Laminated sheet, laminated sheet with release film, sheet cured product, and circuit board material

Abstract

The present invention provides: a laminated sheet which has low dielectric characteristics and excellent conductor adhesion, has a low linear thermal expansion coefficient, and stably exhibits low dielectric characteristics even under a temperature change or humidity change due to a use environment; and a circuit board material using same.　A laminated sheet S1 according to one example has a support layer (1) and at least two or more resin layers L1 (2) provided on both surfaces of the support layer (1), wherein the support layer (1) contains at least one selected from the group consisting of polyimide resins, cyclic olefin resins, liquid crystal polymers, and polyamide resins; the resin layer (2) in the laminated sheet S1 contains at least one thermoplastic resin (A) selected from the group consisting of styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, and ethylene-based polymers; and the laminated sheet S1 satisfies the formula: Y / (X+Y) ≤ 0.40. X is the thickness of the resin layer (2) in the laminated sheet S1, and Y is the thickness of the support layer (1) in the laminated sheet S1.

Description

Laminated sheet, laminated sheet with release film, cured sheet, and circuit board material

[0001] The present invention relates to a laminate sheet, a laminate sheet with a release film, a cured sheet, and a circuit board material. This application claims priority based on Japanese Patent Application No. 2024-46528, filed with the Japan Patent Office on March 22, 2024, the contents of which are incorporated herein by reference.

[0002] In recent years, as the performance and functionality of electrical and electronic devices have become more sophisticated, communication frequencies have become increasingly higher in order to improve communication speeds and the amount of information transmitted. When digital signals are transmitted through a circuit board, a portion of the transmitted digital signal is converted into heat within the circuit board, resulting in transmission loss. Since the amount of transmission loss is expressed as the product of the dielectric constant and the dielectric loss tangent, achieving low loss during communication requires materials with low dielectric constants and dielectric loss tangents, i.e., materials with low dielectric properties. Transmission signals, particularly in the high-frequency range, are more likely to be converted into heat, so materials with lower dielectric constants and dielectric loss tangents are in demand. Meanwhile, as circuits within electrical and electronic devices become more highly integrated, the amount of heat generated within them increases, so circuit board materials must also be heat-resistant.

[0003] As materials having low dielectric properties, for example, thermosetting resins such as polyphenylene ether resin compositions containing an epoxy compound and a cyanate compound (e.g., Patent Document 1), maleimide resins (e.g., Patent Document 2), and thermoplastic resins such as cyclic olefin resin compositions (e.g., Patent Document 3) have been proposed.

[0004] JP 2010-059363 A JP 2012-255059 A International Publication No. 2006 / 095511

[0005] Thermosetting resins generally have higher dielectric constants and dielectric loss tangents than thermoplastic resins. To impart low dielectric properties to thermosetting resins, it is necessary to add large amounts of inorganic particles, etc. On the other hand, thermoplastic resins exhibit low dielectric properties but do not have good heat resistance.

[0006] In addition, when resin materials are used as circuit board materials, they are laminated with conductors such as copper foil, and therefore a low linear thermal expansion coefficient is required to prevent peeling or deformation from occurring. To reduce the linear thermal expansion coefficient while maintaining low dielectric properties, a large amount of inorganic particles or the like must be added. However, using a large amount of inorganic particles or the like not only complicates the manufacturing process but also makes the sheet brittle, impairing adhesion to conductors such as copper foil. Therefore, there is a demand for higher-quality resin materials that have excellent conductor adhesion, low dielectric properties, and dimensional stability. Furthermore, there is a demand for low dielectric properties that can be stably maintained even when the temperature and humidity change due to the usage environment.

[0007] The present invention aims to provide a laminate sheet having low dielectric properties, excellent conductor adhesion, a low coefficient of linear thermal expansion, and stable low dielectric properties even when subjected to temperature and humidity changes due to the usage environment, and a circuit board material using the same.

[0008] Preferred embodiments of the present invention include, but are not limited to, the following. [1] A laminate sheet comprising: a support layer; and at least two resin layers provided on both sides of the support layer, wherein the support layer contains at least one selected from the group consisting of polyimide resins, cyclic olefin resins, liquid crystal polymers, and polyamide resins, and the resin layers contain at least one thermoplastic resin (A) selected from the group consisting of styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, and ethylene-based polymers, and the laminate sheet satisfies the following formula (Z1): Y / (X+Y)≦0.40 (Z1) In formula (Z1), X is the thickness of the resin layer in the laminate sheet, and Y is the thickness of the support layer in the laminate sheet. [2] The laminate sheet according to [1], which has a dielectric loss tangent at 10 GHz of 0.0060 or less. [3] The laminate sheet according to [1] or [2], which has a storage modulus at 24°C of 10 MPa or more. [4] A laminate sheet according to any one of [1] to [3], having a linear thermal expansion coefficient of 60 ppm / °C or less. [5] A laminate sheet comprising: a support layer; and at least two or more resin layers provided on both sides of the support layer, wherein the support layer contains at least one resin selected from the group consisting of polyimide resins, cyclic olefin resins, liquid crystal polymers, and polyamide resins, and the resin layers contain at least one thermoplastic resin (A) selected from the group consisting of styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, and ethylene-based polymers, and a radically polymerizable compound (B) having two or more ethylenically unsaturated bonds in the molecule, and which satisfies the following formula (Z1): Y / (X+Y)≦0.40...formula (Z1) In formula (Z1), X is the thickness of the resin layer in the laminate sheet, and Y is the thickness of the support layer in the laminate sheet. [6] The laminate sheet according to [5], wherein the resin layer contains, as the radical polymerizable compound (B), at least one selected from the group consisting of a bifunctional aromatic vinyl compound and a trialkenyl isocyanurate compound. [7] The laminate sheet according to [5] or [6], wherein the radical polymerizable compound (B) is a compound having no polar functional group in its molecule.[8] The laminate sheet according to any one of [5] to [7], wherein the polar functional group equivalent of the radical polymerizable compound (B) is 2 or more. The polar functional group equivalent is the ratio of the molecular weight of the radical polymerizable compound (B) to the molecular weight of the polar functional group of the radical polymerizable compound (B). [9] The laminate sheet according to any one of [5] to [8], wherein the content of the radical polymerizable compound (B) is 1 part by mass or more and less than 50 parts by mass per 100 parts by mass of the thermoplastic resin (A).

[10] The laminate sheet according to any one of [5] to [9], wherein the storage modulus when the resin layer is cured by applying a pressure of 2 MPa for 30 minutes at a temperature of 200°C is 1 to 7000 MPa.

[11] The laminate sheet according to any one of [5] to

[10] , wherein the resin layer is cured by applying a pressure of 2 MPa for 30 minutes at a temperature of 200°C, and the relative dielectric constant at 10 GHz is 1.0 to 4.0, and the dielectric dissipation factor is 0.0001 to 0.0060.

[12] The laminate sheet according to any one of [5] to

[11] , wherein the resin layer is cured by applying a pressure of 2 MPa for 30 minutes at a temperature of 200°C, and the linear thermal expansion coefficient is 60 ppm / °C or less.

[13] A cured sheet obtained by curing the laminate sheet according to any one of [5] to

[12] .

[14] The laminate sheet according to any one of [1] to

[12] , wherein the content of the thermoplastic resin (A) is 60 mass% or more of the resin components of the resin layer.

[15] The laminate sheet according to any one of [1] to

[12] and

[14] , wherein the resin layer contains a styrene-based thermoplastic elastomer as the thermoplastic resin (A).

[16] The laminate sheet according to

[15] , wherein the styrene content of the styrene-based thermoplastic elastomer is 10% by mass or more and 70% by mass or less.

[17] The laminate sheet according to any one of [1] to

[12] and

[14] to

[16] , wherein the resin layer further contains a cyclic polyolefin resin copolymer (C).

[18] The laminate sheet according to

[17] , wherein the cyclic polyolefin resin copolymer (C) is a copolymer having an alicyclic structure in a polyolefin side chain.

[19] The laminate sheet according to any one of [1] to

[12] and

[14] to

[18] , wherein the content of the thermoplastic resin (A) is more than 50% by mass of the total mass of the resin layer.

[20] The laminate sheet according to any one of [1] to

[12] and

[14] to

[19] , which satisfies the following formula (Z2): Y / (X+Y)≦0.20 ... formula (Z2) In formula (Z2), X is the thickness of the resin layer in the laminate sheet, and Y is the thickness of the support layer in the laminate sheet.

[21] A laminate sheet with a release film, comprising: the laminate sheet according to any one of [1] to

[12] and

[14] to

[20] ; and a release film provided on one or both surfaces of the laminate sheet.

[22] A circuit board material, in which an insulating layer made of the laminate sheet according to any one of [1] to

[12] and

[14] to

[20] is laminated with a conductor.

[0009] According to the present invention, it is possible to obtain a laminated sheet, a cured sheet, and a circuit board material having low dielectric properties and excellent heat resistance, which have low dielectric properties, excellent conductor adhesion, a low coefficient of linear thermal expansion, and which stably exhibit low dielectric properties even when subjected to temperature and humidity changes due to the usage environment.

[0010] Fig. 1 is a cross-sectional view schematically showing an example of a laminate sheet, and Fig. 2 is a cross-sectional view schematically showing another example of a laminate sheet.

[0011] In this specification, the term "film" conceptually encompasses sheets, films, and tapes.

[0012] In this specification, when the term "substrate" is used, such as a circuit board or a resin board, the term "substrate" encompasses plates, sheets, and films.

[0013] In this specification, when it is stated that "x to y" (x and y are any numbers), it means "x or more and y or less" unless otherwise specified, and also includes the meaning of "preferably greater than x" or "preferably smaller than y". In this specification, when it is stated that "x or more" (x is any number), it means "preferably greater than x" unless otherwise specified, and when it is stated that "y or less" (y is any number), it also means "preferably smaller than y" unless otherwise specified. In this specification, "x and / or y (x and y are any configurations)" means at least one of x and y, and means three possibilities: x only, y only, or x and y.

[0014] Hereinafter, several embodiments will be described with reference to the drawings. However, the following description is of typical examples, and the present invention is not limited to the following description. The dimensional ratios in the drawings are for the convenience of explanation and may differ from the actual ones.

[0015] [Laminate Sheet] The present invention includes a first embodiment relating to a laminate sheet S1. The laminate sheet S1 according to the first embodiment has a support layer and at least two or more resin layers L1 provided on both sides of the support layer. The support layer contains at least one resin selected from the group consisting of polyimide resin, cyclic olefin resin, and polyamide resin as a main component. The resin layer L1 in the laminate sheet S1 contains at least one thermoplastic resin (A) selected from the group consisting of a styrene-based thermoplastic elastomer, an olefin-based thermoplastic elastomer, and an ethylene-based polymer.

[0016] The present invention includes a second embodiment relating to a laminate sheet S2. The laminate sheet S2 according to the second embodiment has a support layer and at least two or more resin layers L2 provided on both sides of the support layer. The support layer contains at least one resin selected from the group consisting of polyimide resin, cyclic olefin resin, and polyamide resin as a main component. The resin layer L2 in the laminate sheet S2 contains at least one thermoplastic resin (A) selected from the group consisting of a styrene-based thermoplastic elastomer, an olefin-based thermoplastic elastomer, and an ethylene-based polymer, and a radically polymerizable compound (B) having two or more ethylenically unsaturated bonds in the molecule.

[0017] The laminated sheets S1 and S2 satisfy the following formula (Z1).

[0018] Y / (X+Y)≦0.40 Formula (Z1) In formula (Z1), X is the thickness of the resin layer in laminate sheet S1 or laminate sheet S2, and Y is the thickness of the support layer in laminate sheet S1 or laminate sheet S2.

[0019] The laminate sheets S1 and S2 (hereinafter, in this specification, "the present laminate sheet" is a general term for the laminate sheets S1 and S2) can exhibit low dielectric properties and excellent conductor adhesion, and also have a low linear thermal expansion coefficient. Moreover, the low dielectric properties are stably exhibited even with temperature and humidity changes due to the usage environment. Furthermore, since the present laminate sheet can be obtained simply by laminating at least the above two components, there is no need for complicated manufacturing processes or the use of special materials. Therefore, it is also suitable for mass production. Below, an embodiment of the present laminate sheet will be described in detail.

[0020] (Resin Layer) The resin layer L1 of the laminate sheet S1 is formed from a resin composition C1 containing at least one thermoplastic resin (A) selected from the group consisting of a styrene-based thermoplastic elastomer, an olefin-based thermoplastic elastomer, and an ethylene-based polymer. The resin layer L2 of the laminate sheet S2 is formed from a resin composition C2 containing at least one thermoplastic resin (A) selected from the group consisting of a styrene-based thermoplastic elastomer, an olefin-based thermoplastic elastomer, and an ethylene-based polymer, and a radical polymerizable compound (B) having two or more ethylenically unsaturated bonds in the molecule.

[0021] Hereinafter, in this specification, "the present composition" is a general term for resin composition C1 and resin composition C2. Similarly, "the present resin layer" is a general term for resin layer L1 and resin layer L2. In some examples, the composition of the present resin layer is the same as the composition of the solid content obtained by removing the solvent from the present composition.

[0022] By using this resin layer in combination with the support layer, the circuit board material has good low dielectric properties and heat resistance. The reason why the circuit board material has good low dielectric properties and heat resistance is not entirely clear, but it is thought to be as follows. First, the resin layer L1 and resin layer L2 containing the thermoplastic resin (A) contribute to the development of low dielectric properties. Therefore, it is thought that the support layer ensures heat resistance, thereby developing good low dielectric properties and heat resistance.

[0023] Next, in resin composition C2, by further using a radically polymerizable compound (B) that is soluble in the thermoplastic resin (A), the radically polymerizable compound (B) is less likely to be incorporated into the molecular structure of the thermoplastic resin (A). Therefore, it is believed that the low dielectric properties of the thermoplastic resin (A) are not impaired, and the dielectric loss tangent can be maintained low. Furthermore, when resin composition C2 is cured, favorable entanglement of the molecular chains of the thermoplastic resin (A) and the polymerization product of the radically polymerizable compound (B) can be formed, resulting in a pseudo-high crosslink density, an improved modulus of elasticity, and good heat resistance. Each component of this composition is described below.

[0024] 1. Thermoplastic Resin (A) The thermoplastic resin (A) is at least one selected from the group consisting of a styrene-based thermoplastic elastomer, an olefin-based thermoplastic elastomer, and an ethylene-based polymer. One type of thermoplastic resin (A) may be used alone, or two or more types may be used in combination.

[0025] Examples of styrene-based thermoplastic elastomers include styrene-butadiene-styrene block copolymers (SBS), styrene-isoprene-styrene block copolymers (SIS), and hydrogenated versions thereof, such as styrene-ethylene-butadiene-styrene block copolymers (SEBS), styrene-ethylene-propylene-styrene block copolymers (SEPS), and styrene-isobutylene-styrene block copolymers (SIBS).

[0026] The olefin-based thermoplastic elastomer contains a polyolefin (excluding cyclic polyolefins, which will be described later) as a hard segment and a rubber component as a soft segment. The olefin-based thermoplastic elastomer may be a mixture (polymer blend) of a polyolefin and a rubber component, a crosslinked product obtained by crosslinking a polyolefin and a rubber component, or a polymer obtained by polymerizing a polyolefin and a rubber component.

[0027] Examples of polyolefins include polypropylene, polyethylene, etc. Examples of rubber components include diene rubbers such as isoprene rubber, butadiene rubber, butyl rubber, propylene-butadiene rubber, acrylonitrile-butadiene rubber, and acrylonitrile-isoprene rubber, ethylene-propylene non-conjugated diene rubber, and ethylene-butadiene copolymer rubber.

[0028] Examples of ethylene-based polymers include ethylene homopolymers and copolymers of ethylene and other monomers. The copolymer of ethylene and other monomers preferably contains ethylene as the main component. Here, "containing ethylene as the main component" means that the copolymer contains 50 mol % or more, preferably 60 mol % or more, of ethylene structural units. The other monomer copolymerized with ethylene is not particularly limited as long as it is a monomer copolymerizable with ethylene.

[0029] Suitable examples of ethylene polymers include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polyethylene obtained by polymerization using a metallocene catalyst, etc. Among these, it is particularly preferable to use linear low-density polyethylene (LLDPE) because of its high flexibility.

[0030] Among the thermoplastic resins (A) exemplified above, styrene-based thermoplastic elastomers and olefin-based thermoplastic elastomers are preferred because of their excellent flexibility and toughness.

[0031] In resin composition C2, particularly when a combination is selected in which the thermoplastic resin (A) itself is unlikely to react with the radically polymerizable compound (B), the molecular chains of the thermoplastic resin (A) and the radically polymerizable compound (B) form a structure in which they are partially and physically entangled with each other. Therefore, while maintaining the low dielectric properties of the thermoplastic resin (A), the crosslink density is increased in a manner similar to that of the thermoplastic resin (A) alone. As a result, the elastic modulus is improved and heat resistance is improved. From this perspective, it is preferable that the thermoplastic resin (A) and the radically polymerizable compound (B) are combined in a manner that does not react with each other.

[0032] Among the thermoplastic resins (A), styrene-based thermoplastic elastomers are preferred, styrene-isobutylene-styrene-block copolymers (SIBS) and styrene-ethylene-butadiene-styrene block copolymers (SEBS) are more preferred, and styrene-ethylene-butadiene-styrene block copolymers (SEBS) are even more preferred.

[0033] When a styrene-based thermoplastic elastomer is used as the thermoplastic resin (A), the styrene content is preferably 10% by mass or more, more preferably 15% by mass or more. The styrene content is preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 50% by mass or less, and even more preferably 40% by mass or less. When the styrene content is within the above range, the thermoplastic resin (A) has a low dielectric tangent and an appropriate modulus of elasticity, thereby achieving both low dielectric properties and heat resistance, and also exhibiting good handleability.

[0034] The thermoplastic resin (A) may be modified by a known method. Examples of the modified product include a reaction product of the thermoplastic resin (A) with at least one of the above-mentioned unsaturated carboxylic acid and its anhydride. By modifying the thermoplastic resin (A), the polarity of the polymer increases, which is expected to improve adhesion to a metal layer such as a copper foil.

[0035] Examples of unsaturated carboxylic acids and anhydrides thereof include acrylic acid, methacrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, nadic acids, and other unsaturated carboxylic acids and their anhydrides. Specific examples of acid anhydrides include maleic anhydride, citraconic anhydride, and nadic anhydrides.

[0036] Examples of nadic acids or anhydrides thereof include endo-cis-bicyclo[2.2.1]hept-2,3-dicarboxylic acid (nadic acid), methyl-endo-cis-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid (methylnadic acid), and the like, and anhydrides thereof.

[0037] Among these unsaturated carboxylic acids and / or their anhydrides, acrylic acid, maleic acid, nadic acid, maleic anhydride, and nadic acid anhydride are preferred. One type of unsaturated carboxylic acid and / or its anhydride may be used alone, or two or more types may be used in combination.

[0038] From the viewpoint of low dielectric properties, the content of the thermoplastic resin (A) in the composition is preferably 60 mass % or more, more preferably 70 mass % or more, even more preferably 80 mass % or more, and even more preferably 85 mass % or more of the resin components of the composition. The upper limit of the content is not particularly limited, and the resin components of the composition may consist solely of the thermoplastic resin (A) (100 mass %).

[0039] In this specification, the term "resin component" refers to the thermoplastic resin (A) contained in the present composition, the cyclic polyolefin resin copolymer (C) described below, and other resins added as needed.

[0040] From the viewpoints of low dielectric properties and copper foil adhesion, the content of the thermoplastic resin (A) in the resin layer is preferably more than 50 mass% of the total mass of the resin layer. From the viewpoints of low dielectric properties and copper foil adhesion, the content of the thermoplastic resin (A) is more preferably more than 55 mass% based on the total mass of the resin layer, even more preferably 60 mass% or more, and particularly preferably 65 mass% or more. The upper limit of the content of the thermoplastic resin (A) is more preferably 99 mass% or less, even more preferably 90 mass% or less.

[0041] The storage modulus of the thermoplastic resin (A) at 24°C is preferably 0.1 MPa or more, more preferably 1 MPa or more. The storage modulus is preferably less than 2000 MPa, more preferably less than 1500 MPa, even more preferably less than 1000 MPa, even more preferably less than 500 MPa, even more preferably less than 300 MPa, even more preferably less than 100 MPa, and even more preferably less than 50 MPa. When the storage modulus of the thermoplastic resin (A) at 24°C is less than the upper limit, the flexibility of the resulting cured sheet is good. When the storage modulus of the thermoplastic resin (A) at 24°C is equal to or greater than the lower limit, the heat resistance and handleability of the resulting cured sheet are good.

[0042] The storage modulus is a value obtained by molding the thermoplastic resin (A) into a sheet having a thickness of 300 μm to prepare a test piece and measuring the dynamic viscoelasticity using a viscoelasticity spectrometer. The measurement conditions may be the same as those described in the examples.

[0043] The density of the thermoplastic resin (A) is 0.98 g / cm ３ Preferably, 0.95 g / cm or less ３ More preferably, 0.91 g / cm or less ３ On the other hand, the lower limit of the density is not particularly limited, but is preferably 0.80 g / cm ３ When the density is equal to or less than the above value, the flexibility of the obtained cured sheet is good.

[0044] The density can be measured in accordance with ASTM D792 using a test piece obtained by molding the thermoplastic resin (A) into a sheet having a thickness of 300 μm.

[0045] The dielectric loss tangent of the thermoplastic resin (A) is preferably less than 0.0020 at 10 GHz, more preferably less than 0.0015, and even more preferably less than 0.0010. Meanwhile, the lower limit of the dielectric loss tangent of the thermoplastic resin (A) is not particularly limited, and it may be 0 or more. The smaller the dielectric loss tangent, the smaller the dielectric loss. Therefore, when the present composition is used as a circuit board material, improved electrical signal transmission efficiency and higher speed can be achieved.

[0046] The dielectric loss tangent is a value obtained by forming the thermoplastic resin (A) into a sheet having a thickness of about 300 μm to prepare a test piece, and measuring the dielectric loss tangent at a temperature of 23° C. and a frequency of 10 GHz in accordance with JIS C2565:1992.

[0047] 2. Radically Polymerizable Compound (B) Resin composition C2 contains a radically polymerizable compound (B). The radically polymerizable compound (B) is a compound having two or more ethylenically unsaturated bonds in the molecule. The radically polymerizable compound (B) may be used alone or in combination of two or more. The radically polymerizable compound (B) may be bifunctional, trifunctional or higher. In resin composition C1, the radically polymerizable compound (B) is not essential, but resin composition C1 may contain a polymerization reaction product of the radically polymerizable compound (B).

[0048] Examples of the bifunctional radically polymerizable compound (B) include bifunctional aromatic vinyl compounds such as divinylbenzene, divinylnaphthalene, and divinylbiphenyl; ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and ethoxylated polypropylene glycol. difunctional aliphatic (meth)acrylate compounds such as di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, glycerin di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, and ethoxylated 2-methyl-1,3-propanediol di(meth)acrylate;Cyclohexanedimethanol di(meth)acrylate, ethoxylated cyclohexanedimethanol di(meth)acrylate, propoxylated cyclohexanedimethanol di(meth)acrylate, ethoxylated propoxylated cyclohexanedimethanol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, ethoxylated tricyclodecane dimethanol di(meth)acrylate, propoxylated tricyclodecane dimethanol di(meth)acrylate, ethoxylated propoxylated tricyclodecane dimethanol di(meth)acrylate Bifunctional alicyclic (meth)acrylate compounds such as cyclodecane dimethanol di(meth)acrylate, ethoxylated hydrogenated bisphenol A di(meth)acrylate, propoxylated hydrogenated bisphenol A di(meth)acrylate, ethoxylated propoxylated hydrogenated bisphenol A di(meth)acrylate, ethoxylated hydrogenated bisphenol F di(meth)acrylate, propoxylated hydrogenated bisphenol F di(meth)acrylate, and ethoxylated propoxylated hydrogenated bisphenol F di(meth)acrylate; Ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, ethoxylated propoxylated bisphenol A di(meth)acrylate, ethoxylated bisphenol F di(meth)acrylate, propoxylated bisphenol F di(meth)acrylate, ethoxylated propoxylated bisphenol F di(meth)acrylate, ethoxylated bisphenol AF di(meth)acrylate, propoxylated bisphenol AF di(meth)acrylate, ethoxylated propoxylated bisphenol Examples of suitable aromatic (meth)acrylate compounds include bifunctional aromatic (meth)acrylate compounds such as phenol AF di(meth)acrylate, ethoxylated fluorene di(meth)acrylate, propoxylated fluorene di(meth)acrylate, and ethoxylated propoxylated fluorene di(meth)acrylate; and bifunctional heterocyclic (meth)acrylate compounds such as ethoxylated isocyanuric acid di(meth)acrylate, propoxylated isocyanuric acid di(meth)acrylate, and ethoxylated propoxylated isocyanuric acid di(meth)acrylate.

[0049] Examples of the trifunctional or higher functional radical polymerizable compound (B) include trialkenyl isocyanurate compounds such as triallyl cyanurate and triallyl isocyanurate; trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, ethoxylated propoxylated trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate, propoxylated pentaerythritol tri(meth)acrylate, ethoxylated propoxylated pentaerythritol tri(meth)acrylate, and polyfunctional aliphatic (meth)acrylate compounds such as acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate, propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated propoxylated pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetraacrylate, and dipentaerythritol hexa(meth)acrylate; and polyfunctional heterocyclic (meth)acrylate compounds such as ethoxylated isocyanuric acid tri(meth)acrylate, propoxylated isocyanuric acid tri(meth)acrylate, and ethoxylated propoxylated isocyanuric acid tri(meth)acrylate.

[0050] When a styrene-based thermoplastic elastomer is used as the thermoplastic resin (A), at least one selected from the group consisting of a bifunctional aromatic vinyl compound and a trialkenyl isocyanurate compound is preferred from the viewpoint of exhibiting appropriate solubility in the styrene-based thermoplastic elastomer, and divinylbenzene and triallyl isocyanurate are more preferred, and trialkenyl isocyanurate is even more preferred from the viewpoint of low dielectric properties.

[0051] The radical polymerizable compound (B) preferably has no polar functional groups or a small number of polar functional groups in the molecule. When the radical polymerizable compound (B) has a cyclic structure, it preferably has no polar functional groups or a small number of polar functional groups in the substituent. When the number of polar functional groups is small, the solubility in the thermoplastic resin (A) is good, and the dielectric loss tangent of the obtained sheet cured product is also low.

[0052] The polar functional group refers to a functional group that has a negative atom (e.g., nitrogen, oxygen, chlorine, fluorine, etc.) and has a net dipole. Examples include an ester group, a carbonyl group, a carboxyl group, a hydroxyl group, an amide group, and an amino group.

[0053] When the radical polymerizable compound (B) has an ester group, the polar functional group equivalent of the radical polymerizable compound (B) is preferably 2 or more, more preferably 3 or more, even more preferably 4 or more, even more preferably 5 or more, and even more preferably 6 or more. The polar functional group equivalent is the ratio of the molecular weight of the radical polymerizable compound (B) to the molecular weight of the polar functional group of the radical polymerizable compound (B) (molecular weight of the radical polymerizable compound (B) / molecular weight of the polar functional group of the radical polymerizable compound (B)). When the radical polymerizable compound (B) has multiple polar functional groups, the total amount of those polar functional groups is taken as the molecular weight of the polar functional group.

[0054] The content of the radical polymerizable compound (B) in the resin composition C2 is preferably 1 part by mass or more but less than 50 parts by mass, more preferably 3 parts by mass or more but less than 25 parts by mass, and even more preferably 5 parts by mass or more but less than 20 parts by mass, per 100 parts by mass of the thermoplastic resin (A). When the content of the radical polymerizable compound (B) is within the above range, it becomes easier to increase the crosslink density artificially without reducing the dielectric properties of the thermoplastic resin (A). Therefore, the dielectric properties and heat resistance of the obtained cured sheet are further improved. However, the radical polymerizable compound (B) does not fall under the category of "resin component" in this specification.

[0055] 3. Cyclic Polyolefin Resin Copolymer (C) The present composition may further contain a cyclic polyolefin resin copolymer (C) for the purpose of reducing the linear thermal expansion coefficient, reducing tackiness, etc. The reason why the linear thermal expansion coefficient, tackiness, etc. are improved is not clear, but it is thought that this is because the inclusion of the cyclic polyolefin resin copolymer (C) together with the thermoplastic resin (A) introduces a rigid skeleton into the molecule.

[0056] The cyclic polyolefin resin copolymer (C) is a copolymer having an alicyclic structure, i.e., a copolymer having an alicyclic structure in a side chain of a polyolefin. Suitable examples of the alicyclic structure include cycloalkanes, bicycloalkanes, polycyclic compounds, etc. Among these, cycloalkanes are preferred, and cyclohexane is more preferred. The alicyclic structure is more preferably an alicyclic structure generated by hydrogenation of an aromatic ring contained in a hydrogenated aromatic vinyl polymer block unit described below.

[0057] The crystalline melting peak temperature of the cyclic polyolefin resin copolymer (C) is preferably less than 100° C. The crystalline melting peak temperature of the cyclic polyolefin resin copolymer (C) is preferably 50° C. or higher, more preferably 60° C. or higher, and even more preferably 65° C. or higher. The crystalline melting peak temperature of the cyclic polyolefin resin copolymer is preferably 90° C. or lower, more preferably 85° C. or lower.

[0058] The crystalline melting peak temperature is the temperature at which a crystalline melting peak is detected in differential scanning calorimetry (DSC) measured at a heating rate of 10°C / min. The cyclic polyolefin resin copolymer (C) used in the present composition may have a crystalline melting peak at less than 100°C, and may have a crystalline melting peak at two points, for example, less than 100°C and at or above 100°C.

[0059] Known cyclic polyolefins include hydrogenated ring-opening polymers having units derived from monocyclic norbornene-based or polycyclic norbornene-based monomers (e.g., WO 2012 / 046443, WO 2012 / 033076, etc.). These cyclic polyolefins have an alicyclic structure in the polymer main chain, and either do not have a crystalline melting peak temperature below 100°C or are amorphous.

[0060] The crystallinity of a polymer usually varies depending on the regularity of the molecular structure and steric hindrance, and polymers having an alicyclic structure in the side chain or main chain are difficult to crystallize due to the large steric hindrance, and tend to become amorphous. On the other hand, the cyclic polyolefin resin copolymer (C) of the present composition exhibits crystallinity due to the structure of the hydrogenated conjugated diene polymer block unit described below, and the alicyclic structure in the polyolefin side chain allows the crystalline melting peak temperature to be below 100°C.

[0061] The melt flow rate (MFR) of the cyclic polyolefin resin copolymer (C) is not particularly limited, but is usually 0.1 g / 10 min or more, and from the viewpoint of the molding method and the appearance of the molded product, preferably 0.5 g / 10 min or more. Furthermore, the melt flow rate (MFR) is usually 200 g / 10 min or less, and from the viewpoint of material strength, it is preferably 100 g / 10 min or less, more preferably 90.0 g / 10 min or less. By setting the MFR within the above range, compatibility with thermoplastic resins is improved. The MFR is determined by measuring in accordance with ISO R1133 under conditions of a measurement temperature of 230°C and a measurement load of 2.16 kg.

[0062] From the viewpoint of low dielectric properties, the cyclic polyolefin resin copolymer (C) is preferably a cyclic polyolefin containing at least one hydrogenated aromatic vinyl polymer block unit and at least one hydrogenated conjugated diene polymer block unit (hereinafter also referred to as "cyclic polyolefin (a)"), or a modified product of the cyclic polyolefin (a) with at least one of an unsaturated carboxylic acid and an anhydride thereof.

[0063] As used herein, the term "block" refers to a polymeric segment of a copolymer that exhibits microphase separation from structurally or compositionally distinct polymeric segments of the copolymer. Microphase separation occurs due to the immiscibility of polymeric segments in a block copolymer. Microphase separation and block copolymers are extensively discussed in "Block Copolymers - Designer Soft Materials," February 1999 issue of PHYSICS TODAY, pp. 32-38.

[0064] Examples of the cyclic polyolefin (a) include a diblock copolymer composed of a hydrogenated aromatic vinyl polymer block unit (hereinafter also referred to as "block A") and a hydrogenated conjugated diene polymer block unit (hereinafter also referred to as "block B"), a triblock copolymer containing two or more of at least one of block A and block B, a tetrablock copolymer, and a pentablock copolymer. The cyclic polyolefin (a) preferably contains at least two blocks A, and suitable examples thereof include an A-B-A type, an A-B-A-B type, and an A-B-A-B-A type.

[0065] The cyclic polyolefin (a) preferably contains a segment composed of an aromatic vinyl polymer at each end. Therefore, the hydrogenated block copolymer of the present composition preferably has at least two hydrogenated aromatic vinyl polymer block units (blocks A) and at least one hydrogenated conjugated diene polymer block unit (block B) between the two hydrogenated aromatic vinyl polymer block units (blocks A). From these viewpoints, the cyclic polyolefin (a) is more preferably an A-B-A type or an A-B-A-B-A type.

[0066] The content of hydrogenated aromatic vinyl polymer block units (block A) in the cyclic polyolefin (a) is preferably 30 to 99 mol%, more preferably 40 to 90 mol%. It is even more preferably 50 mol% or more, and even more preferably 60 mol% or more. When the ratio of hydrogenated aromatic vinyl polymer block units (block A) is equal to or greater than the lower limit, rigidity is not reduced, and heat resistance and linear thermal expansion coefficient are also improved. On the other hand, when the ratio is equal to or less than the upper limit, flexibility is improved.

[0067] The content of hydrogenated conjugated diene polymer block units (block B) in the cyclic polyolefin (a) is preferably 1 to 70 mol%, more preferably 10 to 60 mol%. It is even more preferably 50 mol% or less, and even more preferably 40 mol% or less. When the ratio of hydrogenated conjugated diene polymer block units (block B) is equal to or greater than the lower limit, flexibility is improved. On the other hand, when the ratio is equal to or less than the upper limit, rigidity is not reduced, and heat resistance and linear thermal expansion coefficient are also improved.

[0068] The hydrogenated aromatic vinyl polymer block unit and the hydrogenated conjugated diene polymer block unit constituting the cyclic polyolefin (a) can be obtained by hydrogenating polymer blocks composed of an aromatic vinyl monomer and a conjugated diene monomer such as 1,3-butadiene, which will be described in detail later.

[0069] The cyclic polyolefin (a) is preferably a block copolymer without functional groups. The term "without functional groups" means that the block copolymer does not contain any functional groups, i.e., does not contain any groups containing atoms other than carbon and hydrogen atoms.

[0070] The monomers for forming the aromatic vinyl polymer block unit and the conjugated diene polymer block unit before hydrogenation will be described below.

[0071] (Aromatic Vinyl Monomer) The aromatic vinyl monomer serving as a raw material for the aromatic vinyl polymer block unit before hydrogenation is a monomer represented by the following formula (1).

[0072]

[0073] In formula (1), R is hydrogen or an alkyl group, and Ar is a phenyl group, a halophenyl group, an alkylphenyl group, an alkylhalophenyl group, a naphthyl group, a pyridinyl group, or an anthracenyl group.

[0074] In formula (1), when R is an alkyl group, the number of carbon atoms is preferably 1 to 6, and the alkyl group may be mono- or polysubstituted with functional groups such as halo groups, nitro groups, amino groups, hydroxy groups, cyano groups, carbonyl groups, and carboxyl groups.

[0075] Ar is preferably a phenyl group or an alkylphenyl group, more preferably a phenyl group.

[0076] Examples of aromatic vinyl monomers include styrene, α-methylstyrene, vinyltoluene (including all isomers, with p-vinyltoluene being particularly preferred), ethylstyrene, propylstyrene, butylstyrene, vinylbiphenyl, vinylnaphthalene, vinylanthracene (including all isomers), and mixtures thereof. Of these, styrene is preferred.

[0077] (Conjugated Diene Monomer) The conjugated diene monomer used as a raw material for the conjugated diene polymer block unit before hydrogenation is not particularly limited as long as it is a monomer having two conjugated double bonds. Examples of conjugated diene monomers include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2-methyl-1,3-pentadiene and analogous compounds thereof, and mixtures thereof. Among these, 1,3-butadiene is preferred from the viewpoint of obtaining a block having a high structural regularity and being easily crystallized.

[0078] When 1,3-butadiene is used as the conjugated diene monomer, its polymer, polybutadiene, contains 1,4-bond units ([—CH ２ -CH=CH-CH ２ -]) and 1,2-bond units ([-CH ２ -CH(CH=CH ２)-]), the former gives a structure similar to an ethylene unit (ethylene structure), and the latter gives a structure similar to a 1-butene unit (1-butene structure) upon hydrogenation. Therefore, the hydrogenated conjugated diene polymer block in the present composition preferably contains at least one of an ethylene structure and a 1-butene structure.

[0079] When isoprene is used as the conjugated diene monomer, its polymer, polyisoprene, contains 1,4-bond units ([—CH ２ -C(CH ３ )=CH-CH ２ -]), 3,4-bond unit ([-CH ２ -CH(C(CH ３ ) = CH ２ )-]) and 1,2-bond units ([-CH ２ -C(CH ３ ) (CH=CH ２ )-]) is present, and the resulting copolymer contains at least one of the three types of units obtained by hydrogenation.

[0080] (Block Structure) The cyclic polyolefin (a) is preferably produced by hydrogenation of a multiblock copolymer such as a triblock copolymer, a tetrablock copolymer, or a pentablock copolymer, such as SBS, SBSB, SBSBS, SBSBSB, SIS, SISIS, and SISBS (where S is polystyrene, B is polybutadiene, and I is polyisoprene). The block may be a linear block or may be branched. When branched, the polymerization chain may be bonded at any position along the backbone of the copolymer. In addition to a linear block, the block may be a tapered block or a star block.

[0081] The block copolymer constituting the cyclic polyolefin (a) before hydrogenation may contain one or more additional block units other than the aromatic vinyl polymer block units and the conjugated diene polymer block units. For example, in the case of a triblock copolymer, these additional block units may be bonded to any position on the triblock polymer backbone.

[0082] A preferred example of the hydrogenated aromatic vinyl polymer block unit is hydrogenated polystyrene. A preferred example of the hydrogenated conjugated diene polymer block unit is hydrogenated polybutadiene or hydrogenated polyisoprene. Of the hydrogenated conjugated diene polymer block units, hydrogenated polybutadiene is more preferred.

[0083] Suitable examples of the cyclic polyolefin (a) include hydrogenated triblock or pentablock copolymers of styrene and butadiene, with hydrogenated triblock copolymers being more preferred.

[0084] (Hydrogenation Level) The cyclic polyolefin (a) is one in which not only the double bonds derived from conjugated dienes such as butadiene but also the aromatic rings derived from styrene etc. are hydrogenated, and is substantially completely hydrogenated. Specifically, this refers to one that has achieved the following hydrogenation levels:

[0085] The hydrogenation level of the hydrogenated aromatic vinyl polymer block unit is preferably 90% or higher, more preferably 95% or higher, even more preferably 98% or higher, and particularly preferably 99.5% or higher. The hydrogenation level of the hydrogenated conjugated diene polymer block unit is preferably 95% or higher, more preferably 99% or higher, and even more preferably 99.5% or higher. Such a high level of hydrogenation can reduce dielectric loss and improve rigidity and heat resistance.

[0086] The hydrogenation level of the hydrogenated aromatic vinyl polymer block unit indicates the proportion of the aromatic vinyl polymer block unit saturated by hydrogenation. The hydrogenation level of the hydrogenated conjugated diene polymer block unit indicates the proportion of the conjugated diene polymer block unit saturated by hydrogenation. The hydrogenation level of each block unit is determined using proton NMR.

[0087] The cyclic polyolefin resin copolymer (C) may be used alone or in combination of two or more. As the cyclic polyolefin resin copolymer (C) in the present composition, commercially available products can be used, and a specific example is TEFABLOC (registered trademark) manufactured by Mitsubishi Chemical Corporation.

[0088] When the present composition further contains a cyclic polyolefin resin copolymer (C), the content of the cyclic polyolefin resin copolymer (C) is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more of the resin components of the present composition from the viewpoints of reducing the linear thermal expansion coefficient and reducing tackiness, while the upper limit is preferably 40% by mass or less, more preferably 38% by mass or less, and even more preferably 35% by mass or less from the viewpoints of flexibility and adhesion to the substrate.

[0089] 4. Organic Peroxide (D) The present composition may further contain an organic peroxide (D) for the purpose of accelerating the curing reaction. Examples of organic peroxides include those belonging to the groups of hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters, and ketone peroxides.

[0090] Specific examples include hydroperoxides such as cumene hydroperoxide and tert-butyl hydroperoxide; dialkyl peroxides such as dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne and α,α-di(tert-butylperoxyisopropyl)benzene; diacyl peroxides such as lauryl peroxide and benzoyl peroxide; peroxy esters such as tert-butyl peroxyacetate, tert-butyl peroxybenzoate and tert-butylperoxyisopropyl carbonate; and ketone peroxides such as cyclohexanone peroxide.

[0091] The content of the organic peroxide (D) in the composition is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, and even more preferably 0.1 to 1 part by mass, per 100 parts by mass of the thermoplastic resin (A). When the content of the organic peroxide (D) is within the above range, the curing reaction can be promoted while maintaining low dielectric properties of the cured sheet.

[0092] 5. Solvent (E) When the resin layer is formed from the composition via a coating process, the composition may further contain a solvent (E). The solvent (E) is not particularly limited as long as it can uniformly dissolve the thermoplastic resin (A) and the radically polymerizable compound (B), and examples of the solvent include toluene, cyclohexane, tetrahydrofuran, and xylene.

[0093] The solvent (E) preferably has a boiling point of 200° C. or less so that it volatilizes when the resin layer is dried.

[0094] From the viewpoint of film-forming properties, the content of the solvent (E) in the present composition is preferably 100 parts by mass or more and 500 parts by mass or less, and more preferably 200 parts by mass or more and 400 parts by mass or less, per 100 parts by mass of the thermoplastic resin (A).

[0095] 6. Other Components The present composition may further contain, as components other than those described above, a thermoplastic elastomer other than the thermoplastic resin (A), a crosslinking agent other than the radically polymerizable compound (B), an ultraviolet absorber, an antistatic agent, an antioxidant, a coupling agent, a plasticizer, a flame retardant, a colorant, a dispersant, an emulsifier, an elasticity reducing agent, a diluent, an antifoaming agent, an ion trapping agent, a thickener, a leveling agent, inorganic particles, organic particles, etc.

[0096] When the present composition contains a resin component other than the thermoplastic resin (A) and the cyclic polyolefin resin copolymer (C), the content thereof is less than 50 mass % of the total mass of the present composition, preferably less than 40 mass %, more preferably less than 30 mass %, and even more preferably less than 20 mass %.

[0097] Examples of the crosslinking agent other than the radically polymerizable compound (B) include bismaleimide compounds and epoxy compounds.

[0098] Examples of inorganic particles include calcium carbonate, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, zinc oxide, magnesium oxide, calcium oxide, titanium oxide, aluminum oxide, zinc oxide, alumina, aluminum hydroxide, hydroxyapatite, silica, magnesium silicate, mica, talc, kaolin, clay, glass powder, asbestos powder, zeolite, and clay silicate.

[0099] Examples of organic particles include (meth)acrylate resin particles, styrene resin particles, silicone resin particles, nylon resin particles, polyethylene resin particles, benzoguanamine resin particles, and urethane resin particles.

[0100] When inorganic particles or organic particles are contained, the content thereof is preferably 1 part by mass or more and 200 parts by mass or less, more preferably 5 parts by mass or more and 150 parts by mass or less, and even more preferably 10 parts by mass or more and 100 parts by mass or less, per 100 parts by mass of the resin component of the composition. When the content of inorganic particles or organic particles is equal to or more than the above-mentioned lower limit, the dielectric properties of the cured sheet can be further reduced, and the linear thermal expansion coefficient of the cured sheet can be reduced, making it less likely to peel from the substrate when used as a circuit board material. On the other hand, when the content of inorganic particles or organic particles is equal to or less than the above-mentioned upper limit, the moldability of the cured sheet can be improved.

[0101] Physical properties of the resin layer: The relative dielectric constant of the resin layer is preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.5 or less. The lower limit of the relative dielectric constant is not particularly limited, as long as it is 1.0 or more. The dielectric loss tangent of the resin layer is preferably 0.0020 or less, more preferably 0.0018 or less, and even more preferably 0.0015 or less. The lower limit of the dielectric loss tangent is not particularly limited, as long as it is 0 or more.

[0102] The relative permittivity and dielectric loss tangent of the resin layer are values ​​determined by measurement at a temperature of 23°C and a frequency of 10 GHz in accordance with JIS C2565: 1992. However, when the resin layer is curable, the values ​​are determined by measurement at a temperature of 23°C and a frequency of 10 GHz in accordance with JIS C2565: 1992 using a test piece obtained by heat pressing the composition at 200°C and 2 MPa for 30 minutes to obtain a cured product.

[0103] The thickness of the resin layer is preferably 3 to 475 μm, more preferably 4 to 380 μm, and even more preferably 5 to 285 μm. When the thickness of the resin layer in the laminate sheet is within the above range, handling properties and conformability to unevenness in the board when the laminate sheet is used as a circuit board material are improved.

[0104] (Support Layer) The support layer contains at least one selected from the group consisting of polyimide resin, cyclic olefin resin (excluding cyclic polyolefin resin copolymer (C)), liquid crystal polymer, and polyamide resin as a main component. Such a support layer allows for a laminate sheet to be obtained that has a reduced linear thermal expansion coefficient, excellent dimensional stability, and good heat resistance.

[0105] From the viewpoint of heat resistance and dimensional stability, a support layer containing either or both of a polyimide resin and a cyclic olefin resin as a main component is preferred. The polyimide resin is not particularly limited as long as it has an imide bond as a repeating unit in the main chain, and examples thereof include polymers of aliphatic or aromatic diamines and aliphatic or aromatic acid anhydrides. The polyimide resin may be a modified polyimide resin. Modified polyimide resins are preferred from the viewpoint of even better adhesion and heat resistance. The "main component" in the support layer refers to the component contained in the largest amount in the support layer, specifically, a component contained in an amount of 50% by mass or more, preferably 60% by mass or more, when the total mass of the support layer is 100%.

[0106] Examples of commercially available polyimide resin films include "Kapton" manufactured by DuPont, "APICAL" manufactured by Kaneka, "UPILEX" manufactured by UBE, and "ZENOMAX" manufactured by Zenomax Japan. Examples of commercially available modified polyimide resin films include "Pixio" manufactured by Kaneka.

[0107] Examples of commercially available cyclic olefin resins include "Topas (registered trademark)" manufactured by Ticona, "ARTON" manufactured by JSR, "ZEONOR" and "ZEONEX" manufactured by Zeon Corporation, and "APEL" manufactured by Mitsui Chemicals. Examples of commercially available cyclic olefin resin films include "ZEONOR Film" manufactured by Zeon Corporation and "ARTON Film" manufactured by JSR Corporation.

[0108] The thickness of the support layer is preferably 2 to 500 μm, more preferably 3 to 400 μm, and even more preferably 5 to 300 μm. When the thickness of the support layer in the present laminate sheet is equal to or greater than the above-mentioned lower limit, the handleability is improved. When the thickness of the support layer in the present laminate sheet is equal to or less than the above-mentioned upper limit, when the present laminate sheet is used as a circuit board material, the heat resistance and conformability to unevenness in the board are improved.

[0109] The linear thermal expansion coefficient of the support layer is preferably 50 ppm or less, more preferably 40 ppm / °C or less, even more preferably 30 ppm / °C or less, particularly preferably 25 ppm / °C or less, and most preferably 20 ppm / °C or less, from the viewpoint of preventing distortion or peeling due to the difference in linear thermal expansion coefficient with the conductor when the laminate sheet is used in combination with a conductor and heat is applied. The lower limit of the linear thermal expansion coefficient of the support layer is not particularly limited, but is preferably 0 ppm / °C or more. The linear thermal expansion coefficient of the support layer can be measured by thermomechanical analysis using a method in accordance with JIS K7197 (2012).

[0110] The relative permittivity of the support layer is preferably 5.0 or less, more preferably 4.5 or less, and even more preferably 4.0 or less. The lower limit of the relative permittivity of the support layer is not particularly limited, as long as it is 1.0 or more. The dielectric loss tangent of the support layer is preferably 0.020 or less, more preferably 0.015 or less, and even more preferably 0.010 or less. The lower limit of the dielectric loss tangent of one support layer is not particularly limited, as long as it is 0 or more. The relative permittivity and dielectric loss tangent of the support layer are values ​​measured at 10 GHz using a perturbation method cavity resonator.

[0111] The support layer may be embossed or processed to have various irregularities (such as conical, pyramidal, or hemispherical shapes) as needed. In addition, the surface may be subjected to various surface treatments such as corona treatment, plasma treatment, and primer treatment in order to improve adhesion to the resin layer.

[0112] (Layer structure of laminate sheet) As shown in Fig. 1, the present laminate sheet has a support layer 1 and resin layers 2, 2 provided on both sides of the support layer 1. Because the resin layers 2, 2 are provided on both sides of the support layer 1, superior flexibility and warp resistance can be expected compared to a case where a resin layer is provided on only one side of the support layer. The present laminate sheet may be a multilayer structure in which the support layer 1 and the resin layer 2 are sequentially laminated, as shown in Fig. 2. However, a three-layer structure in which the resin layers 2, 2 are provided on both sides of the support layer 1, as shown in Fig. 1, is most preferred.

[0113] When the laminate sheet has multiple support layers, both surfaces of the laminate sheet are resin layers. The thicknesses and materials of the multiple support layers may be the same or different. Similarly, the thicknesses and compositions of the multiple resin layers may be the same or different.

[0114] When the laminate sheet has a three-layer structure having resin layers on both sides of a support layer, the resin composition forming one resin layer and the resin composition forming the other resin layer may be the same or different, but from the viewpoint of ease of production, the same resin composition is preferred. Furthermore, the thickness of one resin layer and the other resin layer may be the same or different, but the same thickness is preferred.

[0115] The thickness of the present laminate sheet is preferably 10 to 500 μm, more preferably 20 to 400 μm, and even more preferably 30 to 300 μm. When the thickness of the present laminate sheet is equal to or greater than the above-mentioned lower limit, handling properties are improved. When the thickness of the present laminate sheet is equal to or less than the above-mentioned upper limit, conformability to unevenness in the board is improved when the present laminate sheet is used as a circuit board material. The thickness of the present laminate sheet can be measured with a micrometer. Alternatively, the thickness of the present laminate sheet may be calculated by observing the cross section of the present laminate sheet with a microscope or the like. When the present laminate sheet is curable, the thickness of the present laminate sheet may be a value measured on a cured product of the present laminate sheet.

[0116] The ratio of the thickness of the support layer to the total thickness of the present laminate sheet is preferably 5% or more and less than 100%. If the thickness ratio of the support layer is equal to or more than the above lower limit, the support layer can preferably improve heat resistance and suppress the linear thermal expansion coefficient. If the thickness ratio of the support layer is less than the above upper limit, the laminate sheet can have low dielectric properties and excellent adhesion to conductors. From this perspective, the thickness ratio of the support layer is preferably 3% or more and 70% or less, more preferably 4% or more and 60% or less, and even more preferably 5% or more and 50% or less.

[0117] The present laminate sheet satisfies the following formula (Z1).

[0118] Y / (X+Y)≦0.40 Formula (Z1) In formula (Z1), X is the thickness of the resin layer in the present laminate sheet, and Y is the thickness of the support layer in the present laminate sheet.

[0119] When the ratio (Y / (X+Y)) of the thickness (Y) of the support layer to the total thickness (X+Y) of the laminate sheet is 0.40 or less, the low dielectric properties and adhesion to conductors are improved, and the wet heat stability of the dielectric properties is also improved. From this viewpoint, (Y / (X+Y)) is more preferably 0.35 or less, even more preferably 0.30 or less, particularly preferably 0.25 or less, and most preferably 0.20 or less. From the viewpoint of being able to optimally exhibit the heat resistance improving effect and the linear thermal expansion coefficient suppressing effect of the support layer, the lower limit of (Y / (X+Y)) is preferably 0.03 or more, more preferably 0.04 or more, and even more preferably 0.05 or more.

[0120] The thickness (X) of the resin layer is the sum of the thicknesses of the resin layers in the present laminate sheet. When the present laminate sheet has multiple support layers, the thickness (Y) of the support layers is the sum of the thicknesses of the multiple support layers.

[0121] The thickness (Y) of the support layer and the thickness (X) of the resin layer in this laminate sheet can be measured with a micrometer. The thickness of each layer may be determined by measuring the thickness (Y) of the support layer and the thickness (X) of the resin layer with a micrometer or the like during the production of the laminate sheet, or the thickness of each layer may be measured with a micrometer after the laminate sheet is produced by separating the support layer and the resin layer. The thickness of each layer may also be calculated by observing the cross section of the laminate sheet with a microscope or the like.

[0122] The thickness of the present laminate sheet as a circuit board material can be measured with a micrometer after removing the conductors, etc. The thickness of the present laminate sheet as a circuit board material can also be calculated by observing the cross section of the circuit board material with a microscope, etc., to determine the thickness of each layer. When the present laminate sheet is sandwiched between two members, the distance between the two members can also be taken as the thickness of the present laminate sheet.

[0123] (Physical Properties of Laminate Sheet S1) The dielectric constant of the laminate sheet S1 is preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.5 or less. There is no particular lower limit to the dielectric constant of the laminate sheet S1, as long as it is 1.0 or more.

[0124] The dielectric loss tangent of the laminate sheet S1 is preferably 0.0060 or less, more preferably 0.0050 or less, and even more preferably 0.0030 or less. Of these, 0.0020 or less is preferred, 0.0018 or less is more preferred, and 0.0015 or less is even more preferred. The lower limit of the dielectric loss tangent of the laminate sheet S1 is not particularly limited, and may be any value as long as it is 0 or more. The relative permittivity and dielectric loss tangent are values ​​measured in accordance with JIS C2565:1992 under conditions of a temperature of 25°C, 50% RH, and a frequency of 10 GHz.

[0125] The dielectric loss tangent of the laminate sheet S1 after storage in an environment of 85°C and 85% RH is preferably 0.0100 or less, more preferably 0.0090 or less, even more preferably 0.0070 or less, even more preferably 0.0060 or less, and particularly preferably 0.0050 or less, from the viewpoint of environmental stability. The smaller the change in the dielectric loss tangent value before and after the moist heat test, the more preferable. The dielectric loss tangent is a value obtained by measurement in accordance with JIS C2565:1992 at a temperature of 23°C and a frequency of 10 GHz.

[0126] From the viewpoint of heat resistance, the storage modulus of the laminate sheet S1 is preferably 1 MPa or more, more preferably 5 MPa or more, and even more preferably 10 MPa or more. The upper limit of the storage modulus of the laminate sheet S1 is not particularly limited, but from the viewpoint of obtaining appropriate flexibility, it is preferably 7000 MPa or less, more preferably 6000 MPa or less. The storage modulus is a value obtained by reading the value of the storage modulus at 24°C from the results of measuring dynamic viscoelasticity.

[0127] From the viewpoint of heat resistance when mounted on a device, the heat resistance temperature of the laminate sheet S1 is preferably 200° C. or higher and 500° C. or lower. The heat resistance temperature is a value obtained by reading the temperature just before the laminate sheet changes from a rubber-like flat region to a viscous liquid state in a graph obtained by measuring the dynamic viscoelasticity of the laminate sheet.

[0128] The linear thermal expansion coefficient of the laminate sheet S1 is preferably 60 ppm / °C or less, more preferably 50 ppm / °C or less, even more preferably 40 ppm / °C or less, particularly preferably 30 ppm / °C or less, and most preferably 25 ppm / °C or less, from the viewpoint of preventing distortion or peeling due to the difference in linear thermal expansion coefficient with the conductor when heat is applied when used in combination with the conductor. The lower limit of the linear thermal expansion coefficient of the laminate sheet S1 is not particularly limited, but is preferably 0 ppm / °C or more.

[0129] The linear thermal expansion coefficient is a value measured by thermomechanical analysis according to a method in accordance with JIS K7197 (2012). Specifically, using a thermal analyzer "TMA 841" (manufactured by Mettler Toledo), the sample shape is 5 mm wide x 16 mm long, and the measurement is started from 30 ° C., heated to 100 ° C. at a rate of 5 ° C. / min, cooled to 0 ° C., and then reheated to 150 ° C. The dimensional change during the reheating process is measured. Based on this measurement result, the average value of the thermal expansion coefficient in the in-plane direction from 0 to 120 ° C. is calculated.

[0130] (Physical properties of laminate sheet S2) The laminate sheet S2 is curable. For curing, known methods such as heat curing and active energy ray curing using ultraviolet rays, electron beams, etc. can be used. Among the many curing methods, a thermosetting laminate sheet S2 is preferred. A laminate sheet having a curable resin layer L2 on both sides of a support layer, that is, a laminate sheet having a support layer laminated on both sides of an uncured resin layer L2, is preferred. The physical properties of the laminate sheet S2 will be described below.

[0131] The dielectric constant of the laminate sheet S2 after curing is preferably 4.0 or less, more preferably 3.0 or less, and even more preferably 2.5 or less. There is no particular lower limit for the dielectric constant of the laminate sheet S2 after curing, as long as it is 1.0 or more.

[0132] The dielectric loss tangent of the laminate sheet S2 after curing is preferably 0.0060 or less, more preferably 0.0050 or less, and even more preferably 0.0030 or less. Among these, 0.002 or less is preferable, 0.0018 or less is more preferable, and 0.0015 or less is even more preferable. The lower limit of the dielectric loss tangent of the laminate sheet S2 after curing is not particularly limited, and it is sufficient if it is 0 or more.

[0133] The relative permittivity and dielectric loss tangent of the laminated sheet S2 were determined by measuring the cured product obtained by heat-pressing the laminated sheet S2 at 200°C and 2 MPa for 30 minutes as a test piece at a temperature of 25°C, 50% RH, and a frequency of 10 GHz in accordance with JIS C2565:1992.

[0134] The dielectric loss tangent of the cured laminate sheet S2 after storage in an environment of 85°C and 85% RH is preferably 0.0100 or less, more preferably 0.0090 or less, even more preferably 0.0070 or less, even more preferably 0.0060 or less, and particularly preferably 0.0050 or less, from the viewpoint of environmental stability. The smaller the change in the dielectric loss tangent value before and after the moist heat test, the more preferable. The dielectric loss tangent is a value obtained by measurement in accordance with JIS C2565:1992 at a temperature of 23°C and a frequency of 10 GHz.

[0135] From the viewpoint of heat resistance, the storage modulus of the laminate sheet S2 after curing is preferably 1 MPa or more, more preferably 5 MPa or more, and even more preferably 10 MPa or more. The upper limit of the storage modulus of the laminate sheet S2 after curing is not particularly limited, but from the viewpoint of obtaining appropriate flexibility, it is preferably 7000 MPa or less, more preferably 6000 MPa or less.

[0136] The storage modulus of the laminated sheet S2 after curing was determined by heat pressing the laminated sheet S2 at 200°C and 2 MPa for 30 minutes to obtain a cured product, which was used as a test piece, and reading the storage modulus at 24°C from the results of measuring the dynamic viscoelasticity.

[0137] From the viewpoint of heat resistance when mounted on a device, the heat resistance temperature of the laminate sheet S2 after curing is preferably 200° C. or higher and 500° C. or lower. The heat resistance temperature of the laminate sheet S2 after curing is a value obtained by reading the temperature just before the laminate sheet S2 changes from a rubber-like flat region to a viscous liquid state on a graph obtained by measuring the dynamic viscoelasticity of a test piece obtained by heat pressing the laminate sheet S2 at 200° C. and 2 MPa for 30 minutes.

[0138] The coefficient of linear thermal expansion of the laminate sheet S2 after curing is preferably 60 ppm / °C or less, more preferably 50 ppm / °C or less, even more preferably 40 ppm / °C or less, particularly preferably 30 ppm / °C or less, and most preferably 25 ppm / °C or less, from the viewpoint of preventing distortion or peeling due to the difference in the coefficient of linear thermal expansion with the conductor when heat is applied when used in combination with the conductor. There is no particular restriction on the lower limit of the coefficient of linear thermal expansion of the laminate sheet S2 after curing, but 0 ppm / °C or more is preferred.

[0139] The linear thermal expansion coefficient of the laminate sheet S2 after curing can be measured by thermomechanical analysis according to JIS K7197 (2012) using a test piece obtained by heat-pressing the laminate sheet at 200 ° C and 2 MPa for 30 minutes. Specifically, using a thermal analyzer "TMA 841" (manufactured by Mettler Toledo), the sample shape is 5 mm wide x 16 mm long, and the measurement is started from 30 ° C, heated to 100 ° C at 5 ° C / min, cooled to 0 ° C, and then reheated to 150 ° C. The dimensional change during the reheating process is measured. Based on this measurement result, the average value of the thermal expansion coefficient in the in-plane direction from 0 to 120 ° C is calculated.

[0140] The preferred physical properties of the laminate sheet S2 described below also apply to the laminate sheet S1. The thickness of the laminate sheet is preferably 10 to 500 μm, more preferably 50 to 400 μm, and even more preferably 100 to 350 μm. When the thickness of the laminate sheet is equal to or greater than the above lower limit, handling properties are improved. When the thickness of the laminate sheet is equal to or less than the above upper limit, conformability to unevenness in the board is improved when the laminate sheet is used as a circuit board material. The thickness of the laminate sheet can be measured with a micrometer. The thickness of the laminate sheet may also be calculated by observing the cross section of the laminate sheet with a microscope or the like. In the case of a curable laminate sheet, the thickness of the laminate sheet may be a value measured on the cured product.

[0141] [Laminate sheet with release film] In order to improve the handleability of the present laminate sheet, a laminate sheet with release film may be used in which a release film is provided on one or both sides of the present laminate sheet. The laminate sheet with release film comprises the present laminate sheet and a release film provided on one or both sides of the laminate sheet.

[0142] The release film may be a resin film whose main component is, for example, a polyolefin such as polyethylene or polypropylene, a polyester such as polyethylene terephthalate or polyethylene naphthalate, a polyimide, or a polycarbonate. The surface of these films may be coated with a silicone resin release agent or the like to adjust the peel strength.

[0143] The "main component" in a release film refers to the component that is contained in the largest amount in the release film, and specifically refers to a component that is contained in an amount of 50% by mass or more, preferably 60% by mass or more, when the total mass of the release film is 100%.

[0144] The thickness of the release film is preferably from 1 to 300 μm, more preferably from 5 to 200 μm, even more preferably from 10 to 150 μm, and even more preferably from 20 to 120 μm.

[0145] The surface of the release film that comes into contact with the laminated sheet may be subjected to a matte treatment, a corona treatment, or an antistatic treatment.

[0146] The laminate sheet with a release film may be wound around a core to form a wound body. In the wound body according to one embodiment of the present invention, the length of the laminate sheet with a release film is preferably 10 m or more, more preferably 20 m or more. When the laminate sheet with a release film has a length of 10 m or more, for example, when the laminate sheet is used as a flexible laminate or a stretchable laminate, it is possible to continuously produce electronic components, and the laminate sheet has excellent continuous film-forming properties. There is no particular upper limit to the length of the laminate sheet with a release film, but it is preferably 1000 m or less.

[0147] The material of the core is not particularly limited, but examples thereof include paper, resin-impregnated paper, acrylonitrile / butadiene / styrene copolymer (ABS resin), fiber-reinforced plastic (FRP), phenolic resin, inorganic-containing resin, etc. An adhesive may be used for the core.

[0148] [Method for Producing Laminated Sheet] Hereinafter, a method for producing the present laminated sheet will be described, but the method for producing the present laminated sheet is not limited to the following method.

[0149] (First Manufacturing Method) The first manufacturing method includes the following steps (I) and (II): (I): a film-forming step of obtaining the present resin layer from the present composition, and (II): a lamination step of laminating the present resin layer and a support layer.

[0150] (I) Film-forming step: In the film-forming step, the present composition is formed into a sheet to obtain the present resin layer. Methods for forming the present composition into a sheet include a film-forming method by coating and a film-forming method by melt extrusion.

[0151] The film-forming method by coating includes the following coating liquid preparation step and coating step. The film-forming method by coating may further include a drying step, if necessary. The film-forming method by coating is preferable in that the thermoplastic resin (A) and the radically polymerizable compound (B) are appropriately compatible with each other, and an optimal crosslinked structure is easily formed after curing, resulting in good low dielectric properties.

[0152] Coating solution preparation step: In the coating solution preparation step, the thermoplastic resin (A) and, if necessary, the radical polymerizable compound (B), the cyclic polyolefin resin copolymer (C), the organic peroxide (D), the solvent (E), and other components are stirred and mixed uniformly to obtain a coating solution. For mixing, a general mixing / stirring device such as a mixer, blender, three-roll kneader, ball mill, kneader, single-screw kneader, or twin-screw kneader can be used, and heating may be performed during mixing, if necessary.

[0153] Coating step: In the coating step, a coating liquid is applied to the surface of a release film to form a coating film. The coating method may be a common method such as a dip method, a spin coating method, a spray coating method, or a blade method. A coating device such as a spin coater, a slit coater, a die coater, or a blade coater can be used for coating, and this makes it possible to form a coating film of a predetermined thickness uniformly on the release film.

[0154] Drying step: When the coating liquid contains a solvent (E), the solvent is removed from the coating film in the drying step. The drying temperature is not particularly limited, but is usually 10 to 150°C, preferably 25 to 120°C, and more preferably 30 to 110°C. If the drying temperature is below the upper limit, the crosslinking reaction of the radically polymerizable compound (B) in the coating film is suppressed. If the drying temperature is above the lower limit, foaming of the laminate sheet is suppressed, the solvent can be effectively removed, and productivity is improved.

[0155] The drying time can be adjusted appropriately depending on the state of the coating film, the drying environment, etc. The lower limit of the drying time is preferably 1 minute or more, more preferably 2 minutes or more, even more preferably 5 minutes or more, still more preferably 10 minutes or more, particularly preferably 20 minutes or more, and most preferably 30 minutes or more. The upper limit of the drying time is preferably 4 hours or less, more preferably 3 hours or less, and even more preferably 2 hours or less. When the drying time is equal to or greater than the lower limit, the solvent can be sufficiently removed. When the drying time is equal to or less than the upper limit, productivity can be improved and production costs can be reduced. The solvent in the resin composition can be removed by a known heating method such as a hot plate, a hot air oven, an IR heating oven, a vacuum dryer, or a high-frequency heater.

[0156] From the viewpoint of preventing contamination of the surface of the laminate sheet and improving handling properties, a release film may be laminated on the laminate sheet after the drying step.

[0157] The film-forming method by melt extrusion includes a film-forming step of extruding the present composition onto a release film. The film-forming method by melt extrusion does not require the use of a solvent, and is therefore preferable in terms of cost and the likelihood of problems caused by residual solvent.

[0158] In the film-forming process by melt extrusion, the thermoplastic resin (A) and, if necessary, the radically polymerizable compound (B), the cyclic polyolefin resin copolymer (C), the organic peroxide (D), and other components are kneaded in a single-screw extruder or a twin-screw extruder. After kneading, the mixture is extruded onto a release film using an extruder or the like under temperature conditions that are equal to or higher than the melting point of the thermoplastic resin (A) and lower than the crosslinking temperature of the radically polymerizable compound (B) to form a film. The extrusion method for the resin composition is not particularly limited, but a more specific example is T-die molding.

[0159] Lamination step: In the lamination step, the present resin layer prepared in step (I) is laminated on a support layer. The lamination method is not particularly limited, and a known laminator such as a roller or a press can be used. In the coating step or melt extrusion step of step (I), a resin film that will serve as the support layer may be used instead of a release film, and the present resin layer may be formed directly on the support layer. If necessary, an adhesive may be interposed between the support layer and the present resin layer.

[0160] The lamination conditions are not particularly limited, but examples include a method of obtaining a laminated sheet by heat pressing at a pressure of 0.1 to 1 MPa for 0.5 to 10 minutes at a temperature equal to or higher than the resin flow initiation temperature of the present resin layer, cooling to room temperature, and then releasing the pressure. In this case, the present resin layer may be laminated on one side of the support layer, or on both sides of the support layer.

[0161] (Second Manufacturing Method) In the second manufacturing method, the thermoplastic resin (A) that serves as the raw material for the resin layer is melt-mixed using a single-screw extruder, twin-screw extruder, or the like. If necessary, a radically polymerizable compound (B), a cyclic polyolefin resin copolymer (C), an organic peroxide (D), and other components are used in combination. Similarly, the resin and other additives that serve as the raw materials for the support layer are melt-mixed using a single-screw extruder, twin-screw extruder, or the like. These are co-extruded using a T-die, and then quenched and solidified using a cast roll to produce a laminate sheet. When laminating the resin layer and the support layer by co-extrusion, a layer to improve adhesion between the layers may be provided as needed.

[0162] [Cured Sheet Product] The cured sheet product (hereinafter also referred to as "main cured product") is obtained by curing the above-described laminated sheet.

[0163] The curing temperature of the laminate sheet may be any temperature at which the thermoplastic resin (A) contained in the resin layer does not flow and the crosslinking reaction of the radically polymerizable compound (B) proceeds. Specifically, the temperature is preferably 120 to 300°C, more preferably 140 to 250°C, and even more preferably 150 to 220°C. The curing time of the laminate sheet is not particularly limited, but is preferably 10 minutes to 1 hour.

[0164] The thickness of the cured sheet is preferably 10 to 500 μm, more preferably 50 to 400 μm, and even more preferably 100 to 350 μm. The thickness of the cured sheet may be measured with a micrometer on the cured product obtained by heat-pressing the laminated sheet at 200°C and 2 MPa for 30 minutes, or may be calculated by observing the cross section of the cured product using a microscope or the like.

[0165] The dielectric constant, dielectric dissipation factor, storage modulus at 200°C, heat resistance temperature and linear thermal expansion coefficient of the cured sheet are the same as the dielectric constant, dielectric dissipation factor, storage modulus at 200°C, heat resistance temperature and linear thermal expansion coefficient of the above-mentioned laminate sheet after curing.

[0166] [Uses of Laminate Sheet and Cured Sheet Product] Examples of uses of the laminate sheet and the cured sheet product include, but are not limited to, copper foil laminates, stretchable substrates, flexible printed circuit boards, multilayer printed wiring boards, circuit board materials for electric and electronic devices such as capacitors, underfill materials, interchip fills for 3D-LSI, insulating sheets, vibration damping materials, adhesives, solder resists, semiconductor encapsulants, hole filling resins, and component embedding resins.

[0167] [Circuit Board Material] A circuit board material can be produced by laminating a laminate sheet according to one embodiment of the present invention with a conductor.

[0168] The conductor may be a metal foil made of a conductive metal such as copper or aluminum, or an alloy containing such a metal, or a metal layer formed by plating or sputtering.

[0169] When used as a circuit board material for electric and electronic devices, the thickness of the laminate sheet is preferably 10 μm or more and 500 μm or less, and the thickness of the conductor is preferably 0.2 μm or more and 70 μm or less.

[0170] (Method for manufacturing circuit board material) The circuit board material can be manufactured, for example, by the following method. When using laminate sheet S1, a conductor is laminated on the surface of an insulating layer made of laminate sheet S1, and a circuit is formed from the conductor to construct a circuit board. When using laminate sheet S2, laminate sheet S2 is laminated on the conductor, and then the laminate sheet is thermally cured to form an insulating layer. A conductor may be further laminated on the insulating layer, and a desired number of conductors and insulating layers may be sequentially stacked.

[0171] The curing temperature of the laminate sheet S2 may be any temperature at which the thermoplastic resin (A) of the resin layer L2 does not flow and at which the crosslinking reaction of the radically polymerizable compound (B) proceeds. The curing temperature of the laminate sheet S2 is preferably 120 to 300° C., more preferably 140 to 250° C., and even more preferably 150 to 220° C. The curing time of the laminate sheet S2 is not particularly limited, but is preferably 10 minutes to 1 hour.

[0172] The lamination of the laminate sheet and the conductor may be performed by directly overlapping a conductive metal foil such as copper foil on the laminate sheet, by bonding the laminate sheet and the conductive metal foil such as copper foil using an adhesive, by forming a conductive metal layer by plating or sputtering, or by a combination of these methods.

[0173] When laminating a conductor such as copper foil in a circuit board material, it is preferable to directly bond the two together without using an adhesive layer. Since the laminated sheet S2 is curable, by laminating the two together with the copper foil and then curing the resin layer, the two layers can function as an adhesive layer, which is preferable because the two layers can be bonded together without using an adhesive. A process of drilling holes in the insulating layer to form via holes and a process of roughening the surface of the insulating layer may be added.

[0174] The present laminate sheet may constitute either a base film or a cover film in circuit board materials. The base film is the substrate of the circuit board. The cover film is sometimes called a coverlay film, and is a film for covering and protecting conductors provided on the base film. The cover film is used by being attached to the surface of the base film or rigid substrate, which is the substrate of the circuit board, on which the conductors are laminated. The cover film may generally be attached directly to the substrate, such as the base film or rigid substrate, or may be attached via an adhesive layer.

[0175] Hereinafter, the embodiments will be described in more detail with reference to examples, but the present invention is not limited to the following description in any way.

[0176] [Raw Materials] (Thermoplastic Resin (A)) a-1: Styrene-ethylene-butadiene-styrene block copolymer (SEBS: manufactured by Asahi Kasei Corporation, "Tuftec H1052"), styrene content 20% by mass, storage modulus (24°C) = 6.2 MPa, density = 0.890 g / cm ３ a-2: Styrene-ethylene-butadiene-styrene block copolymer (SEBS: manufactured by Asahi Kasei Corporation, "Tuftec M1943"), styrene content 20% by mass, storage modulus (24 ° C) = 6.8 MPa, density = 0.900 g / cm ３

[0177] (Radical polymerizable compound (B)) b-1: triallyl isocyanurate (TAIC: manufactured by Shinryo Corporation)

[0178] (Cyclic Polyolefin Resin Copolymer (C)) c-1: cyclic polyolefin copolymer (HSEBS: Mitsubishi Chemical Corporation, "TEFABLOC CP CP402", hydrogenated aromatic vinyl polymer block unit: content of 67 mol%, hydrogenated polystyrene having a hydrogenation level of 99% or more, hydrogenated conjugated diene polymer block unit: content of 33 mol%, hydrogenated polybutadiene having a hydrogenation level of 99% or more, block structure: pentablock structure, total hydrogenation level: 99% or more, crystalline melting peak temperature: 75°C

[0179] (Organic Peroxide (D)) d-1: α,α-di(tert-butylperoxyisopropyl)benzene (manufactured by NOF Corporation)

[0180] (Solvent (E)) e-1: toluene (content: >99.0% by mass)

[0181] (Inorganic particles (F)) f-1: Micromica ("MK-200" manufactured by Katakura Co-op Agri Co., Ltd.), average particle size (D50): 5 to 7 μm

[0182] (Resin layer) x-1: The raw materials were blended in the proportions shown in Table 1, heated to about 80 ° C, and the raw materials were completely dissolved to prepare a resin composition. The resin composition was coated on the release-treated surface of a 50 μm-thick release film (PET film manufactured by Mitsubishi Chemical Corporation) and dried in an oven at 100 ° C for 10 minutes. Then, a separately prepared release film (PET film manufactured by Mitsubishi Chemical Corporation) was attached so that the release-treated surface matched the coated surface, thereby obtaining a resin layer x-1 with a release film laminated on both sides. x-2, x-3: Resin layers x-2 and x-3 with a release film laminated on both sides were obtained in the same manner as x-1, except that the raw materials were blended according to the proportions shown in Table 1.

[0183]

[0184] (Support layer) y-1: Ultra-low CTE polyimide film (manufactured by Xenomax Japan, CTE: <5 ppm / °C, storage modulus (24°C): 1000 MPa, Dk (10 GHz): 3.8, Df (10 GHz): 0.006) y-2: Polyimide film (manufactured by DuPont, CTE: 15 ppm / °C, storage modulus (24°C): 5700 MPa, Dk (10 GHz): 3.7, Df (10 GHz): 0.007)

[0185] [Measurement Method] (Dielectric Properties: Dk, Df) The in-plane dielectric constant (Dk0) and dielectric loss tangent (Df0) of the cured laminate sheet and the comparative single-layer sheet were measured. The in-plane dielectric constant (Dk0) and dielectric loss tangent (Df0) were measured in TE mode using a cavity resonator (manufactured by AET) and a network analyzer MS46 122B (manufactured by Anritsu). The measurement was performed at a frequency of 10 GHz in an environment of 23°C and 50% RH.

[0186] Separately, the cured laminate sheet and the comparative single-layer sheet were stored for three days in an environment of 85°C and 85% RH. Immediately after storage, the in-plane dielectric constant (Dk1) and dielectric loss tangent (Df1) were measured under the same conditions as the dielectric constant (Dk0) and dielectric loss tangent (Df0). The difference (ΔDf) between the initial dielectric loss tangent (Df0) and the dielectric loss tangent (Df1) immediately after three days of storage in an environment of 85°C and 85% RH was calculated. The results are shown in Table 2. When the ΔDf value was less than 0.0001, it was indicated as "<0.0001" in the table. The smaller the ΔDf value, the more stable the product is to environmental changes in temperature and humidity.

[0187] (Coefficient of linear thermal expansion: CTE) The coefficient of linear thermal expansion of the cured laminate sheet and the single-layer sheet of the comparative example was measured by thermomechanical analysis according to JIS K7197 (2012). Specifically, using a thermal analyzer "TMA 841" (manufactured by Mettler Toledo), the sample shape was 5 mm wide x 16 mm long, and the measurement was started from 30 ° C., heated to 100 ° C. at a rate of 5 ° C. / min, cooled to 0 ° C., and then reheated to 150 ° C. The dimensional change during the reheating process was measured, and based on this result, the average value of the thermal expansion coefficient in the in-plane direction from 0 to 120 ° C. was calculated.

[0188] (Copper Foil Adhesion) The release films on the outermost surfaces of the uncured laminate or uncured resin layer x-1 were peeled off from both sides. The uncured laminate was then bonded to the roughened surface of a low-roughness electrolytic copper foil ("CF-T4X-SV" manufactured by Fukuda Metals Co., Ltd.) with a surface roughness (Rz) of 1.0 μm. An uncured copper foil laminate consisting of copper foil / resin layer / support layer / resin layer / copper foil or copper foil / resin layer / copper foil was prepared. The uncured copper foil laminate was sandwiched between flat metal plates and subjected to a heat press treatment at 200°C for 30 minutes, adjusting the pressure applied to the resin layer to 2 MPa. A cured copper foil laminate with a cured resin layer was obtained. A test piece measuring 1 cm wide x 10 cm long was cut from the cured copper foil laminate. The peel strength at the interface between the copper foil and the resin layer of the test piece was measured using a universal testing machine "AG-X plus" (manufactured by Shimadzu Corporation) under the following conditions. The average value of the 2 cm section where stable peeling was possible was calculated as the adhesive strength to the copper foil. The adhesive strength measurement conditions were as follows:

[0189] Peeling angle: 180 degrees Temperature: room temperature Peeling speed: 50 mm / min

[0190] (Storage Modulus) The dynamic viscoelasticity of the cured laminate sheet and single-layer sheet was measured under the following conditions using a viscoelasticity spectrometer DVA-200 (manufactured by IT Measurement Control Co., Ltd.). From the measurement results, the storage modulus at 24°C was calculated. The measurement conditions for the storage modulus were as follows:

[0191] Vibration frequency: 10 Hz Distortion: 0.1% Heating rate: 3°C / min Measurement temperature: -100°C to 300°C

[0192] (Solder Heat Resistance Test) Cured laminate sheets and single-layer sheets cut into 2 cm squares were immersed in a molten solder bath at 300°C for 1 minute, and the change in state was observed. The laminate sheets were then visually inspected and evaluated according to the following criteria: A: No deformation, resin outflow, blistering, or peeling was observed in the laminate sheet (good). B: Significant deformation, resin outflow, or blistering or peeling was observed in the laminate sheet (poor).

[0193] Example 1: A 25 μm-thick resin layer x-1, from which the release film on one side had been peeled off, was bonded to both sides of a 5 μm-thick support layer y-1, with the release surface facing the support layer surface, to obtain an uncured laminate. The laminate was used to evaluate adhesion to copper foil. The laminate was then sandwiched between flat metal plates and heat-pressed at 200°C for 30 minutes under a pressure of 2 MPa to cure the resin layer. The release film on the outermost surface of the cured resin layer laminate was peeled off to obtain a laminate sheet consisting of a resin layer / support layer / resin layer. The dielectric properties, linear thermal expansion coefficient, and storage modulus of the obtained cured laminate sheet were measured, and a heat resistance test was also performed.

[0194] [Examples 2 to 6, Comparative Example 2] Uncured laminates were prepared in the same manner as in Example 1, except that the resin layers and support layers shown in Table 2 were bonded together according to the thickness configurations shown. Adhesion to copper foil was evaluated in the same manner as in Example 1. The laminate was then sandwiched between flat metal plates, and the resin layer was cured by heat pressing at 200°C for 30 minutes under a pressure of 2 MPa. The release film on the outermost surface of the laminate with the cured resin layer was peeled off to obtain a laminate sheet consisting of a resin layer / support layer / resin layer. The dielectric properties, linear thermal expansion coefficient, and storage modulus of the obtained cured laminate sheet were measured, and a heat resistance test was also performed.

[0195] [Comparative Example 1] In Comparative Example 1, a resin layer x-1 of approximately 200 μm was prepared. The resin layer x-1 was evaluated for adhesion to copper foil using the same method as in Example 1. Furthermore, the resin layer x-1 was sandwiched between metal plates without being bonded to the support layer (Y), and cured by heat pressing at 200°C for 30 minutes under a pressure of 2 MPa. The release films on both sides were peeled off to obtain a single-layer sheet of the resin layer x-1. The dielectric properties, linear thermal expansion coefficient, and storage modulus of the obtained cured single-layer sheet were measured, and a heat resistance test was also performed.

[0196]

[0197] The results of Examples 1 to 6 demonstrated that bonding a resin layer (X) and a support layer (Y) together provided low dielectric properties, good copper foil adhesion, and excellent solder heat resistance, while also imparting low CTE properties similar to those of conductors such as copper. In contrast, Comparative Example 1, in which the support layer (Y) was not laminated, exhibited low dielectric properties, good copper foil adhesion, and excellent solder heat resistance, but had an extremely large CTE of 200 ppm / °C or more. When used in combination with a conductor and subjected to heat, there was concern that distortion or peeling could occur due to the difference in CTE with the conductor. In Comparative Example 2, the ratio (Y / (X+Y)) of the thickness of the support layer (Y) to the total thickness (X+Y) of the laminate sheet was greater than 0.40. At this time, the dielectric loss tangent deteriorated. Example 1 and Comparative Example 2 are compared. The resin layer and support layer are the same in Example 1 and Comparative Example 2. In this case, it was confirmed that Comparative Example 2, in which the ratio (Y / (X+Y)) of the thickness of the support layer (Y) to the total thickness (X+Y) of the laminate sheet was high, had a larger change in dielectric properties after the moist heat test and was inferior in environmental stability.

[0198] While the present invention has been described above with reference to specific embodiments, these embodiments are presented as examples and do not limit the scope of the present invention. Each embodiment described in this specification can be modified in various ways within the scope of the effects of the invention, and can be combined with features described in other embodiments within the scope of feasibility.

[0199] According to the present invention, it is possible to obtain a laminated sheet, a cured sheet, and a circuit board material having low dielectric properties and excellent heat resistance, which have low dielectric properties, excellent conductor adhesion, a low coefficient of linear thermal expansion, and which stably exhibit low dielectric properties even when subjected to temperature and humidity changes due to the usage environment.

[0200] 1 Support layer 2 Resin layer

Claims

1. A laminate sheet comprising a support layer and at least two or more resin layers provided on both sides of the support layer, wherein the support layer contains at least one resin selected from the group consisting of polyimide resins, cyclic olefin resins, liquid crystal polymers, and polyamide resins, and the resin layers contain at least one thermoplastic resin (A) selected from the group consisting of styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, and ethylene-based polymers, and the laminate sheet satisfies the following formula (Z1): Y / (X+Y)≦0.40 ... formula (Z1) In formula (Z1), X is the thickness of the resin layer in the laminate sheet, and Y is the thickness of the support layer in the laminate sheet.

2. The laminate sheet according to claim 1, wherein the dielectric loss tangent at 10 GHz is 0.0060 or less.

3. The laminate sheet according to claim 1, having a storage modulus at 24°C of 10 MPa or more.

4. The laminate sheet according to claim 1, having a linear thermal expansion coefficient of 60 ppm / °C or less.

5. A laminate sheet comprising a support layer and at least two or more resin layers provided on both sides of the support layer, wherein the support layer contains at least one resin selected from the group consisting of polyimide resins, cyclic olefin resins, liquid crystal polymers, and polyamide resins, and the resin layer contains at least one thermoplastic resin (A) selected from the group consisting of styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, and ethylene-based polymers, and a radically polymerizable compound (B) having two or more ethylenically unsaturated bonds in the molecule, and which satisfies the following formula (Z1): Y / (X+Y)≦0.40 ... formula (Z1) In formula (Z1), X is the thickness of the resin layer in the laminate sheet, and Y is the thickness of the support layer in the laminate sheet.

6. The laminate sheet according to claim 5, wherein the resin layer contains, as the radical polymerizable compound (B), at least one compound selected from the group consisting of bifunctional aromatic vinyl compounds and trialkenyl isocyanurate compounds.

7. The laminate sheet according to claim 5, wherein the radical polymerizable compound (B) is a compound having no polar functional group in the molecule.

8. The laminate sheet according to claim 5, wherein the polar functional group equivalent of the radical polymerizable compound (B) is at least 2. The polar functional group equivalent is the ratio of the molecular weight of the radical polymerizable compound (B) to the molecular weight of the polar functional group of the radical polymerizable compound (B).

9. The laminate sheet according to claim 5, wherein the content of the radical polymerizable compound (B) is 1 part by mass or more and less than 50 parts by mass per 100 parts by mass of the thermoplastic resin (A).

10. The laminate sheet according to claim 5, wherein the storage modulus of the resin layer when cured by applying a pressure of 2 MPa for 30 minutes at a temperature of 200°C is 1 to 7000 MPa.

11. The laminate sheet according to claim 5, wherein the resin layer is cured by applying a pressure of 2 MPa for 30 minutes at a temperature of 200°C, and the relative dielectric constant at 10 GHz is 1.0 to 4.0 and the dielectric dissipation factor is 0.0001 to 0.0060.

12. The laminate sheet according to claim 5, wherein the resin layer has a linear thermal expansion coefficient of 60 ppm / °C or less when the resin layer is cured by applying a pressure of 2 MPa for 30 minutes at a temperature of 200°C.

13. A cured sheet obtained by curing the laminated sheet according to any one of claims 5 to 12.

14. A laminate sheet according to claim 1 or 5, wherein the content of the thermoplastic resin (A) is 60 mass % or more of the resin components of the resin layer.

15. A laminate sheet according to claim 1 or 5, wherein the resin layer contains a styrene-based thermoplastic elastomer as the thermoplastic resin (A).

16. The laminate sheet according to claim 15, wherein the styrene content of the styrene-based thermoplastic elastomer is 10% by mass or more and 70% by mass or less.

17. The laminate sheet according to claim 1, wherein the resin layer further contains a cyclic polyolefin resin copolymer (C).

18. The laminate sheet according to claim 17, wherein the cyclic polyolefin resin copolymer (C) is a copolymer having an alicyclic structure in the side chain of the polyolefin.

19. A laminate sheet according to claim 1 or 5, wherein the content of the thermoplastic resin (A) is more than 50% by mass of the total mass of the resin layer.

20. The laminate sheet according to claim 1 or 5, which satisfies the following formula (Z2): Y / (X+Y)≦0.20 ... formula (Z2) In formula (Z2), X is the thickness of the resin layer in the laminate sheet, and Y is the thickness of the support layer in the laminate sheet.

21. A laminate sheet with a release film, comprising: the laminate sheet according to claim 1 or 5; and a release film provided on one or both surfaces of the laminate sheet.

22. A circuit board material comprising an insulating layer made of the laminated sheet according to claim 1 or 5 and a conductor laminated together.

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