solvent-free state (uncured or semi-cured).

[0057] As the organic solvent, for example, toluene, xylene, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, methyl ethyl ketone (MEK), methyl isobutyl ketone, dioxane, tetrahydrofuran, etc. can be used alone or as a mixed solvent of two or more kinds.

[0058] [Prepreg] The present invention relates to a prepreg having a reinforcing substrate and the varnish semi-cured by impregnating the reinforcing substrate with the varnish (resin varnish). The varnish (resin varnish) is impregnated into the reinforcing substrate, and the reinforcing substrate impregnated with the varnish (resin varnish) is heat-treated to semi-cure (or uncure) the curable resin composition, thereby forming a prepreg.

[0059] The reinforcing substrate to be impregnated with the varnish (resin varnish) may be a woven or nonwoven fabric made of inorganic fibers such as glass fibers, polyester fibers, or polyamide fibers, or an organic fiber, or a mat, paper, or the like, and these may be used alone or in combination.

[0060] The mass ratio of the curable resin composition to the reinforcing base material in the prepreg is not particularly limited, but it is usually preferable to prepare the prepreg so that the curable resin composition (resin content therein) is 20 to 80 mass %.

[0061] The conditions for the heat treatment of the prepreg are appropriately selected depending on the types and amounts of the organic solvent, catalyst, and various additives used, but the heat treatment is usually performed at a temperature of 80 to 220° C. for 3 to 30 minutes.

[0062] [Circuit board] The present invention relates to a circuit board obtained by laminating the prepreg and copper foil, and subjecting the laminate to thermocompression molding. Specifically, a circuit board can be obtained from the curable resin composition of the present invention by laminating the prepreg in a conventional manner, appropriately layering copper foil, and subjecting the laminate to thermocompression molding at 170 to 300°C under a pressure of 1 to 10 MPa for 10 minutes to 3 hours to obtain a circuit board.

[0063] [Semiconductor encapsulation materials] The semiconductor encapsulant preferably contains the curable resin composition. Specifically, as a method for obtaining a semiconductor encapsulant from the curable resin composition of the present invention, the curable resin composition and further optional compounding agents such as inorganic fillers are melt-mixed sufficiently until homogeneous using an extruder, kneader, roll, etc. as necessary. In this case, fused silica is usually used as the inorganic filler, but when used as a high thermal conductive semiconductor encapsulant for power transistors and power ICs, crystalline silica, alumina, silicon nitride, etc., which have a higher thermal conductivity than fused silica, may be used. The filling rate is preferably in the range of 30 to 95 parts by mass of the inorganic filler per 100 parts by mass of the curable resin composition, and in particular, in order to improve flame retardancy, moisture resistance, and solder crack resistance and to reduce the linear expansion coefficient, 70 parts by mass or more is more preferable, and 80 parts by mass or more is even more preferable.

[0064] [Semiconductor Devices] The semiconductor device preferably includes a cured product obtained by heat-curing the semiconductor encapsulant. Specifically, a semiconductor package molding method for obtaining a semiconductor device from the curable resin composition of the present invention includes a method in which the semiconductor encapsulant is molded by casting or using a transfer molding machine, an injection molding machine, or the like, and then heat-cured at 50 to 250° C. for 2 to 10 hours.

[0065] [Build-up board] The method for obtaining a build-up board from the curable resin composition of the present invention includes a method via steps 1 to 3. In step 1, the curable resin composition containing rubber, filler, etc. is first applied to a circuit board on which a circuit is formed by using a spray coating method, a curtain coating method, etc., and then cured. In step 2, if necessary, the circuit board on which the curable resin composition is applied is drilled for a predetermined through-hole portion, etc., and then treated with a roughening agent, and the surface is washed with hot water to form unevenness on the board, and a metal such as copper is plated. In step 3, the operations of steps 1 and 2 are repeated in sequence as desired, and a resin insulating layer and a conductor layer of a predetermined circuit pattern are alternately built up to form a build-up board. In the above steps, the through-hole portion is preferably drilled after the formation of the outermost resin insulating layer. In addition, the build-up board of the present invention can be produced by forming a roughened surface by semi-curing the resin composition on the copper foil, and then heating and pressing the resin-coated copper foil onto a wiring board having a circuit formed thereon at 170 to 300°C, thereby eliminating the need for a plating process.

[0066] [Build-up film] The build-up film preferably contains the curable resin composition. As a method for obtaining a build-up film from the curable resin composition of the present invention, for example, a method of applying the curable resin composition onto a support film, drying the composition, and forming a resin composition layer on the support film can be mentioned. When the curable resin composition of the present invention is used for a build-up film, it is essential that the film softens under the temperature conditions for lamination in the vacuum lamination method (usually 70 to 140°C), and exhibits a fluidity (resin flow) that allows resin filling in via holes or through holes present in the circuit board at the same time as lamination of the circuit board, and it is preferable to mix the above-mentioned components so as to express such characteristics.

[0067] Here, the diameter of the through-holes in the circuit board is usually 0.1 to 0.5 mm, and the depth is usually 0.1 to 1.2 mm, and it is usually preferable to enable resin filling within this range. When laminating both sides of the circuit board, it is preferable to fill about 1 / 2 of the through-holes.

[0068] A specific method for producing the build-up film described above includes preparing a resin composition varnished by blending an organic solvent, applying the varnished resin composition to the surface of a support film (Y), and then drying the organic solvent by heating or blowing hot air or the like to form a resin composition layer (X).

[0069] The organic solvent used here preferably includes, for example, ketones such as acetone, methyl ethyl ketone, cyclohexanone, etc., acetate esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, carbitol acetate, etc., carbitols such as cellosolve, butyl carbitol, etc., aromatic hydrocarbons such as toluene, xylene, etc., dimethylformamide, dimethylacetamide, N-methylpyrrolidone, etc., and it is preferable to use the organic solvent in a proportion such that the nonvolatile content is 30 to 60 mass%.

[0070] The thickness of the resin composition layer (X) formed is usually required to be equal to or greater than the thickness of the conductor layer. Since the thickness of the conductor layer of the circuit board is usually in the range of 5 to 70 μm, the thickness of the resin composition layer (X) is preferably 10 to 100 μm. The resin composition layer (X) in the present invention may be protected with a protective film described below. By protecting the resin composition layer with a protective film, adhesion of dirt and the like to the surface of the resin composition layer and scratches can be prevented.

[0071] The support film and the protective film may be made of polyolefins such as polyethylene, polypropylene, and polyvinyl chloride, polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate, polycarbonate, polyimide, and even release paper, copper foil, aluminum foil, and other metal foils. The support film and the protective film may be subjected to a release treatment in addition to a mud treatment and a corona treatment. The thickness of the support film is not particularly limited, but is usually 10 to 150 μm, and is preferably in the range of 25 to 50 μm. The thickness of the protective film is preferably 1 to 40 μm.

[0072] The support film (Y) is peeled off after laminating it onto a circuit board or after forming an insulating layer by heat curing. If the support film (Y) is peeled off after the resin composition layer constituting the build-up film is heat cured, adhesion of dust and the like during the curing process can be prevented. When peeling off after curing, the support film is usually subjected to a release treatment in advance.

[0073] A multilayer printed circuit board can be manufactured from the build-up film obtained as described above. For example, when the resin composition layer (X) is protected by a protective film, the protective film is peeled off, and then the resin composition layer (X) is laminated on one or both sides of the circuit board so as to be in direct contact with the circuit board, for example, by a vacuum lamination method. The lamination method may be a batch method or a continuous method using a roll. If necessary, the build-up film and the circuit board may be heated (preheated) before lamination. The lamination conditions are preferably a pressure bonding temperature (lamination temperature) of 70 to 140°C and a pressure bonding pressure of 1 to 11 kgf / cm. 2 (9.8×10 4 ~107.9×10 4 N / m 2 ), and lamination is preferably performed under reduced air pressure of 20 mmHg (26.7 hPa) or less.

[0074] [Conductive paste] As a method for obtaining a conductive paste from the curable resin composition of the present invention, for example, a method of dispersing conductive particles in the composition can be mentioned. Depending on the type of conductive particles used, the above conductive paste can be made into a paste resin composition for circuit connection or an anisotropic conductive adhesive.

Examples

[0075] Next, the present invention will be specifically described with reference to Examples and Comparative Examples. In the following, "parts" and "%" are based on mass unless otherwise specified. The curable resin was synthesized under the conditions shown below. Further, a curable resin composition containing the curable resin was prepared, and a cured product was prepared by the curing reaction of the curable resin composition. The curable resin and the cured product were measured or calculated under the conditions shown below and evaluated.

[0076] <GPC measurement (evaluation of number average molecular weight (Mn), weight average molecular weight (Mw), and average number of repeating units)> Using the following measuring device and measuring conditions, a GPC chart of the curable resin was obtained by the synthesis method shown below (the GPC chart is not shown). From the results of the GPC chart, the number average molecular weight (Mn) and weight average molecular weight (Mw) of the curable resin were calculated. Also, based on Mn, the average number of repeating units n contributing to the indane skeleton in the curable resin was calculated. Specifically, for compounds with n of 0 to 4, the theoretical molecular weight and the measured molecular weight in GPC were plotted on a scatter diagram, an approximate straight line was drawn, and the number average molecular weight (Mn) was obtained from the point indicated by the measured value Mn(1) on the straight line, and the average number of repeating units n was calculated. Measuring device: "HLC-8320 GPC" manufactured by Tosoh Corporation Column: Guard column "HXL-L" manufactured by Tosoh Corporation + "TSK-GEL G2000HXL" manufactured by Tosoh Corporation + "TSK-GEL G2000HXL" manufactured by Tosoh Corporation + "TSK-GEL G3000HXL" manufactured by Tosoh Corporation + "TSK-GEL G4000HXL" manufactured by Tosoh Corporation Detector: RI (differential refractometer) Data processing: Tosoh Corporation's "GPC Workstation EcoSEC-WorkStation" Measurement conditions: Column temperature 40℃ Developing solvent: Tetrahydrofuran Flow rate 1.0ml / min Standard: In accordance with the measurement manual for the "GPC Workstation EcoSEC-WorkStation," the following monodisperse polystyrene with known molecular weight was used. (Polystyrene used) "A-500" manufactured by Tosoh Corporation "A-1000" manufactured by Tosoh Corporation "A-2500" manufactured by Tosoh Corporation "A-5000" manufactured by Tosoh Corporation "F-1" manufactured by Tosoh Corporation "F-2" manufactured by Tosoh Corporation "F-4" manufactured by Tosoh Corporation "F-10" manufactured by Tosoh Corporation "F-20" manufactured by Tosoh Corporation "F-40" manufactured by Tosoh Corporation "F-80" manufactured by Tosoh Corporation "F-128" manufactured by Tosoh Corporation Sample: A tetrahydrofuran solution (1.0 mass % in terms of solid content) of the curable resin obtained in Synthesis Example was filtered through a microfilter (50 μl).

[0077] (Synthesis example: Curable resin (a)) In a 1L flask equipped with a thermometer, a cooling tube, a Dean-Stark trap, and a stirrer, 48.9g (0.4mol) of 2,6-dimethylphenol, 272.0g (1.4mol) of α,α'-dihydroxy-1,3-diisopropylbenzene, 280g of xylene, and 70g of activated clay were charged and heated to 120°C while stirring. The temperature was raised to 210°C while removing the distilled water with a Dean-Stark tube, and the reaction was carried out for 3 hours. After that, the mixture was cooled to 140°C, and 146.6g (1.2mol) of 2,6-dimethylphenol was charged, and the temperature was raised to 220°C and the reaction was carried out for 3 hours. After the reaction, the mixture was air-cooled to 100°C, diluted with 300g of toluene, filtered to remove the activated clay, and low molecular weight substances such as the solvent and unreacted substances were distilled off under reduced pressure to obtain 365.3g of an intermediate phenolic compound. The hydroxyl equivalent (phenol equivalent) of the obtained intermediate phenolic compound was 299.

[0078] In a 2L flask equipped with a thermometer, a cooling tube, and a stirrer, 365.3 g of the intermediate phenol compound obtained and 700 g of toluene were charged and stirred at about 85 ° C. Next, 29.9 g (0.24 mol) of dimethylaminopyridine was charged. When it was thought that all the solids had dissolved, 277.5 g (1.8 mol) of methacrylic anhydride was added dropwise over 1 hour. After the dropwise addition was completed, the reaction was allowed to proceed for another 3 hours at 85 ° C. The reaction liquid was added dropwise over 1 hour to 4000 g of methanol vigorously stirred with a magnetic stirrer in a 5L beaker. The resulting precipitate was filtered under reduced pressure with a membrane filter and then dried to obtain a curable resin (a) (average number of repeating units n = 1.6) having an indane skeleton of the following structural formula.

[0079] [ka]

[0080] <Preparation of Curable Resin Composition> Using the curable resin (a) obtained in the above synthesis example, a curable resin composition (varnish) was prepared having the composition (raw materials, amounts) shown in the following Table 1. Specifically, toluene was used as a solvent and mixed in a planetary centrifugal mixer to adjust the non-volatile content to 60% by mass. The varnish was heated under reduced pressure (held at 70°C for 1 hour under reduced pressure in vacuum) to remove the solvent, resulting in a powder.

[0081] The raw materials other than the curable resin (a) used in the curable resin composition are as follows. Curable resin (a'): SA9000-111 manufactured by SABIC. Modified polyphenylene ether Maleimide compound (b1): BMI1000 manufactured by Daiwa Kasei Kogyo Co., Ltd. 4,4'-diphenylmethane bismaleimide Maleimide compound (b2): BMI5100 manufactured by Daiwa Kasei Kogyo Co., Ltd. 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide Compound (b1'): tert-butylstyrene Compound (b2'): TAIC. Triallyl isocyanurate

[0082] <Preparation of cured product> The above curable resin composition was placed in a mold and heated in a press at 200° C. for 2 hours to be thermally cured. The thickness of the resulting cured product was 1.8 mm.

[0083] <Evaluation of heat resistance> The obtained cured product was cut into a size of 55 mm length × 5 mm width × 1.6 mm thickness to prepare a test piece. The test piece was measured using a viscoelasticity measuring device (DMA: Hitachi High-Tech Science Corporation solid viscoelasticity measuring device "DMS6100", deformation mode: double-support bending, measurement mode: sine wave vibration, frequency 1 Hz, heating rate 3°C / min) to evaluate the temperature at which the elastic modulus change was maximum as the glass transition temperature Tg.

[0084] <Evaluation of dielectric properties> In accordance with JIS-C-6481, the dielectric constant and dielectric loss tangent of the test pieces at 10 GHz were measured using the cavity resonance method with an Agilent Technologies network analyzer "E8362C" after drying and storing them indoors at 23°C and 50% humidity for 24 hours.

[0085] <Tackiness> The above curable resin composition was touched with a finger through a rubber glove at room temperature to check whether it was sticky or not. The absence of stickiness was evaluated as good.

[0086] [Table 1]

[0087] From the evaluation results in Table 1 above, Examples 1 and 2 had improved heat resistance (Tg) and dielectric properties (low dielectric constant) compared to Comparative Examples 1 and 2, which contained modified polyphenylene ether instead of the curable resin having an indane skeleton. Moreover, Examples 1 and 2 had improved heat resistance (Tg) and were also good in terms of tack-free properties compared to Comparative Examples 3 and 4, which contained TAIC or tert-butylstyrene instead of the maleimide compound.

[0088] <Preparation of prepreg> The ingredients (raw materials, amounts) shown in Table 2 below were mixed using a planetary centrifugal mixer with methyl ethyl ketone as a solvent to prepare a varnish with a non-volatile content of 60% by mass. The polyindane-type maleimide resins in Table 1 were synthesized as follows.

[0089] (Synthesis example: Polyindan-type maleimide resin) In a 1L flask equipped with a thermometer, a cooling tube, a Dean-Stark trap, and a stirrer, 48.5g (0.4mol) of 2,6-dimethylaniline, 272.0g (1.4mol) of α,α'-dihydroxy-1,3-diisopropylbenzene, 280g of xylene, and 70g of activated clay were charged and heated to 120°C while stirring. The temperature was raised to 210°C while removing the distilled water with a Dean-Stark tube, and the reaction was carried out for 3 hours. After that, the mixture was cooled to 140°C, and 145.4g (1.2mol) of 2,6-dimethylaniline was charged, and the temperature was raised to 220°C and the reaction was carried out for 3 hours. After the reaction, the mixture was air-cooled to 100°C, diluted with 300g of toluene, filtered to remove the activated clay, and low molecular weight substances such as the solvent and unreacted substances were distilled off under reduced pressure to obtain 364.1g of an intermediate amine compound. The amine equivalent was 298, and the softening point was 70°C.

[0090] A 2L flask equipped with a thermometer, a condenser, a Dean-Stark trap, and a stirrer was charged with 131.8g (1.3mol) of maleic anhydride and 700g of toluene and stirred at room temperature. Next, a mixed solution of 364.1g of reactant (A-1) and 175g of DMF was added dropwise over 1 hour. After the dropwise addition was completed, the reaction was continued for another 2 hours at room temperature. 37.1 g of p-toluenesulfonic acid monohydrate was added, and the reaction solution was heated and refluxed to cool and separate the water and toluene that formed azeotropically. After that, only the toluene was returned to the system and the dehydration reaction was continued for 8 hours. After cooling to room temperature, the mixture was concentrated under reduced pressure to give a brown solution. The liquid was dissolved in 600 g of ethyl acetate, washed three times with 150 g of ion-exchanged water and three times with 150 g of 2% aqueous sodium hydrogen carbonate solution, dried by adding sodium sulfate, concentrated under reduced pressure, and the resulting reaction product was vacuum-dried at 80°C for 4 hours to obtain 413.0 g of a product containing a polyindane-type maleimide resin of the following structural formula. In the FD-MS spectrum (not shown), peaks of M+=560, 718, and 876 were confirmed, and the respective peaks correspond to the cases where n is 0, 1, and 2. The value of the number of repeating units n (based on the number average molecular weight) in the indane skeleton portion of the polyindane-type maleimide resin was determined by GPC (not shown), and it was found to be n=1.47 and the molecular weight distribution (Mw / Mn)=1.81.

[0091] [ka]

[0092] Next, a prepreg was produced using the produced varnish under the following production conditions. Base material: Glass cloth "#2116" (210 x 280 mm) manufactured by Nitto Boseki Co., Ltd. Copper foil: "JTC foil" (18μm) manufactured by JX Nippon Mining & Metals Co., Ltd. Number of plies: 6 Prepreg conditions: 140℃ Curing conditions: 220℃, 40kg / cm 2 2.0 hours Plate thickness after molding: 0.8mm

[0093] The heat resistance and dielectric properties of the obtained prepreg were evaluated in the same manner as above. Furthermore, the hot fluidity was evaluated as follows. The results are shown in Table 2.

[0094] <Hot fluidity> The resin portion obtained by loosening the obtained prepreg was placed on a hot plate heated to 170°C and stirred with a spatula to check for fluidity. Fluidity when heated is evaluated as good. The results are shown in Table 2.

[0095] [Table 2]

[0096] From the evaluation results in Table 2 above, Example 3 had improved dielectric properties (low dielectric constant) and was also evaluated as having good hot fluidity, compared to Comparative Example 5, which contained modified polyphenylene ether instead of a curable resin having an indane skeleton. [Industrial Applicability]

[0097] According to the curable resin composition of the present invention, a cured product having excellent heat resistance (high glass transition temperature) and dielectric properties (low dielectric properties) can be obtained. The cured product of the present invention can be suitably used for heat-resistant components and electronic components, and can be suitably used for prepregs, semiconductor encapsulants, circuit boards, build-up films, build-up boards, adhesives, and resist materials. It can also be suitably used as a matrix resin for fiber-reinforced resins, and is suitable as a highly heat-resistant prepreg.

Claims

1. A curable resin composition comprising a curable resin (A) having an indane skeleton represented by the following general formula (1) and a maleimide compound (B): 【Chemistry 1】 (In the above formula (1), X represents a (meth)acryloyl group. Ra and Rb each independently represent an alkyl group, an aryl group, an aralkyl group, or a cycloalkyl group having 1 to 12 carbon atoms. j represents an integer of 1 to 3. k and l each independently represent an integer of 0 to 4. n is the average number of repeating units and represents a value of 0.5 to 20. m represents an integer of 0 to 2. Note that Ra, X, and the straight lines from the carbon atom to the aromatic ring indicate that the bond may be to any position on the aromatic ring.)

2. The curable resin composition according to claim 1 , wherein the (A) is a curable resin having an indane skeleton represented by the following general formula (2): 【Chemistry 2】 (In the above formula (2), R １ and R ２ are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group, an aralkyl group, or a cycloalkyl group, and R １ and R ２ are not both hydrogen atoms at the same time, and n is the average number of repeating units and is a value of 0.5 to 20.)

3. The (B) is 4,4'-diphenylmethane bismaleimide, m-phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 1,6'-bismaleimide-(2,2,4-trimethyl)hexane, 4,4'-diphenyl ether bismaleimide, 4,4'-diphenylsulfone bismaleimide, 1,3-bis(3-maleimidophenoxy)benzene and 1,3-bis(4-maleimidophenoxy)benzene. The curable resin composition according to claim 1, which is one or more bismaleimide compounds selected from the group consisting of benzene.

4. The curable resin composition according to claim 1 , wherein the (B) is a maleimide compound having an indane skeleton.

5. The curable resin composition according to claim 1, wherein the mass of (B) is 10 to 80 parts by mass relative to 100 parts by mass of the total of the mass of (A) and the mass of (B).

6. A cured product obtained by subjecting the curable resin composition according to any one of claims 1 to 5 to a curing reaction.

7. A varnish obtained by diluting the curable resin composition according to any one of claims 1 to 5 with an organic solvent.

8. A prepreg comprising a reinforcing substrate and a semi-cured product of the varnish according to claim 7 impregnated into the reinforcing substrate.

9. A circuit board obtained by laminating the prepreg according to claim 8 and copper foil, and subjecting the laminate to thermocompression molding.

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